GB785127A - Improvements in or relating to methods of distilling commercial glycerol liquors - Google Patents

Abstract

<PICT:0785127/III/1> <PICT:0785127/III/2> Aqueous glycerine liquor is distilled in a vessel maintained under reduced pressure, by injecting the liquor into a hot pool of concentrated liquor in the vessel, or by projecting the liquor against a hot wall of the vessel, the conditions of temperature and pressure in either case being maintained such that rapid vaporization of the bulk of the liquor occurs leaving only a saline slurry as residue. The apparatus shown in Fig. 4 comprises a jacketed still 1 provided near the base with a heating-coil, sight-glasses 5 and 51, and a gauge-glass 6. The base of the still is connected to a slurry-extractor 9 and a drying-device 10. The top of the still is connected by a vapour-pipe 3 to an entrainment-separator 4 which has a pipe for returning separated liquor to the still. The still is charged with liquor until the heating-coil is immersed, and put under vacuum; and heating-medium is then passed through the coil and the jacket. The first action is the concentration of the liquor with progressive rise in temperature; and fresh liquor is pumped in via injection-pipe 8 to maintain the level of liquid as seen in sight-glass 5. At the same time, saline slurry is removed through extractor 9 so that the upper level of the sediment, as seen through sight-glass 51, remains constant. When the pool of glycerine in the still is sufficiently concentrated, the temperature of the still is raised until the distillation-temperature of the feed-liquor is attained (for a liquor of 40 per cent glycerine content and a still-pressure of 60 mm., this temperature is about 160 DEG C.). The distillation of the fresh liquor is thereby effected, the vapours having substantially the same composition as the liquor. Glycerine is extracted from the "dried" salt by washing it with the fresh liquor. The apparatus shown in Fig. 5 comprises a jacketed vessel which is provided with a rotary scraper 12 in the form of an Archimedean screw. The liquor is sprayed on to the hot walls of the vessel via the hollow shaft of the scraper and nozzles 13. The bulk of the liquor is vaporized, and the saline slurry residue is scraped towards drain-cock 2. The vapours from either apparatus may be subjected to fractional condensation to obtain glycerine itself.