| 摘要 |
824,159. Cold separation of air. UNION CARBIDE CORPORATION. March 7, 1958 [March 22, 1957], No. 7460/58. Class 8(2). In a rectification process wherein air having a compressor 10 at less than 150 p.s.i. is cooled, and freed of readily condensible impurities in heat exchanger with returning nitrogen e.g. in alternating exchangers 12 and in a scrubber 20, part of the so cleaned air in a duct 22 is warmed in heat exchangers 23, 28 recompressed to above 2000 p.s.i. in a compressor 31 and is then divided into a first portion which is cooled in passage 25 of exchanger 23 and expanded at a valve 34 to less than 150 p.s.i. after which it is joined by the remaining high pressure air after being cooled by an external refrigerant e.g. ammonia in an exchanger 35 and expanded with external work at 40 to below 150 p.s.i. ; the so combined air streams then passing to a conventional double column 51, 53. Liquid and gaseous oxygen products are drawn from the low pressure column 51 through valved ducts 65, 87 respectively and crude liquid nitrogen is drawn from the high pressure column 53 through a valved duct 89. To provide the necessary flow unbalance for regenerators 12 a minor portion of the low pressure air by-passes the regenerators and is further compressed at 69 to 2000 p.s.i. cooled in exchanger passage 29 and in an ammonia refrigerator 73 and added to the cold high pressure air leaving the exchanger 35. In a modification the scrubber is replaced by an adsorption trap and the whole of the incoming air is cooled in an indirect countercurrent heat exchanger having a non- reversing passage traversed by a portion of the cold air leaving the absorption trap. |
