Process for hydrogen sulfide removal from gas mixtures containing h2s and co2

摘要

1,141,360. Recovery of sulphur. ALLIED CHEMICAL CORP. 25 Oct., 1966 [25 Oct., 1965; 15 Aug., 1966], No. 47901/66. Heading C1A. [Also in Divisions B1 and C5] H 2 S is removed from gas mixtures, especially from natural gas, by absorption at 1-105 kg/cm.SP2/SP, preferably up to 70 kg./cm.SP2/SP, in a liquid dialkyl ether of a polyalkylene glycol, which is subsequently regenerated by stripping at reduced pressure with an oxygen-containing gas such as air. The mixed gas stream of H 2 S and air is then preferably passed to a bauxite catalyst bed at 150-425‹ C. where the HS 2 is oxidized to sulphur, the effluent vapours from the bed being condensed to recover the sulphur in liquid or solid form. The solvent may be flashed at an intermediate pressure before stripping in order to remove absorbed gases other than H 2 S. The solvents generally contain 2-7 ethenoxy units, the dimethyl ether of tetraethylene glycol being preferred. In Fig. 2, natural gas having an H 2 S/CO 2 molar ratio of 0À1-10 enters sorber 2 by line 1 and sorbent by line 4, the pressure being maintained at 10À5-105 kg./cm.SP2/SP and the gas and liquid flow rates being so chosen that relatively little CO 2 is sorbed. Purified gas leaves at 5, charged solvent at a temperature of 0À5-44‹ C. passing by line 6 to be flashed to 1À05-35 kg./cm.SP2/SP in tank 7. The overhead, which comprises process gas and CO 2 , is returned by line 8 to sorber 2 while the solvent is heated in exchangers 10 and 11 on its way to stripping column 12 which is at 0À14-1À26 kg./cm.SP2/SP Air is fed in at the base and the effluent stream containing desorbed H 2 S passes to condenser 15, condensed solvent being returned to the stripper by line 16. Regenerated solvent is cooled in heat exchanger 10 and cooler 19 before being returned to the sorber. A process in which the stream of solvent is used first to remove and recover CO 2 from a gas stream from which the H 2 S has already been removed, and then, after flashing to remove the H 2 S from an incoming gas stream, is also described (see Fig. 3, not shown). In Fig. 1 (not shown), the effluent gas stream of H 2 S and air is passed by line (59) through heater (61), where more air enters by line (60), to bauxite catalyst bed (63), the effluent vapours being liquified in condenser (20) and molten sulphur recovered through line (21).