Carbon dioxide recovery system

Abstract

To provide a carbon dioxide recovery system in which deterioration of an absorbent is suppressed.SOLUTION: The carbon dioxide recovery system 1 recovers carbon dioxide by heating the absorbing material 11 having absorbed carbon dioxide and desorbing the carbon dioxide from the absorbing material 11, and includes a housing part 20 for housing a carbon dioxide collecting module 10 having the absorbing material 11 in an internal space 23, a gas supply part 24 for supplying a replacement gas as a gas other than oxygen to the internal space 23, and a gas discharge part 4 for discharging the gas in the internal space 23.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a system for recovering carbon dioxide from air, and more particularly to a carbon dioxide recovery system that recovers carbon dioxide by desorbing it from an absorbent that has absorbed carbon dioxide in the air. [Background technology]

[0002] In recent years, technological developments have been made to capture and effectively utilize carbon dioxide, a typical greenhouse gas. In particular, there is a strong demand for reducing carbon dioxide emissions from thermal power plants, steel plants, chemical plants, and other plants that emit large amounts of carbon dioxide. On the other hand, from the perspective of reducing greenhouse gases, it is desirable to be able to capture carbon dioxide not only from thermal power plants and steel plants, but also from ordinary households and the like.

[0003] As a system for recovering carbon dioxide in such an ordinary home, a carbon dioxide recovery system has been disclosed in which carbon dioxide in the air is absorbed by a small module having an absorbent material, and multiple modules are housed in a heat collection device and heated to desorb and recover the carbon dioxide from the absorbent material (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication WO2023 / 210581 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a capture system such as that described in Patent Document 1, in which a small module is housed in a device and heated, when the heated absorbent releases carbon dioxide, depending on the type of absorbent, there is a risk that the absorbent may subsequently react with ambient oxygen and deteriorate. Absorbent materials that have reacted with oxygen have a reduced carbon dioxide absorption efficiency when reused, making it difficult to reuse the absorbent. In particular, when attempting to capture carbon dioxide from the air in an ordinary household, the capture efficiency is low compared to capturing carbon dioxide from exhaust gases at large plants due to the small size of the modules, and it is assumed that a certain amount of absorbent will be reused. Therefore, because absorbent deterioration and the resulting replacement directly lead to increased costs, a carbon dioxide capture system that can better suppress absorbent deterioration has been desired.

[0006] The present invention has been made in view of the above-mentioned problems, and aims to provide a carbon dioxide capture system in which deterioration of the absorbent material is suppressed. [Means for solving the problem]

[0007] The present invention is a carbon dioxide capture system that heats an absorbent material that has absorbed carbon dioxide, and captures the carbon dioxide by desorbing it from the absorbent material, and is characterized in that it comprises a storage section that stores a carbon dioxide capture module having the absorbent material in its internal space, a gas supply section that supplies a gas other than oxygen as a replacement gas to the internal space, and a gas discharge section that discharges the gas from the internal space, and by supplying the replacement gas to the internal space when carbon dioxide is desorbed, the carbon dioxide capture system reduces the oxygen partial pressure in the internal space.

[0008] That is, the carbon dioxide capture system of the present invention includes a storage unit that stores a carbon dioxide capture module having an absorbent in an internal space, and a gas supply unit that supplies a replacement gas as a gas other than oxygen to the internal space, and by supplying the replacement gas to the internal space, the oxygen partial pressure in the internal space is reduced. With this configuration, it is possible to suppress deterioration due to reaction with oxygen after the absorbent is heated and carbon dioxide is desorbed from the absorbent.

[0009] Furthermore, the carbon dioxide capture system of the present invention may be configured such that the replacement gas is water vapor. This configuration prevents the replacement gas from having harmful effects on the human body, making the carbon dioxide capture system easier to handle. Furthermore, water vapor absorbs heat from the surrounding area when it evaporates from water, providing a high heat retention effect, particularly in situations where the storage unit is continuously heated. Therefore, the internal space of the storage unit can be maintained at a constant temperature, preventing the absorbent from evaporating and thermally decomposing due to excessive heating.

[0010] Furthermore, the water vapor supplied to the internal space of the storage unit reduces the partial pressure of oxygen in the internal space, and at the same time, the partial pressure of carbon dioxide can be reduced. The carbon dioxide desorption reaction of the absorbent is promoted more as the partial pressure of carbon dioxide around the absorbent is lower. Therefore, the carbon dioxide desorption efficiency (recovery efficiency) can be improved.

[0011] Furthermore, the desorbed carbon dioxide will be mixed with the water vapor, but by cooling the discharged water vapor, it can be easily separated into liquid water (condensed water) and gaseous carbon dioxide, allowing for more efficient recovery of carbon dioxide.

[0012] The carbon dioxide capture system of the present invention may also be configured such that the absorbent is an amine-based compound. With this configuration, even a relatively small module can absorb a sufficient amount of carbon dioxide. Furthermore, the carbon dioxide desorption temperature can be set to approximately 120°C, which is relatively low compared to other absorbents.

[0013] Furthermore, the carbon dioxide capture system of the present invention may be configured such that the gas supply unit is formed of a holder that holds water, the holder is housed in the internal space of the housing unit, and water vapor produced by evaporation of the water held by the holder is supplied to the internal space as the temperature of the internal space is increased. With such a configuration, there is no need to provide a separate gas supply device, and the carbon dioxide capture system can be simplified, made smaller, and made more energy-efficient. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a carbon dioxide capture system in which deterioration of the absorbent material is suppressed. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing an outline of a carbon dioxide capture system according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the internal configuration of a storage unit according to an embodiment of the present invention. [Figure 3] 1 is a perspective view of a carbon dioxide capture module according to an embodiment of the present invention; [Figure 4] FIG. 1 is a longitudinal cross-sectional view of a carbon dioxide capture module according to an embodiment of the present invention. [Figure 5] FIG. 1 is a schematic diagram showing an outline of a carbon dioxide capture system according to another embodiment of the present invention. [Figure 6] FIG. 10 is a schematic view showing the internal configuration of a storage unit according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0017] FIG. 1 is a schematic diagram showing an outline of a carbon dioxide capture system 1 according to one embodiment of the present invention. The carbon dioxide capture system 1 of this embodiment is a system that desorbs and captures carbon dioxide from a carbon dioxide capture module 10 that has absorbed carbon dioxide, and is equipped with a desorption section 2 that desorbs carbon dioxide from the carbon dioxide capture module 10, and a capture section 3 that captures the carbon dioxide desorbed from the carbon dioxide capture module 10.

[0018] The desorption unit 2 includes a storage unit 20 that stores the carbon dioxide capture module 10. The storage unit 20 and the capture unit 3 are connected by a tubular gas discharge unit 4. The gas discharge unit 4 can be, for example, a hollow resin tube. The gas discharge unit 4 is also provided with a check valve 41 that prevents gas from moving from the capture unit 3 to the storage unit 20.

[0019] The recovery unit 3 is provided with a pump and the like that introduces the carbon dioxide desorbed from the carbon dioxide capture module 10 into the storage unit 20.

[0020] FIG. 2 is a schematic diagram showing the internal configuration of the container 20 according to one embodiment of the present invention. In this specification, the up and down directions in FIG. 2 will be referred to as the respective up and down directions.

[0021] The storage unit 20 in this embodiment has a storage body 20A with a generally cylindrical appearance and a lid member 22 attached to the storage body 20A. The storage body 20A has a bottomed recess 21 with an opening at the top. The top opening of the recess 21 is closed with the lid member 22, thereby forming an internal space 23. The storage body 20A is made of a metal with good thermal conductivity, such as copper, brass, stainless steel, or aluminum.

[0022] A gas supply unit 24 is provided in the internal space 23. In this embodiment, the gas supply unit 24 is made of a sponge impregnated with (holding) water, and is provided along the inner circumferential surface of the recess 21. The medium (holding body) that holds water in the gas supply unit 24 is not limited to a sponge, and any known porous body can be used. As the porous body, for example, one selected from a sponge, porous ceramic, and a membrane filter can be used.

[0023] Furthermore, a plurality of carbon dioxide capture modules 10 are stacked and housed in the internal space 23. In this case, it is preferable that a gas supply unit 24 is arranged so as to surround the outer periphery of the housed carbon dioxide capture modules 10.

[0024] Lid member 22 is configured to be detachable from housing body 20A, and when attached to housing body 20A, it closes the upper opening of recess 21 and forms internal space 23. When lid member 22 is removed from housing body 20A, the upper opening of recess 21 can be opened. A gas discharge section 4 is provided to penetrate lid member 22 so as to communicate between collection section 3 and internal space 23 when lid member 22 is attached to housing body 20A. Lid member 22 can be in a known form, such as a rubber cap or a plastic cap formed to be able to fit into the upper opening of recess 21.

[0025] FIG. 3 is a perspective view of a carbon dioxide capture module 10 according to one embodiment of the present invention, and FIG. 4 is a vertical cross-sectional view of the carbon dioxide capture module 10 according to one embodiment of the present invention. The carbon dioxide capture module 10 in this embodiment has a generally cylindrical shape. The carbon dioxide capture module 10 includes an absorption unit 11 that absorbs carbon dioxide, a filter unit 12 that is disposed opposite the outer peripheral side surface of the absorption unit 11, and fixing units 13 that sandwich and fix the absorption unit 11 and the filter unit 12 from the top and bottom. The size of the carbon dioxide capture module 10 is such that it can be placed in at least part of the interior of an average home.

[0026] The absorption unit 11 in this embodiment has a cylindrical shape and is disposed inside the carbon dioxide capture module 10. The absorption unit 11 includes an absorbent material that chemically reacts with carbon dioxide to absorb it and releases (desorbs) the absorbed carbon dioxide at a predetermined temperature or higher. An amine, for example, can be used as such an absorbent material. The absorption unit 11 is preferably in a solid or liquid phase. Examples of amines that can be used as the absorbent include low-molecular-weight amines such as monoethanolamine, diethanolamine, triethanolamine, 2-amino-2-methyl-1-propanol, 2-isopropylaminoethanol, 2-(methylamino)ethanol, 2-(ethylamino)ethanol, N-methyldiethanolamine, ethylenediamine, hexamethylenediamine, diethylenetriamine, piperazine, o-xylenediamine, m-xylenediamine, p-xylenediamine, and isophoronediamine, or a mixture of two or more thereof. Alternatively, a polymeric amine such as polyethyleneimine can be used. It is preferable to use an amine as the absorbent, and more preferably a polymeric amine.

[0027] When the absorption section 11 is a solid phase, for example, an absorbent-containing porous body obtained by incorporating (attaching) an absorbent to a porous body such as a sponge, porous ceramic, or porous resin can be used as the absorption section 11. Such an absorbent-containing porous body can be produced, for example, by dissolving an absorbent in an organic solvent to prepare an absorption liquid, and then immersing the porous body in the absorption liquid for a predetermined period of time. In other words, the solid phase described in this example does not only refer to a case where the solid (e.g., a porous body) is composed of only solids, but also includes a state in which the solid (e.g., a porous body) absorbs and contains a liquid, or a state in which the surface is coated with a liquid.

[0028] When the absorbing part 11 is in a liquid phase, for example, the absorbing liquid may be an absorbing material dissolved in a hydrophobic organic solvent. The organic solvent that dissolves the absorbing material may be, for example, one selected from xylene, toluene, and butyl acetate.

[0029] The filter section 12 has the property of being permeable to at least carbon dioxide in the air but impermeable to the absorbent material. The filter section 12 is formed in a cylindrical shape and is arranged so as to cover the outer peripheral side surface of the absorption section 11. Furthermore, the filter section 12 forms the outer peripheral side surface of the carbon dioxide capture module 10. The filter section 12 in this embodiment is arranged opposite the absorption section 11 and is composed of a film-like absorbent filter 12a that is impermeable to the absorbent material, and a holder 12b that holds the absorbent filter 12a with the absorbent filter 12a attached to its inner peripheral surface.

[0030] The absorbent filter 12a has the property of being permeable to at least carbon dioxide in the air but impermeable to the absorbent contained in the absorption section 11. Furthermore, when the absorption section 11 is in a liquid phase, it has the property of being impermeable to the solution itself that constitutes the absorption section 11. As the absorbent filter 12a having such properties, a film-like or sheet-like porous body (porous film or porous sheet) can be used. More specifically, for example, a porous film or porous sheet made of a porous resin such as polyolefin or polytetrafluoroethylene (PTFE) in the form of a film or sheet can be used.

[0031] Also, a zeolite membrane can be used as the whole or part of the absorbent filter 12a. The structure of zeolite that can be used as the zeolite membrane is not particularly limited, and zeolites having known structures such as LTA type and CHA type can be used. The zeolite membrane may be formed on the absorbent filter 12a itself (deposited on the holding part 12b) or may be formed by superimposing it on an absorbent filter 12a made of another material (deposited on another absorbent filter 12a).

[0032] The retaining portion 12b has a cylindrical shape, and a film-like absorbent filter 12a is attached (provided) to cover the entire inner circumferential surface thereof. The retaining portion 12b has the property of transmitting at least carbon dioxide in the air. The retaining portion 12b is hard and thick enough to prevent the attached absorbent filter 12a from deforming. For example, porous ceramic made of aluminum oxide or a metal mesh can be used as the retaining portion 12b. The retaining portion 12b is formed as the outer circumferential side surface of the carbon dioxide capture module 10, and is arranged and formed so that the air (outside air, atmosphere) surrounding the carbon dioxide capture module 10 comes into contact with the outer circumferential side surface of the retaining portion 12b.

[0033] The fixing units 13 are provided on the top and bottom surfaces of the carbon dioxide capture module 10, respectively. They sandwich and fix the absorption unit 11 and the filter unit 12 from the top and bottom surfaces. They also serve to prevent the top and bottom surfaces of the absorption unit 11 from coming into contact with air and to prevent the liquids contained in the absorption unit 11 and the gas generated in the absorption unit 11 from leaking out of the carbon dioxide capture module 10 from the top and bottom surfaces. The fixing units 13 are formed of a corrosion-resistant material, such as an alkali-resistant resin material or metal material. Examples of such resin materials include polyethylene, polypropylene, nylon, polytetrafluoroethylene, tetrafluoroethylene, phenolic resin, and epoxy resin. Furthermore, it is preferable that the metal material be magnetic in addition to being alkali-resistant. Examples of such metal materials include ferritic stainless steel such as SUS430 and martensitic stainless steel such as SUS410.

[0034] Therefore, the absorption unit 11 is stored inside the carbon dioxide capture module 10, which has as its exterior the filter unit 12 and the fixing unit 13. Furthermore, the absorption unit 11 does not come into direct contact with the air surrounding the carbon dioxide capture module 10, but comes into contact only with gas that has passed through the filter unit 12. Furthermore, the filter unit 12 prevents the absorbent material contained in the absorption unit 11 from leaking outside the carbon dioxide capture module 10.

[0035] The carbon dioxide capture module 10 having such a configuration can be suitably used by being placed in a room of an ordinary home, etc. The operation of the carbon dioxide capture module 10 of the present invention when placed in a room of an ordinary home will be described below.

[0036] The space surrounding a carbon dioxide capture module 10 placed in a room in an ordinary home is typically filled with air containing nitrogen, oxygen, and a small amount of carbon dioxide. This air containing these elements is blown toward the carbon dioxide capture module 10 by wind or the like. The blown air passes through the filter unit 12 and comes into contact with the absorption unit 11. Note that in this embodiment, the air is blown into the carbon dioxide capture module 10 by wind or the like, but the method and environment in which the air is blown into the carbon dioxide capture module 10 are not particularly limited. For example, the carbon dioxide capture module 10 may be placed in an environment where air circulates easily, such as near a window or at a front door, or air may be forcibly blown in the direction of the carbon dioxide capture module 10 using a fan or the like. Alternatively, a small amount of carbon dioxide contained in the air can be captured even in a windless state without wind.

[0037] The absorbent material contained in the absorption section 11 comes into contact with carbon dioxide contained in the air, and the absorbent material and carbon dioxide chemically react with each other, thereby absorbing the carbon dioxide in the air.

[0038] In this way, the carbon dioxide capture module 10 that has absorbed carbon dioxide in a room of an ordinary home for a predetermined period of time has the absorbed carbon dioxide desorbed by the carbon dioxide capture system 1 of the present invention. Below, we will explain the operation of the carbon dioxide capture system 1 of the present invention to desorb and capture carbon dioxide from the carbon dioxide capture module 10. Note that this embodiment shows an example in which polyethyleneimine, a polymeric amine, is used as the absorbent.

[0039] The carbon dioxide capture modules 10 that have absorbed carbon dioxide are subjected to a process of desorbing carbon dioxide from the absorbent (absorption section 11) by the desorption section 2 of the carbon dioxide capture system 1. More specifically, a plurality of carbon dioxide capture modules 10 that have absorbed carbon dioxide are housed in the internal space 23 of the housing section 20 (housing body 20A), and then the housing body 20A is heated, causing a reaction in which carbon dioxide is desorbed from the absorbent. The desorbed carbon dioxide then moves from the internal space 23 to the capture section 3 via the gas discharge section 4 and is captured.

[0040] The procedure for storing the carbon dioxide capture modules 10 in the internal space 23 of the storage body 20A can be, for example, to store multiple carbon dioxide capture modules 10 stacked in a recess 21 with the top open, and then close the opening of the recess 21 with a lid member 22.

[0041] Furthermore, the gas supply unit 24 may be installed in the recess 21 before the carbon dioxide capture module 10 is accommodated. In this embodiment, a sponge sufficiently impregnated with (holding) water is installed as the gas supply unit 24 along the inner peripheral surface of the recess 21, and the carbon dioxide capture module 10 is accommodated in the recess 21 so that its outer peripheral side surface is surrounded by the sponge. At this time, within the recess 21 (internal space 23), the outer peripheral side surface of the carbon dioxide capture module 10 and the gas supply unit 24 are spaced apart on the entire outer peripheral side surface (see FIG. 2).

[0042] Thereafter, the accommodation body 20A (accommodation section 20) is heated in the internal space 23 to at least a temperature at which the absorbent desorbs carbon dioxide. The method of heating the accommodation body 20A can be, for example, a method of heating the accommodation body 20A by utilizing solar heat collection. In such a case, the desorption section 2 can be configured to have a heat collection device that collects solar heat and supplies it to the accommodation body 20A. Furthermore, in order to more efficiently collect solar heat, the accommodation body 20A (accommodation section 20) may be erected at an angle nearly perpendicular to the direction of solar light incidence. Even in such a case, it is preferable that the outer peripheral side surface of the carbon dioxide capture module 10 is separated from the gas supply unit 24 on the entire outer peripheral side surface within the recess 21 (internal space 23). Furthermore, to maintain this state, the accommodation body 20A may have a support unit (not shown) that supports the carbon dioxide capture module 10 accommodated in the recess 21. It is preferable that at least a portion of the outer peripheral side of the carbon dioxide capture module 10 is separated from the gas supply unit 24, more preferably at least in the heating direction (the direction of incident sunlight in this embodiment) from the gas supply unit 24, and even more preferably at all around from the gas supply unit 24.

[0043] Furthermore, the method for heating the storage body 20A is not limited to sunlight, and may be a method using a heating device such as a heater. In such a case, the desorption unit 2 may be configured to have a heating device such as a heater that heats the storage body 20A. Furthermore, the desorption unit 2 may be configured to have both a heat collection device and a heating device. Note that the carbon dioxide capture system 1 may also include a temperature measurement unit (not shown) that measures the temperature of the internal space 23, and a control unit (not shown) that controls the heat collection device and the heating device by referring to temperature information of the internal space 23 acquired by the temperature measurement unit. The control unit may be configured, for example, by a computer having an input unit, a display unit, and a communication unit.

[0044] As housing body 20A is heated, the water held in the sponge begins to evaporate, and water vapor (replacement gas) begins to be supplied to internal space 23. At this time, the air present in internal space 23 is pushed out by the supplied water vapor and discharged to gas discharge section 4. That is, the supply of water vapor (replacement gas) from gas supply section 24 (sponge) reduces the oxygen partial pressure and carbon dioxide partial pressure in internal space 23.

[0045] As the container 20A is further heated, carbon dioxide is desorbed and released from the amine absorbent. Furthermore, the supply of water vapor from the gas supply unit 24 continues. Therefore, the carbon dioxide desorbed and released from the amine is pushed out by the continuously supplied water vapor and discharged to the gas discharge unit 4. Therefore, the continuously supplied water vapor keeps the carbon dioxide partial pressure in the internal space 23 constantly low. The carbon dioxide desorption reaction of the amine proceeds faster (more efficiently) the lower the ambient carbon dioxide partial pressure is, so in this embodiment, carbon dioxide is desorbed from the amine with high efficiency. Furthermore, when water evaporates into water vapor, it absorbs heat from the surroundings, so the internal space 23 is maintained at a temperature of around 100°C, at which water evaporates.

[0046] After the internal space 23 is heated and maintained for a predetermined time, the temperature of the internal space 23 is lowered. The temperature of the internal space 23 may be lowered by natural temperature lowering or by cooling the housing body 20A.

[0047] Thereafter, the lid member 22 is removed from the housing 20A to open the top opening of the recess 21, and the carbon dioxide capture module 10 and the gas supply unit 24 are removed from the recess 21. At this time, if the fixing portion 13 constituting the carbon dioxide capture module 10 is formed of a magnetic material, the multiple carbon dioxide capture modules 10 can be more easily removed from the internal space 23 by using a rod (magnetic rod) with a magnet on one end. That is, the rod (magnetic rod) with a magnet on one end is inserted into the recess 21 from one end, the carbon dioxide capture module 10 is attracted by the magnet, and the other end of the magnetic rod protruding from the opening of the recess 21 is pulled up, thereby removing the carbon dioxide capture module 10 from the recess 21. With this configuration, the carbon dioxide capture module 10 can be removed without tilting or turning the housing 20A over, making the carbon dioxide capture system 1 easier to handle. Note that the magnet used is preferably an electromagnet that can be electrically switched on and off. With this configuration, the carbon dioxide capture module 10 can be magnetized when it is removed from or stored in the recess 21, and the magnetization can be deactivated when removal and storage are complete, making it easy to remove and store the carbon dioxide capture module 10.

[0048] The removed carbon dioxide capture module 10 can absorb carbon dioxide again because the carbon dioxide has been desorbed from the absorbent (amine). Therefore, the carbon dioxide capture module 10 can be placed again in an ordinary home or the like and absorb carbon dioxide in the air.

[0049] As described above, in this embodiment, the amine after carbon dioxide absorption in the carbon dioxide capture module 10 is regenerated into a state capable of absorbing carbon dioxide by the carbon dioxide capture system 1 of the present invention, and a certain amount of amine can be repeatedly used as a carbon dioxide absorbent.

[0050] The recovery unit 3 may include a storage unit (not shown) that stores the recovered carbon dioxide, and a separation unit (not shown) that separates the carbon dioxide contained in the water vapor discharged from the gas discharge unit 4. The recovered carbon dioxide can be used, for example, in artificial photosynthesis, which synthesizes chemicals using solar energy.

[0051] With the above configuration, it is possible to provide a carbon dioxide capture system that suppresses deterioration of the absorbent material. The carbon dioxide capture system 1 of the present invention is configured to include a storage unit 20 that stores a carbon dioxide capture module 10 having an absorbent in an internal space 23, and a gas supply unit 24 that supplies a replacement gas as a gas other than oxygen to the internal space 23, and to reduce the oxygen partial pressure in the internal space 23 by supplying the replacement gas to the internal space 23. With this configuration, it is possible to prevent the absorbent from reacting with oxygen and desorbing carbon dioxide after it is heated.

[0052] Furthermore, the carbon dioxide capture system 1 of the present invention is configured to use water vapor as the replacement gas. This configuration prevents the replacement gas from having harmful effects on the human body, making the carbon dioxide capture system 1 easier to handle. Furthermore, water vapor has the effect of absorbing heat from the surrounding area when evaporating from water, and therefore has a high heat retention effect, particularly in situations where the storage unit 20 is continuously heated, such as when heated using sunlight as a heat source. Therefore, the internal space 23 of the storage unit 20 can be maintained at a constant temperature, more specifically, around 100°C, and evaporation and thermal decomposition of the absorbent due to excessive heating can be prevented.

[0053] Furthermore, the water vapor supplied to the internal space 23 of the storage unit 20 reduces the partial pressure of oxygen in the internal space 23, and at the same time, the partial pressure of carbon dioxide can also be reduced. The carbon dioxide desorption reaction of the absorbent is promoted more as the partial pressure of carbon dioxide around the absorbent is lower. Therefore, the carbon dioxide desorption efficiency (recovery efficiency) can be improved.

[0054] Furthermore, the desorbed carbon dioxide will be mixed with the water vapor, but by cooling the discharged water vapor, it can be easily separated into liquid water and gaseous carbon dioxide, allowing for more efficient recovery of carbon dioxide.

[0055] Furthermore, the carbon dioxide capture system of the present invention is configured to use an amine compound as the absorbent. This configuration allows even a relatively small module such as the carbon dioxide capture module 10 of the present invention to absorb a sufficient amount of carbon dioxide. Note that, depending on the type of amine compound, including polyethyleneimine exemplified in this embodiment, reaction with oxygen is promoted under temperature conditions in which carbon dioxide desorbs from the amine compound. When the amine compound reacts with oxygen, the reaction rate with carbon dioxide significantly decreases, making it difficult to repeatedly use the carbon dioxide capture module 10. In such cases, the amine compound that has reacted with oxygen must be replaced with an amine compound that has not reacted with oxygen. However, amine compounds are relatively expensive among carbon dioxide absorbents, which increases operating costs. However, with the carbon dioxide capture system 1 of the present invention, the oxygen partial pressure in the internal space 23 housing the carbon dioxide capture module 10 is reduced, thereby preventing the amine compound from reacting with oxygen and deteriorating. In other words, high carbon dioxide absorption efficiency by the amine compound and low cost due to reusability can be achieved.

[0056] Furthermore, in the carbon dioxide capture system 1 of the present invention, the gas supply unit 24 is composed of a holder that holds water, the holder is housed in the internal space 23 of the housing unit 20, and when the temperature of the internal space 23 is raised, the water held by the holder evaporates and water vapor is supplied to the internal space 23. With this configuration, there is no need to provide a separate device for supplying replacement gas to the internal space 23, and the carbon dioxide capture system 1 can be simplified, made smaller, and made more energy-efficient.

[0057] Furthermore, in the carbon dioxide capture system 1 of the present invention, the fixing portion 13 constituting the carbon dioxide capture module 10 is formed of a magnetic material. With this configuration, by using a bar with a magnet on one end (a magnetic bar), it is possible to more easily remove the multiple carbon dioxide capture modules 10 from the internal space 23. In other words, the carbon dioxide capture module 10 can be removed without tilting or turning over the housing 20A, making the carbon dioxide capture system 1 easier to handle.

[0058] Furthermore, in the carbon dioxide capture system 1 of the present invention, it is preferable that at least a portion of the outer peripheral side surface of the carbon dioxide capture module 10 is separated from the gas supply unit 24, more preferably separated from the gas supply unit 24 at least in the heating direction, and even more preferably separated from the gas supply unit 24 over the entire periphery. With this configuration, gas from the gas supply unit 24 is reliably supplied to the periphery of the carbon dioxide capture module 10, and deterioration of the absorbent due to reaction with oxygen can be reliably suppressed.

[0059] Furthermore, the carbon dioxide capture system 1 of the present invention has a carbon dioxide capture module 10 that is small enough to be placed in at least part of a typical home. This configuration enables the carbon dioxide capture system 1 of the present invention to absorb carbon dioxide from the air in a typical home or on a room-by-room basis. Furthermore, when such a small module is used to capture carbon dioxide, the capture efficiency is low because only a very small amount of carbon dioxide is contained in the air, and deterioration of the absorbent material prevents the absorbent material from being reused, significantly adversely affecting cost-effectiveness. However, the carbon dioxide capture system 1 of the present invention can suppress deterioration of the absorbent material, making it possible to achieve a system with excellent cost-effectiveness even when the carbon dioxide capture module 10 is small.

[0060] The present invention is not limited to the configurations of the above-described embodiments, and many other embodiments can be obtained. For example, in this embodiment, the gas supply unit 24 is configured as a holder that holds water and supplies water vapor as the replacement gas, but this configuration is not limited to this. That is, the replacement gas can be selected from gases other than oxygen, and preferably other than carbon dioxide. Such a replacement gas can be, for example, a vaporized organic solvent. When the replacement gas is a vaporized organic solvent, the gas supply unit 24 can be configured as a holder that holds the organic solvent. As the organic solvent, an organic solvent that vaporizes at a temperature lower than the temperature at which the absorbent desorbs carbon dioxide can be used. When the absorbent is an amine, for example, toluene or xylene can be used as the organic solvent.

[0061] FIG. 5 is a schematic diagram showing an outline of a carbon dioxide capture system 100 according to another embodiment of the present invention. The carbon dioxide capture system 100 differs from the above-described embodiment in that the gas supply unit 5 is provided outside the accommodation unit 20, and the gas supply unit 5 and the accommodation unit 20 (the internal space 23 in the above-described embodiment) are connected by a gas supply path 50. The gas supply unit 5 can be a cylinder filled with a replacement gas or a generator that generates a replacement gas. For example, when the replacement gas is nitrogen, the gas supply unit 5 can be a nitrogen cylinder.

[0062] FIG. 6 is a schematic diagram showing the internal configuration of a storage section 200 according to still another embodiment of the present invention. Furthermore, in this embodiment, the gas supply unit 24 is configured to be provided along the inner circumferential surface of the recess 21, but this configuration is not limited thereto. For example, as shown in FIG. 5, the gas supply unit 240 may be configured to be located on the inner bottom surface of the recess 21 and below the carbon dioxide capture module 10. The gas supply unit 240 shown in FIG. 5 has a configuration in which a moisture absorbent 241 (silica balls) is housed in a box 242 formed of a metal mesh. With this configuration, while the carbon dioxide capture module 10 is absorbing carbon dioxide in an ordinary home or the like, the gas supply unit 240 is exposed to the outside air to absorb moisture in the air, and when carbon dioxide is desorbed from the absorbent, the gas supply unit 240 can be suitably used as the gas supply unit 240 that supplies water vapor to the internal space 23. Furthermore, when removing the carbon dioxide capture module 10 from the recess 21, the gas supply unit 240 can also be removed from the recess 21 by using a rod with a magnet on one end (a magnetic rod).

[0063] The embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention should not be interpreted solely by the above-described embodiments, but should be defined by the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included. [Industrial Applicability]

[0064] The carbon dioxide recovery system of the present invention can be used as a system for recovering carbon dioxide in an ordinary home or the like. [Explanation of symbols]

[0065] 1...Carbon dioxide capture system 10...Carbon dioxide capture module 11...Absorption section 2...Detachment part 20...Storage section 20A…Containment unit 21...recess 22...Cover member 23...Interior space 24...Gas supply section 4...Gas exhaust section 41...Check valve

Claims

1. A carbon dioxide capture system that heats an absorbent that has absorbed carbon dioxide, and desorbs and captures the carbon dioxide from the absorbent, a housing section that houses the carbon dioxide capture module having the absorbent material in its internal space; a gas supply unit that supplies a gas other than oxygen as a replacement gas to the internal space; a gas exhaust section that exhausts gas from the internal space, By supplying the replacement gas to the internal space when carbon dioxide is desorbed, the oxygen partial pressure in the internal space is reduced. Carbon dioxide capture system.

2. The replacement gas is water vapor. The carbon dioxide capture system of claim 1 .

3. The absorbent is an amine-based compound.

3. The carbon dioxide recovery system according to claim 1 or 2.

4. the gas supply unit is composed of a holder that holds water, the holder is accommodated in the internal space of the accommodation portion, When the temperature of the internal space is increased, the water held by the holder is evaporated and water vapor is supplied to the internal space.

3. The carbon dioxide recovery system according to claim 1 or 2.

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