Schematic Arrangement of Gas Turbine Power Plant

Schematic Arrangement of Gas Turbine Power Plant:

The schematic arrangement of a gas turbine power plant is shown in Figure.The main components of the plant are :

(i) Compressor 

(ii) Regenerator

(iii) Combustion chamber 

(iv ) Gas turbine

(v) Alternator 

(vi ) Starting motor

Schematic Arrangement of Gas Turbine Power Plant

(i) Compressor. The compressor used in the plant is generally of rotatory type. The air at atmospheric pressure is drawn by the compressor  via the filter which removes the dust from air.The rotatory blades of the compressor push the air between stationary blades to raise its pressure.Thus air at high pressure is available at the output of the compressor.

(ii) Regenerator. A regenerator is a device which recovers heat from the exhaust gases of the turbine. The exhaust is passed through the regenerator before wasting to atmosphere. A regenerator consists of a nest of tubes contained in a shell.The compressed air from the compressor passes through the tubes on its way to the combustion chamber. In this way, compressed air is heated by the hot exhaust gases.

(iii) Combustion Chamber. The air at high pressure from the compressor is led to the combustion chamber  via the regenerator.  In the combustion chamber, heat is added to the air by burning oil.The oil is injected through the burner into the chamber at high pressure to ensure atomization of oil and its thorough mixing with air.The result is that the chamber attains a very high temperature (about 3000F). The combustion gases are suitably cooled to 1300F to 1500F and then delivered to the gas turbine.

(iv) Gas Turbine. The products of combustion consisting of a mixture of gases at high temperature and pressure are passed to the gas turbine. These gases in passing over the turbine blades expand and thus do the mechanical work.  The temperature of the exhaust gases from the turbine is about 900oF.

(v ) Alternator. The gas turbine is coupled to the alternator.The alternator converts mechanical energy of the turbine into electrical energy.The output from the alternator is given to the bus-bars through transformer, circuit breakers and isolators.

(vi ) Starting Motor.  Before starting the turbine, compressor has to be started.  For this purpose, an electric motor is mounted on the same shaft as that of the turbine.The  motor is energized by the batteries. Once the unit starts, a part of mechanical power of the turbine drives the compressor and there is no need of motor now.