PB Power

Gas Turbine Inlet Air Cooling System

The 3rd Annual Australian Gas Turbine Conference

6th – 7th December 2001MelbourneAustralia

Presented by

Bob OmidvarManager, Power Engineering

PB Power Australia

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75%

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110%

0 5 10 15 20 25 30 35 40 45GT Inlet Temp (deg C)

Heat rate kJ/kWh Power output MW Exhaust flow t/h Exhaust temperature °C

Heavy Duty GT - Effects of Ambient Temp

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0 5 10 15 20 25 30 35 40 45

GT Inlet Temp (deg C)

Exhaust temperature C Heat rate kJ/kWh Power output MW Exhaust flow t/h

Aero-Derivative GT - Effects of Ambient Temp

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Gas Turbine Performance Design BasisWhat Does ISO Condition Mean?

! Dry bulb 15°C

! Relative humidity 60%

! Wet bulb temperature 7.2°C

! Atmospheric pressure 1 bar (sea level)

Most of the gas turbine installations are not in ISO standard locations, they are in the real world

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Ambient Air and Gas Turbine Performance

1. Air density is inversely related to the dry bulb temperature

2. Gas turbine output depends on mass flow and not the volume of air

3. Ambient temperature affects the following points drastically

" Air flow

" Output

" Heat rate

" Exhaust temperature

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Gas Turbine Inlet Air CoolingAvailable Technologies

1. Evaporative cooler2. Fogging system3. Mechanical refrigeration system (direct type)4. Mechanical refrigeration system (indirect type)5. Mechanical refrigeration with ice storage6. Mechanical refrigeration system with chilled water storage7. Single stage Lithium Bromide Absorption chiller8. Two stage Lithium Bromide Absorption chiller

PB Power

Gas Turbine Inlet Air CoolingAvailable Technologies

1. Evaporative cooler2. Fogging system3. Mechanical refrigeration system (direct type)4. Mechanical refrigeration system (indirect type)5. Mechanical refrigeration with ice storage6. Mechanical refrigeration system with chilled water storage7. Single stage Lithium Bromide Absorption chiller8. Two stage Lithium Bromide Absorption chiller

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Fuel

Combustion Turbine

Water Tank

CombustionAir

WettedMedia

Schematic of Evaporative Air Coolingshown with Optional Water Treatment

Exhaust GasBlow down

WaterTreatment

MakeUp

AirFilter

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Evaporative CoolerApplications: Areas where RH and wet bulb temperature is rather low

Advantage# Lowest capital cost

# Lowest O&M cost

# Can operate on raw water

# Quick delivery and installation time

# Operates as an air washer and cleans the inlet air

Disadvantage# Limitation on capacity

improvement

# Highly influenced by the site wet bulb

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Gas Turbine Inlet Air CoolingAvailable Technologies

1. Evaporative cooler2. Fogging system3. Mechanical refrigeration system (direct type)4. Mechanical refrigeration system (indirect type)5. Mechanical refrigeration with ice storage6. Mechanical refrigeration system with chilled water storage7. Single stage Lithium Bromide Absorption chiller8. Two stage Lithium Bromide Absorption chiller

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Fuel

Combustion Turbine

DemineralisedWater Tank

CombustionAir

FogSpray

System

Schematic of Fog Inlet Air Cooling SystemUtilizing Demineralised Water

DemineralisedWater Treatment

Plant

RawWater

Exhaust Gas

AirFilter

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Fog Systems

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Demineralised Water Quality For Fog System Inlet Air Cooling

Total dissolved solids

pH

Na + K

5 PPM maximum

6-8

0.1 PPM maximum

Silica (SiO2)

Chlorides

Sulphate

0.1 PPM maximum

0.5 PPM maximum

0.5 PPM maximum

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0 25 50 75 100 125 150 175 200 225 250

Gas Turbine Output MW

t/h

Fogging System Demin. Water ConsumptionInlet air 36°C DB, 25°C WB

Chilled air temp 25.5°C DB 25°C WB, 96%RH

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Fogging SystemApplications: Areas where RH and wet bulb temperature is rather low

Advantage# Low capital cost

# Low O&M cost

# Can increase gas turbine performance better than evaporative cooling

# Quick delivery and installation time

Disadvantage# Limitation on capacity

improvement

# Highly influenced by the site wet bulb

PB Power

Gas Turbine Inlet Air CoolingAvailable Technologies

1. Evaporative cooler2. Fogging system3. Mechanical refrigeration system (direct type)4. Mechanical refrigeration system (indirect type)5. Mechanical refrigeration with ice storage6. Mechanical refrigeration system with chilled water storage7. Single stage Lithium Bromide Absorption chiller8. Two stage Lithium Bromide Absorption chiller

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Fuel

Combustion Turbine

AmmoniaLiquid Line

MechanicalRefrigeration

Machine

CombustionAir

AmmoniaSuction Line

Schematic of a Direct SystemUsing an Ammonia Refrigeration Machine

Exhaust Gas

AirFilter

CondensateDrip Pan

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Mechanical Refrigeration System (Direct Type)Applications: Areas where relative humidity is rather high

Advantage# Can increase gas turbine

performance better than evaporative cooling, and fog system

Disadvantage# High initial capital cost

# High O&M cost

# Longer delivery and installation time

# Expertise is needed to operate and maintain the plant

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Gas Turbine Inlet Air CoolingAvailable Technologies

1. Evaporative cooler2. Fogging system3. Mechanical refrigeration system (direct type)4. Mechanical refrigeration system (indirect type)5. Mechanical refrigeration with ice storage6. Mechanical refrigeration system with chilled water storage7. Single stage Lithium Bromide Absorption chiller8. Two stage Lithium Bromide Absorption chiller

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Fuel

Combustion Turbine

Chilled WaterPump

Mechanical Chiller

CombustionAir

Air CoolingCoil

Schematic of an Indirect SystemUsing a Mechanical Chiller

Exhaust Gas

AirFilter

CondensateDrip Pan

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Mechanical Refrigeration System (Indirect Type)Applications: Areas where relative humidity is rather high

Advantage# Can increase gas turbine

performance better than evaporative cooling, and fog system

# Not very sensitive to ambient air wet bulb temperature

Disadvantage# High initial capital cost# High O&M cost# Long delivery and installation

time# Expertise is needed to

operate and maintain the plant

# Requires extra chilled water cooling circuit

# Higher parasitic load than direct type

# Higher energy input compared to direct type chiller

PB Power

Gas Turbine Inlet Air CoolingAvailable Technologies

1. Evaporative cooler2. Fogging system3. Mechanical refrigeration system (direct type)4. Mechanical refrigeration system (indirect type)5. Mechanical refrigeration with ice storage6. Mechanical refrigeration system with chilled

water storage7. Single stage Lithium Bromide Absorption chiller8. Two stage Lithium Bromide Absorption chiller

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Fuel

Combustion Turbine

Chilled WaterPump

Mechanical Chiller/Ice Maker

CombustionAir

Air CoolingCoil

Inlet Air Cooling With Ice Storage,Chilled Water Storage System Schematic

Ice Storage Tank

Exhaust Gas

AirFilter

CondensateDrip Pan

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Fuel

Combustion Turbine

Chilled WaterPump

ChilledWater

StorageTank

Mech.Chiller

CombustionAir

Air CoolingCoil

Inlet Air Cooling With Chilled Water StorageSystem Schematic

Exhaust Gas

AirFilter

CondensateDrip Pan

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Mechanical Refrigeration SystemWith Ice Storage

Applications: Areas where RH is rather high,plus a wide variation in electricity tariff between peak and non peak hours

Advantage# Can increase gas turbine

performance better than evaporative cooling, and fog system

# Not very sensitive to ambient air wet bulb temperature

# Can utilise low night time tariff to produce and store ice for peak hours operation

Disadvantage# High initial capital cost# High O&M cost# Longer delivery and

installation time# Higher expertise is needed

to operate and maintain the plant

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0 25 50 75 100 125 150 175 200 225 250 275 300

Gas Turbine Output MW

Chi

ller E

lect

rical

Loa

d M

WChiller Electrical Load MW

36°C DB, 25°C WB, 10°C Chilled Air Temp

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Gas Turbine Inlet Air CoolingAvailable Technologies

1. Evaporative cooler2. Fogging system3. Mechanical refrigeration system (direct type)4. Mechanical refrigeration system (indirect type)5. Mechanical refrigeration with ice storage6. Mechanical refrigeration system with chilled water storage7. Single stage Lithium Bromide Absorption chiller8. Two stage Lithium Bromide Absorption chiller

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Fuel

Combustion Turbine

Chilled WaterPump

Absorption Chiller

CombustionAir

Air CoolingCoil

Absorption Chiller Inlet Air CoolingSystem Schematic

Heat RecoverySteam Generator

Exhaust Gas

AirFilter

CondensateDrip Pan

LP S

team

Ret

urn

Con

dens

ate

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6°C

12°C

Chilled Water

Tower Water In

Tower Water Out

Heat Medium Out

Heat Medium In Steam or Hot Water

tc 45°C

95°C

70°C

to 4°C

Condenser

Generator

Pressure approx.60 Torr60 mm Hg80 mbar8 kPa

Pressure approx.6,2 Torr6,2 mm Hg8,2 mbar0,83 kPa

ta 35°C

Evaporator

Absorber

50°C

70°C

27°C

32,5°C

37°C

Refrigerant (Water)Steam or Hot WaterDiluted Solution (LiBr)Concentrated Solution (LiBr)Tower WaterChilled Water

Flow Diagram

Picture courtesy of York International

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Gas Turbine Output MW

Stea

m C

onsu

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t/h

Single StageTwo Stage

Absorption Chiller Steam Consumption36°C DB, 25°C WB, 10°C Chilled Air Temp

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Single Stage Lithium Bromide Absorption ChillerApplications: Areas where relative humidity is rather high, and the plant is going to operate in a combined cycle or cogeneration mode and has

access to low pressure steamAdvantage# Can increase gas turbine

performance better than evaporative cooling, and fog system

# Not very sensitive to ambient air wet bulb temperature

# Low electrical parasitic load

Disadvantage# High initial capital cost# High O&M cost# Longer delivery and

installation time# High expertise is needed to

operate and maintain the plant

# In case of a steam operated chiller, cannot be applied in an open cycle gas turbine plant

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Two Stage Lithium Bromide Absorption ChillerApplications: Areas where relative humidity is rather high, and the plant is going to operate in a combined cycle or cogeneration mode and has

access to low pressure steamAdvantage# Can increase gas turbine

performance better than evaporative cooling, and fog system

# Not very sensitive to ambient air wet bulb temperature

# Low electrical parasitic load# Requires less steam per unit

of refrigeration than single stage chiller

Disadvantage# High initial capital cost# High O&M cost# Longer delivery and

installation time# High expertise is needed to

operate and maintain the plant

# In case of a steam operated chiller, cannot be applied in an open cycle gas turbine plant

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Gas Turbine Output MW

Con

dens

ate

Form

atio

n t/h

Condensate Formation on the Chilled Water Coil t/hBased on 36°C DB, 25°C WB, 10°C Chilled Inlet Air

Temperature

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Performance EvaluationOf Different Inlet Air Cooling Systems

Base Condition! 35°C Dry bulb! 25°C Dry bulb Real world condition! 44.7% Relative humidity

Increase in power output

Gas turbine output before inlet air cooling

Gas turbine output with mechanical refrigeration system and inlet air

temperature of 10°C

Gas turbine with evaporative cooler running at 85% RH

Gas turbine with fog system running at 100% RH

0%108.23 MW (net)

Percent Change

15.3%124.8 MW (net including chiller electrical load)

6%114.8 MW (net)

7.69%116.65 MW (net)

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Capital Cost Comparisons ofInlet Cooling Systems

Options

Evaporative cooler

Fog system (excluding water treatment plant)

Relative Costs

1

2Single stage LiBrabsorption chillerTwo stage LiBrabsorption chillerAmmonia mechanical refrigeration system

8

10

9.5

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Major Contributors To The O&M CostsOptionsEvaporative cooler

Fog system (excluding water treatment plant)

O&M Costs# Make up water# Water treatment (if applicable)# Make up water# Demineralised water treatment# Injection pump power consumption

Single stage LiBrabsorption chiller

Two stage LiBr absorption chiller

Ammonia mechanical refrigeration system

# Steam# Cooling tower chemical treatment# Chiller maintenance# Electric power consumption# Steam# Cooling tower chemical treatment and

make up water# Chiller maintenance# Electric power consumption# Electric power consumption# Cooling tower chemical treatment and

make up water# Chiller maintenance

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Heavy Duty Gas Turbine NOx Emission kg/MWhGT with Dry Low NOx burner

0.410

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0 5 10 15 20 25 30 35 40 45

Ambient Temperature deg C

NO

xEm

issi

on k

g/M

Wh

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Heavy Duty Gas Turbine CO2 Emission kg/MWh

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Ambient Temperature deg C

CO

2Em

issi

on k

g/M

Wh

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Aero-Derivative Gas Turbine NOx Emission kg/MWhGT with Dry Low NOx burner

0.37

0.38

0.39

0.4

0.41

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Ambient Temperature deg C

NO

xEm

issi

on k

g/M

Wh

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Aero-Derivative Gas Turbine CO2 Emission kg/MWh

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550

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Ambient Temperature deg C

CO

2Em

issi

on k

g/M

Wh

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In Selecting Inlet Air Cooling As A Retrofit To An Existing Plant

Points to watch:! Check the generator capacity in order not to overload the

generator

! Quality of raw water for the evaporative cooler

! When using an existing demineralised water treatment plant, be careful about the capacity and quality of available demineralised water

! With an existing heat recovery steam generator, inlet air cooling will change the behaviour of the existing HRSG, leading to a drop in steam production at high pressure and increase in intermediate and low pressure steam