Method for recovering acidic gas

Abstract

Provided is a method for recovering an acid gas, which is capable of suppressing oxidative degradation of an acid gas-adsorbing material and wear caused by volatilization. A method for recovering an acid gas according to an embodiment of the present invention comprises, in this order, an adsorption step, a desorption step, and a cooling step. In the adsorption step, a gas to be treated containing an acid gas is supplied to an acid gas adsorption device containing an acid gas adsorption material, and the acid gas is adsorbed to the acid gas adsorption material. In the desorption step, the acid gas adsorption device is heated to desorb the acid gas from the acid gas adsorption material. In the cooling step, the acid gas adsorption device is cooled by using a cooling medium having a temperature lower than the outside air temperature.

Description

Technical Field

[0001] The invention relates to a method for recovering acidic gas. Background Art

[0002] In recent years, efforts have been made to separate and recover the acidic gases contained in the atmosphere in order to reduce the environmental load. As such an acidic gas, carbon dioxide (hereinafter sometimes referred to as CO2) which causes global warming can be mainly cited. As a representative example of the above efforts, the carbon dioxide capture, utilization and storage (CCUS) cycle is known. As a carbon dioxide adsorption device used in such separation and recovery of carbon dioxide, a gas separation unit has been proposed, which has an adsorption material layer filled with a granular carbon dioxide adsorption material (for example, see Patent Document 1). In such a gas separation unit, the granular carbon dioxide adsorption material adsorbs CO2 from the gas fluid passing through the adsorption material layer at a predetermined adsorption temperature, and when heated to a desorption temperature exceeding the adsorption temperature, the adsorbed CO2 is desorbed. In the gas separation unit described in Patent Document 1, when the CO2 adsorption is restarted after the CO2 is desorbed, the adsorption material layer is cooled from the desorption temperature to the adsorption temperature using the external atmosphere (atmosphere). Therefore, it takes time to cool the adsorbent layer, and sometimes it is not possible to solve the oxidative degradation of the carbon dioxide adsorbent due to oxygen contained in the external atmosphere and the wear caused by the volatilization of the carbon dioxide adsorbent.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2014 / 170184 Summary of the invention

[0006] A main object of the present invention is to provide a method for recovering acid gas that can suppress oxidative degradation of an acid gas adsorbent and abrasion due to volatilization.

[0007] [1] The acid gas recovery method according to an embodiment of the present invention includes: an adsorption step, a desorption step, and a cooling step in sequence. In the adsorption step, a gas to be treated containing acid gas is supplied to an acid gas adsorption device including an acid gas adsorption material, so that the acid gas is adsorbed by the acid gas adsorption material. In the desorption step, the acid gas adsorption device is heated so that the acid gas is desorbed from the acid gas adsorption material. In the cooling step, the acid gas adsorption device is cooled using a cooling medium having a lower temperature than the outside air temperature.

[0008] [2] In the method for recovering acidic gas described in [1] above, the acidic gas may be carbon dioxide.

[0009] [3] In the acid gas recovery method described in [1] or [2] above, in the cooling step, a cooling gas serving as the cooling medium may be passed through the acid gas adsorption device.

[0010] [4] In the acid gas recovery method described in any one of [1] to [3] above, the oxygen concentration in the cooling gas may be lower than the oxygen concentration in the gas to be treated.

[0011] [5] In the acid gas recovery method described in any one of [1] to [4] above, the flow rate of the cooling gas in the cooling step may be smaller than the flow rate of the gas to be treated in the adsorption step.

[0012] [6] In the acid gas recovery method described in any one of [1] to [5] above, the acid gas adsorption device may include a honeycomb substrate and an acid gas adsorption layer. The honeycomb substrate includes partitions defining a plurality of cells. The acid gas adsorption layer includes the acid gas adsorption material. The acid gas adsorption layer is formed on the surface of the partitions.

[0013] [7] In the acid gas recovery method described in [6] above, in the cooling step, a cooling gas serving as the cooling medium may be passed through the compartment.

[0014] [8] In the acid gas recovery method described in [6] or [7] above, in the cooling step, a liquid refrigerant as the cooling medium may be brought into contact with the honeycomb substrate.

[0015] [9] In the acid gas recovery method described in any one of [1] to [8] above, the temperature of the acid gas adsorption device may be monitored during the cooling step, thereby supplying a cooling medium to the acid gas adsorption device until the acid gas adsorption device is cooled to a desired cooling temperature.

[0016] Effects of the Invention

[0017] According to the embodiment of the present invention, it is possible to realize a method for recovering acid gas that can suppress oxidative degradation of an acid gas adsorbent and abrasion due to volatilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic configuration diagram of an acid gas adsorption device according to an acid gas recovery method according to one embodiment of the present invention.

[0019] Figure 2This is a schematic perspective view of an acid gas adsorption device involved in an acid gas recovery method according to another embodiment of the present invention.

[0020] Figure 3 yes Figure 2 A schematic cross-sectional view of an acid gas adsorption device.

[0021] Figure 4 Yes Figure 2 This is a schematic diagram of the acid gas recovery system of the acid gas adsorption device in FIG.

[0022] Figure 5 This is a schematic configuration diagram of an acid gas recovery system according to another embodiment. DETAILED DESCRIPTION

[0023] A. Overview of acid gas recovery methods

[0024] A method for recovering acid gas according to one embodiment of the present invention includes, in sequence, an adsorption step, a desorption step, and a cooling step. Typically, the method for recovering acid gas repeatedly performs the adsorption step, the desorption step, and the cooling step in sequence. In the adsorption step, a gas to be treated containing acid gas is supplied to an acid gas adsorption device including an acid gas adsorption material, so that the acid gas is adsorbed by the acid gas adsorption material. In the desorption step, the acid gas adsorption device is heated so that the acid gas is desorbed from the acid gas adsorption material. In the cooling step, the acid gas adsorption device is cooled using a cooling medium having a lower temperature than the outside air.

[0025] At the beginning of the cooling process, the acid gas adsorption device is typically heated to a relatively high temperature desorption temperature. If the acid gas adsorption device is cooled to a temperature at which the adsorption process can be carried out using the external atmosphere (atmosphere) in this state, the acid gas adsorption material may be oxidatively degraded, resulting in a decrease in the adsorption capacity of the acid gas. Therefore, it is studied to shorten the cooling time of the acid gas adsorption device by increasing the flow rate of the external atmosphere, thereby shortening the time that the acid gas adsorption material is exposed to high temperature. In this case, although the oxidative degradation of the acid gas adsorption material can be suppressed, there is a problem of accelerated wear caused by the volatilization of the acid gas adsorption material.

[0026] In contrast, in one embodiment of the present invention, the acid gas adsorbing device can be smoothly cooled by a cooling medium having a lower temperature than the outside air. Therefore, compared with the case where the acid gas adsorbing device is cooled by the outside air (atmosphere), the implementation time of the cooling process can be shortened without increasing the flow rate of the cooling medium. Therefore, the oxidative degradation of the acid gas adsorbing material and the wear caused by volatilization can be suppressed. In addition, since the implementation time of the cooling process can be shortened, the implementation time of one cycle including the adsorption process, the desorption process, and the cooling process can be shortened.

[0027] In the adsorption process, typically, a gas to be treated containing acidic gas is supplied to an acidic gas adsorption device at a predetermined adsorption temperature, and the acidic gas contacts the acidic gas adsorbent, whereby the acidic gas adsorbent adsorbs the acidic gas.

[0028] As the acidic gas contained in the gas to be treated, for example, there can be mentioned: carbon dioxide (CO2), hydrogen sulfide, sulfur dioxide, nitrogen dioxide, dimethyl sulfide (DMS), hydrogen chloride, etc. In one embodiment, the acidic gas is carbon dioxide (CO2), and the gas to be treated is a CO2-containing gas. The CO2-containing gas may contain nitrogen in addition to CO2. The CO2-containing gas is representatively air (atmosphere). The CO2 concentration in the CO2-containing gas is, for example, greater than 100 ppm (volume basis) and less than 2 volume %.

[0029] The temperature of the gas to be treated supplied to the acid gas adsorption device is, for example, 0° C. or higher and 50° C. or lower, and is preferably the same as the outside air temperature.

[0030] The temperature of the acid gas adsorption device in the adsorption process (adsorption temperature) is, for example, 0° C. or more, preferably 10° C. or more, for example, 50° C. or less, preferably 40° C. or less. In one embodiment, the adsorption temperature is the same as the external air temperature. The implementation time of the adsorption process (adsorption time) is, for example, 15 minutes or more, preferably 30 minutes or more, for example, 3 hours or less, preferably 2 hours or less.

[0031] When the adsorption temperature and / or the adsorption time are within the above ranges, the acid gas adsorbent can efficiently adsorb the acid gas.

[0032] The ratio of the adsorption time to the total execution time of the adsorption step, the desorption step, and the cooling step is, for example, 30% or more, or preferably 50% or more.

[0033] When the ratio of the adsorption time is equal to or greater than the above lower limit, the acid gas adsorbent can efficiently adsorb the acid gas. The upper limit of the ratio of the adsorption time is not particularly limited, but is typically 80% or less.

[0034] The acid gas recovery rate in the adsorption process (=100-(acid gas concentration in the gas to be treated that has passed through the acid gas adsorption device / acid gas concentration in the gas to be treated before being supplied to the acid gas adsorption device×100)) is, for example, 60% or more, preferably 75% or more, more preferably 80% or more, for example 90% or less.

[0035] In the desorption step, the acid gas adsorption device is typically heated to a desorption temperature exceeding the adsorption temperature. More specifically, in the desorption step, the acid gas adsorption device is heated to the desorption temperature and then maintained at the desorption temperature for a predetermined desorption time.

[0036] Thus, the acid gas adsorbed by the acid gas adsorbent in the adsorption step is desorbed from the acid gas adsorbent. Therefore, the desorbed acid gas can be recovered.

[0037] In one embodiment, the desorbed gas is supplied to the acid gas adsorption device, and the desorbed acid gas is recovered together with the desorbed gas. Examples of the desorbed gas include: air, carbon dioxide, water vapor, nitrogen, argon, and gas recovered in the desorbing process. These desorbed gases may be used alone, or may be mixed or used in combination.

[0038] The gas recovered in the desorption process is sometimes referred to as recovered gas. As the desorption gas, preferably, the recovered gas previously recovered by the acid gas adsorption device can be cited. By using the recovered gas as the desorption gas, the acid gas concentration in the recovered gas can be increased. The temperature of the desorption gas supplied to the acid gas adsorption device is, for example, 60° C. or more, preferably 90° C. or more, for example, 200° C. or less, preferably 160° C. or less.

[0039] It should be noted that in the desorption process, the acid gas may be recovered without using the desorption gas. For example, the desorption acid gas may be recovered by suctioning the desorption acid gas with a decompression pump. Alternatively, the desorption gas and the decompression pump may be used in combination.

[0040] The temperature of the acid gas adsorbent in the desorption process (desorption temperature) is, for example, 70° C. or more, preferably 80° C. or more, for example, 200° C. or less, preferably 110° C. or less. The implementation time of the desorption process (desorption time during which the acid gas adsorbent is maintained at the desorption temperature) is, for example, 1 minute or more, preferably 5 minutes or more, for example, 1 hour or less, preferably 30 minutes or less. When the desorption temperature and / or the desorption time are within the above ranges, oxidative degradation and volatilization of the acid gas adsorbent can be suppressed.

[0041] The ratio of the desorption time to the total of the implementation time of the adsorption step, the desorption step, and the cooling step is, for example, 5% or more, preferably 10% or more, for example, 50% or less, preferably 25% or less. If the ratio of the desorption time is above the lower limit, the acid gas can be sufficiently desorbed from the acid gas adsorbent, and if the ratio of the desorption time is below the upper limit, the ratio of the adsorption time in the implementation time of one cycle including the adsorption step, the desorption step, and the cooling step can be stably ensured.

[0042] In the cooling process, typically, the acid gas adsorption device after the desorption process is cooled to a desired cooling temperature using a cooling medium lower than the outside air temperature. The temperature of the cooling medium supplied to the acid gas adsorption device is lower than the outside air temperature and can cool the acid gas adsorption device to a cooling temperature described below, and there is no particular limitation. The temperature of the cooling gas is not limited as long as it does not cause condensation, and is, for example, below -5°C of the outside air temperature, preferably below -10°C of the outside air temperature.

[0043] Examples of the cooling medium include cooling gas and liquid refrigerant, and preferably cooling gas. In one embodiment, in the cooling step, cooling gas is passed through the acid gas adsorption device.

[0044] Examples of the cooling gas include atmospheric air, carbon dioxide, nitrogen, and argon. When the cooling gas is atmospheric air, in the cooling step, air from the outside atmosphere is blown into the acid gas adsorbing device to cool the acid gas adsorbing device.

[0045] The oxygen concentration in the cooling gas is preferably lower than the oxygen concentration in the gas to be treated. The oxygen concentration of the cooling gas supplied to the acid gas adsorption device in the cooling process is, for example, 15% by volume or less, preferably 5% by volume or less, for example, 0% by volume or more. For example, the oxygen concentration can be measured by an electrochemical method (zirconium dioxide method and electrode method) according to the method described in JIS B7983. It should be noted that the oxygen concentration of the gas to be treated supplied to the acid gas adsorption device in the adsorption process is, for example, more than 15% by volume, preferably 20% by volume or more, for example, 30% by volume or less.

[0046] When the oxygen concentration of the cooling gas is lower than the oxygen concentration of the gas to be treated, volatilization of the adsorbent due to temperature is inevitable, but degradation of the acid gas adsorbent can be suppressed and the acid gas adsorbent can be cooled smoothly.

[0047] The cooling gas supplied to the acid gas adsorption device may be at normal pressure (1.0×10 5 PaA (absolute pressure)), it can be pressurized or depressurized. The pressure of the cooling gas is, for example, 2.0×10 5PaA (absolute pressure) or less, for example, normal pressure (1.0×10 5 PaA) or less, and for example, 5.0×10 4 On the other hand, the pressure of the cooling gas is, for example, 0.1×10 4 PaA or more, for example, 0.3×10 5 PaA or above.

[0048] In one embodiment, the cooling gas is decompressed to a pressure lower than normal pressure. This can reduce the oxygen partial pressure in the cooling gas, and further suppress oxidative degradation of the acidic gas adsorbent.

[0049] The oxygen partial pressure in the cooling gas is, for example, 15 kPa or less, preferably 5 kPa or less, for example, 0 Pa or more. The oxygen partial pressure of the gas to be treated supplied to the acid gas adsorption device in the adsorption step is, for example, 15 kPa or more, preferably 20 kPa or more, for example, 30 kPa or less.

[0050] In addition, in the cooling step, the pressure of the cooling gas supplied to the acid gas adsorption device may be constant or may be changed. In one embodiment, in the cooling step, after the reduced pressure cooling gas is supplied to the acid gas adsorption device, the cooling gas at normal pressure is supplied to the acid gas adsorption device, thereby cooling the acid gas adsorption device to a desired cooling temperature.

[0051] In one embodiment, the flow rate of the cooling gas in the cooling process (flow rate x cooling time; hereinafter referred to as the cooling gas flow rate) is smaller than the flow rate of the gas to be treated in the adsorption process (flow rate x adsorption time; hereinafter referred to as the gas to be treated flow rate). This can further suppress the wear caused by the volatilization of the acid gas adsorbent.

[0052] The ratio of the flow rate of the gas to be treated to the flow rate of the cooling gas (flow rate of the gas to be treated / flow rate of the cooling gas) is, for example, 0.1 or more, preferably 1 or more, more preferably 10 or more, for example, 100 or less.

[0053] The flow rate of the cooling gas is, for example, 0.001 m / s to 20 m / s, preferably 0.1 m / s to 10 m / s. For example, the flow rate of the gas can be measured by the method described in JIS B 7556 using an ultrasonic flow meter or the like. If the flow rate of the cooling gas is in such a range, the implementation time of the cooling process (cooling time) can be shortened, and as a result, the implementation time of one cycle including the adsorption process, the desorption process and the cooling process can be shortened. It should be noted that the flow rate of the gas to be treated is, for example, 0.1 m / s to 30 m / s, preferably 0.5 m / s to 10 m / s.

[0054] The cooling temperature is, for example, 0° C. or more, preferably 20° C. or more, for example, 60° C. or less, preferably 50° C. or less. If the cooling temperature is within the above range, the implementation time (cooling time) of the cooling process can be stably shortened. The cooling time is, for example, 5 minutes or more, preferably 10 minutes or more, for example, 60 minutes or less, preferably 30 minutes or less.

[0055] In one embodiment, the cooling temperature (the temperature of the acid gas adsorption device at the end of the cooling process) exceeds the adsorption temperature. In this case, the cooling time can be shortened. In addition, even if the cooling temperature exceeds the adsorption temperature, when the adsorption process starts, the acid gas adsorption device is cooled to the adsorption temperature by the supplied gas to be treated. Therefore, the cooling time can be shortened, and the adsorption process can be stably performed.

[0056] The ratio of the cooling time to the total time of the adsorption step, the desorption step, and the cooling step is, for example, 50% or less, or preferably 30% or less.

[0057] If the ratio of the cooling time is below the upper limit, the implementation time of one cycle including the adsorption step, the desorption step and the cooling step can be stably shortened, and the adsorption amount of the acid gas per unit time in the cycle can be further increased. The lower limit of the ratio of the cooling time is not particularly limited, and is typically 25% or more.

[0058] Hereinafter, embodiments of the present invention will be described with reference to the drawings; however, the present invention is not limited to these embodiments.

[0059] B. Acid gas adsorption device (carbon dioxide adsorption device)

[0060] Figure 1 is a schematic diagram of the structure of an acid gas adsorption device involved in an acid gas recovery method according to one embodiment of the present invention. Figure 2 is a schematic perspective view of an acid gas adsorption device involved in an acid gas recovery method according to another embodiment of the present invention. Figure 3 yes Figure 2 A schematic cross-sectional view of an acid gas adsorption device.

[0061] B-1. First Embodiment of Acid Gas Adsorption Device

[0062] In one embodiment, if Figure 1 As shown, the acid gas adsorbing device 7 includes a plurality of adsorbent layers 71. The plurality of adsorbent layers 71 constitute the acid gas adsorbing section 19. When the gas to be treated by the acid gas adsorbing device is a CO2-containing gas, the acid gas adsorbing device 7 is a carbon dioxide adsorbing device 7a.

[0063] The plurality of adsorbent layers 71 are stacked with a gap in the thickness direction thereof. In the example shown in the figure, five adsorbent layers 71 are arranged in parallel, but the number of adsorbent layers 71 is not limited thereto. The number of adsorbent layers 71 is, for example, 5 or more, preferably 10 or more, and more preferably 20 or more. The gap between adjacent adsorbent layers 71 in the plurality of adsorbent layers 71 is, for example, 0.5 cm or more and 1.5 cm or less.

[0064] Each of the plurality of adsorbent layers 71 includes a flexible fiber member 73 and a plurality of granular adsorbents 72 .

[0065] The flexible fiber component 73 allows the passage of the gas to be treated and restricts the passage of the granular adsorbent material. Typically, the flexible fiber component 73 is formed into a hollow shape (bag shape) capable of accommodating a plurality of granular adsorbent materials 72. The flexible fiber component 73 may be a fabric or a non-woven fabric. Examples of the material of the flexible fiber component 73 include organic fibers and natural fibers, preferably polyethylene terephthalate fibers, polyethylene fibers, and cellulose fibers. The thickness of the flexible fiber component 73 is, for example, not less than 25 μm and not more than 500 μm.

[0066] A plurality of granular adsorbent materials 72 are filled in the interior of a flexible fiber member 73 having a hollow shape (bag shape). The granular adsorbent material 72 functions as an acid gas adsorbent, and typically functions as a carbon dioxide adsorbent. As the material of the granular adsorbent 72, for example, an amine-modified material can be cited, preferably amine-modified cellulose can be cited, and more preferably amine-modified nanofibrillated cellulose can be cited. The average primary particle size of the granular adsorbent material 72 is, for example, not less than 60 μm and not more than 1200 μm. The filling ratio of the granular adsorbent material 72 in the adsorbent layer 71 can adopt any appropriate value.

[0067] The acid gas adsorption device 7 shown in the figure further includes a plurality of spacers 74. The spacers 74 are sandwiched between the adjacent adsorption material layers 71 among the plurality of adsorption material layers 71. The plurality of spacers 74 constitute the acid gas adsorption unit 19. Thus, the intervals between the adjacent adsorption material layers can be stably ensured. In one embodiment, the plurality of adsorption material layers 71 and the plurality of spacers 74 are arranged such that: from a direction orthogonal to the thickness direction of the adsorption material layer 71 ( Figure 1 When viewed in the depth direction of the paper, it becomes a roughly Z shape.

[0068] As such an acid gas adsorption device 7, for example, there can be mentioned a gas separation unit described in International Publication No. 2014 / 170184, the entire contents of which are incorporated herein by reference.

[0069] B-2. Second Embodiment of Acid Gas Adsorption Device

[0070] In another embodiment, if Figure 2 and Figure 3 As shown, the acid gas adsorption device 1 includes a substrate 10 and an acid gas adsorption layer 15. The substrate 10 and the acid gas adsorption layer 15 constitute an acid gas adsorption unit 19. When the gas to be treated by the acid gas adsorption device is a CO2-containing gas, the acid gas adsorption device 1 is a carbon dioxide adsorption device 1a.

[0071] The structure of the substrate 10 is not particularly limited, and examples thereof include a honeycomb structure, a filter structure such as filter cloth, and a particle structure. The acid gas adsorption layer 15 may be disposed on the surface of the substrate 10 and is not particularly limited.

[0072] B-2-1. Base material (honeycomb base material)

[0073] In one embodiment, the substrate 10 is a honeycomb substrate 10 a . The honeycomb substrate 10 a includes partition walls 13 defining a plurality of cells 14 .

[0074] The cells 14 extend from the first end face E1 (inflow end face) to the second end face E2 (outflow end face) of the honeycomb substrate 10a in the longitudinal direction (axial direction) of the honeycomb substrate 10a (see Figure 3 ). The cell 14 has any appropriate shape in the cross section of the honeycomb substrate 10a in a direction perpendicular to the length direction. Examples of the cross-sectional shape of the cell include: a triangle, a quadrilateral, a pentagon, a polygon larger than a hexagon, a circle, and an ellipse. The cross-sectional shape and size of the cell may be all the same or at least partially different. Among the cross-sectional shapes of such cells, preferably a hexagon or a quadrilateral can be mentioned, and more preferably a square, a rectangle or a hexagon can be mentioned.

[0075] The cell density in the cross section of the honeycomb substrate in a direction perpendicular to the longitudinal direction (i.e., the number of cells 14 per unit area) can be appropriately set according to the purpose. For example, the cell density can be 4 cells / cm 2 ~320 compartments / cm 2 When the cell density is within such a range, the strength and effective GSA (geometric surface area) of the honeycomb substrate can be sufficiently ensured.

[0076] The honeycomb substrate 10a has any appropriate shape (overall shape). Examples of the shape of the honeycomb substrate include: a cylindrical shape with a circular bottom surface, an elliptical cylindrical shape with an elliptical bottom surface, a prism shape with a polygonal bottom surface, and a column shape with an irregular bottom surface. The honeycomb substrate 10a shown in the figure has a cylindrical shape. The outer diameter and length of the honeycomb substrate can be appropriately set according to the purpose. Although not shown in the figure, the honeycomb substrate may have a hollow area in the center of the cross section in a direction perpendicular to the longitudinal direction.

[0077] Typically, the honeycomb substrate 10a includes an outer peripheral wall 11 and partition walls 13 located inside the outer peripheral wall 11. In the example shown in the figure, the outer peripheral wall 11 and the partition walls 13 are formed integrally. The outer peripheral wall 11 and the partition walls 13 may be separate bodies.

[0078] The outer peripheral wall 11 has a cylindrical shape. The thickness of the outer peripheral wall 11 can be set arbitrarily and appropriately. The thickness of the outer peripheral wall 11 is, for example, 0.1 mm to 10 mm.

[0079] The partition wall 13 defines a plurality of compartments 14. More specifically, the partition wall 13 includes a first partition wall 13a and a second partition wall 13b that are orthogonal to each other, and the first partition wall 13a and the second partition wall 13b define a plurality of compartments 14. The cross-sectional shape of the compartment 14 is a quadrilateral except for the portion where the first partition wall 13a and the second partition wall 13b contact the outer peripheral wall 11. It should be noted that the configuration of the partition wall is not limited to the above-mentioned partition wall 13. The partition wall may include: a first partition wall extending in a radial direction, and a second partition wall extending in a circumferential direction, which define a plurality of compartments.

[0080] The thickness of the partition wall 13 can be appropriately set according to the purpose of the honeycomb substrate. Typically, the thickness of the partition wall 13 is thinner than the thickness of the peripheral wall 11. The thickness of the partition wall 13 is, for example, 0.03 mm to 0.6 mm. The thickness of the partition wall is measured by, for example, cross-sectional observation based on SEM (scanning electron microscope). If the thickness of the partition wall is within such a range, the mechanical strength of the honeycomb substrate can be sufficient, and the opening area (the total area of ​​the cells in the cross section) can be sufficient.

[0081] The porosity of the partition walls 13 can be appropriately set according to the purpose. The porosity of the partition walls 13 is, for example, 15% or more, preferably 20% or more, and for example, 70% or less, preferably 45% or less. The porosity can be measured by, for example, mercury penetration.

[0082] The bulk density of the partition walls 13 can be appropriately set according to the purpose. For example, the bulk density is 0.10 g / cm 3 Above, preferably 0.20 g / cm 3 Above, for example, 0.60 g / cm 3Below, preferably 0.50g / cm 3 Hereinafter, the bulk density can be measured by, for example, mercury intrusion porosimetry.

[0083] As the material constituting the partition wall 13, representatively, ceramics can be cited. As ceramics, for example, silicon carbide, silicon-silicon carbide composite materials, cordierite, mullite, alumina, silicon nitride, spinel, silicon carbide-cordierite composite materials, lithium aluminum silicate and aluminum titanate can be cited. The material constituting the partition wall can be used alone or in combination. Among the materials constituting the partition wall, cordierite, alumina, mullite, silicon carbide, silicon-silicon carbide composite materials and silicon nitride can be preferably cited, and silicon carbide and silicon-silicon carbide composite materials can be more preferably cited.

[0084] Typically, such a honeycomb substrate 10a is produced by the following method. First, a binder and water or an organic solvent are added to the material powder containing the above-mentioned ceramic powder as needed, and the obtained mixture is kneaded to form a blank, and the blank is molded (typically extrusion molded) into a desired shape, and then dried and fired as needed to produce the honeycomb substrate 10a. In the case of firing, for example, the firing is performed at 1200°C to 1500°C. The firing time is, for example, 1 hour or more and 20 hours or less.

[0085] B-2-2. Acidic gas adsorption layer (carbon dioxide adsorption layer)

[0086] In one embodiment, the acid gas adsorption layer 15 is formed on the surface of the partition wall 13. In the honeycomb substrate 10a, a gas flow path 16 is formed in a portion (representatively, a central portion) of the cross section of the cell 14 where the acid gas adsorption layer 15 is not formed. The acid gas adsorption layer 15 may be formed on the entire inner surface of the partition wall 13 (i.e., in a manner that surrounds the gas flow path 16) as shown in the example of the figure, or may be formed on a portion of the surface of the partition wall. If the acid gas adsorption layer 15 is formed on the entire inner surface of the partition wall 13, the removal efficiency of the acid gas (representatively, CO2) can be improved.

[0087] The gas flow path 16 extends from the first end face E1 (inflow end face) to the second end face E2 (outflow end face) in the same manner as the compartment 14. The cross-sectional shape of the gas flow path 16 may be the same as that of the compartment 14, preferably a hexagon or a quadrilateral, more preferably a square, a rectangle or a hexagon. The cross-sectional shape and size of the gas flow path 16 may be the same in all or may be at least partially different.

[0088] Typically, in the adsorption process, the above-mentioned gas to be treated flows through the compartment 14 (more specifically, the gas flow path 16). In addition, in one embodiment, in the desorption process, the above-mentioned desorption gas flows through the compartment 14 (more specifically, the gas flow path 16), and in the cooling process, the above-mentioned cooling gas flows through the compartment 14.

[0089] The acid gas adsorption layer 15 contains an acid gas adsorption material corresponding to the acid gas to be adsorbed. In one embodiment, the acid gas adsorption layer 15 is a carbon dioxide adsorption layer 15a. The carbon dioxide adsorption layer 15a contains a carbon dioxide adsorption material as an example of an acid gas adsorption material.

[0090] As a carbon dioxide adsorbent, any appropriate compound that can adsorb and desorb CO2 can be used. Examples of carbon dioxide adsorbents include: nitrogen-containing compounds described below; alkaline compounds such as sodium hydroxide and potassium hydroxide; carbonates such as calcium carbonate and potassium carbonate; bicarbonates such as calcium hydrogen carbonate and potassium hydrogen carbonate; organometallic structures (MOFs) such as MOF-74, MOF-200, and MOF-210; zeolites; activated carbon; nitrogen-doped carbon; ionic liquids, etc. Carbon dioxide adsorbents can be used alone or in combination.

[0091] Among the carbon dioxide adsorbents, nitrogen-containing compounds and ionic liquids are preferred. More specifically, the nitrogen-containing compounds include: primary amines such as monoethanolamine and polyethyleneamine; secondary amines such as diethanolamine, cyclic amines, and N-(3-aminopropyl)diethanolamine; tertiary amines such as methyldiethylamine and triethanolamine; ethyleneamine compounds such as tetraethylenepentamine; aminosilane coupling agents such as aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane, and polyethyleneimine-trimethoxysilane; organic monomers having primary to tertiary amino groups such as ethyleneimine and styrene endowed with amino groups; organic polymers having primary to tertiary amino groups such as linear polyethyleneimine and branched polyethyleneimine having primary to tertiary amino groups; piperazine compounds such as 1-(2-hydroxyethyl)piperazine; amide compounds such as polyamideamine; polyethyleneamine; and organic / inorganic compounds endowed with amino groups as substituents.

[0092] Among the nitrogen-containing compounds, preferred examples include methyldiethylamine, monoethanolamine, cyclic amines, diethanolamine, tetraethylenepentamine, ethyleneimine, linear polyethyleneimine, branched polyethyleneimine, and organic / inorganic compounds having an amino group as a substituent.

[0093] Ionic liquids are liquid "salts" composed only of ions (anions and cations), and are in a liquid state at normal temperature and pressure (23°C, 0.1 MPaA (absolute pressure)). Examples of cations of ionic liquids include: ammonium ions such as imidazolium salts and pyridinium salts, phosphonium ions, sulfonium salts, inorganic ions, and the like. Examples of anions of ionic liquids include: halogen ions such as bromide ions and trifluoromethanesulfonates; boron ions such as tetraphenylborate; phosphorus ions such as hexafluorophosphate; sulfur ions such as alkylsulfonates. Among ionic liquids, a combination of imidazolium salts as cations and trifluoromethanesulfonates as anions is preferred.

[0094] The ionic liquid is more preferably used in combination with a carbon dioxide adsorbent material other than the ionic liquid (hereinafter referred to as other carbon dioxide adsorbent material). In this case, the ionic liquid is coated with the other carbon dioxide adsorbent material (eg, a nitrogen-containing compound). Therefore, the performance of the carbon dioxide adsorbent material can be improved and the life can be extended.

[0095] The content ratio of the ionic liquid is, for example, 0.000001 parts by mass or more, preferably 0.00001 parts by mass or more, for example, 0.1 parts by mass or less, preferably 0.05 parts by mass or less, relative to 1 part by mass of other carbon dioxide adsorbents. If the content ratio of the ionic liquid is within the above range, the performance improvement and long life of the carbon dioxide adsorbent can be stably achieved.

[0096] In one embodiment, the carbon dioxide adsorption layer 15a further includes a porous carrier in addition to the above-mentioned carbon dioxide adsorption material. In this case, the carbon dioxide adsorption material is typically supported on the porous carrier and faces the gas flow path. If the carbon dioxide adsorption layer includes a porous carrier, it is possible to suppress the carbon dioxide adsorption material from falling off from the carbon dioxide adsorption layer during the adsorption process and / or the desorption process.

[0097] The porous carrier can form mesopores in the carbon dioxide adsorption layer. As the porous carrier, for example, there can be mentioned: organometallic structures (MOFs) such as MOF-74, MOF-200, and MOF-210; activated carbon; nitrogen-doped carbon; mesoporous silica; mesoporous alumina; zeolite; carbon nanotubes; fluorinated resins such as polyvinylidene fluoride (PVDF), preferably, there can be mentioned: organometallic structures (MOFs), PVDF, activated carbon, zeolite, mesoporous silica, and mesoporous alumina. The porous carrier can be used alone or in combination. The porous carrier preferably uses a material different from the carbon dioxide adsorbent material.

[0098] The BET specific surface area of ​​the porous carrier is, for example, 50 m 2 / g or more, preferably 500m 2If the surface area of ​​the porous carrier is greater than or equal to the above lower limit, the carbon dioxide adsorbent can be stably supported, thereby improving the CO2 recovery rate. The upper limit of the BET specific surface area of ​​the porous carrier is typically 2000 m 2 / g or less.

[0099] When the carbon dioxide adsorption layer contains a carbon dioxide adsorbent and a porous carrier, the total content ratio of the carbon dioxide adsorbent and the porous carrier in the carbon dioxide adsorption layer is, for example, 30 mass % or more, preferably 50 mass % or more, for example, 100 mass % or less, preferably 99 mass % or less.

[0100] The content ratio of the carbon dioxide adsorbent in the carbon dioxide adsorption layer is, for example, 30% by mass or more, preferably 50% by mass or more, for example, 99% by mass or less. The content ratio of the porous carrier is, for example, 0.01% by mass or more, preferably 0.3% by mass or more, for example, 0.7% by mass or less, preferably 0.5% by mass or less, relative to 1% by mass of the carbon dioxide adsorbent. If the content ratio of the porous carrier is within the above range, the carbon dioxide adsorbent can be more stably supported.

[0101] In addition, the carbon dioxide adsorption layer may be composed only of carbon dioxide adsorption material. In this case, the carbon dioxide adsorption material is directly supported on the partition wall 13 and faces the gas flow path. In the case where the carbon dioxide adsorption layer is composed only of carbon dioxide adsorption material, the content of carbon dioxide adsorption material in the carbon dioxide adsorption layer is typically 95.0 mass % or more and 100 mass % or less. If the content of carbon dioxide adsorption material is within the above range, it is possible to stably ensure an excellent CO2 recovery rate.

[0102] Typically, such a carbon dioxide adsorption layer is produced by the following method. The above-mentioned carbon dioxide adsorption material is dissolved in a solvent to prepare a solution of the carbon dioxide adsorption material. In addition, the above-mentioned porous carrier is added to the solvent as needed. There is no particular restriction on the order of adding the carbon dioxide adsorption material and the porous carrier. Afterwards, the solution of the carbon dioxide adsorption material is applied to a substrate (specifically, a partition), and then the coating is dried and sintered as needed to form a carbon dioxide adsorption layer.

[0103] Alternatively, a dispersion containing a carbon dioxide adsorbent other than an ionic liquid and a porous carrier is applied to a substrate, the coating is dried, and if necessary, sintered, and then only the ionic liquid is applied to the substrate to form a carbon dioxide adsorbing layer.

[0104] Although not shown, the acid gas adsorption device 1 may include a heater in addition to the substrate 10 and the acid gas adsorption layer 15. The heater can heat the substrate 10. Typically, the heater is in contact with the substrate 10. If the acid gas adsorption device includes a heater, the temperature of the acid gas adsorption device can be smoothly raised to the desorption temperature in the desorption step.

[0105] Although not shown, each of the acid gas adsorbing device 1 and the acid gas adsorbing device 7 may further include a casing. The casing has a tubular shape (hollow shape) through which a fluid can pass, and accommodates the acid gas adsorbing unit 19. Examples of the tubular shape include a circular cylindrical shape and a square cylindrical shape.

[0106] Typically, the acid gas adsorbing unit 19 is supported by the housing so as to be relatively immovable.

[0107] In the cooling process, typically, the entire acid gas adsorption unit 19 is cooled to the above-mentioned cooling temperature. In one embodiment, the cooling gas passes through the entire acid gas adsorption unit 19 supported by the housing in a relatively non-movable manner. In the case where the acid gas adsorption unit is supported by the housing in a relatively non-movable manner, the separation unit for high-temperature gas to flow in and the cooling unit for cooling gas to flow in are adjacent to each other via a boundary plate. Therefore, the cooling efficiency of the cooling unit near the boundary plate is lower than that of the central area of ​​the cooling unit due to the heat from the separation unit at a high temperature. Therefore, the cooling unit near the boundary plate is in contact with oxygen for a longer time in a high-temperature state, and sometimes there is a difference in the oxidative degradation of the acid gas adsorbent in the central area of ​​the cooling unit and near the boundary plate. In the case where the acid gas adsorption unit is supported by the housing in a relatively non-movable manner, in the cooling process, the cooling unit is not adjacent to the separation unit for separating the high-temperature gas, so that the entire acid gas adsorption unit can be uniformly cooled, and therefore, the oxidative degradation of the entire gas adsorption unit can be uniformly suppressed.

[0108] C. Acid Gas Recovery System

[0109] Next, refer to Figure 4 , an acid gas recovery system capable of implementing the above-mentioned acid gas recovery method is described.

[0110] The acid gas recovery system 100 shown in the figure is provided with an acid gas adsorption device, an acid gas supply blower 2, a desorption gas supply unit 5, a cooling gas supply unit 3, a recovery unit 4, a thermometer 8, and a control unit 9. It should be noted that the acid gas recovery system 100 shown in the figure is provided with one each of the acid gas adsorption device 1, the acid gas supply blower 2, the desorption gas supply unit 5, the cooling gas supply unit 3, the recovery unit 4, the thermometer 8, and the control unit 9, but the number of these may be one or more, and there is no particular limitation.

[0111] In one embodiment, the acid gas recovery system 100 is a carbon dioxide recovery system 100a including a carbon dioxide adsorbent 1a as an example of the acid gas adsorbent 1. The acid gas recovery system 100 includes an acid gas adsorbent 7 (carbon dioxide adsorbent 7a) instead of the acid gas adsorbent 1 (carbon dioxide adsorbent 1a).

[0112] C-1. Blower for acid gas supply

[0113] The acid gas supply blower 2 is configured to supply the above-mentioned gas to be treated (representatively, CO2-containing gas) to the acid gas adsorption device 1 (representatively, the acid gas adsorption unit 19) during the adsorption process. The acid gas supply blower 2 shown in the figure can convey the gas to be treated containing the acid gas toward the acid gas adsorption device 1. The acid gas supply blower 2 can adopt any appropriate structure. The connection between the acid gas supply blower 2 and the acid gas adsorption device 1 can be a pipe or a portion on the upstream side of the acid gas adsorption device in the container that accommodates the acid gas adsorption device 1.

[0114] C-2. Degassing gas supply unit

[0115] The desorption gas supply unit 5 is configured to supply the desorption gas described above to the acid gas adsorption device 1 (representatively, the acid gas adsorption unit 19) during the desorption process. The desorption gas supply unit 5 shown in the figure includes a desorption gas supply line 51 and a first opening and closing valve 52. The desorption gas supply line 51 is typically a pipe capable of supplying the desorption gas described above to the acid gas adsorption device 1. The downstream end of the desorption gas supply line 51 in the supply direction of the desorption gas is connected to a portion between the acid gas supply blower 2 and the acid gas adsorption device 1. When the desorption gas is the above-mentioned recovered gas, although not shown in the figure, the upstream end of the desorption gas supply line 51 in the supply direction of the desorption gas is connected to an intermediate tank for storing the recovered gas. The first opening and closing valve 52 is provided on the desorption gas supply line 51 and can open and close the desorption gas supply line 51. As the first opening and closing valve 52, for example, a ball valve, a gate valve, and a butterfly valve can be cited, and preferably a butterfly valve can be cited.

[0116] C-3. Cooling gas supply unit

[0117] The cooling gas supply unit 3 is configured to supply the cooling gas to the acid gas adsorption device 1 (representatively, the acid gas adsorption unit 19) during the cooling process. The cooling gas supply unit 3 shown in the figure includes a cooling gas device 30, a cooling gas supply line 31, and a second opening and closing valve 32. The cooling gas device 30 can generate and store the cooling gas. The cooling gas supply line 31 is typically a pipe that can supply the cooling gas from the cooling gas device 30 to the acid gas adsorption device 1. The second opening and closing valve 32 is provided on the cooling gas supply line 31 and can open and close the cooling gas supply line 31. As the second opening and closing valve 32, for example, a valve similar to the first opening and closing valve 52 can be cited.

[0118] C-4. Recovery Unit

[0119] The recovery unit 4 is configured to recover the acid gas separated in the separation process. In one embodiment, the recovery unit 4 can recover the cooling gas that has passed through the acid gas adsorption device 1 (representatively, the acid gas adsorption unit 19) in the cooling process. The recovery unit 4 shown in the figure includes a suction pump 40 and a gas discharge unit 41. The suction pump 40 can suck the gas in the acid gas adsorption device. As the suction pump 40, for example, a vacuum pump can be cited. In the gas discharge unit 41, the gas discharged from the acid gas adsorption device 1 and heading toward the suction pump 40 passes. The gas discharge unit 41 can be a pipe, or it can be a portion on the downstream side of the acid gas adsorption device in the container that accommodates the acid gas adsorption device 1.

[0120] C-5. Thermometer and control unit

[0121] The thermometer 8 can measure the temperature of the acid gas adsorption device 1, typically the temperature of the acid gas adsorption unit 19, preferably the temperature of the substrate 10. The thermometer 8 can adopt any appropriate structure. The control unit 9 can control the operation of the acid gas recovery system 100. The control unit 9 can adopt any appropriate structure. The control unit 9 includes, for example, a central processing unit (CPU), ROM, and RAM.

[0122] D. Operation of the Acid Gas Recovery System

[0123] Next, an embodiment of an acid gas recovery method implemented by the acid gas recovery system 100 is described. In one embodiment, the acid gas recovery method includes the above-mentioned adsorption step, the replacement step, the above-mentioned desorption step, and the above-mentioned cooling step in sequence. It should be noted that the following is a detailed description of the case where the acid gas adsorption device 1 includes a honeycomb substrate 10a, an acid gas adsorption layer 15, and a heating body (not shown).

[0124] In the acid gas recovery system 100, first, an adsorption process is performed. In the adsorption process, the control unit 9 sets the first on-off valve 52 and the second on-off valve 32 to the closed state and drives the acid gas supply blower 2. As a result, the above-mentioned gas to be treated is sent out through the acid gas supply blower 2, supplied to the acid gas adsorption unit 19 of the acid gas adsorption device 1, and flows through the gas flow path 16. It should be noted that the temperature of the acid gas adsorption device in the adsorption process (representatively, the temperature of the acid gas adsorption unit 19) is adjusted in advance to the above-mentioned adsorption temperature.

[0125] In the adsorption process, the temperature range of the gas to be treated supplied to the acid gas adsorption device is the same as the above-mentioned adsorption temperature range. The temperature of the gas to be treated may be the same as or different from the adsorption temperature of the acid gas adsorption device. The pressure of the gas to be treated is, for example, 0.3×10 5 PaA (absolute pressure) or above and 2.0×10 5 The relative humidity RH of the gas to be processed is, for example, 10% RH or more and 60% RH or less. The flow rate of the gas to be processed is, for example, 0.5 m / sec or more and 5 m / sec or less.

[0126] Thereafter, when the above-mentioned adsorption time has elapsed, the control unit 9 stops driving the acid gas supply blower 2, and the adsorption process is completed.

[0127] Next, the replacement process is performed in the acid gas recovery system 100. In the replacement process, the control unit 9 changes the first on-off valve 52 from the closed state to the open state, and drives the suction pump 40. Then, the above-mentioned desorbed gas is supplied to the acid gas adsorption unit 19 of the acid gas adsorption device 1 through the desorbed gas supply line 51, and flows through the gas flow path 16. As a result, the gas flow path 16 is replaced from the gas to be treated to the desorbed gas.

[0128] In the replacement step, the temperature range of the desorbed gas supplied to the acid gas adsorption device is the same as the above-mentioned adsorption temperature range. The pressure of the desorbed gas is, for example, 0.1×10 4 PaA or above and 1.0×10 4 PaA or less, for example, 0.1×10 4 PaA or above and 5.0×104 The implementation time of the replacement step (hereinafter referred to as replacement time) is, for example, 1 minute or more and 30 minutes or less.

[0129] It should be noted that in the replacement step, a purge gas different from the desorbed gas may be introduced into the acid gas adsorption device, thereby replacing the gas to be treated in the acid gas adsorption device with the purge gas. In this case, the pressure of the purge gas is, for example, 0.1×10 4 PaA or above and 11×10 4 The replacement time is, for example, 1 minute or more and 30 minutes or less. Examples of the purge gas include water vapor, carbon dioxide, nitrogen, and argon.

[0130] After that, the removal process is performed immediately after the replacement process in the acid gas recovery system 100. The control unit 9 controls the heating body (not shown) to heat the acid gas adsorption device 1 (representatively, the acid gas adsorption unit 19) while maintaining the driving state of the suction pump 40. It should be noted that the heating of the acid gas adsorption device may be started in the middle of the replacement process.

[0131] When the temperature of the acid gas adsorption device (representatively, the temperature of the acid gas adsorption unit 19) reaches the desorption temperature, the acid gas retained by the acid gas adsorption material is desorbed (released) from the acid gas adsorption material. The desorbed acid gas is discharged from the acid gas adsorption device 1 together with the desorbed gas, passes through the gas discharge unit 41 and the suction pump 40, and is stored in an intermediate tank as needed. Such recovered gas can be used for various purposes as described above, can be supplied to the acid gas adsorption device again as the desorbed gas as described above, and can also be used as a raw material for various industrial products (for example, a raw material for hydrocarbon fuel).

[0132] In addition, the control unit 9 may monitor the temperature of the acid gas adsorption device 1 using the thermometer 8 during the desorption process, and control the output of the heating body so that the temperature of the acid gas adsorption device 1 (representatively, the temperature of the acid gas adsorption unit 19) does not exceed the above-mentioned desorption temperature range.

[0133] Next, when the above-mentioned desorption time has passed, the acid gas recovery system 100 performs a cooling process. The control unit 9 first controls the heating element to stop heating the acid gas adsorption device 1. Thereafter, the control unit 9 changes the first on-off valve 52 from an open state to a closed state while maintaining the driving of the suction pump 40, and changes the second on-off valve 32 from a closed state to an open state. Then, the above-mentioned cooling gas is supplied to the acid gas adsorption unit 19 of the acid gas adsorption device 1 through the cooling gas supply line 31, and flows through the gas flow path 16. As a result, the acid gas adsorption device 1 (representatively, the acid gas adsorption unit 19) is cooled.

[0134] During the cooling process, the control unit 9 monitors the temperature of the acid gas adsorption device 1 using the thermometer 8, thereby maintaining the supply of cooling gas as an example of cooling medium to the acid gas adsorption device 1 until the acid gas adsorption device 1 (representatively, the temperature of the acid gas adsorption unit 19) is cooled to the desired cooling temperature.

[0135] It should be noted that the cooling gas having passed through the gas flow path 16 is cooled as necessary after passing through the gas discharge portion 41 and the suction pump 40 , and then returns to the cooling gas device 30 .

[0136] After that, when the acid gas adsorption device 1 (representatively, the temperature of the acid gas adsorption unit 19) reaches the cooling temperature, the acid gas recovery system 100 performs the adsorption process again after the cooling process. More specifically, the control unit 9 stops driving the suction pump 40 and then performs the above-mentioned adsorption process again. In this way, the acid gas recovery system 100 can repeatedly perform the adsorption process, the replacement process, the desorption process, and the cooling process in sequence.

[0137] E. Modification

[0138] In the above embodiment, in the cooling step, the cooling gas as the cooling medium is supplied to the acid gas adsorbing device, but the cooling medium may be a liquid refrigerant as described above. In this case, in the cooling step, the liquid refrigerant contacts the substrate 10 (honeycomb substrate 10a) to cool the acid gas adsorbing device 1.

[0139] Reference Figure 5 , an acid gas recovery system 101 including an acid gas adsorption device that can be cooled by a liquid refrigerant is described.

[0140] The acid gas adsorption device (the acid gas adsorption device 7 or the acid gas adsorption device 1) is provided with a jacket 17, and the acid gas recovery system 101 is provided with a refrigerant supply unit 6 instead of the cooling gas supply unit 3. The acid gas recovery system 101 has the same configuration as the acid gas recovery system 100. The acid gas recovery system 101 shown in the figure is provided with the acid gas adsorption device 1 (the carbon dioxide adsorption device 1a), but the acid gas adsorption device 7 (the carbon dioxide adsorption device 7a) may be provided instead of the acid gas adsorption device 1 (the carbon dioxide adsorption device 1a).

[0141] The jacket 17 is provided on the outer surface of the acid gas adsorption device. The jacket 17 shown in the figure is provided on the outer peripheral wall 11 of the acid gas adsorption device 1 (see Figure 2) of the outer peripheral surface. The jacket 17 is configured such that a liquid coolant can flow therein. Thus, the liquid coolant can contact the outer peripheral wall 11.

[0142] The refrigerant supply unit 6 is configured to be able to circulate the liquid refrigerant via the jacket 17. The refrigerant supply unit 6 includes a cooler 60, a refrigerant supply line 61, a refrigerant circulation line 62, and a pump 63.

[0143] The cooler 60 can cool the circulating liquid refrigerant to a temperature lower than the outside air temperature. The cooler 60 can adopt any appropriate structure. The refrigerant supply line 61 is typically a pipe that can supply the liquid refrigerant from the cooler 60 to the jacket 17. The upstream end of the refrigerant supply line 61 in the supply direction of the liquid refrigerant is connected to the cooler 60. The downstream end of the refrigerant supply line 61 in the supply direction of the liquid refrigerant is connected to the jacket 17. The refrigerant return line 62 is typically a pipe that can return the liquid refrigerant that has passed through the jacket 17 to the cooler 60. The upstream end of the refrigerant return line 62 in the return direction of the liquid refrigerant is connected to the jacket 17. The downstream end of the refrigerant return line 62 in the supply direction of the liquid refrigerant is connected to the cooler 60. The pump 63 is provided on the refrigerant supply line 61, and can adjust the flow rate of the liquid refrigerant passing through the refrigerant supply line 61. The pump 63 can have any appropriate structure.

[0144] The acid gas recovery method implemented by the acid gas recovery system 101 can be described in the same manner as the acid gas recovery method implemented by the above-mentioned acid gas recovery system 100 except for the cooling step. Therefore, the description of the adsorption step, the replacement step, and the desorption step is omitted.

[0145] In the cooling process, the control unit 9 stops heating the acid gas adsorption device by the heating body and drives the pump 63. Then, the liquid refrigerant cooled to the desired temperature in the cooler 60 is supplied to the jacket 17 via the refrigerant supply line 61. The liquid refrigerant contacts the outer peripheral wall 11 of the honeycomb substrate 10a in the jacket 17, cools the honeycomb substrate 10a, is discharged from the jacket 17, and is returned to the cooler 60 via the refrigerant return line 62. Thus, in the cooling process, the liquid refrigerant circulates in the refrigerant supply unit 6 and the jacket 17. In the cooling process, the control unit 9 monitors the temperature of the acid gas adsorption device 1 using the thermometer 8, thereby maintaining the circulation of the liquid refrigerant until the acid gas adsorption device 1 is cooled to the desired cooling temperature. Thus, the acid gas adsorption device after the separation process can also be smoothly cooled, thereby shortening the cooling time.

[0146] On the other hand, Figure 5 The acid gas recovery system 101 and Figure 4Compared with the acid gas recovery system 100 shown in FIG. 1 , the acid gas recovery system 100 can be configured more simply than the acid gas recovery system 101. Therefore, the acid gas recovery system 100 is more desirable than the acid gas recovery system 101.

[0147] In addition, in the cooling process, a cooling gas and a liquid refrigerant may be used in combination as a cooling medium. In this case, the acid gas adsorption device is cooled by being supplied with the cooling gas and the liquid refrigerant. For example, regarding the acid gas adsorption device 1, in the cooling process, the cooling gas flows through the compartment, and the liquid refrigerant contacts the substrate, thereby being cooled. In addition, when the cooling gas and the liquid refrigerant are used in combination, the acid gas recovery system may include a cooling gas supply unit 3 and a refrigerant supply unit 6.

[0148] Industrial Applicability

[0149] The acid gas recovery method according to the embodiment of the present invention is used for separation and recovery of acid gas, and can be particularly well used in a carbon dioxide recovery, utilization and storage (CCUS) cycle.

[0150] Explanation of symbols

[0151] 1 Acid gas adsorption device

[0152] 1a Carbon dioxide adsorption device

[0153] 7 Acid gas adsorption device

[0154] 7a Carbon dioxide adsorption device

[0155] 10. Substrate

[0156] 10a Honeycomb substrate

[0157] 13 Next Door

[0158] 15 Acid gas adsorption layer

[0159] 15a Carbon dioxide adsorption layer

[0160] 100 Acid Gas Recovery System

[0161] 100a CO2 Recovery System

Claims

1. A method for recovering acidic gas, comprising: an adsorption step in which a gas to be treated containing acid gas is supplied to an acid gas adsorption device including an acid gas adsorbing material, so that the acid gas is adsorbed by the acid gas adsorbing material; a desorption step in which the acid gas adsorption device is heated to desorb the acid gas from the acid gas adsorption material; as well as A cooling step in which the acid gas adsorption device is cooled using a cooling medium at a temperature lower than the outside air temperature.

2. The method for recovering acidic gas according to claim 1, wherein: The acid gas is carbon dioxide.

3. The method for recovering acidic gas according to claim 1 or 2, wherein: In the cooling step, a cooling gas serving as the cooling medium is caused to flow through the acid gas adsorption device.

4. The method for recovering acidic gas according to claim 3, wherein: The oxygen concentration in the cooling gas is lower than the oxygen concentration in the gas to be treated.

5. The method for recovering acidic gas according to claim 3, wherein: The flow rate of the cooling gas in the cooling process is smaller than the flow rate of the gas to be treated in the adsorption process.

6. The method for recovering acidic gas according to claim 1 or 2, wherein: The acid gas adsorption device comprises: a honeycomb substrate having walls defining a plurality of cells; and An acidic gas adsorption layer includes the acidic gas adsorption material and is formed on the surface of the partition wall.

7. The method for recovering acidic gas according to claim 6, wherein: In the cooling step, a liquid coolant as the cooling medium is brought into contact with the honeycomb substrate.

8. The method for recovering acidic gas according to claim 1 or 2, wherein: In the cooling step, the temperature of the acid gas adsorbing device is monitored, and a cooling medium is supplied to the acid gas adsorbing device until the acid gas adsorbing device is cooled to a desired cooling temperature.

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