CO2 recovery and separation device

Abstract

This CO2 recovery / isolation device (1) comprises: a reaction vessel (10) in which a CO2-containing gas is brought into contact with an aqueous solution of an alkali metal hydroxide or an aqueous solution of an alkali earth metal hydroxide; a CO2-containing-gas supply unit (41) that supplies the CO2-containing gas into the reaction vessel; a CO2-removed-gas discharge unit (42) that discharges a CO2-removed gas, from which CO2 has been removed, from the reaction vessel; an acid supply unit (44) that supplies an acid into the reaction vessel; and a CO2 gas discharge unit (45) that discharges the CO2 gas generated within the reaction vessel.

Description

Technical Field

[0001] The present disclosure relates to a CO2 recovery and separation device.

Background Art

[0002] In recent years, it has been required to suppress the emission of CO2 gas as a greenhouse gas, and various devices for recovering CO2 from exhaust gas in various facilities have been studied. For example, Patent Document 1 discloses a configuration in which exhaust gas is brought into contact with a carbon dioxide absorbent to absorb CO2 in the exhaust gas into the carbon dioxide absorbent, and then citric acid is brought into contact with the carbon dioxide absorbent that has absorbed CO2 to separate the CO2 absorbed by the carbon dioxide absorbent and recover the CO2 gas.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration disclosed in Patent Document 1, the absorption of CO2 in the exhaust gas into the carbon dioxide absorbent is performed in an absorption tower, and the separation of CO2 from the carbon dioxide absorbent is performed in a regeneration tower, and the locations for performing the absorption and separation of CO2 are provided separately. Therefore, as the entire device becomes larger and the configuration becomes more complex, the manufacturing cost of the device tends to increase. Further, when performing separation after the absorption of CO2, it is necessary to move the carbon dioxide absorbent from the absorption tower to the regeneration tower, which makes the operation complicated and thus the work efficiency is poor.

[0005] The present disclosure aims to provide a CO2 recovery and separation device that can be miniaturized, cost-reduced, and have improved work efficiency.

Means for Solving the Problems

[0006] One aspect of the present disclosure is a reaction vessel for contacting an aqueous alkali metal hydroxide solution or an aqueous alkaline earth metal hydroxide solution with a CO2-containing gas, A CO2-containing gas supply unit that supplies the CO2-containing gas into the above-mentioned reaction vessel, A CO2 removal gas discharge unit discharges the CO2-removed gas from which CO2 has been removed from the above reaction vessel, An acid supply unit that supplies acid into the above reaction vessel, A CO2 gas discharge section for discharging the CO2 gas generated in the above reaction vessel, A control device comprising an acid supply control unit that controls the timing for stopping the supply of the CO2-containing gas from the CO2-containing gas supply unit and starting the supply of the acid to the reaction vessel from the acid supply unit, based on at least one of the weight of the reaction vessel, the pH of the aqueous solution in the reaction vessel, the concentration of the product in the aqueous solution in the reaction vessel, or the weight of the product in the reaction vessel, The above CO 2 A valve for opening and closing the gas supply section, A valve for opening and closing the above-mentioned acid supply unit, Equipped with 、 The above acid supply control unit controls the above CO 2 Controlling the open / closed state of the valve that opens and closes the gas supply section and the open / closed state of the valve that opens and closes the acid supply section. It is located in the CO2 capture and separation device. [Effects of the Invention]

[0007] In the above-described CO2 recovery and separation apparatus, CO2 can be fixed and CO2-removed gas can be discharged by supplying a CO2-containing gas to a reaction vessel in which the CO2-containing gas is brought into contact with an alkali metal hydroxide aqueous solution or an alkaline earth metal hydroxide aqueous solution. Then, by supplying acid into the reaction vessel in which the CO2 has been fixed, the fixed CO2 can be extracted as a high-concentration CO2-containing gas. As a result, CO2 fixation and separation can be performed in a single reaction vessel, the configuration of the apparatus can be simplified, and the apparatus can be made smaller and its cost reduced. Furthermore, compared to cases where CO2 fixation and separation are performed in separate apparatuses, work efficiency is improved.

[0008] As described above, according to the above embodiment, it is possible to provide a CO2 recovery and separation device that is miniaturized, reduces costs, and improves work efficiency.

[0009] The symbols in parentheses in the claims indicate the correspondence with the specific means described in the embodiments described later, and do not limit the technical scope of this disclosure. [Brief explanation of the drawing]

[0010] The above-mentioned and other purposes, features, and benefits of this disclosure will be further clarified by the following detailed description with reference to the attached drawings. Those drawings are: [Figure 1] Figure 1 is a conceptual vertical cross-sectional view showing the configuration of the CO2 recovery and separation device in Embodiment 1. [Figure 2] Figure 2 is a perspective view showing the configuration of the CO2 recovery and separation device in Embodiment 1. [Figure 3] Figure 3 is a conceptual diagram showing the state before the lid member is connected in Embodiment 1. [Figure 4] Figure 4 is a conceptual diagram showing the state after the lid member is connected in Embodiment 1. [Figure 5] Figure 5 is a diagram illustrating the control flow of the CO2 recovery and separation device in Embodiment 1. [Figure 6] Figure 6 is a conceptual vertical cross-sectional view showing the configuration of the CO2 recovery and separation device in modified form 1. [Modes for carrying out the invention]

[0011] (Embodiment 1) An embodiment of the CO2 recovery and separation apparatus will be described with reference to Figures 1 to 5. As shown in Figure 1, the CO2 recovery and separation apparatus 1 of this embodiment mainly comprises a reaction tank 10, a main body 40, a CO2-containing gas supply unit 41, a CO2-removed gas discharge unit 42, a sensor 43, an acid supply unit 44, a CO2 gas discharge unit 45, and a control device 50.

[0012] 1. Main unit 40 As shown in FIGS. 1 and 2, the main body 40 has a side portion 40c erected in the vertical direction Z, an upper portion 40a located above the side portion 40c, and a lower portion 40b located below the side portion 40c, and is configured to form a substantially U shape by these. A CO2-containing gas supply portion 41, a CO2-removed gas discharge portion 42, a sensor 43, an acid supply portion 44, and a CO2 gas discharge portion 45 are attached to the upper portion 40a. The reaction tank 10 is placed on the lower portion 40b. A weighing scale 401 for detecting the weight of the reaction tank 10 is provided on the lower portion 40b. In FIGS. 1 and 2, the width direction is X, the front-rear direction is Y, and the vertical direction is Z.

[0013] In the present embodiment, the upper portion 40a of the main body 40 is slidable in the vertical direction Z, and the lower portion 40b of the main body 40 is slidable in the front-rear direction Y, so that the reaction tank 10 described later can be easily attached to and detached from the main body 40.

[0014] 2. Reaction tank 10 The reaction tank 10 has a hollow cylindrical shape. An alkali metal hydroxide aqueous solution or an alkaline earth metal hydroxide aqueous solution is introduced into the reaction tank 10 as the aqueous solution L. Examples of the aqueous solution L include, for example, a NaOH aqueous solution, a KOH aqueous solution, a Ca(OH)2 aqueous solution, a Mg(OH)2 aqueous solution, etc. In the present embodiment, a NaOH aqueous solution is used.

[0015] The material of the reaction tank 10 is not particularly limited as long as it has alkali resistance. For example, it can be made of stainless steel, or can be made of metal with a surface treatment such as resin lining. Also, it can be made of resin such as polyethylene resin. When it is made of resin, it is preferable to prevent the internal pressure of the reaction tank 10 from becoming excessively high.

[0016] In this embodiment 1, as shown in Figure 1, the top surface of the reaction vessel 10 has a first opening 11, a second opening 12, a third opening 13, a fourth opening 14, and a fifth opening 15. The first opening 11 is fitted with a CO2-containing gas supply unit 41 (described later), the second opening 12 is fitted with a CO2-removed gas discharge unit 42 (described later), the third opening 13 is fitted with a sensor 43 (described later), the fourth opening 14 is fitted with an acid supply unit 44 (described later), and the fifth opening 15 is fitted with a CO2 gas discharge unit 45 (described later). The outer circumferential surface of each cylindrical portion forming the first to fifth openings 11 to 15 is provided with threaded portions 11a to 15a, which have screw grooves. The reaction vessel 10 is also fitted with a pressure sensor 402 for detecting the pressure inside the reaction vessel 10.

[0017] 3. CO2-containing gas supply unit 41 The CO2-containing gas supply unit 41 supplies CO2-containing gas to the aqueous solution L in the reaction vessel 10. In this embodiment 1, as shown in Figure 1, the CO2-containing gas supply unit 41 has a CO2-containing gas supply unit body 411 and a CO2-containing gas supply nozzle unit 412 that forms the tip of the CO2-containing gas supply unit 41. The CO2-containing gas supply nozzle unit 412 is fixed to the upper part of the reaction vessel 10 with the nozzle inserted through the first opening 11, and the lower end of the CO2-containing gas supply nozzle unit 412 is located in the aqueous solution L.

[0018] As shown in Figure 1, the first opening 11 is covered by the first lid member 21, and the inner circumferential surface of the first lid member 21 has a threaded portion 21a having a thread groove that conforms to the shape of the threaded portion 11a of the first opening 11. Then, by placing the first lid member 21 over the first opening 11 and screwing it in, as shown in Figure 2, the threaded portions 11a and 21a of both are screwed together, and the first lid member 21 is detachably attached to the reaction vessel 10.

[0019] As shown in Figure 3, a through hole 211 is formed in the first lid member 21, and the CO2-containing gas supply unit body 411 is inserted into the through hole 211 in a loosely fitted state and extends outward from the reaction tank 10. An enlarged diameter portion 411a is formed at the tip of the CO2-containing gas supply unit body 411, preventing the CO2-containing gas supply unit body 411 from coming out of the first lid member 21.

[0020] As a result, when attaching the first lid member 21 to the first opening 11, the upper part 40a of the main body 40, which had been moved vertically upward Z1, is moved vertically downward Z2 as shown by arrow P, and the first lid member 21 is placed over the first opening 11 and rotated, so that the CO2-containing gas supply unit main body 411 does not rotate, and the enlarged diameter portion 411a is pressed against the CO2-containing gas supply nozzle portion 412, thereby creating communication between the CO2-containing gas supply unit main body 411 and the CO2-containing gas supply nozzle portion 412.

[0021] The CO2-containing gas supply unit 41 is equipped with a first valve 413 for opening and closing the CO2-containing gas supply unit 41. When the first valve 413 is open, the CO2-containing gas supply unit 41 communicates with the reaction vessel 10, allowing CO2-containing gas to be supplied to the reaction vessel 10. On the other hand, when the first valve 413 is closed, the CO2-containing gas supply unit 41 is blocked from the reaction vessel 10, preventing the supply of CO2-containing gas to the reaction vessel 10, and also preventing backflow from the reaction vessel 10 to the CO2-containing gas supply unit 41. The open / closed state of the first valve 413 is controlled by a control device 50, which will be described later.

[0022] In the CO2-containing gas supply unit 41, although not shown, the end opposite the CO2-containing gas supply nozzle unit 412 is connected to a CO2-containing gas supply source. The CO2-containing gas supply source is not limited, but can be, for example, a CO2-containing gas emission facility that discharges CO2-containing gas as exhaust gas. Examples of CO2-containing gas emission facilities include facilities with boilers, fuel cells, incinerators, and heat treatment facilities.

[0023] 4. CO2 removal gas discharge section 42 The CO2 removal gas discharge unit 42 discharges the CO2 removal gas generated in the reaction vessel 10 to the outside of the reaction vessel 10. The "CO2 removal gas" is obtained by removing CO2 from a CO2-containing gas through a CO2 immobilization reaction, which will be described later. As shown in Figure 1, the CO2 removal gas discharge unit 42 has a CO2 removal gas discharge unit body 421 and a CO2 removal gas discharge nozzle 422 that forms the tip of the CO2 removal gas discharge unit 42. The CO2 removal gas discharge nozzle 422 is fixed to the upper part of the reaction vessel 10, inserted through the second opening 12. The tip of the CO2 removal gas discharge nozzle 422 is located in the upper gas phase within the reaction vessel 10 and is not in contact with the aqueous solution L.

[0024] Then, the CO2 removal gas discharge unit body 421 and the CO2 removal gas discharge nozzle unit 422, like the CO2-containing gas supply unit body 411 and the CO2-containing gas supply nozzle unit 412, become connected to each other as the second lid member 22 is attached to the top of the reaction vessel 10 so as to cover the second opening 12.

[0025] The CO2 removal gas discharge section 42 is provided with a second valve 423 for opening and closing the CO2 removal gas discharge section 42. When the second valve 423 is open, the CO2 removal gas discharge section 42 communicates with the reaction vessel 10, allowing the CO2 removal gas generated in the reaction vessel 10 to be discharged. On the other hand, when the second valve 423 is closed, the CO2 removal gas discharge section 42 is blocked from the reaction vessel 10, preventing the discharge of CO2 removal gas from the reaction vessel 10, and also preventing backflow from the CO2 removal gas discharge section 42 to the reaction vessel 10. The open / closed state of the second valve 423 is controlled by a control device 50, which will be described later.

[0026] In the CO2 removal gas discharge section 42, although not shown, the end opposite the CO2 removal gas discharge nozzle section 422 can be connected to an impurity removal filter. The impurity removal filter removes water-soluble substances in the CO2 removal gas (for example, aqueous NaOH solution that reaches the CO2 removal gas discharge nozzle section 422 as droplets due to bubbling in the reaction vessel 10, and nitrogen oxides NO contained in the exhaust gas). x(and so on) can be removed.

[0027] 5. Sensor 43 The sensor 43 can detect various states of the aqueous solution L, such as the pH, temperature, and product concentration of the aqueous solution L. In this embodiment 1, the sensor 43 detects the pH and temperature of the aqueous solution L. As shown in Figure 1, the sensor 43 has a sensor body 431 and a sensor tip 432 that forms the tip of the sensor 43. The sensor tip 432 is fixed to the upper part of the reaction vessel 10 with the sensor tip 432 inserted through the third opening 13. The tip of the sensor tip 432 is located in the aqueous solution L.

[0028] Then, the sensor body 431 and the sensor tip 432, like the CO2-containing gas supply unit body 411 and the CO2-containing gas supply nozzle unit 412, become in communication with each other as the third lid member 23 is attached to the top of the reaction vessel 10 so as to cover the third opening 13.

[0029] 6. Acid supply section 44 The acid supply unit 44 supplies acid into the reaction vessel 10. As shown in Figure 1, the acid supply unit 44 has an acid supply unit body 441 and an acid supply nozzle 442 that forms the tip of the acid supply unit body 441. The acid supply nozzle 442 is fixed to the upper part of the reaction vessel 10 with the nozzle inserted through the fourth opening 14. The tip of the acid supply nozzle 442 is located in the upper gas phase part of the reaction vessel 10 and is not in contact with the aqueous solution L.

[0030] Then, the acid supply unit body 441 and the acid supply nozzle unit 442, like the CO2-containing gas supply unit body 411 and the CO2-containing gas supply nozzle unit 412, become connected to each other as the fourth lid member 24 is attached to the top of the reaction vessel 10 so as to cover the fourth opening 14.

[0031] The acid supply unit 44 is provided with a third valve 443 that opens and closes the acid supply unit 44. When the third valve 443 is open, the acid supply unit 44 communicates with the reaction vessel 10 and can supply acid into the reaction vessel 10. On the other hand, when the third valve 443 is closed, the acid supply unit 44 is cut off from the reaction vessel 10 and cannot supply acid to the reaction vessel 10, and backflow from the acid supply unit 44 to the reaction vessel 10 is also prevented. The open / closed state of the third valve 443 is controlled by a control device 50, which will be described later.

[0032] In the acid supply unit 44, although not shown in the figure, the end opposite to the acid supply nozzle unit 442 is connected to an acid supply source. The type of acid supplied by the acid supply unit 44 can be an inorganic acid or an organic acid. For example, inorganic acids can be sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, or hydroiodic acid, and organic acids can be carboxylic acids or sulfonic acids, with citric acid, formic acid, acetic acid, gluconic acid, lactic acid, oxalic acid, and tartaric acid being examples. The acid can be at least one of the above acids, and may contain multiple of the above acids. The acid supplied by the acid supply unit 44 may be a solid or an aqueous solution. In this embodiment 1, solid citric acid is used as the acid supplied by the acid supply unit 44.

[0033] 7. CO2 gas exhaust section 45 The CO2 gas discharge section 45 releases the CO2 gas generated in the reaction vessel 10 by the CO2 separation reaction described later to the outside of the reaction vessel 10. As shown in Figure 1, the CO2 gas discharge section 45 has a CO2 gas discharge section body 451 and a CO2 gas discharge nozzle section 452 that forms the tip of the CO2 gas discharge section body 451. The CO2 gas discharge nozzle section 452 is fixed to the upper part of the reaction vessel 10 with the nozzle inserted through the fifth opening 15. The tip of the CO2 gas discharge nozzle section 452 is located in the upper gas phase part inside the reaction vessel 10 and is not in contact with the aqueous solution L.

[0034] Then, the CO2 gas discharge unit body 451 and the CO2 gas discharge nozzle unit 452, like the CO2-containing gas supply unit body 411 and the CO2-containing gas supply nozzle unit 412, will be in communication with each other as the fifth lid member 25 is attached to the top of the reaction vessel 10 so as to cover the fifth opening 15.

[0035] The CO2 gas discharge section 45 is provided with a fourth valve 453 that opens and closes the CO2 gas discharge section 45. When the fourth valve 453 is open, the CO2 gas discharge section 45 communicates with the reaction vessel 10, allowing CO2 gas to be discharged from the reaction vessel 10. On the other hand, when the fourth valve 453 is closed, the CO2 gas discharge section 45 is blocked from the reaction vessel 10, preventing CO2 gas from being discharged from the reaction vessel 10, and also preventing backflow from the CO2 gas discharge section 45 to the reaction vessel 10. The open / closed state of the fourth valve 453 is controlled by a control device 50, which will be described later.

[0036] In the CO2 gas discharge section 45, although not shown in the diagram, the end opposite the CO2 gas discharge nozzle section 452 can be connected to CO2 gas utilization equipment. The CO2 gas utilization equipment is not limited to equipment that utilizes CO2 gas, but examples include agricultural greenhouses, carbonated beverage manufacturing equipment, and manufacturing equipment for products that use CO2 as an additive.

[0037] 8. CO2 fixation reaction Next, the CO2 fixation reaction in reaction vessel 10 will be described. In this embodiment 1, the case in which an aqueous NaOH solution is used as the aqueous solution L will be described.

[0038] First, the CO2 fixation reaction is initiated by bringing the CO2-containing gas into contact with the NaOH aqueous solution in the reaction vessel 10 via the CO2-containing gas supply unit 41. The CO2 fixation reaction proceeds as follows: the reaction shown in Equation 1 is carried out, followed by the reaction shown in Equation 2. 2NaOH+CO2→ Na2CO3+H2O (Formula 1) Na2CO3+CO2+H2O → 2NaHCO3 (formula 2)

[0039] In the reaction vessel 10 shown in Figure 1, NaHCO3 and Na2CO3 are not present before the start of the above reaction. However, depending on the progress of the reaction, one of the following states occurs: Na2CO3 is produced and NaHCO3 is absent; some Na2CO3 further reacts with CO2 to produce NaHCO3 and both are present; or all Na2CO3 is converted to NaHCO3 and there is no Na2CO3 but NaHCO3 is present. Both NaHCO3 and Na2CO3 produced by the above reaction dissolve in the water in the reaction vessel 10 and become aqueous solutions. In this specification, NaHCO3, Na2CO3, and mixtures of both are collectively referred to as "products," and their aqueous solutions are collectively referred to as "aqueous product solutions."

[0040] In this embodiment 1, the above reaction can be initiated by bubbling the exhaust gas F1, which is a CO2-containing gas supplied from the CO2-containing gas supply unit 41, into contact with the NaOH aqueous solution in the reaction vessel 10. In order to improve the frequency of contact between the exhaust gas F1 and the NaOH aqueous solution, it is preferable to discharge the exhaust gas F1 in the form of microbubbles. Microbubbles can be formed by a microbubble former (not shown) provided at the tip of the CO2-containing gas supply nozzle unit 412.

[0041] The progress of the CO2 fixation reaction can be determined by the pH of the aqueous solution L obtained by the sensor 43 and the change in weight detected by the weighing scale 401.

[0042] The CO2 fixation reaction can be stopped by stopping the supply of CO2-containing gas from the CO2-containing gas supply unit 41 to the reaction vessel 10. The supply of CO2-containing gas can be stopped by closing the first valve 413. The timing for stopping the CO2 fixation reaction is not limited, and the state of the product can be any state.

[0043] The above CO2 fixation reaction generates a CO2-removed gas from which CO2 has been removed from the exhaust gas F1. The CO2-removed gas is discharged from the CO2-removed gas discharge section 42 by opening the second valve 423. After the release of the CO2-removed gas is complete, the second valve 423 is closed.

[0044] 9. CO2 separation reaction Next, the CO2 separation reaction in reaction vessel 10 will be described. In this embodiment 1, as described above, an aqueous NaOH solution is used as the aqueous solution L, and then citric acid is used as the acid.

[0045] The CO2 separation reaction is initiated by adding citric acid (C6H8O7) to the reaction vessel 10 via the acid supply unit 44 after the CO2 immobilization reaction. Depending on the products present in the reaction vessel 10, the CO2 separation reaction proceeds according to one of the following equations 3, 4, or 5. C6H8O7+3NaHCO3→ Na3C6H5O7+3H2O+3CO2 (Formula 3) 2C6H8O7+3Na2CO3→ 2Na3C6H5O7+3H2O+3CO2 (Formula 4) C6H8O7+Na3H(CO3)2→ Na3C6H5O7+3H2O+3CO2 (Formula 5) Note that Na3H(CO3)2 represents sodium sesquicarbonate, which is a 1:1 mixture of NaHCO3 and Na2CO3.

[0046] As shown in equations 3 to 5 above, in all cases the CO2 separation reaction produces sodium citrate (Na3C6H5O7, also called trisodium citrate), CO2 gas, and water. Since CO2 gas is generated immediately after the start of the CO2 separation reaction, it is preferable to close the third valve 443 immediately after adding citric acid. The CO2 gas generated by the CO2 separation reaction is released through the CO2 gas discharge section 45 by opening the fourth valve 453.

[0047] The sodium citrate produced by the CO2 separation reaction can be removed from the reaction vessel 10 via a drain cock (not shown) provided in the reaction vessel 10. If the sodium citrate precipitates in the reaction vessel 10, it can be removed as solid sodium citrate; if it is dissolved in the aqueous solution in the reaction vessel 10, it can be removed as an aqueous sodium citrate solution. Both solid sodium citrate and aqueous sodium citrate solutions can be used as pH adjusters in food additives, cosmetics, pharmaceuticals, etc., and are useful as resources.

[0048] 10. Configuration of the control device 50 and control method using the control device 50 The control device 50 is composed of a processing unit and a memory device, and as shown in Figure 1, it includes the functions of a CO2-containing gas supply control unit 51, an acid supply control unit 52, and a CO2 gas discharge control unit 53. The CO2-containing gas supply control unit 51, the acid supply control unit 52, and the CO2 gas discharge control unit 53 all control the opening and closing of the first valve 413 provided in the CO2-containing gas supply unit 41, the second valve 423 provided in the CO2 removal gas discharge unit 42, the third valve 443 provided in the acid supply unit 44, and the fourth valve 453 provided in the CO2 gas discharge unit 45.

[0049] The CO2-containing gas supply control unit 51, for example, opens the first valve 413 and the second valve 423 and closes the third valve 443 and the fourth valve 453 when the CO2 fixation reaction starts. This allows exhaust gas F1 as CO2-containing gas to be supplied to the reaction vessel 10 via the open CO2-containing gas supply unit 41. The exhaust gas F1 can be supplied by drawing the exhaust gas from the CO2 discharge unit using an air pump (not shown) provided between the CO2-containing gas supply control unit 51 and the CO2 discharge unit connected to it.

[0050] The acid supply control unit 52 closes the first valve 413, the second valve 423, and the fourth valve 453 and opens the third valve 443 at the timing when the CO2 separation reaction is started after the CO2 fixation reaction, that is, at the timing when switching between the CO2 fixation reaction and the CO2 separation reaction. As a result, the supply of exhaust gas F1 as CO2-containing gas to the reaction vessel 10 is stopped by closing the CO2-containing gas supply unit 41, and acid can be supplied to the reaction vessel 10 through the open acid supply unit 44. Consequently, the CO2 fixation reaction is terminated by stopping the supply of exhaust gas F1 to the reaction vessel 10, and the CO2 separation reaction is started by supplying acid to the reaction vessel 10.

[0051] The timing of switching between the CO2 fixation reaction and the CO2 separation reaction can be controlled based on at least one of the following: the weight of the reaction vessel 10 obtained by the weighing scale 401, the pH of the aqueous solution in the reaction vessel 10 obtained by the sensor 43, the product concentration in the aqueous solution in the reaction vessel 10 obtained by the sensor 43, or the weight of the product in the reaction vessel 10 obtained or calculated by the weighing scale 401.

[0052] For example, by understanding the progress of the CO2 fixation reaction based on the weight of the reaction vessel 10 obtained by the weighing scale 401 or the pH of the aqueous solution in the reaction vessel 10 obtained by the sensor 43, it is possible to determine that the timing to switch to the CO2 separation reaction has arrived when the amount or concentration of the CO2 fixation product reaches a predetermined standard value.

[0053] Furthermore, the acid supply control unit 52 can control the amount and / or concentration of acid supplied to the reaction vessel 10 based on at least one of the pH of the aqueous solution L in the reaction vessel 10, the product concentration in the aqueous solution L in the reaction vessel 10, or the weight of the product in the reaction vessel 10. For example, the acid supply control unit 52 can calculate the amount of acid to be supplied to the reaction vessel 10 based on at least one of the pH of the aqueous solution L in the reaction vessel 10, the product concentration in the aqueous solution L in the reaction vessel 10, or the weight of the product in the reaction vessel 10, and after opening the fourth valve to start supplying acid from the acid supply unit 44 to the reaction vessel 10, it can control the system to close the fourth valve to stop the supply of acid from the acid supply unit 44 when the calculated amount of acid has been supplied to the reaction vessel 10.

[0054] The CO2 gas discharge control unit 53 closes the first valve 413, the second valve 423, and the third valve 443 and opens the fourth valve 453 at a predetermined timing, for example, after the completion of the CO2 separation reaction or while the CO2 separation reaction is in progress. This allows the CO2 gas generated in the reaction vessel 10 to be discharged from the reaction vessel 10 through the opened CO2 gas discharge unit 45. The discharged CO2 gas can be supplied to a CO2 gas utilization facility to which the CO2 gas discharge unit 45 is connected.

[0055] Furthermore, the timing of CO2 gas discharge from the reaction vessel 10 to the CO2 gas utilization equipment and the amount of CO2 gas discharged can be controlled by the opening and closing control of the fourth valve 453 by the CO2 gas discharge control unit 53, based on, for example, the pressure inside the reaction vessel 10 and the weight of the reaction vessel 10. For example, when a sufficient amount of CO2 gas has accumulated in the reaction vessel 10 due to the CO2 separation reaction, the CO2 gas discharge control unit 53 controls the opening and closing state of the fourth valve 453, thereby discharging CO2 gas F3 from the CO2 gas discharge unit 45 in accordance with the amount of CO2 gas required by the CO2 utilization equipment to which the CO2 gas discharge unit 45 is connected, and supplying it to the CO2 utilization equipment.

[0056] 11. Description of Control Modes Next, the control method in this embodiment 1 will be explained using the flowchart shown in Figure 5. As shown in step S1, after the CO2 immobilization reaction S1 is performed, the CO2 separation reaction S2 is performed.

[0057] First, in the CO2 fixation reaction S1, as shown in Figure 5, in step S11, an aqueous NaOH solution is added to the reaction vessel 10 as an aqueous solution L as a preparation step. The concentration of the aqueous NaOH solution was set to 5.0% for easy handling as it is not classified as a hazardous substance. In step S11, the CO2-containing gas supply control unit 51 opens the first valve 413 and the second valve 423, and closes the third valve 443 and the fourth valve 453.

[0058] Next, in step S12, the CO2-containing gas supply control unit 51 opens the first valve 413 and supplies exhaust gas F1 as CO2-containing gas to the reaction vessel 10 by bubbling it from the CO2-containing gas supply unit 41. This starts the CO2 immobilization reaction S1. Then, the CO2 removal gas generated as the reactions of equations 1 and 2 progress is discharged from the CO2 removal gas discharge unit 42, which has been opened by the CO2-containing gas supply control unit 51. After that, in step S13, the pH of the aqueous solution L is obtained by the sensor 43.

[0059] Then, in step S14, the acid supply control unit 52 determines whether the acquired pH has reached the target pH. The target pH can be determined according to the products generated in the CO2 immobilization reaction. In this embodiment 1, the target pH is set to the pH corresponding to the NaHCO3 aqueous solution with a large amount of CO2 immobilized as a product.

[0060] In step S14, if the acid supply control unit 52 determines that the acquired pH has not reached the target pH, the process proceeds to No in step S14 and returns to step S13. On the other hand, if the acid supply control unit 52 determines in step S14 that the target pH has been reached, it determines that the timing to switch to the CO2 separation reaction S2 has arrived and proceeds to Yes in step S14. Then, in step S15, the acid supply control unit 52 closes the first valve 413 to stop the supply of exhaust gas F1, and simultaneously closes the second valve 423. This terminates the CO2 fixation reaction S1.

[0061] Next, in step S21, the acid supply control unit 52 opens the third valve 443 and supplies citric acid from the acid supply unit 44 to the reaction vessel 10. In this flow, in step S21, the acid supply control unit 52 calculates the amount of citric acid to be supplied to the reaction vessel 10 based on the pH of the aqueous solution L in the reaction vessel 10. After the calculated amount of citric acid has been supplied to the reaction vessel 10, the acid supply control unit 52 immediately closes the third valve 443. This starts the CO2 separation reaction S2.

[0062] Subsequently, in step S22, the internal pressure of the reaction vessel 10 is obtained by the pressure sensor 402. The internal pressure of the reaction vessel 10 increases as the CO2 separation reaction progresses and CO2 gas is generated. Then, in step S23, the CO2 gas discharge control unit 53 determines whether the internal pressure of the reaction vessel 10 has reached the target value. The target value of the internal pressure is set by the CO2 gas discharge control unit 53, which calculates the amount of CO2 fixed in the CO2 fixation reaction S1, calculates the amount of CO2 gas that can be separated based on this, and sets the increase in internal pressure corresponding to that amount of CO2 gas as the target value of the internal pressure.

[0063] In step S23, if the CO2 gas discharge control unit 53 determines that the acquired internal pressure of the reaction vessel 10 has not reached the target value, the process proceeds to step S23 No and returns to step S22. On the other hand, in step S23, if the CO2 gas discharge control unit 53 determines that the acquired internal pressure of the reaction vessel 10 has reached the target value, the process proceeds to step S23 Yes. Then, in step S24, the CO2 gas discharge control unit 53 opens the fourth valve 453 and discharges CO2 gas from the CO2 gas discharge unit 45.

[0064] In step S24, the amount of CO2 gas discharged is controlled by the CO2 gas discharge control unit 53 by controlling the open state of the fourth valve 453 according to the amount of CO2 gas required by the CO2 utilization equipment to which the CO2 gas is supplied. When the discharge of CO2 gas is finished, the CO2 separation reaction S2 is terminated, and the CO2 gas discharge control unit 53 closes the fourth valve 453 to end the flow.

[0065] In this flow, the timing to switch to the CO2 separation reaction S2 was determined when it was determined that the pH of the reaction vessel 10 reached the target pH in the CO2 immobilization reaction S1. However, instead, the timing to switch to the CO2 separation reaction S2 may be determined when it is determined that the weight of the reaction vessel 10, the product concentration in the reaction vessel 10, or the weight of the product has reached a predetermined target value.

[0066] In this flowchart, the amount of citric acid to be supplied to the reaction vessel 10 was calculated based on the pH of the aqueous solution L in the reaction vessel 10. Alternatively, the amount of citric acid to be supplied to the reaction vessel 10 may be calculated based on the product concentration in the aqueous solution L in the reaction vessel 10, or the weight of the product in the reaction vessel 10.

[0067] Furthermore, in this flow, CO2 gas is released from the CO2 gas discharge section 45 when it is determined that the internal pressure of the reaction vessel 10 has reached a target value in the CO2 separation reaction S2. Alternatively, the system may be controlled to release CO2 gas when it is determined that the weight change of the reaction vessel 10 has reached a predetermined target value in the CO2 separation reaction S2.

[0068] Furthermore, in this flow, the second valve 423 was closed at the start of the CO2 separation reaction S2. Alternatively, the second valve 423 may be left open at the start of the CO2 separation reaction S2, and then closed after the gas phase of the reaction vessel 10 has been filled with CO2 gas. This allows the CO2 removal gas that remained in the reaction vessel 10 at the start of the CO2 separation reaction S2 to be discharged from the reaction vessel 10, thus enabling the discharge of even higher concentration CO2 gas from the CO2 gas discharge section 45.

[0069] 12. Effects Next, the effects and advantages of the CO2 recovery and separation apparatus 1 of this embodiment will be described in detail. According to the CO2 recovery and separation apparatus 1 of this embodiment, by supplying CO2-containing gas to a reaction vessel 10 in contact with an aqueous NaOH solution, CO2 can be immobilized and CO2 removal gas can be discharged. Then, by supplying acid into the reaction vessel 10 in which the CO2 has been immobilized, the immobilized CO2 can be extracted as a high-concentration CO2-containing gas. As a result, since CO2 immobilization and separation can be performed in a single reaction vessel 10, the configuration of the apparatus can be simplified, and the apparatus can be made smaller and the cost of the apparatus can be reduced. Furthermore, compared to cases in which CO2 immobilization and separation are performed in different apparatuses, work efficiency is improved.

[0070] Furthermore, in this embodiment 1, the CO2-containing gas supply unit 41, CO2 removal gas discharge unit 42, sensor 43, acid supply unit 44, and CO2 gas discharge unit 45 attached to the reaction tank 10 can all be separated while their respective ends are fixed to the top of the reaction tank 10. This allows the reaction tank 10 to be easily removed from the main body 40 of the CO2 recovery and separation device 1 and carried, improving work efficiency.

[0071] In this first embodiment, the acid supplied to the reaction vessel 10 may include at least one of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, hydroiodic acid, citric acid, formic acid, acetic acid, gluconic acid, lactic acid, oxalic acid, and tartaric acid. These acids are readily available and easy to handle, thus improving the efficiency of CO2 separation.

[0072] Furthermore, in this embodiment 1, an aqueous NaOH solution is stored as the aqueous solution L in the reaction vessel 10, and citric acid is used as the acid. This makes it possible to produce sodium citrate, which is highly useful as a resource, through the CO2 separation reaction, and to effectively utilize the products of the CO2 separation reaction.

[0073] Furthermore, in this embodiment 1, a control device 50 is further provided, and the control device 50 includes an acid supply control unit 52 that controls the timing of stopping the supply of CO2-containing gas from the CO2-containing gas supply unit 41 and starting the supply of acid into the reaction vessel 10 from the acid supply unit 44, based on at least one of the weight of the reaction vessel 10, the pH of the aqueous solution in the reaction vessel 10, the concentration of the product in the aqueous solution L in the reaction vessel 10, or the weight of the product in the reaction vessel 10. This makes it possible to switch from the CO2 immobilization reaction to the CO2 separation reaction at an appropriate timing and improves work efficiency.

[0074] Furthermore, in this embodiment 1, a first valve 413 for opening and closing the CO2-containing gas supply unit 41 and a third valve 433 for opening and closing the acid supply unit 44 are further included, and the acid supply control unit 52 is configured to control the open / closed state of the first valve 413 for opening and closing the CO2-containing gas supply unit 41 and the open / closed state of the third valve 433 for opening and closing the acid supply unit 44. As a result, the switching from the CO2 fixation reaction to the CO2 separation reaction can be performed at the appropriate timing with a simple configuration, improving work efficiency, and the increase in equipment costs can be suppressed because the configuration is not complex.

[0075] Furthermore, in this embodiment 1, the acid supply control unit 52 is configured to control the amount and / or concentration of acid supplied to the reaction vessel 10 based on at least one of the pH of the aqueous solution L in the reaction vessel 10, the concentration of the product in the aqueous solution L in the reaction vessel 10, or the weight of the product in the reaction vessel 10. This prevents the consumption of unnecessary acid, thereby reducing costs, and ensures that the fixed CO2 is reliably discharged from the reaction vessel 10 and utilized, thus further promoting the utilization of fixed CO2.

[0076] Furthermore, in this embodiment 1, the control device 50 includes a CO2 gas discharge control unit 53 that controls the amount of CO2 gas discharged from the CO2 gas discharge unit 45 based on at least one of the pressure inside the reaction vessel 10 and the weight of the reaction vessel 10. This ensures that CO2 gas is reliably supplied to the CO2 gas utilization equipment to which the CO2 gas discharge unit 45 is connected, thereby further promoting the utilization of fixed CO2.

[0077] Furthermore, in this embodiment 1, a fourth valve 453 for opening and closing the CO2 gas discharge section 45 is further provided, and the CO2 gas discharge control unit 53 is configured to control the open / closed state of the fourth valve 453 for opening and closing the CO2 gas discharge section 45. This ensures a reliable supply of CO2 gas to the CO2 gas utilization equipment to which the CO2 gas discharge unit 45 is connected, further promoting the utilization of fixed CO2, while also suppressing increases in equipment costs because the configuration is not complex.

[0078] As described above, according to this embodiment 1, it is possible to provide a CO2 recovery and separation device 1 that is miniaturized, cost-reduced, and has improved work efficiency.

[0079] In this embodiment 1, a stainless steel cylindrical container was used as the reaction vessel 10. However, instead, as shown in modified form 1 in Figure 6, a polyethylene container, specifically a commercially available general-purpose poly tank, may be used as the reaction vessel 10. In this case, it is preferable to control the opening and closing state of the CO2 gas discharge section 45 with the CO2 gas discharge control section 53 so that the internal pressure of the reaction vessel 10 does not become excessively high during the CO2 separation reaction. The poly tank used as the reaction vessel 10 may be, for example, one intended for transporting and storing liquids such as drinking water, kerosene, or wastewater. Its capacity is not limited, and a 10 to 20 L tank can be used.

[0080] In the modified form 1 shown in Figure 6, the reaction vessel 10 has a first opening 11 and a second opening 12. The reaction vessel 10 is mounted on a trolley 404 having tires 403 and is restrained to the trolley 404 by restraint bands 405 to prevent displacement relative to the trolley 404. The reaction vessel 10 can be easily moved via the trolley 404 even when the aqueous solution L is stored inside. A handle 16 is provided on the upper surface of the reaction vessel 10 between the first opening 11 and the second opening 12. The handle 16 is integrally molded with the reaction vessel 10.

[0081] In modified form 1, as shown in Figure 6, the CO2-containing gas supply unit 41 and the acid supply unit 44 are attached to the first lid member 21, and the CO2 removal gas discharge unit 42 and the CO2 gas discharge unit 45 are attached to the second lid member 22. The other components in modified form 1 are the same as those in embodiment 1 and are denoted by the same reference numerals as in embodiment 1, and their descriptions are omitted. Furthermore, modified form 1 also provides the same effects and advantages as embodiment 1.

[0082] This disclosure is described in accordance with embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also encompasses various variations and variations within the equivalence range. In addition, various combinations and forms, as well as other combinations and forms that include one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

Claims

1. Add CO2 to an aqueous alkali metal hydroxide solution or an aqueous alkaline earth metal hydroxide solution. ２ A reaction vessel (10) into which the contained gas is brought into contact, The above CO ２ CO2 supplied as a gas containing CO2 ２ The gas supply unit (41) and CO ２ CO2 has been removed. ２ CO2 is emitted as a removed gas. ２ The removal gas discharge section (42) and An acid supply unit (44) that supplies acid into the above reaction vessel, CO generated in the above reaction vessel ２ CO2 emissions ２ Gas discharge section (45) and Based on at least one of the weight of the reaction tank, the pH of the aqueous solution in the reaction tank, the product concentration in the aqueous solution in the reaction tank, or the product weight in the reaction tank, the CO ２ supply of the CO ２ containing gas is stopped, and a control device (50) comprising an acid supply control unit (52) for controlling the timing to start the supply of the acid into the reaction tank in the acid supply unit A valve (413) for opening and closing the CO2-containing gas supply section mentioned above, A valve (433) for opening and closing the above-mentioned acid supply unit, Equipped with, The above-mentioned acid supply control unit controls the open / closed state of the valve (413) that opens and closes the CO2-containing gas supply unit, and the open / closed state of the valve (433) that opens and closes the acid supply unit, CO ２ Recovery and separation device (1).

2. The above acid comprises at least one of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, hydroiodic acid, citric acid, formic acid, acetic acid, gluconic acid, lactic acid, oxalic acid, and tartaric acid, as described in claim 1. ２ Recovery and separation device.

3. The above alkali metal hydroxide aqueous solution is an aqueous NaOH solution, and the above acid is citric acid, as described in claim 1. ２ Recovery and separation device.

4. The acid supply control unit controls the amount and / or concentration of acid supplied to the reaction vessel based on at least one of the pH of the aqueous solution in the reaction vessel, the concentration of the product in the aqueous solution in the reaction vessel, or the weight of the product in the reaction vessel, as described in any one of claims 1 to 3. ２ Recovery and separation device.

5. The control device, based on at least one of the pressure inside the reaction vessel and the weight of the reaction vessel, controls the CO ２ The above CO at the gas discharge section ２ Controlling gas emissions CO2 ２ CO2 according to any one of claims 1 to 3, comprising a gas discharge control unit (53) ２ Recovery and separation device.

6. The above CO ２ It is further equipped with a valve (453) for opening and closing the gas discharge section, The above CO ２ The gas emission control unit controls the above CO ２ The CO2 discharge port according to claim 5, which controls the open / closed state of the valve (453) that opens and closes the gas discharge port. ２ Recovery and separation device.

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