Carbon dioxide adsorption device and carbon dioxide adsorption method

Abstract

To efficiently adsorb carbon dioxide.SOLUTION: A carbon dioxide adsorption device 100 adopts a two-stage vertical structure in which a chamber lower stage 10 serves as a storage tank for ammonia 11 (ammonia aqueous solution), and a chamber upper stage 20 serves as a filling tank for a porous medium 21. An opening 25 is formed in the bottom surface of the chamber upper stage 20, a first hollow member 30 is inserted into the opening to provide a pinhole structure, thereby allowing ammonia vaporized from the chamber lower stage 10 to gradually permeate into fine voids of the porous medium 21 in the chamber upper stage 20. When the gaseous ammonia dissolves into moisture retained in the fine voids of the porous medium 21, a reaction environment with a large contact area for CO2 gas is formed. A structural body 40 allows the gaseous ammonia to remain for a long period inside the porous medium 21, thereby improving the sustainability of the reaction between ammonia and CO2 gas while suppressing volatilization of gaseous ammonia from the surface layer of the porous medium 21.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a carbon dioxide adsorption device and a method for adsorbing carbon dioxide. [Background technology]

[0002] As a technique using ammonia, for example, techniques such as those described in Patent Document 1 and Non-Patent Document 1 are known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2019-510628 [Non-patent literature]

[0004] [Non-Patent Document 1] Haruo Hikita et al. "Absorption of Carbon Dioxide by Ammonia Aqueous Solution" Chemical Engineering, Vol. 35, No. 9, pp. 1021-1028 Summary of the Invention [Problem to be solved by the invention]

[0005] When carbon dioxide absorption using aqueous ammonia solution in the chemical industry is applied to reducing CO2 emissions as a measure against global warming, power is required to operate equipment and pumps to increase the contact efficiency between the liquid and gas.

[0006] Therefore, an object of the present invention is to provide a technology that can ensure the continuity of the reaction between ammonia and carbon dioxide and efficiently adsorb carbon dioxide, while eliminating the need for power to operate equipment, pumps, etc. [Means for solving the problem]

[0007] The present invention employs the following solutions to solve the above-mentioned problems. Note that the following solutions are merely examples, and the present invention is not limited to these. The present invention can be an invention that includes at least one of the invention-specifying matters shown in the following solutions. Furthermore, each invention-specifying matter shown in the following solutions can be made into a subordinate concept by adding an element that limits the invention-specifying matter, or can be made into a superordinate concept by removing an element that limits the invention-specifying matter.

[0008] Solution 1: The carbon dioxide adsorption device of this solution is a carbon dioxide adsorption device comprising: a storage section in which ammonia is stored; a filling section in which a porous medium is filled; a first supply section that supplies gaseous ammonia from the storage section to the porous medium in the filling section; and a second supply section that supplies carbon dioxide in the atmosphere to the porous medium in the filling section.

[0009] According to this solution, gaseous ammonia and carbon dioxide from the atmosphere are supplied to the porous medium (first supply section, second supply section), and the ammonia and carbon dioxide are reacted inside the porous medium to adsorb the carbon dioxide. This eliminates the need for power to operate equipment, pumps, etc., while ensuring the continuity of the reaction between ammonia and carbon dioxide, enabling efficient adsorption of carbon dioxide.

[0010] Solution 2: The carbon dioxide adsorption device of this solution is a carbon dioxide adsorption device characterized in that, in any of the solutions described above, the porous medium is soil, zeolite, diatomaceous earth, charcoal, hydrogel, or silica gel.

[0011] According to this solution, the porous medium is soil, zeolite, diatomaceous earth, charcoal, hydrogel, or silica gel, so that carbon dioxide can be adsorbed using a simple material.

[0012] Solution 3: The carbon dioxide adsorption device of this solution is a carbon dioxide adsorption device characterized in that, in any of the solutions described above, the first supply section or the second supply section is a hollow tube that tapers from the outside to the inside of the filling section.

[0013] According to this solution, the first supply section or the second supply section is a hollow tube that tapers from the outside to the inside of the filling section, so that gaseous ammonia or atmospheric carbon dioxide can be strongly pushed into the interior of the porous medium.

[0014] Solution 4: The carbon dioxide adsorption device of this solution is any one of the solutions described above, characterized in that the number of the second supply units is greater than the number of the first supply units.

[0015] According to this solution, the number of second supply parts is greater than the number of first supply parts, so the area around the second supply parts is dense, and the effect of suppressing the volatilization of gaseous ammonia can be improved.

[0016] Solution 5: The carbon dioxide adsorption device of this solution is any one of the solutions described above, characterized in that the periphery of the second supply section has irregularities.

[0017] According to this solution, the second supply part has an uneven surface around it, and therefore the surface area increases by the amount of the unevenness, making it possible to secure many places for the gaseous ammonia and carbon dioxide to react with each other.

[0018] Solution 6: The carbon dioxide adsorption device of this solution is a carbon dioxide adsorption device in any of the solutions described above, characterized in that the first supply section and the second supply section are inserted inside the porous medium filled in the filling section.

[0019] According to this solution, the first supply section and the second supply section are inserted into the inside of the porous medium filled in the filling section, so that gaseous ammonia and carbon dioxide can be reliably sent to the inside of the porous medium.

[0020] Solution 7: The carbon dioxide adsorption device of this solution is a carbon dioxide adsorption device characterized in that, in any of the solutions described above, the length of the second supply section placed inside the filling section is longer than the length of the first supply section placed inside the filling section.

[0021] According to this solution, the length of the second supply section disposed inside the filling section is longer than the length of the first supply section disposed inside the filling section, so that ammonia and carbon dioxide can be reacted as close to the bottom as possible of the filling section. Note that the reaction between ammonia and carbon dioxide occurs throughout the entire filling section. Furthermore, by increasing the length of the second supply section, it is possible to promote the diffusion of carbon dioxide into the filling section while suppressing the diffusion of ammonia into the outside air.

[0022] Solution 8: The carbon dioxide adsorption method of this solution is a method for adsorbing carbon dioxide, including a first supply step of supplying gaseous ammonia to a porous medium, a second supply step of supplying carbon dioxide from the atmosphere to the porous medium, and a reaction step of reacting the gaseous ammonia with the carbon dioxide inside the porous medium.

[0023] According to this solution, gaseous ammonia and carbon dioxide from the atmosphere are supplied to a porous medium (first supply step, second supply step), and the ammonia and carbon dioxide are reacted inside the porous medium to adsorb the carbon dioxide (reaction step).This eliminates the need for power to operate equipment, pumps, etc., while ensuring the continuity of the reaction between ammonia and carbon dioxide, making it possible to efficiently adsorb carbon dioxide. [Effects of the Invention]

[0024] According to the present invention, it is possible to ensure the continuity of the reaction between ammonia and carbon dioxide and to efficiently adsorb carbon dioxide, while eliminating the need for power to operate equipment, pumps, etc. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a front view showing a carbon dioxide adsorption device 100 according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing the lower chamber 10. [Figure 3] FIG. 2 is a perspective view showing the upper chamber 20. [Figure 4] FIG. 2 is a perspective view showing the cover member 50. [Figure 5] 2 is a diagram illustrating a first hollow member 30 and a second hollow member 42 in comparison. FIG. [Figure 6] FIG. 2 is a perspective view showing a structure 40. [Figure 7] FIG. 10 is a perspective view showing a structure 40A that is different from the structure 40. [Figure 8] FIG. 10 is an exploded view of a second hollow member 42A of the structure 40A. [Figure 9] FIG. 10 is a diagram showing an auxiliary container 60. [Figure 10] FIG. 1 is a perspective view showing a first mode of use of the carbon dioxide adsorption device 100. [Figure 11] FIG. 2 is a perspective view showing a second mode of use of the carbon dioxide adsorption device 100. [Figure 12] FIG. 1 is a process diagram showing a carbon dioxide adsorption method according to an embodiment. [Figure 13] FIG. 1 is a diagram illustrating an experimental environment. [Figure 14] 10 is a graph showing experimental results. [Figure 15] 10 is a graph showing experimental results. DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment is a preferred example of a carbon dioxide adsorption device, and the present invention is not limited to this example.

[0027] FIG. 1 is a front view showing a carbon dioxide adsorption device 100 according to an embodiment. The carbon dioxide adsorption device 100 is a device that adsorbs (for example, absorbs, converts carbon dioxide into another substance, or fixes) carbon dioxide. The carbon dioxide adsorption device 100 includes a lower chamber 10 (storage section), an upper chamber 20 (filling section), a first hollow member 30 (first supply section), a structure 40, and a cover member 50.

[0028] The lower chamber 10 is a case in which ammonia 11 (aqueous ammonia solution) is stored. The upper chamber 20 can be placed on top of the lower chamber 10 and is a case in which a porous medium 21 is packed. The lower chamber 10 and the upper chamber 20 can be made of a transparent material to make it easier to check the status of the items placed inside (each component, ammonia aqueous solution, porous medium 21, etc.). However, the lower chamber 10 and the upper chamber 20 may also be made of a translucent or opaque material. This also applies to other components such as the first hollow member 30, the structure 40, and the lid member 50.

[0029] The first hollow member 30 is a member that supplies gaseous ammonia from the lower chamber 10 to the porous medium 12 in the upper chamber 20. The first hollow member 30 is a tapered (cone-shaped) capillary that is open at both the front and rear ends, allowing gas to pass through. The first hollow member 30 serves as a passage for sending gaseous ammonia into the porous medium 21.

[0030] The structure 40 can be placed on top of the upper chamber 20, and includes a base member 41 and a second hollow member 42 (second supply section). The base member 41 is a member that supports the second hollow member . The second hollow member 42 is a member that supplies carbon dioxide from the atmosphere to the porous medium 21 in the upper chamber 20. Like the first hollow member 30, the second hollow member 42 is a tapered capillary that is open at both the front and rear ends, allowing gas to pass through. The second hollow member 42 serves as a passageway for sending carbon dioxide from the atmosphere into the porous medium 21.

[0031] The porous medium 21 may be soil, zeolite, diatomaceous earth, charcoal, hydrogel, or silica gel. Alternatively, the porous medium 21 may be a combination of at least two of soil, zeolite, diatomaceous earth, charcoal, hydrogel, and silica gel. Among these, soil is particularly suitable. Because soil has pores ranging from micron-sized to millimeter-sized, ammonia is absorbed into the moisture within the soil and reacts with carbon dioxide within the fine pores. The soil contains microorganisms that release carbon dioxide into the air. However, in this embodiment, ammonia is supplied to the soil, and the toxicity of the ammonia suppresses microbial activity and reduces carbon dioxide emissions, while the ammonia dissolved in the moisture in the soil adsorbs carbon dioxide. Furthermore, soil is a combination of particles of various particle sizes, and compaction eliminates gaps, making it advantageous in terms of suppressing ammonia diffusion to the outside.

[0032] The first hollow member 30 and the second hollow member 42 are hollow tubes that taper from the outside to the inside of the upper chamber 20 .

[0033] The number of the second hollow members 42 is greater than the number of the first hollow members 30. For example, the number of the second hollow members 42 is four, and the number of the first hollow members 30 is 36.

[0034] The first hollow member 30 and the second hollow member 42 are inserted into the porous medium 21 filled in the upper chamber 20 .

[0035] FIG. 2 is a perspective view showing the lower chamber 10. As shown in FIG. The lower chamber 10 comprises a cylindrical box-shaped main body 12 that is open at the top, and an outer protrusion 13 that extends outward from the upper periphery of the side of the main body 12. The lower end of the upper chamber 20 (see FIG. 1) can be fitted into the opening of the main body 12 of the lower chamber 10. The outer protrusion 13 serves as a stopper when the lid member 50 (see FIG. 1) is placed over the lower chamber 10.

[0036] FIG. 3 is a perspective view showing the upper chamber 20. As shown in FIG. The upper chamber 20 basically has the same structure as the lower chamber 10, and like the lower chamber 10, it comprises a cylindrical box-shaped main body 22 that is open at the top, and an outer protrusion 23 that is formed and extends outward from the upper periphery of the side of the main body 22. The outer protrusion 23 serves as a stopper when the lid member 50 (see FIG. 1) is placed over the upper chamber 20.

[0037] Furthermore, a structural body 40 (see FIG. 1) can be placed in the opening of the main body 22 of the upper chamber tier 20. For this purpose, the upper chamber tier 20 is provided with inner protrusions 24 formed at the four inner corners of the upper opening, extending toward the inside of the upper chamber tier 20. The inner protrusions 24 are members for fixing the structural body 40 above the upper chamber tier 20.

[0038] Furthermore, four circular openings 25 are formed in the bottom surface of the upper chamber 20. The tip of the first hollow member 30 is inserted into the openings 25 and fixed.

[0039] FIG. 4 is a perspective view showing the cover member 50. As shown in FIG. The lid member 50 is a flat, cubic member that can be placed over the lower chamber 10 or the upper chamber 20. The lid member 50 is removed when in use. By placing the lid member 50 over the lower chamber 10, it is possible to suppress the diffusion of ammonia 11 when the device is not in use. Furthermore, by placing the lid member 50 over the upper chamber 10, it is possible to prevent the porous medium 21 from diffusing even if the carbon dioxide adsorption device 100 is accidentally toppled.

[0040] 5A and 5B are diagrams illustrating the first hollow member 30 and the second hollow member 42 in comparison. Fig. 5A shows a front view of the first hollow member 30, and Fig. 5B shows a front view of the second hollow member 42. The second hollow member 42 is a member that is thicker than the first hollow member 30. In particular, the opening at the rear end (upper side in FIG. 5) of the second hollow member 42 is wider than the opening at the rear end (upper side in FIG. 5) of the first hollow member 30.

[0041] The second hollow member 42 is longer than the first hollow member 30. Furthermore, the length of the second hollow member 42 disposed inside the upper chamber 20 is longer than the length of the first hollow member 30 disposed inside the upper chamber 20 (see FIG. 1).

[0042] The carbon dioxide adsorption device 100 adsorbs carbon dioxide by supplying gaseous ammonia to the porous medium 21. Liquid ammonia does not easily penetrate the gaps in the porous medium 21 due to the influence of surface tension, but gaseous ammonia easily penetrates the gaps in the porous medium 21. Furthermore, because an aqueous ammonia solution is a liquid and carbon dioxide is a gas, contact efficiency is poor. Furthermore, ammonia has an odor, making it difficult to disperse into the air.

[0043] To improve the contact efficiency between ammonia and carbon dioxide, it is possible to spray ammonia in a mist, but when ammonia is present in the air, it does not react easily with carbon dioxide. Therefore, it is necessary to achieve both the contradictory points of reaction efficiency and preventing ammonia from volatilizing.

[0044] Therefore, in this embodiment, a structure 40 is arranged to generate gaseous ammonia and supply it little by little to the porous medium 21 so as to prevent the gaseous ammonia in the porous medium 21 from volatilizing into the air and to allow the gaseous ammonia in the porous medium 21 to remain in the porous medium 21 for as long as possible.

[0045] Fig. 6 is a perspective view showing the structure 40. Fig. 6(A) shows a perspective view of the structure 40 seen from above, and Fig. 6(B) shows a perspective view of the structure 40 seen from below. The structure 40 includes a base member 41 and a second hollow member 42. The base member 41 is a plate-shaped member and has 36 rectangular openings 43. The second hollow members 42 are inserted into the openings 43 of the base member 41 and fixed therein.

[0046] Fig. 7 is a perspective view showing a structure 40A that is different from the structure 40. Fig. 7(A) shows a perspective view of the structure 40A seen from above, and Fig. 7(B) shows a perspective view of the structure 40A seen from below. Note that the carbon dioxide adsorption device 100 can be provided with either the structure 40 shown in Fig. 6 or the structure 40A shown in Fig. 7.

[0047] The difference between the structure 40 and the structure 40A is that the second hollow members 42 in FIG. 6 are changed to second hollow members 42A in FIG. 7. The number of second hollow members 42A is also changed to half, 18. However, the number of second hollow members 42A can be changed arbitrarily within a range of 1 to 36. The number of second hollow members 42 can also be changed arbitrarily within a range of 1 to 36.

[0048] Figure 8 is an exploded view of the second hollow member 42A of the structure 40A. Figure 8(A) shows a front view of the main body 44, Figure 8(B) shows a front view of the covering member 45, and Figure 8(C) shows a plan view of the covering member 45. The second hollow member 42A includes a main body 44 and a covering member 45. As shown in FIG. 8(A), the main body 44 is a hollow member that is open at both the front and rear ends, allowing gas to pass through. 8(B), the covering member 45 is a member having an uneven surface on its periphery, and is an elastic member such as elastic rubber. As shown in FIG. 8(C), the covering member 45 is a member having eight sets of projections and recesses when viewed from above or below. Then, when the covering member 45 is placed around the main body 44, the second hollow member 42A shown in FIG. 7 is obtained.

[0049] FIG. 9 is a diagram showing the auxiliary container 60. As shown in FIG. An auxiliary container 60 can be attached to the rear end (the lower end in FIG. 1) of the first hollow member 30. Ammonia 11 (see FIG. 1) can be stored inside the auxiliary container 60. The auxiliary container 60 is, for example, a glass bottle. The auxiliary container 60 can be attached to the rear end of the first hollow member 30 by an elastic member 61 such as rubber.

[0050] As a countermeasure when the lower chamber 10 and the upper chamber 20 are made of materials that are susceptible to deterioration by ammonia, the auxiliary container 60 is used, eliminating the need for a sealant to protect the lower chamber 10, etc. Furthermore, by connecting pipes and valves (not shown) to the auxiliary container 60, it becomes possible to supply ammonia simply by opening and closing the valve. Furthermore, when ammonia alone does not react well with carbon dioxide, it is also possible to use the auxiliary container 60 to alternately supply other substances.

[0051] FIG. 10 is a perspective view showing a first mode of use of the carbon dioxide adsorbing device 100. As shown in FIG. In the first mode of use, the structure 40 is used, and the auxiliary container 60 is not used. Specifically, in the first usage mode, the upper chamber 20 equipped with the first hollow member 30 is placed above the lower chamber 10, and the structure 40 is placed above the upper chamber 20. When the carbon dioxide adsorption device 100 is used in the first usage mode, ammonia 11 (see FIG. 1) is stored in the lower chamber 10, and the upper chamber 20 is filled with the porous medium 21 (see FIG. 1).

[0052] FIG. 11 is a perspective view showing a second mode of use of the carbon dioxide adsorbing device 100. As shown in FIG. In the second usage mode, the structure 40A is used, and the auxiliary container 60 is also used. Specifically, in the second usage mode, the upper chamber 20 equipped with the first hollow member 30 and auxiliary container 60 is placed on top of the lower chamber 10, and the structure 40A is placed on top of the upper chamber 20. When the carbon dioxide adsorption device 100 is used in the second usage mode, ammonia 11 (see FIG. 1) is stored in the auxiliary container 60 placed inside the lower chamber 10, and the upper chamber 20 is filled with a porous medium 21 (see FIG. 1). Note that in the first and second usage modes, the lid member 50 (see FIG. 1) is removed.

[0053] FIG. 12 is a process diagram showing the carbon dioxide adsorption method of the embodiment. The carbon dioxide adsorption method includes a first supply step S10, a second supply step S20, and a reaction step S30. The first supply step S10 is a step of supplying gaseous ammonia to the porous medium. Specifically, ammonia stored in the lower chamber 10 or the auxiliary container 60 is vaporized and supplied to the porous medium 21 via the first hollow member 30.

[0054] The second supply step S20 is a step of supplying atmospheric carbon dioxide to the porous medium. Specifically, atmospheric carbon dioxide is supplied to the porous medium 21 via the second hollow member 42. The second supply step S20 may be performed before the first supply step S10, simultaneously with (in parallel with) the first supply step S10, or after the first supply step S10.

[0055] The reaction step S30 is a step of reacting gaseous ammonia with carbon dioxide inside the porous medium. Specifically, gaseous ammonia supplied from the first hollow member 30 and carbon dioxide supplied from the second hollow member 42 are reacted inside the porous medium 21. The reaction between ammonia and carbon dioxide produces ammonium carbonate, which is absorbed by microorganisms.

[0056] The carbon dioxide adsorption device 100 of this embodiment employs a two-tiered structure, with the lower chamber 10 serving as a storage tank for ammonia 11 (aqueous ammonia solution), and the upper chamber 20 serving as a tank filled with porous medium 21. An opening 25 is formed in the bottom surface of the upper chamber 20 (the partition between the upper and lower tiers), and a first hollow member 30 is inserted therein to create a pinhole structure, allowing ammonia volatilized from the lower chamber 10, which serves as an ammonia storage tank, to gradually spread throughout the fine pores of the porous medium 21 in the upper chamber 20. The dissolution of gaseous ammonia in the moisture held in the fine pores of the porous medium 21 creates a reaction environment with a large contact area for CO2 gas.

[0057] Furthermore, in the carbon dioxide adsorption device 100 of this embodiment, by placing the structure 40 on the upper surface of the porous medium 21, the structure 40 serves to suppress the volatilization of gaseous ammonia from the surface layer of the porous medium 21 while retaining the gaseous ammonia inside the porous medium 21 for a long period of time, thereby improving the sustainability of the reaction between ammonia and CO2 gas. Furthermore, because the structure 40 suppresses the diffusion of ammonia to the outside, a special sealing structure is not required.

[0058] FIG. 13 is a diagram showing the experimental environment. Soil was placed in the container 70 as the porous medium 21. A pump 71, a cylinder 72, and a CO2 sensor 73 were connected to the container 70. The experiment started with the CO2 concentration in the laboratory atmosphere, and untreated soil / treated soil was placed in the container 70, and the CO2 concentration was continuously measured with the CO2 sensor 73. During this experiment, air was circulated inside the container 70 by the pump 71. When CO2 was introduced from the cylinder 72, the CO2 concentration was measured with the CO2 sensor 73 while the air inside the container 70 was circulated by the pump 71.

[0059] 14 and 15 are graphs showing the experimental results. FIG. 14 shows the experimental results for untreated soil and treated soil. FIG. 15 shows the experimental results for treated soil and when CO2 was additionally added. Note that untreated soil is soil that has not undergone any treatment. On the other hand, treated soil is soil to which gaseous ammonia has been supplied by the carbon dioxide adsorption device 100 described above.

[0060] As shown by the broken line for untreated soil in Figure 14, when untreated soil is placed in container 70, the CO2 concentration increases over time. Specifically, the CO2 concentration is approximately 480 ppm (initial CO2 concentration in the laboratory) at the initial stage, but after 10 hours it rises to approximately 1000 ppm. This is the result of carbon dioxide being generated from the untreated soil.

[0061] On the other hand, as shown by the broken line for ammonia-treated soil in Figure 14, when treated soil (ammonia-treated soil) was placed in container 70, the CO2 concentration rose for the first hour or so, but after one hour, carbon dioxide generation was suppressed, and thereafter the CO2 concentration gradually decreased, and after six hours it fell below the indoor CO2 concentration (initial concentration) (≒ CO2 adsorption), and thereafter the CO2 concentration continued to decrease. This is the result of the treated soil exerting its effect of suppressing carbon dioxide generation.

[0062] Furthermore, as shown by the broken lines for ammonia-treated soil and CO2 addition in Figure 15, the treated soil was placed in a container 70, and carbon dioxide was pumped into the container 70 using a cylinder 72 (CO2 addition), forcibly increasing the CO2 concentration to approximately 3500 ppm. Even in this environment, the CO2 concentration continued to gradually decrease due to the treated soil. This is the result of the treated soil's ability to adsorb carbon dioxide.

[0063] The carbon dioxide adsorption device 100 of this embodiment can realize the following two "basic system formulations."

[0064] [Reducing CO2 emissions by ammonia-fumigated soil] [Establishment of the basic system (1)] The basic system formulation (1) aims to create soil that does not emit CO2. Basically, soil generates CO2 due to the presence of microorganisms. However, by using the carbon dioxide adsorption device 100, soil that emits CO2 can be converted into soil that does not emit CO2 (see Figure 14).

[0065] [CO2 adsorption by ammonia-fumigated soil] [Establishment of the basic system (2)] The basic system formulation (2) aims to create soil that "adsorbs" CO2. Basically, soil alone cannot adsorb CO2. However, by using the carbon dioxide adsorption device 100, soil that cannot adsorb CO2 can be converted into soil that adsorbs CO2 (see Figure 15).

[0066] The current carbon cycle on Earth is estimated to consist of 760 billion tons of atmospheric carbon stock (weight in carbon equivalent; same below), 60 billion tons / year of emissions from soil, 60 billion tons / year of absorption from the atmosphere into plant biomass, and 7.23 billion tons / year of emissions from fossil fuel combustion (Energy and Economic Statistics Handbook, 2007, by the Institute of Energy Economics, Japan, and the OECD Expert Meeting Report on Soil Organic Carbon, 2002). Furthermore, soil organic carbon stock, based on 500 billion tons of plant biomass, is estimated to be 2 trillion tons (in the top 1 meter of the soil), and the ocean-atmosphere carbon exchange is estimated to be 90 billion tons / year, resulting in an ocean carbon stock of 39 trillion tons (ibid.). As a result, atmospheric carbon stock continues to gradually increase. In view of this situation, by utilizing the carbon dioxide adsorption device 100 described above, it is possible to suppress the generation of carbon dioxide and contribute to suppressing the increase in atmospheric carbon stock (reducing CO2 in the atmosphere).

[0067] As described above, this embodiment has the following advantages. (1) According to this embodiment, gaseous ammonia and atmospheric carbon dioxide are supplied to the porous medium 21, and the ammonia and carbon dioxide are reacted inside the porous medium 21 to adsorb the carbon dioxide. This eliminates the need for power to operate equipment, pumps, etc., while ensuring the continuity of the reaction between ammonia and carbon dioxide, enabling efficient adsorption of carbon dioxide.

[0068] (2) According to this embodiment, the porous medium 21 is soil, zeolite, diatomaceous earth, charcoal, hydrogel, or silica gel, and therefore, carbon dioxide can be adsorbed using a simple material.

[0069] (3) According to this embodiment, the first hollow member 30 or the second hollow member 42 is a hollow tube that tapers from the outside to the inside of the upper chamber 20, so that gaseous ammonia and atmospheric carbon dioxide can be strongly pushed into the porous medium 21. Furthermore, because the first hollow member 30 or the second hollow member 42 has a tapered shape, the supply amount of each gas can be reduced (suppressing excessive supply).

[0070] (4) According to this embodiment, the number of second hollow members 42 is greater than the number of first hollow members 30, which makes the area around the second hollow members 42 denser, thereby improving the effect of suppressing the volatilization of gaseous ammonia. In addition, by pressing the tapered second hollow members 42 into the porous medium 21, the surface soil can be densified, thereby suppressing the emission of ammonia into the atmosphere.

[0071] (5) According to the structure 40A of this embodiment, the covering member 45 having projections and recesses is disposed around the second hollow member 42A, which increases the surface area by the amount of the projections and recesses, making it easier for air containing carbon dioxide to penetrate into the porous medium 21 and ensuring more places for the gaseous ammonia and carbon dioxide to react. Also, if only the main body 44 of the second hollow member 42A were present, the only air hole would be the path connecting the opening at the front end and the opening at the rear end, but by adding the covering member 45, the number of air holes can be increased.

[0072] (6) According to this embodiment, the first hollow member 30 and the second hollow member 42 are inserted into the porous medium 21 filled in the upper chamber 20, so that gaseous ammonia and carbon dioxide can be firmly delivered to the interior of the porous medium 21. However, simply supplying carbon dioxide to the upper surface of the porous medium 21 and ammonia to the lower surface of the porous medium 21 does not significantly promote the reaction. By firmly inserting the first hollow member 30 and the second hollow member 42 into the porous medium 21, the reaction can be promoted.

[0073] (7) According to this embodiment, the length of the second hollow member 42 disposed inside the upper chamber 20 is longer than the length of the first hollow member 30 disposed inside the upper chamber 20, and therefore, ammonia and carbon dioxide can be reacted as close to the bottom as possible inside the upper chamber 20. The reaction between ammonia and carbon dioxide occurs throughout the entire upper chamber 20. Furthermore, by increasing the length of the second hollow member 42, it is possible to promote the diffusion of carbon dioxide into the upper chamber 20 while suppressing the diffusion of ammonia into the outside air.

[0074] (8) According to this embodiment, gaseous ammonia and carbon dioxide from the atmosphere are supplied to the porous medium 21 (first supply step S10, second supply step S20), and the ammonia and carbon dioxide are reacted inside the porous medium 21 to adsorb the carbon dioxide (reaction step S30). This eliminates the need for power to operate equipment, pumps, etc., while ensuring the continuity of the reaction between ammonia and carbon dioxide, allowing for efficient adsorption of carbon dioxide.

[0075] (9) If there is an assumption that soil is a mass of microorganisms, it may seem impossible to reduce carbon dioxide using soil. However, the present embodiment has the advantage of overturning such an assumption and using soil to reduce carbon dioxide.

[0076] (10) Carbon dioxide absorption using aqueous ammonia is often used in various chemical industries in the process of generating raw raw gas (carbonation reaction of ammonia). In this case, the efficiency of the contact reaction between the liquid and the gas is largely determined by the surface area of ​​the liquid. Therefore, methods such as spraying the aqueous ammonia solution with a nozzle or forming a thin film of the solution on the surface of a wall or rod-shaped structure are used. In contrast to these methods, this embodiment employs a method of adsorbing carbon dioxide by ammonia fumigation of the porous medium 21. Vaporized ammonia is added to the porous medium 21, which retains moisture in its fine pores (fumigation treatment), and the ammonia dissolves in the retained moisture. This provides a passive system for adsorbing carbon dioxide without the need for power for pumps or other devices or a sealed structure.

[0077] The present invention is not limited to the above-described embodiment, and can be practiced in various modified forms.

[0078] (1) The first supply section has been described using the example of the opening 25 and the first hollow member 30, but it may be just the opening 25 (pinhole). In this case, the opening 25 may be the same size as the opening at the tip of the first hollow member 30. (2) Concave and convex portions may be formed around the periphery of the main body 44 of the second hollow member 42 or the second hollow member 42A. In this case, the covering member 45 is not necessary. (3) For example, in fields where seasonal horticulture or agriculture is conducted, a carbon dioxide adsorption device 100 is installed in the facility, and although ammonia is normally supplied, in some cases the supply of ammonia can be stopped and the device can be used as a source of carbon dioxide. (4) The above experimental results are merely examples. Similar effects can be obtained by using a material other than soil as the porous medium 21. (5) The shape and number of each component are merely examples and may be changed as desired.

[0079] Furthermore, all of the illustrated embodiments are merely preferred examples, and can be modified as appropriate when implementing the present invention. [Explanation of symbols]

[0080] 10 Lower chamber 11 Ammonia 12 Main body 13 Outer protrusion 20 Upper chamber 21 Porous media 22 Main body 23 Outer protrusion 24 Inner protrusion 25 Opening 30 First hollow member 40, 40A structure 41 Base material 42, 42A Second hollow member 43 Opening 44 Main body 45 Covering material 50 Lid member 60 Auxiliary container 61 Elastic member 100 Carbon dioxide adsorption device

Claims

1. a storage section in which ammonia is stored; a filling section in which a porous medium is filled; a first supply unit that supplies gaseous ammonia from the storage unit to the porous medium in the filling unit; a second supply unit that supplies atmospheric carbon dioxide to the porous medium in the filling unit; A carbon dioxide adsorption device comprising:

2. The carbon dioxide adsorption device according to claim 1, A carbon dioxide adsorption device, wherein the porous medium is soil, zeolite, diatomaceous earth, charcoal, hydrogel, or silica gel.

3. The carbon dioxide adsorption device according to claim 1, The carbon dioxide adsorption device, wherein the first supply section or the second supply section is a hollow tube that tapers from the outside to the inside of the filling section.

4. The carbon dioxide adsorption device according to claim 1, The carbon dioxide adsorption device, wherein the number of the second supply units is greater than the number of the first supply units.

5. The carbon dioxide adsorption device according to claim 1, The carbon dioxide adsorption device is characterized in that the periphery of the second supply section has an uneven surface.

6. The carbon dioxide adsorption device according to claim 1, The carbon dioxide adsorption device, wherein the first supply unit and the second supply unit are inserted into the porous medium packed in the packing unit.

7. The carbon dioxide adsorption device according to claim 1, A carbon dioxide adsorption device, characterized in that the length of the second supply section disposed inside the filling section is longer than the length of the first supply section disposed inside the filling section.

8. a first supply step of supplying gaseous ammonia to a porous medium; a second supply step of supplying atmospheric carbon dioxide to the porous medium; a reaction step of reacting the gaseous ammonia and the carbon dioxide within the porous medium; A method for adsorbing carbon dioxide, comprising:

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