Friday, 21 July 2017

introduction to gas turbine

A gas turbine is most satisfactory way of producing large power in compact unit. In gas turbine power plant, a gas turbine is used as the prime mover to produce mechanical energy. In gas turbine power plant, the working medium is either a mixture of combustion products(air and fuel) or heated air at a certain pressure and a higher initial temperature. The gas turbine obtains its power by utilizing the energy of burnt gases and air which are at high pressure and pressure by expanding through several rings of fixed or moving blades.


The simple gas turbine consists of

1) compressor,
2) combustion chamber and
3) turbine.


The basic on which a gas turbine works is similar to internal combustion engine. In both cases air is made to enter the prime mover which compresses and  then heated by combustion process. Hence pressure and temperature of working fluid is increased. This high temperature and prssure working fluid is then expanded in prime mover. The expanded products are discharged through exhust. However in the case of internal combustion engine is reciprocating machine in which charge induces in to engine cylinder intermittently. In case of gas turbine, flow of working fluid through the rotary machine(gas turbine) is continuous and smooth. with respect to design, a gas turbine is quite similar to steam turbine. In the turbine blading working gas expands and the heat energy is converted first in to the kinetic energy and then to the rotary motion of the turbine shaft. However in the seam power plant the product of combustion do not form the working medium. These are utilized to produced an intermediate fluid(steam) which is expanded in the steam turbine.


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