Carbon dioxide capture device

Abstract

The present invention provides a carbon dioxide recovery device that can apply a load evenly to each electrochemical cell. [Solution] The carbon dioxide recovery device 10 includes a laminate 140 formed by stacking a plurality of electrochemical cells 110, which adsorb and desorb CO2 from a CO2-containing gas by electrochemical reaction, under pressure in the cell stacking direction of the plurality of electrochemical cells 110; a pair of supports 151 and 152 positioned on one and the other in the cell stacking direction relative to the laminate 140; and an elastic body 154b provided between the pair of supports 151 and 152, which has a Young's modulus greater than that of the electrochemical cells 110. The elastic body 154b applies a load to the plurality of electrochemical cells 110 under pressure in the cell stacking direction by elastically deforming.

Description

Technical Field

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

Background Art

[0002] Conventionally, an electrochemical cell for separating gas species contained in a mixed gas has been proposed, for example, in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, an electrochemical cell is arranged in a structure capable of introducing a mixed gas. As a structure capable of introducing a mixed gas, for example, a plate-shaped cell frame having an upper surface and a lower surface opposite to the upper surface can be adopted.

[0005] Further, the electrochemical cell has a structure in which an insulating film is sandwiched between a working electrode and a counter electrode. Therefore, in order to prevent the working electrode and the counter electrode from peeling off from the insulating film, it is necessary to apply a load to the working electrode and the counter electrode. When the load is small, the solution resistance of the electrochemical cell increases. For this reason, the gas adsorption amount of the electrochemical cell may decrease, and as a result, the performance of the electrochemical cell may deteriorate.

[0006] Therefore, a unit composed of a cell frame and an electrochemical cell is defined as a single-layer cell, and it is conceivable to provide a protrusion on the lower surface of the cell frame of the upper layer. Then, a plurality of single-layer cells are stacked in the vertical direction perpendicular to the upper surface of the cell frame so that the upper surface of the cell frame of the lower-layer single-layer cell and the lower surface of the cell frame of the upper-layer single-layer cell face each other.

[0007] As a result, the protrusions on the cell frame of the upper single-layer cell come into contact with and press against the lower electrochemical cell. Therefore, a load can be applied to each electrochemical cell. In addition, the solution resistance of the electrochemical cell decreases and stabilizes at a constant value. A space is provided between the lower and upper single-layer cells. The mixed gas can come into contact with the electrochemical cell by passing through this space.

[0008] However, variations in the height of each electrochemical cell, as well as variations in the stacking of each electrochemical cell, may result in uneven load distribution across all cells. This could lead to variations in the performance of each electrochemical cell.

[0009] In view of the above, the present invention aims to provide a carbon dioxide recovery device that can apply a uniform load to each electrochemical cell. [Means for solving the problem]

[0010] To achieve the above objective, the invention described in claim 1 provides a carbon dioxide capture device, A laminate (140) is formed by stacking multiple electrochemical cells (110) that perform adsorption and desorption of CO2 from a CO2-containing gas by electrochemical reaction, under pressure in the cell stacking direction of the multiple electrochemical cells, A pair of supports (151, 152) are positioned on one side and the other side of the cell stacking direction relative to the laminate, An elastic body (154b) is provided between a pair of supports and has a Young's modulus greater than that of an electrochemical cell, Includes.

[0011] The elastic material, through elastic deformation, applies a load to multiple electrochemical cells under pressure in the direction of cell stacking.

[0012] The larger the Young's modulus, the less likely creep deformation is to occur, and the less likely stress relaxation is to progress. Therefore, even if an electrochemical cell deforms in a way that causes it to collapse due to creep deformation, the deformation will be in the form of stretching of the elastic body. Thus, the load on the electrochemical cell can be compensated for. Also, even if the load on the electrochemical cell decreases due to stress relaxation, the deformation will be in the form of stretching of the elastic body. Thus, in this case as well, the load on the electrochemical cell can be compensated for. In other words, even if the pressurized state on each electrochemical cell becomes uneven, an additional load based on the elastic body is applied to each electrochemical cell in addition to the pressurized state on each electrochemical cell. That is, the springiness of the elastic body works to equalize the pressurized force applied to each electrochemical cell. Therefore, a uniform load can be applied to each electrochemical cell.

[0013] The reference numerals in parentheses next to each means described in this section and in the claims indicate the correspondence with the specific means described in the embodiments described later. [Brief explanation of the drawing]

[0014] [Figure 1] This is a conceptual diagram showing the overall configuration of the carbon dioxide capture system according to the first embodiment. [Figure 2] Figure 2 is a perspective view showing a carbon dioxide capture device. [Figure 3] This is a cross-sectional view showing a portion of a laminate in which multiple single-layer cells are stacked. [Figure 4] This is a cross-sectional view of a cell stack. [Figure 5] This is a cross-sectional view showing a method of fixing a columnar structure to another support. [Figure 6] This is a plan view illustrating the positioning of the electrochemical cell. [Figure 7] This is a cross-sectional view of the cell stack according to the second embodiment. [Figure 8] This is a perspective view showing another example of a cell stack according to the second embodiment. [Figure 9] This is a cross-sectional view of a plurality of cell stacks according to the fourth embodiment. [Figure 10]It is a cross-sectional view showing another example of a plurality of cell stacks according to the fourth embodiment. [Figure 11] It is a cross-sectional view showing an elastic body according to the fifth embodiment. [Figure 12] It is a cross-sectional view of a cell stack according to the sixth embodiment. [Figure 13] It is a cross-sectional view for explaining load loss when a load is applied to the laminate at the clamping portion without arranging an elastic body. [Figure 14] It is a cross-sectional view showing another example of a cell stack according to the sixth embodiment.

Modes for Carrying Out the Invention

[0015] Hereinafter, a plurality of modes for carrying out the present disclosure will be described with reference to the drawings. In each mode, the same reference numerals may be assigned to portions corresponding to those described in the preceding mode, and redundant descriptions may be omitted. When only a part of the configuration is described in each mode, other modes described previously can be applied to other parts of the configuration.

[0016] Combinations are possible between parts that are explicitly shown to be combinable in each embodiment. Also, unless there is a problem with the combination, combinations are possible between embodiments, between an embodiment and a modification example, and between modification examples even if not explicitly shown to be combinable.

[0017] (First Embodiment) Hereinafter, the first embodiment will be described with reference to the drawings. The carbon dioxide recovery device recovers CO2 from a CO2-containing gas containing CO2 by an electrochemical reaction. The CO2-containing gas is, for example, the atmosphere. In the present embodiment, the case of recovering CO2 from the atmosphere will be described. A

[0018] As shown in Figure 1, the carbon dioxide recovery system 1 comprises a carbon dioxide recovery device 10, a pump 11, a flow path switching valve 12, a carbon dioxide utilization device 13, and a control device 14. Hereafter, the carbon dioxide recovery system 1, carbon dioxide recovery device 10, and carbon dioxide utilization device 13 will be referred to as CO2 recovery system 1, CO2 recovery device 10, and CO2 utilization device 13, respectively.

[0019] The CO2 recovery device 10 is a device that separates and recovers CO2 from a CO2-containing gas. The CO2-containing gas can be, for example, atmospheric air or exhaust gas from an internal combustion engine. The CO2-containing gas may also contain other gases besides CO2. The CO2 recovery device 10 receives the CO2-containing gas and discharges the CO2-removed gas (the gas remaining after CO2 has been recovered) or the CO2 recovered from the CO2-containing gas. The configuration of the CO2 recovery device 10 will be described in detail later.

[0020] Pump 11 supplies CO2-containing gas to the CO2 recovery device 10 and discharges CO2 or CO2-removed gas from the CO2 recovery device 10. In the example shown in Figure 1, pump 11 is located downstream of the CO2 recovery device 10 in the gas flow direction, but pump 11 may also be located upstream of the CO2 recovery device 10 in the gas flow direction.

[0021] The flow path switching valve 12 is a three-way valve that switches the flow path of the exhaust gas from the CO2 recovery device 10. When CO2 removal gas is discharged from the CO2 recovery device 10, the flow path switching valve 12 switches the exhaust gas flow path to the atmosphere side, and when CO2 is discharged from the CO2 recovery device 10, it switches the exhaust gas flow path to the CO2 utilization device 13 side.

[0022] The CO2 utilization device 13 is a device that utilizes CO2. The CO2 utilization device 13 can include, for example, a storage tank for storing CO2 or a conversion device for converting CO2 into fuel. The conversion device can be one that converts CO2 into a hydrocarbon fuel such as methane. The hydrocarbon fuel may be a gaseous fuel at room temperature and pressure, or a liquid fuel at room temperature and pressure.

[0023] The pump 11 may also be installed between the flow path switching valve 12 and the CO2 utilization device 13. In this case, during CO2 recovery, the pump 11 is not operated, and the CO2-containing gas is sent to the CO2 recovery device 10 by outside airflow or fan blowing. Also, during CO2 desorption, the pump 11 forcibly sends the CO2 to the CO2 utilization device 13.

[0024] The control device 14 consists of a well-known microcomputer including a CPU, ROM, and RAM, and its peripheral circuits. The control device 14 performs various calculations and processes based on the control program stored in the ROM, and controls the operation of various controlled devices. The control device 14 performs operation control of the CO2 recovery device 10, operation control of the pump 11, flow path switching control of the flow path switching valve 12, etc.

[0025] Next, the configuration of the CO2 recovery device 10 of this embodiment will be explained using Figures 2 to 6. In Figures 2 to 5, the direction from the front of the paper to the back of the paper is the gas flow direction, and the vertical direction of the paper is the cell stacking direction.

[0026] As shown in Figure 2, the CO2 recovery device 10 is equipped with a containment section 100. The containment section 100 is box-shaped. The containment section 100 can be constructed using, for example, a metal material. An electrochemical cell 110 is housed in the containment section 100. The CO2 recovery device 10 separates and recovers CO2 from the CO2-containing gas by adsorbing and desorbing CO2 through the electrochemical reaction of the electrochemical cell 110.

[0027] The containment section 100 has two openings. These two openings are an inlet 100a for introducing CO2-containing gas into the interior and an outlet (not shown) for discharging CO2 removal gas or CO2 from the interior. The gas flow direction is the flow direction of the CO2-containing gas as it passes through the containment section 100, and is the direction from the inlet 100a to the outlet of the containment section 100.

[0028] In Figure 2, the CO2-containing gas flows from the front of the page towards the back of the page. Therefore, the containment section 100 has an inlet 100a at the front of the figure and an outlet at the back of the figure. Note that the inlet 100a and outlet of the containment section 100 may be provided with opening and closing members.

[0029] Multiple electrochemical cells 110 are arranged at intervals inside the housing section 100. The direction in which the multiple electrochemical cells 110 are stacked is perpendicular to the direction of gas flow. Each individual electrochemical cell 110 is plate-shaped, and its plate surface is arranged to intersect with the cell stacking direction.

[0030] The electrochemical cell 110 is a device that recovers CO2 by adsorbing it from the atmosphere through an electrochemical reaction, while also capturing CO2 by desorbing it. As shown in Figure 3, the electrochemical cell 110 has a working electrode 111, a counter electrode 112, and an insulating film 113. The working electrode 111, the counter electrode 112, and the insulating film 113 are configured, for example, in the shape of plates.

[0031] The working electrode 111 has a first current collector and a first electrode film. The first current collector is a porous conductive member that can pass air through.

[0032] The first current collector only needs to have gas permeability and conductivity; for example, metal materials or carbonaceous materials can be used. As the carbonaceous material constituting the first current collector, for example, carbon paper, carbon cloth, nonwoven carbon mat, porous gas diffusion layer (GDL), etc., can be used. As the metal material constituting the first current collector, for example, a mesh structure made of metals such as Al, Ni, Ti, and SUS can be used. Of course, the first current collector may also be a porous metal body.

[0033] The first electrode film adsorbs and desorbs CO2 from the CO2-containing atmosphere through an electrochemical reaction. The first electrode film comprises a CO2 adsorbent, a conductive additive on the working electrode side, and a binder on the working electrode side.

[0034] CO2 adsorbents adsorb CO2 by accepting electrons and desorb the adsorbed CO2 by releasing electrons. For example, polyanthraquinone can be used as a CO2 adsorbent. Alternatively, carbon or metal oxides can be used as CO2 adsorbents.

[0035] The conductive additive on the working electrode side is a conductive substance that forms a conductive path to the CO2 adsorbent. As the conductive additive on the working electrode side, carbon materials such as carbon nanotubes, carbon black, and graphene can be used.

[0036] Mixing the CO2 adsorbent and the working electrode conductive additive can be done by dissolving or dispersing the working electrode conductive additive in an organic solvent such as NMP (N-methylpyrrolidone), and then bringing the working electrode conductive additive dispersed in the organic solvent into contact with the CO2 adsorbent.

[0037] The working electrode binder is a retaining material with adhesive properties. The working electrode binder holds the CO2 adsorbent and the working electrode conductive additive to the first current collector. This ensures the movement of electrons between the first current collector, the CO2 adsorbent, and the working electrode conductive additive. Furthermore, the CO2 adsorbent is less likely to peel off the first current collector, which suppresses the decrease in the amount of CO2 adsorbed by the electrochemical cell 110 over time.

[0038] As the binder on the working electrode side, a non-flowing material that does not have fluidity can be used. Examples of non-flowing materials include gel-like materials and solid materials. As a gel-like material, for example, an ionic liquid gel can be used. As a solid material, for example, a solid electrolyte or a conductive resin can be used.

[0039] When using a solid electrolyte as the working electrode binder, it is desirable to use an ionomer made of a polymer electrolyte or the like to increase the contact area with the CO2 adsorbent. When using a conductive resin as the working electrode binder, epoxy resins containing Ag, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and other fluororesins can be used as conductive fillers.

[0040] A mixture of CO2 adsorbent, working electrode-side conductive additive, and working electrode-side binder is formed, and this mixture is adhered to the first current collector. The CO2 adsorbent and working electrode-side conductive additive are held in place by the working electrode-side binder. As a result, the working electrode-side binder firmly holds the CO2 adsorbent and working electrode-side conductive additive. Furthermore, the CO2 adsorbent and working electrode-side conductive additive are less likely to peel off from the first current collector.

[0041] Furthermore, the first electrode film does not necessarily need to contain a binder on the working electrode side. In other words, the first electrode film can have a binderless configuration.

[0042] The counter electrode 112 has a second current collector and a second electrode film. The second current collector may be made of the same material as the first current collector, or a different material. For example, a metal plate can be used as the second current collector. The second current collector constituting the counter electrode 112 is placed on the upper surface 121 of the insulating frame 120, which will be described later.

[0043] The second electrode film exchanges electrons with the first electrode film. The second electrode film comprises a counter-electrode active material, a counter-electrode conductive additive, and a counter-electrode binder.

[0044] The counter electrode active material is an auxiliary electroactive species that exchanges electrons with the CO2 adsorbent of the first electrode film. The counter electrode active material is a substance that can exchange electrons through changes in the valence state of the metal or through charge exchange in and out of the π electron cloud.

[0045] As the counter-electrode active material, for example, a metal complex that enables electron transfer by changing the valence of a metal ion can be used. Examples of such metal complexes include cyclopentadienyl metal complexes such as ferrocene, nickerosene, and cobaltocene, or porphyrin metal complexes. These metal complexes may be polymers or monomers.

[0046] The counter electrode conductive additive is a conductive material that forms a conductive path to the counter electrode active material. The counter electrode conductive additive is used in mixture with the counter electrode active material. The counter electrode conductive additive may be made of the same material as the working electrode conductive additive, or it may be made of a different material. The counter electrode conductive additive is, for example, in particulate form.

[0047] The counter electrode binder is a conductive material that can hold the counter electrode active material and the counter electrode conductive additive in the second current collector. The counter electrode binder may be made of the same material as the working electrode binder, or it may be made of a different material.

[0048] Furthermore, the second electrode film does not necessarily need to contain a counter-electrode binder. In other words, the second electrode film can have a binderless configuration.

[0049] The insulating film 113 is an insulating ion-permeable film that allows ions to pass through. The insulating film 113 is placed between the first electrode film of the working electrode 111 and the second electrode film of the counter electrode 112. The insulating film 113 is sandwiched between the first electrode film and the second electrode film, and also separates the first electrode film and the second electrode film. In other words, the insulating film 113 prevents physical contact between the first electrode film and the second electrode film. Furthermore, the insulating film 113 suppresses electrical short circuits between the first electrode film and the second electrode film.

[0050] As the material for the insulating film 113, cellulose films, polymers, composite materials of polymers and ceramics, etc., can be used. A porous material may also be used as the insulating film 113.

[0051] Furthermore, ion-conducting members may be provided between the first electrode film and the insulating film 113, or between the second electrode film and the insulating film 113. The ion-conducting members promote conductivity to the CO2 adsorbent.

[0052] The electrochemical cell 110 is provided with a power supply (not shown) connected to the first current collector of the working electrode 111 and the second current collector of the counter electrode 112. The power supply can apply a predetermined voltage to the working electrode 111 and the counter electrode 112, thereby changing the potential difference between the working electrode 111 and the counter electrode 112.

[0053] The electrochemical cell 110 operates by changing the potential difference between the working electrode 111 and the counter electrode 112, thereby switching between a CO2 recovery mode in which CO2 is recovered at the working electrode 111 and a CO2 release mode in which CO2 is released from the working electrode 111. The CO2 recovery mode is a charging mode in which the electrochemical cell 110 is charged, and the CO2 release mode is a discharge mode in which the electrochemical cell 110 is discharged.

[0054] In CO2 recovery mode, a first voltage V1 is applied between the working electrode 111 and the counter electrode 112, and electrons are supplied from the counter electrode 112 to the working electrode 111. At the first voltage V1, the working electrode potential is less than the counter electrode potential. The first voltage V1 can be, for example, within the range of 0.5V to 2.0V.

[0055] In CO2 emission mode, a second voltage V2 is applied between the working electrode 111 and the counter electrode 112, supplying electrons from the working electrode 111 to the counter electrode 112. The second voltage V2 is different from the first voltage V1. The second voltage V2 only needs to be lower than the first voltage V1.

[0056] For example, a reference electrode may be provided. In this case, if the working electrode-counter electrode potential is +1V and the working electrode-reference electrode potential is -1V, then the counter electrode-reference electrode potential is +2V, meaning the working electrode potential is less than the counter electrode potential.

[0057] Furthermore, the CO2 recovery device 10 includes an insulating frame 120. The insulating frame 120 is a plate-shaped component having an upper surface 121 and a lower surface 122 opposite to the upper surface 121. The electrochemical cell 110 is positioned on the upper surface 121 of the insulating frame 120.

[0058] The insulating frame 120 is a resin molded product formed from a highly rigid insulating resin material such as polypropylene. The top surface 121 is, for example, rectangular. Of course, the top surface 121 may be of a shape other than rectangular.

[0059] The insulating frame 120 has a wall portion 123 that protrudes from a part of the upper surface 121 along the cell stacking direction. The wall portion 123 is provided along the gas flow direction at both ends of the upper surface 121 in the direction perpendicular to the gas flow direction. The height of the wall portion 123 relative to the upper surface 121 is lower than that of the electrochemical cell 110. Of course, the height of the wall portion 123 is just an example, and it may be the same height as the electrochemical cell 110 or higher than the electrochemical cell 110. The wall portion 123 may be separate from the plate-like portion.

[0060] Furthermore, the insulating frame 120 has a foot portion 124 that protrudes in the direction of cell stacking from a part of its lower surface 122. The foot portion 124 is for pressing a part of the lower electrochemical cell 110 in the direction of cell stacking. For example, the foot portion 124 is integrally molded with the lower surface 122.

[0061] Furthermore, the foot portion 124 does not need to protrude at a 90° angle to the lower surface 122; it may be inclined relative to the lower surface 122. Also, the foot portion 124 does not need to be integrated with the lower surface 122 of the insulating frame 120, and may be separate from the plate-like portion. Moreover, the length (width) of the foot portion 124 in the direction perpendicular to the cell stacking direction does not need to be constant. In other words, the thickness of the foot portion 124 does not need to be constant in the cell stacking direction.

[0062] Here, the units of the insulating frame 120 and the electrochemical cell 110 are defined as single-layer cells 130. Multiple single-layer cells 130 are stacked in the cell stacking direction. As a result, multiple single-layer cells 130 constitute a laminate 140 of single-layer cells 130.

[0063] Furthermore, each electrochemical cell 110 is pressed in by the feet 124 of the upper insulating frame 120, so it is stacked under pressure in the cell stacking direction. Each electrochemical cell 110 is under pressure from above when multiple cells are stacked. Note that the direction in which the working electrodes 111 etc. of each individual electrochemical cell 110 are stacked and the cell stacking direction in which multiple electrochemical cells 110 are stacked are the same direction.

[0064] A flow path for air to pass through is configured between the lower and upper single-layer cells 130 of the multiple single-layer cells 130. The width of the flow path is the space between the electrochemical cell 110 of the lower single-layer cell 130 and the lower surface 122 of the insulating frame 120 of the upper single-layer cell 130. The air passes through the space 141 corresponding to the width of the flow path.

[0065] In the above configuration, the laminate 140 is part of the cell stack. As shown in Figure 4, the cell stack 150 is composed of the laminate 140, a pair of supports 151 and 152, a plurality of columnar structures 153, and an elastic part 154. The cell stack 150 is housed in the housing section 100.

[0066] The pair of supports 151 and 152 are plate members positioned on one side and the other side of the cell stacking direction of the multiple electrochemical cells 110 relative to the laminate 140. One support 151 is the bottom plate, and the other support 152 is the top plate.

[0067] One support 151 has a face 151a facing the other support 152. The multiple columnar structures 153 are supports for maintaining the distance between the pair of supports 151 and 152. The multiple columnar structures 153 are fixed to the face 151a of one support 151. The multiple columnar structures 153 are perpendicular to the face 151a of one support 151 and extend in the direction of cell stacking. The pair of supports 151 and 152 and the columnar structures 153 are made of, for example, metal or resin.

[0068] The other support 152 is fixed to the columnar structure 153 on the side opposite to the other support 151. As shown in Figure 5, the columnar structure 153 and the other support 152 are not directly fixed to each other. The columnar structure 153 and the other support 152 are indirectly fixed together by fittings 155, bolts 156, and springs 157.

[0069] The fitting 155 is, for example, an L-shaped fitting. The fitting 155 is not limited to an L-shaped fitting, and may be a fitting of other shape. The spring 157 is, for example, a coil spring, a disc spring, a leaf spring, etc. The bolt 156 fixes the fitting 155 to the side wall surface of the columnar structure 153. Fixing one end of the spring 157 to the other support 152, and fixing the other end of the spring 157 to the support 152, can be done by, for example, welding, adhesive, mechanical fastening such as clips, etc. Alternatively, the spring 157 does not need to be fixed. For example, the spring 157 may be simply sandwiched between the other support 152 and the fitting 155 by the pressing force of the spring 157 alone.

[0070] Note that Figure 5 shows only one fixing point. In reality, a fitting 155 is fixed to each columnar structure 153. In Figure 5, the laminated body 140 and the elastic part 154 are omitted. Also, in Figures 4 and other cross-sectional views besides Figure 5, the fitting 155, bolt 156, and spring 157 are omitted.

[0071] In this embodiment, the orthogonal surfaces perpendicular to the cell stacking direction in the pair of supports 151 and 152 are rectangular in shape. The columnar structures 153 are positioned at the four corners of each orthogonal surface of each support 151 and 152. Each electrochemical cell 110 is positioned between the pair of supports 151 and 152. Positioning only requires a seating surface for each electrochemical cell 110 and positioning surfaces in two directions of the surface direction of the seating surface.

[0072] The seating surface of the electrochemical cell 110 to be positioned is the single-layer cell 130 located in the lower layer. The seating surface of the lowest single-layer cell 130 (electrochemical cell 110) is one of the support members 151. The positioning surfaces in two directions are the side walls of the columnar structure 153. In other words, each electrochemical cell 110 is positioned by contacting the side walls of at least two columnar structures 153 located in different directions among the plane directions parallel to the plane perpendicular to the cell stacking direction. The lowest single-layer cell 130 may also be positioned by a groove provided in the support member 151.

[0073] As shown in Figure 6, the laminate 140 is in contact with the side walls of two of the four columnar structures 153. In this embodiment, one of the two different directions is the gas flow direction, and the other is a direction perpendicular to both the gas flow direction and the cell lamination direction.

[0074] The laminate 140 consists of alternating layers of electrochemical cells 110 and insulating frames 120. Therefore, depending on the shape of the insulating frame 120, each electrochemical cell 110 may be indirectly positioned by the insulating frame 120 contacting the columnar structure 153. In other words, the target of positioning may be the insulating frame 120, not the electrochemical cell 110. Alternatively, the target of positioning may be said to be the single-layer cell 130.

[0075] By positioning each electrochemical cell 110, it is possible to avoid situations where the load is not properly applied to some of the electrochemical cells 110. In addition, the elastic portion 154 allows a uniform load to be applied to all electrochemical cells 110.

[0076] As shown in Figure 4, the elastic portion 154 is positioned between a pair of supports 151 and 152 and is a component for applying a load in the cell stacking direction to each electrochemical cell 110 constituting the laminate 140. In this embodiment, as shown in Figure 4, the elastic portion 154 has a plate portion 154a and an elastic body 154b.

[0077] The plate portion 154a is a plate member positioned between the other support 152 and the laminate 140. The plate portion 154a is in contact with the uppermost electrochemical cell 110 of the laminate 140. As the plate portion 154a, a stainless steel or aluminum-based metal plate or a high-density resin plate can be used.

[0078] The elastic body 154b is a component that applies pressure to the laminate 140 by applying a load to the laminate 140 in the cell stacking direction. In this embodiment, multiple elastic bodies 154b are provided between a pair of supports 151 and 152, between the other support 152 and the plate portion 154a, and are fixed to the other support 152 and the plate portion 154a.

[0079] The elastic body 154b is a spring material such as a compression coil spring or leaf spring, formed from metal, resin, or the like. The number of elastic bodies 154b is appropriately selected based on their size, shape, force, material, etc. The elastic body 154b may also be made of an expandable resin material such as rubber.

[0080] For example, if the elastic body 154b is made of a metallic material, it is composed of a material containing at least one of stainless steel, high-carbon steel, or nickel. These metallic materials are used as springs. Stainless steel is an excellent material in terms of corrosion resistance. The Young's modulus of SUS304 is, for example, 193 GPa. The Young's modulus of nickel is, for example, 199 GPa to 220 GPa.

[0081] The elastic body 154b is positioned between the other support 152 and the plate portion 154a in a compressed state. Therefore, the elastic body 154b elastically deforms to stretch in the cell stacking direction, thereby transmitting a force to the plate portion 154a in the cell stacking direction. In other words, the elastic body 154b imparts a restoring force to the plate portion 154a that returns it to its original shape from its compressed state. The plate portion 154a applies the force transmitted from the elastic body 154b, i.e., the restoring force, to the uppermost electrochemical cell 110 of the laminate 140. As a result, the load of the elastic body 154b is applied to the entire electrochemical cell 110. In other words, the load is the load at the contact surface of the plate portion 154a within the electrochemical cell 110.

[0082] Furthermore, the elastic body 154b does not necessarily have to be directly connected to both the other support 152 and the plate portion 154a. For example, the elastic body 154b may be connected to a projection provided on the other support 152 or the plate portion 154a. The projection may be provided on one of the other support 152 and the plate portion 154a, or on both. In addition, the load of the spring 157 that supports the other support 152 may be applied directly or indirectly to the laminate 140.

[0083] Here, the Young's modulus of the elastic body 154b is greater than that of the electrochemical cell 110. Materials with a larger Young's modulus undergo less creep deformation. The electrochemical cell 110 is prone to creep deformation due to its constituent materials. Therefore, if the Young's modulus of the elastic body 154b is greater than that of the electrochemical cell 110, the elastic body 154b will have an elastic range greater than the creep deformation of the electrochemical cell 110. As a result, the elastic body 154b can maintain a constant load applied to each electrochemical cell 110 via the plate portion 154a.

[0084] The above describes the overall configuration of the CO2 recovery system 1 and CO2 recovery device 10 according to this embodiment.

[0085] Next, the operation of the CO2 capture system 1 will be described. As described above, the CO2 capture system 1 operates by alternately switching between CO2 capture mode and CO2 release mode. The operation of the CO2 capture system 1 is controlled by the control device 14.

[0086] First, let's explain the CO2 recovery mode. In CO2 recovery mode, the door of the CO2 recovery device 10 is opened, and outside air is introduced into the CO2 recovery device 10. This supplies CO2-containing gas to the CO2 recovery device 10. In the CO2 recovery device 10, the voltage applied between the working electrode 111 and the counter electrode 112 of the electrochemical cell 110 is defined as the first voltage V1. This allows for the simultaneous donation of electrons to the electroactivating auxiliary material of the counter electrode 112 and the withdrawal of electrons to the CO2 adsorbent of the working electrode 111.

[0087] The CO2 adsorbent on the working electrode 111, having received electrons from the counter electrode 112, has a higher binding force to CO2, and thus binds to and adsorbs the CO2 contained in the CO2-containing gas. As a result, the CO2 recovery device 10 can recover CO2 from the CO2-containing gas. The CO2-removed gas, after the CO2 has been removed, is discharged from the CO2 recovery device 10.

[0088] In CO2 recovery mode, the control device 14 switches the flow path switching valve 12 so that the CO2-removed gas emitted from the CO2 recovery device 10 flows out to the atmosphere. As a result, the CO2-removed gas emitted from the CO2 recovery device 10 is released into the atmosphere.

[0089] Next, the CO2 release mode will be described. In the CO2 release mode, the control device 14 stops the pump 11. This stops the supply of CO2-containing gas to the CO2 recovery device 10. In the CO2 recovery device 10, the voltage applied between the working electrode 111 and the counter electrode 112 of the electrochemical cell 110 is set to the second voltage V2. This allows for the simultaneous donation of electrons to the CO2 adsorbent of the working electrode 111 and the withdrawal of electrons to the electroactivating auxiliary material of the counter electrode 112.

[0090] The CO2 adsorbent at the working electrode 111 releases electrons and enters an oxidized state. The CO2 adsorbent's ability to bind to carbon dioxide decreases, and it desorbs and releases CO2. The CO2 released from the CO2 adsorbent is discharged from the CO2 recovery device 10.

[0091] In CO2 release mode, the control device 14 switches the flow path switching valve 12 so that the CO2 emitted from the CO2 recovery device 10 flows out to the inlet side of the CO2 utilization device 13. As a result, the CO2 emitted from the CO2 recovery device 10 is supplied to the CO2 utilization device 13.

[0092] In a system where the pump 11 is located between the flow path switching valve 12 and the CO2 utilization device 13, in CO2 recovery mode, the control device 14 does not operate the pump 11, but instead sends CO2-containing gas to the CO2 recovery device 10 using outside airflow or fan blowing. In CO2 release mode, the control device 14 operates the pump 10 to forcibly send CO2 to the CO2 utilization device 13.

[0093] As described above, the CO2 recovery system 1 of this embodiment allows for the recovery of CO2 from CO2-containing gas and the effective utilization of the recovered CO2.

[0094] In this embodiment, the CO2 recovery device 10 is configured to apply an additional load to each electrochemical cell 110, which is already pressurized due to being stacked in multiple layers, through the elastic deformation of the elastic body 154b. As a result, even if there are variations in the height of each electrochemical cell 110 or variations in the stacking of each electrochemical cell 110, an additional load based on the elastic body 154b is applied to each electrochemical cell 110. Therefore, even if the pressurized state of each electrochemical cell 110 becomes non-uniform due to creep deformation or stress relaxation, the springiness of the elastic body 154b can equalize the pressurizing force applied to each electrochemical cell 110. Consequently, a uniform load can be applied to each electrochemical cell 110. Furthermore, the performance of each electrochemical cell 110 can be made uniform.

[0095] As another example, the elastic portion 154 may be positioned between the laminate 140 and one of the supports 151. In this case, the elastic portion 154 can apply an additional load based on the elastic portion 154b to each electrochemical cell 110 constituting the laminate 140 by pushing the laminate 140 from bottom to top.

[0096] As another example, the elastic portion 154 does not necessarily have a plate portion 154a. In this case, the elastic body 154b is positioned between the other support 152 and the uppermost single-layer cell 130, and the elastic body 154b directly presses the uppermost single-layer cell 130 in the cell stacking direction. Alternatively, the elastic body 154b is positioned between one support 151 and the bottommost single-layer cell 130, and the elastic body 154b directly presses the bottommost single-layer cell 130 in the cell stacking direction.

[0097] (Second Embodiment) This embodiment will mainly describe the differences from the first embodiment. As shown in Figure 7, the elastic body 154b is provided between the plate portion 154a and one of the supports 151 and 152, and is fixed to the plate portion 154a and one of the supports 151.

[0098] The elastic body 154b is positioned between the plate portion 154a and one of the support members 151 in an extended state. Therefore, the elastic body 154b transmits force to the plate portion 154a in the cell lamination direction by elastically deforming to contract in the cell lamination direction.

[0099] As described above, by applying a load to each electrochemical cell 110 using the force that causes the elastic body 154b to contract, the same effect as in the first embodiment can be obtained.

[0100] As another example, as shown in Figure 8, the plate portion 154a has one connecting portion 154c protruding from one of the support members 151. The support member 151 has the other connecting portion 154d protruding from the plate portion 154a. The elastic body 154b is positioned between the one connecting portion 154c and the other connecting portion 154d, and may also be connected to each of the connecting portions 154c and 154d.

[0101] Alternatively, the plate portion 154a may not have one connecting portion 154c, and one support 151 may have the other connecting portion 154d, and the elastic body 154b may be positioned between the plate portion 154a and the other connecting portion 154d, and also connected to the plate portion 154a and the other connecting portion 154d. Alternatively, the plate portion 154a may have one connecting portion 154c, and one support 151 may not have the other connecting portion 154d, and the elastic body 154b may be positioned between the one connecting portion 154c and one support 151, and also connected to the one connecting portion 154c and one support 151. Thus, the elastic body 154b does not have to be directly connected to both the plate portion 154a and one support 151.

[0102] As another example, the elastic portion 154 may be positioned between the laminate 140 and one of the support members 151. In this case, the laminate 140 is sandwiched between the other support member 152 and the plate portion 154a, and is floating above the one support member 151.

[0103] (Third embodiment) This embodiment will mainly describe the differences from the first and second embodiments. In this embodiment, the elastic body 154b is included in the electrochemical cell 110. For example, the elastic body 154b constitutes the first current collector of the working electrode 111 and the second current collector of the counter electrode 112 that make up the electrochemical cell 110. Note that the elastic body 154b may be provided only on the working electrode 111 or only on the counter electrode 112.

[0104] The elastic body 154b is, for example, a nonwoven fabric (SUS felt) made of SUS. The SUS nonwoven fabric is made up of intertwined SUS metal fibers arranged in layers. The SUS nonwoven fabric is manufactured by compressing and molding fibrous SUS. The SUS nonwoven fabric can be said to constitute an aggregate of thin SUS wire springs. Of course, the nonwoven fabric may also be made of metal materials other than SUS. With the above configuration, the same effects as in the first embodiment can be obtained.

[0105] The elastic body 154b may be positioned above or below the electrochemical cell 110, as a separate entity from the electrochemical cell 110. In this case, the elastic body 154b may be positioned only above the electrochemical cell 110, or only below the electrochemical cell 110.

[0106] Furthermore, the elastic body 154b is not limited to felt made of a metal material. The elastic body 154b may be composed of layers of resin material such as plastic or rubber. Also, the electrochemical cell 110 containing the elastic body 154b is not electrically connected to the electrochemical cell 110 directly above or below it via the elastic body 154b.

[0107] (Fourth Embodiment) This embodiment will mainly describe the differences from the embodiments described above. As shown in Figure 9, in this embodiment, a plurality of cell stacks 150 are stacked in the cell stacking direction. In addition, in each cell stack 150, the elastic body 154b is provided in the cell stack 150 so as not to be subjected to the load of one of the support members 151 of the upper cell stack 150.

[0108] Specifically, the other support 152 is located on the side of the support 151 rather than the upper end of each columnar structure 153, and is bolted in the direction perpendicular to the cell stacking direction as described above. The upper cell stack 150 is stacked on top of each columnar structure 153 that make up the lower cell stack 150.

[0109] Furthermore, the elastic body 154b is connected only to the uppermost electrochemical cell 110 of the laminate 140. Here, connection means that only the load based on the elastic body 154b is applied to the uppermost electrochemical cell 110. Therefore, the elastic body 154b applies a load to the uppermost electrochemical cell 110 of the laminate 140 without being affected by the load of the upper cell stack 150.

[0110] With the above configuration, in a stack of multiple cell stacks 150, the electrochemical cells 110 located in the lower cell stack 150 can receive an appropriate load from the elastic body 154b without being affected by the weight of the cell stack 150 located in the upper cell stack. The same applies to the cell stacks 150 shown in the second and third embodiments.

[0111] As another example, as shown in Figure 10, in a plurality of cell stacks 150, the support 151 of the upper cell stack 150 and the other support 152 of the lower cell stack 150 may be common. By commonizing the supports 151 and 152, the other support 152 can be eliminated.

[0112] Even if the upper and lower supports 151 and 152 are common, the upper cell stack 150 is supported by the lower columnar structure 153. Therefore, the elastic body 154b is not affected by the load of the upper cell stack 150. The same applies to the cell stack 150 shown in the second and third embodiments.

[0113] (Fifth embodiment) This embodiment will mainly describe the differences from the embodiments described above. In this embodiment, a leaf spring is used as the elastic body 154b.

[0114] As shown in Figure 11, the elastic body 154b is sandwiched between stacked upper and lower electrochemical cells 110. The elastic body 154b, acting as a leaf spring, is made of insulating material 154e in at least the portion that contacts the electrochemical cells 110. The insulating material 154e is an electrically insulating material such as insulating paint or resin material.

[0115] This prevents the leaching of the elastic material 154b into the upper and lower electrochemical cells 110. Furthermore, the elastic material 154b and the insulating material 154e allow a load to be applied to the upper and lower electrochemical cells 110 while electrically insulating them from each other.

[0116] Furthermore, a disc spring may be used as the elastic body 154b. Disc springs and leaf springs have the advantage of minimizing the thickness in the cell stacking direction compared to coil springs and spiral springs. In addition, the entire elastic body 154b may be covered with insulating material 154e. Alternatively, the elastic body 154b itself may be made of insulating material 154e. Of course, the elastic body 154b according to this embodiment may be applied to each of the above embodiments.

[0117] (Sixth Embodiment) This embodiment will mainly describe the differences from the embodiments described above. In this embodiment, as shown in Figure 12, the cell stack 150 is composed of a laminate 140, a pair of supports 151 and 152, an elastic body 154b, and a set of clamping parts 158 and 159. The cell stack 150 may or may not have a columnar structure 153.

[0118] The clamping portions 158 and 159 clamp and fix the outer edges 151b and 152b of the pair of supports 151 and 152 in the direction perpendicular to the cell stacking direction, when the laminate 140 is positioned between the pair of supports 151 and 152. The clamping portions 158 and 159 are arranged as a pair in a direction perpendicular to the cell stacking direction and the gas flow direction, for example. The clamping portions 158 and 159 are fixed to the pair of supports 151 and 152, for example, by screws.

[0119] In this embodiment, the elastic body 154b is positioned on the outermost side of the laminate 140 in the cell stacking direction. For example, the elastic body 154b is positioned in both one and the other direction of the cell stacking. In other words, the laminate 140 is sandwiched between two elastic bodies 154b.

[0120] The outermost part of the laminate 140 in the cell stacking direction is expected to experience the largest load fluctuations because it receives the cumulative creep deformation of each electrochemical cell 110. Therefore, by placing the elastic body 154b on the outermost part of the laminate 140, it becomes possible to follow the cumulative creep deformation. Thus, the efficiency of load application to each electrochemical cell 110 is maximized.

[0121] The elastic body 154b is positioned in the central portion 142 of the laminate 140 in a direction perpendicular to the cell stacking direction. Here, the central portion 142 is a predetermined region of the laminate 140 that includes the center of the plane perpendicular to the cell stacking direction. The central portion 142 can also be described as a region of the laminate 140 that does not include the outer edge of the plane perpendicular to the cell stacking direction. In other words, the elastic body 154b is positioned away from the clamping portions 158 and 159.

[0122] As shown in Figure 13, in a configuration where the outer edges 151b and 152b of a pair of supports 151 and 152 are clamped by clamping parts 158 and 159, the load of the clamping parts 158 and 159 is applied to the outer edges 151b and 152b, while the load of the clamping parts 158 and 159 is less likely to be applied to positions away from the outer edges 151b and 152b. Note that the elastic body 154b is omitted in Figure 13.

[0123] Therefore, in the direction perpendicular to the cell stacking direction and the gas flow direction, there is a difference in the magnitude of the load in the cell stacking direction between the edges and the central part 142 of the laminate 140. In this way, the load of the clamping parts 158 and 159 is less likely to be applied to the positions of the laminate 140 that are far from the clamping parts 158 and 159, so there is a possibility of load loss.

[0124] In contrast, in this embodiment, as shown in Figure 12, the elastic body 154b is positioned in the central part 142 of the laminate 140 in a direction perpendicular to the cell stacking direction, so that the application of load to the laminate 140 is maintained by the reaction force of the elastic body 154b. Therefore, load release by the clamping parts 158 and 159 can be efficiently prevented.

[0125] As another example, as shown in Figure 14, the elastic body 154b may be positioned in only one of the cell stacking directions. In other words, the laminate 140 does not have to be sandwiched between two elastic bodies 154b. There may be one elastic body 154b or multiple elastic bodies. Note that in Figure 14, the clamping parts 158, 159 and the columnar structure 153 are omitted.

[0126] (Other embodiments) The configurations of the CO2 recovery device 10 shown in each of the above embodiments are examples, and the present invention can be realized with other configurations without being limited to those shown above. For example, the CO2-containing gas is not limited to the atmosphere, but can be any gas that contains CO2.

[0127] A columnar structure 153 is not required between the pair of supports 151 and 152, as long as it can hold the pair of supports 151 and 152. For example, the pair of supports 151 and 152 may be fixed inside the housing 100.

[0128] Figures 9 and 10 show a case where the cell stack 150 has two layers, but this is just one example. Of course, the cell stack 150 can be stacked in three or more layers.

[0129] The features of the CO2 recovery device 10 disclosed herein are as follows: (Item 1) A laminate (140) is formed by stacking a plurality of electrochemical cells (110) that adsorb and desorb CO2 from a CO2-containing gas by an electrochemical reaction, under pressure in the cell stacking direction of the plurality of electrochemical cells, A pair of supports (151, 152) are arranged in one and the other direction of the cell stacking relative to the laminate, An elastic body (154b) is provided between the pair of supports and has a Young's modulus greater than that of the electrochemical cell, Includes, The aforementioned elastic body elastically deforms to apply a load to a plurality of electrochemical cells under pressure in the cell stacking direction, thereby enabling carbon dioxide recovery. (Item 2) The carbon dioxide recovery apparatus according to item 1, wherein the elastic body is electrically insulated in at least the portion that comes into contact with the electrochemical cell. (Item 3) With the laminated body positioned between the pair of supports, it includes clamping portions (158, 159) that clamp and fix the outer edges (151b, 152b) of the pair of supports in a direction perpendicular to the cell stacking direction, The carbon dioxide recovery apparatus according to item 1 or 2, wherein the elastic body is located in the central part (142) of the laminate in a direction perpendicular to the cell stacking direction. (Item 4) The carbon dioxide recovery device according to any one of items 1 to 3, wherein the elastic body is located on the outermost side of the laminate in the cell stacking direction. (Item 5) The carbon dioxide recovery device according to any one of items 1 to 4, wherein the elastic body is a disc spring or a leaf spring. (Item 6) The carbon dioxide capture device according to any one of items 1 to 5, wherein the elastic body is made of a material including at least one of stainless steel, high-carbon steel, and nickel. (Item 7) One of the pair of supports (151) has a side (151a) facing the other of the pair of supports (152), It includes a plurality of columnar structures (153) that are fixed to one surface of the one support and are perpendicular to the one surface of the one support and extend in the cell stacking direction, The other support is fixed to the columnar structure on the side opposite to the first support, A carbon dioxide recovery apparatus according to any one of items 1 to 6, wherein the plurality of electrochemical cells are positioned by contacting at least two of the columnar structures located in different directions among the plane directions parallel to the plane perpendicular to the cell stacking direction. (Item 8) One of the pair of supports (151) has a side (151a) facing the other of the pair of supports (152), It includes a plurality of columnar structures (153) that are fixed to one surface of the one support and are perpendicular to the one surface of the one support and extend in the cell stacking direction, The other support is fixed to the columnar structure on the side opposite to the first support, If the laminate, the pair of supports, and the set of the plurality of columnar structures are defined as a cell stack (150), then the plurality of cell stacks are stacked in the cell stacking direction, The carbon dioxide recovery apparatus according to any one of items 1 to 7, wherein the elastic body applies a load to the uppermost electrochemical cell of the laminate without being subjected to the load of one of the support bodies of the cell stack in the upper layer. (Item 9) The carbon dioxide capture device according to item 8, wherein one support of the cell stack located on the upper side of a plurality of cell stacks and the other support of the cell stack located on the lower side are shared. [Explanation of Symbols]

[0130] 110 Electrochemical Cells 140-layer structure 150-cell stack 151, 152 A pair of supports 153 Columnar structure 154b Elastic body

Claims

1. CO ２ Contains CO ２ The CO2 is obtained from the contained gas through an electrochemical reaction. ２ A laminate (140) is formed by stacking a plurality of electrochemical cells (110) that perform adsorption and desorption under pressure in the cell stacking direction of the plurality of electrochemical cells, A pair of supports (151, 152) are arranged in one and the other direction of the cell stacking relative to the laminate, An elastic body (154b) is provided between the pair of supports and has a Young's modulus greater than that of the electrochemical cell, Includes, The aforementioned elastic body elastically deforms to apply a load to a plurality of electrochemical cells under pressure in the cell stacking direction, thereby enabling carbon dioxide recovery.

2. The carbon dioxide recovery apparatus according to claim 1, wherein the elastic body is electrically insulated in at least the portion that comes into contact with the electrochemical cell.

3. With the laminated body positioned between the pair of supports, it includes clamping portions (158, 159) that clamp and fix the outer edges (151b, 152b) of the pair of supports in a direction perpendicular to the cell stacking direction, The carbon dioxide recovery apparatus according to claim 1 or 2, wherein the elastic body is located in the central part (142) of the laminate in a direction perpendicular to the cell stacking direction.

4. The carbon dioxide recovery apparatus according to claim 1 or 2, wherein the elastic body is located on the outermost side of the laminate in the cell stacking direction.

5. The carbon dioxide recovery apparatus according to claim 1 or 2, wherein the elastic body is a disc spring or a leaf spring.

6. The carbon dioxide recovery apparatus according to claim 1 or 2, wherein the elastic body is made of a material including at least one of stainless steel, high-carbon steel, and nickel.

7. One of the pair of supports (151) has a surface (151a) facing the other of the pair of supports (152), It includes a plurality of columnar structures (153) that are fixed to one surface of the one support and are perpendicular to the one surface of the one support and extend in the cell stacking direction, The other support is fixed to the columnar structure on the side opposite to the first support, The carbon dioxide recovery apparatus according to claim 1 or 2, wherein the plurality of electrochemical cells are positioned by contacting at least two of the columnar structures located in different directions among the plane directions parallel to the plane perpendicular to the cell stacking direction.

8. One of the pair of supports (151) has a surface (151a) facing the other of the pair of supports (152), It includes a plurality of columnar structures (153) that are fixed to one surface of the one support and are perpendicular to the one surface of the one support and extend in the cell stacking direction, The other support is fixed to the columnar structure on the side opposite to the first support, If the laminate, the pair of supports, and the set of the plurality of columnar structures are defined as a cell stack (150), then the plurality of the cell stacks are stacked in the cell stacking direction, The carbon dioxide recovery apparatus according to claim 1 or 2, wherein the elastic body applies a load to the uppermost electrochemical cell of the laminate without being subjected to the load of one of the support bodies of the cell stack in the upper layer.

9. The carbon dioxide recovery apparatus according to claim 8, wherein one support of the cell stack located on the upper side of the plurality of cell stacks and the other support of the cell stack located on the lower side are made common.

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