Superheater in Steam Power Plant – Types, Roles and Application of Steam Power Plant Superheater
A superheater is the equipment of a steam power station that superheats the steam. The superheater is responsible for raising the temperature of steam above the boiling point of water. It is used to increase the overall efficiency of the plant.
Also see: Efficiency of Steam Power Plant
The basic construction of a superheater involves group of tubes that made of special alloy steels such as chromium-molybdenum.
The tubes are heated using heat of flue gases during their journey from the furnace to the chimney. Steam generated in the boiler is led through the superheater where it is superheated using the heat generated by flue gases.
See Also: Why Coal is Pulverized before Combustion in Steam Power Station
Superheaters are primarily divided into two types according to the system of heat transfer from flue gases to steam.
The two types of superheaters are:
- Convection superheater
- Radiant superheater
A convection superheater is popular and most commonly used type of super heater that is employed these days in power plants. Such superheater is installed in the boiler tube bank and receives heat from flue gases entirely through the convection process (as its name implies).
With an increase in steam output the temperature of superheater increases as well.
A radiant superheater is installed in the furnace between the water walls.
As its name implies, a radiant superheater obtains heat from the burning fuel using radiation process.
There are two major limitations associated with radiant superheater thereby restricting its applications in modern systems. These are:
- Overheating: Due to high furnace temperature, radiant superheater may get overheated and, therefore it necessitates a careful design
- Reduction of superheater temperature: The temperature of superheater decreases with increase in steam output
Also see: Disadvantages of Steam Power Plant