Carbon dioxide recovery method and carbon dioxide recovery system

Abstract

Provided are: a method for recovering completely absorbed carbon dioxide, which is capable of removing completely absorbed carbon dioxide from an absorbing material with less energy; and a system suitable for use in the method. The method for recovering absorbed carbon dioxide includes: a step (a) for irradiating an absorption liquid that has absorbed carbon dioxide with light; a step (b) for supplying heat to the absorption liquid; and a step (c) for collecting the carbon dioxide separated from the absorption liquid through the steps (a) and (b).

Description

Technical Field

[0001] The present invention relates to a method for removing and recovering carbon dioxide in an absorbed state (completed absorption) by an absorbing liquid and a system suitable for utilizing the method. In addition, the present invention relates to a method for recovering carbon dioxide via an absorbent showing carbon dioxide absorption and a system suitable for utilizing the method. Background Art

[0002] In recent years, in order to reduce the concentration of carbon dioxide in the atmosphere, research has been conducted on technologies for directly absorbing carbon dioxide in the atmosphere or separating and recovering carbon dioxide contained in exhaust gas from the combustion of fossil fuels.

[0003] In the recovery of carbon dioxide, a method has been proposed in which carbon dioxide is absorbed by an absorbent and the absorbed carbon dioxide is separated from the absorbent. For example, the following patent document 1 describes a method in which carbon dioxide is separated from combustion exhaust gas using a solution containing amine as an absorbent, and then the solution is heated to separate the carbon dioxide and recover it.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 5-245339 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In this way, in order to separate the absorbed carbon dioxide from the carbon dioxide absorbing material, it is considered that energy input such as heating is required. If the energy used for the separation is large, the cost of carbon dioxide recovery becomes large. After carbon dioxide is absorbed by the absorbing material, if the carbon dioxide absorbed by the absorbing material cannot be separated with low energy, it becomes difficult to comprehensively reduce the emission of carbon dioxide. For example, if the separation of carbon dioxide consumes a huge amount of electricity, carbon dioxide is released in order to generate the electricity. In addition, there may also be problems with the operation of the absorbing material after absorbing carbon dioxide.

[0009] On the other hand, as mentioned above, when high energy is required to separate carbon dioxide from the absorbing material that has completed the absorption of carbon dioxide, the running cost of the operation of the system is worrying. This is an obstacle to the introduction and popularization of the system for recovering carbon dioxide. At present, the problem of global warming is regarded as one of the problems that should be solved in the world. Reducing the emission of carbon dioxide, which is regarded as one of the main causes of global warming, and then reducing the concentration of carbon dioxide in the atmosphere can be said to be an urgent issue.

[0010] In view of the above, it is considered important to realize a system that can desorb / recover carbon dioxide from an absorbent at low cost and low energy after carbon dioxide is absorbed by an absorbent in order to promote the trend of reducing the carbon dioxide concentration in the atmosphere.

[0011] In view of the above situation, an object of the present invention is to provide a method and system for recovering carbon dioxide that can separate absorbed carbon dioxide from an absorbent with less energy.

[0012] Means for solving problems

[0013] The method for recovering carbon dioxide of the present invention is characterized in that it comprises the following steps:

[0014] (a) irradiating the absorbing liquid that has absorbed carbon dioxide with light;

[0015] (b) a step of supplying heat to the absorbent;

[0016] and a step (c) of recovering the carbon dioxide desorbed from the absorbent through the steps (a) and (b).

[0017] The details are described below, but the inventors have conducted in-depth research and found that by irradiating light to the absorbing liquid that has absorbed carbon dioxide, the desorption of carbon dioxide from the absorbing liquid that has been absorbed is increased. That is, by irradiating light while supplying heat to the absorbing liquid, the applied heat energy can be reduced compared to the case of heating only, and the absorbed carbon dioxide can be desorbed. In addition, by reducing the applied heat energy, the desorption of carbon dioxide can be achieved at a temperature lower than the temperature of the absorbing liquid that was previously considered to be required for the desorption of carbon dioxide. Furthermore, if the heat energy applied to the absorbing liquid is set to the same as before, more carbon dioxide can be desorbed by irradiating light.

[0018] In order to remove the absorbed carbon dioxide, when heat is supplied to increase the temperature of the absorbing liquid, it is necessary to heat the entire solution containing the carbon dioxide absorbing material. On the other hand, when irradiating the absorbing liquid with light, a wavelength that is easily absorbed by the carbon dioxide absorbing material can be selected. That is, if light irradiation is utilized, energy can be selectively given to the carbon dioxide absorbing material. Therefore, by utilizing heat and light irradiation to supply energy for removing carbon dioxide, the absorbed carbon dioxide can be removed from the absorbing liquid with less energy than when only heating is used.

[0019] The term "recovery" in this specification refers to the transfer of carbon dioxide separated from the absorbent or absorber from the area where the absorbent or absorber is arranged to another area. For example, carbon dioxide can be stored in a storage tank such as a gas cylinder, or can be sent to a carbon dioxide utilization facility via a pipe. Examples of the above-mentioned utilization facilities include plant factories, etc.

[0020] The step (a) is a step of irradiating the absorbing liquid with the light from a light source.

[0021] The step (b) may be a step of supplying the heat generated by the light source to the absorbing liquid.

[0022] Since the light source generates heat when emitting light, when irradiating the absorbent with light, if the heat generated by the light source is supplied to the absorbent, energy can be used effectively. Therefore, the absorbed carbon dioxide can be removed from the absorbent with even less energy.

[0023] The above step (a) and the above step (b) may be performed simultaneously.

[0024] Furthermore, the step (a) includes the step of irradiating the absorbing liquid with the light from a light source.

[0025] In a scheme capable of irradiating sunlight, the step (b) may also include a step in which a solar heat collecting member is arranged directly or in contact with a reaction tank located inside the absorbent liquid, converts the sunlight into the heat, and supplies the heat to the absorbent liquid.

[0026] Although the details are described below, by utilizing the energy of sunlight and supplying heat to the absorbing liquid, it is possible to desorb the absorbed carbon dioxide from the absorbing liquid with less energy.

[0027] The absorbing liquid may contain a carbon dioxide absorber formed of an alkaline material and a solvent.

[0028] The carbon dioxide absorber may also be an amine material. An amine material refers to an amine compound having one or more primary or secondary amino groups. The amine compound is not particularly limited as long as it has carbon dioxide absorption performance, and may be used alone or as a mixture.

[0029] Examples of the amine compound that may be contained in the amine-based material include primary amines such as monoethanolamine, 2-amino-2-methyl-1-propanol, and phenylethylamine; secondary amines such as diethanolamine, 2-methylaminoethanol, and 2-ethylaminoethanol; diamines such as ethylenediamine, N,N-dimethylethylenediamine, o-xylylenediamine, m-xylylenediamine, and p-xylylenediamine; triamines such as diethylenetriamine; and benzylamines such as benzylamine, p-methoxybenzylamine, and p-trifluoromethylbenzylamine.

[0030] The carbon dioxide absorbing liquid can be prepared by dispersing the carbon dioxide absorbing material in a solvent such as water or dimethyl sulfoxide (DMSO). In addition, alcohols such as ethanol can also be used as solvents. These solvents can also be combined in multiple forms.

[0031] Next, take the amine material (R 1 R 2 Taking the aqueous solution of NH) as an example, the absorption and desorption of carbon dioxide are described. 1 represents an alkyl group, a cycloalkyl group, an aryl group or a monovalent heterocyclic group. 2 represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a monovalent heterocyclic group. These functional groups may have a substituent.

[0032] As the reaction of amine-based materials absorbing carbon dioxide, there are mainly the following formulas (1) to (3).

[0033] R 1 R 2 NH + CO2 + H2O → R 1 R 2 NH2 + + HCO3 - (1)

[0034] 2(R 1 R 2 NH)aq + CO2 → R 1 R 2 NH2 + + R 1 R 2 NCOO - (2)

[0035] R 1 R 2 NH+ CO2→ R 1 R 2 NCOOH (3)

[0036] Furthermore, when the solvent is water, it is assumed that hydroxide ions (OH - ), so the absorption reaction of the following formula (4) is also assumed.

[0037] CO2+ OH - → HCO3 - (4)

[0038] It should be noted that, although not limited to the above-mentioned formula (4), when the solution absorbs carbon dioxide, the area in which the gas phase containing carbon dioxide contacts the liquid phase of the solution (also referred to as "gas-liquid contact") is preferably large. If the area of ​​gas-liquid contact is large, then, for example, in formula (4), the hydroxide ions near the surface of the liquid phase become easy to contribute to the reaction, which is suitable. In addition, from the viewpoint of increasing hydroxide ions, the solution is preferably a strong base. Here, the so-called "solution is a strong base" refers to that the pH of the solution is more than 10.

[0039] That is, carbon dioxide is present in the absorption liquid as bicarbonate ions (HCO3 - ), carbamate ion (R 1 R 2 NCOO - ) or carbamic acid (R 1 R 2 NCOOH) and they exist in a mixed state.

[0040] By supplying energy to the absorbing liquid that has absorbed carbon dioxide by heat supply or light irradiation, the reverse reactions of equations (1) to (4) are induced, and the absorbed carbon dioxide can be released.

[0041] The absorption and desorption of carbon dioxide has been described using amine-based materials as an example. On the other hand, other carbon dioxide absorbers include, for example, imines containing amines that exhibit basicity, oxides containing alkali metals, and oxides containing niobium or tantalum.

[0042] The same discussion as above can be made for any carbon dioxide absorber that absorbs carbon dioxide and then causes a desorption reaction of carbon dioxide by absorbing light. That is, the carbon dioxide absorber is not limited to an amine-based material.

[0043] The carbon dioxide recovery system of the present invention is characterized in that it comprises:

[0044] The absorption liquid that has absorbed the carbon dioxide is located in the internal reaction tank;

[0045] a light source disposed directly or fixedly to the reaction tank via another member and irradiating light to the absorption liquid in the reaction tank; and

[0046] A recovery port for recovering the carbon dioxide separated from the absorbent.

[0047] The same discussion as the above-mentioned recovery method can be made about the separation of the absorbed carbon dioxide from the absorption liquid. Here, by fixing a light source that emits light for separating the absorbed carbon dioxide directly or through other components in the reaction tank, the heat emitted by the light source can be supplied to the absorption liquid in the reaction tank. In this case, the energy used for separation can be efficiently utilized, so the absorbed carbon dioxide can be separated from the absorption liquid with less energy.

[0048] The light source may be disposed inside the reaction chamber.

[0049] By arranging the light source inside the reaction tank, the heat generated by the light source can be efficiently supplied to the absorbent in the reaction tank, so that the absorbed carbon dioxide can be desorbed from the absorbent with less energy.

[0050] The carbon dioxide recovery system may also include:

[0051] an inlet for introducing the absorption liquid into the reaction tank; and

[0052] a discharge port for discharging the absorption liquid after being irradiated with the light from the light source,

[0053] The absorbent flowing from the introduction port toward the discharge port is located in the reaction tank.

[0054] The removal of the absorbed carbon dioxide can also be carried out while circulating the absorption liquid. By circulating the absorption liquid while removing the absorbed carbon dioxide, for example, the absorbed liquid after removal can be directly sent to the carbon dioxide absorption system (absorption tank). In this case, the absorbed liquid after the carbon dioxide removal can be continuously used for the absorption of carbon dioxide.

[0055] The recovery port may be located on a side closer to the discharge port than the introduction port with respect to the flow direction of the absorbent.

[0056] In the case where the absorption liquid is circulated while the carbon dioxide is separated, the irradiation of light begins after the absorption liquid is introduced into the reaction tank. After that, the absorption liquid is continuously irradiated with light while circulating toward the discharge port. Here, in order to focus on the absorption liquid at a specific location, it is assumed that the absorption liquid is enclosed in an imaginary container in which the resistance to flow, the resistance to heat, and the shielding effect to light are all zero, and it is assumed that the absorption liquid flows along the flow of the absorption liquid together with the imaginary container. The absorption liquid in the imaginary container is irradiated with light throughout the period of flowing toward the discharge port. That is, the amount of light irradiated (irradiation radiation) of the absorption liquid in the imaginary container increases as it approaches the discharge port from the inlet. Similarly, the absorption liquid is heated by the heat emitted by the light source, and the temperature of the absorption liquid rises as it approaches the discharge port from the inlet. As a result, since the equilibrium condition moves in the direction of increasing the separation of carbon dioxide, the amount of carbon dioxide separated also increases as it approaches the discharge port.

[0057] In view of the above, when observing the entire absorbent flowing into the reaction tank, it is also assumed that the carbon dioxide is released more on the side closer to the discharge port than on the side closer to the inlet. Therefore, by arranging the carbon dioxide recovery port on the side closer to the discharge port, carbon dioxide can be effectively recovered.

[0058] In the above carbon dioxide recovery system,

[0059] The reaction tank includes a bottom wall portion and an upper wall portion vertically separated from the bottom wall portion.

[0060] The reaction tank may have a structure in which a vertical distance between the bottom wall portion and the upper wall portion increases as the distance from the introduction port to the discharge port increases.

[0061] As described above, it is assumed that the carbon dioxide is separated more on the side closer to the discharge port than on the side closer to the inlet. If the above configuration is used, since the distance between the bottom wall and the upper wall increases as the distance closer to the discharge port is, it is possible to ensure a sufficient space in the reaction tank for temporarily placing the carbon dioxide separated from the absorption liquid. Therefore, under this configuration, for example, by providing a recovery port in a manner that penetrates the upper wall on the side closer to the discharge port, a large amount of carbon dioxide can be effectively recovered.

[0062] In addition, the light source may be fixedly arranged relative to the bottom wall portion.

[0063] The upper wall portion is inclined relative to the bottom wall portion.

[0064] The recovery port is provided on the upper wall portion on a side closer to the discharge port than the introduction port.

[0065] According to the above configuration, carbon dioxide desorbed from the absorbent is guided to the side close to the discharge port by the inclination of the upper wall portion. Furthermore, by arranging the recovery port on the side close to the discharge port, carbon dioxide can be recovered efficiently.

[0066] The absorbing liquid may contain a carbon dioxide absorber formed of an alkaline material and a solvent.

[0067] The carbon dioxide absorber may be an amine-based material.

[0068] The discussion about the carbon dioxide absorber and solvent is the same as above.

[0069] In addition, another feature of the carbon dioxide recovery system of the present invention is that it comprises:

[0070] The absorption liquid that has absorbed the carbon dioxide is located in the internal reaction tank;

[0071] a light source for irradiating light to the absorption liquid in the reaction tank;

[0072] A heat source for supplying heat to the absorbent in the reaction tank; and

[0073] A recovery port for recovering the carbon dioxide separated from the absorbent.

[0074] By supplying heat from a heat source to the absorbent and irradiating light from a light source, it is possible to effectively desorb carbon dioxide from the absorbent while reducing the thermal energy applied compared to conventional methods, as described above.

[0075] It should be noted that the heat source may be configured as a separate device different from the light source, and the light source may also serve as the heat source.

[0076] In an embodiment in which the heat source can irradiate sunlight, the heat source may include a sunlight heat collecting member disposed directly on the reaction vessel or in a state of being fixed via another member.

[0077] According to the above configuration, the solar heat collecting member that supplies heat to the absorbent is heated by the sunlight. Since the sunlight is used, heat can be supplied to the absorbent with less energy, and the absorbed carbon dioxide can be desorbed appropriately.

[0078] Another feature of the method for recovering carbon dioxide of the present invention is that it comprises the following steps:

[0079] A step (d) of preparing an absorber for absorbing carbon dioxide, namely, a first absorber;

[0080] (e) a step of converting the sunlight received by the solar heat concentrating member into heat;

[0081] (f) supplying thermal energy derived from the heat obtained in the step (e) to the first absorber; and

[0082] and a step (g) of recovering the carbon dioxide desorbed from the first absorber in the step (f).

[0083] In this specification, the so-called "first absorber" refers to a state in which the absorber exhibiting carbon dioxide absorption has absorbed carbon dioxide. In addition, the so-called "second absorber" described later refers to a state before the absorber exhibiting carbon dioxide absorption has absorbed carbon dioxide. It should be noted that the second absorber also includes a state in which the absorber absorbs carbon dioxide and becomes the first absorber, and then receives heat energy to release the carbon dioxide.

[0084] As described above, in order to separate the carbon dioxide from the first absorber that has completed absorbing carbon dioxide, it is necessary to supply thermal energy to the first absorber. That is, in order to reduce the energy required for the recovery of carbon dioxide, it is crucial to reduce the energy consumed by the supply of thermal energy. In view of this, in the above-mentioned recovery method, a solar heat-collecting component that converts the received sunlight into heat is used to supply thermal energy from the heat source to the first absorber. By utilizing the heat from the solar source for the supply of thermal energy, the energy consumed by the supply of thermal energy can be reduced. It should be noted that the specific implementation will be described later in the "Specific Implementation".

[0085] It should be noted that from the perspective of reducing the energy required for heating, a method of driving a heater for heating, etc. through a so-called solar power generation system is also envisioned. However, the current situation is that in a solar power generation system, there is a problem with the wavelength range of light that can be used by a solar panel that absorbs sunlight. In particular, the proportion of infrared rays in sunlight accounts for more than half, but solar panels only use visible light and a part of ultraviolet rays. In addition, since there is also the influence of the conversion efficiency of the solar panel and the thermal efficiency of the input electricity by the heater, etc., this method cannot be said to be an effective use of sunlight. On the other hand, in the above-mentioned recovery method, as described later, infrared rays can be effectively used in particular, so the wavelength range of the light that can be used is wide, and sunlight can be used more effectively than, for example, a solar power generation system.

[0086] The step (f) may be a step of supplying the thermal energy to the first absorber via a heat transfer medium heated by the heat obtained in the step (e).

[0087] According to the above method, by using a heat transfer medium, for example, the heat converted from sunlight by the solar heat concentrating member can be efficiently supplied to the first absorber regardless of the position of the first absorber relative to the solar heat concentrating member.

[0088] Furthermore, the step (f) may include the step of introducing the heat transfer medium formed by air heated by the thermal energy obtained in the step (e) into the internal space of the reaction tank in which the first absorber is arranged.

[0089] The first absorber can be supplied with thermal energy by the atmosphere heated by the heat from the sunlight coming into contact with the first absorber. The first absorber receives the heat from the atmosphere and desorbs the carbon dioxide that has been absorbed.

[0090] However, near the first absorber where the desorption reaction of carbon dioxide progresses, the carbon dioxide concentration locally becomes high. In order to effectively promote the desorption reaction of carbon dioxide, it is preferred to reduce the carbon dioxide concentration near the first absorber. This is because: in the desorption reaction of carbon dioxide, by reducing the carbon dioxide concentration of the system on the generation (desorption) side, it is easy to make the reaction system advance to the generation side. The carbon dioxide concentration in the atmosphere is about 400ppm, which is a low concentration compared with the space near the first absorber where the desorption reaction of carbon dioxide progresses. Therefore, by introducing the atmosphere as a heat transfer medium into the internal space of the reaction tank, the carbon dioxide concentration near the first absorber can be reduced while supplying heat, and carbon dioxide can be effectively desorbed from the first absorber. That is, the heated atmosphere not only has the function of a heat transfer medium, but also functions as a desorption promoting gas that promotes the desorption of carbon dioxide.

[0091] The step (f) may be a step of exchanging heat between the heat transfer medium flowing outside the reaction tank in which the first absorber is disposed and the first absorber.

[0092] During the step (f), a desorption promoting gas composed of a gas having a carbon dioxide concentration lower than that in the internal space is introduced into the internal space of the reaction vessel.

[0093] The heat transfer medium may also be circulated outside the reaction tank to exchange heat with the first absorber. Through this heat exchange, heat is supplied to the first absorber, and the absorbed carbon dioxide is separated from the first absorber. In this case, a fluid such as air or water may be used as the heat transfer medium.

[0094] It should be noted that, at this time, as described above, from the viewpoint of effectively promoting the desorption reaction of carbon dioxide, it is suitable to introduce the desorption promoting gas with low carbon dioxide concentration into the inner space of the reaction tank. As the desorption promoting gas, nitrogen or atmosphere can be utilized. It should be noted that, from the viewpoint of energy and cost required for procurement, atmosphere is preferred.

[0095] During the step (f), the temperature of the internal space of the reaction vessel may be measured, and when the temperature is equal to or higher than a predetermined value, a cooling gas consisting of air having a lower temperature than the heat transfer medium may be introduced into the internal space.

[0096] As described above, by supplying heat to the first absorber, the absorbed carbon dioxide can be recovered. At this time, the temperature of the internal space of the reaction tank in which the first absorber is arranged is measured. When the temperature is above a specified value, it is preferred to cool the first absorber by introducing an atmosphere that is lower in temperature than the heat transfer medium. Here, the so-called specified value is a value determined by considering the thermal resistance of the carbon dioxide absorber constituting the first absorber, such as the boiling point. If the above method is used, even if the first absorber reaches a high temperature, the thermal influence on the carbon dioxide absorber constituting the first absorber can be reduced.

[0097] The above step (d) may also include:

[0098] a step (d1) of preparing an absorber before absorbing carbon dioxide, namely, a second absorber; and

[0099] After the second absorber is disposed in the reaction vessel, a process (d2) is performed in which a treatment target gas including carbon dioxide is introduced into the internal space of the reaction vessel to allow the second absorber to absorb the carbon dioxide.

[0100] The second absorber absorbs carbon dioxide contained in the treatment target gas in the reaction tank and becomes the first absorber (absorption process). Here, when the process of separating the absorbed carbon dioxide from the first absorber is carried out in a place different from the reaction tank where the absorption process is carried out, energy for transferring the first absorber is required. In contrast, if the above method is used, since the absorption process and the separation process are carried out in the same reaction tank, the energy required for transferring the first absorber can be suppressed, which is suitable.

[0101] Furthermore, the step (d1) may include a step of obtaining the second absorber by supporting a carbon dioxide absorbing liquid made of a basic material and exhibiting carbon dioxide absorbing properties in the pores of a solid material made of a porous substance having pores on the surface.

[0102] In this specification, the term "pore" refers to a microscopic hole having a diameter of about several nanometers to several tens of micrometers, and the term "porous material" refers to a material having countless pores on the surface.

[0103] By allowing the carbon dioxide absorbing liquid to be carried in the pores of the porous material, it can be used as a carbon dioxide absorber. In addition, by allowing the carbon dioxide absorbing liquid to be carried in the pores, the contact area between the carbon dioxide contained in the gas to be treated and the carbon dioxide absorbing liquid can be increased, and carbon dioxide can be effectively absorbed. The specific surface area of ​​the porous material is preferably 10m 2 / g or more, more preferably 50m 2 The specific surface area of ​​the porous material can be measured, for example, by a method in accordance with JIS Z 8830 (method for measuring specific surface area of ​​powder (solid) by gas adsorption).

[0104] As materials that can be used as porous substances, ceramic materials such as silicon dioxide, aluminum oxide, and zirconium oxide, engineering plastic materials such as polypropylene, polyacetal, polyamide, and polycarbonate, and carbon materials such as activated carbon can be listed. It should be noted that the shape of the porous substance is not particularly limited. Examples of the shape of the porous substance include granular, plate-like, tubular, honeycomb, and pellet-like.

[0105] The carbon dioxide absorbing liquid is prepared by dispersing carbon dioxide absorbing materials such as amine materials showing carbon dioxide absorbing properties in solvents such as water, polyethylene glycol (PEG) or dimethyl sulfoxide (DMSO). These solvents can also be combined in multiple ways. In addition, in order to reduce the viscosity of the carbon dioxide absorbing liquid and make it easy for the carbon dioxide absorbing liquid to enter the above-mentioned pores, for example, alcohol such as methanol can be added to the carbon dioxide absorbing liquid, and the alcohol can be evaporated after being impregnated in the above-mentioned porous material.

[0106] From the viewpoint of reducing the energy consumed by the temperature rise of the solvent in the heat energy supplied when carbon dioxide is separated and improving the utilization efficiency of heat energy, it is preferred that the concentration of the carbon dioxide absorbing liquid is high. On the other hand, for example, when the carbon dioxide absorbing liquid is used directly as an absorber, if the concentration of the carbon dioxide absorbing liquid is increased, the viscosity sometimes increases and the operation becomes difficult, and there are certain restrictions on increasing the concentration. In particular, for materials with high viscosity, the concentration of the carbon dioxide absorbing liquid is about 1% to 10%. In contrast, by supporting the carbon dioxide absorbing liquid in a solid material, it can be easily operated even when the concentration of the carbon dioxide absorbing liquid is high (for example, tens of%). That is, the result of increasing the concentration of the carbon dioxide absorbing liquid by using a solid absorber is to improve the utilization efficiency of heat energy. The preparation of the absorber is described in detail in the item "Specific Implementation Method".

[0107] As the carbon dioxide absorber, the above-mentioned amine-based materials can be used. It should be noted that, when water is not selected as the solvent of the carbon dioxide absorber, the reaction of the above-mentioned formula (3) becomes the main reaction.

[0108] If it is a carbon dioxide absorber that causes a carbon dioxide desorption reaction by supplying heat after absorbing carbon dioxide, the same discussion as above can be carried out. That is, the carbon dioxide absorber is not limited to amine-based materials. As other carbon dioxide absorbers, for example, oxides showing alkalinity, typically oxides containing alkali metals, niobium or tantalum, can be listed.

[0109] Furthermore, the step (d1) may include a step of blowing plasma gas or irradiating ultraviolet rays to the pores before causing the pores of the solid material to carry the carbon dioxide absorbing liquid.

[0110] If the above method is used, the wettability of the pore surface with respect to the carbon dioxide absorption liquid is improved, and the carbon dioxide absorption liquid can be more appropriately loaded with respect to the pore. In more detail, when plasma gas is blown to the pores, nitrogen molecules or oxygen molecules in the atmosphere are plasmatized, and the active species after plasmatization form hydrophilic functional groups (hydroxyl, carbonyl or carboxyl, etc.) on the surface of the pores. In the case of ultraviolet irradiation, free radicals are generated in the atmosphere by ultraviolet rays (mainly oxygen free radicals in the case of air). In addition, at the same time, by ultraviolet irradiation, the bonds between the molecules constituting the surface of the pores are cut, and the free radicals react with respect to the cut site, resulting in the formation of hydrophilic functional groups on the surface of the pores.

[0111] Another feature of the carbon dioxide recovery system of the present invention is that it comprises:

[0112] The absorber that completes the absorption of carbon dioxide is the first absorber;

[0113] The first absorber is located in the inner reaction tank;

[0114] introducing a heat transfer medium for supplying heat energy to the first absorber into an introduction port inside the reaction tank;

[0115] a heat source including a solar heat collecting member that converts received sunlight into heat, arranged in front of the first absorber in the flow direction of the heat transfer medium, and heats the heat transfer medium; and

[0116] A recovery port for recovering carbon dioxide separated from the first absorber.

[0117] The same discussion as the above-mentioned recovery method can be made about the separation of the absorbed carbon dioxide from the first absorber. That is, the heat transfer medium heated by the heat from the sunlight in the heat source is introduced into the reaction tank from the introduction port and contacts the first absorber, thereby supplying heat energy to the first absorber.

[0118] In addition, the carbon dioxide recovery system may also include:

[0119] a third flow path through which recovered gas including carbon dioxide recovered from the recovery port flows; and

[0120] A heat exchanger is disposed at a front stage of the first absorber with respect to a flow direction of the heat transfer medium, and performs heat exchange between the heat transfer medium and the recovery gas flowing through the third flow path.

[0121] The first absorber removes carbon dioxide by supplying heat. Therefore, the recovered gas containing the removed carbon dioxide reaches a relatively high temperature. Therefore, by exchanging heat between the recovered gas and the heat transfer medium and utilizing the thermal energy of the recovered gas for removing carbon dioxide, the energy utilization efficiency is improved.

[0122] The carbon dioxide recovery system may also include:

[0123] A first flow path connecting the heat source to the introduction port,

[0124] The heat source is configured to heat the heat transfer medium flowing through the first flow path at a position outside the reaction tank.

[0125] In addition, the carbon dioxide recovery system may also include:

[0126] A second flow path for introducing atmospheric air as a treatment target gas including carbon dioxide into the interior of the reaction tank; and

[0127] A first valve is configured to adjust the opening degree of the second flow passage to control the flow rate of the atmospheric air flowing through the second flow passage.

[0128] In the desorption process of desorbing the carbon dioxide that has been absorbed, the heat transfer medium heated by the heat source is introduced into the reaction tank via the first flow path. In addition, in the absorption process of making the second absorber in the state of desorbing carbon dioxide absorb carbon dioxide, the atmosphere as the treatment target gas is introduced into the reaction tank via the second flow path. That is, if the above-mentioned structure is used, since the absorption process and the desorption process of carbon dioxide can be carried out in the same reaction tank, the energy required for the transfer of the absorber can be suppressed, and as a result, carbon dioxide can be recovered with less energy.

[0129] In the above carbon dioxide recovery system,

[0130] A thermometer for measuring the temperature of the inner space of the reaction tank may also be provided.

[0131] The first valve adjusts the opening degree of the second flow path based on the measurement value of the thermometer.

[0132] As described above, it is preferable to reduce the thermal influence on the carbon dioxide absorber constituting the first absorber. If the above structure is used, even if the first absorber becomes hot due to the supply of heat for desorption, the first absorber can be cooled by introducing the atmosphere as the treatment target gas having a lower temperature than the heat transfer medium from the second flow path.

[0133] It should be noted that the carbon dioxide recovery system may also include a second valve.

[0134] The second valve can adjust the opening degree of the first flow path to control the flow rate of the atmospheric air as the heat transfer medium flowing through the first flow path.

[0135] In the above carbon dioxide recovery system, the absorber may be in a solid state. The structure of the absorber is the same as discussed above.

[0136] Effects of the Invention

[0137] According to the present invention, a method and system for recovering carbon dioxide capable of separating absorbed carbon dioxide from an absorbent with less energy can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0138] Figure 1 This is a conceptual diagram showing an example of an embodiment of the carbon dioxide recovery system of the present invention.

[0139] Figure 2A Yes Figure 1 A magnified view of the reaction tank portion.

[0140] Figure 2B This is an enlarged view of a state where a light source is fixed to a reaction vessel via other members.

[0141] Figure 3A This is a conceptual diagram of the experimental system used in the verification of Example 1.

[0142] Figure 3B This is a conceptual diagram of an experimental system used in the verification of Comparative Example 1.

[0143] Figure 4 This is a graph in which the temperature of the reaction tank during verification is plotted against the elapsed time.

[0144] Figure 5A This is a schematic diagram showing the reaction energy level when the amine-based material exhibits a reaction of absorbing or releasing carbon dioxide.

[0145] Figure 5B It is imitation Figure 5A Schematic diagram showing the energy supplied to the absorbing liquid.

[0146] Figure 6 It is an enlarged view of the installation portion of the light source in the reaction tank of the first modified example.

[0147] Fig. 7A This is a conceptual diagram of a reaction tank according to a second modification.

[0148] Figure 7B Observed from the +Z direction Fig. 7A Conceptual diagram of the reaction tank.

[0149] Figure 8 This is a conceptual diagram of a reaction tank according to a third modification.

[0150] Fig. 9 This is a conceptual diagram of a third modified example in which a plurality of reaction vessels are stacked in the Z direction.

[0151] Fig.10 This is a conceptual diagram of a reaction tank according to a fourth modification.

[0152] Fig.11 This is a conceptual diagram of a reaction tank according to a fifth modification.

[0153] Fig. 12A It is a perspective view of a reaction tank according to a sixth modification.

[0154] Fig. 12B Observed from the +Y direction Fig. 12A Schematic diagram of the reaction tank.

[0155] Fig.13A It is a perspective view of a reaction tank according to a seventh modification.

[0156] Fig. 13B Observed from the +X direction Fig.13A Schematic diagram of the reaction tank.

[0157] Fig. 13C Observed from the +Y direction Fig.13A Schematic diagram of the reaction tank.

[0158] Fig.14A It is a perspective view of a reaction tank according to an eighth modification.

[0159] Fig. 14B Observed from the +X direction Fig.14A Schematic diagram of the reaction tank.

[0160] Fig. 14C The observation is made along the normal direction of the inclined surface where the reaction tank is set. Fig.14A Schematic diagram of the reaction tank.

[0161] Fig.15 It is a schematic diagram showing an example of the internal structure of the heat collecting member.

[0162] Fig.16A This is a conceptual diagram showing an example of the installation plan of the reaction tank according to the ninth modification.

[0163] Fig. 16B This is a schematic diagram of the warm water generator when viewed along the +X direction.

[0164] Fig. 16C This is a conceptual diagram showing a scheme of heat exchange performed in a heat exchanger.

[0165] Fig.17A This is a cross-sectional view schematically showing an example of a carbon dioxide recovery system.

[0166] Fig. 17B It means in Fig.17A The recycling system is different from Fig.17A Figure 2 shows another scene.

[0167] Fig.18 Observe in different directions Fig.17A Figure 1 shows a recycling system.

[0168] Fig.19 This is a flow chart showing an example of the recovery method of the present invention.

[0169] Fig. 20A It is a cross-sectional view schematically showing the structure of a substrate supporting a carbon dioxide absorbing liquid.

[0170] Fig. 20B It is a cross-sectional view schematically showing the structure of the second absorbent body.

[0171] Fig. 20C It is a cross-sectional view schematically showing another example of the structure of the second absorbent body.

[0172] Fig.21 is a conceptual diagram of the experimental system used in the verification.

[0173] Fig. 22 is the spectrum of the halogen lamp used in the verification.

[0174] Fig.23 This is a graph showing the results of desorption of carbon dioxide during verification.

[0175] Fig.24 It is a drawing schematically showing a configuration example of a recovery system.

[0176] Fig.25 It is a cross-sectional view schematically showing the structure of a reaction tank.

[0177] Fig.26 It means in Fig.25 The reaction tank is different from Fig.25Figure 2 shows another scene.

[0178] Fig. 27 It is a cross-sectional view schematically showing the structure of a heat source.

[0179] Fig.28 Observed from the Z direction Fig. 27 The heat source is shown in the figure.

[0180] Fig.29 It is a diagram schematically showing the structure of another embodiment of the recovery system.

[0181] Fig.30 It means in Fig.29 The recycling system is different from Fig.29 Figure 2 shows another scene.

[0182] Fig.31 It is a diagram schematically showing another configuration example of the recovery system.

[0183] Fig.32A It is a schematic representation Fig.31 A three-dimensional diagram of the composition of the heat source.

[0184] Fig.32B Observed from the X direction Fig.32A Cross-sectional view of the heat source.

[0185] Fig.33 It is imitation Fig. 17B The drawings show the configuration of other embodiments of the recovery system. DETAILED DESCRIPTION

[0186] [First Configuration Example]

[0187] The first configuration example of the method and system for recovering absorbed carbon dioxide of the present invention is described below with reference to the accompanying drawings. It should be noted that the following drawings are schematic diagrams, and the size ratios and numbers on the drawings may not be consistent with the actual size ratios and numbers.

[0188] Figure 1 1 is a conceptual diagram showing an example of an embodiment of a carbon dioxide recovery system (hereinafter referred to as a "recovery system") according to the present invention. Figure 1 After describing the configuration of the recovery system 1 , a method for recovering absorbed carbon dioxide performed by the recovery system 1 will be described.

[0189] In each of the following drawings, an XYZ coordinate system including mutually orthogonal X, Y, and Z directions is described as appropriate. Typically, the Z direction is a vertical direction.

[0190] It should be noted that in the following description, when a direction is expressed with a distinction between positive and negative directions, it is recorded with a positive and negative sign such as "+X direction" and "-X direction". In addition, when a direction is expressed without distinguishing between positive and negative directions, it is simply recorded as "X direction". That is, in this specification, when it is simply recorded as "X direction", both "+X direction" and "-X direction" are included. The same applies to the Y direction and the Z direction.

[0191] like Figure 1 As shown in , the recovery system 1 includes an absorption tank 2 for allowing carbon dioxide contained in a treatment target gas 20 to be absorbed by an absorption liquid 10, a reaction tank 3 for separating the absorbed carbon dioxide from the absorption liquid 10 that has absorbed carbon dioxide, and a light source 6 for irradiating the absorption liquid 10 with light L1 in the reaction tank 3. The treatment target gas 20 is a gas that is an object of separating and recovering carbon dioxide from a gas containing carbon dioxide. As an example, the treatment target gas 20 can include exhaust gas, atmosphere, etc. As the absorption liquid 10, for example, an aqueous solution obtained by dispersing an amine-based material as a carbon dioxide absorber in water can be used.

[0192] The carbon dioxide contained in the treatment target gas 20 is absorbed by the absorbent 10. The gas after absorbing the carbon dioxide contained in the treatment target gas 20 (hereinafter referred to as "treated gas 21") is discharged from the absorber 2. Figure 1 In FIG. 1 , the treated gas 21 is represented by a dashed line.

[0193] The absorption liquid 10 that has absorbed carbon dioxide in the absorption tank 2 is sent to the reaction tank 3 via the flow path 4 using, for example, a liquid sending pump (not shown). Then, as described later, the absorption liquid 10 is irradiated with light L1 and supplied with heat H1, so that the absorbed carbon dioxide is separated from the absorption liquid 10. In the reaction tank 3, the gas containing the absorbed carbon dioxide separated from the absorption liquid 10 (hereinafter referred to as "separated gas 22") is recovered from the recovery port 7 provided in the reaction tank 3. Figure 1 In FIG. 1 , the desorbed gas 22 is indicated by a two-dot chain line.

[0194] In addition, in the reaction tank 3, the absorption liquid 10 after the absorption of carbon dioxide is separated is sent to the absorption tank 2 through the flow path 5 by a liquid delivery pump or the like (not shown). Then, it is again used to absorb the carbon dioxide contained in the treatment target gas 20. It should be noted that, for example, heat exchange can be performed in the absorption liquid 10 flowing in the flow paths 4 and 5 by a heat exchanger (not shown). This heat exchange can increase the temperature of the absorption liquid 10 flowing into the reaction tank 3, which is suitable. The flow direction of the absorption liquid 10 is Figure 1The absorption tank 2, the flow path 4 and the flow path 5 can be a conventionally known recovery system.

[0195] Next, refer to Figure 1 An example of a method for recovering absorbed carbon dioxide that can be performed by the recovery system 1 (hereinafter referred to as a “recovery method”) will be described.

[0196] The recovery method includes a pre-step S100 of absorbing carbon dioxide from a treatment target gas 20, a step S101 of irradiating light to an absorbing liquid 10 that has absorbed carbon dioxide, a step S102 of supplying heat to the absorbing liquid 10 that has absorbed carbon dioxide, and a step S103 of recovering carbon dioxide separated from the absorbing liquid 10.

[0197] (Previous process S100)

[0198] In the absorption tank 2, the treatment target gas 20 is typically brought into gas-liquid contact with the absorption liquid 10, so that the carbon dioxide contained in the treatment target gas 20 is absorbed by the absorption liquid 10. It should be noted that, in the previous stage of the previous process, for example, pre-treatment such as cooling the treatment target gas 20 or screening the treatment target gas 20 for substances that hinder the absorption of carbon dioxide may be performed.

[0199] (Light Irradiation Step S101)

[0200] As described above, energy is required to remove the absorbed carbon dioxide from the absorbing liquid 10. Therefore, in this recovery method, the absorbing liquid 10 that has absorbed carbon dioxide is irradiated with light L1 from the light source 6 and heat H1 is supplied. First, the irradiation of the absorbing liquid 10 with light L1 will be described.

[0201] For easy understanding, Figure 2A Yes Figure 1 A diagram obtained by enlarging a portion of the reaction tank 3 in FIG. Figure 2A In FIG. 1 , an example is shown in which the light source 6 is directly fixed to the surface in the −Z direction of the reaction tank 3 . Figure 2A In the figure, the case where the light source 6 is composed of a plurality of LED elements 8 mounted on a substrate 9 is exemplified, but a lamp may be used as the light source 6 .

[0202] In the present invention, the wavelength of the light L1 emitted from the light source 6 is not limited, but as an example, light within the wavelength range of 250 nm to 600 nm is emitted from the light source 6. The wavelength of the light L1 emitted by the light source 6 is preferably selected based on the absorption spectrum of the carbon dioxide absorber such as the amine material. From the viewpoint of effectively giving the energy generated by the irradiation of the light L1 to the carbon dioxide absorber contained in the absorbing liquid 10, a wavelength that is easily absorbed by the carbon dioxide absorber and not easily absorbed by the solvent is more preferred.

[0203] like Figure 2A As shown in , when the light source 6 is arranged outside the reaction tank 3, the reaction tank 3 is formed of a member that can transmit the light L1 emitted by the light source 6, so that the absorption liquid 10 located inside the reaction tank 3 can be irradiated with the light L1. Figure 2A In the figure, the light L1 is indicated by a solid arrow, and the same is true in the following figures. As a member that can transmit the light L1, for example, glass can be used. By adopting such a structure, especially when the reaction tank 3 is set outdoors or in a non-dark room, if it is daytime, the absorption liquid 10 in the reaction tank 3 can also be irradiated with sunlight.

[0204] It should be noted that if Figure 2A As shown in , when the light source 6 is arranged only on the bottom side of the reaction tank 3, the material of only the bottom of the reaction tank 3 may be formed by a member that can transmit the light L1. Figure 6 Described below.

[0205] In addition, when the reaction chamber 3 is composed of a member that can transmit the light L1, it is also possible to Figure 2A As shown in , a reflective film 11 is formed on a part of the outer surface of the reaction tank 3. It is assumed that, depending on the wavelength of the light L1, a part of the light L1 irradiated to the absorbing liquid 10 is not absorbed by the absorbing liquid 10 but passes through the absorbing liquid 10. Therefore, by forming the reflective film 11, the light that once passed through the absorbing liquid 10 can be directed back to the absorbing liquid 10, and the absorbing liquid 10 can be effectively irradiated with the light L1. As such a reflective film 11, aluminum coating or the like can be used.

[0206] It should be noted that in Figure 2A In the description, the light source 6 is provided on the surface of the reaction tank 3 in the -Z direction and irradiates the light L1 emitted in the +Z direction. However, the light source 6 can be provided at any position of the reaction tank 3 within the range in which the light can be irradiated to the absorption liquid 10. That is, for example, the light source 6 can be provided so as to irradiate the light L1 to the absorption liquid 10 from the X direction and the Y direction. In this case, the formation range of the reflection film 11 can be adjusted appropriately.

[0207] In the above description, the reflective film 11 is formed on the outer surface of the reaction vessel 3 . However, the reflective film 11 may be formed on the inner surface of the reaction vessel 3 if the reflective film 11 is made of a material that does not deteriorate even when in contact with the absorbing liquid 10 .

[0208] The light irradiation step S101 corresponds to the step (a).

[0209] (Heat supply step S102)

[0210] In order to remove the absorbed carbon dioxide from the absorbing liquid 10, heat H1 is supplied to the absorbing liquid 10 (see Figure 2A ).exist Figure 1 and Figure 2A In the example shown in , the light source 6 is directly fixed to the reaction tank 3. Therefore, the heat H1 released when the light source 6 emits light is supplied to the absorption liquid 10 located inside the reaction tank 3. That is, in this example, the light irradiation step S101 and the heat supply step S102 are performed simultaneously. Figure 2A In FIG. 1 , heat H1 is indicated by a dotted arrow, and the same applies to the following drawings.

[0211] It should be noted that, generally speaking, heat is easily conducted vertically upward. Figure 2A For example, it is preferable to arrange the light source 6 at the bottom side of the reaction tank 3 so that the +Z direction corresponds to the vertically upward direction. In other words, the heat H1 generated by the light source 6 can be effectively supplied to the absorbing liquid 10.

[0212] also, Figure 2B It is imitation Figure 2A The light source 6 is fixed to the reaction tank 3 via another member (hereinafter referred to as a "heat transfer member"). Figure 2B As shown in , the light source 6 may be fixed to the reaction tank 3 via a heat transfer member 13. The heat transfer member 13 is provided for the purpose of supplying the heat H1 emitted by the light source 6 to the absorbing liquid 10. From the viewpoint of efficiently supplying the heat H1 to the absorbing liquid 10, the heat transfer member 13 is preferably a metal member with high thermal conductivity. For example, copper or aluminum may be used as the heat transfer member 13.

[0213] As a supplement for the sake of caution, the heat supply process S102 is provided for the purpose of making the temperature of the absorbing liquid 10 higher than the ambient temperature. Typically, the absorbing liquid 10 is heated to a temperature of 35°C to 120°C through the heat supply process S102. It should be noted that, from the viewpoint of reducing the thermal energy used for the separation of carbon dioxide, the temperature of the absorbing liquid 10 after heating is preferably below 60°C, more preferably below 50°C, and particularly preferably below 40°C. By setting the scheme to heat to a temperature of about 50°C or less, the concern about scalding can be suppressed, so the system can be installed in an ordinary household. As a result, the effect of greatly reducing the concentration of carbon dioxide in the atmosphere can be expected.

[0214] The heat supply step S102 corresponds to the step (b).

[0215] (Recovery Step S103)

[0216] The desorbed gas 22 containing the desorbed carbon dioxide that has been completely absorbed is typically stored in a storage tank (not shown) such as a gas cylinder or the like. Alternatively, the desorbed gas 22 may be sent to a carbon dioxide utilization facility such as a plant factory through a pipe, for example.

[0217] This recovery step S103 corresponds to step (c).

[0218] [Verification 1]

[0219] The effect of irradiating the absorbing liquid that has absorbed carbon dioxide with light will be described in more detail below.

[0220] (Example 1)

[0221] Figure 3A is a conceptual diagram of the experimental system used in this verification. In this experimental system, Figure 3A As shown in , an absorption liquid 30 is arranged inside the reaction tank 33. The reaction tank 33 is made of glass. In addition, the absorption liquid 30 is a secondary amine aqueous solution with a concentration of 20 mass%. For the absorption liquid 30, carbon dioxide gas for experiment is used in advance to absorb carbon dioxide. More specifically, after the absorption liquid 30 absorbs carbon dioxide until it no longer shows the absorption of additional carbon dioxide, it is adjusted by standing in the atmosphere for about 1 hour in order to reach an equilibrium state.

[0222] For the absorption liquid 30, Figure 3A As shown in FIG. 1 , the light L1 is irradiated using a light source 36. The light source 36 includes an LED element 38 having a peak wavelength of 365 nm.

[0223] In addition, in order to supply the heat H1 emitted by the light source 36 to the absorption liquid 30, the light source 36 is arranged in a manner close to the reaction tank 33. That is, the light source 36 emits light L1, and the absorption liquid 30 inside the reaction tank 33 is irradiated with light L1 and supplied with heat H1 at the same time. The lighting time of the light source 36 is set to 50 minutes, during which the temperature of the reaction tank 33 is measured by the thermocouple 39 installed in the reaction tank 33. It should be noted that in Example 1 and Comparative Example 1 described later, in order to set the temperature of the reaction tank 33 of both to the same degree, the experiment was conducted while manually adjusting the output power of the power supply 37 connected to the light source 36.

[0224] After the light source 36 is turned on, nitrogen gas is introduced into the reaction tank 33 by injecting a syringe 35a filled with nitrogen gas to capture the desorbed carbon dioxide (see Figure 3A ). Since the reaction tank 33 is sealed by the plug 34, the piston of the syringe 35b for gas collection is drawn out by supplying gas with the syringe 35a, so that the gas in the reaction tank 33 can be collected. By measuring the carbon dioxide concentration of the gas in the reaction tank 33 collected in this way, the amount of carbon dioxide gas released from the absorbing liquid 30 can be measured.

[0225] (Comparative Example 1)

[0226] Figure 3B It is imitation Figure 3A A conceptual diagram showing an experimental system used in the verification of Comparative Example 1. In the verification of Comparative Example 1, Figure 3B As shown in FIG. 1 , a copper light shielding plate 40 is disposed between the light source 36 and the reaction chamber 33 so as to shield the light L1 emitted from the light source 36 .

[0227] At this time, the heat H1 emitted by the light source 36 is supplied to the reaction tank 33 via the light shielding plate 40. In addition, the light L1 emitted by the light source 36 is shielded by the light shielding plate 40, but a part of the light L1 is absorbed by the light shielding plate 40 and contributes to the temperature rise of the light shielding plate 40, and is supplied to the reaction tank 33 as the heat H1. That is, in this comparative example 1, only the heat H1 is supplied to the absorption liquid 30 inside the reaction tank 33. The other configurations and operation steps are the same as those of Example 1.

[0228] (Verification of results)

[0229] Figure 4 This is a graph in which the horizontal axis is set to the time elapsed from the lighting of the light source 36, and the vertical axis is plotted with the temperature measured by the thermocouple 39. Figure 4In the figure, the result of Example 1 is shown by a solid line, and the result of Comparative Example 1 is shown by a dotted line. As described above, in order to set the temperature of the reaction tank 33 in Example 1 and Comparative Example 1 to the same level, the experiment was conducted while adjusting the output power of the power supply 37. As a result, as shown in FIG. Figure 4 As shown in , the temperature of the reaction tank 33 in Comparative Example 1 becomes 1°C to 2°C higher than that in Example 1 after about 20 minutes. This is considered to be an error caused by the output of the manual power supply 37, and the temperature of the reaction tank 33 in Example 1 and Comparative Example 1 can be said to be about the same.

[0230] In Example 1, the amount of gas captured by the syringe 35 b was 118 mL. The carbon dioxide concentration of the gas was 16%. That is, 18.9 mL of carbon dioxide was desorbed from the absorbing liquid 30 by the irradiation of light from the light source 36 and the supply of heat.

[0231] On the other hand, in Comparative Example 1, the amount of gas captured by the syringe 35 b was 110 mL. The carbon dioxide concentration of the gas was 14%. That is, 15.4 mL of carbon dioxide was desorbed from the absorbing liquid 30 by the heat supplied from the light source 36 .

[0232] As described above, although the temperature of the reaction tank 33 in Comparative Example 1 is the same as that in Example 1, or more specifically, 1°C to 2°C higher, more carbon dioxide is desorbed in Example 1. This indicates that more carbon dioxide can be desorbed by irradiating the absorbent 30 with light and supplying heat than by supplying heat alone.

[0233] The present inventors speculate as follows about the reason why more carbon dioxide is desorbed by irradiating the absorbent 30 with light in addition to supplying heat.

[0234] Figure 5A Schematic diagram showing the energy level of an amine material when it absorbs or releases carbon dioxide. As described above, when an amine material absorbs carbon dioxide, bicarbonate ions, carbamate ions, or carbamic acid are generated. Figure 5A In FIG. 1 , the line representing the energy level of the bicarbonate ion is indicated by a dotted line, and the line representing the energy level of the carbamate ion and carbamic acid is indicated by a solid line.

[0235] In order to make the amine material absorb carbon dioxide and transfer it to bicarbonate ions from the energy level where the amine material, carbon dioxide and solvent exist independently, in other words, the state where carbon dioxide is separated, activation energy E1 is required. Similarly, in order to make the amine material absorb carbon dioxide and transfer it to carbamate ions or carbamic acid, activation energy E2 is required.

[0236] In addition, in their reverse reactions, energy greater than the respective activation energies (E1, E2) is required. This is because the reaction in which the amine material absorbs carbon dioxide to generate bicarbonate ions, carbamate ions, or carbamic acid is an exothermic reaction, and energy is released during absorption. At this time, it is known that the energy E4 released when generating carbamate ions or carbamic acid is greater than the energy E3 released when generating bicarbonate ions. This means that carbamate ions and carbamic acid are energetically stable compared to bicarbonate ions. Figure 5A In the diagram, the energy levels corresponding to the carbamate ion and carbamic acid are shown to be lower than the energy level of the bicarbonate ion.

[0237] If we focus on the release of carbon dioxide, in order to release carbon dioxide from bicarbonate ions, energy equivalent to activation energy E1 is required in addition to energy E3. In addition, in order to release carbon dioxide from carbamate ions and carbamic acid, energy equivalent to activation energy E2 is required in addition to energy E4.

[0238] Here, in order to remove carbon dioxide, it is assumed that the energy E generated by the heat supplied to the absorbent is H and the energy E generated by the light irradiation L (Refer to Figure 5B ). Figure 5B It is imitation Figure 5A A schematic diagram showing the energy supplied to the absorption liquid. Figure 5B Medium, energy E H The energy E is represented by a dotted line. L It is represented by a two-dot dash line. Figure 5B As shown in H Although the reaction of carbon dioxide being separated from bicarbonate ions can be induced, the reaction of carbon dioxide being separated from carbamate ions and carbamic acid cannot be induced. On the other hand, if the energy E generated by light irradiation is considered, L , then the energy becomes greater than the sum of the energy E4 required for separation and the activation energy E2, and carbon dioxide can be separated from the carbamate ion and carbamic acid.

[0239] The above discussion is consistent with the fact that bicarbonate ions have a small light absorption effect, while carbamate ions and carbamic acid have a large light absorption effect. In other words, heat energy is dominant in the separation of carbon dioxide from bicarbonate ions, and the contribution of energy generated by light irradiation is small. On the other hand, for the separation of carbon dioxide from carbamate ions and carbamic acid, the supply of energy generated by light irradiation is effective.

[0240] It is believed that by supplying not only heat but also light to the absorbent that has absorbed carbon dioxide, more carbon dioxide can be desorbed. In addition, it can be said that even under the desorption condition of low temperature where little heat energy is supplied to the absorbent, a large amount of carbon dioxide can be desorbed by irradiating the absorbent with light.

[0241] If heat energy is supplied to a substance to such an extent that atoms can be separated, molecular dissociation occurs. Conventional methods of supplying heat energy to an absorbing liquid that has absorbed carbon dioxide in order to desorb carbon dioxide utilize the above phenomenon.

[0242] On the other hand, many substances have light absorption bands in the range of near-ultraviolet to visible regions. If light is irradiated on a substance, the molecules constituting the substance are excited by the light energy and move to the ground state. In addition, depending on the magnitude of the light energy, the positions of the atomic nuclei constituting the substance sometimes change and the chemical bonds change. By utilizing light excitation to transfer to an electron orbit showing high energy, the covalent bond becomes unstable, the repulsion between the atomic nuclei increases, and the bond dissociates in the excited state.

[0243] As described above, the dissociation of molecules using heat energy and the dissociation of molecules using light energy have different action mechanisms. Immediately after the molecules dissociate due to light energy, it becomes easy for intermediates to show a free radical state. The following reaction is induced by this intermediate, and it acts in the direction that the dissociation reaction is easy to proceed.

[0244] That is, the above-mentioned recovery method is a method of generating a dissociation phenomenon of molecules originating from different mechanisms by utilizing both heat energy and light energy, thereby being able to improve the efficiency of carbon dioxide removal while reducing the input energy compared to previous methods. In addition, it is also possible to achieve the removal of carbon dioxide in a lower temperature environment than before, which greatly contributes to the introduction and popularization of carbon dioxide recovery systems. This also greatly contributes to Goal 13 of the Sustainable Development Goals (SDGs) led by the United Nations, "To discuss emergency measures to reduce climate change and its impacts; take emergency measures to reduce climate change and its impacts."

[0245] As an example, the irradiance of the light source 36 is set to 150 mW / cm 2 The light emitting surface of the light source 36 is uniformly set to 100 cm 2 In this case, the energy per unit time radiated from the light source 36 is 15 W. The energy E per photon is defined by E=(h·c) / λ using Planck's constant h, light speed c, and wavelength λ.

[0246] If the peak wavelength of the light L1 emitted from the light source 36 is set to 365 nm, the energy E per photon contained in the light L1 emitted from the light source 36 is calculated as

[0247] E=(6.626×10 -34 )×(2.998×10 8 ) / (365×10 -9 )=5.442×10 -19 [J].

[0248] Therefore, the number N of photons of the light L1 emitted from the light source 36 is calculated as

[0249] N = 15 / (5.442×10 -19 )=2.756×10 19 .

[0250] When the total amount of carbamate ions and carbamic acid showing light absorption contained in the absorbing liquid 30 is assumed to be 0.1 mol, and Avogadro's constant is set to NA, the number of molecules K of carbamate ions and carbamic acid is calculated as K = 0.1 × NA. Therefore, the reference irradiation time τ of the light L1 required to dissociate all these molecules is calculated as

[0251] τ=K / N=0.1×(6.022×10 23 ) / (2.756×10 19 )=2185(seconds).

[0252] The above is an example of a design standard for calculating the reference irradiation time τ. Figure 1 When the light source 6 irradiates the light L1 while the absorbing liquid 10 is temporarily stored in the reaction tank 3, as in the system 1 shown in FIG. 3 , the actual irradiation time of the light L1 can be set based on the reference irradiation time τ calculated by the above method, for example. Fig. 7A As described later, when irradiating the light L1 while flowing the absorbing liquid 10 , the flow rate of the absorbing liquid 10 can be adjusted based on the reference irradiation time τ calculated by the above-mentioned method.

[0253] [Modifications]

[0254] Hereinafter, a modified example of the carbon dioxide recovery system will be described, focusing on the parts that are different from the above-mentioned embodiment.

[0255] (First Modification)

[0256] In the above embodiment, the example in which the reaction chamber 3 is composed of a member that can transmit the light L1 is described. However, even if the reaction chamber 3 is not composed of such a member, Figure 6As shown in FIG. 1 , for example, by forming a light irradiation window 12 in a portion where the light source 6 is provided in the reaction vessel 3 , the absorbing liquid 10 in the reaction vessel 3 can be irradiated with the light L1 . Figure 6 It is an enlarged view of the installation part of the light source in the reaction tank of the first modification. The window 12 for light irradiation can be made of glass or the like, for example.

[0257] (Second Modification)

[0258] In the above embodiment, an example in which the light source 6 is arranged outside the reaction tank 3 is shown (see Figure 1 etc.), but the light source 6 can also be arranged inside the reaction tank 3. Fig. 7A This is a conceptual diagram of the reaction tank of the second variant. Figure 7B Observed from the +Z direction Fig. 7A It should be noted that in Figure 7B In FIG. 4 , an example of installing two light sources 46 is shown, but two or more light sources may be installed. In addition, the place and range where the light source 46 is installed may be adjusted appropriately.

[0259] like Fig. 7A and Figure 7B As shown in , the light source 46 is arranged inside the reaction tank 43 and is in contact with the circulating absorption liquid 10. In this way, by arranging the light source 46 inside the reaction tank 43, the heat H1 generated when the light source 46 emits light can be efficiently supplied to the absorption liquid 10. For example, by providing the power supply member 41 that is in electrical contact with the light source 46 outside the reaction tank 43, the power supply for driving the light source 46 can be energized with the light source 46 inside the reaction tank 43.

[0260] In the above-mentioned embodiment, the case where the absorbing liquid 10 is retained in the reaction tank 3 when the absorbed carbon dioxide is desorbed is described (see Figure 1 ), but it is also possible to remove carbon dioxide while circulating the absorbing liquid 10. Fig. 7A As shown in , the reaction tank 43 includes an inlet 44 for introducing the absorbent 10 and an outlet 45 for discharging the absorbent 10 after carbon dioxide is desorbed. With this configuration, the absorbed carbon dioxide can be desorbed while the absorbent 10 is circulated. That is, in this example, the absorbent 10 is circulated in the X direction.

[0261] As described above, it is assumed that the carbon dioxide is released more on the side closer to the outlet 45 than on the side closer to the inlet 44. Fig. 7A and Figure 7B As shown in FIG. 8 , the recovery port 47 for recovering the desorbed gas 22 is preferably arranged on the side closer to the exhaust port 45 than the introduction port 44 .

[0262] (Third Modification)

[0263] From the viewpoint of absorbing light as efficiently as possible with respect to the absorbing liquid 10, the width of the absorbing liquid 10 is preferably narrow with respect to the direction in which light travels. Figure 8 As shown in FIG. 1 , it is effective to set the internal space where the absorbing liquid 10 is located in the reaction tank 53 to be flat in a front view. Figure 8 This is a conceptual diagram of a reaction tank according to a third modification.

[0264] exist Figure 8 , an example is shown in which the light source 56 is directly fixed to the reaction tank 53. The light L1 emitted by the light source 56 is irradiated to the absorption liquid 10 via the window 12 provided on the surface in the -Z direction of the reaction tank 53. In addition, the heat H1 emitted by the light source 56 is supplied to the absorption liquid 10 via the reaction tank 53 including the window 12.

[0265] At this time, if Figure 8 As shown in , it is preferable to make the upper wall 58 of the reaction tank 53 inclined relative to the bottom wall 59. That is, the reaction tank 53 is structured such that the Z-direction separation distance D1 between the bottom wall 59 and the upper wall 58 increases as the distance from the introduction port 54 to the discharge port 55 increases with respect to the X direction.

[0266] By configuring in this way, a space (hereinafter referred to as "desorption space 60") for temporarily accommodating the desorption gas 22 containing carbon dioxide desorbed from the absorbent 10 can be sufficiently ensured in the reaction tank 53. In addition, by inclining the upper wall portion 58, the desorption gas 22 in the desorption space 60 can be guided to the recovery port 57.

[0267] Furthermore, a plurality of reaction tanks may be provided. Fig. 9 3 is a conceptual diagram of a case where a plurality of reaction tanks of the third modified example are stacked in the Z direction. As described above, in the reaction tank 53, it is preferred that the internal space where the absorbent 10 is located is set to a flat shape in the front view (see Figure 8 ) In this case, the installation area of ​​the reaction tank 53 in the virtual XY plane becomes relatively large.

[0268] In addition, depending on the amount of carbon dioxide gas contained in the treatment target gas 20, the volume of the absorbent 10 needs to be increased, and it is also assumed that the installation area of ​​the recovery system becomes larger. Fig. 9 For example, it is preferable to arrange the reaction tank 53b on the top side of the reaction tank 53a so that the +Z direction corresponds to the vertical upward direction. By arranging in this way, the installation area of ​​the reaction tanks (53a, 53b) can be effectively utilized.

[0269] It should be noted that in Fig. 9In the above description, the case where two reaction tanks (53a, 53b) are connected in parallel is described, but the reaction tanks (53a, 53b) may be connected in series. In addition, two or more reaction tanks may be stacked.

[0270] (Fourth Modification)

[0271] In the above embodiment, an example is described in which the heat generated by the light source 6 is supplied to the absorbing liquid 10. However, the present invention does not exclude a configuration in which a heat source other than the light source for irradiating the absorbing liquid 10 with light is provided. Fig.10 : is a conceptual diagram of a reaction tank according to a fourth modification. Fig.10 In the figure, the absorption tank is omitted. Fig.10 As shown in FIG. 1 , the reaction tank 63 may include a heat source 68 for supplying heat to the absorbent 10. As the heat source 68, for example, a heater, a boiler, etc. may be used.

[0272] In the above embodiment, the light source 6 is fixed to the reaction tank 3 directly or via other members. However, as long as heat can be supplied to the absorbing liquid 10, Fig.10 As shown in , the light source 66 may be arranged separately from the reaction tank 63. It should be noted that even when the reaction tank 63 has the heat source 68, the light source 66 can be fixed in the reaction tank 63 directly or through other components, and the heat generated by the light source 66 can be supplied to the absorbing liquid 10.

[0273] (Fifth Modification)

[0274] In addition, if a so-called intermittent form is adopted, for example, there is no need Figure 1 The absorber 2 shown in FIG. 1 can absorb and desorb carbon dioxide using only the reaction tank. Fig.11 This is a conceptual diagram of a reaction tank according to a fifth modification.

[0275] The process of absorbing and removing carbon dioxide using this structure is described below. Fig.11 As shown in , the reaction tank 73 has an inlet 74 for the gas 20 to be treated to flow in and a recovery port 77 for recovering the treated gas 21 and the desorbed gas 22. During the absorption of carbon dioxide, the valve 79a provided in the flow path connected to the inlet 74 and the valve 79b of the rear section of the recovery port 77 are set to an open state, and another valve 79c of the rear section of the recovery port 77 is set to a closed state. Then, for example, the absorption liquid 10 is pressurized by a pump from the flow path 78 by a liquid feeding pump, so that the absorption liquid 10 and the gas 20 to be treated are in gas-liquid contact. At this time, the treated gas 21 is discharged from the flow path of the valve 79b provided with the recovery port 77.

[0276] During the desorption of carbon dioxide, valves 79a and 79b are set to a closed state, and valve 79c is set to an open state. Then, for example, light source 76 is used to irradiate light and supply heat to the absorption liquid 10, and the absorbed carbon dioxide is desorbed. At this time, the desorbed gas 22 is recovered from the flow path of valve 79c having a recovery port 77. It should be noted that in addition to the light source 76, a heat source for supplying heat to the absorption liquid 10 may be further provided.

[0277] If this configuration is used, there is an advantage that the installation area required for the configuration of the system is small. For example, this modification example may be adopted depending on the amount of the process target gas 20 generated and the concentration of carbon dioxide contained in the process target gas 20.

[0278] (Sixth Modification)

[0279] In the fourth modification, the reaction tank 63 is provided with a heat source 68 for supplying heat to the absorbent 10. As one embodiment of the heat source 68, a member that absorbs sunlight and converts it into heat (hereinafter, for convenience, referred to as a "sunlight heat collecting member" or simply a "heat collecting member") may be used. Fig. 12A and Fig. 12B Provide explanation.

[0280] Fig. 12A Corresponding to the stereogram of the reaction tank. Fig. 12B Observed from the +Y side Fig. 12A For the convenience of explanation, the interior of the reaction tank 83 is shown in a transparent manner. Fig. 12A and Fig. 12B , the +Z direction corresponds to vertically upward.

[0281] The reaction tank 83 of this modification example is, for example, a cylindrical shape that is circular when viewed from the +Z direction. Fig. 12A As shown in FIG. 1 , light sources 86 are arranged so as to be spaced apart from each other in the circumferential direction of the reaction chamber 83. Light L1 emitted by the light source 86 irradiates the absorbing liquid 10 through the window 12 for light irradiation (see FIG. 1 ). Fig. 12B ). In addition, the light source 86 is directly fixed to the reaction tank 83. That is, the heat H1 generated by the light source 86 is supplied to the absorbing liquid 10.

[0282] Furthermore, the reaction tank 83 has a window 14 on the +Z side surface. By arranging the reaction tank 83 of this modification example outdoors, sunlight C2 emitted by the sun C1 is irradiated to the absorbent 10 in the reaction tank 83 through the window 14. The window 14 is made of, for example, quartz glass.

[0283] The details of the light contained in the sunlight C2 are said to be approximately 7% ultraviolet light, 43% visible light, and 50% infrared light. A portion of the light contained in the sunlight C2 (typically ultraviolet light) is absorbed by the carbon dioxide absorber contained in the absorbent 10, which helps to release carbon dioxide. This is the same as the above discussion. In addition, the effect of promoting the release of carbon dioxide can also be expected by the solvent contained in the absorbent 10 absorbing a portion of the light contained in the sunlight C2 (typically infrared light) and raising the temperature of the absorbent 10. In this regard, since the amine-based materials typically used as carbon dioxide absorbers show absorption of ultraviolet light, the wavelength range of the available light can effectively utilize the sunlight C2 in a wide range.

[0284] In addition, the reaction tank 83 is provided with a heat collecting member 15 (see Fig. 12B ). In this modification, an example is shown in which the heat collecting member 15 is arranged on the bottom wall portion 59 of the reaction tank 83. That is, the heat collecting member 15 is directly fixed to the reaction tank 83. It should be noted that the heat collecting member 15 can be made of metal such as stainless steel. In addition, from the perspective of effectively absorbing the sunlight C2, it is typically preferred to apply a black coating.

[0285] It is also considered that part of the sunlight C2 passes through the absorbing liquid 10 and reaches the bottom wall portion 59 of the reaction tank 83. Fig. 12B As shown in FIG. 1 , by arranging the heat collecting member 15 on the bottom wall portion 59, the energy of the light can be suitably utilized. The heat collecting member 15 absorbs the sunlight C2 (typically infrared light) and is heated, and supplies heat H1 to the absorbing liquid 10. By utilizing the heat collecting member 15 heated by the sunlight C2 in this way, the energy required for heating can be reduced compared to a heater, a boiler, etc., and heat H1 can be supplied to the absorbing liquid 10.

[0286] From the perspective of reducing the energy required for heating, it is also assumed that the heater or the like is driven by a so-called solar power generation system. However, in the solar power generation system, there is a problem with the wavelength range of light that can be used by the solar panel that absorbs the sunlight C2. On the other hand, in this modification, since infrared light can be effectively used in particular, it has the following characteristics: the wavelength range of light that can be used covers a wide range, and sunlight C2 can be effectively used compared to the solar power generation system.

[0287] (Seventh Modification)

[0288] Reference Figures 13A to 13C , the reaction tank of the seventh variant is described. Fig.13A Corresponding to the stereogram of the reaction tank. Fig. 13B Observed from the +X side Fig.13AIn the drawings of the reaction tank 83, for the convenience of explanation, the interior of the reaction tank 83 is shown in perspective. Fig. 13C Observed from the +Y side Fig.13A The accompanying drawing of the reaction tank 83, and Fig. 13B Likewise, the interior of the reaction tank 83 is shown in perspective. Fig. 13C In the figure, the heat transfer member 13 is omitted.

[0289] The reaction tank 83 of this modification example is provided with a round bar-shaped heat collecting member 16. More specifically, the heat collecting member 16 is composed of a round bar-shaped member, which is arranged at a position separated in the +Z direction relative to the reaction tank 83, and the round bar shape is formed by a plurality of pieces. Fig.13A As shown in FIG. 8 , the heat collecting member 16 is fixed in the reaction tank 83 via the heat transfer member 13 .

[0290] By placing the reaction tank 83 of this modification outdoors, sunlight C2 from the sun C1 is irradiated to the heat collecting member 16, and the sunlight C2 is absorbed and heated in the heat collecting member 16. The heat generated in the heat collecting member 16 is supplied to the absorbing liquid 10 as heat H1 via the heat transfer member 13 connected to the heat collecting member 16.

[0291] In this modification, the heat collecting member 16 disposed at the +Z side of the reaction tank 83 is composed of a plurality of round rod-shaped members. In contrast, if a flat plate-shaped heat collecting member 15 is disposed instead of the heat collecting member 16, then when the sun C1 is at a relatively low position, such as in the early morning or evening time periods, the incident angle of the sunlight C2 relative to the surface of the heat collecting member 15 becomes larger, and the reflectivity of the sunlight C2 on the surface of the heat collecting member 15 increases. By setting Fig. 13C The heat collecting member 16 composed of a plurality of round rod-shaped members as shown in FIG. 1 can improve the absorption efficiency of the sunlight C2 regardless of the height position of the sun C1.

[0292] It should be noted that a flat plate-shaped heat collecting member 15 may be additionally provided inside the reaction tank 83. Figure 13B to Figure 13C In the example shown in FIG, similarly to the sixth modification, a flat heat collecting member 15 is additionally arranged on the bottom wall 59 of the reaction tank 83. Since the heat from the heat collecting member 15 is supplied to the absorbing liquid 10, the description thereof is omitted because it is the same as the sixth modification.

[0293] It should be noted that, in this modification, the heat collecting member 16 disposed on the +Z side of the reaction tank 83 is described as a round rod-shaped member, but this is only an example. Even if the shape of the heat collecting member 16 is other than a round rod such as a rectangular column, it is also included in the scope of the present invention.

[0294] (Eighth Modification)

[0295] Reference Figures 14A to 14C , the reaction tank of the eighth variation example is described. Fig.14A Corresponding to the stereogram of the reaction tank. Fig. 14B Observe along the +X direction Fig.14A In the drawings of the reaction tank 83, for the convenience of explanation, the interior of the reaction tank 83 is shown in perspective.

[0296] Fig. 14C The angle is observed along the normal direction of the inclined surface of the stand 87 described later. Fig.14A For the convenience of explanation, the interior of the reaction tank 83 is shown in perspective. Fig. 14C In the figure, the stand 87 is omitted.

[0297] exist Figures 14A to 14C , the +Z direction corresponds to vertically upward.

[0298] In the seventh modification, an example is shown in which the heat collecting member 16 is fixed to the reaction tank 83 via the heat transfer member 13. In contrast, in this modification, the heat collecting member 16 is directly fixed to the reaction tank 83.

[0299] In this modification, the reaction tank 83 is disposed on a stand 87 having an inclined surface 87a. By disposing the reaction tank 83 on the inclined surface 87a, the heat collecting member 16 fixed in the reaction tank 83 is also disposed along the inclined surface 87a. By setting such an arrangement, the sunlight C2 from the sun C1 can be effectively taken into the heat collecting member 16.

[0300] It should be noted that, in this variant, Fig. 14B and Fig. 14C As shown in , a recess 84 may be provided in a part of the outer wall of the reaction tank 83. The recess 84 has a shape corresponding to the shape of the end 16a of the heat collecting member 16, and the end 16a is arranged to contact the recess 84. As a result, since the area where the heat collecting member 16 and the reaction tank 83 are in contact is increased, the heat H1 from the heat collecting member 16 can be effectively supplied to the absorbing liquid 10.

[0301] In addition, as an example of the heat collecting member 16, it is also possible to use Fig.15 The structure shown in . Fig.15 Schematic diagram showing an example of the internal structure of a heat collecting member. Fig.15As shown in FIG. 1 , one end of each of the outer tube 161 and the inner tube 162 of the heat collecting member 16 is sealed by a sealing portion 163 to form a space (hereinafter referred to as a "sealed space 164" for convenience). The sealed space 164 is set to a vacuum state, so that the heat H1 generated by the heat collecting portion 165 described later is not easily leaked to the outside, which is suitable. For example, the outer tube 161 and the inner tube 162 can be made of a glass material such as quartz glass.

[0302] In addition, a heat collecting portion 165, a heat transfer sheet 166, and a heat pipe 167 having one end 167a exposed to the outside are arranged inside the inner tube 162 sealed by a sealing portion 169 made of silicone, for example. The inside of the heat pipe 167 is in a vacuum state, and a working fluid 168 such as pure water is arranged. Typically, the heat collecting portion 165 is made of a metal such as stainless steel, and the heat transfer sheet 166 is made of a metal such as aluminum.

[0303] The heat collecting member 16 is used, for example, Figures 14A to 14C In the described solution, it can be set in the reaction tank 83. That is, Fig. 14C The end 16a of the heat collecting member 16 corresponds to the end 167a of the heat pipe 167. When the heat collecting member 16 is irradiated with sunlight C2, the heat collecting portion 165 is heated, and heat H1 is supplied to the working liquid 168 via the heat transfer sheet 166. The heated and evaporated working liquid 168 moves toward one end 167a of the heat pipe 167. At the end 167a, the high-temperature vapor of the working liquid 168 supplies heat H1 to the absorbent 10 via the reaction tank 83 (see Fig. 14C ). Heat H1 is supplied to the absorbent 10, and the vapor of the low-temperature working fluid 168 is liquefied and moved to the other end 167b of the heat pipe 167. By repeating this series of operations, the absorbent 10 is heated using the sunlight C2 as an energy source.

[0304] (Ninth Modification)

[0305] As a heat source 68 (refer to Fig.10 ) can also use a heat medium that is heated to a high temperature. That is, heat H1 is supplied to the absorbent 10 by heat exchange between the high-temperature heat medium and the absorbent 10. From the viewpoint of reducing the energy required to supply the heat H1, the heat medium is preferably heated by sunlight C2. For this point, refer to Figures 16A to 16C Provide explanation.

[0306] Fig.16A This is a conceptual diagram showing an example of the installation plan of the reaction tank 89 of the ninth variant. As described later, warm water is supplied to the heat exchanger 91 by the warm water generator 90 installed on the roof 94, and the absorbent 10 in the reaction tank 89 is heated in the heat exchanger 91. Fig. 16B This is a schematic diagram when the hot water generator 90 installed on the roof 94 is viewed from the +X direction. For the convenience of explanation, the interior of the hot water generator 90 is shown in perspective. Fig. 16C 91 is a conceptual diagram showing a scheme of heat exchange performed in the heat exchanger 91. Figures 16A to 16C , the +Z direction corresponds to vertically upward.

[0307] like Fig.16A As shown in FIG. 8 , the reaction tank 89 is connected to the heat exchanger 91 via a flow path 92 . In addition, the heat exchanger 91 is connected to the hot water generator 90 via a flow path 93 .

[0308] The reaction tank 89 may be formed by the above-mentioned embodiment and the configuration of the reaction tank of each modified example. In addition, the shape of the reaction tank can be designed according to the installation environment. Fig.16A , the figure shows a reaction tank 89 designed with a relatively short side in the X direction and a plurality of light sources 86 directly fixed on the -X side. In the reaction tank 89, a flow path 92 connected to a heat exchanger 91 is provided, and the absorbent 10 is guided to the heat exchanger 91 via the flow path 92.

[0309] The warm water generator 90 is, for example, Fig. 16B As shown in FIG. 1 , the hot water generator 90 has an L-shaped cross-sectional shape, and contains water 95 as a heat medium. The hot water generator 90 has a flat heat collecting member 15 in a portion of the outer wall surface. The heat collecting member 15 absorbs the sunlight C2 and is heated, and the temperature of the water 95 becomes high temperature (hereinafter referred to as "hot water 95"). The hot water 95 is guided to the heat exchanger 91 via the flow path 93.

[0310] like Fig. 16C As schematically shown in FIG. 1 , heat is exchanged in the heat exchanger 91 between the absorbent 10 flowing through the flow path 92 and the warm water 95 flowing through the flow path 93 . Thus, the warm water 95 supplies heat H1 to the absorbent 10 .

[0311] It is also assumed that the temperature of the warm water 95 is relatively low depending on the sunshine conditions and time period of the sun C1. Therefore, it is appropriate to perform heat exchange in the heat exchanger 91 when the temperature of the warm water 95 is higher than that of the absorbent 10.

[0312] In addition, Fig.16A In the example of installing the hot water generator 90 on the roof 94 of a building from the viewpoint of effectively irradiating the heat collecting member 15 with the sunlight C2, the example is shown. Fig.16AAs shown in , the reaction tank 89 and the heat exchanger 91 are preferably installed at a location (such as the ground) other than the roof 94. For example, since the absorbent 10 containing the amine material is located inside the reaction tank 89, the reaction tank 89 is particularly preferably installed on the ground from the viewpoint of safety.

[0313] It should be noted that, in this modification, the example in which the warm water generator 90 is installed on the roof 94 of the building is described, but the present invention is not limited thereto. Since the warm water generator 90 can adopt a structure substantially similar to the reaction tank 83 described above in the seventh modification and the eighth modification, its installation scheme can also appropriately refer to the contents described above in the seventh modification and the eighth modification.

[0314] In this modification, the medium supplied to the heat exchanger 91 via the flow path 93 is set to "warm water 95", but it is not limited to water as long as it is a fluid (heat medium) that is relatively easy to heat up. In this case, the "warm water generator 90" can be replaced by a "fluid temperature increaser".

[0315] The above-described embodiments and modifications may be implemented in combination as appropriate.

[0316] As mentioned in the topic at the beginning, in the carbon dioxide recovery system, it is natural to reduce the energy required for carbon dioxide removal, and in many cases, it is also required to operate the system at low cost. As shown in the above-mentioned modification, by using sunlight, the cost of carbon dioxide removal can be further reduced.

[0317] [Second Configuration Example]

[0318] A second configuration example of the carbon dioxide recovery method and recovery system of the present invention will be described below with reference to the drawings.

[0319] (First Embodiment)

[0320] Fig.17A and Fig. 17B This is a cross-sectional view schematically showing an example of a carbon dioxide recovery system (hereinafter, simply referred to as a “recovery system”). Fig.17A This corresponds to a scene in which a step (step S2 described later) of absorbing carbon dioxide contained in the treatment target gas G1 such as the atmosphere is performed. Fig. 17B This corresponds to a scene in which a step of removing the absorbed carbon dioxide (step S4 described later) is performed.

[0321] also, Fig.18 Observe in different directions Fig.17A See the attached figure of the recycling system. Fig.17A , Fig. 17B and Fig.18After describing the structure of the recovery system 101, the method for recovering carbon dioxide performed by the recovery system 101 is described.

[0322] In the following figures, an XYZ coordinate system including mutually orthogonal X, Y, and Z directions is preferably described together. Typically, the Z direction is the vertical direction. If the explanation is based on this definition, then Fig.18 Corresponding to viewing from the Z direction Fig.17A It should be noted that, as described later, in Fig.18 In the figure, part of the structure of the reaction tank 102 is omitted.

[0323] like Fig.17A As shown in , the recovery system 101 includes a reaction tank 102 , an absorber 103 located inside the reaction tank 102 and exhibiting carbon dioxide absorption properties, and a heat source 104 that supplies thermal energy to the absorber 103 .

[0324] As described above, the absorber 103 includes a carbon dioxide absorber having the property of absorbing carbon dioxide and releasing the absorbed carbon dioxide by supplying heat H1. The absorber 103 is formed of, for example, a granular porous material having pores on the surface, and the carbon dioxide absorber is supported in the pores.

[0325] The reaction tank 102 contains an absorber 103, a solar heat collecting member 115 (hereinafter referred to as "heat collecting member 115") as a heat source 104, and a heat transfer member 119 for effectively transferring heat H1 of the heat collecting member 115 to the absorber 103. In addition, the reaction tank 102 has a light-transmitting portion 120 made of a glass material such as quartz glass on the +Z side so that the heat collecting member 115 can receive the sunlight C2 (see also Fig. 17B ).

[0326] In this embodiment, if Fig.18 As shown in , a plurality of plate-shaped heat transfer members 119 are arranged in the X direction. In addition, from the viewpoint of effectively transferring the heat of the heat collecting member 115 to the absorber 103, the heat transfer member 119 is connected on the +Z side and is directly arranged relative to the heat collecting member 115 (see Fig. 17B ). It should be noted that Fig.18 In the figure, for the convenience of illustration, the connecting portion of the light-transmitting portion 120, the heat-collecting member 115 and the heat-conducting member 119 is omitted.

[0327] In the present embodiment, an example in which the heat source 104 is arranged inside the reaction tank 102 is shown, but as described later in the section of the second embodiment, the arrangement of the heat source 104 is not limited to this example.

[0328] Next, an example of a method for recovering absorbed carbon dioxide (hereinafter simply referred to as a “recovery method”) that can be performed by the recovery system 101 will be described.

[0329] Fig.19 1 is a flowchart showing an example of the recovery method of the present invention. The recovery method 101a includes the following steps: step S1 of preparing an absorber in a state before absorbing carbon dioxide (hereinafter, for convenience, referred to as the "second absorber 103a"); step S2 of making the second absorber 103a absorb carbon dioxide to prepare an absorber in a state after absorbing carbon dioxide (hereinafter, for convenience, referred to as the "first absorber 103b"); step S3 of converting sunlight C2 into heat H1; step S4 of supplying the heat obtained in step S3 to the first absorber 103b; and step S5 of recovering the gas containing carbon dioxide separated from the first absorber 103b by the execution of step S4 (hereinafter, for convenience, referred to as the "recovered gas G2").

[0330] It should be noted that, by executing steps S4 and S5, the first absorber 103b becomes the second absorber 103a after removing the absorbed carbon dioxide. That is, the recovery method 101a can repeat the steps after step S2 after executing step S5.

[0331] (Step S1: Preparation of Second Absorbent Body)

[0332] First, an absorber (second absorber 103a) is prepared before absorbing carbon dioxide. For example, the second absorber 103a is prepared by supporting a carbon dioxide absorbing liquid containing an amine material on a substrate formed of a porous material having pores on the surface.

[0333] The carbon dioxide absorbing liquid is prepared by dispersing an amine material in a solvent such as PEG. As an example, when the solvent is set to PEG, the ratio of the solvent to the amine material is 1:1. It should be noted that, depending on the viscosity of the amine material, an alcohol such as methanol may be added to the carbon dioxide absorbing liquid. For example, by mixing methanol, the viscosity of the carbon dioxide absorbing liquid formed by mixing PEG and the amine material can be reduced.

[0334] Fig. 20A 1 is a cross-sectional view schematically showing the structure of the substrate 110. Fig. 20A As shown in , the substrate 110 is a solid material having numerous fine pores 111 on the surface. Then, a carbon dioxide absorbing liquid in which an amine material is dispersed is brought into contact with the substrate 110 so that the fine pores 111 carry the carbon dioxide absorbing liquid. Fig. 20B1 is a cross-sectional view schematically showing the structure of the second absorber 103a prepared through the above operation. For example, the diameter D12 of the pore 111 is set to be less than 15 nm. Fig. 20A and Fig. 20B In the figure, for the convenience of illustration, the diameter D12 is exaggerated relative to the particle diameter D11 of the substrate 110.

[0335] also, Fig. 20C It is imitation Fig. 20B The cross-sectional view schematically shows the structure of the second absorber 103a when the diameter D12 is relatively large (e.g., about several μm). The diameter D12 is appropriately designed according to, for example, the surface tension of the carbon dioxide absorbing liquid 112 carried in the pores 111 and the carbon dioxide absorption capacity. It should be noted that from the viewpoint of suppressing the carried carbon dioxide absorbing liquid 112 from peeling off from the pores 111, the diameter D12 is preferably 0.1 μm or less.

[0336] In addition, by adding alcohol such as methanol to the carbon dioxide absorbing liquid 112, the viscosity of the carbon dioxide absorbing liquid 112 is reduced, and as a result, the carbon dioxide absorbing liquid 112 can be suitably entered into the pores 111. In this case, after the carbon dioxide absorbing liquid 112 is supported on the substrate 110, the substrate 110 is preferably heated to evaporate the alcohol. For example, the heating condition when methanol is used is about 60°C. It should be noted that when evaporating the alcohol, the substrate 110 is preferably placed in a reduced pressure atmosphere of, for example, about 60 kPa.

[0337] In addition, before the substrate 110 is loaded with the carbon dioxide absorbing liquid 112, plasma gas may be blown onto the substrate 110 or ultraviolet rays may be irradiated onto the substrate 110. In this way, the hydrophilicity of the surface of the pores 111 included in the substrate 110 can be increased, and the carbon dioxide absorbing liquid 112 can be appropriately loaded. It should be noted that the hydrophilic treatment of the surface of these pores will be described in detail in the item [Verification] in the later section.

[0338] The second absorbent body 103a obtained through the above operation is put into the interior of the reaction tank 102 (see Fig.17A ).

[0339] Thus, step S1 of preparing the second absorbent body 103a corresponds to step (d1).

[0340] (Step S2: Carbon dioxide absorption step)

[0341] like Fig.17A As shown in FIG. 1 , a treatment target gas G1 containing carbon dioxide is introduced from an inlet 105 into the reaction tank 102 where the second absorber 103a is located, so as to contact the second absorber 103a. Fig.18, a scheme of the process target gas G1 flowing in the reaction tank 102 is schematically shown. Thus, the second absorber 103a absorbs the carbon dioxide in the process target gas G1, and the first absorber 103b that has absorbed the carbon dioxide is obtained. It should be noted that, for the sake of easy understanding, in each of the drawings, the first absorber 103b that has absorbed the carbon dioxide is hatched (see Fig. 17B The treatment target gas G1 whose carbon dioxide concentration is reduced by absorbing carbon dioxide is discharged through the discharge port 106, for example, to the outside space.

[0342] It should be noted that, as described later, the reaction tank 102 is assumed to be irradiated with sunlight C2 (step S3). On the other hand, from the viewpoint of effectively absorbing carbon dioxide using the second absorber 103a, it is preferable to set the atmosphere in the reaction tank 102 to a low temperature. Therefore, in step S2, the sunlight C2 irradiated to the reaction tank 102 may be shielded by any shielding member not shown. In addition, step S2 may be performed at a time period when there is no or little irradiation of sunlight C2, such as at night.

[0343] Examples of the treatment target gas G1 include the atmosphere or exhaust gas from factories, etc. In particular, when the treatment target gas G1 is exhaust gas, before being introduced into the reaction tank 102, pretreatment such as cooling the treatment target gas G1 or screening the treatment target gas G1 for substances that hinder the absorption of carbon dioxide may be performed.

[0344] In this way, step S2 of preparing the first absorber 103b for the second absorber 103a to absorb carbon dioxide corresponds to step (d).

[0345] (Step S3: Converting sunlight into heat)

[0346] As described above, energy is required to remove the absorbed carbon dioxide from the first absorber 103b. Therefore, heat H1 is supplied to the first absorber 103b. The recovery method of this embodiment converts sunlight C2 into heat H1 to reduce the energy consumed in supplying heat H1.

[0347] like Fig. 17B As shown in , the heat source 104 is composed of a heat collecting member 115 arranged vertically above the reaction tank 102 (+Z side). The heat collecting member 115 absorbs the sunlight C2 taken in from the light-transmitting portion 120 and is heated. For example, from the viewpoint of effectively absorbing the sunlight C2, the heat collecting member 115 is typically composed of a metal such as aluminum or copper coated with a black color. In addition, the heat collecting member 115 may also be coated with a black body material such as graphite that shows a high absorption rate with respect to light.

[0348] exist Fig. 17B In the example of the embodiment, the light-transmitting portion 120 is formed by a plurality of transparent members 121 made of a glass material such as quartz glass. In addition, a decompressed low-pressure space 122 is formed between these transparent members 121. The pressure of the low-pressure space 122 is, for example, 10 kPa or less, and is typically approximately near zero pressure. The low-pressure space 122 is provided from the perspective of making it difficult for the heat H1 converted by the heat collecting member 115 to be conducted to the +Z side, but the present invention is not limited to whether the low-pressure space 122 is formed.

[0349] Step S3 of converting the sunlight C2 into heat H1 corresponds to step (e).

[0350] (Step S4: Supplying Heat to the First Absorber)

[0351] The heat H1 obtained in the above step S3 is supplied to the first absorber 103b. Fig. 17B As shown in , the reaction tank 102 has a heat transfer member 119 for effectively supplying the heat H1 of the heat collecting member 115 to the first absorber 103b. Typically, the heat transfer member 119 is directly arranged relative to the heat collecting member 115 and is heated by the heat of the heat collecting member 115. As the heat transfer member 119, for example, a material with high thermal conductivity such as aluminum, copper, and ceramics can be used. It should be noted that the heat transfer member 119 can also be integrally formed of the same material as the heat collecting member 115.

[0352] like Fig. 17B As shown in , the heat H1 radiated from the high temperature heat transfer member 119 is supplied to the first absorber 103b, and the first absorber 103b is heated. That is, in this embodiment, the step S3 of converting sunlight C2 into heat H1 and the step S4 of supplying heat H1 to the first absorber 103b are automatically performed.

[0353] Furthermore, as described above, in order to effectively promote the desorption reaction of carbon dioxide, it is preferable to reduce the carbon dioxide concentration near the first absorber 103b. Fig. 17B As shown in , while heat H1 is supplied, a desorption promoting gas B1 such as air or nitrogen is introduced into the reaction vessel 102 from the introduction port 105 .

[0354] In addition, in order to supply the heat H1 to the first absorber 103b in step S4, a heat transfer medium including a fluid may be used, and this configuration will be described in detail in the second embodiment later.

[0355] In this way, step S4 of supplying heat H1 to the first absorbent body 103b corresponds to step (f).

[0356] (Step S5: Recovering the Desorbed Carbon Dioxide)

[0357] The recovered gas G2 containing the carbon dioxide separated by step S4 is sent to a carbon dioxide utilization facility such as a plant factory through, for example, the discharge port 106 and a pipe (not shown). That is, the discharge port 106 corresponds to a "recovery port". However, in the present invention, the delivery destination of the recovered gas G2 is not limited.

[0358] Thus, step S5 of collecting carbon dioxide corresponds to step (g).

[0359] [Verification 2]

[0360] The fact that carbon dioxide can be effectively recovered through the above-mentioned steps S1 to S5 will be described with reference to the examples. Fig.17A , Fig. 17B and Fig.18 The described configuration was used to verify the recovery of carbon dioxide from the atmosphere as the treatment target gas G1.

[0361] Fig.21 It is imitation Fig. 17B A schematic cross-sectional view of the experimental system used in this verification is shown. Fig.21 The figure shows the execution scene of steps S3 to S5. Fig.17A The internal dimensions of the reaction tank 102 used in this verification are 5 cm in length (X direction), 2 cm in width (Y direction), and 0.7 cm in height (Z direction).

[0362] As the heat collecting member 115, an aluminum plate-shaped member having a size of 5 cm in length, 2 cm in width, and 0.2 cm in height and coated with a black body material was provided at a position of 0.5 cm in height.

[0363] In this verification, an amine material classified as a diamine was used as the carbon dioxide absorber, and PEG was used as the solvent. That is, the carbon dioxide absorbing liquid 112 was a diamine solution adjusted to a volume ratio of 1:1 with PEG as the solvent.

[0364] As a solid material for supporting the diamine solution, granular silica manufactured by Fuji Silysia was used. The silica had an average particle size of 1 to 5 mm and a specific surface area of ​​100 to 200 m 2 / g.

[0365] First, the diamine solution is weighed so that the weight of the diamine solution becomes several tens of wt% for every 1g of solid material, and methanol is added to the diamine solution at a certain ratio to adjust the mixed solution. Then, 1g of the solid material is added to the mixed solution and stirred. The stirring is performed while heating at about 50°C in a reduced pressure atmosphere of 50kPa. In this way, after the diamine solution is impregnated in the solid material, the methanol is evaporated by heating in a reduced pressure atmosphere, thereby obtaining the second absorber 103a.

[0366] It should be noted that in this verification, from the viewpoint of removing carbon dioxide absorbed during the adjustment of the second absorber 103a, after evaporating methanol, the second absorber 103a was heated at 70°C for several hours while nitrogen gas (purity 99.9%) was circulated at 0.5 L / min. Thereafter, the amount of amine material supported relative to the solid material was estimated by weighing the second absorber 103a, and the result was 18 wt%.

[0367] The second absorber 103a obtained through the above operation is placed in the reaction tank 102. Then, as the treatment target gas G1, the atmosphere (carbon dioxide concentration of about 400 pm) is introduced into the reaction tank 102 at a flow rate of 7.5 mL / min for several tens of hours to obtain the first absorber 103b that has completed the absorption of carbon dioxide (step S2).

[0368] Since carbon dioxide is absorbed by the second absorber 103a, the carbon dioxide concentration of the treatment target gas G1 after contacting the second absorber 103a decreases. Afterwards, if the absorption of carbon dioxide by the second absorber 103a is completed (first absorber 103b), the carbon dioxide concentration of the treatment target gas G1 after passing through the reaction tank 102 becomes the same as the state before being introduced into the reaction tank 102. Therefore, in this verification, it is judged that the second absorber 103a has fully absorbed carbon dioxide when the carbon dioxide concentration of the treatment target gas G1 measured at the rear section of the exhaust port 106 reaches 400ppm.

[0369] In this verification, the halogen lamp 130 is used to irradiate the heat collecting member 115 with light L1 (see Fig.21 ). Fig. 22 The spectrum of the halogen lamp 130 used in this verification is shown in FIG. Fig. 22 As shown in , the halogen lamp 130 used in this verification has a peak intensity at about 1000nm where the luminous intensity becomes the maximum, and in the range of 500nm to 2000nm, the light intensity shows more than 40% of the peak intensity. It should be noted that in this verification, the input power of the halogen lamp 130 was set to 50W.

[0370] Furthermore, when the halogen lamp 130 was turned on to desorb the absorbed carbon dioxide, the atmosphere as the desorption promoting gas B1 was flowed through the reaction tank 102 at a flow rate of 7.5 mL / min.

[0371] Fig.23 This is a graph showing the results of carbon dioxide removal in this verification. Fig.23 In FIG. 1 , the horizontal axis shows the elapsed time from the lighting of the halogen lamp 130 , and the vertical axis shows the carbon dioxide concentration measured at the position of the exhaust port 106 .

[0372] like Fig.23 As shown in , the carbon dioxide concentration of the recovered gas G2 exceeds the typical atmospheric carbon dioxide concentration of 400 ppm (0.04%). This is because the first absorber 103b receives the supply of heat H1 from the heat collecting member 115 heated by the irradiation of light L1 and removes the carbon dioxide. In addition, the maximum carbon dioxide concentration of the recovered gas G2 reaches about 9600 ppm (0.96%). This is 24 times the carbon dioxide concentration of the atmosphere. From this point, it can also be said that in this verification, the carbon dioxide was properly removed from the first absorber 103b.

[0373] As described above, it is clear from this verification that at least the light L1 in the wavelength range of 500nm to 2000nm is converted into heat H1 and used for the removal of carbon dioxide. On the other hand, it is known that the intensity of sunlight C2 is particularly high from a wavelength of 500nm to a wavelength of 2500nm. That is, in this verification, the light L1 from the halogen lamp 130 is used, but it can be understood that even if the light L1 is replaced by sunlight C2, the removal of carbon dioxide can be performed in the same appropriate manner.

[0374] In this verification, a diamine-based amine material was used as the carbon dioxide absorber. However, the same discussion as above can be performed as long as the carbon dioxide absorber causes a desorption reaction of carbon dioxide by supplying thermal energy.

[0375] [Verification 3]

[0376] As described above, in step S1 of preparing the second absorber 103a, before the substrate 110 carries the carbon dioxide absorbing liquid 112, plasma gas may be blown onto the substrate 110 or ultraviolet rays may be irradiated onto the substrate 110. The effect of irradiating the substrate 110 with ultraviolet rays has been verified and will be described below.

[0377] Specifically, when the second absorber 103a is adjusted by the same method as described above in Verification 2, the solid material is irradiated with ultraviolet light having a peak wavelength of about 172 nm using a Xe excimer lamp before being put into the mixed solution. The irradiance of the ultraviolet light irradiation is set to several tens of mW / cm 2, for a few seconds.

[0378] After that, the second absorber 103a was weighed and the amount of the amine material supported on the solid material was estimated by evaporating methanol and heating in the same manner as described above in Verification 2. The results of comparison with the above-mentioned amount obtained in Verification 2 without ultraviolet irradiation are shown in Table 1 below.

[0379] [Table 11]

[0380]

[0381] According to Table 1, by irradiating the solid material with ultraviolet rays, the amount of amine-based material supported in the solid material becomes about 1.2 times that in the case where no ultraviolet rays are irradiated (Verification 2). This is believed to be because: by irradiation with ultraviolet rays, hydrophilic functional groups are formed on the pore surfaces of the solid material, resulting in an increase in the wettability of the pore surfaces with respect to the carbon dioxide absorbing liquid containing the amine-based material.

[0382] By increasing the amount of carbon dioxide absorbent loaded in the solid material, the carbon dioxide absorption capacity of the absorbent is improved. In addition, it is speculated that as a result of the improved wettability of the pore surface to the carbon dioxide absorption liquid, when the carbon dioxide absorption step and the desorption step are repeated (see Fig.19 ), the carbon dioxide absorbing liquid can be prevented from peeling off from the pore surface. That is, by carrying the carbon dioxide absorbing liquid after irradiating the solid material with ultraviolet rays, the deterioration of the absorber caused by the peeling of the carbon dioxide absorbing liquid can be prevented even when the carbon dioxide is repeatedly recovered. Thus, it can be expected that the recovery capacity of carbon dioxide can be maintained when observing the recovery system as a whole.

[0383] By blowing plasma gas into the pores of the solid material, hydrophilic functional groups can also be formed on the pore surface. That is, based on the results of this verification, it is speculated that the plasma gas blowing can also hydrophilize the pore surface and increase the amount of carbon dioxide absorber loaded in the solid material.

[0384] As described above, according to the second configuration example of the present invention, by converting sunlight C2 into heat H1, compared with the previous method, it is possible to reduce input energy and improve the recovery efficiency of carbon dioxide. This also greatly contributes to the goal 13 of the Sustainable Development Goals (SDGs) led by the United Nations, "Advice for emergency measures to reduce climate change and its impacts; Take emergency measures to reduce climate change and its impacts."

[0385] (Second Embodiment)

[0386] Hereinafter, a second embodiment of the second configuration example of the present invention will be described mainly focusing on the parts that are different from the first embodiment.

[0387] In the first embodiment, the heat source 104 is disposed inside the reaction tank 102, but the heat source 104 may be disposed outside the reaction tank 102 at a position independent of the reaction tank 102. That is, in this embodiment, the heat transfer medium heated by the heat source 104 is introduced into the reaction tank 102, and the heat H1 is supplied to the first absorber 103b inside the reaction tank 102.

[0388] Fig.24 1 is a diagram schematically showing the structure of the second embodiment of the recycling system 101, and some of the components are shown in block diagrams. Fig.24 As shown in , the recovery system 101 of this embodiment includes a reaction tank 102, a heat source 104, a first flow path 131 connecting the heat source 104 and the reaction tank 102, a second flow path 132 for introducing the treatment target gas G1 into the reaction tank 102, and a third flow path 133 located at the rear section of the reaction tank 102 with respect to the flow direction of the treatment target gas G1, etc. It should be noted that in Fig.24 In the figure, step S4 is shown (see Fig.19 ) depicts a scene in which the atmosphere as the heat transfer medium A1 is introduced into the reaction tank 102 from the first flow path 131.

[0389] In the present embodiment, the atmosphere sent into the reaction tank 102 by a circulation mechanism such as an air supply fan (not shown) is used as the heat transfer medium A1. In addition, in the present embodiment, the treatment object gas G1 is the atmosphere. Therefore, the recovery system 101 has a first valve V1 capable of controlling the flow rate of the atmosphere circulating in the second flow path 132, a second valve V2 capable of controlling the flow rate of the atmosphere circulating in the first flow path 131, and a control unit 108 for controlling the opening and closing states of each valve (V1, V2). Fig.24 In FIG. 1 , the first valve V1 is set to a closed state, and the second valve V2 is set to an open state. In order to schematically express the open and closed states of the valves, the positions of the valves relative to the pipes are depicted differently.

[0390] The reaction tank 102 has a thermometer 109 for measuring the temperature of the internal space of the reaction tank 102. The control unit 108 can send a signal (d1, d2) for adjusting the opening of each valve (V1, V2) based on the temperature information d0 in the reaction tank 102 from the thermometer 109 as described later.

[0391] Hereinafter, the configuration of this embodiment will be described with reference to Figure 25 to Figure 28 Provide explanation. Fig.25 and Fig.26is a cross-sectional view schematically showing the structure of the reaction tank 102, Fig.25 Corresponding to the scene of step S2, Fig.26 The scene corresponding to step S4 (refer to Fig.19 ).also, Fig. 27 and Fig.28 is a cross-sectional view schematically showing the structure of the heat source 104, Fig.28 It is imitation Fig.18 Viewed from the Z direction Fig. 27 The heat source 104 is shown in the figure.

[0392] like Fig.25 As shown in FIG. 1 , the second absorber 103a prepared in the above-mentioned step S1 is arranged inside the reaction tank 102. Then, the second valve V2 is set to a closed state, the first valve V1 is set to an open state, and the atmosphere as the treatment target gas G1 is introduced into the reaction tank 102 via the introduction port 105b. The carbon dioxide contained in the treatment target gas G1 is absorbed by the second absorber 103a, and the first absorber 103b is obtained (step S2).

[0393] Next, step S3 is performed by heat source 104. Fig. 27 As shown in , the heat source 104 includes a heating tank 104a, a heat collecting member 115 disposed vertically above the heating tank 104a (on the +Z side), a heat transfer member 119 disposed directly on the heat collecting member 115, and a light-transmitting portion 120 for taking in sunlight C2. Fig.28 In the figure, for convenience of illustration, the light transmitting portion 120, the heat collecting member 115, and a part of the heat transfer member 119 are omitted. Since the heat source 104 has the same structure as the reaction tank 102 of the first embodiment, the description of the common parts is simplified.

[0394] like Fig. 27 As shown in , the atmosphere as the heat transfer medium A1 is introduced into the interior of the heating tank 104a via the inlet 105. Then, the heat transfer medium A1 contacts the heat transfer member 119 which has reached a high temperature by converting the sunlight C2 through the heat collecting member 115, and is heated. Thereafter, the heat transfer medium A1 is discharged from the discharge port 106 and sent to the reaction tank 102 via the first flow path 131. It should be noted that the same discussion as the first embodiment can be carried out for the light-transmitting portion 120.

[0395] From the viewpoint of increasing the contact area between the heat transfer member 119 and the heat transfer medium A1, the heat transfer member 119 may also be Fig.28As shown in , for example, it is composed of a plate-like member, and is arranged in such a way that its main surface becomes approximately perpendicular to the flow direction of the heat transfer medium A1. From the same point of view, it can also be set to the following structure: the flow portion 125 located between the inner wall of the heating tank 104a and the heat transfer member 119 in the Y direction and through which the heat transfer medium A1 passes overlaps with the main surface of the heat transfer member 119 located in the rear section in the flow direction of the heat transfer medium A1 when viewed along the X direction (flow direction). It should be noted that the so-called "main surface" here refers to the surface of the plate-like heat transfer member 119 that has a much larger area than other surfaces.

[0396] The atmosphere as the heat transfer medium A1 heated by the heat source 104 is as follows Fig.26 As shown in , the heat medium A1 is introduced into the reaction tank 102 where the first absorber 103b is located via the introduction port 105a. The introduction port 105a corresponds to the "introduction port". At this time, typically, the second valve V2 is set to an open state, and the first valve V1 is set to a closed state. In this way, the high-temperature heat transfer medium A1 contacts the first absorber 103b, and the heat H1 is supplied to the first absorber 103b (step S4).

[0397] The recovery gas G2 containing carbon dioxide desorbed from the first absorber 103b by the supply of the heat H1 is recovered through the discharge port 106a (step S5). That is, the discharge port 106a corresponds to a "recovery port".

[0398] It should be noted that in this embodiment, since the air is used as the heat transfer medium A1, the carbon dioxide concentration near the first absorber 103b can be reduced by introducing the heat transfer medium A1 into the reaction tank 102. That is, the air as the heat transfer medium A1 also functions as the desorption promoting gas B1 that promotes the desorption of carbon dioxide.

[0399] By heating the first absorber 103b using the atmosphere as the heat transfer medium A1, the absorbed carbon dioxide is desorbed. However, from the perspective of repeatedly utilizing the absorber 103 (see Fig.19), preferably reducing the thermal influence on the first absorber 103b. Therefore, the control unit 108 receives the temperature information d0 from the thermometer 109, and sends a signal d1 for adjusting the opening to the first valve V1 when the temperature in the reaction tank 102 is above a specified value. By adjusting the opening of the first valve V1, it is possible to introduce an atmosphere with a lower temperature than the heat transfer medium A1, so that the temperature in the reaction tank 102 can be lowered, reducing the thermal influence on the first absorber 103b. That is, the atmosphere in this case corresponds to a "cooling gas". In addition, from the viewpoint of promoting the cooling of the temperature in the reaction tank 102, a signal d2 can also be sent to the second valve V2 to adjust the opening of the second valve V2. It should be noted that the specified value can also be set to, for example, below 100°C, preferably below 80°C, and more preferably below 60°C.

[0400] It should be noted that, in the present embodiment, an example is described in which the control unit 108 adjusts the opening of each valve (V1, V2) based on the temperature information d0 from the thermometer 109 to reduce the temperature in the reaction tank 102 in step S4. However, the control unit 108 may also perform control to set the first valve V1 to the open state and the second valve V2 to the closed state for a predetermined time, for example, when the accumulated time that V2 is set to the open state reaches a preset time.

[0401] In this embodiment, the heat transfer medium A1 introduced into the reaction tank 102 is heated. However, as described with reference to FIG. 17 , a heat source 104 disposed in the reaction tank 102 and heating the heat transfer medium A1 and the first absorber 103 b may be used in combination.

[0402] [Other embodiments]

[0403] <1> Fig.29 and Fig.30 This is a diagram schematically showing the structure of another embodiment of the recovery system 101, and a part of the structure is shown as a block diagram. Fig.29 Corresponding to the scene of executing step S2, Fig.30 This corresponds to the scene where steps S4 and S5 are executed.

[0404] This embodiment includes a heat exchanger 136 (see Fig.30 ). In addition, the recovery system 101 has a fourth flow path 134 that branches from the third flow path 133 and through which the treatment target gas G1 flows after flowing through the reaction tank 102 (see Fig.29 ) and a fourth valve V4 disposed in the fourth flow path 134. It should be noted that the configuration of the reaction tank 102 and the heat source 104 can be similar to that described in reference to Figure 25 to Figure 28Same discussion as narrated.

[0405] like Fig.29 As shown in FIG. 1 , in the execution scene of step S2, the first valve V1 and the fourth valve V4 disposed in the second flow path 132 are set to an open state, and the treatment target gas G1 is introduced into the reaction tank 102 by a circulation mechanism such as a fan (not shown). In the reaction tank 102, the treatment target gas G1 after carbon dioxide is absorbed by the second absorber 103a is discharged to the outside space via the fourth flow path 134, for example.

[0406] like Fig.30 As shown in FIG. 1 , in the execution scene of step S4 and step S5, the second valve V2 disposed in the first flow path 131 through which the atmosphere as the heat transfer medium A1 flows and the third valve V3 disposed in the third flow path 133 through which the recovered gas G2 flows are set to an open state. Fig.30 As shown in , the atmosphere in the space where plants grow in the plant factory 135 (hereinafter, for convenience, referred to as "growth space 135a") is used as the heat transfer medium A1. Furthermore, the recovered gas G2 in the reaction tank 102 containing the carbon dioxide separated from the first absorber 103b can be used in the growth space 135a. Since the recovered gas G2 contains carbon dioxide separated by heating the first absorber 103b, it has a higher temperature than the atmosphere as the heat transfer medium A1. Therefore, it is preferred to perform heat exchange between the recovered gas G2 and the atmosphere as the heat transfer medium A1.

[0407] It should be noted that in the plant factory 135, it is assumed that the lighting for growth is turned on or off in accordance with the circadian rhythms inherent to the plants. That is, during the period when the lighting is turned on, the carbon dioxide concentration in the growth space 135a decreases due to the photosynthesis of the plants. Therefore, from the perspective of improving the effect of the above-mentioned separation-promoting gas B1, it is preferred to use the atmosphere in the growth space 135a as the heat transfer medium A1. It should be noted that in the case where the carbon dioxide concentration in the growth space 135a is high due to the respiration of the plants, etc. (typically during the period when the lighting for growth is turned off), the atmosphere of other spaces such as the outer space can also be used as the heat transfer medium A1.

[0408] <2> In the second embodiment described above, in step S4, it is assumed that the air as the heat transfer medium A1 is introduced into the internal space of the reaction tank 102. Fig.31 As shown in FIG. 1 , heat exchange may be performed between the heat transfer medium A1 flowing outside the reaction tank 102 and the reaction tank 102 inside which the first absorber 103 b is located. Fig.31 1 is a diagram schematically showing a part of another configuration example of the recovery system 101. Fig.32A It is a schematic representation Fig.31 A three-dimensional diagram of the structure of the heat source 104, Fig.32B Observed from the X direction Fig.32A The cross-sectional view of the heat source 104. It should be noted that Fig.32A and Fig.32B In the diagram, the flow direction of the heat transfer medium A1 is set to be the X direction.

[0409] Fig.32A The heat source 104 is, for example, Fig.32B As shown in , it has an L-shaped cross-sectional shape, and water as a heat transfer medium A1 is contained therein. The heat source 104 has a flat heat collecting member 115 in a portion of the outer wall surface, and the heat collecting member 115 is heated by absorbing sunlight C2 to generate high-temperature water (hereinafter referred to as "warm water"). Typically, in order to enable the heat collecting member 115 to effectively receive sunlight C2, the heat source 104 is arranged on an inclined surface such as a stand 141. The warm water is configured to flow in the flow path 140, and by exchanging heat between the warm water as the heat transfer medium A1 and the reaction tank 102, heat H1 can be supplied to the first absorber 103b in the reaction tank 102.

[0410] It should be noted that, at this time, from the viewpoint of reducing the carbon dioxide concentration in the reaction tank 102 and promoting the separation of the absorbed carbon dioxide from the first absorber 103b, for example, the atmosphere as the separation promoting gas B1 may be introduced into the reaction tank 102 from the second flow path 132 (see Fig.31 ).

[0411] <3> In addition, Fig.31 In the example described above, heat exchange is performed between warm water as the heat transfer medium A1 flowing through the flow path 140 and the reaction tank 102. However, the warm water may also be Fig.24 and Fig.26 The first flow path 131 is used to exchange heat with the air as the heat transfer medium A1. That is, the air heated to a high temperature by the heat exchange is introduced into the reaction tank 102, thereby supplying heat H1 to the first absorber 103b (see Fig.26 ) to complete the removal of the absorbed carbon dioxide.

[0412] <4> The above-mentioned embodiments can be implemented by appropriate combination. Fig.24 or Fig.31 A heat source 104 is additionally arranged inside the reaction tank 102. As the structure of the reaction tank 102, for example, the structure described with reference to FIG. 17 can be used.

[0413] <5> In the above description, the case where the absorber 103 is in a granular shape has been described. However, as described above, the shape of the absorber 103 is not limited thereto, and may be in a plate shape, for example.

[0414] <6> In the above description, the absorber 103 is described as being in a solid state. However, a liquid carbon dioxide absorbing liquid may be used as the absorber 103 . Fig.33 It is imitation Fig. 17B The accompanying drawings schematically show other embodiments of the recycling system 101. Fig.33 As shown in , by directly arranging the heat transfer member 119 that reaches a high temperature through the heat H1 of the heat collecting member 115 with respect to the liquid absorber 103, the heat H1 can be supplied to the absorber 103. It should be noted that when the liquid absorber 103 absorbs carbon dioxide (step S2), the treatment target gas G1 such as the atmosphere may be introduced from the inlet 105 to bubble the absorber 103.

[0415] Explanation of symbols

[0416] 1: Recycling system

[0417] 2: Absorption tank

[0418] 3, 33, 43, 53, 63, 73, 83, 89: reaction tank

[0419] 4, 5, 52, 78, 92, 93: flow path

[0420] 6, 36, 46, 56, 66, 76, 86: light source

[0421] 7, 47, 57, 77: Recycling ports

[0422] 8,38: LED components

[0423] 9: Substrate

[0424] 10,30: Absorption liquid

[0425] 11: Reflective film

[0426] 12, 14: Window

[0427] 13: Heat transfer components

[0428] 15, 16: Heat collecting components

[0429] 16a, 167a, 167b: End

[0430] 20: Gas to be treated

[0431] 21: Treated gas

[0432] 22: Out of Gas

[0433] 34: Stopper

[0434] 35a, 35b: Syringe

[0435] 37: Power supply

[0436] 39: Thermocouple

[0437] 40: Shade

[0438] 41: Power supply components

[0439] 44, 54: Import port

[0440] 45, 55: Exhaust port

[0441] 58: Upper wall

[0442] 59: Bottom wall

[0443] 60: Out of Space

[0444] 68: Heat Source

[0445] 74: Inlet

[0446] 79a, 79b, 79c: valve

[0447] 84: Concave

[0448] 87: Set up the platform

[0449] 87a: Inclined surface

[0450] 90: Warm water generator

[0451] 91: Heat exchanger

[0452] 94: Roof

[0453] 95: Warm water

[0454] 101: Recycling System

[0455] 101a: Recycling Methods

[0456] 102: Reaction tank

[0457] 103: Absorber

[0458] 103a: Second absorber

[0459] 103b: First absorber

[0460] 104: Heat Source

[0461] 104a: Heating tank

[0462] 105, 105a, 105b: Inlet

[0463] 106, 106a: Exhaust port

[0464] 108: Control Department

[0465] 109: Thermometer

[0466] 110: Base material

[0467] 111: Pores

[0468] 112: Carbon dioxide absorption liquid

[0469] 115: Solar heat concentrating components

[0470] 119: Heat transfer components

[0471] 120: light-transmitting part

[0472] 121: Transparent component

[0473] 122: Low pressure space

[0474] 125: Circulation Department

[0475] 130: Halogen lamp

[0476] 131, 132, 133, 134, 140: Flow path

[0477] 135: Plant Factory

[0478] 135a: Growing Space

[0479] 136: Heat exchanger

[0480] 141: Stand

[0481] 161: Outer tube

[0482] 162: Inner tube

[0483] 163: Sealing part

[0484] 164: Sealed Space

[0485] 165: Heat Collection Department

[0486] 166: Heat transfer sheet

[0487] 167: Heat pipe

[0488] 168: Working fluid

[0489] 169: Sealed Section

[0490] A1: Heat transfer medium

[0491] B1: Detachment promoting gas

[0492] C1: Sun

[0493] C2: Sunlight

[0494] G1: Processing target gas

[0495] G2: Recycled Gas

Claims

1. A method for recovering carbon dioxide, characterized in that: It includes: (a) irradiating the absorbing liquid that has absorbed carbon dioxide with light; (b) a step of supplying heat to the absorption liquid; and a step (c) of recovering the carbon dioxide desorbed from the absorbing liquid through the steps (a) and (b).

2. The method for recovering carbon dioxide according to claim 1, characterized in that: The step (a) is a step of irradiating the absorbing liquid with the light from a light source, The step (b) is a step of supplying the heat generated by the light source to the absorbing liquid.

3. The method for recovering carbon dioxide according to claim 2, characterized in that: The step (a) and the step (b) are performed simultaneously.

4. The method for recovering carbon dioxide according to claim 1, characterized in that: The step (a) includes irradiating the absorbing liquid with the light from a light source, In the scheme capable of irradiating sunlight, the step (b) includes the following step: a solar heat collecting member is arranged in a state of being in contact with a reaction tank where the absorbing liquid is located directly or through other members, converts the sunlight into the heat and supplies the heat to the absorbing liquid.

5. The method for recovering carbon dioxide according to claim 1 or 2, characterized in that: The absorbing liquid includes a carbon dioxide absorbing material formed of an alkaline material and a solvent.

6. The method for recovering carbon dioxide according to claim 5, characterized in that: The carbon dioxide absorber is formed of an amine material.

7. A carbon dioxide recovery system, characterized in that: It has: The absorption liquid that has absorbed the carbon dioxide is located in the internal reaction tank; a light source, which is disposed in a state of being fixed to the reaction tank directly or via another member, and irradiates light to the absorption liquid in the reaction tank; A recovery port for recovering carbon dioxide separated from the absorbent.

8. The carbon dioxide recovery system according to claim 7, characterized in that: The light source is disposed inside the reaction tank.

9. The carbon dioxide recovery system according to claim 7 or 8, characterized in that: It has: an inlet for introducing the absorption liquid into the reaction tank; and a discharge port for discharging the absorption liquid after being irradiated with the light from the light source, The absorbing liquid flowing from the introduction port toward the discharge port is located in the reaction tank.

10. The carbon dioxide recovery system according to claim 9, characterized in that: The recovery port is located on a side closer to the discharge port than the introduction port with respect to the flow direction of the absorption liquid.

11. The carbon dioxide recovery system according to claim 9, characterized in that: The reaction tank includes a bottom wall portion and an upper wall portion vertically separated from the bottom wall portion. The reaction tank has a structure in which a vertical distance between the bottom wall portion and the upper wall portion increases as the distance from the introduction port to the discharge port increases.

12. The carbon dioxide recovery system according to claim 11, characterized in that: The light source is fixedly arranged relative to the bottom wall portion, The upper wall portion is inclined relative to the bottom wall portion, The recovery port is provided on the upper wall portion on a side closer to the discharge port than the introduction port.

13. The carbon dioxide recovery system according to claim 7 or 8, characterized in that: The absorbing liquid includes a carbon dioxide absorbing material formed of an alkaline material and a solvent.

14. The carbon dioxide recovery system according to claim 13, characterized in that: The carbon dioxide absorber is formed of an amine material.

15. A carbon dioxide recovery system, characterized in that: It has: The absorption liquid that has absorbed the carbon dioxide is located in the internal reaction tank; a light source for irradiating light to the absorption liquid in the reaction tank; a heat source for supplying heat to the absorbent in the reaction tank; and A recovery port for recovering carbon dioxide separated from the absorbent.

16. The carbon dioxide recovery system according to claim 15, characterized in that: In an embodiment capable of irradiating sunlight, the heat source includes a solar heat collecting member that is disposed directly or fixedly to the reaction tank via another member and converts received sunlight into heat.

17. A method for recovering carbon dioxide, characterized in that: It has the following steps: A step (d) of preparing an absorber for absorbing carbon dioxide, namely, a first absorber; (e) a step of converting the sunlight received by the solar heat concentrating member into heat; (f) supplying thermal energy derived from the heat obtained in the step (e) to the first absorber; and and a step (g) of recovering the carbon dioxide desorbed from the first absorber in the step (f).

18. The method for recovering carbon dioxide according to claim 17, characterized in that: The step (f) is a step of supplying the thermal energy to the first absorber via the heat transfer medium heated by the heat obtained in the step (e).

19. The method for recovering carbon dioxide according to claim 18, characterized in that: The step (f) includes the step of introducing the heat transfer medium into the internal space of the reaction tank in which the first absorber is arranged, the heat transfer medium being formed of air heated by the thermal energy obtained in the step (e).

20. The method for recovering carbon dioxide according to claim 19, characterized in that: During the step (f), the temperature of the internal space of the reaction vessel is measured, and when the temperature is equal to or higher than a predetermined value, a cooling gas consisting of air having a lower temperature than the heat transfer medium is introduced into the internal space.

21. The method for recovering carbon dioxide according to claim 19 or 20, characterized in that: The step (d) comprises: a step (d1) of preparing an absorber before absorbing carbon dioxide, namely, a second absorber; and After the second absorber is disposed in the reaction tank, a process (d2) is performed in which a treatment target gas including carbon dioxide is introduced into the internal space of the reaction tank to allow the second absorber to absorb the carbon dioxide.

22. The method for recovering carbon dioxide according to claim 21, characterized in that: The step (d1) includes the step of obtaining the second absorber by supporting a carbon dioxide absorbing liquid made of a basic material and having carbon dioxide absorbing properties in the pores of a solid material made of a porous substance having pores on the surface.

23. The method for recovering carbon dioxide according to claim 22, characterized in that: The step (d1) includes blowing plasma gas or irradiating ultraviolet rays to the pores before causing the carbon dioxide absorbing liquid to be supported on the pores of the solid material.

24. The method for recovering carbon dioxide according to claim 18, characterized in that: The step (f) is a step of performing heat exchange between the heat transfer medium flowing outside the reaction tank in which the first absorber is arranged and the first absorber. During the step (f), a desorption promoting gas composed of a gas having a carbon dioxide concentration lower than that in the internal space is introduced into the internal space of the reaction vessel.

25. A carbon dioxide recovery system, characterized in that: It has: The absorber that completes the absorption of carbon dioxide is the first absorber; The first absorber is located in the inner reaction tank; introducing a heat transfer medium for supplying heat energy to the first absorber into an introduction port inside the reaction tank; a heat source including a solar heat collecting member that converts received sunlight into heat, and is disposed in front of the first absorber in the flow direction of the heat transfer medium to heat the heat transfer medium; and A recovery port for recovering carbon dioxide separated from the first absorber.

26. The carbon dioxide recovery system according to claim 25, characterized in that: It has a first flow path connecting the heat source and the introduction port, The heat source is configured to heat the heat transfer medium flowing through the first flow path at a position outside the reaction tank.

27. The carbon dioxide recovery system according to claim 26, characterized in that: It has: A second flow path for introducing atmospheric air as a treatment target gas including carbon dioxide into the interior of the reaction tank; and A first valve is configured to adjust the opening degree of the second flow passage to control the flow rate of the atmospheric air flowing through the second flow passage.

28. The carbon dioxide recovery system according to claim 27, characterized in that: It is equipped with a thermometer for measuring the temperature of the internal space of the reaction tank. The first valve adjusts the opening degree of the second flow path based on the measurement value of the thermometer.

29. The carbon dioxide recovery system according to claim 27, characterized in that: The heat transfer medium is provided with a second valve capable of adjusting the opening of the first flow path to control the flow rate of the heat transfer medium flowing through the first flow path.

30. The carbon dioxide recovery system according to any one of claims 25 to 29, characterized in that: It has: a third flow path through which a recovered gas including carbon dioxide recovered from the recovery port flows; and A heat exchanger is disposed at a stage ahead of the first absorber in the flow direction of the heat medium, and performs heat exchange between the heat medium and the recovery gas flowing through the third flow path.

31. The carbon dioxide recovery system according to any one of claims 25 to 29, characterized in that: The absorbent is in a solid state.

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