Patent GB-394086-A (GB)
Title: Process for dehydrating organic liquids and apparatus therefor
IPC: C07C51/42
Filed: 1932-03-15
Abstract: <PICT:0394086/IV/1> <PICT:0394086/IV/2> Organic liquids are dehydrated by subjecting their vapours to the action of anhydrous calcium sulphate obtained by heating either plaster of Paris or mineral gypsum to 160-180 DEG  C. or higher, the anhydrous sulphate being used in such quantity as to be converted into the semihydrate. The process is particularly applicable to liquids which have boiling points close to that of water, or form azeotropic mixtures with water, or decompose when heated with water.  Examples of liquids are acetal, acetaldehyde, aldehyde - ammonia, formic acid, amylene hydrate, crotonaldehyde, acetic acid, isobutyl alcohol, propyl and iso-propyl alcohol, ethyl alcohol, piperidine, pyridine and its homologues, chloral, chlorhydrin, chloracetone, cyclohexanol.  In one form of apparatus the sulphate is arranged in layers in a tower and is periodically regenerated without removal, air at 200 DEG  C. being passed through alternately with the vapours of the pyridine to be dehydrated.  In another form of apparatus, Figs. 1 and 2, operating continuously, the vapours of alcohol enter an externally heated drum a at c and leave at d, calcium sulphate circulating in counter-current through the drums a, b and meeting in the drum b a counter-current of air or furnace gases at above 160 DEG  C.  The sulphate is freed from any alcohol residue by a counter-current of superheated steam when descending a small interposed tower e, such alcohol being recovered by condensation.  Gas-tight connections between the parts are ensured by upwardly directed conveyer screws f following downward feed pipes g.  In a modification, used for isopropyl alcohol, drum b is enlarged and provided with a jacket in which the vapours of, e.g. ortho-dichlorobenzene, boiling at 160-170 DEG  C., are condensed for dehydrating the sulphate.  The calcium sulphate may be mixed with 2 per cent or more of silica gel, kieselguhr, talc, fuller's earth, clay, iron oxide, sand, or coke for preventing caking or adherence to the walls.ALSO:<PICT:0394086/III/1> <PICT:0394086/III/2> Alcohol is dehydrated by subjecting the vapours to the action of anhydrous calcium sulphate obtained by heating either plaster of Paris or mineral gypsum to 160-180 DEG  C. or higher, the anhydrous sulphate being used in such quantity as to be converted into the semihydrate.  In one form of apparatus the sulphate is arranged in layers in a tower and is periodically regenerated without removal, air at 200 DEG  C. being passed through alternately with the vapours. In another form of apparatus, Figs. 1 and 2, operating continuously, the vapours of alcohol enter an externally heated drum a at c and leave at d, calcium sulphate circulating in countercurrent through the drums a, b and meeting in the drum b a countercurrent of air or furnace gases at above 150 DEG C.  The sulphate is freed from any alcohol residue by a countercurrent of superheated steam when descending a small interposed tower e, such alcohol being recovered by condensation. Gastight connections between the parts are ensured by upwardly directed conveyer screws f following downward feed pipes g.  In a modification, used particularly for isopropyl alcohol, drum b is enlarged and provided with a jacket in which the vapours of e.g. ortho-dichlorobenzene, boiling at 160-170 DEG  C., are condensed, for dehydrating the sulphate.  The calcium sulphate may be mixed with 2 per cent or more of silica gel, kieselguhr, talc, fuller's earth, clay, iron oxide, sand or coke for preventing caking or adherence to the walls.