forty years of combined cycle power plants

October 2002 | ASME Power Division Special Section 7

Based on my observations of this committee in the lastthree years, I know that we can count on the support ofevery member of the committee. It takes the efforts ofall of us to continue the growth of this committee; wehave come very far in a short period of time. We arepast the birth of this committee and now I believe we

need to chart our future and explore what we can dowith the committee. I look forward to meeting each ofyou at the next meeting in Orlando. I also ask you againfor suggestions and comments on how we can move thiscommittee forward.

Jonathan BainFPL EnergyProduction Assurance - EastRegion100 Middle StreetPortland, ME 04101Phone (207) 771-3522Fax (207) 771-3535Cell (207) 632-1451O&M

Michael MiketaSenior Construction ManagerTIC - The Industrial CompanyEPC

Darrell W. HayslipVice PresidentCalpine CorporationO&M - Asset Management

Les WardVPOrion PowerEPC

Phil Deen, Manager of PlantEngineering forSiemens/WestinghouseEPC

Doug WilliamsonCalpineEPC

Joe SchroederVice-President of EngineeringNooter [email protected] 314-525-8008O&M

Richard WinchCRS Cost Reduction SystemsO&M

Sep Van de lindenABBEPC

GE Representative

MHIA RepresentativeEPC

Vogt-Nem RepresentativeEPC

Constellation PowerO&M

Deltak RepresentativeO&M

List of Panelists for Combined Cycle Users Group

IntroductionEven though the first installations of combined cycle powerplants with heat recovery steam generators (HRSG’s) areonly about forty years old, the first attempt to build gasturbines for power generation was made more than 100years ago. It took however about 40 years before gasturbines were installed to supply peaking power.

When the first gas turbines were installed in the US, theywere mostly used as mechanical drives or as peaking units.At the same time it was also realized that the thermalperformance of a gas turbine installation can beenhanced by utilizing the gas turbine’s sensible heat ofthe exhaust gases in a heat recovery system. Such systemcan provide heat in the form of hot water or steam foreither a combined cycle power plant and/or cogeneration.

The first Westinghouse gas turbine rated at 1340 kWwent into operation in 1949. [3] This W 21 unit,illustrated in Figure 1, was installed at the River FuelCorporation in Mississippi. Also in 1949, General Electricinstalled its first gas turbine for power generation at theBelle Isle Station of the Oklahoma Gas and ElectricCompany, which provided already sensible exhaust heatfor feedwater heating of a steam turbine unit.

The development of combined cycle power plants wasmainly influenced by the available gas turbinetechnology. Initially, relatively small gas turbines wereavailable to build power plants at which the exhaustheat of the gas turbines was utilized for heatingfeedwater or to use the gas turbine’s discharge aspreheated air for the boiler of a steam turbine unit. Inthe late 1960s the gas turbine unit sizes became largeenough to start building combined cycle power plantswith heat recovery steam generators supplying main

Forty Years of Combined Cycle Power PlantsLothar Balling, General Manager Reference Power Plant Development, Siemens Power Generation

Heinz Termuehlen, ConsultantRay Baumgartner, Manager, Reference Power Plant Development, Siemens Westinghouse Power Corp.

Figure 1: First Gas Turbine Installed for Commercial Operation in 1949

For information on how to join the ASME, go tohttp://www.asme.org/divisions/power/membership/

or call 800.977.0474 and we’ll fax you an Express Application form.

ASME Membership Information

8 ASME Power Division Special Section | ENERGY-TECH

steam for a bottomingsteam turbine cycle.

The evolutionary develop-ment of the large heavy-duty gas turbines is bestrevealed by their increasingfiring temperatures andunit ratings. Figure 2 illus-trates the trends of both ofthese values over the past50 years.

The firing temperature inthe early 1950s was in-

creased from roughly 1300°F (705°C) to 1500°F (815°C) inthe late 1950s and reached 2000°F (1090°C) at about1975. From there it increased slowly until 1990, when thefirst advanced gas turbines were introduced resulting ina step change in the firing temperature from initiallyroughly 2300°F (1260°C) to approximately 2400°F(1315°C) at the turn of the century. This advancementwas possible by adopting already proven design featuresfrom aero-engines for heavy-duty gas turbines, such asdirectionally solidified or even single-crystal blading,improved blade coatings and advanced film cooling.

The second diagram in Figure 2 shows the unit rating ofgas turbines for 60 Hertz applications. In the early 1950sthe gas turbine unit rating was relatively small, less than1/100 of the unit rating of steam turbines which reachedalready the 500 MW mark. However the developmenttoward large units went fast and in the early 1960s 20MW gas turbines became available. In the mid 1980s thehighest gas turbine rating was already 100 MW. A smallstep change was made in 1990 with the introduction ofthe first advanced gas turbines. In the late1990sadvanced gas turbines with a rating over 200 MW for 60Hertz were already being built.

The trend of the two design parameters, firing or rotorinlet temperature and output of gas turbines, were themain influential factors for the potential application andeconomics of combined cycle power plant concepts.

Combined Cycle Plant ConceptsWhen building a combined cycle power plant on agreenfield or as a repowered steam plant, four basicplant concepts can be applied, namely:

• Feedwater heating

• Parallel steam supply

• Fully-fired boiler (Hot wind box)

• Heat recovery steam generator (HRSG).

All four concepts are best utilized at a certain gasturbine output to steam turbine output ratio, namelyfor 100 % steam turbine output:

• Feedwater heating 10% - 30 % gas turbine output

• Parallel steam supply 20 % - 60% gas turbine output

• Fully- fired boiler (Hot wind box) 15 - 35 % gasturbine output

• Heat recovery steam generator ~ 200 % gas turbineoutput

These relationships of gas turbine to steam turbineoutputs for different plant concepts and the developmenttrend of gas turbines shown in Figure 2 clearly reveal whythe first combined cycle power plants were eitherfeedwater heating or hot wind box applications.

In the late 1940s and early 1950s the firing temperatureof gas turbines was around 1300°F (705°C). At this lowfiring temperature level the gas turbine exhausttemperature level was with roughly 700°F (370°C), toolow to generate main or reheat steam for steam turbines,which at that time were designed for main steamtemperatures in the 950°F (510°C) to 1000°F (540°C)range. Pilot power plants with even 1100°F (590°C) mainsteam temperatures were already being built.

However, these low gas turbine exhaust temperaturelevels were well suited for feedwater heating, co-generation and also, together with a high oxygencontent in the 13 to16% range due to the high gasturbine excess air, for hot wind box applications. Theparallel steam supply concept as an advancement of thefeedwater heating concept was introduced much lateras a more efficient way to utilize the gas turbine exhaustheat for not only preheating feedwater, but also togenerate some secondary steam for the steam turbine aseither reheat steam or even main steam.

With these three combined cycle concepts most of thefuel is burned in the steam generator, which can befueled with coal or any other fuel, and the first twoconcepts can even be applied to nuclear plants. [4] Onlythe relatively small gas turbine fuel potion requiresnatural gas or distillate oil.

Figure 2: Gas Turbine Development Trend

First Combined Cycle Power Plant Applying Feedwater Heating__________________1949

First Heat Recovery Steam Generator for a Gas Turbine_____________________________1957

First Fully-Fired Boiler Combined Cycle Power Plant __________________1965

First Combined Cycle Power Plant with Heat Recovery Steam Generator __________1968

First Coal-Gasification Combined Cycle Power Plant __________________1972

First Combined Cycle Power Plant with an Advanced Gas Turbine ________________1990

First Combined Cycle Power Plant with Fuel Cell ________________________________2000

Figure 3: Combined Cycle Power Plant History


As revealed in Figure 3, more than forty years ago in1957, the first heat recovery steam generator (HRSG) fora gas turbine was built. Early gas turbine/ HRSG unitswere mostly used in the chemical industry.

In the late 1950s heat recovery steam generators (HRSGs)with continuous spiral fin-tubing become available forbuilding more efficient gas turbine/HRSG units. Initially,they provided steam for co-generation applications,since the gas turbine temperature level was stillrelatively low. It took another decade before, in the1960s, this technology was generally utilized forcombined cycle power plants with gas turbines of 20MW to 50 MW output.

Co-generation, also today referred to as CHP (CombinedHeat and Power), which provides electric power andprocess steam with extremely high fuel utilization, becamean additional incentive in 1978, when the Public UtilitiesRegularly Policy (PURPA) was introduced to promote theselling of co-generation power to the utilities.

From there on, the development of combined cyclepower plants with HRSGs went fast and in the early1970s gas turbines with ratings above 50 MW and firing-temperatures around 20000F (1090°C) became available.The next major step in building highly efficientcombined cycle power plants was done in 1990 when theadvanced gas turbine technology was introduced toeventually reach the goal of the Department of Energy(DOE) to develop combined cycle power plants with a 60% power plant net efficiency.

Pre-Designed Combined Cycle PlantsIn the late 1960s and early 1970s the gas turbinesuppliers started to develop pre-designed or standardcombined cycle power plants, like GE developed theSTAGTM (Steam and Gas) system, Westinghouse thePACETM (Power at Combined Efficiency) system andSiemens the GUDTM (Gas und Dampf meaning gas andsteam) system. The goal was to build standard powerplants around the different gas turbine and steamturbine models to supply an optimal combined cyclepower plant package. The early predesigned packagesfeatured a gas turbine and heat recovery steamgenerator (HRSG) only to provide steam for co-

generation. But also packages for just the gas turbinesused for any kind of application were offered by the gasturbine suppliers. Such an example of a Westinghousemodel W251 EconopacTM gas turbine unit is illustratedin Figure 4 [5]. In the late 1960s the first gasturbine/HRSG units with sufficiently high steamconditions became available to generate main steam forsteam turbines of initially only 750°F (400°C).

The pre-designed combined cycle power plants included avariety of plant arrangements. For example, options likethe number of gas turbine/ HRSG units feeding into onesteam turbine as well as different plant arrangements likesingle shaft gas turbine/ generator/ steam turbine units ormultiple shaft units with separate generators for each gasturbine and steam turbine can be selected.

Combined Cycle Plant ArrangementsTwo examples of pre-designed reference power plants(RPP) featuring advanced gas turbines in a single and amultiple-shaft arrangement are given.[6]

The first example is single-shaft arrangement of a 50Hertz CC1S.V94.3A combined cycle power plantarrangement as shown in Figure 5. This predesigned RPPunit features a 265 MW advanced V94.3A gas turbineand a 130 MW reheat steam turbine. The HRSG is of ahorizontally arranged triple-pressure reheat design. Thegas turbine is directly coupled to a hydrogen-cooledgenerator. The two casing steam turbine consists of anHP casing and a combined IP/LP casing with axial exhaustinto the axially arranged condenser. The steam turbine iscoupled to the other end of the generator by asynchronous clutch for best operating flexibility. The

Figure 4: 39 MW Gas Turbine Package of the 1970’s (Model W251 Econopac™)

Figure 5: Otahuhu Installation of Single-Shaft CCIS.V94.3A Reference Plant


start-up of such combined cycle power plant after anightly shutdown takes only 1/2 hour.

The photograph in figure 5 shows the 380MW/50 HertzOtahuhu CC1S.V94.3A power plant in New Zealand. Thispower plant was placed into operation only 20 monthsafter receipt of order, which was possible because a pre-designed reference power plant (RPP) was installed. Themajor advantage of such RPP concepts is the short deliverytime. Power plant components can be pre-fabricated andmaterials such as large forgings pre-ordered.

The second example is a multiple-shaft arrangement ofadvanced gas turbines for 60 Hertz applications [7]. Two185 MW W501F gas turbines can be arrange with onesteam turbine as 550 MW reference power plants forcombined cycle application with different scopes ofsupply and site-dependent options. Figure 6 illustratesfour major steps of the scope of supply growth for a RPP,starting with two EconopacTM providing the gasturbine-generators with all, associated auxiliaries,electrical and I&C equipment. The EconopacsTM includethe gas turbines’ air intake systems and the exhaust gasducts. The remaining combined cycle power plantequipment is not within the scope of supply from the

gas turbine supplier. The next step is the 2.W501F powerisland which includes all components of the Econo-pacsTM, the HRSGs and the steam turbinegeneratorwith all their auxiliaries, electrical and I&C equipment,the condenser and major pumps. The power island scopeputs the thermodynamic plant design into the hands ofthe gas turbine supplier and consequently he canwarrant the plant’s overall performance. The third stepwould be a turnkey outdoor plant, including allremaining balance of plant equipment. The final stepwould be an indoors turnkey power plant by adding themachine house structure.

The steam turbine design of the 2.W501F RPP is highlyinfluenced by the site-dependent backpressure. Asshown in Figure 7, the RPP design concept provides theoption of applying either a single-flow or a double-flowLP turbine design. The single-flow axial exhaust steamturbine features a HP turbine and a combined IP/LPturbine section, whereas the doubleflow side exhaustunit features a combined HP/IP turbine section and adouble-flow LP turbine section.

Combined Cycle Plant PerformanceThe early feedwater heating and fully-fired plants werecombined cycle plants in which the gas turbineinstallations enhanced the performance of the steamplants. The major portion of the fuel is still burned in thesteam generator. Figure 8 shows, as an example, thefifth unit of the 2300MW Gersteinwerk combined cyclepower plant in Germany.

This 750 MW unit features a coal-fired steam generator,only the 114 MW gas turbine is natural gas-fired. Theunit achieves a power plant net efficiency of 41 %, animprovement of about 7 % points over a conventionalcoal-fired unit, both featuring desulfurization systems.

The performance improvement for such combined cyclepower plants over conventional steam turbine plantsdepends greatly on the steam turbine to gas turbineoutput ratio. The following power plant efficiencyimprovements can be typically achieved:

• Feedwater heating 10% - 30% gas turbine outputimprovement: 1.5% - 4% points

• Parallel steam supply 20% - 60% gas turbine outputimprovement: 3% - 7% points

• Fully-fired boiler (Hot wind box) 15 - 35% gas turbineoutput improvement: 3% - 6% points

Two W501F Econopacs™ 2.W501F Power Island 2.W501F Turnkey Plant 2.W501F Turnkey Plant(outdoor design) (indoor design)

Figure 6: Multiple-Shaft CC2.W501F Reference Power Plant Installation Options

Figure 7: Multiple-Shaft CC2.W501F

CC2.W501F with Single-Flow LP Turbine

CC2.W501F with Double-Flow LP Turbine

Figure 8: 2300 MW Combined Cycle Power Station Gersteinwerk


The performance improvements seem to be small whencompared to as much as 20% points performanceimprovement of combined cycle power plants withHRSGs, but one must realize that roughly 200% gasturbine output is required for these applications. Theevolutionary development of combined cycle powerplants with HRSGs and steam turbines for pure powergeneration started in the 1960s at an efficiency levelbelow 40%. Gas turbine efficiency levels were around25% and the gas turbine firing temperatures reachedabout 1600°F (870°C), providing an exhaust temperaturelevel high enough to generate 750°F (400°C) main steamfor a bottoming steam turbine.

The rating, firing temperature and efficiency of gasturbines were rapidly increased, leading to larger andmore efficient combined cycle plants. The combinationof the gas turbine Brayton cycle and the steam turbineRankine cycle was improved by building more efficientbottoming steam cycles. Figure 9 illustrates how thechanges in bottoming cycles affect the plant heat rate.The single-pressure non-reheat cycle as shown in theEntropy/Temperature diagram, can be improved bybringing the Rankine cycle closer to the Brayton cycle toraise the overall combined cycle performance. With themost effective triple-pressure single-reheat cycle a heatrate improvement of 5.2% can be achieved.

Presently, advanced gas turbines, triple-pressure single-reheat HRSGs and specifically designed steam turbinesfor combined cycle applications achieve about 58%combined cycle efficiency level as illustrated in Figure 10.

Further combined cycle performance improvement canbe expected to reach the 60% plant net efficiency levelwithin this decade. The importance of the increase infiring temperature for combined cycle power plants isbest revealed by the fact that the combined cycleefficiency increase from 58% to 60% can be achieved byonly raising the firing temperature by about 120°F(67°C). Also the bottoming steam cycle can further beimproved by utilizing a once-through boiler design withadvanced main steam pressure and temperature.Increasing the main steam pressure from 1600 psig (110bar) to 2600 psig (180 bar) and the main steamtemperature from 1020°F (550°C) to 1110°F (600°C)would improve the combined cycle power plant netefficiency by 3/4 of a % point.

The performance of an advanced combined cycle powerplant is shown in Figure 11 for a singleshaft gasturbine/generator/steam turbine arrangement. Thediagram is based on the present performance of aV94.3A 50 Hertz gas turbine with a nominal rating of265MW. The triplepressure single-reheat HRSG providesmain steam of 1830 psig (125 bar) and 1049°F (565°C).

Figure 9: Bottoming Steam Cycles of Combined Cycle Power Plants Figure 11: Combines Cycle Power Plant CCIS.V94.3A Performance

Figure 10: Combined Cycle Power Plant with Advanced Gas Turbineand Triple Pressure Single-Reheat Steam Cycle

Figure 12: Repowered Lauderdale Power Station


Reheat steam is provided at atemperature of 1028°F (550°C) andLP steam at a temperature of 491°F(295°C). The reheat steam turbinefeatures an HP turbine section andan IP/LP turbine with axial single-flow exhaust and is rated at about130MW. With this combined cyclepower plant arrangement whichalso includes natural gas preheatingto 266°F (130°C) the net powerplant output of 390 MW can begenerated at a net power plantefficiency of 57.3%. This data can beconsidered a conservative perform-ance level, since the performance ofsuch combined cycle power plantwas last year tested to achieve 398MW net output at a net powerplant efficiency of 58.4 % under ISOconditions.

RepoweringAt the Lauderdale power plant sitein Florida the first steam turbine wasinstalled in 1926 and the firstpeaking power gas turbine in 1970[8]. In the early 1990s all but the lasttwo steam turbines were retired.The last two 125 MW reheat steamturbines, built in the late 1950s,were modified for combined cycleoperation. Four advanced 501F gasturbines were installed to build twoidentical combined cycle units withtwo gas turbine/HRSG units feedingsteam to one steam turbine. Thesetwo triple-pressure reheat combinedcycle power plant units generate 425MW each. The 32% net power plantefficiency of the original reheatsteam turbine plant was improvedto an nearly 50% efficiency of therepowered combined cycle unitsillustrated in Figure 12.

Figure 13: Repowering Concept of Peterhead Power Station Figure 14: Integrated Coal Gasification Combined Cycle Power Station Luenen

Transform your PC into a complete plant equipment analysistool. GPCALCS™ lets you test and calculate the performance of plant equipment with unmatched speed, accuracy, and insight.

PTC-based test procedures, performance calculations (Excel format), and steam table libraries keep both you and your plantoperating at peak efficiency.

Workbooks for:• Boiler and Air Heaters (Coal/Oil/Gas)• Compressors• Condensers• Controlled Extraction Turbines• Cooling Towers• Fans• Feedwater Heaters• GasTurbines• Heat Recovery Steam Generators (HRSGs)• Pumps• Steam Turbines

Used by hundreds of engineers world-wide, GPCALCS™ isbased on years of experience testing and troubleshooting alltypes of power plant machinery and equipment.

GPCALCS™The Per formance Engineer’s Toolbox

Version 4.0 - Power Edition

GPCALCSfor $495*

*Quantity discounts available

For risk-free trial offer, please call: 800.803.6737

[email protected]

Continued on page 26for more information see 04234ET0205 on infolink at energy-tech.com

26 ENERGY-TECH

The next example is a repowering project of the late 1990s, forthe repowering of the 660 MW Peterhead power station inScotland with three advanced V94.3A/ 50 Hertz gas turbines[9,10]. The goal was to achieve close to green-field combinedcycle power plant performance when operation with the gasturbines and still keep all the equipment to allow alsooperation with the existing boiler burning a different fuel. Theexisting reheat steam turbine was designed for a main steampressure of 2300 psig (160 bar) and a main and reheat steamtemperature of 1000°F (538°C). The existing 660 MW powerplant provides a plant net efficiency of about 39 %. Whenoperating the existing steam turbine with the three 270 MWgas turbines, a total output of 1210 MW can be generated witha 57 % plant net efficiency. Figure 13 illustrates how the twodifferent power plant cycles are connected to each other andhow they can be separated.

A combination of shut-off valves and bypass systems allowsindependent start-up of the boiler as well as each gasturbine/HRSG unit. This repowering concept also has thecapability to operate in a hybrid mode with both the boiler andthe HRSGs supplying steam to the steam turbine for up to it’soriginal 660 MW output. This operating flexibility also providesfuel flexibility because electric power can be generated byburning the original fuel in the boiler or by burning natural gasor #2 fuel oil in the gas turbine combustion system.

Coal-Gasification, Fuel Cell and Solar Energy Combined Cycle Power PlantsIntegrated coal-gasification combined cycle (IGCC) power plants

Figure 17: Solid Oxide Fuel Cell and Integrated CoalGasification Power Plant

Figure 15: IGCC Power Plant Puertollano

Figure 16: 217 kW Combined Cycle Pilot Power Plant with Solid Oxide Fuel Cell and Gas Turbine

Combined Cycle Continued from page 13

became available in the mid 1970s and fuel cellcombined cycle (FCCC) power plants as well assolar energy combined cycle power plants (SECC)are presently in their pilot plant stage [11]. In 1972the first integrated coal gasification combinedcycle (IGCC) power plant went into operation atthe Luenen power station in Germany, featuringfive air-blown fixed bed gasifiers, a 74 MW gasturbine and a 96 MW non-reheat steam turbine. Aunique feature of this pilot plant is twopressurized steam generators directly mounted tothe gas turbine, replacing the two silo-typecombustion chambers of the 1960 vintage gasturbine as illustrated in Figure 14. The pressurizedsteam generators operated at about 150 psia (10bar) pressure. The plant net efficiency was 37%based on the lower heating value (LHV) of thecoal. The next IGCC pilot plant was the Cool Waterproject in California featuring an oxygen-blowngasifier and an 80 MW gas turbine. The net plantoutput was about 120 MW. Presently, about 30large IGCC plants are in operation world-wide.However some of these plants are burning eitherrefinery residues or orimulsion instead of coal.

Figure 18: Solar Energy Combined Cycle (SECC) Power Plant

October 2002 27

The latest technology already inoperation with syngas since 1998 hasbeen applied for the largest (300 MW)single-train coal-fired IGCC plant inPuertollano, Spain [12]. As illustratedin Figure 15, this plant is equippedwith an oxygen-blown entrained-flowgasification system. It features anadvanced V94.3/50 Hertz gas turbineoperating at a firing temperature ofabout 2280°F (1250°C).

This IGCC power plant concept canachieve a power plant net efficiency of45 %. However, the Puertollano plantunder site conditions burning with afuel mixture (1:1) of high-ash coal andhigh-sulfur petroleum coke hasachieved a tested net power plantefficiency slightly below 45 %. The firsthybrid SOFC+GT plant for 217 kWoutput with a 187 kW (SOFC) assemblyand a 47 kW micro gas turbine was putinto operation in California. This pilotplant concept with its pressurizedSOFC is illustrated in Figure 16. TheSOFC and gas turbine are skidmounted with the following approx-imate dimensions: 7.4 m (24.3 ft)length, 2.8 m (9.2 ft) width and 3.9 m(12.8 ft) height.

The electrical net efficiency of this firstpilot plant has been estimated to bealready 57%, plus cogeneration of heator hot water supplied by a heatrecovery system. Such co-generationfacilities would be ideally suited fordistributed power generation.

With the future availability of coalgasification and fuel cell technologies,power plants can be built whichcombine both. Such potential coal-fired fuel cell combined cycle powerplant concept is illustrated in Figure 17.

ISO 9001

Ecolochem, Inc. Phone 757.855.9000 • FAX 757.855.1478U.S. Toll Free 800.446.8004 • www.ecolochem.com

Filtration • Softening • Reverse Osmosis Deoxygenation • Demineralization • Gas Transfer Membranes

Electrodeionization • DeltaFlow® • SecureTech®

Ecolochem Provides• Design, Equipment• Installation• Operation & Maintenance• SecureTech

New Technology Upgrades• Guaranteed Quality• Emergency Service Backup

MobileRO®

MobileFlow®

Ask us about making ultrapure water withoutchemicals – the DeltaFlow System

29 Years ofOutsourcing

Figure 19: Historic Development of Combined Cycle Power Plant Performance

An IGCC power plant provides fuel for solid oxide fuel cellsand the heat from the SOFC is recovered in the gas turbine/steam turbine combined cycle power plant. The fuel cellsgenerate about 52 % of the plant’s output and the gas andsteam turbines together the remaining 48%. A combined fuelcell/ coal gasification (FCCC/IGCC) power plant concept couldraise the 45% efficiency of present IGCC power plant conceptsto a 50 % and higher net power plant efficiency level.

for more information see 03448ET0205 on infolink at energy-tech.com

28 ENERGY-TECH

Another potential of combined cycle power plants is to add solarenergy to the steam cycle of a combined cycle unit. Figure 18illustrates how such plants could generate electric powerespecially for air conditioning at a time of the day when it is mostneeded. The example shows how the output of a combined cycle80 MW plant with a mid size V64.3 gas turbine can be raised from88 MW to 115 MW by an LP steam supply from a solar field atnoon at a potential power plant net efficiency of 69%. Such solarenergy combined cycle (SECC) power plants are presently in theirdevelopment phase.

Figure 20: Fuel Cell Combined Cycle (FCCC) Power Plant

Refrigeration Division

FES Systems Inc.

Leading Technologies. Individual Solutions.

FES Systems Inc. • 3475 Board Road • York, PA 17402 USATel: 717-767-6411 • Fax: 717-764-3627 • www.fessystems.com

Direct Refrigeration Systems

FES Systems Inc. builds complete directrefrigeration packages for the precooling of turbineair. A direct refrigeration system guarantees inletair temperature year round, minimizes coilpressure drop and has lower parasitic energyrequirements than alternative liquid chiller systems.FES Systems Inc. manufactures industrial screwcompressors, heat exchangers, vessels andmicroprocessor control systems. We can provideequipment only, equipment plus refrigerant plantand piping design, field supervision or a total“Turn-Key” installation.

Conclusion

In the last forty years combined cycle powerplants have greatly influenced the powergeneration industry. Presently, about 90% ofthe newly constructed power plants are eithercombined cycle power plant or to a less smallerportion gas turbine peaking units. Figure 19illustrates the combined cycle power plantdevelopment with gas turbines as primemovers over the last forty years. The historyreveals that there is a potential improvementof the net power plant efficiency from about20% for the early gas turbine plants to 68% forfuture fuel cell combined cycle power plants insight. The combined cycle power plant effic-iency has risen in the last 40 years from lessthan 40% to 58% and still in this decade thegoal of 60% can be reached.

Integrated coal gasification combined cycle(IGCC) plants have reached a 45% efficiency leveland also here future improvement is possible.Fuel cell combined cycle (FCCC) power plants andsolar energy combined cycle (SECC) are thenewest technologies in power generation andhave just been introduced by building the firstpilot plants. With the FCCC technology a powerplant featuring a gas turbine/steam turbinebottoming cycle as illustrated in Figure 20 canreach already, with present technology avail-able, a 68% net power plant efficiency level. TheSECC technology could enhance a combinedcycle power plant net efficiency from 53% to69% as shown in figure 18.

For such combined cycle power plants theproper judgment of the plant’s performance isof most importance. Power generation from aSECC plant can reach easily 100% if the relativeportion of solar energy is increased and only the


Combined Cycle

October 2002 29

fuel for the gas turbine is accounted foras used energy. All the combined cyclepower plants can also ideally be appliedfor co-generation to further enhancetheir fuel utilization. Here it isimportant to properly judge theefficiency to generate power as well asthe fuel utilization for providingelectric power and heat. Combinedcycle power plant concepts can also bedesigned to provide by-products, e.g.an oil shale fueled combined cyclepower plant can produce oil.

The history of combined cycle powerplants has been relatively shortcompared to the more than 100 yearsof electric power generation bycoalfired steam turbine plants.However, combined cycles powerplants provide excellent performanceespecially when burning natural gas.But even if natural gas would becomescarce, gasification combined cyclepower plants can be utilized to burnlower quality fuels, e.g. nearly anygrade of coal, refinery residues,biomass, waste or oil shale.

References(1) “100 Years of Power Plant

Development- Focus on Steamand Gas Turbines as PrimeMovers” by Heinz Termuehlen,published by ASME Press NewYork, 2001, [email protected]

(2) “Stationaere Gasturbinen”Lechner C., Seume J., Chapter “GT-/ GUD- Kraftwerke” by LotharBalling, Springer- Verlage, Berlin

(3) “Combustion Turbine Cogen-eration”, Westinghouse, SA11253A, Copyright 1983

(4) “Parallel and Feedwater Repow-ering of Nuclear Power Plants”,Termuehlen, H., ASME IJPGC,New Orleans, LA, June 2001

(5) “Outage Management ImprovesGas Turbine Availability”,Westinghouse, SA 11228, 1982

(6) “Customization and Standard-ization a Contradiction?” LotharBalling et al, ASME Turbo- Expo,New Orleans, LA, June 2001

Cost Effective Technology That Works!

Precision TurbineFlowmeters

Liquid & Gas MeasurementStainless Steel Construction

.02% Repeatability

2363 Sandifer Boulevard • Westminster, South Carolina 29693 • USAVoice: 864.647.2065 Fax: 864.647.1255

1-800-258-1165 • www.sponsler.com

±.25% Linearity-450˚ to + 1000˚ F

Pulse Output

For:• Batching

• Blending

• Filling

• Process Control

• Rate Indication

• Totalization



30 ENERGY-TECH

(7) “The Combined Reference Power Plant Approach- Meeting the Targets of Power Plant Supplier and Customers”Christian Engelbert and Raymond Baumgartner, Power- Gen International 2001, Las Vegas, Nevada

(8) “FPL Lauderdale Plant Repowers with 501F Combustion Turbines”, Westinghouse, 494030, 1993

(9) “Repowering of the Peterhead Power Station Provides Oper-ating Flexibility, Increased Efficiency andEmission Reduction” Haupt, A., Thiel H-J., and Termuehlen H.., ASME International Joint Power GenerationConference, San Francisco, CA, 1999, ASME PWR-Vol. 34

(10) “Repowering: A Concept for Improving the Economics of Existing Assets in the Deregulated Power Market”Lothar Balling et al, Power-Gen Asia, September 20- 22, 2000, Bangkok, Thailand

(11) “Power Generation and ItsEffect on the Environment,”Riedle, K., Kuenstle., andTermuehlen, H., Proc. of Power-Gen International Conference,Dallas, TX, 1993

(12) ”Puertollano IGCC Plant:Operating Experience andPotential for Further TechnologyDevelopment” Ignacio Mendes,Francisco Gercia Pena, JuergenKarg and Gerhard Zimmer-mann” Power-Gen Europe 2001,Brussels, Belgium

■

EX-FOSS for Boiler Efficiency call: 415-455-0100visit: www.ExergeticSystems.com

• Most sophisticated steam generator thermal analysis available• Complete system mass and energy balances• Second law analysis for locating degraded equipment • Soot blowing recommendations• Consistency analysis of measured effluents• Btu or SI units, HHV or LHV bases, etc., etc., etc.• Multi-copy site license at $12,400

A. BIEDERMANA Triumph Group Company

STOCKING DISTRIBUTOR

INDUSTRIAL INSTRUMENTS & CONTROLSAMETEK, U.S. GAUGE NOSHOK GAUGES

AMETEK, TEST EQUIPMENT NOSHOK TRANSDUCERS

DICKSON RECORDERS PSI TRONIX

FASTEST CONNECTORS TEL-TRU THERMOMETERS

HEDLAND FLOW UNITED ELECTRIC CONTROLS

INDUSTRIAL VALVES, REGULATORS & FITTINGSATKOMATIC HOKE VALVES

BURKERT CONTROMATIC ITT CONOFLOW

CIRCLE SEAL CONTROLS KIP LEVEL & VALVES

CHEMIQUIP NOSHOK VALVES

GYROLOK VALCOR PUMPS & VALVES

ENVIRONMENTAL INSTRUMENTSALNOR AIR FLOW & SENSORS DICKSON RECORDERS

SCOTT INSTRUMENTS BACHARACHCOMBUSTION

EUROCLEAN HAZARDOUS MATERIAL VACUUMS

1425 GRAND CENTRAL AVE., GLENDALE, CA 91201PHONE: 818-246-8431 FAX: 818-244-2189

TOLL FREE: 800-525-6696E-MAIL: [email protected]



Combined Cycle

forty years of combined cycle power plants

Documents