GB454558A - Improvements in or relating to a process of and apparatus for separating water contained in a liquid - Google Patents

Abstract

<PICT:0454558/III/1> <PICT:0454558/III/2> In the separation of water from aqueous liquids by evaporation of the liquid in a countercurrent of air or gas, condensation of the vapour and return of the gas to the evaporator, evaporation is effected at substantially atmospheric pressure and at a low temperature, for example 60 DEG C. or below, and the circulation of the gas is effected solely by heating and cooling. The system is described as applied to the recovery of pure water from sea water and the separation of alcohol and water. In the apparatus shown in Fig. 1 for evaporating sea-water by heat derived from the sun, the sea-water flows from a drum 1 over a series of trays 4 in an inclined compartment having a glass front 6 and a heat insulated back <PICT:0454558/III/3> 5, and the vapour and circulating air pass to a condenser chamber 14 screened from the sun by the back 5. Concentrated sea water flows down into a collector 11 and distilled water to a vessel 16. In modifications the sea water is allowed to drop from notched edges of trays of clay; or flows down wick-like fabric plaited over horizontal bars. The concentrated salt-water may be returned to the upper tank for further treatment until salt crystallizes out on the trays. Apparatus for removing water from alcohol comprises a packed tower 30, Fig. 5, down which the liquid mixture is sprayed from a pipe 31, a tubular condenser 35 and a collecting vessel 39 below the tower provided with a jacket 40 for low temperature heating. Air or carbon dioxide, nitrogen or hydrogen circulates between the tower and the condenser, and alcohol containing little water is withdrawn from the condenser at 38. Alcohol containing a large proportion of water is supplied through a pipe 44 to the vessel 39, and the vapours evolved in the vessel are rectified by the stronger solution trickling down the tower. Liquid weak in alcohol is continuously withdrawn from the vessel by a pipe 43. A column-still for alcohol-water mixtures comprises a series of superposed evaporator vessels 50, Fig. 6, connected by pipes 53, 54 for the flow of air and vapour with superposed condensers 55. The mixture is supplied by pipe 60 to one of the vessels 50 and trickles over trays 52 therein and through a small aperture 56 in a separating partition to the vessel below. Condensate from the condenser of one vessel is passed by pipe 57 to the vessel next above until eventually alcohol is delivered at 58 from the uppermost condenser. The evaporator vessels are heat jacketed and the condensers are cooled by water, which may be artificially cooled by a refrigerating plant. Another column still is described in which the condensers on the right are connected by cross pipes with those on the left so that the gas current is carried from one condenser to the next above on the opposite side.