As the name suggests, a desuperheater is used to change the state of steam from superheated state to saturated state. All power plants that run on a Rankine cycle use high-pressure, superheated steam to turn a steam turbine. This is true immaterial of the heat source used to generate steam.

When a steam turbine trips, the superheated steam going to the turbine has to be somehow sent to the condenser. This is done using a desuperheating system. Some desuperheaters use a series of cages to rapidly reduce the pressure of steam and have a water spray system to reduce the temperature.