kota super thermal Power station training report


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kota super thermal Power station training report

  1. 1. A Practical Training Report On KOTA SUPER THERMAL POWER STATION Submitted in partial fulfillment for the award of the degree of BACHELOR OF TECHNOLOGY In Mechanical Engineering 2012-2013 (01 June 2012- 30 June 2012)Submitted to: - Submitted by: -Mr. Asheesh Goyal Aman AgrawalLecturer, 09EVVME005Mechanical Engg. B.Tech. IV Yr. VII Sem RAJASTHAN TECHNICAL UNIVERSITY, KOTA DEPARTMENT OF MECHANICAL ENGINEERING VIVEKANANDA INSTITUTE OF TECHNOLOGY (EAST)
  2. 2. PREFACE A student gets theoretical knowledge from classroom and gets practical knowledge fromindustrial training. When these two aspects of theoretical knowledge and practical experiencetogether then a student is full equipped to secure his best. In conducting the project study in an industry, students get exposed and haveknowledge of real situation in the work field and gains experience from them. The object of thesummer training cum project is to provide an opportunity to experience the practical aspect ofTechnology in any organization. It provides a chance to get the feel of the organization and itsfunction. The fact that thermal energy is the major source of power generation itself shows theimportance of thermal power generation in India – more than 60 percent of electric power isproduced by steam plant in India. In steam power plants, the heat of combustion of fossil fuels is utilized by the boilersto raise steam at high pressure and temperature. The steam so produced is used in drivingthe steam turbine coupled to generators and thus in generating ELECTRICAL ENERGY ii
  3. 3. ACKNOWLEDGEMENT It is a matter of great pleasure and privilege for me to present this report of 30 dayson the basis of practical knowledge gained by me during practical training at KOTA SUPERTHERMAL POWER STATION (K.S.T.P.S.), KOTA (Rajasthan) during session 2012-2013. I with full pleasure converge my heartiest thanks to Head of Electrical Department,Mr. Rahul goyal, Vivekanada institute of technology(East) and to my guide Mr. Asheesh goyal,Assistant Professor, Department of Mechanical Engineering. I am also grateful to Er. S.C.Madan & Er. G.K.Rathi to support me at each andevery step of my training Schedule. I attribute hearties thanks to all Engineering departmentsand Engineers for their Ample Guidance during my training period. Aman Agrawal iii
  5. 5. CONTENTS Title Page NoCHAPTER 1 INTRODUCTION………………………………….………... 1-4 1.1 DESIGN OF K.S.T.P.S. ……………………..... 3 1.2 SITE SELECTION CRITERIA………………….. 3 1.3 DESIGN FEATURES………………………....... 4CHAPTER 2 GENERAL LAYOUT AND BASIC IDEA………………... 5-7 2.1 FUEL AND ASH CIRCUIT………………………. 6 2.2 AIR AND GAS CIRCUIT………………………… 6 2.3 FEED WATER AND STEAM CIRCUIT………… 6 2.4 COOLING WATER CIRCUIT…………….......... 7CHAPTER 3 COAL HANDLING PLANT……………………………….. 8 -11 3.1 WAGON UNLOADING SYSTEM……………… 8 3.2 CRUSHING SYSTEM………………………….. 10 3.3 CONSTRUCTION AND OPERATION………… 10 3.4 CONVEYING SYSTEM…………………………. 11 3.5 CONVEYOR BELT SPECIFICATION………….. 11CHAPTER 4 ASH HANDLING PLANT…………………………........... 12-14 4.1 FUEL AND ASH PLANT………………………….. 12 4.2 AIR AND GAS PLANT……………………………. 12 4.3 ASH AND DUST COLLECTION PLANT………… 13 4.4 UTILISATION……………………………………….. 13CHAPTER 5 ELECTRO-STATIC PRECIPITATOR…………………….. 15-16 5.1 PRINCIPLE OF OPERATION…………………… 15 v
  6. 6. 5.2 CONTROLLER…………………………………… 15 ` 5.3 HIGH VOLTAGE RECTIFIER TRANSFORMER… 16 5.4 E.S.P. FIELD……………………………………... 16CHAPTER 6 BOILER…………………………………………………… 17-28 6.1 BOILER CLASSIFICATION………………….. 17 6.2 FURNANCE…………………………………… 18 6.3 PULVERISED FUEL SYSTEM……………… 19 6.4 FUEL OIL SYSTEM………………………….. 19 6.5 BOILER DRUM……………………………….. 20 6.6 DRAFT SYSTEM…………………………….. 22 6.7 DRAUGHT FAN………………………………. 22 6.8 ECONOMIZER………………………………. . 23 6.9 AIR-PREHEATER……………………………. 23 6.10 SUPERHEATER……………………………. 24 6.11 REHEATER…………………………………. 25 6.12 CIRCULATION SYSYTEM………………... 25 6.13 SOOT BLOWER……………………………. 26 6.14 TECHNICAL SPECIFICATION OF BOILER... 26CHAPTER 7 STEAM TURBINE………………………………………… 29-32 7.1 PRINCIPLE …………………………………… 30 7.2 DESCRIPTION OF STEAM TURBINE……… 31CHAPTER 8 TURBO GENERATOR……………………………………. 33-40 8.1 THEORY………………………………………. 33 8.2 ROTOR……………………………………….. 37CHAPTER 9 COOLING SYSTEM……………………………………… 41-42 9.1 INTRODUCTION………………………………. 41 9.2 HYDROGEN DRYER………………………… 41 vi
  7. 7. CHAPTER 10 EXCITATION SYSTEM…………………………………. 43-45 10.1 FUNCTION OF EXCITATION SYSTEM…… 43 10.2 TYPES OF EXCITATION SYSTEM………… 43 10.3 STATIC EXCITATION SYSTEM……………. 43 10.4 GENERAL ARRANGEMENT……………….. 44CHAPTER 11 WATER TREATMENT PLANT…………………………. 46- 47 11.1 D.M. PLANT……………………………………… 46 11.2 C.W. PLANT……………………………………… 47 11.3 B.C.W PUMP HOUSE…………………………… 47CHAPTER 12 CONTROL ROOM……………………………………….. 48-50 12.1 MAIN CONTROL ROOM…………………………. 48 12.2 CONTROL PANEL I……………………………… 49 12.3 CONTROL PANEL II…………………………… 49 12.4 CONTROL PANEL III……………………………. 49 12.5 CONTROL PANEL IV……………………………. 50 12.6 CONTROL PANEL V……………………………. 50CHAPTER 13 PROTECTIONS………………………………………. 51 13.1 GENERAL PROTECTION……………………… 51CHAPTER 14 SALIENT FEATURES OF K.S.T.P.S……………………. 52-53 14.1 LOCATION……………………………………….. 52 14.2 CAPACITY………………………………………… 52 14.3 SOURCE OF WATER…………………………….. 52 14.4 BOILER……………………………………………. 52 14.5 FUELS……………………………………………… 53CONCLUSIONS ……………………………………….………………………. 54REFERENCES ………………...………………………………………........... 55 vii
  8. 8. CHAPTER -1 INTRODUCTIONFor the power generation with 2x110 MW and 3x210 MW of K.T.P.S. authorities arerequired to be operative to active full operation. The auxiliaries are basically operationeither on L.T. System i.e. 415 V 3 Ø power supply is made available to the system afterproviding the station transformer of 3x50 MVA capacity with voltage 220 KV/ 7.2/7.2 KV &different service transformers of capacity 1.0 MVA, 1.5 MVA, 2.0 MVA, which are locatednear the load centre as the transformer having the voltage of 6.6 KV /415 V. The 6.6 KVpower is distributed through 6.6 KV interconnected Bus System for all the five units with acontrol through DC of 220 V. The 415 V power supply is done through a L.T. SWGR (Switchgear) which arelocated nearby the distribution transformer as well as the load centers. The all in -comers,which are breaker controlled, are having the control the L.T. SWGR are having the controlsystem on 110/ 220 V AC. The 6.6 KV power supply which are either MOCB (Minimum OilCircuit Breaker) of JYOTI MAKE or Air Circuit Breakers. The 6.6 KV power supply to various draining g equipment‟s i.e. more is madethrough breakers which are either MOCB of Jyoti make air circuit breaker which are eitherof voltage makers as well as SF 6 of NGEF make. The LT supply is also controlledthrough air break circuit breaker, which are either L&T make or English Electric Companyof India. The various H.T. motors are switched on / started through on direct ON line(DOL) in order to inverse the availability of equipment at full efficiency without time gap. Further , the 6.6 KV system which is normally in delta configuration and terms as anunearthed system so also to keep the running motor complete in operating condition incase of any one .phase of motor winding is earthed due to any one reason. Earthling isdetected by an protection system with alarm facility to take remedial measuresimmediately and at the same time to maintain the generation level in the same condition,prior to occurring the earth fault the single phase earth fault is detected in due course tillthe motor is not earthed to other or another phase. [1]
  9. 9. “PUBLIC ADDRESS SYSTEM” is available through in area of each unit which helpsin fast communication for prompt remedial measure. Soot Blowers are there in the boiler area on the furnace side or Zone which helps inblowing the soot / ash deposition regularly of the furnace wall / economizer tubes to keepheat transfer at the required parameter. In April 1973, Central Electricity Authority prepared a Project Report for powerstation comprising of the two units of each of capacity 110 MW for RSEB subsequently inSeptember, 1975 this was revised by the Consultant Thermal Design Organization ,Central Electricity Authority for invention of 2x110 MW units being manufactured by BHEL,Hyderabad in 1st Stage. The planning commission cleared the project report in Sept., 1976 for installation oftwo units each of 110 MW in first estimated cost of Rs. 143 Crores.There are total 11 lines coming from KSTPS each having 220V over it. Each line is goingas 1 line Sanganer 1line Herapura 1line Modak gss 2lines Power grid nawta 2lines Byawar 4 lines Sakatpura gss [2]
  10. 10. 1.1 K.S.T.P.S. IS DESISIGNED IN FOLLOWING STAGES:-  STAGE I - 2x110 MW  STAGE II - 2X210 MW  STAGE III - 1X210 MW  STAGE IV - 1X195 MW  STAGE V - 1X195MW Total Power Generation - 1240 MW*1.2 SITE SELECTION CRITERIA1.2.1 LOCATION:- The Kota Thermal Power Station is ideally on the left bank ofChambal River at Up Stream of Kota Barrage. The large expanse of water reached by thebarrage provides an efficient direct circulation of cooling system for the power station. The220 KV GSS is within ½ Kms. from the power station.1.2.2 LAND:- Land measuring approx. 250 hectares was required for the project in 1976,For disposal of ash tank very near to power station is acquired which the ash in slurry formis disposed off through ash and slurry disposal plants.1.2.3 COAL:- Coal India limited owns and operates all the major coal fields in Indiathrough its coal producing subsidiary companies viz. Northern Coal Fields Limited, SouthEastern Coal Fields Limited, Coal India limited is supply coal from its coal mines of coalproducing subsidiaries SECL & NCL to Kota Thermal Power Station through railwaywagons. The average distances of SECL, NCL are 800, 950 Kms. respectively.1.2.4 WATER:- The source of water for power station is reservoir formed by Kota Barrageon the Chambal River. In case of large capacity plants huge quantities of coal and wateris required. The cost of transporting coal and water is particularly high. Therefore, as far [3]
  11. 11. as possible, the plant must be located near the pit rather than at load centre for loadabove 200 MW and 375 MW. The transportation of electrical energy is more economicalas compared to the transportation of coal.1.3 DESIGN FEATURES:-The satisfactory design consists of the flowing steps.  Estimation of cost.  Selection of site.  Capacity of Power Station.  Selection of Boiler & Turbine.  Selection of Condensing Unit.  Selection of Electrical Generator.  Selection of Cooling System.  Design of Control and instrumentation system. The design of steam power station requires wide experience as the subsequentoperation and maintenance are greatly affected by its design. The most efficient designconsist of properly sized component designed to operate safely and conveniently alongwith its auxiliaries and installation. Figure 1.1 VIEW OF KOTA SUPER THERMAL POWER PLANT [4]
  12. 12. CHAPTER -2 General Layout & Basic Idea A control system of station basically works on Rankin Cycle.Steam is produced in Boiler is exported in prime mover and is condensed in condenser tobe fed into the boiler again. In practice of good number of modifications are affected so asto have heat economy and to increase the thermal efficiency of plant. Figure 2.1 Layout of Power PlantThe Kota Thermal Power Station is divided into four main circuits :  Fuel and Ash Circuit.  Air and Gas Circuit.  Feed water and Steam Circuit.  Cooling Water Circuit. [5]
  13. 13. 2.1 Fuel & Ash Circuit:- Fuel from the storage is fed to the boiler through fuel handlingdevice. The fuel used in KSTPS is coal, which on combustion in the boiler produced theash. The quantity of ash produced is approximately 35-40% of coal used. This ash iscollected at the back of the boiler and removed to ash storage tank through ash disposalequipment.2.2 Air and Gas Circuit:- Air from the atmosphere is supplied to the combustion chamber ofBoiler through the action of forced draft fan and induced draft fan. The flue gas gases arefirst pass around the boiler tubes and super heated tubes in the furnace, next through dustcollector (ESP) & then economizer. Finally, they are exhausted to the atmosphere throughfans.2.3 Feed Water and Steam Circuit:- The condensate leaving the condenser is first heatedin low pressure (LP) heaters through extracted steam from the lower pressure extraction ofthe turbine. Then its goes to dearator where extra air and non-condensable gases areremoved from the hot water to avoid pitting / oxidation. From deaerator it goes to boilerfeed pump which increases the pressure of the water. From the BFP it passes throughthe high pressure heaters. A small part of water and steam is lost while passing throughdifferent components therefore water is added in hot well. This water is called the make upwater. Thereafter, feed water enters into the boiler drum through economizer. In boilertubes water circulates because of density difference in lower and higher temperaturesection of the boiler. The wet steam passes through superheated. From superheated itgoes into the HP turbine after expanding in the HP turbine. The low pressure steam calledthe cold reheat steam (CRH) goes to the reheater (boiler). From reheater it goes to IPturbine and then to the LP turbine and then exhausted through the condenser into hot well. [6]
  14. 14. 2.4 Cooling Water Circuit:- A large quantity of cooling water is required to condense thesteam in condenser and marinating low pressure in it. The water is drawn from reservoirand after use it is drained into the river.Figure 2.2 CROSS SECTIONAL VIEW OF FOUR MAJOR PART FORM A POWERPLANT [7]
  15. 15. CHAPTER -3 COAL HANDLING PLANTINTRODUCTION:- It can be called the heart of thermal power plant because it providedthe fuel for combustion in boiler. The coal is brought to the KSTPS through rails there arefourteen tracks in all for transportation of coal through rails. The main coal sources forKSTPS are SECL (South Eastern Coalfields Limited), NCL (Northern Coalfield Limited).Everyday 6 to 7 trains of coal are unloaded at KSTPS. Each train consists of 58 wagonsand each wagons consists of 50 tones of coal. The approximate per day consumption atKSTPS is about 18000 metric tones. It costs approximate 4.5 crores of rupees per dayincluding transportation expenses. The coal is firstly unloaded from wagon by wagontriplers then crushed by crushers and magnetic pulley and pulverized to be transformed tothe boiler. The whole transportation of coal is through conveyor belt operated by 3-ØInduction motor.The coal handling plant can broadly be divided into three sections :-1) Wagon Unloading System.2) Crushing System.3) Conveying System.3.1 WAGON UNLOADING SYSTEM:-3.1.1Wagon Tripler:- It unloads the coal from wagon to hopper. The hopper, which ismade of Iron , is in the form of net so that coal pieces of only equal to and less than 200mm. size pass through it. The bigger ones are broken by the workers with the help ofhammers. From the hopper coal pieces fall on the vibrator. It is a mechanical systemhaving two rollers each at its ends. The rollers roll with the help of a rope moving on pulley operatedby a slip ring induction motor with specification: [8]
  16. 16. Figure 3.1 Wagon TriplerRated Output. : 71 KW.Rated Voltage. : 415 V.Rated Current. : 14.22 Amp.Rated Speed. : 975 rpm.No. of phases. : 3Frequency. : 50 Hz. The four rollers place themselves respectively behind the first andthe last pair of wheels of the wagon. When the motor operates the rollers roll in forwarddirection moving the wagon towards the “Wagon Table”. On the Wagon table a limit isspecified in which wagon to be has kept otherwise the triple would not be achieved. [9]
  17. 17. 3.2 CRUSHING SYSTEM:-3.2.1Crusher House:- It consists of crushers which are used to crush the coal to 20 mm.size. There are mainly two type of crushers working in KSTPS:-Primary Crushers i.e. i) Rail crushers or ii) Rotary breaker.Secondary Crushers. i.e. Ring granulators. Primary Crushers:- Primary crushers are provided in only CHP stage 3 system, whichbreaking of coal in CHO Stage 1 & Stage 2 system is done at wagon tripler hopper jail upto the size (-) 250 mm. Secondary Crusher:-Basically there are four ways to reduce material size : impact attrition , Shearing andCompression. Most of the crushers employ a combination of three crushing methods.Ring granulators crush by compressing accompanied by impact and shearing.The uniquefeature of this granulator is the minimum power required for tone for this type of material tobe crushed compared to that of other type of crushers.3.3 Construction & Operation:- Secondary crushers are ring type granulators crushing at the rate of 550 TPH/ 750 TPH for input size of 250 mm. and output size of 20 mm. The crusher is coupled withmotor and gearbox by fluid coupling.Main parts of granulator like break plates, cages , crushing rings and other internal partsare made of tough manganese (Mn) steel. The rotor consists of four rows of crushing rings each set having 20 Nos. oftoothed rings and 18 Nos. of plain rings. In CHP Stage 1 & 2 having 64 Nos. of ringhammers. These rows are hung on a pair of suspension shaft mounted on rotor discs. Crushers of this type employ the centrifugal force of swingingrings stroking the coal to produce the crushing action. The coal is admitted at the top andthe rings stroke the coal downward. The coal discharges through grating at the bottom. [10]
  18. 18. 3.4 CONVEYING SYSTEM:-3.4.1 Stacker Reclaimer:- The stacker re-claimer unit can stack the material on to the pipe or reclaim thestack filed material and fed on to the main line conveyor. While stacking material is beingfed from the main line conveyor via tripler unit and vibrating feeder on the intermediateconveyor which feds the boom conveyor of the stacker cum reclaimer. During reclaimingthe material dis discharged on to the boom conveyor by the bucket fitted to the bucketwheel body and boom conveyor feeds the material on the main line conveyor running inthe reverse direction.3.5 Conveyor belt Specification of Stacker / Reclaimer:-Belt width. : 1400 mm.Speed. : 2.2 m/second.Schedule of motor : All 3-Ø induction motors.Bucket wheel motor : 90 KW.Boom Conveyor motor : 70 KW.Intermediate Conveyor Motor : 90 KW.Boom Housing Motor : 22 KW.Slewing assembly. : 10 KW.Travel Motor : 7.5 KW.Vibrating Feeder. : 2x6 KW.Total installed power. : 360 KW. [11]
  19. 19. CHAPTER -4 ASH HANDLING PLANTThis plant can be divided into 3 sub plants as follows:-1) Fuel and Ash Plant.2) Air and Gas Plant.3) Ash Disposal and & Dust Collection Plant.4.1 Fuel and ash plant:- Coal is used as combustion material in KTPS, In order to get an efficientutilization of coal mills. The Pulverization also increases the overall efficiency and flexibilityof boilers. However for light up and with stand static load , oil burners are also used. Ashproduced as the result of combustion of coal is connected and removed by ash handlingplant. Ash Handling Plant at KTPS consists of specially designed bottom ash and fly ashin electro static precipitator economizer and air pre-heaters hoppers.4.2 Air & Gas Plant:- Air from atmosphere is supplied to combustion chamber of boiler throughthe action of forced draft fan. In KTPS there are two FD fans and three ID fans availablefor draft system per unit. The air before being supplied to the boiler passes through pre-heater where the flue gases heat it. The pre heating of primary air causes improved andintensified combustion of coal. The flue gases formed due to combustion of coal first passes round theboiler tubes and then it passes through the super heater and then through economizer . Inre-heater the temperature of the steam (CRH) coming from the HP turbines heated withincreasing the number of steps of re-heater the efficiency of cycle also increases. Ineconomizer the heat of flue gases raises the temperature of feed water. Finally the fluegases after passing through the Electro-Static Precipitator is exhausted through chimney. [12]
  20. 20. 4.3 Ash Disposal & Dust Collection Plant:- KSTPS has dry bottom furnace. Ash Handling Plant consists ofespecially designed bottom and fly ash system for two path boiler. The system for bothunits is identical and following description is applied to both the units the watercompounded bottom ash hopper receives the bottom ash from the furnace from where it isstores and discharged through the clinker grinder. Two slurry pumps are provided which iscommon to both units & used to make slurry and further transportation to ash dyke throughpipe line. Dry free fly ash is collected in two number of 31 fly ash hopperswhich are handled by two independent fly ash system. The ash is removed from fly ashhoppers in dry state is carried to the collecting equipment where it is mixed with water andresulting slurry sump is discharged4.4 Utilisation:-Utilisation of coal-ash is always practise than its disposal. There are various methods ofutilisation of coal-ash along with established engineering technologies some of them arementioned below:1. Manufacturing of building materials.2. Making of concrete.3. Manufacturing of pozzuolana cement.4. Road construction etc. In all the above cases financial constraint discourages the entrepreneurs to takeup the work. In view of the environmental impact of disposal, Government may giveattractive subsidy and create marketing facility so that entrepreneurs may come forward touse as their raw material. [13]
  21. 21. Figure 4.1 ASH HANDING PLANT [14]
  22. 22. CHAPTER -5 ELECTRO-STATIC PRECIPITATOR5.1 Scope & Principle of Operation:- For general mankind, today an Eco friendlyindustry is must. As far as air pollution is concerned now a days various flue gases filterare there in service. The choice depends on the size of suspended particle matter. Thesefilters are E.S.P. Fabric filter high efficiency cyclone separations and sitelling room. Fop flyash , where the particle size vary from 0.75 microns to 100 micron use gradually useE.S.P. to purify the flue gases due to its higher efficiency & low running cost etc. In anESP the dust lidder gas is passed through an intense electric field, which causes ionizationof the gases & they changed into ion while traveling towards opposite charged electrodeget deposited as particles and thus dust is electric deposited an electrode creating thefield. It is continuous process.5.2 CONTROLLER:- Now a day micro-processor based intelligent controllers areused to regulate the power fed to the HVR. The controls the firing / ignition angle of thethyristor connected in parallel mode. Input out waves of the controller and HVR are alsoshown above, which clearly indicates that average power fed to ESP field can becontrolled by variation of the firing angle of thyristor. The output of controller with respect to time is also controlled bymicroprocessor, so that ESP operation is smooth and efficient . The chars are as shown: As can be seen in the event of spark between electrode the output ofcontroller is reduced to zero for few millisecond for quenching the spark. Controller alsotakes place care of fault in KVR and gives a trapping and non-trapping alarm as per thenature of fault. [15]
  23. 23. 5.3 HIGH VOLTAGE RECTIFIER TRANSFORMER:- HVR receives the regulated supply from controller. Itsteps up to high voltage rectifier. The D.C. supply is fed to E.S.P. field through its negativebushing. The positive bushing so connected to earth through small resistance which formsa current feed back circuit. A very high resistance column is also connected with negativebushing . It forms the voltage feed back circuit. These two feedback are used in thecontroller for indication and control purpose.5.4 E.S.P. FIELD:- The field consists of emitting and collecting electrodes structure whichare totally isolated from each other and hanging with the top roof of field. The emitting isalso isolated from the roof through the support insulators which are supporting the emittingelectrode frame works and also the supply to these electrodes is fed through supportinsulators. The collecting electrodes are of the shape of flat plates. By several similarplates which the emitting electrodes are of the shape of spring. Strong on the emittingframe work with the help of hooks in both the ends. The ash depositing on these electrode is rapped down by separatewrapping mechanism happens at the bottom of the field. From these hoppers ash isevacuated by ash handling system and dispose to the disposal area. The wrappingsystem is automatically controlled with the help of the programmable metal controller,located in the ESP auxiliaries control panels. [16]
  24. 24. CHAPTER -6 BOILER A boiler (or steam generator) is a closed vessel in which water, underpressure is converted into steam. It is one of the major components of a thermal powerplant. A boiler is always designed to absorb maximum amount of heat released in processof combustion. This is transferred to the boiler by all the three modes of heat transfer i.e.conduction, convection and radiation.6.1 Boilers are classified as:-6.1.1 Fire tube boiler: - In this type the products of combustion pass through the tubeswhich are surrounded by water. These are economical for low pressure only.6.1.2 Water tube boiler:- In this type of boiler water flows inside the tubes and hot gases flowoutside the tubes. These tubes are interconnected to common water channels and tosteam outlet.  The water tube boilers have many advantages over the fire tube boilers  High evaporation capacity due to availability of large heating surface.  Better heat transfer to the mass of water.  Better efficiency of plant owing to rapid and uniform circulation of water in tubes.  Better overall control.  Easy removal of scale from inside the tubes. In KSTPS, Natural circulation, tangentially fired, overhanged type, Water tube boilers are used. Oil burners are provided between coal burnersfor initial start up and flame stabilization. Firstly, light oil (diesel oil) is sprayed for [17]
  25. 25. initialization then heavy oil (high speed diesel oil) is used for stabilization of flame.Pulverized coal is directly fed from the coal mills to the burners at the four corners of thefurnace through coal pipes with the help of heated air coming from PA fan. Four nos. ofball mills of 34MT/hr. capacity each have been installed for each boiler. The pressureinside boiler is -ive so as to minimized the pollution and looses & to prevent the accidentsoutside the boiler. For ensuring safe operation of boilers, furnace safeguard supervisory system (FSSS) of combustion engineering USA designed has beeninstalled. This equipment systematically feed fuel to furnace as per load requireme. TheUV flame scanners installed in each of the four corners of the furnace, scan the flameconditions and in case of unsafe working conditions trip the boiler and consequently theturbine. Turbine - boiler interlocks safe guarding the boiler against possibility furnaceexplosion owing to flame failure.6.2 Furnace: Figure 6.1 furnace [18]
  26. 26. Furnace is primary part of the boiler where the chemical energy availablein the fuel is converted into thermal energy by combustion. Furnace is designed forefficient and complete combustion. Major factors that assist for efficient combustion arethe temperature inside the furnace and turbulance, which causes rapid mixing of fuel andair. In modern boilers, water-cooled furnaces are used.6.3 PULVERISED FUEL SYSTEM:-The boiler fuel firing system is tangentially firing system in which the fuel is introduced fromwind nozzle located in the four corners inside the boiler.The crushed coal from the coal crusher is transferred intothe unit coalbunkers where the coal is stored for feedinginto pulverizing mill through rotary feeder The rotaryfeeders feed the coal to pulverize mill at a definite rate.Then coal burners are employed to fire the pulverizedcoal along with primary air into furnace. These burnersare placed in the corners of the furnace and they sendhorizontal streams of air and fuel tangent to an imaginarycircle in the center of the furnace. Figure 6.2 Pulverised System6.4 Fuel Oil System:- The functional requirement of the fuel burning system is to supply acontrollable and uninterrupted flammable furnace input of fuel and air and to continuouslyignite and burn the fuel as rapidly as it is introduced into the furnace. This system providesefficient conversion of chemical energy of fuel into heat energy. The fuel burning systemshould function such that fuel and air input is ignited continuously and immediately upon itsentry into furnace. The Fuel air (secondary air) provided FD fan, surrounds the fuel nozzles. Sincethis air provides covering for the fuel nozzles so it is called as mantle air. Dampers areprovided so that quantity of air can be modulated. Coal burners distribute the fuel and airevenly in the furnace. [19]
  27. 27. Ignition takes place when the flammable furnace input is heated above the ignitiontemperature. No flammable mixture should be allowed to accumulate in the furnace.Ignition energy is usually supplied in the form of heat. This ignitionenergy is provided by oil guns and by igniters.6.5 Boiler Drum:- The drum is a pressure vessel. Its function is to separate water and steam frommixture (of steam & water) generated in the furnace walls. It provides water storage forpreventing the saturation of tubes. It also houses the equipment needed for purification ofsteam. The steam purification primarily depends on the extent of moisture removal, sincesolids in steam are carried by the moisture associated with it. The drum internals reducethe dissolved solids content of the steam to below the acceptable limit. drum is made up oftwo halves of carbon steel plates having thickness of 133 mm. The top half and bottom half are heated in a plate heating furnace at a very hightemperature and are pressured to form a semi cylindrical shape. The top and bottom semicylinders with hemispherical dished ends are fusion welded to form the boiler drum. Thedrum is provided with stubs for welding all the connecting tubes i.e. down comer stubs,riser tubes stubs and super-heater outlet tube stubs. Boiler drum is located at a height of 53m from ground. The drum is provided withmanholes and manhole covers. Manhole is used for facilitating the maintenance person togo inside the drum for maintenance. [20]
  28. 28. . Figure 6.3 Steam Drum The drum form the part of boiler circulating system i.e. movement of fluid from thedrum to the combustion zone and back to boiler drum. Feed water is supplied to the drumfrom the economizer through feed nozzles. Water from the drum goes to water wallsthrough six down comers.Main parts of boiler drum are:-  Feed pipe  Riser tube  Down comer  Baffle plate  Chemical dosing pipe  Turbo separation  Screen dryer  Drum level gauge [21]
  29. 29. 6.6 Draft System:- The combustion process in a furnace can take place only when it receivesa steady flow of air and has the combustion gases continuously removed. Theoreticallybalanced draft means keeping furnace pressure equal to atmospheric pressure, but inpractice the furnace is kept slightly below atmospheric pressure. It ensures that there is noegress of air or hot gas and ash into boiler house.6.7 Draught Fans:- A fan can be defined as volumetric machine which like pumps moves quantities ofair or gas from one place to another. In doing this it overcomes resistance to flow bysupplying the fluid with the energy necessary for contained motion. The following fans areused in boiler house.6.7.1 Primary air fan (P.A. fan) or Exhauster fan-Pulverized coal is directly fed from coal mills to the burners at the four corners of thefurnace through coal pipes with the help of heated air coming from PA fan. Secondly, thisfan also dries the coal. Usually sized for 1500 RPM due to high pressure.6.7.2 Forced draught fan (F.D. fan):- The combustion process in the furnace can take place only when it receives asteady flow of air. This air is supplied by FD fan. Thus FD fan takes air from atmosphere atambient temperature & so provides additional draught. Its speed varies from 600-1500RPM.6.7.3 Induced draught fan (I.D. fan):- The flue gases coming out of the boiler are passed to the ESP &then dust free gases are discharged up by the chimney to the atmosphere through the IDfan. [22]
  30. 30. 6.8 Economizer:- . Figure 6.4 EconomizerThe flue gases coming out of the boiler carry lot of heat. An economiser extracts a part ofthis heat from the flue gases and uses it for heating the feed water before it enters into thesteam drum. The use of economiser results in saving fuel consumption and higher boilerefficiency but needs extra investment. In an economizer, a large number of small diameterthin walled tubes are placed between two headers. Feed water enters the tubes throughthe other. The flue gases flow outside the tubes.6.9 Air preheaters:- Air preheaters are employed to recover the heat from the flue gasesleaving the economiser and are used to heat the incoming air for combustion. This raisesthe temperature of the furnace gases, improves combustion rates an efficiency and lowersthe stack (chimney) temperature, thus improving the overall efficiency of the boiler.Cooling of flue gases by 20% raises the plant efficiency by 1%. [23]
  31. 31. Figure 6.5 air pre-heater Air preheaters are employed to recover the heat from the flue gases leaving theeconomiser and are used to heat the incoming air for combustion. This raises thetemperature of the furnace gases, improves combustion rates and efficiency and lowersthe stack (chimney) temperature, thus improving the overall efficiency of the boiler.Cooling of flue gases by 20% raises the plant efficiency by 1%. In KSTPS regenerative type of preheater is used. They use a cylindrical rotor madeof corrugated steel plate. The rotor is placed in a drum which is divided into twocompartments, i.e. air compartment (primary air coming from primary air fan andsecondary air for air coming from FD fan with + ive pressure) and flue gases (fromeconomizer with – ive pressure) compartments. To avoid leakage from one compartmentto other seals are provided. The rotor is fixed on an electrical shaft rotating at a speed of 2 to 4 rpm. As therotor rotates the flue gases, are pass through alternatively gas and air zone. The rotorelements are heated by flue gases in their zone and transfer the heat to air when they arein air zone. The air temperature required for drying in the case of coal-fired boiler decidedthe size of the air heaters6.10 Super heater:- Superheated steam is that steam, which contains more heat than the saturatedsteam at the same pressure i.e. it, has been heated above the temperature corresponding [24]
  32. 32. to its pressure. This additional heat provides more energy to the turbine and thus theelectrical power output is more. A superheater is a device which removes the last traces of moisture from thesaturated steam leaving the boiler tubes and also increases its temperature above the saturation temperature.The steam is superheated to the highest economical temperature not only to increase theefficiency but also to have following advantages –  Reduction in requirement of steam quantity for a given output of energy owing to its high internal energy reduces the turbine size.  Superheated steam being dry, turbine blades remain dry so the mechanical resistance to the flow of steam over them is small resulting in high efficiency.  No corrosion and pitting at the turbine blades occur owing to dryness of steam.6.11 Re-heater:- Re-heaters are provided to raise the temperature of the steam from whichpart of energy has already been extracted by HP turbine. This is done so that the steamremains dry as far as possible through the last stage of the turbine. A re-heater can alsobe convection, radiation or combination of both.6.12 Circulation System:- In natural circulation system, water delivered to steam generator from header,which are at a temperature well below the saturation value corresponding to that pressure.After header, it is delivered to economizer, which heated to above the saturationtemperature.From economizer the water enters the drum and thus joins the circulation system throughdown covering water wall tubes. In water wall tubes a part of the water is converted tosteam due to boiler and the mixture flows back to the drum. In the drum, the steam is [25]
  33. 33. separated out through the steam separators and passed to the super heater. After thesuper heater when the steam temperature becomes high and pressure upto 150 Kg./cm 3steam is allowed to enter the turbine to convert potential energy to kinetic energy.6.13 Soot Blower:- The boiler tubes are cleaned with the help of steam by the process called sootblowing. We are well known that a greater no. of tubes are presented inside the boiler.Slowly and slowly the fine ash particles are collected on the tube surface and from a layerthis is called soot. Soot is a thermal insulating material.There are mainly three types of soot blower are used in KSTPS: -  Water wall soot blower  Super heater soot blower  Air pre heater soot blower6.14 TECHNICAL SPECIFICATION OF BOILER1.Type : Direct fired, natural circulation2. No. of Units. : Two.3.Make : BHEL.4.Capacity. : 375 tonnes per hour.5.Steam Pressure. : 139 Kg./Cm26.Efficiency : 86.6 %.7.No. of fans in service. a) ID fans. : 2 Nos. b) FD fans. : 2 Nos. c) PA fans. : 2 Nos. d) Seal Air fan. : 1 No. e) Scanner Air fan. : 1 No. f) Igniter fan. : 1 No. [26]
  34. 34. 8. Steam Temperature : 540oC.9. No. of coal mills in : 3 Nos. service.10. No. of soot blowers : 70 Nos.FUEL :- A) COAL:-Type : Slack Coal.Quantity consumed : 3074 tones per day.Type of handing. : Conveyor.Ash disposal : Wet system.B) OIL:-Type. : HSD and fuel oil.Quantity. : a) HSD – 5520 KL per year. b) Furnace Oil : 28800 KL per year.No. of chimney / stack. : 1 / 2.Height of Chimney. : 180 Meters.Volume of flue Gas/ : 198 M3/ Sec. Air emitted.Temp. of flue gas. : 140oC.ESP : One for each unit.6.15 GENERAL DESCRIPTION:- Boilers are tangentially fired, balance draft,natural circulation , radiant type, dry bottom with direct fired pulverized coal from bowlmills. They are designed for burning low grade coal with high ash content. Oil burners arelocated between coal burners for flame stabilization. Pulverized coal is directly fed fromthe coal mills to the burners at the four corners of the furnace through coal pipes. The [27]
  35. 35. pulverized fuel pipes from the mills to the bunkers are provided with basalt lined bends toreduce erosion and to improve the life of these pipes owing to poor grade of coal there is ahigh percentage of mill rejects. The mill rejects are conveyed in a sluice way to an under-ground tank. From this tank the mixture is taken to an overhead hydro-bin where water isdecanted and the mill reject are disposed off by trucking. ESP with collection efficiency of99.8% have been provided to reduce environmental pollution and to minimize induce draftfan wear. A multi-flue reinforced concrete stack with two internal flues has been provided. Two boiler feed pumps each of 100 % capacity are driven by AC motor throughhyd. coupling with scoop tube arrangement for regulating feed water pressure for eachunit. The air required for combustion is supplied by two forced draft fans.Due to anticipated high abrasion of ID fans impellers. Three ID fans each of 60% capacityhave been provided one ID fan to serve as standby. For ensuring safe operation of boilers, furnace safe guard supervisory system(FSSS) of combustion engineering USA designed has been installed. This equipmentsystematically feed fuel to furnace as per load requirement. The UV flame scanners installed at two elevation in each of the four corners of thefurnace, scan the flame conditions and in case of unsafe working conditions but out fueland trip the boiler and consequently the turbine. Turbine – boiler interlocks safe guardingthe boiler against possibility furnace explosion owing to flame failure. Facilities have been provided to simultaneously unload and transfer 10 light oil and40 heavy oil tankers to the designated tanks. Oil preheating arrangement is provided onthe tanks floors for the heavy oil tanks. Superheated steam temperature is controlled byattemperation. Re-heater steam temperature is primarily by tilting fuel burners through + 30 o andfurther control if necessary is done by attemperation. [28]
  36. 36. CHAPTER - 7 STEAM TURBINEINTRODUCTION:- Turbine is a machine in which a shaft is rotated steadily by impact orreaction of current or stream of working substance (steam, air, water, gases etc) uponblades of a wheel. It converts the potential or kinetic energy of the working substance intomechanical power by virtue of dynamic action of working substance. When the workingsubstance is steam it is called the steam turbine. Figure 7.1 steam turbine [29]
  37. 37. 7.1 PRINCIPAL OF OPERATION OF STEAM TURBINE:- Working of the steam turbine depends wholly upon the dynamic action of Steam.The steam is caused to fall in pressure in a passage of nozzle: doe to this fall in pressure acertain amount of heat energy is converted into mechanical kinetic energy and the steam isset moving with a greater velocity. The rapidly moving particles of steam, enter the movingpart of the turbine and here suffer a change in direction of motion which gives rose tochange of momentum and therefore to a force. This constitutes the driving force of themachine. The processor of expansion and direction changing may occur once or a numberof times in succession and may be carried out with difference of detail. The passage ofsteam through moving part of the commonly called the blade, may take place in such amanner that the pressure at the outlet side of the blade is equal to that at the inlet inside.Such a turbine is broadly termed as impulse turbine. On the other hand the pressure of thesteam at outlet from the moving blade may be less than that at the inlet side of theblades; the drop in pressure suffered by the steam during its flow through the movingcauses a further generation of kinetic energy within the blades and adds to the propellingforce which is applied to the turbine rotor. Such a turbine is broadly termed as impulsereaction turbine. The majority of the steam turbine have, therefore two important elements, or Sets of such elements . These are (1) the nozzle in which the system expands from high pressure end a state of comparative rest to a lower pressure end a status of comparatively rapid motion. The blade or deflector , in which the steam particles changes its directions and hence its momentum changes . The blades are attach to the rotating elements are attached to the stationary part of the turbine which is usually termed the stator, casing or cylinder. Although the fundamental principles on which all steam turbine operate the same, yet the methods where by these principles carried into effect very end as a result, certain types of turbine have come into existence. 1. Simple impulse steam turbine. 2. The pressure compounded impulse turbine. 3. Simple velocity compounded impulse turbine. [30]
  38. 38. 4. Pressure-velocity compounded turbine. 5. Pure reaction turbine. 6. Impulse reaction turbine.7.2 Description of Steam Turbines:-7.2.1 Steam flow:- 210 MW steam turbine is a tandem compound machine with HP, IP & LP parts. TheHP part is single flow cylinder and HP & LP parts are double flow cylinders. The individualturbine rotors and generator rotor are rigidly coupled. The HP cylinder has a throttlecontrol. Main steam is admitted before blending by two combined main stop and controlvalves. The HP turbine exhaust (CRH) leading to reheated have tow swing check valvesthat prevent back flow of hot steam from reheated, into HP turbine. The steam comingfrom reheated called HRH is passed to turbine via two combined stop and control valves.The IP turbine exhausts directly goes to LP turbine by cross ground pipes.7.2.2 HP Turbine:- The HP casing is a barrel type casing without axial joint. Because of its rotationsymmetry the barrel type casing remain constant in shape and leak proof during quickchange in temperature. The inner casing too is cylinder in shape as horizontal joint flangeare relieved by higher pressure arising outside and this can kept small. Due to this reasonbarrel type casing are especially suitable for quick start up and loading.The HP turbineconsists of 25 reaction stages. The moving and stationary blades are inserted intoappropriately shapes into inner casing and the shaft to reduce leakage losses at bladetips.7.2.3 IP Turbine:- The IP part of turbine is of double flow construction. The casing of IP turbine is splithorizontally and is of double shell construction. The double flow inner casing is supportedkinematically in the outer casing. The steam from HP turbine after reheating enters theinner casing from above and below through two inlet nozzles. The centre flowscompensates the axial thrust and prevent steam inlet temperature affecting brackets, [31]
  39. 39. bearing etc. The arrangements of inner casing confines high steam inlet condition toadmission branch of casing, while the joints of outer casing is subjected only to lowerpressure and temperature at the exhaust of inner casing. The pressure in outer casingrelieves the joint of inner casing so that this joint is to be sealed only against resultingdifferential pressure. The IP turbine consists of 20 reaction stages per flow. The moving andstationary blades are inserted in appropriately shaped grooves in shaft and innercasing.7.2.4 LP Turbine:- The casing of double flow type LP turbine is of three shell design. The shells areaxially split and have rigidly welded construction. The outer casing consist of the front andrear walls , the lateral longitudinal support bearing and upper part. The outer casing is supported by the ends of longitudinal beams on the base platesof foundation. The double flow inner casing consist of outer shell and inner shell. Theinner shell is attached to outer shell with provision of free thermal movement. Steam admitted to LP turbine from IP turbine flows into the inner casing from bothsides through steam inlet nozzles. [32]
  40. 40. CHAPTER – 8 TURBO GENERATOR8.1.1 THEORY TURBO GENERATOR manufactured by B.H.E.L. and incorporated with mostmodern design concepts and constructional features, which ensures reliability, withconstructional & operational economy. The generator stator is a tight construction, supporting & enclosing the statorwindings, core and hydrogen coolers. Cooling medium hydrogen is contained within frame& circulated by fans mounted at either ends of rotor. The generator is driven by directlycoupled steam turbine at a speed of 3000 r.p.m. the Generator is designed for continuousoperation at the rated output. Temperature detectors and other devices installed orconnected within then machine, permit the windings, teeth core & hydrogen temperature,pressure & purity in machine under the conditions. The source of excitation of rotorwindings is thyristor controlled D.C. supply. The auxiliary equipment‟s supplied with themachine suppresses and enables the control of hydrogen pressure and purity, shaft sealinglubricating oils. There is a provision for cooling water in order to maintain a constanttemperature of coolant (hydrogen) which controls the temperature of windings.8.1.2 STATOR FRAME The stator frame of welded steel frame construction, which gives sufficient &necessary rigidity to minimize the vibrations and to withstand the thermal gas pressure.Heavy end shields enclose the ends of frame and form mounting of generator bearings andradial shaft seals. Ribs subdivide the frame and axial members to form duct from which thecooling gas to & fro radial ducts in the core and is re-circulated through internally mountedcoolers. All the gas ducts are designed so as to secure the balanced flow of hydrogen to allparts of the core. The stator constructed in a single piece houses the core and windings.The horizontally mounted water cooled gas coolers being so arranged that it may be [33]
  41. 41. cleaned on the water side without opening the machine to atmosphere. All welded jointsexposed to hydrogen are specially made to prevent leakage. The complete frame issubjected to hydraulic test at a pressure of 7 ATA.8.1.3 STATOR CORE It is built up of special sheet laminations and whose assembly is supported by aspecial guide bass. The method of construction ensures that the core is firmly supported ata large number of points on its periphery. The laminations of high quality silicon steel whichcombines high permeability with low hysteresis and eddy current losses. After stampingeach lamination is varnished on both sides with two coats. The segment of insulatingmaterial is inserted at frequent intervals to provide additional insulation. The laminationsare stamped out with accurately fine combination of ties. Laminations are assembled onguide bass of group separated by radial ducts to provide ventilation passage. Theventilation ducts are disposed so as to distribute the gas evenly over the core & inparticularly to give adequate supports to the teeth. At frequent intervals during stacking theassembled laminations are passed together in powerful hydraulic press to ensure tight corewhich is finally kept between heavy clamping plates which are non-magnetic steel. Use ofnon-magnetic steel reduces considerably by heating of end iron clamping. The footedregion of the core is provided by pressing figures of non-magnetic steel, which are weldedto the inner periphery of the clamping plates. In order to reduce the losses in the endspackets special dampers are provided at either ends of core. Mostly dampers are providedto prevent hunting in ac machines.8.1.4 STATOR BARS Stator bars are manufactured as half bars. Each stator half coil is composed ofdouble glass cover and bars of copper transposed in straight portion of “Robill Method” sothat each strip occupies every radial portion in the bar. For an equal length along the bar.They are made in strips to reduce skin effect. The winding overhead is in volute shape. Theoverhung portion of the bar is divided into four quadrants & insulated. The arrangementreduces additional losses due to damping currents which otherwise be present due to self-induced non-uniform flux distribution in the coil slots. The main distribution for the barconsists of resin rich mica loosed thermosetting epoxy. This has excellent mechanical andelectrical properties & does not require any impregnation. Its moisture absorbing tendency [34]
  42. 42. is very low and behavior of mica is for superior than any other conventional tape insulationsystem. Semi-conductor coating is also applied to a part of overhung with a straight overlapof conductive coil in the sides to reduce eddy currents to minimum. Conductor material iselectrolytic copper connections brazed with free coating silver alloy to obtain joints, whichare both electrically & mechanically sound.8.1.5 STATOR WINDINGS Stator windings are double star layers, lap wound, three phase, and short pitch type.The top & bottom are brazed and insulated at either end to form turns. Several such turnsform a phase. Phases are connected to form a double star winding. The end of windingform involutes shape ends, inclined towards machine axis by 20 o, thus form a basketwinding with total induced conical angle of 400 . Due to this stray load losses in the statorends to zero. The arrangement of complete stator winding electrical circuit is viewed fromturbine end of generator & rotor windings. Slot numbering is clockwise from turbine end. Athick line identifies the top bar in slot No.1. End windings will be sealed against movementof short circuit by both axial & peripheral bracing. The later consists of hardened glasslaminated blocks inserted between adjacent coil sides in coil overhangs, so that with thecoils, they form a continuous rigid ring. Glass cord or top is used lashing the packing ofblocks. The complete assembly is secured b y high tensile brass blots. The winding isdesigned to withstand short circuit stresses. The exposed portion of windings is finallycoated. Insulation of individual bars & stator windings at various stresses is tested withapplied high voltages of AC of Hz.8.1.6 TERMINAL BUSHINGS Six output leads (3 long, 3 short) have been brought out of the coming on the exciterside. External connections are to be made to the three shorter terminals, which are phaseterminals. The large terminals are of neutral & current transformer is inserted. Theconductor of Generator terminal bushing having hollow copper tubes with Copper brazed atthe ends to avoid leakage of hydrogen. Hollow portions enable bushings to be hydrogencooled. Ends of bushings are Silver-plated: middle portion of the bushing is adequatelyinsulated & has a circular flange for bolting the stator casing. Gaskets are providedbetween the Flange of terminal bushings and castings to make it absolutely gas tight. [35]
  43. 43. 8.1.7 BEARINGS Generator bearings have electrical seats of consists of steel bodies with removablesteel pads. The bearings are formed for forced lubrication of oil at a pressure of 2-3 ATM/from the same pump that supplies oils to the turbine, bearings & governing gears. There isa provision to ensure & measure the rotor bearing temperature by inserting a resistancethermometer in the oil pockets.8.1.8 VENTILATION SYSTEM The machine is designed with ventilation system having 2 ATM rated hydrogenpressure. Two axial fans mounted on either side of the rotor to ensure circulation ofhydrogen. The stator is designed for radial ventilation by stem. The end stator core packets& core clamping & plates are intensively cooled by Hydrogen through special ventilationsystem. Design of special ventilation is so as to ensure almost uniform temperature of rotorwindings and stator core. Rated load operating temperature is well within the limitscorresponding to the Class B operation. Embedded Resistance Temperature Detectors docontinuous monitoring of Hydrogen temperature at active parts of Generator.8.1.9 RESISTANCE TEMPERATURE DETECTORS (R.T.D.) An R.T.D. is a point resistance element. Operation of R.T.D. depends on the principalthat electrical resistance of metallic conductor varies linearly with temperature.8.1.10 APPLICATIONS RTD & its associated equipments are designed for use with Generator to determinetemperature at various parts & places. The equipment‟s consists of two parts:-1. Switch Board Equipment: is usually includes a temperature indicating meter, testresistor transfer switch & leads.2. Machine Equipment: is usually includes temperature R.T.D.leads and terminal blockswith grounding connections. [36]
  44. 44. Leads from RTD are brought out to the terminal board by cables through conduits to protectthem from physical damage and from contact with high voltage coils. Some RTDs are instator teeth with 7 spacers, 7 RTDs between the coil sides in stator slots with 7 spacers and3 RTDs are there in the stator core with spacers. The location of RTDs is in three phase‟si.e. in the centre of machine, in each region of machine and midway between them. Thedetectors in the stator slots are distributed uniformly in all three phases. Measurement oftemperature of Hydrogen cooling water for Hydrogen coolers & metals is as:Six RTDs are provided at the inlets of each of six individual Hydrogen cooler elements formeasurement of temperature of Hydrogen, similarly Six RTDs are provided at the outletsalso. One RTD along-with one spacer is provided in the lower part of stator frame formeasurement & signalization of hot Hydrogen. Six RTDs are provided at outlets of each ofsix individual Hydrogen Cooler elements for measurement of temperature of cooling waterat the outlet.8.1.11 MEASUREMENT OF BEARING TEMPERATURETwo RTDs are provided in the shelves of Turbo-Generator for measurement ofsignalization of the bearing metal cap. All the terminals of RTDs are brought out to acommon terminal board located on the stator frame.8.1.12 HYDROGEN COOLERS Three Hydrogen Coolers each comprising of two individual units are mounted insidethe stator frame. The inlet and outlet of cooling water from both of machine i.e. from non-driving side as well as turbine side. The Clearing of the individual cooler element can becarried out from both ends of the Generator even during operation. The assembly ofindividual cooler elements in stator frame is however carried out only from the non-drivingside.8.2 ROTOR Rotor shaft consists of single piece alloy steel forging of high mechanical andmagnetic properties performance test includes :-1. Tensile test on specimen piece. [37]
  45. 45. 2. Surface examination.3. Sulfur prist tests.4. Magnetic crack detection.5. Visual examination of bore.6. Ultrasonic examination.Slots are milled on the rotor gorging to receive the rotor winding. Transverse slotsmachined in the pole faces of the rotor to equalize the moment of inertia in direct andquadrilateral axis of rotor with a view minimizing the double frequency.8.2.1 VIBRATION OF ROTOR The fully brazed rotor is dynamically balanced and subject to 120 % over speed testat the work balancing tunnel so as to ensure reliable operation.8.2.2 ROTOR WINDINGS Rotor winding is of direct coil type and consists of parallel strips of very highconductivity Silver Bearing Copper, bent on edge to form coil. The coils are placed inimpregnated glass, laminated short shells; using glass strips inter turn insulation and will bebrazed at the end to form continuous winding. The complete winging will be packed at hightemperature and pressed to size by heavy steel damping rings. When the windings havecooled, heavy dove tail wedges of non-magnetic materials will seal the insulation at the topof slot portion. The cooling medium hydrogen gas will be brought in direct contact withcopper by means of radial slots in embedded portion. Treated glass spacers insertedbetween the coils and solid ring prevent lateral movement of coil overhang. The formationand description of glass spacer is such as to leave ample space for ventilation.8.2.3 BEARINGS The bearings are self-aligned & consist of slip steel shells linked with special bearingmetal having very low coefficient of friction. The bore is machined on an elliptical shape soas to increase the mechanical stability of the rotor. The bearings are pressure lubricated [38]
  46. 46. from the turbine oil supply. Special precautions are taken to prevent oil & oil vapor fromshaft seals and bearing along the shaft. The circulation of shaft current is liable to damage.The bearing surface is protected by insulation so placed that the bearings, seals &necessary pipes are inclined from the frame.8.2.4 SLIP RINGS The slip rings are made of forged steel. They are located at either side of GeneratorShaft. The slip ring towards the exciter side is given +ve polarity initially. They have helicalgrooves and skewed holes in the body for cooling purpose by air. Calibrated mica is firstbuilt up to required thickness on the shaft where slip rings are located. The slip rings areinsulated from the rotor shaft. Excitation current is supplied to the rotor winding. Throughthe slip rings, which are connected to the winding. On one end and to the slip ring on theother end with insulated (terminal) studs passing „though‟ the radial holes in the rotor shaft.The terminal studs at both the ends of excitation leads are fitted gas cat seals to preventleakage.8.2.5 BUSH GEAR ASEMBLY Generator bushes are made from the various compositions of natural graphite andbinding material. They have a low coefficient of friction and are self lubricating. Thebrushes are provided with a double flexible copper or pigtails. A helical spring is mountedrapidly over each bush so that pressure is applied on the centerline of bush. A metal cap isriveted to the brass bead and is provided with a hole to maintain the position of the springplug. Several brush holder, each carrying on brush in radial position are fixed to a silverplated copper studs mounted on the collecting arm concentric with each slip rings. Thecollecting arm is made out of a copper strip.8.2.6 DRYING OF WINDING Generator stator bars are insulated with mica insulation, which is homogeneous innature and practically impervious to moisture, and reduce time required to draught. Theinsulation resistance of the stator phase winging against earth and with reference to otherphases under hot condition shall not be less than the value obtained automatically. [39]
  47. 47. Rin = µ/(s/100+1000) m 52U = rated winding Voltage under test.Rin = insulation resistance under hot conditions Rated o/p of turbo generator.The insulation resistance of entire excitation system circuit. In hot condition must not fallbelow 0.5 m 52. The insulation resistance in calculated as per the formula:Rin = Rv (U1 +U2) / (U-1)Rin = Insulation resistance of exciter ()Rv = Internal resistance of voltmeter ()U1 = Voltage measured btw. Slip ring & shaft/ earth (volts).When starting the drying process, the winding insulation resistance will usually decreasewhen the drying process becomes effective; the insulation will gradually increase. Figure 8.1 CROSS SECTIONAL VIEW OF TURBO GENERATOR [40]
  48. 48. CHAPTER – 9 COOLING SYSTEM9.1 INTRODUCTION:- In KSTPS hydrogen cooling system is employed for generatorcooling. Hydrogen is used for cooling medium primarily because of its superior coolingproperties & low density. Thermal conductivity of hydrogen 7.3 times of air. It also hashigher transfer co-efficient . Its ability to transfer heat through forced convection is about75% better than air. Density of hydrogen is approx. 7/14 of the air at a given temperatureand pressure. This reduces the wind age losses in high speed machine like turbo-generator. Increasing the hydrogen pressure the machine improve its capacity to absorb& remote heat. Relative cooling properties of air and hydrogen are given below :-1) Elimination of fire risk because hydrogen will not support combustion.2) Corona discharge is not harmful to insula. since oxidation is not possible.3) Smooth operation of machine in view of vertical elimination of wind age noise & the use of heavy gas light enclosure and dirty probe casing. At pressure 0.035 atm. of hydrogen heat carrying capacity is 1. But at2.0atm. of hydrogen heat carrying capacity is 1.95 to overcome the serious possibility ofhydrogen explosion with in the machine and to ensure the safety of operation purity ofhydrogen on the generator. Casing must be maintained as high as possible. The purity ofhydrogen should be 98% above but should not be less than 98% . In case of hydrogenpurity drops below 98% an alarm is provided.9.2 HYDROGEN DRYERS:- Two nos. of dryers are provided to absorb the hydrogen in theGenerator. Moisture in this gas is absorbed by silica gel in the dryer as the absorbed gaspasses through it. The satural of silica gel is indicated by change in its color from blue topink. The silica gel is reactivated by heating. By suitable change over from drier to theother on un-interrupted drying isachieve. [41]
  49. 49. Fig : 9.1 HYDROGEN COOLED ALTERNATOR [42]
  50. 50. CHAPTER - 10 EXCITATION SYSTEM The electric power Generators requires direct current excited magnets for its fieldsystem. The excitation system must be reliable, stable in operation and must responsequickly to excitation current requirements. When excitation system response is controlledby fast acting regulators, it is chiefly dependent on exciter. Exciter supply is given fromtransformer and then rectified.10.1 Function of excitation system:- The main function of excitation system is to supply requiredexcitation current at rated load condition of turbo Generator. It should be able to adjust thefield current of the Generator, either by normal controller automatic control so that for alloperation & between no load and rated load. The terminal voltage of the system machineis maintained at its value. The excitation system makes contribution improving powersystem stability steady state condition. The excitation system that are commonly termedquick response system and have following principal feature :- Exciter of quick response &high voltage of not less than 1.4 times the rated filed voltage and nominal exciter responseof minimum Type of Excitation System:-There have been many developments in excitation system design. There has been continuing reachmakes turbo-generator I. Conventional DC excitation system. Brushes excitation system.10.3 STATIC EXCITATION SYSTEM :- In KSTPS static excitation system is provided it mainly consists of the following:-1) Rectifier transformer.2) Nos. of thyristor converters.3) An automatic voltage regulator (AVR).4) Field suppression equipment. [43]
  51. 51. 5) Field flashing equipment.10.4 GENERAL ARRANGEMENT:- In the excitation system the power required for excitation ofGeneration are tapped from 11 KV bus ducts through a step down rectifier transformer.After rectification in thermistor, converter, the DC power is fed to the Generator fieldwinding through a field breaker. The AVR control the o/p from thyristor converter byadjusting the firing angle depending upon Generator voltages. The field flashing systemfacilitates initial built up of the Generator voltage from the static AC or DC supply.10.4.1 RECTIFIER TRANSFORMER :- This transformer steps down the bus voltage 11 KV to 640 V and has arating of 1360 KVA. It is dry type, it is however provided with current relays and twotemperature sensors.10.4.2 A THYRISTOR CONVERTOR :- The thyristor panel and are intended for controlledrectification of AC Input power. 6. Thyristor converter are connected in parallel each ratesfor continuous current o/p of 20 % of the rated capacity i.e. 20 % reserve. Each thyristorconverter consists of 6 thyristor connected in 3-3 , full wave, 6-pulse bridge from and theyare cooled by fans provided with a fuse for protection against short circuit.10.4.3 AUTOMATIC VOLTAGE CONTROLS :- The AVR is transistorized thyristor controlled equipmentwith very fast response. The AVR is also having provision of stator and rotor currentslimits and load angle limits for optimum utilization of lagging and leading reactivecapacities of generator.10.4.4 FIELD SUPRESSION EQUIPMENT:-The field equipment consists of a field breaker with discharge resistors. The field breakershave 4 main breaking contacts and two discharge contacts, which close before maincontact break.(a) A very fast response.(b) Extremely reliable in view of static components. [44]
  52. 52. (c) Low maintenance cost.(d) High efficiency.(e) Fast field suppression through field and discharge resistance as well as through Thyristor Bridge, feeding the Generator field.10.5 OPERATION:- After bringing the speed to operation speed say 3000 r.p.m. , the voltageis slowly built up with the help of excitation system. This action is taken for synchronizingthe Generator.10.5.1 SYNCHRONIZING:- For synchronizing the Generator to the grid system 5 condition of equalityhave to be satisfied. These are (I)_Voltage (II) Frequency (III) Phase displacement (IV)Phase sequence (V) Wave form. Wave form and phase sequence of the Generator aredetermined at the design of each connection SYNCHRONIZING of the generator . [45]
  53. 53. CHAPTER – 11 WATER TREATMENT PLANT The principle problem in high pressure boiler is to control corrosionand steam quality. Internal corrosion costs power station crores of rupees in repair withoutstrict control impurities in steam also form deposit over turbine blades and nozzles. Theimpurities present in water are as follows :-1) Un-dissolved and suspended solid materials.2) Dissolved slats and minerals.3) Dissolved gases4) Other minerals ( oil, acid etc.).5). a) Turbidity & Sediment. b) Silica. c) Micro Biological. d) Sodium & Potassium Salt. e) Dissolved Sales Minerals.6). a) O2gas. b) CO2 gas.11.1 D.M. PLANT:- In this plant process water is fed from all these dissolved salts.Equipment for demineralization cum softening plant is supplied and erected by M/s.Wanson (India) Ld., Pune. This plant consists of two streams each stream with activatedcarbon filter, weak acid , cation exchanger and mixed bed exchanger. The filter water toDM plant through 250 dia. header from where a heater top off has been taken to softeningplant. Two filtered water booster pumps are provided on filtered water line for meeting thepressure requirement in DM Plant. Sodium Sulphate solution of required strength is dosedinto different filtered water by mean of dosing pump to neutralize chlorine prior to activatedcarbon filter. When water passed an activated carbon filter will remove residual chlorine [46]
  54. 54. from water. Provision is made for back washing the activated carbon filter. Whenpressure drop across filter exceeds a prescribed limit from the activated carbon filter theworks acid cation unit. The deception water the weak base anion exchanger unit waterthen enters de-gasified unit where free CO2 is scrubbed out of water by upward counterflow of low pr. air flow through degasified lower and degassed water is pumped to strongbase exchanger ( anion exchanger). Arrangement for dosing ammonia solution into de-mineralized water after mixedbed unit has been provided p+1 correction before water is taken in de-condensate transferpump the DM water to unit condensor as make up.11.2 C.W. PLANT:- Circulating water pump house has pumps for condensing thesteam for condensor. Five pumps are used for condensing Unit No.1 & 2 and aftercondensing this water is discharged back into the river. Each pump has capacity of 8275M3/Hr, and develop pressure about 1.94 Kg./Cm2.Three seal water pump are used forsealing circulating water pump shaft at pr. 4.5 kg./cm2. Two pump for unit 1 & 2 with one stand by is used for supplying raw water tochlrofied chemical dosing is tone between and chlorified water is taken through main line.From main line water passes through filter bed to filter the water. Chlorified water ispumped to 42 m elevation by two pumps of capacity 270 M 3/Inch at discharge pressure of6.9 Kg./Cm2. At 42 M elevation the water is stored in tank and used for cooling the oilcoolers and returned back to river. Oil coolers are situated on ground and there are no. oftress for each unit.11.3 B.C.W. PUMP HOUSE:- Filter water after demineralization is used for bearingcooling from BCW pump house after passing through strainer and heat exchanger it entersat 30-32oC and leave exchanger at 38oC. The raw water used in ash handling plant andremaining quantity is stored in sumps of BCW Pump House. From here the water ispumped to CW Pump by TWS (Traveling water screens) pumps are run by motors of 90KW and has a capacity of 240 Cum/hr/pump at pressure of 5 kg/cm 2. BCW here stand forwater used for cooling oil used for cooling the bearing. In CW pump house water isdischarged from nozzle and impinged for traveling water screens for cleaning it. [47]
  55. 55. CHAPTER 12 CONTROL ROOM12.1 MAIN CONTROL ROOM In control room various controls are provided simultaneously various measurementare made various relays are provided here. Instrumentation Limited Kota is major supplierof apparatus. There is one unit control from which two adjacent unit of 110 MW each can becontrolled. In addition are local panels at the boilers, turbo sets and boiler feed pumps.The operation of unit is basically controlled from unit control room. The operation of various rents and chain are done locally as per requirement. Theunit control room has a set of parameters panel for indicating or recording parameter ofboilers or turbo sets. The parameters recorded in control room included per pr. and temp. of line steam,reheat steam , feed water, fuel oil flow, mill outlet temp. ,mill differential , turbine speed,control valve operation, turbine shaft , axial shaft , back pressure in condenser , metaltemperature etc. There is a data logger to ensure accurate lagging of essential data. The VCB also control panel for one generator and contains exciter synchronizingarrangement. The unit control room also houses most of electronic regulator, relay,recorders and other devices in near side of room. The scheme of control and instruction is provided to control the parameters andsafe operation of equipment. Automatic control is provided for combustion for feed waterregulation and reheat temp. The combustion control is designed to inlet maintain thedesired steam pressure at turbine only variation thereof utilized to very fuel input to theboiler w.r.t. steam pressure. Ratio steam flow maintained automatically. The feed water regulation is based on impulses from drum level, feed water flow toboiler and steam flow for the boiler. [48]
  56. 56. Super heater temp. counted with feed water spray. The furnace draft control of draft fan.The boiler oil system is provided with itself control for ignition control and also providedwith safety interlock to prevent operation under low oil pressure and temperature.12.2 CONTROL PANEL I12.2.1 FAN CONTROL DESK a) Induced draft fan ( 3 Nos.) at full load and 2 Induce Draft Fans Run. b) Forced draft fan ( 2 Nos.). c) Primary Air Fan (3 Nos.) at full load. d) Furnace Pressure (- 5 to 10 wcl). e) Primary Air Header Pressure (750-800 mm. level wcl.) f) FO Wind box pressure or wind box differential pressure.12.3 CONTROL PANEL II12.3.1 FUEL CONTROL DESK a) Coal, oil flow. b) Oil pressure. c) Temp. of mill (inlet & outlet). d) Flow of air. e) Differential Pressure of mill.12.4 CONTROL PANEL III12.4.1 STEAM & WATER DESK a) Drum Level Control [49]
  57. 57. b) Flow of steam & water. c) Pressure of Steam & Water. d) Temp. of steam and water.12.5 CONTROL PANEL IV12.5.1 TURBINE DESK a) Pressure Control. b) Load Control. c) Speed Control. d) Effectors, Control Values, Stop Values, Deaerators.12.6 CONTROL PANEL V12.6.1GENRATOR CONTROL PANEL a) Voltage Current MVAR. b) Stator Rotor Temp. c) For Stator Cooling (a) H2 pressure. b) H2O pressure. Fig : 12.1 control room [50]
  58. 58. CHAPTER -13 PROTECTION1. Field Protection.2. Pole Slipping.3. Plane Overload Protection.4. Inter-turn Fault5. Negative Phase Sequence Protection.6. Reverse Power Protection.7. Forward Power Protection.8. Under Frequency & Over Frequency Protection.9. Generator Voltage Protection.10. Rotor Earth Fault Protection.13.1 General Protection: It is most important electrical equipment of many generating station. Tripping ofeven a generating unit may cause overloading of associated machines and even to systemun-stability . The basis function of protection applied to generator is to reduce voltage tominimum by rapid discrimination clearance of faults. Unlike other apparatus the openingof C.B. to isolate faulty generator is not sufficient to prevent future damage. [51]
  59. 59. CHAPTER -14 SALIENT FEATURE OF K.S.T.P.S.1. LOCATION Sakatpura, Kota.2. CAPACITY A) 1ST Stage. 2x110 MW. B) 2nd Stage. 2x210 MW. C) 3rd Stage. 1x210 MW. D) 4th Stage. 1x195 MW. E) 5th Stage 1x195 MW3. SOURCE OF WATER. Chambal River.4. BOILER a) type. tangentially fired natural circulation, balance draft , direct fired radiant reheat, water tube boiler. b) No. of units. 7 c) Max. efficiency. BHEL (86.6 + 1) % d) Capacity. 375 t/Hr , 710 t/hr (110 MW) / (210 MW) e) Steam Pressure 139 Kg/cm2 / 150 Kg/cm2 f) Steam Temp. 540oC, g) No. of draft fans in i) FD fans 2 Unit ( Each boiler) Service. ii) ID fan 2 Unit ( Each boiler ). h) No. of Air fans in Service. i) Primary 2 Unit. ii)Seal Air fan. 1 Unit. iii) Scanner. 1 Unit. [52]
  60. 60. i) No. of coal mills in service. 3 Unit. j) No. of Soot blower in service. 68 k) No. of oil burners. 85. Fuels:-A) COAL:- i)Type. Stack Coal. ii) Calorific Value. 3300 K.Cal./Kg. iii) Qty. Used. 80 t/hr, 140 t/hr iv) Ash contents. 40% v) Sulphur contents. 0.5%. vi)Type of Handling. Belt Conveyor. [53]
  61. 61. CONCLUSION The first phase of practical training has proved to be quiet fruitful. It provided anopportunity for encounter with such huge machines like wagon tippler .110 MW, 210 MW &195 MW turbines and generators. The architecture of the power plant the way various units are linked and theway working of whole plant is controlled make the student realize that engineering is notjust learning the structured description and working of various machines, but the greaterpart is of planning proper management. It also provides an opportunities to lean low technology used at proper placeand time can cave a lot of labour e.g. wagon Tripler (CHP).But there are few factors thatrequire special mention. Training is not carried out into its tree sprit. It is recommendedthat there should be some project specially meant for students where presence ofauthorities should be ensured. There should be strict monitoring of the performance ofstudents and system of grading be improved on the basis of work done. However training has proved to be quite fruitful. It has allowed an opportunityto get an exposure of the practical implementation to theoretical fundamentals. [54]
  62. 62. REFERENCES http://www.mapsofindia.com/kota/industries/super-thermal-power-plant.html http://en.wikipedia.org/wiki/Thermal_power_station www.geocities.com http://www.energymanagertraining.com/power_plants/ThermalPowerPlants.htmBOOKS Electrical Power by J.B.Gupta Generation of Electrical Power by B.R.Gupta Power System by V.K.Mehta. Power System Design & Analysis by B.R.Gupta Steam & Gas turbines and Power Plant Engineering by R.Yadav [55]