Repowering of Thermal Power Plants asFully-Fired CombinedCycle Generating PlantsHITACHI, Ltd.Tokyo, JapanChubu Electric Power Co.,Inc. Nagoya, JapanYoshiki NoguchiTakao KoikeREP-1TYPE OF COMBINED CYCLEREPOWERINGFEEDWATER HEATING COMBINED CYCLEFULLY-FIRED COMBINED CYCLEREQUIREMENTSA) REDUCTION OF POWER GENERATINGCOST   **Economy**B) REDUCTION OF CARBON DIOXIDEEMISSIONS   **Environment**C) IMPROVEMENT OFEFFICIENCYOF EXISTING POWER PLANTS**Energy**SOLUTIONS1. INTRODUCTION OF EXISTING POWER PLANT REPOWERINGREP-2HEAT RECOVERY COMBINED CYCLERemove Existing BoilerAir**SYSTEM CONFIGURATION** **IMPROVEMENT IN PLANT EFFICIENCY** **Approx.**(Relatively)**MODIFICATION AND** **NEW INSTALLATION EQUIPMENT** **Modification Items New** **Installation Equipments** **Nil GT** **generating equipment** **GT exhaust gas duct** **GT exhaust** **gas stack Exhaust** **gas/feedwater heat exchanger REMARKS** 1.New equipments can be installed while the existing power plant in operation.2.Interconnection can be completed in less than eight weeks.**Exhaust gas/ Feedwater Heat** **Exchanger Gas** **Turbine**Additional SystemPumpSteamTurbineCondenserFeedwater HeaterFuelBoilerAirFuelREP-31.1 FEEDWATER HEATING COMBINED CYCLE**SYSTEM CONFIGURATION** **IMPROVEMENT IN PLANT EFFICIENCY** **Approx.****10**(Relatively)**MODIFICATION AND** **NEW INSTALLATION EQUIPMENT** **Modification**Items**New Installation Equipments** **Boiler GT generating** **equipment GT** **exhaust gas duct Gas feedwater heater** **REMARKS**Modification of the existing plant can be completed in less than six months.* It depends on system configuration around the GT and Boiler show in the table of Item No.1.4 (Next page)**Additional System**STACKPumpSteamTurbineCondenserFeedwater HeaterBoilerFuelAir**Gas Feedwater Heater** **Gas Turbine** FuelREP-41.2 FULLY-FIRED COMBINED CYCLEItem**High temperature wind box GT exhaust gas cooler FD fan mixing-injection Heat recovery equipment of** **GT exhaust gas**Boiler Boiler evaporator Feed water heater Boiler**Configuration Improvement of the thermal** **efficiency(relatively)***1)**10***1)**10***1)**Modification of the boiler**Largest Larger Smaller Smallest**Remarks**Thermal analysis for theinterface between the boilerand wind box is required.The wind box shall bemade of materials such aslow alloy steel or stainlesssteel.Exhaust gas cooleris designed as aboiler evaporator.Bypass systemaround the boilerevaporator isrequired.Bypass systemaround the feed watersystem is required.A gas mixing device isrequired for the mixingpoint of GT exhaust gasand FDF air.**Period of modification work**Longer Longer**Shorter Shorter***1)In case that gas turbine exhaust gas flow is Just matched to boiler combustion air required.coolercoolerBoilerBoilerExhaust gasExhaust gasBoilerDTRHP heaterFDFBoilerREP-51.3 SYSTEM CONFIGURATION AROUND THE GT AND BOILER1.4 PLANT EFFICIENCY IMPROVEMENT BY CONVERTING TO FULLY-FIREDCOMBINED CYCLE PLANT

**EXISTING THERMAL FULLY-FIRED COMBINED CYCLE PLANT**  **POWER PLANT F** 2**E 2** **E**1**Electric output** **Boiler fuel F** 1'GT loss**GT fuel**Boiler lossTurbine loss**Condenser**Boiler loss Turbine loss**Electric output** **Condenser Boiler fuel** **F**1**E**1Plant outputincreaseGT outputPlantefficiencyimprovementBoiler fuel can be reduced by using GTexhaust gas as boiler input'REP-61.5 BASIC CONFIGURATION OF FULLY-FIRED COMBINED CYCLE PLANT**Gas turbine**2CondenserStack**Gas feedwater heater** FDFA/H**Low pressure feedwater** **heater High pressure** **feedwater heater 100** **340**DeaeratorBoilerEcoLNGLNGAir**540****600****Residual O 14** **15%**Steam turbineREP-7Modification1.6 BASIC ENGINEERING FOR FULLY-FIRED COMBINED CYCLE PLANTItem Basic engineering Consideration**Increase of output****Improvement of efficiency** Adoption of high**efficiency**gas turbineSelection of heat recovery typeSelection of gas turbine to match theexisting boilerUtilization of gas turbine exhaust gas as a combustion airEffective utilization of exhaust heat of gas turbine and boilerIncrease of plant output is equal to gas turbine outputPlant efficiency improvement (depend on cycle configuration)**Boiler exhaust gas****Cooling water for condenser** Study on**environmental**regulation orrequirementsExhaust gas flow rate from boiler will be increasedNOx from stack shall be less than the limitationIncrease of cooling water flow rate for condenser, orIncrease of temperature rise of cooling water for condenser**Site area****Compact**arrangementInstallation of gas turbine beside the existing thermalpower plant**Modification schedule** **Shut-down period****Shorten**the modification period**Shorten**the shut-down periodConstruction work while the existing thermal power plantin operationEffective utilization of inspection periodShorten shut-down period**Gas turbine Steam turbine** **Plant operation**Gas turbine simple cycle operationSteam turbine independent operation isrequired or notSame operation flexibility as existingthermal power plantGas turbine simple cycle operation-Low efficiency-Environmental issueDepend on steam turbine output and plant operationCombined cycle operation by using high load change rate ofgas turbine**Existing equipment****Additional equipment** Utilization of existing equipmentRemoval of existing equipmentAdditional equipments with gas turbine installationUtilization of equipment for boiler exhaust gasUtilization of existing stackRemoval of FDF, A/H etc.Addition of IDF, gas feedwater heater, gas duct, damper etc.

EnvironmentArrangement Schedule Operation PerformanceREP-81.7 EXAMPLE OF SELECTION FOR GAS TURBINE TYPE12001000800600400200500 2000Plant output increase byconverting to fully-fired C/CApprox.1030%(at GT base operation)Exhaust gas flow rate (103Nm3/h)50Hz1300class GT		class GT1000MW700MW600MW500MW350MW250MW

**Plant output (MW)**50Hz60Hz1GT2GT1GT2GT1GT2GT1GT2GT		class		class**1100 class GT** **1300 class GT** JUST MatchWith FDF operation1000 25001500REP-960Hz2. EXPERIENCES IN JAPANOutput (MW) Supplier**GT ST**Plant GT Boiler ST1Tokyo ElectricPower Co., Inc.Goi Unit No.6‘94/7126 350 476 Hitachi Hitachi HitachiRepoweringHitachi2Chubu ElectricPower Co., Inc.**Chita Unit No.6**‘94/9**154 700 854**Hitachi Hitachi ToshibaRepoweringHitachi3Chubu ElectricPower Co., Inc.**Chita Daini Unit No.1** ‘94/9**154 700 854**Hitachi Hitachi ToshibaRepoweringHitachi4Chubu ElectricPower Co., Inc.**Chita Unit No.5**‘95/6**154 700 854** Hitachi Hitachi ToshibaRepoweringHitachi5Chubu ElectricPower Co., Inc.Chita Unit No.2‘95/8154 375 529 Mitsubishi Mitsubishi ToshibaRepoweringMitsubishi6Power Co., Inc.Unit No.2‘96/7154 700 854 Toshiba IHI ToshibaRepowering	

7Chubu ElectricPower Co., Inc.Chita Unit No.1‘96/8 154375 529 Mitsubishi Mitsubishi ToshibaRepoweringMitsubishiChubu ElectricChita DainiNo. Utility Plant name C/O RemarksREP-103. REPOWERING FOR CHITA POWER PLANT AND CHITA SECONDPOWER PLANT OF CHUBU ELECTRIC POWER Co., Inc.3.1 LOCATIONCHITA POWER STATIONTOKYONAGOYAOSAKACHITA DAINI POWER STATIONREP-113.2 MAIN SPECIFICATION**Before repowering After repowering**Chita Unit No.5,6 Chita Daini Unit No.1 Chita Unit No.5,6 Chita Daini Unit No.1Plant output 700MW 854MWSteam turbine output 700MW 700MW**Gas turbine output**154MWBoiler(ModificationSupercritical,constant pressureSupercritical,sliding pressureSupercritical,constant pressureSupercritical,sliding pressureonce-throughreheat systemonce-throughreheat systemonce-throughreheat systemonce-throughreheat systemMCR 2300t/h 2150t/h 2050t/hAir supply system Forced Forced induced inducedFuel LNG LNGSteam turbine(Modification)Type TC4F-33.5 TC4F-33.5Vacuum of Condenser 722mmHg 717mmHgGas turbine (Newly installed)Type Single-shaft typeModelF7FAfiring Temperature 1288FuelLNGCommercial operation#5:1978.51983.9#5:1995.61994.9#6:1978.4 #6:1994.9ItemTypeREP-123.3 SYSTEM CONFIGURATIONGray areas indicate newly installed or modified sections.BFPHP IPLPLPReheaterBoilerBFP-TGRFLNGDe NOxTo condenserStack	
 	
	
	
	
	No.1GFWHNo.2GFWHAirAirIDFFDFNo.3 GFWHAirLNGGas turbine(F7FA)Low pressurefeed water heaterHigh pressurefeed water heaterFire ignition torchEconomizerDe NOxA/HA/HCondenserDeaeratorREP-13Item FeatureFeed water heating systemGas turbine exhaustgas heat recoverysystemNo.3 gas feed water heater(newly installed)(Gas turbine exhaust temp. :about 600350)Boiler exhaust gasheat recoverysystemNo.2 gas feed water heater(newly installed)No.1 gas feed water heater(newly installed)Boiler exhaust gas temp. (about 350)Stack inlet gas temp. (about 100)Boiler bypass ductNewly installed(For plant start-up andpartial load operation)Forced draft fan/air heaterExisting equipment(Gas turbine exhaust gas flowBoiler required air flow)(Steam turbine independentoperation possible)Induced draft fan Newly installed(For adjustment of gas turbineexhaust draft)REP-143.4 SYSTEM FEATURE3.5 INSTALLATION AND TRIAL OPERATION SCHEDULEAdd F7FA gas turbine to existing 700MW thermal power plantRepowering to 854MW fully-fired combined cycle plantModification of repowering is completed with shut-down period ofthree(3) monthsConstruction schedule of repowering(Example of Chita Unit No.6)1992 1993 1994 1995Boiler firing11Beginconstructionof GT house1GTon base459GT firingC/OCommercial operation of 700MW plantShut-downTrial operationCommercial operation854MW*REP-15Boilershut-down102*)Authorized output3.6 MODIFICATION OF BOILERHeating surface area of reheater is increasedbecause steam flow rate and heat load ofreheater is increased by converting tofully-fired combined cycle plant.Example of Chita Unit No.6Economizer outlet headerIncrease of reheaterheating surface areaREP-16The modification of combustion facility isnecessary to introduce fresh air to ignition torchbecause low O2 gas turbine exhaust gasis used as boiler combustion air source.Catalyst and plate type catalyst are increasedbecause exhaust gas flow and NOxconcentration is increased by adding gasturbine.3.7 MODIFICATION OF STEAM TURBINE PLANTFurther investigation for the modification of the condenser and circulating water systemis required because the heat load of the condenser is increased due to the addition of agas turbineItem Chita Unit No.6 Chita Daini Unit No.1IP and LP nozzle(newly exchanged) LP nozzle (newly exchanged)Steam turbine(because of the increasing the IP/LP section steam flow)Gas turbine auxiliarycooling water facilityDry type radiator(for gas turbine plant)Dry type radiator(for gas turbine plant)CondenserRe -used(cooling water flow not changed) (cooling water flow not change)Circulating water systemCondensate water system(operate stand-by equipment)Boiler feed water pump(driven by steam turbine)Re -usedRe -used Re -usedRe -used Re -used(operate stand-by equipment)Re -used Re -usedREP-173.8 PLANT OPERATIONGAS TURBINE AND STEAM TURBINE LOADGas turbine is started at 50% steam turbine load from theview point of high efficiency operationGas turbine is operated as high load as possible15477035070075%Operating limitationbecause ofeconomizer steamingSteam turbine load(MW)

Gas turbine load (MW)REP-183.9 PLANT PERFORMANCE TEST RESULTItem**Chita Unit No.5 Chita Unit No.6 Chita Daini Unit No.1** Gas turbine output154MW 154MW154MW**Plant efficiency**Result5.8%5.0%5.7%**improvement***1)Target3.7%3.7%3.5%Plant efficiency (HHV)Combined cycle operation40.0% 40.1% 40.7%Steam turbine independent operation37.8% 38.2% 38.5%Plant efficiency improvement shows the relative improved efficiency between steam turbineindependent operation and combined cycle operation.Plant efficiency (HHV)REP-194. REDUCTION VALUE OF CARBON DIOXIDE EMISSIONS0.45(kg-CO2/kWh)**[ - 44****]**0.54(kg-CO2/kWh)**[ - 32****]**0.58(kg-CO2/kWh)**[ - 28****]**0.80(kg-CO2/kWh)**[ Base ]**CO2 emission*1)2)per gross output(kg-CO2/kWh)235MW845MW700MW700MWUnit Gross OutputLNG FiredLNG FiredLNG FiredCoal FiredFuelAdvancedCombined CycleFully-FiredCombined Cycle(AfterRepowering)ConventionalConventionalType ofPower PlantAssumptionType of Power plant units are selected as typical examples.*1) CO2 emission = Energy Consumption x Carbon emission factorx Fraction of Carbon Oxidised x 44/12*2) Operating hour is 6100 hr/year ( 70% Capacity Factor )REP-20