Carbon dioxide gas removal device and carbon dioxide gas absorption liquid purification device used therein

Abstract

The present invention provides a carbon dioxide gas removal device capable of repeatedly using an acid component trapping liquid for purifying a carbon dioxide gas absorption liquid, and a carbon dioxide gas absorption liquid purification unit used therein. The carbon dioxide gas removal device is provided with: a carbon dioxide separation and recovery unit that absorbs and recovers a gas to be treated, which contains carbon dioxide gas, using a carbon dioxide absorption liquid containing an amine compound; and a carbon dioxide absorption liquid purification unit for purifying the carbon dioxide absorption liquid by electrodialysis from the carbon dioxide absorption liquid. The carbon dioxide absorption liquid purification unit is provided with: an electrodialysis unit that purifies the carbon dioxide absorption liquid by moving an acid component contained in the carbon dioxide absorption liquid in an acid component collection liquid; and an amine separation unit that separates an amine compound from the acid component collection liquid. And an acid component separation unit that separates an acid component from the acid component collection liquid.

Description

Technical Field

[0001] Embodiments of the present invention relate to a carbon dioxide gas removal device for removing carbon dioxide gas contained in exhaust gas discharged from factories and the like, and a carbon dioxide gas absorbing liquid purification device capable of purifying a carbon dioxide absorbing liquid used in the device. Background Art

[0002] In order to achieve the "2°C target" and "1.5°C effort target" proposed in the Paris Agreement on limiting temperature rise, countries are required to further accelerate climate change countermeasures. Among them, Carbon dioxide Capture, Utilization and Storage (CCUS: Carbon dioxide capture, utilization and storage) is expected to play a major role alongside hydrogen and renewable energy as a measure to reduce emissions of carbon dioxide (CO2), which has a significant greenhouse effect.

[0003] One of the methods for recovering carbon dioxide is the chemical absorption method. The chemical absorption method refers to a method in which waste gas containing carbon dioxide discharged from thermal power plants and iron and steel plants, etc. is brought into contact with an aqueous solution (hereinafter sometimes referred to as an absorption liquid) containing an alkaline compound such as an amino group-containing compound (hereinafter sometimes referred to as an amine compound) to absorb carbon dioxide in the absorption liquid. In the chemical absorption method, carbon dioxide is recovered by repeatedly circulating the absorption liquid between an absorption section in which carbon dioxide is absorbed in the absorption liquid and a regeneration section in which carbon dioxide is released from the absorption liquid. However, when carbon dioxide is absorbed, acid components other than carbon dioxide are also absorbed by the absorption liquid. These acid components, such as NOx, SOx, carbonyl sulfide, hydrogen cyanide, thiocyanic acid, thiosulfuric acid, etc., react with amine compounds in the absorption liquid to generate impurities called heat stable amine salts (Heat Stable Amine Salt: HSAS). In addition, in the recovery section, the amine compounds are decomposed or modified by the heating performed to release carbon dioxide and the reaction between oxygen in the waste gas and the amine compounds, which sometimes promotes the generation of heat stable amine salts. If heat-stable amine salts accumulate in the absorbent, not only will the carbon dioxide absorption efficiency of the absorbent decrease, but it may also cause corrosion of the carbon dioxide recovery device. Therefore, it is desirable to remove the heat-stable amine from the absorbent and inhibit the generation of the heat-stable amine.

[0004] As a kind of technology for removing the acid component that can form the heat-stable amine salt, there is electrodialysis. In the electrodialysis, the ion exchange part stacked with the ion exchange membrane is clamped by electrodes from both ends, and a voltage is applied. At this time, the absorption liquid is contacted with the acid component capture liquid (hereinafter sometimes referred to as the capture liquid) via the ion exchange membrane, so that the acid component in the absorption liquid moves in the capture liquid, that is, the acid component is removed from the absorption liquid. In this system, it is expected to efficiently remove the acid component in the absorption liquid and suppress the leakage of the amine compounds in the capture liquid. On the other hand, by removing the acid component from the absorption liquid, the acid component is continuously accumulated in the capture liquid. If the acid component concentration of the capture liquid exceeds a certain level, the efficiency of removing the acid component from the absorption liquid is reduced. Therefore, it is necessary to appropriately maintain the acid concentration by regularly exchanging or diluting the capture liquid, as a result, there is a problem of generating a large amount of capture liquid waste.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2012-210595

[0008] Patent Document 2: Japanese Patent Application Publication No. 2013-163168 Summary of the invention

[0009] Problems to be solved by the invention

[0010] As described above, in the carbon dioxide separation and recovery system, in the conventional method of removing the acid component from the absorbent by electrodialysis, a large amount of acid waste liquid of the acid component capture liquid is generated. Therefore, it is desired to reuse the acid component capture liquid to reduce the amount of acid waste liquid.

[0011] Means for solving problems

[0012] The carbon dioxide gas removal device of this embodiment is characterized in that it comprises:

[0013] A carbon dioxide separation and recovery unit, which absorbs carbon dioxide gas by bringing a treated gas containing carbon dioxide gas into contact with a carbon dioxide absorbing liquid containing an amine compound, and further recovers carbon dioxide gas from the carbon dioxide absorbing liquid that has absorbed carbon dioxide gas and regenerates the carbon dioxide absorbing liquid for reuse as the carbon dioxide absorbing liquid; and

[0014] a carbon dioxide absorbing liquid refining unit, which removes acid components from the carbon dioxide absorbing liquid by electrodialysis to purify the carbon dioxide absorbing liquid;

[0015] The carbon dioxide absorption liquid purification unit comprises:

[0016] An electrodialysis unit comprising a desalting chamber, a concentrating chamber, and a membrane selected from a cation exchange membrane, an anion exchange membrane, or a bipolar membrane disposed between the desalting chamber and the concentrating chamber between a pair of opposing electrodes, wherein the carbon dioxide absorbing liquid is purified by dissolving the acid component from the carbon dioxide absorbing liquid introduced into the desalting chamber into the acid component capturing liquid introduced into the concentrating chamber;

[0017] an amine separation unit for separating amine compounds contained in the acid component capture liquid; and

[0018] an acid component separation unit for separating the acid component contained in the acid component capture liquid;

[0019] The electrodialysis unit, the amine separation unit, and the acid component separation unit are connected in such a manner that the acid component capture solution can circulate.

[0020] Furthermore, the carbon dioxide absorbing liquid purification unit of the present embodiment is characterized in that it comprises:

[0021] An electrodialysis unit comprising a desalting chamber, a concentrating chamber, and a membrane selected from a cation exchange membrane, an anion exchange membrane, or a bipolar membrane disposed between the desalting chamber and the concentrating chamber between a pair of opposing electrodes, wherein the carbon dioxide absorbing liquid is purified by dissolving the acid component from the carbon dioxide absorbing liquid containing the acid component introduced into the desalting chamber into the acid component capturing liquid introduced into the concentrating chamber;

[0022] an amine separation unit for separating amine compounds contained in the acid component capture liquid; and

[0023] An acid component separation unit that separates the acid component contained in the acid component capture liquid;

[0024] The electrodialysis unit, the amine separation unit, and the acid component separation unit are connected in such a manner that the acid component capture solution can circulate.

[0025] In addition, the carbon dioxide gas removal method of the present embodiment is characterized in that it is a carbon dioxide separation and recovery method, which absorbs carbon dioxide gas by bringing a treated gas containing carbon dioxide gas into contact with a carbon dioxide absorbing liquid containing an amine compound, and then recovering carbon dioxide gas from the carbon dioxide absorbing liquid that has absorbed carbon dioxide gas while regenerating the carbon dioxide absorbing liquid and reusing it as the carbon dioxide absorbing liquid, and comprises the following steps:

[0026] By electrodialysis, the acid component is moved in the acid component capturing liquid to purify the carbon dioxide absorbing liquid;

[0027] Separating the amine compounds contained in the acid component capture solution; and

[0028] The acid component contained in the acid component collection liquid is separated.

[0029] Effects of the Invention

[0030] According to the present embodiment, the acid component captured liquid used for purifying the carbon dioxide gas absorbing liquid used in the carbon dioxide gas removal device can be repeatedly used, and the amount of acid waste liquid can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a conceptual diagram of the carbon dioxide gas removal device according to the first embodiment.

[0032] Figure 2 This is a conceptual diagram of a carbon dioxide gas removal device according to a second embodiment.

[0033] Figure 3 This is a conceptual diagram of a carbon dioxide gas removal device according to a third embodiment.

[0034] Figure 4 This is a conceptual diagram of a carbon dioxide gas removal device according to a fourth embodiment.

[0035] Figure 5 This is a conceptual diagram of a carbon dioxide gas removal device according to a fifth embodiment.

[0036] Figure 6 This is a conceptual diagram of a carbon dioxide gas removal device according to a sixth embodiment.

[0037] Explanation of symbols

[0038] 1: Carbon dioxide gas removal device

[0039] 2: Carbon dioxide separation and recovery unit

[0040] 3: Carbon dioxide absorption liquid refining unit

[0041] 4: Electrodialysis unit

[0042] 4a: Electrode chamber

[0043] 4b: Desalination chamber

[0044] 4c: Concentration Room

[0045] 4d: membrane

[0046] 5: Amine separation unit

[0047] 6: Acid component separation unit

[0048] 7: Acid component capture liquid storage tank

[0049] L1: Absorption liquid introduction pipeline

[0050] L2: Absorption liquid discharge pipeline

[0051] L3: Acid component capture liquid discharge pipeline

[0052] L4: Connecting pipe

[0053] L5: Acid component collection liquid introduction pipeline

[0054] L6: Unrefined acid component collection liquid discharge pipeline

[0055] L7: Refined acid component collection liquid introduction pipeline

[0056] L8: Acid component capture liquid refining circulation pipeline DETAILED DESCRIPTION

[0057] Hereinafter, embodiments for carrying out the invention will be described.

[0058] (First embodiment)

[0059] Figure 1 1 is a conceptual diagram of a carbon dioxide gas removal device according to the first embodiment. Figure 1 As shown, the carbon dioxide gas removal device 1 according to the embodiment includes a carbon dioxide separation and recovery unit 2 and a carbon dioxide absorption liquid purification unit 3 .

[0060] The carbon dioxide separation and recovery unit 2 absorbs carbon dioxide by contacting the processed gas containing carbon dioxide with an absorption liquid containing an amine compound in an absorption unit, and then recovers carbon dioxide from the absorption liquid absorbed by carbon dioxide in a regeneration unit while regenerating the absorption liquid, and reuses it as a carbon dioxide absorption liquid. Therefore, the absorption liquid circulates between the absorption unit and the regeneration unit (not shown) contained in the carbon dioxide separation and recovery unit. Such a carbon dioxide separation and recovery unit 2 can be arbitrarily selected and used from commonly known carbon dioxide separation and recovery units.

[0061] The carbon dioxide absorption liquid refining unit 3 purifies the absorption liquid discharged from the carbon dioxide separation and recovery unit 2 by removing the acid component, and discharges a part of the generated absorption liquid to the carbon dioxide separation and recovery unit 2. That is, a part of the absorption liquid circulating inside the carbon dioxide separation and recovery unit 2 flows into the carbon dioxide absorption liquid refining unit 3 through the absorption liquid introduction line L1, and the purified absorption liquid flows out to the carbon dioxide separation and recovery unit 2 through the absorption liquid discharge line L2. As a result, the carbon dioxide separation and recovery unit 2 and the carbon dioxide absorption liquid refining unit 3 are connected in a manner that the circulating liquid circulates between them.

[0062] The carbon dioxide absorption liquid purification unit 3 includes an electrodialysis unit 4 , an amine separation unit 5 , and an acid component captured liquid separation unit 6 .

[0063] The electrodialysis unit 4 includes a pair of electrodes 4a facing each other and a desalting chamber 4b and a concentrating chamber 4c disposed therebetween. In addition, a membrane 4d selected from a cation exchange membrane, an anion exchange membrane or a bipolar membrane is disposed between the desalting chamber 4b and the concentrating chamber 4c, so that the absorbent introduced into the desalting chamber can be indirectly contacted with the acid component collecting solution introduced into the concentrating chamber.

[0064] Furthermore, in Figure 1 In FIG. 1 , an electrodialysis unit including three desalting chambers and three concentrating chambers is shown. However, at least one desalting chamber and one concentrating chamber may be provided, and two or four or more desalting chambers and concentrating chambers may be provided.

[0065] In the embodiment, part or all of the absorbent circulating in the carbon dioxide separation and recovery unit 2 is supplied to the carbon dioxide absorption liquid purification unit 3 via the absorbent introduction line L1.

[0066] In the carbon dioxide separation and recovery unit, carbon dioxide is introduced into the absorption liquid by bringing the gas containing carbon dioxide (processed gas) into contact with the absorption liquid. The processed gas is, for example, the combustion exhaust gas discharged from the boilers and turbines of thermal power plants, process exhaust gas generated in iron and steel plants, and combustion exhaust gas generated in cleaning plants. Preferably, the processed gas is supplied to the carbon dioxide separation and recovery unit after being cooled by a cooler, etc. and subjected to treatments such as desulfurization and denitrification. By subjecting the non-processed gas to desulfurization and denitrification treatments, the formation of heat-stable amine salts in the absorption liquid can be suppressed, and the load on the carbon dioxide absorption liquid refining unit 3 can be reduced.

[0067] The absorbing liquid generates carbonates when absorbing carbon dioxide in the treated gas (the following formula (1)). At the same time, it also absorbs SOx, NOx, carbonyl sulfide, hydrogen cyanide, thiocyanic acid, thiosulfuric acid, other inorganic acids, etc. contained in the treated gas to generate heat-stable amine salts (the following formula (2)). At this time, organic acids such as formic acid and acetic acid are generated in the absorbing liquid by reacting with the oxygen contained in the treated gas and the components of the absorbing liquid, and sometimes they react with amine compounds to form heat-stable amine salts.

[0068] R3N+CO2+H2O→R3NH2CO3 (1)

[0069] R3N+HX→R3NHX (2)

[0070] Here, R represents hydrogen, a substituted or unsubstituted alkyl group (which may also form a heterocyclic ring), etc., and HX is an acid component such as sulfuric acid and nitric acid that can form a thermally stable amine salt. In this embodiment, the acid component refers to an acid compound other than carbon dioxide or carbonic acid that can form a thermally stable amine salt.

[0071] Furthermore, the absorption liquid is preferably an aqueous solution containing an amine compound and water. Preferred amine compounds include, for example:

[0072] (Ⅰ) Primary amines such as monoethanolamine and 2-amino-2-methyl-1-propanol;

[0073] (II) Secondary amines such as diethanolamine and 2-methylaminoethanol;

[0074] (III) tertiary amines such as triethanolamine and N-methyldiethanolamine;

[0075] (IV) polyethylene polyamines such as ethylenediamine, triethylenediamine, and diethylenetriamine;

[0076] (V) Cyclic amines such as piperazines, piperidines, and pyrrolidines;

[0077] (VI) polyamines such as xylylenediamine;

[0078] (VII) Amino acids such as methylaminocarboxylic acid, etc.

[0079] These amine compounds may be used alone or in combination of two or more.

[0080] The absorbing liquid is used as an aqueous solution containing 10 to 70% by weight of these amine compounds. In addition, the absorbing liquid may contain other compounds such as a reaction accelerator, a nitrogen-containing compound for improving the absorption performance of acidic gases such as carbon dioxide, an antiseptic for preventing corrosion of production equipment, a defoaming agent for preventing foaming, an antioxidant for preventing deterioration of the absorbing liquid, a pH adjuster, etc., as needed, within a range that does not impair the effect of the absorbing liquid.

[0081] The absorbent having absorbed carbon dioxide gas is separated by a regeneration tower or the like generally arranged in a carbon dioxide separation and recovery unit, and is further refined by an electrodialysis unit of the embodiment and reused. However, since the generated heat-stable amine salt is not removed in a common carbon dioxide separation and recovery unit, the heat-stable amine salt tends to accumulate in the absorbent.

[0082] In this embodiment, the heat-stable amine salt can be removed and purified by subjecting part or all of the absorbent to electrodialysis in the carbon dioxide absorbent purification unit 3. The absorbent from which the acid component is removed in the electrodialysis unit 3 is returned to the carbon dioxide separation and recovery unit via the absorbent discharge line L2.

[0083] In the first embodiment, the carbon dioxide absorption liquid purification unit 3 is provided with an electrodialysis unit 4, an amine separation unit 5 and an acid component separation unit 6. The capture liquid flows between the devices by a pump (not shown) arranged at an arbitrary position. The absorption liquid is supplied to the electrodialysis unit 4 from the absorption liquid introduction line L1, and the capture liquid is supplied from the capture liquid introduction line L4. By applying a voltage to the electrodes 4a located at both ends of the electrodialysis unit 4, the acid component of the heat-stable amine salt in the absorption liquid can be removed. The electrodialysis unit, for example, has an anode and a cathode at both ends, and a membrane 4d such as a cation exchange membrane, an anion exchange membrane or a bipolar membrane is arranged between the desalting chamber 4b and the concentrating chamber 4c.

[0084] As the cation exchange membrane, a polymer membrane having a cation exchange group that allows cations to pass and blocks anions from passing is used. For example, a membrane formed by a polymer having one or more of a sulfonic acid group, a carboxylic acid group, a phosphonic acid group, a sulfate group, and a phosphate group can be used. As a preferred cation exchange membrane, specifically, known cation exchange membranes such as Neoceptor CMX, Neoceptor CMB (manufactured by ASTROM Co., Ltd., trade name), SELEMION CMV, SELEMION CMD, SELEMION CSO, and SELEMION CMF (manufactured by AGC Engineering Co., Ltd., trade name) can be used.

[0085] As anion exchange membrane, use a polymer membrane with anion exchange group that can make anions pass through and block cations from passing through. For example, a membrane formed by a polymer having weakly basic functional groups such as primary amino, secondary amino, and tertiary amino in the strong basic group of a quaternary ammonium group, etc. can be used. As a preferred anion exchange membrane, specifically, known anion exchange membranes such as Neoceptor AMX, Neoceptor AHA (manufactured by ASTROM Co., Ltd., trade name), SELEMION AMV, SELEMION AMT, SELEMION DSV, SELEMION ASV, SELEMION AHO (manufactured by AGC Engineering Co., Ltd., trade name) can be used.

[0086] The bipolar membrane is a composite membrane formed by stacking an anion exchange membrane and a cation exchange membrane, and is configured in such a way that the anode side is an anion exchange membrane and the cathode side is a cation exchange membrane. If a voltage is applied above the theoretical decomposition voltage of water in the presence of water, water can be electrolyzed into hydrogen ions and hydroxide ions. As a preferred bipolar membrane, specifically, a known bipolar membrane such as Neoceptor BP-1E (manufactured by ASTROM Co., Ltd., trade name) can be used.

[0087] The collecting solution can be any aqueous solution with an electrical resistance capable of electrodialysis, but by containing a small amount of acid components in the initial stage of operation, the amount of amines that can be present as cations in the collecting solution can be increased, thereby increasing the amount of amine recovery, which is more preferred. As the acid components, for example, sulfuric acid, nitric acid, formic acid, acetic acid, etc. can be used. In addition, if the collecting solution is circulated, the acid components removed from the absorbing solution continue to accumulate, so by setting it to only add the acid components to the collecting solution in the initial stage of operation and not adding such an operation thereafter, the generation of unnecessary thermally stable amine salts can be suppressed, and the usage of the added acid components can also be reduced, which is therefore preferred.

[0088] The collected liquid discharged from the electrodialysis unit 4 is supplied to the amine separation unit 5 via the acid component collected liquid discharge line L3. The amine separation unit 5 has a function of mainly separating amine compounds from the components contained in the collected liquid. The separation method of the amine compounds is not particularly limited, and reverse osmosis, ultrafiltration, electrodialysis, ion exchange resin, etc. can be used.

[0089] The captured liquid from which the amine compounds are separated in the amine separation unit 5 is supplied to the acid component separation unit 6 via the connecting line L4. The acid component separation unit 5 has a function of mainly separating acid components from the components contained in the captured liquid.

[0090] The method for removing the acid component from the captured liquid is not particularly limited, but a method can be adopted by forming a salt with the acid component as a base and then removing the neutralizing salt. For example, by adding an alkaline compound having an alkali metal or an alkaline earth metal as a cation to the captured liquid, the acid component and the neutralizing salt in the captured liquid can be generated. By removing the neutralizing salt, the acid component can be removed from the captured liquid. The input of the alkaline compound can also be carried out manually, but it is also possible to further set an alkaline compound input unit in the carbon dioxide removal device.

[0091] As a method for removing the generated neutralization salt, after adding the alkaline compound, the solubility of the neutralization salt is reduced by cooling to a low temperature, for example, below 0°C, so that it can be precipitated. As the alkaline compound that can be added, specifically, KOH, NaOH, Ca(OH)2, Mg(OH)2, etc. are preferred. The acid components in the capture liquid sometimes contain a variety of inorganic acids from exhaust gas and organic acids from amine compounds, so it is preferred to select the alkaline compound to be added according to the acid components present. For example, when the neutralization salt is potassium nitrate and sodium formate, its solubility and the soluble concentration in water calculated from the solubility are shown in Table 1.

[0092] Table 1

[0093]

[0094] The captured liquid generated by removing the acid component in the acid component separation unit 6 is introduced into the electrodialysis unit 4 through the acid component captured liquid introduction line L5 and is used again to remove the acid component.

[0095] (Second embodiment)

[0096] Figure 2 This is a conceptual diagram of a carbon dioxide gas removal device according to the second embodiment. The main difference between this embodiment and the first embodiment is the order of the amine separation unit 5 and the acid component collection liquid separation unit 6 .

[0097] In this embodiment, the liquid is sent from the electrodialysis unit 4 to the acid component separation unit 6, and after the acid is separated, the amine compounds are separated by the amine separation unit 5. In the method of separating amine compounds by the amine separation unit, this embodiment is preferably applied when the concentration of the acid component is previously reduced and the amine compounds can be removed efficiently.

[0098] (Third embodiment)

[0099] Figure 33 is a conceptual diagram of a carbon dioxide gas removal device according to the third embodiment. The main difference between this embodiment and the first embodiment is that it is equipped with an acid component captured liquid storage tank 7. The electrodialysis unit 4 and the acid component captured liquid storage tank 7 are connected together by an acid component captured liquid discharge pipeline L3 and an acid component captured liquid introduction pipeline L5. The captured liquid circulates between the electrodialysis unit 4 and the acid component captured liquid storage tank 7, and in the electrodialysis unit 4, the acid component concentration in the captured liquid is increased by moving the acid component in the captured liquid. On the other hand, the acid component captured liquid storage tank 7, the amine separation unit 5 and the acid component separation unit 6 are connected together by an unrefined acid component captured liquid discharge pipeline 6, a connecting pipeline L4 and a refined acid component captured liquid introduction pipeline, and a part of the captured liquid stored in the acid component captured liquid storage tank 7 circulates between these pipelines. In addition, the captured liquid circulating in the electrodialysis unit 4 and the captured liquid circulating in the amine separation unit 5 and the acid component separation unit 6 can be circulated at independent flow rates respectively. Therefore, it is easier to use than the first or second embodiment which does not include the acid component captured liquid storage tank 7. For example, in the acid component separation unit, when a neutralized salt is formed and a precipitate is generated by cooling, the circulation of the captured liquid can be stopped during cooling, and the retained captured liquid can be cooled. In addition, while measuring the acid component concentration, amine compound concentration, etc. of the circulating captured liquid, the flow rate of the captured liquid circulating in the electrodialysis unit and the flow rate of the captured liquid circulating in the amine separation unit 5 and the acid component separation unit 6 can be independently adjusted in a manner to optimally purify the absorbent.

[0100] (Fourth embodiment)

[0101] Figure 4 This is a conceptual diagram of a carbon dioxide gas removal device according to the fourth embodiment. The main difference between this embodiment and the first embodiment is that the order of the amine separation unit 5 and the acid component capture liquid separation unit 6 is reversed. This embodiment is similar to the second embodiment, and in the method of separating amine compounds by the amine separation unit, it is preferably applied when the concentration of the acid component is low and the amine compound can be removed efficiently.

[0102] (Fifth embodiment)

[0103] Figure 5This is a conceptual diagram of a carbon dioxide gas removal device according to the fifth embodiment. The main difference between this embodiment and the first embodiment is that an acid component captured liquid storage tank 7 is provided in series with the amine separation unit 5 and the acid component captured liquid separation unit 6. In such a configuration, the flow rate of the circulating captured liquid can be adjusted by increasing or decreasing the captured liquid stored in the acid component captured liquid storage tank. In this method, the range of the flow rate adjustment of the captured liquid is reduced, but if compared with the third or fourth embodiment, the configuration of the device can be simplified. According to this method, liquid can be directly fed from the acid component captured liquid separation unit to the electrodialysis unit. In addition, since the captured liquid after the acid component is separated is supplied to the electrodialysis unit, it is believed that the removal efficiency of the acid component in the electrodialysis unit can be improved.

[0104] In the fifth embodiment, the connection order of the amine separation unit 5 , the acid component captured liquid separation unit 6 , and the acid component captured liquid storage tank 7 is not particularly limited, and they can be connected in any order.

[0105] (Sixth embodiment)

[0106] Figure 6 This is a conceptual diagram of a carbon dioxide gas removal device according to the sixth embodiment. This embodiment is different from the fifth embodiment in that the once-purified captured liquid is circulated to the acid component captured liquid storage tank 7 through the refined acid component captured liquid circulation pipeline. According to such a structure, the purified captured liquid with less acid components and amine compounds can be introduced into the electrodialysis unit, and the flow rate of the captured liquid can be easily adjusted. Furthermore, by providing a bypass for introducing the captured liquid from the acid component captured liquid storage tank 7 to the acid component captured liquid introduction pipeline L5 or the electrolysis unit 4, the flow rate of the captured liquid can be easily adjusted.

[0107] The above describes several embodiments of the carbon dioxide gas removal device and the removal method of the present invention, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways, and various omissions, substitutions, changes or additions can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and purpose of the invention, and are also included in the invention described in the claims and their equivalents.

Claims

1. A carbon dioxide gas removal device, characterized in that: It has: A carbon dioxide separation and recovery unit, which absorbs carbon dioxide gas by bringing a treated gas containing carbon dioxide gas into contact with a carbon dioxide absorbing liquid containing an amine compound, and further recovers carbon dioxide gas from the carbon dioxide absorbing liquid that has absorbed carbon dioxide gas and regenerates the carbon dioxide absorbing liquid for reuse as the carbon dioxide absorbing liquid; and a carbon dioxide absorbing liquid refining unit, which removes acid components from the carbon dioxide absorbing liquid by electrodialysis to purify the carbon dioxide absorbing liquid; The carbon dioxide absorption liquid purification unit comprises: An electrodialysis unit comprising a desalting chamber, a concentrating chamber, and a membrane selected from a cation exchange membrane, an anion exchange membrane, or a bipolar membrane disposed between the desalting chamber and the concentrating chamber between a pair of opposing electrodes, wherein the carbon dioxide absorbing liquid is purified by dissolving the acid component from the carbon dioxide absorbing liquid introduced into the desalting chamber into the acid component capturing liquid introduced into the concentrating chamber; An amine separation unit, which separates the amine compounds contained in the acid component capture liquid; and an acid component separation unit for separating the acid component contained in the acid component capture liquid; The electrodialysis unit, the amine separation unit, and the acid component separation unit are connected in such a manner that the acid component capture solution can circulate.

2. The carbon dioxide gas removal device according to claim 1, wherein: The invention further comprises an acid component captured liquid storage tank for temporarily storing the acid component captured liquid.

3. The carbon dioxide gas removal device according to claim 1 or 2, wherein: The acid component separation unit includes a basic compound introduction unit that introduces a basic compound containing an alkali metal or an alkaline earth metal as a cation into the acid component collection liquid.

4. The carbon dioxide gas removal device according to claim 1 or 2, wherein: The acid component separation unit further includes a cooling unit for cooling the acid component collection liquid into which the basic compound is introduced.

5. The carbon dioxide gas removal device according to claim 3, wherein: The cooling unit further includes an acid component recovery unit for separating and recovering the neutralized salt precipitated by the cooling unit.

6. The carbon dioxide gas removal device according to claim 1 or 2, wherein: The amine separation unit separates the amine compound from the acid component capture liquid by reverse osmosis, forward osmosis, ultrafiltration, ion exchange resin or electrodialysis.

7. The carbon dioxide gas removal device according to claim 2, wherein: A portion of the acid component captured solution is circulated from the acid component captured solution storage tank via the electrodialysis unit to the acid component captured solution storage tank, Another part of the acid component captured liquid is circulated to the acid component captured liquid storage tank via the amine separation unit and the acid component separation unit.

8. The carbon dioxide gas removal device according to claim 2, wherein: The acid component captured liquid circulates from the acid component captured liquid storage tank via the electrodialysis unit, the amine separation unit, and the acid component separation unit to the acid component captured liquid storage tank.

9. A carbon dioxide absorption liquid purification unit, characterized in that: It has: An electrodialysis unit comprising a desalting chamber, a concentrating chamber, and a membrane selected from a cation exchange membrane, an anion exchange membrane, or a bipolar membrane disposed between the desalting chamber and the concentrating chamber between a pair of opposing electrodes, wherein the carbon dioxide absorbing liquid is purified by dissolving the acid component from the carbon dioxide absorbing liquid containing the acid component introduced into the desalting chamber into the acid component capturing liquid introduced into the concentrating chamber; An amine separation unit, which separates amine compounds contained in the acid component capture liquid; and An acid component separation unit that separates the acid component contained in the acid component capture liquid; The electrodialysis unit, the amine separation unit, and the acid component separation unit are connected in such a manner that the acid component capture solution can circulate.

10. A method for removing carbon dioxide gas, characterized in that: The invention relates to a carbon dioxide separation and recovery method, wherein a treated gas containing carbon dioxide gas is brought into contact with a carbon dioxide absorbing liquid containing an amine compound to absorb the carbon dioxide gas, and the carbon dioxide absorbing liquid is regenerated while the carbon dioxide gas is recovered from the carbon dioxide absorbing liquid that has absorbed the carbon dioxide gas, and is reused as the carbon dioxide absorbing liquid, and the method comprises the following steps: By electrodialysis, the acid component is moved in the acid component capturing liquid to purify the carbon dioxide absorbing liquid; Separating the amine compounds contained in the acid component capture solution; as well as The acid component contained in the acid component collection liquid is separated.

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