| 摘要 |
The method and apparatus serve to obtain a compressed nitrogen product by low-temperature fractionation of air in a distillation column system having a high-pressure column (10) and a low-pressure column (11) and a main condenser (12) and a low-pressure column top condenser (13), both of which take the form of condenser-evaporators. Bottoms liquid (28, 29) from the low-pressure column is introduced into the evaporation space of the low-pressure column top condenser (13). Gas formed therein is decompressed to perform work as residual gas (30, 31) in a first residual gas turbine (33). The mechanical energy generated is used to drive a cold compressor (36). A first compressed nitrogen product stream (19) is drawn off in gaseous form from the top of the high-pressure column (10) and warmed in the main heat exchanger (8). A further nitrogen stream (37) is drawn off in gaseous form from the top of the low-pressure column (11), compressed in the cold compressor (36) to a pressure which is at least equal to the pressure of the first compressed nitrogen product stream (19) when it is drawn off from the high-pressure column (10), and is then warmed as the second compressed nitrogen product stream (38) in the main heat exchanger (8). The cold compressor (36) overcomes a pressure differential which is at least equal to two thirds of the pressure differential between the top of the high-pressure column (10) and the top of the low-pressure column (11). |
