An attemperation is an act of attempering or regulating something.

I assume that you are asking "Why is the attemperation water spray placed between the primary superheater and the secondary superheater?" This gives time for all the spray water to evaporate and still be effective at de-superheating, or attemperating.

An attemperator is a device which regulates the temperature of somewhere, such as a boiler, by passing hot or cold water through a coil of spring.

Some major fields of study under engineering are as follows.

* Electrical engineering

* Electronics engineering * Chemical engineering

* Mechanical engineering

* Engineering management

* Architectural engineering

* Civil engineering