The desuperheater DAM-D is typically used in combination with a steam pressure reducing valve to create a steam conditioning valve. The VLR steam conditioning valve uses the DAM-D as its desuperheating component. The DAM-D can be welded to the outlet or installed close downstream from the steam pressure reducing valve. Apart from providing desuperheating functionality to the upstream pressure reducing valve, the DAM-D also straightens the often very non-uniform flow patterns that are created by the pressure reducing valve. The DAM-D also reduces noise and creates a backpressure that reduces or eliminates high velocity in the valve’s outlet.
The DAM-D steam desuperheater is used in desuperheater applications where large spray water flows are required.
The DAM-D desuperheater consists of two stages. The first stage, the pressure reducing stage, consists of one or several perforated cylinders installed directly after the desuperheater inlet. The second stage consists of a series of mechanically opening spray nozzles inserted in to the desuperheater outlet. The size of nozzles, their number and insertion length may vary depending on steam desuperheating needs. In case of large pipes, they may use multiple insertion lengths in order to improve coverage. The spray nozzles receive water from a common water pipe encircling the desuperheater. The spray water flow must be controlled externally through a water control valve.
- Pressure reduction -Pressure reduction in the desuperheater depends on the number of pipes installed after the inlet, as well as their drill patterns. Placing the pipes in the DAM-D reduces the necessary outlet size of the upstream pressure control valve when installed separately. It can also provide this feature to an existing pressure control valve when a secondary pressure reducing stage is desired.
- Flow pattern- The pressure reducing pipes straighten the often non-uniform flow patterns created by the upstream pressure control valve, and create a backpressure that reduces and/or eliminates high velocities in its outlet. They also redirect the flow towards the center of the pipe and water away from the pipe wall, removing the need for a thermal liner. The increased steam flow speed caused by the pipes creates higher dynamic forces acting on the water droplets injected by the spray nozzles, improving their evaporation.
- Noise abatement- The multiple pressure-reducing pipes serve as a diffuser, where the steam flow is broken up into a great number of partial fluid jets. This improves the rapid dissipation of kinetic energy in the steam, resulting in a substantially reduced emission of noise and vibration.