| 摘要 |
The invention relates to a process and apparatus for producing nitrogen by low-temperature fractionation of air in a rectification system which has a high-pressure column (4) and a low-pressure column (5). Feed air (1, 3) is introduced into the high-pressure column (4). An oxygen-containing liquid fraction (11) is removed from the high-pressure column (4) and fed into the low-pressure column (5). Gaseous nitrogen (18) is extracted from the low-pressure column (5) above a mass transfer section (25), which has at least one theoretical or practical plate, and is at least partially condensed in a top condenser (17) by indirect heat exchange with a refrigerant (13). High-purity nitrogen is removed from the low-pressure column below the mass transfer section (25), and is obtained as a nitrogen product (26, 27, 30). The process and apparatus have a refrigeration-supply system, in which a refrigeration fluid (31) flows. At least part of the refrigeration fluid from the refrigeration-supply system is introduced into the low-pressure column (5) above the mass transfer section (25).
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