Dimple plate horizontal evaporator effects.

摘要

Liquid is evaporated in a multi effect evaporator (10) having effects comprising sets of horizontally elongated dimpled plate evaporator elements (20, 21). Steam is introduced to the internal passage of at least the second set in all the effects, and a head of circulation liquid directs liquid being evaporated to flow downwardly from the head over the external surfaces of the sets of dimpled plates in a thin film. The vapor evaporated is drawn through a demistor (48) and is used as the heating fluid for the next effect. Recirculating liquid that has not evaporated and liquid separated by the demisting process are recirculated to the head associated with each effect. Clean condensate (61) -- such as distilled water - is withdrawn from the last effect. The liquid to be evaporated may be preheated by passing it (via 62) through the first sets of dimpled plates countercurrent to the flow of vapour. A vapour compressor (67) may be used to raise the temperature of the vapour withdrawn from the last effect and return it to the heating fluid inlet of the first effect.