| 摘要 |
An impure gas (or gas mixture) is purified by adsorbing the impurities on a bed of adsorbent and (a) regenerating the bed by means of a gas of the same composition as, but hotter than, said impure gas, (b) cooling a portion of the bed by means of a cold gas (or gas mixture) free from adsorbable impurities and (c) cooling the remainder of the bed by passing through said portion and the remainder of the bed, a stream of said impure gas. The bed is then in a suitable condition for a further adsorption step. The process is described in relation to the purification of air from CO2, moisture and/or hydrocarbons for subsequent low-temperature separation into oxygen and nitrogen and the purification of hydrogen, helium and hydrocarbon mixtures is also mentioned. Specified adsorbents are silica gel, activated alumina and synthetic zeolites, e.g. a 5 molecular sieve. Four embodiments are described. (1) (Figs. 1a, 1b, 1c, not shown). In phase a, first adsorbent bed 3 is used to purify air whilst adsorbent 9 is regenerated by passing ambient air at 100 DEG C. therethrough. In phase b initially nitrogen separated from the purified air is passed through adsorbent 9 to effect cooling of part 18, of the adsorbent, the remainder of the cooling being effected by the air to be purified. In phase c adsorbent 9 is used for adsorption while adsorbent 3 is regenerated. (2) In place of the partial nitrogen cooling of embodiment (1), cooled ambient air is cirulated in a closed path, Fig. 2b (not shown), whereby part of the adsorbent, 20, is cooled, while a part 19 adsorbs impurity in the circulating air. (3) In place of the partial nitrogen cooling of embodiment (1), purified air from the first adsorbent bed 3, Fig. 3b (not shown), is passed into the hot adsorbent to effect the cooling of part thereof before directly passing the ambient air thereinto for further cooling and adsorption, Fig. 3c (not shown). (4) Three beds are cylically employed, Fig. 4a (not shown), purified air from first bed (3) in adsorption phase being used to cool adsorbent in the second bed (9) which has been heated by hot ambient air, in the preceding phase. Bed 24 is shown in the heating and regenerating phase. |
