GB958596A - A method of and apparatus for cooling and crystallising saline solutions - Google Patents

Abstract

958,596. Crystallizing saline solutions by evaporation. KESTNER EVAPORATOR & ENGINEERING CO. Ltd. July 25, 1962 [Aug. 4, 1961], No. 28379/61. Heading B1B. Saline solutions, such as pickle and spin bath liquors, are crystallized by flash evaporation without external heating in a multi-stage vacuum evaporator, wherein the vacuum increases progressively from one stage to the next, and the solution flows by gravity through the successive stages of the vessel. The feed to the three stage vacuum vessel 10 enters the first stage 13 via pipe 16 and flows by gravity down pipe 17 into stage 14, down pipe 18 into stage 15, and finally leaves the vessel via pipe 20. Different degrees of vacuum are maintained in stages 13, 14 and 15 by the steam ejectors 30 connected via the manifold 31 to the direct contact condenser 32, which is connected to a vacuum pump via line 2. Evaporation of the feed occurs under the reduced pressure in stage 13, and the vapour produced is extracted from the system via the aperture 27 in the separator 26, which serves to remove entrained liquid from the vapour. The cooled liquid from stage 13 passes into stage 14 and is cooled further by evaporation under a lower pressure. Similarly, the liquid leaving stage 14 is cooled further in stage 15. The liquid in each stage is agitated by a controlled supply of air admitted via pipe 24 and distributer 25. The liquid finally withdrawn from the vessel via line 20, containing the crystals formed during its passage through the vessel, is pumped into a centrifuge or filter 23 having a discharge outlet 4 for the separated crystals and an outlet 5 for the mother liquor.