| 摘要 |
Nitrogen is produced by a cryogenic process in which air is distilled in a distillation system comprising a high pressure (HP) column (30), a low pressure (LP) column (28) and an extra high pressure (EHP) column (72). Cooled, compressed air (70) is fed to the EHP column (72) at higher pressure than to the HP column (30) and rectified to provide an extra high pressure nitrogen overhead (74) which is condensed in a reboiler/condenser (80) to provide reflux (82) for the EHP column (72). Said reboiler/condenser (80) is located in the stripping section of the LP{ column (28) below a reboiler/condenser (44) providing reflux (52) for the HP column (30) from the high pressure nitrogen overhead stream (32,40). In one embodiment a portion of the cooled, compressed air feed to the HP column (30) is condensed in a reboiler/condenser located in the LP column (28) below said reboiler/condensers (44,80) to provide impure reflux to the HP column (30) and/or the LP column (28). <IMAGE> |
