Technical Data

Selection of equipment
The selection of optimum equipment and appropriate piping plan are necessary for realization of excellent temperature control.
Direction for the selection of equipment and precautions for the piping plan are given in the following paragraph.

Desuperheater
When selecting a desuperheater, it is necessary to know the type of equipment for which the desuperheated steam is used.
Particularly, it is important to know the operation conditions such as the range or load fluctuation of the downstream equipment
and the allowable range of drain.

It is also necessary to predict the cooling water condition, auxiliary steam condition, and the transient conditions at start and stop of the plant.
Thus, when designing a new plant, the planner is required to make delicate considerations on the design of the desuperheater.
It is desirable that the selection of the desuperheater and the composition of the control loop be determined
through detailed discussion with the maker.

Required control range for the valve
In order to achieve a stable temperature control, the plan must be worked out so that the cooling water control valve can be smoothly
operated over the entire range of load.
The valve is required not only to control the cooling water needed during high load operation but also to sufficiently control the minimum
volume of water during low load operation which is calculated through the enthalpy method.

Generally, the steam temperature at the inlet of desuperheater tends to decrease with decrease in load, and the required turn-down ratio
for the cooling water control valve(ratio of minimum controllable value of Cv and maximum controllable value of Cv)
is considerably greater than the turn-down ratio of desuperheater.

Performance

High efficiency atomization.

High rangeability variable area spray unit.

Accurate and repeatable control of fluid temperature
to within 6C deg providing appropriate installation and
instrumentation are used.

High spray water pressure capability.

Design

Wide variation of design options.

Wide range of available nozzle sizes.

Erosion resistant materials of construction.

Minimum number of components.

Low maintenance featured.

Fully rationalized.

Wide range of actuating mechanism available.