Carbon dioxide recovery apparatus and carbon dioxide recovery method

Abstract

To reduce energy consumption for recovering carbon dioxide.SOLUTION: A carbon dioxide recovery apparatus comprises a separation processing unit that separates carbon dioxide contained in a raw material gas from the raw material gas by a membrane that allows for permeation of carbon dioxide, a suction unit that suctions a processing gas containing carbon dioxide separated from the raw material gas, a cooling unit that is disposed upstream of the suction unit and cools the processing gas using a refrigerant, a vaporization unit that gasifies a liquefied gas using the refrigerant, and a circulation unit that circulates the refrigerant between the cooling unit and the vaporization unit such that the refrigerant repeats a temperature increase accompanying cooling of the processing gas and a temperature decrease accompanying gasification of the liquefied gas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a carbon dioxide capture device, a combustion system, a power generation system, and a method for capturing carbon dioxide. [Background technology]

[0002] Techniques for separating and recovering carbon dioxide from a gas containing carbon dioxide are known (see, for example, Patent Documents 1 to 3 and Non-Patent Document 1 below). Patent Document 1 discloses a gas separation device that separates carbon dioxide and water vapor from a mixed gas containing carbon dioxide and water vapor as main component gases. Patent Document 2 discloses a gas recovery device that individually separates carbon dioxide and an inert gas from a mixed gas containing carbon dioxide and an inert gas as main components. Patent Document 3 discloses a gas separation system that includes a carbon dioxide separation membrane that separates carbon dioxide and a water vapor removal means that removes water vapor in the gas from which carbon dioxide has been separated. Patent Document 4 discloses a membrane that has high carbon dioxide permeability and can selectively permeate carbon dioxide relative to nitrogen and the like. Non-Patent Document 1 discloses a technique for recovering carbon dioxide by a chemical absorption method that utilizes a chemical reaction between a basic substance and carbon dioxide. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2012 / 086836 [Patent Document 2] International Publication No. 2017 / 086293 [Patent Document 3] Japanese Patent Application Publication No. 2017-221864 [Patent Document 4] International Publication No. 2017 / 146231 [Non-patent literature]

[0004] [Non-Patent Document 1] Shigeo Murai et al., "CCS (CO2 Storage, Capture, and Separation Technology)", Journal of the Japan Society of Mechanical Engineers, April 2011, Vol. 114, No. 1109, pp. 26-28 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a carbon dioxide capture device, a combustion system, a power generation system, and a carbon dioxide capture method that can reduce the energy consumption for capturing carbon dioxide. [Means for solving the problem]

[0006] [1] a separation processing unit that separates carbon dioxide contained in a raw material gas from the raw material gas using a carbon dioxide permeable membrane; an intake unit that intakes a treatment gas containing carbon dioxide separated from the raw material gas; a cooling unit disposed upstream of the suction unit and configured to cool the processing gas using a refrigerant; an evaporation unit that gasifies a liquefied gas using the refrigerant; A carbon dioxide recovery device comprising: a circulation unit that circulates the refrigerant between the cooling unit and the evaporation unit so that the refrigerant repeatedly undergoes a temperature increase due to cooling of the treated gas and a temperature decrease due to gasification of the liquefied gas. [2] The recovery device according to [1] above, wherein the refrigerant supplied from the circulation section to the cooling section has a temperature of 1°C to 20°C. [3] Further provided is a water vapor-containing gas supply unit that supplies a water vapor-containing gas containing water vapor to the separation treatment unit; the separation processing unit has the membrane arranged to separate a first space to which the source gas is supplied from a second space, The recovery device according to the above [1] or [2], wherein the water vapor-containing gas supply unit supplies the water vapor-containing gas to the second space. [4] Another cooling unit is arranged downstream of the suction unit and cools the gas discharged by the suction unit using the refrigerant; The recovery device according to any one of the above [1] to [3], further comprising another suction part that is arranged downstream of the other cooling part and that sucks in the gas released by the suction part. [5] The recovery device according to [4] above, wherein the pressure of the gas discharged from the recovery device via at least the suction section and the other suction section is 1 atmosphere or more. [6] The recovery device according to any one of the above [1] to [5], wherein the liquefied gas is liquefied natural gas. [7] The recovery device of [6] above; a combustion device that combusts natural gas obtained by gasifying the liquefied natural gas in the vaporization unit, A combustion system, wherein the raw material gas supplied to the separation processing unit includes exhaust gas discharged from the combustion device. [8] The recovery device of [6] above; a power generation device that generates electricity by combusting natural gas obtained by gasifying the liquefied natural gas in the vaporization unit, The power generation system, wherein the raw material gas supplied to the separation processing unit includes an exhaust gas discharged from the power generation device. [9] a separation step of separating carbon dioxide contained in a raw material gas from the raw material gas using a carbon dioxide permeable membrane; a suction step of suctioning a treatment gas containing carbon dioxide separated from the raw material gas; a cooling step of cooling the treatment gas using a refrigerant upstream of the suction step; a gasification step of gasifying a liquefied gas using the refrigerant; a circulation step of circulating the refrigerant so that the refrigerant repeatedly undergoes a temperature increase associated with cooling of the treated gas and a temperature decrease associated with gasification of the liquefied gas.

[10] The recovery method according to [9] above, wherein the liquefied gas is liquefied natural gas.

[11] The method further includes a combustion step of burning natural gas obtained by gasifying the liquefied natural gas in the gasification step, The recovery method according to

[10] above, wherein the raw material gas includes exhaust gas emitted in the combustion step.

[12] The method further includes a power generation step of generating electricity by combusting natural gas obtained by gasifying the liquefied natural gas in the gasification step, The recovery method according to

[10] above, wherein the raw material gas includes exhaust gas discharged in the power generation step. [Effects of the Invention]

[0007] According to the present disclosure, there are provided a carbon dioxide capture device, a combustion system, a power generation system, and a carbon dioxide capture method that are capable of reducing the energy consumption for capturing carbon dioxide. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing an example of a carbon dioxide recovery device. [Figure 2] FIG. 2 is a schematic diagram showing an example of a separation device. [Figure 3] FIG. 3 is a schematic diagram showing another example of the separation device. [Figure 4] FIG. 4 is a schematic diagram showing an example of a combustion system. [Figure 5] FIG. 5 is a schematic diagram showing an example of a power generation system. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment will be described below with reference to the drawings. In the description, the same elements or elements having the same functions are designated by the same reference numerals, and redundant description will be omitted.

[0010] [Carbon dioxide capture device] FIG. 1 is a schematic diagram showing an example of a carbon dioxide recovery apparatus. The carbon dioxide recovery apparatus 10 shown in FIG. 1 is an apparatus that recovers carbon dioxide from a raw material gas containing carbon dioxide. Specifically, the recovery apparatus 10 separates carbon dioxide contained in a supplied raw material gas (hereinafter referred to as "raw material gas G0") from the raw material gas G0, and recovers a gas having a higher carbon dioxide purity (concentration) than the raw material gas G0. The concentration of carbon dioxide contained in the gas obtained by recovering carbon dioxide with the recovery apparatus 10 may be 70% or more, 80% or more, or 90% or more.

[0011] Examples of the raw material gas G0 include combustion exhaust gas, indoor or outdoor air, biogas, and fossil fuels reformed with steam. The combustion exhaust gas may be exhaust gas emitted after combustion in oil refineries, petrochemical / chemical plants, steel plants, cement plants, factories, agricultural heaters, automobile engines, gas heat pumps, boilers, combustion-type water heaters, or power plants (e.g., power generation facilities using fossil fuels, biomass, biogas, garbage, or waste as fuel). The combustion exhaust gas may be gas obtained by burning fossil fuels, biomass, biogas, garbage, or waste with a gas containing more oxygen than air. The combustion exhaust gas is primarily composed of nitrogen, carbon dioxide, oxygen, and water vapor, and may also contain trace components such as ash, sulfur oxides, or nitrogen oxides. The carbon dioxide concentration in the combustion exhaust gas may be 30% or less, 20% or less, or 10% or less.

[0012] The raw material gas G0 contains carbon dioxide, water vapor, and gas components other than carbon dioxide and water vapor. The gas components other than carbon dioxide and water vapor include, for example, nitrogen, oxygen, methane, or hydrogen. An example of the recovery device 10 will be described in detail below. In this disclosure, the terms "upstream" and "downstream" are used based on the gas flow. In other words, the gas flows from upstream to downstream in the gas flow path. As shown in FIG. 1, the recovery device 10 includes a vaporization device 20 (vaporization section), a separation device 30, and a circulation device 60 (circulation section).

[0013] The vaporizer 20 is a device that generates gas by gasifying (vaporizing) liquefied gas. The liquefied gas gasified by the vaporizer 20 is a gas with a boiling point of 0°C or lower. The type of liquefied gas is not limited, and examples of the liquefied gas include liquefied natural gas (LNG), liquefied hydrogen, liquefied ammonia, and liquefied carbon dioxide. An example in which the liquefied gas is liquefied natural gas (LNG) will be described below. The vaporizer 20 may generate natural gas Gn by gasifying (vaporizing) liquefied natural gas LNG. In addition to gasifying liquefied natural gas LNG, the vaporizer 20 may have a function of heating the natural gas Gn after gasification. For example, liquefied natural gas LNG is supplied to the vaporizer 20 from a tank in which liquefied natural gas LNG is stored by a pump or the like.

[0014] The vaporizer 20 gasifies (regasifies) the liquefied natural gas LNG using a fluid supplied from the circulation device 60. The fluid supplied from the circulation device 60 to the vaporizer 20 is used to cool the gas in the separation device 30, as described below. Therefore, the fluid supplied from the circulation device 60 will be referred to as a "refrigerant" even when used for gasification in the vaporizer 20. The vaporizer 20 may gasify and heat the liquefied natural gas LNG using the refrigerant from the circulation device 60. The vaporizer 20 may supply the generated natural gas Gn to a device that generates energy such as electricity or heat using the natural gas Gn as fuel.

[0015] The separation device 30 is a device that separates carbon dioxide from the raw material gas G0. The above-mentioned combustion exhaust gas may be supplied to the separation device 30 as the raw material gas G0. The separation device 30 discharges gas Gd1 and gas Gd2. The gas Gd1 is the gas remaining after carbon dioxide is extracted from the raw material gas G0. The gas Gd2 is a gas containing carbon dioxide extracted from the raw material gas G0. FIG. 2 is a schematic diagram showing an example of the separation device in more detail. Note that some elements of the separation device 30 are omitted in FIG. 1. The separation device 30 may have a separation treatment unit 40 and an exhaust treatment unit 50, as shown in FIG. 2.

[0016] The separation processing unit 40 is a processing unit that extracts at least a portion of the carbon dioxide in the raw material gas G0. The separation processing unit 40 separates the carbon dioxide contained in the raw material gas G0 from the raw material gas G0 using a carbon dioxide-permeable membrane. The separation processing unit 40 generates a gas (hereinafter referred to as "processed gas Gp") in which the ratio of carbon dioxide to components other than carbon dioxide and water vapor is higher than that of the raw material gas G0. In other words, the ratio of carbon dioxide to components other than carbon dioxide and water vapor in the processed gas Gp is ​​higher than the ratio of carbon dioxide to components other than carbon dioxide and water vapor in the raw material gas G0. The separation processing unit 40 has, for example, a housing 42 and a separation member 44. The housing 42 houses the separation member 44 and forms an internal space.

[0017] The separating member 44 is a member that separates carbon dioxide from the source gas G0 using a separation membrane that selectively allows carbon dioxide contained in the source gas G0 to permeate. The separating member 44 is arranged to divide the internal space formed by the housing 42 into two spaces. Hereinafter, of the pair of spaces separated by the separating member 44, the space to which the source gas G0 is supplied will be referred to as the "first space V1," and the other space will be referred to as the "second space V2." In other words, the separating member 44 is arranged inside the housing 42 to separate the first space V1 from the second space V2.

[0018] The separation member 44 includes a separation membrane 46 that selectively allows carbon dioxide (or carbon dioxide and water vapor) in the source gas G0 to permeate. In the present disclosure, "selectively allowing one or more components to permeate" means allowing a portion of the gas to permeate so that the amount of permeation of the one or more components among the various components contained in the supplied gas is greater than the amount of permeation of the other components. The separation membrane 46 has the property of allowing carbon dioxide and water vapor, among the various components contained in the source gas G0, to permeate more easily than components other than carbon dioxide and water vapor (e.g., nitrogen, oxygen, methane, hydrogen, etc.). The separation membrane 46 may be made of an alkaline material. The separation membrane 46 may be made of the material (gelling polymer particles) described in Patent Document 4 above.

[0019] The separation membrane 46 includes, for example, a monolayer membrane containing gelling polymer particles having basic functional groups. Gelling polymer particles are polymer particles that have the property of swelling in water or a polar solvent to form gel-like microparticles. The gelling polymer particles may be, for example, particles of a neutral, alkaline, or acidic polymer compound impregnated with basic molecules. The thickness of the monolayer membrane containing the gelling polymer particles may be less than 50 μm. The functional groups contained in the gelling polymer particles may be one or more functional groups selected from the group consisting of amino groups, ammonium groups, carboxylic acids, and sulfuric acids. The polymer compound constituting the gelling polymer particles may be a polymer of monomer components containing a monomer having a basic functional group or an acidic functional group. The impregnated basic molecules may include an amine-containing compound having a molecular weight of 61 to 10,000, and the pKa of the conjugate acid of the amine-containing compound may be 5 to 10. The impregnated basic molecules may have a hydroxyl group, a carboxylic acid group, or a sulfonic acid group. Alternatively, the basic molecule to be impregnated may have multiple amino groups or multiple hydroxyl groups.

[0020] The monomer may include a substituted acrylamide monomer, an N-(aminoalkyl)acrylamide, or a carboxylic acid or sulfonic acid. The proportion of the monomer having a carboxylic acid or sulfonic acid in the monomer component may be 1 to 95 mol %, or may be 5 to 95 mol %. The monomer component may include a monomer having a carboxylic acid or sulfonic acid and a monomer having a hydrophobic group. In this case, the molar ratio of the monomer having a carboxylic acid or sulfonic acid to the monomer having a hydrophobic group may be 1:95 to 95:5. The monomer having a carboxylic acid may be methacrylic acid or acrylic acid, and the monomer having a hydrophobic group may be N-alkylacrylamide. Alternatively, the monomer having a sulfonic acid may be acrylamido-t-butylsulfonic acid or vinylsulfonic acid, and the monomer having a hydrophobic group may be N-alkylacrylamide.

[0021] The gelling polymer particles may be crosslinked polymer compounds. The crosslinks may be formed by copolymerizing a monomer (crosslinking agent) having multiple polymerizable functional groups during polymerization, or by chain transfer during polymerization without using a crosslinking agent, resulting in the formation of covalent crosslinks. The crosslinks may also be formed by generating covalent bonds through reactions between polymer chains after polymerization. Furthermore, the crosslinks may be formed by covalent bonds or by interactions or entanglements between polymers.

[0022] The separation member 44 may include a carrier 46a supporting the separation membrane 46. The carrier 46a may be a porous material (e.g., a porous film). The monolayer membrane containing gelling polymer particles may be formed by applying an aqueous solution containing gelling polymer particles to the surface of a porous film and drying the aqueous solution. The gelling polymer particles may be large enough to block the surface pores of the porous carrier 46a. The particle diameter of the gelling polymer particles may be larger than the surface pores of the porous carrier 46a. The porous carrier 46a has a first surface and a second surface facing opposite to each other. The surface pores of the first surface may be blocked by the polymer particles, while the surface pores of the second surface may not be blocked by the polymer particles. In this case, the separation membrane 46 and the carrier 46a may be arranged so that the first surface faces the first space V1 and the second surface faces the second space V2. The surface of the carrier 46a may have a regular uneven structure that is sufficiently larger than the surface pores.

[0023] A source gas G0 is supplied to the first space V1 in the housing 42. The pressure of the first space V1 to which the source gas G0 is supplied may be about 101 kPa (approximately equal to 1 atmosphere) or may be greater than 1 atmosphere. The second space V2 may be maintained at a pressure lower than the pressure of the first space V1 (for example, a pressure lower than 1 atmosphere). The pressure of the second space V2 may be about half or less than half the pressure of the first space V1. The pressure of the second space V2 may be 50 kPa or less, 30 kPa or less, or 20 kPa or less. When the diameter of the polymer particles contained in the separation membrane 46 is larger than the pore diameter of the porous carrier 46a, the separation membrane 46 is less likely to be damaged by the pressure difference between the first space V1 and the second space V2.

[0024] The separation device 30 may have a water vapor-containing gas supply unit 38. The water vapor-containing gas supply unit 38 supplies a gas containing water vapor to the separation treatment unit 40. The water vapor-containing gas supply unit 38 supplies a gas containing water vapor (hereinafter referred to as "water vapor-containing gas Gs") to the second space V2 of the separation treatment unit 40, thereby promoting separation of carbon dioxide by the separation member 44 (permeation of carbon dioxide through the separation membrane 46). Specifically, the supply of the water vapor-containing gas Gs dilutes the carbon dioxide in the second space V2, and the partial pressure of carbon dioxide in the second space V2 becomes lower than the partial pressure of carbon dioxide in the first space V1. As a result, a greater amount of carbon dioxide is separated by the separation membrane 46 of the separation member 44 than when the water vapor-containing gas Gs is not supplied.

[0025] The water vapor-containing gas Gs may be any gas as long as it contains water vapor and is capable of diluting carbon dioxide in the second space V2. The water vapor-containing gas Gs may contain gaseous components other than water vapor. The water vapor-containing gas supply unit 38 may generate the water vapor-containing gas Gs by utilizing exhaust heat generated in a factory or the like. The temperature of the water vapor-containing gas Gs may be adjusted so as to further promote permeation of carbon dioxide through the separation membrane 46. The temperature of the water vapor-containing gas Gs supplied from the water vapor-containing gas supply unit 38 to the second space V2 may be 25°C to 100°C. Alternatively, the temperature of the water vapor-containing gas Gs may be 30°C to 90°C, or 35°C to 80°C.

[0026] The separation processing unit 40 discharges the gas Gd1 obtained after carbon dioxide has been extracted from the source gas G0 from the first space V1. The separation processing unit 40 may discharge the gas Gd1 from the first space V1 to the outside (to the atmosphere). The separation member 44 separates the carbon dioxide and water vapor from components other than carbon dioxide and water vapor in the source gas G0 (selectively permeating from the first space V1 to the second space V2), thereby generating the above-mentioned process gas Gp in the second space V2. When the water vapor-containing gas supply unit 38 is provided, the process gas Gp contains not only carbon dioxide but also water vapor in the source gas G0 and water vapor in the water vapor-containing gas Gs. The relative humidity of the process gas Gp may be, for example, 50% or more, 60% or more, or 70% or more.

[0027] The exhaust treatment unit 50 is a treatment unit that sucks in the gas in the second space V2 and removes at least a portion of the water vapor in the processing gas Gp. The exhaust treatment unit 50 sucks in the gas from the second space V2 and discharges the gas from which the water vapor has been removed as the above-mentioned gas Gd2. The exhaust treatment unit 50 may discharge the gas Gd2 to the outside of the separation device 30.

[0028] The exhaust treatment unit 50 has, for example, a plurality of suction units (suction devices) and a plurality of cooling units (cooling devices). In the following, an example will be given in which the exhaust treatment unit 50 has two suction units and three cooling units. The two suction units will be referred to as "suction unit 52a" and "suction unit 52b," and the three cooling units will be referred to as "cooling unit 54a," "cooling unit 54b," and "cooling unit 54c," respectively. The suction units 52a and 52b and the cooling units 54a, 54b, and 54c are connected to one another via a gas flow path extending from the second space V2 to the exhaust port of the gas Gd2.

[0029] In the gas flow path between the second space V2 and the outlet of the gas Gd2, a cooling unit 54a, a suction unit 52a, a cooling unit 54b (another cooling unit), a suction unit 52b (another suction unit), and a cooling unit 54c are arranged in this order from the upstream side. Hereinafter, the gas in the intermediate stage (during processing) released from each of these devices will also be referred to as the "processing gas Gp."

[0030] The suction unit 52a is connected to the second space V2 via a gas flow path and is a device that suctions the processing gas Gp in the second space V2. The suction unit 52a may be a compressor or a pump (e.g., a vacuum pump) that depressurizes the second space V2. The suction unit 52a suctions the processing gas Gp in the second space V2, thereby reducing the pressure in the second space V2. The suction unit 52a may suction the gas in the second space V2 so that the pressure in the second space V2 is maintained at a value lower than the pressure in the first space V1.

[0031] The cooling unit 54a is a device that cools the processing gas Gp released from the second space V2 using a refrigerant supplied from the circulation device 60. The cooling unit 54a is disposed between the second space V2 and the suction unit 52a. More specifically, the cooling unit 54a is disposed between the second space V2 and the suction unit 52a (upstream of the suction unit 52a) in the flow path through which the processing gas Gp released from the second space V2 flows. The cooling unit 54a may have a function of separating the processing gas Gp into gas and liquid in addition to a function of cooling the processing gas Gp with a refrigerant (heat exchange function).

[0032] The cooling by the cooling unit 54a reduces the amount of water vapor contained in the processing gas Gp. In this way, the cooling unit 54a removes at least a portion of the water vapor from the processing gas Gp to generate a gas having a higher carbon dioxide purity than the processing gas Gp immediately after being released from the second space V2. The cooling unit 54a may discharge the liquid Ld removed from the processing gas Gp to the outside.

[0033] The suction unit 52a, which is disposed downstream of the cooling unit 54a, sucks in (compresses) the processing gas Gp after at least a portion of the water vapor has been removed by the cooling unit 54a. The suction unit 52a releases the processing gas Gp at a pressure higher than the processing gas Gp immediately after it is released from the second space V2.

[0034] The suction unit 52b is connected in series to the suction unit 52a and is a device that suctions the processing gas Gp released by the suction unit 52a. The suction unit 52b may be of the same type as the suction unit 52a, or may be of a type with different performance or cooling method. The cooling unit 54b is disposed between the suction units 52a and 52b (downstream of the suction unit 52a) in the gas flow path. Like the cooling unit 54a, the cooling unit 54b may cool the processing gas Gp released from the suction unit 52a using a refrigerant supplied from the circulation unit 60. The cooling unit 54b may cool the processing gas Gp using cooling water available at the cooling location, instead of or in addition to the refrigerant from the circulation unit 60, or may cool the processing gas Gp using an air-cooling method. Note that the temperature of the processing gas Gp released from the suction unit 52a is increased by suction by the suction unit 52a compared to the temperature of the processing gas Gp before suction (the processing gas Gp immediately after being released from the second space V2).

[0035] The suction unit 52b, located downstream of the cooling unit 54b, sucks in (compresses) the processing gas Gp from which at least a portion of the water vapor has been removed by the cooling unit 54b. The suction unit 52b discharges the processing gas Gp at a higher pressure than the processing gas Gp discharged by the suction unit 52a. The pressure of the processing gas Gp discharged by the suction unit 52b may be 1 atmosphere or higher.

[0036] The cooling unit 54c is disposed downstream of the suction unit 52b. Like the cooling unit 54b, the cooling unit 54c may cool the process gas Gp discharged from the suction unit 52b using a refrigerant supplied from the circulation device 60. Instead of or in addition to the refrigerant from the circulation device 60, the cooling unit 54c may cool the process gas Gp using available cooling water, or may cool the process gas Gp using an air-cooling method. The temperature of the process gas Gp discharged from the suction unit 52b increases with the suction by the suction unit 52b compared to the temperature of the process gas Gp before suction (the process gas Gp after cooling by the cooling unit 54b). The cooling units 54b and 54c may be of the same type as the cooling unit 54a, or may be of different types with different performance or cooling method. The cooling unit 54c cools the process gas Gp after removing water vapor from it and discharges it to the outside of the discharge treatment unit 50 as the gas Gd2.

[0037] The exhaust treatment unit 50 described above sucks gas from the second space V2 using two suction units (suction units 52a, 52b) connected in multiple stages. In the exhaust treatment unit 50, the pressure of the processing gas Gp released from the second space V2 is increased in stages by the suction units 52a, 52b. The pressure of the gas Gd2 exhausted from the exhaust treatment unit 50 may be 1 atmosphere or more. That is, the exhaust treatment unit 50 may increase the pressure of the processing gas Gp to 1 atmosphere or more via the suction units 52a, 52b, and then exhaust the gas Gd2 whose pressure has been increased to 1 atmosphere or more.

[0038] Returning to FIG. 1 , the circulation device 60 is a device that circulates a refrigerant between the vaporizer 20 and at least the cooling section 54a of the separation device 30. The refrigerant (hereinafter referred to as "refrigerant Cm") circulated by the circulation device 60 may be of any type as long as it is capable of gasifying (or gasifying and heating) the liquefied natural gas LNG in the vaporizer 20 and cooling the treated gas Gp in the separation device 30. Specific examples of the refrigerant Cm include water (chiller water), oil, and antifreeze such as glycol. The circulation device 60 has a pump or the like for sending the refrigerant Cm to the vaporizer 20 and the separation device 30, respectively.

[0039] The circulation device 60 circulates the refrigerant Cm between at least the cooling section 54a of the separation device 30 and the vaporization device 20 so that the refrigerant Cm alternates between a temperature increase associated with cooling the treated gas Gp and a temperature decrease associated with gasification of the liquefied natural gas LNG. When the vaporization device 20 not only gasifies the liquefied natural gas LNG but also increases the temperature of the gas, the refrigerant Cm alternates between a temperature increase associated with cooling the treated gas Gp and a temperature decrease associated with gasification and temperature increase of the liquefied natural gas LNG. FIG. 2 shows a case where the refrigerant Cm is supplied to each of the cooling sections 54a, 54b, and 54c. The following describes a case where the treated gas Gp is ​​cooled by the refrigerant Cm in each of the cooling sections 54a, 54b, and 54c. An example will be given of a case where both gasification and temperature increase are performed in the vaporization device 20.

[0040] The circulation device 60 supplies the refrigerant Cm to the vaporization device 20 and recovers the refrigerant Cm after it has been used for gasification and temperature increase in the vaporization device 20. The temperature (first temperature) of the refrigerant Cm supplied from the circulation device 60 to the vaporization device 20 may be 5°C to 50°C, 8°C to 45°C, or 10°C to 40°C. In the vaporization device 20, all or part of the liquefied natural gas LNG supplied to the vaporization device 20 is gasified by removing heat from the refrigerant Cm. As the liquefied natural gas LNG is gasified and its temperature is increased after gasification, the temperature of the refrigerant Cm drops by approximately 5°C to 20°C.

[0041] The circulation device 60 supplies the refrigerant Cm to the cooling sections 54a, 54b, and 54c of the separation device 30 and recovers the refrigerant Cm after it has been used to cool the process gas Gp in the cooling sections 54a, 54b, and 54c. The circulation device 60 supplies the refrigerant Cm recovered from the vaporization device 20 to the cooling sections 54a, 54b, and 54c. The temperature (second temperature) of the refrigerant Cm supplied from the circulation device 60 to the cooling sections 54a, 54b, and 54c is lower than the temperature (first temperature) of the refrigerant Cm supplied from the circulation device 60 to the vaporization device 20. The temperature of the refrigerant Cm supplied from the circulation device 60 to the cooling sections 54a, 54b, and 54c may be lower than the temperature of the water-vapor-containing gas Gs supplied from the water-vapor-containing gas supply section 38 to the second space V2. The temperature of the refrigerant Cm supplied from the circulation device 60 to the cooling units 54a, 54b, and 54c may be 1°C to 20°C, 2°C to 15°C, or 3°C to 10°C.

[0042] In the cooling units 54a, 54b, and 54c, the refrigerant Cm removes heat from the process gas Gp, thereby cooling the process gas Gp. As a result, water vapor is removed from the process gas Gp. As the process gas Gp is ​​cooled, the temperature of the refrigerant Cm rises by approximately 5°C to 20°C. The circulation device 60 supplies the refrigerant Cm recovered from the cooling units 54a, 54b, and 54c to the vaporization device 20. As described above, the circulation device 60 is used to cool the process gas Gp in the cooling units 54a, 54b, and 54c, and supplies the refrigerant Cm, whose temperature has risen, to the vaporization device 20.

[0043] The circulation device 60 is used to gasify the liquefied natural gas LNG in the vaporizer 20 and to raise the temperature after gasification, and supplies the refrigerant Cm, after its temperature has been lowered, to the cooling sections 54a, 54b, 54c. The refrigerant Cm circulated by the circulation device 60 alternately increases in temperature as the treated gas Gp is ​​cooled in the cooling sections 54a, 54b, 54c, and decreases in temperature as the liquefied natural gas LNG is gasified and raised in temperature in the vaporizer 20. The refrigerant Cm may also be used to adjust the temperature of the raw material gas G0 supplied to the separation device 30 by exchanging heat with the raw material gas G0.

[0044] (Variation) FIG. 3 is a schematic diagram showing another example of a separation device. The separation device 30 shown in FIG. 3 has a discharge processing unit 50A instead of the discharge processing unit 50. The discharge processing unit 50A has two suction units and two cooling units. The discharge processing unit 50A differs from the discharge processing unit 50 shown in FIG. 2 in that it does not have the cooling unit 54c. In the discharge processing unit 50A, the processing gas Gp sucked and discharged by the suction unit 52b is discharged to the outside of the discharge processing unit 50A as gas Gd2. In the discharge processing unit 50A, the cooling units 54a and 54b cool the processing gas Gp using a refrigerant Cm supplied from the circulation device 60. Note that the cooling unit 54b may cool the processing gas Gp using another refrigerant instead of the refrigerant Cm.

[0045] The discharge processing unit 50, 50A has a plurality of suction units and a plurality of cooling units, but the number of these devices is not limited to the above example. The discharge processing unit 50, 50A may have one suction unit and one cooling unit. When the number of suction units and cooling units is the same, the number may be three or more. When the number of suction units is one less than the number of cooling units, the number of suction units may be one and the number of cooling units may be two. Alternatively, the number of suction units may be three or more and the number of cooling units may be four or more. The number of suction units may be set depending on the performance of each device and the target value of the pressure of the gas Gd2 (the use of the gas Gd2).

[0046] [Combustion system] Next, a case where the carbon dioxide capture device is applied to a combustion system that uses natural gas as fuel will be described. FIG. 4 is a schematic diagram showing an example of a combustion system. The combustion system 80 shown in FIG. 4 is a system that captures carbon dioxide while combusting liquefied natural gas. The combustion system 80 includes a capture device 10 and a combustion device 82. The combustion system 80 may also include a storage device 2.

[0047] The storage device 2 stores liquefied natural gas LNG and supplies the liquefied natural gas LNG to the vaporization device 20 of the recovery device 10. The storage device 2 is located, for example, at an LNG receiving terminal installed at a port or the like or in its vicinity. The storage device 2 may also be located at a location separate from the LNG receiving terminal (for example, a factory) and may store liquefied natural gas LNG transported from the LNG receiving terminal. In one example, the storage device 2 has a tank for storing liquefied natural gas LNG and a pump for sending the liquefied natural gas LNG to the vaporization device 20.

[0048] The vaporizer 20 gasifies and heats the liquefied natural gas LNG supplied from the storage device 2 using the refrigerant Cm supplied from the circulation device 60. The vaporizer 20 may gasify and heat the liquefied natural gas LNG using another refrigerant in addition to the refrigerant Cm. The vaporizer 20 supplies the natural gas Gn produced by gasifying and heating the liquefied natural gas LNG to the combustion device 82.

[0049] The combustion device 82 is a device that combusts natural gas Gn. The combustion device 82 is, for example, a boiler that generates hot water or steam by burning natural gas Gn. The combustion device 82 may generate hot water or steam by heating water or a heat transfer medium with combustion gas generated by burning natural gas Gn. The hot water or steam generated by the combustion device 82 may be used for any purpose. The combustion device 82 cools the combustion exhaust gas generated after heating water or the like by heat exchange with a refrigerant or the like as necessary (the part that performs the cooling is not shown), and then supplies the cooled combustion exhaust gas to the separation device 30. In this case, the raw material gas G0 supplied to the separation processing unit 40 of the separation device 30 includes the combustion exhaust gas discharged from the combustion device 82.

[0050] The separation treatment unit 40 separates carbon dioxide from the exhaust gas discharged from the combustion device 82 to generate a treated gas Gp. The separation treatment unit 40 of the separation device 30 discharges, as a gas Gd1, the gas remaining after carbon dioxide has been separated from the exhaust gas by the combustion device 82. The gas Gd1 may be released to the outside through a chimney installed in a factory or the like.

[0051] In this combustion system 80, the circulation device 60 also circulates the refrigerant Cm between the vaporization device 20 and at least the cooling section 54a (e.g., the cooling sections 54a, 54b, and 54c) of the separation device 30. The various modified examples described above may be applied to the recovery device 10 of the combustion system 80.

[0052] [Power generation system] Next, a case will be described in which the carbon dioxide capture device is applied to a power generation system that generates electricity (generates power) using liquefied natural gas. FIG. 5 is a schematic diagram showing an example of a power generation system. The power generation system 90 shown in FIG. 5 is a system that captures carbon dioxide while generating electricity using liquefied natural gas. The power generation system 90 includes a capture device 10 and a power generation device 92. The power generation system 90 may also include a storage device 2. The power generation system 90 is constructed, for example, at or near an LNG receiving terminal.

[0053] The vaporizer 20 gasifies the liquefied natural gas LNG to generate natural gas Gn, and supplies the natural gas Gn to the power generation device 92. The power generation device 92 may generate power using any method using the natural gas Gn. For example, the power generation device 92 may combust the natural gas Gn to generate steam, and then use the steam to rotate a steam turbine to operate a power generator. The power generation device 92 may also combust the natural gas Gn to generate combustion gas, and then use the combustion gas to rotate a gas turbine to operate a power generator. The power generation device 92 may also generate power using a power generation method (combined cycle power generation method) that combines these steam turbines and gas turbines.

[0054] The power generation device 92 cools the exhaust gas after generating steam or the exhaust gas after running the gas turbine by heat exchange with a refrigerant or the like as necessary (the part that performs the cooling is not shown), and then supplies the cooled exhaust gas to the separation device 30. In this case, the raw material gas G0 supplied to the separation treatment unit 40 of the separation device 30 includes the exhaust gas discharged from the power generation device 92. The separation treatment unit 40 separates carbon dioxide from the exhaust gas discharged from the power generation device 92 to generate a treated gas Gp. The separation treatment unit 40 discharges the gas remaining after carbon dioxide has been separated from the exhaust gas by the power generation device 92 as gas Gd1. The gas Gd1 may be released to the outside via a chimney installed in a power plant or the like.

[0055] In this power generation system 90, the circulation device 60 also circulates the refrigerant Cm between the vaporization device 20 and at least the cooling section 54a (e.g., the cooling sections 54a, 54b, and 54c) of the separation device 30. The various modified examples described above may be applied to the recovery device 10 of the power generation system 90.

[0056] Next, as an example of a method for recovering carbon dioxide, a method for recovering carbon dioxide from a raw material gas G0 using the above-mentioned recovery apparatus 10 will be described. The recovery method performed in the recovery apparatus 10 includes a separation process, a suction process, a discharge process, a cooling process, a gasification process, and a circulation process. These processes are performed in parallel so that at least a portion of their execution periods overlap with each other.

[0057] In the separation process, carbon dioxide is separated from the source gas G0 using the separation member 44 to generate a process gas Gp. Specifically, in the separation process, in the separation processing unit 40, the source gas G0 is supplied to a first space V1 within the housing 42. In addition to the supply of the source gas G0, a process is performed in which a water vapor-containing gas Gs is supplied from the water vapor-containing gas supply unit 38 to a second space V2 within the housing 42. Due to the pressure difference between the first space V1 and the second space V2 and the supply of the water vapor-containing gas Gs, the carbon dioxide and water vapor contained in the source gas G0 supplied to the first space V1 permeate the separation membrane 46 arranged to separate the first space V1 and the second space V2 and are introduced into the second space V2. As a result, a process gas Gp is ​​generated in the second space V2.

[0058] In the suction process, the suction units 52a and 52b suction the gas in the second space V2 so that the processing gas Gp is ​​discharged from the second space V2. By performing the suction process, the pressure difference between the first space V1 and the second space V2 occurs, and the separation process continues. In the cooling process, the processing gas Gp discharged from the second space V2 is cooled using a refrigerant Cm in at least the cooling unit 54a (e.g., each of the cooling units 54a, 54b, and 54c). In the cooling process, the refrigerant Cm may be supplied from the circulation device 60 to the cooling units 54a, 54b, and 54c. In the cooling process, the refrigerant Cm removes heat from the processing gas Gp, thereby cooling the processing gas Gp, and the temperature of the refrigerant Cm rises by about 5°C to 20°C.

[0059] In the discharge step, the gas that has been sucked from the second space V2 by the suction units 52a and 52b and from which water vapor has been removed by the cooling units 54a, 54b, and 54c is discharged as the above-mentioned gas Gd2. In the discharge step, the gas Gd2 may be discharged to the outside of the separation device 30. By discharging the gas Gd2, carbon dioxide is recovered.

[0060] In the gasification process, the liquefied gas is gasified using the refrigerant Cm in the vaporizer 20. In the gasification process, liquefied natural gas LNG, which is an example of liquefied gas, may be gasified (or may be gasified and heated). In the gasification process, the liquefied natural gas LNG is supplied to the vaporizer 20, and the refrigerant Cm is supplied from the circulation device 60. In the gasification process, the liquefied natural gas LNG absorbs heat from the refrigerant Cm, thereby regasifying the liquefied natural gas LNG. As a result, natural gas Gn is produced from the liquefied natural gas LNG. In the gasification process, the gas produced by regasifying the liquefied natural gas LNG may be heated by the refrigerant Cm. The natural gas Gn produced in the gasification process is supplied to the combustion system 80, the power generation system 90, etc.

[0061] In the circulation process, the refrigerant Cm circulates between the vaporizer 20 and the separator 30 (e.g., cooling sections 54a, 54b, 54c) so that the refrigerant Cm repeatedly rises in temperature as the treated gas Gp is ​​cooled and falls in temperature as the liquefied natural gas LNG is gasified and heated. By performing this circulation process, the refrigerant Cm, which has risen to the first temperature as the treated gas Gp is ​​cooled, is used to cool the liquefied natural gas LNG in the gasification process. In addition, the refrigerant Cm, which has fallen to the second temperature as the liquefied natural gas LNG is gasified and heated, is used to cool the treated gas Gp in the cooling process.

[0062] In the circulation step, the refrigerant Cm after being used in heat exchange with the treated gas Gp in the cooling step is recovered by the circulation device 60. The refrigerant Cm after being recovered from the cooling units 54a, 54b, 54c is supplied to the vaporization device 20 by the circulation device 60. The refrigerant Cm after being used in heat exchange with the liquefied natural gas LNG in the gasification step is recovered by the circulation device 60. The refrigerant Cm after being recovered from the vaporization device 20 is supplied to the cooling units 54a, 54b, 54c by the circulation device 60.

[0063] The above-described carbon dioxide capture method may also be performed in a combustion system 80 equipped with the capture device 10. In the combustion system 80, a combustion process is performed in addition to the separation process, suction process, discharge process, cooling process, gasification process, and circulation process included in the above-described capture method. The combustion process burns natural gas Gn obtained by gasifying liquefied natural gas LNG in the gasification process. In the combustion process, water or the like may be heated using the natural gas Gn as fuel. In the separation process, the raw material gas G0 supplied to the separation device 30 includes the exhaust gas discharged in the combustion process.

[0064] The above-described carbon dioxide capture method may also be performed in a power generation system 90 equipped with the capture device 10. In the power generation system 90, a power generation process is performed in addition to the separation process, suction process, discharge process, cooling process, gasification process, and circulation process included in the above-described capture method. In the power generation process, natural gas Gn obtained by gasifying liquefied natural gas LNG in the gasification process is combusted to generate electricity. In the separation process, the raw material gas G0 supplied to the separation device 30 includes the exhaust gas discharged in the power generation process.

[0065] [Effects of the embodiment] The recovery device 10 according to the embodiment described above comprises a separation processing unit 40 that separates the carbon dioxide contained in the raw gas G0 from the raw gas G0 using a carbon dioxide-permeable membrane, an suction unit 52a that sucks in a treatment gas Gp containing the carbon dioxide separated from the raw gas G0, a cooling unit 54a that is arranged upstream of the suction unit 52a and cools the treatment gas Gp using a refrigerant Cm, an evaporation device 20 that gasifies the liquefied gas using the refrigerant Cm, and a circulation device 60 that circulates the refrigerant Cm between the cooling unit 54a and the evaporation device 20 so that the refrigerant Cm repeatedly rises in temperature due to cooling of the treatment gas Gp and falls in temperature due to gasification of the liquefied gas.

[0066] In this recovery device 10, by circulating the refrigerant Cm between the vaporizer 20 and the cooling unit 54a, the cold energy generated when evaporating the liquefied gas (e.g., the cold energy generated during gasification and temperature rise) can be used to cool the treatment gas Gp released from the second space V2. This further reduces the temperature of the treatment gas Gp before it is sucked into the suction unit 52a, condensing and removing much of the moisture contained in the treatment gas Gp. This reduces the performance required of the suction unit 52a. This makes it possible to reduce the energy consumption required to recover carbon dioxide.

[0067] The temperature of the refrigerant Cm supplied from the circulation device 60 to the cooling unit 54a may be 1°C to 20°C. When the refrigerant Cm has the above temperature, it can remove a large amount of heat from the process gas Gp before being sucked by the suction unit 52a, and the amount of moisture removed from the process gas Gp can be increased. Therefore, it is possible to reduce the amount of energy required to recover gas containing carbon dioxide.

[0068] The recovery apparatus 10 may further include a water vapor-containing gas supply unit 38 that supplies a water vapor-containing gas Gs containing water vapor to the separation processing unit 40. The separation processing unit 40 may have a membrane arranged to separate the first space V1, to which the raw material gas G0 is supplied, from the second space V2. The water vapor-containing gas supply unit 38 may supply the water vapor-containing gas Gs to the second space V2. Supplying the water vapor-containing gas Gs to the second space V2 promotes separation of carbon dioxide by the membrane. As a result of the supply of a gas containing water vapor, the treatment gas Gp generated in the second space V2 may contain a large amount of water vapor, but by utilizing the cold heat, a large amount of water vapor can be removed from the treatment gas Gp. Therefore, it is possible to achieve both efficient separation of carbon dioxide and a reduction in the amount of energy required for recovery.

[0069] The recovery device 10 may further include a cooling unit 54b disposed downstream of the suction unit 52a and configured to cool the gas discharged by the suction unit 52a using a refrigerant Cm, and a suction unit 52b disposed downstream of the cooling unit 54b and configured to suck the gas discharged by the suction unit 52a. The provision of multiple suction units including the suction units 52a and 52b facilitates increasing the pressure of the gas. Therefore, gas in which carbon dioxide is concentrated and the pressure is increased can be easily obtained.

[0070] The pressure of the gas discharged from the recovery device 10 via at least the suction units 52a and 52b may be 1 atmosphere or more. By setting the pressure of the gas discharged from the recovery device 10 to 1 atmosphere or more, the gas recovered from the recovery device 10 can be easily sent from the recovery device 10 to another device or another location.

[0071] The liquefied gas may be liquefied natural gas (LNG). Even when liquefied natural gas (LNG) is vaporized using a refrigerant (Cm), the cold generated when vaporizing the liquefied natural gas (LNG) can be used to cool the treated gas (Gp) released from the second space (V2). This further reduces the temperature of the treated gas (Gp) before it is drawn into the suction section (52a), increasing the amount of moisture condensing in the treated gas (Gp) and allowing a large amount of moisture to be removed. This reduces the performance required of the suction section (52a). This makes it possible to reduce the energy consumption required to capture carbon dioxide.

[0072] [Simulation Results] Next, a description will be given of the results of a simulation of the energy consumption required to capture carbon dioxide in the capture device 10 shown in Figures 1 and 2. For each of the following Reference Example 1, Reference Example 2, Example 1, and Example 2, an evaluation (simulation) of the energy consumption required to capture 1 ton of carbon dioxide when capturing gas with a carbon dioxide concentration of about 95% or more was performed. Reference Example 1 is a case in which carbon dioxide is captured by a chemical absorption method, and Reference Example 2 and Examples 1 and 2 are cases in which carbon dioxide is captured by a membrane separation method.

[0073] Reference Example 2 is a case in which carbon dioxide concentration in the combustion flue gas is relatively high, and carbon dioxide is recovered from coal combustion flue gas using general cooling water by membrane separation. Example 1 is a case in which the refrigerant in Reference Example 2 is changed from general cooling water to refrigerant Cm circulated between the vaporizer 20. Example 2 is a case in which the carbon dioxide concentration in the natural gas combustion flue gas is relatively low, and carbon dioxide is recovered from the combustion flue gas using refrigerant Cm by membrane separation. Reference Example 2 does not have the vaporizer 20 and circulation device 60 shown in Figures 1 and 2, and was evaluated using a configuration in which general cooling water circulated between the vaporizer 20 and the separation device 30. Examples 1 and 2 were evaluated using the device configuration shown in Figures 1 and 2. The main differences between Reference Examples 1 and 2 and Examples 1 and 2, and the evaluation results, are shown in Table 1. [Table 1]

[0074] Details of Reference Examples 1 and 2 and Examples 1 and 2 are described below. In Reference Example 1, an evaluation value of energy consumption was obtained with reference to the separation and recovery energy of the atmospheric pressure chemical absorption liquid shown in the above-mentioned Non-Patent Document 1. For Reference Example 2 and Examples 1 and 2, the main prerequisites for the simulation and the calculation results are shown in Table 2, and the calculation process and calculation results for the carbon dioxide recovery energy are shown in Table 3.

[0075] [Table 2]

[0076] [Table 3]

[0077] The main energy consumption in Reference Example 2 and Examples 1 and 2 is considered to be the power consumption by the motor for operating the suction device (suction sections 52a, 52b) in the suction process, etc., and the power consumption required by the motor for operating the pump that circulates the refrigerant in the circulation device. The main energy consumption in Reference Example 1 is the thermal energy for generating steam used to regenerate the chemical absorption liquid. In Reference Examples 1 and 2 and Examples 1 and 2, the energy required for carbon dioxide recovery must be compared equally as thermal energy, in line with Reference Example 1. Therefore, in Reference Example 2 and Examples 1 and 2, the thermal energy required for power generation to supply power consumption is calculated and compared with the thermal energy in Reference Example 1.

[0078] In Reference Example 2 and Examples 1 and 2, the required power is assumed to be supplied from a power plant emitting the combustion exhaust gas assumed in each example. The coal-fired power plant has a gross power generating efficiency of approximately 40% based on the lower heating value (LHV), and the natural gas-fired power plant also has a gross power generating efficiency of approximately 40% based on the LHV. Furthermore, the thermal energy required to supply the required power was calculated assuming a transmission and distribution loss of approximately 5%.

[0079] From the evaluation results in Table 1 or Table 3, it can be seen that in Reference Example 2, in which normal cooling water was used as the refrigerant, the energy consumption was reduced by about 35% compared to Reference Example 1. It can also be seen that in Examples 1 and 2, in which the refrigerant Cm circulated by the circulation device 60 was used as the refrigerant, the energy consumption was reduced by more than half compared to Reference Example 1. [Explanation of symbols]

[0080] 10...recovery device, 20...vaporization device, 30...separation device, 38...water vapor-containing gas supply section, 40...separation treatment section, 46...separation membrane, V1...first space, V2...second space, 50, 50A...discharge treatment section, 52a, 52b...suction section, 54a, 54b, 54c...cooling section, 60...circulation device, 80...combustion system, 82...combustion device, 90...power generation system, 92...power generation device, G0...raw material gas, Gp...treated gas, Gs...water vapor-containing gas, LNG...liquefied natural gas, Gn...natural gas, Cm...refrigerant

Claims

1. a separation processing unit that separates carbon dioxide contained in the raw material gas from the raw material gas using a carbon dioxide permeable membrane; an intake unit that intakes a treatment gas containing carbon dioxide separated from the raw material gas; a cooling unit disposed upstream of the suction unit and configured to cool the processing gas using a refrigerant; an evaporation unit that gasifies a liquefied gas using the refrigerant; A carbon dioxide recovery device comprising: a circulation unit that circulates the refrigerant between the cooling unit and the evaporation unit so that the refrigerant repeatedly undergoes a temperature increase due to cooling of the treated gas and a temperature decrease due to gasification of the liquefied gas.

2. 2. The recovery device according to claim 1, wherein the temperature of the refrigerant supplied from the circulation section to the cooling section is 1°C to 20°C.

3. The apparatus further includes a water vapor-containing gas supply unit that supplies a water vapor-containing gas containing water vapor to the separation treatment unit, the separation processing unit has the membrane arranged to separate a first space to which the source gas is supplied from a second space, The recovery apparatus according to claim 1 or 2, wherein the water vapor-containing gas supply unit supplies the water vapor-containing gas to the second space.

4. Another cooling unit is arranged downstream of the suction unit and cools the gas discharged by the suction unit using the refrigerant; The recovery device according to any one of claims 1 to 3, further comprising: another suction section arranged downstream of the other cooling section and configured to suck in the gas released by the suction section.

5. 5. The recovery device according to claim 4, wherein the pressure of the gas discharged from the recovery device via at least the suction part and the another suction part is 1 atmosphere or more.

6. The recovery device according to any one of claims 1 to 5, wherein the liquefied gas is liquefied natural gas.

7. The recovery device according to claim 6 ; a combustion device that combusts natural gas obtained by gasifying the liquefied natural gas in the vaporization unit, A combustion system, wherein the raw material gas supplied to the separation processing unit includes exhaust gas discharged from the combustion device.

8. The recovery device according to claim 6 ; a power generation device that generates electricity by combusting natural gas obtained by gasifying the liquefied natural gas in the vaporization unit, The power generation system, wherein the raw material gas supplied to the separation processing unit includes an exhaust gas discharged from the power generation device.

9. a separation step of separating carbon dioxide contained in a raw material gas from the raw material gas using a carbon dioxide permeable membrane; a suction step of suctioning a treatment gas containing carbon dioxide separated from the raw material gas; a cooling step of cooling the treatment gas using a refrigerant upstream of the suction step; a gasification step of gasifying a liquefied gas using the refrigerant; a circulation step of circulating the refrigerant so that the refrigerant repeatedly undergoes a temperature increase associated with cooling of the treated gas and a temperature decrease associated with gasification of the liquefied gas.

10. 10. The method of claim 9, wherein the liquefied gas is liquefied natural gas.

11. The method further includes a combustion step of combusting natural gas obtained by gasifying the liquefied natural gas in the gasification step, The recovery method according to claim 10 , wherein the raw material gas includes an exhaust gas discharged in the combustion step.

12. The method further includes a power generation step of generating electricity by combusting natural gas obtained by gasifying the liquefied natural gas in the gasification step, The recovery method according to claim 10 , wherein the raw material gas includes an exhaust gas discharged in the power generation process.

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