Process for separation of gases

A process for separating a gas mixture stream comprising:

• separating the gas mixture with an apparatus comprising:
• membrane separation stages;
• and
• a compressor, a vacuum pump, or both,
• wherein the membrane separation stages comprise a feed stream separation stage, a retentate separation stage, and a permeate separation stage:
• the feed stream separation stage is configured to separate the gas mixture stream into a first permeate stream and a first retentate stream,
• the retentate separation stage is configured to divide the first retentate stream into a second permeate stream and a second retentate stream,
• wherein the second permeate stream is supplied to the gas mixture stream, and the second retentate stream is withdrawn as a product, and the permeate separation stage is configured to divide the first permeate stream into a third retentate stream and a third permeate stream,
• wherein the third retentate stream is supplied to the gas mixture stream, and
• the third permeate stream is withdrawn as a product,
• the apparatus is configured not to subject the first permeate stream to any recompression,
• the feed stream separation stage comprises a gas separation membrane module having a mixed gas selectivity of at least 30,
• the apparatus is configured such that a gas volume recycled in the second permeate stream and in the third retentate stream totals less than 60% by volume of a crude gas stream,
• the apparatus is configured to increase a concentration of at least one permeate gas of the feed stream separation stage, after recycling of the second permeate stream and of the third retentate stream, in the feed stream, compared to a concentration in the crude gas stream, and
• wherein the third permeate stream comprises more than 95 vol % of a retentate gas of the feed stream separation stage in the gas mixture stream, and the second retentate system comprises more than 95 vol % of a permeate gas of the feed stream separation stage in the gas mixture stream.

A process for separating a gas mixture stream comprising methane and carbon dioxide, comprising:

• separating the gas mixture with an apparatus comprising:
• membrane separation stages;
• and,
• a compressor, a vacuum pump, or both,
• wherein the membrane separation stages comprise a feed stream separation stage, a retentate separation stage, and a permeate separation stage:
• the feed stream separation stage is configured to separate a feed stream comprising at least two components into a first permeate stream and a first retentate stream,
• the retentate separation stage is configured to divide the first retentate stream into a second permeate stream and a second retentate stream,
• wherein the second permeate stream is supplied to the feed stream, and the second retentate stream is withdrawn as a product, and
• the permeate separation stage is configured to divide the first permeate stream into a third retentate stream and a third permeate stream,
• wherein the third retentate stream is supplied to the feed stream, and the third permeate stream is withdrawn as a product,
• the apparatus is configured not to subject the first permeate stream to any recompression,
• the feed stream separation stage comprises a gas separation membrane module having a mixed gas selectivity of at least 30,
• the apparatus is configured such that a gas volume recycled in the second permeate stream and in the third retentate stream totals less than 60% by volume of a crude gas stream,
• the apparatus is configured to increase a concentration of at least one permeate gas of the feed stream separation stage, after recycling of the second permeate stream and of the third retentate stream, in the feed stream, compared to a concentration in the crude gas stream.