# US 10,479,685 B2 · Enriched acid gas for sulfur recovery > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,479,685 B2 - Document ID: US10479685B2 - Status: Granted - Kind: B2 - Application number: 15/681,093 - Filed: 2017-08-18 - Published: 2019-02-21 - Granted: 2019-11-19 - Earliest claimed: 2017-08-18 - Assignees: Saudi Arabian Oil Company - Applicants: Saudi Arabian Oil Company - Inventors: Nasser A. Al-Qahtani - Web page: https://patentgrep.com/patent/US10479685B2 ## CPC - C01B 17/167: {Separation} - B01D 53/1412: {Controlling the absorption process} - B01D 53/1462: {Removing mixtures of hydrogen sulfide and carbon dioxide} - B01D 53/1493: {Selection of liquid materials for use as absorbents} - B01D 2252/20405: Monoamines - B01D 2252/20431: Tertiary amines - B01D 2252/20489: with two or more hydroxyl groups - Y02P 20/151: Reduction of greenhouse gas [GHG] emissions, e.g. CO2 - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - 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) - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A method of sulfur enriching an acid gas stream in an acid gas enrichment system includes: (i) feeding an acid gas stream to a contactor, the acid gas stream comprising hydrogen sulfide (H2S), carbon dioxide (CO2), and hydrocarbons; (ii) separating the acid gas stream in the contactor to create a carbon dioxide rich stream and a purified acid gas stream; (iii) feeding the purified acid gas stream to a regenerator fluidly connected to the contactor; (iv) separating the purified acid gas stream in the regenerator to create a hydrogen sulfide rich stream and a hydrogen sulfide lean stream, the hydrogen sulfide rich stream having a concentration of hydrogen sulfide; and (v) periodically feeding at least a portion of the hydrogen sulfide rich stream exiting the regenerator to the acid gas stream entering the contactor. ## Claims ### Claim 1 A method of sulfur enriching an acid gas stream in an acid gas enrichment system, the method comprising: feeding an acid gas stream to an acid gas stream connector and thereafter to a contactor, the acid gas stream comprising hydrogen sulfide (H2S), carbon dioxide (CO2), and hydrocarbons; separating the acid gas stream in the contactor to obtain a carbon dioxide rich stream and a purified acid gas stream; feeding the purified acid gas stream to a regenerator fluidly connected to the contactor; separating the purified acid gas stream in the regenerator to obtain a hydrogen sulfide rich stream and a hydrogen sulfide lean stream, the hydrogen sulfide rich stream having a concentration of hydrogen sulfide; and periodically feeding at least a portion of the hydrogen sulfide rich stream exiting the regenerator through a recycle valve positioned along a fluid pathway upstream of the acid gas stream connector to combine with the acid gas stream prior to the combination of the hydrogen sulfide rich stream and the acid gas stream entering the contactor, wherein the periodically feeding comprises adjusting the recycle valve to direct the hydrogen sulfide rich stream exiting the regenerator to combine with the acid gas stream at the acid gas stream connector prior to the combination of the hydrogen sulfide rich stream and the acid gas stream entering the contactor, and wherein the adjusting the recycle valve comprises opening or closing the recycle valve based on an H2S content in the hydrogen sulfide rich stream. ### Claim 2 (depends on 1) The method of claim 1, wherein the adjusting the recycle valve comprises opening the recycle valve when the H2S content in the hydrogen sulfide rich stream is less than 35% wt. ### Claim 3 (depends on 1) The method of claim 1, wherein the adjusting the recycle valve comprises closing the recycle valve when the H2S content in the hydrogen sulfide rich stream is greater than or equal to 75% wt. ### Claim 4 (depends on 1) The method of claim 1, wherein the adjusting the recycle valve comprises closing the recycle valve when a threshold mass flow of the recycled enriched gas from the regenerator is 20% wt or greater than the acid gas stream to the contactor. ### Claim 5 (depends on 1) The method of claim 1, wherein the adjusting the recycle valve comprises closing the recycle valve when an H2S content in the carbon dioxide rich stream is at least 500 ppm. ### Claim 6 (depends on 1) The method of claim 1, further comprising removing at least a portion of the hydrogen sulfide rich stream exiting from the regenerator from an acid gas enrichment system. ### Claim 7 (depends on 1) The method of claim 1, further comprising periodically removing at least a portion of the hydrogen sulfide rich stream exiting from the regenerator from an acid gas enrichment system. ### Claim 8 (depends on 1) The method of claim 1, further comprising determining a residual factor based on a flow rate of the hydrogen sulfide rich stream and a flow rate of the carbon dioxide rich stream. ### Claim 9 (depends on 8) The method of claim 8, wherein the residual factor comprises a comparative measurement that compares flow rates of the hydrogen sulfide rich stream and the carbon dioxide rich stream in a predicted model to measured flow rates of the hydrogen sulfide rich stream and the carbon dioxide rich stream. ### Claim 10 (depends on 8) The method of claim 8, further comprising: (i) determining that the residual factor is within an acceptable level; (ii) determining a measured flow rate of the hydrogen sulfide rich stream is outside of an acceptable level; and (iii) based on the determinations in (i) and (ii), adjusting the recycle value toward an open state or maintaining the recycle valve at the open state. ### Claim 11 (depends on 8) The method of claim 8, further comprising: (i) determining that the residual factor is within an acceptable level; (ii) determining a measured flow rate of the hydrogen sulfide rich stream is within an acceptable level; and (iii) based on the determinations in (i) and (ii), adjusting the recycle value toward a closed state or maintaining the recycle valve at the closed state. ### Claim 12 (depends on 8) The method of claim 8, further comprising periodically removing at least a portion of the hydrogen sulfide rich stream exiting from the regenerator from an acid gas enrichment system. ### Claim 13 (depends on 1) The method of claim 1, wherein the adjusting the recycle valve further comprises closing the recycle valve when at least one of: the H2S content in the hydrogen sulfide rich stream is greater than or equal to 75% wt; a threshold mass flow of the recycled enriched gas from the regenerator is 20% wt or greater than a mass flow of the acid gas stream to the contactor; or an H2S content in the carbon dioxide rich stream is at least 500 ppm. ### Claim 14 (depends on 1) The method of claim 1, wherein the adjusting the recycle valve further comprises closing the recycle valve when: the H2S content in the hydrogen sulfide rich stream is greater than or equal to 75% wt; a threshold mass flow of the recycled enriched gas from the regenerator is 20% wt or greater than a mass flow of the acid gas stream to the contactor; and an H2S content in the carbon dioxide rich stream is at least 500 ppm. ### Claim 15 (depends on 1) The method of claim 1, wherein the adjusting the recycle valve further comprises opening or closing the recycle valve based on an operating pressure of the contactor. ### Claim 16 (depends on 15) The method of claim 15, wherein a setpoint of the recycle valve is based on the operating pressure of the contactor plus 3 psig. ### Claim 17 (depends on 1) The method of claim 1, wherein the adjusting the recycle valve further comprises opening or closing the recycle valve based on a volumetric flow rate of amine acid gas entering the contactor. ### Claim 18 (depends on 17) The method of claim 17, wherein a setpoint of the recycle valve is based on 20% of the amine acid gas volumetric flow rate. ### Claim 19 (depends on 6) The method of claim 6, wherein the removing comprises periodically removing at least the portion of the hydrogen sulfide rich stream exiting from the regenerator from the acid gas enrichment system. ### Claim 20 (depends on 9) The method of claim 9, further comprising: (i) determining that the residual factor is within an acceptable level; (ii) determining that the measured flow rate of the hydrogen sulfide rich stream is outside of an acceptable level; and (iii) based on the determinations in (i) and (ii), adjusting the recycle value toward an open state or maintaining the recycle valve at the open state. ### Claim 21 (depends on 9) The method of claim 9, further comprising: (i) determining that the residual factor is within an acceptable level; (ii) determining that the measured flow rate of the hydrogen sulfide rich stream is within an acceptable level; and (iii) based on the determinations in (i) and (ii), adjusting the recycle value toward a closed state or maintaining the recycle valve at the closed state.