Flash evaporator for e.g. seawater or industrial effluent - has tapering duct to flash nozzles and diverging evaporator duct in each stage

摘要

A flash evaporator comprises a series of evaporator stages, each discharging through one or more flash nozzles into the next stage, the direction of discharge being transverse to the general flow direction. The evaporator comprises two sets of ducts, one set of lateral ducts tapers in its cross-section in the direction of flow towards the end of each evaporator stage, while the other duct or set of ducts increases in cross-section in the same direction. The water discharged from the first set of ducts through the flash nozzles into the second duct and at the downstream of the second duct, the water returns to the first duct of the next stage. A condenser receives and condenses the vapour from the second, diverging set of ducts. Used for any flash evapn. e.g. evapn. of sea water or industrial effluent, where the viscosity may be high. The arrangement ensures that a heavy thick layer of water does not discharge over the weir or nozzle into the evapn. duct, but that a sufficient area is exposed to evapn. to achieve improved thermal efficiency.