Single expander and a cold compressor process to produce oxygen

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) at the bottom of the distillation column (198) producing an oxygen product (172) is provided by condensing a stream whose nitrogen concentration is at least equal to that in the feed air stream (100), is reduced by: (a) generating work energy which is in excess of the overall refrigeration demand of the distillation column system by (1) work expanding (139) a first process stream (154 Fig 2) 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) by latent heat exchange (194 Fig 2; 394 Fig 3) 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 (198) having an oxygen concentration at least equal to the concentration of oxygen in the feed air (100); (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 (130) 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); and/or (3) work expanding (503 Fig 5; 603 Fig 6)a fraction (504 Fig 5; 604 Fig 6) of the feed air (100); and (b) 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) a process stream (114; 482 Fig 4; 551 Fig 5) at a temperature lower than the ambient temperature.