C1_CCPP

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1. Introduction to Combined 1. Introduction to Combined Cycle Cycle Power Plants Power Plants

Combined Cycle Power Plants 1. Combined Cycle Power Plants 1 / 109

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Introduction to Combined Cycle Power Plants 21Electricity Demand and Supply 222Cost of Electricity 443Electricity Demand and Supply 222

Characteristics of Combined Cycle Power Plants 534Wide Use of Gas Turbine 1025Characteristics of Combined Cycle Power Plants 534


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Gas Turbine In a gas turbine, the working fluid for transforming thermal energy into rotating mechanical energy is the hot

combustion gas, hence the term gas turbine.

The first power generation gas turbine was introduced by ABB in 1937 it was a standby unit with a thermal The first power generation gas turbine was introduced by ABB in 1937. it was a standby unit with a thermal efficiency of 17%.

The gas turbine technology has many applications. The original jet engine technology was first made into a h d t li ti f h i l d iheavy duty application for mechanical drive purposes.

Pipeline pumping stations, gas compressor plants, and various modes of transportation have successfully used gas turbines.

While the mechanical drive applications continue to have widespread use, the technology has advanced into larger gas turbine designs that are coupled to electric generators for power generation applications.

Gas turbine generators are self-contained packaged power plants.

Air compression, fuel delivery, combustion, expansion of combustion gas through a turbine, and electricity generation are all accomplished in a compact combination of equipment usually provided by a singlegeneration are all accomplished in a compact combination of equipment usually provided by a single supplier under a single contract.

The advantages of the heavy-duty gas turbines are their long life, high availability, and slightly higher overall


efficiencies. The noise level from the heavy-duty gas turbines is considerably less than gas turbines for aviation.

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Power Generation Requirement

CoalGas

Variety of Fuels Competitive Machine

GasOilWaterNuclearWind

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issioC

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WindSolarGeothermalBiomass

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Type of PlantBase Load Intermediate Load Peak Load

OperatingOperating Hours [hr/a] 5000 2000 to 5000 2000

Nuclear plant Gas turbine

Generating Units

High-performance steam turbine plant

High efficient combined cycle

Simple steam turbine plant

Old base-load plant

Combined gas and steam

Diesel engine

Pumping-up power plantg yplant

Hydropower plant

Combined gas and steam plant Old simple steam turbine

plant

Characteri-

Operated at full load as long as possible during the year

High efficiency and lowest cost

Operated on weekdays andshutdown at night and on the weekend

Low capital investment, buthighest operating costs

Characteri-stics

High efficiency and lowest cost

Poor load change capability (take more time to respond load demand)

The efficiency is higher than that of peak-load plants, but lower than that of base-load plants

Ease in startup

Used as standby or emergency also


) plants

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Combined Cycle Power PlantsIn simple cycle mode, the gas turbine is operated alone, without the benefit of recovering any of energy in the hot exhaust gases. The exhaust gases are sent directly to the atmosphere.Fuel

In combined cycle mode, the gas turbine exhaust gases are sent into HRSG. The HRSG generates steam that is normally used to power a steam turbine.

Combustor

Turbine G

Compressor

Inlet Air

Steam GHP LP

Exhaust GasAir Turbine G

Condenser

HP Drum

LP Drum

HRSGCondenser

DeaeratorHP Superheater

HP EvaporatorHP Economizer

LP Superheater

Condensate

LP Boiler Feed Pump

pLP Evaporator

LP Economizer


PumpHP Boiler Feed Pump

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Simple Cycle Simple cycle gas turbines for electricity generation are typically used for standby or peaking capacity and

are generally operated for a limited number of hours per year. Peaking operation is often defined as fewer than 2,000 hours of operation per year., p p y

In mechanical drive applications, and for some industrial power generation, simple cycle gas turbines are base load and operate more than 5 000 hours of operation per yearbase-load and operate more than 5,000 hours of operation per year.

Some plants are initially installed as simple cycle plants with provisions for future conversion to combined cycle.

Gas turbines typically have their own cooling, lubricating, and other service systems needed for simple yp y g g y pcycle operation. This can eliminate the need to tie service systems into the combined cycle addition and will allow continued operation of the gas turbine during the conversion process and, with proper provisions, during periods when the combined cycle equipment is out of service.

If future simple cycle is desired, a bypass stack may be included with the connection of the HRSG. A typical method for providing this connection is to procure a divert damper box at the outlet of the gas turbine.


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Schematic of a CCPP


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3 P R h C l (F Cl G T bi )

Cycle Diagram3 Pressure Reheat Cycle (F-Class Gas Turbine)

Fuel

G Heat Recovery Steam Generator

Air

Gas Turbine

IP Steam LP SteamCold ReheatHot Reheat Main

G

SteamCold Reheat Steam

Hot Reheat Steam

Main Steam

St

Condenser

G

Steam Turbine

Condensate Pump

SteamWaterFuelAir


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T-s Diagram for a Typical CCPP

T

Topping Cyclepp g y(Brayton Cycle)

Bottoming Cycle(Rankine Cycle)

s


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CHP; Combined Heat and Power

In the simplest arrangements, the gas turbine waste heat is used directly in an industrial process, such as for drying in a paper mill,such as for drying in a paper mill, or cement works.

Adding an HRSG converting t h t i t t iwaste heat into steam, gives

greater flexibilities in the process for chemical industries, or district heating


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Thermodynamic Consideration

THH

W

QHGas

TH

WTurbine

W

QH

HRSG

Q

W

Q

WSteamTurbine

TL

QLTL

QL

[ F il / N l ] [ C bi d C l ]


[ Fossil / Nuclear ] [ Combined Cycle]

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Gas Turbine Combined Cycle Topping Cycle Bottoming Cycle

Main Components GT ST/HRSG

Working Fluid Air Water/Steam

Temperature High Medium/Low

Thermodynamic Cycle Brayton Rankine

Coupling Two Cycles Heat Exchanger

Topping Cycle Bottoming Cycle


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Combined Cycle Power Plants Combined cycle means the combination of two thermal cycles in one plant.

When two cycles are combined, the efficiency increases higher than that of one cycle alone.y y g y

Thermal cycles with the same or with different working fluid can be combined.

In general a combination of cycles with different working fluid has good characteristics because their In general, a combination of cycles with different working fluid has good characteristics because their advantages can complement one another.

Normally, when two cycles are combined, the cycle operating at the higher temperature level is called as t i l Th t h t i d f d th t i t d t th l t t l ltopping cycle. The waste heat is used for second process that is operated at the lower temperature level, and is called as bottoming cycle.

The combination used today for commercial power generation is that of a gas topping cycle with a water/steam bottoming cycle. In this case heat can be introduced at higher temperature and exhausted at very low temperature.

Temperature of the air used as a working fluid of gas turbines can be increased very high under lower Temperature of the air used as a working fluid of gas turbines can be increased very high under lower pressure. Water/steam used as a working fluid can contain very high level of energy at lower temperature because it has very high specific heat.

N ll th t i d b tt i l l d i h t h


Normally the topping and bottoming cycles are coupled in a heat exchanger.

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Combined Cycle Power Plants Air is used as a working fluid in gas turbines having high turbine inlet temperatures because it is easy to get

and has good properties for topping cycle.

Steam/water is an ideal material for bottoming cycle because it is inexpensive, easy to get, non-hazardous, and suitable for medium and low temperature ranges.

The initial breakthrough of gas-steam cycle onto the commercial power plant market was possible due to the development of the gas turbine.

In the late 1970s, EGT reached sufficiently high level that can be used for high efficiency combined cycles.

The breakthrough was made easier because gas turbines have been used for power generation as a simple cycle and steam turbines have been used widely.

For this reason, the combined cycle, which has high efficiency, low installation cost, fast delivery time, had been developed easily.


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CCPP System OptionsItems Options Remarks

Single pressure / Two pressure /Three pressure *Steam Cycle Reheat

Non-reheatDependent on EGT

Natural gas */ Distillate oil / Ash bearing oilFuel Low BTU coal and oil-derived gas

Multiple fuel systems

Water injection / Steam injectionNOx Control SCR (NOx and/or CO)

Dry Low NOx combustion *

Condenser Water cooled (once-through system) *

Condenser Water cooled (cooling tower) /Air-cooled condenser

Deaeration Deaerating condenser * Deaerator/evaporator integral with HRSGg

HRSG Design

Natural circulation evaporators * Forced circulation evaporators Unfired *


Supplementary fired

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Base Configurations for CCPP

Unfired, 3-pressure steam cycle Non-reheat for rated EGT less than 1000F/538C Reheat for rated EGT higher than 1050F/566C and fuel heating Heat recovery feedwater heating Feedwater dearation on condenser Feedwater dearation on condenser Natural circulation HRSG evaporators

GT with DLN combustors

Once-through condenser cooling water system

Multi-shaft systems

Single-shaft systems Integrated equipment and control system


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GT vs. STGas Turbine Steam Turbine

Combustion Internal External

Thermodynamic cycle Brayton Rankine

Cycle type Open Closed

Working fluid Air Water/Steam

Max. pressure, bar 23 (40 for Aviation) 350 (5050 psig)

Max. temperature, C(F) 1350 (2462) 630 (1166)a te pe atu e, C( ) 350 ( 6 ) 630 ( 66)Blade cooling Yes No

Shaft cooling No Yes (USC only)

Max. cycle efficiency, % 40 49 (USC only)

Max. number of reheat 1 2

Power density High Lowy g

Steam conditions of the steam turbines for combined cycle applications are lower than those for USC steam turbines.


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CCPP Major equipment of combined cycle power plant

Gas turbine, steam turbine, generator, HRSG

Main advantages of the combined cycle power plant Higher thermal efficiency than the others (up to 60%)

- SC steam plants: 35~40%, USC steam plants: 49%p , p Shorter construction period Lower initial construction cost

- Capital costs of gas fired combined cycle are about 40% of coal fired steam plants Lower emission (low NOx burners, SCR, CO catalysts are available)

Current situationC t ti f CCPP h i d d ti ll i 1970 Construction of CCPP has increased dramatically since 1970s

Market is governed by GE and SIEMENS It is hard to develop a new competitive model because it requires both advanced technologies and

high costhigh cost


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CCPP Concept

Electricity Demand Process-energy (steam/water) demand Operating Philosophy Financing

Customer Requirements

(steam/water) demand

Site Related FactorsSite conditions / Ambient conditions50 or 60Hz Site conditions / Ambient conditions

Legislation / Emission requirements

Resources

50 or 60Hz

Fuel Water Space

Plant Concept SolutionpCapital cost

US$/kWType / Number of GTs

Single shaft Multiple shaft

Cycle selection with parameter optimization

Final optimization Plant /Cycle


Plant /Cycle

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A Typical HRSG

StackHPSection

IPSection

LPSection

TransitionDuct

starting

DuctBurner

Air Inlet

Duct

AddtionalAir supply

startingMoter

GeneratorGasTurbine

GasTurbine

FlowCorrectionDevice

HRSG

Inlet duct

A-A section


Exhaust duct

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Introduction to Combined Cycle Power Plants1Electricity Demand and Supply2Cost of Electricity 3Electricity Demand and Supply2

Characteristics of Combined Cycle Power Plants4Wide Use of Gas Turbine 5Characteristics of Combined Cycle Power Plants 4


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Demand and Supply Electricity must be produced when the consumers need it because it cannot be stored in a practical manner

on a large scale.

Electricity can be stored indirectly through water, but it is not economical.

Actually only storage of water pumped into lakes during off-peak time to be used during peak hours has been used practically.

Large fluctuation in demand during the day requires quick response from power plants to meet the balance between demand and supply.

Gas turbine combined cycle power plants have good characteristics in terms of fast start-up and shut-down.

In addition, they have low investment costs, short construction times compared to large coal-fired power stations and nuclear plants.

The other advantages of combined cycles are high efficiency and low emission.


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Power Demand during a Day

Excellent start-up and shut down capabilities are essential for thisare essential for this


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Combined Cycle Power Plants 1. Combined Cycle Power Plants 25 / 109: , (2012)

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- GT GT ST

GS EPS Siemens V84.3 SGT6-8000H

41

710.0274 0

378.0136 0 2013/8 SGT6 8000H 1 274.0 136.0 2013/8

GS WH 501D5 3 315.6 100.0 CHP ABB GT11N 4 317.6 100.0 CHP

SK E&S GE 7FA+e 4 686.8 340.0 K-Power 3 515 1 285 0 833 3 on 1 Conf 3 515.1 285.0 833 3-on-1 Conf.

POSCO GE 7FA+ 2 337.6 165.0 GE 7FA+ 2 337.6 165.0

POSCO WH W501D5 12 1,200.0 600.0POSCO WHV84.3A 4 812.0 440.0

MPC Siemens W501F 2 340.0 160.0

MHI M501J 2 640.0 280.0 920 2-on-1 Conf. WH W501D5 4 408.0 100.0

2 340.0 7EA GE 6F 2 154.0

NCC GE 6B 5 190 0NCC GE 6B 5 190.0 2 1560S-Power Siemens SGT6-8000H 2 548.0 272.0 2014/10

() 556 2013/12


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- Site GT () GT GT ST

GE 7FA+e (171.7) 8 1373.6 680.0 GE 7FA (170) 8 1360.0 680.0

GE 6B (38) 2 76.0 38.0 MHI M501F 3 550.0 310.5 Siemens SGT6-8000H 1 274.0 136.0 2014 ABB GT24 (150) 6 900 0 450 0

ABB GT24 (150) 6 900.0 450.0

Siemens V84.3A?

22

320.0360.0

160180.0

515.0 2013/11

GE 7FA+e (171.7) 8 1373.6 680.0

GE 7EA (87.9) 4 351.6 160.0MHI M501J 2 640.0 280.0

MHI M501G 2 508.0 210.0 MHI M501G 2 508.0 210.0 MHI M501J 4 1280.0 560.0

ABB GT11N (79.4) 8 635.2 300.0 WH 501D5 (105.2) 6 631.2 300.0

WH 501D5 (105.2) 2 210.4 100.0WH 501F (150) 4 600.0 300.0MHI M501J 2 640.0 280.0

500MW 340 0 160 0 2014 ()


500MW 340.0 160.0 2014 ()

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/ 4,300 MW (7FA+e x 16 Units)


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(2,000 MW) (960 MW) (900 MW)

(1,800 MW) POSCO (500 MW) POSCO (500 MW)

POSCO (3 000 MW) GS EPS (1 000 MW) (500 MW) (500 MW) K P (1 074 MW)POSCO (3,000 MW) GS EPS (1,000 MW) (500 MW) (500 MW) K-Power(1,074 MW) (1,200 MW)

GS (1,000 MW)


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(550 MW) (700 MW) (900 MW)( ) ( ) ( )

(507 MW) (960 MW) GS EPS (1020 MW)


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Gas Turbine Production by SectorS D i F F I i l

18

Source: Davis Franus, Forecast International

7

)

15Commercial Aviation

l

a

r

s

(

2

0

0

7

12

Electrical Generation

o

n

s

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f

D

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6

9Electrical Generation

B

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l

l

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o

3

6Military Aviation

Mechanical Drive

2004 2006 2008 2010

Marine Propulsion


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(: QBtu, %)

162.1 99.1 100.4 26.5 32.7 420.8

38.5 23.6 23.9 6.2 7.8 100

: 2003 ( )

(7.8%)) , International Energy Outlook, 20061 QBtu = 25.2Mtoe1 QBtu 1 Qu d illi Btu {Qu d illi 1015

(38.5%)(23.9%)

(6.2%)

1 QBtu = 1 Quadrillion Btu {Quadrillion = 1015() or 1024 ()}

toe = Tonnage of Oil Equivalent (1 = 1 )

(23.6%)


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World Primary Energy


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S IEO (2008)

World Power Generation by Fuel Type

Billion MW-h40

Source: IEO (2008)

40

30

Renewables

Nuclear

20

Renewables

Nat. Gas

10Coal

02005 2010 2015 2020 2025 2030

Hydro


2005 2010 2015 2020 2025 2030

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B d C li d G i

World Power Generation by Fuel TypeBased on Centralized Generation


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Market Share and Product


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Characteristics of Combined Cycle Power Plants4Wide Use of Gas Turbine 5Characteristics of Combined Cycle Power Plants4


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2007

: /kWh 677 4: /kWh 677.4

117.0 128.3 107.3

39.4 40.9

27.2

LNG


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S P Pl E i i (Bl k & V h)

Source: Power Plant Engineering (Black & Veatch)


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400

300W

-

y

e

a

r

Coal-Steam

Gas Turbine

200

l

C

o

s

t

,

$

/

k

W

100

A

n

n

u

a Combined Cycle

0 1,500 5,000 8,760

Operation Hours/year

0

Comparisons will depend on fuel costs, capital costs, and maintenance costs.


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In contrast to steam turbine-generators, the manufacturers of gas turbines have a defined product line,

allowing for substantial standardization and assembly line manufacturing.

The modular concept of the package power plants made gas turbines relatively quick and easy to install.

Standardization and modularization combine to provide the product benefits of relatively low capital cost and fast installation.

The benefits of low capital cost and fast installation were initially offset by higher operating costs when compared to other installed capacity. Therefore, early utility applications of gas turbine generator were strictly for peak load operation for a few hundred hours per year.

Improvements in efficiency and reliability and the application of combined cycles have added to the economic benefits of the technology and now give gas turbine based power plants a wider range of application on electric systems.


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Cost of Electricity

< Inputs for the evaluation of the cost of electricity >

Type of Plant Output, MWDescripti

onInvestment

cost, US$/kW

Average efficiency (LHV), %

Fuel price, US$/MBTu

(LHV)

Combined Cycle Power Plant 800

2 x GT1 x ST

750 56.5 8.0 25

Gas Turbine Plant (gas) 250 1 x GT 413 37.5 8.0 25Plant (gas)

Steam Power Plant (coal) 800 1 x ST 1716 44.0 3.5 25

Nuclear Power 1250 1 x ST 3500 34 5 0 5 40Plant 1250 1 x ST 3500 34.5 0.5 40

No cost for CO2 emissions were included.


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Cost of Electricity

100Capital

I t di t L dB L d

M

W

h

) 80

O&MFuel

Intermediate LoadBase Load

r

i

c

i

t

y

(

U

S

$

/

M

60

o

s

t

o

f

E

l

e

c

t

r

20

40

C

o 20

800 MW CCPP (gas)

800 MW Steam (coal)

250 MW GT PP (gas)

1250 MW Nuclear PP

800 MW CCPP (gas)

800 MW Steam (coal)

250 MW GT PP (gas)

1250 MW Nuclear PP


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GE S109H: Dry Low NOxCombustors(H System): Combined cycle: 14 Can-annular lean pre-mix DLN-2.5combustors : Output 480 MW (Gas turbine power 300 MW): Heat rate 6000 kJ/kWh: $153,500,000 ($320/kW) F15-K : $1


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Turbine Blade Prices (1998 )NOZZLE BUCKET MODEL (MW) TIT (C) ($)/Set MATERIAL ($)/Set MATERIAL

1 48 1,180,000 FSX410 92 2,200,000 GTD1112 48 1,180,000 GTD222 92 1,500,000 GTD1117FA 175 1,2603 60 1 190 000 GTD222 92 1 450 000 GTD1113 60 1,190,000 GTD222 92 1,450,000 GTD1111 32 680,000 FSX414 92 670,000 GTD1112 48 690,000 FSX414 92 680,000 IN7387EA 88 1,1043 48 740,000 FSX414 92 600,000 U5001 36 390,000 FSX414 92 430,000 GTD111

GE

2 48 450,000 GTD222 92 330,000 IN7386B 39 1,1043 64 420,000 GTD222 92 310,000 U5001 42 240,000 IN738 115 400,000 IN738LC2 66 210,000 IN939 115 400,000 IN738LC3 84 280 000 IN730 97 210 000 IN738LCGT11N 80 1 027 3 84 280,000 IN730 97 210,000 IN738LC4 90 210,000 X45 105 390,000 IN738LC

GT11N 80 1,027

5 40 390,000 20/25/2 59 500,000 ST 16/25MD1 100 1,170,000 MAR M247LC 197 800,000 DS CM247LC2 44 656,000 MAR M247LC 88 950,000 DS CM247LC

ABB

3 80 948,000 MAR M247LC 86 1,170,000 DS CM247LC4 78 1,170,000 IN738LC 84 950,000 MAR M247LC

GT24 150 1,255

5 76 800,000 IN738LC 82 1,240,000 MAR M247LC1 48 810,000 ECY-768 81 340,000 U5202 48 700 000 X45 73 300 000 U5202 48 700,000 X45 73 300,000 U5203 56 720,000 ECY-768 55 340,000 U520

501D2 105 1,198

4 56 770,000 X45 51 340,000 IN GC-7501 32 560,000 ECY-768 72 1,400,000 IN7382 24 410,000 X45 66 1,000,000 IN738

WH

501F 150 1 293


3 16 380,000 ECY-768 112 1,400,000 IN738501F 150 1,293

4 14 430,000 X45 100 1,100,000 U520

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System Features of CCPPAdvantages Disadvantages

ff1. High thermal efficiency

2. Low initial investment

3. Short construction time

4. Fuel flexibility Wide range of gas and liquid fuels

5. High reliability and availability1. Higher fuel costs

g y y

6. Low operation and maintenance cost

7. High efficiency in small capacity increments Various gas turbine models

2. Uncertain long-term fuel supply

3. Output more dependent on ambient temperatures

Various gas turbine models8. Operating flexibility

Base, intermediate, peak load9 E i t l f i dli9. Environmental friendliness

10. Reduced plant space


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1. High Thermal Efficiency [1/6] The value of efficiency is very high because fuel spend may be about 70 percent of the total cost.

All major OEMs have developed air-cooled gas turbines for combined cycles with efficiencies around 61 percent.percent.

Siemens proved performance of 60.75% at the Irsching site outside Berlin.

The old paradigm that high performance meant advanced steam cooled gas turbines and slow started The old paradigm that high performance meant advanced steam cooled gas turbines and slow started bottoming cycles has definitely proven false.

Both GE and Siemens are able to do a hot-start within 30 minutes to full load.

Steam cooling will most likely only be used for 1,600C firing level since there will be an air shortage for both dry low emission and turbine cooling.

The key for 61% efficiency is high performance gas turbines having higher pressure ratio and firing The key for 61% efficiency is high performance gas turbines having higher pressure ratio and firing temperature.

In addition, the exhaust gas temperature has to be at a level for maximum bottoming cycle performance.

Currently, most OEMs have capability of steam turbine throttle temperature of 600C(1112F) and the optimum exhaust gas temperature should therefore be on the order of 25-30C higher.

B th GE d Si h t d d d th ttl diti f th i b tt i l 165


Both GE and Siemens have presented advanced throttle conditions for their bottoming cycles, 165 bar/600C and 170 bar/600C, respectively.

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1. High Thermal Efficiency [2/6]

Fuel EnergyThree Pressure

Combined cycle power plants have a higher thermal efficiency because of the application of two complementary thermodynamic cycles

Fuel Energy

100%

GT 37 6%L i HRSG

Three PressureReheat Cycle T

Topping CycleGT 37.6%Loss in HRSG0.3%

Loss

0 5%

pp g y(Brayton Cycle)

ST 21.7%

e

n

s

e

r

0.5%

Loss

C

o

n

d

eStack8.6%Loss

0.3% Bottoming Cycle(Rankine Cycle)

31.0%s

[ Heat balance in a typical combined cycle plant ]


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C i f Th l Effi i


Comparison of Thermal Efficiency

60

5049 48

60

,

%

50

4035

38 40

30

35

10

20

IGCC(SIMPLE)

(SC)

(USC)

()


(SIMPLE)(SC) (USC) ()

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E l i f H D G T bi D i F


1967 1972 1979 1990 2000 2008 2012

Evolution of Heavy Duty Gas Turbine Design Features

TIT, C (F) 900 (1650) 1010 (1850) 1120 (2050) 1260 (2300) 1426 (2600)1426

(2600) 1500

Press. Ratio 10.5 11 14 14.5 19-23 20-23 20-23

EGT, C (F) 427 (800) 482 (900) 530 (986) 582 (1080) 593 (1100) 623

Cooling 1 vane1&2 vane1 blade

1&2 vane1&2 blade

1,2,3 vane1,2,3 blade

1,2,3 vane1,2,3 bladeblade

SC Power, MW 50-60 60-80 70-105 165-240 165-280 400-480 (CC)

SC Heat RateSC Heat Rate, Btu/kWh 11,600 11,180 10,250 9,500 8,850

CC Heat Rate, Btu/kWh 8,000 7,350 7,000 6,400 5,880 5,690

SC Effi., % 29.4 30.5 33.3 35.9 38.6 40

CC Effi., % 42.7 46.4 48.7 53.3 58.0 60 61


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P L d Effi i


100 The gas turbine equipped with

Part Load Efficiency

95

90

The gas turbine equipped with VIGV or several rows of variable stator vanes keeps the efficiency of the combined cycle plant almost constant down to

85

80

almost constant down to approximately 80 to 85% load.

This is because a high exhaust

75

70

ggas temperature can be maintained as the air mass flow is reduced.

30 40 50 60 70 80 90 100

65

60

Below that level, the turbine inlet temperature must be reduced, leading to an increasingly fast

d i f ffi i iLoad, %

30 40 50 60 70 80 90 100reduction of efficiencies.

The steam turbine is operated with sliding pressure mode down to 50% load. Below that point, the live-steam pressure is held constant resulting in throttling losses


steam pressure is held constant, resulting in throttling losses.

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P L d Effi i


110

Part Load Efficiency

95

1004GTs3GTs2GTs1GT

85

90

75

80

Down to 75% parallel reduction in load on all 4 GTs

65

70

Down to 75%, parallel reduction in load on all 4 GTs.At 75%, one GT is shut down.Down to 50%, parallel reduction in load on 3 remaining GTs.At 50%, a second GT is shut down.

Combined Cycle Load, %30 40 50 60 70 80 90 100

6020


4 GTs + 1 ST Arrangement

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C i f I i i l C i C

2. Low Initial Construction Cost [1/4]

Capital costs of gas-fired combined cycle are about 45% of coal-fired steam plants

Comparison of Initial Construction Cost

Type of Plant Output (MW) Specific Price (US$/kW)Combined Cycle Power Plant 800 550 650Combined Cycle Power Plant 800 550 - 650

Combined Cycle Power Plant 60 700 - 800

Gas Turbine Plant 250 300 - 400

Gas Turbine Plant 60 500 - 600

Steam Power Plant (coal) 800 1,200 1,400

Steam Power Plant (coal) 60 1,000 1,200

Nuclear Power Plant 1,250 2,000 3,000

Bi P Pl t 30 2 000 2 500Biomass Power Plant 30 2,000 2,500

These prices are valid for 2007.Interest during construction is not included.


g

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C i f G T bi P i


550

Source: Gas Turbine World (1999 Jan/Feb)

Comparison of Gas Turbine Price

500

550

1xV84.2

1xGT13D1x401

1x501D5A

1x701D

G.E.

SIEMENS

ABB

s

e

)

450

500

W

1x7FA

1xV94.21xV84.3A

1xGT11N2 1xGT24

1x701DW.H.

u

r

n

k

e

y

B

a

s

400

450

U

S

D

p

e

r

k

W

1x7EA

1 9FA

1xGT11N2 1xGT24

r

C

C

P

P

(

T

u

350

400

U 1x9FA

1xV94.2A

1x501F

e

L

e

v

e

l

f

o

r

100 200 300 400300

350

1xV94.3A1xGT26

1x701F

P

r

i

c

e


100 200 300 400ISO Net Combined Cycle Plant Output (MW)

300

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C B kd f CCPP


Items Portion % CCPP

Cost Breakdown for CCPP

Integrated Services 15%

4 Project management / Subcontracting

2 Plant and project engineering / Software

8 Plant erection / Commissions / TrainingServices 8 Plant erection / Commissions / Training

1 Transport / Insurance

15 Civil works

Lots 85%

32 Gas turbine / Steam turbine / Generator set

16 Balance of plants

7 Electrical systems7 Electrical systems

4 Instrumental and control

11 HRSG island

Basis: 350~700MW CC plant with a V94.3A Gas Turbine

As a rule of thumb, a 1% increase in the efficiency could mean that 3.3% more capital can be invested.


, y p

HIPT

C B kd f 400 MW CCPP


Site

Cost Breakdown for a 400 MW CCPP

Steam Turbine Set

Power Island Mechanical System

9%Civil, Arrangement, Building Facilities

18%

Site Infrastructure

3%

8%Heat Recovery

Steam Generator 10%

Mechanical Systems Outside

18%

Control 3%

yPower Island

8%

Electrical (without high

Control 3%

Gas Turbine Set 32%

Electrical (without high voltage switchyard)

9%


32%

HIPT

C i f C i Ti

3. Short Construction Time [1/2]

T pe of Plant Time [Months] Combined cycle plants are relatively quick

to design and erect because all major

Comparison of Construction Time

Type of Plant Time [Months]

Combined Cycle Power Plant 20 - 30

Gas Turbine Plant 12 - 24

to design and erect because all major equipment is shipped to the field as assembled and tested components.

The gas turbine is assembled at theSteam Power Plant (coal) 40 - 50

Nuclear Power Plant 60 - 80

The gas turbine is assembled at the factory and mounted on a structural base plate or skid, minimizing the need for field assembly of the turbine.

Biomass Power Plant 22 - 26 Other components and support systems such as cooling water and lubricating oil are modules that are easily erected and connected to the gas turbine skid

The gas turbine usually can be operated in simple cycle mode while the steam portion of the combined cycle is erected.

connected to the gas turbine skid.

The gas turbine from the 1960s to the late 1980s was used only as peaking power in the countries where the large steam turbines were used as base load power plants.

However gas turbine was used as base load mainly in the developing countries where the need of power


However, gas turbine was used as base load mainly in the developing countries where the need of power was increasing rapidly because the waiting period of three to six years for a steam plant was unacceptable.

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3. Short Construction Time [2/2]

Design Philosophy for Combined Cycle Plants

/ /

Customizationstart from outside to inside

Standardizationstart from inside to outside

/ /

1980s 2000s

Pre-engineered solution has the following benefits: Time (shorter delivery time) Quality (robust design) Risk (exchangeable components in case of troubles) Cost


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4. Fuel Flexibility Most gas turbine applications rely on natural gas or No. 2 distillate

oil.

Because of the availability and economics of natural gas, the [Table] GE heavy-duty GT shipped for fuels (by 1983)y g ,majority of new power plants prefer natural gas as a fuel.

Fuel affects CC performance in a variety of ways. Fuel UnitsNatural Gas 1408

shipped for fuels (by 1983)

Natural gas containing high hydrogen content has a higher heat content and therefore output and efficiency increase when the natural gas is used as a fuel.

Process GasDual GasDistillateNaphtha

1360

78314

Plant output and efficiency can be reduced when the ash bearing fuels (crude oil, residual oil, blends, or heavy distillate) are used because of fouling occurred in gas turbine and HRSG.

KeroseneDistillate or GasDistillate and GasCrudeCrude and Distillate

30964

825932

Plant output and efficiency can be reduced when the fuels containing higher sulfur content are used. This is because higher stack gas temperature is required to prevent condensation of corrosive sulfuric acid

Crude and DistillateResidualResidual or GasResidual/Distillate/Gas

32120

41

corrosive sulfuric acid.

Heavy fuels normally cannot be ignited for gas turbine startup; therefore a startup and shutdown fuel, usually light distillate, is needed with its own storage forwarding system and fuel

Total 3570


needed with its own storage, forwarding system, and fuel changeover equipment.

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D fi i i f R li bili d A il bili

5. High Reliability and Availability [1/4]

Reliability = Availability =P F P S F

Definition of Reliability and Availability

P = period hours (normally one year, 8,760h)F = total forced outage hours for unplanned outages and repairs

Reliability = Availability =P P

No of Successful Starts

S = scheduled maintenance hours

The probability that a unit, which is classified as available, and in ready service, can be started, and be brought to synchronization within a specific period time is defined as above An inability to start

Starting Reliability =No. of Successful StartsNo. of Attempted Starts

be brought to synchronization within a specific period time is defined as above. An inability to start within the specified period and synchronize is considered a failure to start. However, repeated attempts to start without attempting corrective action are not considered additional failures to start.

MTBF =Fired Hours

Trips from a state of operation


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C i f R li bili d A il bili

5. High Reliability and Availability [2/4]

Source A Source B

Comparison of Reliability and Availability

Type of Plant Availability (%)

Reliability (%)

Availability (%)

Reliability (%)

Combined Cycle Power Plant 90 - 94 95 - 98 86 - 93 95 - 98y

Advanced GT CCPP 84 - 90 94 - 96

Gas Turbine Plant (gas fired) 90 - 95 97 - 99 88 - 95 97 - 99

Steam Power Plant (coal fired) 88 - 92 94 - 98 82 - 89 94 - 97

Nuclear Power Plant 88 - 92 94 - 98 80 - 89 92 - 98

SGT6-5000F (W501F): Reliability: 99%, Availability: 95%, Starting reliability: 93% (2010)

Many analyses show that a 1% drop in the availability needs about 2~3% increase in the efficiency to Many analyses show that a 1% drop in the availability needs about 2 3% increase in the efficiency to offset that loss.

The larger gas turbines, just due to their size, take more time to undergo any of the regular inspections, such as combustor, hot gas path, and major overall inspections, thus reducing the availability of these turbines


availability of these turbines.

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A il bili R d i i C l Fi d P Pl

5. High Reliability and Availability [3/4]Source: EPRI CS-3344 pp.1-3

Stack S.H.R.H.

Availability Reduction in Coal-Fired Power Plant

Stack

HP Turbine IP Turbine

Econ

Gas

Water

LP Turbines

I.D. fan

Generator

Gas clean up

Condenser

AshAsh

Air heater

Coal

HP heater

LP heater

Water treatment

Fans (0 6%) Boiler tubes (4 2%) Fouling/slagging (2 8%) Pulverizers (0 6%) Bearings (2 0%)

Pulverizer

Coal prep CoalF.D. fan


Fans (0.6%) Boiler tubes (4.2%) Fouling/slagging (2.8%) Pulverizers (0.6%) Bearings (2.0%) Pumps (1.7%) Condenser (3.8%) Turbine blades (2.7%) Generator (3.8%)

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5. High Reliability and Availability [4/4] Reliability is the percentage of the time between planned overhauls where the plant is generating or is

ready to generate electricity, whereas the availability is the percentage of the total time where power could be producedbe produced.

Availability and reliability are very important in terms of plant economy because the power stations fixed costs are constant whether the plant is running or not.costs are constant whether the plant is running or not.

A high availability has a positive impact on the cost of electricity.

The major factors affecting plant availability and reliability are: Design of the major components

Engineering of the plant as whole, especially of the interfaces between the systems

Mode of operation (whether base, intermediate, or peak-load duty)

Type of fuel Type of fuel

Qualifications and skill of the operating and maintenance staff

Adherence to manufacturers operating and maintenance instructions (preventive maintenance)


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C i f O i d M i C

6. Low O&M Cost [1/4]

Type of Plant Output (MW) Fixed (Million US$/ )Variable

(US$/MWh)

Comparison of Operating and Maintenance Cost

yp p ( ) US$/year) (US$/MWh)

Combined Cycle Power Plant 800 6~8 2~3

Combined Cycle Power Plant 60 3~4 3~4y

Gas Turbine Plant 250 2~2.5 3~4

Gas Turbine Plant 60 1~1.5 4~5

Steam Power Plant (coal) 800 12~15 2.5~3.5

Nuclear Power Plant 1250 40~60 2.0

Biomass Power Plant 30 3~4 5~8

Fixed O&M: personnel and insurance costs. Variable O&M: cost depending upon the operation regime of the plant. Included items are:Variable O&M: cost depending upon the operation regime of the plant. Included items are: Inspection and overhauls, including labor, parts, and rentals Water treatment expenses Catalyst replacement Major overhaul expences


Major overhaul expences Air filter replacements

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C i f O i d M i C

6. Low O&M Cost [2/4]

Source: GE (1991)

Comparison of Operating and Maintenance Cost

Items Simple cycleCombined

cycle Steam coal IGCC

Fuel type NG NG Coal Coal

Fuel cost ($/MBtu) 2.65 2.65 1.5 1.5

Fixed O&M cost ($/kW/year) 0.7 3.7 28.1 38.8

Variable O&M cost ($/MWh) 7.3 3.3 2.7 3.7

Normalized plant cost 1.14 1 4.40 6.07

Some estimate that burning residual or crude oil will increase maintenance costs by a factor of 3, (summing a base of 1 for natural gas, and by a factor of 1.5 for distillate) and that those costs will ( g g , y )be three times higher for the same number of fired hours if the unit is started every fired hour, instead of once every 1000 fired hours.


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6. Low O&M Cost [3/4] O&M costs include operating labor, materials, and tools for plant maintenance on both a routine and

emergency basis.

These expenses are neither a function of plant capital cost nor plant generating capacity.p p p p g g p y

They vary from year to year and generally become higher as the plant becomes older.

These costs also vary according to the size of plant type of fuel used loading schedule and operating These costs also vary according to the size of plant, type of fuel used, loading schedule, and operating characteristics (peaking or base load).

In general, O&M costs are approximately equal to one-fourth of the fuel costs.

A good rule of thumb is that the maintenance cost is twice the initial cost during the plant life (normally, 25 years).

The running profile has a profound impact on the O&M cost The running profile has a profound impact on the O&M cost.

Usually, the first maintenance is scheduled for either 24,000 hours or 1,200 starts (whichever occurs first).

Nowadays it is common to have a maintenance agreement at some level for risk mitigation Nowadays, it is common to have a maintenance agreement at some level for risk mitigation.

There are different levels of contractual services ranging from part agreement to full coverage LTSA services.


One can choose to use either the OEM or another third party service provider.

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6. Low O&M Cost [4/4] In many cases, financing organs or insurer requires and LTSA (or better) for risk mitigation to level the

insurance cost at a reasonable level.

There are ways of potentially reducing the maintenance cost and one should always lumped methods with equivalent hours.

The word lumped is used in a sense that the two different ageing mechanisms, such as creep, oxidation, regular wear and tear and stresses related to thermal gradients during start and stop, are evaluated as equivalent time by e.g. assuming that a start consumes time rather being a low cycle.

The total number of gas turbine operated in the world is about 47,000 units and the total value of the gas turbine after market was 19.3 billion USD in 2009.

The after market is valuable greatly to the manufacturers since all 47,000 units requires maintenance on a regular basis.

Certain in-house produced parts may be offered with several hundred percent margin. In contrast, the margin of a complete new turn-key power plant is about 10 percent.


The reward for the user, by having a LTSA, is discounted parts and prioritized treatment by the supplier.

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7. Operating Flexibility [1/11]

Mode Baseload Plant (1990s) SCC5-4000F cycling plant (Siemens)Hot start (8 h) 90 min 45-55 min

Warm start (64 h) 200 min 120 min

C ld t t ( 120 h) 250 i 150 iCold start (>120 h) 250 min 150 min

Operational flexibility is essential in combined cycle power plants for frequency control.

Most OEMs are capable of 30 min hot-start and steep (35-50 MW/minute) ramp-rates.

The steam cooled gas turbine gas a longer start-up time. Thus, is has less flexibility in terms of DSS.


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7. Operating Flexibility [2/11] Gas turbines as well as combined cycle power plants have the unique potential to react quickly and with

flexibility to changes in grid, because they have the following characteristics:

Short startup time High-loading gradients Possibilities for frequency support

Operational flexibility becomes a major topic in modern power

k t Good part load behavior Additional system for power augmentation

B ilt f b th b l d d k l d ti

markets

Built for both base-load and peak-load operation

High efficiency to maximize generation opportunities

Lower start-up emissions

Lower demineralized water consumption

Once-through HRSG


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7. Operating Flexibility [3/11][ Start-up procedure ]


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Hot start (start after an 8-hour shutdown) of a 400 MW CCPP with optimized steam turbine start-up technology (Siemens)


HIPT


5 additional30 min. to baseload

30 MW/min 5 additional minutes to 150 MW

5 minutes to accelerate

13.5 minutes to accelerate

Improved

accelerate to accelerate

Improvement of SGT6-5000F (W501F) Starting Capability


Improvement of SGT6-5000F (W501F) Starting Capability

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HIPT

7. Operating Flexibility [7/11] Gas turbines are capable of relatively quick starts.

Heavy duty gas turbines can achieve starting times as low as 10 minutes but usually no higher than 30 minutes from cold start to 100% load.

Aeroderivative gas turbines can achieve 100% load in 3 minutes or less.

If equipped with bypass systems, the startup of the steam cycle portion of the combined cycle can be t d f th t biseparated from the gas turbine.

The gas turbine can be operated at full load while the steam turbine is warming up.

The HRSG can be warmed up nearly as quickly as the gas turbine with excess steam produced being The HRSG can be warmed up nearly as quickly as the gas turbine, with excess steam produced being bypassed to the condenser.

The startup time of the gas turbine and the combined cycle plant is significantly less than the time required for a comparably sized coal-fired power plantfor a comparably sized coal-fired power plant.

Supercritical plants require feedwater purity so that tube side deposition will not cause overheating damage.

Condensate polishing with oxygenated water treatment is required to achieve excellent water purity.p g yg q p y

Even many natural circulation (drum type) units now use oxygenated water treatment.

The deposition has been greatly reduced so that the requirement for frequent chemical cleaning is almost


eliminated.

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7. Operating Flexibility [8/11] For rapid changes in gas temperature, the edges of the bucket or nozzle respond more quickly than

the thicker bulk section.

These gradients, in turn, produce thermal stress that, when cycled, can eventually lead cracking.

Turbine start/stop cycle firing temperature changes Transient temperature distribution (1st stage bucket)


HIPT

B k L C l F i (LCF) T S i Hi


Key Parameters

Bucket Low Cycle Fatigue (LCF) Temperature Strain History

FSNL

Fired Shutdown

T

e

n

s

i

l

e

(

+

)

Key Parameters Total strain range Max metal temperature

Tm

FSNL

r

a

i

n

T

Metal Temperaturem

%

S

t

r

max Base Load

r

e

s

s

i

v

e

(

)

Light Off & Warm-up

Acceleration

C

o

m

p

r


HIPT

7. Operating Flexibility [10/11] Currently, short start-up and shutdown times are emphasized by customers because of high fuel price. Especially, fast start-up is important for intermediate load application. The important parameters should be considered for fast start-up are as follows:

HRSG ramp capability Steam turbine ramp capabilityp p y Piping warm up times Steam chemistry Steam turbine back-pressure limitations


HIPT

HRSG

7. Operating Flexibility [11/11]HRSG

There has also been a debate over the years whether the once-through HRSG technology should be better off than drum boilers in terms of cyclingthan drum boilers in terms of cycling.

Detailed transient analysis showed that the majority of fatigue life consumption occurs at the hottest high pressure superheater and reheater during fast gas turbine loading

GE

the hottest high pressure superheater and reheater during fast gas turbine loading, regardless of whether the HRSG uses high pressure drum or once through technology.

The HRSG stack is equipped with an automatic damper that closes upon plant shutdown to reduce HRSG heat loss and the time required for next plant start-up as well as reduce thereduce HRSG heat loss and the time required for next plant start up, as well as reduce the cyclic stress of the start.

Once through HRSG eliminates the thick wall HP drum and allows an unrestricted gas

Siemens

Once-through HRSG eliminates the thick wall HP drum and allows an unrestricted gas turbine start-up.a. gas turbine start-up produces rapid boiling in the evaporatorb. if water level in the drum rises to the separators, water carry over into the superheaterp , y p

may occurc. the typical response to this is to either trip or slow gas turbine load ramp


It is hard to conclude that which one is better in terms of operating flexibility.

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8. Lower Emissions [1/6]Pollutants characteristics

Smoke Smoke is usually formed in small fuel rich regions especially during start-up.

Unburned hydrocarbons The unburned hydrocarbons and CO are formed incomplete combustion and CO typically at idling conditions.

CO2 production is a direct function of the CHx fuels burned it produces 3.14 times the fuel burned

CO2times the fuel burned.

The only way to reduce the production of CO2 is to use less fuel for the power produced.

NOx have been major pollutant in modern gas turbines.

New units under development have goals which would reduce NOx levels below 9 ppmNOx below 9 ppm.

SCRs have also been used in conjunction with DLN combustors.

New research of catalytic combustors will give 2 ppm in the future.


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E i i [N 2 Oil]

8. Lower Emissions [2/6]Emission [No. 2 Oil]

4000 300

High SmokeEmissions

High CO Emissions

3000F

e

,

p

p

m

v

a

n

d

3000

m

e

T

e

m

p

.

,

200

N

O

x

R

a

t

e

c

o

n

d

i

t

i

o

n

O

p

t

i

m

u

m

B

2000Fl

a

100

c

h

i

o

m

e

t

r

i

c

O

1000

S

t

o

i


0.5 1.51.0Equivalence Ratio

Fuel richFuel lean

HIPT

W /S I j i

8. Lower Emissions [3/6] Most gas turbines control NOx emission with diluent injection into the combustor until 1990.

The injected diluent used as a heat sink that lowers the combustion zone temperature which is the primary

Water/Steam Injection

The injected diluent used as a heat sink that lowers the combustion zone temperature, which is the primary parameter affecting NOx formation.

As the combustion zone temperature decreases, NOx production decreases exponentially.

In order to increase thermal efficiency, gas turbines having higher firing temperature has being developed by manufacturers.

H hi h fi i t t hi h b ti t t hi h d NO However, higher firing temperature mean higher combustion temperatures, which produce more NOx, resulting in more diluent injection to achieve the same emission levels of NOx.

The increased diluent injection lowers the thermal efficiency because some of the energy of combustion i d t h t th t tgases is used to heat the water or steam.

Furthermore, as injection increases, dynamic pressure oscillation activity (i.e., noise) in the combustor also increases, resulting in increased wear of internal parts.

Carbon monoxide, representing the measure of the inefficiency of the combustion process, also increases as the diluent injection increases.


The lowest practical NOx levels achieved with diluent injection are generally 25 ppm and 42 ppm when firing natural gas and distillate oil, respectively.

HIPT

L NO E i i

8. Lower Emissions [4/6]

CCPP includes gas turbines with DLN combustors that can operate with stack gas NOx emission concentration as low as 9 ppmvd at 15% oxygen without steam or water injection, when the natural gas is

f

Lower NOx Emissions

used as a fuel.

Water or steam injection may be required to meet NOx emission requirements, when distillate is used as a fuel.

Water or steam injection can be used in the gas turbines with diffusion flame combustors to meet NOxemission limits.

NOx can be reduced to less than 9 ppmvd by the installation of SCR in the HRSG.

Lower CO Emissions Carbon monoxide (CO) emissions are low at gas turbine loads above 50%, typically less than 5~25 ppmvd

(9~43 g/GJ).

Low CO emissions are the result of highly-efficient combustion.

Catalytic CO emission abatement systems are also available, if required.


The CO catalyst is installed in the exhaust gas path, typically upstream of the HRSG superheater.

HIPT

L CO E i i


The role of gas turbine has changed from either a special application or stand-by mode to combined cycle plants in either intermediate or base load.

Lower CO2 Emissions

The high efficiency combined with natural gas high hydrogen content result in relatively low levels of specific CO2 emission.

Unfortunately, however, the relative lower CO2 content in the flue gas makes the separation process more difficult, and may render in high separation tower heights to provide for sufficient residence time.

Another issue is the flue gas flow which is on the order of 1.5 kg/MW, compared to 0.95 kg/MW for than advanced steam plants.

The cross section of the separation tower should provide for a velocity around 5 m/s Therefore a combined The cross section of the separation tower should provide for a velocity around 5 m/s. Therefore, a combined cycle plant requires a higher and wider tower for CO2 capture plant compared to a coal fired plant.

No commercial full-scale technology for CO2 capture exists today and the road-maps towards feasible solution are still not clear.

It has been expected that the efficiency of combined cycle power plant with CO2 capture plant will drop 8 percent for a GE 9FB.03 with a 3-pressure HRSG. This is because a lot of LP steam is required for solvent


percent for a GE 9FB.03 with a 3 pressure HRSG. This is because a lot of LP steam is required for solvent regeneration.

HIPT

CO E i i f Diff P Pl


Lignite: 980~1,230

CO2 Emissions from Different Power Plants

Hard coal: 790~1,080

Oil: 890

NG: 640

NG Comb. cycle 410~430

Unit: g CO2/kWh

Solar 80~160

Nuclear: 16~23

Wind: 8~16

Hydro power: 4~13

Electricity generation with CCS

The CO2 emissions of the plant are having a more direct impact on the economics of a plant due to the effort to globally limitation.

The combined cycle plant emits about 40% of the CO of a coal fired plant This is driven by the higher


The combined cycle plant emits about 40% of the CO2 of a coal-fired plant. This is driven by the higher efficiency and the higher hydrogen content in natural gas.

HIPT

9. Options for Power Enhancements

O ti f P E h tTypical Performance Impact

Output = m h

Options for Power Enhancements Output Heat RateBase configuration Base Base

Evaporative cooling GT inlet air (85% effective cooler) +5.2 % -

Chill GT inlet air to 45F +10.7 % +1.6 %GT k l d i 2 % 1 0 %GT peak load operation +5.2 % 1.0 %GT steam injection (5% of GT airflow) +3.4 % +4.2 %

GT water injection (2 9% of GT airflow) +5 9 % +4 8 %GT water injection (2.9% of GT airflow) +5.9 % +4.8 %

HRSG supplementary firing +28 % +9 %

Note: 1. Site conditions = 90F, 30% RH(Relative Humidity)2. Fuel = NG3. 3-pressure, reheat steam cycle


HIPT

C i i h C l Fi d P Pl

10. Compactness [1/8]

BoilerFeedwater

Steam Turbine

Comparison with Coal-Fired Power Plants

FeedwaterPump

Turbine

10 Meters


HIPT

A f Si l Sh f [GE]

10. Compactness [2/8]Arrangement of Single-Shaft [GE]

[ Single-Shaft CCPP (107FA) ]


HIPT

A f M l i Sh f [207FA GE]

10. Compactness [3/8]Arrangement of Multi-Shaft [207FA GE]


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10. Compactness [4/8]Single Shaft (1-on-1 configuration) Multiple Shaft (2-on-1 configuration)

ComponentsLess generator required One large ST instead of 2 smaller STs

ComponentsOne compact lube oil system Less auxiliaries (pumps etc) required

Civil Smaller plant area Higher flexibility in plant layout

L i l f l bCosts

Lower capital cost of plant because one generator and one step-up transformer is eliminated

St t bi h hi h ffi i bPerformance Same level in larger plants Steam turbine has higher efficiency because of larger steam volume flow

Operating Fl ibilit

Suitable for daily start and stop (DSS) ti Suitable for base load operationFlexibility operation p

Availability Higher (less complexity)

Operation limit

Operation is limited to concurrent operation of the gas turbine and steam turbine, unless the steam turbine can be decoupled from the generator through a clutch

The gas turbine can be decoupled from the operation of the steam turbine, allowing for steam turbine shutdown with continued gas turbine operation


generator through a clutch turbine operation

HIPT

A f Si l Sh f [Si ]

10. Compactness [5/8]Arrangement of Single-Shaft [Siemens]


HIPT

Si l Sh f

10. Compactness [6/8]

Single-shaft with generator between gas turbine and steam turbine enables installation of a clutch between steam turbine and generator.

Single-Shaft

One problem of a Jaw clutch, which was used previously, is that it can only be engaged when the gas turbine is at rest. This means that in the event of a failed gas turbine start, the operator must wait until the gas turbine is stationary before engaging the jaw clutch to re-start.

Currently, SSS(Synchronous Self-Shifting) clutch has been employed popularly. The SSS clutch engages in that moment when the steam turbine speed tries to overrun the rigidly coupled gas turbine generator and disengages if the torque transmitted from the steam turbine to the generator becomes zero.

The clutch allows startup and operation of gas turbine without driving the steam turbine.

This results in a lower starting power and eliminates certain safety measures for the steam turbine, such as g ycooling steam or sealing steam.

The clutch also provides design opportunities for accommodating axial thermal expansion.

However, the clutch is an additional component with a potential impact on availability. Additionally, the generator located at the end of the line of shafting has advantages during generator overhaul.

Single-shaft units without a clutch definitely need auxiliary steam supply to cool the steam turbine during


Single shaft units without a clutch definitely need auxiliary steam supply to cool the steam turbine during startup. This is not necessary in units with a clutch.

HIPT

A f Si l Sh f [GE 6FA]

10. Compactness [7/8]Arrangement of Single-Shaft [GE, 6FA]

A b i i li ti hA gearbox is necessary in applications where the manufacturer offers the package for both 60 and 50 cycle applications. The gearbox will use roughly 2 percent of the power produced b th t biby the turbine.


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T i l Pl A [GE S207EA]

10. Compactness [8/8]Typical Plant Arrangement [GE, S207EA]


HIPT




HIPT

C i [1/2]

Wide Use of Gas Turbine

Cogeneration means the simultaneous production of electricity and thermal energy in the same plants.Cogeneration [1/2]

The thermal energy is usually steam or hot water.

The types of cogeneration plants:

Industrial power stations supplying heat to an industrial process

District heating power plants

Power plants coupled to seawater desalination plants

The supplementary firing in the HRSG gives greater design and operating flexibility, but the cycle efficiency is normally lower if supplementary firing is used.y pp y g

Thermal energy in the form of steam can be extracted from HRSG, or from an extraction in the steam turbine.

The power coefficient (also called the alpha-value) is defined as the ratio between the electrical and the thermal output.

Fuel utilization is a measure of how much of the fuel supplied is usefully used in the plant It is equal to the


Fuel utilization is a measure of how much of the fuel supplied is usefully used in the plant. It is equal to the sum of electrical output and thermal output divided by the fuel input.

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C i [2/2]

Wide Use of Gas TurbineCogeneration [2/2]

Single PressureSupplementary FiringB k T bi

Heat Balance

Backpressure Turbine


HIPT

S D li i Pl

Wide Use of Gas TurbineSeawater Desalination Plant


HIPT

P ll l P i

Wide Use of Gas TurbineParallel Powering


Parallel powering: Gas turbine exhausts are used in the existing steam cycle.

HIPT

IGCC

Wide Use of Gas TurbineIGCC


HIPT

Load Control & Frequency Response Combined cycle plants are very well suited to rapid load changes because gas turbine react extremely

quickly to frequency variations.

As soon as fuel valve opens more added power becomes available on the shaft and gas turbine load jumps As soon as fuel valve opens, more added power becomes available on the shaft and gas turbine load jumps of up to 35% are possible, but this is detrimental to the life expectancy of the turbine blades.

To perform a plant load jump while the frequency is falling, it is essential that gas turbine is operating below the maximum output levelthe maximum output level.

For frequency support gas turbines are typically operated between 50 and 95% load.

The electrical output of the combined cycle power plants is controlled by means of gas turbine only This is The electrical output of the combined cycle power plants is controlled by means of gas turbine only. This is because the gas turbine generates two-thirds of the total power output, a solution without control for the steam turbine power output is generally preferred.

The gas turbine output is controlled by a combination of VIGV and TIT control The gas turbine output is controlled by a combination of VIGV and TIT control.

The TIT is controlled by a combination of the fuel flow into the combustor and VIGV setting.

VIGV ll hi h t bi h t t t d t i t l 40% GT l d B l thi l l VIGVs allows a high gas turbine exhaust temperature down to approximately 40% GT load. Below this level, TIT is further reduced because the airflow cannot be further reduced.

The steam turbine will always follow the gas turbine by generating power with whatever steam is available.


HIPT

: (): 2014 03 03 (Ver 3)


: 2014. 03. 03 (Ver.3): ebyeong @ naver.comMobile: 010-3122-2262: /

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