Schematic Arrangement of Gas Turbine Power Plant
The schematic arrangement of a gas turbine power plant is shown in figure.The main components of plants are
(i)Compressor (ii)Regenerator (iii)Combustion Chamber (iv)Gas Turbine
(v)Alternator (vi) Starting motor
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 the 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.
A regenerator is a device which recovers heat from the 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 ashell.the compressed air from the compressor passes through the tubes on its way to the combustion chamber.In this way compressor is heated by the hot exhaust gases.
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 ensure atomisation of oil and its through 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 then delivered to 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 900 F.
The gas turbine is coupled into the alternator.The alternator converts the mechanical energy of the turbine into electrical energy.The output of the alternator is given to the bus-bars through transformers,isolators and circuit breakers.
(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 energised by the batteries.Once the unit starts, a part of the mechanical power of the turbine drives the compressor and there is no need of the motor now.