| 摘要 |
The method and the device are used for the cryogenic decomposition of air in a distillation column system for separating nitrogen and oxygen, said system having a first high-pressure column (23), a low-pressure column (25, 26), and three condenser-evaporators, namely a high-pressure column head condenser (27), a low-pressure column bottom evaporator (28), and an auxiliary condenser (29; 228). A first feed air stream is cooled in a main heat exchanger (20, 21). The cooled first feed air stream (22) is introduced into the first high-pressure column (23) under a first pressure. Gaseous head nitrogen (44, 45) from the first high-pressure column (23) is condensed in the high-pressure column head condenser (27). At least one part (47) of the head nitrogen (46) which is condensed in the high-pressure column head condenser (27) is delivered to the first high-pressure column (23) as reflux liquid. A part of the bottom liquid (66) of the low-pressure column (25, 26) is evaporated in the low-pressure column bottom evaporator (28) in indirect heat exchange with a condensing heating fluid (58). A non-evaporated part (67) of the bottom liquid (66) of the low-pressure column (25, 26) is at least partially evaporated in the auxiliary condenser (29; 228). At least one part of the liquid (68) evaporated in the auxiliary condenser (29; 228) is obtained as a gaseous oxygen product (69). The distillation column system for separating nitrogen and oxygen additionally has a second high-pressure column (24). A second feed air stream (35) is cooled in the main heat exchanger (20, 21) and subsequently introduced into the second high-pressure column (24) under a second pressure which is higher than the first pressure. At least one part of the head gas (58) of the second high-pressure column (24) is used as heating fluid in the low-pressure column bottom evaporator (28). |
