| 摘要 |
Air is compressed in compressors 2, 8, 12 and 14. A first flow of the thus compressed air flows through a main heat exchanger 22 from its warm end 24 to its cold end 26 and is liquefied by passage through a valve 28. Two second stream of compressed air are taken. One is expanded in expansion turbine 44, the other in expansion turbine 38. The streams leaving the valve 28 and expansion turbine 44 are separated in a double rectification column 34. Liquid oxygen product is extracted from outlet 60. Part is taken as liquid product and the rest is vaporised by passage through the heat exchanger 22 from its cold end 26 to its warm end 24 and taken as gaseous oxygen product. The ratio of liquid oxygen product to total oxygen product is capable of being varied. Accordingly a chosen but variable proportion of the two second air streams flows to the double rectification column 34 and a chosen but variable proportion of the two second air streams is returned to the arrangement of compressors 2, 8, 12 and 14 at a region intermediate compressors 2 and 8. <IMAGE> |
