| 摘要 |
Air is compressed in a compressor 2 and has water vapour and carbon dioxide removed therefrom in an apparatus 4. A portion of the resulting purified air is then cooled by passage through a main heat exchanger 6 to a temperature suitable for its separation by rectification. The air is then introduced into the higher pressure stage 12 of a double rectification column 10 (which also has a lower pressure stage 14). Liquid oxygen is withdrawn from the lower pressure stage 14 by a pump 36 and is vaporised by passage through the heat exchanger 6 countercurrently to the aforementioned air to form a high pressure gaseous oxygen product. A second portion of the purified air is further compressed in compressors 38 and 40 and is then passed through the heat exchanger 6 countercurrently to the oxygen product, thereby helping to warm such product. A part of the first portion of air is withdrawn from an intermediate region of the heat exchanger 6, is expanded in a turbine 50 and is introduced into the lower pressure rectification stage 14. A part of the second portion of the air is taken from intermediate the compressors 38 and 40 and is passed through the heat exchanger 6, being withdrawn therefrom at an intermediate location thereof. This air stream is then expanded in an expansion turbine 48 and is passed into the higher pressure rectification stage 12 of the column 10. <IMAGE> |
