GB598346A - Improved process and apparatus for the rectification of impure alcoholic liquids - Google Patents

Abstract

<PICT:0598346/III/1> <PICT:0598346/III/2> Pure 95 per cent. alcohol is recovered from raw alcoholic aqueous liquids obtained by fermentation and containing also other alcohols, esters, ketones, acids, amines and acetals, by introducing the impure liquid into the intermediate part of a first (distillation) column heated at its lower end and washed with a spray of hot aqueous liquid fed in at the top end, transferring the partly purified liquid from the bottom of the first column to a second (concentration) column from which purified concentrated alcohol is recovered at a point near the top while impurities collecting at the middle of the column are returned to the first column at a point a few plates above the point of introduction of the raw liquid. The vinasses recovered at the bottom of the second column are preferably used as the washing liquid for the first column while head impurities from the second column are returned to the first column. Vapours from the top of the first column are redistilled in a third column to recover aldehydes &c. Feed from a tank 1 flows through heat exchanger 4 and line 5 to the first column 6 and the partly concentrated alcohol is transferred through pipe 11 to the second column 12 from which the purified concentrated alcohol is recovered through line 12 and cooler 18. The exhausted vinasses are returned through lines 15, 15a to the top of column 6 to serve as washing liquid, while alcoholic &c. impurities collecting at the middle of the column are removed through taps R1, R2, R3, R4 and fed by emulsifier 21a to column 6. Vapours from top of column 12 pass through heat exchangers 4, 16, the condensate being in part recycled as reflux to column 12 through line 4a and in part being fed through line 10d to column 6. The vapours from column 6 are passed to the third column 7 surmounted by condenser 8 where they are fractionated to recover aldehydes esters and ketones through tap 9, and a liquid rich in propyl alcohol but also containing esters, ketones and acetals through tap 9a. Liquid recovered from the bottom of this column is cooled and passed to a separator 9c where separation into layers takes place. The upper layer rich in higher alcohols is removed through overflow 10 while the aqueous layer is mixed in a reheater 10c with the condensate in line 10d and fed back to the middle part of column 6. The Specification as open to inspection under Sect. 91 describes recovery of amines from the vapours issuing from the top of column 12 by passing these through line 25, Fig. 2 (Cancelled), into a column 26 where they are sprayed with dilute acid solution fed through 27 the amines being converted to non volatile salts the remaining vapours being condensed in cooler 28 and passed through line 29 to column 6. This subject-matter does not appear in the Specification as accepted.