Venturi desuperheater is a self atomizing type device. Cooling water is introduced into the central nozzle and atomized by flow of steam at high velocity. When leaving the nozzle, the fog enters the main flow at the venturi throat without contacting the side walls, getting effective desuperheating with minimum erosion. High turbulence at the venturi throat improves the heat and mass transfer to get close approach to saturation temperature and moderate turndown ratios.
VENTURI ASSISTED DESUPERHEATER
Is similar to the former but uses high pressure steam to atomize the cooling water, with a steam ejector nozzle type. As the water dispertion is independent of the steam flow, it has turndown ratios of 50 to 1 and very good approach to saturation temperature.
Is the simplest desuperheater. It uses high pressure water in a special nozzle to obtain the atomization. It is used for low approach and turn down ratios.
VARIABLE AREA DESUPERHEATER
Variable area desuperheater eliminates need for separate water control valve. They form a simple, compact and low cost unit. Essentially, it is a constant pressure mechanical atomizing device usual mounted on the main steam pipe through a DN 80 (3") flange; The steam enters to the center of the pipe in order to give a uniform water distribution. Cooling water at a pressure at last 4 bar higher than steam usual enter through a DN 25 flange, flow down into the cylinder-seat devices and leave the jacket through several nozzles, as conical jets.