Page 559 - Handbook of Electrical Engineering

Appendix F

Worked Example for Calculating

the Performance of a Gas Turbine

F.1 THE REQUIREMENTS AND DATA GIVEN

A 12 MW gas turbine generator is required to operate at sea level with an ambient temperature T 1
◦
◦
of 20 C and a combustion temperature T 3 of 950 C. The following data apply.
Compressor
11.0
Pressure ratio of the compressor r pc
0.85
Compressor efficiency η c
1.4
Ratio of specific heats for compression γ c
◦
1.005 kJ/kg K
Specific heat at constant pressure C pc
Ambient pressure 1.0 bar
Turbine
Pressure ratio of the turbine r pt , nominal 11.0
Turbine efficiency η t 0.87
Combustion pressure drop P 23 /P 23 0.04
Ratio of specific heats for expansion γ t 1.33
◦
Specific heat at constant pressure C pt 1.147 kJ/kg K
Heat rate 15.750 MJ/kWh
Losses
Inlet ducting and silencer pressure drop P 1 125 mm of water
50 mm of water
Exhaust ducting pressure drop P 4
Gear box efficiency η gb at full load 0.985 per unit
0.985 per unit
Generator energy conversion efficiency η gen
Fuel
LHV for hydrocarbon natural gas 37.50 MJ/kg
Fuel air ratio by mass 0.01 per unit

F.2 BASIC REQUIREMENTS
Assume constant specific heat C p = C pc ,and γ = γ c . Ignore the losses in the ducting, gear box
and generator.

Handbook of Electrical Engineering: For Practitioners in the Oil, Gas and Petrochemical Industry. Alan L. Sheldrake
 2003 John Wiley & Sons, Ltd ISBN: 0-471-49631-6