GB1162821A - Improvements in and relating to the Desalination of Brine - Google Patents

Abstract

1,162,821. Purification of water by freezing. SIMON-CARVES Ltd. 22 Aug., 1966 [8 June, 1965], No. 24145/65. Heading B1G. [Also in Division C1] In a process for the desalination of brine in which butane in a compression-condensation circuit is passed in direct contact with the brine in a freezing vessel to effect partial freezing, the slurry in the freezing, the slurry in the freezing vessel is agitated in such a manner as to maintain a substantially uniform distribution of ice crystals in the slurry. As illustrated, butane is compressed at 48 and passed through a heat exchanger 10 in direct contact with cold mother liquor to a condenser 6, whence it passes to the freezing vessel 2 in which it evaporates in direct contact with feedstock brine prior to return through a heat exchanger 8 to the compressor 48. Feedstock brine passes through the heat exchanger 8 in direct contact with brine, and through a double direct contact heat exchanger 11 in which it is cooled by cold mother liquor, to the freezing vessel 2 in which it is partially frozen by the boiling butane. Brine/ice slurry is passed to a centrifuge 4 from which separated brine mother liquor is passed by a pump 58 through the heat exchangers 11 and 10 to an exit line 29 including a butane separator 55. Purified water is added to the ice crystals at the centrifuge and in a tank 36 and the resulting slurry is passed by a pump 42 to the condenser 6 in which ice is melted by direct contact with partially gaseous butane. Purified water from the condenser is passed in part to the centrifuge and tank 36 and the remainder passes through a butane separator 46 for use. The freezing vessel 2 is provided with paddles 20 and with fixed baffles, and baffles may be provided over the butane outlet and brine/ice outlet to prevent the passage of brine and butane respectively. In a modification (Fig. 1, not shown), the heat-exchanger 11, pump 58 and butane separator 55 are omitted and all heat exchangers other than the freezing vessel itself are of direct contact type. Preferred operating conditions are disclosed.