Desulfurization of carbon dioxide-containing gases

Abstract

Sulfur-containing compounds are converted to elemental sulfur in the Claus process, and subsequently the residual sulfur-containing compounds are converted to H2S by hydrogenation of the Claus tail gas. After cooling, water is removed and compressed, and then removed, either by physical separation or by chemical reaction with a solid metal oxide to form a solid metal sulfide, and then oxidized and regenerated, to produce a recycled gas containing purified CO2 and at least one sulfur-containing compound recycled to the Claus process, along with any other sulfur-containing impurities. Some of the H2S in the Claus tail gas can be first removed by selective and / or non-selective amine absorption in a tail gas treatment unit before the residual H2S and any other residual sulfur-containing impurities are removed in a physical separation or chemical reaction step.

Description

Background Art

[0001] Cross - reference to related applications This application claims priority to U.S. Non - Provisional Patent Application No. 17 / 856,455, filed on July 1, 2022.

[0002] The present invention is in the field of carbon dioxide (CO2) recovery and purification. In particular, the present invention relates to methods and apparatuses for desulfurization of CO2 - containing streams for carbon capture and storage ("CCS").

[0003] In the art, there are numerous examples of methods for removing sulfur - containing compounds such as hydrogen sulfide (H2S), carbonyl sulfide (COS), mercaptan (i.e., thiol), carbon disulfide (CS2), and / or sulfur oxides (SO x ) from raw CO2 or other CO2 - containing gases.

[0004] GB871750 relates to a method for removing H2S from CO2 - containing gases generated by hydrocarbon combustion or in a blast furnace. Such gases usually contain up to 400 ppm of H2S. Since CO2 is mainly intended to be used in the synthesis of urea, the amount of H2S needs to be reduced to 2 ppm or less. This reference teaches reducing the amount of H2S in the CO2 gas to the required level by passing the gas through a zeolite layer activated by heating and from which the water of crystallization has been removed. The activation of the zeolite by discharging this water creates interstitial voids having dimensions that allow the adsorption of H2S. The gas supply to the zeolite can be dried or undried, and the zeolite can be thermally regenerated using a heated regeneration gas.

[0005] US5674463A relates to a method for purifying CO2 obtained from natural sources such as natural gas, or industrially produced in particular by the combustion of hydrocarbon products, for use in applications requiring high purity CO2, such as the manufacture of food or medical products. This reference teaches that CO2 and H2S are removed from the CO2 gas by first contacting the CO2 with water vapor in the presence of a hydrolysis catalyst such as activated alumina to convert the COS in the gas to H2S, and then using an oxidation catalyst such as iron oxide to convert the resulting H2S in the gas to form elemental sulfur and metal sulfides, which are then removed from the gas. Residual sulfur compounds can be removed by contacting the remaining gas with copper oxide, zinc oxide, or a mixture of copper-zinc oxide.

[0006] US2012 / 0012000A primarily relates to the separation of acidic (i.e., sulfur-containing) synthesis gas, which is obtained from the gasification of solid or liquid carbonaceous feedstocks and contains hydrogen (H2) and carbon monoxide (CO), as well as H2S and CO2, into a CO2 product stream suitable for at least underground storage, a synthesis gas (H2 / CO) product stream suitable for use in chemical plants or refineries or as fuel for gas turbines, and an H2S-enriched stream that can be further processed in, for example, a Krauss plant or other suitable sulfur recovery system. This reference teaches introducing acidic synthesis gas into a pressure swing adsorption (PSA) system that separates a feed gas into a synthesis gas product stream and a stream enriched with CO2 and H2S, or separates an H2S-deficient feed gas (produced in an acidic PSA system) into a synthesis gas product stream and a CO2-enriched gas stream. The acidic PSA system contains an H2S-selective adsorbent such as silica gel, activated carbon, or molecular sieves.

[0007] WO2016 / 075109A discloses a process for removing H2S equivalents such as COS and / or CS2 by adsorption from a CO2-containing Klaus tail gas. The tail gas containing H2S equivalents and CO2 is supplied to an adsorption system, where it comes into contact with an alumina-based adsorbent material to produce a CO2-enriched first product gas. The adsorbent material is regenerated with a purge gas containing vapor to recover the adsorbed impurities in the form of H2S, obtaining a second product gas containing H2S, which is recycled to a Klaus unit. Optionally, the purged adsorbent material is then dried.

[0008] However, especially when CO2 is intended for CCS, new methods and apparatus for desulfurizing CO2-containing streams are still needed, taking into account low maximum limits of sulfur-containing compounds (e.g., less than 100 ppm total). [Overview of the Initiative]

[0009] The present invention relates to a method for desulfurizing CO2-containing gas streams. Such streams are often by-products of crude oil refining or other industrial processes involving physical and chemical gas treatment units used in refineries, natural gas processing plants, and gasification or synthesis gas plants, and may be called “acidic” gas streams. These “acidic” gases often (but not always) contain H2S as an impurity, along with one or more of CS2, COS, and mercaptans.

[0010] Such gases are typically treated in the Krauss process, which recovers elemental sulfur from gaseous H2S in the presence of O2, according to the following overall reaction. 2H2S + 3O2 → 2SO2 + 2H2O 4H2S + 2SO2 → 3S2 + 4H2O

[0011] The Krauss process may involve either a thermal or catalytic process, but typically a combination of both is used to increase the overall yield of sulfur. In the thermal process, gaseous H2S undergoes a quasi-stoichiometric combustion reaction at temperatures above 850°C, producing elemental sulfur and water. In the catalytic process, gaseous H2S reacts with SO2 on a catalyst such as activated aluminum(III) or titanium(IV) oxide to produce further elemental sulfur and water.

[0012] Most commercial Krauss processes involve a thermal stage followed by one or more catalytic stages, with sulfur removed between stages by a condenser. The first stage typically operates at approximately 315°C to 330°C, helping to hydrolyze COS and CS2. Subsequent stages typically operate at lower temperatures, above the sulfur dew point, but to increase catalytic conversion. Thus, the second stage may operate at approximately 240°C, and the third stage at approximately 200°C. O2 can be supplied to the Krauss process in the form of air, i.e., an "air-Krauss" process, or in the form of pure O2 or O2-enriched air, i.e., an "oxy-Krauss" process.

[0013] The inventors have recognized that sulfur-containing compounds other than H2S, such as COS, CS2, and mercaptans, from the original "acidic" gas can be removed from the tail gas by generating a recycled gas containing purified CO2 and at least one sulfur-containing compound that is recycled back into the Krauss process, either by physical separation, by hydrogenation which forms H2S that can be removed together with SO2 from the Krauss process and subsequently together with residual H2S from the Krauss process, or by chemical separation which forms a metal sulfide by chemical reaction with at least one solid metal oxide and then oxidative regeneration.

[0014] The physical separation of H2S and any other sulfur-containing compounds from CO2 is (i) Selective adsorption of sulfur-containing compounds onto adsorbent materials that are selective for such compounds - adsorption is purely physical in the sense that the compound in question is not transformed by a chemical reaction with the adsorbent, and as a result when the adsorbent material is regenerated and the adsorbed compound is removed, the spent regenerated gas will contain impurities from the impure gas feed to the adsorbent, or (ii) This may be achieved by either distillation and / or partial condensation by phase separation.

[0015] Alternatively, H2S and any other sulfur-containing compounds can be removed from impure CO2 gas by reaction with a bed containing at least one solid metal oxide, such as zinc oxide (ZnO), where the metal oxide is converted to a metal sulfide, such as zinc sulfide (ZnS). The metal oxide can be regenerated by oxidation using a regenerating gas containing O2 to release sulfur from the bed as sulfur dioxide (SO2).

[0016] Therefore, according to a first aspect of the present invention, a method for desulfurizing crude carbon dioxide (CO2) gas comprising hydrogen sulfide (H2S) and optionally at least one other sulfur-containing impurity, Crude CO2 gas containing H2S is supplied to the Krauss process to convert H2S into elemental sulfur in the presence of oxygen (O2) gas, producing Krauss-tail gas containing CO2, residual H2S, and at least one other sulfur-containing impurity. The klaus tail gas is supplied to a hydrogenation process to convert at least one other sulfur-containing impurity into H2S in the presence of hydrogen (H2), thereby producing H2S-enriched CO2 tail gas. The H2S-enriched CO2 tail gas is cooled, condensed water is removed, and cooled H2S-enriched CO2 tail gas is produced. Compressing the cooled H2S-enriched CO2 tail gas, or the H2S-containing impure CO2 gas derived therefrom, to produce compressed impure CO2 gas containing H2S, By physical separation and / or chemical reaction with at least one solid metal oxide, solid metal sulfides are formed, and then by oxidative regeneration, H2S and any other sulfur-containing impurities are removed from the compressed impure CO2 gas to produce a first recycled gas containing purified CO2 and at least one sulfur-containing compound. A method is provided which includes recycling the first recycled gas to the Krauss process to convert the at least one sulfur-containing compound into elemental sulfur.

[0017] According to a second aspect of the present invention, an apparatus for desulfurizing crude CO2 gas containing H2S and optionally at least one other sulfur-containing impurity, A Krauss unit for removing H2S from crude CO2 gas, A first inlet for the oxidizing gas containing O2, A second inlet for the crude CO2 gas, A first outlet for Claustail gas containing CO2, residual H2S, and at least one other sulfur-containing impurity, A Krauss unit, equipped with a second outlet for elemental sulfur, A source of oxidizing gas containing O2 is in fluid flow communication with the first inlet of the Krauss unit, The crude CO2 source is in fluid flow communication with the second inlet of the Krauss unit, A hydrogenation unit for converting at least one other sulfur-containing impurity in the Claustail gas into H2S, The first inlet of the Krauss unit is in fluid flow communication with the first inlet, A second entrance for H2, A hydrogenation unit comprising a first outlet for H2S-enriched CO2 tail gas, The H2 supply source is in fluid flow communication with the second inlet of the hydrogenation unit, A cooling unit for cooling H2S-enriched CO2 tail gas, The first outlet of the hydrogenation unit and the first inlet, which is in fluid communication with it, a first outlet for the cooled H2S-enriched CO2 tail gas, and a second outlet for the condensed water, and a cooling unit; a compression unit for compressing the cooled H2S-enriched CO2 tail gas or the impure CO2 gas containing H2S derived therefrom, the compression device having an inlet in fluid flow communication with the first outlet of the cooling unit, and an outlet for the compressed impure CO2 gas, and a compression unit; a purification unit for removing H2S and any other sulfur-containing impurities from the compressed impure CO2 gas by forming solid metal sulfides by physical separation or by chemical reaction with at least one metal oxide and then oxidatively regenerating, a first inlet in fluid flow communication with the first inlet of the Claus unit, and a first outlet for the purified CO2, and a second outlet for the first recycle gas containing at least one sulfur-containing compound, and the second outlet of the purification unit being in fluid communication with the Claus unit, and a purification unit.

[0018] The term "raw CO2" refers to a gas mixture containing at least about 50 mol% CO2, e.g., from about 50 mol% to about 80 mol% CO2. Raw CO2 is a gaseous mixture containing H2S and typically water, although in some embodiments other components, e.g., one or more other sulfur-containing compounds, may be present.

[0019] The term "sulfur-containing compound" refers to a compound containing at least one sulfur atom. Examples of sulfur-containing compounds include H2S, COS, CS2, SO2, and mercaptans (or thiols). H2S is typically present in the crude CO2 feed and is also produced in the hydrogenation step of the present invention. COS and / or CS2 may be present in the crude CO2 feed but can also be produced in the Krauss process. SO2 is typically not present in the crude CO2 feed but is produced in the Krauss process. Mercaptans are not produced in the process of the present invention, so if present in CO2, they enter with the crude CO2 feed gas.

[0020] The term "sulfur-containing impurities" refers to individual sulfur-containing compounds present in the gas at impurity levels, e.g., 5 mol% (or 50,000 ppm) or less, and typically 3 mol (or 30,000 ppm) or less.

[0021] The term "impure CO2" refers to a CO2-containing gas that has a higher proportion (in terms of mole fraction) of CO2 than the crude CO2 from which it is derived. Such gases typically contain at least about 80 mol% CO2, for example, about 80 mol% to about 95 mol% CO2.

[0022] The term "physical separation" refers to the process by which at least one sulfur-containing component of a fluid mixture is removed from the other components of the mixture without chemical change, reaction, or transformation. In other words, the component is separated from the mixture "as is," that is, in the form in which it exists in the fluid mixture.

[0023] The term "oxidative regeneration" typically refers to the process by which solid metal oxides are regenerated from solid metal sulfides through oxidation, using a regeneration gas that typically contains O2.

[0024] The term "purified CO2" refers to a CO2-containing gas that has a higher proportion (in terms of mole fraction) of CO2 than the impure CO2 from which it is derived. Such gases typically contain at least about 95 mol% CO2, e.g., about 95 mol% to about 100 mol% CO2, and typically the total amount of sulfur-containing compounds is 500 ppm or less, and sometimes 100 ppm or less.

[0025] The term "further purified CO2" refers to a CO2-containing gas that has a higher proportion (in terms of mole fraction) of CO2 than the purified CO2 from which it is derived. Such a gas typically contains at least about 99 mol% CO2, e.g., about 99 mol% to 100 mol% CO2, and typically the total amount of sulfur-containing compounds is 100 ppm or less.

[0026] An "H2S-enriched" gas is a gas that contains a higher proportion (in terms of mole fraction) of H2S than the H2S-containing gas from which it is derived.

[0027] A "H2S-deficient" gas is a gas that contains a lower proportion (in terms of mole fraction) of H2S than the H2S-containing gas from which it is derived. This term encompasses (but is not limited to) gases that do not contain H2S.

[0028] A "sulfur-selective adsorbent material" is a material that preferentially adsorbs sulfur-containing compounds over at least one other component in a gas mixture, that is, a material that has a higher affinity for sulfur-containing compounds than other components in the gas mixture.

[0029] "Selective adsorption" is a process in which sulfur-containing components removed from impurity CO2 are selectively adsorbed onto an adsorbent, and then recovered (in the same chemical form) by desorption using regenerating gas.

[0030] A "water-selective adsorbent material" is a material that preferentially adsorbs water over at least one other component in a gas mixture, that is, a material with a higher affinity for water than the other components.

[0031] The "bed" selectively contains particles of either adsorbent material or solid metal oxide, or both. A particle bed is typically a packed bed, but can also be a fluidized bed. In packed beds containing both types of particles, the particles are typically in separate layers.

[0032] In the context of selective adsorption units or reactors, the term "downstream" refers to the relative location when the unit or reactor is on-feed. The term "upstream" should be interpreted accordingly.

[0033] The term "selective amine absorption" refers to a separation or purification process that uses an amine that selectively (but not necessarily exclusively) absorbs a specific acidic gas component, such as H2S, in a gas mixture, such as H2S-enriched CO2 tail gas.

[0034] The term "non-selective amine absorption" refers to a separation or purification process that uses amines to absorb a specific acidic gas component, such as H2S, sometimes in combination with another acidic gas component, such as CO2, in a gas mixture, such as an H2S-deficient CO2 tail gas.

[0035] The term "non-condensable gas" refers to a gas that cannot be condensed under the conditions of the present invention. Examples of non-condensable gases include H2, N2, O2, and noble gases.

[0036] A "CO2 purification unit" (i.e., a "CPU") is a unit that purifies (or further purifies) CO2 by partial condensation through phase separation. Such a unit typically comprises a heat exchanger for cooling and partially condensing the gas to be purified, and one or more phase separators in series, for example, two, for separating the condensed phase from the gas phase.

[0037] A “distillation unit” is a unit that purifies (or further purifies) CO2 by distillation. Such a unit typically comprises a heat exchanger for cooling and optionally at least partially condensing the gas to be purified, and at least one distillation column. The column may include a tray or be packed with loose and / or structured packing to increase the vapor / liquid contact surface area within the column. [Brief explanation of the drawing]

[0038] Preferred embodiments of the present invention are described with reference to the drawings. [Figure 1] This is a simplified flow sheet describing an embodiment of the present invention, in which tail gas from a Krauss plant is treated by hydrogenation and selective amine absorption (to remove H2S) in a tail gas treatment unit before CO2 is recovered by non-selective amine absorption and purified in a selective adsorption unit (or reactor). [Figure 2] Figure 1 is a simplified flow sheet illustrating an alternative embodiment of the present invention, in which impure CO2 gas from a tail gas treatment unit is compressed and then purified first in a selective adsorption unit (or reactor), and then purified by distillation or partial condensation and phase separation. [Figure 3] This is a simplified flow sheet illustrating a modified version of the process shown in Figure 1, without the selective amine absorption step. [Figure 4] This is a simplified flow sheet illustrating a modified version of the process shown in Figure 2, without the selective amine absorption step. [Figure 5] This is a simplified flow sheet of an alternative embodiment of the present invention, in which the purification unit comprises a first stage including a CPU and a second stage including a distillation unit. [Figure 6] This is a simplified flow sheet illustrating a modified version of the process shown in Figure 5, involving sulfur removal (unit 50) on flow 107 from CPU unit 56. [Figure 7]Figures 1 to 5 are simplified flow sheets illustrating embodiments of tail gas treatment processes that may be integrated with the SUPERCLAUS® process and / or the EUROCLAUS® process. [Modes for carrying out the invention]

[0039] A first aspect of the present invention is a method for desulfurizing crude CO2 gas containing H2S and optionally at least one other sulfur-containing impurity. The method comprises feeding crude CO2 gas containing H2S to a Krauss process to convert H2S to elemental sulfur in the presence of oxygen (O2) gas to produce a Krauss tail gas containing CO2, residual H2S, and at least one other sulfur-containing impurity. The Krauss tail gas is fed to a hydrogenation process to convert other sulfur-containing impurities (or impurities) to H2S in the presence of H2 to produce an H2S-enriched CO2 tail gas. The H2S-enriched CO2 tail gas is cooled to remove water, and the resulting cooled H2S-enriched tail gas (or impure CO2 gas containing H2S derived therefrom) is compressed to produce compressed impure CO2 gas containing H2S. By physical separation or by chemical reaction with solid metal oxides to form solid metal sulfides, which are then converted back to metal oxides by oxidative regeneration, H2S and any other sulfur-containing impurities are removed from the compressed gas, producing purified CO2 and a first recycled gas containing at least one sulfur-containing compound. The first recycled gas is recycled back into the Krauss process, where at least one sulfur-containing compound is converted back into elemental sulfur.

[0040] Embodiments of the present invention improve the recovery and / or purity of CO2 from crude CO2 containing H2S and optionally any other sulfur-containing impurities.

[0041] The Krauss process may be the conventional "air Krauss" process or "oxy Krauss" process as described above, but in either case, it typically includes a thermal stage and at least one, for example, one to four, preferably two or three catalytic stages. The recycled gas may be used for supply to the Krauss process or recycled to interstage locations, i.e., between two stages in the process, or both.

[0042] The Krauss process may alternatively be the SUPERCLAUS® process, the EUROCLAUS® process, or a combination of two Krauss processes.

[0043] The SUPERCLAUS® process consists of a thermal stage followed by at least three catalytic reaction stages, with sulfur removed by a condenser at each stage. The first reactor is filled with a standard Krauss catalyst such as activated alumina, promoted alumina, and / or titania (TiO2), and the final reactor is filled with a selective oxidation catalyst such as iron oxide and / or chromium oxide (or other metal oxides) on alpha-alumina or silica. In the thermal stage, the acidic gas is burned in a quasi-stoichiometric amount of controlled combustion air (or pure O2 or O2-enriched air), and the tail gas exiting the final Krauss reactor typically contains 0.8–1.0 volume% H2S. The selective oxidation catalyst in the final reactor oxidizes H2S to sulfur with an efficiency of over 85%. If a sulfur recovery rate of over 99% is required, a third Krauss reactor stage can be placed upstream of the selective oxidation reactor.

[0044] The EUROCLAUS® process consists of a thermal stage followed by three or four catalytic reaction stages, with sulfur removed by a condenser at each stage. The final Claus reactor is filled with a layer of hydrogenation catalyst, such as a CoMo catalyst (cobalt and molybdenum oxides on alumina), followed by reactors filled with selective oxidation catalysts, such as iron oxide and / or chromium oxide (or other metal oxides) on alpha-alumina or silica. In the thermal stage, the acidic gas is combusted with a quasi-stoichiometric amount of controlled combustion air, and the tail gas exiting the final Claus reaction typically contains 0.8–1.0 volume% H₂S and 100–200 ppmv SO₂. This low SO₂ content is obtained by the hydrogenation catalyst that converts SO₂ to H₂S in the final Claus reactor. The selective oxidation catalyst in the final reactor oxidizes H₂S to sulfur with an efficiency of over 85%. A total sulfur recovery efficiency of up to 99.3% can be achieved with a three-stage reactor, and up to 99.5% with a four-stage reactor.

[0045] Crude CO2 gas may be supplied to the Krauss process at a temperature of about 10°C to about 70°C, for example, about 45°C, and at a pressure in the range of about 0.3 bar gauge (g) to about 30 bar g, for example, about 0.3 bar g to about 1.8 bar g, for example, about 0.9 bar g.

[0046] The hydrogenation process requires H2 as a reducing gas. H2 can be generated in an H2 generation process, such as the partial oxidation of natural gas with quasi-stoichiometric air / oxygen in a reducing gas generator, and then supplied to the hydrogenation process. However, the demand for fresh H2 from the H2 generation process, or "makeup" H2, can be reduced or completely eliminated by recycling H2 from another point in the process (see below).

[0047] The klaus tail gas may be supplied to the hydrogenation process at a temperature in the range of about 120°C to about 200°C, for example, about 130°C, and at a pressure in the range of about 0.2 bar g to about 30 bar g, for example, about 0.2 bar g to about 1.8 bar g, for example, about 0.3 bar g. The pressure and / or temperature of the klaus tail gas can be adjusted as needed using conventional means before being supplied to the hydrogenation process, but in a preferred embodiment, the tail gas is supplied to the hydrogenation process without such adjustment.

[0048] The H2S-enriched CO2 tail gas from the hydrogenation process is cooled. Any suitable cooling process may be used, but in a preferred embodiment, the H2S-enriched CO2 tail gas is quenched by direct contact with liquid water. After removing the condensed water, the cooled H2S-enriched CO2 tail gas is compressed to form compressed impure CO2 gas containing H2S.

[0049] The cooled H2S-enriched CO2 tail gas may be supplied to a compression unit at a temperature in the range of approximately 10°C to approximately 70°C, for example, approximately 45°C, and at a pressure in the range of approximately 0.3 bar g to approximately 1.8 bar g, for example, approximately 1 bar g. The compression unit compresses the gas to a pressure in the range of approximately 1 bar g to approximately 120 bar g, for example, approximately 30 bar g.

[0050] The content of H2S and any other sulfur-containing impurities in the compressed impure CO2 gas is significantly reduced, in some embodiments to levels below 100 ppm, by physical separation or by chemical reaction with at least one solid metal oxide to form solid metal sulfides, followed by oxidative regeneration, along with a first recycled gas containing at least one sulfur-containing compound that is recycled to the Krauss process.

[0051] Physical separation can be carried out by selective adsorption or by partial condensation via distillation and / or phase separation.

[0052] In embodiments using selective adsorption, the method includes removing H2S and any other sulfur-containing compounds from compressed impure CO2 gas by adsorption on a floor of at least one adsorbent material selective for sulfur compounds within a selective adsorption unit to produce purified CO2, and after desorption, producing spent recycled gas containing H2S and any other sulfur-containing compounds from the compressed impure CO2 gas as a first recycled gas.

[0053] Such adsorbent materials include silica gel, molecular sieves (e.g., 4A or 5A zeolite), activated alumina, and activated carbon (e.g., Calgon Cu material and Cu-impregnated carbon). Sulfur-containing compounds are reversibly adsorbed onto a bed of solid-selective adsorbents and then, preferably, desorbed when the solid adsorbent is saturated with sulfur-containing compounds. The adsorption process can operate any preferred cycle, including PSA, vacuum swing adsorption (VSA), or temperature swing adsorption (TSA). Specific examples include TSA with silica gel, PSA or VSA with silica gel, TSA with zeolite (e.g., 4A, 5A), and TSA with Cu-impregnated carbon.

[0054] The compressed impure CO2 gas may be supplied to the selective adsorption unit at a temperature in the range of approximately 10°C to approximately 70°C, for example, approximately 50°C.

[0055] The adsorbent bed of a selective adsorption unit is suitably regenerated using purified (or further purified) CO2 generated in the process. The temperature and / or pressure of the regenerated gas may be adjusted as necessary using conventional means, depending on where it is removed from the process and the type of cycle used, e.g., the temperature and / or pressure of the CO2 gas in a TSA, VSA, or PSA. In embodiments using solid metal oxides to purify compressed impure CO2 gas, the method involves passing the compressed gas through a bed containing at least one solid metal oxide in the reactor. H2S and any other sulfur-containing impurities in the gas convert the metal oxide in the bed into the corresponding metal sulfides, thereby removing the impurities from the gas and producing purified CO2. The metal oxide in the bed is oxidatively regenerated by passing a regenerated gas containing O2 through the bed, usually in the direction of backflow into the gas when the bed is “feeding,” thereby emitting sulfur from the bed in the form of SO2. The spent regenerated gas containing SO2 is then recycled to the Krauss process as a first recycled gas.

[0056] In embodiments in which H2S is removed by a chemical reaction with at least one solid metal oxide, suitable solid metal oxides include zinc(II) oxide (ZnO), iron(III) oxide (Fe2O3), aluminum(III) oxide (Al2O3), and group II metal oxides such as calcium oxide (CaO), magnesium oxide (MgO), and barium oxide (BaO). A single metal oxide may be used, but in some embodiments, a mixture of metal oxides (i.e., a mixed metal oxide) is used. In some embodiments, the mixture of solid metal oxides contains about 40% to about 60% by weight, for example, about 50% by weight of ZnO.

[0057] Examples of suitable mixed metal oxides are disclosed in US4044114 and include, with or without additional elements, about 20% to about 85% by weight, preferably about 25% to about 80% by weight, zinc oxide (calculated as ZnO), about 0.9% to about 50% by weight, alumina (calculated as Al2O3), and about 2% to about 45% by weight, oxides of group II metals, preferably calcium (calculated as an oxide).

[0058] The compressed impure CO2 gas may be supplied to the reactor at a temperature in the range of approximately 300°C to approximately 800°C, or approximately 300°C to approximately 700°C, for example, approximately 400°C to approximately 550°C. After compression, the temperature of the compressed gas may be adjusted as necessary using conventional means before being supplied to the reactor containing the solid metal oxide.

[0059] The mixed metal oxide bed in the reactor is preferably regenerated by adding an oxygen-containing gas, for example, purified (or further purified) CO2 generated in the process, to an amount of O2 in the range of about 1 to about 5 mol%, for example, about 2 mol% oxygen. The temperature and / or pressure of the regenerating gas can be adjusted as necessary using conventional means, depending on the temperature and / or pressure of the CO2 gas at the point where it is removed from the process.

[0060] The first recycled gas can be recycled to the Krauss process at a temperature in the range of about 10°C to about 70°C, for example, about 50°C, and at a pressure in the range of about 0.3 bar g to 30 bar g, or in the range of about 0.3 bar g to about 1.8 bar g, for example, about 1 bar g. In embodiments where the temperature and / or pressure of the first recycled gas exiting the purification process is not appropriate considering the operating conditions of the Krauss unit, the temperature and / or pressure of the first recycled gas can be appropriately adjusted by conventional means.

[0061] Compressed impure CO2 gas supplied to a reactor containing a selective adsorption unit or a solid metal oxide will typically contain water. In such cases, the water can be removed by adsorption onto at least one water-selective adsorbent material located downstream of either a sulfur-selective adsorbent material or a solid metal oxide. Suitable water-selective adsorbent materials include those identified above as sulfur-selective adsorbent materials. The water-selective adsorbent material may be located in the same container as the sulfur-selective adsorbent material or metal oxide, for example, in a separate layer or in a separate container.

[0062] Alternatively, water can be removed by absorption in a separate container, such as a glycol unit, located downstream of either the selective adsorption unit or the reactor.

[0063] Regardless of whether sulfur-containing impurities are removed by selective adsorption or chemical reaction with solid metal oxides, the regenerated gas may contain small amounts of water. However, if water is present, the amount of water is not sufficient to hydrolyze the sulfur-containing compounds discharged from the regenerated floor. In this regard, the regenerated gas typically contains less than 5 mol%, preferably less than 2 mol%, and more preferably less than 1 mol% of water. Such amounts of water are considered minimal in the art.

[0064] The H2S-enriched tail gas can be supplied directly to a compression unit for compression, producing compressed impure CO2. However, in some embodiments, this method includes recovering H2S from the H2S-enriched CO2 tail gas by selective amine absorption to produce H2S-deficient CO2 tail gas and recovered H2S, and recycling the recovered H2S to a Krauss process to convert the recovered H2S into elemental sulfur.

[0065] The H2S-enriched CO2 tail gas can be supplied to the selective amine absorption unit at a temperature of approximately 10°C to approximately 70°C, for example, approximately 50°C, and at a pressure of approximately 0.05 bar g to approximately 30 bar g, for example, approximately 0.05 bar g to approximately 1.8 bar g, for example, approximately 0.1 bar g.

[0066] For example, conventional selective amine absorption processes that use methyldiethanolamine (MDEA) as the selective amine are suitable for use in these embodiments of the present invention.

[0067] H2S-deficient tail CO2 gas can be supplied directly to a compression unit for compression, producing compressed impure CO2. However, in some embodiments, the method includes recovering CO2 and residual H2S from the H2S-deficient CO2 tail gas by non-selective amine absorption, and producing an impure CO2 gas containing H2S, along with waste gas containing CO2 and at least one non-condensable gas.

[0068] H2S-deficient CO2 tail gas can be supplied to a non-selective amine absorption unit at a temperature of approximately 10°C to approximately 70°C, for example, approximately 50°C, and at a pressure of approximately 0.01 bar g to approximately 30 bar g, for example, approximately 0.01 bar g to approximately 1.8 bar g, for example, approximately 0.1 bar g.

[0069] Conventional non-selective amine absorption processes using, for example, monoethanolamine (MEA), activated methyldiethanolamine (aMDEA), or diethanolamine (DEA) as the non-selective amine are suitable for use in these embodiments of the present invention.

[0070] Depending on the composition, any exhaust gas generated in the present invention may be exhausted or supplied to a thermal oxidizer, which is burned to produce flue gas that complies with local emission standards, and optionally vapor. If the exhaust gas contains a significant amount of H2, the exhaust gas itself can be used as fuel, or H2 can be recovered from the exhaust gas.

[0071] As shown above, purified CO2 may contain less than 100 ppm of sulfur-containing impurities, in which case further purification is typically not required for CCS. However, in embodiments where the amount of impurities exceeds this threshold, further purification is typically required.

[0072] In embodiments requiring further purification, the method may include feeding the purified CO2 into a further purification process to produce a second recycled gas containing further purified CO2 and CO2 and H2, and recycling the second recycled gas, or an H2-enriched gas derived therefrom, into a hydrogenation process. The second recycled gas, or a portion thereof, is typically purged in the process to prevent the accumulation of H2 (if there is an excess), or N2 and / or Ar noncondensable pollutants.

[0073] Further purification processes for further purifying CO2 may involve distillation, such as the process disclosed in US10254042, and / or partial condensation by phase separation, such as the process disclosed in US7819951, and the inventors recognize that both of these may be appropriately adapted for integration with the present invention.

[0074] Both distillation and partial condensation of CO2 require temperatures ranging from the critical temperature of CO2 (i.e., about +31°C) to the triple point temperature of CO2 (i.e., about -57°C). In some embodiments, partial condensation by distillation and / or phase separation is carried out at "low" (or below ambient temperature) temperatures, typically in the range of about +15°C to about -55°C. In other embodiments, partial condensation by distillation and / or phase separation is carried out at temperatures in the range of about 0°C to -30°C, particularly for H2S distillation from CO2.

[0075] The purified CO2 is typically at a temperature of about 10°C to about 70°C, for example, about 50°C, and at a pressure of about 10 bar g to about 120 bar g, for example, about 30 bar g. Therefore, in embodiments where further purification is required, the purified CO2 is typically cooled to the preferred temperatures described above before further purification, for example, by heat exchange with a coolant. Additionally, or alternatively, if the gas pressure is not sufficient for further purification, the purified CO2 is further compressed.

[0076] Recycling H2 into the hydrogenation process reduces the amount of additional H2 that needs to be generated to meet the demand in that process, thereby reducing or even eliminating the size of the required hydrogenation unit, and thereby saving capital and operating costs. If the demand is only partially met by the recycled H2, the additional H2 can be generated in an H2 generation process, as discussed above. However, in some embodiments, the amount of H2 recycled into the hydrogenation process is sufficient to meet the H2 demand in that process, completely eliminating the need for an H2 generation process.

[0077] Recycling CO2 into the hydrogenation process increases overall CO2 capture. However, it may be desirable or advantageous to reduce the amount of CO2 recycled into the hydrogenation unit in the second recycled gas, for example, to reduce the size of the hydrogenation unit. In such cases, the method may include recovering H2 gas from the recycled gas supplied to the hydrogenation process in a membrane separation process to produce an H2-enriched gas that is recycled into the hydrogenation unit, together with the waste gas containing CO2 and at least one non-condensable gas.

[0078] Using conventional membrane separation units, H2 gas can be recovered from recycled gas that is recycled into a hydrogenation process. The membrane may be a spiral-shaped, hollow fiber membrane made from a polymer such as polysulfone, polyimide, or cellulose acetate. Examples of suitable membrane separation processes are disclosed in US2010 / 126180A, and the inventors recognize that these can be appropriately adapted for integration with the present invention.

[0079] In embodiments in which H2S-enriched CO2 tail gas is directly compressed to produce compressed impure CO2 gas containing H2S, the method may include feeding the purified CO2 to a further purification process as described above to produce a second recycled gas containing further purified CO2 and CO2 and H2, and recycling the second recycled gas, or an H2-enriched gas derived therefrom, to a hydrogenation process. The second recycled gas, or a portion of the H2-enriched gas derived therefrom, is typically purged in the process to prevent the accumulation of H2 (if there is an excess), or N2 and / or Ar.

[0080] As described above, purification by physical separation may also be carried out by distillation and / or partial condensation by phase separation.

[0081] In these embodiments, the method typically includes removing H2 and any non-condensable gases from compressed impurity CO2 by partial condensation by distillation and / or phase separation to produce an H2S-enriched CO2 fluid (which may be liquid, gaseous, or two-phase) and an H2-enriched CO2 gas; recycling the H2-enriched CO2 gas, or any further H2-enriched CO2 gas derived therefrom, to a hydrogenation process as a second recycle gas; separating the H2S-enriched CO2 fluid by partial condensation by distillation and / or phase separation to produce purified CO2 as an overhead gas and an H2S-enriched bottom liquid; and vaporizing the H2S-enriched bottom liquid to produce an H2S-enriched gas as a first recycle gas. The second recycle gas, or a portion thereof, of the H2-enriched gas is typically purged in the process to avoid the accumulation of H2 (if there is an excess) or N2 and / or Ar.

[0082] As described above, suitable CO2 purification processes in this context are disclosed in US10254042 and US7819951, which the inventors recognize can be appropriately adapted for integration with the present invention.

[0083] In embodiments in which the purified CO2 contains at least one residual sulfur-containing impurity, the method may include further purifying the purified CO2 by selective adsorption or by chemical reaction with at least one solid metal oxide to form a solid metal sulfide, and then generating a further recycled gas containing further purified CO2 and at least one sulfur-containing compound by subsequent oxidative regeneration, and recycling the further recycled gas to the Krauss process to convert the sulfur-containing compound into elemental sulfur.

[0084] Alternatively, in embodiments in which the purified CO2 overhead gas contains one or more residual sulfur-containing compounds as impurities, the method may include removing H2S and any other sulfur-containing impurities from the purified CO2 overhead gas by selective adsorption or by forming solid metal sulfides by chemical reaction with at least one solid metal oxide, followed by oxidative regeneration, to produce a third recycled gas containing further purified CO2 and at least one sulfur-containing compound. The third recycled gas may be recycled to a Krauss process to convert the sulfur-containing compound into elemental sulfur.

[0085] A second aspect of the present invention is typically an apparatus for desulfurizing crude CO2 gas containing H2S and optionally at least one other sulfur-containing impurity, according to the method of the first aspect.

[0086] The apparatus comprises a Krauss unit for removing H2S from crude CO2 gas. The Krauss unit includes a first inlet for an oxidizing gas containing O2, a second inlet for crude CO2 gas, a first outlet for a Krauss-tail gas containing CO2, residual H2S, and at least one sulfur-containing impurity, and a second outlet for elemental sulfur. An example of a suitable Krauss unit is described in US2010 / 0126180A.

[0087] The apparatus also includes a source of an oxidizing gas containing O2, which is in fluid flow communication with the first inlet of the Krauss unit. In the case of a unit operating the "Air Krauss" process, the source may simply be a blower with a small filter, while in the case of a unit operating the "Oxy Krauss" process, the source may be a vacuum swing adsorption (VSA) unit or an air separation unit (ASU), which may optionally be combined with a backup system such as a liquid oxygen tank and vaporizer.

[0088] In addition, the apparatus includes a crude CO2 gas source that is in fluid flow communication with a second inlet of the Krauss unit. Such sources include a natural gas "sweetening" unit that generates an acidic gas flow using an amine absorption process / unit, a membrane separation system / unit, and / or a low-temperature purification process / unit.

[0089] The apparatus further comprises a hydrogenation unit for converting at least one sulfur-containing impurity in the Krauss tail gas to H2S. The hydrogenation unit comprises a first inlet in fluid flow communication with a first outlet of the Krauss unit, a second inlet for H2, and a first outlet for H2S-enriched CO2 tail gas. An example of a suitable hydrogenation unit is described in US2010 / 0126180A.

[0090] The apparatus also includes an H2 source that is in fluid flow communication with a second inlet of the hydrogenation unit. The source may be a unit that generates H2 as described above.

[0091] In addition, the apparatus includes a cooling unit for cooling the H2S-enriched CO2 tail gas, which is either separated from or integrated with the hydrogenation unit. The cooling unit comprises a first inlet in fluid communication with a first outlet of the hydrogenation unit, a first outlet for the cooled H2S-enriched CO2 tail gas, and a second outlet for condensate. The cooling unit may be a heat exchanger using indirect heat exchange with a coolant, but is typically a direct contact cooler including a second inlet for cooling water. The cooling unit may be a separate unit or may be integrated with the hydrogenation unit.

[0092] Furthermore, the apparatus includes a compression unit for compressing the H2S-enriched CO2 tail gas or impure CO2 gas containing the H2S derived therefrom. Therefore, the compression unit must be inherently suitable for processing "acidic" gases.

[0093] The compression unit comprises an inlet that is in fluid flow communication with the outlet of the first outlet of the cooling unit, and an outlet for the compressed impure CO2 gas. The compression unit may include one or more centrifugal or reciprocating compressors and / or a multistage compressor with associated intercoolers and aftercoolers. In particular, the compression unit may be an integrated gear or inline centrifugal compressor.

[0094] Furthermore, the apparatus includes a purification unit for removing H2S and any other sulfur-containing impurities from compressed impure CO2 gas by physical separation or chemical reaction with solid metal oxides. The purification unit includes a first inlet which is in fluid flow communication with the outlet of the compression unit, a first outlet for purified CO2, and a second outlet for a first recycled gas containing at least one sulfur-containing compound. The second outlet of the purification unit is in fluid flow communication with the Krauss unit. In this regard, the second outlet may be in fluid flow communication with a second inlet of the Krauss unit, or with a third inlet on the Krauss unit which is typically dedicated to recycled gas.

[0095] Throughout this specification, the term “fluid flow communication” is used to refer to different units (or parts of a unit, such as an inlet / outlet) that are appropriately connected by conduits, pipes, and / or ducts in such a manner that they allow for the flow of fluid, such as gas, between the units. This term is intended to include any associated flow control devices, such as sensors and / or valves, necessary to ensure control of the operation of the apparatus. Unless otherwise stated, this term is intended to encompass both direct and indirect fluid flow communication. “Direct” fluid (or gas) flow communication means that no other fluid (or gas) processing units (except flow control devices) are provided in the line between the units thus connected. “Indirect” fluid (or gas) flow communication should be interpreted accordingly, i.e., one or more other fluid (or gas) processing units are provided in the line between the units thus connected.

[0096] In some embodiments, the apparatus includes an H2 generation unit that includes a second inlet of a hydrogenation unit and an outlet for H2 that is in fluid communication with the hydrogenation unit.

[0097] In some embodiments, the purification unit is a selective adsorption unit comprising at least one container having an upstream and a downstream end, or comprising such or each container, an adsorbent bed comprising at least one layer of adsorbent material selective for sulfur-containing compounds, a first inlet for compressed impure CO2 gas at the upstream end of such or each container, a first outlet for purified CO2 at the downstream end of such or each container, a second inlet for regenerated gas at the downstream end of such or each container, and a second outlet for spent regenerated gas at the upstream end of such or each container. The first inlet is in fluid flow communication with the outlet of the compression unit, and the second outlet is in fluid flow communication with the Krauss unit. In this regard, the second outlet may be in fluid flow communication with a second inlet of the Krauss unit, or with a third inlet on the Krauss unit, which is typically dedicated to recycled gas.

[0098] In other embodiments, the purification unit includes a reactor comprising at least one vessel having an upstream and a downstream end. The vessel or each vessel comprises a bed comprising at least one solid metal oxide, a first inlet for compressed impure CO2 gas at the upstream end of the vessel or each vessel, a first outlet for purified CO2 at the downstream end of the vessel or each vessel, a second inlet for regenerated gas at the downstream end of the vessel or each vessel, and a second outlet for spent regenerated gas at the upstream end of the vessel or each vessel. The first inlet is in fluid flow communication with the outlet of a compression device, and the second outlet is in fluid flow communication with a Krauss unit. In this regard, the second outlet may be in fluid flow communication with a second inlet of the Krauss unit, or with a third inlet on the Krauss unit, which is typically dedicated to recycled gas.

[0099] The inventors acknowledge that a suitable example of a reactor that can be adapted for integration with these embodiments is disclosed in US4797268.

[0100] The floor of the selective adsorption unit or reactor, or within each of its containers, may each include at least one layer of water-selective adsorbent material downstream of at least one layer of adsorbent material selective for sulfur-containing compounds or solid metal oxides.

[0101] Alternatively, the purification unit may include a separate drying unit downstream of any of the selective adsorption units in the reactor. The drying unit may be an adsorption unit such as a further selective adsorption unit or a glycol unit. In any case, the drying unit typically comprises an inlet that is in fluid communication with the first outlet of the selective adsorption unit or reactor, and an outlet for the dried and purified CO2.

[0102] In some embodiments, the apparatus includes a selective amine absorption unit for recovering H2S from H2S-enriched CO2 tail gas. The selective amine absorption unit typically includes an inlet that is in fluid flow communication with a first outlet of a cooling unit, a first outlet for H2S-deficient CO2 tail gas, and a second outlet for recovered gas containing H2S that is in fluid flow communication with a Krauss unit. In this regard, the second outlet may be in fluid flow communication with a second inlet of the Krauss unit, or with a third inlet on the Krauss unit, which is typically dedicated to recycled gas. Examples of suitable selective amine absorption units that the inventors have found to be adaptable for use in this context are disclosed in WO93 / 10883A.

[0103] In some embodiments, the first outlet of the selective amine absorption unit is in direct fluid flow communication with the inlet of the compression unit.

[0104] In other embodiments, the apparatus may further include a non-selective amine absorption unit for recovering CO2 and residual H2S from H2S-deficient CO2 tail gas. The non-selective amine absorption unit typically comprises an inlet that is in fluid flow communication with a first outlet of a selective amine absorption unit, a first outlet for impure CO2 gas, and a second outlet for exhaust gas containing CO2 and at least one non-condensable gas. The apparatus usually comprises a thermal oxidizer having an exhaust port for the exhaust gas and optionally, an inlet that is in fluid flow communication with a second outlet of the non-selective amine absorption unit and an outlet for exhaust gas that is in fluid communication with the atmosphere via a vent.

[0105] In embodiments of the present invention where, even after passing through the selective adsorption unit or reactor described above, the content of sulfur-containing impurities in the purified CO2 gas still exceeds a required threshold, for example, 100 ppm, the apparatus may further include a further purification unit, such as a distillation unit and / or a phase separation unit (or CPU) for partial condensation, for further purifying the purified CO2.

[0106] In these embodiments, the further purification unit comprises an inlet for purified CO2 which is in fluid flow communication with a first outlet of the purification unit, a first outlet for further purified CO2, a second outlet for a second recycled gas containing CO2 and H2 which is in fluid flow communication with either the hydrogenation unit and / or the Krauss unit, and a purge line which is in fluid flow communication with the second outlet of the further purification unit.

[0107] In these and other embodiments involving the use of further purification units, the second outlet of the further purification unit may be in fluid flow communication with the first or second inlet of the hydrogenation unit, or with the third inlet of the hydrogenation unit, which is typically dedicated to recycled gas. The second outlet of the CPU may, additionally or alternatively, be in fluid communication with the first or second inlet of the Krauss unit, or with the third inlet on the Krauss unit, which is typically dedicated to recycled gas. Furthermore, the purge line may be in direct fluid communication with an exhaust port to the atmosphere or with a thermal oxidizer. Alternatively, the fluid from the purge line may be used as fuel or for H2 recovery.

[0108] The inventors acknowledge that the CPU shown in Figure 1B of US10254042 may be used (after suitable adaptation) as a further refinement unit of the present invention.

[0109] These embodiments may further include a membrane separation unit for recovering H2 gas from a second recycled gas. The membrane separation unit typically comprises an inlet for the second recycled gas, which is in fluid flow communication with a second outlet of a further purification unit; a first outlet for the H2-enriched gas, which is in direct fluid flow communication with a hydrogenation unit and / or a Krauss unit; and a second outlet for waste gas containing CO2 and at least one non-condensable gas.

[0110] These embodiments of the apparatus typically include an exhaust port for waste gas, along with a thermal oxidizer that has an inlet in fluid flow communication with a second outlet of the membrane separation unit and an outlet for exhaust gas in fluid communication with the exhaust port.

[0111] In addition, the second outlet of the membrane separation unit may be in fluid flow communication with the second inlet of the hydrogenation unit and / or Krauss unit, or with the third inlet of the hydrogenation unit and / or Krauss unit, which is typically dedicated to recycled gas. In this regard, any excess H2 that is not needed elsewhere can be supplied to the Krauss unit for combustion / disposal.

[0112] In other embodiments, the first outlet of the hydrogenation unit is in direct fluid flow communication with the inlet of the compression unit.

[0113] In these embodiments, the apparatus may include a further purification unit for further purifying the purified CO2. The further purification unit typically comprises an inlet for purified CO2 which is in fluid flow communication with a first outlet of the purification unit, a first outlet for further purified CO2 which is in fluid flow communication with a hydrogenation unit, a second outlet for a second recycled gas containing CO2 and H2, and a purge line which is in fluid flow communication with the second outlet of the further purification unit. The second outlet of the further purification unit may be in fluid flow communication with an inlet of a hydrogenation unit (and / or Krauss unit), or typically with an inlet of a hydrogenation unit (and / or Krauss unit) which is dedicated to recycled gas.

[0114] These embodiments may further include a membrane separation unit for recovering H2 gas from a second recycled gas. The membrane separation unit typically comprises an inlet for the second recycled gas, which is in fluid flow communication with a second outlet of a further purification unit; a first outlet for the H2-enriched gas, which is in direct fluid flow communication with a hydrogenation unit; and a second outlet for the waste gas, which contains CO2 and at least one non-condensable gas. The H2-enriched gas is typically removed from the permeate side of the membrane, and the waste gas is typically removed from the residue side of the membrane.

[0115] These embodiments of the apparatus typically include an exhaust port for waste gas, along with a thermal oxidizer that has an inlet in fluid flow communication with a second outlet of the membrane separation unit and an outlet for exhaust gas in fluid communication with the exhaust port.

[0116] In addition, the second outlet of the membrane separation unit may be in fluid flow communication with the second inlet of the hydrogenation unit and / or the Krauss unit, or with a third inlet on the hydrogenation unit and / or the Krauss unit, which is typically dedicated to recycled gas.

[0117] In some embodiments, the apparatus includes a non-selective amine absorption unit for recovering CO2 and H2S from H2S-enriched CO2 tail gas. The non-selective amine absorption unit includes an inlet that is in direct fluid flow communication with the outlet of a cooling unit, a first outlet for impure CO2 gas that is in direct fluid flow communication with the inlet of a compression unit, and a second outlet for waste gas containing CO2 and at least one non-condensable gas. These embodiments of the apparatus typically include an exhaust port for waste residue gas, along with a thermal oxidizer that has an inlet that is in fluid flow communication with the second outlet of a membrane separation unit and an outlet for exhaust gas that is in fluid flow communication with an exhaust port.

[0118] The purification unit may be a single-stage unit. In these embodiments, the purification unit comprises an inlet for compressed impure CO2 which is in fluid flow communication with the outlet of the compression unit, a first outlet for H2S-enriched CO2 fluid, and a second outlet for H2-enriched CO2 gas which is in fluid flow communication with the inlet of the hydrogenation unit (and / or the inlet of the Krauss unit).

[0119] In these embodiments, the apparatus may further include a selective adsorption unit comprising at least one container having an upstream and a downstream end, the container or each container comprising an adsorbent bed, the adsorbent bed comprising at least one layer of an adsorbent material selective for sulfur-containing compounds, a first inlet for H2S-enriched CO2 fluid located at the upstream end of the container or each container, a first outlet for purified CO2 located at the downstream end of the container or each container, a second inlet for regenerated gas located at the downstream end of the container or each container, and a second outlet for spent regenerated gas located at the upstream end of the container or each container. The first inlet of the selective adsorption container is in fluid flow communication with a first outlet of a single-stage purification unit, and the second outlet is in fluid flow communication with a Krauss unit.

[0120] Alternatively, the apparatus may comprise a reactor including at least one vessel having an upstream and a downstream end, wherein each vessel has a bed containing at least one solid metal oxide, and comprises a first inlet for H2S-enriched CO2 fluid at the upstream end of the vessel, a first outlet for purified CO2 at the downstream end of the vessel, a second inlet for regenerated gas at the downstream end of the vessel, and a second outlet for spent regenerated gas at the upstream end of the vessel. The first inlet of the reactor is in fluid flow communication with a first outlet of a single-stage purification unit, and the second outlet is in fluid flow communication with a Krauss unit.

[0121] In further embodiments of the apparatus, the purification unit includes a first stage, for example, a CPU, and a second stage, for example, a distillation unit.

[0122] The first stage comprises an inlet for compressed impure CO2, which is in fluid flow communication with the outlet of a compression unit; a first outlet for H2S-enriched CO2 fluid; and a second outlet for H2-enriched CO2 gas, which is in fluid flow communication with the inlet of a hydrogenation unit (and / or the inlet of a Krauss unit).

[0123] The second stage comprises an inlet for an H2S-enriched CO2 fluid, which is in fluid flow communication with a first outlet of the first stage; a first outlet for purified CO2 gas; and a second outlet for the H2S-enriched gas, which is in fluid flow communication with a third inlet of the Krauss unit. These embodiments of the apparatus further include a purge line, which is in fluid flow communication with a second outlet of the first stage of the purification unit.

[0124] The inventors acknowledge that Figure 2 of US10254042 depicts an integrated configuration of first and second steps that would be suitable for use as a purification unit according to these embodiments of the present invention.

[0125] These embodiments may further include a membrane separation unit for recovering H2 gas from H2-enriched CO2 gas. The membrane separation unit typically comprises an inlet for H2-enriched CO2 gas which is in fluid flow communication with a second outlet of a first stage of a purification unit; a first outlet for H2-enriched gas which is in direct fluid flow communication with an inlet of a hydrogenation unit (and / or an inlet of a Krauss unit); and a second outlet for waste gas containing CO2 and at least one non-condensable gas.

[0126] These embodiments of the apparatus typically include an exhaust port for waste gas, along with a thermal oxidizer that has an inlet in fluid flow communication with a second outlet of the membrane separation unit and an outlet for exhaust gas in fluid communication with the exhaust port.

[0127] In addition, the second outlet of the membrane separation unit may be in fluid flow communication with the second inlet of the hydrogenation unit and / or the Krauss unit, or with a third inlet on the hydrogenation unit and / or the Krauss unit, which is typically dedicated to recycled gas.

[0128] If the amount of sulfur-containing components in the purified CO2 gas still exceeds a required threshold, for example, 100 ppm, these embodiments may further include a further purification unit selected from a reactor comprising a selective adsorption unit and a bed of solid metal oxides as described above.

[0129] In this context, a selective adsorption unit typically comprises at least one vessel having an upstream and a downstream end. The vessel or each vessel comprises an adsorbent bed containing at least one layer of adsorbent material selective for sulfur-containing compounds, a first inlet for purified CO2 at the upstream end of the vessel or each vessel, a first outlet for further purified CO2 at the downstream end of the vessel or each vessel, a second inlet for regenerated gas at the downstream end of the vessel or each vessel, and a second outlet for spent regenerated gas at the upstream end of the vessel or each vessel. In these embodiments, the first inlet of the further purification unit is in fluid flow communication with the first outlet of a second stage of the purification unit, and the second outlet is in fluid flow communication with a Krauss unit. In this regard, the second outlet of the vessel or each vessel may be in fluid flow communication with the second inlet of the Krauss unit, or with a third inlet on the Krauss unit, which is typically dedicated to recycled gas.

[0130] In this context, a reactor unit typically comprises at least one vessel having an upstream and a downstream end. The vessel or each vessel comprises a bed containing at least one solid metal oxide, a first inlet for compressed impure CO2 gas at the upstream end of the vessel or each vessel, a first outlet for purified CO2 at the downstream end of the vessel or each vessel, a second inlet for regenerated gas at the downstream end of the vessel or each vessel, and a second outlet for spent regenerated gas at the upstream end of the vessel or each vessel. In addition, the first inlet of a further purification unit is in fluid flow communication with the first outlet of a second stage of the purification unit, and the second outlet is in fluid flow communication with a Krauss unit. In this regard, the second outlet of the vessel or each vessel may be in fluid flow communication with the second inlet of the Krauss unit, or with a third inlet on the Krauss unit, which is typically dedicated to recycled gas.

[0131] Referring to Figure 1, a stream of crude CO2 gas containing H2S, 100, is taken from the acid gas recovery unit 4 and supplied to the Krauss unit 6, where the H2S is converted into a stream of elemental sulfur, 102. Using a quasi-stoichiometric amount of oxygen from the air stream 101, sufficient H2S in the crude CO2 gas feed is oxidized and reacted to produce a mixture of H2S and SO2 in appropriate proportions, thereby generating elemental sulfur. Depending on the type of Krauss process, the Krauss unit 6 typically converts 92 mol% to 99.5 mol% of the H2S in the crude CO2 gas feed into elemental sulfur. The residual sulfur compounds exit the Krauss unit 6 in a stream of Krauss tail gas containing CO2, 103, which is supplied to a tail gas treatment unit 14, which includes a hydrogenation unit 16 and a selective amine absorption unit 20.

[0132] Residual sulfur compounds are converted to H2S in the hydrogenation unit 16 in the presence of H2 gas produced in the reducing gas generation unit 18, generating an H2S-enriched CO2 tail gas flow 104, which is quenched with water in a direct contact cooler (shown as being integrated with the hydrogenation unit - see the (water) flow leaving the hydrogenation unit 16) and then supplied to a selective amine absorption unit 20, which selectively absorbs H2S to generate an H2S-deficient CO2 tail gas flow 105, recovering H2S which is recycled to the Krauss unit 6 as part of the flow 110. The H2S-deficient CO2 tail gas from the tail gas processing unit 14 mainly contains CO2, N2, H2 and small amounts of sulfur compounds and is saturated with water.

[0133] In the absence of a CO2 capture unit, flow 105 is typically oxidized in a thermal oxidizer. However, in this case, the CO2 is intended for capture and storage.

[0134] The H2S-deficient CO2 tail gas 105 from the tail gas treatment unit 14 is supplied to the non-selective amine absorption unit 26, where most of the CO2 and sulfur compounds are non-selectively captured and recovered, and depending on their composition, are either directly exhausted before being exhausted or supplied to the thermal oxidizer 42 with water to create a stream of impure CO2 gas 107, along with a stream of waste gas 115 containing CO2 and non-condensable gases, N2 and H2.

[0135] Flow 107 is primarily CO2 but contains sulfur compounds that may be unacceptable for CO2 sequestration or further use. Therefore, flow 107 is fed to a compression device 32, where it is compressed to form a stream 108 of compressed impure CO2 gas, which is then purified using a selective adsorption unit (or reactor) 36 according to the present invention to remove sulfur compounds and produce a stream 109 of spent regenerated gas (or purge gas) containing purified CO2 flow 111 for sequestration and desorbed sulfur compounds that are recycled to the Krauss unit 6.

[0136] Water can be removed from the compressed impure CO2 gas in the selective adsorption unit (or reactor) 36 by including at least one layer of water adsorbent material downstream of a layer of sulfur-selective adsorbent material or a solid metal oxide, such as ZnO. Alternatively, the purified CO2 stream 111 may be supplied to a drying unit (not shown) before isolation.

[0137] The flowsheet depicted in Figure 2 is a replacement for the flowsheet depicted in Figure 1. Unless otherwise indicated, common features between the two flowsheets are given the same reference number. The following is a discussion of the features that distinguish Figure 1 from Figure 2.

[0138] Instead of the air used in Figure 1, the process in Figure 2 uses a stream of O2 or O2-enriched air 101 as an oxidizing agent supplied to the Krauss unit 6, converting the amount of H2S necessary for the Krauss reaction to produce elemental sulfur into SO2.

[0139] In addition, the H2S-deficient CO2 tail gas flow 105 is taken out of the tail gas treatment unit 14 and supplied directly to the compression device 46, where it is compressed. Water is removed from the compressed gas in one or more intercoolers and / or aftercoolers (not shown). The compressed impure CO2 gas flow 106 is then purified using the selective adsorption unit (or reactor) 50 according to the present invention to remove sulfur-containing compounds, generating a purified CO2 gas flow 107 and a spent regenerated gas (or purge gas) flow 109 containing sulfur-containing compounds that are recycled to the Krauss unit 6.

[0140] Water can be removed from the compressed impure CO2 gas in the selective adsorption unit (or reactor) 50 by including at least one layer of water adsorbent material downstream of a layer of sulfur-selective adsorbent material or a solid metal oxide, such as ZnO. Alternatively, the purified CO2 stream 111 may be supplied to a drying unit (not shown) before isolation.

[0141] Next, the purified CO2 gas stream 107 is supplied to a further purification unit 56, where the CO2 is further purified by distillation and / or partial condensation and phase separation to produce a further purified CO2 stream 111 for sequestration or other use, and a waste gas stream 108 containing CO2 and H2.

[0142] Flow 108 can be directly recycled to the hydrogenation unit 16. However, it may be desirable to reduce the amount of CO2 recycled to the hydrogenation unit 16. In such cases, flow 108 can be supplied to the membrane unit 62 for H2 recovery to generate an H2-enriched gas flow 112 and a waste gas flow 115.

[0143] Flow 112 is recycled to the hydrogenation unit 16. Recycling this flow in this manner has the advantage of reducing, or even eliminating, the need for fresh H2 from a reducing gas generation unit (not shown) to supply to the hydrogenation unit 16.

[0144] Depending on its composition, the exhaust gas flow 115 may be directly exhausted or supplied to the thermal oxidizer 70 before being exhausted.

[0145] The flowsheet depicted in Figure 3 is a modified version of the flowsheet depicted in Figure 1, without the selective amine absorption unit 20. Unless otherwise indicated, common features between the two flowsheets are given the same reference numbers. The following is a discussion of the features that distinguish Figure 1 from Figure 3.

[0146] The H2S-enriched CO2 tail gas stream 104 is supplied directly from the hydrogenation unit 16 to the non-selective amine absorption unit 26, where most of the CO2 and sulfur-containing compounds are non-selectively captured and recovered, and, depending on their composition, are either directly exhausted before being exhausted or supplied to the thermal oxidizer 42, along with the waste gas stream 115, to generate an impure CO2 gas stream 107.

[0147] The flowsheet depicted in Figure 4 is a modified version of the flowsheet depicted in Figure 2, without the selective amine absorption unit 20. Unless otherwise indicated, common features between the two flowsheets are given the same reference numbers. The following is a discussion of the features that distinguish Figure 2 from Figure 4.

[0148] In this configuration, the flow of O2 or O2-enriched air 101 for the Krauss unit 6 is generated within the air separation unit 72 by either vacuum swing adsorption (VSA) or cryogenic air separation (air separation unit or ASU).

[0149] The flow of impure CO2 tail gas 104 is supplied directly from the hydrogenation unit 16 to the compression device 46, where it is compressed to form a compressed flow of impure CO2 gas 106, which is then supplied to the selective adsorption unit (or reactor) 50, where H2S (optionally, along with water) is removed from the gas.

[0150] In this configuration, sufficient H2 may be recovered within the membrane separation unit 62 and recycled to the hydrogenator 16 so that a reducing gas generator (not shown) does not need to provide additional H2.

[0151] The flowsheet depicted in Figure 5 is a modified version of the flowsheet depicted in Figure 4, including a selective adsorption unit (or reactor) for further purification of CO2 by the purification unit. Unless otherwise indicated, common features between the two flowsheets are given the same reference numbers. The following is a discussion of the features that distinguish Figure 4 from Figure 5.

[0152] The purification unit has a first stage and a second stage. In the first stage, a stream 106 of compressed impure CO2 gas is supplied to the first stage 56, where the CO2 is purified, for example, by partial condensation by phase separation to produce H2S-enriched CO2 liquid. The waste gas stream 108 containing CO2 and H2 optionally passes through a membrane separation unit 62 to recover H2, and is then recycled to a hydrogenation unit 16.

[0153] A stream 107 of H2S-enriched CO2 liquid (or gas if vaporized) is supplied to the distillation column system 74, where CO2 and H2S are separated in a second stage to produce purified CO2 as an overhead gas and vaporized H2S-enriched bottom liquid before being recycled to the Krauss unit 6 of stream 110.

[0154] The purified CO2 stream 111 may be suitable for sequestration. However, if the total amount of sulfur-containing compounds in the purified CO2 is too high, for example, more than 100 ppm, the purified CO2 may be further purified in the selective adsorption unit (or reactor) 50 to produce a stream 120 of further purified CO2 for sequestration or further use, and a stream 118 of spent regenerated gas (or purge gas) containing desorbed sulfur-containing compounds that is recycled to the Krauss unit 6.

[0155] The flow sheets depicted in Figures 2, 4, and 5 all include a membrane separation unit 62 for recovering H2 from the waste gas generated in the purification unit. In these embodiments, the purge flow may be taken from the recycle flow 112 to control the accumulation of H2 (if in excess) or N2 and / or Ar during the process.

[0156] The flow sheet depicted in Figure 6 is a modified version of the flow sheet depicted in Figure 5, and the purification unit includes a single step, and the CO2 may be further purified using a selective adsorption unit (or reactor). Unless otherwise indicated, common features between the two flow sheets are given the same reference number. The following is a discussion of the features that distinguish Figure 5 from Figure 6.

[0157] The purification unit has a single stage (unit 56). A stream 106 of compressed impure CO2 gas is supplied to unit 56, where the CO2 is purified, for example, by partial condensation by phase separation or by distillation to produce H2S-enriched CO2 liquid. A stream 108 of waste gas containing CO2 and H2 optionally passes through a membrane separation unit 62 to recover H2, and is then recycled to a hydrogenation unit 16.

[0158] The level of sulfur-containing compounds in the H2S-enriched CO2 gas flow 107 is typically above 2 mol%, which is too high for CCS. However, instead of purifying the CO2 by distillation (as shown in Figure 5), the flow may be supplied from unit 56 to the selective adsorption unit (or reactor) 50 to produce a stream 111 of purified CO2 for sequestration or further use, and a stream 110 of spent regenerated gas (or purge gas) containing desorbed sulfur-containing compounds that are recycled to the Krauss unit 6.

[0159] The flow sheet in Figure 7 illustrates how the SUPERCLAUS process and / or EUROCLAUS process (unit 6*) can be integrated with the tail gas treatment process depicted in Figures 1-5. In this regard, unit 26** represents the “CCS block,” which includes a specific combination of selective amine absorption units, non-selective amine absorption units, compression units, selective adsorption units, reactor units, membrane separation units, and / or purification units, as depicted in one of Figures 1-5. The H2S-containing recycled stream is fed to the Claus unit 6*, the purified CO2 is removed as stream 111, and the waste gas is sent to the thermal oxidizer unit 42 via stream 115.

[0160] Embodiments of the Invention Embodiment 1: A method for desulfurizing crude CO2 gas containing H2S and optionally at least one other sulfur-containing impurity, Crude CO2 gas containing H2S is supplied to the Krauss process to convert H2S into elemental sulfur in the presence of oxygen (O2) gas, producing Krauss-tail gas containing CO2, residual H2S, and at least one other sulfur-containing impurity. The klaus tail gas is supplied to a hydrogenation process to convert at least one other sulfur-containing impurity into H2S in the presence of H2, thereby producing an H2S-enriched CO2 tail gas. The H2S-enriched CO2 tail gas is cooled, condensed water is removed, and cooled H2S-enriched CO2 tail gas is produced. Compressing the cooled H2S-enriched CO2 tail gas, or the H2S-containing impure CO2 gas derived therefrom, to produce compressed impure CO2 gas containing H2S, By physical separation or by chemical reaction with at least one solid metal sulfide, and then by oxidative regeneration, H2S and any other sulfur-containing impurities are removed from the compressed impure CO2 gas to produce a first recycled gas containing purified CO2 and at least one sulfur-containing compound. A method comprising recycling the first recycled gas to the Krauss process to convert the at least one sulfur-containing compound into elemental sulfur.

[0161] Appearance 2: The process of generating H2 in the hydrogen production process, The method according to embodiment 1, comprising supplying the H2 to the hydrogenation process.

[0162] Embodiment 3: The method according to Embodiment 1 or 2, wherein the H2S-enriched CO2 tail gas is cooled by bringing it into direct contact with water.

[0163] Embodiment 4: The method according to any one of #1 to #3, wherein the physical separation involves removing H2S and any other sulfur-containing impurities from the compressed impure CO2 gas by selective adsorption.

[0164] Embodiment 5: The method according to Embodiment 4, wherein the selective adsorption removes H2S and any other sulfur-containing compounds from compressed impure CO2 gas by adsorption on a floor containing at least one adsorbent material selective for sulfur-containing compounds in a selective adsorption unit, thereby producing purified CO2, which is then desorbed with regenerated gas, and the used regenerated gas containing H2S and any other sulfur-containing compounds from the compressed impure CO2 gas is produced as the first recycled gas.

[0165] Embodiment 6: The method according to Embodiment 5, wherein the regenerated gas contains an amount of water insufficient to hydrolyze other sulfur-containing compounds.

[0166] Embodiment 7: The method according to Embodiment 5 or 6, wherein the compressed impure CO2 gas supply to the selective adsorption unit contains water, and the method comprises drying the purified CO2 gas downstream of the adsorbent material which is selective for sulfur-containing compounds.

[0167] Embodiment 8: The method according to Embodiments 1 to 3, wherein H2S and any other sulfur-containing impurities are removed from the compressed impure CO2 gas by the chemical reaction with at least one solid metal oxide, a solid metal sulfide is formed, and then oxidatively regenerated.

[0168] Appearance 9: The compressed impure CO2 gas is passed through a bed containing at least one solid metal oxide in the reactor to convert the metal oxide into a metal sulfide, thereby producing the purified CO2. The method according to embodiment 8, comprising: regenerating a floor using a regenerated gas containing O2 to generate a spent regenerated gas containing SO2 as the first recycled gas.

[0169] Embodiment 10: The method according to Embodiment 9, wherein the regenerated gas contains an amount of water insufficient to hydrolyze other sulfur-containing compounds.

[0170] Embodiment 11: The method according to Embodiment 9 or 10, wherein the compressed impure CO2 gas supply to the reactor contains water, and the method comprises drying the purified CO2 gas downstream of the bed containing the solid metal oxide.

[0171] Appearance 12: By selective amine absorption, H2S is recovered from the H2S-enriched CO2 tail gas to produce H2S-deficient CO2 tail gas and recovered H2S. The method according to any one of embodiments 1 to 11, comprising recycling the recovered H2S into the Krauss process to convert the recovered H2S into elemental sulfur.

[0172] Embodiment 13: The method according to Embodiment 12, comprising recovering CO2 and residual H2S from the H2S-deficient CO2 tail gas by non-selective amine absorption to produce the impure CO2 gas for compression together with waste gas containing CO2 and at least one non-condensable gas.

[0173] Embodiment 14: The method according to Embodiment 12, wherein the H2S-deficient CO2 tail gas is directly compressed to produce the compressed impure CO2 gas.

[0174] Appearance 15: The purified CO2 is then supplied to a further purification process to produce even more purified CO2 and a second recycled gas containing CO2 and H2. This includes recycling the second recycled gas, or the H2-enriched gas derived therefrom, into the hydrogenation process, The method according to aspect 14, wherein a portion of the second recycled gas, or a portion of the H2-enriched gas derived therefrom, is purged.

[0175] Embodiment 16: The method according to Embodiment 15, wherein the amount of H2 recycled in the hydrogenation process is sufficient to meet the demand in the process.

[0176] Embodiment 17: The method according to Embodiment 15 or 16, comprising recovering H2 gas from the second recycled gas in a membrane separation process and generating the H2-enriched gas together with waste gas containing CO2 and at least one non-condensable gas.

[0177] Embodiment 18: The method according to any one of Embodiments 1 to 3, wherein the H2S-enriched CO2 tail gas is directly compressed to produce the compressed impure CO2 gas containing H2S.

[0178] Appearance 19: The purified CO2 is then supplied to a further purification process to produce even more purified CO2 and a second recycled gas containing CO2 and H2. This includes recycling the second recycled gas, or the H2-enriched gas derived therefrom, into the hydrogenation process, The method according to any one of embodiments 1 to 18, wherein a portion of the second recycled gas, or a portion of the H2-enriched gas derived therefrom, is purged.

[0179] Embodiment 20: The method according to Embodiment 19, wherein the amount of H2 recycled in the hydrogenation process is sufficient to meet the demand in the process.

[0180] Embodiment 21: The method according to Embodiment 19 or 20, comprising recovering H2 gas from the second recycled gas in a membrane separation process and generating the H2-enriched gas for recycling together with the waste gas containing CO2 and at least one non-condensable gas.

[0181] Embodiment 22: The method according to any one of Embodiments 1 to 3, comprising recovering CO2 and residual H2S from the H2S-enriched CO2 tail gas by non-selective amine absorption to produce the impure CO2 gas for compression together with waste gas containing CO2 and at least one non-condensable gas.

[0182] Embodiment 23: The method according to Embodiments 1 to 3, wherein the H2S and any other sulfur-containing impurities are removed from the compressed impure CO2 gas by partial condensation by distillation and / or phase separation as the aforementioned physical separation.

[0183] Embodiment 24: The purified CO2 contains at least one residual sulfur-containing impurity, and the method is The purified CO2 is further purified by selective adsorption or chemical reaction with at least one solid metal oxide to form a solid metal sulfide, and then oxidatively regenerated to produce a further recycled gas containing further purified CO2 and at least one sulfur-containing compound. The method according to embodiment 23, further comprising recycling the further recycled gas to the Krauss process to convert the sulfur-containing compound into elemental sulfur.

[0184] Appearance 25: The process involves removing H2 and any other non-condensable gases from the compressed impure CO2 gas by distillation and / or partial condensation by phase separation to produce an H2S-enriched CO2 fluid and an H2-enriched CO2 gas. The H2-enriched CO2 gas, or any further H2-enriched CO2 gas derived therefrom, is recycled as a second recycled gas for the hydrogenation process. The H2S-enriched CO2 fluid is separated by partial condensation through distillation and / or phase separation, and the purified CO2 is produced as overhead gas and H2S-enriched bottom liquid. This includes vaporizing the H2S-enriched bottom liquid to produce an H2S-enriched gas as the first recycled gas, The method according to aspect 24, wherein a portion of the second recycled gas, or a portion of the H2-enriched gas derived therefrom, is purged.

[0185] Embodiment 26: The method according to Embodiment 25, wherein the amount of H2 recycled in the hydrogenation process is sufficient to meet the demand in the process.

[0186] Embodiment 27: The method according to Embodiment 25 or 26, comprising recovering H2 gas from the second recycled gas in a membrane separation process and generating the further H2-enriched CO2 gas for recycling together with the waste gas containing CO2 and at least one non-condensable gas.

[0187] Embodiment 28: The purified CO2 overhead gas contains one or more residual sulfur-containing compounds, and the method is The method according to aspects 26 to 28, comprising: removing H2S and any other sulfur-containing impurities from the purified CO2 overhead gas by selective adsorption or by chemical reaction with at least one solid metal oxide to form a solid metal sulfide and subsequent oxidative regeneration to produce a third recycled gas containing further purified CO2 and at least one sulfur-containing compound; and recycling the third recycled gas to the Krauss process to convert the sulfur-containing compound into elemental sulfur.

[0188] Embodiment 29: Apparatus for desulfurizing crude CO2 gas containing H2S and optionally at least one other sulfur-containing impurity, A Krauss unit for removing H2S from crude CO2 gas, A first inlet for the oxidizing gas containing O2, A second inlet for the crude CO2 gas, A first outlet for Claustail gas containing CO2, residual H2S, and at least one other sulfur-containing impurity, A Krauss unit having a second outlet for elemental sulfur, A source of oxidizing gas containing O2 is in fluid flow communication with the first inlet of the Krauss unit, The crude CO2 source is in fluid flow communication with the second inlet of the Krauss unit, A hydrogenation unit for converting at least one other sulfur-containing impurity in the Claustail gas into H2S, The first inlet of the Krauss unit is in fluid flow communication with the first inlet, A second entrance for H2, A hydrogenation unit comprising a first outlet for H2S-enriched CO2 tail gas, The H2 supply source is in fluid flow communication with the second inlet of the hydrogenation unit, A cooling unit for cooling H2S-enriched CO2 tail gas, The first outlet of the hydrogenation unit and the first inlet that is in fluid communication with it, A first outlet for cooled H2S-enriched CO2 tail gas, A cooling unit comprising a second outlet for condensed water, A compression unit for compressing cooled H2S-enriched CO2 tail gas, or impure CO2 gas containing H2S derived therefrom, wherein the compression device is The first outlet of the cooling unit and the inlet which is in fluid flow communication, A compression unit having an outlet for compressed impure CO2 gas, A purification unit for removing H2S and any other sulfur-containing impurities from compressed impure CO2 gas by physical separation or by forming a solid metal sulfide through a chemical reaction with at least one metal oxide, and then oxidative regeneration, The first inlet of the Krauss unit is in fluid flow communication with the first inlet, First outlet for purified CO2, A second outlet for a first recycled gas containing at least one sulfur-containing compound, An apparatus comprising a purification unit, the second outlet of which the purification unit is in fluid communication with the Krauss unit.

[0189] Embodiment 30: The apparatus according to Embodiment 29, wherein the H2 supply source is an H2 generating unit having an outlet for H2 that is in fluid communication with the second inlet of the hydrogenation unit.

[0190] Embodiment 31: The apparatus according to Embodiment 29 or 30, wherein the cooling unit is a direct contact cooler further comprising a second inlet for cooling water.

[0191] Embodiment 32: The purification unit is a selective adsorption unit, At least one container having an upstream end and a downstream end, wherein the or each of the containers is An adsorbent bed comprising at least one layer of an adsorbent material selective for sulfur-containing compounds, A first inlet for compressed impure CO2 gas located at the upstream end of the container or each container, A first outlet for purified CO2 located at the downstream end of the container or each container, A second inlet for regenerating gas located at the said or the said downstream end of each container, A selective adsorption unit comprising at least one container, which includes a second outlet for spent regenerated gas located at the upstream end of the said or each container, The apparatus according to embodiment 29, wherein the first inlet of the selective adsorption unit is in fluid flow communication with the outlet of the compression unit, and the second outlet is in fluid flow communication with the Krauss unit.

[0192] Embodiment 33: The apparatus according to Embodiment 32, wherein the adsorbent bed in the container or in each container comprises, downstream of at least one layer of adsorbent material selective for water, the adsorbent bed in the container or in each container comprises

[0193] Embodiment 34: A drying unit downstream of the selective adsorption unit, The first outlet of the selective adsorption unit and the inlet which is in fluid flow communication, The apparatus according to embodiment 33 or 34, comprising a dryer unit having an outlet for dried and purified CO2, which is in fluid flow communication with the inlet of the compression unit.

[0194] Embodiment 35: The purification unit is a reactor, At least one container having an upstream end and a downstream end, wherein the or each of the containers is A floor containing at least one solid metal oxide, A first inlet for compressed impure CO2 gas located at the upstream end of the container or each container, A first outlet for purified CO2 located at the downstream end of the container or each container, A second inlet for regenerating gas located at the said or the said downstream end of each container, A reactor comprising at least one container, which includes a second outlet for spent regenerated gas located at the upstream end of the said or each container, The apparatus according to embodiment 29, wherein the first inlet of the reactor is in fluid flow communication with the outlet of the compression device, and the second outlet is in fluid flow communication with the Krauss unit.

[0195] Apparatus 36: The apparatus according to Apparatus 35, wherein the or each container comprises at least one layer of water-selective adsorbent material downstream of the floor containing the solid metal oxide.

[0196] Embodiment 37: A drying unit downstream of the reactor, The first outlet of the reactor and the inlet that is in fluid communication with it, The apparatus according to embodiment 35 or 36, comprising a drying unit having an outlet for dried and purified CO2 which is in fluid flow communication with the compression unit.

[0197] Appearance 38: A selective amine absorption unit for recovering H2S from H2S-enriched CO2 tail gas, The cooling unit has a first outlet and an inlet that is in fluid flow communication with it, and the compression unit has a first outlet for H2S-deficient CO2 tail gas that is in fluid flow communication with it, The apparatus according to any one of embodiments 29 to 37, comprising a selective amine absorption unit having a second outlet for recovered H2S, which is in fluid flow communication with the Krauss unit.

[0198] Appearance 39: A non-selective amine absorption unit for recovering CO2 and residual H2S from H2S-deficient CO2 tail gas, The first outlet of the selective amine absorption unit and the inlet, which is in fluid flow communication with it, The first outlet for impure CO2 gas is in direct fluid flow communication with the inlet of the compression unit, The apparatus according to embodiment 38, comprising a non-selective amine absorption unit, and a second outlet for exhaust gas containing CO2 and at least one non-condensable gas.

[0199] Embodiment 40: The apparatus according to Embodiment 38, wherein the first outlet of the selective amine absorption unit is in direct fluid flow communication with the inlet of the compression unit.

[0200] Embodiment 41: The purification unit is a selective adsorption unit or reactor, and the apparatus is A further purification unit for further purifying purified CO2, The selective adsorption unit or the first outlet of the reactor and the inlet for purified CO2, which is in fluid flow communication with the first outlet, Furthermore, a first outlet for purified CO2, A further purification unit comprising a second outlet for a second recycled gas containing CO2 and H2, which is in fluid flow communication with the hydrogenation unit, The apparatus according to embodiment 40, further comprising a purge line in fluid flow communication with a second outlet of the further purification unit.

[0201] Appearance 42: A membrane separation unit for recovering H2 gas from a second recycled gas, The second outlet of the further purification unit and the inlet for the second recycled gas, which is in fluid flow communication with it, A first outlet for H2-enriched gas that is in direct fluid flow communication with the hydrogenation unit, The apparatus according to embodiment 41, comprising a membrane separation unit, the second outlet for exhaust gas containing CO2 and at least one non-condensable gas.

[0202] Embodiment 43: The apparatus according to any one of Embodiments 29 to 31, wherein the first outlet of the hydrogenation unit is in direct fluid flow communication with the inlet of the compression unit.

[0203] Embodiment 44: The purification unit is a selective adsorption unit or reactor, and the apparatus is A further purification unit for further purifying purified CO2, The selective adsorption unit or the first outlet of the reactor and the inlet for purified CO2, which is in fluid flow communication with the first outlet, Furthermore, a first outlet for purified CO2, A further purification unit comprising a second outlet for a second recycled gas containing CO2 and H2, which is in fluid flow communication with the hydrogenation unit, The apparatus according to embodiment 43, further comprising a purge line that is in fluid flow communication with a second outlet of the further purification unit.

[0204] Appearance 45: A membrane separation unit for recovering H2 gas from a second recycled gas, The second outlet of the further purification unit and the inlet for the second recycled gas, which is in fluid flow communication with it, A first outlet for H2-enriched permeate gas that is in direct fluid flow communication with the hydrogenation unit, The apparatus according to embodiment 44, comprising a membrane separation unit, the second outlet for waste residue gas containing CO2 and at least one non-condensable gas.

[0205] Appearance 46: A non-selective amine absorption unit for recovering CO2 and residual H2S from H2S-enriched CO2 tail gas, The outlet of the cooling unit and the inlet that is in direct fluid flow communication with it, The first outlet for impure CO2 gas is in direct fluid flow communication with the inlet of the compression unit, The apparatus according to any one of embodiments 29 to 31, comprising a non-selective amine absorption unit, and a second outlet for exhaust gas containing CO2 and at least one non-condensable gas.

[0206] Embodiment 47: The purification unit is a single-step purification unit, The outlet of the compression unit and the inlet for compressed impure CO2, which is in fluid flow communication with it, First outlet for H2S-enriched CO2 fluid, A single-stage hydrogenation unit comprising an inlet and a second outlet for H2-enriched CO2 gas, which is in fluid flow communication with the hydrogenation unit, The device is a selective adsorption unit, At least one container having an upstream end and a downstream end, wherein the or each of the containers is An adsorbent bed comprising at least one layer of an adsorbent material selective for sulfur-containing compounds, A first inlet for the H2S-enriched CO2 fluid located at the upstream end of the said or each container, A first outlet for purified CO2 located at the downstream end of the container or each container, A second inlet for regenerating gas located at the said or the said downstream end of each container, A selective adsorption unit comprising at least one container, which includes a second outlet for spent regenerated gas located at the upstream end of the said or each container, The apparatus according to any one of embodiments 29 to 31, wherein the first inlet of the selective adsorption vessel is in fluid flow communication with the first outlet of the single-step purification unit, and the second outlet is in fluid flow communication with the Krauss unit.

[0207] Embodiment 48: The purification unit is a single-step purification unit, The outlet of the compression unit and the inlet for compressed impure CO2, which is in fluid flow communication with it, First outlet for H2S-enriched CO2 fluid, This is a single-stage purification unit comprising an inlet for the hydrogenation unit and a second outlet for H2-enriched CO2 gas that is in fluid flow communication with the inlet of the hydrogenation unit, The apparatus is a reactor, At least one container having an upstream end and a downstream end, wherein the or each of the containers is A floor containing at least one solid metal oxide, A first inlet for the H2S-enriched CO2 fluid located at the upstream end of the said or each container, A first outlet for purified CO2 located at the downstream end of the container or each container, A second inlet for regenerating gas located at the said or the said downstream end of each container, A reactor comprising at least one container, which includes a second outlet for spent regenerated gas located at the upstream end of the said or each container, The apparatus according to any one of embodiments 29 to 31, wherein the first inlet of the reactor is in fluid flow communication with the first outlet of the single-stage purification unit, and the second outlet is in fluid flow communication with the Krauss unit.

[0208] Embodiment 49: The purification unit is in the first step, The first stage is, The outlet of the compression unit and the inlet for compressed impure CO2, which is in fluid flow communication with it, First outlet for H2S-enriched CO2 fluid, A first stage comprising an inlet of the hydrogenation unit and a second outlet for H2-enriched CO2 gas in fluid flow communication, The second stage, and the said second stage is The first outlet of the first stage is in fluid flow communication with the inlet for the H2S-enriched CO2 fluid, First outlet for purified CO2 gas, A second outlet for H2S enriched gas, which is in fluid flow communication with the Krauss unit, The apparatus according to any one of embodiments 29 to 31, comprising a purification unit, a second stage comprising a purge line having fluid flow communication with the second outlet of the first stage of the purification unit.

[0209] Appearance 50: A membrane separation unit for recovering H2 gas from H2-enriched CO2 gas, The inlet for H2-enriched CO2 gas is in fluid flow communication with the second outlet of the first stage of the purification unit, A first outlet for H2-enriched permeate gas that is in direct fluid flow communication with the hydrogenation unit, The apparatus according to embodiment 49, comprising a membrane separation unit, the second outlet for waste residue gas containing CO2 and at least one non-condensable gas.

[0210] Embodiment 51: A selective adsorption unit, At least one container having an upstream end and a downstream end, wherein the or each of the containers is An adsorbent bed comprising at least one layer of an adsorbent material selective for sulfur-containing compounds, A first outlet for purified CO2 located at the downstream end of the container or each container, A first outlet for purified CO2 located at the downstream end of the container or each container, A second inlet for regenerating gas located at the said or the said downstream end of each container, A selective adsorption unit comprising at least one container, which includes a second outlet for spent regenerated gas located at the upstream end of the said or each container, The apparatus according to embodiment 50, wherein the first inlet of the selective adsorption unit is in fluid flow communication with the first outlet of the second stage of the purification unit, and the second outlet is in fluid flow communication with the Krauss unit.

[0211] Embodiment 52: A reactor, At least one container having an upstream end and a downstream end, wherein the or each of the containers is A floor containing at least one solid metal oxide, A first outlet for purified CO2 located at the downstream end of the container or each container, A first outlet for purified CO2 located at the downstream end of the container or each container, A second inlet for regenerating gas located at the said or the said downstream end of each container, A reactor comprising at least one container, which includes a second outlet for spent regenerated gas located at the upstream end of the said or each container, The apparatus according to embodiment 50, wherein the first inlet of the reactor is in fluid flow communication with the first outlet of the second stage of the purification unit, and the second outlet is in fluid flow communication with the Krauss unit. [Examples]

[0212] Here, specific embodiments of the present invention are illustrated by computer modeling in the following examples.

[0213] Example 1 The process depicted in the flowsheet of Figure 1, in which Unit 36 ​​is a reactor containing a bed of mixed metal oxides of the type disclosed in US4797268, was modeled by computer using Aspen Plus (version 10), and key flow thermal and mass balance data are provided in Table 1. [Table 1]

[0214] This example illustrates that with a purity of 100 mol%, the overall CO2 recovery rate is 92.5 mol%, meaning that residual H2S (and water) is completely removed from impure CO2.

[0215] Example 2 The process depicted in the flowsheet of Figure 2, in which unit 50 is a reactor having a bed of mixed metal oxides of the type disclosed in US4797268 and unit 56 is a CPU of the type disclosed in US7819951, was modeled by computer using Aspen Plus (version 10), and key flow thermal and mass balance data are provided in Table 2. In the model, the purge flow was zero. [Table 2]

[0216] This example illustrates that with a purity of 99.5 mol%, the overall CO2 recovery rate is 95.8 mol%, with the remainder being H2, meaning that residual H2S (and water) is completely removed from impure CO2.

[0217] Example 3 The process depicted in the flow sheet of Figure 3, where unit 36 is a reactor containing a bed of mixed metal oxides of the type disclosed in US4797268, was modeled by computer using Aspen Plus (version 10), and the heat and mass balance data for the important streams are provided in Table 3. [Table 3]

[0218] This example illustrates that the overall CO2 recovery rate is 91.5 mol% at a purity of 100 mol%, i.e., residual H2S (and water) is completely removed from the impure CO2.

[0219] Example 4 The process depicted in the flow sheet of Figure 4, where unit 50 is a reactor containing a bed of mixed metal oxides of the type disclosed in US4797268, was modeled by computer using Aspen Plus (version 10), and the heat and mass balance data for the important streams are provided in Table 4. [Table 4] <照合

[0220] This example illustrates that the overall CO2 recovery rate is 95.8 mol% at a purity of 99.5 mol%, with the remainder being H2, i.e., residual H2S (and water) is completely removed from the impure CO2.

[0221] Example 5 The process depicted in the flow sheet of Figure 5, where the purification units 56 and 74 are of the type disclosed in Figure 2 of US10254042A, was modeled by computer using Aspen Plus (version 10), and the heat and mass balance data for the important streams are provided in Table 5. [Table 5]

[0222] This example illustrates that with a purity of 99.5 mol%, the overall CO2 recovery rate is 95.6 mol%. The product CO2 also contains approximately 0.5 mol% H2 and less than 100 ppm of H2S, which meets the H2S requirements for sequestering.

[0223] Example 6 The process depicted in the flowsheet of Figure 1, in which unit 36 ​​is a selective adsorption unit of the type disclosed in WO2021130530A, was modeled by computer using Aspen Plus (version 10), and key flow thermal and mass balance data are provided in Table 6. [Table 6]

[0224] This example illustrates that with a purity of 100 mol%, the overall CO2 recovery rate is 91.6 mol%, meaning that residual H2S (and water) is completely removed from impure CO2 using the selective adsorption unit 36 ​​(which includes a layer of water adsorbent material).

[0225] Example 7 The purification unit 56 is of the type disclosed in Figure 1B of US10254042A. The process depicted in the flowsheet of Figure 6 is modeled by computer using Aspen Plus (version 10), and key flow thermal and mass balance data are provided in Table 7. [Table 7]

[0226] This example illustrates that the CO2 recovery rate is 95.3 mol% with a purity of 99.5 mol%. The product CO2 contains less than 0.5 mol% H2 and no H2S, thus meeting the H2S requirements for sequestering.

[0227] Example 8 The process depicted in the flowsheet of Figure 7 (where Unit 26** represents a specific combination of Units 26, 32, and 36 from Figure 1) was modeled by computer using Aspen Plus (version 10), and key flow thermal and mass balance data are provided in Table 8. [Table 8]

[0228] This example illustrates that with a purity of 100 mol%, the overall CO2 recovery rate is 91.6 mol%. Therefore, although the CO2 recovery is less than in other embodiments, the purity of the CO2 is high in this embodiment.

[0229] It will be understood that the present invention is not limited to the details described above with reference to preferred embodiments, and that numerous modifications and variations can be made without departing from the spirit and scope of the invention as defined in the following claims.

[0230] In this specification, unless otherwise explicitly specified, the word “or” is used to mean an operator that returns true if either or both of the specified conditions are met, as opposed to the “exclusive or” operator which requires that only one of the conditions be met. The word “contains” is used to mean “contains,” and not “consist of.”

[0231] All prior teachings above are incorporated herein by reference. Approval of any previously published documents herein does not constitute an acknowledgment or representation that such teachings were common knowledge in Australia or elsewhere as of that date. This disclosure includes the following embodiments of the invention: <Aspect 1> Hydrogen sulfide (H 2 S) and optionally containing at least one other sulfur-containing impurity, crude carbon dioxide (CO2) 2 ) A method for desulfurizing gas, H 2 Crude CO2 containing S 2 The gas is supplied to the Krauss process, and oxygen (O 2 ) In the presence of gas H 2 Convert S to elemental sulfur, CO 2 , residual H 2 To produce a Claustail gas containing S and at least one other sulfur-containing impurity, The aforementioned Claustaire gas is supplied to the hydrogenation process to produce hydrogen (H 2 In the presence of H 2 Convert to S, H 2 S-enriched CO 2 To generate tail gas, The aforementioned H 2 S-enriched CO 2 The tail gas is cooled, condensed water is removed, and cooled H 2 S-enriched CO 2 To generate tail gas, The cooled H 2 S-enriched CO 2 Tail gas, or H derived therefrom 2 Impure CO2 containing sulfur 2 Compress the gas, H 2 Compressed impure CO2 containing S 2 To generate gas, By physical separation or by chemical reaction with at least one solid metal sulfide, and then by oxidation regeneration, the compressed impure CO 2 Gas to H 2 Removing sulfur and any other sulfur-containing impurities, purified CO2 2 , and generating a first recycled gas containing at least one sulfur-containing compound, A method comprising recycling the first recycled gas to the Krauss process to convert the at least one sulfur-containing compound into elemental sulfur. <Aspect 2> In the hydrogen generation process, H 2 To cause, The aforementioned H 2 To supply the above-mentioned hydrogenation process, Non-selective amine absorption leads to the H 2 S-enriched CO 2 CO from tail gas 2 and H 2 S is recovered, and the impure CO for compression. 2 CO 2 The method according to embodiment 1, further comprising generating it together with waste gas containing at least one non-condensable gas. <Aspect 3> The aforementioned H 2 S-enriched CO 2 By directly compressing the tail gas, H 2 The compressed impure CO2 containing S 2 The method according to embodiment 1, wherein gas is generated. <Aspect 4> The purified CO 2 The CO2 is then supplied to a further purification unit to produce even more purified CO2. 2 CO 2 and H 2 To produce a second recycled gas containing, The second recycled gas, or H derived therefrom 2 Recycling enriched gas into the aforementioned hydrogenation process, In the membrane separation process, H is extracted from the second recycled gas. 2 The H 2 enriched gas, CO 2 and further comprising being produced together with waste gas containing at least one non-condensable gas, A portion of the second recycled gas, or the H derived therefrom 2 The method according to embodiment 1, wherein a portion of the enriched gas is purged. <Aspect 5> Selective amine absorption leads to the H 2 S-enriched CO 2 H from tail gas 2 Retrieve S, H 2 S-deficient CO2 2 Tail gas and recovered H 2 The generation of S, The recovered H 2 S is recycled to the Krauss process, and the recovered H 2 Converting S to elemental sulfur, Non-selective amine absorption leads to the H 2 S-deficient CO2 2 CO from tail gas 2 and residual H 2 S is recovered, and the impure CO for compression. 2 CO 2 and is produced together with waste gas containing at least one non-condensable gas, The purified CO 2 The CO2 is then supplied to a further purification unit to produce even more purified CO2. 2 CO 2 and H 2 To produce a second recycled gas containing, The second recycled gas, or H derived therefrom 2 Recycling enriched gas into the aforementioned hydrogenation process, In the membrane separation process, H is extracted from the second recycled gas. 2 The gas is recovered, H 2 enriched gas, CO 2 and further comprising being produced together with waste gas containing at least one non-condensable gas, The aforementioned H 2 S-deficient CO2 2 The tail gas is directly compressed, and the compressed impure CO 2 Gas is generated, and part of the second recycled gas, or the H derived therefrom. 2 The method according to embodiment 1, wherein a portion of the enriched gas is purged. <Aspect 6> The chemical reaction with at least one solid metal oxide forms a solid metal sulfide, which is then regenerated by oxidation, thereby H 2 S and any other sulfur-containing impurities are present in the compressed impure CO 2 The method according to embodiment 1, wherein the gas is removed. <Aspect 7> The purified CO is downstream of a sulfur-containing adsorbent material that is selective for sulfur-containing compounds. 2 Further includes drying, The regenerated gas contains an insufficient amount of water to hydrolyze other sulfur-containing compounds, and the compressed impure CO2 is transferred to the selective adsorption unit. 2 The gas supply contains water and H 2 S and any other sulfur-containing impurities are separated by selective adsorption as the physical separation from the compressed impurity CO 2 The compressed impure CO is removed from the gas, and the selective adsorption is by adsorption on the floor containing at least one adsorbent material that is selective for sulfur-containing compounds in the selective adsorption unit. 2 H in gas 2 Remove S and any other sulfur-containing compounds from the purified CO 2 After generating and desorbing with regenerating gas, the compressed impure CO 2 From the gas, the H 2 The method according to embodiment 1, comprising generating spent regenerated gas containing S and any other sulfur-containing compound as the first recycled gas. <Aspect 8> H 2 S and any other sulfur-containing impurities, the impure CO 2 The gas is passed through the bed containing the at least one solid metal oxide in the reactor, converting the at least one solid metal oxide into at least one metal sulfide to obtain the purified CO 2 To generate, O 2 The floor is regenerated using a regenerated gas containing sulfur dioxide (SO4) as the first recycled gas. 2 By generating spent recycled gas containing ) and the compressed impure CO 2 The method according to embodiment 1, wherein the gas is removed. <Pattern 9> The method according to embodiment 8, wherein the regenerated gas contains an amount of water insufficient to hydrolyze other sulfur-containing compounds. <Aspect 10> The purified CO2 downstream of the bed containing the at least one solid metal oxide 2 The process further includes drying the gas and supplying the compressed impure CO to the reactor. 2 The method according to embodiment 8, wherein the gas supply includes water. <Aspect 11> It is a method, Compressed impure CO 2 H is obtained from gas by distillation and / or partial condensation by phase separation. 2 And remove any other non-condensable gases, H 2 S-enriched CO 2 Fluid and H 2 enriched CO 2 To generate gas, The aforementioned H 2 enriched CO 2 gas, or further H derived therefrom 2 enriched CO 2 Recycling the gas as a second recycled gas for the hydrogenation process, The H 2 S-enriched CO 2 The fluid was separated and purified CO was obtained as overhead gas. 2 and H 2 To generate an S-enriched bottom liquid, The aforementioned H 2 The S-enriched bottom liquid is vaporized, and H is used as the first recycled gas. 2 This includes generating S-enriched gas, A portion of the second recycled gas, or the H derived therefrom 2 A method for purging a portion of the enriched gas. <Aspect 12> In the membrane separation process, H is extracted from the second recycled gas. 2 By recovering the gas, CO 2 and the further H for recycling, together with the waste gas containing at least one non-condensable gas. 2 enriched CO 2 The method according to embodiment 11, further comprising generating a gas. <Aspect 13> The purified CO 2 The method according to embodiment 11, wherein the overhead gas contains one or more residual sulfur-containing compounds. <Aspect 14> By selective adsorption or by chemical reaction with at least one solid metal oxide, solid metal sulfides are formed, and then by oxidation and regeneration, H 2 S and any other sulfur-containing impurities are removed from the purified CO 2 Further purified CO is removed from the overhead gas. 2 , and generating a third recycled gas containing at least one sulfur-containing compound, The method according to embodiment 11, further comprising recycling the third recycled gas to a Krauss process to convert the sulfur-containing compound into elemental sulfur. <Aspect 15> It is a system, crude CO 2 Gas to H 2 A Krauss unit for removing S, O 2 A first inlet for the oxidizing gas containing, The aforementioned crude CO 2 A second inlet for gas, CO 2 , residual H 2 A first outlet for Claustail gas containing S and at least one other sulfur-containing impurity, A Krauss unit, equipped with a second outlet for elemental sulfur, The first inlet of the Krauss unit is in fluid flow communication with O 2 A source of oxidizing gas containing, The crude CO2 is in fluid flow communication with the second inlet of the Krauss unit. 2 The source of supply and The at least one other sulfur-containing impurity in the Claustail gas is H 2 A hydrogenation unit for converting to S, The first inlet of the Krauss unit is in fluid flow communication with the first inlet, H 2 A second entrance for, H 2 S-enriched CO 2 A hydrogenation unit comprising a first outlet for tail gas, H 2 The source of supply and H 2 S-enriched CO 2 A cooling unit for cooling tail gas, The first outlet of the hydrogenation unit and the first inlet, which are in fluid communication with each other, Cooled H 2 S-enriched CO 2 The first outlet for tail gases, A cooling unit comprising a second outlet for condensed water, Cooled H 2 S-enriched CO 2 Tail gas, or H derived therefrom 2 Impure CO2 containing sulfur 2 A compression unit for compressing gas, wherein the compression device is The first outlet of the cooling unit and the inlet which is in fluid flow communication, Compressed impure CO 2 A compression unit equipped with an outlet for gas, By physical separation or by chemical reaction with at least one metal oxide, solid metal sulfides are formed, and then by oxidation and regeneration, H 2 S and any other sulfur-containing impurities are removed from compressed impure CO2. 2 A purification unit for removing gas, The first inlet of the compression unit is in fluid flow communication with the outlet, purified CO 2 The first exit for, A purification unit comprising a second outlet for a first recycled gas containing at least one sulfur-containing compound, A system in which the second outlet of the purification unit is in fluid communication with the Krauss unit.

Claims

1. Hydrogen sulfide (H 2 S) and optionally containing at least one other sulfur-containing impurity, crude carbon dioxide (CO2) 2 ) A method for desulfurizing gas, H 2 Crude CO2 containing S 2 The gas is supplied to the Krauss process, and oxygen (O) 2 ) In the presence of gas H 2 Convert S to elemental sulfur, CO 2 , residual H 2 To produce a Claustaire gas containing S and at least one other sulfur-containing impurity, Feeding the Claus tail gas to a hydrogenation process to convert the at least one other sulfur-containing impurity in the presence of hydrogen (H 2 ), to H 2 S and producing H 2 S-enriched CO 2 tail gas; The aforementioned H 2 S-enriched CO 2 The tail gas is cooled, the condensed water is removed, and the cooled H 2 S-enriched CO 2 To generate tail gas, The cooled H 2 S-enriched CO 2 Tail gas, or H derived therefrom 2 Impure CO2 containing sulfur 2 Compress the gas, H 2 Compressed impure CO2 containing sulfur 2 To generate gas, By physical separation or by chemical reaction with at least one solid metal sulfide, and then by oxidation regeneration, the compressed impure CO 2 Gas to H 2 By removing sulfur and any other sulfur-containing impurities, purified CO 2 , and generating a first recycled gas containing at least one sulfur-containing compound, The aforementioned first recycled gas is recycled to the Krauss process to convert the at least one sulfur-containing compound into elemental sulfur, The purified CO2 is supplied to a further purification unit to produce further purified CO2 and a second recycled gas containing CO2 and H2. The process includes recycling the second recycled gas, or an H2-enriched gas derived therefrom, into the hydrogenation process, A method in which a portion of the second recycled gas, or a portion of the H2-enriched gas derived therefrom, is purged.

2. In the hydrogen generation process, H 2 To cause, The aforementioned H 2 To supply the above-mentioned hydrogenation process, Non-selective amine absorption leads to the H 2 S-enriched CO 2 CO from tail gas 2 and H 2 S is recovered, and the impure CO is used for compression. 2 CO 2 The method according to claim 1, further comprising generating it together with waste gas containing at least one non-condensable gas.

3. The aforementioned H 2 S-enriched CO 2 By directly compressing the tail gas, H 2 The compressed impure CO2 containing S 2 The method according to claim 1, comprising generating a gas.

4. In the membrane separation process, H from the second recycled gas 2 The H 2 enriched gas, CO 2 The method according to claim 1, further comprising producing it together with waste gas containing at least one non-condensable gas.

5. A solid metal sulfide is formed by the aforementioned chemical reaction with at least one solid metal oxide, and then H is regenerated by oxidation. 2 S and any other sulfur-containing impurities are present in the compressed impure CO 2 The method according to claim 1, which is removed from the gas.

6. The purified CO2 is used downstream of a sulfur-containing adsorbent material that is selective for sulfur-containing compounds. 2 Further includes drying, The regenerated gas contains an insufficient amount of water to hydrolyze other sulfur-containing compounds, and the compressed impure CO2 is transferred to the selective adsorption unit. 2 The method according to claim 1, wherein the gas supply includes water.

7. H 2 S and any other sulfur-containing impurities, the impure CO 2 The gas is passed through the bed containing the at least one solid metal oxide in the reactor to convert the at least one solid metal oxide into at least one metal sulfide, thereby producing the purified CO 2 To generate, O 2 The floor is regenerated using a regenerated gas containing sulfur dioxide (SO4) as the first recycled gas. 2 By generating spent recycled gas containing ) and the compressed impure CO 2 The method according to claim 1, which is removed from the gas.

8. The method according to claim 7, wherein the regenerated gas contains an amount of water insufficient to hydrolyze other sulfur-containing compounds.

9. The purified CO2 downstream of the bed containing the at least one solid metal oxide 2 The process further includes drying the gas and supplying the compressed impure CO2 to the reactor. 2 The method according to claim 7, wherein the gas supply includes water.

10. A system for the method of Claim 1, Crude CO 2 Gas to H 2 A Krauss unit for removing S, O 2 A first inlet for the oxidizing gas containing, The aforementioned crude CO 2 A second inlet for gas, CO 2 , residual H 2 A first outlet for claustaire gas containing S and at least one other sulfur-containing impurity, A Krauss unit, comprising a second outlet for elemental sulfur, The first inlet of the Krauss unit is in fluid flow communication with O 2 A source of oxidizing gas containing, The crude CO2 is in fluid flow communication with the second inlet of the Krauss unit. 2 The source of supply and The at least one other sulfur-containing impurity in the Claustail gas is H 2 A hydrogenation unit for converting to S, The first inlet of the Krauss unit is in fluid flow communication with the first inlet, H 2 A second entrance for, H 2 S-enriched CO 2 A hydrogenation unit comprising a first outlet for tail gas, H is in fluid flow communication with the second inlet of the hydrogenation unit. 2 The source of supply and H 2 S-enriched CO 2 A cooling unit for cooling tail gas, The first outlet of the hydrogenation unit and the first inlet, which are in fluid communication with each other, Cooled H 2 S-enriched CO 2 The first outlet for tail gas, A cooling unit comprising a second outlet for condensed water, Cooled H 2 S-enriched CO 2 Tail gas, or H derived therefrom 2 Impure CO2 containing sulfur 2 A compression unit for compressing gas, wherein the compression device is The first outlet of the cooling unit and the inlet which is in fluid flow communication, Compressed impure CO 2 A compression unit equipped with an outlet for gas, By physical separation or by chemical reaction with at least one metal oxide, solid metal sulfides are formed, and then by oxidation and regeneration, H 2 S and any other sulfur-containing impurities are removed from compressed impure CO2. 2 A purification unit for removing gas, The first inlet of the compression unit is in fluid flow communication with the outlet, purified CO 2 The first exit for, A purification unit comprising a second outlet for a first recycled gas containing at least one sulfur-containing compound, A system in which the second outlet of the purification unit is in fluid communication with the Krauss unit.

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