The gas turbine power plant is also called a combustion turbine power plant. The gas turbine is a type of continuous combustion, internal combustion engine.
There are three main components in a gas turbine, they are
- An upstream rotating gas compressor;
- A downstream turbine on the same shaft and
- A combustion chamber or area called a combustor.
- Gas turbine plants are used as standby plants for the hydroelectric power plants.
- Gas turbine power plants may be used as peak loads plant and standby plants for smaller power units.
- Gas turbines are used in jet aircraft and ships. Pulverised fuel-fired plants are used in a locomotive.
The economics of power generation by gas turbines are proving to be more attractive, due to low capital cost, and high reliability and flexibility in operation. Quick starting and capability of using a wide variety of fuels from natural gas to residual oil or powdered coal are other outstanding features of gas turbine power plants. Major progress has been made in three directions namely increase in unit capacities of gas turbine units (50—100 mW), increase their efficiency and drop in capital cost. The primary application of gas turbine plant is to supply peak load. However, gas turbine plants nowadays are universally used as peak load, base lead as well as standby plants.
- It is smaller in size and weight as compared to an equivalent steam power plant. For smaller capacities, the size of the gas turbine power plant is appreciably greater than a high-speed diesel engine plant, but for larger capacities, it is smaller in size than a comparable diesel engine plant. If size and weight are the main consideration such as in ships, aircraft engines and locomotives, gas turbines are more suitable.
- The initial cost and operating cost of the gas turbine plant are lower than an equivalent steam power plant.
- The plant requires less water as compared to a condensing steam power plant.
- The plant can be started quickly and can be put on load in a very short time.
- There are no standby losses in the gas turbine power plant whereas in steam power plant these losses occur because the boiler is kept in operation even when the turbine is not supplying any load.
- Maintenance cost of the gas turbine power plant is low and easier to maintain.
- The lubrication of the plant is easy. In gas turbine plant, lubrication is needed mainly in compressor, turbine main bearing and bearings of auxiliary equipment.
- The plant does not require massive foundations and building.
- There is a significant simplification of the plant over a steam plant due to the absence of boilers with their feed water evaporator and condensing system.
- The significant part of the work developed by the turbine is used to derive the compressor. Therefore, network output of the plant is low.
- The temperature of the products of combustion becomes too high, so service conditions become complicated even at moderate pressures.