| 摘要 |
The invention provides a process and apparatus for the separation of nitrogen from a gaseous feed 1 comprising a mixture of hydrocarbons and nitrogen gas. The process includes cooling and at least partially condensing the gaseous feed in a first heat exchanger 2, and feeding the cooled mixture to a first fractionation column 8 to produce a nitrogen rich overhead vapour fraction 19 and a hydrocarbon rich liquid fraction 9. The liquid fraction is subjected to a second fractionation process, which includes reboil in a second fractionation column 15 at a lower pressure than the first fractionation column. The overhead vapour 19 from the high pressure column is partially condensed, and separated to provide a further liquid stream 22 which provides reflux to the first fractionation column, and a separated vapour stream 23 which is condensed to provide reflux to the second fractionation column. The hydrocarbon rich liquid fraction 9 is sub-cooled in a second heat exchanger 10 and divided into at least two streams. The first stream being expanded and fed to the second fractionation column, and a second stream being expanded and in heat exchange with the separated vapour stream 23, and which provides reheat before the second stream is fed to the second fractionation column. A hydrocarbon product stream 31 low in nitrogen, and a nitrogen rich stream 28, can then both be removed from the second fractionation column. |
