CRYOGENIC PROCESS FOR REMOVING NITROGEN FROM A DISCHARGE GAS

• Main Authors: CHANTANT, Nicolas, ANDRICH, Marine, TERRIEN, Paul
• Format: Patent
• Language: English
• Published: 10.06.2021
• Subjects: BLASTING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; HEATING; LIGHTING; LIQUEFACTION SOLIDIFICATION OF GASES; LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS; MANUFACTURE OR STORAGE OF ICE; MECHANICAL ENGINEERING; MIXTURES BY PRESSURE AND COLD TREATMENT; REFRIGERATION OR COOLING; WEAPONS

A process for producing biomethane by scrubbing a biogas feed stream including introducing a feed gas stream into a pretreatment unit wherein the gas stream is partially separated from a CO2 stream and an oxygen stream, thereby producing a CO2-depleted gas stream, which is compressed, thereby producing a pressurized CO2-depleted gas stream; separating the pressurized CO2-depleted gas stream by cryogenic separation by introducing the pressurized CO2-depleted gas stream into a distillation column thereby producing a nitrogen stream and a CH4-enriched stream, recovering a pressurized CH4-enriched stream by pumping the CH4-enriched stream; wherein the separation of the CO2 stream and the oxygen stream from the feed gas stream is performed by a unit comprising at least two separating membrane stages in order that the CO2-depleted gas stream comprises between 0.3 mol % and 2 mol % of CO2.