CPC F25J 3/0295 (2013.01) [F25J 3/0233 (2013.01); F25J 3/0257 (2013.01); F25J 2200/20 (2013.01); F25J 2205/40 (2013.01); F25J 2205/80 (2013.01); F25J 2280/50 (2013.01)] | 20 Claims |
1. A process for the separation of nitrogen from a feed stream comprising methane and nitrogen, with a methane content between 4 and 12% mol, the process comprising the steps of:
a) separating the feed stream by means of a rubbery-type membrane to produce a permeate enriched in methane at a pressure greater than 2 bara and a non-permeate that is a nitrogen-enriched residue gas at a pressure greater than 2 bara;
b) processing of the high-pressure residue gas in a cryogenic separation unit to produce a methane rich liquid and a nitrogen-enriched gas; and
c) measuring the nitrogen concentration of the nitrogen-enriched gas,
wherein the pressure of the membrane permeate is controlled as a function of the nitrogen concentration in the nitrogen-enriched gas.
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