Superheated steam is steam that is heated above the previously mentioned boiling temperature of 100 °C (212 °F) at atmospheric pressure. This process involves a few different steps. When additional heat content is added to boiling water in liquid condition, the heat content (enthalpy) of the water further increases. The temperature of the water, however, maintains a constant value until all liquid has been evaporated to a gaseous state. At this point, a condition of so-called saturated steam is reached. When additional heat content is added to saturated steam, a condition of superheated steam is obtained. Superheated steam is also known as “dry” steam, as it contains no water droplets. It does contain, however, a lot of energy. The stored energy in dry steam makes it highly efficient to transport it  to a point where the energy is required.

When a Desuperheater is deployed to reduce the pressure of superheated steam that is supplied around a turbine or another power engine, this usually called ‘turbine bypass desuperheating’. The letdown (=reduced) steam is still strongly superheated, and although it could have reached the required pressure level at the outlet of the steam-reducing valve, it is usually still unsuitable for use owing to its temperature. In the steam turbine back pressure system to which the steam is fed, the basic requirement is to maintain the pressure and the temperature of this back pressure steam at a constant level, undependable of the load of the steam turbine.