Gas recovery method and gas recovery system

Abstract

To provide a gas collection method and a gas collection system for collecting predetermined gas by using less energy.SOLUTION: A gas collection method includes: a conversion step of converting first liquid into mist; a spraying step of spraying the mist; a contact step of bringing the sprayed mist into contact with gas; a contact step of bringing a droplet formed by second liquid into contact with the mist obtained by the contact step described above; and a collection step of collecting a droplet containing predetermined gas obtained by the contact step described above.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a gas recovery method, a gas recovery system, and a gas recovery device for recovering a predetermined gas from the atmosphere.

Background Art

[0002] Reducing carbon dioxide, which is considered one of the causes of global warming, has become an important global issue. Among them, much of the carbon dioxide emissions are considered to come from thermal power generation that uses energy sources such as oil and coal. Technology development has been carried out to reduce the amount of carbon dioxide in the atmosphere by recovering and storing the carbon dioxide that has been emitted until now by directly capturing carbon dioxide in the atmosphere, called DAC (Direct Air Capture).

[0003] Patent Document 1 discloses a technique for immobilizing NOx as a method for recovering NOx contained in exhaust gas by atomizing an aqueous alkali solution, mixing it with the exhaust gas, and using an acid-base reaction to recover and immobilize it using a recovery device or the like.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the technique described in Patent Document 1, a large-scale mechanism and energy are required for purifying exhaust gas, such as an atomization process, an oxidation process, a mixing process including a static mixer, and a recovery device for recovering the mist generated by the mixing process.

[0006] An object of the present invention is to provide a gas recovery method, a gas recovery system, and a gas recovery device that can recover a predetermined gas with less energy.

Means for Solving the Problems

[0007] The inventors of this invention have conducted extensive research to achieve the above objective, From the atmosphere carbon dioxide Recover and take it out A recovery method, Contains water The first liquid Size less than 10 μm The conversion process to convert it into mist, The aforementioned mist is sprayed in a spraying process, scattered The aforementioned Mist and the air carbon dioxide Bring them into contact The first method of dissolving the carbon dioxide in the mist Contact process and, After the specified time has elapsed The aforementioned First A droplet composed of a second liquid is brought into contact with the mist obtained through the contact process. second Contact process and, The aforementioned second Obtained through the contact process The carbon dioxide We discovered that the above objective can be achieved by configuring a recovery process for collecting droplets containing [the specified substance], and thus completed the present invention. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a gas recovery method and recovery system that can recover a predetermined gas with less energy. [Brief explanation of the drawing]

[0009] [Figure 1] A functional configuration diagram relating to the gas recovery system of the present invention. [Figure 2] A diagram illustrating the gas recovery flow of the present invention. [Figure 3] A diagram illustrating the gas recovery method of the present invention. [Figure 4] A diagram illustrating a schematic example of the gas recovery method of the present invention. [Figure 5] A schematic diagram of gas recovery using mist. [Figure 6] A schematic diagram illustrating gas recovery in a closed space. [Figure 7]A diagram showing an example of a method for recovering a gas.

Mode for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described in detail with reference to preferred embodiments.

[0011] Note that the present invention is not limited to the following embodiments, and modifications and improvements can be appropriately made to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention, and such modified and improved embodiments are also included in the scope of the present invention.

[0012] <First Embodiment> The gas recovery system of the present invention is a recovery system for recovering a predetermined gas. The system converts a first liquid into mist, sprays the converted mist, contacts the sprayed mist with the gas, and further contacts droplets composed of a second liquid. The system recovers the droplets containing the predetermined gas obtained through the contact to recover the predetermined gas. Although the following description will use the accompanying drawings, the system configuration may be realized as a gas recovery device composed of one or more devices.

[0013] FIG. 1 is a functional configuration diagram of the gas recovery system 1 of the present invention. The gas recovery system includes a mist generation unit 2 that generates mist from a first liquid, a contact unit 3 that contacts droplets composed of a second liquid with the mist obtained by contacting the generated mist with a predetermined gas, and a recovery unit 4 that recovers the droplets containing the predetermined gas obtained through the contact. The mist generation unit 2 includes a mist conversion unit 21 that converts the first liquid into mist and a mist spraying unit 22 that sprays the converted mist. Note that the mist conversion unit 21 and the mist spraying unit 22 in the mist generation unit 2 may be configured as an integrated device.

[0014] The mist generation unit 2 generates mist from the first liquid. Specifically, an ultrasonic irradiation unit is used as a mechanism for converting the liquid into mist. The mist generation unit 2 generates fine droplets by ultrasonic vibration using the ultrasonic irradiation unit as the atomization mechanism. The ultrasonic irradiation unit is made of, for example, a piezoelectric material.

[0015] Piezoelectric materials are widely used in applications such as actuators, ultrasonic transducers, micropower supplies, and high-voltage generators. Many of the piezoelectric materials used in these applications are materials known as PZT, which are oxides containing lead (Pb), zirconium (Zr), and titanium (Ti). Therefore, due to environmental concerns, the development of lead-free piezoelectric materials is progressing. An example of a lead-free piezoelectric material is the Ba-based perovskite oxide represented by the general formula BaM'O3. Here, M' represents a mixed crystal of one or more elements in a certain composition ratio, but it is necessary to satisfy the requirement that the charge of the general formula BaM'O3 is neutral. An example of a piezoelectric material represented by BaM'O3 is BaTiO3, which has a tetragonal structure at around room temperature. Commercially available ultrasonic irradiation units can also be used. Examples include, but are not limited to, the IM1-24 immersion ultrasonic atomization unit manufactured by Seikou Giken and the Muji Cordless Aroma Diffuser MJ-CAD1 44486320, which is marketed as a humidifier. Nebulizers are also suitable examples of commercially available ultrasonic atomization devices. It is also preferable to separate the first liquid from the liquid phase equipped with a piezoelectric atomization unit that irradiates it with ultrasound, and indirectly atomize it. There are no particular limitations on the liquid phase equipped with the ultrasonic atomization unit, but Kaijo's Quova Mini is a preferred example. There are no particular limitations on the transducer frequency, but 1.6 MHz is a preferred example. Furthermore, as an example of improving acid resistance, alkali resistance, solvent resistance, and corrosion resistance, it is also preferable to coat the wetted parts of the piezoelectric element with fluorine-based resins, titanium-based materials, or glass materials such as quartz. The mist generation unit 2 only needs to be able to generate mist from the liquid, and is not limited to this mechanism.

[0016] Contact section 3 brings droplets, composed of a second liquid, into contact with mist generated by mist generation section 2 and brought into contact with gas in the atmosphere. The second liquid that contacts contact section 3 is characterized by being larger than the mist composed of the first liquid, as will be described in detail later. Contact section 3 can collect the first droplets containing a predetermined gas by bringing the second liquid into contact with them, by spraying the liquid from above. A watering nozzle or shower head may be used. In order to reduce the amount of second liquid used, a watering nozzle with a small nozzle is preferable, and an inkjet head may also be used.

[0017] The recovery unit 4 recovers the droplets containing a predetermined gas obtained through contact by the contact unit 3.

[0018] The gas recovery system 1, configured in this way, can recover a specified gas with minimal energy. The installation and application locations of the gas recovery system 1 are not particularly limited, as long as there are gases that dissolve in liquid. When the gas recovery system 1 is applied to the atmosphere, carbon dioxide can be recovered. Furthermore, applying the gas recovery system 1 to thermal power plants and the like can particularly effectively recover carbon dioxide. Additionally, by installing the gas recovery system 1 in spaces where exhaust gases accumulate, such as tunnels, NOx can be recovered.

[0019] The flow of the gas recovery method performed by the gas recovery system of the present invention will be explained below with reference to Figure 2.

[0020] (Step S201) In step S201, the mist conversion unit 21 converts the first liquid into mist. Here, the mist conversion unit 21 converts the first liquid into mist using, for example, a transducer that emits ultrasonic waves. Alternatively, as explained in Figure 3, the mist conversion unit 21 may convert the first liquid into mist by transmitting vibrations from an ultrasonic transducer 201 to the first liquid. Figure 3 shows the mist conversion unit 21, which includes an ultrasonic transducer 201 and a first liquid 202. In a later flow, by bringing the contact unit 3, which is a device 301 for contacting the second liquid, into contact with the second liquid 302, droplets in which a predetermined liquid has dissolved can be collected.

[0021] The mist conversion unit 21 may convert the first liquid into mist using a known method, such as a method of discharging minute droplets that can be converted into mist. The size of the mist converted here is preferably about 10 μm or less, and by generating mist of 10 μm or less, the mist conversion unit 21 can retain the mist of the first liquid in the atmosphere for a certain period of time, like a cloud, depending on the ambient humidity. After processing by the mist conversion unit 21 is completed, the process proceeds to the next step.

[0022] (Step S202) In step S202, the mist dispensing unit 22 disperses the mist converted by the mist conversion unit 21 into the atmosphere. Steps S201 and S202 may be performed as a single integrated process. The mist dispensing unit 22 can also disperse the mist into the atmosphere by, for example, applying wind. Alternatively, the mist may be dispersed with a certain velocity due to the mist conversion process. The destination for dispersal by the mist dispensing unit 22 can be appropriately set to, for example, a gas flow path composed of a partition wall and an opening, a closed space, the atmosphere, etc. Examples of gas flow paths include tunnels. Here, Figures 4(a) and 4(b) show a flow chart illustrating the process from mist generation to dispersal.

[0023] The mist dispensing unit 22 proceeds to the next step after dispensing mist.

[0024] (Step S203) In step S203, the gas recovery system 1 brings the dispersed mist into contact with the gas. The gas recovery system 1 ensures contact between the mist and the gas by providing a predetermined time interval between the dispersal of the mist by the mist dispersal unit 32 and its recovery. By allowing the mist to remain in the atmosphere, the gas recovery system 1 can recover a predetermined amount of gas, taking into account variations in the mist diameter and the time it takes for the predetermined gas to dissolve in the mist. If there is not enough of the predetermined gas to reach the solubility level, the gas recovery system 1 may introduce air to accelerate the dissolution to the predetermined gas solubility level. After completing this contact process, the gas recovery system 1 proceeds to the next step.

[0025] (Step S204) In step S204, the contact unit 3 brings a droplet, composed of a second liquid, into contact with the mist obtained through the contact process. That is, the contact unit 3 performs the contact process after a predetermined time has elapsed.

[0026] Figure 4(c) is an illustrative diagram showing that droplets, composed of the second liquid, are brought into contact with the mist obtained through the contact process from the contact section 3. The contact section 3 can condense the mist and prevent it from remaining in the atmosphere through the contact process of bringing the droplets into contact with it. Here, droplets refer to liquid particles, including small particles such as granular droplets.

[0027] The condensed mist can then fall naturally, allowing for the recovery of the liquid containing the specified gas.

[0028] (Step S205) The recovery unit 4 recovers the droplets containing a predetermined gas obtained through the contact process by the contact unit 3.

[0029] Here, using Figure 5, we will explain the collection of droplets containing a predetermined gas by the collection unit 4.

[0030] Figure 5(a) shows the state after steps S201 to S203, where the atomized liquid is airborne and sprayed in a predetermined gaseous atmosphere. Because the airborne and sprayed droplets are minute, the area of ​​the gas-liquid interface per unit volume is large, and as the airborne and sprayed droplets float in the space, the entire gaseous component can be efficiently replaced and exchanged toward equilibrium concentration, resulting in droplets containing the predetermined gas, as shown in Figure 5(b). In particular, if the gas has high solubility in liquid, it can be selectively dissolved to produce a highly concentrated solution of the predetermined gas. For example, carbon dioxide has a solubility of (1 cm³ in water) at 20°C. 3 (compared to) 0.88cm 3 This is the case. On the other hand, nitrogen is 0.016 cm³. 3 Oxygen is 0.031 cm³ 3 Therefore, because its solubility is more than 10 times greater, carbon dioxide dissolves more easily in droplets that are airborne or sprayed, and carbon dioxide in the atmosphere can be recovered by airborne or spraying water into the atmosphere. Similarly, in spaces with high NOx concentrations, such as inside tunnels, NOx can be recovered by utilizing its solubility in liquids. Recovery unit 4 recovers droplets containing a predetermined gas, as explained using Figure 5(b).

[0031] (Regarding liquids) Here, we will explain the first liquid used by the mist generation unit 2 and the second liquid used by the contact unit 3 in the gas recovery system 1. Note that the first liquid and the second liquid may be the same or different.

[0032] The first liquid used by the mist generation unit 2 is, for example, water. By using water as the first liquid, the mist generation unit 2 can perform dissolution that takes into account the ease of extracting a predetermined gas, compared to recovery by strong bonding such as acid-base reactions.

[0033] Furthermore, candidates for the first liquid used by the mist generation unit 2 include highly purified water (ultrapure water) purified by reaction, tap water, hard water, etc. The first liquid used by the mist generation unit 2 may also contain solutes that dissolve in them (electrolytes formed by the dissociation of sodium chloride, silver nitrate, etc., free chlorine, amino acids, sugars, buffers, dyes, etc.), and may also contain dispersions (pigments, dispersants, cells, bubbles, emulsions, titanium dioxide, emulsifiers, etc.). The mist generation unit 2 may also use a mixture of water and an organic liquid as the first liquid. The water-soluble organic solvent used by the mist generation unit 2 is not particularly limited, but specific examples include the following: alkyl alcohols having 1 to 4 carbon atoms, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol. Amides such as N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N,N-dimethylformamide, and N,N-dimethylacetamide. Ketones or keto alcohols such as acetone and diacetone alcohol. Cyclic ethers such as tetrahydrofuran and dioxane. Ethylene glycol, 1,2-propylene glycol, and 1,3-propylene glycol. Glycols such as 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, and thiodiglycol. Lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and triethylene glycol monobutyl ether. Polyalkylene glycols such as polyethylene glycol and polypropylene glycol. Triols such as glycerin, 1,2,6-hexanetriol, and trimethylolpropane.These water-soluble organic solvents may be used individually or in combination of two or more. Furthermore, it is possible to use biological fluids, specifically blood or cerebrospinal fluid, as the liquid in the gaseous solution.

[0034] Next, the second liquid used by the contact part 3 will be explained. The contact part 3 uses water as the second liquid. By using water as the second liquid, the contact part 3 can recover a predetermined gas while considering its effect on the system. Candidates for the second liquid used by the contact part 3 include highly purified water (ultrapure water) purified by reaction, tap water, hard water, etc. The second liquid used by the contact part 3 may also contain solutes that dissolve in them (electrolytes formed by the dissociation of sodium chloride, silver nitrate, etc., free chlorine, amino acids, sugars, buffers, dyes, etc.), and may also contain dispersions (pigments, dispersants, cells, bubbles, emulsions, titanium dioxide, emulsifiers, etc.). The contact part 3 may also use a mixture of water and an organic liquid as the second liquid. The water-soluble organic solvent used by the contact part 3 is not particularly limited, but the following can be given as specific examples. Alkyl alcohols having 1 to 4 carbon atoms, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol. Amides such as N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N,N-dimethylformamide, and N,N-dimethylacetamide. Ketones or keto alcohols such as acetone and diacetone alcohol. Cyclic ethers such as tetrahydrofuran and dioxane. Ethylene glycol, 1,2-propylene glycol, and 1,3-propylene glycol. Glycols such as 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, and thiodiglycol.Lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and triethylene glycol monobutyl ether. Polyalkylene glycols such as polyethylene glycol and polypropylene glycol. Triols such as glycerin, 1,2,6-hexanetriol, and trimethylolpropane. These water-soluble organic solvents may be used alone or in combination of two or more. In addition, it is possible to use a liquid of biological origin, specifically blood or cerebrospinal fluid, as the liquid for the gas dissolution solution. Furthermore, the second liquid used by contact part 3 is intended to recover the gas dissolved in the first liquid, so it does not have to be water; it may be oil or fat. When oil or fat is used as the second liquid in contact part 3, it becomes easier to separate only the first liquid after recovery. [Examples]

[0035] The embodiments of this invention will be described below with reference to the drawings. The present invention is not limited in any way by the following embodiments, unless it exceeds the scope of its essence.

[0036] • Example 1 As shown in Figure 4(a), a piezoelectric element 201 was used for mist generation in the mist conversion unit 21 and mist dispersal unit 22 of the mist generation unit 2. Specifically, a piezoelectric atomizing element (1.6 MHz) manufactured by Seikou Giken was used. It was placed in a 1 L beaker and 500 mL of ultrapure water was poured in. Using the illustrated apparatus, the power was turned on and mist was generated. The mist particle size was 10 μm. After generating mist until the ultrapure water was used up, as shown in Figure 4(c), the recovery unit 4, the recovery container 103, was placed on 101 and left for 10 minutes. After 10 minutes, ultrapure water was brought into contact with the second liquid from the mist shower, which is the device 102 for contacting the second liquid, and collected in the recovery container 103. The particle size of the contacted ultrapure water was 50 μm.

[0037] • Example 2 Using the same configuration as shown in Example 1, an inkjet head was used as the contact part 3 in the second liquid contact device 301. The particle size was 30 μm.

[0038] • Example 3 As shown in Figure 6, a closed space was created with one or more openings that communicate with the atmosphere. The apparatus used in Example 1 was used within the closed space, and the method shown in Figure 2 was applied. Mist was generated using a mist generator with a piezoelectric element 201. During this time, air was introduced from the atmosphere and brought into contact with the mist. After standing for 5 minutes, ultrapure water was brought into contact with the mist using a mist shower, which is a second liquid contact device 102, and collected in a recovery container 103.

[0039] • Example 4 As shown in Figure 7, a piezoelectric element was used to generate the mist, similar to Example 1. Specifically, a piezoelectric atomizing element (1.6 MHz) manufactured by Seikou Giken was used. It was placed in a 1 L beaker and 500 mL of ultrapure water was poured in. Using the illustrated apparatus, the power was turned on and mist was generated. After standing for 10 minutes, a second liquid mist was produced using the same atomizing apparatus as used to generate the mist from the first liquid. At the same time, a recovery container 103 was placed on the power generation element 101. Then, air was blown to bring the first mist and the second mist into contact and collected in the recovery container 103.

[0040] • Comparative Example 1 Using the method shown in Figure 4, 1 liter of ultrapure water was applied from the apparatus for contacting the second liquid and recovered in the recovery container 103.

[0041] When the pH of the water recovered in Examples 1-4 was measured using pH test paper, it was found to be pH 5-6. Since the original ultrapure water had a pH of 7, it is thought that the pH decreased due to the dissolution of carbon dioxide from the air. The pH of the recovered liquid in Comparative Example 1 was 7. In other words, a characteristic feature is that the pH of the droplets obtained after the recovery process is lower than the pH of the second liquid before contact with the mist.

[0042] From the above examples, it is clear that in order to capture carbon dioxide from the air, it is necessary to contain it in a space as a sufficiently small mist. [Explanation of Symbols]

[0043] 2. Mist generation unit 21 Mist conversion unit 22 Mist spraying unit 3 Contact area 4. Recovery section

Claims

1. A method of capturing and extracting carbon dioxide from the atmosphere, A conversion process that converts a first liquid containing water into a mist with a size of 10 μm or less, The aforementioned mist is sprayed in a spraying process, A first contact step involves bringing the sprayed mist into contact with carbon dioxide in the atmosphere to dissolve the carbon dioxide in the mist, A second contact step is performed in which a droplet composed of a second liquid is brought into contact with the mist obtained through the first contact step after a predetermined time has elapsed. A method for recovering carbon dioxide, characterized by comprising a recovery step of recovering the carbon dioxide-containing droplets obtained through the second contact step.

2. The method for recovering carbon dioxide according to claim 1, characterized in that the spraying step involves spraying the mist onto a gas flow path composed of a partition wall and an opening.

3. The method for recovering carbon dioxide according to claim 1 or 2, characterized in that the droplets composed of the second liquid are larger than the mist composed of the first liquid.

4. The method for recovering carbon dioxide according to claim 1 or 2, characterized in that the mist is generated by ultrasonic vibration.

5. A method for recovering carbon dioxide according to claim 1 or 2, characterized in that it is carried out in the atmosphere.

6. The method for recovering carbon dioxide according to claim 1 or 2, characterized in that the second liquid is a liquid containing water.

7. The carbon dioxide recovery method according to claim 1 or 2, characterized in that the first contact step is performed after a predetermined time has elapsed since the spraying of the mist.

8. The method for recovering carbon dioxide according to claim 1 or 2, characterized in that the pH of the droplets obtained through the recovery step is lower than the pH of the second liquid before contact with the mist.

9. A mist conversion unit that converts a first liquid containing water into a mist with a size of 10 μm or less, The mist spraying unit that sprays the aforementioned mist, A contact portion, composed of a second liquid, is used to bring droplets into contact with the mist containing dissolved carbon dioxide, which is obtained by contact between the sprayed mist and carbon dioxide in the atmosphere. A carbon dioxide recovery system characterized by having a recovery unit that recovers carbon dioxide-containing droplets obtained through contact and extracts the carbon dioxide from the liquid consisting of the droplets.

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