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Gas Turbine Inlet Air Cooling SystemThe 3rd Annual Australian Gas Turbine Conference6th 7th December 2001 Melbourne Australia Presented by

Bob Omidvar Manager, Power Engineering PB Power AustraliaPB Power

Heavy Duty GT - Effects of Ambient Temp110% 105% 100% 95% 90% 85% 80% 75% 0 5 10 15 20 25 30 35 40 45

GT Inlet Temp (deg C)Heat rate kJ/kWh Power output MW Exhaust flow t/h Exhaust temperature C

PB Power

Aero-Derivative GT - Effects of Ambient Temp

120% 110% 100% 90% 80% 70% 60% 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

PB Power

Gas Turbine Performance Design BasisWhat Does ISO Condition Mean?! ! ! !

Dry bulb 15C Relative humidity 60% Wet bulb temperature 7.2C Atmospheric pressure 1 bar (sea level)

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

PB Power

Ambient Air and Gas Turbine Performance1. 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

PB Power

Gas Turbine Inlet Air CoolingAvailable Technologies1. Evaporative cooler 2. Fogging system 3. Mechanical refrigeration system (direct type) 4. Mechanical refrigeration system (indirect type) 5. Mechanical refrigeration with ice storage 6. Mechanical refrigeration system with chilled water storage 7. Single stage Lithium Bromide Absorption chiller 8. Two stage Lithium Bromide Absorption chiller

PB Power

Gas Turbine Inlet Air CoolingAvailable Technologies1. Evaporative cooler 2. Fogging system 3. Mechanical refrigeration system (direct type) 4. Mechanical refrigeration system (indirect type) 5. Mechanical refrigeration with ice storage 6. Mechanical refrigeration system with chilled water storage 7. Single stage Lithium Bromide Absorption chiller 8. Two stage Lithium Bromide Absorption chiller

PB Power

Schematic of Evaporative Air Cooling shown with Optional Water TreatmentCombustion Air Air Filter Water Treatment Make Up Blow down Wetted Media

Water Tank

Exhaust Gas

Fuel

Combustion Turbine

PB Power

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

Advantage# # # #

Disadvantage#

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

Limitation on capacity improvement Highly influenced by the site wet bulb

#

#

PB Power

Gas Turbine Inlet Air CoolingAvailable Technologies1. Evaporative cooler 2. Fogging system 3. Mechanical refrigeration system (direct type) 4. Mechanical refrigeration system (indirect type) 5. Mechanical refrigeration with ice storage 6. Mechanical refrigeration system with chilled water storage 7. Single stage Lithium Bromide Absorption chiller 8. Two stage Lithium Bromide Absorption chiller

PB Power

Schematic of Fog Inlet Air Cooling System Utilizing Demineralised WaterRaw Water Demineralised Water Treatment Plant Demineralised Water Tank

Combustion Air Air Filter Fog Spray System

Exhaust Gas

Fuel

Combustion Turbine

PB Power

Fog Systems

PB Power

Demineralised Water Quality For Fog System Inlet Air CoolingTotal dissolved solids pH Na + K Silica (SiO2) Chlorides Sulphate 5 PPM maximum 6-8 0.1 PPM maximum 0.1 PPM maximum 0.5 PPM maximum 0.5 PPM maximum

PB Power

Fogging System Demin. Water Consumption Inlet air 36C DB, 25C WB Chilled air temp 25.5C DB 25C WB, 96%RH

10 9 8 7 6 5 4 3 2 1 0 0 25 50 75 100 125 150 175 200 225 250

t/h

Gas Turbine Output MW

PB Power

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

Advantage# # #

Disadvantage#

Low capital cost Low O&M cost Can increase gas turbine performance better than evaporative cooling Quick delivery and installation time

Limitation on capacity improvement Highly influenced by the site wet bulb

#

#

PB Power

Gas Turbine Inlet Air CoolingAvailable Technologies1. Evaporative cooler 2. Fogging system 3. Mechanical refrigeration system (direct type) 4. Mechanical refrigeration system (indirect type) 5. Mechanical refrigeration with ice storage 6. Mechanical refrigeration system with chilled water storage 7. Single stage Lithium Bromide Absorption chiller 8. Two stage Lithium Bromide Absorption chiller

PB Power

Schematic of a Direct System Using an Ammonia Refrigeration MachineAmmonia Suction Line

Mechanical Refrigeration Machine

Combustion Air Air Filter Condensate Drip Pan Ammonia Liquid Line

Exhaust Gas

Fuel

Combustion Turbine

PB Power

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

Advantage#

Disadvantage# # #

Can increase gas turbine performance better than evaporative cooling, and fog system

High initial capital cost High O&M cost Longer delivery and installation time Expertise is needed to operate and maintain the plant

#

PB Power

Gas Turbine Inlet Air CoolingAvailable Technologies1. Evaporative cooler 2. Fogging system 3. Mechanical refrigeration system (direct type) 4. Mechanical refrigeration system (indirect type) 5. Mechanical refrigeration with ice storage 6. Mechanical refrigeration system with chilled water storage 7. Single stage Lithium Bromide Absorption chiller 8. Two stage Lithium Bromide Absorption chiller

PB Power

Schematic of an Indirect System Using a Mechanical Chiller

Combustion Air Mechanical Chiller Air Filter Air Cooling Coil Condensate Drip Pan

Exhaust Gas

Fuel

Chilled Water Pump

Combustion Turbine

PB Power

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

Advantage#

Disadvantage# # # #

#

Can increase gas turbine performance better than evaporative cooling, and fog system Not very sensitive to ambient air wet bulb temperature

# # #PB Power

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

Gas Turbine Inlet Air CoolingAvailable Technologies1. Evaporative cooler 2. Fogging system 3. Mechanical refrigeration system (direct type) 4. Mechanical refrigeration system (indirect type) 5. Mechanical refrigeration with ice storage 6. Mechanical refrigeration system with chilled water storage 7. Single stage Lithium Bromide Absorption chiller 8. Two stage Lithium Bromide Absorption chiller

PB Power

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

Combustion Air Mechanical Chiller/ Ice Maker Ice Storage Tank Air Filter Air Cooling Coil Condensate Drip Pan

Exhaust Gas

Fuel

Chilled Water Pump

Combustion Turbine

PB Power

Inlet Air Cooling With Chilled Water Storage System Schematic

Mech. Chiller

Chilled Water Storage Tank

Combustion Air Air Filter Air Cooling Coil Condensate Drip Pan

Exhaust Gas

Fuel

Chilled Water Pump

Combustion Turbine

PB Power

Mechanical Refrigeration System With Ice StorageApplications: Areas where RH is rather high,plus a wide variation in electricity tariff between peak and non peak hours

Advantage#

Disadvantage# # #

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 operationPB Power

High initial capital cost High O&M cost Longer delivery and installation time Higher expertise is needed to operate and maintain the plant

#

#

#

Chiller Electrical Load MW 36C DB, 25C WB, 10C Chilled Air Temp6

Chiller Electrical Load MW

5 4 3 2 1 0 0 25 50 75 100 125 150 175 200 225 250 275 300

Gas Turbine Output MW

PB Power

Gas Turbine Inlet Air CoolingAvailable Technologies1. Evaporative cooler 2. Fogging system 3. Mechanical refrigeration system (direct type) 4. Mechanical refrigeration system (indirect type) 5. Mechanical refrigeration with ice storage 6. Mechanical refrigeration system with chilled water storage 7. Single stage Lithium Bromide Absorption chiller 8. Two stage Lithium Bromide Absorption chiller

PB Power

Absorption Chiller Inlet Air Cooling System Schematic

Combustion Air Absorption Chiller Air Filter Return Condensate LP Steam Air Cooling Coil Condensate Drip Pan

Exhaust Gas

Chilled Water Pump

Fuel

Heat Recovery Steam Generator Combustion Turbine

PB Power

Flow DiagramPressure approx. 60 Torr 60 mm Hg 80 mbar 8 kPa Condenser tc 45C 37C Tower Water Out

GeneratorHeat Medium In

Steam or Hot Water

70 C

Heat Medium Out

95 C

Pressure approx. 6,2 Torr 6,2 mm Hg 8,2 mbar 0,83 kPa

to 4C 6C Chilled Water

Evaporator

12C

Absorber 32,5C 27C ta 35C Chilled Water Tower Water Concentrated Solution (LiBr) Diluted Solution (LiBr) Steam or Hot Water Refrigerant (Water) 50C Tower Water In

70C

PB Power

Picture courtesy of York International

Absorption Chiller Steam Consumption 36C DB, 25C WB, 10C Chilled Air Temp80 70

Steam Consumption t/h

60 50 40 30 20 10 0

0

25

50

75

100

125

150

175

200

225

250

275

300 Single Stage Two Stage

Gas Turbine Output MW

PB Power

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 steam

Advantage#

Disadvantage# # #

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

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

#

#

#

#

PB Power

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 steam

Advantage#

Disadvantage# # #

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 chillerPB Power

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

#

#

# #

#

Condensate Formation on the Chilled Water Coil t/h Based on 36C DB, 25C WB, 10C Chilled Inlet Air TemperatureCondensate Formation t/h

20 15 10 5 0

25

35

45

55

65

75

85

95

105 115 125 135 145 155 165 175 185 195 205 215 225 235 245 255 265

Gas Turbine Output MW

PB Power

Performance Evaluation Of Different Inlet Air Cooling SystemsBase Condition! ! !

35C Dry bulb 25C Dry bulb 44.7% Relative humidity

Real world condition

Increase in power outputPercent Change Gas turbine output before inlet air cooling Gas turbine output with mechanical refrigeration system and inlet air temperature of 10C Gas turbine with evaporative cooler running at 85% RH Gas turbine with fog system running at 100% RHPB Power

108.23 MW (net) 124.8 MW (net including chiller electrical load) 114.8 MW (net) 116.65 MW (net)

0%

15.3%

6% 7.69%

Capital Cost Comparisons of Inlet Cooling SystemsOptionsEvaporative cooler Fog system (excluding water treatment plant) Single stage LiBr absorption chiller Two stage LiBr absorption chiller Ammonia mechanical refrigeration systemPB Power

Relative Costs 1 2 8 10 9.5

Major Contributors To The O&M CostsOptionsEvaporative cooler Fog system (excluding water treatment plant) Single stage LiBr absorption chiller

O&M Costs# # # # # # # # # # # # # #

Make up water Water treatment (if applicable) Make up water Demineralised water treatment Injection pump power consumption 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

Two stage LiBr absorption chiller

Ammonia mechanical refrigeration systemPB Power

# #

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

0.470

NOx Emission kg/MWh

0.460 0.450 0.440 0.430 0.420 0.410 0 5 10 15 20 25 30 35 40 45

Ambient Temperature deg C

PB Power

Heavy Duty Gas Turbine CO2 Emission kg/MWh

590 CO2 Emission kg/MWh 580 570 560 550 540 530 520 0 5 10 15 20 25 30 35 40 45 Ambient Temperature deg C

PB Power

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

0.43

NOx Emission kg/MWh

0.42 0.41 0.4 0.39 0.38 0.37

0

5

10

15

20

25

30

35

40

45

Ambient Temperature deg C

PB Power

Aero-Derivative Gas Turbine CO2 Emission kg/MWh

550

CO2 Emission kg/MWh

540 530 520 510 500 490 480 470 0 5 10 15 20 25 30 35 40 45

Ambient Temperature deg C

PB Power

In Selecting Inlet Air Cooling As A Retrofit To An Existing PlantPoints 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 steamPB Power

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PB Power Gas Turbine Inlet Air Cooling System The 3 rd Annual Australian Gas Turbine Conference 6 th –7 th December 2001 Melbourne Australia Presented by Bob Omidvar Manager, Power Engineering PB Power Australia
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