GB683322A - Improvements in process for recovering substances from a gas containing vapours of said substances - Google Patents

Abstract

683,322. Gas scrubbing processes. SOC. DES ETABLISSEMENTSBARBET. Aug. 1, 1950 [Aug.2, 1949], No. 19213/50. Class 55 (ii). To recover benzene coal gas &c. is passed through a turbulent body of an aqueous solution non-freezing under the working conditions and through a turbulent body of a liquid aromatic hydrocarbon having a higher boiling point than benzene, both treatments being effected below 0‹C. The aqueous solution may comprise a mineral salt such as calcium chloride or a nitrate or a solution of a glycol or glycol ether. Gas to be freed from benzol is cooled to about 0‹C. in a heat chamber A in indirect contact with treated gas, and then passes to a vessel C<SP>1</SP> in which a rotary member submerged in a dehydrating solution e.g. of concentrated calcium chloride at -20‹C. produces an emulsifying effect and a condensation of toluene, xylene, and possibly benzene. Effluent gas is similarly treated in a second vessel C<SP>2</SP> with a solvent, e.g. crude benzol from which the benzene fraction has been removed, also cooled to -20‹C. The gas then passes through a packed tower M supplied with regenerated solvent to heat exchanger A. The dehydrating solution from vessel C' is regenerated by indirect heat exchange with regenerated solution, and concentration by evaporation in a vessel E after decanting in a vessel D a top layer having a high content of benzene homologues. The solvent from vessel C<SP>2</SP> when containing 25-30 per cent of benzene is warmed in a heat exchange H and distilled in a column I, the debenzolized liquid being pumped to a tank L and returned to the emulsifier through heat exchanger H and tower M.