Desuperheaters are used to cool steam in power plants. Desuperheating or steam conditioning is the process of restoring superheated steam to its saturated state through temperature reduction. There are two basic types of desuperheaters: indirect contact and direct contact. Indirect contact desuperheaters such as shell and tube heat exchangers separate the steam and the medium used to cool it. Direct contact steam desuperheaters do not. A direct contact steam desuperheater injects moisture through small holes into the path of high-velocity steam. After injection, the water is atomized into small drops and quickly evaporated by absorbing the superheat. Measurement of the steam temperature downstream is used to control the amount of water added during desuperheating.
Desuperheaters can be installed vertically or horizontally and use either pneumatic or electric power. Desuperheater components include steam and water control valves, automation controls, and desuperheater heat pumps. The outer pipe of desuperheaters is usually made of carbon steel or stainless steel. In some applications, desuperheaters with fiberglass, Teflon? or plastic components can be used. Teflon is a registered trademark of DuPont. Several factors can affect the efficiency of a dusuperheater heat pump. These factors include the pressure differential between water and steam, the velocity differential between water and steam, the temperature differential between water and steam, and the amount turbulence.
Superheaters are used to produce steam at temperatures that are higher than the saturation temperature for the steam pressure. Typically, a superheater is used to drive a turbine or similar device in a power generation plant or facility. One advantage of superheated steam is that it contains more energy than saturated steam and has a greater specific volume. Unlike desuperheaters, however, superheaters can be relatively difficult to size. Superheaters are also more expensive than desuperheaters. Superheater applications include production processes in the papermaking and sugar processing industries.