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Ge Combined Cycle
 

Ge Combined Cycle

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GE Combined Cycle

GE Combined Cycle

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    Ge Combined Cycle Ge Combined Cycle Document Transcript

    • g GER-3936A GE Power SystemsAdvancedTechnologyCombined CyclesR.W. SmithP. PolukortC.E. MaslakC.M. JonesB.D. GardinerGE Power SystemsSchenectady, NY
    • Advanced Technology Combined CyclesContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1System Integration Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Steam Turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Shaft Train Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Steam-Cooling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Integrated Control System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Plant Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Integrated Gasification Combined Cycle (IGCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Repowering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15GE Power Systems GER-3936A (05/01) s s i
    • Advanced Technology Combined CyclesGE Power Systems GER-3936A (05/01) s s ii
    • Advanced Technology Combined CyclesIntroduction A diagram of the cycle (Figure 2) shows an overview of the three-pressure, reheat steamThe General Electric H technology combined cycle and its integration with the gas turbinecycles represent the most advanced power gen- cooling system. Gas turbine cooling steam iseration systems available today. These com- supplied from the intermediate pressure (IP)bined-cycle power generation systems can superheater and the high pressure (HP) steamachieve 60% net thermal efficiency burning turbine exhaust to the closed circuit system thatnatural gas. Their environmental impact per cools the gas turbine stage 1 and 2 nozzles andkilowatt-hour is the lowest of all fossil-fired gen- buckets. The cooling system operates in serieseration equipment. These highly efficient com- with the reheater, with gas turbine coolingbined cycles integrate the advanced technology, steam returned to the steam cycle cold reheatclosed-circuit steam-cooled 60 Hz MS7001H line.and 50 Hz MS9001H gas turbines with reliablesteam cycles using state-of-the-art steam tur- Air extracted from the compressor discharge isbines and unfired, multi-pressure, reheat heat cooled using water from the IP economizer.recovery steam generators (HRSGs). The cooled air is readmitted to the gas turbine and compressor to cool compressor wheels andSystem Integration Overview selected turbine gas path components. TheThe STAG 107H and STAG 109H are offered in energy extracted from the compressor dis-a single-shaft combined-cycle configuration. charge air is returned to the steam cycle by gen-Figure 1 is a conceptual presentation of an out- erating IP steam. A fuel gas heating system uti-door power plant with this equipment. This lizes low grade energy from the HRSG toconfiguration complements the cycle integra- improve combined-cycle thermal efficiency.tion between the steam-cooled gas turbine and Water extracted from the discharge of thethe steam bottoming cycle. HRSG IP economizer is supplied to the fuel gas Figure 1. Advanced technology combined-cycle unitGE Power Systems GER-3936A (05/01) s s 1
    • Advanced Technology Combined Cycles Fuel Heat Recovery Fuel Steam Generator Heating System To Stack Cooling Air Cooling System Attemp Filter Feedwater HP IP LP LP Generator Pump Gas Turbine Steam Turbine LEGEND Cooling Deaerating Steam Water Condenser Air Treatment Water Exhaust Filter Air A Fuel Gland Seal Air Filter Condenser B Condensate Pump Condensate Filter Figure 2. STAG 107H/109H cycle diagramheater to pre-heat the fuel gas supplied to the ture effect on performance for the STAG 107Hcombustion system. The water leaving the fuel as well as the part load performance. Theheater is returned to the cycle through the con- graphs in Figure 4 show the ambient tempera-densate receiver to the condenser. ture effect on performance for the STAG 109H as well as the part load performance.Performance The low NOx emissions are achieved by a DryThe rating point thermal and environmental Low NOx (DLN) combustion system. Theperformance is summarized in Table 1 for the closed circuit steam-cooling system also con-advanced technology single-shaft combined- tributes to the low NOx emissions because acycle units burning natural gas fuel. The minimum of air bypasses the combustors forgraphs in Figure 3 show the ambient tempera- cooling the gas turbine hot gas path parts. NOx Thermal Emissions Thermal Discharge Combined-Cycle Net Net Heat Rate (LHV) Efficiency ppmvd at to Cooling Water Unit Power, MW BTU/kWh kJ/kWh (LHV), % 15% O2 BTU/kWh kJ/kWh STAG 107H 400 5,687 6,000 60 <9 1,790 1,888 STAG 109H 480 5,687 6,000 60 < 25 1,790 1,888 Notes: 1. Ambient Air Conditions = 15°C (59°F), 1.0133 barA (14.7 psia), 60% RH 2. Steam Turbine Exhaust Pressure = 0.04064 barA, (1.2 In HgA) 3. Performance is net plant with allowances for equipment and plant auxiliaries with a once-through cooling water system 4. Three-Pressure, Reheat, Heat Recovery Feedwater Heating Steam Cycle Table 1. Advanced technology combined cycle – thermal and environmental performanceGE Power Systems GER-3936A (05/01) s s 2
    • Advanced Technology Combined Cycles 125% 102.5% 170% 120% 102.0% 160% 115% 101.5% 150% Basis: 15°C (59°F) ambient temperature, Heat Rate (Percent of Rated) Heat Rate (Percent of Rated) Output (Percent of Rated) 140% 1.013 BarA (14.7 psia) ambient pressure, 110% 101.0% 60% relative humidity, 0.0508 BarA (1.5" HgA) ST exhaust pressure, 130% 2 x 851mm (33.5") LSB 105% 100.5% Heat Rate 120% 100% 100.0% 110% 95% Power 99.5% Basis: 100% 90% 15°C (59°F) ambient temperature, 99.0% 1.013 BarA (14.7 psia) ambient pressure, 90% 60% relative humidity, 85% 98.5% 0.0508 BarA (1.5" HgA) ST exhaust pressure, 2 x 851mm (33.5") LSB 80% 80% 98.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 100.0% 0 10 20 30 40 50 60 70 80 90 100 110 Power Output (Percent of Rated) Ambient Temperature (°F) Figure 3. S107H ambient temperature effect on performance and part load performance 125% 102.5% 170% 120% 102.0% 160% Basis: 15°C (59°F) ambient temperature, 115% 101.5% 150% 1.013 BarA (14.7 psia) ambient pressure, Heat Rate (Percent of Rated) Heat Rate (Percent of Rated) 60% relative humidity, Output (Percent of Rated) 110% 101.0% 140% 0.0508 BarA (1.5" HgA) ST exhaust pressure, 2 x 851mm (33.5") LSB 105% Heat Rate 100.5% 130% 100% 100.0% 120% 95% Power 99.5% 110% Basis: 90% 99.0% 100% 15°C (59°F) ambient temperature, 1.013 BarA (14.7 psia) ambient pressure, 60% relative humidity, 90% 85% 98.5% 0.0508 BarA (1.5" HgA) ST exhaust pressure, 2 x 851mm (33.5") LSB 80% 98.0% 80% 0 10 20 30 40 50 60 70 80 90 100 110 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 100.0% Ambient Temperature (°F) Power Output (Percent of Rated) Figure 4. S109H ambient temperature effect on performance and part load performance HP Throttle Pressure (psig/Barg) 2400/165 Temperature (°F/°C) 1050/565 Hot Reheat Pressure (psig/Barg) 345/23.8 Temperature (°F/°C) 1050/565 LP Admission Pressure (psig/Barg) 31/2.2 Temperature (°F/°C) 530/277 Exhaust Pressure Pressure (in. HgA/barA) 1.2/0.04064 Table 2. Advanced technology combined-cycle steam conditionsGE Power Systems GER-3936A (05/01) s s 3
    • Advanced Technology Combined CyclesThe low thermal discharge to cooling water specific back pressure conditions expectedresults from the high efficiency and the general requires low-pressure section designs with acharacteristic of combined-cycle systems in broad range of exhaust annulus areas. This iswhich approximately 30% of the unit power achieved by selection of the last stage bucketoutput is produced by the steam cycle. length and the use of both single-flow and dou-Bottoming cycle steam conditions are tabulated ble-flow exhausts. Table 3 summarizes the last-in Table 2 for systems that produce the perform- stage buckets that are applicable for theance shown in Table 1. The combined-cycle sys- advanced technology combined cycle units.tems are also available with 124 barA / (1800 Applications with low condenser pressurePsig) throttle pressure which may more opti- require a steam turbine with a double-flowmally suit systems with lower cost fuel or a mid- exhaust. This two-casing design is similar in con-range duty cycle. figuration and construction to that applied by GE in single-shaft combined-cycle applicationsSteam Turbine with F technology gas turbines. The high and intermediate pressure sections are combined inA wide range of steam turbines are available to one casing connected by a single crossover tosuit specific site, duty and economic require- the center of the double-flow low-pressure sec-ments for both 50 Hz and 60 Hz applications tion.while satisfying all of the combined-cycle inte-gration requirements. Since there are no Operation is with sliding pressure with the con-extractions for feedwater heating and since trol valves wide open. A control stage at thesteam is generated and admitted to the turbine inlet is therefore not required.at three pressures, the flow at the exhaust isapproximately 30% greater than the throttle Shaft Train Configurationflow. The last stage generates up to 15% of the The single-shaft power train is configured withsteam turbine output, so the efficiency of the the gas turbine on one end, the steam turbineturbines last stage and the sizing of the exhaust in the middle and the generator on the otherannulus area are particularly important for all end, as shown in Figure 5. This close coupling ofcombined-cycle applications. The range of site- the steam and gas turbines permits full mechan- Frequency Length Pitch Diameter Exhaust annulus Area for Number of Parallel Flows 1 1 2 2 Hz/RPM mm inches mm inches Sq M Sq Ft Sq M Sq Ft 60/3600 851 33.5 2300 95.5 12.28 132.2 1016 40.0 2540 100.0 8.11 87.3 16.22 174.6 50/3000 851 33.5 2530 99.5 13.51 145.4 1067 42.0 2804 110.4 9.4 101.2 18.80 202.4 Table 3. Last-stage buckets for advanced technology combined-cycle applicationsGE Power Systems GER-3936A (05/01) s s 4
    • Advanced Technology Combined Cycles COL. COL. T C HP LP IP GEN. SINGLEFLOW, SINGLE-FLOW, DOWNEXHAUST DOWNEXHAUST COL. COL. T C HP IP LP GEN. TWO FLOW, TWO FLOW, DOWN EXHAUST EXHAUST DOWN THRUST BEARING THRUST BEARING TIETIE RODS RODS KEY FOR SHAFT POSITION KEY SHAFT FOR POSITION SOLID COUPLING SOLID COUPLING BEARING BEARING Figure 5. S107H and S109H single-shaft STAG equipment configurationical integration as a single prime mover with a Features:single thrust bearing, thus minimizing the over- 1. Steam turbine installed between theall machine length. Use of all solid rotor cou- gas turbine and the “field assembled”plings provides maximum reliability and simpli- hydrogen-cooled generator.fies the control, overspeed protection, and aux-iliary systems. 2. Solid coupling between gas turbine and steam turbine. Direct coupledThe thrust bearing is located in the gas turbine steam turbine shafts and directinlet end bearing housing, which permits inde- coupled steam turbine to generator.pendent operation of the gas turbine for testingin the factory. This location is at the high pres- 3. Single thrust bearing in the gassure end of the steam turbine, which minimizes turbine compressor to fix shaftdifferential expansion and permits use of small position in conjunction with tie rodaxial clearances throughout the HP and IP sec- installation between the steam turbinetions. The steam turbine contribution to the front standard and the gas turbineshaft thrust load is low and in the opposite compressor inlet casing.direction to that of the gas turbine, so that the 4. Steam turbine front standard keyed tothrust bearing is lightly loaded under all oper- foundation.ating conditions. 5. Common lube oil system withA single lubricating oil system with AC- and DC- hydrogen seal oil system. Commonpowered pumps provides oil to all shaft bear- fire-resistant hydraulic oil system.ings and to the generator hydrogen seals.Similarly, a single high-pressure hydraulic fluid 6. Static start (LCI).system is used for all control and protective 7. Turning gear mounted between steamdevices. turbine and generatorGE Power Systems GER-3936A (05/01) s s 5
    • Advanced Technology Combined Cycles 8. Lift oil for gas turbine only. Mechanical Outline, One-Line 9. Gas turbine, steam turbine, generator, Diagram, Device Summary, Piping and gas skid installed on a pedestal Schematics (Lube Oil, Hydraulic). foundation. All other modules (lube The selection of the single shaft as the pre- oil, hydraulic, fuel oil/atomizing air, ferred configuration for the advanced technol- etc.) are installed at lower level. Shaft ogy combined cycles is based on the extensive center line height (approximately experience since its introduction by GE in 1968. 10.2M [33.5 feet] above grade) Table 4 presents the operating experience on 86 determined by gas turbine inlet duct GE single-shaft combined-cycle units with near- location and/or steam turbine ly 18,000 MW of installed capacity. condenser. 10. Single-flow or two-flow down exhaust Steam-Cooling System steam turbine with sliding shell The gas turbine steam cooling system is inte- support on the fixed/keyed front grated with the steam bottoming cycle to reli- standard. ably provide cooling steam at all operating con- 11. Integrated unit control system (GT, ditions. The normal supply of cooling steam is ST, Gen, HRSG & Mechanical from the outlet of the HRSG IP superheater, Auxiliaries). supported as necessary with HP steam turbine 12. Integrated overspeed protection. exhaust. The steam is delivered to the gas tur- bine stationary parts through casing connec- 13. Down generator terminals. tions and to the rotor through a conventional 14. Reheat, three-pressure steam cycle. gland connection. The cooling steam is 15. Integrated drawings - Shaft returned to the steam cycle at the cold reheat No. Rating (MW) Gas Commercial Utility Site Units Unit Plant Turbine Operation Wolverine Electric Michigan, USA 1 21 21 MS5001 1968 City of Ottawa Ottawa, KS, USA 1 11 11 MS3002 1969 City of Clarksdale Clarksdale, MS, USA 1 21 21 MS5001 1972 City of Hutchinson Hutchinson, MN, USA 1 11 11 MS3002 1972 Salt River Projects Santan, AZ, USA 4 72 290 MS7001B 1974 Arizona Public Ser. Phoenix, AZ, USA 3 83 250 MS7001C 1976 Western Farmers Anadarko, OK, USA 3 93 278 MS7001E 1977 Tokyo Electric Futtsu, Japan 14 165 2310 MS9001E 1986 Chubu Electric Yokkiachi, Japan 5 112 560 MS7001E 1988 Chugoku Electric Yanai, Japan 6 125 750 MS7001E 1990 Ministry of Pet. Lama Dien, China 1 50 50 MS6001B 1990 Kyushu Electric Shin-Oita, Japan 5 138 690 MS7001EA 1992 Power Gen Connah’s Quay, UK 4 350 1400 MS9001F 1995 EPON Netherlands 5 350 1400 MS9001FA 1995 Tokyo Electric Yokohama, Japan 8 343 2742 MS9001FA 1997 Chubu Electric Kawagowe, Japan 7 235 1645 MS7001FA 1998 China Light & Power Black Point, Hong Kong 8 340 2720 MS9001FA 1996 Crocket Cogen Calif, USA 1 248 248 MS7001FA 1996 Cogentrix Clark County, WA 1 253 253 MS7001FA 1997 Tokyo Electric Chiba, Japan 4 360 1440 MS9001FA 1999 Boffolora Italy 1 110 110 MS6001FA 1998 Akzo Delesto II, Netherlands 1 360 360 MS9001FA 1999 Great Yarmouth Great Yarmouth, UK 1 407 407 MS9001FA 2001 Total 86 17,967 Table 4. Single-shaft combined-cycle experienceGE Power Systems GER-3936A (05/01) s s 6
    • Advanced Technology Combined Cyclesline. The gas turbine cooling steam return and extraction after the first superheater pass isany HP steam turbine exhaust steam not used used to cool the LP steam turbine from ~70%for gas turbine cooling are reheated in the speed until steam turbine loading is underway.HRSG and admitted to the IP steam turbine. Figure 2 includes a diagram of the three-pres-During unit acceleration to rated speed and sure, reheat HRSG. While the system can beoperation at low load, the gas turbine is cooled configured with either forced or natural circu-by air extracted from the compressor discharge. lation evaporators, Figure 2 shows a system withThe air is filtered prior to supply to the cooling natural circulation evaporators. The HRSG is asystem. The cooling air from the gas turbine typical three-pressure, reheat HRSG that is com-cooling circuit is discharged to the gas turbine monly applied in combined cycles. It includesexhaust. During air-cooled gas turbine opera- the following features to accommodate thetion steam flow is established through the steam steam cooling system:supply system to warm the steam lines and sta- s The reheater size is reduced since partbilize the steam supply conditions prior to of the reheating is performed by theadmission of steam to the gas turbine cooling gas turbine cooling steam system.system. This steam is discharged via thereheater to the condenser through the IP s The reheater is located in the gas pathbypass valve, which is modulated to maintain downstream of the high temperaturethe pressure of the cooling steam above the gas section of the HP superheater. Theturbine compressor discharge pressure to pre- reheater receives steam during allclude gas leakage into the steam cycle. operating modes except at very lowAppropriate shutoff valves isolate the gas tur- loads during startup, prior tobine cooling circuit from the steam cycle while availability of IP steam.it is operating with air cooling. These cooling s HP steam is extracted after the firststeam shutoff valves are included in the trip cir- pass of the HP superheater during lowcuit such that the system is transferred to air load operation to establish gas turbinecooling immediately upon an emergency shut- steam cooled operation before thedown to purge steam from the cooling system. steam turbine is loaded and provideInitial cooling steam supply and line warming cooling steam to the LP steam turbinesteam is supplied from the HRSG. Steam is above ~70% speed.extracted from the HP superheater after the s Control of the HP steam temperaturefirst pass and mixed with steam from the HP is accomplished by a steamsuperheater discharge to supply steam to the attemperation system which bypasses acooling steam system at the required tempera- section of the HP superheater. Thisture. The cooling steam temperature control system eliminates the potential forwill match gas turbine cooling steam supply to dissolved contaminants to enter thethe gas turbine compressor discharge tempera- steam as can occur with attemperationture during transfer from gas turbine air cool- with feedwater. Attemperation steaming to gas turbine steam cooling, which occurs is extracted after it passes through oneprior to steam turbine loading. In addition to pass in the superheater to assure thatproviding start-up cooling steam supply to the it will be dry after the small pressuregas turbine cooling steam circuit, the HP steam drop across the steam control valve.GE Power Systems GER-3936A (05/01) s s 7
    • Advanced Technology Combined CyclesSupply of high purity steam to the gas turbine steam supply to the gas turbine. This device willcooling system is an essential requirement of operate at least 24,000 hours without mainte-the system for efficient long-term plant opera- nance when provided with steam meeting thetion with high availability. Features included in system purity requirements. The upstream sys-the system to accomplish this requirement are: tem design features and associated protective s Reliable condenser leakage detection strategies provide a means of assuring the system with redundant condensate design life of the steam filter. conductivity sensors and automated Figure 6 presents the location of the steam and protection logic. water sampling points within the S107H and s Full flow feedwater filtration. S109H combined-cycle systems. All sampling s All cooling steam is purified by probes and instrumentation (including a sam- evaporation in a steam drum with pling panel) are of high sensitivity and reliable continuous monitoring of drum water design. Steam and water conductivity, pH, and purity. sodium measurements are continuously sam- pled and monitored. Other measurements not s HP steam temperature control by required for plant protection are monitored steam attemperation. intermittently. s Full flow steam filtration. s Application of non-corrosive materials Integrated Control System in piping, filters and equipment The single-shaft combined-cycle unit is con- downstream of the cooling steam shut- trolled by an integrated, computer control sys- off valves. tem that coordinates the gas turbine, steam tur-The steam filter is the final line of defense bine, generator, HRSG and unit auxiliaries toagainst particulate contaminants in the cooling start, stop and operate the unit to meet system Si Si C.A.C. HX Fuel Htg. HX Na Na Si CC CC 1 CC SC HP Steam to IP Steam Steam Turbine, pH LP Steam to to Gas Gas Turbine Steam Turbine Turbine HP LP IP Drum Drum Drum 2 1 1 SC SC SC Si pH pH pH LP Steam Turbine 1 Exhaust CC Steam/Water Sampling and Monitor Panel Dis. Extraction Probes O2 Condenser (Divided Cooling Waterbox) Water DP SC Hotwell 8 extraction probes 2 Filter A SC Filter B Legend: All samples are taken on SC - Specific Conductivity continuous basis CC - Cation Conductivity Note: All HRSG sampling requires Na - Sodium Analyzer cooling and temperature D.Ox - Dissolved Oxygen compensation, minimize time for Si - Silica Analyzer sampling process pH Figure 6. Steam and water sampling schematicGE Power Systems GER-3936A (05/01) s s 8
    • Advanced Technology Combined Cyclespower requirements with input from a control load and daily start service. The high degree ofroom operator or from a remote dispatch area. control integration maximizes automation ofThe architecture for the single-shaft integrated startup, shutdown and normal operations,control system (ICS) for a single unit is shown which reduces plant operating costs.on Figure 7. Figure 8 shows the architecture for Easy to configure color graphic displays providea multiple-unit plant. a common look and feel to both the unit and • All New Microprocessor Design Control Room Remote Dispatch • Triple Modular Redundant Fault Tolerant Plant Data Highway • Remotable I/O • Capability for I/O Expansion Color Log Operator Operator Engineering Display Printer Station Station Workstation Printer Historian • Redundant Control and Plant Data Highways Redundant Unit Data Highway HMI/ • Peer-to-Peer Communications Server Generator Static Steam Turbine Gas Turbine & HRSG & Unit HMI/ • Time Synchronized Unit Controls Excitation Steam Cycle Auxiliary Server Starter & Cooling & Mechanical Control Bypass Steam Protection Auxiliaries Control Control Alarm Printer • Time Coherent System Data HRSG/MA BOP Gas Turbine Generator Equipment Steam Turbine Figure 7. Single-shaft combined-cycle unit integrated control architectureA redundant data highway connects all control plant level control. Windowed displays enablecomponents with the central control room con- the operator to constantly monitor the desiredsoles. Historical archival and retrieval of plant process and simultaneously view detailed pop-data assists performance optimization and up windows to trend equipment operating dataequipment maintenance. Time synchronization or diagnose process problems. An engineeringof all control components provides time coher- workstation enables the operator to configureent, time tagged data for process monitoring, and tune control loops, perform detailed con-historical archival, sequence of events logging, trol and process diagnostics, maintain software,real time trending and comprehensive alarm manage the system configuration and generatemanagement. High speed communication operation reports.interfaces link the plant control to external dis- The ICS is designed with dedicated I/Opatch and control systems. (inputs/outputs) to control the engineeredThe control and protection strategies are inte- equipment packages. In addition, it has the flex-grated between all components of the system. ibility and expandability needed to addressHigh levels of fault tolerance maximize unit additional I/O requirements to satisfy individ-starting and running reliability for both base ual owner requirements. This includes bothGE Power Systems GER-3936A (05/01) s s 9
    • Advanced Technology Combined Cycles Remote Dispatch Control Room Gateway Fault Tolerant Plant Data Highway Bridge Color Log Operator Long Additional Additional Additional Display Printer Station Term Operator Operator Printers Printer Historian Station Station Redundant Unit Data Highway #1 Operator Station Generator Steam Turbine Gas Turbine HRSG & Balance Operator Excitation Static & & Cooling Steam Cycle Of Station & Starter Bypass Control Steam Mechanical Plant Protection Control Auxiliaries Alarm Printer HRSG/MA BOP Gas Turbine Equipment Generator Steam Turbine Redundant Unit Data Highway #2 Operator Station Generator Steam Turbine Gas Turbine HRSG & Balance Operator Excitation Static & & Cooling Steam Cycle Of Station & Starter Bypass Control Steam Mechanical Plant Protection Control Auxiliaries Alarm Printer HRSG/MA BOP Gas Turbine Equipment Generator Steam Turbine Redundant Unit Data Highway #3 Operator Station Generator Steam Turbine Gas Turbine HRSG & Operator Static Balance Excitation & & Cooling Steam Cycle Station Of & Starter Bypass Control Steam Mechanical Plant Protection Control Auxiliaries Alarm Printer HRSG/MA BOP Gas Turbine Equipment Generator Steam Turbine Figure 8. Multiple-unit station control architectureredundant and non-redundant I/O which is close at 105% rated speed and reaching theintegrated with serial remote I/O (e.g. fully closed position at 107% of rated speed.GENIUS, Fieldbus) and connections to pro- This normal governing characteristic is overrid-grammable logic control systems. All I/O points den by a power/load unbalance-sensing featureare available to the controls database for the upon the sudden loss of significant electricalintegrated system. load. Pressure in a steam turbine stage, repre-The speed and load control for the unit oper- sentative of steam turbine output, is summedates through control of the gas turbine fuel with a gas turbine fuel flow signal and continu-valves. The steam turbine control valves are ously compared with the generator electricalclosely coordinated, being closed at startup output. When a significant imbalance of poweruntil steam at sufficient pressure and tempera- generated over electrical output is detected theture for admission is available from the HRSG. control and intercept valves are closed as rapid-They are then ramped open and held in fixed ly as possible, limiting the speed rise to less thanposition as load is changed with sliding pres- the 110% setting of the emergency overspeedsure. The steam turbine control valves do not trip. Ultimate protection against excessive over-participate in normal frequency control. The speed is provided by the emergency governorHP and LP control valves begin to close when that trips the unit by simultaneously closing allspeed rises to 103% of rated speed and are fully gas turbine fuel and steam turbine control andclosed at 105%. stop valves.The intercept valves operate in a pressure con- The sequencing system automatically starts thetrol mode at low load to maintain proper steam unit from a ready-to-start condition and loads itpressure in the gas turbine steam cooling sys- to gas turbine base load or a preset load. Tabletem. With increasing speed the intercept valves 5 shows starting time from initiation to full load.lag the control valves by 2% speed, beginning to Figure 9 presents an overview of the starting andGE Power Systems GER-3936A (05/01) s s 10
    • Advanced Technology Combined Cyclesloading sequence for a hot start. Figure 10 is a steam turbine has a single-casing and single-similar presentation of the cold start sequence flow exhaust as would be applied at a site withof a single unit. Note the speed hold shown for steam turbine condenser cooling that accom-developing steam for steam turbine cooling, modates the higher range of exhaust pressures.which is not required in multi-unit installations Plants using steam turbines with double-flowwhere running units can be used to support exhausts are approximately 10 feet (3m) longer.steam turbine cooling needs of the starting The plan area for the 60 Hz advanced technol-unit. ogy combined cycle is approximately 10% larg- er than that for current technology combined Start Standby Time to cycles, while the power is increased approxi- Designation Period (hrs) Full Load (min) mately 60% so that the plot space per unit of Hot 0-12 60 installed capacity is reduced approximately Warm 12-48 120 45%. Cold >48 180 Plant related considerations that influence the selection of the single-shaft configuration for Table 5. Starting time from initiation to full load the advanced technology combined cycle are tabulated in Table 6. The gas turbine cannotPlant Arrangement operate independently of the steam cycle soThe high power density of the advanced tech- there is no operating flexibility advantage fornology combined-cycle systems enables a com- the multi-shaft system. The single-shaft system ispact plant arrangement. Typical plan and eleva- lower in installation cost because of the singletion arrangements are shown in Figure 11 with generator, main electrical connections, trans-overall dimensions for outdoor STAG 107H and former and switchgear as compared to two forSTAG 109H plants. In this arrangement, the the multi-shaft system. 110 100 90 ..% Speed, % Net Plant Output.. 80 Normal loading 70 60 OUTPUT 50 Bring steam turbine on 40 line. 30 Transfer from air to SPEED 20 steam. 10 0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 Time from Synchronization (minutes) Time from Roll Off (minutes) Figure 9. Typical S107H/S109H hot start loading profileGE Power Systems GER-3936A (05/01) s s 11
    • Advanced Technology Combined Cycles 110 Speed hold to generate 100 steam turbine cooling steam. 90 (Not required for multi- ..% Speed, % Net Plant Output.. unit sites with cross 80 connection for ST LSB cooling). Normal loading Bring steam turbine on 70 line. Loading rate limited by steam 60 turbine warming rate. 50 SPEED 40 Transfer from air to 30 steam cooling. Basis: 20 Single unit with auxiliary OUTPUT boiler sized for steam seals 10 and condenser purge only. 0 0 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 240 Time from Synchronization (minutes) Time from Roll Off (minutes) Figure 10. Typical S107H/S109H cold start loading profile, single unit Multi-Shaft STAG 107H STAG 107H Single Shaft (One GT/ST) Equipment (Quantity) – Gas Turbine 1 1 – Steam Turbine 1 1 – Condenser 1 1 – Cooling Water Trains 1 1 – Generators 1 2 – Main Electrical Connections 1 2 – Generator Transformers 1 2 Steam Valves (Quantity) – Main Steam Non-Return 0 0 – Reheat Isolation 0 1 – Reheat Relief 2 2 – Reheat Stop/Control 1 1 – Low Pressure Non-Return 0 0 Foundations High High/Low Installed Cost Low High Operation – Combined-Cycle Simple Simple – Start/Stop Simple Simple – Load Following Good Good – Contingency Management Simple Complex – Islanding Good — – Simple Cycle No Yes Staged Construction No Yes Table 6. Combined-cycle configuration comparison summaryGE Power Systems GER-3936A (05/01) s s 12
    • Advanced Technology Combined CyclesIntegrated Gasification Combined The capacities and efficiencies are shown as ranges because they vary with plant economicCycle (IGCC) considerations and the type of gasifier, gasThe IGCC is broadly recognized as the coal- cleanup system, air and steam cycle integrationfired generation plant with the best environ- and the coal or other solid fuel analysis andmental performance. Integration with the moisture content.advanced technology combined cycle also willenable it to be the most economical power gen- Key features of an advanced technology IGCCeration system firing coal, petroleum coke, plant that enable economical power generationheavy residual oil and other solid or low grade are:liquid fuels. Figure 12 shows a diagram of a typ- s Low installed cost resulting from theical unitized advanced technology IGCC system capacity of the unit which enables it towith an oxygen blown gasifier and integration be matched with a single large gasifier.of the air separation unit with the gas turbine. s High efficiency which reduces fuelThe range of ratings for the advanced technol- consumption and further reducesogy IGCC plants are shown in Table 7: plant cost by reducing the capacity of the gasification and cleanup system per unit of installed generation IGCC Frequency Capacity Thermal Net capacity. UNIT Hz Range LHV (MW) Eff. Range (%) STAG 107H 60 400-425 45-49 Repowering STAG 109H 50 500-530 45-49 The advanced technology combined-cycle sys-Table 7. Ratings for advanced technology IGCC tem is readily adaptable to the repowering of plants existing steam turbine generator units. The A C B Dimension STAG STAG (M/Ft) 107H 109H A 129/424 136/445 B 46.3/152 48.6/159 C 94.9/309 98.9/325 Figure 11. Single-shaft unit plan and elevationGE Power Systems GER-3936A (05/01) s s 13
    • Advanced Technology Combined Cycles Coal Air Separation Gas Air Gasifier Unit Cooler Nitrogen Air Gas Cleanup Heat Recovery Steam Generator Cold Reheat Hot Reheat Main Air Exh. Gas Nitrogen I.P. Coal Coal Gas Steam Water L.P. Oxygen Gas Steam Electric Air Generator Power Turbine Turbine Figure 12. Unitized advanced technology IGCC systemintegration of the steam cycle with the gas tur- water permits can minimize sitebine cooling system requires appropriate con- permitting work.sideration, but several methods for matching A wide range of steam turbine ratings can bethe cooling requirements to the existing steam matched to the MS7001H and MS9001H gascycle are available and include the following: turbines by retaining existing feedwater heaters s The cooling steam temperature and as may be necessary to meet exhaust flow limi- pressure for the MS7001H and tations. MS9001H gas turbines are in the same range as those of the cold reheat Conclusion steam in many conventional steam The GE advanced technology combined cycles units with 2400 psig (165 bar) throttle promise improved economics of electric power pressure. generation with outstanding environmental s Apply cooling water and existing performance in natural gas and coal-fired appli- support facilities and replace the cations. These characteristics are enhanced by existing steam turbine with a modern, the evolutionary development from a technolo- high efficiency steam turbine that is gy base with extensive experience, which specifically matched to the combined- assures low maintenance and reliable, conven- cycle requirements. This option is ient operation. attractive when the use of existingGE Power Systems GER-3936A (05/01) s s 14
    • Advanced Technology Combined CyclesList of FiguresFigure 1. Advanced technology combined-cycle unitFigure 2. STAG 107H/109H cycle diagramFigure 3. S107H ambient temperature effect on performance and part load performanceFigure 4. S109H ambient temperature effect on performance and part load performanceFigure 5. S107H and 109H single-shaft STAG equipment configurationFigure 6. Steam and water sampling schematicFigure 7. Single-shaft combined-cycle unit integrated control architectureFigure 8. Multiple-unit station control architectureFigure 9. Typical S107H/S109H hot start loading profileFigure 10. Typical S107H/S109H cold start loading profile, single unitFigure 11. Single-shaft unit plan and elevationFigure 12. Unitized advanced technology IGCC systemList of TablesTable 1. Advanced technology combined-cycle – thermal and environmental performanceTable 2. Advanced technology combined-cycle steam conditionsTable 3. Last-stage buckets for advanced technology combined-cycle applicationsTable 4. Single-shaft combined-cycle experienceTable 5. Starting time from initiation to full loadTable 6. Combined-cycle configuration comparison summaryTable 7. Ratings for advanced technology IGCC plantsGE Power Systems GER-3936A (05/01) s s 15
    • Advanced Technology Combined CyclesGE Power Systems GER-3936A (05/01) s s 16