WO2023243328A1

WO2023243328A1 - Carbon dioxide recovering method and carbon dioxide recovering system

Info

Publication number: WO2023243328A1
Application number: PCT/JP2023/019110
Authority: WO
Inventors: 貴紀鮫島; 正人大岩; 優一大塚; 知典原田
Original assignee: ウシオ電機株式会社
Priority date: 2022-06-17
Filing date: 2023-05-23
Publication date: 2023-12-21

Abstract

Provided are: a method for recovering absorbed carbon dioxide, whereby it becomes possible to detach absorbed carbon dioxide from an absorbent material with a smaller energy; and a system suitable for the employment of the method.　The method for recovering absorbed carbon dioxide comprises: a step (a) for irradiating an absorption solution in which carbon dioxide has been absorbed with light; a step (b) for supplying heat to the absorption solution; and a step (c) for recovering carbon dioxide detached from the absorption solution through the steps (a) and (b).

Description

Carbon dioxide recovery method and carbon dioxide recovery system

The present invention relates to a method for desorbing and recovering carbon dioxide that has been absorbed (already absorbed) in an absorption liquid, and a system suitable for using the method. The present invention also relates to a method of recovering carbon dioxide via an absorber exhibiting carbon dioxide absorbability, and a system suitable for using the method.

In recent years, in order to reduce the concentration of carbon dioxide in the atmosphere, technologies that directly absorb carbon dioxide from the atmosphere or separate and recover carbon dioxide contained in fossil fuel combustion exhaust gas, etc., have been studied.

In the recovery of carbon dioxide, a method has been proposed in which carbon dioxide is absorbed into an absorbent material and the absorbed carbon dioxide is desorbed from the absorbent material. For example, Patent Document 1 below describes a method of separating carbon dioxide from combustion exhaust gas using a solution containing amine as an absorbent, and then heating the solution to desorb and recover carbon dioxide. is listed.

Japanese Patent Application Publication No. 5-245339

In this way, input of energy such as heating is required to desorb absorbed carbon dioxide from the carbon dioxide absorbing material. The greater the energy for this desorption, the greater the cost of carbon dioxide capture. After absorbing carbon dioxide with an absorbent material, unless the carbon dioxide absorbed by the absorbent material can be desorbed with low energy, it will be difficult to comprehensively reduce the amount of carbon dioxide emissions. For example, if a large amount of power is consumed to desorb carbon dioxide, carbon dioxide must be released in order to generate this power. Problems may also arise in handling the absorbent material after the carbon dioxide has been absorbed.

On the other hand, as mentioned above, if high energy is required to desorb and recover carbon dioxide from an absorbent material that has already absorbed carbon dioxide, there is a concern about running costs associated with operating the system. This point is an impediment to the introduction and widespread use of carbon dioxide capture systems. At present, the problem of global warming is considered to be one of the problems that must be solved worldwide. It is an urgent issue to reduce emissions of carbon dioxide, which is considered one of the main causes of global warming, and to reduce the concentration of carbon dioxide in the atmosphere.

Based on the above, it is important to realize a system that can desorb and recover carbon dioxide from the absorbent material at low cost and with low energy after absorbing it with the absorbent material. This is thought to be important in promoting movements that reduce

In view of the above circumstances, it is an object of the present invention to provide a carbon dioxide recovery method and system that can desorb absorbed carbon dioxide from an absorbent material with less energy.

The carbon dioxide recovery method according to the present invention includes:
a step (a) of irradiating light onto the absorption liquid in which carbon dioxide has been absorbed;
(b) supplying heat to the absorption liquid;
The method is characterized by including a step (c) of recovering carbon dioxide desorbed from the absorption liquid through the step (a) and the step (b).

Details will be described later, but as a result of extensive research, the present inventors have found that by irradiating light onto an absorption liquid in which carbon dioxide has been absorbed, the desorption of absorbed carbon dioxide from the absorption liquid increases. I discovered that. In other words, by supplying heat to the absorption liquid and irradiating it with light, the absorbed carbon dioxide is desorbed while reducing the amount of thermal energy applied compared to the case of simply applying heat. be able to. Furthermore, by reducing the applied thermal energy, carbon dioxide can be desorbed at a lower temperature than the temperature of the absorption liquid conventionally required for desorption of carbon dioxide. Furthermore, if the thermal energy applied to the absorption liquid is the same as in the past, more carbon dioxide can be desorbed by irradiation with light.

When supplying heat to raise the temperature of the absorption liquid in order to desorb absorbed carbon dioxide, it is necessary to heat the entire solution containing the carbon dioxide absorbing material. On the other hand, when irradiating the absorption liquid with light, a wavelength that is easily absorbed by the carbon dioxide absorbing material can be selected. That is, by irradiating light, energy can be selectively given to the carbon dioxide absorbing material. Therefore, by supplying the energy to desorb carbon dioxide through heat and light irradiation, it is possible to desorb carbon dioxide that has already been absorbed from the absorption liquid with less energy than when simply applying heat. can.

In this specification, "recovery" means to transfer the carbon dioxide desorbed from the absorbent liquid or absorber from the area where the absorbent liquid or absorber is placed to another area. For example, carbon dioxide may be stored in a storage tank such as a cylinder, or may be sent to a carbon dioxide utilization facility via piping. Examples of the utilization facility include a plant factory and the like.

The step (a) is a step of irradiating the absorption liquid with the light from a light source,
The step (b) may be a step of supplying the heat generated by the light source to the absorption liquid.

Since the light source emits heat when emitting light, energy can be used efficiently by supplying the heat emitted by the light source to the absorbing liquid when irradiating the absorbing liquid with light. Therefore, absorbed carbon dioxide can be desorbed from the absorption liquid with even less energy.

The step (a) and the step (b) may be performed simultaneously.

Further, the step (a) includes a step of irradiating the absorption liquid with the light from a light source,
In the step (b), a solar heat collecting member is placed in a state where sunlight can be irradiated, and the solar heat collecting member is placed in contact with the reaction tank in which the absorption liquid is located, either directly or through another member. , the method may include a step of converting the sunlight into the heat and supplying the heat to the absorption liquid.

Although the details will be described later, by using the energy of sunlight to supply heat to the absorption liquid, the absorbed carbon dioxide can be desorbed from the absorption liquid with less energy.

The absorption liquid may include a carbon dioxide absorbent made of a basic material and a solvent.

The carbon dioxide absorbing material may be an amine-based material. The 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 it can be used alone or as a mixture.

Examples of amine compounds that can be included in the amine-based material include primary amines such as monoethanolamine, 2-amino-2-methyl-1-propanol, and phenylethylamine, diethanolamine, 2-methylaminoethanol, and 2-methylaminoethanol. Secondary amines such as ethylaminoethanol, diamines such as ethylenediamine, N,N-dimethylethylenediamine, ortho-xylylenediamine, meta-xylylenediamine, para-xylylenediamine, triamines such as diethylenetriamine, benzylamine, Examples include benzylamines such as para-methoxybenzylamine and para-trifluoromethylbenzylamine.

A carbon dioxide absorption liquid can be prepared by dispersing a carbon dioxide absorbent in a solvent such as water or dimethyl sulfoxide (DMSO). Furthermore, alcohol such as ethanol may be used as the solvent. A plurality of these solvents may be used in combination.

Hereinafter, absorption and desorption of carbon dioxide will be explained using an aqueous solution of an amine material (R ¹ R ² NH) as an example. Here, R ¹ represents an alkyl group, a cycloalkyl group, an aryl group, or a monovalent heterocyclic group. Further, R 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.

The following formulas (1) to (3) mainly exist as reactions in which an amine-based material absorbs carbon dioxide.
R ¹ R ² NH + CO ₂ + H ₂ O → R ¹ R ² NH ₂ ⁺ + HCO ₃ ^-・・・・・・(1)
2(R ¹ R ² NH) aq + CO ₂ → R ¹ R ² NH ₂ ⁺ + R ¹ R ² NCOO ^-・・・(2)
R ¹ R ² NH + CO ₂ → R ¹ R ² NCOOH (3)

Furthermore, when the solvent is water, it is assumed that hydroxide ions (OH ^- ) are present on the surface of the liquid phase, so the absorption reaction of the following formula (4) is also assumed.
CO ₂ + OH ^- → HCO ₃ ^-... (4)

Note that, although not limited to the above formula (4), when the solution absorbs carbon dioxide, the area where the gas phase containing carbon dioxide and the liquid phase of the solution come into contact (also referred to as "gas-liquid contact") is large. is preferred. For example, in equation (4), if the area of gas-liquid contact is large, hydroxide ions near the surface of the liquid phase can easily contribute to the reaction, which is preferable. Further, from the viewpoint of increasing hydroxide ions, the solution is preferably a strong alkali. Here, "the solution is strongly alkaline" means that the pH of the solution is 10 or more.

In other words, carbon dioxide exists in the absorption liquid in the form of bicarbonate ions (HCO ₃ ^- ), carbamate ions (R ¹ R ² NCOO ^- ), or carbamate ions (R ¹ R ² NCOOH), and these are mixed. ing.

Energy is applied to the absorption liquid that has absorbed carbon dioxide in this way by heat supply and light irradiation, and by causing the reverse reactions of equations (1) to (4), the absorbed carbon dioxide can be desorbed. can.

The absorption and desorption of carbon dioxide was explained using amine-based materials as an example. On the other hand, other carbon dioxide absorbing materials are also known, such as basic imines containing amines, oxides containing alkali metals, and oxides containing niobium or tantalum.

The same argument as above can be made as long as the carbon dioxide absorbent material absorbs carbon dioxide and then causes a carbon dioxide desorption reaction by absorbing light. In other words, the carbon dioxide absorbent is not limited to amine-based materials.

The carbon dioxide recovery system according to the present invention includes:
a reaction tank in which an absorption liquid in which carbon dioxide has been absorbed is located;
a light source that is fixed to the reaction tank directly or via another member and irradiates the absorption liquid in the reaction tank with light;
It is characterized by comprising a recovery port for recovering carbon dioxide desorbed from the absorption liquid.

Regarding the point of desorbing absorbed carbon dioxide from the absorption liquid, the same discussion as the above-mentioned recovery method can be made. Here, a light source that emits light for desorbing absorbed carbon dioxide is fixed to the reaction tank directly or through another member, so that the heat emitted by the light source is transferred to the absorption liquid in the reaction tank. can be supplied. In this case, since the energy for desorption can be used efficiently, the absorbed carbon dioxide can be desorbed from the absorption liquid with less energy.

The light source may be placed inside the reaction tank.

By disposing the light source inside the reaction tank, the heat generated by the light source can be efficiently supplied to the absorption liquid in the reaction tank. Therefore, it becomes possible to desorb the absorbed carbon dioxide from the absorption liquid with less energy.

The carbon dioxide recovery system includes:
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 absorption liquid flowing from the introduction port toward the discharge port may be located in the reaction tank.

Desorption of absorbed carbon dioxide may be performed while flowing the absorption liquid. By desorbing the absorbed carbon dioxide while flowing the absorbing liquid, it becomes possible, for example, to send the desorbed absorbing liquid as it is to the carbon dioxide absorption system (absorption tank). In this case, the absorption liquid from which carbon dioxide has been desorbed can be used continuously for carbon dioxide absorption.

The recovery port may be located closer to the outlet than the inlet with respect to the flow direction of the absorption liquid.

When desorbing carbon dioxide while flowing the absorption liquid, the absorption liquid is introduced into the reaction tank, and then light irradiation is started. Thereafter, the absorption liquid is continuously irradiated with light while flowing toward the discharge port. Here, in order to focus on the absorbent liquid at a specific location, we assume that the absorbent liquid is surrounded by a virtual container that has zero resistance to flow, resistance to heat, and shielding effect against light, and absorbs the entire virtual container. Assume a situation where the liquid flows along the flow. The absorption liquid in this virtual container is irradiated with light while flowing toward the discharge port. In other words, the amount of light irradiated (irradiation dose) increases as the absorption liquid in this virtual container approaches the discharge port from the inlet. Similarly, the absorbent liquid is heated by the heat emitted by the light source, and the temperature of the absorbent liquid increases as it approaches the outlet from the inlet. As a result, the equilibrium conditions shift in a direction in which the amount of carbon dioxide desorbed increases, and the amount of desorbed carbon dioxide also increases as it approaches the outlet.

Based on the above, even when looking at the entire absorption liquid flowing into the reaction tank, it is assumed that the desorption of carbon dioxide is greater on the side closer to the outlet than on the side closer to the inlet. . Therefore, by arranging the carbon dioxide recovery port on the side closer to the exhaust port, carbon dioxide can be efficiently recovered.

In the carbon dioxide recovery system,
The reaction tank has a bottom wall portion and an upper wall portion vertically spaced apart from the bottom wall portion,
The reaction tank may have a structure in which the distance between the bottom wall portion and the top wall portion in the vertical direction increases as the distance from the inlet port approaches the discharge port.

As mentioned above, it is assumed that the desorption of carbon dioxide is greater on the side closer to the outlet than on the side closer to the inlet. According to the above configuration, the distance between the bottom wall and the top wall increases as you get closer to the discharge port, so there is a space in the reaction tank in which the carbon dioxide desorbed from the absorption liquid is temporarily located. We can secure enough. Therefore, with this configuration, a large amount of carbon dioxide can be efficiently recovered by providing a recovery port so as to penetrate, for example, the upper wall portion on the side closer to the exhaust port.

Further, the light source is fixedly arranged with respect to the bottom wall,
The top wall part is inclined with respect to the bottom wall part,
The recovery port may be provided in the upper wall portion closer to the outlet than the inlet.

According to the above configuration, the carbon dioxide desorbed from the absorption liquid is guided to the side closer to the discharge port by the slope of the upper wall. Furthermore, by arranging the recovery port on the side closer to the exhaust port, carbon dioxide can be efficiently recovered.

The carbon dioxide absorbing material may be an amine-based material.

Regarding the carbon dioxide absorbent and solvent, the discussion is the same as above.

Furthermore, the carbon dioxide recovery system according to the present invention includes:
a reaction tank in which an absorption liquid in which carbon dioxide has been absorbed is located;
a light source that irradiates light to the absorption liquid in the reaction tank;
a heat source that supplies heat to the absorption liquid in the reaction tank;
Another feature is that it includes a recovery port that recovers carbon dioxide desorbed from the absorption liquid.

By supplying heat from a heat source to the absorption liquid and irradiating it with light from a light source, carbon dioxide can be efficiently removed from the absorption liquid while reducing the amount of heat energy applied compared to conventional methods. It can be detached.

Note that the heat source may be arranged as a separate device from the light source, or the light source may also serve as the heat source.

The heat source may include a solar heat collecting member that is fixed to the reaction tank directly or via another member in such a manner that sunlight can be irradiated thereon.

According to the above configuration, the solar heat collecting member that supplies heat to the absorption liquid is heated by sunlight. Since sunlight is used, heat can be supplied to the absorption liquid with less energy, and absorbed carbon dioxide can be desorbed suitably.

The carbon dioxide recovery method according to the present invention includes:
a step (d) of preparing a first absorber which is an absorber that has already absorbed carbon dioxide;
a step (e) of converting sunlight received by the solar heat collecting member into heat;
a step (f) of supplying thermal energy derived from the heat obtained in the step (e) to the first absorber;
Another feature is that the method further comprises a step (g) of recovering the carbon dioxide desorbed from the first absorber through the step (f).

As used herein, the term "first absorber" refers to a state in which an absorber exhibiting carbon dioxide absorbing properties has absorbed carbon dioxide. In addition, the "second absorber" described below refers to the state before the absorber exhibiting carbon dioxide absorbability absorbs carbon dioxide. Note that the second absorber also includes a state in which the absorber absorbs carbon dioxide and becomes the first absorber, and then receives supply of thermal energy and desorbs the carbon dioxide.

As mentioned above, in order to desorb carbon dioxide from the first absorber that has already absorbed the carbon dioxide, it is necessary to supply thermal energy to the first absorber. In other words, in order to reduce the energy required to recover carbon dioxide, it is important to reduce the energy consumed in supplying this thermal energy. In view of this, in the above-mentioned recovery method, thermal energy derived from the heat is supplied to the first absorber using a solar heat collecting member that converts received sunlight into heat. By using heat derived from sunlight for supplying thermal energy, it is possible to reduce the energy consumed in supplying the thermal energy. Note that specific embodiments will be described later in "Detailed Description of the Invention".

Note that from the viewpoint of reducing the energy required for heating, a method in which a heater for heating and the like is driven by a so-called solar power generation system is also envisaged. However, currently, in solar power generation systems, there is a problem with the wavelength range of light that can be used by solar panels that absorb sunlight. In particular, infrared rays account for more than half of sunlight, but solar panels only use visible light and some ultraviolet rays. In addition, this method cannot be said to be able to effectively utilize sunlight because of the influence of the conversion efficiency of solar panels and the thermal efficiency of input power of heaters and the like. On the other hand, as will be explained later, in the above collection method, infrared rays in particular can be effectively used, so the usable wavelength range of light is wide-ranging, and compared to, for example, a solar power generation system, it is possible to use sunlight more efficiently. Available.

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).

According to the above method, by using a heat transfer medium, regardless of the position of the first absorber with respect to the solar heat collecting member, for example, the heat converted from sunlight by the solar heat collecting member is transferred to the first absorber. can be efficiently supplied.

Further, in the step (f), the heat transfer medium made of the atmosphere heated by the thermal energy obtained in the step (e) is added to the internal space of the reaction tank in which the first absorber is disposed. It may also include a step of introducing.

By bringing the atmosphere heated by heat derived from sunlight into contact with the first absorber, thermal energy can be supplied to the first absorber. The first absorber receives heat from the atmosphere and desorbs the absorbed carbon dioxide.

Incidentally, near the first absorber where the carbon dioxide desorption reaction progresses, the carbon dioxide concentration locally increases. In order to efficiently advance the carbon dioxide desorption reaction, it is preferable to lower the carbon dioxide concentration near the first absorber. This is to make it easier for the reaction system to proceed to the production side by lowering the carbon dioxide concentration in the production (desorption) side system in the carbon dioxide desorption reaction. The carbon dioxide concentration in the atmosphere is about 400 ppm, which is lower than the space near the first absorber where the carbon dioxide desorption reaction progresses. Therefore, by introducing the atmosphere into the internal space of the reaction tank as a heat transfer medium, it is possible to simultaneously supply heat and lower the carbon dioxide concentration in the vicinity of the first absorber. It is possible to eliminate carbon. In other words, the heated atmosphere not only functions as a heat transfer medium but also as a desorption-promoting gas that promotes desorption of carbon dioxide.

The step (f) is a step of exchanging heat between the first absorber and the heat transfer medium flowing through the outside of the reaction tank in which the first absorber is disposed,
During execution of the step (f), a desorption-promoting gas consisting of a gas having a lower carbon dioxide concentration than the interior space may be introduced into the interior space of the reaction tank.

The heat transfer medium may exchange heat with the first absorber by flowing through the outside of the reaction tank. Through the heat exchange, heat is supplied to the first absorber, and absorbed carbon dioxide is desorbed from the first absorber. In this case, a fluid such as air or water can be used as the heat transfer medium.

Note that at this time, as mentioned above, from the viewpoint of efficiently proceeding with the carbon dioxide desorption reaction, it is preferable to introduce a desorption-promoting gas with a low carbon dioxide concentration into the internal space of the reaction tank. Nitrogen gas or the atmosphere can be used as the desorption promoting gas. In addition. Atmospheric air is preferable from the viewpoint of energy and cost required for procurement.

During execution of the step (f), the temperature of the internal space of the reaction tank is measured, and if the temperature is equal to or higher than a predetermined value, an atmosphere that is lower temperature than the heat transfer medium is applied to the internal space. It is also possible to introduce a cooling gas consisting of:

As mentioned above, absorbed carbon dioxide can be recovered by supplying heat to the first absorber. At this time, the temperature of the internal space of the reaction tank where the first absorber is placed is measured, and if this temperature is above a predetermined value, the first absorber is Preferably, the body is cooled. Here, the predetermined value is a value determined in consideration of heat resistance such as the boiling point of the carbon dioxide absorbent that constitutes the first absorber. According to the above method, even when the first absorber reaches a high temperature, the thermal influence on the carbon dioxide absorbing material constituting the first absorber can be reduced.

The step (d) includes:
a step (d1) of preparing a second absorber, which is an absorber before absorbing carbon dioxide;
After arranging the second absorber inside the reaction tank, a step (d2) of introducing a gas to be treated containing carbon dioxide into the internal space of the reaction tank and causing the second absorber to absorb carbon dioxide. It may also include.

The second absorber absorbs carbon dioxide contained in the gas to be treated in the reaction tank and becomes the first absorber (absorption step). Here, if the process of desorbing the absorbed carbon dioxide from the first absorber is performed in a place different from the reaction tank where the absorption process was performed, the energy required to transport the first absorber is Is required. On the other hand, according to the above method, since the absorption step and the desorption step are performed in the same reaction tank, the energy required for transporting the first absorber, etc. is suppressed, which is preferable.

Further, in step (d1), the pores of a solid material made of a porous material having pores on its surface are supported with a carbon dioxide absorbing liquid made of a basic material and exhibiting carbon dioxide absorption properties. , the method may include a step of obtaining the second absorbent body.

In this specification, "pore" refers to a fine pore with a diameter of several nanometers to several tens of micrometers, and "porous material" refers to a material that has countless pores on its surface.

By supporting a carbon dioxide absorption liquid in the pores of a porous substance, it can be used as a carbon dioxide absorber. In addition, by supporting the carbon dioxide absorption liquid in the pores, it is possible to increase the area in which the carbon dioxide contained in the gas to be treated and the carbon dioxide absorption liquid come in contact with each other, allowing efficient absorption of carbon dioxide. It will be done. The specific surface area of the porous substance is preferably 10 m ² /g or more, more preferably 50 m ² /g or more. Note that the specific surface area of the porous substance can be measured, for example, by a method according to JIS Z 8830 (method for measuring the specific surface area of powder (solid) by gas adsorption).

Materials that can be used as porous substances include ceramic materials such as silica, alumina, and zirconia, engineering plastic materials such as polypropylene, polyacetal, polyamide, and polycarbonate, and carbon materials such as activated carbon. Note that the shape of the porous substance is not particularly limited. Examples of the shape of the porous material include granules, plates, tubes, honeycombs, and pellets.

The carbon dioxide absorbing liquid is prepared by dispersing a carbon dioxide absorbing material such as an amine-based material exhibiting carbon dioxide absorbing property in a solvent such as water, polyethylene glycol (PEG), or dimethyl sulfoxide (DMSO). A plurality of these solvents may be used in combination. In addition, in order to reduce the viscosity of the carbon dioxide absorption liquid and make it easier for the carbon dioxide absorption liquid to enter the pores, alcohol such as methanol is added to the carbon dioxide absorption liquid and impregnated into the porous substance. The alcohol may be evaporated later.

In terms of thermal energy supplied during desorption of carbon dioxide, it is preferable that the concentration of the carbon dioxide absorption liquid is high from the viewpoint of reducing the energy consumed to raise the temperature of the solvent and increasing the utilization efficiency of thermal energy. On the other hand, for example, when using a carbon dioxide absorption liquid as it is as an absorber, increasing the concentration of the carbon dioxide absorption liquid increases the viscosity and makes handling difficult. There are certain restrictions. In particular, in the case of highly viscous materials, the concentration of the carbon dioxide absorption liquid will be approximately 1% to 10%. On the other hand, by supporting the carbon dioxide absorption liquid on a solid material, even when the concentration of the carbon dioxide absorption liquid is high (for example, several tens of percent), it can be easily handled. In other words, by using a solid absorber, the concentration of the carbon dioxide absorption liquid can be increased, and as a result, the efficiency of thermal energy utilization can be increased. Preparation of the absorbent body is detailed in the "Detailed Description" section.

The above-mentioned amine-based materials can be used as the carbon dioxide absorbent. In addition, when water is not selected as the solvent of the carbon dioxide absorbent, the reaction of the above formula (3) becomes the main reaction.

The same argument as above can be made as long as the carbon dioxide absorbent absorbs carbon dioxide and then causes a carbon dioxide desorption reaction by supplying heat. In other words, the carbon dioxide absorbent is not limited to amine-based materials. Other carbon dioxide absorbers include, for example, oxides exhibiting basicity, typically containing alkali metals, niobium or tantalum.

Further, the step (d1) may include a step of spraying plasma gas or irradiating ultraviolet rays onto the pores before the carbon dioxide absorption liquid is supported in the pores of the solid material. do not have.

According to the above method, the wettability of the pore surface to the carbon dioxide absorbing liquid is improved, and the carbon dioxide absorbing liquid can be more suitably supported on the pores. More specifically, when plasma gas is sprayed onto the pores, nitrogen molecules or oxygen molecules in the atmosphere are turned into plasma, and the activated species turned into plasma form hydrophilic functional groups (hydroxyl groups) on the surface of the pores. , carbonyl group or carboxy group). When irradiated with ultraviolet rays, radicals (mainly oxygen radicals in the atmosphere) are generated in the atmosphere. Furthermore, at the same time, the bonds between molecules constituting the pore surface are cut by ultraviolet irradiation, and as a result of radicals reacting with the cut portions, hydrophilic functional groups are formed on the pore surface.

The carbon dioxide recovery system according to the present invention includes:
a first absorber which is an absorber that has already absorbed carbon dioxide;
a reaction tank in which the first absorber is located;
an introduction port for introducing a heat transfer medium that supplies thermal energy to the first absorber into the reaction tank;
a heat source that heats the heat transfer medium, including a solar heat collecting member that converts received sunlight into heat, and is disposed before the first absorber with respect to the flow direction of the heat transfer medium;
Another feature is that it includes a recovery port for recovering carbon dioxide desorbed from the first absorber.

Regarding the point of desorbing absorbed carbon dioxide from the first absorber, the same discussion as the above-mentioned recovery method can be made. That is, the heat transfer medium heated by sunlight-derived heat in the heat source is introduced into the reaction tank from the introduction port and comes into contact with the first absorber, thereby supplying thermal energy to the first absorber. Ru.

Further, in the carbon dioxide recovery system,
a third flow path through which recovered gas containing carbon dioxide recovered from the recovery port flows;
A heat exchanger that is disposed upstream of the first absorber with respect to the flow direction of the heat transfer medium and performs heat exchange between the heat transfer medium and the recovered gas flowing through the third flow path. It's okay to be prepared.

The first absorber desorbs carbon dioxide by supplying heat. Therefore, the recovered gas containing desorbed carbon dioxide has a relatively high temperature. Therefore, by performing heat exchange between the recovered gas and the heat transfer medium and using the thermal energy of the recovered gas for desorption of carbon dioxide, energy utilization efficiency is improved.

The carbon dioxide recovery system includes:
comprising a first flow path communicating the heat source and the introduction port,
The heat source may be configured to heat the heat transfer medium flowing through the first channel at a position outside the reaction tank.

Furthermore, the carbon dioxide recovery system includes:
a second flow path that guides the atmosphere as a gas to be treated containing carbon dioxide into the reaction tank;
A first valve that can control the flow rate of the atmosphere flowing through the second flow path by adjusting the opening degree of the second flow path may be provided.

In the desorption step of desorbing absorbed carbon dioxide, a heat transfer medium heated by a heat source is introduced into the reaction tank via the first flow path. In addition, in the absorption step of absorbing carbon dioxide into the second absorber from which carbon dioxide has been desorbed, the atmosphere as a gas to be treated is introduced into the reaction tank via the second flow path. That is, according to the above configuration, the carbon dioxide absorption process and desorption process can be performed in the same reaction tank, so the energy required for transferring the absorber, etc. is suppressed, and as a result, carbon dioxide can be produced with less energy. can be collected.

In the carbon dioxide recovery system,
comprising a thermometer that measures the temperature of the internal space of the reaction tank,
The opening degree of the second flow path in the first valve may be adjusted based on the measured value of the thermometer.

As mentioned above, it is preferable to reduce the thermal influence on the carbon dioxide absorbing material that constitutes the first absorber. According to the above configuration, even if the first absorber becomes high in temperature due to the supply of heat for desorption, the atmosphere as a gas to be treated that is lower in temperature than the heat transfer medium can be introduced from the second flow path. With this, the first absorber can be cooled.

Note that the carbon dioxide recovery system includes:
A second valve may be provided that can control the flow rate of the air as the heat transfer medium flowing through the first flow path by adjusting the opening degree of the first flow path.

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

According to the present invention, a carbon dioxide recovery method and system are provided that can desorb absorbed carbon dioxide from an absorbent material with less energy.

1 is a conceptual diagram showing an example of an embodiment of a carbon dioxide recovery system according to the present invention. 2 is an enlarged view of a reaction tank portion in FIG. 1. FIG. It is an enlarged view when a light source is fixed to a reaction tank via another member. 2 is a conceptual diagram of an experimental system used in verification of Example 1. FIG. 3 is a conceptual diagram of an experimental system used in the verification of Comparative Example 1. FIG. It is a graph plotting the temperature of the reaction tank against the elapsed time during verification. FIG. 2 is a schematic diagram showing reaction energy levels when an amine-based material exhibits a reaction in which carbon dioxide is absorbed or desorbed. FIG. 5A is a schematic diagram showing energy supplied to the absorption liquid, similar to FIG. 5A. It is an enlarged view of the installation part of the light source in the reaction tank based on a 1st modification. FIG. 7 is a conceptual diagram of a reaction tank according to a second modification. 7A is a conceptual diagram when the reaction tank according to FIG. 7A is viewed from the +Z direction. FIG. FIG. 7 is a conceptual diagram of a reaction tank according to a third modification. It is a conceptual diagram in which a plurality of reaction vessels according to a third modification are stacked in the Z direction. FIG. 7 is a conceptual diagram of a reaction tank according to a fourth modification. FIG. 7 is a conceptual diagram of a reaction tank according to a fifth modification. FIG. 7 is a perspective view of a reaction tank according to a sixth modification. FIG. 12B is a schematic diagram of the reaction tank in FIG. 12A viewed from the +Y direction. FIG. 7 is a perspective view of a reaction tank according to a seventh modification. FIG. 13A is a schematic diagram of the reaction tank shown in FIG. 13A when viewed from the +X direction. FIG. 13B is a schematic diagram of the reaction tank in FIG. 13A viewed from the +Y direction. FIG. 14A is a perspective view of a reaction tank according to an eighth modification. FIG. 14 is a schematic diagram of the reaction tank in FIG. 14A viewed from the +X direction. FIG. 14B is a schematic diagram of the reaction tank of FIG. 14A when viewed in the normal direction of the inclined surface on which the reaction tank is installed. It is a schematic diagram showing an example of the internal structure of a heat collecting member. It is a conceptual diagram which shows an example of the installation aspect of the reaction tank based on a ninth modification. It is a schematic diagram when a hot water generator is seen in the +X direction. It is a conceptual diagram showing the aspect of heat exchange performed in a heat exchanger. FIG. 1 is a cross-sectional view schematically showing an example of a carbon dioxide recovery system. 17A is a drawing showing a different scene from FIG. 17A in the collection system according to FIG. 17A. 17A is a different view of the retrieval system of FIG. 17A; FIG. FIG. 3 is a flow diagram showing an example of a collection method according to the present invention. FIG. 2 is a cross-sectional view schematically showing the structure of a base material supporting a carbon dioxide absorption liquid. FIG. 3 is a cross-sectional view schematically showing the structure of the second absorbent body. FIG. 7 is a cross-sectional view schematically showing another example of the structure of the second absorbent body. It is a conceptual diagram of the experimental system used in verification. This is the spectrum of the halogen lamp used in the verification. It is a graph showing the desorption results of carbon dioxide in verification. 1 is a diagram schematically showing a configuration example of a collection system. FIG. 2 is a cross-sectional view schematically showing the structure of a reaction tank. 26 is a drawing showing a different scene from FIG. 25 in the reaction tank according to FIG. 25. FIG. FIG. 3 is a cross-sectional view schematically showing the structure of a heat source. 28 is a drawing when the heat source according to FIG. 27 is viewed from the Z direction. 7 is a drawing schematically showing the configuration of another embodiment of the collection system. 29 is a drawing showing a different scene from FIG. 29 in the collection system according to FIG. 29. It is a drawing which shows typically another example of composition of a collection system. 32 is a perspective view schematically showing the configuration of a heat source in FIG. 31. FIG. FIG. 32A is a cross-sectional view of the heat source in FIG. 32A when viewed from the X direction. It is a drawing which shows the structure of another embodiment of a collection system following FIG. 17B.

[First configuration example]
A first configuration example of the absorbed carbon dioxide recovery method and recovery system according to the present invention will be described below with reference to the drawings. It should be noted that the following drawings are all schematically illustrated, and the dimensional ratios and numbers on the drawings do not necessarily match the actual dimensional ratios and numbers.

FIG. 1 is a conceptual diagram showing an example of an embodiment of a carbon dioxide recovery system (hereinafter simply referred to as "recovery system") according to the present invention. After describing the configuration of the recovery system 1 with reference to FIG. 1, a method for recovering absorbed carbon dioxide executed by the recovery system 1 will be explained.

In each of the following figures, an XYZ coordinate system consisting of an X direction, a Y direction, and a Z direction that are perpendicular to each other is also shown as appropriate. Typically, the Z direction is a vertical direction.

Note that in the following description, when expressing directions to distinguish between positive and negative directions, they will be described with positive and negative signs, such as "+X direction" and "-X direction." Furthermore, when expressing a direction without distinguishing between positive and negative directions, it is simply written as "X direction." That is, in this specification, when the term "X direction" is simply used, it includes both the "+X direction" and the "-X direction." The same applies to the Y direction and the Z direction.

As shown in FIG. 1, the recovery system 1 includes an absorption tank 2 that causes an absorption liquid 10 to absorb carbon dioxide contained in a gas 20 to be treated, and a reaction system that desorbs absorbed carbon dioxide from the absorption liquid 10 that has absorbed carbon dioxide. It has a tank 3 and a light source 6 that irradiates the absorption liquid 10 with light L1 in the reaction tank 3. The gas to be treated 20 is a gas to be separated and recovered from carbon dioxide-containing gas. As an example, the gas to be processed 20 includes exhaust gas, the atmosphere, and the like. As the absorption liquid 10, for example, an aqueous solution in which an amine material as a carbon dioxide absorbent is dispersed in water can be used.

This absorption liquid 10 absorbs carbon dioxide contained in the gas 20 to be treated. The gas after the carbon dioxide contained in the gas to be treated 20 has been absorbed (hereinafter referred to as “treated gas 21”) is discharged from the absorption tank 2. In FIG. 1, the post-processing gas 21 is indicated by a dashed line.

The absorption liquid 10 that has absorbed carbon dioxide in the absorption tank 2 is sent to the reaction tank 3 through the channel 4 using, for example, a liquid pump (not shown). Then, as described later, the absorption liquid 10 is irradiated with light L1 and heat H1 is supplied, and the absorbed carbon dioxide is desorbed from the absorption liquid 10. In the reaction tank 3, the gas containing absorbed carbon dioxide desorbed from the absorption liquid 10 (hereinafter referred to as "desorption gas 22") is recovered from the recovery port 7 provided in the reaction tank 3. In FIG. 1, the desorption gas 22 is indicated by a chain double-dashed line.

Further, in the reaction tank 3, the absorption liquid 10 from which the absorbed carbon dioxide has been desorbed is sent to the absorption tank 2 through the flow path 5 by a liquid pump or the like (not shown). Then, the carbon dioxide contained in the gas 20 to be treated is again absorbed. Note that heat exchange may be performed in the absorption liquid 10 flowing through the

channels

4 and 5 using, for example, a heat exchanger (not shown). This heat exchange makes it possible to increase the temperature of the absorption liquid 10 flowing into the reaction tank 3, which is preferable. The flow direction of the absorption liquid 10 is indicated by a double arrow in FIG. 1, and the same is true in the following drawings. Regarding the absorption tank 2, the flow path 4, and the flow path 5, the configuration of a conventionally known recovery system can be used.

Next, with reference to FIG. 1, an example of a method for recovering absorbed carbon dioxide (hereinafter simply referred to as a "recovery method") that can be executed by the recovery system 1 will be described.

This recovery method includes a pre-step S100 of absorbing carbon dioxide from the gas 20 to be treated, a step S101 of irradiating light onto the absorption liquid 10 that has absorbed carbon dioxide, and a step S101 of irradiating light onto the absorption liquid 10 that has absorbed carbon dioxide. It includes a step S102 of supplying heat and a step S103 of recovering carbon dioxide desorbed from the absorption liquid 10.

(Pre-process S100)
In the absorption tank 2 , typically the gas to be treated 20 and the absorption liquid 10 are brought into gas-liquid contact, so that the carbon dioxide contained in the gas to be treated 20 is absorbed into the absorption liquid 10 . Note that, in a further preceding stage of the pre-process, pre-treatment such as cooling the gas to be treated 20 or screening for substances contained in the gas to be treated 20 that inhibit carbon dioxide absorption may be performed.

(Light irradiation step S101)
As mentioned above, energy is required to remove absorbed carbon dioxide from the absorption liquid 10. Therefore, in this recovery method, the absorption liquid 10 that has absorbed carbon dioxide is irradiated with light L1 using the light source 6 and supplied with heat H1. First, irradiation of the light L1 onto the absorption liquid 10 will be explained.

FIG. 2A is an enlarged view of the reaction tank 3 portion in FIG. 1 for ease of understanding. FIG. 2A shows an example in which the light source 6 is directly fixed to the surface of the reaction tank 3 in the −Z direction. Further, in FIG. 2A, a case is illustrated in which the light source 6 is composed of a plurality of LED elements 8 mounted on the substrate 9, but it is also possible to employ a lamp as the light source 6.

In the present invention, the wavelength of the light L1 emitted from the light source 6 is not limited, but as an example, the light source 6 may emit light within a wavelength range of 250 nm to 600 nm. The wavelength of the light L1 emitted by the light source 6 is preferably selected according to the absorption spectrum of the carbon dioxide absorbing material such as an amine material. From the viewpoint of efficiently imparting energy by irradiation of the light L1 to the carbon dioxide absorbing material included in the absorption liquid 10, a wavelength that is easily absorbed by the carbon dioxide absorbing material and difficult to be absorbed by the solvent is more preferable.

As shown in FIG. 2A, when the light source 6 is placed outside the reaction tank 3, the inside of the reaction tank 3 can be configured by configuring the reaction tank 3 with a member that transmits the light L1 emitted from the light source 6. The light L1 can be irradiated onto the absorbing liquid 10 located at. In FIG. 2A, the light L1 is indicated by a solid arrow, and the same applies to the following drawings. For example, glass can be used as the member that transmits the light L1. By adopting such a configuration, especially when the reaction tank 3 is installed outdoors or in a non-dark room, sunlight can also be used to irradiate the absorption liquid 10 in the reaction tank 3 during the daytime. can get.

Note that, as shown in FIG. 2A, when the light source 6 is disposed only on the bottom side of the reaction tank 3, only the material at the bottom of the reaction tank 3 may be made of a member that transmits the light L1. . This aspect will be discussed later with reference to FIG.

Furthermore, when the reaction tank 3 is made of a member that transmits the light L1, a reflective film 11 may be formed on a part of the outer surface of the reaction tank 3, as shown in FIG. 2A. Depending on the wavelength of the light L1, it is assumed that a part of the light L1 irradiated onto 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 has once passed through the absorbing liquid 10 can be directed toward the absorbing liquid 10 again, and the absorbing liquid 10 can be efficiently irradiated with the light L1. As such a reflective film 11, an aluminum coating or the like can be used.

Note that in FIG. 2A, the light source 6 is installed on the surface of the reaction tank 3 in the -Z direction, and the light L1 emitted in the +Z direction is irradiated with the light source 6. However, the light source 6 can be installed at any location in the reaction tank 3 as long as it can irradiate the absorption liquid 10 with light. That is, for example, the light source 6 may be installed so as to irradiate the absorption liquid 10 with the light L1 from the X direction and the Y direction. In this case, the formation range of the reflective film 11 is adjusted as appropriate.

Further, in the above explanation, it is assumed that the reflective film 11 is formed on the outer surface of the reaction tank 3, but if the reflective film 11 is made of a material that does not deteriorate even if it comes into contact with the absorption liquid 10, the reflective film 11 can be The membrane 11 may be formed on the inner surface of the reaction tank 3.

This light irradiation step S101 corresponds to step (a).

(Heat supply step S102)
Furthermore, in order to desorb the absorbed carbon dioxide from the absorption liquid 10, heat H1 is supplied to the absorption liquid 10 (see FIG. 2A). In the example shown in FIGS. 1 and 2A, the light source 6 is fixed directly 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 executed simultaneously. Note that in FIG. 2A, the heat H1 is indicated by a broken arrow, and the same applies to the following drawings.

Note that heat generally tends to be transmitted vertically upward. Therefore, taking FIG. 2A as an example, it is preferable to arrange the light source 6 on the bottom side of the reaction tank 3 so that the +Z direction corresponds to the vertically upward direction, in other words. Thereby, the heat H1 emitted by the light source 6 can be efficiently supplied to the absorption liquid 10.

Further, FIG. 2B is an enlarged view of the case where the light source 6 is fixed to the reaction tank 3 via another member (hereinafter referred to as a "heat transfer member"), similar to FIG. 2A. As shown in FIG. 2B, the light source 6 may be fixed to the reaction tank 3 via the heat transfer member 13. The heat transfer member 13 is provided for the purpose of supplying the heat H1 generated by the light source 6 to the absorption liquid 10. From the viewpoint of efficiently supplying the heat H1 to the absorption liquid 10, the heat transfer member 13 is preferably a metal member with high thermal conductivity. For example, the heat transfer member 13 can be made of copper, aluminum, or the like.

To be sure, the heat supply step S102 is performed for the purpose of making the temperature of the absorption liquid 10 higher than the surrounding environmental temperature. Typically, the temperature of the absorption liquid 10 is raised to a temperature of 35° C. to 120° C. in the heat supply step S102. In addition, from the viewpoint of lowering the thermal energy used for desorption of carbon dioxide, the temperature after raising the temperature of the absorption liquid 10 is preferably 60°C or lower, more preferably 50°C or lower, and particularly 40°C or lower. preferable. By heating to a temperature of about 50° C. or lower, concerns about burns are suppressed, so this system can be installed in general households. As a result, the effect of greatly reducing the carbon dioxide concentration in the atmosphere is expected.

This heat supply step S102 corresponds to step (b).

(Collection step S103)
The desorption gas 22 containing the desorbed and absorbed carbon dioxide is typically stored in a storage tank (not shown) such as a cylinder. Alternatively, for example, it may be sent to a carbon dioxide utilization facility such as a plant factory via piping.

This recovery step S103 corresponds to step (c).

[Verification 1]
The effect of irradiating the absorption liquid that has absorbed carbon dioxide with light will be explained in more detail below.

(Example 1)
FIG. 3A is a conceptual diagram of the experimental system used in this verification. In this experimental system, as shown in FIG. 3A, an absorption liquid 30 was placed inside a reaction tank 33. The reaction tank 33 is made of glass. Further, the absorption liquid 30 is a secondary amine aqueous solution having a concentration of 20% by mass. This absorption liquid 30 was made to absorb carbon dioxide in advance using experimental carbon dioxide gas. More specifically, the absorption liquid 30 was adjusted by allowing it to absorb carbon dioxide until no additional carbon dioxide was absorbed, and then allowing it to stand still in the air for about one hour to reach an equilibrium state.

This absorption liquid 30 was irradiated with light L1 using a light source 36, as shown in FIG. 3A. The light source 36 is equipped with an LED element 38 having a peak wavelength of 365 nm.

Furthermore, the light source 36 was placed close to the reaction tank 33 in order to supply the heat H1 emitted by the light source 36 to the absorption liquid 30. That is, by the light source 36 emitting the light L1, the absorption liquid 30 inside the reaction tank 33 was irradiated with the light L1 and supplied with the heat H1 at the same time. The lighting time of the light source 36 was 50 minutes, and during that time, the temperature of the reaction tank 33 was measured by a thermocouple 39 attached to the reaction tank 33. In addition, in Example 1 and Comparative Example 1 to be described later, the experiment was conducted while manually adjusting the output of the power source 37 connected to the light source 36 in order to make the temperatures of the reaction vessels 33 of both the same.

After turning on the light source 36, nitrogen gas was supplied to the reaction tank 33 by pushing a syringe 35a filled with nitrogen gas in order to collect the desorbed and absorbed carbon dioxide (see FIG. 3A). . Since the reaction tank 33 is sealed by the stopper 34, by supplying air with the syringe 35a, the piston of the gas collecting syringe 35b is pulled out, and the gas in the reaction tank 33 can be collected. By measuring the carbon dioxide concentration of the gas collected in the reaction tank 33, the amount of carbon dioxide desorbed from the absorption liquid 30 was measured.

(Comparative example 1)
FIG. 3B is a conceptual diagram showing an experimental system used in the verification of Comparative Example 1, similar to FIG. 3A. In the verification of Comparative Example 1, as shown in FIG. 3B, a copper light shielding plate 40 was placed between the light source 36 and the reaction tank 33 so as to block the light L1 emitted from the light source 36.

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. Furthermore, although the light L1 emitted by the light source 36 is blocked by the light shielding plate 40, 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 heat H1. be done. That is, in Comparative Example 1, only the heat H1 was supplied to the absorption liquid 30 inside the reaction tank 33. Other configurations and operating procedures are the same as in the first embodiment.

(Verification of results)
FIG. 4 is a graph in which the horizontal axis is the time elapsed since the light source 36 was turned on, and the vertical axis is the temperature measured by the thermocouple 39. In FIG. 4, the results of Example 1 are shown by a solid line, and the results of Comparative Example 1 are shown by a broken line. As described above, the experiment was conducted while adjusting the output of the power source 37 in order to keep the temperatures of the reaction vessels 33 in Example 1 and Comparative Example 1 at the same level. As a result, as shown in FIG. 4, the temperature of the reaction tank 33 was 1 to 2° C. higher in Comparative Example 1 than in Example 1 after about 20 minutes had passed. This is considered to be an error caused by manually controlling the output of the power source 37, and it can be said that the temperatures of the reaction tank 33 were approximately the same in Example 1 and Comparative Example 1.

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

On the other hand, in Comparative Example 1, the amount of gas collected by the syringe 35b was 110 mL. The carbon dioxide concentration of this gas was 14%. That is, 15.4 mL of carbon dioxide was desorbed from the absorption liquid 30 by the supply of heat from the light source 36.

As mentioned above, although the temperature of the reaction tank 33 in Comparative Example 1 was about the same as that in Example 1, or more specifically, 1°C to 2°C higher, the temperature in Example 1 was higher. This resulted in desorption of carbon dioxide. This indicates that by irradiating the absorption liquid 30 with light and supplying heat, more carbon dioxide can be desorbed than simply supplying heat.

The inventor speculates as follows about the reason why more carbon dioxide was desorbed by irradiating the absorption liquid 30 with light in addition to supplying heat.

FIG. 5A is a schematic diagram showing energy levels when an amine-based material exhibits a reaction of absorbing or desorbing carbon dioxide. As mentioned above, when an amine-based material absorbs carbon dioxide, bicarbonate ions, carbamate ions, or carbamic acid are generated. In FIG. 5A, lines representing the energy levels of bicarbonate ions are shown as broken lines, and lines representing the energy levels of carbamate ions and carbamic acid are shown as solid lines.

The energy level at which the amine material, carbon dioxide, and solvent each exist independently, in other words, the state in which carbon dioxide is desorbed, the amine material must be active to absorb carbon dioxide and convert it to bicarbonate ions. ization energy E ₁ is required. Similarly, activation energy E ₂ is required for an amine-based material to absorb carbon dioxide and convert it into carbamate ions or carbamic acid.

Furthermore, these reverse reactions require energy greater than their respective activation energies (E ₁ , E ₂ ). This is because the reaction in which the amine-based material absorbs carbon dioxide to produce 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 E ₄ released when producing carbamate ions or carbamic acid is greater than the energy E ₃ released when producing bicarbonate ions. This means that carbamate ions and carbamate ions are more energetically stable than bicarbonate ions, and in Figure 5A, the energy levels of carbamate ions and carbamate are lower than that of bicarbonate ions. Correspond to what is shown.

Focusing on the desorption of carbon dioxide, in order to desorb carbon dioxide from bicarbonate ions, energy equivalent to the activation energy E ₁ is required in addition to the energy E ₃ . Moreover, in order to desorb carbon dioxide from carbamate ions and carbamic acid, energy corresponding to activation energy E ₂ is required in addition to energy E ₄ .

Here, in order to desorb carbon dioxide, energy E _H due to heat supplied to the absorption liquid and energy E _L due to light irradiation are assumed (see FIG. 5B). FIG. 5B is a schematic diagram illustrating energy supplied to the absorption liquid, similar to FIG. 5A. In FIG. 5B, the energy E _H is indicated by a dashed line, and the energy E _L is indicated by a dashed double dotted line. As shown in FIG. 5B, even if the thermal energy E _H can cause a reaction to desorb carbon dioxide from bicarbonate ions, it cannot cause a reaction to desorb carbon dioxide from carbamate ions and carbamic acid. It is assumed that this is not possible. On the other hand, considering the energy E _L due to light irradiation, the energy is greater than the sum of energy E ₄ and activation energy E ₂ necessary for desorption, and carbon dioxide can be desorbed from carbamate ions and carbamic acid. Can be done.

The above discussion is also consistent with the fact that bicarbonate ions have a small light absorption effect, and carbamate ions and carbamic acid have a large light absorption effect. In other words, thermal energy is dominant in the desorption of carbon dioxide from bicarbonate ions, and the energy contribution from light irradiation is small. On the other hand, supply of energy through light irradiation is effective for desorption of carbon dioxide from carbamate ions and carbamic acid.

In this way, it is thought that more carbon dioxide can be desorbed by not only supplying heat but also irradiating light to the absorption liquid that has absorbed carbon dioxide. It can also be said that even under desorption conditions at low temperatures where little thermal energy is supplied to the absorption liquid, a large amount of carbon dioxide can be desorbed by irradiating the absorption liquid with light.

When heat energy sufficient to separate atoms is supplied to a substance, molecular dissociation occurs. The conventional method of supplying thermal energy to an absorption liquid that has already absorbed carbon dioxide in order to desorb carbon dioxide utilizes the above phenomenon.

On the other hand, many substances have light absorption bands in the range from near ultraviolet to visible regions. When a substance is irradiated with light, molecules constituting the substance are excited by the light energy and then transition to a ground state. Furthermore, depending on the magnitude of light energy, the positions of atomic nuclei constituting a substance may change, resulting in changes in chemical bonds. When the electrons move to higher energy orbits due to photoexcitation, the covalent bonds become unstable, the repulsion between the atomic nuclei increases, and the bonds dissociate in the excited state.

As described above, the mechanism of action is different between molecular dissociation using thermal energy and molecular dissociation using light energy. Immediately after molecules dissociate due to light energy, intermediates exhibiting a radical state tend to exist. This intermediate induces the next reaction, making it easier for the dissociation reaction to proceed.

In other words, the above-mentioned recovery method uses both thermal energy and light energy to cause the dissociation of molecules originating from different mechanisms, thereby reducing the amount of energy input compared to conventional methods. It becomes possible to increase the desorption efficiency of carbon dioxide while decreasing the carbon dioxide. Furthermore, it becomes possible to desorb carbon dioxide in a lower temperature environment than before, greatly contributing to the introduction and spread of carbon dioxide recovery systems. This will greatly contribute to Goal 13 of the Sustainable Development Goals (SDGs) led by the United Nations, ``Take urgent measures to reduce climate change and its impacts.''

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

When the peak wavelength of the light L1 emitted from the light source 36 is 365 nm, the energy E per photon included in the light L1 emitted from the light source 36 is:
E = (6.626 × 10 ^-34 ) × (2.998 × 10 ⁸ ) / (365 × 10 ^-9 ) = 5.442 × 10 ^-19 [J]
It is calculated that

Therefore, the number N of photons of the light L1 emitted from this light source 36 is:
N = 15 / (5.442 × 10 ^-19 ) = 2.756 × 10 ¹⁹
It is calculated that

Assuming that the total amount of light-absorbing carbamate ions and carbamic acid contained in the absorption liquid 30 is 0.1 mol, and if Avogadro's constant is NA, then the number of molecules of carbamate ions and carbamic acid, K= It is calculated as 0.1×NA. Therefore, the standard irradiation time τ of the light L1 required to separate all these molecules is:
τ = K / N = 0.1 × (6.022 × 10 ²³ ) / (2.756 × 10 ¹⁹ ) =2185 (seconds)
It is calculated that

The above is just an example of the design standard when calculating the standard irradiation time τ. For example, as in the system 1 shown in FIG. 1, when the light L1 is irradiated from the light source 6 while the absorption liquid 10 is temporarily stored in the reaction tank 3, the reference irradiation calculated by the above method is used. Based on the time τ, the time during which the light L1 is actually irradiated can be set. In addition, as will be described later with reference to FIG. 7A, in the case of irradiating the light L1 while flowing the absorbing liquid 10, the flow rate of the absorbing liquid 10 is determined based on the reference irradiation time τ calculated by the above method. can be adjusted.

[Modified example]
Hereinafter, a modified example of the carbon dioxide recovery system will be described, focusing on the differences from the above embodiment.

(First variation)
In the embodiment described above, an example has been described in which the reaction tank 3 is made of a member that transmits the light L1. However, even if the reaction tank 3 is not composed of such members, as shown in FIG. It is also possible to irradiate the absorption liquid 10 located inside the reaction tank 3 with the light L1. FIG. 6 is an enlarged view of a part where a light source is installed in a reaction tank according to a first modification. The light irradiation window 12 can be made of, for example, glass.

(Second modification)
In the embodiment described above, an example was shown in which the light source 6 is arranged outside the reaction tank 3 (see FIG. 1, etc.), but the light source 6 may be arranged inside the reaction tank 3. FIG. 7A is a conceptual diagram of a reaction tank according to a second modification. Moreover, FIG. 7B is a conceptual diagram when FIG. 7A is viewed from the +Z direction. Although FIG. 7B shows an example in which two light sources 46 are installed, two or more light sources 46 may be installed. Further, the location and range where the light source 46 is installed can be adjusted as appropriate.

As shown in FIGS. 7A and 7B, the light source 46 is placed inside the reaction tank 43 and comes into contact with the flowing absorption liquid 10. By arranging the light source 46 inside the reaction tank 43 in this way, the heat H1 emitted by the light source 46 when emitting light can be efficiently supplied to the absorption liquid 10. For example, by providing a current-carrying member 41 that is in electrical contact with the light source 46 outside the reaction tank 43, a power source for driving the light source 46 and the light source 46 inside the reaction tank 43 can be energized.

Furthermore, in the above embodiment, when desorbing the absorbed carbon dioxide, the absorbing liquid 10 was described as remaining in the reaction tank 3 (see FIG. 1), but while the absorbing liquid 10 is flowing through it, carbon dioxide is desorbed. You may leave. As shown in FIG. 7A, the reaction tank 43 includes an inlet 44 for introducing the absorption liquid 10, and an outlet 45 for discharging the absorption liquid 10 after desorbing carbon dioxide. According to this configuration, absorbed carbon dioxide can be desorbed while flowing the absorption liquid 10. That is, in this example, the absorption liquid 10 is passed through in the X direction.

As mentioned above, it is assumed that the desorption of carbon dioxide is greater on the side closer to the outlet 45 than on the side closer to the inlet 44. Therefore, as shown in FIGS. 7A and 7B, the recovery port 47 for recovering the desorbed gas 22 is preferably arranged closer to the outlet 45 than the inlet 44.

(Third variation)
From the viewpoint of making the absorption liquid 10 absorb light as efficiently as possible, it is preferable that the width of the absorption liquid 10 is narrow with respect to the direction in which the light travels. From this point of view, as shown in FIG. 8, it is effective to make the internal space in the reaction tank 53 in which the absorbing liquid 10 is located have a flat shape when viewed from the front. FIG. 8 is a conceptual diagram of a reaction tank according to a third modification.

In FIG. 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 onto the absorption liquid 10 through the window 12 provided on the surface of the reaction tank 53 in the −Z direction. Further, 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.

At this time, as shown in FIG. 8, it is preferable that the top wall 58 of the reaction tank 53 be inclined with respect to the bottom wall 59. That is, the reaction tank 53 has a structure in which the distance D1 between the bottom wall portion 59 and the top wall portion 58 in the Z direction increases as the distance from the inlet port 54 approaches the outlet port 55 in the X direction. .

With this configuration, a space (hereinafter referred to as "desorption space 60") is created in the reaction tank 53 in which the desorption gas 22 containing carbon dioxide desorbed from the absorption liquid 10 is temporarily located. ) can be secured sufficiently. Further, the slope of the upper wall portion 58 allows the desorption gas 22 present in the desorption space 60 to be guided to the recovery port 57.

Additionally, multiple reaction tanks may be installed. FIG. 9 is a conceptual diagram when a plurality of reaction vessels according to the third modification are stacked in the Z direction. As described above, in the reaction tank 53, it is preferable that the internal space in which the absorption liquid 10 is located has a flat shape when viewed from the front (see FIG. 8). In this case, it is assumed that the installation area of the reaction tank 53 on the XY plane will be relatively large.

Furthermore, depending on the amount of carbon dioxide gas contained in the gas to be treated 20, it is necessary to increase the volume of the absorption liquid 10, and it is also assumed that the installation area of the recovery system will increase. Therefore, taking FIG. 9 as an 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 vertically upward direction. With this arrangement, the installation area of the reaction vessels (53a, 53b) can be effectively utilized.

Although FIG. 9 describes the case where two reaction vessels (53a, 53b) are connected in parallel, the reaction vessels (53a, 53b) may be connected in series. Moreover, two or more reaction vessels may be stacked.

(Fourth variation)
Further, in the embodiment described above, an example has been described in which heat generated by the light source 6 is supplied to the absorbing liquid 10. However, the present invention does not exclude a configuration that includes a heat source different from the light source that irradiates the absorption liquid 10 with light. FIG. 10 is a conceptual diagram of a reaction tank according to a fourth modification. In FIG. 10, the absorption tank is omitted. As shown in FIG. 10, the reaction tank 63 may include a heat source 68 that supplies heat to the absorption liquid 10. As the heat source 68, for example, a heater, a boiler, or the like can be used.

Furthermore, in the above embodiment, the light source 6 was described as being fixed to the reaction tank 3 directly or via another member. However, as long as heat can be supplied to the absorption liquid 10, the light source 66 and the reaction tank 63 may be placed apart from each other as shown in FIG. 10. Note that even when the reaction tank 63 includes the heat source 68, the light source 66 can be fixed to the reaction tank 63 directly or via another member, and the heat generated by the light source 66 can be supplied to the absorption liquid 10.

(Fifth modification)
Moreover, if a so-called batch type method is adopted, the absorption tank 2 shown in FIG. 1, for example, is not required, and carbon dioxide can be absorbed and desorbed using only the reaction tank. FIG. 11 is a conceptual diagram of a reaction tank according to a fifth modification.

The flow of absorption and desorption of carbon dioxide with this configuration will be explained. As shown in FIG. 11, the reaction tank 73 has an inlet 74 through which the gas to be treated 20 flows, and a recovery port 77 through which the treated gas 21 and the desorbed gas 22 can be recovered. In absorbing carbon dioxide, the valve 79a provided in the flow path leading to the inlet 74 and the valve 79b downstream of the recovery port 77 are opened, and the other valve 79c downstream of the recovery port 77 is closed. Ru. Then, the absorption liquid 10 is pumped up from the flow path 78 using, for example, a liquid pump, and the absorption liquid 10 and the gas to be treated 20 are brought into gas-liquid contact. At this time, the processed gas 21 is discharged from the flow path provided with the valve 79b of the recovery port 77.

In the desorption of carbon dioxide, the

valves

79a and 79b are closed, and the valve 79c is opened. Then, using, for example, the light source 76, the absorption liquid 10 is irradiated with light and heat is supplied, and the absorbed carbon dioxide is desorbed. At this time, the desorbed gas 22 is recovered from the flow path provided with the valve 79c of the recovery port 77. Note that in addition to the light source 76, a heat source that supplies heat to the absorption liquid 10 may be further provided.

This configuration has the advantage that the installation area required for the system configuration is small. For example, this modification may be adopted depending on the amount of generated gas 20 to be treated and the concentration of carbon dioxide contained in the gas 20 to be treated.

(Sixth variation)
In the fourth modification described above, an example has been described in which the reaction tank 63 includes a heat source 68 that supplies heat to the absorption liquid 10. As one aspect of the heat source 68, a member that absorbs sunlight and converts it into heat (hereinafter, for convenience, referred to as a "solar heat collecting member" or simply a "heat collecting member") may be used. This modification will be described with reference to FIGS. 12A and 12B.

FIG. 12A corresponds to a perspective view of the reaction tank. FIG. 12B is a drawing when the reaction tank 83 in FIG. 12A is viewed from the +Y side, and for convenience of explanation, the inside of the reaction tank 83 is shown transparently. In FIGS. 12A and 12B, the +Z direction corresponds to vertically upward.

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

Further, the reaction tank 83 has a window 14 on the +Z side surface. Since the reaction tank 83 of this modification is placed outdoors, the absorption liquid 10 in the reaction tank 83 is irradiated with sunlight C2 emitted by the sun C1 through the window 14. The window 14 is made of quartz glass, for example.

It is said that the breakdown of the light contained in sunlight C2 is generally 7% ultraviolet light, 43% visible light, and 50% infrared light. A part of the light (typically ultraviolet light) contained in the sunlight C2 is absorbed by the carbon dioxide absorbing material contained in the absorption liquid 10, and contributes to desorption of carbon dioxide. This point is similar to the discussion above. In addition, the solvent contained in the absorption liquid 10 absorbs a part of the light (typically infrared light) contained in the sunlight C2, and the temperature of the absorption liquid 10 increases, promoting desorption of carbon dioxide. We can also expect the effect of In this regard, since amine-based materials typically used as carbon dioxide absorbers exhibit absorption of ultraviolet light, the usable wavelength range of light is wide, and sunlight C2 can be effectively utilized.

Furthermore, the reaction tank 83 includes a heat collecting member 15 inside (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. Note that the heat collecting member 15 can be made of metal such as stainless steel. Further, from the viewpoint of efficiently absorbing sunlight C2, it is typically preferable to apply a black coating.

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

From the perspective of reducing the energy required for heating, it is also envisaged that the heater etc. be driven by a so-called solar power generation system. However, in a solar power generation system, there is a problem in the wavelength range of light that can be used by a solar panel that absorbs sunlight C2. On the other hand, in this modified example, infrared light in particular can be used effectively, so the wavelength range of usable light is wide, and compared to solar power generation systems, sunlight C2 can be used more efficiently. It has characteristics.

(Seventh variation)
The reaction tank of the seventh modification will be described with reference to FIGS. 13A to 13C. FIG. 13A corresponds to a perspective view of the reaction vessel. FIG. 13B is a drawing when the reaction tank 83 in FIG. 13A is viewed from the +X side, and for convenience of explanation, the inside of the reaction tank 83 is shown transparently. FIG. 13C is a drawing when the reaction tank 83 in FIG. 13A is viewed from the +Y side, and similarly to FIG. 13B, the inside of the reaction tank 83 is shown transparently. Furthermore, in FIG. 13C, illustration of the heat transfer member 13 is omitted.

The reaction tank 83 of this modification includes a heat collecting member 16 in the shape of a round bar. More specifically, the heat collecting member 16 is composed of a plurality of round rod-shaped members, and is arranged at a position spaced apart from the reaction tank 83 in the +Z direction. As shown in FIG. 13A, the heat collecting member 16 is fixed to the reaction tank 83 via the heat transfer member 13.

By arranging the reaction tank 83 of this modification outdoors, sunlight C2 from the sun C1 is irradiated onto the heat collecting member 16, and the heat collecting member 16 absorbs the sunlight C2 and is heated. The heat generated by the heat collecting member 16 is supplied to the absorption liquid 10 as heat H1 via the heat transfer member 13 connected to the heat collecting member 16.

In this modification, the heat collecting member 16 arranged at the +Z side position of the reaction tank 83 was composed of a plurality of round bar-shaped members. On the other hand, if a flat heat collecting member 15 is arranged in place of the heat collecting member 16, heat will be collected when the sun C1 is at a relatively low position, such as in the morning hours or evening hours. It is assumed that the angle of incidence of the sunlight C2 on the surface of the member 15 increases, and the reflectance of the sunlight C2 on the surface of the heat collecting member 15 increases. By using the heat collecting member 16 made up of a plurality of round bar-shaped members as shown in FIG. 13C, the absorption efficiency of sunlight C2 can be increased regardless of the height position of the sun C1.

Note that a flat heat collecting member 15 may be additionally provided inside the reaction tank 83. In the example shown in FIGS. 13B to 13C, a flat heat collecting member 15 is additionally disposed on the bottom wall portion 59 of the reaction tank 83, as in the sixth modification. The point in which the heat from the heat collecting member 15 is supplied to the absorbing liquid 10 is the same as in the sixth modification, so a description thereof will be omitted.

Note that in this modification, the heat collecting member 16 disposed on the +Z side of the reaction tank 83 is described as being a round bar-shaped member, but this is just an example. Even if the heat collecting member 16 has a shape other than a round bar shape such as a rectangular column shape, it is within the scope of the present invention.

(Eighth variation)
The reaction tank of the eighth modification will be described with reference to FIGS. 14A to 14C. FIG. 14A corresponds to a perspective view of the reaction vessel. FIG. 14B is a drawing when the reaction tank 83 of FIG. 14A is viewed in the +X direction, and for convenience of explanation, the inside of the reaction tank 83 is shown transparently.

FIG. 14C is a drawing when the reaction tank 83 of FIG. 14A is viewed in the normal direction of an inclined surface provided on a pedestal 87, which will be described later. For convenience of explanation, the inside of the reaction tank 83 is shown transparently. ing. Note that illustration of the pedestal 87 is omitted in FIG. 14C.

In FIGS. 14A to 14C, the +Z direction corresponds to vertically upward.

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.

In this modification, the reaction tank 83 is installed on a pedestal 87 having an inclined surface 87a. By installing the reaction tank 83 on the inclined surface 87a, the heat collecting member 16 fixed to the reaction tank 83 is also arranged along the inclined surface 87a. By adopting such an arrangement mode, it becomes possible to efficiently capture sunlight C2 from the sun C1 into the heat collecting member 16.

Note that in this modification, a recess 84 may be provided in a part of the outer wall of the reaction tank 83, as shown in FIGS. 14B and 14C. The recess 84 has a shape corresponding to the shape of the end 16 a of the heat collecting member 16 , and the end 16 a is placed in contact with the recess 84 . As a result, the contact area between the heat collecting member 16 and the reaction tank 83 increases, so that the heat H1 from the heat collecting member 16 can be efficiently supplied to the absorption liquid 10.

Furthermore, as an example of the heat collecting member 16, a structure as shown in FIG. 15 can also be used. FIG. 15 is a schematic diagram showing an example of the internal structure of the heat collecting member. As shown in FIG. 15, one end of each of the outer tube 161 and the inner tube 162 included in the heat collecting member 16 is sealed by a sealing part 163, and a space (hereinafter referred to as "sealed space 164" for convenience) .) to form. Since the sealed space 164 is in a vacuum state, it is preferable that the heat H1 generated by the heat collecting section 165, which will be described later, is unlikely to leak to the outside. For example, the outer tube 161 and the inner tube 162 can be made of a glass material such as quartz glass.

Further, inside the inner tube 162 that is sealed with a sealing part 169 made of silicone, for example, a heat collecting part 165, heat transfer fins 166, and a heat pipe 167 with one end 167a exposed to the outside are arranged. be done. The inside of the heat pipe 167 is in a vacuum state, and a working fluid 168 such as pure water is placed therein. Typically, the heat collecting portion 165 is made of metal such as stainless steel, and the heat transfer fins 166 are made of metal such as aluminum.

The heat collecting member 16 can be installed in the reaction tank 83, for example, in the manner described using FIGS. 14A to 14C. That is, the end 16a of the heat collecting member 16 in FIG. 14C corresponds to the end 167a of the heat pipe 167. By irradiating the heat collecting member 16 with sunlight C2, the heat collecting part 165 is heated, and heat H1 is supplied to the working fluid 168 via the heat transfer fins 166. The heated and evaporated working fluid 168 moves toward one end 167a of the heat pipe 167. At the end 167a, heat H1 is supplied from the vapor of the high-temperature working fluid 168 to the absorption liquid 10 via the reaction tank 83 (see FIG. 14C). The vapor of the working fluid 168, which has become low temperature by supplying the heat H1 to the absorption fluid 10, is liquefied and moves to the other end 167b of the heat pipe 167. By repeating this series of operations, the absorption liquid 10 is heated using sunlight C2 as an energy source.

(Ninth modification)
As one aspect of the heat source 68 (see FIG. 10) that supplies heat to the absorption liquid 10, a heat medium heated to a high temperature may be used. That is, heat H1 is supplied to the absorption liquid 10 by heat exchange performed between the high temperature heat medium and the absorption liquid 10. From the viewpoint of reducing the energy required to supply this heat H1, the heat medium is preferably heated using sunlight C2. This point will be explained with reference to FIGS. 16A to 16C.

FIG. 16A is a conceptual diagram showing an example of an installation mode of a reaction tank 89 according to a ninth modification, and as described later, hot water is supplied to a heat exchanger 91 from a hot water generator 90 installed on a roof 94. The absorption liquid 10 in the reaction tank 89 is heated in the heat exchanger 91. FIG. 16B is a schematic drawing when the hot water generator 90 installed on the roof 94 is viewed in the +X direction, and for convenience of explanation, the inside of the hot water generator 90 is shown transparently. FIG. 16C is a conceptual diagram showing a mode of heat exchange performed in the heat exchanger 91. In FIGS. 16A to 16C, the +Z direction corresponds to vertically upward direction.

As shown in FIG. 16A, the reaction tank 89 is connected to a heat exchanger 91 via a flow path 92. Further, the heat exchanger 91 is connected to the hot water generator 90 via a flow path 93.

Regarding the reaction tank 89, the configurations of the reaction tank according to the above-described embodiment and each modification can be used. Furthermore, the shape of the reaction tank can be designed to suit the installation environment. As an example, FIG. 16A shows a reaction tank 89 whose sides in the X direction are designed to be relatively short and where a plurality of light sources 86 are directly fixed on the -X side. A flow path 92 connected to a heat exchanger 91 is provided in the reaction tank 89, and the absorption liquid 10 is guided to the heat exchanger 91 via the flow path 92.

The hot water generator 90 has an L-shaped cross-section, for example, as shown in FIG. 16B, and contains water 95 as a heat medium therein. The hot water generator 90 has a flat heat collecting member 15 on a part of the outer wall surface. The heat collecting member 15 is heated by absorbing sunlight C2, and the temperature of the water 95 becomes high (hereinafter referred to as "hot water 95"). This hot water 95 is guided to a heat exchanger 91 via a flow path 93.

As schematically shown in FIG. 16C, in the heat exchanger 91, heat exchange occurs between the absorption liquid 10 flowing through the flow path 92 and the hot water 95 flowing through the flow path 93. It will be done. Thereby, heat H1 is supplied from the hot water 95 to the absorption liquid 10.

Note that depending on the solar radiation conditions and time of day of the sun C1, it is also assumed that the temperature of the hot water 95 is relatively low. Therefore, heat exchange by the heat exchanger 91 is preferably performed when the temperature of the hot water 95 is higher than that of the absorption liquid 10.

Further, FIG. 16A shows an example in which the hot water generator 90 is installed on the roof 94 of a building from the viewpoint of efficiently irradiating the heat collecting member 15 with sunlight C2. At this time, from the viewpoint of reducing the load on the building, it is preferable to install the reaction tank 89 and the heat exchanger 91 at a location other than the roof 94 (such as the ground), as shown in FIG. 16A. Since the absorption liquid 10 containing, for example, an amine-based material is located inside the reaction tank 89, from the viewpoint of safety, it is particularly preferable that the reaction tank 89 be installed on the ground.

Note that in this modification, an example in which the hot water generator 90 is installed on the roof 94 of a building has been described, but the present invention is not limited to this. Since the hot 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 mode is also the same as in the seventh modification and the eighth modification. Reference may be made to what has been described above in the examples as appropriate.

In addition, in this modification, the medium supplied to the heat exchanger 91 via the flow path 93 is "hot water 95", but if it is a fluid (heating medium) whose temperature is relatively easy to rise, , but not limited to water. In this case, "hot water generator 90" can be read as "fluid warmer".

The above embodiment and each modification can be realized by appropriately combining them.

As mentioned above in the topic at the beginning, in carbon dioxide recovery systems, it is often required not only to reduce the energy required to desorb carbon dioxide, but also to operate the system at low cost. As exemplified in the above modification, by using sunlight, the cost associated with desorption of carbon dioxide can be further reduced.

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

(First embodiment)
17A and 17B are cross-sectional views schematically showing an example of a carbon dioxide recovery system (hereinafter simply referred to as "recovery system"). 17A corresponds to a scene in which a step of absorbing carbon dioxide contained in the gas G1 to be processed such as the atmosphere (step S2 described later) is executed, and FIG. 17B corresponds to a scene in which a step of desorbing carbon dioxide that has been absorbed (described later) This corresponds to a scene where step S4) is executed.

Moreover, FIG. 18 is a drawing of the collection system of FIG. 17A viewed from a different direction. After describing the configuration of the recovery system 101 with reference to FIGS. 17A, 17B, and 18, a carbon dioxide recovery method executed by the recovery system 101 will be described.

In each of the following figures, an XYZ coordinate system consisting of an X direction, a Y direction, and a Z direction that are perpendicular to each other is also shown as appropriate. Typically, the Z direction is a vertical direction. Based on this definition, FIG. 18 corresponds to a drawing of the collection system shown in FIG. 17A viewed from the Z direction. Note that, as described later, in FIG. 18, illustration of a part of the configuration of the reaction tank 102 is omitted.

As shown in FIG. 17A, the recovery system 101 includes a reaction tank 102, an absorber 103 that is located inside the reaction tank 102 and exhibits carbon dioxide absorption, and a heat source 104 that supplies thermal energy to the absorber 103. Be prepared.

As described above, the absorber 103 is configured to include a carbon dioxide absorbing material that has the property of absorbing carbon dioxide and the property of desorbing the absorbed carbon dioxide by supplying heat H1. The absorber 103 is made of, for example, a granular porous material having pores on its surface, and a carbon dioxide absorbing material is supported in the pores.

The reaction tank 102 includes an absorber 103, a solar heat collecting member 115 (hereinafter simply referred to as "heat collecting member 115") as a heat source 104, and efficiently transfers heat H1 of the heat collecting member 115 to the absorber 103. A heat transfer member 119 for transmitting heat is housed inside. Further, the reaction tank 102 has a light-transmitting part 120 made of a glass material such as quartz glass on the +Z side so that the heat collecting member 115 can receive sunlight C2 (see also FIG. 17B).

In this embodiment, as shown in FIG. 18, a plurality of plate-shaped heat transfer members 119 are arranged in the X direction. Further, from the viewpoint of efficiently transmitting 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 arranged directly with respect to the heat collecting member 115 (Fig. 17B reference). Note that in FIG. 18, for convenience of illustration, the connection portion between the light transmitting part 120, the heat collecting member 115, and the heat transfer member 119 is not shown.

Although this embodiment shows an example in which the heat source 104 is arranged inside the reaction tank 102, the arrangement of the heat source 104 is not limited to this example, as will be described later in the section of the second embodiment.

Next, an example of a method for recovering absorbed carbon dioxide (hereinafter simply referred to as a "recovery method") that can be executed by the recovery system 101 will be described.

FIG. 19 is a flow diagram showing an example of the collection method according to the present invention. This recovery method 101a includes a step S1 of preparing an absorber (hereinafter referred to as "second absorber 103a" for convenience) in a state before absorbing carbon dioxide, and absorbing carbon dioxide into the second absorber 103a. Step S2 of preparing an absorber (hereinafter referred to as "first absorber 103b" for convenience) that has already absorbed carbon dioxide; Step S3 of converting sunlight C2 into heat H1; A step S4 of supplying the heat obtained in S3 to the first absorber 103b, and a gas containing carbon dioxide desorbed from the first absorber 103b by performing S4 (hereinafter referred to as "recovered gas G2" for convenience). It includes a step S5 of collecting.

Note that by performing steps S4 and S5, the first absorber 103b desorbs the absorbed carbon dioxide and then becomes the second absorber 103a. That is, the recovery method 101a can repeat the steps after step S2 after performing step S5.

(Step S1: Preparation of second absorbent body)
First, an absorber (second absorber 103a) in a state before absorbing carbon dioxide is prepared. For example, the second absorbent body 103a is prepared by supporting a carbon dioxide absorption liquid containing an amine-based material on a base material made of a porous material having pores on the surface.

The carbon dioxide absorption liquid is prepared by dispersing an amine-based material in a solvent such as PEG. As an example, when the solvent is PEG, the ratio of the solvent to the amine material is 1:1. Note that alcohol such as methanol may be added to the carbon dioxide absorption liquid depending on the viscosity of the amine material. For example, by mixing methanol, the viscosity of the carbon dioxide absorption liquid containing PEG and amine-based material can be lowered.

FIG. 20A is a cross-sectional view schematically showing the structure of the base material 110. As shown in FIG. 20A, the base material 110 is a solid material having countless pores 111 on its surface. Then, a carbon dioxide absorbing liquid in which an amine-based material is dispersed is brought into contact with this base material 110, and the carbon dioxide absorbing liquid is supported in the pores 111. FIG. 20B is a cross-sectional view schematically showing the structure of the second absorbent body 103a prepared through the above operation. For example, the diameter D12 of the pore 111 is set to 15 nm or less. Note that in FIGS. 20A and 20B, for convenience of illustration, the diameter D12 is exaggerated with respect to the particle diameter D11 of the base material 110.

Further, FIG. 20C is a cross-sectional view schematically showing the structure of the second absorbent body 103a when the diameter D12 is relatively large (for example, about several μm), following FIG. 20B. The diameter D12 is appropriately designed depending on, for example, the surface tension of the carbon dioxide absorption liquid 112 supported in the pores 111 and the carbon dioxide absorption capacity. In addition. From the viewpoint of suppressing the supported carbon dioxide absorption liquid 112 from peeling off from the pores 111, the diameter D12 is preferably 0.1 μm or less.

Furthermore, by adding alcohol such as methanol to the carbon dioxide absorption liquid 112, the viscosity of the carbon dioxide absorption liquid 112 is lowered, so that the carbon dioxide absorption liquid 112 can suitably enter the pores 111. In this case, it is preferable to make the base material 110 support the carbon dioxide absorption liquid 112 and then heat the base material 110 to evaporate the alcohol. For example, the heating condition when methanol is used is about 60°C. Note that when evaporating the alcohol, the base material 110 is preferably placed in a reduced pressure atmosphere of, for example, about 60 kPa.

Furthermore, before the carbon dioxide absorption liquid 112 is supported on the base material 110, the base material 110 may be sprayed with plasma gas or irradiated with ultraviolet rays. Thereby, the hydrophilicity of the surface of the pores 111 included in the base material 110 can be improved, and the carbon dioxide absorption liquid 112 can be suitably supported. Note that the hydrophilic treatment of the surfaces of these pores will be described in detail in the [Verification] section below.

The second absorbent body 103a obtained through the above operation is placed inside the reaction tank 102 (see FIG. 17A).

In this way, the step S1 of preparing the second absorbent body 103a corresponds to the step (d1).

(Step S2: carbon dioxide absorption step)
As shown in FIG. 17A, the gas G1 to be treated containing carbon dioxide is introduced from the inlet 105 into the reaction tank 102 in which the second absorber 103a is located, and brought into contact with the second absorber 103a. FIG. 18 schematically shows how the gas to be treated G1 flows within the reaction tank 102. Thereby, the second absorber 103a absorbs carbon dioxide in the gas G1 to be treated, and the first absorber 103b that has already absorbed carbon dioxide is obtained. Note that, from the viewpoint of easy understanding, in each drawing, the first absorber 103b that has already absorbed carbon dioxide is hatched (see FIG. 17B, etc.). The target gas G1 whose carbon dioxide concentration has decreased due to absorption of carbon dioxide is discharged to, for example, outside space via the discharge port 106.

Note that, as described later, it is assumed that the reaction tank 102 is irradiated with sunlight C2 (step S3). On the other hand, from the viewpoint of efficiently absorbing carbon dioxide by the second absorber 103a, it is preferable that the atmosphere in the reaction tank 102 be kept at a low temperature. Therefore, in step S2, the sunlight C2 irradiated onto the reaction tank 102 may be shielded by an arbitrary shielding member (not shown). Further, the step S2 may be executed during a time period such as nighttime when there is no or little irradiation of sunlight C2.

Examples of the gas to be processed G1 include the atmosphere and exhaust gas from factories. In particular, when the gas to be treated G1 is exhaust gas, the gas to be treated G1 is cooled or screened for substances that inhibit absorption of carbon dioxide contained in the gas to be treated G1 before introducing it into the reaction tank 102. Pre-processing such as

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

(Step S3: convert sunlight into heat)
As mentioned above, energy is required to desorb the absorbed carbon dioxide from the first absorber 103b. Therefore, heat H1 is supplied to the first absorber 103b. The recovery method according to the present embodiment converts sunlight C2 to obtain heat H1 in order to reduce the energy consumed in supplying heat H1.

As shown in FIG. 17B, the heat source 104 is composed of a heat collecting member 115 arranged vertically above the reaction tank 102 (on the +Z side). The heat collecting member 115 absorbs the sunlight C2 taken in from the transparent part 120 and is heated. For example, from the viewpoint of efficiently absorbing sunlight C2, the heat collecting member 115 is typically made of a metal such as aluminum or copper coated with a black color. Further, the heat collecting member 115 may be coated with a black body material such as graphite, which exhibits a high absorption rate for light.

In the example of FIG. 17B, the light-transmitting part 120 is composed of a plurality of transparent members 121 made of a glass material such as quartz glass. Furthermore, a reduced pressure space 122 is formed between these transparent members 121 . The pressure in the low pressure space 122 is, for example, 10 kPa or less, and is typically around 0 atmospheres. Although the low-pressure space 122 is provided in order to make it difficult for the heat H1 converted by the heat collecting member 115 to be transmitted to the +Z side, the present invention is not limited to whether or not the low-pressure space 122 is formed.

The step S3 of converting this sunlight C2 into heat H1 corresponds to step (e).

(Step S4: Supplying heat to the first absorber)
The heat H1 obtained in the above step S3 is supplied to the first absorber 103b. As shown in FIG. 17B, the reaction tank 102 includes a heat transfer member 119 for efficiently supplying the heat H1 of the heat collecting member 115 to the first absorber 103b. Typically, the heat transfer member 119 is placed directly against 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 having a high heat transfer coefficient such as aluminum, copper, or ceramics can be used. Note that the heat transfer member 119 may be integrally made of the same material as the heat collecting member 115.

As shown in FIG. 17B, the heat H1 radiated by the heated heat transfer member 119 is supplied to the first absorber 103b, and the first absorber 103b is heated. That is, in this embodiment, step S3 of converting sunlight C2 into heat H1 and step S4 of supplying heat H1 to the first absorber 103b are automatically executed.

Furthermore, as described above, in order to efficiently proceed with the carbon dioxide desorption reaction, it is preferable to lower the carbon dioxide concentration near the first absorber 103b. Therefore, as shown in FIG. 17B, a desorption-promoting gas B1 such as air or nitrogen gas may be introduced into the reaction tank 102 from the inlet 105 at the same time as the heat H1 is supplied.

Note that in step S4, a heat transfer medium made of fluid may be used to supply the heat H1 to the first absorber 103b, and this configuration will be detailed in the second embodiment later.

In this way, the step S4 of supplying the heat H1 to the first absorber 103b corresponds to step (f).

(Step S5: Recovering the desorbed carbon dioxide)
The recovered gas G2 containing carbon dioxide desorbed in step S4 is sent, for example, to a carbon dioxide utilization facility such as a plant factory via an outlet 106 and a pipe (not shown). In other words, the discharge port 106 corresponds to a "recovery port". However, in the present invention, the destination of the recovered gas G2 is not limited.

In this way, step S5 of recovering carbon dioxide corresponds to step (g).

[Verification 2]
The point that carbon dioxide can be efficiently recovered through the above-mentioned steps S1 to S5 will be explained with reference to Examples. Specifically, using the configuration described with reference to FIGS. 17A, 17B, and 18, a verification was performed to recover carbon dioxide from the atmosphere as the gas to be processed G1.

FIG. 21 is a cross-sectional view schematically showing the experimental system used in this verification, similar to FIG. 17B. In FIG. 21, the execution scene of steps S3 to S5 is illustrated. Since the reaction tank 102 according to this experimental system has the same configuration as that described with reference to FIG. 17A and the like, the above description will be omitted as appropriate. The internal dimensions of the reaction tank 102 used in this verification were 5 cm in length (X direction), 2 cm in width (Y direction), and 0.7 cm in height (Z direction).

As the heat collecting member 115, an aluminum plate member coated with a black body material and having dimensions of 5 cm in length, 2 cm in width, and 0.2 cm in height was installed at a position of 0.5 cm in height.

In this verification, an amine material classified as diamines was used as the carbon dioxide absorbent, and PEG was used as the solvent. That is, the carbon dioxide absorption liquid 112 is a diamine solution adjusted to have a volume ratio of 1:1 with PEG as a solvent.

Granular silica manufactured by Fuji Silysia was used as the solid material supporting the diamine solution. This silica has an average particle size of 1 to 5 mm and a specific surface area of 100 to 200 m ² /g.

First, the weight of the diamine solution was weighed to be several tens of wt% per 1 g of the solid material, and methanol was added to the diamine solution at a constant ratio to prepare a mixed solution. Then, 1 g of solid material was added to this mixed solution and stirred. Stirring was performed in a reduced pressure atmosphere of 50 kPa while heating at about 50°C. In this way, the second absorbent body 103a was obtained by impregnating the solid material with the diamine solution and then heating it under a reduced pressure atmosphere to evaporate methanol.

In addition, in this verification, from the viewpoint of desorbing carbon dioxide absorbed during the adjustment of the second absorber 103a, 0.5 L of nitrogen gas (purity 99.9%) was evaporated after methanol was evaporated. The second absorbent body 103a was heated at 70° C. for several hours while passing the current at a rate of 1/min. Thereafter, by weighing the second absorbent body 103a, the amount of the amine material supported on the solid material was estimated to be 18 wt%.

Several grams of the second absorber 103a obtained through the above operations were placed inside the reaction tank 102. Then, the atmosphere (carbon dioxide concentration is approximately 400 pm) was introduced into the reaction tank 102 at a flow rate of 7.5 mL/min for several tens of hours as the gas G1 to be treated, thereby obtaining the first absorber 103b that had already absorbed carbon dioxide. (Step S2).

Since carbon dioxide is absorbed by the second absorber 103a, the carbon dioxide concentration of the gas G1 to be treated after contacting the second absorber 103a decreases. Thereafter, when the absorption of carbon dioxide by the second absorber 103a is completed (first absorber 103b), the carbon dioxide concentration of the target gas G1 that has passed through the reaction tank 102 is the same as the state before being introduced into the reaction tank 102. It will be about the same level. Therefore, in this verification, it was determined that the second absorber 103a had sufficiently absorbed carbon dioxide when the carbon dioxide concentration of the gas to be treated G1 measured at the latter stage of the exhaust port 106 reached 400 ppm.

In addition, in this verification, sunlight C2 was simulated and the heat collecting member 115 was irradiated with light L1 using the halogen lamp 130 (see FIG. 21). FIG. 22 shows the spectrum of the halogen lamp 130 used in this verification. As shown in FIG. 22, the halogen lamp 130 used in this verification has a peak intensity near 1000 nm, and has a light intensity of 40% or more of the peak intensity in the range of 500 nm to 2000 nm. shows. Note that in this verification, the power input to the halogen lamp 130 was 50W.

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

FIG. 23 is a graph showing the carbon dioxide desorption results of this verification. In FIG. 23, the horizontal axis shows the elapsed time since the halogen lamp 130 was turned on, and the vertical axis shows the carbon dioxide concentration measured at the position of the exhaust port 106.

As shown in FIG. 23, the carbon dioxide concentration of the recovered gas G2 exceeded the typical atmospheric carbon dioxide concentration of 400 ppm (0.04%). This is because the first absorber 103b desorbs carbon dioxide in response to the supply of heat H1 from the heat collecting member 115 heated by the irradiation of the light L1. Further, the carbon dioxide concentration of the recovered gas G2 reached a maximum of about 9600 ppm (0.96%). This is 24 times the carbon dioxide concentration compared to the atmosphere. From this point of view, it can be said that in this verification, carbon dioxide was desorbed suitably from the first absorber 103b.

In this way, it is clear from this verification that at least the light L1 in the wavelength range of 500 nm to 2000 nm is converted into heat H1 and used for desorption of carbon dioxide. On the other hand, it is known that the intensity of sunlight C2 is particularly high in the wavelength range from 500 nm to 2500 nm. In other words, although the light L1 from the halogen lamp 130 was used in this verification, it can be understood that even when the light L1 is replaced with sunlight C2, carbon dioxide can be desorbed suitably.

In addition, in this verification, an amine-based material such as diamines was used as the carbon dioxide absorbing material, but the same argument as above can be made if the material is a carbon dioxide absorbing material that causes a carbon dioxide desorption reaction when thermal energy is supplied. is possible.

[Verification 3]
As described above, in step S1 of preparing the second absorber 103a, before the base material 110 is made to support the carbon dioxide absorbing liquid 112, plasma gas may be sprayed onto the base material 110 or ultraviolet rays may be irradiated on the base material 110. good. The effect of irradiating the base material 110 with ultraviolet rays was verified and will be described below.

Specifically, when preparing the second absorber 103a using the same method as described above in Verification 2, before adding it to the mixed solution, a Xe excimer lamp is used to treat the solid material at a wavelength near 172 nm. Irradiated with ultraviolet light. The ultraviolet irradiation was performed for several seconds at an irradiance of several tens of mW/cm ² .

Thereafter, in the same manner as described above in Verification 2, the second absorber 103a was subjected to treatments such as evaporation of methanol and heating, and the weight of the second absorber 103a was measured to estimate the amount of the amine-based material supported on the solid material. Table 1 below shows the results of comparison with the supported amount obtained in Verification 2, which was not irradiated with ultraviolet rays.

According to Table 1, by irradiating the solid material with ultraviolet rays, the amount of amine-based material supported on the solid material was approximately 1.2 times that in the case without ultraviolet irradiation (verification 2). This is thought to be because hydrophilic functional groups were formed on the pore surfaces of the solid material by ultraviolet irradiation, resulting in improved wettability of the pore surfaces with respect to the carbon dioxide absorption liquid containing the amine-based material.

By increasing the amount of carbon dioxide absorbent supported in the solid material, the carbon dioxide absorption capacity of the absorber can be increased. In addition, as a result of the improved wettability of the pore surface to the carbon dioxide absorption liquid, when the operations related to the carbon dioxide absorption process and desorption process are repeated (see Figure 19), the carbon dioxide absorption from the pore surface is reduced. It is presumed that peeling of the liquid is suppressed. In other words, by supporting the carbon dioxide absorbing liquid after irradiating the solid material with ultraviolet rays, deterioration of the absorber due to peeling off of the carbon dioxide absorbing liquid can be suppressed even if carbon dioxide is repeatedly recovered. Ru. As a result, it is expected that the carbon dioxide recovery capacity will be maintained when looking at the recovery system as a whole.

Hydrophilic functional groups can also be formed on the pore surfaces by spraying plasma gas onto the pores of a solid material. In other words, based on the results of this verification, it is inferred that spraying plasma gas can also make the pore surface hydrophilic and increase the amount of carbon dioxide absorbent supported in the solid material.

As described above, according to the second configuration example of the present invention, by converting sunlight C2 into heat H1, the carbon dioxide recovery efficiency is increased while reducing the input energy amount compared to the conventional method. becomes possible. This will greatly contribute to Goal 13 of the Sustainable Development Goals (SDGs) led by the United Nations, ``Take urgent measures to reduce climate change and its impacts.''

(Second embodiment)
The second embodiment of the second configuration example according to the present invention will be described below, focusing on the differences from the first embodiment.

In the first embodiment, the heat source 104 is placed inside the reaction tank 102, but the heat source 104 can also be placed 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 supplies heat H1 to the first absorber 103b inside the reaction tank 102.

FIG. 24 is a drawing schematically showing the configuration of the second embodiment of the collection system 101, and some components are shown in a block diagram. As shown in FIG. 24, the recovery system 101 according to the present embodiment includes a reaction tank 102, a heat source 104, a first flow path 131 that connects the heat source 104 and the reaction tank 102, and a gas G1 to be processed into the reaction tank 102. A second flow path 132 for introducing gas G1 and the like, and a third flow path 133 located downstream of the reaction tank 102 with respect to the flow direction of the gas to be treated G1 and the like are provided. Note that FIG. 24 illustrates a scene in step S4 (see FIG. 19), in which the atmosphere as the heat transfer medium A1 is introduced into the reaction tank 102 from the first flow path 131.

In this embodiment, atmospheric air sent into the reaction tank 102 by a ventilation mechanism such as a blower fan (not shown) is used as the heat transfer medium A1. Moreover, in this embodiment, the gas G1 to be processed is the atmosphere. For this reason, the recovery system 101 includes a first valve V1 that can control the flow rate of atmospheric air flowing through the second flow path 132, and a second valve V2 that can control the flow rate of atmospheric air that flows through the first flow path 131. , a control unit 108 that controls the opening and closing states of each valve (V1, V2). In FIG. 24, the first valve V1 is in the closed state and the second valve V2 is in the open state. In order to schematically express the open and closed states of the valves, the positions of each valve with respect to the piping are drawn differently. It is.

Additionally, the reaction tank 102 has a thermometer 109 that measures the temperature of the internal space of the reaction tank 102. As described later, the control unit 108 sends signals (d1, d2) to each valve (V1, V2) to adjust the opening degree of the valve, based on temperature information d0 in the reaction tank 102 from the thermometer 109. ) can be sent.

The configuration of this embodiment will be described below with reference to FIGS. 25 to 28. 25 and 26 are cross-sectional views schematically showing the structure of the reaction tank 102, with FIG. 25 corresponding to step S2 and FIG. 26 corresponding to step S4 (see FIG. 19). 27 and 28 are cross-sectional views schematically showing the structure of the heat source 104, and FIG. 28 is a drawing when the heat source 104 according to FIG. 27 is viewed from the Z direction, following FIG. 18.

As shown in FIG. 25, inside the reaction tank 102, the second absorbent body 103a prepared through the above-described step S1 is placed. Then, the second valve V2 is closed and the first valve V1 is opened, and the atmosphere as the gas to be treated G1 is introduced into the reaction tank 102 through the inlet 105b. The first absorber 103b is obtained by the second absorber 103a absorbing carbon dioxide contained in the gas G1 to be treated (step S2).

Next, step S3 is performed by the heat source 104. As shown in FIG. 27, the heat source 104 includes a heating tank 104a, a heat collecting member 115 arranged vertically above (+Z side) of the heating tank 104a, and a heat transfer member arranged directly on the heat collecting member 115. 119, and a transparent part 120 for taking in sunlight C2 inside. Note that, in FIG. 28, for convenience of illustration, some of the light-transmitting part 120, the heat collecting member 115, and the heat transfer member 119 are omitted. Since the heat source 104 has the same structure as the reaction tank 102 according to the first embodiment, the description of the common parts will be simplified.

As shown in FIG. 27, air as the heat transfer medium A1 is introduced into the heating tank 104a through the inlet 105. Then, the heat transfer medium A1 comes into contact with the heat transfer member 119, which has become high in temperature due to the heat H1 converted from the sunlight C2 by the heat collecting member 115, and is heated. Thereafter, the heat transfer medium A1 is discharged from the discharge port 106 and sent into the reaction tank 102 via the first flow path 131. Note that the same discussion as in the first embodiment can be made regarding the transparent portion 120.

In order to increase the contact area between the heat transfer member 119 and the heat transfer medium A1, the heat transfer member 119 is made of, for example, a plate-shaped member, as shown in FIG. They may be arranged substantially perpendicular to the flow direction. From a similar point of view, the flow section 125, which is 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, is It may be configured to overlap the main surface of the heat transfer member 119 located at the rear stage with respect to the flow direction of the heat medium A1. Note that the "principal surface" herein refers to a surface that is much larger in area than other surfaces among the surfaces that the plate-shaped heat transfer member 119 has.

As shown in FIG. 26, atmospheric air as the heat transfer medium A1 heated by the heat source 104 is introduced into the reaction tank 102 in which the first absorber 103b is located via the inlet 105a. This introduction port 105a corresponds to an "introduction port". At this time, typically the second valve V2 is opened and the first valve V1 is closed. In this way, the first absorbent body 103b is brought into contact with the high temperature heat transfer medium A1, and the heat H1 is supplied to the first absorbent body 103b (step S4).

The recovered gas G2 containing carbon dioxide desorbed from the first absorber 103b by the supply of the heat H1 is recovered through the exhaust port 106a (step S5). In other words, this discharge port 106a corresponds to a "recovery port".

Note that in this embodiment, since the atmosphere is used as the heat transfer medium A1, by introducing the heat transfer medium A1 into the reaction tank 102, the carbon dioxide concentration near the first absorber 103b can be lowered. . That is, the atmosphere as the heat transfer medium A1 also functions as a desorption-promoting gas B1 that promotes the desorption of carbon dioxide.

The absorbed carbon dioxide is desorbed by heating the first absorber 103b by the atmosphere as the heat transfer medium A1. However, from the viewpoint of repeatedly using the absorber 103 (see FIG. 19), the first absorber Preferably, thermal effects on 103b are reduced. Therefore, the control unit 108 receives the temperature information d0 from the thermometer 109, and when the temperature inside the reaction tank 102 is equal to or higher than a predetermined value, the control unit 108 sends a signal to the first valve V1 to adjust the opening degree. Send d1. By adjusting the opening degree of the first valve V1, it is possible to introduce atmospheric air that is lower temperature than the heat transfer medium A1, so that the temperature inside the reaction tank 102 can be lowered and the thermal influence on the first absorber 103b can be reduced. In other words, the atmosphere in this case corresponds to "cooling gas." Furthermore, from the viewpoint of promoting cooling of the temperature inside the reaction tank 102, the opening degree of the second valve V2 may be adjusted by transmitting the signal d2 to the second valve V2. Note that the predetermined value may be, for example, 100°C or less, preferably 80°C or less, and more preferably 60°C or less.

In addition, in this embodiment, the control unit 108 adjusts the opening degree of each valve (V1, V2) based on the temperature information d0 from the thermometer 109, and lowers the temperature inside the reaction tank 102 in step S4. explained. However, the control unit 108 opens the first valve V1 and closes the second valve V2 for a predetermined period of time, for example, when the cumulative time during which V2 is in the open state reaches a preset time. It does not matter if it is something that performs control.

In this embodiment, a configuration is shown in which the heat transfer medium A1 introduced into the reaction tank 102 is heated, but as described with reference to FIG. The configuration of the heat source 104 that heats the absorber 103b may be used in combination.

[Another embodiment]
<1> FIGS. 29 and 30 are drawings schematically showing the configuration of another embodiment of the collection system 101, and a part of the configuration is shown in a block diagram. FIG. 29 corresponds to a scene where step S2 is executed, and FIG. 30 corresponds to a scene where steps S4 and S5 are executed.

This embodiment includes a heat exchanger 136 that performs heat exchange between the atmosphere as the heat transfer medium A1 and the recovered gas G2 containing carbon dioxide recovered from the reaction tank 102 (see FIG. 30). The recovery system 101 also includes a fourth flow path 134 that is branched from the third flow path 133 and through which the gas G1 to be treated after passing through the reaction tank 102 flows (see FIG. 29); It has a fourth valve V4 located at. Note that the same discussion as described with reference to FIGS. 25 to 28 can be made regarding the configurations of the reaction tank 102 and the heat source 104.

As shown in FIG. 29, when step S2 is executed, the first valve V1 and the fourth valve V4 arranged in the second flow path 132 are opened, and the reaction tank is opened by a flow mechanism such as a fan (not shown). A gas to be treated G1 is introduced into the chamber 102 . The gas G1 to be treated in which carbon dioxide has been absorbed by the second absorber 103a in the reaction tank 102 is discharged, for example, to the outside space via the fourth flow path 134.

As shown in FIG. 30, in the execution scene of steps S4 and 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 second valve V2 through which the recovered gas G2 flows. The third valve V3 arranged in the third flow path 133 is opened. In this embodiment, as shown in FIG. 30, the atmosphere in the space where plants are grown in the plant factory 135 (hereinafter referred to as "growth space 135a" for convenience) is used as the heat transfer medium A1. Furthermore, the recovered gas G2 containing carbon dioxide desorbed from the first absorber 103b in the reaction tank 102 can be used in the growth space 135a. Since the recovered gas G2 contains carbon dioxide desorbed by heating the first absorber 103b, it has a higher temperature than the atmosphere as the heat transfer medium A1. Therefore, it is preferable to perform heat exchange between the recovered gas G2 and the atmosphere as the heat transfer medium A1.

In addition, in the plant factory 135, it is assumed that the lighting for growth is turned on or off in accordance with the circadian rhythm unique to the plant. That is, while the lighting is turned on, the carbon dioxide concentration in the growth space 135a decreases due to photosynthesis of the plants. Therefore, from the viewpoint of enhancing the effect as the desorption-promoting gas B1 described above, it is preferable to use the atmosphere in the growth space 135a as the heat transfer medium A1. Note that when the carbon dioxide concentration in the growth space 135a is high due to plant respiration etc. (typically while the growth lights are turned off), the atmosphere in another space such as the outside space may be used as a heat transfer medium. It may be used as A1.

<2> In the second embodiment, the atmosphere as the heat transfer medium A1 is introduced into the internal space of the reaction tank 102 in step S4. However, as shown in FIG. 31, heat exchange may be performed between the heat transfer medium A1 flowing outside the reaction tank 102 and the reaction tank 102 in which the first absorber 103b is located inside. FIG. 31 is a diagram schematically showing a part of another configuration example of the collection system 101. 32A is a perspective view schematically showing the configuration of the heat source 104 in FIG. 31, and FIG. 32B is a cross-sectional view of the heat source 104 in FIG. 32A when viewed from the X direction. Note that in FIGS. 32A and 32B, the flow direction of the heat transfer medium A1 is the X direction.

The heat source 104 according to FIG. 32A has an L-shaped cross-sectional shape, for example, as shown in FIG. 32B, and water as the heat transfer medium A1 is accommodated therein. The heat source 104 has a flat heat collecting member 115 on a part of the outer wall surface, and the heat collecting member 115 is heated by absorbing sunlight C2, and high temperature water (hereinafter referred to as "hot water") is heated. generate. Typically, the heat source 104 is placed on an inclined surface such as the pedestal 141 so that the heat collecting member 115 can efficiently receive sunlight C2. The hot water is configured to flow through the flow path 140, and by performing heat exchange between the hot water as the heat transfer medium A1 and the reaction tank 102, it is heated to the first absorber 103b in the reaction tank 102. can supply heat H1.

In addition, at this time, from the viewpoint of reducing the carbon dioxide concentration in the reaction tank 102 and promoting the desorption of absorbed carbon dioxide from the first absorber 103b, for example, from the second flow path 132 as a desorption-promoting gas B1. The atmosphere may be introduced into the reaction tank 102 (see FIG. 31).

<3> In addition, in FIG. 31, an example was described in which heat exchange is performed between hot water as the heat transfer medium A1 flowing through the flow path 140 and the reaction tank 102. However, heat exchange may be performed between the hot water and the atmosphere as the heat transfer medium A1 flowing through the first flow path 131 described with reference to FIGS. 24 and 26. That is, by introducing the atmosphere that has become high temperature through the heat exchange into the reaction tank 102, heat H1 is supplied to the first absorber 103b (see FIG. 26), and absorbed carbon dioxide is desorbed.

<4> The above embodiments can be combined as appropriate. For example, a heat source 104 may be additionally placed inside the reaction tank 102 shown in FIG. 24 or 31. As the configuration of the reaction tank 102, for example, the configuration described with reference to FIG. 17 can be used.

<5> In the above description, the absorber 103 is described as having a granular shape, but as described above, the shape of the absorber 103 is not limited to this, and may be, for example, plate-shaped.

<6> In the above, the absorber 103 has been described as having a solid state, but a liquid carbon dioxide absorption liquid can also be used as the absorber 103. FIG. 33 is a drawing schematically showing another embodiment of the recovery system 101, similar to FIG. 17B. As shown in FIG. 33, by directly arranging the heat transfer member 119 that becomes hot due to the heat H1 of the heat collecting member 115 to the absorber 103 which is in a liquid state, the supply of the heat H1 to the absorber 103 is reduced. It is possible. Note that when carbon dioxide is to be absorbed into the liquid absorber 103 (step S2), the gas G1 to be treated, such as the atmosphere, may be introduced from the inlet 105 and bubbled into the absorber 103.

1: Recovery system 2: Absorption tank 3, 33, 43, 53, 63, 73, 83, 89: Reaction tank 4, 5, 52, 78, 92, 93: Channel 6, 36, 46, 56, 66, 76, 86: Light source 7, 47, 57, 77: Recovery port 8, 38: LED element 9: Substrate 10, 30: Absorbing liquid 11: Reflective film 12, 14: Window 13: Heat transfer member 15, 16: Heat collection Members 16a, 167a, 167b: End portion 20: Processing target gas 21: Post-processing gas 22: Desorption gas 34: Stopper 35a, 35b: Syringe 37: Power source 39: Thermocouple 40: Light shielding plate 41: Current-carrying member 44, 54 : Inlet port 45, 55 : Discharge port 58 : Upper wall part 59 : Bottom wall part 60 : Desorption space 68 : Heat source 74 : Inlet port 79a, 79b, 79c : Valve 84 : Recessed part 87 : Frame 87a : Inclined surface 90 : Hot water generator 91: Heat exchanger 94: Roof 95: Hot water 101: Recovery system 101a: Recovery method 102: Reaction tank 103: Absorber 103a: Second absorber 103b: First absorber 104: Heat source 104a: Heating tank 105 , 105a, 105b: Inlet 106, 106a: Discharge port 108: Control unit 109: Thermometer 110: Base material 111: Pore 112: Carbon dioxide absorption liquid 115: Solar heat collection member 119: Heat transfer member 120: Transparent Light section 121: Transparent member 122: Low pressure space 125: Flow section 130: Halogen lamp 131, 132, 133, 134, 140: Channel 135: Plant factory 135a: Growth space 136: Heat exchanger 141: Frame 161: Outer tube 162: Inner tube 163: Sealing section 164: Sealing space 165: Heat collecting section 166: Heat transfer fins 167: Heat pipe 168: Working fluid 169: Sealing section A1: Heat transfer medium B1: Desorption promoting gas C1: Sun C2: Sunlight G1: Gas to be treated G2: Recovered gas

Claims

a step (a) of irradiating light onto the absorption liquid in which carbon dioxide has been absorbed;
(b) supplying heat to the absorption liquid;
A method for recovering carbon dioxide, comprising a step (c) of recovering carbon dioxide desorbed from the absorption liquid through the steps (a) and (b).
The step (a) is a step of irradiating the absorption liquid with the light from a light source,
The carbon dioxide recovery method according to claim 1, wherein the step (b) is a step of supplying the heat generated by the light source to the absorption liquid.
The method for recovering carbon dioxide according to claim 2, wherein the step (a) and the step (b) are performed simultaneously.
The step (a) includes a step of irradiating the absorption liquid with the light from a light source,
In the step (b), a solar heat collecting member is placed in a state where sunlight can be irradiated, and the solar heat collecting member is placed in contact with the reaction tank in which the absorption liquid is located, either directly or through another member. 2. The carbon dioxide recovery method according to claim 1, further comprising the steps of converting the sunlight into the heat and supplying the heat to the absorption liquid.
The method for recovering carbon dioxide according to claim 1 or 2, wherein the absorption liquid contains a carbon dioxide absorbent made of a basic material and a solvent.
The carbon dioxide recovery method according to claim 5, wherein the carbon dioxide absorbent is made of an amine-based material.
a reaction tank in which an absorption liquid in which carbon dioxide has been absorbed is located;
a light source that is fixed to the reaction tank directly or via another member and irradiates the absorption liquid in the reaction tank with light;
A carbon dioxide recovery system comprising: a recovery port for recovering carbon dioxide desorbed from the absorption liquid.
8. The carbon dioxide recovery system according to claim 7, wherein the light source is located inside the reaction tank.
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,
9. The carbon dioxide recovery system according to claim 7, wherein the absorption liquid is located in the reaction tank and is flowing from the inlet toward the outlet.
The carbon dioxide recovery system according to claim 9, wherein the recovery port is located closer to the outlet than the inlet with respect to the flow direction of the absorption liquid.
The reaction tank has a bottom wall portion and an upper wall portion vertically spaced apart from the bottom wall portion,
The reaction tank is characterized in that the distance between the bottom wall portion and the top wall portion in the vertical direction increases as the inlet approaches the discharge port. Item 9. The carbon dioxide recovery system according to item 9.
The light source is fixedly arranged with respect to the bottom wall,
The top wall part is inclined with respect to the bottom wall part,
12. The carbon dioxide recovery system according to claim 11, wherein the recovery port is provided in the upper wall portion closer to the outlet than the inlet.
The carbon dioxide recovery system according to claim 7 or 8, wherein the absorption liquid includes a carbon dioxide absorbent made of a basic material and a solvent.
The carbon dioxide recovery system according to claim 13, wherein the carbon dioxide absorbent is made of an amine-based material.
a reaction tank in which an absorption liquid in which carbon dioxide has been absorbed is located;
a light source that irradiates light to the absorption liquid in the reaction tank;
a heat source that supplies heat to the absorption liquid in the reaction tank;
A carbon dioxide recovery system comprising: a recovery port for recovering carbon dioxide desorbed from the absorption liquid.
The heat source is a solar heat collection member that converts received sunlight into heat, and is fixed to the reaction tank directly or through another member in a manner that allows sunlight to irradiate. The carbon dioxide recovery system according to claim 15, comprising:
a step (d) of preparing a first absorber which is an absorber that has already absorbed carbon dioxide;
a step (e) of converting sunlight received by the solar heat collecting member into heat;
a step (f) of supplying thermal energy derived from the heat obtained in the step (e) to the first absorber;
A method for recovering carbon dioxide, comprising a step (g) of recovering carbon dioxide desorbed from the first absorber through the step (f).
The step (f) is a step of supplying the thermal energy to the first absorber through a heat transfer medium heated by the heat obtained in the step (e). 18. The carbon dioxide recovery method according to 17.
In the step (f), the heat transfer medium made of air heated by the thermal energy obtained in the step (e) is introduced into the internal space of the reaction tank in which the first absorber is disposed. The method for recovering carbon dioxide according to claim 18, comprising the step of:
During execution of the step (f), the temperature of the internal space of the reaction tank is measured, and if the temperature is equal to or higher than a predetermined value, an atmosphere that is lower temperature than the heat transfer medium is applied to the internal space. The carbon dioxide recovery method according to claim 19, characterized in that a cooling gas consisting of: is introduced.
The step (d) includes:
a step (d1) of preparing a second absorber, which is an absorber before absorbing carbon dioxide;
After arranging the second absorber inside the reaction tank, a step (d2) of introducing a gas to be treated containing carbon dioxide into the internal space of the reaction tank and causing the second absorber to absorb carbon dioxide. 21. The method for recovering carbon dioxide according to claim 19 or 20, comprising:
In the step (d1), a carbon dioxide absorption liquid made of a basic material and exhibiting carbon dioxide absorption property is supported on the pores of a solid material made of a porous material having pores on its surface. 22. The method for recovering carbon dioxide according to claim 21, comprising the step of obtaining a second absorber.
The step (d1) is characterized by including a step of spraying plasma gas or irradiating the pores with ultraviolet rays, before making the pores of the solid material carry the carbon dioxide absorption liquid. The carbon dioxide recovery method according to claim 22.
The step (f) is a step of exchanging heat between the first absorber and the heat transfer medium flowing through the outside of the reaction tank in which the first absorber is disposed,
19. The method according to claim 18, wherein during execution of the step (f), a desorption-promoting gas consisting of a gas having a lower carbon dioxide concentration than the internal space is introduced into the internal space of the reaction tank. The carbon dioxide recovery method described.
a first absorber which is an absorber that has already absorbed carbon dioxide;
a reaction tank in which the first absorber is located;
an introduction port for introducing a heat transfer medium that supplies thermal energy to the first absorber into the reaction tank;
a heat source that heats the heat transfer medium, including a solar heat collecting member that converts received sunlight into heat, and is disposed before the first absorber with respect to the flow direction of the heat transfer medium;
A carbon dioxide recovery system comprising: a recovery port for recovering carbon dioxide desorbed from the first absorber.
comprising a first flow path communicating the heat source and the introduction port,
26. The carbon dioxide recovery system according to claim 25, wherein the heat source is configured to heat the heat transfer medium flowing through the first flow path at a position outside the reaction tank.
a second flow path that guides the atmosphere as a gas to be treated containing carbon dioxide into the reaction tank;
27. The carbon dioxide recovery method according to claim 26, further comprising a first valve capable of controlling the flow rate of atmospheric air flowing through the second flow path by adjusting the opening degree of the second flow path. system.
comprising a thermometer that measures the temperature of the internal space of the reaction tank,
28. The carbon dioxide recovery system according to claim 27, wherein the opening degree of the second flow path in the first valve is adjusted based on the measured value of the thermometer.
28. The carbon dioxide recovery according to claim 27, further comprising a second valve capable of controlling the flow rate of the heat transfer medium flowing through the first flow path by adjusting the opening degree of the first flow path. system.
a third flow path through which recovered gas containing carbon dioxide recovered from the recovery port flows;
A heat exchanger that is disposed upstream of the first absorber with respect to the flow direction of the heat transfer medium and performs heat exchange between the heat transfer medium and the recovered gas flowing through the third flow path. The carbon dioxide recovery system according to any one of claims 25 to 29, characterized in that it comprises:
The carbon dioxide recovery system according to any one of claims 25 to 29, wherein the absorber has a solid state.