GB368078A - Improved process and apparatus for the precipitation of carbohydrates and carbohydrate compounds - Google Patents

Abstract

<PICT:0368078/III/1> <PICT:0368078/III/2> Carbohydrates and their compounds, e.g. cellulose acetate, cellulose ethers, cellulose xanthogenate, cellulose copper oxide ammonia, &c. are precipitated from their solutions by aqueous or organic liquid precipitants or mixtures thereof with solvents by a process in which the solution is finely divided, for example by centrifugal force, and after traversing a free space impinges at any desired angle on the precipitant which has also traversed a free path, the amount of solution being considerably less than the amount of precipitant. The liquids become intensively and thoroughly mixed, and by adjustment of the amount and velocity of flow of the liquids the nature of the precipitate may be regulated. As precipitants, water, salt solutions, acids, bases, hydrocarbons, hexane, benzene, petroleum, alcohols, aldehydes, esters, ethers &c. may be employed and may be mixed with solvents. Fig. 1 shows one form of apparatus for carrying out the process wherein the solution is fed through a valved pipe 1 to a perforated drum 2, rotated through stepped pulleys 19, and passes through slits 20 into the free space of the vessel 3; precipitant is supplied by a pump 12 and pipe 10 to conduits 4, 5, 6 terminating in slits 17. The mixture of precipitant, solvent and precipitate is discharged through pipes 8, 9 to a separator 14 furnished with a sieve 15 from which the precipitate is removed through an opening 25. The mixture of solvent and precipitant is partly discharged through a valved pipe 16 and is partly returned to the pump 12, fresh precipitant being introduced through a pipe 11. Fig. 2 shows a modified apparatus in which the precipitant is fed to the upper part 29 of a double perforated drum 26, and in which the vessel 27 also rotates. Examples are given of the precipitation of cellulose acetate dissolved in acetic acid by means of dilute acetic acid and water, and of cellulose dissolved in ammoniacal copper oxide by means of alkali. The Specification as open to inspection under Sect. 91 (3) (a) describes also the use of coating jets or nozzles. This subject-matter does not appear in the Specification as accepted.ALSO:Carbohydrates and their compounds, e.g. cellulose acetate, cellulose ethers, cellulose xanthogenate, cellulose copper oxide ammonia, &c. are precipitated from their solutions by aqueous or organic liquid precipitants or mixtures thereof with solvents by a process in which the solution is finely divided for example by centrifugal force and after traversing a free space impinges at any desired angle on the precipitant which has also traversed a free path, the amount of solution being considerably less than the amount of precipitant. The liquids become intensively and thoroughly mixed, and by adjustment of the amount and velocity of flow of the liquids the nature of the precipitate may be regulated. As precipitants, water, salt solutions, acids, bases, hydrocarbons, hexane, benzene, petroleum, alcohols, aldehydes, esters, ethers, &c. may be employed and may be mixed with solvents. Fig. 1 shows one form of apparatus for carrying out the process wherein the solution is fed through a valved pipe 1 to a perforated drum 2, rotated through stepped pulleys 19, and passes through slits 20 into the free space of the vessel 3; precipitant is supplied by a pump 12 and pipe 10 to conduits 4, 5, 6 terminating in slits 17. The mixture of precipitant, solvent and precipitate is discharged through pipes 8, 9 to a separator 14 <PICT:0368078/IV/1> <PICT:0368078/IV/2> furnished with a sieve 15 from which the precipitate is removed through an opening 25. The mixture of solvent and precipitant is partly discharged through a valved pipe 16 and is partly returned to the pump 12, fresh precipitant being introduced through a pipe 11. Fig. 2 shows a modified apparatus in which the precipitant is fed to the upper part 29 of a double perforated drum 26, and in which the vessel 27 also rotates. Examples are given of the precipitation of cellulose acetate dissolved in acetic acid by means of dilute acetic acid and water, and of cellulose dissolved in ammoniacal copper oxide by means of alkali. The Specification as open to inspection under Sect. 91 (3) (a) describes also the use of coacting jets or nozzles and refers also to nitrocellulose. This subject-matter does not appear in the Specification as accepted.