| 摘要 |
The method and the device serve to produce oxygen by the low-temperature separation of air at variable energy consumption. A distillation column system comprises a high-pressure column (34), a low-pressure column (35) and a main condenser (36), a secondary condenser (26) and a supplementary condenser (37). Gaseous nitrogen (41, 42) from the high-pressure column (34) is liquefied in the main condenser (36) in indirect heat exchange with an intermediate liquid (43) from the low-pressure column (35). A first liquid oxygen stream (70) from the bottom of the low-pressure column (35) is evaporated in the secondary condenser (26) in indirect heat exchange with feed air (25b) to obtain a gaseous oxygen product (72). The supplementary condenser serves as a bottom heating device for the low-pressure column (35) and is heated by means of a first nitrogen stream (44) from the distillation column system, which nitrogen stream was compressed previously in a cold compressor (45). In a second operating mode of lower energy consumption, less feed air (1) is compressed in the main air compressor (3) of the installation to a lower pressure compared to a first operating mode of higher energy consumption, less liquid oxygen (70) from the low-pressure column (35) is passed into the secondary condenser (26) and more nitrogen is compressed in the cold compressor (45). Furthermore, in the second operating mode, a second liquid oxygen stream (73) is additionally passed into the secondary condenser (26). |
