Process and apparatus to recover helium

A non-cryogenic process for separately recovering high purity helium and high purity methane from a feed stream comprising methane, nitrogen and helium, the process comprising:

• a) introducing the feed stream into a high pressure adsorption column or a low pressure adsorption column of a first dual reflux pressure swing adsorption (DRPSA) unit;
• b) separating the feed stream by adsorption into a first reflux product and a first heavy product and circulating the first reflux product and the first heavy product thereof in said first DRPSA unit to produce an intermediate helium-enriched stream and a high purity methane stream;
• c) withdrawing the intermediate helium-enriched stream from first DRPSA unit and introducing the intermediate helium-enriched stream to a high pressure adsorption column or a low pressure adsorption column of a second DRPSA unit;
• d) separating the intermediate helium-enriched stream by adsorption into a second reflux product and a second heavy product and circulating the second reflux product and the second heavy product thereof in said second DRPSA unit to produce a high purity helium stream and a waste stream containing helium;
• and
• e) withdrawing the waste stream containing helium from the second DRPSA unit and recycling thereof to one of a plurality of locations in the first DRPSA unit to increase helium recovery in the high purity helium stream produced in the second DRPSA unit.

An apparatus to recover high purity helium from a feed stream comprising low helium content, the apparatus comprising:

• a first dual reflux pressure swing adsorption (DRPSA) unit comprising a high pressure adsorption column and a low pressure adsorption column configured in fluid communication with the high pressure adsorption column, the first DRPSA unit being arranged to receive and separate the feed stream into a first reflux product and a first heavy product and circulate the first reflux product and the first heavy product between the high and low pressure adsorption columns to produce an intermediate helium-enriched stream;
• a second DRPSA unit comprising a high pressure adsorption column and a low pressure adsorption column configured in fluid communication with the high pressure adsorption column, the second DRPSA unit being arranged to receive and separate the intermediate helium-enriched stream into a second reflux product and a second heavy product and circulate the second reflux product and the second heavy product between the high and low pressure adsorption columns to produce a high purity helium stream and a waste stream containing helium, wherein the first DRPSA is in fluid communication with the second DRPSA via a feedline for said helium-enriched stream, and
• a recycle feedline arranged to withdraw said waste stream from the second DRPSA unit and recycle said waste stream to one of a plurality of locations in the first DRPSA unit to increase helium recovery in the high purity helium stream produced in the second DRPSA unit.

An apparatus to recover helium and methane from a feed stream comprising methane, nitrogen and helium, the apparatus comprising:

• a first dual reflux pressure swing adsorption (DRPSA) unit comprising a high pressure adsorption column and a low pressure adsorption column configured in fluid communication with the high pressure adsorption column, the first DRPSA unit being arranged to receive and separate the feed stream into a first reflux product and a first heavy product and circulate the first reflux product and the first heavy product between the high and low pressure adsorption columns to produce an intermediate helium-enriched stream and a high purity methane stream;
• a second DRPSA unit comprising a high pressure adsorption column and a low pressure adsorption column configured in fluid communication with the high pressure adsorption column, the second DRPSA unit being arranged to receive and separate the intermediate helium-enriched stream into a second reflux product and a second heavy product and circulate the second reflux product and the second heavy product between the high and low pressure adsorption columns to produce a high purity helium stream and a waste stream containing helium, wherein the first DRPSA is in fluid communication with the second DRPSA via a feedline for said helium-enriched stream, and
• a recycle feedline arranged to withdraw said waste stream from the second DRPSA unit and recycle said waste stream to one of a plurality of locations in the first DRPSA unit to increase helium recovery in the high purity helium stream produced in the second DRPSA unit.