What is an attemperator?

About an attemporator

The majority of high pressure boilers are using one, two or even three superheaters. The temperature in the superheaters tends to fluctuate as a result of many operational parameters. These parameters include things like excess air, feed water supply temperature, the type of fuel used, and other operational issues like start-up. Of course, the variation in the steam flow demand also plays an important part. Since high efficiency boilers and furnaces operate with temperatures as close as possible to maximum allowable temperatures dictated by the construction materials, the protection of the superheaters – in particular the second and third one – is essential.

Such protection is necessary to prevent serious erosion problems and damage to the materials of the superheater and downstream steam piping. For this purpose, a desuperheater is typically installed between the primary and secondary superheater. In this case, the desuperheater is often referred to as an attemperator. It is named an attemperator because it tempers the high steam temperature to an accurate temperature. Functionally, a desuperheater and attemperator are the same, i.e. they remove the superheat content of the steam with the help of water. But in this set-up it is even more crucial to install a reliable and accurate desuperheater. The ASME Boiler I: Rules for Construction of Power Boilers, however, only mention a desuperheater arrangement between superheater or reheater, not attemperator.

Difference between a desuperheater and an attemperator?

The term attemperator is generally used in places where it is crucial that the final steam temperature reaches an accurate temperature. Every attemperator is a desuperheater, but not every desuperheater can be used as an attemperator.

The in-line Kiekens Venturi is the best available boiler attemperator solution for use in the HP inter stage, reheat inter stage and final stage application. The absence of moving wear and tear parts makes it very reliable. Only minimized maintenance is required during its lifetime. Due to its working principle it is highly accurate, even at extreme high demands of water injection (up to 40%). Furthermore, a controlled and full evaporation of the cooling water is guaranteed without the need for a so-called thermal liner or thermal sleeve to protect the downstream piping.

Read more about the in-line Kiekens Venturi