Variable Spray Desuperheaters (VSD) are recommended under low load conditions where the load is reduced, and the spray nozzle area is also reduced. The VSD provides more economical control of steam temperature by introducing cooling water into the steam flow through a nozzle of advanced design.
The design of the VSD eliminates the need for a separate water control valve, which allows maximum water pressure at the nozzle.
The VSD consists of a piston ring, stem, nozzle tube, nozzle head, seat ring, and plug. The nozzle tube assembly fits into the bore of the mounting flange and is locked in place by a retaining ring. The coolant inlet connection can be located in any direction in relation to the nozzle spray discharge.