Patent GB-985134-A (GB)
Title: A cyclic process for concentrating an aqueous liquid and recovering water therefrom
IPC: F25C3/00
Filed: 1961-04-24
Abstract: 985,134. Concentrating aqueous liquids. M. H. GORIN, and L ROSENSTEIN April 24, 1961, No. 14777/61. Heading A2D. [Also in Division F4] A process of concentrating an aqueous liquid and concurrently producing ice includes the steps of subjecting the aqueous liquid to a direct contact, heat exchanging relationship with a liquid immiscible with the aqueous liquid, the liquid being initially at a temperature lower than the temperature of the aqueous liquid, so producing a cooled aqueous liquid, then evaporating the or another liquid while in direct contact with the cooled aqueous liquid producing ice and a residual more concentrated aqueous liquid. The process may be used to purify sea water and remove water from milk, fruit juices and wine. Fig. 1 is a flow sheet which illustrates the purification of sea water according to one embodiment of the invention. Sea water enters a cooler B at about 20‹C. after being deaerated in a barometric leg A, and comes into direct contact with cold liquid propane entering via line 9 and leaving via line 10. The cooled sea water now at 0‹C. enters a freezer C via line 3 into which liquid propane evaporates fed by line 9a. The sea water is cooled still further forming ice at about minus 2.1‹C. average. The pressure in the freezer C is always maintained below the vapour pressure of the propane, so that the latter evaporates at a required rate. The slurry of ice and brine leaves the freezer C by line 5 and transfers to the separator E. The ice transfers by a path 6 to a melter F and cold water leaving the melter F by a line 8 transfers to a contactor G. Propane gas leaving the freezer C is compressed by a compressor D and condensed in the melter F. The refrigerating cycle of the propane is completed by liquid propane leaving the melter F by line 9 and entering the freezer C. Warm liquid propane enters contactor G by line 10 at about 20‹C. and is cooled to about 0‹C. before leaving by line 12. Cold brine enters a contactor H by line 13 and cools warm liquid propane entering by line 14 at about 20‹C. to about 0‹C. The cooled liquid propane leaves by line 15. All heat exchanges take place by direct counter-current contacts of immiscible liquids and direct contact between vapour and solid. In a second embodiment (Fig 2, not shown), the refrigerating cycle is separate from the cooling cycle. Kerosene is used instead of propane in the precooler B and the contactors G and H. The ice produced by freezing sea water is not pure as a certain amount of residual brine is occluded. This is removed with the first portion of ice to melt; therefore, the melter F need not be considered only as a single vessel, but as a number of such vessels in which fractionation by melting may take place. Mentioned as suitable refrigerants as well as heat exchange liquids are ethane, ethylene, propane, propene, iso-butane, isobutene, methyl chloride, and di-chloro-difluoro-methane. Mentioned as suitable heat exchange liquids are octane, kerosene, xylene, blends of hydrocarbon known as "paint thinner", vegetable oils such as cotton seed oil, diethyl, di-butyl or analogous phthalates.