PRDV control valve is a very efficient and compact equipment for steam conditioning either in turbine by-pass lines discharging to condenser or in cogeration processes (see included layout). Conditioning includes pressure reduction and integrated desuperheating devices. Pressure reduction is obtained through three stages, except in LP applications where two stages are adequate to provide good performance and noise limitation. The first stage is the throttling section where flow rate is adjusted by the change of plug position inside a drilled cage. The second stage is a fixed resistance performed by a drilled basket, which creates a backpressure on the seat in order to reduce its velocity head and the generated noise. The third stage has a patented cone-shaped special designed drilled ring wich contributes to noise reduction and improves the mixing of steam with the downstream injected water. Shape and orientation of this ring optimize the steam impact against the external surface of sprayed water pattern, where the biggest water drops tend to reunite and to improve the atomizing efficiency of the equipment as a whole. Desuperheating section consists of a chamber installed downstream the third stage where some spring-assisted nozzles are mounted. Great care is taken to avoid any risk of thermal shocks, including a jacketing of internal surface of injection chamber which is recommended for high pressure sytems and whenever steam inlet temperature exceeds 500°C.
- Sizes: sizes depending on service conditions
- Ratings: inlet section up to ANSI 2500. Outlet section up to ANSI 900 included
- Construction: from bar stock or forgings. Inlet connnection and injection chamber are welded to main body section
- Pressure seal design for inlet ratings over ANSI 900
- Materials: carbon steel or Cr-Mo steels, F91 (9%Cr) depending on service conditions