GB723230A - Improvements in or relating to the recovery of glycerol - Google Patents

Abstract

<PICT:0723230/III/1> Glycerol is recovered from a concentrated fermentation liquor by mixing therewith a granular material in an amount and for a time sufficient to form a free-flowing mixture, continuously agitating the mixture while heating it under reduced pressure to distil glycerol-containing vapours therefrom, and continuously replacing the spent and removed mixture by fresh free-flowing mixture. The time of contact of the glycerol with a heated surface is thus kept to a minimum. The vapours may be wholly condensed and the glycerol recovered by distillation, or the glycerol may be directly recovered by fractional condensation of the vapours. The fermentation liquors used are obtained by the fermentation of carbohydrates such as sugars, starch and molasses. The granular materials specified comprise sand, coke, Fuller's earth, kieselguhr and anhydrous sodium sulphate. The mixture may be agitated by any mechanical means such as by rakes or paddle stirrers or by vibrating the vessel containing the free-flowing mixture. The heating may be effected by a steam-heated jacket, radiant heat or high-frequency heating. The granular material may be recovered for re-use by washing with water and drying and, if necessary, burning off the residue on the granules. In a suitable apparatus, a mixture of concentrated fermentation liquor comprising glycerol, water and solids, obtained by concentrating and stripping the liquor obtained by fermenting blackstrap molasses, together with kieselguhr in given proportions, is fed into a hopper 1 on to a feed tray 2 attached to a tube 3 having a heating jacket 4 maintained at 180 DEG -200 DEG C. by steam heating. The pressure in the tube is maintained at two mms. The jacketed tube is mounted on spring leaves 19 on a rigid support 20, the leaves being at an angle of 70 degrees. The tube is vibrated by means of the piston 21 of a hydraulic pump 22 acting at right angles to the leaves 19, a vibration frequency of 1,500 cycles per minute being used. The tube 3 is connected to an extension piece 10 having an outlet 11 for spent material. The vapours pass into a cyclone 13 p for removal of dust at 14 and then to a condenser 16, condensate collecting in a receiver 17.