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 remaining 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 motorGas turbines are not self starting. They require a starting motor to first bring the turbine to the minimum speedcalled 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.