GB855550A - Improvements in or relating to evaporators - Google Patents

Abstract

<PICT:0855550/III/1> <PICT:0855550/III/2> A multi-stage flash evaporator comprises a series of heaters and a series of flash chambers located in a common vessel, each heater being provided with tubes arranged for the passage therethrough of liquid to be evaporated and for the liquid to be heated therein by liquid flashed off in the flash chambers, a single nest of tubes extending through at least two adjacent heaters, the tubes passing from one heater to the next through a partition wall common to them both. A rectangular vessel 30 is divided by horizontal and vertical partitions 34 and 32 into two layers of evaporators in pairs. Each evaporator comprises a flash zone 14 and a heat-transfer zone 10 (wherein the vapour from zone 14 is condensed by contact with the cold liquid in pipes 36) connected through water vapour separators 46 which remove water entrained in the flashed vapour. The liquid to be evaporated is heated by passage through the heaters within the nest of tubes 36. To aid venting between stages the holes in the partitions through which the tubes pass may be of larger diameter than the tubes or additional venting holes may be provided. The heater associated with the highest temperature flash chamber may be vented separately since the bulk of the non-condensible gases, e.g. CO2, will be released therein. The apparatus may be used to purify sea water.