| 摘要 |
PURPOSE: To crack air by rectification improved in cost effectiveness by heating at least a portion of nitrogen expanded by executing work, compressing the nitrogen again and utilizing at least a portion of the work recovered at the time of the previous expansion for the compression described above at this time. CONSTITUTION: The compressed and prepurified air is introduced through a conduit 1 into a main heat exchanger 17 where the air is cooled and is precracked by the high-pressure stage 3 of a two-stage rectification column 23 to the portion 5 enriched in the nitrogen and the liquid 6 enriched in the oxygen. These components 5 and 6 are at least partly introduced into the intermediate pressure stage 4 of the rectification column 2 and are cracked to the oxygen and the nitrogen. At this time, the at least one gaseous nitrogen component is taken out by a conduit 16 and is heated in the main heat exchanger 17. The work is executed by at least a portion by the conduit 30 and the nitrogen is expanded by an expansion turbine 31. The nitrogen expanded by executing the work is introduced through a conduit 32 to the main heat exchanger 17 where the nitrogen is heated. The heated nitrogen is again compressed by compressing machines 33 and 36 and at this time, part of the recovered work at the time of the expansion described above is utilized for the compression described above. |
