PROCESS AND PLANT FOR MULTI-STAGE FLASH DESALINATION OF WATER

摘要

In a multi-stage desalination process, the pre-heated recirculated feed stream is heated in brine heater 1 and then released to flash in first desalination stage via valve 3. The feed stream is flashed through a series of desalination zones 4, the steam condensing on tubes 5 cooled by the recirculated feed stream. Product water is collected in water trough 6, and flashes down between stages to heat rejection stage(s) 7. Feed stream is recirculated by pumps 8 through desalination and heat rejection zones. Non-condensible gases are extracted by ejectors 9. Condensing sections of heat exchange rejection stages are cooled by sea water 11. Warm sea water is recycled Ivia/I deaerator 12 and make up pump 13. The thermal recycle stream may be a portion of the product stream, a portion of the depleted feed stream or the feed stream before it is supplied to the first heat exchange zone.