What Does Superheated Steam Mean?
Superheated steam is steam at a temperature that is higher than its vaporization (boiling) point at the absolute pressure. It is steam which is formed at the temperature which exceeds that of saturated steam at the same pressure.
Superheated steam is used in turbines to improve thermal efficiency. Other uses include:
- Surface technologies
- Cleaning technologies
- Catalysis/chemical reaction processing
- Surface drying technologies
- Curing technologies
- Soil steaming
- Energy systems
Pitting, corrosion fatigue and stress corrosion cracking all may be caused by superheated steam.
Corrosionpedia Explains Superheated Steam
When saturated steam produced in a boiler is exposed to a surface with a higher temperature, its temperature will increase above the boiling temperature. The steam is then described as superheated by the number of degrees through which it has been heated above saturation temperature. The saturated steam drawn from a boiler is passed through a detached heating device which transfers extra heat to the steam by contact or by radiation.
Superheated steam is not usually used in a heat exchanger due to low heat transfer coefficient. It is mainly used for stripping and cleaning purposes in the refining and hydrocarbon industries.
The properties of superheated steam are close to a perfect gas rather than a vapor. Since superheated steam has no direct relationship between temperature and pressure, at a particular pressure it may be possible for superheated steam to exist at a wide range of temperatures.
As superheated steam is an insulator, superheated steam farther away from the surface cannot easily cool down and yield its energy.
Superheated steam’s greatest value lies in its tremendous internal energy that can be used for kinetic reaction through mechanical expansion against turbine blades and reciprocating pistons, producing rotary motion of a shaft.