Adsorption separation process

摘要

1,067,177. Separating gases. UNION CARBIDE CORPORATION. Sept. 2, 1963 [Sept. 4, 1962]. No. 34515/63. Addition to 989,073. Heading B1L. A fluid feed stream is purified by contacting it with one end of an absorbent bed at a first higher pressure, continuing the adsorption process until the impurity adsorption front has reach a predetermined point within the bed, discontinuing the introduction of the feed, removing fluid trapped in voids in the bed and moving the impurity front further forward by concurrently depressurising the bed and then desorbing the absorbent, the absorbent bed comprising activated AL 2 O 3 alone or together with SiO 2 gel, activated C or a zeolitic molecular seive. The process may be used to treat gaseous mixtures containing H 2 , O 2 . N 2 . Ne, Ne, Ar, Kr, NH 3 , H 2 O, CO 2 , CO, SO 2 , H 2 S, CH 4 , C 2 H 8 , C 3 H 8 , C 4 H 10 . C 2 H 4 . C 3 H 6 , C 4 H 8 , C 2 H 2 and higher saturated and unsaturated hydrocarbons. A feed stream at 100‹F and 750 psig passes via line 10 and valve 12 to adsorber A containing first a layer of silica gel and then a layer of zeolitic molecular seive. The partially impurity depleted feed stream is fed via lines 14 and valves 16 and 18 to adsorber D containing a plurality of adsorbents including activated alumina, weak adsorbate impurities being adsorbed in adsorber D until the adsorption front reaches a predetermined point within the adsorber D, but the adsorption front in adsorber A is not stopped at a predetermined point. The product effluent from D passes through lines 20 and 34 via valve 22 a portion being diverted along line 21 to repressurise bed F whilst another portion cools bed C which has previously been heated and desorbed. The warm effluent from C is further warmed at 60 and passed via line 28 to bed B which has previously been used for adsorption, and is thereby desorbed and the desorbate vented through cooler 62. Bed D is depressurised cocurrently with valves 18 and 22 closed and valve 38 open, the void gas being passed to adsorber F. Adsorber E which has just completed a cocurrent depressurisation step, is desorbed by opening valve 42, thus allowing the weak adsorbate constituents to leave through conduit 52. In another embodiment (Figs. 1 and 2, not shown) four adsorbers are used in a continuous process wherein at any time, one bed is being used for adsorption whilst the others undergo the steps of co-current depressurisation, desorption and repressurisation respectively.