KALASALINGAM UNIVERSITY
DEPARTMENT OF MECHANICAL ENGINEERING
(MEC 401) POWER PLANT ENGINEERING
GAS TURBINE POWER PLANT
GAS TURBINE POWER PLANT:
A gas turbine, also called a combustion turbine, is a type of internal
combustion engine.
It has an upstream rotating compressor coupled to a downstream turbine, and
a combustion chamber in-between.
Energy is added to the gas stream in the combustor, where fuel is mixed with
air and ignited.
In the high pressure environment of the combustor, combustion of the fuel
increases the temperature.
The products of the combustion are forced into the turbine section.
There, the high velocity and volume of the gas flow is directed through a
nozzle over the turbine's blades, spinning the turbine which powers the
compressor and, for some turbines, drives their mechanical output.
The energy given up to the turbine comes from the reduction in the
temperature and pressure of the exhaust gas.
Energy can be extracted in the form of shaft power, compressed air or thrust or any
combination of these and used to power aircraft, trains, ships, generators, or even
tanks.
KALASALINGAM UNIVERSITY
DEPARTMENT OF MECHANICAL ENGINEERING
(MEC 401) POWER PLANT ENGINEERING
Working principle of gas turbine power plant
Gas turbines are described thermodynamically by the Brayton cycle, in
which air iscompressed isentropically, combustion occurs at constant
pressure, and expansion over the turbine occurs isentropically back to the
starting pressure.
The atmospheric air enters the compressor where it is compressed to a high
pressure.
This high pressure air then enters the combustion chamber where it mixes
with the fuel (natural gas or petrol) and combustion takes place.
The high pressure and high temperature combustion gases expand in the gas
turbine and thus mechanical energy is produced.
Part of this mechanical energy is used in driving the compressor which is
usually mounted on the same shaft as that of the turbine shaft and the remain
ing part of this mechanical energy is utilized for producing electric power.
KALASALINGAM UNIVERSITY
DEPARTMENT OF MECHANICAL ENGINEERING
(MEC 401) POWER PLANT ENGINEERING
Uses of gas power plant
1. Gas turbine plants are used in jet, aircraft and ships.
2. They are used as standby plants for hydro electric power plants.
Elements of a gas turbine power plant
The gas turbine plant consists of
1. Starting motor
2. Low pressure compressor (LPC)
3. Intercooler
4. High pressure compressor (HPC)
5. Regenerator
6. Combustion chamber
7. Gas turbine
8. Reheating unit
Starting motor
Gas turbines are not self starting.
They require a starting motor to first bring the turbine to the minimum speed
called coming in speed, for this purpose a starting motor is required.
KALASALINGAM UNIVERSITY
DEPARTMENT OF MECHANICAL ENGINEERING
(MEC 401) POWER PLANT ENGINEERING
Low pressure Compressor (LPC)
In gas turbine plant, the axial and centrifugal flow compressors are used.
