GB989866A - Art of separating water from aqueous liquid by freezing - Google Patents

Abstract

989,866. Concentrating liquids by freezing. H. H. CLARK, and B. C. BRIGGS. July 8, 1963, No. 26912/63. Heading F4H. In a process for freezing out water from a liquid the liquid is introduced into a continuous stream of a cooled, water-immiscible carrier liquid. As shown in Fig. 1 the liquid, e.g. spent sulphite liquor, brine or fruit juice, is supplied through a line 8, pre-cooler 9 and line 10 to a spray assembly 12 at the top of a freezing vessel 1. A cooled carrier liquid, e.g. kerosene, is also introduced into the vessel 1 via a manifold 18 and apertures 20 at a substantially greater rate than that of the liquid from spray 12, so that the latter becomes dispersed in and partially frozen by the carrier liquid. The bottom of the vessel 1 is disposed in a tank 21 immediately above a wire-mesh conveyer 22 which retains the ice-crystals and mother liquor while permitting the passage of carrier liquid, the latter being withdrawn from the tank by a pump 32, cooled in the evaporator 62 of a refrigerative system and recirculated to the vessel 1 through line 16. The ice and mother liquor are conveyed to a centrifuge 37 which discharges liquor and any entrained carrier liquid to a separator 52, the carrier liquid being supplied by a pump 54 to pump 32 and the mother liquor being recirculated to spray 12 through line 58. The ice from the centrifuge is digested with water from a spray ring 40 to form a slurry which is forwarded through a line 44 to a valve 45 and thence either to the precooler 9 or to a line 48. Well water from the pre-cooler may be recirculated to the spray 40 via a line 50, the remainder passing through the line 48 to cool the condenser 49 of the refrigerating system. The heated water then passes through a line 63 to a heat exchanger 60 which is used to heat mother liquor from separator 52 to reduce the viscosity of the liquor which is discharged, together with liquor drawn off from the tank 21 through line 34, through a line 36. The water is discharged at 64. In the modification of Fig. 6 (not shown) the tank 21 and conveyer 22 are omitted and the carrier liquid is extracted from the vessel 1 through circumferential outlets while the ice and mother liquor continue to move downwardly to an axial outlet.