What is a desuperheater and how does it differ from an attemperator?

Desuperheater and an attemperator are both devices used in steam systems to control the temperature of superheated steam, but they function differently.


  • A desuperheater is a device designed to reduce the temperature of superheated steam by injecting a coolant, typically water, into the steam flow.
  • It is commonly used in applications where the temperature of the superheated steam needs to be lowered before it can be utilized or directed to downstream processes.
  • The desuperheater consists of a nozzle or multiple nozzles installed in the steam line. The coolant, usually water, is sprayed into the steam flow through these nozzles.
  • The water droplets evaporate instantly due to the high temperature of the steam, absorbing the heat from the steam and reducing its temperature.
  • The resulting mixture of steam and water vapor is then directed to a separator to remove any remaining liquid water before it continues downstream.
  • Desuperheaters are commonly used in power plants, chemical plants, and other industrial processes where precise temperature control is required.
  • They help prevent equipment damage, ensure safe operation, and optimize the efficiency of heat transfer processes.


  • An attemperator is also a device used to control the temperature of superheated steam.
  • However, unlike a desuperheater, an attemperator uses the direct contact principle to cool the steam.
  • It achieves this by spraying a controlled amount of water directly into the steam flow.
  • The attemperator consists of a spray water system that injects water into the steam path.
  • The water droplets mix with the steam, absorbing the heat and reducing its temperature.
  • The steam and water mixture then flows through a separator or baffle arrangement to separate the water droplets from the steam before it continues downstream.
  • Attemperators are commonly used in applications where precise and rapid temperature control of superheated steam is required.
  • They are often utilized in power plants, particularly in steam turbine systems, to ensure that the steam temperature entering the turbine remains within the desired range, preventing potential damage to the turbine blades.

Attemperator vs Desuperheater

Attemperators and desuperheaters are frequently confused since they serve the same purpose. Either directly or indirectly coming into touch with liquid water, both serve to lower the temperature of steam in a system. As the table below illustrates, there are a few characteristics that set the two apart.

Attemperator Desuperheater
Attemperators often function across a greater pressure and temperature range. As a result, their turndown ratio is higher. Desuperheaters only operate within a small range of temperature and pressure.
The only method of lowering steam temperature is the addition of liquid water. Some variations use a venturi tail to lower the steam’s temperature.
Its temperature control could aim to raise or lower the temperature. However, in most situations it works to lower the temperature.Only the lowering in steam temperature is the only goal of desuperheaters.

While both desuperheaters and attemperators are used to control the temperature of superheated steam, they differ in their operating principles. A desuperheater reduces the steam temperature by injecting a coolant (typically water) into the steam flow, while an attemperator achieves temperature control by directly spraying water into the steam, allowing for efficient heat transfer and precise temperature regulation. The choice between the two depends on specific process requirements, temperature control accuracy, and system design considerations.