# US 6,461,413 B1 · Method for dehydrating a wet gas using a liquid dessicant, with advanced regeneration of said dessicant > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,461,413 B1 - Document ID: US6461413B1 - Status: Granted - Kind: B1 - Application number: 09/555,643 - Filed: 2000-11-27 - Granted: 2002-10-08 - Earliest claimed: 1997-12-02 - Assignees: Prosernat - Inventors: Benoit Landreau; Jean-Claude Amande - Web page: https://patentgrep.com/patent/US6461413B1 ## CPC - B01D 53/263: {by absorption} - C10L 3/10: Working-up natural gas or synthetic natural gas - 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 ## Abstract In a process using a hydrophilic liquid desiccant, for dehydrating a gas containing water with regeneration of the steps of: (a) absorbing water by contact between the moist gas and regenerated liquid desiccant from step c), producing a dry gaseous effluent and a stream of liquid desiccant charged with water and absorbed gases; (b) regenerating the liquid desiccant charged with water in a regeneration zone constituting a reboiling zone and a distillation zone, the charged liquid desiccant being sent to said distillation zone, from which a vapor containing water leaves overhead and from which liquid desiccant still containing water leaves from the bottom in the reboiling zone; (c) passing the liquid desiccant from the reboiling zone of step b) and still containing water to an absorption zone, in which the water in the desiccant is vaporized and the water vapor is absorbed by a fraction of regenerated or non regenerated desiccant, passing the resultant desiccant which has absorbed water vapor to the reboiling zone of step b) and returning resultant regenerated desiccant from the absorption zone, to the absorption zone of step a). ## Claims ### Claim 1 A process for dehydrating a gas containing water which uses a hydrophilic liquid desiccant, with regeneration of said liquid desiccant, comprising: (a) a step for absorbing water by contact between said moist gas and regenerated liquid desiccant from step c), producing a dry gaseous effluent and a stream of liquid desiccant charged with water and absorbed gases; (b) a step for regenerating said liquid desiccant charged with water in a regeneration zone comprising a reboiling zone and a distillation zone, the charged liquid desiccant being sent to said distillation zone, from which a vapor containing water leaves overhead and liquid desiccant still containing water leaves from the bottom in the reboiling zone; and (c) a step in which said liquid desiccant from the reboiling zone of step b) and still containing water is sent to an absorption zone, in which the water in the vapor generated by said desiccant is absorbed by a fraction of regenerated or non regenerated desiccant, removed at a point in the process, returning said desiccant which has absorbed water from said vapor to the reboiling zone of step b) and returning the regenerated desiccant to the absorption zone of step a). ### Claim 2 (depends on 1) A process according to claim 1, wherein the absorption zone of step c), the desiccant from the reboiling zone of step b) is kept at substantially the same temperature using an integral heating means. ### Claim 3 (depends on 1) A process according to claim 1, wherein said moist gas is selected from natural gas and refinery gases and contains at least one light hydrocarbon containing 1 to 4 carbon atoms. ### Claim 4 (depends on 3) A process according to claim 3, wherein said light hydrocarbon is at least methane. ### Claim 5 (depends on 1) A process according to claim 1, wherein characterized in that the charged liquid desiccant from step a) acts as a cooling fluid at the head of the distillation zone of step b). ### Claim 6 (depends on 1) A process according to claim 1, further comprising after step a), a step d) in which the liquid desiccant charged with water and absorbed gases is depressurized and separated into a vapor containing principally said absorbed gases and a liquid phase containing principally the liquid desiccant charged with water. ### Claim 7 (depends on 6) A process according to claim 6, wherein: in step a), the moist gas stream is brought into contact in an absorption column A1 with a counter-current of regenerated liquid desiccant, which produces a dry gaseous effluent leaving overhead and a stream of liquid desiccant charged with water and absorbed gases leaving the bottom of said absorption column A1; in step b), the stream of liquid desiccant is sent to a distillation column D1 of a regeneration apparatus R1, which also comprises a reboiler R2 separating a vapor effluent rich in water leaving from the head of the regeneration apparatus R1 via a line 9 and a liquid effluent constituting the partially regenerated liquid desiccant leaving from the bottom thereof, which is sent to an absorber A2 via an overflow to undergo the second regeneration step c); and in step c), the liquid effluent leaving the overflow principally containing liquid desiccant generates a vapor which is rich in water in absorber A2, said water-rich vapor being brought into contact with liquid effluent arriving from the absorption column A1 via a line 8, by spraying it into the top of the absorber A2, said liquid effluent, having absorbed said vapor being recovered and sent to the reboiler R2 via an overflow 11 (step b)) and the liquid effluent from the reboiler and which has undergone the second absorption step c) being sent to the column A1 (step a)) via the line 3. ### Claim 8 (depends on 7) A process according to claim 7, characterized in that in the absorber A2, the desiccant arriving via the overflow 10 is kept at substantially the same temperature. ### Claim 9 (depends on 7) A process according to claim 7, wherein before separation step d), the liquid desiccant charged with water is sent as a cooling fluid to the head of the distillation column D1 of the regeneration apparatus R1. ### Claim 10 (depends on 7) A process according to claim 7, wherein in step d), the stream of liquid desiccant is depressurized by a valve V1 and sent to a flash separation drum S1 where it is separated into a vapor effluent leaving overhead via a line 6 and containing at least a portion of the absorbed gases and a liquid phase containing principally the liquid desiccant charged with water, leaving the bottom via a line 7. ### Claim 11 (depends on 7) A process according to claim 7, wherein the fraction of liquid desiccant used for absorbing water in step c) is a fraction of non regenerated liquid desiccant, and in that the upper portion and the walls of the absorber A2 are not insulated and in that the fraction of liquid desiccant which has absorbed the vapor is recovered in a collecting means and returned to the reboiler R2 of the regeneration apparatus R1, for regeneration in step b). ### Claim 12 (depends on 7) A process according to claim 7, wherein the fraction of liquid desiccant used for absorbing water in step c) is a fraction of non regenerated liquid desiccant, in that the fraction of charged liquid desiccant which is sent to the inlet to absorber A2 via line 8 is sprayed into a heat exchanger E5 inside absorber A2 on which it is cooled, and in that the fraction of liquid desiccant which has absorbed the vapor is recovered in a collecting means and sent to the reboiler R2 of the regeneration apparatus R1, for regeneration in step b). ### Claim 13 (depends on 7) A process according to claim 7, wherein the fraction of liquid desiccant used in step c) is a fraction of regenerated liquid desiccant. ### Claim 14 (depends on 1) A process according to claim 1, wherein said gas comprises minor proportions of aromatic compounds, also carbon dioxide, nitrogen and/or hydrogen sulfide. ### Claim 15 (depends on 1) A process according to claim 1, wherein the liquid desiccant is a glycol. ### Claim 16 (depends on 15) A process according to claim 15, wherein the liquid desiccant is triethylene glycol. ### Claim 17 (depends on 1) A process according to claim 1, wherein: in step a), the moist gas stream is brought into contact in an absorption column A1 with a counter-current of regenerated liquid desiccant, which produces a dry gaseous effluent leaving overhead and a stream of liquid desiccant charged with water and absorbed gases leaving the bottom of said absorption column A1; in step b), the stream of liquid desiccant is sent to a distillation column D1 of a regeneration apparatus R1, which also comprises a reboiler R2, separating a vapor effluent rich in water leaving from the head of the regeneration apparatus R1 via a line 9 and a liquid effluent constituting the partially regenerated liquid desiccant leaving from the bottom thereof, which is sent to an absorber A2 via an overflow to undergo the second regeneration step c); and in step c), the liquid effluent leaving the overflow principally containing liquid desiccant generates a vapor which is rich in water in absorber A2, said water-rich vapor being brought into contact with liquid effluent arriving from the absorption column A1 via a line 8, by spraying it into the top of the absorber A2, said liquid effluent, having absorbed said vapor being recovered and sent to the reboiler R2 via an overflow 11 (step b)) and the liquid effluent from the reboiler and which has undergone the second absorption step c) being sent to the column A1 (step a)) via the line 3. ### Claim 18 (depends on 17) A process according to claim 17, wherein the fraction of liquid desiccant used for desiccant used for absorbing water in step c) is a fraction of non regenerated liquid desiccant, and in that the upper portion and the walls of the absorber A2 are not insulated and in that the fraction of liquid desiccant which has absorbed the vapor is recovered in a collecting means and returned to the reboiler R2 of the regeneration apparatus R1, for regeneration in step b). ### Claim 19 (depends on 17) A process according to claim 17, wherein the fraction of liquid desiccant used for absorbing water in step c) is a fraction of non regenerated liquid desiccant, in that the fraction of charged liquid desiccant which is sent to the inlet to absorber A2 via line 8 is sprayed into a heat exchanger E5 inside absorber A2 on which it is cooled, and in that the fraction of liquid desiccant which has absorbed the vapor is recovered in a collecting means and sent to the reboiler R2 of the regeneration apparatus R1, for regeneration in step b).