GB505580A - Improvements in or relating to vacuum distillation - Google Patents

Abstract

505,580. Vacuum distillation; utilizing vapours for further evaporation. PHIPPS, J. W. and BRITISH DRUG HOUSES, Ltd. Nov. 12, 1937, No. 31161. [Class 32] In vacuum distillation the vapours are condensed in contact with the wall of a condenser filled with a liquid refrigerant maintained at its boiling point, the vapours and the refrigerant flowing over the surfaces so as to prevent freezing of the condensed vapour. 'The cooling liquid may be ammonia, methyl chloride, ethyl chloride, sulphur dioxide, dichloro-difluoromethane, or water. As shown, liquid is evaporated in a vessel 11 under a vacuum maintained by a pump 19. The vapours pass through a liquid trap 16 to a condenser 12 cooled by a refrigerant boiling in the tubes 21, the condensed vapours being removed through the chambers 20, 23, without destroying the vacuum. The vaporized refrigerant passes through a separator 17 to a compressor 13 and condenser 14 and thence as liquid through a trap 15 and the separator 17 back to the tubes 21 of the condenser 12. A spring-loaded valve 22 returns liquid refrigerant to the condenser 14 if the pressure in the tube 21 becomes too high. In modifications, some of the tubes of the condenser 12 are placed underneath a baffle in the lower part of the condenser chamber near the exit for uncondensed gases, to ensure that these latter are cooled substantially to the temperature of the entering refrigerant ; baffles are provided to ensure flow of the vapours over the tubes ; the condenser 12 is constructed of vertical thimble tubes dipping into the condensed liquid. The temperature of the ovaporated refrigerant may be controlled by a thermostat, or the speed of the compressor 13 may be controlled by variations of pressure in the evaporator.