PROCESS FOR THE REMOVAL OF SULPHUR COMPOUNDS FROM GASES OR GAS MIXTURES

摘要

1367941 Removing sulphur compounds from gases SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ NV 18 Oct 1971 [19 Oct 1970] 48251/71 Heading C1A [Also in Division B1] In removing sulphur compounds from gaseous mixtures containing them by passing the mixture under oxidizing conditions into contact with a metal and/or metal compound containing acceptor for sulphur oxides at a temperature from 325-475‹ C., and subsequently regenerating the loaded acceptor by a reduction step in the same temp. range, the gas mixture is free from solid matter, one or more fixed beds of acceptor are used, and one bed, or part of a bed is used for absorption. A second bed or part of a bed is contacted with a reducing gas, and a third bed or part of a bed is contacted with an oxidizing gas, and the gas stream being treated is transferred from passing to the bed or part thereof which has become loaded with sulphur oxides to that bed or part of a bed which has been oxidized, the released loaded bed being now subjected to the reduction step, and the released reduced bed or part of a bed being now subjected to an oxidizing step. If desired, before being oxidized the reduced bed may be contacted with an inert gas. Similarly a treatment with an inert gas may be inserted between the loading and reducing phases. The inert gas which is inert to the absorbent material under the conditions used, may be N2, CO2 or steam. The reducing gas and the oxidizing gas may be passed through the bed or part thereof in a direction counter to the direction in which the gases being treated have been passed. Preferably at least three acceptor beds are utilized, but most preferably four beds are used arranged in two parallel pairs, and the time taken for the absorption step is substantially equal to the time taken by the reducing phase, the oxidizing phase and the inert gas treatment. In a preferred embodiment shown in Figs. 1A and 2 the acceptor is in the form of a single cylindrical bed divided into non-communicating sectors by partitions 2a, 2b, 2c. The gas inlet line 5 is connected to the chamber by conical extension 6 and rotatable disc 7 provided with a single opening so that any of the three compartments may be placed on line with the gas inlet. The outlet of the apparatus is similarly equipped, the two discs being synchronized. The hole in discs 7 and 8 may be a slot 20 extending over 120 degrees of arc or simply a circular hole (Fig. 1B, not shown). Oxidizing, reducing and optionally inert gas are supplied via lines 13, 14 and 15 in desired sequence and exit through a similar array of outlets. The inlet and outlet functions of the various gas lines may be interchanged. In a second embodiment as shown in Figs. 3, 4, and 6, a cylindrical housing 29 has a central space 37 having a wall 31, and the annulus between housing and wall is divided by impermeable walls 86 into radial compartments 85. Extending down from the upper surface 31 of the housing walls 48, 49, 50 divide the upper area into a series of annular zones, and disc 41 rotates in gas tight relationship beneath the walls on radial trusses 60 and annular trusses 57, 58a, 58b, 58c which are positioned to correspond with said annular zones-viz. 44, 45, 46, and 47. These zones are fitted with inlets/outlets 52, 53, 54, 56 to admit/ exhaust gas to/from the bed and annular slots 42, 43, 81, 84, in disc 41 are positioned so as to direct gas to or from the appropriate zone, being of length to control the time taken for such action when the disc is continuously rotated during use. The base of the vessel is similarly equipped with synchronously rotating disc 38.