method for separating a stream of natural gas into a fraction enriched with methane and a fraction enriched with c2 and higher hydrocarbons

摘要

method for purifying a feed gas stream comprising methane and hydrocarbons having at least two carbon atoms, comprising the following steps: step a): cooling the feed gas stream in a heat exchanger; step b): introducing the stream from step a) into a first phase separation vessel to produce a liquid stream and a gas stream; step c): separate the gas stream from step b) in a membrane permeation unit, thereby producing at least one permeate gas stream and a partially condensed waste stream; step d): feeding the waste stream from step c) into a second phase separation vessel in order to produce a liquid stream and a gas stream; step e): introducing at least a portion of the gas stream from step d) into a joule thomson expansion medium; step f): heat at least a portion of the expanded current from step e) by introducing it into the heat exchanger (2) implemented in step a), in countercurrent with the supply current.