1,239,432. Evaporators, multi-stage flash type; desalination of water. HYDRO CHEMICAL & MINERAL CORP. 10 July, 1968 [17 July, 1967; 6 June, 1968], No. 33006/68. Heading B1B. Multi-stage evaporation of liquid, e.g. saline water from reservoir R 1 , is carried out by preheating it in heat-exchanger H 2 and then passing it in succession through a series of flash evaporators E 1 , E 2 .. E n arranged at successively increasing elevation and maintained at successively -lower pressure, the liquid being driven from one evaporator to the next through a U-tube T 2 , T 3 .. by the boiling of the liquid as it rises up the longer leg of the U-tube. The vapour in each evaporator passes through cyclone 10 and demister 11, and then flows to an associated directcontact condenser C 1 , C 2 .. C n . The uppermost condenser Cn is supplied with cool desalinated water from tank R 4 . Each condenser contains perforated plates and a liquidseal. The condensate (desalinated water) flows down by gravity through the series of condensers. The hot condensate from the lowermost condenser C, is cooled, by contact with upflowing drops of hydrocarbon oil, in heatexchanger H 1 . Part of the cool distillate is pumped to tank R 5 whence it flows to tank R 4 . The remainder of the distillate is withdrawn from the system via power generator M 2 and outlet 40. The saline water to the treated is heated in H 2 by contact with hot oil withdrawn from H 1 . Residual brine flows from E n into tank R 3 , and is withdrawn from the system via power generator M 1 and outlet 22. Boiling liquid may also rise from one evaporator to the next by the arrangement shown in Fig. 5. An apparatus is described wherein each distillation stage comprises an evaporator and a condenser arranged in the same housing.
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