Verfahren zur Waermeeinsparung bei extraktiver Destillation

1,065,178. Extractive distillation. FARBENFABRIKEN BAYER A.G. Nov. 29, 1963 [Dec. 1, 1962], No. 47308/63. Heading BIB. Extractive distillation is carried out in distillation column 1 the base of which is connected by pipe 11 to a series of evaporators 25, 26, 27 and the vapours, formed by partial evaporation of the sump liquid from the column in the evaporators, are conducted into the base of column 1 through pipes 13, 14, 15, 33. The liquid mixture to be fractionated is fed to the column in the vapour state through pine 7, and the extraction liquid is supplied to the top section of the column through pipe 5. The more volatile components of the feed mixture are withdrawn from the head of column 1, and vapours of the less volatile components are withdrawn from the lower section of the column through pipe 31. The sump liquid leaves column 1 at a relatively low temperature, i.e. at a temperature which is higher than the temperature at the head of the column by only the amount corresponding to the pressuregradient in the column. The liquid flowing out of evaporator 27 enters column 36 where further quantities of the less volatile components of the feed mixture are vaporized. and are conducted into the lower section of the main column. The base of column 36 is connected to a series of evaporators 28, 29, 30. The liquid which flows out of evaporator 30 enters column 16, the sump liquid of which is heated by evaporator 17. The overhead vapours from column 16 are introduced into the lower section of column 36. The extraction liquid withdrawn from the base of column 16 is pumped through the heating-coils of evaporators 30, 29, 28. 27, 26, 25 and next through the heating-coil of the vaporizer 22 for the feed-mixture; the extraction liquid then flows through cooler 23 and is returned to the top section of the main column 1.