Patent GB-525501-A (GB)
Title: Improvements in or relating to the extraction of wax from peat by means of solvents
IPC: C10G73/00
Filed: 1939-02-22
Abstract: 525,501. Extracting peat wax. REILLY, J., KELLY, D. F., and DUFFY, J. Feb. 22, 1939, No. 5926. [Class 91] In the extraction of wax from peat by a mixture of solvents, the wet solvents distilled from the extract are dehydrated by passing as vapour or as liquid through a tower or the like containing a hygroscopic substance and are re-used. The solvents may be such as to form azeotropes, or as do not form azeotropes but may have an approximately constant B.P. except at the beginning and end, e.g. as described in Specification 486,383; petroleum spirit mixed with an equal vol. of methyl, ethyl, propyl, or isopropyl alcohol is suitable. Hygroscopic substances specified are ferric, calcium, cobalt, and nickel chlorides, sodium acetate, ammonium propionate, acetamide, dimethylamine or diethylamine hydrochloride, or piperazine; they may be used singly or mixed, and dry or as a solution in the solvent mixture or even in water. Using the apparatus shown, peat in an extractor A is digested at 50‹C. for 30 minutes with an azeotropic mixture of benzene and ethylalcohol fed from a tank B by a pipe 1; the solution of wax is passed through a filter and a pipe 2 to a still C, from which wet solvent vapours rise through a pipe 3 to a condenser D ; the condensate flows through a pipe 4 to a tank E, from which it is returned to the extractor by a pipe 5 if not too wet, or is taken by a pipe 6 to a centrifuge F from which the layer of low water content is discharged through a pipe 7 to tank E or through a pipe 8 to tank B, while the layer of high water content is taken via a pipe 9, a tank G, and a preheater H to a fractionating column J. Wet vapours of residual solvent from the steaming of the heated peat in extractor A and of the wax in still C are also passed to the column J by the pipes 10, 11 respectively. The solvent vapours from the fractionator J are led by pipe 12, condenser D, and pipe 4 to the tank E, or by pipes 12, 13, a condenser K, and a pipe 14 to tank B if not too wet. When the wet solvent in tank E must be dehydrated it is passed by pipe 17 to a still N ; the vapours therefrom are taken by a pipe 18 to a tower M, and ascend against a solution of hygroscopic substance led in by a pipe 16 and made in a mixer L with drier solvent from pipe 15 and tank B ; the dried solvent ascends through a pipe 19 to condenser K and is returned to dry solvent tank B by pipe 14. Alternatively the wet solvent vapours from extract still C are led by a pipe 20 direct to the tower M. The wet solution of dehydrating agent is conducted by a pipe 21, a pump P, and a pipe 22 to a drying drum O, the vapours being passed by a pipe 23 to condenser D ; the condensate is taken direct to preheater H and fractionator J. The recovered dehydrating agent in drum O is returned to mixer L by a pipe 24. In a modification the wet solution of dehydrating agent is discharged from tower M to a still R, and the vapours passed to a fractionating column S ; the solvent fractions are then led to condenser K and tank B or to condenser D and tank E; the aqueous solution of dehydrating agent is passed from the bottom of column S to drying drum O by a pump T. The drying in drum O may be effected under reduced pressure. The pressure in the whole plant may be normal, reduced, or raised, and may be different at different parts.