Gas recovery device

Abstract

This gas recovery device comprises: a honeycomb structure 10 having outer peripheral walls 11, and partition walls 15 which are provided to the inner side of the outer peripheral walls 11 and which separate and form a plurality of cells 14 extending from an inflow end face 12 to an outflow end face 13, the honeycomb structure having communication hole sections 16 formed in the facing outer peripheral walls 15 and the partition walls 15 therebetween, and being capable of adsorbing and releasing a capturing target gas; an accommodation section 20 for accommodating the honeycomb structure 10; gas supply piping 30 which is connected to the accommodation section 20 and is capable of supplying a processing gas and / or purge gas containing the capturing target gas; and gas discharge piping 40 which is connected to the accommodation section 20 and is capable of discharging the processing gas and / or purge gas. The processing gas flows from the cells 14 at the inflow end face 12 to the cells 14 at the outflow end face 13, and the purge gas can flow from the communication hole sections 16 in one of the facing outer peripheral walls 11 to the communication hole sections 16 in the other of the outer peripheral walls 11.

Description

Gas Recovery Device

[0001] The present invention relates to a gas recovery device.

[0002] To realize a decarbonized society, there is a growing need for technologies that capture and utilize greenhouse gases (e.g., carbon dioxide) from the atmosphere or exhaust gases. A typical conventional carbon dioxide (CO2) capture technology is Direct Air Capture (DAC), which adsorbs CO2 from the atmosphere. There are several types of DAC, including liquid absorption, membrane separation, and solid adsorption. Among these, in the solid adsorption method, a basic adsorbent such as a CO2 adsorbent (absorbent) is generally supported on a substrate. Honeycomb structures, which have a proven track record in purifying automobile exhaust gases, are expected to be used as substrates for the solid adsorption method.

[0003] For example, Patent Document 1 describes a honeycomb ceramic structure for CO capture. This honeycomb ceramic structure for CO capture includes a honeycomb ceramic substrate having porous partition walls, a plurality of inorganic support particles in at least one pore of the porous partition walls, and an organic carbon dioxide sorbent supported by at least one of the inorganic support particles. Patent Document 2 also describes a honeycomb structure having a plurality of partition walls extending axially from an inlet end to an outlet end, thereby forming a plurality of flow channels, in which an amine polymer having functional structural unit groups that absorb CO is dispersed in the inorganic powder component of the partition walls of the honeycomb structure, which comprises a mixture of an inorganic powder component and an organic binder.

[0004] The honeycomb structure can adsorb CO2 by passing a CO2-containing treatment gas through the cells. On the other hand, CO2 adsorbed in a substrate such as a honeycomb structure can be desorbed by passing a purge gas (desorption gas) such as water vapor through the cells (see, for example, Patent Document 3).

[0005] JP 2018-538137 A JP 2015-508018 A JP 2024-34883 A

[0006] As described above, when CO2 is adsorbed or desorbed, a process gas or a purge gas is circulated through the cells of the honeycomb structure. However, because the flow rate of the process gas suitable for CO2 adsorption and the flow rate of the purge gas suitable for CO2 desorption are different, circulating each gas at the same flow rate reduces the CO2 adsorption or desorption efficiency. Note that while the above description has been given using an example in which the target gas to be captured is CO2, similar problems arise when adsorbing or desorbing other target gases to be captured.

[0007] The present invention has been made to solve the above-mentioned problems, and has an object to provide a gas recovery device that can efficiently adsorb and desorb a target gas to be captured.

[0008] As a result of extensive research into the structure of a gas recovery device, the inventors have discovered that the above problems can be solved by using a specific structure, and have thus completed the present invention. That is, the present invention is exemplified as follows.

[0009] <1> A gas recovery device comprising: a honeycomb structure having an outer peripheral wall and partition walls disposed inside the outer peripheral wall and defining a plurality of cells extending from an inflow end face to an outflow end face, wherein communicating holes are formed in the opposing outer peripheral walls and in the partition wall between them, and capable of adsorbing and desorbing a target gas to be captured; a storage section for accommodating the honeycomb structure; a gas supply pipe connected to the storage section and capable of supplying a process gas and / or a purge gas containing the target gas to be captured; and a gas discharge pipe connected to the storage section and capable of discharging the process gas and / or the purge gas, wherein the gas recovery device is configured so that the process gas flows from the cells at the inflow end face to the cells at the outflow end face, and the purge gas can flow from the communicating holes in one opposing outer peripheral wall to the communicating holes in the other outer peripheral wall.

[0010] <2> The gas recovery device described in <1>, wherein the storage section has an inlet valve capable of switching the inflow of each gas into the cell on the inlet end surface or the communication hole portion of the opposing one of the outer peripheral walls, and an outlet valve capable of switching the outflow of each gas from the cell on the outlet end surface or the communication hole portion of the opposing other of the outer peripheral walls.

[0011] <3> The gas recovery device according to <2>, further comprising a control unit capable of controlling the inlet valve and the outlet valve, wherein the control unit is capable of executing an adsorption mode in which the processing gas flows into the cells at the inlet end surface and flows out of the cells at the outlet end surface, and a desorption mode in which the purge gas flows into the communicating hole portion of one of the opposing outer peripheral walls and flows out of the communicating hole portion of the other outer peripheral wall.

[0012] <4> The gas recovery device according to <3>, wherein a sensor capable of measuring the concentration of the target gas to be captured in the processing gas is disposed in the gas exhaust pipe, and the control unit executes the adsorption mode and then executes the desorption mode when the concentration of the target gas to be captured reaches a predetermined value.

[0013] <5> The gas recovery device according to any one of <1> to <4>, wherein the gas supply piping has a gas supply branch piping branched into two, the gas supply branch piping being a first gas supply branch piping capable of supplying the processing gas and a second gas supply branch piping capable of supplying the purge gas; the gas exhaust piping has a gas exhaust branch piping branched into two, the gas exhaust branch piping being a first gas exhaust branch piping capable of exhausting the processing gas and a second gas exhaust branch piping capable of exhausting the purge gas; a supply gas switching valve capable of switching supply from the first gas supply branch piping or the second gas supply branch piping is provided at a branching portion of the gas supply piping; and an exhaust gas switching valve capable of switching exhaust from the first gas exhaust branch piping or the second gas exhaust branch piping is provided at a branching portion of the gas exhaust piping.

[0014] <6> The gas recovery device according to any one of <1> to <4>, wherein the gas supply pipe is a first gas supply pipe capable of supplying the processing gas to the cells at the inlet end surface and a second gas supply pipe capable of supplying the purge gas to the communication hole portion of one of the opposing outer peripheral walls, and the gas exhaust pipe is a first gas exhaust pipe capable of exhausting the processing gas from the cells at the outlet end surface and a second gas exhaust pipe capable of exhausting the purge gas from the communication hole portion of the other opposing outer peripheral wall.

[0015] <7> The gas recovery device according to any one of <1> to <6>, further comprising a heating unit capable of heating the honeycomb structure.

[0016] <8> The gas recovery device according to any one of <1> to <7>, wherein the communication hole portion constitutes a group of communication holes arranged so as to be positioned on a straight line perpendicular to the direction in which the cells extend, and there are two or more groups of communication holes.

[0017] <9> The gas recovery device described in <8>, wherein in a cross section of the honeycomb structure perpendicular to the direction in which the cells extend, the communicating hole portions of the communicating hole group are arranged so that one straight line perpendicular to the direction in which the cells extend passes through the center of the honeycomb structure.

[0018] <10> The gas recovery device according to <8> or <9>, wherein in a cross section of the honeycomb structure parallel to the direction in which the cells extend, a relationship of D1 / L≦0.2 and / or D2 / L≧0.8 is satisfied, where D1 is the distance between the inflow end face and the center of the communicating hole portion in the communicating hole group closest to the inflow end face, D2 is the distance between the inflow end face and the center of the communicating hole portion in the communicating hole group closest to the outflow end face, and L is the length from the inflow end face to the outflow end face.

[0019] <11> The gas recovery device according to any one of <1> to <10>, wherein the diameter of the communication hole portion is 20 to 80% of the diameter of the cell.

[0020] <12> The gas recovery device according to any one of <1> to <11>, wherein the honeycomb structure has a quadrangular prism shape.

[0021] <13> The gas recovery device according to any one of <1> to <12>, wherein the shape of the cells in a cross section of the honeycomb structure perpendicular to the direction in which the cells extend is quadrangular or hexagonal.

[0022] <14> The gas recovery device according to any one of <1> to <13>, wherein the honeycomb structure is mainly composed of one or more selected from cordierite, mullite, alumina, silica, silicon carbide, and Si-bonded silicon carbide.

[0023] <15> The gas recovery device according to any one of <1> to <13>, wherein the honeycomb structure is made of one or more materials selected from paper, paper coated with a protective layer, nonwoven fabric, and nonwoven fabric coated with a protective layer.

[0024] <16> The gas recovery device according to any one of <1> to <15>, wherein the thickness of the partition wall is 0.05 to 5 mm.

[0025] <17> The gas recovery device according to any one of <1> to <14> and <16>, wherein the porosity of the partition walls is 30% or more and less than 80%.

[0026] <18> The gas recovery device according to any one of <1> to <14>, <16> and <17>, wherein the partition walls have an average pore size of 10 to 300 μm.

[0027] <19> The gas recovery device according to any one of <1> to <18>, further comprising a functional material carried on the partition wall.

[0028] <20> The gas recovery device according to <19>, wherein the functional material is an amine compound and / or a metal organic framework.

[0029] According to the present invention, it is possible to provide a gas recovery device that can efficiently adsorb and desorb a target gas to be captured.

[0030] FIG. 2A is a schematic view of a gas recovery apparatus according to a first embodiment of the present invention in an adsorption mode. FIG. 2B is a schematic view of a gas recovery apparatus according to a first embodiment of the present invention in a desorption mode. FIG. 2C is a schematic view of a cross section parallel to the cell extension direction of a honeycomb structure used in the gas recovery apparatus according to the first embodiment of the present invention. FIG. 2D is a schematic view of a cross section taken along line a-a' of the honeycomb structure of FIG. 2A. FIG. 2E is a schematic view of a gas recovery apparatus according to a second embodiment of the present invention in an adsorption mode. FIG. 2F is a schematic view of a gas recovery apparatus according to a second embodiment of the present invention in a desorption mode.

[0031] The gas recovery apparatus of the present invention includes: a honeycomb structure having an outer peripheral wall and partition walls disposed inside the outer peripheral wall to define a plurality of cells extending from an inflow end face to an outflow end face, the honeycomb structure having communicating holes formed in the opposing outer peripheral walls and the partition walls therebetween, the honeycomb structure being capable of adsorbing and desorbing a target gas to be captured; a storage section for accommodating the honeycomb structure; a gas supply pipe connected to the storage section and capable of supplying a process gas and / or a purge gas containing the target gas to be captured; and a gas discharge pipe connected to the storage section and capable of discharging the process gas and / or the purge gas. The gas recovery apparatus of the present invention is configured so that the process gas flows from the cells at the inflow end face to the cells at the outflow end face, and the purge gas flows from the communicating holes in one of the opposing outer peripheral walls to the communicating holes in the other outer peripheral wall. This structure of the gas recovery apparatus of the present invention allows the flow of the process gas and purge gas flowing through the honeycomb structure to be suitable for adsorbing and desorbing the target gas to be captured, thereby enabling efficient adsorption and desorption of the target gas to be captured.

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and it should be understood that modifications and improvements made to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention are also within the scope of the present invention.

[0033] 1A and 1B are schematic diagrams of a gas recovery device according to a first embodiment of the present invention. FIG. 1A shows a state in which a processing gas is circulated (adsorption mode), and FIG. 1B shows a state in which a purge gas is circulated (desorption mode). The gas recovery device according to the first embodiment of the present invention includes a honeycomb structure 10, a storage unit 20, a gas supply pipe 30, and a gas exhaust pipe 40. The honeycomb structure 10 has an outer peripheral wall 11 and partition walls 15 disposed inside the outer peripheral wall 11 to define a plurality of cells 14 extending from an inlet end face 12 to an outlet end face 13. Communication holes 16 are formed in the opposing outer peripheral walls 11 and in the partition walls 15 between them, enabling adsorption and desorption of a target gas to be captured. The storage unit 20 accommodates the honeycomb structure 10. The gas supply pipe 30 is connected to the storage unit 20 and is capable of supplying a processing gas and / or a purge gas containing a target gas to be captured into the storage unit 20. The gas exhaust pipe 40 is connected to the container 20 and is capable of exhausting the process gas and / or the purge gas from the container 20 .

[0034] Here, in this specification, "processing gas" refers to various gases containing the target gas to be captured. The processing gas is not particularly limited, but examples thereof include exhaust gases emitted from factories and power plants, and the atmosphere. The exhaust gas is not particularly limited, but examples thereof include combustion exhaust gases generated when burning fossil fuels, coal gasification gas obtained by gasifying coal, and natural gas in thermal power plants and steelworks. The target gas to be captured is not particularly limited, but examples thereof include carbon dioxide (CO2), nitrogen oxides (NO x ), sulfur oxides (SO x), and acidic gases such as hydrogen sulfide (HS). Among these, the gas recovery device according to the first embodiment of the present invention is particularly useful for recovering carbon dioxide (CO2) contained in combustion exhaust gas and the atmosphere. In addition, in this specification, "purge gas" refers to a gas that can desorb the target gas captured in the honeycomb structure 10 and be discharged from the gas recovery device. The purge gas may be selected appropriately depending on the type of target gas. For example, when the target gas is carbon dioxide, water vapor or the like can be used. The water vapor is preferably heated to 100°C or higher (e.g., 120°C) within the honeycomb structure 10.

[0035] In the gas recovery device according to the first embodiment of the present invention, the storage unit 20 has an inlet valve 21 capable of switching the inflow of each gas into the cells 14 on the inlet end face 12 or the communicating holes 16 on one of the opposing outer peripheral walls 11, and an outlet valve 22 capable of switching the outflow of each gas from the cells 14 on the outlet end face 13 or the communicating holes 16 on the other of the opposing outer peripheral walls 11. By providing such an inlet valve 21 and outlet valve 22, it is possible to circulate the process gas from the cells 14 on the inlet end face 12 to the cells 14 on the outlet end face 13, and to circulate the purge gas from the communicating holes 16 on one of the opposing outer peripheral walls 11 to the communicating holes 16 on the other of the outer peripheral walls 11.

[0036] The gas recovery device according to the first embodiment of the present invention may further include a control unit 50 capable of controlling the inlet valve 21 and the outlet valve 22. The control unit 50 is capable of executing an adsorption mode in which the process gas flows into the cells 14 at the inlet end surface 12 and flows out from the cells 14 at the outlet end surface 13, and a desorption mode in which the purge gas flows into the communicating holes 16 at one of the opposing outer peripheral walls 11 and flows out from the communicating holes 16 at the other outer peripheral wall 11. Specifically, in the adsorption mode, as shown in FIG. 1A , the control unit 50 switches the inlet valve 21 so that the process gas flows into the cells 14 at the inlet end surface 12, and switches the outlet valve 22 so that the process gas flows out from the cells 14 at the outlet end surface 13. 1B , the control unit 50 switches the inlet valve 21 so that the purge gas flows into the communication hole 16 of one of the opposing outer peripheral walls 11, and switches the outlet valve 22 so that the purge gas flows out from the communication hole 16 of the other opposing outer peripheral wall 11. By controlling the inlet valve 21 and the outlet valve 22 in this way by the control unit 50, the adsorption mode and the desorption mode can be easily performed.

[0037] The gas supply pipe 30 may have two branched gas supply branch pipes. The branched gas supply pipes are a first gas supply branch pipe 31 capable of supplying a process gas and a second gas supply branch pipe 32 capable of supplying a purge gas. A supply gas switching valve 33 capable of switching between the first gas supply branch pipe 31 and the second gas supply branch pipe 32 may be provided at the branched portion of the gas supply pipe 30. The supply gas switching valve 33 is electrically connected to the control unit 50, and its switching can be controlled by the control unit 50. For example, in the adsorption mode, as shown in FIG. 1A, the control unit 50 switches the supply gas switching valve 33 so that the process gas is supplied from the first gas supply branch pipe 31. In the desorption mode, as shown in FIG. 1B, the control unit 50 switches the supply gas switching valve 33 so that the purge gas is supplied from the second gas supply branch pipe 32. By switching the supply gas switching valve 33 in this way, it is possible to easily switch between supplying the process gas in the adsorption mode and supplying the purge gas in the desorption mode.

[0038] The gas exhaust pipe 40 may have two branched gas exhaust branch pipes. The first gas exhaust branch pipe 41 is capable of exhausting the process gas, and the second gas exhaust branch pipe 42 is capable of exhausting the purge gas. The branched portion of the gas exhaust pipe 40 may be provided with an exhaust gas switching valve 43 that can switch between exhausting from the first gas exhaust branch pipe 41 or the second gas exhaust branch pipe 42. The exhaust gas switching valve 43 is electrically connected to the control unit 50, and its switching can be controlled by the control unit 50. For example, in the adsorption mode, as shown in FIG. 1A, the control unit 50 switches the exhaust gas switching valve 43 so that the process gas is exhausted from the first gas exhaust branch pipe 41. In the desorption mode, as shown in FIG. 1B, the control unit 50 switches the exhaust gas switching valve 43 so that the purge gas is exhausted from the second gas exhaust branch pipe 42. By switching the exhaust gas switching valve 43 in this way, it is possible to easily switch between exhausting the processing gas in the adsorption mode and exhausting the purge gas in the desorption mode.

[0039] A sensor 60 capable of measuring the concentration of the target gas to be captured in the processing gas can be disposed in the gas exhaust pipe 40. This sensor 60 is electrically connected to the control unit 50. After executing the adsorption mode, the control unit 50 executes the desorption mode when the concentration of the target gas to be captured reaches a predetermined value. By executing the mode in this manner, the efficiency of the adsorption mode is improved, and switching from the adsorption mode to the desorption mode can be executed in a timely manner.

[0040] The gas recovery device according to the first embodiment of the present invention may further include a heating unit capable of heating the honeycomb structure 10. By providing a heating unit capable of heating the honeycomb structure 10, the honeycomb structure 10 can be heated in the desorption mode, thereby making it easier to desorb the target gas to be captured. The heating unit is not particularly limited, and various heaters can be used. For example, a heater may be provided in a part of the outer wall 11 of the honeycomb structure 10.

[0041] The following describes in detail the components of the gas recovery apparatus according to the first embodiment of the present invention and its use. (1. Honeycomb Structure 10) FIG. 2A is a schematic diagram of a cross section parallel to the cell extension direction of a honeycomb structure used in the gas recovery apparatus according to the first embodiment of the present invention. FIG. 2B is a schematic diagram of a cross section of the honeycomb structure of FIG. 2A taken along line a-a'. As shown in FIG. 2A, the communicating hole portions 16 provided in the honeycomb structure 10 constitute communicating hole groups P, which are arranged so as to be positioned on a single line L1 perpendicular to the extension direction of the cells 14. The number of communicating hole groups P is preferably two or more, and more preferably three or more. This structure optimizes the flow rate of the purge gas flowing through the communicating hole portions 16 during desorption mode, thereby improving the efficiency of the desorption mode. The upper limit of the number of communicating hole groups P is not particularly limited, but is, for example, 10 or less from the viewpoint of suppressing a decrease in the strength of the honeycomb structure 10.

[0042] In a cross section ( FIG. 2B ) of the honeycomb structure 10 perpendicular to the extension direction of the cells 14, the communicating hole portions 16 of the communicating hole group P are preferably arranged so that one straight line L1 perpendicular to the extension direction of the cells 14 passes through the center C1 of the honeycomb structure 10. By providing the communicating hole portions 16 of the communicating hole group P in this manner, it is possible to facilitate the flow of desorbed gas through the communicating hole portions 16 in the desorption mode.

[0043] In a cross section ( FIG. 2A ) of the honeycomb structure 10 parallel to the extension direction of the cells 14, it is preferable to satisfy the relationship D1 / L≦0.2 and / or D2 / L≧0.8, where D1 is the distance between the inlet end face 12 and the center of the communicating hole portion 16 in the communicating hole group P closest to the inlet end face 12, D2 is the distance between the inlet end face 12 and the center of the communicating hole portion 16 in the communicating hole group P closest to the outlet end face 13, and L is the length from the inlet end face 12 to the outlet end face 13. By satisfying these conditions, it is possible to suppress a decrease in the strength of the honeycomb structure 10 while making it easier for the desorbed gas to flow through the communicating hole portion 16 in the desorption mode.

[0044] The diameter of the communicating hole portion 16 is not particularly limited, but is preferably 20 to 80% of the diameter of the cell 14, more preferably 25 to 75%, and even more preferably 30 to 70%. By controlling the diameter of the communicating hole portion 16 within such a range, the flow rate of the purge gas flowing through the communicating hole portion 16 during desorption mode can be optimized, thereby improving the efficiency of the desorption mode. The shape of the communicating hole portion 16 is not particularly limited, and can be a circle, an ellipse, a rectangle, or another polygon. When the shape of the communicating hole portion 16 is not circular, the diameter of the communicating hole portion 16 means the diameter of the largest inscribed circle inscribed in the shape of the communicating hole portion 16.

[0045] The shape of the honeycomb structure 10 is not particularly limited as long as it has the above-mentioned characteristics. For example, the outer shape of a cross section perpendicular to the extension direction of the cells 14 of the honeycomb structure 10 can be a polygon such as a triangle, a rectangle, a hexagon, or an octagon, or a round shape such as a circle, an ellipse, an oval, an egg, an oval, a rounded rectangle (a rectangle in which each side and each corner is formed by a curve, and the radius of curvature of each side is larger than the radius of curvature of each corner, and which is formed by curves overall). Among these, from the viewpoint of manufacturability, it is preferable that the outer shapes of the cross section and end faces (the inlet end face 12 and the outlet end face 13) of the honeycomb structure 10 are quadrangular (i.e., the shape of the honeycomb structure 10 is a square prism).

[0046] The honeycomb structure 10 preferably has a square pillar shape with the length of one side of the inlet end face 12 and the outlet end face 13 being 100 to 500 mm (preferably 200 to 400 mm) and the length in the direction of extension of the cells 14 being 100 to 1000 mm (preferably 300 to 500 mm). With a honeycomb structure 10 of this size, a sufficient amount of functional material can be supported in the cells 14, and therefore practicality as a gas recovery device can be ensured.

[0047] The shape of the cells 14 is not particularly limited, and may be polygonal, such as a triangle, a rectangle, a hexagon, or an octagon, or a round shape, such as a circle, an ellipse, an oval, an egg, or an oblong, in a cross section perpendicular to the extension direction of the cells 14 of the honeycomb structure 10. Each cell may have a single shape or a combination of two or more shapes. Among these cell shapes, a rectangle or a hexagon is preferable. By providing cells of such a shape, pressure loss during the flow of the process gas can be reduced. The shape of each cell in the cross section is the same as the shape of each cell at the end face.

[0048] The material of the honeycomb structure 10 (the outer peripheral wall 11 and the partition walls 15) is not particularly limited. However, from the viewpoint of ensuring the strength of the honeycomb structure 10, it is preferable that the honeycomb structure 10 be mainly composed of one or more selected from cordierite, mullite, alumina, silica, silicon carbide, and Si-bonded silicon carbide. Here, in this specification, "main component" means a component whose proportion in the total components exceeds 50 mass%. Furthermore, from the viewpoint of reducing the amount of heat required for heating, it is also useful to compose the honeycomb structure 10 from one or more selected from paper, paper coated with a protective layer, nonwoven fabric, and nonwoven fabric coated with a protective layer. The protective layer can be composed of, for example, a polymer (e.g., a resin), a metal, glass, etc.

[0049] The thickness of the partition walls 15 is not particularly limited, but is preferably 0.05 to 5 mm, more preferably 0.10 to 4.5 mm, and even more preferably 0.15 to 4 mm, from the viewpoints of ensuring the strength of the honeycomb structure 10 and reducing pressure loss when the process gas passes through the cells 14. In this specification, the "thickness of the partition walls 15" refers to the length of a line segment that crosses the partition walls 15 when the line segment connects the centers of gravity of adjacent cells 14 in a cross section of the honeycomb structure 10 that is perpendicular to the extension direction of the cells 14. The thickness of the partition walls 15 refers to the average value of the thicknesses of all the partition walls 15.

[0050] The porosity of the partition walls 15 is not particularly limited, but is preferably 30% or more and less than 80%, more preferably 35% to 75%, and even more preferably 40% to 70%, from the viewpoints of ensuring the strength of the honeycomb structure 10 and reducing the pressure loss when the process gas passes through the cells 14. In this specification, the "porosity of the partition walls 15" means the porosity of the partition walls 15 measured by mercury porosimetry in accordance with JIS R1655:2003.

[0051] The average pore diameter of the partition walls 15 is not particularly limited, but is preferably 10 to 300 μm, more preferably 15 to 280 μm, and even more preferably 20 to 260 μm, from the viewpoints of ensuring the strength of the honeycomb structure 10 and reducing the pressure loss when the process gas passes through the cells 14. In this specification, the "average pore diameter of the partition walls 15" means the pore diameter of the partition walls 15 at an integrated value of 50% in the pore distribution determined by mercury intrusion porosimetry in accordance with JIS R1655:2003.

[0052] The thickness of the peripheral wall 11 is not particularly limited, but is preferably 0.05 to 10 mm, more preferably 0.20 to 8 mm, and even more preferably 0.30 to 6 mm, from the viewpoint of ensuring the strength of the honeycomb structure 10. In this specification, the thickness of the peripheral wall 11 refers to the length in the normal direction to the peripheral surface of the honeycomb structure 10 from the boundary between the peripheral wall 11 and the outermost cell 14 or partition wall 15 to the peripheral surface of the honeycomb structure 10 in a cross section perpendicular to the extension direction of the cells 14 of the honeycomb structure 10.

[0053] The cell density of the honeycomb structure 10 is not particularly limited, but from the viewpoint of ensuring the strength of the honeycomb structure 10 and increasing the amount of functional material carried, it is set to 0.05 to 25 cells / cm. 2 It is preferable that the density is 0.1 to 20 cells / cm 2 More preferably, the density is 0.5 to 15 cells / cm 2 In this specification, the term "cell density" refers to a value obtained by dividing the number of cells by the area of ​​one end face of the honeycomb structure 10 (the total area of ​​the partition walls 15 and the cells 14 excluding the outer peripheral wall 11).

[0054] The honeycomb structure 10 may further include a functional material (not shown) supported on the partition walls 15. The functional material may also be supported on the outer peripheral wall 11 facing the cells 14. Supporting the functional material enables the recovery (adsorption) and release (desorption) of the target gas from the process gas. The method for supporting the functional material is not particularly limited, and a layer containing the functional material may be formed on the partition walls 15 of the honeycomb structure 10 and the outer peripheral wall 11 facing the cells 14. The functional material is not particularly limited as long as it can recover the target gas contained in the process gas. For example, an adsorbent for the target gas can be used. By using an adsorbent as the functional material, the target gas can be adsorbed and recovered, and the recovered target gas can be easily desorbed by changing conditions such as temperature.

[0055] The adsorbent may be selected appropriately depending on the type of gas to be captured, and is not particularly limited. Examples of adsorbents that are effective for adsorbing target gases such as carbon dioxide (CO2) include amine compounds and organometallic complexes. Nanoporous ceramics or mesoporous silica supported with amine compounds and / or organometallic complexes may also be used. These may be used alone or in combination of two or more. Examples of amine compounds include, but are not limited to, monoethanolamine (MEA) and N-methyldiethanolamine (MDEA). Examples of organometallic complexes include, but are not limited to, porous metal-organic frameworks (MOFs) having a structure capable of adsorbing target gases in their pores. Among the various adsorbents listed above, amine compounds and / or metal-organic frameworks are preferred. By using these adsorbents, the amount of adsorption of target gases such as carbon dioxide (CO2) can be stably improved.

[0056] The thickness of the layer containing the functional material is not particularly limited and may be determined depending on the size of the cells 14. For example, from the viewpoint of ensuring sufficient contact with air, the thickness of the layer containing the functional material is preferably 20 μm or more, more preferably 25 μm or more, and even more preferably 30 μm or more. On the other hand, from the viewpoint of preventing the layer containing the functional material from peeling off from the partition walls 15 and the outer peripheral wall 11, the thickness of the layer containing the functional material is preferably 400 μm or less, more preferably 380 μm or less, and even more preferably 350 μm or less.

[0057] The manufacturing method of the honeycomb structure 10 having the above-mentioned structure is not particularly limited, but for example, the honeycomb structure 10 can be manufactured by a method including a step (step A) of making the honeycomb structure 10 having an outer peripheral wall 11 and partition walls 15 arranged inside the outer peripheral wall 11 and defining a plurality of cells 14 extending from the inlet end face 12 to the outlet end face 13, a step (step B) of forming communicating holes 16 in the outer peripheral wall 11 and the partition walls 15 of the honeycomb structure 10, and a step (step C) of supporting a functional material on the partition walls 15 of the honeycomb structure 10, etc.

[0058] In step A, the method for producing the honeycomb structure 10 is not particularly limited and can be carried out according to methods known in the art. For example, the honeycomb structure 10 can be produced as follows. First, a clay containing ceramic powder is extruded into a desired shape to produce a honeycomb formed body. By selecting an appropriate die and jig, the shape and density of each cell 14, the shape and thickness of the partition walls 15 and the outer peripheral wall 11, etc. can be controlled. The ceramic powder can be a ceramic powder or a raw material powder that becomes ceramic after firing (e.g., a cordierite raw material). The cordierite raw material is a raw material that becomes cordierite upon firing. The cordierite raw material preferably has a chemical composition of 30 to 45 mass% alumina (Al2O3) (including aluminum hydroxide converted to alumina), 11 to 17 mass% magnesia (MgO), and 42 to 57 mass% silica (SiO2). The clay may contain a binder, a pore-forming agent, a dispersant, water, an organic solvent, etc. The porosity and average pore diameter of the partition walls 15 can be controlled by appropriately selecting the type and amount of the ceramic powder, binder, pore-forming agent, and dispersant used. Next, the honeycomb formed body obtained above is dried and fired to obtain the honeycomb structure 10. The drying method is not particularly limited, and conventionally known drying methods such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, and freeze drying can be used. Among these, a drying method that combines hot air drying with microwave drying or dielectric drying is preferred because it can dry the entire honeycomb formed body quickly and uniformly.

[0059] In step B, communicating holes 16 are formed at predetermined positions in the honeycomb structure 10 obtained above. The method for forming the communicating holes 16 is not particularly limited, but for example, laser processing or the like can be used. By using laser processing, the communicating holes 16 can be easily formed at predetermined positions without deforming the honeycomb structure 10. The conditions for the laser processing are not particularly limited and can be adjusted appropriately depending on the type of laser processing machine used, etc.

[0060] Step C may be performed at any stage after Step A, but is typically performed after Step B. The method for supporting the functional material is not particularly limited, but may be, for example, the following process. The honeycomb structure 10 is immersed in a slurry containing the functional material, an organic binder, and a dispersion medium for a predetermined period of time, and excess slurry from the end faces and periphery of the honeycomb structure 10 is removed by blowing and wiping. The dispersion medium may be water, an organic solvent (e.g., toluene, xylene, ethanol, n-butanol, ethyl acetate, butyl acetate, terpineol, dihydroterpineol, Texanol, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether), or a mixture thereof. The slurry is then dried to support the functional material on the surfaces of the partition walls 15 and the like. Drying may be performed by heating the honeycomb structure 10 to a temperature of, for example, about 120 to 600°C. The series of steps of immersion, slurry removal, and drying may be carried out only once, but by repeating the steps multiple times, a desired amount of functional material can be supported.

[0061] In the above description, the honeycomb structure 10 is described in which a functional material (adsorbent) is supported on the surfaces of the outer peripheral wall 11 and the partition walls 15. However, a honeycomb structure 10 in which the outer peripheral wall 11 and the partition walls 15 are made of a material containing the functional material (adsorbent) may also be used. In this case, the outer peripheral wall 11 and the partition walls 15 may contain an organic binder, an inorganic binder, or the like in addition to the functional material (adsorbent). The functional material (adsorbent), the organic binder, and the inorganic binder may each contain one type alone or two or more types simultaneously.

[0062] (2. Storage Section 20) The storage section 20 is not particularly limited as long as it can store the honeycomb structure 10 and does not hinder the flow of the process gas and the purge gas. The storage section 20 may be in direct contact with the honeycomb structure 10 or indirect contact with it. For example, the storage section 20 may be a cylindrical member fitted to the outer periphery of the honeycomb structure 10. In this case, the cylindrical member needs to have openings so that the communicating holes 16 formed in the outer wall 11 are exposed. The method for storing the honeycomb structure 10 in the storage section 20 is not particularly limited, and known methods can be used. For example, when storing the honeycomb structure 10 in the cylindrical member, methods such as a fitting method using clearance fitting, interference fitting, or shrink fitting, as well as brazing, welding, or diffusion bonding can be used.

[0063] The material of the housing portion 20 is not particularly limited, but is preferably a metal from the viewpoint of manufacturability. For example, stainless steel, titanium alloy, copper alloy, aluminum alloy, brass, etc. can be used as the material of the housing portion 20. Among these, stainless steel is preferred because of its high durability, reliability, and low cost.

[0064] The inlet valve 21 and the outlet valve 22 provided in the storage section 20 are not particularly limited as long as they have the above-mentioned functions, and known valves can be used.

[0065] (3. Gas Supply Pipe 30 and Gas Exhaust Pipe 40) The gas supply pipe 30 (including the first gas supply branch pipe 31 and the second gas supply branch pipe 32) and the gas exhaust pipe 40 (including the first gas exhaust branch pipe 41 and the second gas exhaust branch pipe 42) are not particularly limited as long as they allow the flow of process gas and purge gas. The material of the gas supply pipe 30 and the gas exhaust pipe 40 is preferably a metal, and for example, stainless steel, titanium alloy, copper alloy, aluminum alloy, brass, etc. can be used. Among these, stainless steel is preferred because of its high durability, reliability, and low cost. Furthermore, the supply gas switching valve 33 provided in the gas supply pipe 30 and the exhaust gas switching valve 43 provided in the gas exhaust pipe 40 are also not particularly limited as long as they have the above-mentioned functions, and known valves can be used.

[0066] (4. Method of Using the Gas Recovery Apparatus) In the gas recovery apparatus according to the first embodiment of the present invention, when recovering a target gas contained in a process gas (in the case of adsorption mode), as shown in FIG. 1A , the inlet valve 21 is switched so that the process gas flows into the cells 14 at the inlet end face 12, and the outlet valve 22 is switched so that the process gas flows out of the cells 14 at the outlet end face 13. The supply gas switching valve 33 is switched so that the process gas is supplied from the first gas supply branch pipe 31, and the exhaust gas switching valve 43 is switched so that the process gas is exhausted from the first gas exhaust branch pipe 41. The process gas containing the target gas to be captured, supplied from the first gas supply branch pipe 31, flows through the cells 14 of the honeycomb structure 10 via the gas supply pipe 30, and the target gas to be captured is recovered during this process. The process gas from which the target gas to be captured has been recovered is then exhausted from the first gas exhaust branch pipe 41 via the gas exhaust pipe 40.

[0067] Next, when the target gas to be captured collected in the honeycomb structure 10 is desorbed (in the desorption mode), as shown in FIG. 1B , the inlet valve 21 is switched so that the purge gas flows into the communicating holes 16 of one of the opposing outer peripheral walls 11, and the outlet valve 22 is switched so that the purge gas flows out of the communicating holes 16 of the other opposing outer peripheral wall 11. The supply gas switching valve 33 is switched so that the purge gas is supplied from the second gas supply branch pipe 32, and the exhaust gas switching valve 43 is switched so that the purge gas is discharged from the second gas exhaust branch pipe 42. The purge gas supplied from the second gas supply branch pipe 32 then flows through the communicating holes 16 of the honeycomb structure 10 via the gas supply pipe 30, and the target gas to be captured is desorbed during this process. The honeycomb structure 10 can be heated to promote desorption of the target gas to be captured. The honeycomb structure 10 may be heated by a heating unit or by preheated purge gas. The purge gas containing the target gas is discharged from the second gas discharge branch pipe 42 via the gas discharge pipe 40 .

[0068] 3A and 3B are schematic diagrams of a gas recovery device according to a second embodiment of the present invention. Fig. 3A shows a state in which a process gas is circulated (adsorption mode), and Fig. 3B shows a state in which a purge gas is circulated (desorption mode). As shown in Figs. 3A and 3B, the gas recovery device according to the second embodiment of the present invention differs from the gas recovery device according to the first embodiment of the present invention in that the gas supply pipe 30 includes a first gas supply pipe 34 capable of supplying a process gas to the cells 14 at the inlet end surface 12 and a second gas supply pipe 35 capable of supplying a purge gas to the communicating holes 16 in one of the opposing outer peripheral walls 11, and the gas exhaust pipe 40 includes a first gas exhaust pipe 44 capable of exhausting the process gas from the cells 14 at the outlet end surface 13 and a second gas exhaust pipe 45 capable of exhausting the purge gas from the communicating holes 16 in the other opposing outer peripheral wall 11. Apart from this difference, the gas recovery apparatus according to the second embodiment of the present invention has the same configuration as the gas recovery apparatus according to the first embodiment of the present invention, and can therefore achieve the same effects as the gas recovery apparatus according to the first embodiment of the present invention. Note that components having the same reference numerals as those appearing in the description of the gas recovery apparatus according to the first embodiment of the present invention are the same as the components of the gas recovery apparatus according to the second embodiment of the present invention. Therefore, detailed description of the same components will be omitted, and only different components will be described.

[0069] In the gas recovery device according to the second embodiment of the present invention, when recovering a target gas contained in a process gas (in the adsorption mode), as shown in Fig. 3A, the inlet valve 21 is switched so that the process gas flows into the cells 14 at the inlet end face 12, and the outlet valve 22 is switched so that the process gas flows out from the cells 14 at the outlet end face 13. The process gas containing the target gas to be captured, supplied from the first gas supply pipe 34, flows through the cells 14 of the honeycomb structure 10, and the target gas to be captured is recovered during this process. The process gas from which the target gas to be captured has been recovered is discharged from the first gas discharge pipe 44.

[0070] Next, when the target gas to be captured collected in the honeycomb structure 10 is desorbed (in the desorption mode), as shown in FIG. 3B , the inlet valve 21 is switched so that the purge gas flows into the communicating holes 16 of one of the opposing outer peripheral walls 11, and the outlet valve 22 is switched so that the purge gas flows out from the communicating holes 16 of the other opposing outer peripheral wall 11. The purge gas supplied from the second gas supply pipe 35 flows through the communicating holes 16 of the honeycomb structure 10, during which the target gas to be captured is desorbed. At this time, the honeycomb structure 10 can be heated to promote the desorption of the target gas to be captured. The honeycomb structure 10 may be heated by a heating unit or by preheated purge gas. The purge gas containing the target gas to be captured is discharged from the second gas discharge pipe 45.

[0071] In the gas recovery apparatus according to the second embodiment of the present invention, the first gas supply pipe 34 and the second gas supply pipe 35 are used as the gas supply pipe 30, and therefore the supply gas switching valve 33 for switching the gas flowing through the gas supply pipe 30 to a processing gas or a purge gas is not required. Similarly, the first gas exhaust pipe 44 and the second gas exhaust pipe 45 are used as the gas exhaust pipe 40, and therefore the exhaust gas switching valve 43 for switching the gas flowing through the gas exhaust pipe 40 to a processing gas or a purge gas is not required. Therefore, the gas recovery apparatus according to the second embodiment of the present invention is easier to control in the adsorption mode and the desorption mode than the gas recovery apparatus according to the first embodiment of the present invention.

[0072] DESCRIPTION OF SYMBOLS 10 Honeycomb structure 11 Outer peripheral wall 12 Inlet end face 13 Outlet end face 14 Cell 15 Partition wall 16 Communication hole portion 20 Storage portion 21 Inlet valve 22 Outlet valve 30 Gas supply pipe 31 First gas supply branch pipe 32 Second gas supply branch pipe 33 Supply gas switching valve 34 First gas supply pipe 35 Second gas supply pipe 40 Gas exhaust pipe 41 First gas exhaust branch pipe 42 Second gas exhaust branch pipe 43 Exhaust gas switching valve 44 First gas exhaust pipe 45 Second gas exhaust pipe 50 Control unit 60 Sensor

Claims

1. A gas recovery device comprising: a honeycomb structure having an outer peripheral wall and partition walls disposed inside the outer peripheral wall that define a plurality of cells extending from an inflow end face to an outflow end face, wherein communicating holes are formed in opposing outer peripheral walls and in the partition wall between them, and which is capable of adsorbing and desorbing a target gas to be captured; a storage section that stores the honeycomb structure; a gas supply pipe connected to the storage section and capable of supplying a processing gas and / or purge gas containing the target gas to be captured; and a gas discharge pipe connected to the storage section and capable of discharging the processing gas and / or purge gas, wherein the gas recovery device is configured so that the processing gas flows from the cells at the inflow end face to the cells at the outflow end face, and the purge gas can flow from the communicating holes in one opposing outer peripheral wall to the communicating holes in the other outer peripheral wall.

2. The gas recovery device described in claim 1, wherein the storage section has an inlet valve capable of switching the inflow of each gas into the cells on the inlet end face or the communicating hole portion of one of the opposing outer walls, and an outlet valve capable of switching the outflow of each gas from the cells on the outlet end face or the communicating hole portion of the other opposing outer wall.

3. A gas recovery device as described in claim 2, further comprising a control unit capable of controlling the inlet valve and the outlet valve, wherein the control unit is capable of executing an adsorption mode in which the processing gas flows into the cells at the inlet end face and flows out of the cells at the outlet end face, and a desorption mode in which the purge gas flows into the communicating hole portion of one of the opposing outer peripheral walls and flows out of the communicating hole portion of the other outer peripheral wall.

4. A gas recovery device as described in claim 3, wherein a sensor capable of measuring the concentration of the target gas to be captured in the processing gas is arranged in the gas exhaust pipe, and the control unit executes the desorption mode after executing the adsorption mode when the concentration of the target gas to be captured reaches a predetermined value.

5. A gas recovery device according to any one of claims 1 to 4, wherein the gas supply piping has a gas supply branch piping branched into two, the gas supply branch piping being a first gas supply branch piping capable of supplying the processing gas and a second gas supply branch piping capable of supplying the purge gas; the gas exhaust piping has a gas exhaust branch piping branched into two, the gas exhaust branch piping being a first gas exhaust branch piping capable of exhausting the processing gas and a second gas exhaust branch piping capable of exhausting the purge gas; a supply gas switching valve capable of switching supply from the first gas supply branch piping or the second gas supply branch piping is provided at the branching portion of the gas supply piping, and an exhaust gas switching valve capable of switching exhaust from the first gas exhaust branch piping or the second gas exhaust branch piping is provided at the branching portion of the gas exhaust piping.

6. A gas recovery device according to any one of claims 1 to 4, wherein the gas supply piping is a first gas supply piping capable of supplying the processing gas to the cells at the inlet end face and a second gas supply piping capable of supplying the purge gas to the communicating hole portion of one of the opposing outer peripheral walls, and the gas exhaust piping is a first gas exhaust piping capable of exhausting the processing gas from the cells at the outlet end face and a second gas exhaust piping capable of exhausting the purge gas from the communicating hole portion of the other opposing outer peripheral wall.

7. The gas recovery device according to any one of claims 1 to 4, further comprising a heating section capable of heating the honeycomb structure.

8. A gas recovery device described in any one of claims 1 to 4, wherein the communication hole portion constitutes a group of communication holes arranged so as to be positioned on a straight line perpendicular to the direction in which the cells extend, and there are two or more groups of communication holes.

9. A gas recovery device as described in claim 8, wherein in a cross section of the honeycomb structure perpendicular to the direction in which the cells extend, the communicating hole portions of the group of communicating holes are arranged so that one straight line perpendicular to the direction in which the cells extend passes through the center of the honeycomb structure.

10. A gas recovery device as described in claim 8, wherein, in a cross section of the honeycomb structure parallel to the direction in which the cells extend, when the distance between the inlet end face and the center of the communicating hole portion in the communicating hole group closest to the inlet end face is D1, the distance between the inlet end face and the center of the communicating hole portion in the communicating hole group closest to the outlet end face is D2, and the length from the inlet end face to the outlet end face is L, the relationship D1 / L≦0.2 and / or D2 / L≧0.8 is satisfied.

11. A gas recovery device according to any one of claims 1 to 4, wherein the diameter of the communication hole portion is 20 to 80% of the diameter of the cell.

12. The gas recovery device according to any one of claims 1 to 4, wherein the honeycomb structure has a square pillar shape.

13. A gas recovery device according to any one of claims 1 to 4, wherein the shape of the cells in a cross section of the honeycomb structure perpendicular to the direction in which the cells extend is quadrangular or hexagonal.

14. A gas recovery device according to any one of claims 1 to 4, wherein the honeycomb structure is primarily composed of one or more materials selected from the group consisting of cordierite, mullite, alumina, silica, silicon carbide, and Si-bonded silicon carbide.

15. A gas recovery device according to any one of claims 1 to 4, wherein the honeycomb structure is made of one or more materials selected from paper, paper coated with a protective layer, nonwoven fabric, and nonwoven fabric coated with a protective layer.

16. A gas recovery device according to any one of claims 1 to 4, wherein the thickness of the partition is 0.05 to 5 mm.

17. A gas recovery device according to any one of claims 1 to 4, wherein the porosity of the partition wall is 30% or more and less than 80%.

18. A gas recovery device according to any one of claims 1 to 4, wherein the partition walls have an average pore size of 10 to 300 μm.

19. The gas recovery device according to any one of claims 1 to 4, further comprising a functional material carried on the partition wall.

20. The gas recovery device according to claim 19, wherein the functional material is an amine compound and / or a metal organic framework.

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