GB499332A - Process and plant for the recovery of commercial benzene (benzol), toluol and like products from coal gas, with the purification of coal gas from sulphur, gums and gum-forming organic compounds - Google Patents

Abstract

<PICT:0499332/III/1> In the separation of benzol with carbon disulphide and other impurities dissolved therein from foul wash-oil in a circuit comprising a heat exchanger 2, a steam heater 3, a stripping still 4 and a pump 10, and wherein a part of the regenerated wash-oil is continuously recycled through the heat exchanger and an oil cooler 7 back to a static coal-gas scrubber 8, the foul wash-oil is circulated in the closed circuit 2-3-4-10 at a greater rate than that at which the regenerated oil is circulated through the scrubber to inhibit deposition of sludgy impurities in the regenerating circuit. The primary washing circuit is connected to the latter through the heat exchanger and is completed by a benzolized-oil tank 9 and a pump 1. To increase the simultaneous removal of sulphur impurities and particularly organic substances with benzol from the gas, some of the recovered purified benzol is returned through a pipe-line 28 to one or more bays 81 of the scrubber either next to the gas inlet 12 or to a separate set of bays after the first three bays. The vapours from the stripping still enter a fractionating column 5 and fractions comprising benzolcarbon disulphide, purified benzol, residual naphtha, naphthalene and gum formers, are bled therefrom in the liquid phase. The benzol circulated through the washer is returned to the upper part of the column through a pipe 14. In an example, 500 gallons per hour of wash-oil are circulated through the regenerating circuit, 100 gallons per hour being branched off for circulation in the primary washing circuit.