# US 12,109,528 B2 · Plant for the membrane permeation treatment of a biogas stream with a membrane separation unit containing two modules > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,109,528 B2 - Document ID: US12109528B2 - Status: Granted - Kind: B2 - Application number: 17/700,966 - Filed: 2022-03-22 - Published: 2022-09-22 - Granted: 2024-10-08 - Earliest claimed: 2021-03-22 - Assignees: L'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude - Applicants: L'Air Liquide Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude - Inventors: Francois Barraud - Web page: https://patentgrep.com/patent/US12109528B2 ## CPC - B01D 53/226: {in serial connexion} - B01D 53/228: {characterised by specific membranes} - B01D 53/229: {Integrated processes (Diffusion and at least one other process, e.g. adsorption, absorption)} - C10L 3/104: {Carbon dioxide} - B01D 2256/245: Methane - B01D 2257/504: Carbon dioxide - C10L 2290/46: Compressors or pumps - C10L 2290/548: Membrane- or permeation-treatment for separating fractions, components or impurities during preparation or upgrading of a fuel - Y02C 20/40: of CO2 - Y02E 50/30: Fuel from waste, e.g. synthetic alcohol or diesel - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - C10L: FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS - Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG] - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract Process and plant for membrane permeation treatment of a carbon dioxide and methane-containing biogas stream in which the biogas stream is compressed with a compressor and the compressed biogas stream is fed to a membrane separation unit comprising first and second modules each containing at least one membrane selective for carbon dioxide over methane. The first module separates the compressed biogas stream into a first, second, and third methane-deficient permeates (in comparison to the biogas stream) and a first methane-enriched retentate (in comparison to the biogas stream). The first permeate being richer in methane than the second or third permeates. The second module separates the first permeate into a fourth methane-deficient permeate and a second methane-enriched retentate. The second and third retentates are recycled back to an inlet of the compressor. ## Claims ### Claim 1 A process for a membrane permeation treatment of a methane and carbon dioxide-containing biogas stream, comprising the steps of: providing a plant comprising a compressor and a membrane separation unit that comprises first and second modules each comprising at least one membrane that is more permeable to carbon dioxide than methane, wherein: the first module is adapted and configured to receive a compressed biogas stream and separate it into a first permeate, a second permeate, a third permeate, and a first retentate, and the second module is adapted and configured to receive the first permeate from the first module and separate it into a fourth permeate and a second retentate; compressing the biogas stream, the compressor producing the compressed biogas stream; supplying the first module with the compressed biogas stream and separating the supplied compressed biogas stream into a first retentate that is enriched in methane relative to the biogas stream and first, second, and third permeates each of which is enriched in carbon dioxide relative to the biogas stream, the first permeate being richer in methane than the second or third permeates; supplying the second module with the first permeate and separating the supplied first permeate into a second retentate that is enriched in methane relative to the first permeate and a fourth permeate that is enriched in carbon dioxide relative to the first permeate; and recycling the second retentate and the third permeate to the inlet of the compressor where they are compressed with the biogas stream to produce the compressed biogas stream. ### Claim 2 (depends on 1) The process of claim 1, further comprising prepurifying the biogas stream upstream of the compressor so as to dry the biogas stream, reduce a CO2 concentration of the biogas stream, and/or remove volatile organic compounds from the biogas stream. ### Claim 3 (depends on 1) The process of claim 1, further comprising the steps of: measuring a methane concentration of the first retentate; and setting a pressure of the first retentate as a function of the measured methane concentration. ### Claim 4 (depends on 1) The process of claim 1, wherein the biogas stream is produced by a methanizer and said process further comprises the steps of: measuring a pressure of the first retentate; comparing the measured pressure with a target pressure value; and sending the first retentate back to the methanizer if the measured pressure is lower than the target pressure value. ### Claim 5 (depends on 1) The process of claim 1, wherein the biogas stream is produced by a methanizer and said process further comprises the steps of: measuring a methane concentration of the first retentate; comparing the measured concentration with a target concentration value; and sending the first retentate back to the methanizer if the measured concentration is lower than the target concentration value. ### Claim 6 (depends on 1) The process of claim 1, wherein each of the membranes of the first and second modules have a same carbon dioxide to methane selectivity. ### Claim 7 (depends on 1) The process of claim 1, wherein at least one of the first and second modules comprises a membrane with first carbon dioxide to methane selectivity that is different from another membrane or membranes of the first and second modules.