Gas recovery method and gas recovery system

Abstract

The present invention relates to a gas recovery method and a gas recovery system for recovering a predetermined gas with low energy. The gas recovery method includes: converting a first liquid into mist; dispersing the mist; bringing the dispersed mist into contact with the gas in the atmosphere as a first contact; bringing droplets of a second liquid into contact with the mist generated by the first contact as a second contact; and recovering droplets generated by the second contact and containing the predetermined gas.

Description

Technical Field

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

[0002] An important issue in the world is to reduce carbon dioxide, which is one of the factors of global warming. Carbon dioxide is mostly emitted from thermal power generation using oil, coal, etc. as energy. Direct air capture (DAC) technology has been developed to reduce the amount of carbon dioxide in the atmosphere by directly recovering the carbon dioxide emitted so far from the atmosphere and storing the recovered carbon dioxide.

[0003] As a method for recovering NOx contained in exhaust gas, Patent Literature (PTL) 1 discusses a technology in which an alkaline aqueous solution is atomized, the mist of the alkaline aqueous solution is mixed with the exhaust gas, and NOx is recovered and fixed by an acid-base reaction using a recovery machine or the like.

[0004] Reference List

[0005] Patent Literature

[0006] PTL1: Japanese Patent Laid-Open No. 2021-23900 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] However, in the technology discussed in Patent Document 1, in order to purify the exhaust gas, a large-scale mechanism and energy are required, the mechanism involving, for example, an atomization process, an oxidation process, a mixing process using a static mixer, and a recoverer for recovering the mist generated by the mixing process.

[0009] The present invention relates to providing a gas recovery method, a gas recovery system and a gas recovery device for recovering a predetermined gas with a small amount of energy.

[0010] Technical solutions to the problem

[0011] The present inventors have conducted intensive research to achieve the above-mentioned object, and as a result, found that the above-mentioned object can be achieved by the constitution of a gas recovery method for recovering a predetermined gas from the atmosphere, thereby completing the present invention. The gas recovery method includes converting a first liquid into mist; spreading the mist; as a first contact, bringing the spread mist into contact with a gas in the atmosphere; as a second contact, bringing droplets of a second liquid into contact with the mist generated by the first contact; and recovering the droplets generated by the second contact and containing the predetermined gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] [ Figure 1 ] Figure 12 is a functional configuration diagram showing a gas recovery system according to the present invention.

[0013] [ Figure 2 ] Figure 2 is a diagram showing a gas recovery flow according to the present invention.

[0014] [ Figure 3 ] Figure 3 is a diagram showing a gas recovery method according to the present invention.

[0015] [ Figure 4A ] Figure 4A It is a diagram showing the outline of the gas recovery method according to the present invention.

[0016] [ Figure 4B ] Figure 4B It is a diagram showing the outline of the gas recovery method according to the present invention.

[0017] [ Figure 4C ] Figure 4C It is a diagram showing the outline of the gas recovery method according to the present invention.

[0018] [ Figure 5A ] Figure 5A is a schematic diagram showing gas recovery through mist.

[0019] [ Figure 5B ] Figure 5B is a schematic diagram showing gas recovery through mist.

[0020] [ Figure 6 ] Figure 6 is a schematic diagram showing gas recovery in an enclosed space.

[0021] [ Fig. 7A ] Fig. 7A is a diagram showing an example of a gas recovery method.

[0022] [ Figure 7B ] Figure 7B is a diagram showing an example of a gas recovery method.

[0023] [ Figure 7C ] Figure 7C is a diagram showing an example of a gas recovery method. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below with reference to desirable exemplary embodiments.

[0025] The present invention is not limited to the following exemplary embodiments. Without departing from the spirit of the present invention, changes and improvements appropriately added to the following exemplary embodiments based on common sense of those skilled in the art are also included in the scope of the present invention.

[0026] <First Exemplary Embodiment>

[0027] The gas recovery system according to the present invention is a recovery system for recovering a predetermined gas, converting a first liquid into mist, spreading the converted mist, bringing the spread mist into contact with a gas, further bringing droplets of a second liquid into contact with the mist, recovering droplets generated by the contact and containing the predetermined gas, thereby recovering the predetermined gas. As described below with reference to the accompanying drawings, the system configuration can be implemented as a gas recovery device including more than one device.

[0028] Figure 1 : is a functional structure diagram of a gas recovery system 1 according to the present invention. The gas recovery system includes a mist generating section 2 for generating mist from a first liquid, a contact section 3 for contacting droplets of a second liquid with mist obtained by a first contact process between the generated mist and a predetermined gas, and a recovery section 4 for recovering droplets generated by the second contact and containing a predetermined gas. The mist generating section 2 includes a mist conversion section 21 for converting the first liquid into mist and a mist spreading section 22 for spreading the converted mist. The mist conversion section 21 and the mist spreading section 22 of the mist generating section 2 can be configured as an integrated device.

[0029] The mist generating unit 2 generates mist from the first liquid. More specifically, as a mechanism for converting the liquid into mist, an ultrasonic irradiation unit is used. The mist generating unit 2 generates fine droplets by ultrasonic vibration generated by using the ultrasonic irradiation unit serving as an atomizing mechanism. The ultrasonic irradiation unit is composed of, for example, a piezoelectric material.

[0030] Piezoelectric materials are widely used in applications such as actuators, ultrasonic vibrators, micro power supplies, and high voltage generating devices. Most of the piezoelectric bodies in these devices are so-called PZT materials, and are oxides containing lead (Pb), zirconium (Zr), and titanium (Ti). For environmental reasons, lead-free piezoelectric materials have been developed. Examples of lead-free piezoelectric materials include Ba-based perovskite oxides represented by the general formula BaM'O3. In this general formula, M' represents a single element or a mixed crystal containing two or more elements in a certain composition ratio, and the charge satisfying the general formula BaM'O3 is neutral. Examples of piezoelectric materials represented by BaM'O3 include BaTiO3 having a tetragonal structure near room temperature. As an ultrasonic irradiation unit, a commercially available unit can be used. Examples of ultrasonic irradiation units include an immersion ultrasonic atomization unit IM1-24 manufactured by SEIKO GIKEN INC. and a wireless fragrance diffuser MJ-CAD1 44486320 manufactured by Ryohin Keikaku Co., Ltd. and sold as a humidifier, but are not limited thereto. The atomizer is also a preferred example of a commercially available ultrasonic atomization generating device. In addition, a form in which the first liquid is separated from the liquid phase of a piezoelectric atomization unit provided with an irradiated ultrasonic wave to be indirectly atomized is preferred. The liquid phase of the atomization unit provided with the irradiated ultrasonic wave is not particularly limited, but is preferably QUAVA mini manufactured by Kaijo Corporation. The frequency of the vibrator is not particularly limited, but is preferably 1.6 MHz. As an example for improving acid resistance, alkali resistance, solvent resistance and corrosion resistance, a form in which the liquid contact member of the piezoelectric element is covered with a fluorine-based resin, a titanium-based member or a glass member such as quartz is also preferred. The mist generating unit 2 is not limited to the above-mentioned mechanism, as long as the mist generating unit 2 generates mist from a liquid.

[0031] The contact part 3 brings droplets of the second liquid into contact with the mist generated by the mist generating part 2 and having been in contact with the gas in the atmosphere. Although the details will be described below, the second liquid that comes into contact with the mist through the contact part 3 is characterized in that it is larger than the mist of the first liquid. As a method of bringing the second liquid into contact with the mist and recovering the first droplets in which a predetermined gas is dissolved, the contact part 3 spreads the liquid from the upper part of the space. A sprinkler nozzle or a spray head, etc. can be used. In order to reduce the amount of the second liquid used, a sprinkler nozzle with a small nozzle is preferred, and an inkjet head, etc. can be used.

[0032] The recovery unit 4 recovers liquid droplets containing a predetermined gas generated by the contact at the contact unit 3 .

[0033] With this configuration, the gas recovery system 1 recovers a predetermined gas with a small amount of energy. There are no particular restrictions on the installation destination and application destination of the gas recovery system 1, as long as there is a gas that can be dissolved in a liquid. In the case where the gas recovery system 1 is applied to the atmosphere, carbon dioxide is recovered by the gas recovery system 1. By applying the gas recovery system 1 to a thermal power plant, etc., particularly effective carbon dioxide recovery is achieved. By setting the gas recovery system 1 in a space where the discharged gas is retained, such as in a tunnel, NOx recovery is achieved.

[0034] The following references Figure 2 The flow of a gas recovery method performed by the gas recovery system according to the present invention is described.

[0035] (Step S201)

[0036] In step S201, the mist conversion unit 21 converts the first liquid into mist. In this step, the mist conversion unit 21 converts the first liquid into mist by using a vibrator irradiated with ultrasonic waves, for example. Figure 3 As described above, the mist converting unit 21 may convert the first liquid into mist by transmitting the vibration of the ultrasonic vibrator 201 to the first liquid. Figure 3 There are shown an ultrasonic vibrator 201 and a first liquid 202 as the mist conversion section 21. In the subsequent process, when a device 301 as the contact section 3 for bringing the second liquid into contact and the second liquid 302 come into contact with each other, liquid droplets in which a predetermined gas is dissolved are recovered.

[0037] The mist conversion unit 21 can convert the first liquid into mist by using a known method such as a method of spraying tiny droplets to be converted into mist. In this method, the size of the converted mist is preferably about 10 μm or less. The mist conversion unit 21 generates a mist with a size of less than 10 μm, and according to the ambient humidity, the mist of the first liquid is retained in the atmosphere for a certain time and space like a cloud. After the processing by the mist conversion unit 21 is completed, the processing proceeds to the next step.

[0038] (Step S202)

[0039] In step S202, the mist spreading unit 22 spreads the mist converted by the mist conversion unit 21 into the atmosphere. The processing of step S201 and the processing of step S202 can be performed as an integrated process. The mist spreading unit 22 can spread the mist into the atmosphere by, for example, blowing air. Alternatively, in the mist conversion process, the mist itself can have a certain speed and be spread. The spreading destination of the mist spreading unit 22 can be appropriately set to, for example, a gas flow path including a partition wall and an opening, a closed space, and the atmosphere. Examples of gas flow paths include tunnels. Figure 4A and Figure 4B The process from fog generation to dispersion is conceptually illustrated.

[0040] After the mist spreading section 22 spreads the mist, the process proceeds to the next step.

[0041] (Step S203)

[0042] In step S203, the gas recovery system 1 brings the spread mist into contact with the gas. The gas recovery system 1 provides a predetermined time interval from the spreading of the mist by the mist spreading section 32 to the recovery, thereby bringing the mist into contact with the gas. The gas recovery system 1 allows the mist to remain in the atmosphere. This is intended to recover the predetermined gas in consideration of changes in the diameter of the mist and the time it takes for the predetermined gas to dissolve in the mist. In the event that the amount of the predetermined gas is insufficient to reach the solubility, the gas recovery system 1 may deliver the atmosphere to promote the dissolution of the predetermined gas to the solubility. After the first contact treatment by the gas recovery system 1 is completed, the process proceeds to the next step.

[0043] (Step S204)

[0044] In step S204, the contact unit 3 brings the droplets of the second liquid into contact with the mist generated by the first contact process. That is, the contact unit 3 performs the second contact process after a predetermined time has passed.

[0045] Figure 4C 3 is a conceptual diagram showing a state in which the contact portion 3 brings the droplets of the second liquid into contact with the mist generated by the first contact process. By bringing the droplets of the second liquid into contact with the mist, the contact portion 3 performs agglomeration of the mist, thereby terminating the retention of the mist in the atmosphere. The droplets represent drops of a liquid including drops each having a small diameter such as droplets.

[0046] Thereafter, the condensed mist falls naturally, and liquid in which a predetermined gas is dissolved is recovered.

[0047] (Step S205)

[0048] The recovery unit 4 recovers the liquid droplets generated by the second contact process of the contact unit 3 and containing the predetermined gas.

[0049] refer to Figure 5A and 5B The recovery of the liquid droplets containing the predetermined gas by the recovery section 4 is described.

[0050] Figure 5A 1 shows a state in which the mist of the liquid is caused to fly and spread into a predetermined gas atmosphere by the processing of steps S201 to S203. The liquid droplets thus flown and spread have a small size. Therefore, the area of ​​the gas-liquid interface per volume is large, and while suspended in the space after flying and spreading, the overall gas components are effectively replaced / exchanged to achieve a balanced concentration, generating a liquid droplet such as Figure 5BIn particular, in the case where the solubility of the gas in the liquid is high, the gas is selectively dissolved to prepare a high concentration of the predetermined gas solution. For example, the solubility of carbon dioxide at a temperature of 20°C is 0.88 cm 3 (relative to 1cm 3 of water). On the other hand, the solubility of nitrogen is 0.016 cm 3 , the solubility of oxygen is 0.031 cm 3 . Therefore, the solubility of carbon dioxide is more than 10 times greater than that of nitrogen and oxygen. Therefore, carbon dioxide is more easily dissolved in the droplets that are blown and dispersed, and blowing and dispersing water into the atmosphere makes it possible to recover carbon dioxide from the atmosphere. Similarly, in spaces with high NOx concentrations such as inside tunnels, NOx can be recovered using its solubility in liquids. Reference Figure 5B The recovery section 4 is described as recovering the liquid droplets containing the predetermined gas.

[0051] (liquid)

[0052] The first liquid used in the mist generating section 2 and the second liquid used in the contacting section 3 in the gas recovery system 1 are described. The first liquid and the second liquid may be the same as or different from each other.

[0053] The first liquid used by the mist generating unit 2 is, for example, water. Considering the ease of extraction of the predetermined gas, the mist generating unit 2 uses water as the first liquid to facilitate dissolution compared to recovery using a strong bond such as an acid-base reaction.

[0054] For example, water with high purity (ultrapure water) purified by reaction, tap water and hard water are candidates for the first liquid used by the mist generating unit 2. The first liquid used by the mist generating unit 2 may contain solutes dissolved in such water (electrolytes formed by dissociation of sodium chloride, silver nitrate, etc., free effective chlorine, amino acids, sugars, buffers, dyes, etc.) and dispersions (pigments, dispersants, cells, bubbles, emulsions, titanium oxide, emulsifiers, etc.). The mist generating unit 2 may use a mixed liquid of water and an organic liquid as the first liquid. The water-soluble organic solvent used in the mist generating unit 2 is not particularly limited, but specific examples of water-soluble organic solvents include the following. Alkyl alcohols having a carbon number of 1 to 4, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol and tert-butanol. Amides, such as N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N,N-dimethylformamide and N,N-dimethylacetamide.

[0055] Ketones or ketone alcohols, such as acetone and diacetone alcohol. Cyclic ethers, such as tetrahydrofuran and dioxane. Diols, such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol and thiodiethylene glycol. Lower alkyl ethers of polyols, 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 glycerol, 1,2,6-hexanetriol and trimethylolpropane. These water-soluble organic solvents may be used alone or in combination of two or more. As the liquid for dissolving the gas, a liquid derived from a living body, such as blood and cerebrospinal fluid, may be used.

[0056] Next, the second liquid used in the contact part 3 is described. The contact part 3 uses water as the second liquid. Considering the influence on the system, the use of water as the second liquid in the contact part 3 helps to recover the predetermined gas. For example, water with high purity (ultrapure water) purified by reaction, tap water and hard water are candidates for the second liquid used in the contact part 3. The second liquid used in the contact part 3 may contain solutes dissolved in such water (electrolytes formed by dissociation of sodium chloride, silver nitrate, etc., free effective chlorine, amino acids, sugars, buffers, dyes, etc.) and dispersions (pigments, dispersants, cells, bubbles, emulsions, titanium oxide, emulsifiers, etc.). The contact part 3 may use a mixed liquid of water and an organic liquid as the second liquid. The water-soluble organic solvent used in the contact part 3 is not particularly limited, but specific examples of the water-soluble organic solvent include the following. Alkyl alcohols having a carbon number of 1 to 4, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol and tert-butanol. Amides such as N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N,N-dimethylformamide and N,N-dimethylacetamide. Ketones or ketoalcohols such as acetone and diacetone alcohol.

[0057] Cyclic ethers, such as tetrahydrofuran and dioxane. Diols, such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol and thiodiglycol. Lower alkyl ethers of polyols, 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 glycerol, 1,2,6-hexanetriol and trimethylolpropane. These water-soluble organic solvents may be used alone or in combination of two or more. As the liquid of the gas dissolving liquid, a liquid derived from a living body, such as blood and cerebrospinal fluid, can also be used. Since the second liquid used in the contact part 3 is used to recover the gas dissolved in the first liquid, the second liquid may not be water but grease or the like. In the case where grease is used as the second liquid in the contact part 3, only the first liquid can be easily separated after recovery.

[0058] Example

[0059] Hereinafter, exemplary embodiments of the present invention are described with reference to the accompanying drawings. The present invention is not limited to the following embodiments within the scope not departing from the gist thereof.

[0060] First embodiment

[0061] The mist conversion unit 21 and the mist spreading unit 22 of the mist generating unit 2 are as follows: Figure 4A As shown, mist is generated using a piezoelectric element 201, more specifically, a piezoelectric atomizing element (1.6 MHz) manufactured by SEIKO GIKEN INC. The piezoelectric element 201 is placed in a beaker having a capacity of 1 liter, and 500 mL of ultrapure water is poured into the beaker.

[0062] The illustrated device is turned on to generate mist. The particle shape of the mist is 10 μm. After the mist is generated until the ultrapure water is exhausted, the recovery container 103 as the recovery unit 4 is placed on 101 and left for 10 minutes. After 10 minutes, the ultrapure water is brought into contact with the mist through the mist shower as the device 102 for bringing the second liquid into contact with the mist, and the resulting liquid is recovered through the recovery container 103. The particle size of the ultrapure water brought into contact with the mist is 50 μm.

[0063] Second embodiment

[0064] Using the same configuration as that described in the first embodiment, as the contact portion 3, an inkjet head was used as a means 301 for bringing the second liquid into contact with the mist. The particle diameter of the second liquid was 30 μm.

[0065] Third embodiment

[0066] like Figure 6 As shown, a closed space including one or more openings communicating with the atmosphere is formed, and the device used in the first embodiment is placed in the closed space, and the application Figure 2 The method shown in the figure is used to generate mist using a mist generating device through a piezoelectric element 201. During this period, the atmosphere is transported from the atmospheric space and contacts the mist. After 5 minutes, ultrapure water is contacted with the mist after a certain degree through a mist shower as a device 102 for contacting a second liquid with the mist, and the resulting liquid is recovered through a recovery container 103.

[0067] Fourth embodiment

[0068] like Figure 7A to Figure 7C As shown, a piezoelectric element is used to generate mist as in the first embodiment, more specifically, a piezoelectric atomizing element (1.6MHz) manufactured by SEIKO GIKEN INC. is used. The piezoelectric element is placed in a beaker with a capacity of 1 liter, and 500mL of ultrapure water is injected into the beaker. The illustrated device is turned on to generate mist. After 10 minutes, the mist of the second liquid is generated by the atomizing device in the same manner as the generation of the mist of the first liquid. At the same time, a recovery container 103 is placed on the power generation element 101. Then, air is transported so that the first mist and the second mist are in contact with each other, and the resulting liquid is recovered by the recovery container 103.

[0069] First Comparative Example

[0070] pass Figure 4A to Figure 4C In the method shown, 1 liter of ultrapure water is applied from the device for bringing the second liquid into contact with the mist, and the resulting liquid is recovered through the recovery container 103.

[0071] When the pH of the water recovered in Examples 1 to 4 was measured by pH test paper, the pH was 5 to 6. The pH of the original ultrapure water was 7. Therefore, it is considered that the carbon dioxide in the air is dissolved and the pH is reduced. The pH of the recovered liquid in the first comparative example is 7. That is, the pH of the droplets obtained by the recovery process is reduced compared to the pH of the second liquid before contact with the mist.

[0072] It was found from the above-mentioned embodiments that in order to recover carbon dioxide in the air, it is necessary to allow sufficiently small mist to remain in the space.

[0073] The present invention is not limited to the above-described exemplary embodiments, and various changes and modifications may be made without departing from the spirit and scope of the present invention. The appended claims disclose the scope of the present invention.

[0074] This application claims priority from Japanese Patent Application No. 2022-097000 filed on June 16, 2022, which is hereby incorporated by reference in its entirety.

Claims

1. A gas recovery method for recovering a predetermined gas from the atmosphere, the gas recovery method comprising: converting the first liquid into mist; spreading the mist; as a first contact, contacting the dispersed mist with a gas in said atmosphere; as a second contact, bringing droplets of a second liquid into contact with the mist generated by the first contact; and Liquid droplets generated by the second contact and containing the predetermined gas are recovered.

2. The gas recovery method according to claim 1, wherein: In the spreading, the mist is spread into a gas flow path including partition walls and openings.

3. The gas recovery method according to claim 1 or 2, wherein the droplets of the second liquid are larger than the mist of the first liquid. The gas recovery method according to claim 1 or 2, wherein the mist is 10 μm or less.

5. The gas recovery method according to claim 1 or 2, wherein the mist is generated by ultrasonic vibration.

6. The gas recovery method according to claim 1 or 2, wherein the gas recovery method is carried out in the atmosphere.

7. The gas recovery method according to claim 1 or 2, wherein the predetermined gas is a gas containing carbon dioxide.

8. The gas recovery method according to claim 1 or 2, wherein the first liquid is a liquid containing water.

9. The gas recovery method according to claim 1 or 2, wherein the second liquid is a liquid containing water.

10. The gas recovery method according to claim 1 or 2, wherein the second contact is performed after a predetermined time has passed from the dispersion of the mist.

11. The gas recovery method according to claim 1 or 2, wherein the pH of the droplets generated by the recovery is lower than the pH of the second liquid before contacting the mist.

12. A gas recovery system comprising: a mist conversion portion configured to convert a first liquid into mist; a mist spreading portion configured to spread the mist; a contact portion configured to bring droplets of the second liquid into contact with mist generated by contacting the dispersed mist with a predetermined gas; and A recovery unit configured to recover liquid droplets generated by the contact and containing a predetermined gas.

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