| 摘要 |
An air stream is compressed in compressor 2 and purified in unit 4. One subsidiary stream of this air is cooled in heat exchanger 10 to a temperature suitable for its separation by rectification. This subsidiary air stream is separated in a double rectification column 24 comprising a higher pressure stage 18 and a lower pressure stage 20. A secondary subsidiary air stream is further compressed in compressors 42, 44, 46 and 48. It is cooled in heat exchanger 10 to a first temperature intermediate ambient temperature and the operating temperature of the column 24. The second subsidiary stream is expanded in an expansion turbine 50 and leaves that turbine 50 at a second intermediate temperature lower than the first intermediate temperature. The expanded second subsidiary stream enters a second expansion turbine 52 at such second intermediate temperature and is expanded therein. The expansion turbine 52 feeds the second subsidiary air stream to the lower pressure stage 20 of the double column 24. Oxygen and nitrogen products are withdrawn from the lower pressure stage partly in liquid state. <IMAGE> |
