Carbon dioxide separation recovery device and carbon dioxide separation recovery method

Abstract

To provide a device and a method to separate and recover carbon dioxide by a chemical absorption method where the chemical reaction efficiency between carbon dioxide and an absorbent is enhanced without modifying carbon dioxide absorbed by the absorbent.SOLUTION: In a carbon dioxide separation recovery device 10 where a carbon dioxide-containing gas and an absorbent 1 are in contact, carbon dioxide is absorbed in the absorbent 1 and carbon dioxide is separated from the gas and recovered, an electric field formation device 4 to form an electric field where an anion and a cation generated by a chemical reaction between carbon dioxide and the absorbent 1 are migrated in a direction where carbon dioxide apart from the reaction field of the absorbent 1 is equipped.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a carbon dioxide separation and recovery apparatus and a carbon dioxide separation and recovery method.

Background Art

[0002] As a carbon dioxide treatment method for modifying carbon dioxide into another substance, there is known one that performs a carbon dioxide absorption step of dissolving carbon dioxide in an alkaline aqueous solution and an electrolysis step of electrolyzing the alkaline aqueous solution in which carbon dioxide is dissolved (see, for example, Patent Document 1). In the carbon dioxide treatment method described in Patent Document 1, during the execution of the electrolysis step, by applying an inter-electrode voltage so that the value of the electrolytic current becomes 150 to 300 A, the carbon dioxide dissolved in the alkaline aqueous solution is modified into a substance that can remain in the alkaline aqueous solution.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a chemical absorption method in which a gas containing carbon dioxide is brought into contact with an absorbent liquid to chemically react to separate and recover carbon dioxide from the gas, as the reaction proceeds, the ionic concentration in the product system increases. Therefore, as the equilibrium collapses over time, the reaction from the starting system to the product system becomes difficult to occur, and the efficiency of the chemical reaction between carbon dioxide and the absorbent liquid decreases.

[0005] In the carbon dioxide treatment method described in Patent Document 1, in the electrolysis step, the carbon dioxide dissolved in the alkaline aqueous solution is modified into another substance that can remain in the alkaline aqueous solution, and excessive treatment is performed from the viewpoint of improving the efficiency of the reaction from the starting system to the product system.

[0006] In view of the above circumstances, the present invention aims to improve the efficiency of the chemical reaction between carbon dioxide and an absorption liquid without denaturing the carbon dioxide absorbed by the absorption liquid in an apparatus and method for separating and recovering carbon dioxide by a chemical absorption method.

Means for Solving the Problems

[0007] The carbon dioxide recovery apparatus of the present invention is a carbon dioxide separation and recovery apparatus that separates and recovers carbon dioxide from a gas by bringing the gas containing carbon dioxide into contact with an absorption liquid to absorb the carbon dioxide into the absorption liquid, and includes an electric field forming unit that forms an electric field in which anions and cations generated by the chemical reaction between the carbon dioxide and the absorption liquid migrate in a direction away from the reaction field of the absorption liquid.

[0008] The carbon dioxide recovery method of the present invention is a carbon dioxide separation and recovery method that separates and recovers carbon dioxide from a gas by bringing the gas containing carbon dioxide into contact with an absorption liquid to absorb the carbon dioxide into the absorption liquid, and forms an electric field in which anions and cations generated by the chemical reaction between the carbon dioxide and the absorption liquid migrate in a direction away from the reaction field of the absorption liquid.

Effects of the Invention

[0009] According to the present invention, in an apparatus and method for separating and recovering carbon dioxide by a chemical absorption method, the efficiency of the chemical reaction between carbon dioxide and an absorption liquid can be improved without denaturing the carbon dioxide absorbed by the absorption liquid.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

[0011] Hereinafter, the present invention will be described along with preferred embodiments. Note that the present invention is not limited to the embodiments shown below, and the embodiments shown below can be appropriately modified without departing from the gist of the present invention. Further, in the embodiments shown below, there are some places where the illustration and description of some configurations are omitted. For the details of the omitted technology, well-known or well-understood technologies are appropriately applied within the range where there is no contradiction with the content described below.

[0012] FIG. 1 is a diagram showing an outline of a carbon dioxide separation and recovery apparatus 10 according to an embodiment of the present invention. The carbon dioxide separation and recovery apparatus 10 shown in this figure is an apparatus that separates and recovers carbon dioxide from a gas containing carbon dioxide (CO2), such as exhaust gas, by a chemical absorption method.

[0013] The carbon dioxide separation and recovery apparatus 10 includes a container 2, a gas supply device 3, and an electric field forming device 4. The container 2 is a tower or a tank to which the absorption liquid 1 and the gas are supplied. The gas supply device 3 includes a gas supply pipe 31 inserted into the container 2 from the upper part of the container 2. The tip of the gas supply pipe 31 is arranged near the center of the absorption liquid 1. The gas supply device 3 introduces the gas into the vicinity of the center of the absorption liquid 1 by bubbling through the gas supply pipe 31 and brings it into contact with the absorption liquid 1.

[0014] Near the center of the absorption liquid 1 in the container 2, carbon dioxide contained in the gas chemically reacts with the absorption liquid 1, and the carbon dioxide is absorbed by the absorption liquid 1. The absorption liquid 1 that has absorbed carbon dioxide in the container 2 is supplied to a regeneration tower (not shown). The gas from which carbon dioxide has been separated is discharged from the container 2. In the regeneration tower, by performing processes such as heating and depressurization, carbon dioxide is separated from the absorption liquid 1. The absorption liquid 1 from which carbon dioxide has been separated is supplied to the container 2.

[0015] The absorption liquid 1 is an alkaline aqueous solution such as an amine used in the chemical absorption method, for example, monoethanolamine (MEA). Note that the absorption liquid 1 may be a primary amine other than monoethanolamine, or a secondary amine or a tertiary amine.

[0016] Typical examples of the chemical reaction between carbon dioxide and the absorption liquid 1 are the carbamate reaction of the following (1) and the bicarbonate reaction of the following (2). In the following (1) and (2), R and R' represent substituents of the alkyl group bonded to the amine group.

Chemical formula

Chemical formula

[0017] In the chemical reaction between carbon dioxide and the absorption liquid 1, by transitioning from the origin system (the product on the left side) to the product system (the product on the right side), the carbon dioxide becomes carbamate ion (RR’NCOO - ), or bicarbonate ion (HCO3 -) and will be absorbed by the absorption liquid 1. However, as the chemical reaction between carbon dioxide and the absorption liquid 1 proceeds and the concentration of carbamate ions or bicarbonate ions increases, the ionic concentration in the production system increases. Therefore, as the equilibrium collapses over time, the reaction from the original system to the production system becomes less likely to occur, and the efficiency of the chemical reaction between carbon dioxide and the absorption liquid 1 decreases. Therefore, in the carbon dioxide separation and recovery device 10 according to the present embodiment, an electric field forming device 4 is provided to improve the efficiency of the chemical reaction between carbon dioxide and the absorption liquid 1.

[0018] The electric field forming device 4 includes a positive electrode 41 and a negative electrode 42 inserted into the container 2 from the upper part of the container 2, and a power source 43 that applies a voltage between the positive electrode 41 and the negative electrode 42. The positive electrode 41 and the negative electrode 42 are inserted into the absorption liquid 1 so as to sandwich the air supply pipe 31 on the left and right. When a voltage is applied between the positive electrode 41 and the negative electrode 42 by the power source 43, an electric field is formed between the positive electrode 41 and the negative electrode 42.

[0019] Here, the electric field forming device 4 applies a voltage between the positive electrode 41 and the negative electrode 42 so that a weak current flows between the positive electrode 41 and the negative electrode 42. This weak current causes anions such as carbamate ions and bicarbonate ions generated by the chemical reaction between carbon dioxide and the absorption liquid 1 to migrate from the reaction field to the positive electrode 41 side, and cations such as protonated amine (RR’NH2 + ) to migrate from the reaction field to the negative electrode 42 side. On the other hand, this weak current does not electrolyze the absorption liquid 1 or modify the carbon dioxide absorbed by the absorption liquid 1.

[0020] That is, the electric field forming device 4 forms an electric field in the absorption liquid 1 with a magnitude such that it does not electrolyze the absorption liquid 1 or modify the carbon dioxide absorbed by the absorption liquid 1. It should be noted that it is only necessary to form a potential difference between the positive electrode 41 and the negative electrode 42, and the value of the current between the positive electrode 41 and the negative electrode 42 may be 0 A.

[0021] As described above, in the carbon dioxide separation and recovery apparatus 10 according to the present embodiment, the electric field forming device 4 forms an electric field in which anions and cations generated by the chemical reaction between carbon dioxide and the absorption liquid 1 migrate in a direction away from the reaction field of the absorption liquid 1. Thereby, it is possible to suppress an increase in the ionic concentration in the generation system near the reaction field of the absorption liquid 1 as the chemical reaction progresses, suppress a decrease in the reaction from the original system to the generation system, and improve the efficiency of the chemical reaction between carbon dioxide and the absorption liquid 1.

[0022] Further, the electric field forming device 4 includes a positive electrode 41 and a negative electrode 42 arranged so as to sandwich the reaction field of the absorption liquid 1, and a voltage is applied between the positive electrode 41 and the negative electrode 42 so that the current between the positive electrode 41 and the negative electrode 42 has a magnitude that does not denature carbon dioxide. Thereby, it is possible to improve the efficiency of the chemical reaction between carbon dioxide and the absorption liquid 1 without denaturing the carbon dioxide absorbed by the absorption liquid 1.

[0023] FIG. 2 is a diagram showing an outline of a carbon dioxide separation and recovery apparatus 100 according to another embodiment of the present invention. Note that the same reference numerals are given to the same configurations as those in the above-described embodiment, and the description of the above-described embodiment is incorporated herein.

[0024] As shown in FIG. 2, the carbon dioxide separation and recovery apparatus 100 includes a container 2, a gas supply device 13, an electric field forming device 14, and a stirring device 15. The gas supply device 13 includes a gas supply pipe 131 inserted into the container 2 from the upper part of the container 2. The tip of the gas supply pipe 131 is arranged facing the vicinity of the center of the liquid surface of the absorption liquid 1. The gas supply device 13 introduces gas into the vicinity of the center of the liquid surface of the absorption liquid 1 through the gas supply pipe 131.

[0025] The stirring device 15 is arranged near the center of the bottom of the container 2. The stirring device 15 stirs the absorption liquid 1 in the container 2 to bring the gas supplied from the gas supply pipe 131 near the center of the liquid surface of the absorption liquid 1 into contact with the absorption liquid 1. In the vicinity of the center of the absorption liquid 1 in the container 2, carbon dioxide contained in the gas chemically reacts with the absorption liquid 1, and the carbon dioxide is absorbed by the absorption liquid 1.

[0026] The electric field forming device 14 includes a positive electrode 41 and a negative electrode 42 inserted into the container 2 from the bottom of the container 2, and a power source 43 that applies a voltage between the positive electrode 41 and the negative electrode 42. The positive electrode 41 and the negative electrode 42 are inserted into the absorption liquid 1 so as to sandwich the stirring device 15 on the left and right. When a voltage is applied between the positive electrode 41 and the negative electrode 42 by the power source 43, an electric field is formed between the positive electrode 41 and the negative electrode 42.

[0027] Similar to the above-described embodiment, the electric field forming device 14 applies a voltage between the positive electrode 41 and the negative electrode 42 so that a weak current flows between the positive electrode 41 and the negative electrode 42. That is, the electric field forming device 14 forms an electric field in the absorption liquid 1 having a magnitude such that it does not electrolyze the absorption liquid 1 or modify the carbon dioxide absorbed in the absorption liquid 1.

[0028] As described above, in the carbon dioxide separation and recovery device 100 according to the present embodiment, the gas supplied to the liquid surface of the absorption liquid 1 by the air supply device 13 and the absorption liquid 1 come into contact with each other by the stirring device 15 provided at the bottom of the absorption liquid 1 stirring the absorption liquid 1. Therefore, a reaction field where a chemical reaction between carbon dioxide and the absorption liquid 1 occurs is formed near the liquid surface of the absorption liquid 1.

[0029] In the carbon dioxide separation and recovery device 100 according to the present embodiment, the positive electrode 41 and the negative electrode 42 are inserted into the absorption liquid 1 so as to sandwich the reaction field formed near the liquid surface of the absorption liquid 1, and an electric field is formed in which anions and cations migrate in a direction away from the reaction field of the absorption liquid 1. Thereby, it is possible to suppress an increase in the ionic concentration in the generation system near the reaction field of the absorption liquid 1 as the chemical reaction proceeds, suppress a decrease in the reaction from the original system to the generation system, and improve the efficiency of the chemical reaction between carbon dioxide and the absorption liquid 1.

[0030] FIG. 3 is a diagram showing an outline of a carbon dioxide separation and recovery device 200 according to another embodiment of the present invention. In addition, the same reference numerals are given to the same configurations as those in the above-described embodiment, and the description of the above-described embodiment is incorporated herein.

[0031] As shown in FIG. 3, the carbon dioxide separation and recovery device 200 includes a container 2, a gas supply device 3, and an electric field forming device 24. The electric field forming device 24 includes a positive electrode 41, a negative electrode 42, a power source 43, a container 244, and an electrolytic solution 245.

[0032] The container 244 houses the container 2 and the electrolytic solution 245. The container 2 is inserted into the electrolytic solution 245. The electrolytic solution 245 is a high-resistance liquid in which electrolysis hardly occurs.

[0033] The positive electrode 41 and the negative electrode 42 are inserted into the electrolytic solution 245 so as to sandwich the container 2 on the left and right. When a voltage is applied between the positive electrode 41 and the negative electrode 42 by the power source 43, an electric field is formed between the positive electrode 41 and the negative electrode 42.

[0034] Similar to the above-described embodiment, the electric field forming device 24 applies a voltage between the positive electrode 41 and the negative electrode 42 so that a weak current flows between the positive electrode 41 and the negative electrode 42. That is, the electric field forming device 24 forms an electric field in the absorption liquid 1 having a magnitude such that it does not electrolyze the absorption liquid 1 or modify the carbon dioxide absorbed by the absorption liquid 1.

[0035] As described above, in the carbon dioxide separation and recovery device 200 according to the present embodiment, the electric field forming device 24 includes a container 244 that houses the container 2 and the electrolytic solution 245, and the positive electrode 41 and the negative electrode 42 are inserted into the electrolytic solution 245 so as to sandwich the container 2. Thereby, without electrolyzing the absorption liquid 1, an electric field can be formed between the positive electrode 41 and the negative electrode 42 arranged so as to sandwich the reaction field of the absorption liquid 1, in which anions migrate to the positive electrode 41 side and cations migrate to the negative electrode 42 side.

[0036] FIG. 4 is a diagram showing an outline of a carbon dioxide separation and recovery device 300 according to another embodiment of the present invention. Note that the same reference numerals are given to the same configurations as those in the above-described embodiment, and the description of the above-described embodiment is incorporated herein.

[0037] As shown in FIG. 4, the carbon dioxide separation and recovery device 300 includes a container 2, a gas supply device 3, and an electric field forming device 34. The electric field forming device 34 includes electrodes 341 and 342, and a power source 43. Both ends of the electrode 341 are connected to the positive and negative electrodes of the power source 43. The electrode 342 is grounded.

[0038] The electrode 341 and the electrode 342 are arranged so as to sandwich the container 2 on the left and right. When a voltage is applied to the electrode 341 by the power source 43, an electric field is formed between the electrode 341 and the electrode 342.

[0039] Similar to the above-described embodiment, the electric field forming device 34 applies a voltage to the electrode 341 so that a weak current flows between the electrode 341 and the electrode 342. That is, the electric field forming device 34 forms an electric field in the absorption liquid 1 having a magnitude such that the absorption liquid 1 is not electrolyzed and the carbon dioxide absorbed in the absorption liquid 1 is not denatured.

[0040] As described above, in the carbon dioxide separation and recovery device 300 according to the present embodiment, the electrode 341 connected to the power source 43 and the grounded electrode 342 are arranged so as to sandwich the container 2. Thereby, an electric field can be formed between the electrode 341 and the electrode 342 arranged so as to sandwich the reaction field of the absorption liquid 1 without electrolyzing the absorption liquid 1, and anions migrate to the electrode 341 side and cations migrate to the electrode 342 side.

[0041] Although the present invention has been described based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and modifications may be made to the above-described embodiment without departing from the spirit of the present invention, and known and well-known technologies may be appropriately combined.

Explanation of Reference Numerals

[0042] 1: Absorption liquid 2: Container (first container) 4: Electric field forming device (electric field forming unit) 10: Carbon dioxide separation and recovery device 14: Electric field forming device (electric field forming unit) 24: Electric field forming device (electric field forming section) 34: Electric field forming device (electric field forming section) 41: Positive electrode (electrode) 42: Negative electrode (electrode) 100: Carbon dioxide separation and recovery device 200: Carbon dioxide separation and recovery device 244: Container (second container) 245: Electrolyte 300: Carbon dioxide separation and recovery device 341: Electrode 342: Electrode

Claims

1. A carbon dioxide separation and recovery device that separates and recovers carbon dioxide from a gas by bringing a gas containing carbon dioxide into contact with an absorption liquid and absorbing the carbon dioxide into the absorption liquid, The carbon dioxide separation and recovery device comprising an electric field forming unit that forms an electric field in which anions and cations generated by a chemical reaction between the carbon dioxide and the absorption liquid migrate in a direction away from the reaction field of the absorption liquid.

2. The carbon dioxide separation and recovery device according to claim 1, wherein the electric field forming unit includes a pair of electrodes arranged so as to sandwich the reaction field, and a voltage is applied to the pair of electrodes such that the current between the pair of electrodes has a magnitude that does not denature the carbon dioxide.

3. Comprising a first container to which the absorption liquid and the gas are supplied, The electric field forming unit, Comprising a second container that houses the first container and an electrolytic solution, The pair of electrodes are inserted into the electrolytic solution so as to sandwich the first container. The carbon dioxide separation and recovery device according to claim 2.

4. Comprising a container to which the absorption liquid and the gas are supplied, The pair of electrodes are arranged so as to sandwich the container, One of the pair of electrodes is connected to a power source, The other of the pair of electrodes is grounded. The carbon dioxide separation and recovery device according to claim 2.

5. A carbon dioxide separation and recovery method that separates and recovers carbon dioxide from a gas by bringing a gas containing carbon dioxide into contact with an absorption liquid and absorbing the carbon dioxide into the absorption liquid, The carbon dioxide separation and recovery method forming an electric field in which anions and cations generated by a chemical reaction between the carbon dioxide and the absorption liquid migrate in a direction away from the reaction field of the absorption liquid.

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