| 摘要 |
This invention relates to a cryogenic process for the separation of air utilizing an integrated multi-column distillation system wherein an ultra high purity nitrogen product is generated. In the cryogenic distillation separation of air, air is initially compressed, pretreated and cooled for separation into its components. Ultra high purity, e.g., nitrogen having less than 0.1 ppm of light impurities is generated with enhanced nitrogen product recovery by withdrawing liquid nitrogen from a first column at an intermediate point and charging that fraction as feed to the second column, withdrawing a nitrogen stream which is rich in volatile contaminants from the top of the first column, partially condensing that nitrogen stream against crude liquid oxygen, and removing the uncondensed portion which has been concentrated in volatile contaminants as a purge stream. An ultra high purity nitrogen product is obtained from a second column.
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