GB737570A - Improvements in or relating to the recovery of glycerol from industrial liquors by evaporation - Google Patents

Abstract

<PICT:0737570/III/1> <PICT:0737570/III/2> Glycerol is recovered from liquors which contain a high proportion of solids (e.g. concentrated fermentation liquors or soap lyes) by causing the liquor to flow in the form of a film down the surface or surfaces of one or more vertical tubes enclosed in a vessel maintained at sub-atmospheric pressure, said tube or tubes being heated to such a temperature that the glycerol is vaporized from the liquor and leaves a residue which remains in the fluid state. The glycerol vapours are passed to a condenser or to a series of condensers, while the fluid residue flows from the lower part of the surface or surfaces into a vessel from which it is pumped at such a rate that sufficient fluid residue is maintained therein to form a seal for the region at sub-atmospheric pressure. The film-supporting surface may be the internal surface of a vertical tube surrounded by a jacket containing heating medium, or several such tubes may be used. Alternatively, the external surfaces of internally heated vertical tubes may be used. Fermentation glycerol containing 56 per cent glycerol, 13 per cent water and 22 per cent residue passes from tank 4 (Fig. 1) into preheater 6 where it is heated to 138 DEG C. The preheated liquor then flows onto the inner surface of tube 11 through slot 10 (Fig. 2). Tube 11, which is made of stainless steel and is 15 feet long and 1.5 inches internal diameter, is heated by steam at 190 p.s.i.g. in jacket 12. A pressure of 31 mm. Hg. (absolute) is maintained in tube 11 by means of a vacuum pump (not shown) connected to pipe 29. The distilled vapours pass through pipe 17 to condenser 18, which is cooled by boiling water; and a fraction of high glycerol content (97 per cent) condenses, which is collected in receiver 22. The vapours which have not been condensed pass on to condenser 24, which is cooled by cold water, to give a condensate containing 57 per cent glycerol and 33 per cent water, which is collected in receiver 28. The non-volatile residue is removed from the bottom of tube 11 by pump 15.