Patent GB-995156-A (GB)
Title: Concentration of solutions by solid formation
IPC: C02F1/22
Filed: 1962-07-03
Abstract: 995,156. Concentrating liquids by cooling. M. H. GORIN, and L. ROSENSTEIN. July 3, 1962 [July 3, 1961], No. 25510/62. Heading F4H. A process for separating a less and a more concentrated solution from a solution of intermediate concentration comprises contacting the latter solution directly with a liquid refrigerant to form a solid, a residual solution and refrigerant vapour, separating the solid from the residual solution, washing the solid with a heat exchange liquid, compressing the refrigerant vapour and melting the solid by direct contact with the compressed refrigerant vapour. As shown in a process for obtaining relatively pure water from sea water supplied through a line 10, the sea water is precooled by liquid butane in a vessel 11, the cooled sea water being then supplied through lines 14 and 16, together with butane from line 38, to a low-pressure freezing vessel 15 where the butane evaporates and the brine is partially frozen. The brine and ice slurry is supplied through a line 19 to a vessel 20 where the ice is washed with warm liquid butane supplied through lines 13, 21 from the pre-cooler 11. Ice then passes to a second washing vessel 23 where it is washed and partially melted by warm compressed butane vapour taken from the outlet line 24 of a compressor 18 through line 25, the compressor 18 being supplied with butane vapour from the freezer vessel 15 through a line 17. The ice is finally melted in a vessel 27 by further butane vapour from line 24, the resulting water leaving the vessel through a line 30 and liquid butane through a line 31 to rejoin the butane in line 12 for use in the pre-cooler 11. The butane vapour remaining in line 24 is compressed in an auxiliary compressor 45, condensed in a condenser 47 and then is supplied to heat exchangers 39 and 40, in which it is cooled by contact with brine from a line 33 and water from the line 30 respectively, before passing to the line 12. The brine in line 33 is obtained from a separator 32 which receives brine and butane from the vessel 20 through line 21a, butane from the separator being returned to line 12 through line 34. A further separator 35 receives liquid butane and water from vessel 23, the water therefrom being recirculated to the freezer 15 through a line 37 and the butane being returned to line 12 through a line 36. Concentrated brine and relatively pure water leave heat exchangers 39 and 40 through lines 43 and 44 respectively. In a second embodiment (Fig. 2, not shown), the pre-cooling and washing steps in the process are effected by liquid octane which flows in a separate circuit from the refrigerant (butene-1), the latter being used as before to freeze and melt the brine. The process may be used to concentrate orange juice, coffee, beer or wine for subsequent freezing and the solids formed in the process may comprise a refrigerant hydrate instead of or in addition to the ice. Examples of suitable refrigerants for use in the process are propane, isobutane, butene-2, isobutylene, methyl chloride, fluorohydrocarbons, carbon dioxide, ammonia, field butane or LPG. Specification 993,263 is referred to.