# US 9,433,887 B2 · Membrane loop process for separating carbon dioxide for use in gaseous form from flue gas > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,433,887 B2 - Document ID: US9433887B2 - Status: Granted - Kind: B2 - Application number: 14/477,633 - Filed: 2014-09-04 - Published: 2014-12-18 - Granted: 2016-09-06 - Earliest claimed: 2014-09-04 - Assignees: Membrane Technology and Research, Inc. - Applicants: Johannes G Wijmans; Richard W Baker; Timothy C Merkel - Inventors: Johannes G Wijmans; Richard W Baker; Timothy C Merkel - Web page: https://patentgrep.com/patent/US9433887B2 ## CPC - B01D 53/22: by diffusion (manufacturing semi-permeable membranes B01D67/00; form, structure or properties of semi-permeable membranes B01D69/00; material for semi-permeable membranes B01D71/00) - B01D 53/62: Carbon oxides - F23J 15/006: {Layout of treatment plant} - F23J 15/02: of purifiers, e.g. for removing noxious material (traps for solid residues F23J3/04) - F23L 7/007: {Supplying oxygen or oxygen-enriched air} - B01D 2256/22: Carbon dioxide - B01D 2257/504: Carbon dioxide - B01D 2311/13: Use of sweep gas - F23J 2215/50: Carbon dioxide - F23J 2219/00: Treatment devices - Y02C 20/20: of methane - Y02C 20/40: of CO2 - Y02E 20/32: Direct CO2 mitigation - Y02E 20/34: Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery - 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) - F23J: REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES (combustion apparatus for consuming smoke or fumes, e.g. exhaust gases, F23G7/06) - F23L: SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ({air-supply arrangements for fluent fuels F23C;} firebridges with means for feeding air or steam F23M3/04; baffles or shields with air supply passages F23M9/04); VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS {(dampers and throat restrictors for open fire-places F24; air inlet valves for open fire fronts F24)}; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES - 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 The invention is a process involving membrane-based gas separation for separating and recovering carbon dioxide emissions from combustion processes in partially concentrated form, and then transporting the carbon dioxide and using or storing it in a confined manner without concentrating it to high purity. The process of the invention involves building up the concentration of carbon dioxide in a gas flow loop between the combustion step and a membrane separation step. A portion of the carbon dioxide-enriched gas can then be withdrawn from this loop and transported, without the need to liquefy the gas or otherwise create a high-purity stream, to a destination where it is used or confined, preferably in an environmentally benign manner. ## Claims ### Claim 1 A membrane process for treating flue gas, comprising: (a) performing a combustion step by combusting a mixture of a fuel and air, oxygen enriched air, or oxygen, thereby creating an exhaust stream comprising carbon dioxide and nitrogen; (b) splitting the exhaust stream into a first portion and a second portion without adjusting the composition of either portion; (c) providing a membrane having a feed side and a permeate side, and being selectively permeable to carbon dioxide over nitrogen and to carbon dioxide over oxygen; (d) performing a membrane separation step, comprising, (i) passing a first portion of the exhaust stream across the feed side; (ii) passing air, oxygen-enriched air, or oxygen as a sweep stream across the permeate side, (iii) withdrawing from the feed side a carbon dioxide-depleted vent stream, and (iv) withdrawing from the permeate side a permeate stream comprising oxygen and carbon dioxide; (e) passing at least a portion of the permeate stream to step (a) as at least part of the air, oxygen-enriched air, or oxygen used in step (a), thereby forming a gas-flow loop between the combustion step and the membrane separation step; (f) withdrawing a second portion of the exhaust stream from a point in the gas flow loop downstream of the combustion step and upstream of the membrane separation step; and (g) using, storing, or otherwise disposing of the second portion in a confined manner. ### Claim 2 (depends on 1) The process of claim 1, wherein the second portion is transported to a confining operation, where it is used, stored, or otherwise disposed of in a confined manner. ### Claim 3 (depends on 1) The process of claim 1, wherein the second portion is used for enhanced oil recovery. ### Claim 4 (depends on 1) The process of claim 1, wherein the second portion is used for enhanced coalbed or coal mine methane recovery. ### Claim 5 (depends on 1) The process of claim 1, wherein the second portion is used in the production of carbonates. ### Claim 6 (depends on 1) The process of claim 1, wherein the second portion is injected into subsurface water. ### Claim 7 (depends on 1) The process of claim 1, wherein the second portion comprises at least 20 vol % CO2. ### Claim 8 (depends on 7) The process of claim 7, wherein the second portion comprises at least 30 vol % CO2. ### Claim 9 (depends on 8) The process of claim 8, wherein the second portion comprises at least 40 vol % CO2. ### Claim 10 (depends on 7) The process of claim 7, wherein the second portion comprises less than 60 vol % CO2. ### Claim 11 (depends on 1) The process of claim 1, wherein the second portion comprises at least 3 vol % oxygen. ### Claim 12 (depends on 1) The process of claim 1, wherein between about 10 vol % and 50 vol % of the exhaust stream is withdrawn from the gas flow loop as the second portion. ### Claim 13 (depends on 1) The process of claim 1, wherein the first portion is compressed to a pressure of up to about 5 bar before being passed across the feed side of the membrane. ### Claim 14 (depends on 1) The process of claim 1, wherein the membrane exhibits a carbon dioxide permeance of at least 500 gpu under process operating conditions. ### Claim 15 (depends on 1) The process of claim 1, wherein the membrane exhibits a selectivity in favor of carbon dioxide over nitrogen of at least 10 under process operating conditions. ### Claim 16 (depends on 1) The process of claim 1, wherein the vent stream comprises 3 vol % carbon dioxide or less. ### Claim 17 (depends on 16) The process of claim 16, wherein the vent stream comprises 2 vol % carbon dioxide or less. ### Claim 18 (depends on 1) The process of claim 1, wherein the membrane comprises two or more membranes, and the two or more membranes are arranged in one or more modules, and wherein the one or more modules are arranged in a vertical configuration. ### Claim 19 A membrane process for treating flue gas, comprising: (a) performing a combustion step by combusting a mixture of a fuel and air, oxygen-enriched air, or oxygen, thereby creating an exhaust stream comprising carbon dioxide and nitrogen; (b) splitting the exhaust stream into a first portion and a second portion without adjusting the composition of either portion; (c) providing a membrane having a feed side and a permeate side, and being selectively permeable to carbon dioxide over nitrogen and to carbon dioxide over oxygen; (d) performing a membrane separation step, comprising, (i) passing a first portion of the exhaust stream across the feed side, (ii) passing air, oxygen-enriched air, or oxygen as a sweep stream across the permeate side, (iii) withdrawing from the feed side a carbon dioxide-depleted vent stream, and (iv) withdrawing from the permeate side a permeate stream comprising oxygen and carbon dioxide; (e) passing at least a portion of the permeate stream to step (a) as at least part of the air, oxygen-enriched air, or oxygen used in step (a), thereby forming a gas-flow loop between the combustion step and the membrane separation step; (f) withdrawing a second portion of the exhaust stream from a point in the gas flow loop downstream of the combustion step and upstream of the membrane separation step; and (g) using the second portion for enhanced oil recovery. ### Claim 20 (depends on 19) The process of claim 19, wherein the second portion comprises at least 30 vol % CO2. ### Claim 21 (depends on 20) The process of claim 20, wherein the second portion comprises at least 40 vol % CO2. ### Claim 22 (depends on 21) The process of claim 21, wherein the second portion comprises at least 50 vol % CO2.