| 摘要 |
666,914. Separation of air. STEVENS, A. H. (Air Products, Inc.). June 14, 1949, No. 15788/4 Class 8 (ii) A method of deriming a heat exchanger 23B having a passage 25 in which there is alternate flow of a continuous stream of a warm gas containing congealable vapours, e.g. air containing carbon dioxide, and a continuous stream of cold dry gas in the opposite direction, e.g. nitrogen from an air fractionating column 69 comprises passing a second stream of said cold gas at a higher pressure than the first continuously through a path 26 in the exchanger in heat exchange relationship with the passage 25, expanding this second stream in an engine 97 to a lower pressure and adding it to the first stream at a duct 101. In operation and with switching valves 29A, 29B in the positions shown air at 100 p.s.i. pressure to be fractionated in the column 69 and having traversed a filter 11, turbo compressors 15, 16 and coolers 17, 18 is divided at a junction 20 so that 80 per cent traverses a duct 21, valve 29A, a path 25 of an interchanger 23A and the shell of interchanger 23B, ducts 36, 38, 42, a flap valve 44 and an air feed line 48 to the base of high pressure stage 70. The air flowing through the interchanger 23A is cooled by indirect contact with the said first mentioned stream of counterflowing nitrogen which is supplied from the top of the low pressure stage 71 through ducts 83, 49, a flap valve 47, ducts 46, 40 to the shell of the interchanger 23A which is vented through a duct 33, the valve 29B and a valved duct 28. Additional cooling is effected by a portion of the said second nitrogen stream which latter is supplied from the top 85 of the high pressure stage 70 through-ducts 89, 90, 91 and the path 26. The remainder of this second nitrogen stream is passed through the path 26 of the interchanger 23B being derimed and is thereafter vented through the valve 29B and the duct 28. The 20 per cent portion of the incoming air traverses a manifold 22, a switching valve 51A, the shell of an interchanger 50A being derimed by returning oxygen and the tubes of an interchanger 50B, after which the air streams are combined in a duct 56, and after passing a flap valve 58 this air is fed into the air feed line 48. The counterflowing oxygen in interchangers 50A, 50B is supplied from the base of the low pressure section 71 through a line 60, a flap valve 61 and lines 63, 64 and is thereafter vented through a switching valve 51B and a line 68. In a modification cold accumulators are substituted for the exchangers 23A, 23B, 50A, 50B.
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