What is Steam Desuperheating?
In power plant processes, steam is usually produced in a superheated state so that it does not condense unnecessarily in the transfer pipeline but remains as steam.
However, the heat transfer capacity of superheated steam is inferior compared to that of saturated steam, and therefore it must be cooled to a temperature close to that corresponding to the pressure of saturated steam. This can be done using a separate valve.
Selection of Equipment
Precision determines the cooling method chosen.
Cooling of superheated steam is most commonly done by controlled injection of cooling water into the steam. The cooling water is sprayed either directly into the valve seat or immediately after the valve. The operation is relatively simple and failsafe. By adding cooling water, the temperature can at best be brought to +3 °C relative to that of saturated steam.
Often, the valve is equipped with a separate expansion chamber, which is placed immediately afterwards. It allows for the expansion of the steam under lower pressure. The expansion chamber extends the lifespan of the valve and helps in controlling noise levels.
Depending on the required accuracy of cooling and the amount of water, cooling water is directed to the expansion section using various techniques. It can be atomized into the steam as water vapor or the steam can be driven through a water sheet. If necessary, perforated plates/silencers can be added to the expansion section to reduce the flow rate in a controlled manner to lower noise levels.
If the process requires fully saturated steam, it can be produced using a separate steam desuperheating machine.
We assist in selecting the equipment used for desuperheating according to the application’s requirements. Ask our contact persons for more information.
