Construction and working principle of Open cycle gas
turbine power plant
In the open cycle gas turbine, air is drawn into the
compressor from atmosphere and is compressed. The compressed air is heated by
directly burning the fuel in the air at constant pressure in the combustion
chamber. Then the high pressure hot gases expand in the turbine and mechanical
power is developed.
Part of the power developed by the turbine (about 66%) is
used for driving the compressor. The remaining is available as useful output.
The working fluid, air and fuel, must be replaced continuously as they are
exhausted into the atmosphere. Thus the entire flow comes from the atmosphere
and is returned to the atmosphere.
and working principle of closed cycle gas turbine power plant
In this, the compressed air from the compressor is heated
in a heat exchanger (air heater) by some external source of heat (coal or oil)
at constant pressure. Then the high pressure hot gases expand passing through
the turbine and mechanical power is developed. The exhaust gas is then cooled
to its original temperature in a cooler before passing into the compressor
The main difference between the open and closed cycles is
that the working fluid is continuously replaced in open cycle whereas it is
used again and again in a closed cycle. The open cycle plant is much lighter
than the closed cycle. Hence it is widely used.