| 摘要 |
The power consumption required by the cryogenic distillation of air in a distillation column system comprising at least one distillation column (198) wherein the boil-up (193; 593 Fig 5; 893 Fig 8) at the bottom of the distillation column (198) producing a oxygen product (172) is provided by condensing a stream (152; 552 Fig 5) whose nitrogen concentration is at least equal to that in the feed air stream (100), is reduced by (a) generating work energy which is at least ten percent of the overall refrigeration demand of the distillation column system by (1) work expanding (139) a first process stream (154 Fig 2; 538 Fig 5; 738 Fig 7; 838 Fig 8) with nitrogen content at least equal to that in the feed air (100) and then condensing at least a portion of the expanded stream (240 Fig 2; 540 Fig 5; 740 Fig 7) by latent heat exchange (194 Fig 2; 394 Fig 3; 594 Fig 5; 794 Fig 7; 894 Fig 8) with (i) a liquid at an intermediate height in the distillation column (198) producing oxygen product and/or (ii) one of the liquid feeds (136) to this distillation column having an oxygen concentration at least equal to the concentration of oxygen in the feed air (100); and/or (2) condensing at least a second process stream (154) with nitrogen content at least equal to that in the feed air (100) by latent heat exchange (194) with at least a portion (136) of a liquid stream which has oxygen concentration at least equal to the concentration of oxygen in the feed air (100) and which is also at a pressure greater than the pressure of the distillation column (198) producing oxygen product, and after vaporization of at least a portion of said liquid stream into a vapor fraction (137) due to latent heat exchange (194), work expanding (139) at least a portion of the resulting vapor stream (137); (b) work expanding (103; 603 Fig 6; 703 Fig 7) a third process stream (104; 604 Fig 6; 704 Fig 7; 904 Fig 9) to produce additional work energy such that the total work generated along with step (a) exceeds the total refrigeration demand of the cryogenic distillation and, if the third process stream (704 Fig 7) is the same as the first process stream (738 Fig 7) in step (a)(1), at least a portion of said third process stream (704) after work expansion (703) is not condensed against either of the two liquid streams described in step (a)(1); and (c) using the work which is generated in excess of the refrigeration need of the distillation column system to cold compress (115; 484 Fig 4; 515 Fig 5; 784 Fig 7) a process stream (114; 482 Fig 4; 551 Fig 5; 782 Fig 7; 851 Fig 8) at a temperature lower than the ambient temperature. <IMAGE> |
