Energy-Saving System And Method For Direct Air Capture With Precise Ion Control

Abstract

Disclosed is an energy-saving system and method for direct air capture with precise ion control. The system includes an air conveying device, an air distribution device and a CO.sub.2 adsorption device with a moisture swing adsorbent with high CO.sub.2 adsorption capacity, where the air conveying device, the air distribution device and the CO.sub.2 adsorption device are connected in sequence, and the CO.sub.2 adsorption device is provided with a spray desorption device; a valence-state ion sieving device; a pH swing regeneration device; and a CO.sub.2 regeneration device. In accordance with the energy-saving system provided by the present disclosure, ultra-low concentration of CO.sub.2 in the air can be enriched to the concentration of 95% step by step for industrial application or biological application at room temperature and pressure by consuming the electricity which cannot be connected to a power grid.

Claims

1. An energy-saving system for direct air capture with precise ion control, comprising an air conveying device (1), an air distribution device (2), and a CO.sub.2 adsorption device (3) internally provided with moisture swing adsorbents with high CO.sub.2 adsorption capacity, wherein the air conveying device (1), the air distribution device (2) and the CO.sub.2 adsorption device (3) are connected in sequence, and the CO.sub.2 adsorption device (3) is provided with a spraying device (4); a valence-state ion sieving device (5), wherein valence ion selective anion membranes (11) and cation membranes (10) through which OH can pass but CO.sub.3.sup.2? is prevented are alternately arranged, and an anode plate (9) and a cathode plate (8) are arranged on both sides of the valence-state ion sieving device (5) to form a constant electric field; in the valence-state ion sieving device (5), an OH removing chamber (12) receives desorption solution flowing out from the CO.sub.2 adsorption device (3), and the aqueous solution rich in CO.sub.3.sup.2? flowing out from an outlet of the OH removing chamber is pumped into a CO.sub.2 regeneration device (7), and an outlet of the OH-receiving chamber (13) is connected with a pH swing regeneration device (6); a pH swing regeneration device (6), which employs a pH swing regeneration system and is configured to produce acid solution and to concentrate alkaline solution, wherein the concentrated alkaline solution outlet is connected to the spraying device (4), the produced acid solution flows into the CO.sub.2 regeneration device (7) to react with the aqueous solution rich in CO.sub.3.sup.2? to generate CO.sub.2 gas, or is partially pumped into the CO.sub.2 regeneration device (7) to react with the solution rich in CO.sub.3.sup.2? to generate CO.sub.2 gas and is partially concentrated to obtain concentrated acid solution; a CO.sub.2 regeneration device (7), wherein the acid solution after the CO.sub.2 regeneration is completed flows into the OH receiving chamber (13) of the valence-state ion sieving device (5), or is partially pumped into the OH receiving chamber (13) of the valence-state ion sieving device (5), and is partially pumped into the pH swing regeneration device (6).

2. The energy-saving system for direct air capture with precise ion control of claim 1, wherein the moisture swing adsorbent with high CO.sub.2 capacity in the CO.sub.2 adsorption device (3) comprises at least one of quaternary ammonium-based or quaternary phosphonium-based resin, lignin, activated carbon, molecular sieves, and metal organic frameworks, which has the function of spraying alkaline solution or aqueous solution to release CO.sub.2.

3. The energy-saving system for direct air capture with precise ion control of claim 1, wherein an electrochemical regeneration system thereof comprises a valence-state ion sieving device (5), a pH swing regeneration device (6), and a CO.sub.2 regeneration device (7); the electrochemical regeneration system is able to be used as a central processing unit, a plurality of capture units are coupled with the central processing unit to form a continuous module with precise control system, which is convenient to scale up, wherein the capture units comprise a CO.sub.2 adsorption device (3), an air conveying device (1), and an air distribution device (2).

4. The energy-saving system for direct air capture with precise ion control of claim 1, wherein the principle of the system is to achieve adsorption and release of carbon dioxide by using the pH swing, carbon dioxide (400 ppm) in the air is concentrated to 1% to 5% on the adsorbents at first, and then is concentrated to 95% or more by the electrochemical system in the next step.

5. The energy-saving system for direct air capture with precise ion control according to claim 1, wherein the alkaline solution sprayed by the spraying device (4) comprises at least one of organic amine, sodium hydroxide, potassium hydroxide, phosphate and sulfate, and the content of hydroxide ion ranges from 0.1 mol/L to 3 mol/L.

6. The energy-saving system for direct air capture with precise ion control of claim 1, wherein the energy saving property thereof is that the energy consumption of the valence-state ion sieving device (5) is much less than that of the pH swing regeneration device (6); the valence-state ion sieving device (5) is able to selectively sieve out high-concentration OH from the mixed solution of carbonate and hydroxide, instead of the original way of neutralization with acid solution, and the recycle of alkaline solution and the storage of acid solution are achieved, and therefore the energy-saving effect is achieved.

7. The energy-saving system for direct air capture with precise ion control of claim 1, wherein the concentration of carbonate ion and the concentration of hydroxide ion in the desorption solution flowing out from the CO.sub.2 adsorption device (3) are from 0.1 mol/L to 1 mol/L and from 0.05 mol/L to 2 mol/L, respectively.

8. The energy-saving system for direct air capture with precise ion control of claim 1, wherein in the valence-state ion sieving device (5), structural parameters are designed according to the solution handling capacity, and when the solution handling capacity is 1 liter: the number of the anion membranes (11) is from 1 to 30, and the area of the single anion membrane is from 100 cm.sup.2 to 1,000 cm.sup.2; a basis unit of the valence-state ion sieving device (5) is composed of a cathode plate (8), a partition plate, a cation membrane (10), a partition plate, an anion membrane (11), a partition plate, a cation membrane (10), a partition plate, and an anode plate (9); the cathode plate (8) materials comprise at least one of titanium-ruthenium-iridium electrodes, carbon electrodes, and stainless-steel electrodes; the anode plate (9) materials comprise at least one of ruthenium-iridium coating electrodes, lead plate electrodes, and stainless-steel electrodes; the solution employed by the valence-state ion sieving device (5) comprises at least one of potassium ferricyanide, quinone organic compounds, organic amine, sodium hydroxide, potassium hydroxide, phosphate, and sulfate; the cation membrane (10) is at least one of polytetrafluoroethylene sulfonated acid-based cation exchange membranes and polystyrene sulfonated acid membranes.

9. An energy-saving method for direct air capture with precise ion control, which utilizes the energy-saving system for direct air capture with precise ion control of claim 1; the energy-saving method for direct air capture with precise ion control comprises the following steps: the air enters a CO.sub.2 adsorption device (3) through an air conveying device (1) and an air distribution device (2), and then is discharged after CO.sub.2 is adsorptively separated in the CO.sub.2 adsorption device (3); alkaline solution is sprayed by a spraying device (4) to react with CO.sub.2 adsorbed by moisture swing adsorbents with high CO.sub.2 adsorption capacity for desorption, the obtained desorption solution containing carbonate ions and hydroxide ions enters a valence-state ion sieving device (5), and then enters a CO.sub.2 regeneration device (7) to react with acid solution with pH from 2 to 5 after the hydroxide ions are removed, and the generated CO.sub.2 gas is collected; the reacted acid solution in the CO.sub.2 regeneration device (7) enters the valence-state ion sieving device (5), or is partially pumped into the valence-state ion sieving device (5) and is partially pumped into a pH swing regeneration device (6); the acid solution in the valence-state ion sieving device (5) flows into the pH swing regeneration device (6) after receiving the hydroxide ions, regenerated alkaline solution is pumped into the spraying device (4), and the regenerated acid solution flows into the CO.sub.2 regeneration device (7), or is partially pumped into the CO.sub.2 regeneration device (7) and is partially concentrated to obtain high concentrated acid solution.

10. The energy-saving method for direct air capture with precise ion control of claim 9, wherein in the valence-state ion sieving device (5), one basis unit has an operating voltage from 1.5 V to 5 V, an operating current from 0.1 A to 10 A, and an operating temperature from 5? C. to 70? C.

11. The energy-saving method for direct air capture with precise ion control of claim 9, wherein in the pH swing regeneration device (6), one basis unit has an operating voltage from 3 V to 10 V, an operating current from 0.1 A to 10 A, and an operating temperature from 5? C. to 70? C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG. 1 is a schematic diagram of an energy-saving system for direct air capture with precise ion control in accordance with an embodiment;

[0049] FIG. 2 is a schematic diagram of a valence-state ion sieving device in accordance with an embodiment.

[0050] In the drawings: 1-air conveying device; 2-air distribution device; 3-CO.sub.2 adsorption device; 4-spraying device; 5-valence-state ion sieving device; 6-pH swing regeneration device; 7-CO.sub.2 regeneration device; 8-cathode plate; 9-anode plate; 10-cation membrane; 11-valence ion selective anion membrane, 12-OH removing chamber; 13-OH receiving chamber.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] The present disclosure is further set forth below with reference to accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present disclosure rather than limiting the scope of the present disclosure. In the following embodiments, the operation methods without specific conditions are usually in accordance with the conventional conditions or the conditions suggested by the manufacturer.

[0052] As shown in FIG. 1, an energy-saving system for direct air capture with precise ion control includes:

[0053] an air conveying device 1, an air distribution device 2, and a CO.sub.2 adsorption device 3 internally provided with a moisture swing adsorbent with high CO.sub.2 adsorption capacity, where the air conveying device 1, the air distribution device 2 and the CO.sub.2 adsorption device 3 are connected in sequence, and the CO.sub.2 adsorption device 3 is provided with a spraying device 4;

[0054] a valence-state ion sieving device 5, as shown in FIG. 2, where valence ion selective anion membranes 11 and cation membranes 10 through which OH can pass but CO.sub.3.sup.2? is prevented are alternately arranged, and an anode plate 9 and a cathode plate 8 are arranged on both sides of the valence-state ion sieving device 5 to form a constant electric field. In the valence-state ion sieving device 5, an OH removing chamber 12 receives desorption solution flowing out from the CO.sub.2 adsorption device 3, and the aqueous solution rich in CO.sub.3.sup.2? flowing out from an outlet of the OH-removing chamber 12 is pumped into a CO.sub.2 regeneration device 7, and an outlet of the OH-receiving chamber 13 is connected with a pH swing regeneration device 6;

[0055] a pH swing regeneration device 6, which employs a pH swing regeneration system and is configured to produce acid solution and to concentrate alkaline solution, where the concentrated alkaline solution outlet is connected to the spraying device 4, the produced acid solution flows into the CO.sub.2 regeneration device 7 to react with the aqueous solution rich in CO.sub.3.sup.2? to generate CO.sub.2 gas, or is partially pumped into the CO.sub.2 regeneration device 7 to react with the aqueous solution rich in CO.sub.3.sup.2? to generate CO.sub.2 gas and is partially concentrated to obtain concentrated acid solution; and

[0056] a CO.sub.2 regeneration device 7, where the acid solution after the CO.sub.2 regeneration is completed flows into the OH receiving chamber 13 of the valence-state ion sieving device 5, or is partially pumped into the OH receiving chamber 13 of the valence-state ion sieving device 5, and is partially pumped into the pH swing regeneration device 6.

[0057] Specifically,

[0058] CO.sub.2 adsorbent in the CO.sub.2 adsorption device 3 includes at least one of quaternary ammonium-based or quaternary phosphonium-based resin, lignin, activated carbon, molecular sieve, and metal organic framework, and the saturated adsorption capacity is from 0.1 mmol/g to 1.2 mmol/g.

[0059] The content of hydroxide ions in the alkali solution sprayed by the spraying device 4 is from 0.1 mol/L to 3 mol/L, which is in the form of sodium hydroxide solution.

[0060] The concentration of carbonate ion and the concentration of hydroxide ion in the desorption solution flowing out from the CO.sub.2 adsorption device 3 are from 0.1 mol/L to 1 mol/L and from 0.05 mol/L to 2 mol/L, respectively.

[0061] In the valence-state ion sieving device 5:

[0062] The number of the valence ion selective anion membranes 11 is from 2 to 20, and the area of the membrane is from 100 cm.sup.2 to 1,000 cm.sup.2.

[0063] The cathode plate 8 material includes at least one of titanium-ruthenium-iridium electrodes, carbon electrodes, and stainless-steel electrodes.

[0064] The anode plate 9 material includes at least one of ruthenium-iridium coating electrodes, lead plate electrodes, and stainless-steel electrodes.

[0065] The cation membrane 10 is at least one of a polytetrafluoroethylene sulfonated acid-based cation exchange membrane and a polystyrene sulfonated acid membrane.

[0066] In the valence-state ion sieving device 5, under the action of electric field force, the hydroxide ions may be migrated to a dilute solution side by passing through the valence ion selective anion membranes at a faster speed, and based on the electrostatic repulsion of selective ionic membranes to the carbonate and the strong selectivity of pore size sieving, most of carbonate remains on a concentrated solution side, thus achieving the sieving of two types of ions.

[0067] An energy-saving method for direct air capture with precise ion control conducted by utilizing the energy-saving system for direct air capture with precise ion control includes the following steps:

[0068] The air enters a CO.sub.2 adsorption device 3 through an air conveying device 1 and an air distribution device 2, and then is discharged after CO.sub.2 is adsorptively separated in the CO.sub.2 adsorption device 3.

[0069] Alkaline solution is sprayed by a spraying device 4 to react with CO.sub.2 adsorbed by a moisture swing adsorbent with high CO.sub.2 adsorption capacity for desorption, the obtained desorption solution containing carbonate ions and hydroxide ions flows into a valence-state ion sieving device 5, and then flows into a CO.sub.2 regeneration device 7 to react with acid solution with pH from 2 to 5 after the hydroxide ions are removed, and the generated CO.sub.2 gas is collected.

[0070] The reacted acid solution in the CO.sub.2 regeneration device 7 enters the valence-state ion sieving device 5, or is partially pumped into the valence-state ion sieving device 5 and is partially pumped into a pH regeneration device 6.

[0071] The acid solution entering the valence-state ion sieving device 5 flows into the pH swing regeneration device 6 after receiving the hydroxide ions, regenerated alkaline solution flows into the spraying device 4, and regenerated acid solution flows into the CO.sub.2 regeneration device 7, or is partially pumped into the CO.sub.2 regeneration device 7 and is partially concentrated to obtain concentrated acid solution.

[0072] Specifically, the valence-state ion sieving device 5 includes ten basis units, one basis unit has an operating voltage from 1.5 V to 5 V, an operating current from 0.1 A to 10 A, and an operating temperature from 5? C. to 70? C.

[0073] The pH swing regeneration device 6 includes ten basis units, one basis unit has an operating voltage from 3 V to 10 V, an operating current from 0.1 A to 10 A, and an operating temperature from 5? C. to 70? C.

[0074] The purity of the CO.sub.2 gas generated by the CO.sub.2 regeneration device 7 is greater than 95%, and the CO.sub.2 gas can be compressed into products for commercial application.

[0075] The valence-state ion sieving device 5 in the present disclosure may separate the carbonate ions from hydroxide ions, control the content of hydroxide in the aqueous solution rich in CO.sub.3.sup.2?, and reduce the energy consumption of the system. In the CO.sub.2 adsorption device 3, carbon dioxide adsorption materials are used to increase the concentration of carbon dioxide in the air to the same level as that of flue gas, and then the concentration of carbon dioxide is increased to 95% or more by spraying the alkaline solution. The present disclosure is simple and feasible in process flow, small in entire equipment volume, capable of precisely controlling the concentration of aqueous solution rich in CO.sub.3.sup.2? and the concentration of barren solution, thus improving the system performance, reducing the energy consumption and facilitating the commercial popularization of the technology of direct air capture of CO.sub.2.

[0076] In addition, it should be understood that those of ordinary skill in the art may make various changes or modifications to the present disclosure after reading the content described above in the present disclosure, and these equivalent forms also fall within the scope defined by the appended claims.