GB845824A - Improvements in apparatus for and method of removing impurities from a vapour mixture such as carbon dioxide vapour containing other vapours - Google Patents

Abstract

A method of purifying a vapour such as carbon dioxide in a vapour mixture containing vapours of at least two other and mutually soluble compounds such as water and alcohol having widely different solidification temperatures so that one compound substantially lowers the solidification temperature of the other compound when the two materials are <PICT:0845824/III/1> in solution, comprises the steps of increasing the proportion in the vapour mixture of the compound having the lowest solidification temperature, and then cooling the vapour mixture to a temperature substantially lower than the solidification temperature of the mutually soluble compound having the higher solidification temperature, condensing the said other vapours of both compounds in said vapour mixture while utilizing the original low temperature solidifying compound of said vapour mixture as enriched, to permit such low temperature condensation while preventing solidification of the condensate with resulting accumulation on cooled surfaces, continuously refluxing substantially all of the condensate to the vapour mixture for use in increasing the proportion of the lower temperature solidifying compound therein, and withdrawing the cooled uncondensed vapour. In a preferred embodiment used to remove the impurities from the fermentation vapour mixture of a brewing process, CO2 containing water vapour, alcohol, aldehydes and esters is led via a pipe 21 from a fermentation tank 20 to a separator 22 where suspended solids and liquids are deposited. The vapour mixture then passes through a line 24 into a blower 25 and after passing through a heat exchanger 26 it leaves through pipe 30 at about 80 DEG F. and is then cooled in a heat exchanger 31 to about 320 DEG F. by a medium such as ethylene glycol. The vapours then pass to a fractionating column 39, in which the vapour mixture becomes enriched with alcohol, and leaves through an outlet pipe 50 and enters a horizontal heat exchanger 51 in which it can be cooled to -45 DEG F. without forming ice. Fog which may be formed is removed by a trap 55 and purified CO2 passes to a compressor 58 which is compressed to 75 p.s.i.a.