Patent ID: 7799964

Claim:
A process for the recovery of a C 3 + rich LPG stream and a high purity hydrogen stream from a hydrocarbon-containing feedstream comprised of hydrogen and C 1 , C 2 and C 3 + hydrocarbons, comprising: (a) feeding the hydrocarbon feedstream into a first membrane separation unit wherein the hydrocarbon-containing feedstream is contacted with a first side of at least one first rubbery polymer membrane, (b) retrieving a first retentate product stream which has a higher hydrogen mol% than the hydrocarbon-containing feedstream from the first side of the first rubbery polymer membrane and retrieving a first permeate product stream which has a higher C 3 + mol % than the hydrocarbon-containing feedstream from a second side of the first rubbery polymer membrane, (c) feeding the first permeate product stream to a compressor wherein the first permeate product stream is raised in pressure, (d) feeding the higher pressure first permeate product stream to a knockout drum, (e) retrieving a liquid C 3 + rich LPG product stream from the knockout drum, wherein the C 3 + rich LPG product stream has a higher C 3 + mol % than the first permeate product stream, (f) retrieving a vapor C 2 − rich stream from the knockout drum, wherein the C 2 − rich stream has a higher C 2 − mol % than the first permeate product stream, (g) feeding C 2 − rich stream into a second membrane separation unit wherein the C 2 − rich is contacted with a first side of at least one second rubbery polymer membrane, (h) retrieving a second retentate product stream which has a higher C 2 − mol % than the C 2 − rich stream from the first side of the second rubbery polymer membrane and retrieving a second permeate product stream which has a higher C 3 + mol % than the C 2 − rich stream from a second side of the second rubbery polymer membrane, and (i) mixing at least a portion of the second permeate product stream with the first permeate product stream at a point upstream of the compressor, wherein: the first retentate product stream has a hydrogen purity of at least 70 mol %; the wt % of the hydrogen component of the first retentate product stream is at least 40 wt % of the hydrogen component in the hydrocarbon-containing feedstream; and the C 3 + rich LPG product stream has a C 3 + purity of at least 70 mol %; and the wt % of the C 3 + component in the C 3 + rich product stream is at least 80 wt % of the C 3 + component in the hydrocarbon-containing feedstream.