| 摘要 |
The invention provides a process and apparatus for the separation of nitrogen from a gaseous feed comprising a mixture of hydrocarbons and nitrogen gas, the process comprising the steps of: (i) cooling and at least partially condensing the gaseous feed; (ii) feeding the cooled and at least partially condensed feed from step (i) to a first fractionation to produce an overhead vapour stream having an enriched nitrogen content and a condensed product having a reduced nitrogen content which is subjected to a second fractionation, which comprises reboil, at a lower pressure than the first fractionation; (iii) partially condensing the overhead vapour stream, and separating to provide a liquid stream, which is used to provide reflux to the first fractionation, and a separated vapour stream, which is condensed to provide reflux to the second fractionation; and (iv) sub-cooling the condensed product of the first fractionation and dividing the resulting sub-cooled product into at least two streams: a first stream being expanded and fed to the second fractionation, and a second stream being expanded and reheated in heat exchange with the separated vapour stream from step (ii) before being fed to the second fractionation; (v) removing a hydrocarbon product stream low in nitrogen from the second fractionation; and (vi) removing a nitrogen rich stream from the second fractionation. |
