11 TH HVACR CONFERENCE, KARACHI, MARCH 25-27,2004

1. 11TH HVACR CONFERENCE, KARACHI, MARCH 25-27,2004 CONDITIONING OF GAS TURBINE INLET AIR BY ABSORPTION REFRIGERATION TO REDUCE COSTS OF COMBINED CYCLE POWER PLANTS AUTHOR: AINUL ABEDIN, P.E. FELLOW ASHRAE, FELLOW I.E. (PAK) AINUL ABEDIN CONSULTING ENGINEERS KARACHI

2. COMBINED CYCLE POWER PLANT PERFORMANCE • Most Efficient Thermal Power Plants. • GT Performance Affected By Air Mass Flow. • Lowering of Air Density Both Due to Higher Altitude (Site Specific) & Increase in Ambient Temperature. • 1 % Capacity Loss For Each 1 deg.C Rise in Temperature. • 1 % Decrease in Efficiency For Each 3 deg.C Rise in Temperature.

3. EFFECT OF GT COMPRESSOR INLET TEMPERATURE ON OUTPUT & HEAT RATE

4. COMBINED CYCLE POWER PLANT COSTS • Capital Costs US $ 600-700 / kW Capacity (ISO Rating). • At Peak Summer (45 deg.C), Actual Capacity Could Cost 30 % Higher Per kW Due to Power Plant De-rating. • Inefficient Operation at High Ambients also Increase Specific Fuel Consumption.

5. CONDITIONING OF GT INLET AIR BY REFRIGERATION • Cooling & Controlling Humidity of GT Inlet Air to ISO Conditions For Full Combined Cycle Power Plant Capacity, Increase Upto 30 % from De-rated Capacity at 45 deg.C. • Operation at ISO Conditions Will Result in Lower Heat Rate, Not Only For Additional Capacity But For Total Generation And This Would Result in Very Big Fuel Savings

6. GAS TURBINE-BASED COMBINED CYCLE STATION LAYOUT

7. INTEGRATED SYSTEM DESIGN FOR GT INLET CONDITIONING WITH ABSORPTION REFRIGERATION • For Economical Refrigeration, Proposed Design is Based on Utilisation of Waste Heat Availability From Steam Turbine Extraction. • Actual Cost of Energy For Absorption Refrigeration is Reduced Due to Maximum Utilisation of Steam Enthalpy (Over 75 %) For Power Generation in Steam Turbine before Extraction at 15 psig.

8. INTEGRATED SYSTEM DESIGN (CONTD) • Single-stage Low-cost Absorption Chillers Have Very Reliable Operation History in Pakistan. • Since There Are No Moving Equipment (Only Small Pumps), Simple Service & Maintenance Required For Absorption Chillers. • Cooling Water Circuit of Condensing Steam Turbine Can Be Combined With Absorption Chiller Condenser Water Circuit For Most Economical Integrated Combined Cycle Power Plant Design.

9. REFRIGERATION CAPACITY FOR GT INLET CONDITIONING • For Efficient Gas Turbines, Capacity Increase of 30 % (To Cool Inlet Air From 45 deg.C To 15 deg.C) Requires About 44 Tons of Cooling For Each 1 MW ISO Capacity. • Modern Efficient 300 MW ISO Rated Combined Cycle Power Plant Would Require Peak 8,800 Tons of Refrigeration to Increase De-rated Capacity at 45 deg.C, to Full Capacity at 15 deg.C This Would be Required During Full-load Operation, Normally 8-10 Hrs/Day. • With Thermal Storage System, On-line Absorption Refrigeration of About 3,000 Tons Capacity Would Ensure Both Enhanced Capacity & Efficiency During Full Load Operation.

10. COMBINED CYCLE POWER STATION PART-LOAD OPERATION WITH CONDITIONING OF GT INLET AIR • Since Cooling Coil is Redundant During Part-load Operation, Additional GT Inlet Pressure Drop Increases Heat Rate Due to Lower Efficiency. • GT Inlet Air Heating Could Be Utilised To Increase Overall Cogeneration Efficiency Since Normally, Most Base-load Combined Cycle Power Stations Operate at Part-load For Long Duration (14 – 16 Hours) Every Day. • Integrated System Design Allows Use of Components of GT Inlet Cooling for Economical Inlet Heating Cycle.

11. WORLD WIDE APPLICATIONS OF GAS TURBINE INLET COOLING BY REFRIGERATION • In USA, Over 350,000 Tons of Refrigeration Have Been Installed For Enhancement of Gas Turbine-Based Power Plant Capacity. • In Brazil (With Conditions Similar To Pakistan), Nearly 53,000 Tons of Refrigeration Have Been Installed in Similar Power Plants. • Large Installation in Saudi Arabia Also. • Pakistan Has Only Small Gas Turbine Power Plants’ Installation With Inlet Air Cooling But These Examples Prove Performance & Available Technology.