One of the most important accessories of a boiler is a superheater. It affects improvement and economy in the following ways.

* The superheater increases the capacity of the plant.

* Eliminates corrosion of the steam turbine.

* Reduces steam consumption of the steam turbine.

Superheat normally refers to the process of increasing the temperature of steam above about 200°C and 15 bar to produce a very "dry" steam with absolutely no water vapor. This feature is most common in very large power plant boilers of water tube construction. But is not mandatory. Superheater (of different design) is applicable to low pressure boilers, even to firetube boilers, where superheating is done by passing the saturated steam through the hot flue gasses, before to leave the boiler.

An additional heat exchanger capable of the high temperatures and pressures is required.
Regardless of the boiling point, when water boils, the water and steam have the same temperature. This is called the saturation temperature.

As long as the water and steam remain in contact, the temperature will remain at the saturation temperature. The boiler is only capable of producing saturated steam.
 

Superheater design

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