Acid gas recovery device and acid gas recovery method

Abstract

To provide an acid gas recovery device and method for recovering acid gas from exhaust gas or the atmosphere, capable of effectively utilizing supplied renewable energy.SOLUTION: An acid gas recovery device includes: an acidic gas absorption unit that brings a to-be-treated gas containing an acidic gas into contact with an acidic gas absorption liquid and discharges a rich acidic gas absorption liquid having absorbed the acidic gas; and a recycling unit that recycles the acid gas absorption liquid by moving a specific component, which the rich acidic gas absorption liquid contains, into a recovery liquid by means electrodialysis; wherein the electrodialysis uses renewable energy.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present embodiment relates to an acid gas recovery apparatus and an acid gas recovery method using renewable energy. [Background technology]

[0002] In thermal power plants and steel mills that use large amounts of fossil fuels, the combustion exhaust gases generated by burning fossil fuels in boilers, coal gasification gas (gasification gas) produced by gasifying coal, and natural gas contain acidic gas components such as carbon dioxide (CO2), SOx, NOx, NOx, and H2S.

[0003] In order to prevent the release of acidic gas components contained in such combustion exhaust gases and the like into the atmosphere, methods for recovering the acidic gas components from the gas being treated by bringing the gas containing the acidic gas components into gas-liquid contact with an absorption liquid containing an amino group-containing compound (amine compound) in an absorption tower and absorbing the acidic gas components into the absorption liquid have been actively researched.

[0004] In addition, in recent years, in order to curb greenhouse gas emissions, DAC (Direct Air Capture) technology, which captures carbon dioxide from carbon dioxide in the atmosphere rather than from exhaust gases, has also been actively researched.

[0005] However, these acid gas recovery technologies require energy to heat the absorption liquid, reduce pressure, etc. If this energy is obtained by burning fossil fuels, there is an issue that carbon dioxide is emitted during combustion, reducing the effect of reducing greenhouse gas emissions.

[0006] Meanwhile, renewable energy sources such as solar power and wind power are becoming more widespread as energy sources that do not emit greenhouse gases. However, the power generation capacity of renewable energy varies greatly depending on the weather and season, making it difficult to provide a stable power supply. For this reason, depending on the surplus or shortage of renewable energy supply, the use of surplus electricity from existing thermal power plants and the like, and the use of excess energy to produce hydrogen and store it are being considered. However, it is not easy for existing power plants and hydrogen production to keep up with sudden fluctuations in renewable energy, so it is desirable to use renewable energy as much as possible. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6659293 [Patent Document 2] Patent No. 7058349 Summary of the Invention [Problem to be solved by the invention]

[0008] In order to reduce greenhouse gases, it is desirable to further reduce the energy required to enhance the greenhouse gas reduction effect of methods for capturing carbon dioxide from exhaust gases and the atmosphere. From this perspective, it has been considered to achieve a greenhouse gas reduction effect by using renewable energy in methods for capturing carbon dioxide from exhaust gases and the atmosphere. However, it has not been easy to effectively utilize renewable energy, whose supply tends to be unstable.

[0009] This embodiment has been made taking such circumstances into consideration, and aims to provide an acid gas recovery device and method that makes maximum use of renewable energy to recover acid gases from exhaust gases and the atmosphere, even if the supplied renewable energy is unstable. [Means for solving the problem]

[0010] The acid gas recovery apparatus according to the embodiment includes: an acid gas absorbing section that contacts a gas to be treated containing an acid gas with an acid gas absorbing liquid containing an alkaline substance, absorbs at least a part of the acid gas in the acid gas absorbing liquid, and discharges a rich acid gas absorbing liquid having absorbed the acid gas and the gas to be treated from which the acid gas has been removed; A regeneration unit that transfers a specific component contained in the rich acidic gas absorbing liquid to a recovery liquid and regenerates the acidic gas absorbing liquid, The regeneration unit includes an acidic gas absorbent chamber, a recovery liquid chamber, and a membrane selected from a cation exchange membrane, an anion exchange membrane, and a bipolar membrane, which are disposed between the acidic gas absorbent chamber and the recovery liquid chamber, between a cathode and an anode facing each other, and regenerates the acidic gas absorbent by transferring and separating the specific component from the acidic gas absorbent introduced into the acidic gas absorbent chamber to a recovery liquid introduced into the recovery liquid by electrodialysis; The electrodialysis is characterized in that renewable energy is utilized.

[0011] The method for recovering an acidic gas according to an embodiment includes the following steps (A) to (B): Step (A): contacting a gas to be treated containing an acidic gas with an acidic gas absorbing liquid containing an alkaline substance, and allowing the acidic gas in the gas to be treated to be absorbed by the acidic gas absorbing liquid to obtain a rich acidic gas absorbing liquid; Step (b): A step of separating and removing the acid gas from the rich acid gas absorbing solution by electrodialysis using renewable energy, and regenerating the acid gas absorbing solution. The present invention is characterized in that it comprises: Effect of the Invention

[0012] According to the embodiment, an acid gas recovery apparatus and method for recovering acid gas from exhaust gas or the atmosphere, which effectively utilizes supplied renewable energy, can be obtained. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing a configuration of an acid gas recovery apparatus according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing the configuration of a regeneration unit used in the acid gas recovery apparatus according to the embodiment. [Diagram 3] FIG. 2 is a schematic diagram showing the configuration of a regeneration unit used in the acid gas recovery apparatus according to the embodiment. [Figure 4] 1 is a schematic diagram showing a part of the configuration of an acid gas recovery apparatus according to an embodiment. [Diagram 5] 1 is a schematic diagram showing a configuration of an acid gas recovery apparatus according to an embodiment. [Figure 6] 1 is a schematic diagram showing a configuration of an acid gas recovery apparatus according to an embodiment. [Figure 7] FIG. 2 is a schematic diagram showing the configuration of a regeneration unit used in the acid gas recovery apparatus according to the embodiment. [Figure 8] FIG. 2 is a schematic diagram showing the configuration of a regeneration unit used in the acid gas recovery apparatus according to the embodiment. [Figure 9] FIG. 2 is a schematic diagram showing the configuration of a regeneration unit used in the acid gas recovery apparatus according to the embodiment. [Figure 10] FIG. 2 is a schematic diagram showing the configuration of a regeneration unit used in the acid gas recovery apparatus according to the embodiment. [Figure 11] 1 is a schematic diagram showing a part of the configuration of an acid gas recovery apparatus according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the embodiment of the present invention will be described in more detail. Note that, in this specification, the case where the acidic gas is carbon dioxide (CO2) will be described in detail, but the embodiment is not limited to the case where the acidic gas is carbon dioxide (CO2).

[0015] [First acid gas recovery unit] FIG. 1 is a schematic diagram showing the basic configuration of an acid gas recovery apparatus according to a preferred embodiment of the present invention.

[0016] The acidic gas recovery apparatus shown in FIG. 1 comprises an acidic gas absorption section 1 and a regeneration section 2 . The acidic gas absorption unit 1 introduces the treated gas 101 containing acidic gas, such as exhaust gas or air, through line L1, brings it into contact with an acidic gas absorbing liquid (hereinafter sometimes referred to as the absorbing liquid) containing an alkaline substance introduced through line L4, absorbs at least a portion of the acidic gas into the acidic gas absorbing liquid, discharges a rich acidic gas absorbing liquid 110 (hereinafter sometimes referred to as the rich absorbing liquid) that has absorbed the acidic gas through line L3, and discharges the treated gas 102 from which the acidic gas has been removed through line L2.

[0017] The regeneration unit 2 transfers specific components contained in the rich acidic gas absorbing liquid 110 to a recovery liquid, removes the acidic gas from the acidic gas absorbing liquid, and regenerates it as a lean acidic gas absorbing liquid 111 (hereinafter sometimes referred to as lean absorbing liquid).

[0018] In this acid gas recovery system, an absorbing solution that absorbs CO2 in a gas to be treated (exhaust gas) 101 that contains CO2 circulates between an absorbing section 1 and a regenerating section 2 (hereinafter referred to as "within the system"). An absorbing solution (rich absorbing solution) 110 that has absorbed CO2 in the exhaust gas 101 is supplied from the absorbing section 1 to the regenerating section 2 via a line L3. An absorbing solution (lean absorbing solution) 111 that has been regenerated by removing some or almost all of the CO2 from the rich absorbing solution 110 in the regenerating section 2 is supplied from the regenerating section 2 to the absorbing section 1 via a line L4. In an embodiment, the absorbing liquid contains an alkaline substance. The alkaline substance may be an inorganic compound such as an alkali metal hydroxide or an alkaline earth metal hydroxide, an organic compound such as an amine compound, or an amino acid salt.

[0019] Specific examples of inorganic compounds include aqueous solutions of alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, and alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide. These compounds may be used alone or in combination. In the embodiment, these aqueous solutions are suitable as the absorbing liquid. Sodium hydroxide and potassium hydroxide are particularly preferred because of their high solubility in water.

[0020] Specific examples of amine compounds include primary amines such as monoethanolamine and 2-amino-2-methyl-1-propanol, secondary amines such as diethanolamine and 2-methylaminoethanol, tertiary amines such as triethanolamine and N-methyldiethanolamine, polyethylene polyamines such as ethylenediamine, triethylenediamine, and diethylenetriamine, cyclic amines such as piperazines, piperidines, and pyrrolidines, polyamines such as xylylenediamine, and amino acids such as methylaminocarboxylic acid. These compounds can be used alone or in combination of two or more. In the embodiment, the absorbing liquid is preferably an aqueous solution of these compounds.

[0021] Various kinds of amino acid salts can be used, but in the present invention, salts made of amino acids and alkali metals are preferred. Examples of amino acids include alanine, arginine, asparagine, cysteine, glutamine, glycine, histidine, hydroxyproline, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine. Examples of alkali metals include any alkali metal such as lithium, sodium, potassium, rubidium, and cesium, but in the embodiment of the present invention, sodium and potassium are particularly preferred in that the molecular weight of the amino acid salt does not become too large.

[0022] Examples of the amino acid salt include sodium alanine salt, potassium alanine salt, sodium glycine salt, potassium glycine salt, rubidium proline salt, and any combination thereof. These can be used alone or in combination of two or more. In the embodiment, an aqueous solution of these is suitable as the absorbing liquid. Amino acid salts are preferred as the absorbing liquid because they have a low vapor pressure, and are less dissipated into the treated gas after the acid gas absorption treatment, and are less discharged outside the system.

[0023] The absorbing liquid is usually used as an aqueous solution containing 10 to 70% by weight of these alkaline substances.

[0024] In a general acid gas recovery apparatus, the absorbing solution is often regenerated by heating, and an amine compound from which acid gas is easily separated by heating is often used as the absorbing solution. In this embodiment, since heating is not used to regenerate the absorbing solution, it is preferable to use an inorganic compound or an amino acid salt, which absorbs acid gas more easily than an amine compound, as the alkaline substance. Amine compounds may diffuse outside the system during operation of the acid gas absorption apparatus and pollute the atmosphere, but it is preferable to use inorganic compounds or amino acid salts as the alkaline substance because such problems do not occur.

[0025] In addition, the absorption liquid may contain other compounds, such as a reaction accelerator, a nitrogen-containing compound that improves the absorption performance of acidic gases such as CO2, an anticorrosive agent for preventing corrosion of plant equipment, an antifoaming agent for preventing foaming, an antioxidant for preventing deterioration of the absorption liquid, a pH adjuster, etc., in any proportion as long as the effect of the absorption liquid is not impaired.

[0026] The gas to be treated 101 is an exhaust gas containing CO2, and is, for example, a combustion exhaust gas discharged from a boiler or a gas turbine of a thermal power plant or the like, a process exhaust gas generated in a steelworks, etc. The gas to be treated 101 is preferably pressurized by a blower or the like, cooled by a cooler, and then supplied into the device from the lower part of the absorption section 1 through a flue.

[0027] In addition, air containing CO2 can be used as the gas to be treated 101. Since the CO2 concentration contained in the air gas is relatively low, the energy used in the regeneration unit is also relatively small, so that in this embodiment, it is preferable to use air as the gas to be treated.

[0028] Here, the CO2 absorbing section 1 is, for example, in the shape of a tower, and a packing material is formed inside the CO2 absorbing section 1 to increase the gas-liquid contact efficiency. A liquid distributor can be provided above the CO2 absorbing section 1, and the lean absorbing liquid 111 supplied to the absorbing section 1 is dispersed and falls toward the CO2 absorbing section by the liquid distributor. The treated gas 101 supplied into the absorbing section 1 flows from the bottom of the absorbing section 1 toward the tower top (upper part). In the CO2 absorbing section 1, when the flue gas 101 ascending in the absorbing section comes into countercurrent contact with the lean absorbing liquid 111 in the CO2 absorbing section 1, a reaction such as that shown in the following formula (1) occurs, for example, when the absorbing liquid is an amine, and the CO2 in the flue gas 101 is absorbed by the lean absorbing liquid 111 and removed from the flue gas 101.

[0029] The shape of the absorbing section 1 does not have to be a tower with a packing material placed inside. For example, the absorbing liquid may be supplied by spraying, or the absorbing liquid may be circulated through a flat honeycomb.

[0030] The lean absorbing solution 111 absorbs CO2 in the exhaust gas 101, becomes the rich absorbing solution 110, and is stored in the lower part. Here, R represents hydrogen or a substituted or unsubstituted alkyl group (which may form a heterocycle). R3N+CO2+H2O → R3NH2CO3···(1)

[0031] The treated exhaust gas 102 is discharged to the outside from the top of the absorption section 1 .

[0032] The CO2-removed flue gas that has passed through the CO2 absorption unit 1 can be supplied to a gas scrubbing unit (not shown) to remove the accompanying absorbing liquid components. The CO2-removed flue gas is purified in the gas scrubbing unit and then discharged to the outside from the top of the absorption unit 1 as treated flue gas 102.

[0033] On the other hand, the rich absorbent 111 stored in the lower part of the absorbing section 1 is discharged from the lower part of the absorbing section 1 and supplied to the regenerating section 2 through the rich absorbent supply line L3.

[0034] The regeneration unit 2 releases CO2 from the rich absorbing solution 110, and regenerates the rich absorbing solution 110 as a lean absorbing solution 111. The rich absorbing solution 110 is supplied into the regeneration unit 2, and when a voltage is applied by power supplied from the renewable energy supply source 10, the CO2 contained in the rich absorbing solution 110 is desorbed, and the rich absorbing solution 110 becomes a lean absorbing solution 111 from which a part or almost all of the CO2 contained in the rich absorbing solution 111 has been removed.

[0035] As the renewable energy supply source 10, energy supply sources that are subject to large weather and seasonal fluctuations, such as solar power generation, wind power generation, hydroelectric power generation, and wave power generation, can be used.

[0036] The renewable energy supply source used in the embodiment may supply energy to other demand destinations other than the regeneration unit 2, and by operating the regeneration unit 2 when the amount of renewable energy supply is greater than the power supplied to destinations other than the regeneration unit 2, the renewable energy can be effectively utilized without being left in surplus.

[0037] In addition, a renewable energy source dedicated to the acid gas recovery device according to the embodiment may be installed. When the air is used as the gas to be treated, it is not necessary to continuously treat the generated gas to be treated, as in the case of factory exhaust gas. For this reason, it is preferable that the gas to be treated is the air, since the gas can be treated according to the power generation capacity of the renewable energy source.

[0038] The lean absorbing solution 111 discharged from the regenerating section 2 is supplied again to the absorbing section 1 through the line L4. The lean absorbing solution 111 can also be cooled in order to improve the CO2 recovery rate from the gas 101 to be treated.

[0039] The CO2 gas dissolved in the rich absorbing liquid 110 is transferred to an acidic gas recovery liquid 112 (hereinafter, sometimes referred to as a lean recovery liquid) that recovers the CO2 gas in the regenerating section 2, and the acidic gas recovery liquid (hereinafter, sometimes referred to as a rich recovery liquid) into which the CO2 gas has been introduced is discharged from the regenerating section 2. That is, in the regenerating section 2, anions derived from the CO2 gas, which is a specific component contained in the rich absorbing liquid 110, are transferred to the lean recovery liquid, and the CO2 gas is dissolved in the generated rich recovery liquid and discharged from the regenerating section 2.

[0040] The rich recovery liquid 113 is supplied to the gas-liquid separator 3 through a line L6, where it is separated into CO2 gas 103 and acidic gas recovery liquid 112, and the CO2 gas 103 is recovered through a line L7. The lean recovery liquid 112 from which the CO2 gas has been separated is extracted from the bottom of the gas-liquid separator 3 and is supplied again to the regeneration unit 2 through a line L5.

[0041] The CO2 gas recovery liquid is preferably one having high electrical conductivity as long as it can separate CO2 into gas and liquid in the gas-liquid separator 3. In addition to pure water, an acid solution such as sulfuric acid or nitric acid, an aqueous salt solution such as sodium sulfate can be used, and may contain an absorption liquid component.

[0042] According to this embodiment, it is possible to provide an acid gas recovery device that recovers acid gas from exhaust gas or the atmosphere, making effective use of renewable energy.

[0043] [First Regeneration Section] The configuration of the first regeneration section 2 in the acid component removal device according to the embodiment will be further described with reference to FIGS.

[0044] The regeneration unit shown in Fig. 2 has an electrodialysis structure consisting of two chambers, in which a recovery liquid chamber 21a, an anion exchange membrane 24A-1, and an acidic gas absorbing liquid chamber 20a are arranged in this order between an anode 22 and a cathode 23. This regeneration unit extracts anions derived from dissolved CO2 gas, such as CO3 2- or HCO3 -The specific components are transferred to the lean recovery liquid through the anion exchange membrane. Therefore, the recovery liquid chamber 21a is an acidic gas recovery liquid chamber that recovers the acidic gas, and the acidic gas absorption liquid chamber 20a is an acidic gas separation chamber in which the acidic gas is separated.

[0045] The cathode 22 and the anode 23 may be immersed in the electrode solution.

[0046] In this embodiment, one recovery liquid chamber 21a and one acidic gas absorbing liquid chamber 20a are formed, but one or more sets of recovery liquid chambers and acidic gas absorbing liquid chambers may be formed, and more may be formed. The number of combinations of recovery liquid chambers and acidic gas absorbing liquid chambers does not have to be the same. As long as one or more sets of recovery liquid chambers and acidic gas absorbing liquid chambers are formed, there may be other recovery liquid chambers and acidic gas absorbing liquid chambers as separate chambers. Therefore, not only a three-chamber or four-chamber configuration as described below, but also a configuration having five or more chambers may be adopted.

[0047] The anion exchange membrane 24A-1 is a polymer membrane having an anion exchange group that allows anions to pass through and blocks the passage of cations. For example, a membrane made of a polymer having a weakly basic functional group such as a primary amino group, a secondary amino group, or a tertiary amino group in addition to a strongly basic group of a quaternary ammonium group can be used as the anion exchange membrane. Specifically, known anion exchange membranes such as Neocepta AMX and Neocepta AHA (trade names, manufactured by Astom Corporation); Selemion AMV, Selemion AMT, Selemion DSV, Selemion ASV, and Selemion AHO (trade names, manufactured by AGC Engineering Co., Ltd. and Asahi Glass Co., Ltd.) can be used.

[0048] The acidic gas recovery liquid chamber 21a is supplied with the acidic gas recovery liquid 112. The acidic gas absorbing liquid chamber 20a is supplied with the rich absorbing liquid 110.

[0049] The rich absorbing liquid 110 is supplied from the absorbing section 1. When the rich absorbing liquid is supplied to the regenerating section 2 and a voltage is applied to both electrodes, the acidic gas component (HCO3 - , CO3 2- ) is an anion and is attracted to the anode 22. As a result, the acidic gas component (HCO3 - , CO3 2- ) moves from the acidic gas absorbing liquid chamber 20a through the anion exchange membrane 24A-1 to the recovery liquid chamber 21a, and the anion (HCO3 - , CO3 2- ) is removed, the specific component moves to the lean recovered solution 112, and the rich recovered solution 113 containing the specific component is discharged. On the other hand, the lean absorbent 111 in which the specific component has been removed from the rich absorbent 110 is also discharged.

[0050] In the rich recovery liquid 113, the acid gas components (HCO3 - , CO3 2- ) that cannot be completely dissolved as anions may be mixed in as non-ionic CO2.

[0051] The rich recovery liquid 113 is separated into CO2 gas 103 and acidic gas recovery liquid 112 by the gas-liquid separator 3, and the CO2 gas 103 is recovered as a single substance.

[0052] The lean absorbing solution 111 discharged from the regenerating section 2 may be entirely supplied to the absorbing section 1 as shown in Fig. 1, but if the removal of CO2 is insufficient, it may be repeatedly passed through the regenerating section 2 again to obtain lean absorbing solution 111 with a sufficiently low CO2 content, which may then be supplied to the absorbing section 1. This is more preferable as it improves the acid gas recovery rate in the absorbing section 1.

[0053] [Second Regeneration Section] The details of another configuration of the reproducing unit 2 in the embodiment will be further described with reference to FIG. 3 and FIG.

[0054] The regeneration unit 2 shown in Fig. 3 has an electrodialysis structure consisting of two chambers, an acidic gas absorbing liquid chamber 25a, a cation exchange membrane 27C, and a recovery liquid chamber 26a, arranged in this order between an anode 22 and a cathode 23. This regeneration unit transfers cations derived from the dissolved alkaline substances as specific components from the rich absorbing liquid 110 to the lean recovery liquid through the cation exchange membrane. Therefore, the acidic gas absorbing liquid chamber 25a is an absorbing liquid component separation chamber where the cations dissolved in the absorbing liquid are separated, and the recovery liquid chamber 26a is an absorbing liquid component recovery liquid chamber where the cations are recovered.

[0055] The cathode 22 and the anode 23 may be immersed in the electrode solution.

[0056] In this embodiment, one acidic gas absorbing liquid chamber 25a and one recovery liquid chamber 26a are formed, but one or more sets of recovery liquid chambers and acidic gas absorbing liquid chambers may be formed, and more may be formed. The number of combinations of recovery liquid chambers and acidic gas absorbing liquid chambers does not have to be the same. As long as one or more sets of recovery liquid chambers and acidic gas absorbing liquid chambers are formed, the recovery liquid chamber and the acidic gas absorbing liquid chamber may exist as separate chambers. Therefore, not only a three-chamber configuration or a four-chamber configuration as described below, but also a configuration having five or more chambers may be adopted.

[0057] The cation exchange membrane 27C is a polymer membrane having a cation exchange group that allows cations to pass through and blocks the passage of anions. For example, a membrane made of a polymer having one or more of a sulfonic acid group, a carboxylic acid group, a phosphonic acid group, a sulfate ester group, and a phosphate ester group can be used as the cation exchange membrane 27C. Specifically, a known cation exchange membrane such as Neocepta CMX or Neocepta CMB (trade names, manufactured by Astom Corporation), Selemion CMV, Selemion CMD, Selemion CSO, or Selemion CMF (trade names, manufactured by AGC Engineering Co., Ltd.) can be used.

[0058] The acidic gas absorbing liquid chamber 25a is supplied with a rich absorbing liquid 110. The recovering liquid chamber 26a is supplied with a lean recovering liquid 114.

[0059] As the rich absorbing liquid 110, one supplied from the absorbing section 1 shown in FIG. 4 is used. When the rich absorbing liquid is supplied to the regenerating section 2 and a voltage is applied between the two electrodes, the specific component (M + ) is a cation and is attracted to the cathode 23. As a result, the cations in the acidic gas absorbing solution chamber 25a pass through the cation exchange membrane 27C from the acidic gas absorbing solution chamber 25a and move to the recovery solution chamber 26a, so that the absorbing solution component (M + ) is removed, the specific component moves to the lean recovered liquid 114, and the rich recovered liquid 115 containing the specific component is discharged. On the other hand, the lean absorbent 111 in which the specific component has been removed from the rich absorbent 110 is also discharged.

[0060] In the lean absorption liquid 110, acid gas components (HCO3 - , CO3 2- ) that cannot be completely dissolved as anions may be mixed in as non-ionic CO2.

[0061] As shown in FIG. 4, the CO2 gas 104 is separated from the lean absorbing liquid 111 from which the CO2 gas has been removed by the gas-liquid separator 4, and the CO2 gas 104 is recovered.

[0062] Specific component (M + Since the rich recovery liquid 115 containing the specific component (M) exhibits acid gas absorption performance, it can be supplied to the absorption section 1 as a lean absorption liquid 116 and used for recovery of acid gas. As shown in FIG. 4, it may be supplied to the absorption section 1 via the storage section 5 or directly. However, if the concentration of the specific component is not sufficient, it is possible to repeatedly circulate the lean recovery liquid 114 again through the regeneration section 2 until the concentration of the specific component (M) is sufficient. + ) may be used as the lean absorbing solution 116 with a high concentration. By doing so, the recovery rate of the acid gas in the absorbing section 1 is improved, which is more preferable.

[0063] 4, the lean absorbing liquid 117 discharged from the gas-liquid separator 4 may be supplied to the absorbing section 1 together with the rich recovery liquid 116, but if the removal of CO2 is insufficient, it may be repeatedly circulated through the regenerating section 2 again to obtain lean absorbing liquid 117 with a sufficiently low CO2 concentration, which may then be supplied to the absorbing section 1 together with the lean absorbing liquid 116. This is more preferable because it improves the acid gas recovery rate in the absorbing section 1.

[0064] [Second Acid Gas Recovery Unit] FIG. 5 shows the configuration of an acid gas recovery apparatus according to another embodiment. The configuration of this apparatus differs from the first acid gas recovery apparatus described above in that the recovery liquid circulates in a path having a bypass line L11 that does not pass through the regeneration unit 2. This embodiment is a schematic diagram showing an embodiment in which, when the power required for the operation of the regeneration unit 2 is not supplied from the renewable energy supply source 10, an operation is performed in which the acid gas is absorbed by the absorption liquid in the absorption unit 1, and the operation of the regeneration unit 2 is not performed. Note that FIG. 5 is based on the first acid gas recovery apparatus, but it is sufficient to have a bypass line that allows the absorption liquid to circulate without passing through the regeneration unit, and the bypass line may be combined with other acid gas absorption apparatuses according to the embodiment.

[0065] When the power supplied from the renewable energy supply source 10 is insufficient to operate the regenerating section 2, the absorbing liquid is not supplied to the regenerating section 2, but is supplied again to the absorbing section 1 through the bypass line L11 and is used to absorb CO2 gas from the gas to be treated. Therefore, the absorbing liquid circulates through the absorbing section and is repeatedly used to absorb CO2 gas.

[0066] When the absorbing liquid is repeatedly used without regeneration, the amount of CO2 gas absorbed in the absorbing liquid increases. As a result, the CO2 gas absorption efficiency decreases with each use, so it is preferable to stop the operation of the absorbing section when the amount of CO2 gas absorbed in the absorbing liquid exceeds a certain level. For this reason, for example, a lower limit of the CO2 capture rate in the absorbing section 1 can be set in advance, and operation can be stopped when the capture rate falls below that limit. Alternatively, an upper limit of the amount of CO2 gas absorbed in the absorbing liquid can be set in advance, and operation can be stopped when the amount of absorption exceeds that limit. In such a case, a storage section 6 as shown in FIG. 6 can be provided to store the absorbing liquid therein.

[0067] This operation is particularly effective under conditions where the CO2 gas recovery performance is still maintained after the absorption liquid 111 has passed through the absorption section 1 only once, and when the CO2 gas concentration in the treated gas 101 is low, the amount of CO2 gas absorbed can be maximized to the theoretical equilibrium value by repeatedly supplying the absorption liquid to the absorption section 1. Therefore, the acid gas recovery apparatus according to the embodiment is particularly preferable when the treated gas 101 is the atmosphere.

[0068] Furthermore, since the amount of CO2 gas that can be absorbed increases as the total amount of circulating absorption liquid increases relative to the amount of gas to be treated, it is preferable that the amount of absorption liquid stored in the storage unit 6 is as large as possible.

[0069] When the power supplied from the renewable energy supply source 10 becomes sufficient to operate the regeneration section, the stored rich absorption liquid 110 is supplied to the regeneration section 2, and regeneration operation is initiated, thereby restarting the CO2 gas recovery process.

[0070] In the embodiment in which the absorbing solution is regenerated by electrodialysis, CO2 gas recovery can be started immediately after starting operation. Therefore, the time until start-up is shorter than in the case of a regeneration method that requires heating, etc., and therefore it is easy to follow load fluctuations and enables efficient operation.

[0071] [Third acid gas recovery unit] 6 is a schematic diagram showing the configuration of an acidic gas recovery apparatus according to a preferred embodiment of the present invention, which illustrates that when there is no surplus electricity from renewable energy, the absorption unit 1 operates to absorb acidic gas with an absorption liquid, and the regeneration unit 2 does not operate. The regeneration unit 2 has a configuration of Form 2.

[0072] When the amount of renewable energy 10 generated is small and no surplus electricity is generated, the rich absorbing solution 110 is not supplied to the regeneration section 2, but is supplied again to the absorption section 1 as the absorbing solution 111 through the bypass line L11, and absorbs CO2 from the gas 101 to be treated.

[0073] When the CO2 absorption is completed, the supply of the absorbing liquid is stopped and the absorbing liquid is stored in the storage section 6. The storage section 6 may be integrated with the gas-liquid separation section 4. When the CO2 capture rate in the absorption section 1 becomes equal to or lower than a set value as a criterion for the completion of the CO2 absorption, the supply can be stopped.

[0074] This operation is particularly effective under conditions where the CO2 recovery performance is still maintained after the absorption liquid 111 has passed through the absorption section 1 only once, and when the CO2 concentration in the treated gas 101 is low, the CO2 absorption amount can be maximized to the theoretical equilibrium value by repeatedly supplying the absorption liquid to the absorption section 1, which is particularly preferable when the treated gas 101 is air. To facilitate such operation, the acid gas recovery apparatus according to the embodiment can further include a member for measuring the CO2 content concentration of the rich absorption liquid.

[0075] In addition, since the amount of absorbent that can be absorbed increases as the amount of absorbent held relative to the amount of gas to be treated increases, it is preferable to store a larger amount of absorbent in the storage section 6. When the amount of renewable energy 10 generated increases, the stored rich absorbent 110 is supplied to the regeneration section 2 and regeneration operation is started, so that the CO2 gas can be recovered again.

[0076] The rich absorption solution 110 supplied to the regeneration section 2 can immediately start CO2 capture by applying voltage, and since the start-up time is shorter than that of methods that require heating, it is easy to follow load fluctuations and enables efficient operation.

[0077] [Third Regeneration Section] Another embodiment of the regenerating section 2 that can be used in the acidic gas recovery apparatus according to the embodiment will be described with reference to FIG.

[0078] The regeneration unit shown in Fig. 7 is provided with an electrodialysis structure having a three-chamber structure in which a first recovery liquid chamber 21a, a first anion exchange membrane 24A-1, an acidic gas absorbing liquid chamber 20a, a bipolar membrane 28BP, and a second recovery liquid chamber 21b are arranged in this order between an anode 22 and a cathode 23. This regeneration unit transfers anions derived from the dissolved CO2 gas from the rich absorbing liquid 110 as specific components to the lean recovery liquid through the anion exchange membrane. The first recovery liquid chamber and the second recovery chamber are acidic gas recovery liquid chambers for recovering acidic gas, and the acidic gas absorbing liquid chamber is an acidic gas separation chamber in which acidic gas is separated.

[0079] As the anion exchange membrane 24A-1, the same anion exchange membrane as mentioned in the first regeneration section can be used.

[0080] The bipolar membrane 28BP is a composite membrane in which an anion exchange membrane and a cation exchange membrane are laminated, and is arranged so that the anode side is the anion exchange membrane and the cathode side is the cation exchange membrane. When a voltage equal to or higher than the theoretical decomposition voltage of water is applied in the presence of water, water can be electrolyzed into hydrogen ions and hydroxide ions. Specifically, a known bipolar membrane such as Neocepta BP-1E (trade name, manufactured by Astom Corporation) can be used.

[0081] The first recovery liquid chamber 21a and the second recovery liquid chamber 21b are supplied with the lean recovery liquid 112. The acidic gas absorption liquid chamber 20a is supplied with the rich absorption liquid 110. By applying a voltage between the two electrodes, the absorption liquid can be regenerated by the same function as the first regeneration unit, but by combining with a bipolar membrane, a large number of chambers can be formed, the amount of absorbent that can be treated increases, and the amount of CO2 gas recovered can also be increased, which is preferable.

[0082] [Fourth Reproduction Section] Another embodiment of the regenerating section 2 in the acid component removing device according to the embodiment will be described with reference to FIG.

[0083] The regeneration unit shown in Fig. 8 is provided with an electrodialysis structure consisting of a three-chamber structure in which a first acidic gas absorbent chamber 25a, a first cation exchange membrane 27C-1, a recovery liquid chamber 26a, a bipolar membrane 28BP, and a second acidic gas absorbent chamber 25b are arranged in this order between the anode 22 and the cathode 23. This regeneration unit transfers cations derived from the dissolved alkaline substances from the rich absorbent 110 as specific components to the lean recovery liquid through the cation exchange membrane. Therefore, the first and second acidic gas absorbent chambers 25a and 25b are absorption liquid component separation chambers in which cations dissolved in the absorption liquid are separated, and the recovery liquid chamber 26a is an absorption liquid component recovery liquid chamber for recovering the cations.

[0084] The anion exchange membrane 27C-1 may be the same as the cation exchange membrane described in the second regeneration section, and the bipolar membrane 28BP may be the same as the bipolar membrane described in the third regeneration section.

[0085] The first and second acidic gas absorbing liquid chambers 25a and 25b are supplied with a rich absorbing liquid 110. The absorbing liquid component recovery liquid chamber 26a is supplied with an absorbing liquid component recovery liquid 114. By applying a voltage between the two electrodes, the absorbing liquid can be regenerated by the same function as the first regenerating section. The fourth regenerating section is also preferable because it has many chambers, which increases the amount of absorbing liquid that can be treated and increases the amount of CO2 gas recovered.

[0086] [Fifth Playback Section] Another embodiment of the regenerating section 2 that can be used in the acidic gas recovery apparatus according to the embodiment will be described with reference to FIG.

[0087] The regeneration unit shown in Fig. 9 is provided with an electrodialysis structure having a four-chamber structure in which a first recovery liquid chamber 21a, a first anion exchange membrane 24A-1, a first acidic gas absorbing liquid chamber 20a, a bipolar membrane 28BP, a second recovery liquid chamber 21b, a second anion exchange membrane 24A-2, and a second acidic gas absorbing liquid chamber 20b are arranged in this order between an anode 22 and a cathode 23. This regeneration unit transfers anions derived from dissolved CO2 gas from the rich absorbing liquid 110 as specific components to the lean recovery liquid through the anion exchange membrane. The first recovery liquid chamber and the second recovery chamber are acidic gas recovery liquid chambers for recovering acidic gas, The first acid gas absorbent chamber and the second acid gas absorbent chamber are acid gas separation chambers in which acid gases are separated.

[0088] The anion exchange membranes 24A-1 and 24A-2 may be the same as the anion exchange membranes described in the first regeneration section, and the bipolar membrane 28BP may be the same as the bipolar membrane described in the third regeneration section.

[0089] The first recovery liquid chamber 21a and the second recovery liquid chamber 21b are supplied with the lean recovery liquid 112. The first acidic gas absorption liquid chamber 20a and the second acidic gas absorption liquid chamber 20b are supplied with the rich absorption liquid 110. By applying a voltage between the two electrodes, the absorption liquid can be regenerated by the same function as the first regeneration unit, but by combining with a bipolar membrane, a large number of chambers can be formed, the amount of absorbent that can be treated increases, and the amount of CO2 gas recovered can also be increased, which is preferable.

[0090] [Sixth Reproduction Section] Another embodiment of the regenerating section 2 in the acid component removing device according to the embodiment will be described with reference to FIG.

[0091] The regeneration unit shown in Fig. 10 is provided with an electrodialysis structure consisting of a four-chamber structure in which a first acidic gas absorbent chamber 25a, a first cation exchange membrane 27C-1, a first recovery liquid chamber 26a, a bipolar membrane 28BP, a second acidic gas absorbent chamber 25b, a second cation exchange membrane 17C-2, and a second recovery liquid chamber 26b are arranged in this order between the anode 22 and the cathode 23. This regeneration unit transfers cations derived from the dissolved alkaline substances as specific components from the rich absorbent 110 to the lean recovery liquid through the cation exchange membrane. Therefore, the first and second acidic gas absorbent chambers 25a and 25b are absorption liquid component separation chambers in which cations dissolved in the absorption liquid are separated, and the first and second recovery liquid chambers 26a and 26b are absorption liquid component recovery liquid chambers in which the cations are recovered.

[0092] The anion exchange membranes 27C-1 and 27C-2 may be the same as the cation exchange membranes described in the second regeneration section, and the bipolar membrane 28BP may be the same as the bipolar membrane described in the third regeneration section.

[0093] The first and second acidic gas absorbing liquid chambers 25a and 25b are supplied with a rich absorbing liquid 110. The first and second recovering liquid chambers 26a and 26b are supplied with an absorbing liquid component recovering liquid 114. By applying a voltage between the two electrodes, the absorbing liquid can be regenerated by the same function as the first regenerating unit. The sixth regenerating unit is also preferable because it has many chambers, which increases the amount of absorbing liquid that can be treated and increases the amount of CO2 gas recovered.

[0094] [Fourth acid gas recovery unit] FIG. 11 shows the configuration of an acid gas recovery apparatus according to another embodiment, which includes a power storage unit 11 capable of storing electricity generated from renewable energy.

[0095] This acid gas recovery device can store the surplus power in the power storage unit 11 when the amount of energy supplied from the renewable energy supply source 10 exceeds the energy required to operate the regeneration unit 2. The stored energy can be used when the amount of energy supplied from the energy supply source 10 is insufficient, thereby enabling highly stable acid gas recovery processing.

[0096] A secondary battery such as a lithium ion battery, a lead battery, a nickel-metal hydride battery, or a NAS battery can be used as the power storage unit 11. By using such a secondary battery, the generated renewable energy can be effectively utilized, which is preferable.

[0097] Although the acid gas recovery apparatus and recovery method according to some embodiments of the present invention have been described above, these embodiments are presented as examples and do not limit the scope of the invention. These embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, additions, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0098] 1: Absorption section 2: Playback section 3, 4: Gas-liquid separator 5, 6: Storage section 10. Renewable energy sources 11: Power storage unit 20a, 20b: Acid gas absorbing liquid chamber 21a, 21b: recovery liquid chamber 25a, 25b: Acid gas absorption liquid chamber 26a, 26b: recovery liquid chamber 24A-1, 24A-2: Anion exchange membrane 27C-1, 27C-2: Cation exchange membrane 28BP: Bipolar membrane 110: Rich absorbent 111: Lean absorbent 112: Lean recovery fluid 113: Rich recovery liquid 114: Lean recovery fluid 115: Rich recovery liquid

Claims

1. an acid gas absorbing section that contacts a gas to be treated containing an acid gas with an acid gas absorbing liquid containing an alkaline substance, absorbs at least a part of the acid gas in the acid gas absorbing liquid, and discharges a rich acid gas absorbing liquid having absorbed the acid gas and the gas to be treated from which the acid gas has been removed; A regeneration unit that transfers a specific component contained in the rich acidic gas absorbing liquid to a recovery liquid and regenerates the acidic gas absorbing liquid, The regeneration unit includes an acidic gas absorbent chamber, a recovery liquid chamber, and a membrane selected from a cation exchange membrane, an anion exchange membrane, and a bipolar membrane, which are disposed between the acidic gas absorbent chamber and the recovery liquid chamber, between a cathode and an anode facing each other, and regenerates the acidic gas absorbent by transferring and separating the specific component from the acidic gas absorbent introduced into the acidic gas absorbent chamber to a recovery liquid introduced into the recovery liquid by electrodialysis; An acid gas recovery apparatus, characterized in that renewable energy is used for the electrodialysis.

2. The acid gas recovery apparatus according to claim 1 , further comprising a storage section for storing the rich acid gas absorbing liquid.

3. Further comprising a power storage unit capable of storing electricity from renewable energy sources, 3. The acid gas recovery apparatus according to claim 1, wherein when the renewable energy supplied to the regeneration unit exceeds an amount required for the electrodialysis, the surplus electricity can be stored in a power storage unit.

4. 3. The acid gas recovery apparatus according to claim 1, wherein the alkaline substance is an alkali metal hydroxide or an alkaline earth metal hydroxide.

5. 3. The acid gas recovery apparatus according to claim 1, wherein the alkaline substance is an amine compound.

6. 3. The acid gas recovery apparatus according to claim 1, wherein the alkaline substance is an amino acid salt.

7. the specific component is an anion derived from the acidic gas, 3. The acid gas recovery apparatus according to claim 1 or 2, wherein the regeneration section has an electrodialysis structure consisting of two chambers, in which the recovery liquid chamber, the anion exchange membrane, and the acid gas absorption liquid chamber are arranged in this order between the anode and the cathode.

8. the specific component is a cation derived from the alkaline substance, 3. The acid gas recovery apparatus according to claim 1, wherein the regeneration section has an electrodialysis structure consisting of two chambers, in which the acid gas absorption liquid chamber, the cation exchange membrane, and the recovery liquid chamber are arranged in this order between the anode and the cathode.

9. the specific component is an anion derived from the acidic gas, 3. The acid gas recovery apparatus according to claim 1 or 2, wherein the regeneration section has an electrodialysis structure consisting of three chambers, in which a first recovery liquid chamber, an anion exchange membrane, the acid gas absorption liquid chamber, a bipolar membrane, and a second recovery liquid chamber are arranged in this order between the anode and the cathode.

10. the specific component is a cation derived from the alkaline substance, the regeneration unit has an electrodialysis structure including three compartments, in which a first acidic gas absorbing liquid chamber, a cation exchange membrane, the recovery liquid chamber, a bipolar membrane, and a second acidic gas absorbing liquid chamber are arranged in this order between the anode and the cathode; 3. The acid gas recovery apparatus according to claim 1 or 2.

11. the specific component is an anion derived from the acidic gas, 3. The acid gas recovery apparatus according to claim 1 or 2, wherein the regeneration section comprises an electrodialysis structure having a four-chamber structure in which a first recovery liquid chamber, a first anion exchange membrane, a first acid gas absorption liquid chamber, a bipolar membrane, a second recovery liquid chamber, a second anion exchange membrane, and a second acid gas absorption liquid chamber are arranged in this order between the anode and the cathode.

12. the specific component is a cation derived from the alkaline substance, 3. The acid gas recovery apparatus according to claim 1 or 2, wherein the regeneration section comprises an electrodialysis structure having a four-chamber structure in which a first acid gas absorbing liquid chamber, a first cation exchange membrane, a first recovery liquid chamber, a bipolar membrane, a second acid gas absorbing liquid chamber, a second cation exchange membrane, and a second recovery liquid chamber are arranged in this order between the anode and the cathode.

13. The following steps (a) to (b): Step (A): contacting a gas to be treated containing an acidic gas with an acidic gas absorbing liquid containing an alkaline substance to allow the acidic gas in the gas to be treated to be absorbed into the acidic gas absorbing liquid, thereby obtaining a rich acidic gas absorbing liquid; Step (b): A step of separating and removing the acid gas from the rich acid gas absorbing solution by electrodialysis using renewable energy, thereby regenerating the acid gas absorbing solution. A method for recovering acidic gas, comprising:

14. 14. The method for recovering acidic gas according to claim 13, which does not include a step of regenerating the acidic gas absorbing solution without electrodialysis.

15. The method for recovering acidic gas according to claim 13 or 14, characterized in that the operation of the step (b) is carried out when the renewable energy is surplus electricity generated during operation of a renewable energy generating device.

16. The method for recovering acidic gas according to claim 13 or 14, wherein, when the renewable energy is not supplied, the operation of the step (i) is carried out but the operation of the step (ii) is not carried out.

17. 15. The method for recovering acidic gas according to claim 13 or 14, characterized in that, in step (i), when the acidic gas content contained in the rich acidic gas absorbing liquid becomes equal to or lower than a set value, the operation of step (i) is stopped and the rich acidic gas absorbing liquid is stored.

18. 15. The method for recovering acid gas according to claim 13 or 14, wherein the acid gas is atmospheric air.

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