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Basic guidlines for designing of a power plant

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Design power plant Design power plant Document Transcript

  • TM 5-811-6 TECHNICAL MANUAL ELECTRIC POWER PLANT DESIGNHEADQUARTERS, DEPARTMENT OF THE ARMY 20 JANUARY 1984
  • TM 5-811-6 REPRODUCTION AUTHORIZATION/RESTRICTIONSThis manual has been prepared by or for the Government and, except to the extent indicated below, is publicproperty and not subject to copyright.Copyrighted material included in the manual has been used with the knowledge and permission of the proprie-tors and is acknowledged as such at point of use. Anyone wishing to make further use of any copyrighted ma-terial, by itself and apart from this text, should seek necessary permission directly from the proprietors.Reprints or republications of this manual should include a credit substantially as follows: “Department of theArmy, USA, Technical Manual TM 5-811-6, Electric Power Plant Design.If the reprint or republication includes copyrighted material, the credit should also state: “Anyone wishing tomake further use of copyrighted material, by itself and apart from this text, should seek necessary permissiondirectly from the proprietors. ” A/(B blank)
  • TM 5-811-6T ECHNICAL M A N U A L HEADQUARTERS DEPARTMENT OF THE ARMYNO. 5-811-6 W ASHINGTON , DC 20 January 1984 ELECTRIC POWER PLANT DESIGN Paragraph PageCHAPTER 1. INTRODUCTION Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1-1 Design philosophy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1-1 Design criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 1-1 Economic considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 1-5CHAPTER 2. SITE AND CIVIL FACILITIES DESIGN Selection I. Site Selection Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2-1 Environmental considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2-1 Water supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 2-1 Fuel supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 2-1 Physical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 2-1 Economic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6 2-1 Section II. Civil Facilities, Buildings, Safety, and Security Soils investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 2-2 Site development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8 2-2 Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 2-2CHAPTER 3. STEAM TURBINE POWER PLANT DESIGN Section I. Typical Plants and Cycles Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3-1 Plant function and purpose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 3-1 Steam power cycle economy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3-1 Cogeneration cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4 3-3 Selection of cycle steam conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 3-6 Cycle equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6 3-6 Steam power plant arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 3-6 Section II. Steam Generators and Auxiliary Systems Steam generator convention types and characteristics . . . . . . . . . . . . . . . . . . . . . . . . 3-8 3-9 Other steam generator characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9 3-11 Steam generator special types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10 3-12 Major auxiliary systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11 3-12 Minor auxiliary systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12 3-25 Section III. Fuel Handling and Storage Systems Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13 3-26 Typical fuel oil storage and handling system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14 3-26 Coal handling and storage systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15 3-27 Section IV. Ash Handling Systems Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-16 3-29 Description of major components.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17 3-30 Section V. Turbines and Auxiliary Systems Turbine prime movers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-18 3-30 Generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19 3-32 Turbine features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-20 3-32 Governing and control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21 3-33 Turning gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-22 3-33 Lubrication systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-23 3-33 Extraction features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-24 3-34 Instruments and special tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-25 3-34 Section VI. Condenser and Circulating Water System Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26 3-34 Description of major components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27 3-35 Environmental concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-28 3-40 Section VII. Feedwater System Feedwater heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-29 3-40 Boiler feed pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-30 3-41 Feedwater supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-31 3-43 Section VIII. Service Water and Closed Cooling Systems Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-32 3-43 Description of major components.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-33 3-44 i
  • TM 5-811-6 Paragraph PageC HAPTER 3. STEAM TURBINE POWER PLANT DESIGN (Continued) Description of systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-34 3-44 Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-35 3-45 Reliability of systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-36 3-45 Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-37 3-45 Section IX. Water Conditioning Systems Water conditioning selection.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-38 3-45 Section X. Compressed Air Systems Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-39 3-46 Description of major components.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-40 3-46 Description of systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-41 3-50C HAPTER 4. GENERATOR AND ELECTRICAL FACILITIES DESIGN Section I. Typical Voltage Ratings and Systems Voltages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 -1 Station service power syetems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 4-1 Section II. Generators General types and standards.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3 4-3 Features and acceesories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4 4-7 Excitation systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 4-8 Section III. Generator Leads and Switchyard General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6 4-8 Generator leads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7 4-9 Switchyard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8 4-13 Section IV. Transformers Generator stepup transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9 4-16 Auxiliary transformers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10 4-16 Unit substation transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11 4-17 Section V. Protective Relays and Metering Generator, stepup transformer and switchyard relaying . . . . . . . . . . . . . . . . . . . . . . . 4-12 4-18 Switchgear and MCC protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13 4-19 Instrumentation and metering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14 4-19 Section VI. Station Service Power Systems General requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15 4-20 Auxiliary power transformers. . . . . . . . . . . . . . . . . . . . . . . . ...’. . . . . . . . . . . . . . . . . 4-16 4-20 4160 volt switchgear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17 4-20 480 volt unit substations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-18 4-21 480 volt motor control centers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-19 4-21 Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20 4-21 Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-21 4-21 Conduit and tray systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-22 4-21 Distribution outside the power plant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-23 4-22 Section VII. Emergency Power System Battery and charger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-24 4-23 Emergency ac system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-25 4-23 Section VIII. Motors General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-26 4-23 Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-27 4-24 Horsepower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-28 4-24 Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-29 4-24 Conduit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-30 4-24 Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-31 4-24 Motor details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-32 4-24 Section IX. Communication Systems Intraplant communications.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-33 4-24 Telephone communications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-34 4-26C HAPTER 5. GENERAL POWER PLANT FACILITIES DESIGN Section I. Instruments and Control Systems General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 5-1 Control panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 5-1 Automatic control systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3 5-5 Monitoring instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4 5-9 Alarm and annunciator systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5 5-14 Section II. Heating, Ventilating and Air Conditioning Systems Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6 5-14 Operations areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7 5-14 Service areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8 5-14ii
  • TM 5-811-6 Paragraph Page CHAPTER 5. GENERAL POWER PLANT FACILITIES DESIGN (Continued) Section 111. Power and Service Piping Systems Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9 5-15 Piping design fundamentals... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10 5-15 Specific system design considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11 5-15 Section IV. Thermal Insulation and Freeze Protection Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12 5-17 Insulation design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13 5-17 Insulation materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-14 5-17 Control of useful heat losses.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15 5-21 Safety insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16 5-21 Cold surface insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-17 5-21 Economic thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18 5-21 Freeze protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-19 5-21 Section V. Corrosion Protection General remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20 5-22. Section VI. Fire Protection Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21 5-22 Design considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-22 5-23 Support facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-23 5-24 CHAPTER 6. GASTURBINE POWER PLANT DESIGN General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 6-1 Turbine-generator selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2 6-1 Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3 6-2 Plant arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4 6-2 Waste heat recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5 6-2 Equipment and auxiliary systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6 6-3 C HAPTER 7. DIESEL ENGINE POWER PLANT DESIGN Section I. Diesel Engine Generators Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 7-1 Fuel selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2 7-1 Section II. Balance of Plant SystemsL 7-3 7-2 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cooling systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4 7-2 Combustion air intake and exhaust systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5 7-2 Fuel storage and handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6 7-2 Engine room ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7 7-2 Section III. Foundations and Building General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8 7-3 Engine foundation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9 7-3 Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10 7-3. C HAPTRR 8. COMBINED CYCLE POWER PLANTS Section I. Typical Plants and Cycles Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1 8-1 Plant details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2 8-1. Section II. General Design Parameters Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3 8-1 Design approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4 8-2 APPENDIX A: REFERENCES BIBLIOGRAPHY LIST OF FiGURES Figure No. Page Figure 1-1 Typical Metropolitan Area Load Curves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 1-2 Typical Annual Load Duration Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5 3-1 Typical Straight Condensing Cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 3-2 Turbine Efficiencies Vs.Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3-3 Typical Condensing–Controlled Extraction Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 3-4 Typical Smal1 2-Unit Power Plant "A” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 3-5 Typical Smal1 2-Unit Power Plant “B’’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8 3-6 Critical Turbine Room Bay and Power Plant "B’’Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9 3-7 Fluidized Bed Combustion Boiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13 3-8 Theorectical Air and Combustion Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15 3-9 Minimum Metal Temperatures for Boiler Heat Recovery Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-16
  • TM 5-811-6 Page 3-10 Coal Handling System Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26 3-11 Typical Coal Handling System for Spreader Stoker Fired Boiler (with bucket elevator). . . . . . . . . . . . . . . . . . . 3-28 3-12 Pneumatic Ash Handling Systems-Variations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-31 3-13 Types of Circulating Water Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-38 3-14 Typical Compressed Air System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-50 3-15 Typical Arrangement of Air Compressor and Acceesories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-51 4-1 Station Connections–Two Unit Station Common Bus Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 4-2 Station Connections–Two Unit Station–Unit Arrangment–Generator at Distribution Voltage. . . . . . . . . . 4-4 4-3 Station Connections–Two Unit Station–Unit Arrangement–Distribution Voltage Higher Than Genera- tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 4-4 One Lone Diagram-TypicalStation Service Power System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6 4-5 Typical Synchronizing Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9 4-6 Typical Main and TransferBus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10 4-7 Typical Ring Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11 4-8 Typical Breaker and a Half Bus.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12 5-1 Economical Thickness of Heat Insulation (Typical Curves) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-22 6-1 Typical Indoor Simple Cycle Gas Turbine Generator PowerPlant.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3 7-1 Typical Diesel Generator Power Plant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4 8-1 Combined Cycle Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3 LIST OF TABLESTable No. PageTable 1-1 General Description of Type of Plant.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1-2 Diesel Class and Operational Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 1-3 Plant Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 1-4 Deeign Criteria Requirements.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 3-1 Theoretical Steam Rates for Typical Steam Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4 3-2 Fuel Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10 3-3 Indivdual Burner Turndown Ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14 3-4 Emission Levels Allowable, National Ambient Air Quality Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17 3-5 Uncontrolled Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-18 3-6 Characteristics of Cyclones for Particulate Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19 3-7 Characteristics of Scrubbers for Particulate Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-20 3-8 Characterietics of Electrostatic Precipitators (ESP) for Particulate Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21 3-9 Characteristics of Baghouses for Particulate Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-22 3-10 Characteristics of Flue-Gas Desulfurization Systems for Particulate Control. . . . . . . . . . . . . . . . . . . . . . . . . . . 3-23 3-11 Techniques for Nitrogen Oxide Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-24 3-12 Condenser Tube Design Velocities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-36 3-13 General Guide for Raw Water Treatment of Boiler Makeup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-47 3-14 Internal Chemical Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-48 3-15 Effectiveness of Water Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-49 4-1 Standard Motor Control Center Enclosures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-22 4-2 Suggested Locations for Intraplant Communication System Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-25 5-1 List of Typical Instrumente and Devices for Boiler-Turbine Mechanical Panel. . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 5-2 List of Typical Instrument and Devices for Common Services Mechanical Panel. . . . . . . . . . . . . . . . . . . . . . . 5-4 5-3 List of Typical Instruments and Devices for Electrical (Generator and Switchgear) Panel . . . . . . . . . . . . . . . . 5-6 5-4 List of Typical Instrument and Devices for Diesel Mechanical Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8 5-5 Sensing Elements for Controls and Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10 5-6 Piping Codes and Standards for Power Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16 5-7 Characteristics of Thermal Insulations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18iv
  • TM 5-811-6 CHAPTER 1 INTRODUCTION1-1. Purpose 1-3. Design criteria a. General: This manual provides engineering a. General requirements. The design will providedata and criteria for designing electric power plants for a power plant which has the capacity to providewhere the size and characteristics of the electric the quantity and type of electric power, steam andpower load and the economics of the particular facil- compressed air required. Many of the requirementsit y justify on-site generation. Maximum size of discussed here are not applicable to each of the plantplant considered in this manual is 30,000 kW. categories of Table 1-1. A general overview is pro- b. References: A list of references used in this vided in Table 1-4.manual is contained in Appendix A. Additionally, a b. Electric power loads. The following informa-Bibliography is included identifying sources of ma- tion, as applicable, is required for design:terial related to this document. (1) Forecast of annual diversified peak load to be served by the project. 1-2. Design philosophy (2) Typical seasonal and daily load curves and a. General. Electric power plants fall into several load duration curves of the load to be served. Ex- categories and classes depending on the type of ample curves are shown in Figures 1-1 and 1-2. prime mover. Table 1-1 provides a general descrip- (3) If the plant is to operate interconnected with tion of plant type and related capacity require- the local utility company, the designer will need in-ments. For purposes of this introduction Table 1-2 formation such as capacity, rates, metering, and in- defines, in more detail, the diesel plant classes and terface switchgear requirements. operational characteristics; additional information (4) If the plant is to operate in parallel withis provided in Chapter 7. No similar categories have existing generation on the base, the designer willbeen developed for gas turbines. Finally, for pur- also need:poses of this manual and to provide a quick scale for (a) An inventory of major existing generation the plants under review here, several categories equipment giving principal characteristics such ashave been developed. These are shown in Table 1-3. capacities, voltages, steam characteristics, back b. Reliability. Plant reliability standards will be pressures, and like parameters.equivalent to a l-day generation forced outage in 10 (b) Incremental heat rates of existing boiler-years with equipment quality and redundancy se- turbine units, diesel generators, and combustionlected during plant design to conform to this stand- turbine generator units.ard. (c) Historical operating data for each existing c. Maintenance. Power plant arrangement will generating unit giving energy generated, fuel con-permit reasonable access for operation and mainte- sumption, steam exported, and other related infor-nance of equipment. Careful attention will be given mation.to the arrangement of equipment, valves, mechan- (5) Existing or recommended distribution vol-ical specialties, and electrical devices so that rotors, tage, generator voltage, and interconnecting substa-tube bundles, inner valves, top works, strainers, tion voltages.contractors, relays, and like items can be maintained (6) If any of the above data as required for per-or replaced. Adequate platforms, stairs, handrails, forming the detailed design is unavailable, the de-and kickplates will be provided so that operators signer will develop this data.and maintenance personnel can function conven- c. Exports team loads.iently and safely. (1) General requirements. If the plant will ex- d. Future expansion. The specific site selected for port steam, information similar to that required forthe power plant and the physical arrangement of the electric power, as outlined in subparagraph c above,plant equipment, building, and support facilities will be needed by the designer.such as coal and ash handling systems, coal storage, (2) Coordination of steam and electric powercirculating water system, trackage, and access loads. To the greatest extent possible, peak, season-roads will be arranged insofar as practicable to allow al, and daily loads for steam will be coordinated withfor future expansion. the electric power loads according to time of use. 1-1
  • Table 1-1. General Description of Type of Plant. TYPE OF POWERCategory Capacity No Export Steam With Export SteamPrimary Adequate to meet all peacetime Purchased electric power to match Purchased electric power and steam to requirement. electric load. match electric load plus supplementary boiler plant to match export steam load. Continuous duty diesel plant, Automatic back pressure steam plant plus Class “A” diesel. automatic packaged firetube boiler to supplement requirements of export steam load. Straight condensing boilers and Automatic extraction steam plant boilers and turbines matched in capacity and turbines matched in capacity se units as units; enough units so plant and enough units installed so that plant without largest unit can carry without largest unit can carry emergency emergency load. load.Standby Adequate with prime source to match Purchased electric power. Purchased electric power and steam to mobilization needs; or alone to supply match electric power load plus supple- emergency electric load and export mentary boiler plant. steam load in case of primary source Standby diesel plant, Class “B” Standby diesel plant with supplementary out age. diesel. boiler plant. Equal to primary source . . . . . . . . . . . . Retired straight condensing plant. Retired automatic extraction steam plant.Emergency To supply that part of emergency load Fixed emergency diesel plant, None. that cannot be interrupted for m o r e Class “C” diesel. than 4 hours. Mobile utilities support equipment. None. NAVFAC DM3
  • TM 5-811-6 Table 1-2. Diesel Class and Operational Characteristics. Fu1l Load Rating Capability Expected Operating Hours Minimum OperatingClass— Usage —Hours - Period — — First Ten Years " A " . . . . . . . . . Continuous . . . . . . . 8,000 . . . . . Yearly . . . . . . . 4,000 hours plus . . . . . 40,000 hours plus “B” . . . . . . . . . Standby . . . . . . . . . . 8,000 . . . . . Yearly . . . . . . . 1,000 to 4,000 hours . 20,000 to 40,000 hours “c” . . . . . . . . . Emergency . . . . . . . . 650 . . . . . Monthly* . . . . . Under 1,000 hours . . . . Under 10,000 hours*Based on a 30-day month. U.S. Army Corps of Engineers Table-3. Plant Sizes. Category S i z e Small o to 2,500 kW Medium 2,500 kW to 10,000 kW Large 10,000 kW to 30,000 kW U.S. Army Corps of Engineers Table-4. Design Criteria Requirements. Fuel Electric Export Source Class Power St earn and Water Stack Waste (Plant Category) Loads Loads Cost Supply Emission Disposal A A A A A A (Primary) A A A A B (Standby) N/A N/A N/A C (Emergency) critical N/A A N/A N/A N /A loads only A= Applicable = N/A Not Applicable Courtesy of Pope, Evans and Robbins (Non-Copyrighted) 1-3
  • TM 5-811-6This type of information is particularly important if will be designed for the type of stack gas cleanupthe project involves cogeneration with the simul- equipment which meets federal, state, and munici-taneous production of electric power and steam. pal emission requirements. For a solid fuel fired boil- d. Fuel source, and cost. The type, availability, er, this will involve an electrostatic precipitator orand cost of fuel will be determined in the early bag house for particulate, and a scrubber for sulfurstages of design; taking into account regulatory re- compounds unless fluidized bed combustion or com-quirements that may affect fuel and fuel characteris- pliance coal is employed. If design is based on com-tics of the plant. pliance coal, the design will include space and other e. Water supply. Fresh water is required for required provision for the installation of scrubberthermal cycle makeup and for cooling tower or cool- equipment. Boiler design will be specified as re-ing pond makeup where once through water for heat quired for NOx control.rejection is unavailable or not usable because of g. Waste disposal.regulatory constraints. Quantity of makeup will (1) Internal combustion plants. Solid and liq-vary with the type of thermal cycle, amount of con- uid wastes from a diesel or combustion turbine gen-densate return for any export steam, and the maxi- erating station will be disposed of as follows: Mis-mum heat rejection from the cycle. This heat rejec- cellaneous oily wastes from storage tank areas andtion load usually will comprise the largest part of sumps will be directed to an API separator. Supple-the makeup and will have the least stringent re- mentary treating can be utilized if necessary to meetquirements for quality. the applicable requirements for waste water dis- f. Stack emissions. A steam electric power plant charge. For plants of size less than 1,000 kW, liquid . URBAN ----- Sumner Load [NDUSTRIAL TRACTION Winter Load LOAD LOAD Kw 1 12612612612612612612 AM PM AM PM AM PM FROM POWER STATION ENGINEERING AND ECONOMY BY SROTZKI AND LOPAT. COPYRIGHT © BY THE MC GRAW-HILL BOOK COMPANY, INC. USED WITH THE PERMISSION OF MC GRAW-HILL BOOK COMPANY. Figure 1-1. Typical metropolitan area load curves.1-4
  • TM 5-811-6 oily wastes will be accumulated in sumps or small the style of surrounding buildings. Any anticipated tanks for removal. Residues from filters and centri- noise or aesthetics problem will be resolved prior tofuges will be similarly handled. the time that final site selection is approved. (2) Steam electric stations. For steam electricgenerating stations utilizing solid fuel, both solid 1-4. Economic considerationsand liquid wastes will be handled and disposed of in a. The selection of one particular type of designan environmentally acceptable manner. The wastes for a given application, when two or more types ofcan be categorized generally as follows: design are known to be feasible, will be based on the (a) Solid wastes. These include both bottom results of an economic study in accordance with theash and fly ash from boilers. requirements of DOD 4270.1-M and the National (b) Liquid wastes. These include boiler blow- Energy Conservation Policy Act (Public Lawdown, cooling tower blowdown, acid and caustic 95-619,9 NOV 1978).water treating wastes, coal pile runoff, and various b. Standards for economic studies are containedcontaminated wastes from chemical storage areas, in AR 11-28 and AFR 178-1, respectively. Addi-sanitary sewage and yard areas. tional standards for design applications dealing h. Other environmental considerations. Other en- with energy/fuel consuming elements of a facilityvironmental considerations include noise control are contained in the US Code of Federal Regula-and aesthetic treatment of the project. The final lo- tions, 20 CFR 436A. Clarification of the basic stand-cation of the project within the site area will be re- ards and guidelines for a particular application andviewed in relation to its proximity to hospital and supplementary standards which may be required foroffice areas and the civilian neighborhood, if appli- special cases may be obtained through normal chan-cable. Also, the general architectural design will be nels from HQDA (DAEN-ECE-D), WASH DCreviewed in terms of coordination and blending with 20314. I I 0 1000 2000 3000 4000 5000 6000 7000 8000 8760- — HOURS U.S. Army Corps of Engineers Figure 1-2. Typical annual load duration curve. 1-5
  • -
  • TM 5-811-6 CHAPTER 2 SITE AND CIVIL FACILITIES DESIGN Section 1. SITE SELECTION2-1. Introduction tain a permit required to discharge heated water toSince the selection of a plant site has a significant the source.influence on the design, construction and operating (2) Maximum allowable temperature rise per-costs of a power plant, each potential plant site will missible as compared to system design parameters.be evaluated to determine which is the most If system design temperature rise exceeds permissi-economically feasible for the type of power plant be- ble rise, a supplemental cooling system (coolinging considered. tower or spray pond) must be incorporated into the design.2-2. Environmental considerations (3) Maximum allowable temperature for river a. Rules and regulations. All power plant design, or lake after mixing of cooling system effluent withregardless of the type of power plant, must be in ac- source. If mixed temperature is higher than allow-cordance with the rules and regulations which have able temperature, a supplemental cooling systembeen established by Federal, state and local govern- must be added. It is possible to meet the conditionsmental bodies. of (2) above and not meet the conditions in this sub- b. Extraordinary design features. To meet var- paragraph.ious environmental regulations, it is often necessary (4) If extensive or repetitive dredging of wat-to utilize design features that will greatly increase erway will be necessary for plant operations.the cost of the power plant without increasing its ef- (5) The historical maximum and minimumficiency. For example, the cost of the pollution con- water level and flow readings. Check to see that ade-trol equipment that will be required for each site un- quate water supply is available at minimum flowder consideration is one such item which must be and if site will flood at high level.carefully evaluated. 2-4. Fuel supply 2-3. Water supply Site selection will take into consideration fuel stor- a. General requirements. Water supply will be age and the ingress and egress of fuel delivery equip-adequate to meet present and future plant require- ment.ments. The supply maybe available from a local mu-nicipal or privately owned system, or it may be nec- 2-5. Physical characteristicsessary to utilize surface or subsurface sources. Selection of the site will be based on the availability b. Quality. Water quality and type of treatment of usable land for the plant, including yard struc-required will be compatible with the type of power tures, fuel handling facilities, and any future expan-plant to be built. sion. Other considerations that will be taken into ac- c. Water rights. If water rights are required, it will count in site selection are:be necessary to insure that an agreement for water -Soil information.rights provides sufficient quantity for present and -Site drainage.future use. - Wind data. d. Water wells. If the makeup to the closed sys- -Seismic zone.tem is from water wells, a study to determine water -Ingress and egress.table information and well drawdown will be re- For economic purposes and operational efficiency,quired. If this information is not available, test well the plant site will be located as close to the load cen-studies must be made. ter as environmental conditions permit. e. Once-through system. If the plant has a oncethrough cooling system, the following will be deter- 2-6. Economicsmined: Where the choice of several sites exists, the final se- (1) The limitations established by the appro- lection will be based on economics and engineeringpriate regulatory bodies which must be met to ob- studies. 2-1
  • . TM 5-811-6 Section Il. CIVIL FACILITIES, BUILDINGS, SAFETY, AND SECURITY 2-7. Soils investigation -Trucks for removal of ash, sludge and other An analysis of existing soils conditions will be made waste materials. to determine the proper type of foundation. Soils (2) Roadway material and width. Aside from data will include elevation of each boring, water temporary construction roads, the last two catego- table level, description of soil strata including the ries described above will govern most roadway de- group symbol based on the Unified Soil Classifica- sign, particularly if the plant is coal fired. Roadway tion System, and penetration data (blow count). The material and thickness will be based on economic soils report will include recommendations as to type evaluations of feasible alternatives. Vehicular park- of foundations for various purposes; excavation, de- ing for plant personnel and visitors will be located in watering and fill procedures; and suitability of on- areas that will not interfere with the safe operation site material for fill and earthen dikes including data of the plant. Turning radii will be adequate to han- on soft and organic materials, rock and other perti- dle all vehicle categories. Refer to TM 5-803-5/ nent information as applicable. NAVPAC P-960/AFM 88-43; TM 5-818-2/ AFM 88-6, Chap. 4; TM 5-822-2/AFM 88-7, Chap. 2-8. Site development 7; TM 5-822-4/AFM 88-7, Chap. 4; TM a. Grading and drainage. 5-822 -5/AFM 88-7, Chap. 3; TM 5-822-6/AFM (1) Basic criteria. Determination of final grad- 88-7, Chap. 1; TM 5-822-7/AFM 88-6, Chap. 8; and ing and drainage scheme for a new power plant will TM 5-822-8. be based on a number of considerations including c. Railroads. If a railroad spur is selected to han- size of property in relationship to the size of plant dle fuel supplies and material and equipment deliv- facilities, desirable location on site, and plant access eries during construction or plant expansion, the de- based on topography. If the power plant is part of sign will be in accordance with American Railway an overall complex, the grading and drainage will be Engineering Association standards. If coal is the compatible and integrated with the rest of the com- fuel, spur layout will accommodate coal handling fa- plex. To minimize cut and fill, plant facilities will be cilities including a storage track for empty cars. If located on high ground and storm water drainage liquid fuel is to be handled, unloading pumps and will be directed away from the plant. Assuming on steam connections for tank car heaters may be re- site soils are suitable, grading should be based on quired in frigid climates. balanced cut and fill volume to avoid hauling of ex- cess fill material to offsite disposal and replacement 2-9. Buildings with expensive new material. a. Size and arrangement. (2) Drainage. Storm water drainage will be (1) Steam plant. Main building size and ar- evaluated based on rainfall intensities, runoff char- rangement depend on the selected plant equipment acteristics of soil, facilities for receiving storm and facilities including whether steam generators water discharge, and local regulations. Storm water are indoor or outdoor type; coal bunker or silo ar- drains or systems will not be integrated with sani- rangement; source of cooling water supply relative tary drains and other contaminated water drainage to the plant; the relationship of the switchyard to systems. the plant; provisions for future expansion; and , (3) Erosion prevention. All graded areas will be aesthetic and environmental considerations. Gener- stabilized to control erosion by designing shallow ally, the main building will consist of a turbine bay slopes to the greatest extent possible and by means with traveling crane; an auxiliary bay for feedwater of soil stabilization such as seeding, sod, stone, rip- heaters, pumps, and switchgear; a steam generator rap and retaining walls. bay (or firing aisle for semi-outdoor units); and gen- b. Roadways. eral spaces as may be required for machine shop, (1) Basic roadway requirements. Layout of locker room, laboratory and office facilities. The plant roadways will be based on volume and type of general spaces will be located in an area that will not traffic, speed, and traffic patterns. Type of traffic or interfere with future plant expansion and isolated vehicle functions for power plants can be catego- from main plant facilities to control noise. For very rized as follows: mild climates the turbine generator sets and steam -Passenger cars for plant personnel. generators may be outdoor type (in a weather pro- -Passenger cars for visitors. tected, walk-in enclosure) although this arrange- -Trucks for maintenance material deliveries. ment presents special maintenance problems. If in- -Trucks for fuel supply. corporated, the elevator will have access to the high- 2-2
  • TM 5-811-6est operating level of the steam generator (drum lev- areas, such as for the control room enclosure and forels). offices, may utilize factory fabricated metal walls, (2) Diesel plant. The requirements for a build- fixed or moveable according to the application.ing housing a diesel generator plant are the same as (4) Roof decks. Main building roof decks will befor a steam turbine plant except that a steam gener- constructed of reinforced concrete or ribbed metalator bay is not required. deck with built-up multi-ply roofing to provide wat- b. Architectural treatment. erproofing. Roofs will be sloped a minimum of 1/4,- (1) The architectural treatment will be de- inch per foot for drainage.veloped to harmonize with the site conditions, both (5) Floors. Except where grating or checkerednatural and manmade. Depending on location, the plate is required for access or ventilation, all floorsenvironmental compatibility y may be the determin- will be designed for reinforced concrete with a non-ing factor. In other cases the climate or user prefer- slip finish.ence, tempered with aesthetic and economic factors, (6) Live loads. Buildings, structures and allwill dictate architectural treatment. Climate is a portions thereof will be designed and constructed tocontrolling factor in whether or not a total or partial support all live and dead loads without exceedingclosure is selected. Semi-outdoor construction with the allowable stresses of the selected materials inthe bulk of the steam generator not enclosed in a the structural members and connections. Typicalboiler room is an acceptable design. live loads for power plant floors are as follows: (2) For special circumstances, such as areas (a) Turbine generator floor 500 psfwhere extended periods of very high humidity, fre- (b) Basement and operating floors exceptquently combined with desert conditions giving rise turbine generator floor 200 psfto heavy dust and sand blasting action, indoor con- (c) Mezzanine, deaerator, andstruction with pressurized ventilation will be re- miscellaneous operating floors 200 psfquired not only for the main building but also, gen- (d) Offices, laboratories, instrumenterally, for the switchyard. Gas enclosed switchyard shops, and other lightly loaded areas 100 psfinstallations may be considered for such circum- Live loads for actual design will be carefully re-stances in lieu of that required above. viewed for any special conditions and actual loads (3) Control rooms, offices, locker rooms, and applicable. some out-buildings will be enclosed regardless of en- (7) Other loads. In addition to the live and deadclosure selected for main building. Circulating water loads, the following loadings will be provided for:pumps may be installed in the open, except in the (a) Wind loading. Building will be designed tomost severe climates. For semi-outdoor or outdoor resist the horizontal wind pressure available for thestations, enclosures for switchgear and motor con- site on all surfaces exposed to the wind.trols for the auxiliary power system will be enclosed (b) Seismic loading. Buildings and otherin manufacturer supplied walk-in metal housings or structures will be designed to resist seismic loadingsite fabricated closures. in accordance with the zone in which the building is c. Structural design. located. (1) Building framing and turbine pedestals. (c) Equipment loading. Equipment loads areThermal stations will be designed utilizing conven- furnished by the various manufacturers of eachtional structural steel for the main power station equipment item. In addition to equipment deadbuilding and support of boiler. The pedestal for sup- loads, impact loads, short circuit forces for genera-porting the turbine generator (and turbine driven tors, and other pertinent special loads prescribed byboiler feed pump if utilized) will be of reinforced con- the equipment function or requirements will be in-crete. Reinforced concrete on masonry construction cluded.may be used for the building framing (not for boiler d. Foundation design.framing); special concrete inserts or other provision (1) Foundations will be designed to safely sup-must be made in such event for support of piping, port all structures, considering type of foundationtrays and conduits. An economic evaluation will be and allowable bearing pressures. The two most com-made of these alternatives. mon types of foundations are spread footings and (2) Exterior walls. The exterior walls of most pile type foundations, although “raft” type of otherthermal power stations are constructed of insulated special approaches may be utilized for unusual cir-metal panels. However, concrete blocks, bricks, or cumstances.other material may be used depending on the aes- (2) Pile type foundations require reinforcedthetics and economics of the design. concrete pile caps and a system of reinforced con- (3) Interior walls. Concrete masonry blocks will crete beams to tie the caps together. Pile load capa-be used for interior walls; however, some specialized bilities may be developed either in friction or point 2-3
  • TM 5-811-6bearing. The allowable load on piles will be deter- wheels. This can be achieved by careful piping de-mined by an approved formula or by a load test. sign, but some access platforms or remote mechani-Piles can be timber, concrete, rolled structural steel cal operators may be necessary.shape, steel pipe, or steel pipe concrete filled. (4) Impact type handwheels will be used for (3) Design of the reinforced concrete turbine high pressure valves and all large valves.generator or diesel set foundation, both mat and (5) Valve centers will be mounted approximate-pedestal, will be such that the foundation is isolated ly 7 feet above floors and platforms so that risingfrom the main building foundations and structures stems and bottom rims of handwheels will not be aby expansion joint material placed around its perim- hazard.eter. The design will also insure that the resonance (6) Stairs with conventional riser-tread propor-of the foundation at operating speed is avoided in tions will be used. Vertical ladders, installed only asorder to prevent cracking of the foundation and a last resort, must have a safety cage if required by .damage to machines caused by resonant vibration. the Occupational Safety and Health Act (OSHA).The foundation will be designed on the basis of de- (7) All floors, gratings and checkered plates willflection. The limits of deflection will be selected to have non-slip surfaces.avoid values of natural frequency by at least 30 per- (8) No platform or walkway will be less than 3 ‘cent above or 30 percent below operating speed. feet wide. (4) Vibration mounts or “floating floor” foun- (9) Toe plates, fitted closely to the edge of alldations where equipment or equipment foundation floor openings, platforms and stairways, will be pro-inertia blocks are separated from the main building vided in all cases.floor by springs or precompressed material will gen- (10) Adequate piping and equipment drains toerally not be used in power plants except for ventila- waste will be provided.tion fans and other building service equipment. In (11) All floors subject to washdown or leaks willthese circumstances where such inertia blocks are be sloped to floor drains.considered necessary for equipment not normally so (12) All areas subject to lube oil or chemicalmounted, written justification will be included in spills will be provided with curbs and drains,the project design analysis supporting such a neces- (13) If plant is of semi-outdoor or outdoor con-sity. struction in a climate subject to freezing weather, (5) The location of turbine generators, diesel en- weather protection will be provided for criticalgine sets, boiler feed pumps, draft fans, compres- operating and maintenance areas such as the firingsors, and other high speed rotating equipment on aisle, boiler steam drum ends and soot blower loca-elevated floors will be avoided because of the diffi- tions.culty or impossibility of isolating equipment foun- (14) Adequate illumination will be provideddations from the building structure. throughout the plant. Illumination will comply with requirements of the Illuminating Engineers Society2-10. Safety. (IES) Lighting Handbook, as implemented by DOD a. Introduction. The safety features described in 4270.1-M.the following paragraphs will be incorporated into (15) Comfort air conditioning will be providedthe power plant design to assist in maintaining a throughout control rooms, laboratories, offices andhigh level of personnel safety. similar spaces where operating and maintenance b. Design safety features. In designing a power personnel spend considerable time.plant, the following general recommendations on (16) Mechanical supply and exhaust ventilationsafety will be given attention: will be provided for all of the power plant equipment (1) Equipment will be arranged with adequate areas to alleviate operator fatigue and prevent accu-access space for operation and for maintenance. mulation of fumes and dust. Supply will be ductedWherever possible, auxiliary equipment will be ar- to direct air to the lowest level of the power plantranged for maintenance handling by the main tur- and to areas with large heat release such as the tur-bine room crane. Where this is not feasible, mono- bine or engine room and the boiler feed pump area.rails, wheeled trucks, or portable A-frames should Evaporative cooling will be considered in low hu-be provided if disassembly of heavy pieces is re- midity areas. Ventilation air will be filtered andquired for maintenance. heated in the winter also, system air flow capacity (2) Safety guards will be provided on moving should be capable of being reduced in the winter.parts of all equipment. Battery room will have separate exhaust fans to re- (3) All valves, specialties, and devices needing move hydrogen emitted by batteries as covered inmanipulation by operators will be accessible with- TM 5-811-2/AFM 88-9, Chap. 2.out ladders, and preferably without using chain (17) Noise level will be reduced to at least the2-4
  • TM 5-811-6recommended maximum levels of OSHA. Use of fan (19) Color schemes will be psychologically rest-silencers, compressor silencers, mufflers on internal ful except where danger must be highlighted withcombustion engines, and acoustical material is re- special bright primary colors.quired as discussed in TM 5-805-4/AFM (20) Each equipment item will be clearly la-88-37/NAVFAC DM-3.1O and TM 5-805-9/AFM belled in block letters identifying it both by equip88-20/NAVFAC DM-3.14. Consideration should be ment item number and name. A complete, coordi-given to locating forced draft fans in acoustically nated system of pipe markers will be used for identi-treated fan rooms since they are usually the largest fication of each separate cycle and power plant serv-noise source in a power plant. Control valves will be ice system. All switches, controls, and devices on alldesigned to limit noise emissions. control panels will be labelled using the identical (18) A central vacuum cleaning system should names shown on equipment or remote devices beingbe considered to permit easy maintenance of plant. controlled. 2-5
  • TM 5-811-6 CHAPTER 3 STEAM TURBINE POWER PLANT DESIGN Section 1. TYPICAL PLANTS AND CYCLES 3-1. Introduction planning criteria on which the technical and econom- a. Definition. The cycle of a steam power plant is ic feasibility is based. The sizes and characteristics the group of interconnected major equipment com- of the loads to be supplied by the power plant, in- ponents selected for optimum thermodynamic char- cluding peak loads, load factors, allowances for fu- acteristics, including pressure, temperatures and ca- ture growth, the requirements for reliability, and pacities, and integrated into a practical arrange- the criteria for fuel, energy, and general economy, ment to serve the electrical (and sometimes by-prod- will be determined or verified by the designer and uct steam) requirements of a particular project. Se- approved by appropriate authority in advance of the lection of the optimum cycle depends upon plant final design for the project. size, cost of money, fuel costs, non-fuel operating b. Selection of cycle conditions. Choice of steam costs, and maintenance costs. conditions, types and sizes of steam generators and b. Steam conditions. Typical cycles for the prob- turbine prime movers, and extraction pressures de-able size and type of steam power plants at Army es- pend on the function or purpose for which the plant tablishments will be supplied by superheated steam is intended. Generally, these basic criteria shouldgenerated at pressures and temperatures between have already been established in the technical and600 psig (at 750 to 850°F) and 1450 psig (at 850 to economic feasibility studies, but if all such criteria 950º F). Reheat is never offered for turbine genera- have not been so established, the designer will selecttors of less than 50 MW and, hence, is not applicable the parameters to suit the intended use.in this manual. c. Coeneration plants. Back pressure and con- c. Steam turbine prime movers. The steam tur- trolled extraction/condensing cycles are attractivebine prime mover, for rated capacity limits of 5000 and applicable to a cogeneration plant, which is de-kW to 30,000 kW, will be a multi-stage, multi-valve fined as a power plant simultaneously supplyingunit, either back pressure or condensing. Smaller either electric power or mechanical energy and heatturbines, especially under 1000 kW rated capacity, energy (para. 3-4).may be single stage units because of lower first cost d. Simple condensing cycles. Straight condensingand simplicity. Single stage turbines, either back cycles, or condensing units with uncontrolled ex-pressure or condensing, are not equipped with ex- tractions are applicable to plants or situationstraction openings. where security or isolation from public utility power d. Back pressure turbines. Back pressure turbine supply is more important than lowest power cost.units usually exhaust at pressures between 250 psig Because of their higher heat rates and operatingand 15 psig with one or two controlled or uncon- costs per unit output, it is not likely that simple con-trolled extractions. However, there is a significant densing cycles will be economically justified for aprice difference between controlled and uncontrolled military power plant application as compared withextraction turbines, the former being more expen- that associated with public utility ‘purchased powersive. Controlled extraction is normally applied costs. A schematic diagram of a simple condensingwhere the bleed steam is exported to process or dis- cycle is shown on Figure 3-1.trict heat users. e. Condensing turbines. Condensing units ex- 3-3. Steam power cycle economyhaust at pressures between 1 inch of mercury abso- a. Introduction. Maximum overall efficiency andlute (Hga) and 5 inches Hga, with up to two con- economy of a steam power cycle are the principal de-trolled, or up to five uncontrolled, extractions. sign criteria for plant selection and design. In gener- al, better efficiency, or lower heat rate, is accom-3-2. Plant function and purpose panied by higher costs for initial investment, opera- a. Integration into general planning. General tion and maintenance. However, more efficientplant design parameters will be in accordance with cycles are more complex and may be less reliable peroverall criteria established in the feasibility study or unit of capacity or investment cost than simpler and 3-1
  • TM 5-611-6 NAVFAC DM3 Figure 3-1. Typical straight condensing cycle. less efficient cycles. Efficiency characteristics can pressed in terms of heat rate, which is total thermal be listed as follows: input to the cycle divided by the electrical output of (1) Higher steam pressures and temperatures the units. Units are Btu/kWh.contribute to better, or lower, heat rates. (1) Conversion to cycle efficiency, as the ratio of (2) For condensing cycles, lower back pressures output to input energy, may be made by dividingincrease efficiency except that for each particular the heat content of one kWh, equivalent to 3412.14turbine unit there is a crossover point where lower- Btu by the heat rate, as defined. Efficiencies are sel-ing back pressure further will commence to decrease dom used to express overall plant or cycle perform-efficiency because the incremental exhaust loss ef- ance, although efficiencies of individual compo-fect is greater than the incremental increase in avail- nents, such as pumps or steam generators, are com-able energy. monly used. (3) The use of stage or regenerative feedwater (2) Power cycle economy for particular plants orcycles improves heat rates, with greater improve- stations is sometimes expressed in terms of poundsment corresponding to larger numbers of such heat- of steam per kilowatt hour, but such a parameter isers. In a regenerative cycle, there is also a thermody- not readily comparable to other plants or cycles andnamic crossover point where lowering of an extrac- omits steam generator efficiency.tion pressure causes less steam to flow through the (3) For mechanical drive turbines, heat ratesextraction piping to the feedwater heaters, reducing are sometimes expressed in Btu per hp-hour, exclud-the feedwater temperature. There is also a limit to ing losses for the driven machine. One horsepowerthe number of stages of extraction/feedwater heat- hour is equivalent to 2544.43 Btu.ing which may be economically added to the cycle. c. Heat rate applications. In relation to steamThis occurs when additional cycle efficiency no long- power plant cycles, several types or definitions ofer justifies the increased capital cost. heat rates are used: (4) Larger turbine generator units are generally (1) The turbine heat rate for a regenerative tur-more efficient that smaller units. bine is defined as the heat consumption of the tur- (5) Multi-stage and multi-valve turbines are bine in terms of “heat energy in steam” supplied bymore economical than single stage or single valve the steam generator, minus the “heat in the feedwa-machines. ter” as warmed by turbine extraction, divided by (6) Steam generators of more elaborate design, the electrical output at the generator terminals.or with heat saving accessory equipment are more This definition includes mechanical and electricalefficient. losses of the generator and turbine auxiliary sys- b. Heat rate units and definitions. The economy tems, but excludes boiler inefficiencies and pumpingor efficiency of a steam power plant cycle is ex- losses and loads. The turbine heat rate is useful for3-2
  • TM 5-811-6 performing engineering and economic comparisons plant lighting, air conditioning and heating, general of various turbine designs. Table 3-1 provides theo- water supply, startup and shutdown losses, fuel de- retical turbine steam rates for typical steam throttle terioration losses, and related items. The gradual conditions. Actual steam rates are obtained by di- and inevitable deterioration of equipment, and fail- viding the theoretical steam rate by the turbine effi- ure to operate at optimum conditions, are reflected ciency. Typical turbine efficiencies are provided on in plant operating heat rate data. Figure 3-2. d. Plant economy calculations. Calculations, esti- mates, and predictions of steam plant performance ASR = will allow for all normal and expected losses and where: ASR = actual steam rate (lb/kWh) loads and should, therefore, reflect predictions of TSR = theoretical steam rate (l/kWh) monthly or annual net operating heat rates and nt = turbine efficiency costs. Electric and district heating distribution Turbine heat rate can be obtained by multiplying losses are not usually charged to the power plant the actual steam rate by the enthalpy change across but should be recognized and allowed for in capacity the turbine (throttle enthalpy - extraction or ex- and cost analyses. The designer is required to devel- haust enthalpy). op and optimize a cycle heat balance during the con- Ct = ASR(hl – h2) ceptual or preliminary design phase of the project. where = turbine heat rate (Btu/kWh) The heat balance depicts, on a simplified flow dia- ASR = actual steam rate lb/kWh) gram of the cycle, all significant fluid mass flow h1 = throttle enthalpy rates, fluid pressures and temperatures, fluid en- h1 = extraction or exhaust enthalpy thalpies, electric power output, and calculated cycle heat rates based on these factors. A heat balance is TSR usually developed for various increments of plant load (i.e., 25%, 50%, 75%, 100% and VWO (valves wide open)). Computer programs have been devel- oped which can quickly optimize a particular cycle heat rate using iterative heat balance calculations. Use of such a program should be considered. e. Cogeneration performance. There is no gener-’ ally accepted method of defining the energy effi- ciency or heat rates of cogeneration cycles. Various methods are used, and any rational method is valid. The difference in value (per Btu) between prime en- ergy (i.e., electric power) and secondary or low level energy (heating steam) should be recognized. Refer FROM STANDARD HANDBOOK FOR MECHANICAL ENGINEERS BY MARKS. COPYRIGHT © 1967, to discussion of cogeneration cycles below.. MCGRAW-HILL BOOK CO. USED WITH THE PERMISSION OF MCGRAW- HILL BOOK COMPANY. 3-4. Cogeneration cycles Figure 3-2. Turbine efficiencies vs. capacity. a. Definition. In steam power plant practice, co-m generation normally describes an arrangement (2) Plant heat rates include inefficiencies and whereby high pressure steam is passed through a losses external to the turbine generator, principally turbine prime mover to produce electrical power, the inefficiencies of the steam generator and piping and thence from the turbine exhaust (or extraction) systems; cycle auxiliary losses inherent in power re- opening to a lower pressure steam (or heat) distribu- quired for pumps and fans; and related energy uses tion system for general heating, refrigeration, or such as for soot blowing, air compression, and simi- process use. lar services. b. Common medium. Steam power cycles are par- (3) Both turbine and plant heat rates, as above, ticularly applicable to cogeneration situations be- are usually based on calculations of cycle perform- cause the actual cycle medium, steam, is also a con- ance at specified steady state loads and well defined, venient medium for area distribution of heat. optimum operating conditions. Such heat rates are (1) The choice of the steam distribution pres- seldom achieved in practice except under controlled sure will be a balance between the costs of distribu- or test conditions. tion which are slightly lower at high pressure, and (4) Plant operating heat rates are long term the gain in electrical power output by selection of a average actual heat rates and include other such lower turbine exhaust or extraction pressure. losses and energy uses as non-cycle auxiliaries, (2) Often the early selection of a relatively low 3-3
  • TM 5-811-63-4
  • TM 5-811-6 steam distribution pressure is easily accommodated (1) Back pressure cycle. In this type of plant, in the design of distribution and utilization systems, the entire flow to the turbine is exhausted (or ex- whereas the hasty selection of a relatively high tracted) for heating steam use. This cycle is the steam distribution pressure may not be recognized more effective for heat economy and for relatively as a distinct economic penalty on the steam power lower cost of turbine equipment, because the prime plant cycle. mover is smaller and simpler and requires no con- (3) Hot water heat distribution may also be ap- denser and circulating water system. Back pressure plicable as a district heating medium with the hot turbine generators are limited in electrical output by water being cooled in the utilization equipment and the amount of exhaust steam required by the heat returned to the power plant for reheating in a heat load and are often governed by the exhaust steam exchange with exhaust (or extraction) steam. load. They, therefore, usually operate in electrical c. Relative economy. When the exhaust (or ex- parallel with other generators. traction) steam from a cogeneration plant can be (2) Extraction-condensing cycles. Where the utilized for heating, refrigeration, or process pur- electrical demand does not correspond to the heat poses in reasonable phase with the required electric demand, or where the electrical load must be carried power load, there is a marked economy of fuel ener- at times of very low (or zero) heat demand, then con- gy because the major condensing loss of the conven- densing-controlled extraction steam turbine prime tional steam power plant (Rankine) cycle is avoided. movers as shown in Figure 3-3 may be applicable. If a good balance can be attained, up to 75 percent of Such a turbine is arranged to carry a specified elec- the total fuel energy can be utilized as compared trical capacity either by a simple condensing cycle with about 40 percent for the best and largest Ran- or a combination of extraction and condensing. kine cycle plants and about 25 to 30 percent for While very flexible, the extraction machine is rela- small Rankine cycle systems. tively complicated, requires complete condensing d. Cycle types. The two major steam power cogen- and heat rejection equipment, and must always pass eration cycles, which may be combined in the same a critical minimum flow of steam to its condenser to plant or establishment, are: cool the low pressure buckets... NAVFAC DM3 Figure 3-3. Typical condensing-controlled extinction cycle. 3-5
  • TM 5-811-6 e. Criteria for cogeneration. For minimum eco- protection against internal corrosion.nomic feasibility, cogeneration cycles will meet the c. Special considerations. Where the special cir-following criteria: cumstances of the establishment to be served are (1) Load balance. There should be a reasonably significant factors in power cycle selection, the fol-balanced relationship between the peak and normal lowing considerations may apply:requirements for electric power and heat. The (1) Electrical isolation. Where the proposedpeak/normal ratio should not exceed 2:1. plant is not to be interconnected with any local elec- (2) Load coincidence. There should be a fairly tric utility service, the selection of a simpler, lowerhigh coincidence, not less than 70%, of time and pressure plant may be indicated for easier operationquantity demands for electrical power and heat. and better reliability y. (3) Size. While there is no absolute minimum (2) Geographic isolation. Plants to be installedsize of steam power plant which can be built for co- at great distances from sources of spare parts, main-generation, a conventional steam (cogeneration) tenance services, and operating supplies may re-plant will be practical and economical only above quire special consideration of simplified cycles, re- some minimum size or capacity, below which other dundant capacity and equipment, and highest prac-types of cogeneration, diesel or gas turbine become tical reliability. Special maintenance tools and facil-more economical and convenient. ities may be required, the cost of which would be af- (4) Distribution medium. Any cogeneration fected by the basic cycle design.plant will be more effective and economical if the (3) Weather conditions. Plants to be installedheat distribution medium is chosen at the lowest under extreme weather conditions will require spe-possible steam pressure or lowest possible hot water cial consideration of weather protection, reliability,temperature. The power energy delivered by the tur- and redundancy. Heat rejection requires special de-bine is highest when the exhaust steam pressure is sign consideration in either very hot or very coldlowest. Substantial cycle improvement can be made weather conditions. For arctic weather conditions,by selecting an exhaust steam pressure of 40 psig circulating hot water for the heat distribution medi-rather than 125 psig, for example. Hot water heat um has many advantages over steam, and the use ofdistribution will also be considered where practical an antifreeze solution in lieu of pure water as a dis-or convenient, because hot water temperatures of tribution medium should receive consideration.200 to 240º F can be delivered with exhaust steampressure as low as 20 to 50 psig. The balance be- 3-6. Cycle equipmenttween distribution system and heat exchanger a. General requirements. In addition to the primecosts, and power cycle effectiveness will be opti- movers, alternators, and steam generators, a com-mized. plete power plant cycle includes a number of second- ary elements which affect the economy and perform- 3-5. Selection of cycle steam conditions ance of the plant. a. Balanced costs and economy. For a new or iso- b. Major equipment. Refer to other parts of thislated plant, the choice of initial steam conditions manual for detailed information on steam turbine should be a balance between enhanced operating driven electric generators and steam generators.economy at higher pressures and temperatures, and c. Secondary cycle elements. Other equipmentgenerally lower first costs and less difficult opera- items affecting cycle performance, but subordinatetion at lower pressures and temperatures. Realistic to the steam generators and turbine generators, areprojections of future fuel costs may tend to justify also described in other parts of this chapter.higher pressures and temperatures, but such factorsas lower availability y, higher maintenance costs, 3-7. Steam power plant arrangementmore difficult operation, and more elaborate water a. General. Small units utilize the transverse ar-treatment will also be considered. rangement in the turbine generator bay while the b. Extension of existing plant. Where a new larger utility units are very long and require end-to-steam power plant is to be installed near an existing end arrangement of the turbine generators.steam power or steam generation plant, careful con- b. Typical small plants. Figures 3-4 and 3-6 showsideration will be given to extending or paralleling typical transverse small plant arrangements. Smallthe existing initial steam generating conditions. If units less than 5000 kW may have the condensers atexisting steam generators are simply not usable in the same level as the turbine generator for economythe new plant cycle, it may be appropriate to retire as shown in Figure 3-4. Figure 3-6 indicates thethem or to retain them for emergency or standby critical turbine room bay dimensions and the basicservice only. If boilers are retained for standby serv- overall dimensions for the small power plants shownice only, steps will be taken in the project design for in Figure 3-5.
  • TM 5-811-6U. S. Army Corps of Engineers Figure 3-4. Typical small 2-unit powerplant “A”. 3-7
  • TM 5-811-6 a3-8
  • TM 5-811-6 Section Il. STEAM GENERATORS AND AUXILIARY SYSTEMS. 3-8. Steam generator conventional tors for a steam power plant can be classified by types and characteristics type of fuel, by unit size, and by final steam condi- a. Introduction. Number, size, and outlet steam- tion. Units can also be classified by type of draft, by ing conditions of the steam generators will be as de- method of assembly, by degree of weather protec- termined in planning studies and confirmed in the fi- tion and by load factor application. nal project criteria prior to plant design activities. (1) Fuel, general. Type of fuel has a major im- Note general criteria given in Section I of this chap pact on the general plant design in addition to the ter under discussion of typical plants and cycles. steam generator. Fuel selection may be dictated by b. Types and classes. Conventional steam genera- considerations of policy and external circumstances.!. AND CONDENSER SUPPLIERS SELECTED. 36 43 31 16 6 11.3 7.5 3.7 1.2 5.5 5 17.5 5 8 11 NOTE: DIMENSIONS IN TABLE ARE APPLICABLE TO FIG. 3-5 U S . Army Corps of Engineers Figure 3-6. Critical turbine room bay and power plant “B” dimensions. 3-9
  • TM 5-811-6unrelated to plant costs, convenience, or location. stoker and grate selection, performance, and main-Units designed for solid fuels (coal, lignite, or solid tenance. For pulverized coal firing, grindability is awaste) or designed for combinations of solid, liquid, major consideration, and moisture content beforeand gaseous fuel are larger and more complex than and after local preparation must be considered. Coalunits designed for fuel oil or fuel gas only. burning equipment and related parts of the steam (2) Fuel coal. The qualities or characteristics of generator will be specified to match the specificparticular coal fuels having significant impact on characteristics of a preselected coal fuel as well assteam generator design and arrangement are: heat- they can be determined at the time of design.ing value, ash content, ash fusion temperature, fri- (3) Unit sizes. Larger numbers of smaller steamability, grindability, moisture, and volatile content generators will tend to improve plant reliability andas shown in Table 3-2. For spreader stoker firing, flexibility for maintenance. Smaller numbers of larg-the size, gradation, or mixture of particle sizes affect er steam generators will result in lower first costs Table 3-2. Fuel Characteristcs. Characteristic Effects Coal Heat balance. Handling and efficiency loss. Ignition and theoretical air. Freight, storage, handling, air pollution. Slagging, allowable heat release, allowable furnace exit gas temperature. Heat balance, fuel cost. Handling and storage. Crushing and pulverizing. Crushing , segregation, and spreading over fuel bed. Allowable temp. of metal contacting flue gas; removal from flue gas. Oil Heat balance. Fuel cost. Preheating, pumping, firing. Pumping and metering. Vapor locking of pump suction. Heat balance, fuel cost. Allowable temp. of metal contacting flue gas; removal from flue gas. Gas Heat balance. Pressure, f i r i n g , f u e l c o s t . Metering. Heat balance, fuel cost. Insignificant. NAVFAC DM33-10
  • TM 5-811-6 per unit of capacity and may permit the use of de- building construction costs. Aesthetic, environmen- sign features and arrangements not available on tal, or weather conditions may require indoor instal- smaller units. Larger units are inherently more effi- lation, although outdoors units have been used SUC- cient, and will normally have more efficient draft cessfully in a variety of cold or otherwise hostile cli- fans, better steam temperature control, and better mates. In climates subject to cold weather, 30 “F. for control of steam solids. 7 continuous days, outdoor units will require electri- (4) Final steam conditions. Desired pressure cally or steam traced piping and appurtenances to and temperature of the superheater outlet steam prevent freezing. The firing aisle will be enclosed (and to a lesser extent feedwater temperature) will either as part of the main power plant building or as have a marked effect on the design and cost of a a separate weather protected enclosure; and the steam generator. The higher the pressure the heav- ends of the steam drum and retractable soot blowers ier the pressure parts, and the higher the steam tem- will be enclosed and heated for operator convenience perature the greater the superheater surface area and maintenance. and the more costly the tube material. In addition to (8) Load factor application. As with all parts of this, however, boiler natural circulation problems in- the plant cycle, the load factor on which the steam crease with higher pressures because the densities generator is to be operated affects design and cost of the saturated water and steam approach each oth- factors. Units with load factors exceeding 50% will er. In consequence, higher pressure boilers require be selected and designed for relatively higher effi- more height and generally are of different design ciencies, and more conservative parameters for fur- than boilers of 200 psig and less as used for general nace volume, heat transfer surface, and numbersspace heating and process application. and types of auxiliaries. Plants with load factors (5) Type of draft. less than 50% will be served by relatively less ex- (a) Balanced draft. Steam generators for elec- pensive, smaller and less durable equipment.tric generating stations are usually of the so called “balanced draft” type with both forced and induced draft fans. This type of draft system uses one or 3-9. Other steam generator characteris-more forced draft fans to supply combustion air un- tics der pressure to the burners (or under the grate) and a. Water tube and waterwell design. Power plant one or more induced draft fans to carry the hot com- boilers will be of the water welled or water cooledbustion gases from the furnace to the atmosphere; a furnace types, in which the entire interior surface of slightly negative pressure is maintained in the fur- the furnace is lined with steam generating heatingnace by the induced draft fans so that any gas leak- surface in the form of closely spaced tubes usually age will be into rather than out of the furnace. Nat- all welded together in a gas tight enclosure.ural draft will be utilized to take care of the chimney b. Superheated steam. Depending on manufac- or stack resistance while the remainder of the draft turer’s design some power boilers are designed to friction from the furnace to the chimney entrance is deliver superheated steam because of the require-handled by the induced draft fans. ments of the steam power cycle. A certain portion of (b) Choice of draft. Except for special cases the total boiler heating surface is arranged to add such as for an overseas power plant in low cost fuel superheat energy to the steam flow. In superheaterareas, balanced draft, steam generators will be spec- design, a balance of radiant and convective super-ified for steam electric generating stations. heat surfaces will provide a reasonable superheat (6) Method of assembly. A major division of characteristic. With high ‘pressure - high temper-steam generators is made between packaged or fac- ature turbine generators, it is usually desirable totory assembled units and larger field erected units. provide superheat controls to obtain a flat charac-Factory assembled units are usually designed for teristic down to at least 50 to 60 percent of load.convenient shipment by railroad or motor truck, This is done by installing excess superheat surfacecomplete with pressure parts, supporting structure, and then attemperating by means of spray water atand enclosure in one or a few assemblies. These the higher loads. In some instances, boilers are de-units are characteristically bottom supported, while signed to obtain superheat control by means of tilt-the larger and more complex power steam gener- ing burners which change the heat absorption pat-ators are field erected, usually top supported. tern in the steam generator, although supplemen- (7) Degree of weather protection. For all types tary attemperation is also provided with such a con-and sizes of steam generators, a choice must be trol system.made between indoor, outdoor and semi-outdoor in- c. Balanced heating surface and volumetric de-stallation. An outdoor installation is usually less ex- sign parameters. Steam generator design requirespensive in first cost which permits a reduced general adequate and reasonable amounts of heating surface 3-11
  • TM 5-811-6 and furnace volume for acceptable performance and steam header system may be more reliable and more longevity. economical than unit operation. Where a group of (1) Evaporative heating surface. For its rated steam turbine prime movers of different types; i.e., capacity output, an adequate total of evaporative or one back pressure unit plus one condensing/extrac- steam generating heat transfer surface is required, tion unit are installed together, overall economy can which is usually a combination of furnace wall ra- be enhanced by a header (or parallel) boiler arrange- diant surface and boiler convection surface. Bal- ment. anced design will provide adequate but not exces- sive heat flux through such surfaces to insure effec- 3-10. Steam generator special types tive circulation, steam generation and efficiency. a. Circulation. Water tube boilers will be specified (2) Superheater surface. For the required heat to be of natural circulation. The exception to this transfer, temperature control and protection of met- rule is for wasteheat boilers which frequently are a . . al parts, the superheater must be designed for a bal- special type of extended surface heat exchanger de- ance between total surface, total steam flow area, signed for forced circulation. and relative exposure to radiant convection heat b. Fludized bed combustion. The fluidized bed sources. Superheaters may be of the drainable or boiler has the ability to produce steam in an environ- non-drainable types. Non-drainable types offer cer- mentally accepted manner in controlling the stack tain advantages of cost, simplicity, and arrange- emission of sulfur oxides by absorption of sulfur in ment, but are vulnerable to damage on startup. the fuel bed as well as nitrogen oxides because of its Therefore, units requiring frequent cycles of shut- relatively low fire box temperature. The fluidized down and startup operations should be considered bed boiler is a viable alternative to a spreader stoker for fully drainable superheaters. With some boiler unit. A fluidized bed steam generator consists of a designs this may not be possible. fluidized bed combustor with a more or less conven- (3) Furnace volume. For a given steam gener- tional steam generator which includes radiant and ator capacity rating, a larger furnace provides lower convection boiler heat transfer surfaces plus heat re- furnace temperatures, less probability of hot spots, covery equipment, draft fans, and the usual array ofand a lower heat flux through the larger furnace wall steam generator auxiliaries. A typical fluidized bed surface. Flame impingement and slagging, partic- boiler is shown in Figure 3-7.ularly with pulverized coal fuel, can be controlled orprevented with increased furnace size. 3-11. Major auxiliary systems. (4) General criteria. Steam generator design a. Burners.will specify conservative lower limits of total heat- (1) Oil burners. Fuel oil is introduced throughing surface, furnace wall surface and furnace vol- oil burners, which deliver finely divided or atomizedume, as well as the limits of superheat temperature liquid fuel in a suitable pattern for mixing with com-control range. Furnace volume and surfaces will be bustion air at the burner opening. Atomizing meth-sized to insure trouble free operation. ods are classified as pressure or mechanical type, air (5) Specific criteria. Steam generator specifica- atomizing and steam atomizing type. Pressuretions set minimum requirements for Btu heat re- atomization is usually more economical but is alsolease per cubic foot of furnace volume, for Btu heat more complex and presents problems of control,release per square foot of effective radiant heating poor turndown, operation and maintenance. Thesurface and, in the case of spreader stokers, for Btu range of fuel flows obtainable is more limited withper square foot of grate. Such parameters are not set pressure atomization. Steam atomization is simpleforth in this manual, however, because of the wide to operate, reliable, and has a wide range, but con-range of fuels which can affect these equipment de- sumes a portion of the boiler steam output and addssign considerations. The establishment of arbitrary moisture to the furnace gases. Generally, steamlimitations which may handicap the geometry of atomization will be used when makeup water is rela-furnace designs is inappropriate. Prior to setting tively inexpensive, and for smaller, lower pressurefurnace geometry parameters, and after the type plants. Air atomization will be used for plants burn-and grade of fuel are established and the particular ing light liquid fuels, or when steam reacts ad-service conditions are determined, the power plant versely with the fuel, i.e., high sulfur oils.designer will consult boiler manufacturers to insure (2) Gas and coal burners. Natural gas or pulver-that steam generator specifications are capable of ized coal will be delivered to the burner for mixingbeing met. with combustion air supply at the burner opening. d. Single unit versus steam header system. For Pulverized coal will be delivered by heated, pressur-cogeneration plants, especially in isolated locations ized primary air.or for units of 10,000 kW and less, a parallel boiler or (3) Burner accessories. Oil, gas and pulverized3-12
  • TM 5-811-6coal burners will be equipped with adjustable air heating surfaces, and convenience of operation andguide registers designed to control and shape the air control.flow into the furnace, Some burner designs also pro- (5) Burner managerment systems. Plant safetyvide for automatic insertion and withdrawal of vary- practices require power plant fuel burners to being size oil burner nozzles as load and operating con- equipped with comprehensive burner control andditions require. safety systems to prevent unsafe or dangerous con- (4) Number of burners. The number of burners ditions which may lead to furnace explosions. Therequired is a function both of load requirements and primary purpose of a burner management system isboiler manufacturer design. For the former, the indi- safety which is provided by interlocks, furnacevidual burner turndown ratios per burner are pro- purge cycles and fail safe devices.vided in Table 3-3. Turndown ratios in excess of b. Pulverizes. The pulverizers (mills) are an essen-those listed can be achieved through the use of mul- tial part of powdered coal burning equipment, andtiple burners. Manufacturer design limits capacity are usually located adjacent to the steam generatorof each burner to that compatible with furnace flame and burners, but in a position to receive coal byand gas flow patterns, exposure and damage to gravity from the coal silo. The coal pulverizers grind STEAM OUTLET TO SUPERHEATER IN BED k 1111111 rlu- SPREAOER U.S. Army Corps of Engineers Figure 3-7. Fluidized bed combustion boiler. 3-13
  • TM 5-811-6and classify the coal fuel to specific particle sizes for clude sudden load changes, pulverized coal feedersrapid and efficient burning. Reliable and safe pulver- are to be used.izing equipment is essential for steam generator op- (2) Grate operation requires close and skillfuleration. Pulverized coal burning will not be specified operator attention, and overall plant performance isfor boilers smaller than 150,000 lb/hour. sensitive to fuel sizing and operator experience. c. Stokers and grates. For small and medium Grates for stoker fired units occupy a large part ofsized coal burning steam generators, less than the furnace floor and must be integrated with ash re-150,000 lb/hour, coal stokers or fluidized bed units moval and handling systems. A high proportion ofwill be used. For power boilers, spreader stokers stoker ash must be removed from the grates in awith traveling grates are used. Other types of wide range of particle sizes and characteristics al-stokers (retort, underfeed, or overfeed types) are though some unburned carbon and fly ash is carriedgenerally obsolete for power plant use except per- out of the furnace by the flue gas. In contrast, ahaps for special fuels such as anthracite. larger proportion of pulverized coal ash leaves the . (1) Spreader stokers typically deliver sized coal, furnace with the gas flow as finely divided particu-with some proportion of fines, by throwing it into late,the furnace where part of the fuel burns in suspen- (3) Discharged ash is allowed to COOl in the ashsion and the balance falls to the traveling grate for hopper at the end of the grate and is then sometimesburnout. Stoker fired units will have two or more put through a clinker grinder prior to removal in thespreader feeder units, each delivering fuel to its own vacuum ash handling system described elsewhere inseparate grate area. Stoker fired units are less re- this manual.sponsive to load changes because a large proportion d. Draft fans, ducts and flues.of the fuel burns on the grate for long time periods (1) Draft fans.(minutes). Where the plant demand is expected to in- (a) Air delivery to the furnace and flue gas re- Table 3-3. Individual Burner Turndown Ratios. Burner Type Turndown Ratio NATURAL GM Spud or Ring Type 5:1 to 10:1 HEAVY FUEL OIL Steam Atomizing 5:1 to 10:1 Mechanical Atomizing 3:1 to 10:1 COAL Pulverized 3:1 Spreader-Stoker 2:1 to 3:1 Fluidized Bed (single bed) 2:1 to 3:1 U.S. Army Corps of Engineers3-14
  • II TM 5-811-6 moval will be provided by power driven draft fans sion resistance and overall gas tightness. Adequate designed for adequate volumes and pressures of air space and weight capacity will be allowed in overall and gas flow. Typical theoretical air requirements plant arrangement to avoid awkward, noisy or mar- are shown in Figure 3-8 to which must be added ex- ginal fan, duct and flue systems. Final steam gener- cess air which varies with type of firing, plus fan ator design will insure that fan capacities (especially margins on both volumetric and pressure capacity pressure) are matched properly to realistic air and for reliable full load operation. Oxygen and carbon gas path losses considering operation with dirty dioxide in products of combustion for various boilers and under abnormal operating conditions. amounts of excess air are also shown in Figure 3-8. Damper durability and control characteristics will (b) Calculations of air and gas quantities and be carefully designed; dampers used for control pur- pressure drops are necessary. Since fans are heavy poses will be of opposed blade construction. power consumers, for larger fans consideration e. Heat recovery. Overall design criteria require should be given to the use of back pressure steam highest fuel efficiency for a power boiler; therefore, turbine drives for economy, reliability and their abil- steam generators will be provided with heat recov- it y to provide speed variation. Multiple fans on each ery equipment of two principal types: air pre- boiler unit will add to first costs but will provide heater and economizers. more flexibility and reliability . Type of fan drives (1) Efficiency effects. Both principal types of and number of fans will be considered for cost effec- heat recovery equipment remove relatively low level tiveness. Fan speed will be conservatively selected, heat from the flue gases prior to flue gas discharge and silencers will be provided in those cases where to the atmosphere, using boiler fluid media (air or noise by fans exceeds 80 decibels. water) which can effectively absorb such low level (c) Power plant steam generator units de- energy. Such equipment adds to the cost, complex- signed for coal or oil will use balanced draft design ity and operational skills required, which will be bal- with both forced and induced draft fans arranged for anced by the plant designer against the life cycle closely controlled negative furnace pressure. fuel savings. (2) Ducts and flues. Air ducts and gas flues will (2) Air preheater. Simple tubular surface be adequate in size and structural strength and de- heaters will be specified for smaller units and the re- signed with provision for expansion, support, corro- generative type heater for larger boilers. To mini- . . 3-15
  • TM 5-811-6mize corrosion and acid/moisture damage, especially height sometimes limited by aesthetic or other non-with dirty and high sulphur fuels, special alloy steel economic considerations. Draft is a function of den-will be used in the low temperature heat transfer sit y difference between the hot stack gases and am-surface (replaceable tubes or “baskets”) of air pre- bient air, and a number of formulas are available forheater. Steam coil air heaters will be installed to calculating draft and friction. Utilize draft of themaintain certain minimum inlet air (and metal) tem- stack or chimney only to overcome friction withinperatures and thus protect the main preheater from the chimney with the induced draft fan(s) supplyingcorrosion at low loads or low ambient air tempera- stack or chimney entrance. Maintain relatively hightures. Figure 3-9 illustrates the usual range of mini- gas exit velocities (50 to 60 feet per second) to ejectmum metal temperatures for heat recovery equip- gases as high above ground level as possible. Reheatment. (usually by steam) will be provided if the gases are (3) Economizers. Either an economizer or an air treated (and cooled) in a flue gas desulfurizationheater or a balanced selection of both as is usual in a scrubber prior to entering the stack to add buoy-power boiler will be provided, allowing also for tur- ancy and prevent their settling to the ground afterbine cycle feedwater stage heating. ejection to the atmosphere. Insure that downwash f. Stacks. due to wind and building effects does not drive the (1) Delivery of flue gases to the atmosphere flue gas to the ground.through a flue gas stack or chimney will be pro- g. Flue gas cleanup. The requirements for flue gasvided. cleanup will be determined during design. (2) Stacks and chimneys will be designed to dis- (1) Design considerations. The extent and na-charge their gases without adverse local effects. Dis- ture of the air pollution problem will be analyzedpersion patterns and considerations will be treated prior to specifying the environmental control sys-during design. tem for the steam generator. The system will meet (3) Stacks and chimneys will be sized with due all applicable requirements, and the application willregard to natural draft and stack friction with be the most economically feasible method of accom- plishment. All alternative solutions to the problem 290 will be considered which will satisfy the given load and which will produce the least objectionable wastes. Plant design will be such as to accommodate future additions or modifications at minimum cost. Questions concerning unusual problems, unique ap- placations or marginal and future requirements will be directed to the design agency having jurisdiction over the project. Table 3-4 shows the emission lev- els allowable under the National Ambient Air Quality Standards. (2) Particulate control. Removal of flue gas par- ticulate material is broadly divided into mechanical dust collectors, electrostatic precipitators, bag fil- ters, and gas scrubbing systems. For power plants of the size range here considered estimated uncon- trolled emission levels of various pollutants are shown in Table 3-5. Environmental regulations re- quire control of particulate, sulfur oxides and nitro- gen oxides. For reference purposes in this manual, typical control equipment performance is shown in Table 3-6, 3-7, 3-8, 3-9, 3-10 and 3-11. These only provide general guidance. The designer will refer to TM 5-815-l/AFR 19-6/NAVFAC DM-3.15 for de- tails of this equipment and related computational requirements and design criteria. (a) Mechanical collectors. For oil fired steam generators with output steaming capacities lessNAVFAC DM3 than 200,000 pounds per hour, mechanical (centrifu- gal) type dust collectors may be effective and eco-Figure 3-9. Minimum metal temperatures for boiler heat recovery equipment. nomical depending on the applicable emission stand-3-16
  • TM 5-811-6ards. For a coal fired boiler with a spreader stoker, a efficiency slightly but also will increase collectormechanical collector in series with an electrostatic dust loading and carryover. Ultimate collectedprecipitator or baghouse also might be considered. dust material must be handled and disposed of sys-Performance requirements and technical environ- tematically to avoid objectionable environmental ef-mental standards must be carefully matched, and fects.ultimate performance warranties and tests require (b) Electrostatic precipitators. For pulverizedcareful and explicit definitions. Collected dust from coal firing, adequate particulate control will requirea mechanical collector containing a large proportion electrostatic precipitators (ESP). ESP systems areof combustibles may be reinfected into the furnace well developed and effective, but add substantialfor final burnout; this will increase steam generator capital and maintenance costs. Very high percent- 3-17
  • Table3-5. Uncontrolled Emissions. COAL FIRED OIL FIRED NATURAL GAS (Lb of Pollutant/Ton of Coal) (Lb of Pollutant/1000 Gal) (Lb o f P o l l u t a n t / 1 06 F t 3 ) Pulverized Stokers orPollutantParticulateSulfur OxidesNitrogen Oxides1. The letter A indicates that the weight percentage of ash in the coal should be multiplied by the value given. Example: If the factor is 16 and the ash content is 10 percent, the particulate emissions before the control equipment would be 10 times 16, or 160 pounds of particulate per ton of coal.2. Without fly ash reinfection. With fly ash reinfection use 20A.3. S equals the sulfur content, use like the factor A (see Note 1 above) for estimate emissions.U.S. Environmental Protection Agency
  • 50-70 90-95 Industrial a n d utility boiler Particulate control. 2-6 50U.S. Army Corps of Engineers
  • Table 3-2! Characteristics of Scrubbers for Particulate Control. Internal Particle Pressure Drop Gas Flow Velocity Collection Water UsageScrubber Type Energy Type In. H O Ft /Min Ft/Sec Efficiency Per 1000 Gal/MinCentrifugal Low Energy 3-8 1,000- 50-150 80 3-5 Scrubber 20,000Impingement & Low Energy 4-20 500- 50-150 60-90 10-40 Entrainment 50,000Venturi High Energy 4-200 200- 200-600 95-99 5-7 150,000Ejector Venturi High Energy 10-50 500- 200-500 90-98 70-145 10,000 U.S. Army Corps of Engineers
  • Table 3-8. Characteristics of Electrostatic Precipitators (ESP) for Particulate Control. Pressure Operating , Resistivity Gas Drop Temperature at 300º F Flow In. ofType °F ohm-cm Ft/Min WaterHot ESP 600+ Greater Than 100,000+ Less Than 1 01 2 1"Cold ESP 300 Less0 Than 1 01Wet ESP 300- G r e1 a t e r T h a n 1 02below 1 04 U.S. Army Corps of Engineers
  • Table 3-9. Characteristics of Baghouses for Particulate Control. Pressure Loss Filter Ratio (Inches of (cfm/ftSystem Type Water) Efficiency Cloth Type Cloth Area) Recommended ApplicationShaker 3-6 99+% Woven 1-5 Dust with good filter cleaning properties, intermittent collection.Reverse Flow 3-6 99+% Woven 1-5 Dust with good filter cleaning properties, high temperature collection (incinerator fly- ash) with glass bags.Pulse Jet 3-6 99+% Felted 4-20 Efficient for coal and oil fly ash collection.Reverse Jet 3-8 99+% Felted 10-30 Collection of fine dusts and fumes.Envelope 3-6 99+% Woven 1-5 Collection of highly abrasive dust . U.S. Army Corps of Engineers
  • Table 3-10. Characteristics of Flue-Gas Desulfurization Systems for Particulate Control. Retrofit to SO Removal Pressure Drop Recovery and Operational ExistingSystem Type Efficiency (%) (Inches of Water) Regeneration Reliability Installations1) Limestone Boiler 30-40% Less Than 6“ No Recovery High Yea Injection Type of Limestone2) Limestone, Srubber 30-40% Greater Than 6“ No Recovery High Yea Injection Type of Lime3) Lime, Scrubber, 90%+ Greater Than 6“ No Recovery Low Yea Injection Type of Lime4) Magnesium Oxide Greater Than 6“ Recovery of MgO Low Yea and Sulfuric Acid5) Wellman-Lord 90%+ Greater Than 6“ Recovery of NaS03 Unknown and Elemental Sulfur6) Catalytic 85% May be as high as 24” Recovery of 80% Unknown No oxidation H2S047) Single Alkali 90%+ Tray Tower Pressure Little Recovery Unknown Yea Systems Drop 1.6-2.0 in. of Sodium Carbonate H2O/tray, w/Venturi add 10-14 in. H2O8) Dual Alkali 90-95%+ Regeneration of Unknown Yea Sodium Hydroxide and Sodium Sulfites U.S. Army Corps of Engineers g
  • Tabble 3-11. Techniques for Nitrogen Oxide Control. PotentialTechnique NO Reduction (%) Advantages DisadvantagesLoad Reduction Easily implemented; no additional Reduction in generating capacity; equipment required; reduced particu- possible reduction in boiler thermal late and SOX emissions. thermal efficiency.Low Excess Air Firing 15 to 40 Increased boiler thermal efficiency; A combustion control system which possible reduction in particulate closely monitors and controls fuel/ emissions may be combined with a load air ratios is required. reduction to obtain additional NOx emission decrease; reduction in high temperature corrosion and ash deposition.Two Stage ConbustionCoal 30 --- Boiler windboxes must be designed for this application.Oil 40 Furnace corrosion and particulateGas 50 - -- emissions may increase.Off-Stoichiometric Combustion Control of alternate fuel rich/and fuel lean burners may be a problemCoal 45 --- during transient load conditions.Reduced Combustion Air 10-50 --- Not applicable to coal or oil firedPreheat units; reduction in boiler thermal efficiency; increase in exit gas volume and temperature; reduction in boiler load.Flue Gas Recirculation 20-50 Possible improvement in combustion Boiler windbox must be modified to efficiency end reduction in particu- handle the additional gas volume; late emissions. ductwork, fans and Controls required. U.S. Army Corps of Engineers
  • TM 5-811-6 ages of particulate removal can be attained (99 per- compressed air and injected into the boiler flue gas cent, plus) but precipitators are sensitive to ash stream. SO2 and SO3 in the flue gas is absorbed by composition, fuel additives, flue gas temperatures the slurry droplets and reacts with the calcium hy- and moisture content, and even weather conditions. droxide of the slurry to form calcium sulfite. Evapo- ESP’s are frequently used with and ahead of flue ration of the water in the slurry droplets occurs si- gas washing and desulfurization systems. They may multaneously with the reaction. The dry flue gas be either hot precipitators ahead of the air preheater then travels to a bag filter system and then to the in the gas path or cold precipitators after the air pre- boiler stack. The bag filter system collects the boiler heater. Hot precipitators are more expensive be- exit solid particles and the dried reaction products. cause of the larger volume of gas to be handled and Additional remaining SO2 and SO3 are removed by temperature influence on materials. But they are the flue gas filtering through the accumulation on sometimes necessary for low sulfur fuels where cold the surface of the bag filters, Dry scrubbers permit precipitators are relatively inefficient. the use of coal with a sulfur content as high as 3 per- (c) Bag filters. Effective particulate removal cent. may be obtained with bag filter systems or bag (3) Induced draft fan requirements. Induced houses, which mechanically filter the gas by passage draft fans will be designed with sufficient capacity through specially designed filter fabric surfaces. to produce the required flow while overcoming the Bag filters are especially effective on very fine parti- static pressure losses associated with the ductwork, cles, and at relatively low flue gas temperatures. economizer, air preheater, and air pollution control They may be used to improve or upgrade other par- equipment under all operating (clean and dirt y) con- ticulate collection systems such as centrifugal col- ditions. lectors. Also they are probably the most economic (4) Waste removal. Flue gas cleanup systems choice for most medium and small size coal fired usually produce substantial quantities of waste steam generators. products, often much greater in mass than the sub- (d) Flue gas desulfurization. While various stances actually removed from the exit gases. De- gaseous pollutants are subject to environmental sign and arrangement must allow for dewatering control and limitation, the pollutants which must be and stabilization of FGD sludge, removal, storage removed from the power plant flue gases are the ox- and disposal of waste products with due regard for ides of sulfur (SO2 and SO3). Many flue gas desulfuri- environmental impacts. ztion (FGD) scrubbing systems to control SO2 and SO3stack emission have been installed and oper- 3-12. Minor auxiliary systems ated, with wide variations in effectiveness, reliabil- Various minor auxiliary systems and components ity, longevity and cost. For small or medium sized are vital parts of the steam generator. power plants, FGD systems should be avoided if a. Piping and valves. Various piping systems are possible by the use of low sulfur fuel. If the parame- defined as parts of the complete boiler (refer to the ters of the project indicate that a FGD system is re- ASME Boiler Code), and must be designed for safe quired, adequate allowances for redundancy, capital and effective service; this includes steam and feed- cost, operating costs, space, and environmental im- water piping, fuel piping, blowdown piping, safety pact will be made. Alternatively, a fluidized bed and control valve piping, isolation valves, drips, boiler (para. 3-10 c) may be a better economic choice drains and instrument connections. for such a project. b. Controls and instruments. Superheater and (1) Wet scrubbers utilize either limestone, ‘burner management controls are best purchased lime, or a combination of lime and soda ash as sor- along with the steam generator so that there will be bents for the SO2 and SO3 in the boiler flue gas integrated steam temperature and burner systems. stream. A mixed slurry of the sorbent material is c. Soot blowers. Continuous or frequent on line sprayed into the flue gas duct where it mixes with cleaning of furnace, boiler economizer, and air pre- and wets the particulate in the gas stream. The S02 heater heating surfaces is required to maintain per- and S09 reacts with the calcium hydroxide of the formance and efficiency. Soot blower systems, slurry to form calcium sulfate. The gas then contin- steam or air operated, will be provided for this pur- ues to a separator tower where the solids and excess pose. The selection of steam or air for soot blowing solution settle and separate from the water vapor is an economic choice and will be evaluated in terms saturated gas stream which vents to the atmosphere of steam and makeup water vs. compressed air costs through the boiler stack. Wet scrubbers permit the with due allowance for capital and operating cost use of coal with a sulfur content as high as 5 percent. components. (2) Dry scrubbers generally utilize a diluted solution of slaked lime slurry which is atomized by 3-25k
  • TM 5-811-6 Section Ill. FUEL HANDLING AND STORAGE SYSTEMS3-13. Introduction of the power plant facilities. Time for unloading will a. Purpose. Figure 3-10 is a block diagram illus- be analyzed and unloading pump(s) optimized fortrating the various steps and equipment required the circumstances and oil quantities involved.for a solid fuel storage and handling system. Heavier fuel oils are loaded into transport tanks hot b. Fuels for consideration. Equipment required and cool during delivery. Steam supply for tank carfor a system depends on the type of fuel or fuels heaters will be provided at the plant if it is expectedburned. The three major types of fuels utilized for that the temperature of the oil delivered will be be-steam raising are gaseous, liquid and solid. low the 120 to 150ºF. range. (2) Storage of the fuel oil will be in two tanks so3-14. Typical fuel oil storage and han- as to provide more versatility for tank cleanout in- dling system spection and repair. A minimum of 30 days storageThe usual power plant fuel oil storage and handling capacity at maximum expected power plant loadsystem includes: (maximum steaming capacity of all boilers with a. Unloading and storage. maximum expected turbine generator output and (1) Unloading pumps will be supplied, as re- maximum export steam, if any) will be provided.quired for the type of delivery system used, as part Factors such as reliability of supply and whether Figure 3-10. Coal handling system diagram.3-26
  • TM 5-811-6 backup power is available from other sources may controls include combustion controls, burner man- result in additional storage requirements. Space for agement system, control valves and shut off valves. future tanks will be allocated where additional boil- ers are planned, but storage capacity will not be pro- 3-15. Coal handling and storage systems vided initially. a. Available systems. The following principal sys- (3) Storage tank(s) for heavy oils will be heated tems will be used as appropriate for handling, stor- with a suction type heater, a continuous coil extend- ing and reclaiming coal: ing over the bottom of the tank, or a combination of (1) Relatively small to intermediate system; both types of surfaces. Steam is usually the most coal purchases sized and washed. A system with a economical heating medium although hot water can track or truck (or combined track/truck) hopper, be considered depending on the temperatures at bucket elevator with feeder, coal silo, spouts and which low level heat is available in the power plant. chutes, and a dust collecting system will be used. Tank exterior insulation will be provided. Elevator will be arranged to discharge via closed b. Fuelpumps and heaters. chute into one or two silos, or spouted to a ground (1) Fuel oil forwarding pumps to transfer oil pile for moving into dead storage by bulldozer. Re- from bulk storage to the burner pumps will be pro- claim from dead storage will be by means of bulldoz- vided. Both forwarding and burner pumps should be er to track/truck hopper. selected with at least 10 percent excess capacity (2) Intermediate system; coal purchased sized over maximum burning rate in the boilers. Sizing and washed. This will be similar to the system de- will consider additional pumps for future boilers and scribed in (1) above but will use an enclosed skip pressure requirements will be selected for pipe fric- hoist instead of a bucket elevator for conveying coal tion, control valves, heater pressure drops, and to top of silo. burners. A reasonable selection would be one pump (3) Intermediate system alternatives. For more per boiler with a common spare if the system is de- than two boilers, an overbunker flight or belt con- signed for a common supply to all boilers. For high veyor will be used. If mine run, uncrushed coal pressure mechanical atomizing burners, each boiler proves economical, a crusher with feeder will be in- may also have its own metering pump with spare. stalled in association with the track/truck hopper. (2) Pumps may be either centrifugal or positive (4) Larger systems, usually with mine run coal. displacement. Positive displacement pumps will be A larger system will include track or truck (or com- specified for the heavier fuel oils. Centrifugal pumps bined track/truck) unloading hopper, separate dead will be specified for crude oils. Where absolute relia- storage reclaim hoppers, inclined belt conveyors ability is required, a spare pump driven by a steam with appropriate feeders, transfer towers, vibrating turbine with gear reducer will be used. For “black screens, magnetic separators, crusher(s), overbunk- starts, ” or where a steam turbine may be inconven- er conveyor(s) with automatic tripper, weighingient, a dc motor driver may be selected for use for equipment, sampling equipment, silos, dust collect-relatively short periods. ing system(s), fire protection, and like items. Where (3) At least two fuel oil heaters will be used for two or more types of coal are burned (e.g., high andreliability and to facilitate maintenance. Typical low sulphur), blending facilities will be required.heater design for Bunker C! fuel oil will provide for (5) For cold climates. All systems, regardless oftemperature increases from 100 to 230° F using size, which receive coal by railroad will require carsteam or hot water for heating medium. thawing facilities and car shakeouts for loosening c. Piping system. frozen coal. These facilities will not be provided for (1) The piping system will be designed to main- truck unloading because truck runs are usuallytain pressure by recirculating excess oil to the bulk short.storage tank. The burner pumps also will circulate b. Selection of handling capacity. Coal handlingback to the storage tank. A recirculation connection system capacity will be selected so that ultimatewill be provided at each burner for startup. It will be planned 24-hour coal consumption of the plant atmanually valved and shut off after burner is suc- maximum expected power plant load can be unload-cessfully lit off and operating smoothly. ed or reclaimed in not more than 7-1/2 hours, or within (2) Piping systems will be adapted to the type the time span of one shift after allowance of a 1/2-hourof burner utilized. Steam atomizing burners will margin for preparation and cleanup time. The hand-have “blowback” connections to cleanse burners of ling capacity should be calculated using the worstfuel with steam on shutdown. Mechanical atomizing (lowest heating value) coal which may be burned inburner piping will be designed to suit the require- the future and a maximum steam capacity boiler ef-ments of the burner. ficiency at least 3 percent less than guaranteed by d. Instruments and control. Instruments and boiler manufacturer. 3-27
  • TM 5-811-6 c. Outdoor storage pile. The size of the outdoor typical bucket elevator grade mounted silo arrange-storage pile will be based on not less than 90 days of ment for a small or medium sized steam generatingthe ultimate planned 24-hour coal consumption of facility.the plant at maximum expected power plant load. (2) For large sized spreader stoker fired plants,Some power plants, particularly existing plants silo type overhead construction will be specified. Itwhich are being rehabilitated or expanded, will have will be fabricated of structural steel or reinforcedoutdoor space limitations or are situated so that it is concrete with stainless steel lined conical bottoms.environmentally inadvisable to have a substantial (3) For small or medium sized plants combinedoutdoor coal pile. live and reserve storage in the silo will be not less d. Plant Storage. than 3 days at 60 percent of maximum expected (1) For small or medium sized spreader stoker load of the boiler(s) being supplied from the silo sofired plants, grade mounted silo storage will be spe- that reserves from the outside storage pile need notcified with a live storage shelf above and a reserve be drawn upon during weekends when operatingstorage space below. Usually arranged with one silo staff is reduced. For large sized plants this storageper boiler and the silo located on the outside of the requirement will be 1 day.firing aisle opposite the boiler, the live storage shelfwill be placed high enough so that the spout to the e. Equipment and systems.stoker hopper or coal scale above the hopper (1) Bucket elevators. Bucket elevators will beemerges at a point high enough for the spout angle chain and bucket type. For relatively small installa-to be not less than 60 degrees from the horizontal. tions the belt and bucket type is feasible althoughThe reserve storage below the live storage shelf will not as rugged as the chain and bucket type. Typicalbe arranged to recirculate back to the loading point bucket elevator system is shown in Figure 3-11.of the elevator so that coal can be raised to the top of (2) Skip hoists. Because of the requirement forthe live storage shelf as needed. Figure 3-11 shows a dust suppression and equipment closure dictated by
  • TM 5-811-6environmental considerations, skip hoists will not ceived” and’ ‘as fired” samples for large systems.be specified. (f) Chutes, hoppers and skirts, as required, (3) Belt conveyors. Belt conveyors will be se- fabricated of continuously welded steel for dust lected for speeds not in excess of 500 to 550 feet per tightness and with wearing surfaces lined withminute. They will be specified with roller bearings stainless steel. Vibrators and poke holes will be pro-for pulleys and idlers, with heavy duty belts, and vided at all points subject to coal stoppage or hang-with rugged helical or herringbone gear drive units. up. (4) Feeders. Feeders are required to transfer (g) Car shakeout and a thaw shed for loosen-coal at a uniform rate from each unloading and inter- ing frozen coal from railroad cars.mediate hopper to the conveyor. Such feeders will be (h) Dust control systems as required through-of the reciprocating plate or vibrating pan type with out the coal handling areas. All handling equip-single or variable speed drive. Reciprocating type ment—hoppers, conveyors and galleries-will be en-feeders will be used for smaller installations; the vi- closed in dust tight casings or building shells andbrating type will be used for larger systems. provided with negative pressure ventilation com- (5) Miscellaneous. The following items are re- plete with heated air supply, exhaust blowers, sepa-quired as noted rators, and bag filters for removing dust from ex- (a) Magnetic separators for removal of tramp hausted air. In addition, high dust concentrationiron from mine run coal. areas located outside which cannot be enclosed, such (b) Weigh scale at each boiler and, for larger as unloading and reclaim hoppers, will be providedinstallations, for weighing in coal as received. Scales with spray type dust suppression equipment.will be of the belt type with temperature compensat- (i) Fire protection system of the sprinklered load cell. For very small installations, a low cost type.displacement type scale for each boiler will be used. (j) Freeze protection for any water piping lo- (c) Coal crusher for mine run coal; for large in- cated outdoors or in unheated closures as providedstallations the crusher will be preceded by vibrating for dust suppression or fire protection systems.(scalping) screens for separating out and by-passing (k) A vacuum cleaning system for mainte-fines around the crusher. nance of coal handling systems having galleries and (d) Traveling tripper for overbunker conveyor equipment enclosures. serving a number of bunkers in series. (l) System of controls for sequencing and (e) One or more coal samplers to check “as re- monitoring entire coal handling system. Section IV. ASH HANDLING SYSTEMS3-16. Introduction crease efficiency, although this procedure does in- a. Background. crease the dust loading on the collection equipment (1) Most gaseous fuels burn cleanly, and the downstream of the last hopper from which such ma-amount of incombustible material is so small that it terial is reinfected.can be safely ignored. When liquid or solid fuel is (3) It is mandatory to install precipitators orfired in a boiler, however, the incombustible materi- baghouses on all new coal fired boilers for finalal, or ash, together with a small amount of unburned cleanup of the flue gases prior to their ejection to at-carbon chiefly in the form of soot or cinders, collects mosphere. But in most regions of the United States,in the bottom of the furnace or is carried out in a mechanical collectors alone are adequate for heavylightweight, finely divided form usually known oil fired boilers because of the conventionally lowloosely as “fly ash.” Collection of the bottom ash ash content of this type of fuel. An investigation isfrom combustion of coal has never been a problem as required, however, for each particular oil fired unitthe ash is heavy and easily directed into hoppers being considered.which may be dry or filled with water, (2) Current ash collection technology is capable b. Purpose. It is the purpose of the ash handlingof removing up to 99 percent or more of all fly ash system to:from the furnace gases by utilizing a precipitator or (1) Collect the bottom ash from coal-firedbaghouse, often in combination with a mechanical spreader stoker or AFBC boilers and to convey itcollector. Heavier fly ash particles collected from dry by vacuum or hydraulically by liquid pressurethe boiler gas passages and mechanical collectors of- to a temporary or permanent storage terminal. Theten have a high percentage of unburned carbon con- latter may be a storage bin or silo for ultimate trans- tent, particularly in the case of spreader stoker fired fer to rail or truck for transport to a remote disposalboilers; this heavier material may be reinfected into area, or it maybe an on-site fill area or storage pondthe furnace to reduce unburned carbon losses and in- for the larger systems where the power plant site is 3-29
  • TM 5-811-6adequate and environmentally acceptable for this or mechanical exhauster for creating the vacuumpurpose. (Figure 3-12). This typical plant would probably (2) Collect fly ash and to convey it dry to tem- have a traveling grate spreader stoker, a mechanicalporary or permanent storage as described above for collector, and a baghouse; in all likelihood, no on-sitebottom ash. Fly ash, being very light, will be wetted ash disposal area would be available.and is mixed with bottom ash prior to disposal to (3) The ash system for the typical plant will in-prevent a severe dust problem. clude the following for each boiler: (a) A refractory lined bottom ash hopper to3-17. Description of major components receive the discharge from the traveling grate. A a. Typical oil fired system. Oil fired boilers do not clinker grinder is not required for a spreader stokerrequire any bottom ash removal facilities, since ash although adequate poke holes should be incorpor-and unburned carbon are light and carried out with ated into the outlet sections of the hopper.the furnace exit gas. A mechanical collector may be (b) Gas passage fly ash hoppers as requiredrequired for small or intermediate sized boilers hav- by the boiler design for boiler proper, economizer,ing steaming rates of 200,000 pounds per hour or and air heater.less. The fly ash from the gas passage and mechani- (c) Collector fly ash hoppers for the mechani-cal collector hoppers can usually be handled manu- cal collector and baghouse.ally because of the small amount of fly ash (soot) col- (d) Air lock valves, one at each hopper outlet,lected. The soot from the fuel oil is greasy and can manually or automatically operated as selected bycoagulate at atmospheric temperatures making it the design engineer.difficult to handle. To overcome this, hoppers (4) And the following items are common to allshould be heated with steam, hot water, or electric boilers in the plant:power. Hoppers will be equipped with an outlet (a) Ash collecting piping fabricated of specialvalve having an air lock and a means of attaching hardened ferro-alloy to transfer bottom and fly ashdisposable paper bags sized to permit manual hand- to Storage.ling. Each hopper will be selected so that it need not (b) Vacuum producing equipment, steam orbe evacuated more than once every few days. If boil- mechanical exhauster as may prove economical. Forer size and estimated soot/ash loading is such that plants with substantial export steam and with lowmanual handling becomes burdensome, a vacuum or quality, relatively inexpensive makeup require-hydraulic system as described below should be con- ments, steam will be the choice. For plants withsidered. high quality, expensive makeup requirements, b. Typical ash handling system for small or inter consideration should be given to the higher cost me-mediate sized coal fired boilers; chanical exhauster. (1) Plant fuel burning rates and ash content of (c) Primary and secondary mechanical (centri-coal are critical in sizing the ash handling system. fugal) separators and baghouse filter are used toSizing criteria will provide for selecting hoppers and clean the dust out of the ash handling system ex-handling equipment so that ash does not have to be haust prior to discharge to the atmosphere. Thisremoved more frequently than once each 8-hour equipment is mounted on top of the silo.shift using the highest ash content coal anticipated (d) Reinforced concrete or vitrified tile over-and with boiler at maximum continuous steaming head silo with separator and air lock for loading silocapacity. For the smaller, non-automatic system it with a “dustless” unloader designed to dampenmay be cost effective to select hoppers and equip ashes as they are unloaded into a truck or railroadment which will permit operating at 60 percent of car for transport to remote disposal.maximum steam capacity for 3 days without remov- (e) Automatic control system for sequencinging ash to facilitate operating with a minimum operation of the system. Usually the manual initia-weekend crew. tion of such a system starts the exhauster and then (2) For a typical military power plant, the most removes bottom and fly ash from each separator col-economical selection for both bottom and fly ash dis- lection point in a predetermined sequence. Ash un-posal is a vacuum type dry system with a steam jet loading to vehicles is separately controlled. Section V. TURBINES AND AUXILIARY SYSTEMS3-18. Turbine prime movers generator and its associated electrical accessories,The following paragraphs on turbine generators dis- refer to Chapter 4.cuss size and other overall characteristics of the tur- a. Size and type ranges. Steam turbine gener-bine generator set. For detailed discussion of the ators for military installations will fall into the fol-3-30
  • Figure 3-12. Pneumatic ash handling systems—variations.
  • TM 5-811-6lowing size ranges: 3-19. Generators (1) Small turbine generators. From 500 to about For purposes of this section, it is noted that the gen-2500 kW rated capacity, turbine generators will erator must be mechanically compatible with theusually be single stage, geared units without extrac- driving turbine, coupling, lubrication system, andtion openings for either back pressure or condensing vibration characteristics (see Chapter 4 for gener-service. Rated condensing pressures for single stage ator details).turbines range from 3 to 6 inches Hga. Exhaustpressures for back pressure units in cogeneration 3-20. Turbine featuresservice typically range from 15 psig to 250 psig. a. General. Turbine construction may be general- (2) Intermediate turbine generators. F r o m ly classified as high or low pressure, single or multi-about 2500 to 10,000 kW rated capacity, turbine stage, back pressure on condensing, direct drive orgenerators will be either multi-stage, multi-valve gear reducer drive, and for electric generator or formachines with two pole direct drive generators turn- mechanical drive service.ing at 3600 rpm, or high speed turbines with gear re- (1) Shell pressures. High or low pressure con-ducers may also be used in this size range. Units are struction refers generally to the internal pressuresequipped with either uncontrolled or controlled (au- to be contained by the main shell or casing parts.tomatic) extraction openings. Below 4000 kW, there (2) Single us. multi-stage. Single or multi-stagewill be one or two openings with steam pressures up designs are selected to suit the general size,to 600 psig and 750°F. From 4000 kW to 10,000 enthalpy drops and performance requirements ofkW, turbines will be provided with two to four un- the turbine. Multi-stage machines are much morecontrolled extraction openings, or one or two auto- expensive but are also considerably more efficient.matic extraction openings. These turbines would Single stage machines are always less expensive,have initial steam conditions from 600 psig to 1250 simpler and less efficient. They may have up topsig, and 750°F to 900°F. Typical initial steam con- three velocity wheels of blading with reentry sta-ditions would be 600 psig, 825º For 850 psig, 900°F. tionary vanes between wheels to improve efficiency. (3) Large turbine generators. In the capacity As casing pressure of single stage turbines are equalrange 10,000 to 30,000 kW, turbine generators will to exhaust pressures, the design of seals and bear-be direct drive, multi-stage, multi-valve units. For ings is relatively simple.electric power generator applications, from two to (3) Back pressure vs. condensing. Selection of afive uncontrolled extraction openings will be re- back pressure or a condensing turbine is dependentquired for feedwater heating. In cogeneration appli- on the plant function and cycle parameters. (Seecations which include the provision of process or Chapter 3, Section I for discussion of cycles.) Con-heating steam along with power generation, one au- densing machines are larger and more complex withtomatic extraction opening will be required for each high pressure and vacuum sealing provisions, steamlevel of processor heating steam pressure specified, condensers, stage feedwater heating, extensive lubealong with uncontrolled extraction openings for oil systems and valve gear, and related auxiliary fea-feedwater heating. Initial steam conditions range up tures.to 1450 psig and 950 “F with condensing pressures (4) Direct drive vs. geared sets. Direct drive tur-from 1 1/2 to 4 inches Hga. bines generators turn the turbine shaft at generator b. Turbine features and accessories. In all size speed. Units 2500 kW and larger are normally directranges, turbine generator sets are supplied by the connected. Small, and especially single stage, tur-manufacturer with basic accessories as follows: bines may be gear driven for compactness and for (1) Generator with cooling system, excitation single stage economy. Gear reducers add complex-and voltage regulator, coupling, and speed reduc- ity and energy losses to the turbine and should betion gear, if used. used only after careful consideration of overall econ- (2) Turbine and generator (and gear) lubrication omy and reliability.system including tank, pumps, piping, and controls. (5) Mechanical drive. Main turbine units in (3) Load speed governor, emergency overspeed power plants drive electrical generators, althoughgovernor, and emergency inlet steam trip valve with large pumps or air compressors may also be drivenrelated hydraulic piping. by large turbines. In this event, the turbines are (4) Full rigid base plate in small sizes or sepa- called “mechanical drive” turbines. Mechanicalrate mounting sole plates for installation in concrete drive turbines are usually variable speed units withpedestal for larger units. special governing equipment to adapt to best econ- (5) Insulation and jacketing, instruments, turn- omy balance between driver (turbine) and driven ma-ing gear and special tools. chine. Small auxiliary turbines for cycle pumps,3-32
  • TM 5-811-6fans, or air compressor drives are usually single duction through the turbine bleed (extraction)stage, back pressure, direct drive type designed for points.mechanical simplicity and reliability. Both constant c. Single and multi-valve arrangements. What-speed and variable speed governors are used de- ever type of governor is used, it will modulate thepending on the application. turbine inlet valves to regulate steam flow and tur- b. Arrangement. Turbine generators are horizon- bine output. For machines expected to operate ex-tal shaft type with horizontally split casings. Rela- tensively at low or partial loads, multi-valve ar-tively small mechanical drive turbines may be built rangements improve economy. Single valve tur-with vertical shafts. Turbine rotor shaft is usually bines, in general, have equal economy and efficiencysupported in two sleeve type, self aligning bearings, at rated load, but lower part load efficiencies.sealed and protected from internal casing steamconditions. Output shaft is coupled to the shaft of 3-22. Turning gearthe generator which is provided with its own enclo- a. General. For turbines sized 10,000 kW andsure but is always mounted on the same foundation larger, a motor operated turning gear is required toas the turbine. prevent the bowing of the turbine rotor created by (1) Balance. Balanced and integrated design of the temperature differential existing between thethe turbine, coupling and generator moving parts is upper and lower turbine casings during the long pe-important to successful operation, and freedom riod after shutdown in which the turbine cools down.from torsional or lateral vibrations as well as pre- The turbine cannot be restarted until it has com-vention of expansion damage are essential. pletely cooled down without risk of damage to inter- (2) Foundations. Foundations and pedestals for state packing and decrease of turbine efficiency,turbine generators will be carefully designed to ac- causing delays in restarting. The turning gear iscommodate and protect the turbine generator, con- mounted at the exhaust end of the turbine and isdenser, and associated equipment. Strength, mass, used to turn the rotor at a speed of 1 to 4 rpm whenstiffness, and vibration characteristics must be con- the turbine is shut down in order to permit uniformsidered. Most turbine generator pedestals in the cooling of the rotor. Turning gear is also used duringUnited States are constructed of massive concrete. startup to evenly warm up the rotor before rolling the turbine with steam and as a jacking device for3-21. Governing and control turning the rotor as required for inspection and a. Turbine generators speed/load control. Electri- maintenance when the turbine is shut down.cal generator output is in the form of synchronized b. Arrangement and controls. The turning gearac electrical power, causing the generator and driv- will consist of a horizontal electric motor with a seting turbine to rotate at exactly the same speed (or of gear chains and a clutching arrangement whichfrequency) as other synchronized generators con- engages a gear ring on the shaft of the turbine. Itsnected into the common network. Basic speed/load controls are arranged for local and/or remote start-governing equipment is designed to allow each unit ing and to automatically disengage when the tur-to hold its own load steady at constant frequency, or bine reaches a predetermined speed during startupto accept its share of load variations, as the common with steam. It is also arranged to automatically en-frequency rises and falls. Very small machines may gage when the turbine has been shut down and de-use direct mechanical governors, but the bulk of the celerated to a sufficiently slow speed. Indicatingunits will use either mechanical-hydraulic governing lights will be provided to indicate the disengaged orsystems or electrohydraulic systems. Non-reheat engaged status of the turning gear and an interlockcondensing units 5000 kW and larger and back pres- provided to prevent the operation of the turningsure units without automatic extraction will be gear if the pressure in the turbine lubrication oil sys-equipped with mechanical-hydraulic governing. For tem is below a predetermined safe setting.automatic extraction units larger than 20,000 kW,governing will be specified either with a mechanical- 3-23. Lubrication systemshydraulic or an electro-hydraulic system. a. General. Every turbine and its driven machine b. Overspeed governors. All turbines require sep- or generator requires adequate lubricating oil suparate safety or overspeed governing systems to in- ply including pressurization, filtration, oil cooling,sure inlet steam interruption if the machine exceeds and emergency provisions to insure lubrication ina safe speed for any reason. The emergency gover- the event of a failure of main oil supply. For a typ-nor closes a specially designed stop valve which not ical turbine generator, an integrated lube oil storageonly shuts off steam flow but also trips various safe- tank with built in normal and emergency pumps isty devices to prevent overspeed by flash steam in- usually provided. Oil cooling may be by means of an 3-33
  • TM 5-811-6 external or internal water cooled heat exchanger. Oil extracted steam will not be used or routed to any temperatures should be monitored and controlled, substantial uses except for feedwater heating. and heating may be required for startup. b. Automatic extraction. Controlled or automatic b. Oil Pumps. Two full capacity main lube oil extraction turbines are more elaborate and equippedpumps will be provided. One will be directly driven with variable internal orifices or valves to modulatefrom the turbine shaft for multi-stage machines. internal steam flows so as to maintain extractionThe second full size pump will be ac electric motor pressures within specified ranges. Automatic ex-driven. An emergency dc motor driven or turbine- traction machine governors provide automatic self-driven backup pump will be specified to allow or- contained modulation of the internal flow orifices orderly shutdown during normal startup and shut- valves, using hydraulic operators. Automatic ex-down when the shaft driven pump cannot maintain traction governing systems can also be adapted topressure, or after main pump failure, or in the event respond to external controls or cycle parameters toof failure of the power supply to the ac electric mo- permit extraction pressures to adjust to changingtor driven pumps. cycle conditions. c. Filtration. Strainers and filters are necessary c. Extraction turbine selection. Any automaticfor the protection and longevity of lubricated parts. extraction turbine is more expensive than itsFilters and strainers should be arranged in pairs for straight uncontrolled extraction counterpart of sim-on line cleaning, inspection, and maintenance. Larg- ilar size, capacity and type; its selection and use re-er turbine generator units are sometimes equipped quire comprehensive planning studies and economicwith special off base lubrication systems to provide analysis for justification. Sometimes the same ob-separate, high quality filtering. jective can be achieved by selecting two units, one of which is an uncontrolled extraction-condensing ma- 3-24. Extraction features chine and the other a back pressure machine. a. Uncontrolled extraction systems. Uncontrolled 3-25. Instruments and special toolsbleed or extraction openings are merely nozzles in a. Operating instruments. Each turbine will bethe turbine shell between stages through which rela- equipped with appropriate instruments and alarmstively limited amounts of steam may be extracted to monitor normal and abnormal operating condi-for stage feedwater heating. Such openings add tions including speed, vibration, shell and rotor ex-little to the turbine cost as compared with the cost pansions, steam and metal temperatures, rotorof feedwater heaters, piping, and controls. Turbines straightness, turning gear operation, and variousso equipped are usually rated and will have efficien- steam, oil and hydraulic system pressures.cies and performance based on normal extraction b. Special took. Particularly for larger machines,pressures and regenerative feedwater heating calcu- complete sets of special tools, lifting bars, and re-lations. Uncontrolled extraction opening pressures lated special items are required for organized and ef-will vary in proportion to turbine steam flow, and fective erection and maintenance. Section VI. CONDENSER AND CIRCULATING WATERSYSTEM 3-26. Introduction ing water can be a natural body of water such as an a. Purpose. ocean, a river, or a lake, or it can be from a recircu- (1) The primary purpose of a condenser and cir- lated source such as a cooling tower or cooling pond.culating water system is to remove the latent heat In the second step, the heated circulating water isfrom the steam exhausted from the exhaust end of rejected to the natural body of water or recirculatedthe steam turbine prime mover, and to transfer the source which, in turn, transfers the heat to the at-latent heat so removed to the circulating water mosphere, principally by evaporative cooling effect.which is the medium for dissipating this heat to the b. Equipment required—general. Equipment re-atmosphere. A secondary purpose is to recover the quired for a system depends on the type of systemcondensate resulting from the phase change in the utilized. There are two basic types of con-exhaust steam and to recirculate it as the working densers: surface and direct contact.fluid in the cycle. There are also two basic types of cooling sys- (2) Practically, these purposes are accom- tems:plished in two steps. In the first step, the condenser Once through; andis supplied with circulating water which serves as a Recirculating type, including cooling ponds, me-medium for absorbing the latent heat in the con- chanical draft cooling towers, natural draft coolingdensing exhaust steam. The source of this circulat- towers, or a combination of a pond and tower.3-34
  • TM 5-811-6 3-27. Description of major components to permit variations in level for the condensate con- a. Surface condensers. trol system. (1) General description. These units are de- (4) Air removal offtakes. One or more air off- signed as shell and tube heat exchangers. A surface takes in the steam space lead accumulating air to condenser consists of a casing or shell with a cham- the air removal pump. ber at each end called a “water box. ” Tube sheets (5) Tubes. separate the two water boxes from the center steam (a) The tubes provide the heat transfer sur- space. Banks of tubes connect the water boxes by face in the condenser are fastened into tube sheets, piercing the tube sheets; the tubes essentially fill usually made of Muntz metal. Modern designs have the shell or steam space. Circulating water pumps tubes rolled into both tube sheets; for ultra-tight- force the cooling (circulating] water through the wa- ness, alloy steel tubes may be welded into tube ter boxes and the connecting tubes. Uncontami- sheets of appropriate material. Admiralty is the . most common tube material and frequently is satis- nated condensate is recovered in surface condensers since the cooling water does not mix with the con- factory for once through systems using fresh water densing steam. Steam pressure in a condenser (or and for recirculating systems. Tube material in the * vacuum) depends mainly on the flow rate and tem- “off gas” section of the condenser should be stain- perature of the cooling water and on the effective- less steel because of the highly corrosive effects of ness of air removal equipment. carbon dioxide and ammonia in the presence of (2) Passes and water boxes. moisture and oxygen. These gases are most concen- (a) Tubing and water boxes may be arranged trated in this section. Other typical condenser tube for single pass or two pass flow of water through the materials include: shell. In single pass units, water enters the water (1) Cupronickel box at one end of the tubes, flows once through all (2) Aluminum bronze the tubes in parallel, and leaves through the outlet (3) Aluminim brass water box at the opposite end of the tubes. In two (4) Various grades of stainless steel pass units, water flows through the bottom half of (b) Condenser tube water velocities range the tubes (sometimes the top half) in one direction, from 6 to 9 feet per second (Table 3- 12). Higher flow reverses in the far end water box, and returns rates raise pumping power requirements and erodeL through the upper or lower half of the tubes to the tubes at their entrances, thus shortening their life near water box. Water enters and leaves through the expectancy. Lower velocities are inefficient from a near water box which is divided into two chambers heat transfer point of view. Tubes are generally in- by a horizontal plate. The far end water box is undi- stalled with an upwardly bowed arc. This provides vided to permit reversal of flow. for thermal expansion, aids drainage in a shutdown (b) For a relatively large cooling water source condenser, and helps prevent tube vibration. and low circulating water pump heads (hence low b. Direct contact condensers. Direct contact con- unit pumping energy costs), single pass units will be densers will not be specified.. c. Condenser auxiliaries. used. For limited cooling water supplies and high circulating water pump heads (hence high unit (1) General. A condenser needs equipment and pumping energy costs), two pass condensers will be conduits to move cooling water through the tubes,< specified. In all cases, the overall condenser-circulat- remove air from the steam space, and extract con- ing water system must be optimized by the designer densate from the hotwell. Such equipment and con- to arrive at the best combination of condenser sur- duits will include: face, temperature, vacuum, circulating water (a) Circulating water pumps. pumps, piping, and ultimate heat rejection equip- (b) Condensate or hotwell pumps. ment. (c) Air removal equipment and piping. (c) Most large condensers, in addition to the (d) Priming ejectors. inlet waterbox horizontal division, have vertical par- (e) Atmospheric relief valve. titions to give two separate parallel flow paths (f) Inlet water tunnel, piping, canal, or com- through the shell. This permits taking half the con- bination of these conduits. densing surface our of service for cleaning while wa- (g) Discharge water tunnel, piping or canal, ter flows through the other half to keep the unit run- or combination of these conduits. ning at reduced load. (2) Circulating water pumps. A condenser uses (3) Hot well. The hot well stores the condensate 75 to 100 pounds of circulating water per pound of‘L and keeps a net positive suction head on the conden- steam condensed. Hence, large units need substan- sate pumps. Hot well will have a capacity of at least tial water flows; to keep pump work to a minimum, 3 minutes maximum condensing load for surges and top of condenser water boxes in a closed system will 3-35
  • TM 5-811-6 Table 3-12. Condenser Tube Design Velocities. Material Design Velocities fps Fresh Water Brackish Water Salt Water Admiralty Metal 7.0 (1) (1) Aluminum Brass(2) 8.0 7.0 7.0 Copper-Nickel Alloys: 90-10 8.0 8.0 7.0 to 7.5 80-20 8.0 8.0 7.0 to 7.5 70-30 9.0 9.0 8.0 to 8.5 Stainless Steel 9.0 to 9.5 8 . 0( 3 ) 8 . 0( 3 ) Aluminum (4) 8.0 7.0 6.8 NOTES : (1) Not normally used, but if used, velocity shall not exceed 6.0 fps. (2) For salt and brackish water , velocities in excess of 6.8 fps are not recommended. (3) Minimum velocity of 5.5 fps to prevent chloride attack. (4) Not recommended for circulating water containing high concentration of heavy metal salts. U.S. Army Corps of Engineersnot be higher than approximately 27 feet above min- pumps handle much smaller flows than the circulat-imum water source level which permits siphon oper- ing water pumps. They must develop heads to pushation without imposing static head. With a siphon water through atmospheric pressure, pipe and con-system, air bubbles tend to migrate to the top of the trol valve friction, closed heater water circuit fric-system and must be removed with vacuum-produc- tion, and the elevation of the deaerator storage tank.ing equipment. The circulating pumps then need to These pumps take suction at low pressure of twodevelop only enough head to overcome the flow re- inches Hg absolute or less and handle water at sat-sistance of the circulating water circuit. Circulating uration temperature; to prevent flashing of the con-pumps for condensers are generally of the centrif- densate, they are mounted below the hotwell to re-ugal type for horizontal pumps, and either mixed ceive a net positive suction head. Modern verticalflow or propeller type for vertical pumps. Vertical “can” type pumps will be used. Specially designedpumps will be specified because of their adaptability pump glands prevent air leakage into the conden-for intake structures and their ability to handle high sate, and vents from the pump connecting to the va-capacities at relatively low heads. Pump material por space in the condenser prevent vapor binding.will be selected for long life. (4) Spare pumps. Two 100 percent pumps for (3) Condensate pumps. Condensate (or hotwell) both circulating water and condensate service will
  • TM 5-811-6 be specified. If the circulating water system serves (a) Intake structure. more than one condenser, there will be one circulat- (b) Discharge, or outfall. ing pump per condenser with an extra pump as a (c) Trash racks. common spare. Condensate pump capacity will be (d) Traveling screens. sized to handle the maximum condenser load under (e) Circulating water pumps. any condition of operation (e.g., with automatic ex- (f) Circulating water pump structure (indoor traction to heating or process shutoff and including or outdoor). all feedwater heater drains and miscellaneous drips (g) Circulating water canals, tunnels, and received by the condenser.) pipework. (5) Air removal. (2) System operation. (a) Non-condensable gases such as air, carbon (a) The circulating water system functions as dioxide, and hydrogen migrate continuously into follows. Water from an ocean, river, lake, or pond the steam space of a condenser inasmuch as it is the flows either directly from the source to the circulat- lowest pressure region in the cycle. These gases may ing water structure or through conduits which bring enter through leakage at glands, valve bonnets, por- water from offshore; the inlet conduits discharge ous walls, or may be in the throttle steam. Those into a common plenum which is part of the circulat- gases not dissolved by the condensate diffuse ing water pump structure. Water flows through bar throughout the steam space of the condenser. As trash racks which protect the traveling screens from these gases accumulate, their partial pressure raises damage by heavy debris and then through traveling the condenser total pressure and hence decreases ef- screens where smaller debris is removed. For large ficiency of the turbine because of loss of available systems, a motor operated trash rake can be in- energy. The total condenser pressure is: stalled to clear the bar trash racks of heavy debris. Pc = PS + Pa In case the traveling screens become clogged, or to where Ps = steam saturation pressure cor- prevent clogging, they are periodically backwashes responding to steam tempera- by a high pressure water jet system. The backwash ture is returned to the ocean or other body of water. Each Pa = air pressure (moisture free) separate screen well is provided with stop logs and This equation shows that air leakage must be re- sluice gates to allow dewatering for maintenanceL moved constantly to maintain lowest possible vac- purposes. uum for the equipment selected and the particular (b) The water for each screen flows to the suc- exhaust steam loading. In removing this air, it will tion of the circulating water pumps. For small sys- always have some entrained vapor. Because of its tems, two 100-percent capacity pumps will be se- subatmospheric pressure, the mixture must be com- lected while for larger systems, three 50-percent pressed for discharge to atmosphere. pumps will be used. At least one pump is required (b) Although the mass of air leakage to the for standby. Each pump will be equipped with a mo-. condenser may be relatively small because of its torized butterfly valve for isolation purposes. The very low pressure, its removal requires handling of a pumps discharge into a common circulating water large volume by the air removal equipment. The air tunnel or supply pipe which may feed one or more offtakes withdraw the air-vapor moisture from the condensers. Also, a branch line delivers water to the. steam space over a cold section of the condenser booster pumps serving the closed cooling water ex- tubes or through an external cooler, which con- changers. denses part of the moisture and increases the air-to- (c) Both inlet and outlet water boxes of the steam ratio. Steam jets or mechanical vacuum main condensers will be equipped with butterfly pumps receive the mixture and compress it to at- valves for isolation purposes and expansion joints. mosphere pressure. As mentioned above, the system may have the capa- (6) Condenser cleanliness. Surface condenser bility to reverse flow in each of the condenser halves performance depends greatly on the cleanliness of for cleaning the tubes. The frequency and duration the tube water side heat transfer surface. When of the condenser reverse flow or back wash opera- dirty fresh water or sea water is used in the circulat- tion is dictated by operating experience. ing water system, automatic backflush or mechan- (d) The warmed circulating water from the ical cleaning systems will be specified for on line condensers and closed cooling water exchangers is cleaning of the interior condenser tube surfaces. discharged to the ocean, river, lake, or pond via a d. Circulating water system–once through common discharge tunnel. (1) System components. A typical once through (3) Circulating water pump setting. The circu- circulating water system, shown in figure 3-13, con- lating water pumps are designed to remain operable sists of the following components: with the water level at the lowest anticipated eleva- 3-37
  • ITM 5-811-6 NAVFAC DM3 Figure 3-13. Types of circulating water systems.tion of the selected source. This level is a function of e. Circulating water system—recirculating typethe neap tide for an ocean source and seasonal level (1) General discussion.variations for a natural lake or river. Cooling ponds (a) With a once-through system, the evapora-are usually man-made with the level controlled with- tive losses responsible for rejecting heat to the at-in modest limits. The pump motors and valve motor mosphere occur in the natural body of water as theoperators will be located so that no electrical parts warmed circulating water is mixed with the residualwill be immersed in water at the highest anticipated water and is cooled over a period of time by evapora-elevation of the water source. tion and conduction heat transfer. With a recircula- (4) System pressure control. On shutdown of a tion system, the same water constantly circulates;circulating water pump, water hammer is avoided evaporative losses responsible for rejecting heat toby ensuring that the pumps coast down as the pump the atmosphere occur in the cooling equipment andisolation valves close. System hydraulics, circulat- must be replenished at the power plant site. Recircu-ing pump coastdown times, and system isolation lating systems can utilize one of the following forvalve closing times must be analyzed to preclude heat rejection:damage to the system due to water hammer. The (1) A natural draft, hyperbolic cooling tow-condenser tubes and water boxes are to be designed er.for a pressure of approximately 25 psig which is well (2) A mechanical draft cooling tower, us-above the ordinary maximum discharge pressure of ually induced draft.the circulating water pumps, but all equipment (3) A spray pond with a network of pipingmust be protected against surge pressures caused serving banks of spray nozzles.by sudden collapse of system pressure. (b) Very large, man-made ponds which take (5) Inspection and testing. All active compo- advantage of natural evaporative cooling may benents of the circulating water system will be accessi- considered as “recirculating” systems, although forble for inspection during station operation. design purposes of the circulating water system3-38
  • TM 5-811-6 they are once through and hence considered as such ratings for the pumps and condensers will be speci- in paragraph d above. fied. (c) To avoid fogging and plumes which are (4) Cooling tower design. characteristic of cooling towers under certain at- (a) In an induced draft mechanical cooling mospheric conditions in humid climates, so called tower, atmospheric air enters the louvers at the bot- wet-dry cooling towers may be used. These towers tom perimeter of the tower, flows up through the use a combination of finned heat transfer surface fill, usually counterflow to the falling water drop and evaporative cooling to eliminate the fog and vis- lets, and is ejected to the atmosphere in saturated ible plume. The wet-dry types of towers are expen- condition thus carrying off the operating load of sive and not considered in this manual. Hyperbolic heat picked up in the condenser. Placement and ar- towers also are expensive and are not applicable to rangement of the tower or towers on the power sta- units less than 300-500 M W; while spray ponds tion site will be carefully planned to avoid recircula- have limited application (for smaller units) because tion of saturated air back into the tower intake and of the large ground area required and the problem of to prevent drift from the tower depositing on elec- excessive drift. Therefore, the following descriptive trical buses and equipment in the switchyard, road- material applies only to conventional induced draft ways and other areas where the drift could be detri- cooling towers which, except for very special cir- mental. cumstances, will be the choice for a military power (b) Hot circulating water from the condenserplant requiring a recirculating type system. enters the distribution header at the top of the tow- (2) System components. A typical recirculating er. In conventional towers about 75 percent of the system with a mechanical draft cooling tower con- cooling takes place be evaporation and the re-sists of the following components: mainder by heat conduction; the ratio depends on (a) Intake structure which is usually an ex- the humidity of the entering air and various factors.tension of the cooling tower basin. (5) Cooling tower performance. The principal (b) Circulating water pumps. performance factor of a cooling tower is its approach (c) Circulating water piping or tunnels to con- to the wet bulb temperature; this is the difference densers and from condensers to top of cooling tower. between the cold water temperature leaving the tow- (d) Cooling tower with makeup and blowdown er and the wet bulb temperature of the entering air. systems. The smaller the approach, the more efficient and ex- (3) System operation. pensive the tower. Another critical factor is the cool- (a) The recirculating system functions as fol- ing range. This is the difference between the hot wa-lows. Cooled water from the tower basin is directed ter temperature entering the tower and the cold wa-to the circulating water pump pit. The pit is similar ter temperature leaving it is essentially the same asto the intake structure for a once through system ex- the circulating water temperature rise in the conden-cept it is much simpler because trash racks or trav- ser. Practically, tower approaches are 8 to 15°F witheling screens are not required, and the pit setting ranges of 18 to 22°F. Selection of approach andcan be designed without reference to levels of a nat- range for a tower is the subject for an economic opti-ural body of water. The circulating water pumps mization which should include simultaneous selec-pressure the water and direct it to the condensers tion of the condensers as these two major items ofthrough the circulating water discharge piping. A equipment are interdependent.stream of circulating water is taken off from the (6) Cooling tower makeup.main condenser supply and by means of booster (a) Makeup must be continuously added topumps further pressurized as required for bearing the tower collecting basin to replace water lost bycooling, generator cooling, and turbine generator oil evaporation and drift. In many cases, the makeupcooling. From the outlet of the condensers and mis- water must be softened to prevent scaling of heatcellaneous cooling services, the warmed circulating transfer surfaces; this will be accomplished bywater is directed to the top of the cooling tower for means of cold lime softening. Also the circulatingrejection of heat to the atmosphere. water must be treated with bioxides and inhibitors (b) Circulating water pump and condenser while in use to kill algae, preserve the fill, and pre-valving is similar to that described for a typical vent metal corrosion and fouling. Algae control isonce-through system, but no automatic back flush- accomplished by means of chlorine injection; aciding or mechanical cleaning system is required for and phosphate feeds are used for pH control and tothe condenser. Also, due to the higher pumping keep heat surfaces clean. heads commonly required for elevating water to the (b) The circulating water system must betop of the tower and the break in water pressure at blown down periodically to remove the accumulatedthat point which precludes a siphon, higher pressure solid concentrated by evaporation. 3-39
  • TM 5-811-63-28. Environmental concerns (a) Entrapment or fish kill. a. Possible problems. Some of the environmental (b) Migration of aquatic life.concerns which have an impact on various types of (c) Thermal discharge.power plant waste heat rejection systems are as fol- (d) Chemical discharge.lows: (e) Effect of plankton. (1) Compatibility of circulating water system (8) Effect on animal and bird life.with type of land use allocated to the surrounding (9) Possible obstruction to aircraft (usually onlyarea of the power plant. a problem for tall hyperbolic towers). (2) Atmospheric ground level fogging from (10) Obstruction to ship and boat navigationcooling tower. (for once through system intakes or navigable (3) Cooling tower plumes. streams or bodies of water). (4) Ice formation on adjacent roads, buildings b. Solutions to problems. Judicious selection ofand structures in the winter. the type of circulating water system and optimum (5) Noise from cooling tower fans and circulat- orientation of the power plant at the site can mini-ing water pumps. mize these problems. However, many military proj- (6) Salts deposition on the contiguous country- ects will involve cogeneration facilities which mayside as the evaporated water from the tower is ab- require use of existing areas where construction ofsorbed in the atmosphere and the entrained chemi- cooling towers may present serious on base prob-cals injected in the circulating water system fallout. lems and, hence, will require innovative design solu- (7) Effect on aquatic life for once though sys- tions.tems: Section VII. FEEDWATER SYSTEM3-29. Feedwater heaters off in deaerator pressure under an upset condition. a. Open type—deaerators. Access will be provided for heater maintenance and (1) Purpose. Open type feedwater heaters are for reading and maintaining heater instrumenta-used primarily to reduce feedwater oxygen and oth- tion.er noncondensable gases to essentially zero and thus (4) Design criteria.decrease corrosion in the boiler and boiler feed sys- (a) Deaerating heaters and storage tanks willtem. Secondarily, they are used to increase thermal comply with the latest revisions of the followingefficiency as part of the regenerative feedwater heat- standards:ing cycle. (1) ASME Unified Pressure Vessel Code. (2) Types. (2) ASME Power Test Code for Deaerators. (a) There are two basic types of open deaerat- (3) Heat Exchanger Institute (HE I).ing heaters used in steam power plants—tray type (4) American National Standards Instituteand spray type. The tray or combination spray/tray (ANSI).type unit will be used. In plants where heater tray (b) Steam pressure to the deaerating heatermaintenance could be a problem, or where the feed- will not be less than three psig.water has a high solids content or is corrosive, a (c) Feedwater leaving the deaerator will con-spray type deaerator will be considered. tain no more than 0.005 cc/liter of oxygen and zero (b) All types of deaerators will have internal residual carbon dioxide. Residual content of the dis-or external vent condensers, the internal parts of solved gases will be consistent with their relativewhich will be protected from corrosive gases and volubility and ionization.oxidation by chloride stress resistant stainless steel. (d) Deaerator storage capacity will be not less (c) In cogeneration plants where large than ten minutes in terms of maximum design flowamounts of raw water makeup are required, a deaer- through the unit.ating hot process softener will be selected depending (e) Deaerator will have an internal or externalon the steam conditions and the type of raw water oil separator if the steam supply may contain oil,being treated (Section IX, paragraph 3-38 and such as from a reciprocating steam engine.3-39). (f) Deaerating heater will be provided with (3) Location. The deaerating heater should be the following minimum instrumentation: relieflocated to maintain a pressure higher than the valve, thermometer, thermocouple and test well atNPSH required by the boiler feed pumps under all feedwater inlet and outlet, and steam inlet; pressureconditions of operation. This means providing a gauge at feedwater and steam inlets; and a level con-margin of static head to compensate for sudden fall trol system (paragraph c).3-40
  • TM 5-811-6 b. Closed type. actual plant cycle. (1) Purpose. along with the deaerating heater, (2) Closed feedwater heaters. closed feedwater heaters are used in a regenerative (a) Closed feedwater heater drains are usually feedwater cycle to increase thermal efficiency and cascaded to the next lowest stage feedwater heater thus provide fuel savings. An economic evaluation or to the condenser, A normal and emergency drain will be made to determine the number of stages of line from each heater will be provided. At high loads feedwater heating to be incorporated into the cycle. with high extraction steam pressure, the normal Condensing type steam turbine units often have heater drain valve cascades drain to the next lowest both low pressure heaters (suction side of the boiler stage heater to control its own heater level. At low feed pumps) and high pressure heaters (on the dis- loads with lower extraction steam pressure and low- charge side of the feed pumps). The economic anal- er pressure differential between successive heaters, ysis of the heaters should consider a desuperheater sufficient pressure may not be available to allow the section when there is a high degree of superheat in drains to flow to the next lowest stage heater. In the steam to the heater and an internal or external this case, an emergency drain valve will be provided drain cooler (using entering condensate or boiler to cascade to a lower stage heater or to the conden- feedwater) to reduce drains below steam saturation ser to hold the predetermined level. temperature. (b) The following minimum instrumentation (2) Type. The feedwater heaters will be of the U- will be supplied to provide adequate level control at tube type. each heater: gauge glass; level controller to modu- (3) Location. Heaters will be located to allow late normal drain line control valve (if emergency easy access for reading and maintaining heater in- drain line control valve is used, controller must strumentation and for pulling the tube bundle or have a split range); and high water level alarm heater shell. High pressure heaters will be located to switch. provide the best economic balance of high pressure (3) Open feedwater heaters-deaerators. The fol- feedwater piping, steam piping and heater drain pip lowing minimum instrumentation will be supplied ing. to provide adequate level control at the (4) Design criteria heater: gauge glass, level controller to control feed- (a) Heaters will comply with the latest revi- water inlet control waive (if more than one feedwater sions of the following standards: inlet source, controller must have a split range); low (1) ASME Unfired Pressure Vessel Code. water level alarm switch; “low-low” water level (2) ASME Power Test Code for Feedwater alarm switch to sound alarm and trip boiler feedHeaters. pumps, or other pumps taking suction from heater; (3) Tubular Exchanger Manufacturers As- high water level alarm switch; and “high-high” wa-sociation (TEMA). ter level controller to remove water from the deaer- (4) Heat Exchanger Institute (HE I). ator to the condenser or flash tank, or to divert feed- (5) American National Standards Institute water away from the deaerator by opening a divert-(ANSI). ing valve to dump water from the feedwater line to (b) Each feedwater heater will be provided the condenser or condensate storage tank.with the following minimum instrumentation: shell (4) Reference. The following papers should beand tube relief valves; thermometer, thermocouple consulted in designing feedwater level control sys-and test well at feedwater inlet and outlet; steam in- tems, particularly in regard to the prevention of wa-let and drain outlet; pressure gauge at feedwater in- ter induction through extraction pipinglet and outlet, and steam inlet; and level control sys- (a) ASMD Standard TWDPS-1, July 1972,tem. “Recommended Practices for the Prevention of Wa- c. Level control systems. ter Damage to Steam Turbines Used for Electric (1) Purpose. Level control systems are required Power Generation (Part 1- Fossil Fueled Plants).”for all open and closed feedwater heaters to assure (b) General Electric Company Standardefficient operation of each heater and provide for GEK-25504, Revision D, “Design and Operatingprotection of other related power plant equipment. Recommendations to Minimize Water Induction inThe level control system for the feedwater heaters is Large Steam Turbines.”an integrated part of a plant cycle level control sys- (c) Westinghouse Standard, “Recommenda-tem which includes the condenser hotwell and the tion to Minimize Water Damage to Steam Tur-boiler level controls, and must be designed with this bines.”in mind. This paragraph sets forth design criteriawhich are essential to a feedwater heater level con- 3-30. Boiler feed pumps.trol system. Modifications may be required to fit the a. General. Boiler feed pumps are used to pressur- 3-41
  • TM 5-811-6 ize water from the deaerating feedwater heater or whenever the pump is in operation. The control sys- deaerating hot process softener and feed it through tem will consist off any high pressure closed feedwater heaters to the (a) Flow element to be installed in the pump boiler inlet. Discharge from the boiler superheated suction line. steam in order to maintain proper main steam tern- (b) Flow controller.perature to the steam turbine generator. (c) Flow control valve. b. Types. There are two types of centrifugal (d) Breakdown orifice.multi-stage boiler feed pumps commonly used in (2) Whenever the pump flow decreases to mini- steam power plants—horizontally split case and bar- mum required flow, as measured by the flow ele-rel type with horizontal or vertical (segmented) split ment in the suction line, the flow controller will beinner case. The horizontal split case type will be designed to open the flow control valve to maintainused on boilers with rated outlet pressures up to 900 minimum pump flow. The recirculation line will bepsig. Barrel type pumps will be used on boilers with discharge to the deaerator. A breakdown orifice willrated outlet pressure in excess of 900 psig. be installed in the recirculation line just before it en- c. Number of pumps. In all cases, at least one ters the deaerator to reduce the pressure from boilerspare feed pump will be provided. feed pump discharge level to deaerator operating (1) For power plants where one battery of boiler pressure.feed pumps feeds one boiler. f. Design criteria. (a) If the boiler is base loaded most of the (1) Boiler feed pumps will comply with the lat-time at a high load factor, then use two pumps each est revisions of the following standards:at 110-125 percent of boiler maximum steaming ca- (a) Hydraulics Institute (HI).pacity. (b) American National Standards Institute (b) If the boiler is subject to daily wide range (ANSI).load swings, use three pumps at 55-62.5 percent of (2) Pump head characteristics will be maximumboiler maximum steaming capacity. With this ar- at zero flow with continuously decreasing head as rangement, two pumps are operated in parallel be- flow increases to insure stable operation of onetween 50 and 100 percent boiler output, but only one pump, or multiple pumps in parallel, at all loads.pump is operated below 50 percent capacity. This ar- (3) Pumps will operate quietly at all loads with-rangement allows for pump operation in its most ef- out internal flashing and operate continuously with-ficient range and also permits a greater degree of out overheating or objectionable noises at minimumflexibility. recirculation flow. (2) For power plants where one battery of pump (4) Provision will be made in pump design forfeeds more than one boiler through a header system, expansion ofthe number of pumps and rating will be chosen to (a) Casing and rotor relative to one another.provide optimum operating efficiency and capital (b) Casing relative to the base.costs. At least three 55-62.5 percent pumps should (c) Pump rotor relative to the shaft of thebe selected based on maximum steaming capacity of driver.all boilers served by the battery to provide the flexi- (d) Inner and outer casing for double casingbility required for a wide range of total feedwater pumps. -flows. (5) All rotating parts will be balanced statically d. Location. The boiler feed pumps will be located and dynamically for all speeds.at the lowest plant level with the deaerating heater (6) Pump design will provide axial as well as ra-or softener elevated sufficiently to maintain pump dial balance of the rotor at all outputs.suction pressure higher than the required NPSH of (7) One end of the pump shaft will be accessiblethe pump under all operating conditions. This for portable tachometer measurements.means a substantial margin over the theoretically (8) Each pump will be provided with a pumpcalculated requirements to provide for pressures col- warmup system so that when it is used as a standbylapses in the dearator under abnormal operating it can be hot, ready for quick startup. This is doneconditions. Deaerator level will never be decreased by connecting a small bleed line and orifice from thefor structural or aesthetic reasons, and suction pipe common discharge header to the pump discharge in-connecting deaerator to boiler feed pumps should be side of the stop and check valve. Hot water can thensized so that friction loss is negligible. flow back through the pump and open suction valve e. Recirculation control system. to the common suction header, thus keeping the (1) To prevent overheating and pump damage, pump at operating temperature.each boiler feed pump will have its own recirculation (9) Pump will be designed so that it will startcontrol system to maintain minimum pump flow safely from a cold start to full load in 60 seconds in
  • TM 5-811-6an emergency, although it will normally be warmed steam, the extraction steam, and the high pressurebefore starting as described above. feedwater system. If there are low pressure closed (10) Other design criteria should be as forth in heaters incorporated into the prime movers, the con-Military Specification MIL-P-17552D. densate system usually remains independent for g. Pump drives. For military plants, one steam each such prime mover; however, the deaerator andturbine driven pump may be justified under certain boiler feed pumps are frequently common for allconditions; e.g., if the plant is isolated, or if it is a co- boilers although paralleling of independent highgeneration plant or there is otherwise a need for sub- pressure heater trains (if part of the cycle) on thestantial quantities of exhaust steam. Usually, how- feedwater side maybe incorporated if high pressureever, adequate reliability can be incorporated into bleeds on the primer movers are uncontrolled. Eachthe feed pumps by other means, and from a plant ef- cogeneration feedwater system must carefully be de-ficiency point of view it is always better to bleed signed to suit the basic parameters of the cycle. Lev-steam ‘from the prime mover(s) rather than to use el control problems can become complex, particu-steam from an inefficient mechanical drive turbine. larly if the cycle includes multiple deaerators operat- ing in parallel.3-31. Feedwater supply c. Feedwater controls. Condensate pumps, boiler a. General description. feed pumps, deaerator, and closed feedwater heaters (1) In general terms, the feedwater supply in- are described as equipment items under other head- cludes the condensate system as well as the boiler ings in this manual. Feedwater system controls will feed system. consist of the following (2) The condensate system includes the conden- (1) Condenser hotwell level controls which con- sate pumps, condensate piping, low pressure closed trol hotwell level by recirculating condensate fromheaters, deaerator, and condensate system level and the condensate pump discharge to the hotwell, bymakeup controls. Cycle makeup may be introduced extracting excess fluid from the cycle and pumpingeither into the condenser hotwell or the deaerator. it to atmospheric condensate storage (surge) tanks,For large quantities of makeup as in cogeneration and by introducing makeup (usually from the sameplants, the deaerator maybe preferred as it contains condensate storage tanks) into the hotwell to replen-a larger surge volume. The condenser, however, is ish cycle fluid.better for this purpose when makeup is of high pur- (2) Condensate pump minimum flow controls toity and corrosive (demineralized and undeaerated). recirculate sufficient condensate back to the con-With this arrangement, corrosive demineralized wa- denser hotwell to prevent condensate pumps fromter can be deaerated in the condenser hotwell; the overheating.excess not immediately required for cycle makeup is (3) Deaerator level controls to regulate amountextracted and pumped to an atmospheric storage of condensate transferred from condenser hotwell totank where it will be passive in its deaerated state. deaerator and, in an emergency, to overflow excessAs hotwell condensate is at a much lower tempera- water in the deaerator storage tank to the conden-ture than deaerator condensate, the heat loss in the sate storage tank(s).atmospheric storage tank is much less with this ar- (4) Numerous different control systems are pos-rangement. sible for all three of the above categories. Regardless (3) The feedwater system includes the boiler of the method selected, the hotwell and the deaer-feed pumps, high pressure closed heaters, boiler feed ator level controls must be closely coordinated andsuction and discharge piping, feedwater level con- integrated because the hotwell and deaerator tanktrols for the boiler, and boiler desuperheater water are both surge vessels in the same fluid system.supply with its piping and controls. (5) Other details on instruments and controls b. Unit vs. common system. Multiple unit cogen- for the feedwater supply are described under Sectioneration plants producing export steam as well as 1 of Chapter 5, Instruments and Controls.electric will always have ties for the high pressure Section Vlll. SERVICE WATER3-32. Introduction heavily contaminated or sedimented fresh circulat- ing water. a. Definitions and purposes. Service water supply (a) Most power stations, other than thosesystems and subsystems can be categorized as fol- with cooling towers, fall into this category. Circulat-lows: ing water booster pumps increase the pressure of a (1) For stations with salt circulating water or (small) part of the circulating water to a level ade- 3-43
  • TM 5-811-6quate to circulate through closed cooling water ex- (thermometers, pressure gages, and flow indicators)changers. If the source is fresh water, these pumps should be incorporated into the system to allowmay also supply water to the water treating system. monitoring of equipment cooling.Supplementary sources of water such as the areapublic water supply or well water may be used for 3-33. Description of major componentspotable use and/or as a supply to the water treating a. Service water systerm.system. In some cases, particularly for larger sta- (1) Circulating water booster (or service water)tions, the service water system may have its pumps pumps. These pumps are motor driven, horizontaldivorced from the circulating water pumps to pro- (or vertical) centrifugal type. Either two 100-per-vide more flexibility y and reliability. cent or three 50-percent pumps will be selected for (b) The closed cooling water exchangers this duty. Three pumps provide more flexibility; de-transfer rejected heat from the turbine generator pending upon heat rejection load and desired water .lube oil and generator air (or hydrogen) coolers, bear- temperature, one pump or two pumps can be oper-ings and incidental use to the circulating water side- ated with the third pump standing by as a spare. Astream pressurized by the booster pumps. The medi- pressure switch on the common discharge lineum used for this transfer is cycle condensate which alarms high pressure, and in the case of the boosterrecirculates between the closed cooling exchangers pumps a pressure switch on the suction header or in-and the ultimate equipment where heat is removed. terlocks with the circulating water pumps providesThis closed cooling cycle has its own circulating permissive to prevent starting the pumps unless(closed cooling water) pumps, expansion tank and the circulating water system is in operation.temperature controls. (2) Temperature control. In the event the sys- (2) For stations with cooling towers. Circulat- tem serves heat rejection loads directly, temper-ing water booster pumps (or separate service water ature control for each equipment where heat is re-pumps). may also be used for this type of power moved will be by means of either automatic or man-plant. In the case of cooling tower systems, how- ually controlled valves installed on the cooling wa-ever, the treated cooling tower circulating water can ter discharge line from each piece of equiment, or bybe used directly in the turbine generator lube oil and using a by-pass arrangement to pass variablegenerator air (or hydrogen) coolers and various other amounts of water through the equipment withoutservices where a condensate quality cooling medium upsetting system hydraulic balance.is unnecessary. This substantially reduces the size b. Closed cooling water system.of a closed cooling system because the turbine gen- (1) Closed cooling water pumps. The closederator auxiliary cooling requirements are the largest cooling water pumps will be motor driven, horizon-heat rejection load other than that required for the tal, end suction, centrifugal type with two 100-per-main condenser. If a closed cooling system is used cent or three 50-percent pumps as recommended forfor a station with a cooling tower, it should be de- the pumps described in a above.signed to serve equipment such as air compressor (2) Closed cooling water heat exchangers. Thecylinder jackets and after coolers, excitation system closed cooling water exchangers will be horizontalcoolers, hydraulic system fluid coolers, boiler TV shell and tube test exchangers with the treatedcameras, and other similar more or less delicate plant cycle condensate on the shell side and circulat-service. If available, city water, high quality well ing (service) water on the tube side. Two 100-per-water, or other clean water source might be used for cent capacity exchangers will be selected for thisthis delicate equipment cooling service and thus service, although three 50-percent units may be se-eliminate the closed cooling water system. lected for large systems. b. Equipment required—general. Equipment re- (3) Temperature control. Temperature controlquired for each system is as follows: for each equipment item rejecting heat will be simi- (1) Service water system lar to that described above for the service water sys- (a) Circulating water booster pumps (or sepa- tem.rate service water pumps). (b) Piping components, valves, specialities 3-34. Description of systemsand instrumentation. a. Service water system. (2) Closed cooling water system. (1) The service water system heat load is the (a) Cosed cooling water circulating pumps. sum of the heat loads for the closed cooling water (b) Closed cooling water heat exchangers. system and any other station auxiliary systems (c) Expansion tank. which may be included. The system is designed to (d) Piping components, valves, specialities maintain the closed cooling water system supplyand instrumentation. Adequate instrumentation temperature at 950 For less during normal operation
  • TM 5-811-6 with maximum heat rejection load. The system will vide means to start a standby pump automatically. also be capable of being controlled or manually ad- (2) The system will be designed to ensure ade- justed so that a minimum closed cooling water sup quate heat removal based on the assumption that all ply temperature of approximately 55 ‘F can be service equipment will be operating at maximum de- maintained with the ultimate heat sink at its lowest sign conditions. temperature and minimum head load on the closed cooling water system. The service water system will 3-35. Arrangement be designed with adequate backup and other reli- a. Service water system. The circulating water ability features to provide the required cooling to booster pumps will be located as close as possible to components as necessary for emergency shutdown the cooling load center which generally will be nearof the plant. In the case of a system with circulating the turbine generator units. All service water pipingwater booster pumps, this may mean a crossover located in the yard will be buried below the frostfrom a city or well water system or a special small line.circulating water pump. b. Closed cooling water system. The closed cool- (2) Where cooling towers are utilized, means ing water system exchangers will be located nearwill be provided at the cooling tower basin to permit the turbine generators.the service water system to remain in operationwhile the cooling tower is down for maintenance or 3-36. Reliability of systemsrepairs. (3) The system will be designed such that opera- It is of utmost importance that the service andtional transients (e.g., pump startup or water ham- closed cooling water systems be maintained in serv-mer due to power failure) do not cause adverse ef- ice during emergency conditions. In the event powerfects in the system. Where necessary, suitable valv- from the normal auxiliary source is lost, the motoring or surge control devices will be provided. driven pumps and electrically actuated devices will b. Closed cooling water system. be automatically supplied by the emergency power (1) The closed cooling water coolant tempera- source (Chapter 4, Section VII). Each standby pumpture is maintained at a constant value by automatic will be designed for manual or automatic startupcontrol of the service water flow through the heat upon loss of an operating pump with suitable alarmsexchanger. This is achieved by control valve modu- incorporated to warn operators of loss of pressure inlation of the heat exchanger by-pass flow. All equip- either system.ment cooled by the cooling system is individuallytemperature controlled by either manual or auto- 3-37. Testingmatic valves on the coolant discharge from, or by The systems will be designed to allow appropriateby-pass control around each piece of equipment. The initial and periodic testing to:quantity of coolant in the system is automatically u. Permit initial hydrostatic testing as required inmaintained at a predetermined level in the expan- the ASME Boiler and Pressure Vessel Code.sion tank by means of a level controller which oper- b. Assure the operability and the performance ofates a control valve supplying makeup from the the active components of the system.cycle condensate system. The head tank is provided c. Permit testing of individual components orwith an emergency overflow. On a failure of a run- subsystems such that plant safety is not impairedning closed cooling water pump, it is usual to pro- and that undesirable transients are not present. Section IX. WATER CONDITIONING SYSTEMS3-38. Water Conditioning Selection sure boiler used in power generation. a. Purpose. (2) The purpose of the water conditioning sys- (1) All naturally occuring waters, whether sur- tems is to purify or condition raw water to the re-face water or well water, contain dissolved and pos- quired quality for all phases of power plant opera-sibly suspended impurities (solids) which may be in- tion. Today, most high pressure boilers (600 psig orjurious to steam boiler operation and cooling water above) require high quality makeup water which isservice. Fresh water makeup to a cooling tower, de- usually produced by ion exchange techniques. Tore-pending on its quality, usually requires little or no duce the undesirable concentrations of turbidity andpretreatment. Fresh water makeup to a boiler sys- organic matter found in most surface waters, the tem ranges from possibly no pretreatment (in the raw water will normally be clarifed by coagulationcase of soft well water used in low pressure boiler) to and filtration for pretreatment prior to passing toultra-purification required for a typical high pres- the ion exchangers (demineralizers). Such pretreat- 3-45
  • TM 5-811-6 ment, which may also include some degree of soften- (a) Removal of suspended matter by sedimen- ing, will normally be adequate without further treat- tation, coagulation, and filtration (clarification). ment for cooling tower makeup and other general (b) Deaeration and degasification for removal plant use. of gases. b. Methods of conditioning. (c) Cold or hot lime softening. (1) Water conditioning can be generally cate- (d) Sodium zeolite ion exchange. gorized as’ ‘external” treatment or’ ‘internal” treat- (f) Choride cycle dealkalization. ment. External treatment clarifies, softens, or puri- (g) Demineralization (ultimate ion exchange). fies raw water prior to introducing it into the power (h) Internal chemical treatment. plant fluid streams (the boiler feed water, cooling (i) Blowdown to remove sludge and concen- tower system, and process water) or prior to utiliz- tration buildups. ing it for potable or general washup purposes. Inter- c. Treatment Selection. Tables 3-13, 3-14, and nal treatment methods introduce chemicals directly 3-15 provide general guidelines for selection of into the power plant fluid stream where they coun- treatment methodologies. The choice among these is teract or moderate the undesirable effects of water an economic one depending vitally on the actual con- impurities. Blowdown is used in the evaporative stituents of the incoming water. The designer will processes to control the increased concentration of make a thorough life cycle of these techniques in dissolved and suspended solids at manageable lev- conjunction with the plant data. Water treatment els. experts and manufacturer experience data will (2) Some of the methods of water conditioning called upon. are as follows: Section X. COMPRESSED AIR SYSTEMS3-39. Introduction Non-lubricated design for service air as well as in- a. Purpose. The purpose of the compressed air strument air will be specified so that when the for-systems is to provide all the compressed air require- mer is used for backup of the latter, oil carryoverments throughout the power plant. The compressed will not be a problem. Slow speed horizontal unitsair systems will include service air and instrument for service and instrument air will be used. Sootair systems. blower service requirements call for pressures which b. Equipment required-general. Equipment re- require multi-stage design. The inlet air filter-silenc-quired for a compressed air system is shown in Fig- er will be a replaceable dry felt cartridge type. Eachures 3-14 and 3-15. Each system will include compressor will have completely separate and inde- (1) Air compressors. pendent controls. The compressor controls will per- (2) Air aftercoolers. mit either constant speed-unloaded cylinder control (3) Air receiver. or automatic start-stop control. Means will be pro- (4) Air dryer (usually for instrument air system vided in a multi-compressor system for selection ofonly). the’ ‘lead” compressor. (5) Piping, valves and instrumentation. b. Air aftercooler. The air aftercooler for each c. Equipment served by the compressed air sys- compressor will be of the shell and tube type, de-tems. signed to handle the maximum rated output of the (1) Service (or plant) air system for operation of compressor. Water cooling is provided except fortools, blowing and cleaning. relatively small units which may be air cooled. (2) Instrument air system for instrument and Water for cooling is condensate from the closed cool-control purposes. ing system which is routed counter-flow to the air (3) Soot blower air system for boiler soot blow- through the aftercooler, and then through the cylin-ing operations. der jackets. Standard aftercoolers are rated for 95 “F. maximum inlet cooling water. Permissive 3-40. Description of major components can be installed to prevent compressor startup un- a. Air compressors. Typical service and instru- less cooling water is available and to shut compress- ment air compressor? for power plant service are or down or sound an alarm (or both) on failure of single or two stage, reciprocating piston type with water when unit is in operation. electric motor drive, usually rated for 90 to 125 psig c. Air receiver. Each compressor will have its own discharge pressure. They may be vertical or horizon- receiver equipped with an automatic drainer for re-tal and, for instrument air service, always have oil- moval of water.less pistons and cylinders to eliminate oil carryover. d. Instrument air dryer. The instrument air dryer3-46
  • TM5-811-6 Table 3-13. General Guide for Raw Water Treatment of BoilerMakeup St earn Pressure Silica Alkalinity - (psig) reg./l. reg./l. (as CaCO 3 ) Water Treatmentup to 450 Under 15 Under 50 Sodium ion exchange. Over 50 Hot lime-hot zeolite, or cold lime zeolite, or hot lime soda, or sodium ion exchange plus chloride anion exchange. Over 15 Over 50 Hot lime-hot zeolite, or cold lime-zeolite, or hot lime soda.450 to 600 Under 5 Under 50 Sodium ion exchange plus chloride anion exchange, or hot lime-hot zeolite. Over 50 Sodium plus hydrogen ion exchange, or cold lime- zeolite or hot lime-hot zeolite. Above 5 Demineralizer, or hot lime-hot zeolite.600 to 1000 ------- ‘Any Water ------- Demineralizer.1000 & Higher ------- Any Water ------- Demineralizer.NOTES : (1) Guide is based on boiler water concentrations recommended in the American Boiler and Affiliated Industries “Manual of Industry Standards and Engineering Information.”(2) Add filters when turbidity exceeds 10mg./l.(3) See Table 3-15 for effectiveness of treatments.(4) reg./l. = p.p.m.Source: Adapted from NAVFAC DM3 3-47
  • TM 5-811-6 Table 3-14. Internal Chemical Treatment. Corrosive Treatment Required Chemical Maintenance of feedwater pH and boiler water Caustic Soda alkalinity for scale and corrosion control. Soda Ash Sulfuric Acid . Prevention of boiler scale by internal softening Phosphates of the boiler water. Soda Ash Sodium Aluminate Alginates Sodium Silicate Conditioning of boiler sludge to prevent adherence Tannins to internal boiler surfaces. Lignin Derivatives Starch Glucose Derivatives Prevention of scale from hot water in pipelines, Polyphosphates stage heaters, and economizers. Tannins Lignin Derivatives Glucose Derivatives Prevention of oxygen corrosion by chemical Sulfites deaeration of boiler feedwater. Tannins Ferrus hydroxide Glucose Derivatives Hydrazine Ammonia Prevention of corrosion by protective film Tannins formation. Lignin Derivatives Glucose Derivatives Prevention of corrosion by condensate. Amine Compounds Ammonia Prevention of foam in boiler water. Polyamides Polyalkylene Glycols Inhibition of caustic embrittlement. Sodium Sulfate Phosphates Tannins Nitrates U.S. Army Corps of Engineers 3-48
  • TM 5-811-6 Table 3-15. Effectiveness of Water Treatment Average Analysis of Effluent Hardness Alkalinity co Dissolved (as CaCO ) (as CaCO ) Solids Silica Treatment mg./1. Cold Lime- o to 2 75 Reduced 8 ZeoliteHot Lime Soda 17 to 25 35 to 50 Medium High Reduced 3Hot Lime- o to 2 20 to 25 Low Reduced 3Hot Zeolite Sodium Zeolite o to 2 Unchanged Low to High Unchanged UnchangedSodium Plus o to 2 10 to 30 Low Reduced UnchangedHydrogen ZeoliteSodium ZeolitePlus Chloride o to 2 15 to 35 Low Unchanged UnchangedAnion ExchangerDemineralizer o to 2 o to 2 o to 5 o t o 5 Below 0.15Evaporator o to 2 o to 2 o to 5 o t o 5 Below 0.15NOTE : (1) reg./l. = p.p.m.Source: NAWFAC DM3 3-49
  • WET AIR ENTRAINMENT SEPARATOR Courtesy of Pope, Evans and Robbins (Non-Copyrighted) Figure 3-14. Typical compressed airsystem.will be of the automatic heat reactivating, dual elude work shops, laboratory, air hose stations forchamber, chemical desiccant, downflow type. It will maintenance use, and like items. Air hose stationscontain a prefilter and afterfilter to limit particulate should be spaced so that air is available at eachsize in the outlet dried air. Reactivating heat will be piece of equipment by using an air hose no longerprovided by steam heaters. than 75 feet. Exceptions to this will be as follows: (1) The turbine operating floor will have service3-41. Description of systems air stations every 50 feet to handle air wrenches a. General. The service (or plant) air and the in- used to tension the turbine hood bolts.strument air systems may have separate or common (2) No service air stations are required in thecompressors. Regardless of compressor arrange- control room and in areas devoted solely to switch-ment, service and instrument air systems will each gear and motor control centers.have their own air receivers. There will be isolation (3) Service air stations will be provided insidein the piping system to prevent upsets in the service buildings at doors where equipment or supplies mayair system from carrying over into the vital instru- be brought in or out.ment air system. c. Instrument air sys tern. A detailed analysis will b. Service air system. The service air system be performed to determine system requirements.capacity will meet normal system usage with one The analysis will be based on:compressor out of service. System capacity will in- (1) The number of air operated valves andclude emergency instrument air requirements as dampers included in the mechanical systems.well as service air requirements for maintenance (2) The number of air transmitters, controllersduring plant operation. Service air supply will in- and converters.3-50
  • TM 5-811-6 Courtesy of Pope, Evans and Robbins (Non-Copyrighted) Figure 3-15. Typical arrangement of air compressor and accessories. (3) A list of another estimated air usage not in- (2) Instrument air reserve. In instances whereeluded in the above items. short term, large volume air flow is required, local d. Piping system. air receivers can be considered to meet such needs (1) Headers. Each separate system will have a and thereby eliminate installation of excessive com-looped header to distribute the compressed air, and pressor capacity. However, compressor must befor large stations a looped header will be provided at sized to recharge the receivers while continuing toeach of the floor levels. supply normal air demands. 3-51
  • . ”
  • TM 5-811-6 CHAPTER 4 GENERATOR AND ELECTRICAL FACILITIES DESIGN Section 1. TYPICAL VOLTAGE RATINGS AND SYSTEMS “ 4-1. Voltages common bus system and a unit system. The distinc- a. General. Refer to ANSI Standard C84. 1 for tion is based on the relationship between the gener- voltage ratings for 60 Hz electric power systems ating unit and the auxiliary transformer supplying and equipment. In addition, the standard lists appli- power for its auxiliary equipment. cable motor and motor control nameplate voltage (1) In the common bus system the auxiliary ranges up to nominal system voltages of 13.8 kV. transformer will be connected through a circuit b. Generators. Terminal voltage ratings for power breaker to a bus supplied by a number of units and plant generators depend on the size of the genera- other sources so that the supply has no relationship tors and their application. Generally, the larger the to the generating unit whose auxiliary equipment is generator, the higher the voltage. Generators for a being served. In the unit system the auxiliary trans- power plant serving an Army installation will be in former will be connected solidly to the generator the range from 4160 volts to 13.8 kV to suit the size leads and is switched with the generator. In either of the unit and primary distribution system voltage. case, the auxiliary equipment for each generating Generators in this size range will be offered by the unit usually will be supplied by a separate transfor- manufacturer in accordance with its design, and it mer with appropriate interconnections between the would be difficult and expensive to get a different secondary side of the transformers.voltage rating. Insofar as possible, the generator (2) The unit type system has the disadvantagevoltage should match the distribution voltage to that its station service power requirements must beavoid the installation of a transformer between the supplied by a startup transformer until the generat-generator and the distribution system. ing unit is synchronized with the system. This start- c. Power plant station service power systems. up transformer also serves as the backup supply in (1) Voltages for station service power supply case of transformer failure. This arrangement re-within steam electric generating stations are related quires that the station service power supply beto motor size and, to a lesser extent, distances of ca- transferred from the startup source to the unitble runs. Motor sizes for draft fans and boiler feed source with the auxiliary equipment in operation aspumps usually control the selection of the highest apart of the procedure of starting the unit.station service power voltage level. Rules for select- (3) The advantages of the unit system are thating motor voltage are not rigid but are based on rela- it reduces the number of breakers required and thattive costs. For instance, if there is only one motor its source of energy is the rotating generating unitlarger than 200 hp and it is, say, only 300 hp, it so that, in case of system trouble, the generatingmight be a good choice to select this one larger mo- unit and its auxiliaries can easily be isolated fromtor for 460 volts so that the entire auxiliary power the rest of the system. For application to Army in-system can be designed at the lower voltage. stallations, the advantage of switching the gener- (2) Station service power requirements for com- ator and its auxiliary transformer as a unit is notbustion turbine and internal combustion engine gen- very important, so the common bus system will nor-erating plants are such that 208 or 480 volts will be mally be used.used. b. Common bus system. In this system, gener- d. Distribution system. The primary distribution ators will be connected to a common bus and thesystem for an Army installation with central in- auxiliary transformers for all generating units willhouse generation should be selected in accordance be fed from that common bus. This bus may havewith TM 5-811 -l/AFM 88-9. one or more other power sources to serve for station startup.4-2. Station service power systems. (1) Figure 4-1 is a typical one-line diagram for a. General. Two types of station service power such a system. This type system will be used forsystems are generally in use in steam electric plants diesel generating plants with all station service sup-and are discussed herein. They are designated as a plied by two station service transformers with no 4-1
  • TM 5-811-64-2
  • TM 5-811-6 isolation between auxiliaries for different generat- one-line diagram of this arrangement. If the highest ing units. It also will be used for steam turbine and level of auxiliary voltage required is more than 480 gas turbine generating plants. For steam turbine volts, say 4.16 kV, the auxiliary switchgear air cir- generating plants the auxiliary loads for each unit in cuit breakers will only serve motors 250 hp and larg- the plant will be isolated on a separate bus fed by a er and feeders to unit substations. Each unit substa- separate transformer. A standby transformer is in- tion will include a transformer to reduce voltage cluded and it serves the loads common to all units from the highest auxiliary power level to 480 volts such as building services. together with air circuit breakers in a lineup for (2) The buses supplying the auxiliaries for the starting of motors 100 to 200 hp and for’ serving several units will be operated isolated to minimize 480-volt motor control centers. The motor control fault current and permit use of lower interrupting centers will include combination starters and feed- rating on the feeder breakers. Provision will be made ers breakers to serve motors less than 100 hp and for the standby transformer to supply any auxiliary other small auxiliary circuits such as power panels. bus. e. Startup auxiliary transformer. In addition to c. Unit type system. the above items, the unit auxiliary type system will (1) The unit type station service power system incorporate a “common” or “startup” arrangement will be used for a steam electric or combustion tur- which will consist of a startup and standby auxil- bine generating station serving a utility transmis- iary transformer connected to the switchyard bus or sion network. It will not be, as a rule, used for a other reliable source, plus a low voltage switchgear diesel generating station of any kind since the sta- and motor control center arrangement similar to tion service power requirements are minimal. that described above for the unit auxiliary system. (2) The distinguishing feature of a unit type sta- The common bus system may have a similar ar-tion power system is that the generator and unit rangement for the standby transformer.auxiliary transformer are permanently connected to- (1) This common system has three principalgether at generator voltage and the station service functions:power requirements for that generating unit, includ- (a) To provide a source of normal power foring boiler and turbine requirements, are normally power plant equipment and services which are com- supplied by the auxiliary transformer connected to mon to all units; e.g., water treating system, coalthe generator leads. This is shown in Figure 4-2. If and ash handling equipment, air compressors, light-the unit is to be connected to a system voltage that is ing, shops and similar items.higher than the generator voltage, the unit concept (b) To provide backup to each auxiliary powercan be extended to include the step-up transformer system segment if the transformer supplying thatby tying its low side solidly to the generator leads segment fails or is being maintained.and using the high side breaker for synchronizing (c) In the case of the unit system, to providethe generator to the system. This arrangement is startup power to each unit auxiliary power systemshown in Figure 4-3. until the generator is up to speed and voltage and is d. Station service switchgear. A station service synchronized with the distribution system.switchgear lineup will be connected to the low side (2) The startup and standby transformer andof the auxiliary transformer; air circuit breakers will switchgear will be sized to accomplish the abovebe used for control of large auxiliary motors such as three functions and, in addition, to allow for possibleboiler feed pumps, fans and circulating water pumps future additions to the plant. Interconnections willwhich use the highest station service voltage, and be provided between the common and unit switch-for distribution of power to various unit substations gear. Appropriate interlocks will be included so thatand motor control centers to serve the remaining no more than one auxiliary transformer can feed anystation service requirements. Figure 4–4 is a typical switchgear bus at one time. Section Il. GENERATORS4-3. General types and standards a gear reducer up to 10,000 kVA or more). Self-ven- a. Type. Generators for power plant service can tilation is provided for generators larger than 5000be generally grouped according to service and size. kVA by some manufacturers, but this is not recom- (1) Generators for steam turbine service rated mended for steam power plant service.5000-32,000 kVA, are revolving field, non-salient, (2) Similar generators rated 5000 kVA and be-two-pole, totally enclosed, air cooled with water low are revolving field, non-salient or salient pole,cooling for air coolers, direct connected, 3600 rpm self-ventilated, open drip-proof type, sometimesfor 60 Hz frequency (sometimes connected through connected through a gear reducer to the turbine 4-3
  • TM 5-811-6 w
  • LEGENDCourtesy of Pope, Evans and Robbins (Non-Copyrighted) Figure 4-3. Station connections, two unit station unit arrangement-distribution voltage higher than generation.
  • TM 5-811-6with the number of poles dependent on the speed se- pole generators. Generators may be obtained totallylected which is the result of an economic evaluation enclosed with water cooling if desired because ofby the manufacturer to optimize the best combina- high ambient temperatures or polluted atmosphere.tion of turbine, gear and generator. (4) Generators for diesel service are revolving (3) Generators for gas turbine service are re- field, salient pole, air cooled, open type, direct con-volving field, non-salient or salient pole, self-venti- nected, and with amortisseur windings to dampenlated, open drip-proof type, sometimes connected pulsating engine torque. Number of poles is six orthrough a gear reducer, depending on manufactur- more to match low speeds typical of diesels,er’s gas turbine design speed, to the gas turbine b. Standards. Generators will meet the require-power takeoff shaft. Non-salient pole generators are ments of ANSI C50. 10, C50. 13 and C50.14 is applic-two-pole, 3600 rpm for 60 Hz, although manufactur- able as well as the requirements of NEMA SM 12ers of machines smaller than 1500 kVA may utilize and SM 13.1800 rpm, four-pole, or 1200 rpm, six-pole, salient (1) ANSI C84.1 designates standard voltages4-6
  • TM 5-811-6 as discussed in section I. achieving generator stability without the heavy ex- (2) Generator kVA rating for steam turbine pense associated with the high cost of building high generating units is standardized as a multiplier of short circuit ratios into the generator. Generators the turbine kW rating. Turbine rating for a condens- have standard short circuit ratios of 0.58 at rated ing steam turbine with controlled extraction for kVA and power factor. If a generator has a fast act- feedwater heating is the kW output at design initial ing voltage regulator and a high ceiling voltage steam conditions, 3.5-inches hg absolute exhaust static excitation system, this standard short circuit pressure, three percent cycle makeup, and all feed- ratio should be adequate even under severe system water heaters in service. Turbine rating for a non- disturbance conditions. Higher short circuit ratios condensing turbine without controlled or uncon- are available at extra cost to provide more stability trolled extraction is based on output at design ini- for unduly fluctuating loads which may be anticipat- tial steam conditions and design exhaust pressure. ed in the system to be served. Turbine standard ratings for automatic extraction (6) Maximum winding temperature, at rated units are based on design initial steam conditions load for standard generators, is predicated on oper- and exhaust pressure with zero extraction while ation at or below a maximum elevation of 3300 feet; maintaining rated extraction pressure. However, this may be upgraded for higher altitudes at an ad- automatic extraction turbine ratings are complicat- ditional price. ed by the unique steam extraction requirements for each machine specified. For air cooled generators up 4-4. Features and accessories to 15,625 kVA, the multiplier is 1.25 times the tur- The following features and accessories are available bine rating, and for 18,750 kVA air cooled and hy- in accordance with NEMA standards SM 12 anddrogen cooled generators, 1.20. These ratings are for SM 13 and will be specified as applicable for eachwater cooled generators with 95 “F maximum inlet generator.water to the generator air or hydrogen coolers. a. Voltage variations. Unit will operate with volt-Open, self-ventilated generator rating varies with age variations of plus or minus 5 percent of ratedambient air temperature; standard rating usually is voltage at rated kVA, power factor and frequency,at 104° F ambient. but not necessarily in accordance with the stand- (3) Generator ratings for gas turbine generat- ards of performance established for operation at rat-ing units are selected in accordance with ANSI ed voltage; i.e., losses and temperature rises may ex-Standards which require the generator rating to be ceed standard values when operation is not at ratedthe base capacity which, in turn, must be equal to or voltage.greater than the base rating of the turbine over a b. Thermal variations.specified range of inlet temperatures. Non-standard (1) Starting from stabilized temperatures andgenerator ratings can be obtained at an additional rated conditions, the armature will be capable ofprice. operating, with balanced current, at 130 percent of (4) Power factor ratings of steam turbine driven its rated current for 1 minute not more than twice agenerators are 0.80 for ratings up to 15,625 kVA year; and the field winding will be capable of operat-and 0.85 for 17,650 kVA air cooled and 25,600 kVA ing at 125 percent of rated load field voltage for 1to 32,000 kVA air/water cooled units. Standard pow- minute not more than twice a year.er factor ratings for gas turbine driven air cooled (2) The generator will be capable of withstand-generators usually are 0.80 for machines up to 9375 ing, without injury, the thermal effects of unbal-kVA and 0.90 for 12,500 to 32,000 kVA. Changes in anced faults at the machine terminals, including theair density, however, do not affect the capability of decaying effects of field current and dc componentthe turbine and generator to the same extent so that of stator current for times up to 120 seconds, provid-kW based on standard conditions and generator ed the integrated product of generator negativekVA ratings show various relationships. Power fac- phase sequence current squared and time (122t) doestors of large hydrogen cooled machines are stand- not exceed 30. Negative phase sequence current isardized at 0.90. Power factor for salient pole gener- expressed in per unit of rated stator current, andators is usually 0.80. Power factor lower than stand- time in seconds. The thermal effect of unbalancedard, with increased kVA rating, can be obtained at faults at the machine terminals includes the decay-an extra price. ing effects of field current where protection is pro- (5) Generator short circuit ratio is a rough indi- vided by reducing field current (such as with an ex-cation of generator stability; the higher the short citer field breaker or equivalent) and dc componentcircuit ratio, the more stable the generator under of the stator current.transient system load changes or faults. However, c. Mechanical withstand. Generator will be cap-fast acting voltage regulation can also assist in able of withstanding without mechanical injury any 4-7
  • TM 5-811-6 type of short circuit at its terminals for times not ex- 4-5. Excitation systems ceeding its short time thermal capabilities at rated Rotating commutator exciters as a source of dc pow-kVA and power factor with 5 percent over rated er for the ac generator field generally have been re-voltage, provided that maximum phase current is placed by silicon diode power rectifier systems oflimited externally to the maximum current obtained the static or brushless type.from the three-phase fault. Stator windings must a. A typical brushless system includes a rotatingwithstand a normal high potential test and show no permanent magnet pilot exciter with the stator con-abnormal deformation or damage to the coils and nected through the excitation switchgear to the sta-connections. tionary field of an ac exciter with rotating armature d. Excitation voltage. Excitation system will be and a rotating silicon diode rectifier assembly,wide range stabilized to permit stable operation which in turn is connected to the rotating field of thedown to 25 percent of rated excitation voltage on generator. This arrangement eliminates both the .manual control. Excitation ceiling voltage on man- commutator and the collector rings. Also, part ofual control will not be less than 120 percent of rated the system is a solid state automatic voltage regula-exciter voltage when operating with a load resist- tor, a means of manual voltage regulation, and nec-ance equal to the generator field resistance, and ex- essary control devices for mounting on a remotecitation system will be capable of supplying this panel. The exciter rotating parts and the diodes areceiling voltage for not less than 1 minute. These cri- mounted on the generator shaft; viewing duringteria, as set for manual control, will permit oper- operation must utilize a strobe light.ation when on automatic control. Exciter response b. A typical static system includes a three-phaseratio as defined in ANSI/IEEE 100 will not be less excitation potential transformer, three single-phasethan 0.50. current transformers, an excitation cubicle with e. Wave shape. Deviation factor of the open cir- field breaker and discharge resistor, one automaticcuit terminal voltage wave will not exceed 10 per- and one manual static thyristor type voltage regula-cent. tors, a full wave static rectifier, necessary devices f. Telephone influence factor. The balanced tele- for mounting on a remote panel, and a collector as-phone influence factor (TIF) and the residual compo- sembly for connection to the generator field.nent TIF will meet the applicable requirements ofANSI C50.13. Section Ill. GENERATOR LEADS AND SWITCHYARD4-6. General rupting the maximum possible fault current thatThe connection of the generating units to the distri- will flow through them to a fault. In the event thatbution system can take one of the following pat- the possible fault current exceeds the interruptingterns: capacity of the available breakers, a synchronizing a. With the common bus system, the generators bus with current limiting reactors will be required.are all connected to the same bus with the distribu- Switching arrangement selected will be adequate totion feeders. If this bus operates at a voltage of 4.16 handle the maximum calculated short circuit cur-kV, this arrangement is suitable up to approximate- rents which can be developed under any operatingly 10,000 kVA. If the bus operates at a voltage of routine that can occur. All possible sources of fault13.8 kV, this arrangement is the best for stations up current; i.e., generators, motors and outside utilityto about 25,000 or 32,000 kVA. For larger stations, sources, will be considered when calculating shortthe fault duty on the common bus reaches a level circuit currents. In order to clear a fault, all sourcesthat requires more expensive feeder breakers and will be disconnected. Figure 4-5 shows, in simplifiedthe bus should be split. single line format, a typical synchronizing bus ar- b. The bus and switchgear will be in the form of a rangement. The interrupting capacity of the break-factory fabricated metal clad switchgear as shown ers in the switchgear for each set of generators isin Figure 4-1. For plants with multiple generators limited to the contribution to a fault from the gener-and outgoing circuits, the bus will be split for reli- ators connected to that bus section plus the contri-ability y using a bus tie breaker to permit separation bution from the synchronizing bus and large (load)of approximately one-half of the generators and motors. Since the contribution from generators con-lines on each side of the split. nected to other bus sections must flow through two c. A limiting factor of the common type bus sys- reactors in series fault current will be reduced ma-tem is the interrupting capacity of the switchgear. terially.The switchgear breakers will be capable of inter- d. If the plant is 20,000 kVA or larger and the4-8
  • I TM 5-811-6 Figure 4-5. Typical synchronizing bus. . area covered by the distribution system requires used with more than eight bus sections because of distribution feeders in excess of 2 miles, it may be the possibility of simultaneous outages resulting in advantageous to connect the generators to a higher the bus being split into two parts. The breaker and a voltage bus and feed several distribution substa- half arrangement, shown in Figure 4-8, is the high- tions from that bus with step-down substation est cost alternative and provides the highest relia- transformers at each distribution substation as bility without limitation on the number of circuits. shown in Figure 4-3. e. The configuration of the high voltage bus will 4-7. Generator leads be selected for reliability and economy. Alternative a. Cable. bus arrangements include main and transfer bus, (1) Connections between the generator and ring bus and breaker and a half schemes. The main switchgear bus where distribution is at generator and transfer arrangement, shown in Figure 4-6, is voltage, and between generator and stepup trans- the lowest cost alternative but is subject to loss of former where distribution is at 34.5 kV and higher, all circuits due to a bus fault. The ring bus arrange- will be by means of cable or bus duct. In most in- ment, shown in Figure 4-7, costs only slightly more stances more than one cable per phase will be neces- than the main and transfer bus arrangement and sary to handle the current up to a practical maxi- L eliminates the possibility of losing all circuits from a mum of four conductors per phase. Generally, cable bus fault since each bus section is included in the installations will be provided for generator capac- protected area of its circuit. Normally it will not be ities up to 25 MVA. For larger units, bus ducts will 4-9
  • TM 5-811-6 LOAD LOADbe evaluated as an alternative. be tri-plexed; i.e., all run in one steel armored enclo- (2) The power cables will be run in a cable tray, sure. In the event that single phase cables are re-separate from the control cable tray; in steel con- quired, the armor will be nonmagnetic.duit; suspended from ceiling or on wall hangers; or (5) In no event should the current carrying ca-in ducts depending on the installation requirements. pacity of the power cables emanating from the gen- (3) Cable terminations will be made by means of erator be a limiting factor on turbine generator out-potheads where lead covered cable is applied, or by put. As a rule of thumb, the cable current carryingcompression lugs where neoprene or similarly jack- capacity will be at least 1.25 times the current asso-eted cables are used. Stress cones will be used at ciated with kVA capacity of the generator (not the4.16 kV and above. kW rating of the turbine). (4) For most applications utilitizing conduit, b. Segregated phase bus.cross-linked polyethylene with approved type filler (1) For gas turbine generator installations theor ethylene-propylene cables will be used. For appli- connections from the generator to the side wall orcations where cables will be suspended from hangers roof of the gas turbine generator enclosure will haveor placed in tray, armored cable will be used to pro- been made by the manufacturer in segregated phasevide physical protection. If the cable current rating bus configuration. The three phase conductors willdoes not exceed 400 amperes, the three phases will be flat copper bus, either in single or multiple con-4-10
  • TM 5-811-6 Typical ring bus.ductor per phase pattern. External connection to bles but final selection will be based on expectedswitchgear or transformer will be by means of segre- field conditions.gated phase bus or cable. In the segregated phase c. Isolated phase bus.bus, the three bare bus-phases will be physically sep- (1) For steam turbine generator ratings of 25arated by non-magnetic barriers with a single enclo- MVA and above, the use of isolated phase bus forsure around the three buses. connection from generator to stepup transformer (2) For applications involving an outdoor gas will be used. At such generator ratings, distributionturbine generator for which a relatively small lineup seldom is made at generator voltage. An isolatedof outdoor metal clad switchgear is required to han- phase bus system, utilizing individual phase copperdle the distribution system, segregated phase bus or aluminum, hollow square or round bus on insula-will be used. For multiple gas turbine generator in- tors in individual non-magnetic bus enclosures, pro-stallations, the switchgear will be of indoor con- vides maximum reliability by minimizing the possi-struction and installed in a control/switchgear build- bility of phase-to-ground or phase-to-phase faults.ing. For these installations, the several generators (2) Isolated phase bus current ratings shouldwill be connected to the switchgear via cables. follow the rule of thumb set forth above for gener- (3) Segregated bus current ratings may follow ator cables.the rule of thumb set forth above for generator ca- 4-11
  • TM 5-811-6 AD b D4-12
  • I TM 5-811-6 4-8. Switchyard titularly polluted atmospheres, the next higher volt- age rating than that of the system will be used. In a. Outdoor vs. indoor. With normal atmospheric some instances, the manufacturer can furnish cur- conditions, switchyards will be of the outdoor type rent carrying parts designed for the system voltage as described below. It is possible that a plant will be and will increase phase spacing and insulator stack located on a tropical desert area where alternate length to the next higher voltage rating in order to sand blasting and corrosion or contamination is a increase the leakage paths in the polluted atmos- problem or in an arctic area where icing is a problem. phere. In such installations, the normal relationship In such an event, an indoor switchyard or installa- between flashover across the open switch and flash- tion employing totally enclosed metal clad switch- over to ground must be maintained. gear with SF6 insulation will be provided. (5) All disconnect switches will be operable b. Structures and buses. from ground level by means of either a lever or rotat- (1) In the event distribution for a large installa- ing crank mechanism. The crank type mechanism is tion is at higher than generator voltage; e.g., 34.5 preferred because it is more positive and takes less kV, or in the event an interconnection with a local strength to operate. Operating mechanisms will be utility is necessary, a switchyard will be required. capable of being locked by padlock in both the open The switching structure will be erected to support and closed positions. A switchplate will be provided the bus insulators, disconnecting switches, poten- at each operating mechanism for the operator to tial and current transformers, and the terminations stand on when operating the switch. Each plate will for the generator stepup transformer and transmis- be approximately 2 feet, 6 inches wide by 4 feet sion lines. long, made of galvanized steel, and with two ground (2) Structures of galvanized steel or aluminum lugs permanently attached to the underside of each are most often used. Where the switchyard is lo- plate on the side next to the operating mechanism. cated close to an ocean, the salt laden atmosphere The switchplates will be connected to the operating may be extremely corrosive to aluminum requiring handle and to the switchyard ground grid at two the use of galvanized steel. separate points by means of a 2/0 stranded bare cop- (3) Either copper or aluminum, tubular buses per wire. will be employed depending upon the atmosphere, d. Oil circuit breakers. with aluminum generally being less expensive. Cop- (1) For outdoor service, from nominal 13.8 kV per bus connections will be bolted; aluminum con- through 69 kV, single tank oil circuit breakers nections must be welded. Special procedures are re- (ocb’s) having one operating mechanism attached to quired for aluminum welding, and care should be the tank will be used. Above 69 kV, three tanks are taken to assure that welders certified for this type of used, all permanently mounted on a single channel welding are available. For isolated or overseas es- base, with ‘a single operating mechanism attached to tablishments, only copper buses should be used. A one of the end tanks. corrosive atmosphere will preclude the use of alumi- (2) Operating mechanisms can be spring num. charged using a motor to charge the spring, pneu- c. Disconnect switches; insulators matic employing a motor driven compressor in each (1) Two three-phase disconnect switches will be operating mechanism; or pneudraulic, a combina- used for each oil circuit breaker, one on each side of tion pneumatic and hydraulic mechanism. The 69 the breaker. If the ring bus arrangement is used, a kV and below applications utilize the spring charged disconnect switch will also be used in the circuit mechanism because of lower cost while above 69 kV, take-off so the ring can be reclosed with the circuit either of the other two work satisfactorily. Both an out for maintenance. If only one bus is used, a dis- ac and a dc auxiliary source must be made available connect switch will be installed as a by-pass around to each breaker operating mechanism. the circuit breaker so it can be maintained. (3) Up to two doughnut type multi-ratio current (2) Line disconnect switches at all voltage rat- transformers (600:5, with taps; or 1200:5, with taps) ings will have arcing horns. Above 69 kV, all discon- can be obtained on each bushing. These are mounted nect switches will have arcing horns. inside the tanks with all leads brought to terminal (3) Current carrying capacity of each discon- blocks in the mechanism cabinets. Since it is a major nect switch will be at least 25 percent above that of task to add current transformers, the two will be the line or transformer to which it is connected. The purchased initially for each bushing. switches are available in 600, 1200 and 2000 ampere (4) A considerable range of both current carry- ratings. ing and current interrupting capacity is available (4) Voltage ratings of switches and bus support for each system operating voltage level. Careful insulators will match the system voltage. In par- study must be made of the continuous load current 4-13
  • TM 5-811-6 and fault current requirements before selecting oil time. Power circuits can be operated for extended, circuit breakers. Short circuit calculations must be periods with a part of the instrumentation and me- made for any power system, but for extensive power tering out of service; they should not be operated for systems operating in parallel with a utility, a sys- extended periods without the protective devices. tem study will be performed prior to selecting the oil f. Duct system. circuit breakers. Power networks analyzers or com- (1) Except as otherwise described herein, duct puter programs will be utilized in such work. systems will be in accordance with TM 5-811-1/ e. Potential and current transformers. AFM 88-9. (1) For power systems through 69 kV, potential (2) Power and control cables will be run in un- transformers are generally used to provide voltages derground conduit in a concrete duct system be- in the 69- and 120-volt ranges for voltmeters, watt- tween the generating station and switchyard; the meters, varmeters, watt-hour meters, power factor two types of cable maybe run in the same duct bank meters, synchroscopes, various recorders, and for but in separate conduits. If in the same duct bank, certain protective relays and controls. Above 69 kV, the manholes will be divided with a concrete barrier the cost becomes prohibitive and capacitor potential between the power and control cable sections. The devices are used. The latter do not have as much main power cables will be run in their own duct volt-ampere capacity as potential transformers so system and will terminate at the power transform- care must be taken not to overload the potential de- ers which are usually placed in a single row. vices by placing too many instruments or devices in (3) At the point of entrance into the switchyard, the circuit. the control cable duct system will empty into a con- (2) Both the potential transformers (pt’s) and crete cable trench system, either poured in place or capacitor potential devices (cpd’s) will be purchased assembled from prefabricated runs. The U-shaped with dual 120 volt secondaries, each tapped at 69 trench will be of sufficient size in width and depth to volts for circuit flexibility y. All should be for single accommodate control and auxiliary power cables for phase-to-ground application on the high voltage present transformers, breakers, disconnect side. switches, pt’s and ct ‘s, ac and dc auxiliary power ca- (3) Three line-to-ground pt’s or cpd’s will be em- bles and lighting circuits, plus provision of at least ployed on each main high voltage bus. Generally, 25 percent for expansion of the switchyard. only one pt or cpd is needed on each feeder for syn- (4) Checkered plate or sectionalized prefabri- chronizing or hot line indication; but for ties to the cated concrete covers will be placed on the trench, outside utility or for special energy metering for bill- complete with holes or tilt-up recessed handles for ing purposes or other energy accounting, or for re- assistance in removal of each cover section. laying, three devices will be necessary. (5) Control cables will be run through sleeves (4) Current transformers (et’s) of the through from the trench then through galvanized steel con- type, where the primary winding is connected in the duit buried 18 inches deep to the point of rising to circuit, will seldom be used. In the usual case, there the circuit breaker mechanism housing or other ter- are sufficient bushing type ct’s in the oil circuit mination. Risers will be attached securely to the ter- breakers and power transformers. Multi-ratio units minating device. will be employed, as described under d above, for g. Ac and dc distribution. One or more 120/208control, indication and protective relaying. Should Vat, 24 or 40 circuit distribution panlboards and billing metering be needed, more accurate metering one 125 Vdc, 24-circuit distribution panel will be type bushing type ct’s will be used. provided in weatherproof enclosures in a central lo- (5) Current transformer ratios do not necessar- cation in the switchyard. Oil circuit breakers require ily have a direct relationship with the continuous 125 Vdc for closing, tripping and indication. Com- current capacity of the circuit breaker or transform- pressor motors or spring winding motors for the oil er bushing on which they are mounted. The high cur- circuit breakers will require 120 or 208 volts ac, as rent portion of the ratio shoul be selected so that will the radiator cooling fans for the power trans- the circuit full load current ‘wall beat approximately formers. Strip heaters for the ocb transformer 70-80 percent of instrument full scale for best accu- mechanism housings will operate at 208 Vat. Light- racy. Ratios for protective relaying will be specially ing circuits will require 120 Vat. Weatherproof, selected to fill the particular relays being applied. grounding type convenience outlets at 120 volts and (6) Joint use of a particular set of et’s for both 208 volts will be provided for electrically operated instrumentation and protective relaying will be tools and maintenance equipment needed to main- avoided because the two ratio requirements may be tain the switchyard. different and testing or repair of instrument circuits h. Grading and fencing.may require those circuits to be out of service for a (1) The entire switchyard area will be at the4-14
  • TM 5-811-6 same grade except for enough slope to provide the perimeter, cross-connections from side to side drainage. The concrete pads and foundations for all and end to end will be 250 MCM stranded tinned ocb’s and transformers; for all bus, pt and ct sup- copper cable on 10- to 12-foot spacing in accord- porting structures; and for the switchyard struc- ance with TM 5-811-l/AFM 88-9. Taps will be tures will be designed for the same top elevation, made to each vertical bay column of the switchyard and final rough grade will set some 9 inches below structure, to every pt and ct and bus support struc- top of concrete. ture, to every ocb and transformer, and to every dis- (2) Three inches of coarse gravel and 3 inches of connect switch structure with 4/0 stranded tinned fine gravel will be provided on the rough grade copper conductor. Two taps will be run to each cir- which will allow the top of the concrete to be ex- cuit breaker and power transformer from different posed 3 inches above the final crushed rock grade. 250 MCM cross-connections. The rough grade will be sloped at 1 inch per hundred (3) Taps will extend outward from the 500 feet to provide drainage, but the final crushed rock MCM perimeter cable to a fence rectangular loop course will be dead level. Crushed rock will extend 3 with taps at no more than 40-foot centers. This loop feet outside the fence line. will be run parallel to the fence, 2 feet outside the (3) All concrete foundations will have a l-inch, fence line, and the fence loop will be tapped every 20- 45-degree chamfer so the edges will not chip. feet via 2/0 stranded tinned copper taps securely (4) An 8-foot galvanized steel chain link fence bolted to the fence fabric near the top rail. Flexible with round line and corner posts will enclose the en- tinned copper ground straps will be installed across tire substation. The fence will be angle braced in the hinge point at each swinging gate. both directions. End posts for personnel and vehicle (4) At least two 500 MCM bare-stranded,gates will be similarly braced. Posts will be mounted tinned copper cables will be connected via directin poured concrete footings, having the top cap burial to the generating station ground grid. Con-rounded for drainage. nection will be made to opposite ends of the switch- (5) Two 36-inch wide personnel gates will be yard 500 MCM loop and to widely separated pointsplaced in diagonally opposite locations; one located at the generating station grid.for convenience for operator and maintenance regu- (5) Ground rods, at least 8 feet long, 3/4-inch di-lar access, and the other to provide an emergency ameter, will be driven at each main grid intersectionexit. The gate for regular access will be padlockable. point and at 20-foot centers along the fence loop toThe emergency exit gate will not be padlocked but a depth of 13 inches above the intersection about 17will be openable only from inside the switchyard by inches below rough grade.means of removing a drop-in pin; the pin will be so (6) Every grid intersection and every groundbarriered that it cannot be removed from outside the rod connection to both grids will be exothermicfence. This panic hardware will be designed for in- welded using appropriate molds.stant, easy removal in the event use of the emergen- (7) The ground grid system described above willcy exit is necessary. suffice for most Army establishments except in par- (6) A double hung, padlockable vehicle gate will ticularly rocky areas or in the Southwest desertbe installed; each section will be 8 feet in width to states. Target is to obtain not greater than fiveprovide adequate room for transformer removal and ohms ground resistance. In rocky or desert areas,line truck entrance and egress. special connections of the switchyard grid to remote (7) If local codes will permit, a three-strand grounding pits via drilled holes perhaps 200 feetbarbed wire security extension, facing outward at deep or grids buried in remote stream beds may be45 degrees, will be mounted on top of the fence and necessary. NOTE: TM 5-811-1 describes a grad-gates. ing, fencing and grounding system in considerable i. Grounding. detail for station and substation applications where (1) A grounding grid, buried approximately 2 power is purchased from a utility or small genera-feet below rough grade level will be installed prior to tors are installed. The intent herein is to provide forinstallation of cable ducts, cable trenches and the additional requirements for a larger (5000-crushed rock, but simultaneously with the installa- 30,000 kW) generating station stepup switchyardtion of switchyard structure, ocb, and transformer which permits connection to a distribution systemfootings. and interconnection with an outside utility system. (2) The main rectangular grid will be looped The system herein described is a “heavy duty” sys-around the perimeter of the yard and composed of tem. TM 5-811-UAFM 88-9 will be followed for de-500 MCM bare stranded tinned copper cable. From tail not described herein. 4-15
  • TM 5-811-6 Section IV. TRANSFORMERS 4-9. Generator stepup transformer auxiliary power sources within the plant. The stepup transformer will be in accordance with (2) The transformer alarms will be connected to ANSI Standard C 57.12.10 and will include the fol- the plant annunciator system and will require 125 lowing optional features. Vdc for the alarm system auxiliary relays. Protec- a. Rating. tive devices, which will be mounted in the trans- (1) The generator stepup transformer kVA rat- former with control and indication leads run by the ing for boiler-turbine-generator “unit type” power transformer manufacturer to the control cabinet, plants will depend upon the generator kVA rating are as follows: which, in turn, is dependent upon the prime mover (a) Oil low level gauge with alarm contacts. ratings. In any event, the transformer kVA rating (b) Top oil temperature indicator with alarm will be selected so that it is not the limiting factor contacts. for station output. (c) Winding hot spot oil temperature indica- (2) As a rule of thumb, the top kVA rating will tor with two or more sets of electrically independent be selected to be approximately 115-120 percent of control and alarm contacts, the number depending the KVA rating of the generator. Since the genera- on whether unit is FOA, O/FA, or OA/FA/FA. tor unit auxiliary transformer load is tapped off be- (d) Sudden gas pressure Buchholz type relay tween the generator and stepup transformer and with alarm contacts and external reset button. will amount to about 6 percent of the generator rat- (e) Pressure relief device with alarm contacts ing, the operating margin for the stepup transform- and with operation indicator clearly visible from er will be on the order of 20-25 percent. This will per- ground level. mit making full use of the margin the turbine gener- (f) Pressure/vacuum gauge with electrically ator manufacturer must build in, in order to meet independent high and low alarm contacts; gauge to his guarantees. be visible from ground level. (3) If the load served is expected to be quite (g) Full set of thermally protected molded constant and the generator will be operating at a case circuit breakers and auxiliary control and high load factor, it should be cost effective to obtain alarm relays for denotingan FOA (forced oil/air cooled) transformer. Pumps -Loss of preferred fan pump power source.and fans are on whenever the transformer is ener- -Automatic throwover of fan and pump sources onegized. If, on the other hand, a widely varying load is or two.expected, it may be cost effective to obtain a dual -Loss of control power.rated transformer OA/FA, or even triple rated (3) The control compartment will have a dualOA/FA/FA having two increments of fan cooling as hinged door readily accessible from finished gradewell as a self-cooled rating. The top rating would co- level; bottom of compartment will be about 3 feetordinate with the generator rating but fans would above grade. Thermostat and heaters will be provid-shut down when the unit is operating at partial load. ed,The resulting rating of the turbine, generator and c. Miscellaneous. Miscellaneous items that will bestepup transformer for typical unit might be: included are as follows: Turbine 25,000 kW (1) Control of the fixed high side winding taps G e n e r a t o r 31,250 kVA at 0.8 PF will be accessible to a person standing on the Transformer 35,000 kVA at OA/FA/FA rat- ground. The control device will permit padlocking ing with the selected tap position clearly visible. (4) Voltage of the high side will match the nomi- (2) Base of transformer will be on I-beams suit-nal operating voltage desired for the distribution able for skidding the transformer in any direction.system, such as 34.5 kV; and for the low side will (3) Two 600-5 or 1200-5 multi-ratio bushingmatch the generator voltage, such as 13.8 kV. High ct’s will be provided on each of the high side and lowvoltage side will have two 2 1/2 percent full capacity side bushings with all leads brought to terminaltaps above and “below rated voltage. blocks in the control cabinet. b. Control. (4) One 600-5, or lesser high current rating, (1) Both the fan and pump systems will operate bushing ct will be provided on the high side neutralon 208 volts, 60 Hz, single phase. The control sys- bushing with leads brought to a terminal block intem will provide automatic throwover from dual 208 the control compartment.volt sources with one being preferred and the otheralternate; either may be selected as preferred via a 4-10. Auxiliary transformersselector switch. Sources will be run from separate a. Rating.4-16
  • TM 5-811-6 (1) As a rule of thumb, the unit auxiliary trans- 4-11. Unit substation transformerformer for a steam electric station will have a kVA a. Definition. The phrase “unit substation” israting on the order of 6 to 10 percent of the genera- used to denote a unit of equipment comprising ator maximum kVA rating. The percent goes down transformer and low-side switchgear designed andslightly as generator kVA goes up and coal fired factory assembled as a single piece of equipment. Itplants have highest auxiliary power requirements is used herein to denote an intermediate voltage re-while gas fired plants have the least. The actual rat- ducing station fed by one or two circuits from theing specified for an installation will be determined auxiliary switchgear and, in turn, serving a numberfrom the expected station service loads developed of large motors or motor control centers. The break-by the design. The station startup and standby aux- ers will have lower ratings than those in the auxilia-iliary transformer for plants having a unit system ry switchgear but higher ratings than those in thewill have a kVA rating on the order of 150 percent of motor control centers. The transformer in the “unita unit auxiliary transformer— say 10 to 12 percent of substation” is referred to as a “unit substationthe maximum generator kVA. The additional capac- transformer.”it y is required because the transformer acts as 100 (1) The term “unit auxiliary transformer” ispercent spare for the unit auxiliary transformer for used to denote the transformer connected to theeach of one or more generators, while also serving a generator leads that provides power for the auxilia-number of common plant loads normally fed from ries of the unit to which it is connected. It feeds thethis source. If the auxiliary power system is not on “auxiliary switchgear” for that unit.the unit basis; i.e., if two or more auxiliary trans- (2) The “unit stepup transformer” designatesformers are fed from the station bus, sizing of the the stepup transformer that is connected perma-auxiliary transformer will take into account the aux- nently to the generator terminals and connects thatiliary power loads for all units in the station plus all generator to the distribution system.common plant loads. The sizing of auxiliary trans- b. Rating. For steam electric stations there willformers, in any case, will be subject to an analysis of be a minimum of two unit substations per turbineall loads served under any set of startup, operating, installation so that each can be located near an areaor shutdown conditions with reasonable assumed load center to minimize the lengths of cables serving transformer outages and will include a minimum of the various low voltage loads. The kVA rating of the 10 percent for future load additions. transformer in each unit substation will be suffi- (2) Auxiliary transformer voltage ratings will cient to handle the full kVA of the connected load,be compatible with the switchyard voltage and the including the starting kVA of the largest motor fedauxiliary switchgear voltages. Two 2 1/2 percent taps from the center, plus approximately 15 percent forabove and below rated voltage on the high voltage future load additions. For diesel engine or gas tur-side will be included f or each transformer. bine installations, these unit substations may not be b. Control. required or one such unit substation may serve more (1) One step of fan control is commonly pro- than one generating unit.vided, resulting in an OA/FA rating. Fan control for c. Control. No fans or pumps are required andauxiliary transformers will be similar to that de- thus no control voltage need be brought to the scribed for the generator stepup transformer, except transformer.that it is not necessary to provide for dual power d. Alarms. Protective devices will be mounted on sources to the fans. Since the unit auxiliary and the the transformer with alarm leads run to an easily ac- station auxiliary transformers can essentially fur- cessible terminal board. Devices will include a wind-nish power for the same services, each transformer ing hot spot temperature indicator having two serves as a spare for the other. Also, if a fan source alarm stages for two temperature levels with elec- fails, the transformer it serves can still be operated trically independent alarm contacts. On occasion, it continuously at the base self-cooled rating. will be found that design and construction of the (2) The protective devices and alarms will be unit substation transformer and its physically at- identical to those of the generator stepup trans- tached 480-volt switchgear may require the ground former. indication pt’s and their ground indicating lamps to (3) The control compartment will be similar to be mounted within and on the transformer venti- that of the generator stepup transformer. lated enclosure. In this event, the ground alarm re- c. Miscellaneous. The miscellaneous items will be lays will be mounted in a readily accessible portion similar to those for the generator stepup transform- of the enclosure with leads brought to terminal er, except that only one set of multi-ratio bushing blocks for external connection to the control room ct’s need be provided on each of the high and low annunicator. side bushings. 4-17
  • TM 5-811-6 Section V. Protective RELAYS AND METERING 4-12. Generator, stepup transformer face heating of the rotor. The generator is designed and switchyard relaying to accept a specified amount of this current con- a. General. Selection of relays and coordination of tinually and higher amounts for short periods with- their settings so that the correct circuit breaker in a specified integrated time-current square (I22t) trips when it is supposed to, and does not trip when limit. The negative sequence relay (ANSI device 46) it is not supposed to is a subject too broad to be cov- is to remove the unit from service if these limits are ered herein. For the purpose of this document the exceeded.. listings below will set forth those protective relay (5) The reverse power relay (ANSI device 32) is types which will be considered. used to trip the generator from the system in case it b. Generator relaying. Each generator will be pro- starts drawing power from the system and driving vided with the following protective relays: its primemover. –Three – Generator differential relays (ANSI De- (6) A ground on the generator field circuits is vice 87) not serious as long as only one ground exists. How- –One – Lockout relay, electrical trip, hand reset ever, a second ground could cause destructive vibra- (ANSI Device 86) tions in the unit due to unbalanced magnetic forces. –One – Loss of field relay (ANSI Device 40) The generator field ground relay (ANSI device 64) is –One – Negative sequence relay (ANSI Device 46) used to detect the first ground so the unit can be –One – Reverse power relay (ANSI Device 32) shut down or the condition corrected before a second –One – Generator field ground relay (ANSI Device ground occurs. 64) (7) The phase time-overcurrent relays (ANSI –Three – Phase time overcurrent relays, voltage device 51) are used for overload protection to pro- restrained (ANSI Device 51V) tect the generator from faults occurring on the sys- —One – Ground overcurrent relay in the generator tem. neutral (ANSI Device 5 lG) (8) The ground overcurrent relay (ANSI 51G) in Although not a part of the ANSI device identifica- the generator neutral is used to confirm that a tion system, generator relay numbers are frequently ground fault exists before other ground relays can suffixed with a letter-number sequence such as operate, thus preventing false trips due to unbal- ‘(G1”. For instance, differential relays for generator antes in circuit transformer circuits. 1 would be 87G 1 and for generator 2 would be 87G2. d. Power transformer relaying. Each stepup c. Relay functions. transformer will be provided with the following pro- (1) It is usual practice in relay. application to tective relays: provide two separate relays that will be activated by (1) Three – Transformer differential relays a fault at any point on the system. In the case of a (ANSI Device 87).generating unit with an extended zone of differential (2) One–Transformer neutral time over-current -protection including generator, feeder, auxiliary relay to be used as a ground fault detector relaytransformer, stepup transformer and circuit break- (ANSI Device 51G)er, it is also common practice to use a dedicated zone (3) One–Transformer sudden gas pressure re-of differential protection for the generator as back- lay. This device is specified and furnished as part ofup protection. the transformer (ANSI Device 63). (2) The lockout relay (ANSI device 86) is a hand (4) For application in a “unit system” wherereset device to control equipment when it is desired the generator, the stepup transformer, and the aux-to have the operator take some positive action be- iliary transformer are connected together perma-fore returning the controlled equipment to its nor- nently, an additional differential relay zone is estab-mal position. lished comprising the three items of equipment and (3) If a unit operating in parallel with other the connections between them. This requires threeunits or a utility system loses its excitation, it will additional differential relays, one for each phase,draw excessive reactive kVA from the system, shown as Zone 1 in Figure 4-3.which may cause other difficulties in the system or e. Auxiliary transformer relaying. These transfor-may cause overloads in the generator. The loss of mers will each be provided with the following pro-field relays (ANSI device 40) will sense this situa- tective relays:tion and initiate a safe shutdown. (1) Three–Transformer differential relays (4) Negative sequence currents flowing in a gen- (ANSI Device 87)erator armature will cause double frequency mag- (2) One–Lockout relay (ANSI Device 86)netic flux linkages in the rotor and may cause sur- (3) One–Transformer netural time overcurrent4-18
  • TM 5-811-6 relay to be used as a fault detector relay (ANSI De- (1) Incoming line: three–long time and short vice 51G) time elements. (4) One–Transformer sudden gas pressure re- (2) Motor control center feeders: three–long lay (ANSI Device 63). time and short time elements. f. Switchyard bus relaying. Each section of the (3) Motor feeders: three–long time and instan- switchyard bus will be provided with bus differen- taneous elements. tial relaying if the size of the installation, say 25,000 c. Motor control center protection (480-volt sys- kW or more, requires high speed clearing of bus tem). Because of the lower rating, breakers will be faults. molded case type employing thermal/magnetic ele- g. Distribution feeder relaying. Whether feeders ments for protection on direct feeders. Combination emanate from the switchyard bus at, say 34.5kV, or starters will employ three thermal protective heater from the generator bus at 13.8 kV, the following re- type elements in conjunction with the starter. lays will be provided for each circuit: (1) Three–Phase time overcurrent relays with 4-14. Instrumentation and metering instantaneous element (ANSI Device 50/5 1). The following instruments will be mounted on the. (2) One–Residual ground time overcurrent re- control board in the operating room to provide the lay with instantaneous element (ANSI Device operator with information needed for operations: 50/51 N). a. Generator. h. Ties to utility. Relaying of tie lines to the util- (1) Ammeter with phase selector switch ity company must be coordinated with that utility (2) Voltmeter with phase selector switch and the utility will have its own standards which (3) Wattmeter must be met. For short connections, less than 10 (4) Varmeter miles, pilot wire relaying is often used (ANSI device (5) Power factor meter 87PW). For longer connections, phase directional (6) Frequency meter distance and ground distance relays are often used (7) Temperature meter with selector switch for (ANSI device 21 and 21 G). Various auxiliary relays stator temperature detectors will also be required. Refer to the utility for these tie (8) D.C. volmeter for excitation voltage line protective relaying requirements. (9) D.C. ammeter for field current b. Stepup transformer. 4-13. Switchgear and MCC protection (1) Voltmeter on high voltage side with selector a. Medium voltage switchgear (4160 volt system). switch (1) The incoming line breaker will be provided (2) Ammeter with selector switch with: Three-Phase time overcurrent relays set (3) Wattmeter high enough to provide protection against bus faults (4) Varmeter on the switchgear bus and not to cause tripping on (5) Power factor meter feeder faults (ANSI Device 50/51). c. Auxiliary transformer. (2) Each transformer feeder will be provided (1) Voltmeter on low voltage side with selector with: switch (a) Three-Phase time overcurrent relays (2) Ammeter with selector switch with instantaneous trip attachments (ANSI Device (3) Wattmeter 50/51). (4) Varmeter (b) One–Residual ground time overcurrent (5) Power factor meter relay with instantaneous trip attachment (ANSI d. Common. Device 50N/51N). (1) Voltmeter with selector switch for each bus (3) Each motor feeder will be provided with: (2) Synchroscope (a) Three–Phase time overcurrent relay e. Integrating meters. The following integrating (ANSI Device 50/51). meters will be provided but need not be mounted on (b) One–Replica type overcurrent relay the control board: (ANSI Device 49) (to match motor characteristic (1) Generator output watthour meter heating curves). (2) Auxiliary transformer watthour meter for (4) Each bus tie will be provided with: Three– each auxiliary transformer. Phase time overcurrent relays (ANSI Device 50). f. Miscellaneous. For units rated 20,000 kW or b. Unit substation switchgear protection (480 volt larger, a turbine-generator trip recorder will be pro- system). Breakers in the 480-volt substations uti- vided but not necessarily mounted on the control lize direct acting trip devices. These devices will be board. This is for use in analyzing equipment fail- provided as follows: ures and shutdowns. 4-19
  • TM 5-811-6 Section Vl. STATlON SERVlCE POWER SYSTEMS 4-15. General requirements c. Impedance. a. Scope. The power plant station service electric- (1) Impedance should be selected so that the al system will consist of the following voltage drop during starting of the largest motor on (1) For steam turbine plants of about 20,000 an otherwise fully loaded bus will not reduce motor kW or larger, a medium voltage (4.16 kV) distribu- terminal voltage below 85 percent of the nominal tion system utilizing outdoor oil filled auxiliary bus voltage to assure successful motor starting power transformers and indoor metal clad drawout under adverse conditions and so that the symmetri- type switchgear assemblies. Usually a medium vol- cal short circuit current on the low voltage side will tage level of 4.16 kV is not required until generator not exceed 48 kA using 4160 volt rated switchgear unit sizes reach approximately 20 MW. A 4.16 kV or 41 kA for 4.16 kV system where 2400 volt switch- system may be grounded permitting the use of gear is to be used. This permits using breakers hav- phase and ground protective relays. ing an interrupting rating of 350 MVA for 4160 (2) A low voltage (480-volt and 208/120-volt) volts swichgear or 300 MVA for 2400 volt switch- distribution system, unit substation assemblies, gear. and also motor control centers containing combina- (2) Meeting these criteria is possible for units of tion starters and feeder breakers. the size contemplated herein. If the voltage drop (3) Station power requirements are smaller for when starting the largest motor exceeds the criteri- combustion gas turbine units and diesel engine driv- on with the fault current limited as indicated, al- en generators. For the combustion gas turbine ternative motor designs and reduced voltage start- plant, a starting transformer capable of supplying ing for the largest motor or alternative drives for the starting motors is required if the turbine is mo- that load, will be investigated. tor started, but may serve more than one unit. For d. Transformer connections. diesel plants a single 480-volt power supply with (1) With the unit system, the turbine generator appropriate standby provisions is adequate for all unit auxiliary transformers will be 13.8 kV delta to units. 4.16 kV wye. If the startup and standby auxiliary b. Operating conditions and redundancy. The sta- transformer is fed from a bus to which the generator tion service system will be designed to be operation- is connected through a delta-wye transformation, it al during station startup, normal operation and nor- must be wye-wye with a delta tertiary. The wye-wye mal shutdown. Redundancy will be provided to per- connection is necessary to get the correct phase rela- mit operation of the plant at full or reduced output tionship for the two possible sources to the 4160 during a component failure of those portions of the volt buses. Voltage phase relationships must be con- system having two or more similar equipments. sidered whenever different voltage sources are in c. Switchgear and motor control center location. parallel. For wye-wye or delta-delta transformer con- Switchgear inside the power plant will be located so nections, there is no phase shift between theas to minimize the requirements for conduit to be primary and secondary voltages. However, forembedded in the grade floor slab. In steam electric delta-wye or wye-delta transformer connections, theplants it will generally be convenient to have one or primary and secondary voltage will be 30 degreesmore motor control centers at grade with top en- out of phase in either a leading or lagging relation-trance of control and power cables. The 4160-volt ship. With the correct arrangement of transformersswitchgear and 480-volt unit substation will prefer- it will be possible to establish correct phase anglesably be located on upper floor levels for maximum for paralleling voltages from different sources. Figconvenience in routing power cables; control and ures 4– 1, 4-2 and 4-3 illustrate the typical phase re-power cables can thus enter from either above or be- lationships for power station generators and trans-low. The 480-volt switchgear in combustion gas tur- formers.bine or diesel plants will be at ground level. (2) Where more than one generator is installed, a single startup and standby auxiliary transformer4-16. Auxiliary power transformers is sufficient. The low side will be connected through a. Type. The auxiliary power transformers will be suitable switches to each of the sections of mediumoil filled, outdoor type, having both natural and voltage switchgear,forced air cooled ratings. b. Taps. Four full capacity taps for deenergized 4-17. 4160 volt switchgeartap changing will be provided on the high voltage a. Type. The 4160 volt assemblies will be indoorside, in two 2 1/2 percent increments above and below metal clad, drawout type employing breakers hav-rated voltage. ing a symmetrical interrupting rating of 48 kA and4-20
  • TM 5-811-6with copper or aluminum buses braced to withstand receptacle system and the like. Loads should bethe corresponding 350 MVA short circuit. Quantity grouped in such a manner as to result in relativelyof breakers will be determined to handle incoming short feeder runs from the centers, and also to facili-transformer, large motors above 200 hp and trans- tate alternate power sources to vital services.former feeds to the 480 volt unit substations. d. Cable space. Connection to the MCC’s will be b. Cable entrance. Power and control cable en- via overhead cable tray, and thus the top horizontaltrance from above or below the gear will depend on section of the MCC will incorporate ample cablefinal locations in the power plant. training space. Control and power leads will termi- c. Relaying. Appropriate protective relaying will nate in each compartment. The MCC’s can be de-be applied to each incoming and outgoing circuit as signed with all external connections brought by thediscussed in paragraph 4- 13a above. manufacturer to terminal blocks in the top or bot- tom horizontal compartments, at added expense.4-18. 480 volt unit substations e. Enclosures. Table 4-1 lists standard MCC en- a. General arrangement. The unit substation as closures. Type 2, drip tight, will be specified for alldefined in subparagraph 4-1 la, or power centers, indoor power plant applicants; Type 3, weather re-employ a 4160-480 volt transformer close coupled sistant, for outdoor service. The other types listed into a section of 480 volt switchgear. Switchgear por- Table 4-1 should be used when applicable.tion will utilize drawout breakers and have breakersand buses braced to interrupt and withstand, re- 4-20. Foundationsspectively, a short circuit of 42 kA, symmetrical. a. Transformers. The outdoor auxiliary powerBuses may be of aluminum or copper. transformers will be placed on individual reinforced b. Loads served. The unit substations will serve concrete pads.as sources for 480-volt auxiliary motor loads be- b. Medium voltages switchgear. The medium volt-tween 75 and 200 horsepower, and also serve as sup- age switchgear assemblies will be mounted on flushply to the 480-volt motor control centers. embedded floor channels furnished by the switch- c. Cable entrance. Power and control cable en- gear manufacturer prior to shipment of the gear.trance from above or below will depend on final loca- c. Unit substations and motor control centers.tion in the station. 480-volt unit substation transformers and switch- d. Trip devices. Direct acting trip devices will be gear, and all MCCs will be mounted on chamferedapplied to match the appropriate transformer or concrete pads at least 3 inches above finished floormotor feeder load and fault characteristics as dis- grade. Foundations will be drilled for clinch anchorscussed in paragraph 4- 13b above. after the foundation has been poured and set; the anchor placement will be in accordance with the4-19. 480-volt motor control centers switchgear manufacturer’s recommendation. a. General arrangement. Motor control centers(MCC’S) will utilize plug-in type circuit breakers and 4-21. Groundingcombination starters in either a front only or a back- A minimum 1/4-inch by 2-inch copper ground busto-back free standing construction, depending on will be incorporated within the lower rear of eachspace limitations. Main bus, starters and breakers section of switchgear and MCC. Each ground bus .will be braced to withstand a short circuit of 22 kA, will be connected to the station ground grid withsymmetrical. A power panel transformer and feeder two 4/0 stranded copper cables.breaker, complete with a 120/208 volt power paneland its own main breaker, may be built into the 4-22. Conduit and tray systemsMCC. a. Power cables. Power cables will generally be b. Current limiting reactors. Dry type three phase run in galvanized rigid steel conduit to the motorreactors, when necessary, will be located in a verti- and switchgear terminations, although a laddercal section of the MCC’s to reduce the available type galvanized steel cable tray system having ade-short circuit at the 480-volt unit substations to 22 quate support may be used with conduit runoutskA at the MCC’s. Each system will be investigated from trays to terminations.to determine the necessity for these current limiting b. Control cables. Control cables will be run in anreactors; cable reactance will play an important part expanded metal galvanized steel overhead tray sys-in determining the necessity for reactors. tem wherever possible. Adequate support will be c. Location. The several motor control centers provided to avoid sagging. Exit from the tray willwill be strategically located in the power plant to be via rigid steel conduit.serve most of the plant auxiliary motor loads, light- c. Grounding. Every cable tray length (i.e., eaching transformers, motor operated devices, welding construction section) will be grounded by bolting to 4-21
  • TM 5-811-6 Table 4-1. Standard Motor Control Center Enclosures. NEMA Classification Comments Type 1: General purpose . . . . . . . . . . . . . . A sheet metal case designed primarily to protect against accidental contact with the control mechanism. Type 1: Gasketed . . . . . . . . . . . . . . . . . . . . . The general purpose enclosure with gasketed door or cover. Type 2: Drip tight . . . . . . . . . . . . . . . . . . . Similar to Type 1 with the addition of drip shields or the equivalent. Type 3: Weather-resistant ............ Designed to provide protection against weather hazards such as rain and sleet. Type 4: Watertight ................... Designed to meet the hose test described in NEMA Definition lC-1.2.6B. Type 7: Hazardous locations, Class 1, Air break . . . . . . . . . . . . . . . . . . . . Type 9: Enclosures designed to meet the application Hazardous locations, Class 2, requirements of the NEC for the indicated Groups F & G. . . . . . . . . . . . . . . . . specific classes of hazardous locations. Type 9-C: Hazardous locations, Class 2, Group E. . . . . . . . . . . . . . . . . . . . . Type 12: Industrial use . . . . . . . . . . . . . . . A sheet metal case designed with welded corners and no knockouts to meet the Joint Industry Conference standards for use where it is desired to exclude dust, l i n t , fibers and fillings, and oil or coolant seepage. Source: NAVFAC DM3a stranded bare copper ground cable which will be 4-23. Distribution outside the powerrun throughout the tray system. The tray cable it- plantself will be tapped to the plant ground grid at each Electrical distribution system for the installationbuilding column. Basic tray cable will be 4/0 bare outside of the power plant is covered in TMstranded copper with connections to station taps of 5-811-11AFM88-9.minimum 2/0 copper.4-22
  • TM 5-811-6 Section Vll. EMERGENCY POWER SYSTEM 4-24. Battery and charger ously. To assure, however, that the manufacturer of a. General requirements. The dc system, consist- all dc operated devices is aware of the source of dc ing of a station battery, chargers and dc distribution system voltage, the various equipment specifica- panels, provides a continuous and reliable source of tions will advise that the nominal system voltage dc control voltage for system protection during nor- will be 125 volts but will have an equalizing charge mal operation and for emergency shutdown of the applied periodically. power plant. Battery will be nominal 125 volts, (2) Appurtenances. The following instruments mounted on wooden racks or metal racks with PVC and devices will be supplied for each charger: covers on the metal supporting surfaces. Lead calci- (a) Relay to recognize loss of ac supply. urn cells having pasted plates Plante or other suit- (b) Ac voltage with selector switch. able cells will be considered for use. (c) Dc ground detection system with test de- b. Duty cycle. Required capacity will be calcu- vice. lated on an 8-hour duty cycle basis taking into ac- (d) Relay to recognize loss of dc output. count all normal and emergency loads. The duty (e) Relay to alarm on high dc voltage. cycle will meet the requirements of the steam gen- (f) Relay to alarm on low dc voltage. erator burner control system, emergency cooling (g) Dc voltmeter. systems, control benchboard, relays and instrument (h) Dc ammeter with shunt.panels, emergency lighting system, and all close/trip d. Battery room. Only the battery will be locatedfunctions of the medium voltage and 480-volt cir- in a ventilated battery room, which will be in accord-cuit breaker systems. In addition, the following ance with TM 5-811-2. The chargers maybe wall oremergency functions shall be included in the duty floor mounted, together with the main dc distribu-cycle: tion panel, immediately outside the battery room. (1) Simultaneously close all normally open e. DC distribution panel. The distribution panelbreakers and trip 40 percent of all normally closed will utilize molded case circuit breakers or fuses se-breakers during the first minute of the duty cycle; lected to coordinate with dc breakers furnished induring the last minute, simultaneously trip all main control panels and switchgear. The breakers will beand tie breakers on the medium voltage system. equipped with thermal magnetic trip devices, and (2) One hour (first hour) running of the turbine for 20 kA dc interrupting rating.generator emergency lube oil pump motor and, forhydrogen cooled units, 3-hour running of the emer- 4-25. Emergency ac systemgency seal oil pump motor. Those portions of the station service load that must (3) One hour (first hour) running of the backup be operable for a safe shutdown of the unit, or thatturning gear motor, if applicable. are required for protection of the unit during shut- c. Battery chargers. down, will be fed from a separate 480-volt unit (1) Two chargers capable of maintaining a 2.17 emergency power bus. A suitable emergency dieselthe proper float and equalizing voltage on the bat- engine driven generator will be installed and ar-tery will be provided. Each charger will be capable ranged to start automatically and carry these loadsof restoring the station battery to full charge in 12 if the normal source of power to this bus is lost. Thehours after emergency service discharge. Also, each loads fed from this bus might include such things asunit will be capable of meeting 50 percent of the to- emergency lighting, communication system, bat-tal dc demand including charging current taken by tery charger, boiler control system, burner controlthe discharged battery during normal conditions. system, control boards, annunciator, recorders andNote: Equalizing voltage application will subject instrumentation. Design of these systems will pro-coils and indicating lamps to voltages above the vide for them to return to operation after a briefnominal 125-volt dc system level. These devices, power outage.however, will accept 20 percent overvoltage continu- Section Vlll. MOTORS4-26. General weatherproof construction employing labyrinthMotors inside the power plant require drip proof en- type enclosures for air circulation will be applied.closures, while outside the plant totally enclosed fan All motors will be capable of starting at 85 percentcooled motors are used. For induced draft and forced nameplate voltage.draft, and outdoor fan motors in the larger sizes, a 4-23
  • TM 5-811-6 4-27. Insulation Above 200 horsepower, three phase, 4/0 bare a. 4000-volt motors. Motors at this voltage will stranded copper wire will be used for the ground be three phase, 60 Hz, have Class B insulation for 80 connection. C. rise above 40 C. ambient, and with 1.0 service 4-30. Conduit factor. b. 460-volt motors. These motors will be three Motor power cables will be run in rigid steel galvan- phase, 60 Hz, have Class B insulation for 80 C. rise, ized conduit to a point approximately 18 inches or Class F for 95 C. rise, above 40 C. ambient, and from the motor termination or pull box. The last 18 with 1.0 service factor. inches, approximately, will be flexible conduit with c. 115-volt motors. These motors will be one PVC weatherproof jacket. Firm support will be giv- phase, 60 Hz, with Class B insulation for 80 C. rise en the rigid conduit at the point of transition to the above 40 C. ambient, and with 1.25 service factor. flexible conduit. 4-28. Horsepower 4-31. Cable It is seldom necessary to specify motor horsepower In selecting motor cable for small motors on a high if the motor is purchased with the driven equipment capacity station service power system, the cable size as is the usual case with military projects. In almost is seldom set by the motor full load current. Manu- every instance, the load required by the pump, fan, facturer’s curves showing copper temperature melt- or other driven equipment sets the motor horse- ing values for high short circuit currents for a spe- power and characteristics-thus the specification is cific time duration must be consulted; the cable may written to require manufacturer of the driven ma- need to be appreciably larger than required by chine to furnish a motor of proper horsepower and motor full load current. characteristics to perform the intended function. 4-32. Motor details 4-29. Grounding It is important to specify enclosure type, special Every motor will be connected to the station ground high temperature or other ambient conditions and grid via a bolted connection to a stranded copper similar data which is unique to the particular appli- tap. Single phase motors may be grounded with #6 cation. Also the type of motor, whether squirrel AWG bare wire; to 75 horsepower, three phase with cage, wound rotor or synchronous, and power sup- #2 AWG bare stranded copper cable; and to 200 hp, ply characteristics including voltage, frequency, three phase, with 2/0 bare stranded copper wire. and phases must be specified. Section IX. COMMUNICATION SYSTEMS 4-33. Intraplant communications into the private conversation already taking place. a. General requirements. Installation of a high Any number of parties will be able to participate in quality voice communication system in a power the “private conversation” because the private sys-‘ plant and in the immediate vicinity of the plant is tem is a party line system. vital to successful and efficient startup, operation (4) Additional handsets and speakers can be and maintenance. The communications system se- added to the basic system as the power plant or out- lected will be designed for operation in a noisy en- door areas are expanded. vironment. c. Handsets. b. Functional description. A description of the (1) Except for handsets at desks in offices or features of an intraplant communication system is operating rooms, the indoor handsets in the power given below. plant will be hook switch mounted in a metal enclos- (1) A page-talk party line system will be re- ure having a hinged door. They will be mounted on quired. building columns approximately 5 feet above the (2) If a conversation is in process on the party floor. In particularly noisy areas, e.g., in the boiler line when a page is initiated, the paging party will feed pump and draft fan areas, the handsets will be instruct the party paged to respond on the “page” of the noise canceling types. system. This second conversation will be carried on (2) Desk type handsets will be furnished either over the page system—that is, both parties will be for table top use or in “wall-mounting” hook switch heard on all speakers, except that the speakers near- type for mounting on the side of a desk. The hook est the four or more handsets in use will be muted. switch wall mounting will also be used at various (3) If a party wishes to break into a private con- control boards for ease of use by the plant control versation, all he will do is lift his handset and break room operators. 4-24
  • TM 5-811-6 (3) Outdoor handsets will be hook switch area configuration but a handset will be readilymounted in a weatherproof enclosure having a available to any operator performing an operatinghinged door. They will be mounted on the switch- function.yard structure or other structure five feet above d. Speakers.final grade. (1) Speakers for general indoor use will be of (4) Flexible coil spring type cords will be sup- relatively small trumpet type and will be weather-plied with each handset to permit freedom of move- proof for durability. They will be mounted on build-ment by the caller. In the control room provide extra ing columns about 10 feet above floor level withlong cords. The spacing depends upon the operating spacing as indicated in Table 4-2. Table 4-2. Suggested Locations for Intraplant Communication Systems Devices. For Speakers Handsets Control Room Two ceiling speakers. Desk set on operator’s desk; handsets spaced about 10- feet apart on control benchboards and on each isolated control panel. Offices Ceiling speaker in Desk set in each office. Sup’t. and Assistant Sup’t. o f f i c e s . Locker Room Wall speaker in locker Wall handset in locker room. room. Plant Column mounted speakers Column mounted handsets, as necessary to provide as necessary to provide coverage of work areas. convenient access. The required spacing will depend upon plant layout, equipment loca- tion and noise levels. Switchyard Minimum two structure Mininum two structure mounted speakers at mounted handsets at quarter diagonally opposite points on longitudinal corner of structure. centerline of structure. Cooling tower area Speaker mounted on Two handsets; one inside cooling tower auiliary auxiliary building; one building facing tower. mounted on outside wall. Fuel oil unloading Minimum two speakers on One handset near pump area area (or coal handl- structures (one inside (one handset inside grade ing area) crusher house). door or crusher house). Gate house (if power Speaker on outside of One handset outside fence, plant area is fenced) gate house. at personnel or vehicle gate. Note: Speakers and handsets for inside-the-power plant coverage will be provided at every floor and mezzanine level from basement to uppermost boiler platform. Courtesy of Pope, Evans and Robbins (Non-Copyrighted) 4-25
  • TM 5-811-6 (2) Speakers for outdoor use will be large It is not necessary to have a speaker and a handsettrumpet type, weatherproof. They will be mounted mounted near to one another. Speakers will be posi-on the switchyard structure or other structure tioned to provide “page” coverage; handsets will beabout 15 feet above final finished grade. placed for convenience of access. For example, a (3) In the control room, two flush mounted speaker may be mounted outdoors to cover a tankspeakers will be installed in the ceiling. A wall area, while the nearest handset may be convenientlymounted speaker in wooden enclosure will be pro- located immediately inside the plant or auxiliaryvided for the plant superintendent’s office, training building adjacent to the door giving access to theroom or other similar location. tanks. e. Power supply. g. Suggested device locations. Table 4-2 shows (1) Power supply will be 120 Vat, 60 Hz, single suggested locations for the various intraplant com-phase as supplied from the emergency power sup- munication systems devices.ply. The single phase conductors will be run in theirown conduit system. It is vital to have the plant 4-34. Telephone communicationscommunication system operable under all normal At least one normal telephone desk set will be pro-and emergency conditions. vided in the central control room for contact by the (2) The manufacturer will be consulted regard- operators with the outside world and for contacting type of power supply cable, as well as type, with the utility company in the event of parallelshielding, and routing of the communication pair operation. For those instances when the power plantconductors. is connected into a power pool grid, a direct tele- f. Device locations, general. Proper selection and phone connection between the control room and theplanning for location of components is necessary to pool or connected utility dispatcher will also be pro-ensure adequate coverage. Alignment of speakers is vided.important so as to avoid interference and feedback.
  • TM 5-811-6 CHAPTER 5 GENERAL POWER PLANT FACILITIES DESIGN Section l. lNSTRUMENTS AND CONTROL SYSTEMS 5-1. General unit. Coal handling, ash handling and water treatingq Input adjustments will be designed to be delegated panels will not be located in the central control room to automatic control systems except during startup, unless the plant is small and the operating crew may shutdown, and abnormal operating conditions when be reduced by such additional centralizing. If the the operator. displaces or overrides automatic con- plant has a header system which is not conducive to trol functions. boiler-turbine panels, group controls and instru- ments into a boiler panel for all boilers and a turbine 5-2. Control panels generator panel for all turbines whenever practic-  a. Types and selection. able. Usually, a separate electrical panel with mimic (1) General types. Control panels used in power bus for the generators and switchgear and switch- plants may be free standing or mounted on a wall or yard, if applicable, will be provided regardless of column, as appropriate. whether the mechanical instruments are grouped on (2) Central control panel selection. Control a unit basis or a header basis. panels for use in central control rooms will be en- (2) Local panels. These will be mounted as close closed and of the dual switchboard, duplex switch- to the equipment (or process) they are controlling as board, dual benchboard, control benchboard, or con- is practical. trol desk type depending upon the size of the plant c. Instrument selection and arrangement on and complexity of the instruments and controls to panels. Selection and arrangement of the various be mounted. When control panels have complex wir- controls, instruments and devices on the panels will ing (piping and devices mounted in the interior) the be generally in accordance with the guidelines of vertical panel section will be provided with rear or Tables 5-1,5 -2,5-3 and 5-4, and the following walk-in access for ease in erection and maintenance. (1) Items. Mechanical items will be grouped by Frequently the floor of the walk-in space is dropped basic function (i.e., turbine, boiler, condensate, feed- .2 or 3 feet below the raised control room floor to sim- water, circulating water, service water and like sys- plify cable and tubing entrance to the panel interior tems), Burner management controls will be obtained and to increase space for terminals. A dropped floor as an “insert” or subpanel which can be incorporat- will be provided for proper access to any benchboard ed into the boiler grouping of controls and instru- section of a panel. The shape of the panel will be se- ments. Such an insert may include remote lightoff. lected using the following criteria: and startup of burners if desired. Electrical items (a) Space availability in the control room. will be grouped by generator, voltage regulator, (b) Number of controls and instruments to be switchgear and like equipment items in a manner mounted. which is easily incorporated into a mimic bus. (c) Visibility of the controls and instruments (2) Readability. Instruments which require by the plant operators. operator observation will be located not higher than (d) Grouping and interrelationship of the con- 6 1/2 feet nor lower than 3 feet above the floor for trols and instruments for ease of operation and easy readability. avoidance of operating error. (3) Controls, switches and devices. Those con- b. Location of panels. trols, switches and other devices which require (1) Control room. The various panels located in manipulation by the operators will be easily access- the central control room will be arranged to mini- ible and will be located on a bench or desk wherever mize operator wasted motion. In a unitized power practicable. plant (one without a header system), provide a (4) Indicators versus recorders. Indicators will boiler-turbine mechanical panel (or section) for each be provided where an instantaneous reading of cycle‘ unit with separate common panel(s) to accommodate thermodynamic or physical parameters suffices as a compressed air, circulating water, service water and check of proper system operation. When a perma- like system which may pertain to more than one nent record of plant parameters is desired for eco- 5-1
  • TM 5-811-6 Table 5-1. List of Typical Instruments and Devices to be Provided for Boiler Turbine Mechanical Panel Measurement Primary Element Instrument or or Device Fluid Location Device on Panel Pressure Steam Boiler drum Indicator Steam Boiler atomizing steam Indicator Steam Turbine Throttle Indicator Steam Deaerator steam space Indicator Feedwater BFP discharge Indicator Condensate Cond. pump discharge Indicator Fuel gas Boiler burners Indicator Fuel gas Igniter Indicator Fuel gas Boiler burne s Indicator Flue gas Indicator Lube Oil Turbine generator Indicator Vacuum Condenser Indicator Temperature Steam Turbine throttle Steam Boiler superheater outlet Steam Turbine extraction steam Air-flue gas Boiler draft system Lube Oil Turbine generator Flow Steam Boiler main steam Recorder & totalizer Air Boiler FD f n discharge Recorder C02 Recorder Feedwater Boiler main supply Recorder Feedwater Boiler Attemperator Recorder Fuel gas Boiler burner supply Recorder & totalizer Fuel oil Boiler burner supply Recorder & totalizer Notes: (1) Including FD fan discharge, air inlet & outlet to air preheater, windbox, furnace draft, inlet & outlet to economizer, gas inlet and outlet to air preheater, overfire or primary air pressure, and ID fan discharge. (2) Multi-point electronic type to track air and gas temperatures through the unit. (3) May be used for combustion controls instead of steam flow-air flow. (4) Usually in condensate system, boiler feed system and process returns.5-2
  • TM 5-311-6 Table 5-1. List of Typical Instruments and Devices to be Provided for Boiler Turbine Mechanical Panel. (Continued)Measurement Primary Element Instrument or or Device Fluid Location Device on PanelLevel Feedwater Boiler drum Recorder Condensate Deaerator, Condenser Hotwell Recorder Coal Bunker Indicator or pilot lightsConductivity Condensate Cells as required ( 4 ) RecorderManual- -- Combustion control system, Each stationautomatic condensate and feedwaterstations control systems, steam attemperator, and as re- quiredMotor control -- Starters for draft fans, Each switchswitches BF pumps, condensate pumps, vacuum pumps, fuel pumps, lube oil pumps, turning gear, turbine governor and like itemsAmmeters -- Major motors (high volt- Indicator age) : draft fans, BF pumpsAlarms -- Points as selected for Annunciator safe operation section for boiler turbine panelBurner -- Boiler burner system Insert on boiler-Management turbine panelIndicating - As required to start up Each light and monitor boiler and turbine.Notes: See first page of Table.Courtesy of Pope, 5-3
  • TM 5-811-6 Table 5-2. List of Typical Instruments and Devices to be Provided for Common Services Mechanical Panel Measurement Primary Element Instrument or or Device Fluid Location Device on Panel Pressure Steam Main steam header (l) Recorder Steam Extraction steam header(l) Indicator Fuel gas Supply to plant Indicator Fuel oil supply Indicator Fuel oil Burner pump discharge Indicator Circ. water Discharge header Indicator Water Service water Indicator Water Closed cooling water Indicator Water Fire system Indicator . Air Instrument air Indicator Air Service air Indicator Air Atmosphere Barometer Temperature Steam Extraction steam header(l) Fuel Oil supply Various As required Viscosity Fuel oil Pump and heater sets Flow Steam Recorder Steam Extraction to process Recorder & totalizer Fuel gas Supply to plant Recorder & totalizer Level Fuel oil Tank(s) Indicator Condensate Tank(s) Indicator Manual- -- Pressure reducing station, Each station automatic misc. air operated devices stations Motor -- CW pumps, cooling tower Each switch control fans, air compressors, switches condensate transfer pumps, service water pumps, fuel transfer pumps, and like i t ems : For header systems only (2) Multi-point electronic type5-4
  • TM 5-811-6 Table 6-2, List of Typical Instruments and Devices to be provided for Common Services Mechanical Panel. (Continued) Measurement Primary Element Instrument or or Device Fluid Location Device on Panel Ammeter - Major (high voltage) Indicator motors; CW pumps, cooling tower fans Alarms -- Points as selected Annunciator for safe operation section for common panel Indicating -- As required to start-up Each light . and monitor principal common systems Courtesy of Pope, Evans and Robbins (Non-Copyrighted) nomic or engineering accountability purposes, re- Mechanical-hydraulic and electro-hydraulic systems corders will be provided. will be utilized in connection with turbine generator d. Ventilation. All panels which house heat pro- speed governing control systems. Pneumatic con- ducing instruments will be ventilated or air condi- trols will be used for power plant units of 30 MW or tioned to prevent overheating of the instruments. less. Applications include: combustion control, For . panel~in the central control room, this will be feedwater regulation, desuperheating and pressure‘ accomplished by having a filtered air intake and me- reducing station control, heater drain control, and chanical exhaust arrangement to circulate cool air boiler feed recirculation control. Pneumatic systems from the air conditioned control room through each are economical, reliable, and provide smooth, modu- enclosed panel wherever practicable. Local panels, lating type of operation. For plants where the ar- as a rule, have only gages and other devices which rangement is dispersed and precision is required, emit little heat and do not require special ventila- electronic controls and instruments will be provided tion. in lieu of the pneumatic type because of the slug- e. Illumination. In a central control room, the gishness of pneumatic response where long dis- best illumination is a “light ceiling” with diffuser tances are involved. Electronic digital controls have type suspended panels to give a shadowless, even recently become economically competitive with level of lighting throughout the control room. Levels analog pneumatic and electronic controls and offer of illumination at bench tops of 75-foot candles, the advantage of’ ‘soft-wired” control logic and pro- plus or minus 10-foot candles, will be provided. grammable versatility. With electronic controls it is However, caution must be used when designing required to use pneumatically operated valves with lighting for control rooms utilizing electronic digital transducers to convert the electronic signals to controls with cathode ray tube (CRT) display as ex- pneumatic at the pneumatic valve operator. cessive illumination tends to wash out displays. In b. Combustion controls. Combustion controls for areas with electronic digital controls with CRT dis- steam generators will be based on the conventional plays, the level of general illumination will be main- indirect method of maintaining steam pressure. tained at 15- to 25-foot candles. Local panel illumi- Systems will be of the fully metering type, designed nation will be accomplished by means of a canopy to hold steam pressure within plus or minus 1 per- built into the top of the panel. Local switch control cent of the controller setting with load changes of 5 will be provided at each canopy light. percent per minute; under the same rate of load change, excess air will be maintained at plus or 5-3. Automatic control systems minus 2 percent of the control setting. (Note: With a. Types. Control systems and instruments may stoker fired boilers having limited heat inputs from be pneumatic, ac or dc electronic, electronic digital, suspension heat release, the tolerances on steam combination pneumatic and electronic, or hydraulic. pressure will be greater than 1 percent.) 5-5
  • TM 5-811-6 Table 5-3. List of Typical Instruments and Devices to be Provided for Electrical (Generator and Switchgear) Panel Measurement Instrument or or Device Device on Panel Notes For Each Generator Generator gross output Wattmeter Power Factor P.F. Meter Generator ac current AC ammeter -- Generator ac volts AC voltmeter -- Generator dc current DC ammeter -- Generator dc volts DC voltmeter -- Generator ac current AC ammeter For phase measurement selection (for individual phases) control switch -- Generator ac volts AC voltmeter For phase measurement selection (for individual phases) control switch -- Generator Synchronizing synchronizing control switch Generator Separate panel I n c l . synch. lamps and meters synchronizing section for incoming and running indication Oil circuit breaker OCB control If step-up transformation trip switch included Generator field Field breaker -- breaker control switch Voltage regulator Voltage reg. transfer voltmeter Voltage regulator Manual voltage regulator -- Voltage regulator Auto. voltage reg. adjuster -- Voltage regulator Voltage reg. transfer switch -- Unit governor Governor control switch, raise-lower -- Unit trip Trip pushbutton -- Unit reset Reset pushbutton -- Unit speed Speed indicator -- Unit temperatures Electronic For turbine and generator recorder temperatures Generator alarms Annunciator With test and reset pushbuttons Miscellaneous Indicating For switches and as required lights Supervisory Recorders Vibration, e c c e n t r i c i t y5-6
  • TM 5-811-6Table 5-3. List of Typical Instruments and Devices to be Provided for Electrical (Generator and Switchgear) Panel. (Continued) Measurement Instrument or or Device Device on Panel Notes For Switchgear 2.4 or 4.16 kV unit Breaker control If higher plant auxiliary switchgear switch voltage required 2.4 or 4.16 kV Breaker control If required common switchgear switch 2.4 or 4.16 kV Breaker control For plant auxiliaries feeders switches and/or for outside distri- bution circuits as re- quired. 480 V unit switchgear Breaker control switch 480 V common Breaker control switchgear switch 480 V feeders Breaker control For plant auxiliaries as switches required Swithgear ac current AC ammeters One for each switchgear with switch Switchgear ac volts AC voltmeters One for each switchgear with switch Switchgear alarms Annunciator With test and reset push- buttons Miscellaneous Indicating For switches and as re- lights quired Intraplant Telephone handset communication Notes: (1) If a high voltage switchyard is required a separate panel may be required. (2) For relays see Chapter 4, Section V; generator and auxiliary power relays may be mounted on the back of the generator walk-in bench- board or on a separate panel. Courtesy of Pope, Evans and Robbins (Non-Copyrighted) 5-7
  • TM 5-811-6 Table 5-4. List of Typical Instruments and Devices to be Provided for Diesel Mechanical Panel Measurement Primary Element Instrument or or Device Fluid Location Device on Panel Pressure Fuel gas Supply to engine Indicator Fuel oil Supply to engine Indicator Lube oil Supply to engine Indicator Lube oil supply to turbocharger Indicator Comb. air Turbocharger discharge Indicator Comb. air Filter downstream Indicator Cooling water Pump discharge Indicator Starting air Air receiver Indicator Temperature Exhaust Each cylinder and Indicator(l) combined exhaust Cooling water Supply to engine Indicator Cooling water Return from engine Indicator Level Jacket water Surge tank Indicator Lube Oil Sump tank Indicator Fuel Bulk storage tank Indicator Fuel Day Tank Indicator Motor - Jacket water pumps, Each switch control radiator (or cooling switches tower) fans, fuel oil (or pushbuttons) pumps, centrifuges, and like auxiliaries Alarms -- Low lube oil pressure, Annunciator low jacket water pressure, high lube oil temperature, high jacket water temperature, high and low day tank levels Notes: (1) With selector switch. Courtesy of Pope, Evans and Robbins (Non-Copyrighted)5-8
  • TM 5-811-6 c. Feedwater regulation. A three element feed- the deaerator at low loads for protection against water regulator system will be provided for steam boiler feed pump overheating. A flow signal from power plant service. Such a system balances feed- the suction of each pump will be used to sense the water input to steam output subject to correction preset minimum safe pump flow. This low flow sig- for drum level deviations caused by operating pres- nal will open an automatic recirculation valve lo- sure variations (drum swell). cated in the piping run from the pump discharge to d. Attemperator control system. Each power the deaerator. This recirculation line poses mini- plant steam generator will have superheat (attem- mum flow through a breakdown orifice for pressure perator) controls to maintain superheat within the reduction to the deaerator. The breakdown orifice limits required for protection of the turbine metal will be located as closely as possible to the deaerator parts against thermal stress and for preventing because flashing occurs downstream. When pump excessive reduction in part load turbine efficiency. suction flow increases to a preselected amount in ex- Injection of desuperheating water (which must be cess of pump minimum flow, the recirculation valve high purity water, such as condensate) will be done closes. The operator will be able to open the recir- between stages of the boiler superheater to reduce culation valve manually with a selector switch on chances of water carryover to the turbine. An at- the control panel. Designs will be such as to pre- temperator system having a controller with a fast clude accidental closing of the valve manually. Such response, derivative feature will be provided. This an operator error could cause flow to drop below the type of controller anticipates the magnitude of sys- safe level quickly, destroying high pressure pumps. tem deviations from the control set point in accord- g. Other control systems. Desuperheating, pres- ance with the rate of change of superheat temperat- sure reducing, fuel oil heating, and other miscellane- ure. Automatic positive shutoff valve(s) will be pro- ous power plant control systems will be provided as vided in the desuperheating water supply line up- appropriate. Direct acting valves will not be used. stream of the desuperheater control valve to prevent Control valves will be equipped with a matching dribbling of water to the desuperheater when the valve operator for positive opening and closing ac- controls are not calling for spray water. tion. Deaerator and hotwell level control systems e. Closed heater drain controls. Although it is are described in Chapter 3, Section VII. thermodynamically preferable to pump the drains from each feedwater heater forward into the conden- 5-4. Monitoring instruments sate or feedwater stream exiting from the heater, a. Types. the expense and general unreliability of the low (1) Control system components will include NPSH pumps required for this type of drain service sensing devices for primary fluids plus transmitters, will normally preclude such a design. Accordingly, transducers, relays, controllers, manual-automatic the drains from each heater will normally be cas- stations, and various special devices. Table 5-5 lists caded to the next lower pressure heater through a sensing elements for controls and instruments. In- level control valve. The valve will be located as struments generally fall into two classifications—di- closely as possible to the lower pressure heater due rect reading and remote reading. to the flashing which occurs because of the pressure (2) Direct reading instruments (e.g., thermome- reduction at the outlet of the level control valve. ters, pressure gages, and manometers) will be Each heater will be provided with two level control mounted on local panels, or directly on the process valves. The secondary valve only functions on piping or equipment if at an accessible location. startup, on malfunction of the normal valve, or Locally mounted thermometers will be of the con- sometimes during light loads when pressure differ- ventional mercury type or of the more easily read ential between heaters being cascaded becomes very (but less accurate) dial type. Type selected will de- small. The secondary valve frequently discharges pend on accuracy required. Pressure gages for steam directly to the condenser. Such a complexity of con- or water service will be of the Bourdon tube type. trols for heater drains is necessary to assist in pre- (3) Remote reading instruments (recorders, in- venting problems and turbine damage caused by tegrators, indicators and electrical meters) will be turbine water induction. Water induction occurs mounted on panels in the central control room. when feedwater header tubes or level control valves These instruments will have pneumatic or electronic fail, causing water to backup into the turbine transmission circuits. Sometimes the same trans- through the extraction steam piping. Refer to mitters utilized for control system service can be Chapter 3, Section VII. utilized for the pertinent remote reading instru- f. Boiler feed recirculation controls. An automatic ment, although for vital services, such as drum recirculation system will be installed for each pump level, an independent level transmitter will be used to bypass a minimum amount of feedwater back to for the remote level indicator. 5-9.
  • Table 5-5. Sensing Elements for Controls and Instruments. (Continued) Common Applications Element Type Control InstrumentMotion Centrifugal - . Speed governs Tachometer Vibrating reed - - Speed governs Tachometer Relative motion - - - - Stroboscope Photo-electric cell - - Limit control CounterChemical Flue gas analysis -- Combustion Orsat control Water analysis -- Water -- treatment Fuel analysis -- --Physical Specific gravity -- -- Hydrometer for liquids Weight -- -- Scales for solids Humidity -- Hygrometer Smoke density -- -- Ringelman chart Gas density Combustion C 02 meter Heat Combination of Combustion Btu meter water flow and temperature differentialElectric Photo-conductivity Flame safe- Photo-electric celland guard Smoke densityelectronic Electric Probes Alarm pH of water conductivity Oil in condensateSource: NAVFAC DM3
  • Table 5-5. Sensing Elements for Controls and Instruments. (Continued) Common Applications Element Type Control InstrumentPressure Mechanical Bourdon tube Pressure, draft Pressure gage Bellows or and vacuum Low pressure, draft and diaphragm regulators vacuum gages Manometers Barometer Variable electric Pressure transducer Process pressure Potentiom. 100 to 50,000 psi resistance due to regulator strain Variable electric Thermocouple Vacuum High vacuum 1-7000 resistance due to regulator microns Hg vacuum Variable Vacuum tube Vacuum High-vacuum down to electronic regulator 0.1 micron Hg resistance due to vacuumLevel Visual -- -- Gage stick Transparent tube Float Buoyant float Mechanical Tape connected to float level regulator Displacement Pneumatic float Torque regulator Differential Manometer Level regulator Remote level gage pressure Hydrostatic Diaphragm in tank Level regulator Tank levels with bottom viscous fluids
  • Table 5-5. Sensing Elements for Controls and Instruments. (Continued) Common Applications Element Type Control InstrumentTemperature Solid expansion Bimetal On-off Dial therm. - 100 to 1000 F thermostats Fluid expansion Mercury or alcohol -- Glass therm.- 38 to 750 F Mercury in coil Temperature Dial therm. - 38 to 1000 F Organic liquid regulators 125 to 500 F Organic vapor - 40 to 600 F liquid Gas - 400 to 1000 F Thermocouple Copper-constantan Temperature Low voltage - 300 to 600 F Iron-constantan regulators O to 1400 F Chromel-alumel 600 to 2100 F Plat.-plat. rhodium 1300 to 3000 F Elec. resistance Copper Temperature Potentiom. - 40 to 250 F of metals Nickel regulators - 300 to 600 F Platinum - 300 to 1800 F Optical Comparative radiant -- Potentiom. - 800 to 5200 F Pyrometer energy Radiation Radiant energy on Flame safeguard Potentiom. - 200 to 7000 F pyrometer thermocouples Surface temperature regulation Fusion - - -- Pyrom.cones -1600 to 3600 F Crayons - 100 to 800 F
  • TM 5-811-6 (4) Panel mounted receiver gages for pressure, audibly and visually when trouble occurs so that temperature, level and draft will be of the miniature, proper steps can be taken to correct the problem. vertical indicating type which can be arranged in b. General. The alarm system will be both audible convenient lineups lineups on the panel and are easy and visual. The sounding of the alarm will alert theto read. operators that a problem exists and the visual light (5) Recorders will be of the miniature type, ex- in the pertinent annunciator window will identify cept for multi-point electronic dot printing recorders the problem. Annunciator systems shall provide for which will be full size. the visual display to be distinguishable between b. Selection. The monitoring instruments for any new alarms and previous alarms already acknowl- control system will be selected to provide the neces- edged by the operator pushing a button provided for sary information required for the control room this purpose. New alarms will be signified by a flash-operator to be informed at all times on how the con- ing light, whereas acknowledged alarms will be sig- trolled system is functioning, on vital process nified by a steady light. Alarm windows will be ar-trends, and on other essential information so that ranged and grouped on vertical, upper panel sec-corrective action can be taken as required. tions with corresponding control stations and operating switches within easy reach of the operator5-5. Alarm and annunciator systems at all times. Critical or potentially dangerous alarms a. Purpose. The annunciator system supplements will be a different color from standard alarms forthe operator’s physical senses and notifies him both rapid operator identification and response. Section Il. HEATlNG; VENTILATING AND AlR CONDITIONING SYSTEMS5-6. introduction ducted exhaust systems to prevent heat from beingThis section sets forth general criteria for design of carried into other areas. All exhaust and supplyspace conditioning systems for a power plant. openings will be provided with power operated dampers, bird screens, and means for preventing en- 5-7. Operations areas trance of rain, sleet and snow. a. Enclosed general operating areas. (3) Heating. As much heating as practicable (1) Ventilation supply. Provide mechanical ven- will be supplied via the central ventilation supply tilation for fresh air supply to, as well as exhaust system, which will be designed so that maximum de- from, the main operating areas, A filtered outside sign air flow can be reduced to a minimum required air supply, with heating coils and recirculation op- for winter operation. Heat supplied by the ventila-tion for winter use, will be provided. Supply fans tion system will be supplemented as required bywill be selected so that indoor temperature does not unit heaters and radiation. Heating system designrise more than 15oF. above the ambient outdoor air for ventilation and other space heating equipmentdesign temperature, and to maintain a slight posi- will be selected to maintain a minimum plant indoortive inside pressure with all exhaust fans operating temperature of 55OF. and an office, control roomat maximum speed. Ventilation system design will and laboratory area temperature of 68OF.take into account any indoor air intakes for boiler b. Control room.forced draft fans, which can be designed to draw (1) The central control room is the operatingwarm air from near the roof of the plant. Supply air center of a power plant and will be air conditionedwill be directed through a duct system to the lowest (i.e., temperature control, humidity control and airlevels of the plant with particular emphasis on fur- filtration) for the purpose of human comfort and tonishing large air quantities to “hot spots. ” The protect equipment such as relays, meters and com-turbine room will receive a substantial quantity of puters. Unattended control rooms may not requirefresh air, supplemented by air from lower levels ris- comfort conditions but have temperature limits asing through operating floor gratings. For hot, dry required by the equipment housed in the room. Con-climates, evaporative cooling of ventilation air sup- trol system component manufacturers will be con-ply will be provided. sulted to determine the operating environment re- (2) Ventilation exhaust. Exhaust fans with at quired for equipment reliability.least two speeds are switched so that individual fan (2) Intermediate season cooling using 100 per-and fan speed can be selected according to air quan- cent outside air for an economizer cycle or enthalpytity desired will be provided. Battery rooms will control will be life cycle cost analyzed.have separate exhaust systems designed in accord- 5-8. Service areasance with TM 5-811-21AFM 88-9/2. It may beeconomical to remove heat from hot spots with local a. Toilets, locker rooms and lunch rooms.5-14
  • TM 5-811-6 (1) Toilets will be exhausted to maintain a nega- of other systems to prevent recirculation of food tive pressure relative to adjacent areas. All exhaust odors to other spaces. outlets from a toilet will be a minimum of 15 feet b. Shops and maintenance rooms. All shops and from any supply inlet to prevent short circuiting of maintenance rooms will be ventilated according to air. Toilet exhaust will be combined with a locker applicable codes. Welding and painting areas will be room exhaust but not with any other exhaust. exhausted. Heating will be provided by means of unit heaters sized to maintain a maximum of 68 “F. (2) Locker rooms will be exhausted according to on the coldest winter design day. the applicable codes and supplied by a heated air c. Offices and laboratories. All offices and labora- supply. tories will be air conditioned for human comfort in (3) Lunch rooms will be furnished with recircu- accordance with TM 5-810-l/AFM 88-8/1. Ex- lation heating systems to meet applicable codes; ex- haust will be provided where required for laboratory haust will be installed. System will be independent hoods or other special purposes. Section lll. POWER AND SERViCE PlPlNG SYSTEMS 5-9. introduction d. Include provisions for drainage and venting of a. General. Power plant piping systems, designed all pipe lines. to transfer a variety of fluids (steam, water, com- e. Design pipe supports, restraints and anchors, pressed air, fuel oil, lube oil, natural gas) at pres- using accepted procedures for thermal expansion sures ranging from full vacuum to thousands of psi, stress analysis. The stress analysis will consider si- will be engineered for structural integrity and econo- multaneous application of seismic loads, where ap- my of fluid system construction and operation. plicable. Computer analysis will be used for major b. Design considerations. Piping systems will be three plane piping systems with multiple anchors. designed to conform to the standards listed in Table 5-6. ASME Boiler Pressure Vessel Code Section I 5-11. Specific system design considera- governs the design of boiler piping, usually up to the tions second isolation valve. ANSI B31.1, Code for Pres- sure Power Piping governs the pressure boundary a. Steam piping. In all steam systems, provisions requirements of most other plant piping (excluding will be made for draining of condensate before start- plumbing and drainage piping). Each of these codes up, during operation and after shutdown. Steam provides a detailed description of its scope and lim- traps will be connected to low points of the pipe- itations. lines. Small bore bypass piping will be provided around block valves on large, high pressure lines to 5-10. Piping design fundamentals permit warming before startup. Design of piping system will conform to the follow- b. Circulating water piping. Reinforced plastic ing procedure: piping will be used for salt or brackish water service1 whenever practicable.I a. Select pipe sizes, materials and wall thickness (pipe schedule). Design for the maximum pressure c. Fuel oil piping. Fuel oil piping will be designed and temperature the piping will experience during with relief valves between all block valves to protect either operation or upset conditions. Follow appro- against pipe rupture due to thermal expansion of the priate sections of ASME Section I and ANSI B31.1. oil. Fuel oil piping will be designed in accordance Other requirements for welding qualification and with National Fire Protection Association (NFPA) pressure vessel design are set forth in ASME Sec- standards and ANSI B31. Piping subject to vibra- tions VIII and IX. Specify hydrostatic pressure tion (such as engine service) will be socket or butt testing requirements in accordance with the codes. welded, although flared tubing may be used for Select flow velocities for overall economy. small lines under 1/2 inch. d. Insulation. Insulate all lines containing fluids b. Select piping components and end connections for equipment. above 120oF. so that insulation surface tempera- c. Route piping. Make runs as simple and direct tures remain below 1200F. at 80oF. still air ambient. Provide anti-sweat insulation for all lines which op- as possible. Allow for maintenance space and access to equipment. Do not allow piping to encroach on erate below ambient temperatures. Protect all insu- aisles and walkways. Inspect for interferences with lation against weather (or wash down water if in- structures, ductwork, equipment and electric serv- doors) and mechanical abuse. ices. 5-15I
  • 24-30
  • TM 5-811-6 Table 5-6. Piping Codes and Standards for Power Plants. (Continued) Sponsor Identification Title Coverage ANSI B36 series Iron and steel Materials and dimensions. pipe B16 series Pipe, flanges Materials, dimensions, and G37.1 and fittings stresses and temperature- pressure ratings. B18 series Bolts and nuts Bolted connections. ASTM -- Testing materials Physical properties of materials specified in above ASME and ANSI standards. Major -- - - Allowable reactions and equipment movements on nozzles from manufacturers piping. (turbines, pumps, heat exhangers, etc.) Courtesy of Pope, Evans and Robbins (Non-Copyrighted) Section IV. THERMAL INSULATION AND FREEZE PROTECTION5-12. Introduction 5-14. lnsulation materialsApplications. Thermal insulations are used for the a. Bulk material. Refer to Table 5-7 for nomencla-following purposes: ture and characteristics of conventional thermal in- a. Limit useful heat losses. sulations. b. Personnel burn protection. b. Restrictions on asbestos. Asbestos insulation, c. Limit heat gains where cold is desired. or insulations containing loose, fibrous, or free as- d. Prevent icing and condensation. bestos are not to be used. e. Freeze protection. c. Maximum temperatures. Each type of insula- tion is suitable for use at a specified maximum tem-5-13. Insulation design perature. Design will be such that those maximumsThe principal elements of insulation system design will not be approached closely in ordinary applica-and specification areas follows: tions. All high temperature insulations are more ex- a. Selection of surfaces. Define and list the vari- pensive and more fragile than lower temperatureous surfaces, piping, vessels, ductwork, and machin- products and, in general, the least expensive materi-ery for which insulation is needed including lengths, al which is suitable for the temperature exposureareas and temperatures. will be selected. Where substantial total insulation b. Insulation systems. For each class or type of thicknesses of 6 inches or more are required, eco-surface select an appropriate insulation system: nomics may be realized by using two layers of differ-bulk insulation material and miscellaneous materi- ent materials using high temperature material closeals,coverings, and like items. to the hot surface with cheaper low temperature ma- c. Economical thickness. Based on the above terial on the cold side.data, select the economical or necessary thickness of d. Prefabricated insulation. A major part of totalinsulation for each class or type of surface. insulation cost is field labor for cutting, fitting and 5-17
  • 0.64 0.68 -- -- -- -- 200 6-18 0.28 0.29 0.30 -- -- -- -- --600 6-10 -- -- 0.28 0.35 0.43 -- -- --1600 16-24 -- -- 0.34 0.39 0.44 0.54 0.64 -- 175 1.6 0.26 0.28 0.30 -- -- -- -- -- 150 5 0.23 0.24 0.25 -- -- -- -- --
  • Corrugated and laminatedasbestos paper: 4 ply per in. 300 11-13 -- 0.54 0.57 0.62 -- -- - 6 ply per in. 300 15-17 — 0.49 0.51 0.59 -- -- -- 8 ply per in. 300 18-20 -- 0.47 0.49 0.57 -- -- --Calcium silicate 1200 11 -- -- 0.36 0.40 0.55 -- --Cellular glass 800 9 0.37 0.39 0.41 0.48 -- -- --Cork (without added 200 7-10 0.27 0.28 0.29 0.30 -- -- --binder)Diatomaceous silica 1500 22 . - -- — -- -. 0.64 0.66 0.71 1900 25 -- -- -- -- -- 0.70 0.75 0.8085% magnesia 600 11-14 -- -- 0.39 0.42 0.51 -- --Mineral wool (rock,slag or glass): Low temp. (asphalt 200 15 0.28 0.30 0.33 0.39 -- -- -- -- or resin bonded) . Low temp. (fine 450 3 0.22 0.23 0.24 0.27 0.31 — -- -- fiber resin bonded) High temp. blanket- 1200 type (metal reinforced)
  • 24-30
  • TM 5-811-6 installation. For large areas or long piping runs, sub- ing outside air into power plants and HVAC sys- stantial savings may be realized by factory forming, tems. cutting or covering. Valves and pipe fittings, espe- b. Criteria. In most cases, cold surface insulations cially large ones, may be economically insulated will be selected to prevent icing or condensation. Ex- with factory made prefabricated shapes. Equipment tra insulation thickness is not normally economical requiring periodic servicing will be equipped with re- for heat absorption control. movable, reusable insulation. e. Miscellaneous materials. Complete insulation 5-18. Economic thickness systems include accessory materials such as fasten- a. General. Economic thickness of an insulation ers, adhesives, reinforcing wire meshes and screens, material (ETI) is a calculated parameter in which bandings and binder wires, coverings or laggings, the owning costs of greater or lesser thicknesses are .. and finishes. All insulations will be sealed or closed compared with the relative values of heat energy at joints and should be arranged to accommodate which might be saved by such various thicknesses. differential expansions between piping or metal The method is applicable only to systems which are structures and insulations. installed to save useful heat (or refrigeration) and f. Cold surface materials. Cold surface insulation does not apply to safety insulation or anti-sweat materials will be selected primarily for high resis- (condensation) materials. tance to moisture penetration and damage, and for b. Economic criteria. The general principle of ETI avoidance of corrosion where wet insulation materi- calculations is that the most economical thickness als may contact metal surfaces. Foamed plastics or of a group or set of thicknesses is that one for which rubber and cellular (or foamed) glass materials will the annual sum of owning costs and heat loss costs be used wherever practicable. is a minimum. Generally, thicker insulations will represent higher owning costs and lower heat loss 5-15. Control of useful heat losses costs. The range of thicknesses selected for calcula- a. General. Control of losses of useful heat is the tion will indicate at least one uneconomical thick- most important function of insulations. Substantial ness on each side of the indicated ETI. Refer to Fig investments for thermal insulation warrants careful ure 5-1 for a generalized plot of an ETI solution. selection and design. c. Required data. The calculations of ETI for a b. Durability and deterioration. Most convention- particular insulation application involves routine al insulating materials are relatively soft and fragile calculations of costs for a group of different thick- and are subject to progressive deterioration and loss nesses. While calculations are readily performed by of effectiveness with the passage of time. Insulation computers, the required input data are relatively assemblies which must be removed for maintenance complex and will include energy or fuel prices with or which are subject to frequent contact with tools, allowance for future changes, relative values of par- operating equipment and personnel, or are subject ticular heat sources or losses, depreciation and to shock or vibration, will be designed for maximum money cost rates, costs of complete installed insula- resistance to these forces. tion systems, conductivities, temperatures, air velocities and operating hours. Standard programs 5-16. Safety insulation are available for routine calculations but must be, a. General Insulation for personnel protection or used with care. The most uncertain data will be the safety purposes will be used to cover dangerously installed costs of alternative insulation systems and hot surfaces to avoid accidental contact, where heat thicknesses. Assumptions and estimates of such loss is not itself an important criteria. costs will be as accurate as possible. Refer to the b. General safety criteria. Safety or burn protec- publications and program systems of the Thermal tion insulations will be selected to insure that out- Insulation Manufacturers Association (TIMA) and side insulation surfaces do not exceed a reasonably of leading insulation manufacturers. safe maximum, such as 140 “F. c. Other criteria Close fitting or sealing of safety 5-19. Freeze protection insulation is not required. Metal jacketing will be a. Application. Freeze protection systems are avoided due to its high conductivity in contact with combinations of insulation and heat source materi- the human body. als arranged to supply heat to exposed piping or equipment to prevent freezing in cold weather. 5-17. Cold surface insulation b. Insulaztion materials. Conventional insulation a. Applications. Insulations for cold surfaces will materials will be used and selected for general heat be applied to refrigeration equipment, piping and loss control purposes in addition to freeze protec- ductwork, cold water piping, and to air ducts bring- tion. Insulation will be such as not to be damaged by 5-21
  • TM 5-811-6 Courtesy of Pope, Evans and Robbins (Non-Copyrighted) Figure 5-1. Economical thickness for heat insulation (typical curves).the heat source or by extended exposure to weather erally be used to supply the correct heat flow to theand moisture. protected surface. Steam and ho water tracing may c. Design criteria. In general, the insulation for a also be used with provisions to avoid loss of steamfreeze protection system will be selected for maxi- or water. In either case, the required heat supplymum overall coldest ambient temperatures. Allow- will be sufficient to meet the heat loss of the insula-ance for wind conditions will be made. tion under the combination of design ambient and d. Heat sources. Electrical heating tape will gen- pipe line surface temperature. Section V. CORROSION PROTECTION5-20. General remarks cycle is generally accomplished by more convention-The need for corrosion protection will be investigat- al methods such as:ed. Cycle fluids will be analyzed to determine treat- U. Selection of corrosion resistant materials.ment or if addition of corrosion inhibitors is re- b. Protective coatings.quired. Corrosion protection of items external to the c. Cathodic protection. Section Vl. FIRE PROTECTION5-21. Introduction lar type of fire which can occur in the station. ThisFire protection will be provided in order to safe- manual discusses various fire protection systemsguard the equipment and personnel. Various sys- and their general application in power plants. Refer-tems will be installed as required to suit the particu- ence will be made to TM 5-812-1 for specific re-5-22
  • TM 5-811-6quirements for military installations. Further de- elements have been opened by the heat from a fire.tails may be found in the National Fire Protection This system will be utilized for the turbine and gen- Association (NFPA) Codes and Standards. erator bearings and for the above water spray de- luge sprinkler system areas where more localized 5-22. Design considerations control is desired. a. Areas and equipment to be protected. The fol- (3) Wet pipe sprinkler systems. This wet pipe lowing are some of the major areas which will be in- system utilizes a water filled piping system connect- vestigated to determine the need for installing fire ed to a water supply and is equipped with sprinklers protection facilities. having fixed temperature elements which each open (1) Main and auxiliary transformers. individually when exposed to a high temperature (2) Turbine lubricating oil system including the due to a fire. The areas where wet pipe sprinkler sys- oil reservoir, oil, cooler, storage tanks, pumps and tems will be used are heated shops, garages, ware- the turbine and generator bearings. houses, laboratories, offices, record rooms, locker (3) Generator hydrogen cooling system includ- rooms, lunch rooms and toilets. ing control panels, seal oil unit, hydrogen bottles (4) Foam extinguishing systems. Foam fire ex- and the purification unit. tinguishing systems utilize a foam producing solu- (4) Coal storage bunkers, fuel oil storage tanks tion which is distributed by pipes equipped with and the burner front of the steam generator. spray nozzles or a fuel tank foam entry chamber for (5) Emergency diesel generator and its oil stor- discharging the foam and spreading it over the area age tank. to be protected. It is principally used to form a co- (6) Office and records rooms. herent floating blanket over flammable and com- (7) Control room. bustible liquids which extinguish (or prevent) a fire (8) Relay, computer, switchgear and battery by excluding air and cooling the fuel. The foam isrooms. usually generated by mixing proportionate amounts (9) Shops, warehouses, garages and laborato- of 3% double strength, low expansion standardries. foam concentrate using either a suitably arranged (10) Personnel locker rooms, lunch rooms and induction device with (or without) a foam storage-toilets. proportioning tank to mix the foam concentrate b. Types of systems. The following is a brief de- with a water stream from a fire water header. A spe-scription of the various types of systems and their cially designed hand play pipe, tank foam chambergeneral application. or open sprinklers aspirate the air to form the foam (1) Water spray and deluge system. This type of to blanket the area to be protected. The deluge wa-system consists of open type sprinkler heads at- ter entry valve to the system may be manually ortached to a network of dry (not water filled) piping automatically opened. Foam systems will be in-which is automatically controlled by a fully super- stalled in power plants to protect fuel oil areas,vised fire detection system which also serves as a lubricating oil systems, and hydrogen seal oil sys-fire alarm system. When a fire is detected, an auto- tems.matic deluge valve is tripped open, admitting water (5) Carbon dioxide extinguishing systems. Thisto the system to discharge through all of the sprink- type of system usually consists of a truck filled lowler heads. The system may be subdivided into sepa- pressure refrigerated liquid carbon dioxide storagerately controlled headers, depending on the area to tank with temperature sensing controls to permitbe covered and the number of sprinkler heads re- the automatic injection of permanently pipe carbonquired. The usual pressure required at the sprinkler dioxide into areas to be protected. The systemheads is about 175 psi and the piping should be usually includes warning alarms to alert personnelproperly sized accordingly. A water spray deluge whenever carbon dioxide is being injected into an ac-sprinkler system will be provided where required in tuated area. Carbon dioxide extinguishing systemsopen areas and areas requiring the protection of the of this total flooding type will be utilized to extin-piping from freezing, such as the steam generator guish coal bunker fires and for electrical hazardburner fronts; the generator hydrogen system; the areas such as in battery rooms, electrical relaymain and auxiliary transformers; and unheated rooms, switchgear rooms, computer rooms and with-shops, garages, warehouses and laboratories. in electrical cabinets. (2) Water spray pre-action and deluge system. (6) Halogenated fire extinguishing systems.This type of system is similar to the above water This type of system utilizes specially designed re- spray deluge system, except that it contains closed movable and rechargeable storage containers con-type sprinkler heads which only discharges water taining liquid HaIon at ambient temperature whichthrough those sprinklers whose fixed temperature is superpressurized with dry nitrogen up to 600 psig 5-23
  • TM 5-811-6pressure. These manifolded containers are located actuated; however, some special conditions may re-as closely as possible to the hazards they protect quire manual actuation on an alarm indication. Aand include connecting piping and discharge noz- manual actuation will be included to provide forzles. There are two types of systems. The total flood- emergencies arising from the malfunction of an au-ing system is arranged to discharge into, and fill to tomatic system. The primary element of any firethe proper concentration, an enclosed space or an en- protection system is the fire detection sensing de-closure about the hazard. The local application sys- vice which is actuated by heat detectors which de-tem is arranged to discharge directly onto the burn- tect abnormally high temperature or rate-of-tem-ing material. Either system may be arranged to pro- perature rise, or smoke detectors which are sensitivetect one or more hazards or groups of hazards by so to the visible or invisible particles of combustion.arranging the piping and valves and may be manual- The ionization type of smoke detector belongs inly or automatically actuated. Halon is a colorless this category.and odorless gas with a density of approximatelyfive times that of air, and these systems must in- 5-23. Support facilitiesclude warning alarms to alert personnel whenever To support the fire protection water systems, an as-the gas is being ejected. However, personnel maybe sured supply of water at an appropriate pressure isexposed to Halon vapors in low concentrations for necessary. This water supply will be provided frombrief periods without serious risk. The principal ap- an underground fire water hydrant system main ifplication of Halon extinguishing systems is where one is available in the area and/or by means of an ele-an electrically nonconductive medium is essential or vated head storage tank or by fire pumps which takedesired or where the cleanup of other media presents their suction from a low level storage tank. Fora problem, such as in control rooms, computer cases where the water supply pressure is inadequaterooms, chemical laboratories and within electrical to fill the tank, fill pumps will be provided. Firepanels. pumps will be electric motor driven, except that at c. Automatic fire detectors. All fire protection least one should be of the engine driven or of thesystems will normally be automatically alarmed and dual drive type.5-24
  • TM5-811-6 CHAPTER 6 GAS TURBINE POWER PLANT DESIGN 6-1. General consideration of the number of units or the total Gas turbines find only limited application as prime plant capacity, movers for power generation at military facilities. (2) Initial selection of the gas turbine unit be- This is because gas turbine generators typically gins using the International Standards Organiza- have significantly higher heat rates than steam tur- tion (ISO) rating provided on the manufacturer’s bine or diesel power plants; their higher fuel costs data sheets. This is a power rating at design speed quickly outweigh their initial advantages in most and at sea level with an ambient temperature of applications. Applications to be evaluated include: 590F (150C). The ISO rating considers inlet and out- a. Supplying relatively large power requirements let losses to be zero. Initially, ISO ratings will be re- in a facility where space is at a significant pre- duced 15 percent for typical applications, which willmium—such as hardened structure. further be refined to reflect actual site and installa- b. Mobile, temporary or difficult access site— tion conditions. The four variables which will be con- such as a troop support or lie of sight station. sidered in unit rating are: c. Peak shaving, in conjunction with a more effi- (a) Elevation.cient generating station. (b) Ambient temperature. d. Emergency power, where a gas turbine’s light (c) Inlet losses.weight and relatively vibration-free operation are of (d) Exhaust losses.greater importance than fuel consumption over The following subsections define the impact of eachshort periods of operation. However, the starting of these variables.time of gas turbines may not be suitable for a given b. Elevation. For a specific site, the ISO rating re-application. duction due to site altitude is read directly from an e. Combined cycle or cogeneration power plants altitude correction curve published by the variouswhere turbine exhaust waste heat can be econom- manufacturers. There is little difference in suchically used to generate additional power and thermal curves. For mobile units, the effect of possible siteenergy for process or space heating. altitudes will be evaluated. The operating altitude will be used to determine the unit rating. c. Temperature. Site temperature data will be ob- 6-2. Turbine-generator selection tained from TM 5-785. The design temperature se- a. Packaged plants. Gas turbines are normally lected is normally the 2 1/2 percent dry bulb tempera-purchased as complete, packaged power plants. ture, although the timing of the load curve peak willWith few exceptions, only simple cycle turbines are also be considered. Unless the choice of equipment isapplicable to military installations. Therefore, the tight, there is usually sufficient overload capabilityremainder of this chapter focuses on the simple to carry the unit during the 2 1/2 percent time of high-cycle configuration. The packaged gas turbine pow- er temperature. Another temperature related selec-er plant will include the prime mover, combustion tion parameter is icing. Icing is caused when thesystem, starting system, generator, auxiliary right combination of temperature and humidity lev-switchgear and all turbine support equipment re- els occurs, and is manifested by ice formation on thequired for operation. This equipment is usually downstream side of the inlet filters or at the com-“skid” or base mounted. The only “off base” or pressors bell mouth intake. Chunks of ice can beadditional auxiliaries normally required to supple- sucked in the compressor with possible blade dam-ment the package are the fuel oil storage tanks, age resulting. Icing occurs when ambient tempera-transfer pumps and oil receiving station, distribu- tures are in the 350 to 420F. range and relative hu-tion switchgear, step up transformer and switch- midity is high. This problem will be avoided by recir-yard, as required. culating hot air from the compressor discharge to (1) Selection of unit size requires establishment the filter inlet, either manually or automatically.of plant loading and the number of units required for This causes some loss of turbine efficiency.reliability y and turndown. Wide gaps in the standard d. Inlet losses. Inlet losses are a critical perform-equipment capacity ratings available may force re- ance variable, and one over which the designer has 6-1
  • TM 5-811-6considerable control. Increases in the inlet air fric- sembled into three or more skid mounted modules,tion cause a significant reduction in power output. each with its own weatherproof housing the sepa-The total inlet pressure loss will not exceed 2 inches rate modules have wiring splits, piping connections,of water and will be as close to zero as space limita- and housing flanges arranged so that the modulestions and economics will permit. Additional duct- may be quickly assembled into a unit on a reinforcedwork costs will be quickly amortized by operating concrete pad in the field. Supplementing these mainfuel savings. Dust, rain, sand and snow will be pre- modules are the inlet and exhaust ducts, inlet si-vented from entering the combustion air inlet of the lencer and filters, exhaust silencer, fuel tanks, unitengine. Inlet air filter design will preclude entrance fuel skid, and unit auxiliary transformer which areof these contaminants with minimal pressure loss. connected by piping and cables to the main as-The air inlet will be located to preclude ingestion of sembly after placing on separate foundation ascombustion products from other turbines or a near- may be required.by boiler plant, or hot, humid discharge from any (b) The other outdoor sub-type is a similarcooling towers. package unit except that the weatherproof housing e. Outlet losses. Outlet friction losses also result is shipped knocked down and is, in effect, a prefabri-in a decrease of turbine-generator output and will be cated building for quick field assembly into a clo-accounted for in the unit design. The major factor in sure for the main power plant components.outlet losses is the requirement to attenuate noise. (c) Outdoor units to be provided with all com-More effective silencers typically have higher pres- ponents, auxiliaries and controls assembled in all-sure losses. Exhaust back pressure has a smaller weather metal enclosures and furnished completeoverall effect on performance than inlet losses but for operation will be specified for Class “B” and “C”will be kept as low as possible, and will be less than power plants having a 5-year anticipated life and re-6 inches of water. Since increasing exhaust silencer quiring not more than four generating units.size costs considerably more than ductwork design (2) Indoor. An indoor type unit will have theimprovements, the return on investment for a low compressor-turbine-generator mounted at gradepressure loss exhaust is significantly longer. floor level of the building on a pad, or possibly raised above or lowered below grade floor level to6-3. Fuels provide space for installation of ducts, piping andEach manufacturer has his own specification on fuel cabling. Inlet and exhaust ducts will be routed toacceptable for his turbine. The high grade liquid the outside through the side wall or the roof; the sidefuels such as Diesel No. 1 or 2 and JP-4 or JP-5 will wall is usually preferable for this so that the turbinelikely be acceptable to all manufacturers. Use of room crane can have full longitudinal travel in theheavier oils is possible with a specially designed tur- turbine generator bay. Filters and silencers may bebine. The heavy oil will have to be cleaned up to re- inside or outside. All heat rejection equipment willduce corrosive salts of sodium, potassium, vana- be mounted outside while fuel oil skids may be in-dium, and sulfur–all of which will elevate the cost side or outside. Unit and distribution switchgearof the fuel. Storage and handling at the site will also and motor control centers will be indoors as in a con-be more costly, particularly if a heavy oil such as ventional steam power plant. Figure 6-1 shows aNo. 6 was involved because of the heating require- typical indoor unit installation with the prime mov-ment. No. 4 oil will increase transfer pumping costs er mounted below grade floor level.a bit but, except in extremely cold regions, wouldnot require heating. 6-5. Waste heat recovery Waste heat recovery will be used wherever cost ef-6-4. Plant arrangement fective. If the turbine unit is to be used only inter- a. General. Turbine generator units are frequent- mittently, the capital cost of heat recovery must bely sold as complete packages which include all com- kept down in order to be considered at all. Add-on orponents necessary to operate, ready for connection sidestream coils might provide a temporary hotto the fuel supply and electrical distribution system. water supply for the period of operation—for one ex-This presents the advantages of faster lead time, ample. Care must be exercised due to the high ex-well matched components and single point of perfor- haust gas temperature. It may prove feasible tomance responsibility y. flash steam through the jacket of a small heat ex- b. Outdoor vs. indoor. changer. In the event that a long term operation is (1) Outdoor. Outdoor units can be divided into indicated, the cost trade off for heat recovery equiptwo sub-types. ment is enchanced, but still must be considered as (a) The package power plant unit is supplied an auxiliary system. It will take a sizable yearlywith the principal components of the unit factory as- load to justify an exhaust gas heat recovery boiler.6-2
  • , TM 5-811-6 L. r AIR INTAKE WET CELL WASHER OR FILTER I Rs1 T I 2s’-0’ T w w A . I STACK ExHAuST A. I Q ~ n 1 ,1 n Ii , L 1 r l?$dLEJ%/ &~a:. ,! I ‘ l-w ;r .-. . ,. . ... . “’-’”A’&?yBAsEMENTk~;fl lNTi4KE . . . . . FLOOR ,------ .7. -... LONGITUDINAL SECTION “A” -“A” , NAVFAC DM3 Figure 6-1. T:ppical indoor simple cycle gas turbine generatorpowerpkznt. Turbine efficiency loss due to back pressure is also a gas turbine power plant, including the generator, factor to be considered. switchgear, switchyard, transformers, relays and controls. Chapter 2 describes the pertinent civil fa- 6-6. Equipment and auxiliary systems cilities. a. GeneraL The gas turbine package is a complete c. Scope. The scope of a package gas turbine gen- power plant requiring only adequate site prepara- erator for purchase from the manufacturer will in- tion, foundations, and support facilities including clude the following fuel storage and forwarding system, distribution (1) Compressor and turbine with fuel and com- switchgear, stepup transformer, and switchyard. If bustion system, lube oil system, turning gear, gov- the fuel to be fired is a residual oil, a fuel washing ernor, and other auxiliaries and accessories. and treating plant is also required. ‘L b. References. Chapter 4 sets forth guidelines for (2) Reduction gear. the design of the electrical facilities required for a (3) Generator and excitation system. 6-3
  • TM 5-811-6 (4) AC auxiliary power system including (9) Unit fuel skid (may be purchased separatelyswitchgear and motor controls. if desired). (5) DC power system including battery, charg- (10) Intake and exhaust ducts.er, and inverter if required. (11) Intake air filters. (6) External heat rejection equipment if re- (12) Acoustical treatment for intake and ex-quired. haust ducts and for machinery. (7) All mechanical and electrical controls. (13) Weatherproof housing option with appro- (8) Diesel engine or electric motor starting sys- priate lighting, heating, ventilating, air condition-tem. ing and fire protection systems. 6-4
  • CHAPTER 7 DIESEL ENGINE POWER PLANT DESIGN 7-1. Engines (2) Exhaust and exhaust silencng. a. Diesel engines have higher thermal efficiencies (3) Source of secondary cooling (heat sink). than other commercial prime movers of comparable (4) Engine foundation and vibration isolation. size. Diesel engine-generators are applicable to elec- (5) Fuel storage, transfer and supply to the en- tric loads. from about 10 to 5000 kilowatts. Diesel- gine. engine-driven electric generator sets are divided into (6) Electrical switchgear, stepup transformer, if three general categories based on application as fol- required, and connection to distribution wiring. lows: (7) Facilities for engine maintenance, such as (1) Class A: Diesel-electric generator sets for cranes, hoists and disassembly space. stationary power plants generating prime power (8) Compressed air system for starting, if re-continuously at full nameplate kW rating as the sole quired. source of electric power. e. Generator design criteria are provided in (2) Class B: Diesel-electric generators sets for Chapter 4.stationary power plants generating power on astandby basis for extended periods of time where 7-2. Fuel selectionmonths of continuous operation at full nameplate A fuel selection is normally made according to avail-kW rating are anticipated. ability and economic criteria during the conceptual (3) Class C: Diesel-electric generator sets for design. Fuels are specified according to ASTM, Fed-stationary power plants generating power on an eral and military specifications and include:emergency basis for short periods of time at full a. ASTM Grades l-D, 2-D, and 4-D as specifiednameplate kW rating where days of continuous by ASTM D 975. These fuels are similar to No. 1,operation are anticipated. No. 2 and No. 4 heating oils. b. Diesel engines normally will be supplied as b. Federal Specification Grades DF-A and DF-2skid mounted packaged systems. For multiple-unit (see Federal Specification VV-F-800). These specifi-procurement, matched engine-generator sets will be cations parallel ASTM Grades 1-D and 2-D, respec-provided for units of 2500kW electrical output or tively.less. For larger units, investigate the overall eco- c. Jet Fuel Grade JP-5 (Military Specificationnomics and practicality of purchasing the gener- MIL-T-5624).ators separately, recognizing that the capability for d. Marine Diesel (Military Specification MIL-reliable operation and performance of the units are F-16884). Marine Diesel is close to ASTM No. 2-D,sacrificed if engine and generator are bought from although requirements differ somewhat.two sources. e. ASTM No. 6, or its Federal equivalent, or Navy c. Engines and engine-generator sets are normal- special may be specified for engines in excess ofly provided with the primary subsystems necessary 2000 kW if economics permit. Fuel selection mustfor engine operation, such as: be closely coordinated with the requirements of the (1) Starting system. engine manufacturer. The No. 2-D or DF- 2 fuels are (2) Fuel supply and injection system. most common. If fuel is stored at ambient tempera- (3) Lubrication system and oil cooling. tures below 200F,, No. 1-D or DF-A (arctic fuel) (4) Primary (engine) cooling system. should be considered. ASTM No. 4-D or No. 6 are (5) Speed control (governor) system. residual oil blends which require preheating prior to (6) Required instrumentation. burning. Fuel oil storage and handling equipment d. The designer must provide for the following and the engine itself will be specifically designed for (1) Intake air. burning these viscous fuel oils. 7-1
  • TM 5-811-6 Section ll. BALANCE OF PLANT SYSTEMS7-3. General a waste heat boiler which can be used for space heat-Balance of plant systems are those which must be ing, absorption refrigeration, or other useful pur-provided and interfaced with a packaged diesel or pose. This boiler produces steam in parallel with thediesel-generator set to provide an operational gener- vapor phase cooling system. The exhaust silencerating unit. attenuates exhaust gas pulsations (noise), arrests sparks, and in some cases recovers waste heat. The7-4. Cooling systems muffler design will provide the required sound at- a. Water-to-water systems. Jacket water and lube tenuation with minimum pressure loss.oil cooling heat exchangers are cooled by a sec- 7-6. Fuel storage and handlingondary circulating water system. Normally, a recir- a. Storage requirements.culating system will be used. Heat is dissipated tothe atmosphere through an evaporative, mechan- (1) Aboveground fuel storage tanks with a mini-ical-draft cooling tower. If the plant is located on or mum capacity for 30 days continuous operation willnear a body of water, once-through circulating water be provided for continuous and standby dutywill be evaluated. Bidders will be informed of the plants. Fuel storage shall be designed to the require-type and source of secondary water used so heat ex- ments of NFPA 30. A tank with 3 day storage ca-changers can be designed for their intended service. pacity will be provided for emergency duty plants. b. Water-to-air systems. Water-to-air systems (2) For continuous duty plants, provide a daywill be restricted to small engines. If an integral tank for each engine. The tank will provide a 4-hour(skid mounted) radiator is used, sufficient cooling storage capacity at maximum load. The tank will beair will be provided. Outside air may be ducted to filled by automatic level controls and transferthe radiator air inlet. Ductwork will be designed for pumps. Standby plants will be provided with dayminimum pressure loss. The cooling fan(s) will be tanks of sufficient capacity to permit manual fillingchecked for adequate flow (cfm) and static pressure once per shift (10-hour capacity). No separate dayunder the intended service. Air leaving the radiator tank is required for emergency plants.normally goes to the engine room and is exhausted. b. Fuel handling. Provide unloading pumps if fuelCooling air inlets will be equipped with automatic is to be delivered by rail car or barge. Most fuel tankdampers and bird screens. trucks are equipped with pumps. Provide transfer pumps capable of filling the day tank in less than 1/2 7-5. Combustion air intake and exhaust hour when the engine is operating at maximum load. systems Duplex pumps, valved so that one can operate while the other is on standby, will be provided for reliabil- a. Purpose. The functions of the intake and ex- ity. Pipeline strainers and filters will be provided tohaust systems are to deliver clean combustion air to protect the fuel pumps and engine injectors fromthe engine and dispose of the exhaust quietly with dirt. Strainers and filters will not pass particles larg-the minimum loss of performance. er than half the injector nozzle opening. b. Intake. The air intake system usually consistsof air intake duct or pipe appropriately supported, a 7-7. Engine room ventilationsilencer, an air cleaner, and flexible connections as About 8 percent of the heating value of the fuel con-required. This arrangement permits location of area sumed by the engine is radiated to the surroundingof air intake beyond the immediate vicinity of the air. It is essential that provision be made for re-engine, provides for the reduction of noise from in- moval of this heat. Engine room temperature risetake air flow, and protects vital engine parts against should be limited to 150F. For engines with wallairborne impurities. The air intake will be designed mounted or ducted radiators, radiator fans may beto be short and direct and economically sized for sufficient if adequate exhaust or air relief is pro-minimum friction loss. The air filter will be designed vided. If engines are equipped with water cooledfor the expected dust loading, simple maintenance, heat exchangers, a separate ventilation system willand low pressure drop. Oil bath or dry filter element be provided. The approximate ventilation rate mayair cleaners will be provided. The air filter and si- be determined by the following formula:lencer may be combined. 1,000 x HP c. Exhaust. The exhaust system consists of a CFM =muffler and connecting piping to the atmosphere Twith suitable expansion joints, insulation, and sup- where:ports. In cogeneration plants, it also provides for HP = maximum engine horsepowerutilization of exhaust heat energy by incorporating T = allowable temperature rise, ‘F.7-2
  • TM 5-811-6 Provision will be made to allow for reducing the air the engine room; however, jacket water cooling will flow during the cooler months so as not to over-cool remain within recommended limits at all times. Section Ill. FOUNDATIONS AND BUILDING 7-8. General 7-10. Building Chapter 2 should be consulted for the civil facilities a. Location. design criteria associated with a diesel power plant. (1) A diesel engine power plant has few limita- This section amplifies the civil engineering aspects tions regarding location. Aesthetically, an architec- directly applicable to the diesel plant. turally attractive building can enclose the equip- ment if required. Fuel can be stored underground if 7-9. Engine foundation appearance so dictates. Proper exhaust and intake air silencing can eliminate all objectionable noise. a. Design considerations. Air and water pollution problems are minimal with (1) The foundation will have the required mass most recommended fuels.’ and base area, assuming installation on firm soil and (2) Consider the relative importance of the fol- the use of high quality concrete. Before final details lowing when selecting a plant site: of the foundation design are established by the de- (a) Proximity to the center of power demand. signer, the bearing capacity and suitability of the (b) Economical delivery of fuel. soil on which the foundation will rest will be deter- (c) Cost of property. mined. Modification of the manufacturer’s recom- (d) Suitability of soil for building and machin- mended foundation may be required to meet special ery foundations. requirements of local conditions. Modifications re- (e) Space available for future expansion. quired may include: (f) Proximity to potential users of engine (a) Adjustment of the mass. waste heat. (b) Additional reinforcing steel. (g) Availability of water supply for cooling (c) Use of a reinforced mat under the regular systems. foundation. b. Arrangement. (d) Support of the foundation on piles. Piling (1) In designing the power plant building, a gen- may require bracing against horizontal displace- ment. eral arrangement or plant layout will be designed for the major components. The arrangement will facili- ‘ (2) The engine foundation will extend below the tate installation, maintenance and future plant ex- footings of the building and the foundation will be pansion. Ample space shall be provided around each completely isolated from the walls and floors of the unit to create an attractive overall appearance and building. The foundation block will be cast in a sin- simplify maintenance for engines and auxiliary gle, continuous pour. If a base mat is used, it will be equipment. cast in a separate continuous pour and be provided (2) In addition to the basic equipment arrange- with vertical re-bars extending up into the founda- ment, provide for the location of the following, as re- tion block. quired by the project scope: b. Vibration mounts. (a) Office space. (1) For small engine installations where there is (b) Lunchroom and toilet facilities. a possibility y of transmission of vibration to adjacent (c) Engine panels, plant and distribution areas, the engine foundations will be adequately in- switchgear, and a central control board (Chapter 5, sulated by gravel, or the engine mounted on vibra- Section I). tion insulating material or devices. Vibration (d) Cooling system including pumps and heat mounts for larger engines become impractical and exchangers. foundation mass must be provided accordingly. (e) Lube oil filters and, for heavier fuels, fuel (2) Skid mounted generating units will be sup- oil processing equipment such as centrifuges. plied with skids of sufficient strength and rigidity to (f) Tools and operating supplies storage. maintain proper alignment between the engine and (g) Facilities for maintenance. the generator. Vibration isolators, either of the ad- (h) Heat recovery equipment, if included. justable spring or rubber pad type, will be placed be- (3) The main units should usually be lined up in tween the unit skid and the foundation block to min- parallel, perpendicular to the long axis of the engine imize the transmission of vibrations. room thus making unlimited future expansion easy 7-3
  • TM 5-811-6and economical. The engine bay will be high enough possible wiring between the switchgear and gener-for a motorized, overheat traveling crane. The crane, ators. The switchgear may be enclosed in a separateif economically feasible, will be sized for mainte- room or maybe a part of the main engine bay. -nance only. The switchgear will be located at the (4) A typical small two-unit diesel power plantgenerator end of each unit, permitting the shortest arrangement is shown in Figure 7-1. U.S. Army Corps of Engineers Figure 7-1. Typical diesel generator power plant.7-4
  • TM 5-811-6 CHAPTER 8 COMBINED CYCLE POWER PLANTS Section 1. TYPlCAL PLANTS AND CYCLES 8-1. Introduction expensive. Heavier distillates and residual oils are a. Definition. In general usage the term ‘ ‘com- also expensive as compared to coal. bined cycle power plant” describes the combination 8-2. Plant details of gas turbine generator(s) (Brayton cycle) with tur- bine exhaust waste heat boiler(s) and steam turbine a. Unfired boiler operation. For turbines burning generator(s) (Rankine cycle) for the production Of natural gas or light distillate oil, the boiler will be of electric power. If the steam from the waste heat boil- the compact, extended surface design with either er is used for process or space heating, the term "co- natural or forced circulation with steam generated generation” is the more correct terminology (simul- at approximately 650 psig and 8250F. The addition taneous production of electric and heat energy). of the waste heat boiler-steam turbine generator combinations increases power output over the sim- b. General description. ple gas turbine. (1) Simple cycle gas turbine generators, when b. Fired boiler operation. The exhaust from a gas operated as independent electric power producers, turbine contains large amounts of excess air. This are relatively inefficient with net heat rates at full exhaust has an oxygen content close to fresh air, load of over 15,000 Btu per kilowatt-hour. Conse- and will be utilized as preheated combustion air for quently, simple cycle gas turbine generators will be supplementary fuel firing. Supplementary fuel fir- used only for peaking or standby service when fuel ing permits increasing steaming of the waste heat economy is of small importance. boiler. Burners will be installed between the gas tur- (2) Condensing steam turbine generators have bine exhaust and the waste boiler to elevate the ex- full load heat rates of over 13,000 Btu per kilowatt- haust gases to the heat absorption limitations of the hour and are relatively expensive to install and oper- waste heat boiler. Supplementary burners also per- ate. The efficiency of such units is poor compared to mit generation when the gas turbine is out ofthe 8500 to 9000 Btu per kilowatt-hour heat rates service. typical of a large, fossil fuel fired utility generating c. Other types of combined cycle plants. Varia- station. tions of combined cycle plants areas follows: (3) The gas turbine exhausts relatively large (1) Back pressure operation of the steam tur- quantities of gases at temperatures over 900 “F, In bine. This may include either unfired or fired boilercombined cycle operation, then, the exhaust gases operation. The steam turbine used is a non-condens- from each gas turbine will be ducted to a waste heat ing machine with all of the exhaust steam utilized boiler. The heat in these gases, ordinarily exhausted for heating or process at a lower pressure level.to the atmosphere, generates high pressure super- (2) Controlled (automatic) extraction operationheated steam. This steam will be piped to a steam of the steam turbine. This may also include either turbine generator. The resulting “combined cycle” unfired or fired boiler operation. A controlled extrac- heat rate is in the 8500 to 10,500 Btu per net kilo- tion steam turbine permits extraction steam flow towatt-hour range, or roughly one-third less than a be matched to the steam demand. Varying amountssimple cycle gas turbine generator. of steam can be used for heating or process pur- (4) The disadvantage of the combined cycle is poses. Steam not extracted is condensed. This typethat natural gas and light distillate fuels required of steam turbine will only be used when electrical re-for low maintenance operation of a gas turbine are quirements are very large (see Chapter 1). Section Il. GENERAL DESIGN PARAMETERS8-3. Background turbine and steam turbine power plants. The wasteA combined cycle power plant is essentially com- heat boiler is different in design, however, from aprised of standard equipment derived from both gas normal fossil fueled boiler. Feedwater heating is 8-1
  • TM 5-811-6usually less complex. Power plant controls must load decreases with load-following between shut-take into account the simultaneous operation of gas down steps by any or both of the above methods.turbine, boiler and steam turbine. (d) Installation of gas dampers to bypass variable amounts of gas from turbine exhaust di-8-4. Design approach rectly to atmosphere. With this method, gas turbine exhaust and steam temperatures can be maintained a. Operating differences. The following items while steam flow to steam turbine generator is de-should be given consideration: creased as is the load. This has the added advantage (1) Turndown. Gas turbine mass flows are fairly that if both atmospheric bypass and boiler dampersconstant, but exhaust temperature falls off rapidly are installed, the gas turbine can operate while theas load is reduced. Therefore, decreasing amounts of steam turbine is down for maintenance. Also, if fullsteam are generated in the waste heat boiler. Varia- fuel firing for the boiler is installed along with ations in gas turbine generator output affect the out- standby forced draft fan, steam can be producedput from the steam turbine generator unless supple- from the boiler while the gas turbine is out for main-mentary fuel is fired to adjust the temperature. Sup- tenance. This plan allows the greatest flexibilityplementary fuel firing, however, decreases combined when there is only one gas turbine-boiler-steam tur-cycle efficiency because of the increased boiler stack bine train. It does introduce equipment and controlgas losses associated with the constant mass flow of complication and is more costly; and efficiency de-the turbine. creases as greater quantities of exhaust gas are by (2) Exhaust gas flows. For the same amount of passed to atmosphere.steam produced, gas flows through a combined cycle (2) Boiler design.boiler are always much higher than for a fuel fired (a) Waste heat boilers must be designed forboiler. the greater gas flows and lower temperature differ- (3) Feedwater temperatures. With a combined entials inherent in combined cycle operation. If acycle plan, no air preheater is needed for the boiler. standby forced draft fan is installed, the fan must beHence, the only way to reduce final stack gas exit carefully sized. Gas turbine full load flow rates needtemperature to a sufficiently low (efficient) level is not be maintained,to absorb the heat in the feedwater with economizer (b) If the fuel to be fired, either in the gas tur-recovery equipment. Inlet feedwater temperature bine or as supplementary fuel, is residual oil, baremust be limited (usually to about 2500F) to do this. tubes should be used in the boiler with extended sur- b. Approaches to specialized problems: face tubes used in the economizer only. This in- (1) Load following. Methods of varying loads creases the boiler cost substantially but will pre-for a combined cycle include: clude tube pass blockages. Soot blowers are required (a) Varying amount of fuel to a gas turbine for heavy oil fired units.will decrease efficiency quickly as output is reduced (3) Feedwater heating and affect on steam gen-from full load because of the steep heat rate curve of erator design.the gas turbine and the multiplying effect on the (a) Because of the requirement for relativelysteam turbine. Also, steam temperature can rapidly low temperature feedwater to the combined cyclefall below the recommended limit for the steam tur- boiler, usually only one or two stages of feedwaterbine. heating are needed. In some cycles, separate econo- (b) Some supplementary firing may be used mizer circuits in the steam generator are used tofor a combined cycle power plant full load. Supple- heat and deaerate feewater while reducing boilermentary firing is cut back as the load decreases; if exit gas to an efficient low level.load decreases below combined output when supple- (b) For use in military installations, only co-mentary firing is zero, fuel to the gas turbine is also generation combined cycles will be installed. A typi-cut back. This will give somewhat less efficiency at cal cycle diagram is shown in Figure 8-1.combined cycle full load and a best efficiency point (4) Combined cycle controls. There is a wideat less than full load; i.e., at 100 percent waste heat variation in the controls required for a combined cy-operation with full load on the gas turbine. cle unit which, of course, are dependent on the type (c) Use of a multiple gas turbine coupled with of unit installed. Many manufacturers have de-a waste heat boiler will give the widest load range veloped their own automated control systems towith minimum efficiency penalty. Individual gas suit the standardized equipment array which theyturbine-waste heat units can be shut down as the have developed.8-2
  • TM 5-811-6.* 8-3
  • TM 5-811-6 APPENDIX A REFERENCES Government Publications Code of Federal Register Part 436: Federal Energy Management and Planning Program. 10 CFR 436A Subpart A: Methodology and Procedures for Life Cycle Cost Analysis. Federal Specifications VV-F-800 Fuel Oil, Diesel.q¦ Department of Defense DOD 4270.1-M Department of Defense Construction Manual Guide. Army Regulations AR 11-28 Economic Analysis and Program Evaluation for Resource Management. Air Force Regulations AFR 178-1 Economic Analysis and Program Evaluation for Resources Manage- ment. Military Specifications MIL-T-5624L Turbine Fuel, Aviation, Grades JP-4 and JP-5. MIL-F-16884C Fuel Oil, Diesel, Marine. MIL-P-17552D Pump Units, Centrifugal, Water, Horizontal; General Service and Boiler Feed: Electric Motor or Steam Turbine Driven. Departments of the Army, Air Force and Navy TM 5-803-5/NAVPAC P-960 Installation Design. AFM 88-43 TM 5-805-41AFM 88-371 Noise Control for Mechanical Equipment. NAVFAC DM-3.1O TM 5-805-91AFM 88-201 Power Plant Acoustics. NAVFAC DM-3.14 TM 5-815-l/AFR 19-6/ Air Pollution Control Systems for Boilers and Incinerators. NAVFAC DM-3.15 Departments of the Army and Air Force TM 5-810-l/AFM 88-8, Mechanical Design - Heating, Ventilating and Air Conditioning. Chap. 1 TM 5-811 -l/AFM 88-9, Electrical Power Supply and Distribution. Chap, 1 TM 5-811-2/AFM 88-9, Electrical Design, Interior Electrical System. Chap. 2 TM 5-818-2/AFM 88-6, Pavement Design for Frost Conditions. Chap. 4 TM 5-822-2/AFM 88-7, General Provisions and Geometric Design for Roads, Streets, Walks, and Chap. 5 Open Storage Areas. TM 5-822-41AFM 88-7, Soil Stabilization for Roads and Streets. Chap. 4 TM 5-822-5/AFM 88-7, Flexible Pavements for Roads, Streets, Walks and Open Storage Areas. Chap, 3 A-1
  • TM 5-811-6TM 5-822-6/AFM 88-7, Rigid Pavements for Roads, Streets, Walks and Open Storage Areas. Chap. 1TM 5-822-7/AFM 88-7, Standard Practice for Concrete Pavements. Chap. 8Department of the ArmyTM 5-785 Engineering Weather Data.TM 5-822-8 Bituminous Pavements - Standard Practice.Non-Government PublicationsAmerican National Standards Institute (ANSI), 1430 Broadway, New York, N.Y. 10018B31.1 Code for Pressure Piping - Power Piping.C5O.1O General Requirements for Synchronous Machines.C50.13 Requirements for Cylindrical Rotor Synchronous Generators.C50.14 Requirements for Combustion Gas Turbine Cylindrical Rotor Syn- chronous Generators.C57.12.1O Requirements for Transformers, 230,000 Volts and Below, 833/958 Through 8,333/10,417 kVA, Single-Phase, and 750/862 Through 60,000/80,000/100,000 kVA, Three-Phase.C84.1 Voltage Ratings for Electrical Power Systems and Equipment.American Society of Mechanical Engineers, 345 East 47th Street, New York, N.Y. 10017ASME Code ASME Boiler and Pressure Code: Section I, Power Boilers; Section II, Material Specifications; Section VIII, Pressure Vessels; Section IX, Welding and Brazing Qualifications.ASME TWDPS-1 Recommended Practices of Water Damage to Steam Turbines Used for Electric Power Generation (Part 1- Fossil Fueled Plants).Institute of Electrical and Electronic Engineers, (NEMA) IEEE Service Center, 445 Hoes Lane, Piscataway, N.J. 08854100 Standard Dictionary of Electrical and Electronic Terms.112 Test Procedure for Polyphase Indicator Motors and Generators.114 Test Procedure for Single Phase Induction Motors.115 Test Procedure for Synchronous Machines.National Electrical Manufacturer’s Association, 155 East 44th Street, New York, N.Y. 10017SM 12 Direct-Connected Steam Turbine Synchronous Generator Units, Air Cooled.SM 13 Direct-Connected Steam Turbine Synchronous Generator Units, Hydro- - gen Cooled (20,000 to 30,000 kW, Inclusive).National Fire Protection Association, Publication Sales Department, 470 Atlantic Avenue, Boston, MA. 0221030 Flammable and Combustible Liquids Code.70 National Electric Code.General Electric Company, Lynn, MA. 0910GEK 22504 Standard Design and Operating Recommendations to Minimize Water Rev. D. Induction in Large Steam Turbines.Westinghouse Electric Corporation, Lester, PA. 19113— Recommendation to Minimize Water Damage to Steam Turbines.A-2
  • TM 5-811-6 BIBLIOGRAPHYAmerican Institute of Architecture, Life Cycle Cost Analysis - A Guide for Architects, AIA, 1735 New York Avenue, Washington, DC 20006Fink and Beatty, Standard Handbook for Electrical Engineers, McGraw Hill Book Company, New York, N.Y. 10020Grant, Ireson and Leavenworth, Principals of Engineering Economy, John Wiley & Sons, Inc., New York, N.Y. 10036Kent, R. T., Kents Mechanical Engineers Handbook Power Volume, John Wiley& Sons, Inc., New York, N.Y. 10036Marks Standurd Handbook for Mechanical Engineers, McGraw Hill Book Company, New York, N.Y. 10020Mason, The Art and Science of Protective Relaying, General Electric Engineering Practice Series, John Wiley & Sons, Inc., New York, N.Y. 10036Morse, Frederick T., Power Plant Engineering and Design, D. Van Nostrand Company, Inc., New York, N.Y.Naval Facilities Engineering Command, Economic Analysis Handbook, NAVFAC P442, U.S. Naval Publica- tions and Forms Center, 5801 Tabor Avenue, Philadelphia, PA. 19120.
  • TM 5-811-6 Changes to Publications and Blank Forms) directly to HQDA (DAEN-ECE-E), WASH DC 20314. By Order of the Secretary of the Army: JOHN A. WICKHAM, JR. General United States Army Official: Chief of Staff ROBERT M. JOYCE Major General United States Army The Adjutant General* U . S . GOVERNMENT PRINTING OFFICE: 1983-424-688