Block Diagram of a Simple Gas Turbine Plant
- Main components are : 1. Air filter, 2. Air compressor, 3. Combustion chamber, 4. Gas turbine, 5. Alternator, 6. Starting motor.
- The other auxiliaries are lubrication pump, oil system, fuel system and duct system etc.
- The compressor is mounted on the same shaft of turbine to which alternator is also connected on the other side of the starting motor.
- The rotary type compression sucks the air through air filter from the atmosphere.
- Filter removes dust , dirt particles from air and pure air goes to the compressor.
- The rotary blade assembly pushes the air between the stationary blades. By this the pressure is ralsed from 4 to 5 atmosphere.
- Thus at the output of compressor , high pressure air is available.
- Combustion chamber costs of a vessel into which high pressure all from combustion is fed. The fuel is injected into the combustion chamber and burnt with the help of high pressure from compressor.
- The combustion products Le mature of gases at high temperature and at high pressure passed through gas turbine.
- This moves turbine blade assembly and therefore turbine shaft starts rotating.
- Gases are expanded in the turbine, thereby pressure decreases and come out from turbine go to atmosphere. The temperature at outlet gases is about 400 to 500 C.
- Some major part of power developed by gases in passing through turbine is utilized for run the compressor and other auxiliaries.
- Rest power of the turbine rotates the generator and generator converts mechanical power into electrical.
- Prior to start the turbine the motor is used to start compressor Initially. But once the plant starts then turbine drives the compressor and alternator, so motor is then not required and shut off.
- Efficiency of this plant is lesser because some power produced is taken for running-compressor and remaining for generator for electrical energy conversion.
- This is the open cycle plant whose efficiency is 20 to 30% only.
1. Small size
2. Simple design
3. Requires low space per kW output
4. Quick start
5. No warming up period
Demerits of open cycle type Gas plant
1. Requires higher air rate.
2. More erosion and corrosion of turbine blades.