Operation of Gas Turbines
The operation of gas turbine includes the starting and shut down.
1. Starting of gas turbine : The gas turbines are not self starting type. Because, in a gas turbine power plant, the air from surroundings needs to be inducted into the compressor to raise its pressure and the high temperature gases generated by combustion of fuel are expanded in a turbine to develop sufficient power. Thus a gas turbine power plant needs auxiliary power source for its starting.
Various starting devices for operation of gas turbine power plant are :
- An I.C. engine
- An electric motor
- Compressed air bottle
- Another prime mover like steam turbine or gas turbine.
It is coupled to the gas turbine plant with a disengaging clutch. Once the air is inducted into the compressor by a starting device, the fuel is injected and ignited by a ignition device. Gradually the load is built upon the alternator by governor gear control till the plant starts operating at full load.
2. Shut down of a gas turbine : The shut-down of a the gas turbine takes place very quickly as soon as the fuel supply combustion chamber is cut-off. Quick shut-down also avoids the chilling effect resulted due to cold air passing through the gas turbine during shut-down period.