Carbon dioxide capture and purification method and system

Abstract

A method and system for capturing and purifying carbon dioxide are provided. The method for capturing and purifying carbon dioxide includes the steps of: performing a carbon dioxide capturing process on a target component using an alkaline solution to obtain a carbonate-containing aqueous solution; mixing at least a part of the carbonate-containing aqueous solution with the carbon dioxide-containing crude oxygen generated in the carbon dioxide separation process to obtain a bicarbonate-containing aqueous solution and oxygen gas, the volume content of carbon dioxide in the carbon dioxide-containing crude oxygen being 9.7-35.9 vol%; electrolyzing the bicarbonate-containing aqueous solution to obtain anode gas, hydrogen gas and a regenerated alkaline solution; and performing a carbon dioxide separation process on the anode gas to obtain liquid carbon dioxide and carbon dioxide-containing crude oxygen. The carbon dioxide content in the liquid carbon dioxide is 98.5-99.9999 vol%, and the carbon dioxide content in the crude oxygen accounts for 5-40% of the carbon dioxide content in the anode gas. The method effectively reduces electrolysis energy consumption and reduces the amount of liquid CO 2 It is possible to provide a purity of

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is based on and claims priority from a Chinese application having Chinese application number 202210577489.3 and filed on May 25, 2022, the disclosure of which is incorporated herein in its entirety. The present invention relates to the field of carbon dioxide capture technology, and in particular to a method and system for carbon dioxide capture and purification. [Background technology]

[0002] CO 2 As a major greenhouse gas, CO emissions are increasing and the issue of global warming is drawing attention. 2 The capture technology is CO 2 Reduce emissions and atmospheric CO 2 It can effectively reduce CO 2 The development of collection techniques has also become a focus of people's research.

[0003] Currently, various carbon capture technologies are emerging one after another both at home and abroad. For example, Carbon Engineering (CE) is developing a carbon capture technology using KOH and Ca(OH). 2 We developed a direct air capture process using KOH as the main absorption solution. 2 Absorbs KOH solution and turns it into KOH. 2 CO 3 solution and then Ca(OH) 2 The KOH is regenerated using a solution. During the regeneration process, Ca(OH) 2 CaCO from solution 3 A solid is generated, CaCO 3 The solid was calcined at high temperature to obtain CaO, and then the CaO was again 2 React with O to form Ca(OH) 2In the above process, inorganic alkali with stable properties is used as the absorbent, and the operation is stable and can be operated continuously, making it possible to apply it on a large scale. However, the entire process is long, and the CaCO 3 In the solid calcination process, there is a problem of high energy consumption in the regeneration process as well as secondary carbon emissions.

[0004] By electrolyzing the carbonate solution in an electrolysis process, the alkaline solution can be regenerated and the captured CO 2 can be electrowinning from carbonate solutions, Ca(OH) 2 Regeneration of alkaline solution with CaCO 3 However, the carbonate solution added to the electrolytic cell contains unreacted hydroxide ions (OH - When the electrolyte contains hydroxide ions, they are discharged first during the electrolysis process, and OH - Carbonate ions are electrolyzed only after the carbon dioxide is completely consumed. 2 Electrolysis is carried out in two steps: 3 2- to hydrogen carbonate ion HCO 3 - and then HCO 3 - CO 2 The electrolysis is completed by electrolyzing the carbonate solution added to the electrolytic cell. - and a prescribed amount of HCO 3 - When CO is included, the power consumption of the electrolyzer during the electrolysis process can be reduced to some extent. 2 When collecting CO using an alkaline solution, 2 When collecting air with low concentration, high OH - The concentration is CO 2 This guarantees a high CO capture rate. 2 To obtain a desired capture efficiency, the carbonate solution after absorption is usually added with a certain amount of OH. - , which increases the power consumption of the electrolyzer.

[0005] In theory, gaseous CO generated by electrolysis 2 Approximately 30% of O 2 is mixed in, and conventional CO 2 Using a separation tower 2 and CO 2 By separating the CO2 from the gas, a highly pure liquid CO2 can be obtained. 2 When obtaining the product, O discharged from the top of the column 2 Large amounts of CO 2 was brought out, CO 2 The recovery rate cannot be guaranteed and the capture rate of the entire system decreases.

[0006] Therefore, the research and development of carbon dioxide capture and purification methods and systems is of great significance in simultaneously achieving high carbon dioxide capture efficiency and low energy consumption. Summary of the Invention [Problem to be solved by the invention]

[0007] The main objective of the present invention is to provide a method and system for carbon dioxide capture and purification to solve the problems of low carbon dioxide capture efficiency and high energy consumption in conventional carbon dioxide capture and purification processes. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a method for capturing and purifying carbon dioxide, which includes capturing carbon dioxide, electrolysis, and carbon dioxide separation, and includes the steps of: performing a carbon dioxide capturing process on a target component using an alkaline solution to obtain a carbonate-containing aqueous solution; mixing at least a part of the carbonate-containing aqueous solution with the carbon dioxide-containing crude oxygen generated in the carbon dioxide separation process to obtain a bicarbonate-containing aqueous solution and oxygen gas, the volume content of carbon dioxide in the carbon dioxide-containing crude oxygen being 9.7-35.9 vol%; electrolyzing the bicarbonate-containing aqueous solution to obtain anode gas, hydrogen gas, and a regenerated alkaline solution; and performing a carbon dioxide separation process on the anode gas to obtain liquid carbon dioxide and carbon dioxide-containing crude oxygen, the carbon dioxide content in the liquid carbon dioxide being 98.5-99.9999 vol% and the carbon dioxide content in the crude oxygen being 5-40% of the carbon dioxide content in the anode gas.

[0009] Furthermore, the carbon dioxide separation process is carried out in a carbon dioxide separation device, the operating pressure is 10-60 bar, the molar reflux ratio is (1.4-4):1, and the mass ratio of the overhead gas phase extraction to the raw material is (0.25-0.45):1.

[0010] Furthermore, the temperature during the electrolysis is 50-200°C, the electrolytic cell voltage is 1.1-4V, and the current density is 500-8000A / m 2 In the bicarbonate-containing aqueous solution, the ratio of the amount of bicarbonate ions to the total amount of carbonate ions and bicarbonate ions is (0.1-1:1).

[0011] Furthermore, prior to the carbon dioxide separation process, the method for capturing and purifying carbon dioxide further includes the steps of sequentially subjecting the anode gas to cooling, gas-liquid separation, compression and drying dehydration.

[0012] Furthermore, after undergoing a cooling process, the temperature of the anode gas drops to 5-50°C.

[0013] Furthermore, between the compression step and the separation step, the carbon dioxide capture and purification method includes a step of exchanging heat between the anode gas that has been subjected to the compression step and the crude oxygen.

[0014] Furthermore, the hydroxide ion concentration in the alkaline solution is 0.2-3 mol / L, the carbonate ion concentration in the carbonate-containing aqueous solution is 0.2-6 mol / L, the hydroxide ion concentration is 0-1.5 mol / L, and the carbonate-containing aqueous solution has a pH of 10-14. Preferably, the hydroxide ion concentration in the alkaline solution is 0.5-1.5 mol / L, the carbonate ion concentration in the carbonate-containing aqueous solution is 0.5-5.5 mol / L, the hydroxide ion concentration is 0-1 mol / L, and the carbonate-containing aqueous solution has a pH of 12-14.

[0015] Additionally, the method for carbon dioxide capture and purification further includes the step of recycling at least a portion of the carbonate-containing aqueous solution and / or the regenerated alkaline solution back into the carbon dioxide capture process.

[0016] In order to achieve the above object, another aspect of the present invention provides a system for capturing and purifying carbon dioxide. The system for capturing and purifying carbon dioxide includes a carbon dioxide capture device, an oxygen gas purification device, an electrolysis unit, a carbon dioxide separation device, a carbon dioxide detection device, and a valve. The carbon dioxide capture device is provided with an alkaline solution inlet, a target component inlet, and a carbonate-containing aqueous solution outlet. The oxygen gas purification device is provided with a crude oxygen inlet, a carbonate-containing aqueous solution inlet, a bicarbonate-containing aqueous solution outlet, and an oxygen gas outlet, and the carbonate-containing aqueous solution inlet and the carbonate-containing aqueous solution outlet are connected to each other. The electrolysis unit is provided with a bicarbonate-containing aqueous solution inlet, an anode gas outlet, a hydrogen gas outlet, and a regenerated alkaline liquid outlet, and the bicarbonate-containing aqueous solution inlet and the bicarbonate-containing aqueous solution outlet are connected to each other through an aqueous bicarbonate solution transport pipe. The carbon dioxide separation device is provided with an anode gas inlet, a liquid carbon dioxide outlet, and a crude oxygen outlet, the anode gas inlet and the anode gas outlet are connected to each other through an anode gas transport pipe, and the crude oxygen outlet and the crude oxygen inlet are connected to each other through a crude oxygen transport pipe. The carbon dioxide detector is used to measure the carbon dioxide content in the crude oxygen delivery line. The valve is installed in the crude oxygen delivery line and is located downstream of the carbon dioxide detector, and the valve is connected to the carbon dioxide detector, and opens when the carbon dioxide content reaches a predetermined value.

[0017] Furthermore, the carbon dioxide capture device is further provided with a reflux port which is in communication with the regenerated alkaline solution outlet and the carbonate-containing aqueous solution outlet, respectively.

[0018] Furthermore, the reflux port and the regenerated alkaline liquid outlet are connected by a regenerated alkaline liquid transport pipeline, and the carbon dioxide capture and purification system further includes a buffer tank and a first cooling device which are sequentially installed in the regenerated alkaline liquid transport pipeline along the material flow direction.

[0019] Furthermore, the buffer tank is provided with an external water supply inlet for adjusting the concentration of the regenerated alkaline solution in the buffer tank.

[0020] Furthermore, the carbon dioxide capture and purification system further includes a second cooling device, a gas-liquid separation device, a compression device and a drying and dehydrating device, which are sequentially installed in the anode gas transport pipeline along the material flow direction in the anode gas transport pipeline.

[0021] Furthermore, the carbon dioxide capture and purification system further includes a heat exchanger, which is installed in the anode gas transport pipeline between the compression device and the carbon dioxide separation device and is configured to exchange heat between the anode gas and the crude oxygen.

[0022] Furthermore, the carbon dioxide capture and purification system further includes a column bottom liquid flow rate regulator installed in the aqueous bicarbonate solution transport pipeline.

[0023] Furthermore, the compression device is a 2- to 8-stage compressor, and a third cooling device and a liquid separating device are installed between each stage of the compressor.

[0024] In addition, a condenser and a reboiler are further installed inside the carbon dioxide separation device to adjust the carbon dioxide content in the crude oxygen transport pipeline. Effect of the Invention

[0025] The technical solution of the present application is applied to convert the carbon dioxide in the target component into a carbonate-containing aqueous solution through a carbon dioxide capture process. The carbonate-containing aqueous solution is used to absorb the carbon dioxide in the crude oxygen and convert it into bicarbonate ions, and then the electrolysis process is carried out. Compared with the process of electrolysis using carbonate as an electrolyte, the present application can effectively reduce the energy consumption of the electrolysis process by using a bicarbonate-containing aqueous solution as the electrolyte. In the carbon dioxide separation process, the proportion of the carbon dioxide content in the obtained crude oxygen product to the carbon dioxide content in the anode gas, and the dry basis contents of oxygen and carbon dioxide in the crude oxygen gas are limited within a certain range, and the carbonate-containing aqueous solution obtained in the carbon dioxide capture process is used to absorb the carbon dioxide in the obtained crude oxygen product. As a result, the process can obtain high-purity liquid carbon dioxide and maintain a high carbon dioxide recovery rate, reduce the process cost of the carbon dioxide capture and purification process, and further improve the overall economic effect. [Brief description of the drawings]

[0026] The drawings forming a part of this application are intended to provide a further understanding of the present invention, and the schematic embodiments of the present invention and the description thereof are intended to interpret the present invention and are not intended to be undue limitations on the present invention. [Figure 1] FIG. 1 is a schematic diagram showing the structure of a carbon dioxide capture and purification system in Example 1 of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] It should be noted that, where not inconsistent, the embodiments and features in the embodiments in the present application may be combined with each other.

[0028] As explained in the Background Art, in order to improve the yield of liquid carbon dioxide in conventional carbon dioxide capture and utilization processes, the ratio of liquid carbon dioxide in the anode gas in the carbon dioxide separation process is usually increased as much as possible, but this results in ineffective utilization of the large amount of carbon dioxide contained in the crude oxygen obtained after separation, resulting in a low carbon dioxide capture and utilization rate and high energy consumption throughout the process. To solve the above problems, the present application provides a method for carbon dioxide capture and purification, which includes carbon dioxide capture, electrolysis, and carbon dioxide separation. The method for capturing and purifying carbon dioxide includes the steps of: performing a carbon dioxide capturing process on a target component using an alkaline solution to obtain a carbonate-containing aqueous solution; mixing at least a portion of the carbonate-containing aqueous solution with carbon dioxide-containing crude oxygen generated in the carbon dioxide separation process to obtain a bicarbonate-containing aqueous solution and oxygen gas, wherein the volumetric carbon dioxide content in the carbon dioxide-containing crude oxygen is 9.7-35.9 vol%; electrolyzing the bicarbonate-containing aqueous solution to obtain anode gas, hydrogen gas and a regenerated alkaline solution; and performing a carbon dioxide separation process on the anode gas to obtain liquid carbon dioxide and carbon dioxide-containing crude oxygen, wherein the carbon dioxide content in the liquid carbon dioxide is 98.5-99.9999 vol% and the carbon dioxide content in the crude oxygen accounts for 5-40% of the carbon dioxide content in the anode gas.

[0029] The carbon dioxide in the target component is converted into a carbonate-containing aqueous solution through the carbon dioxide capture process. The carbonate-containing aqueous solution absorbs the carbon dioxide in the crude oxygen and converts it into bicarbonate ions, and then the electrolysis process is carried out. Compared with the process of electrolysis using carbonate as an electrolyte, the present application uses a bicarbonate-containing aqueous solution as an electrolyte, which can effectively reduce the energy consumption of the electrolysis process.

[0030] In the carbon dioxide separation process, the proportion of the carbon dioxide content in the obtained crude oxygen product to the carbon dioxide content in the anode gas, and the contents of oxygen gas and carbon dioxide in the crude oxygen gas are limited to specific ranges. Furthermore, the carbonate-containing aqueous solution obtained in the carbon dioxide capture process is used to absorb the carbon dioxide in the obtained crude oxygen product to obtain a hydrogencarbonate-containing aqueous solution (CO 3 2- +CO 2 +H 2 O→HCO 3 - ), this process can obtain high-purity liquid carbon dioxide and maintain a high carbon dioxide recovery rate. It also reduces the process costs of the carbon dioxide capture and purification process, improving the overall economic efficiency.

[0031] In a preferred embodiment, the carbon dioxide separation process is carried out in a carbon dioxide separation apparatus, with an operating pressure of 10-60 bar, a molar reflux ratio of (1.4-4):1, and a ratio of the amount of substance between the overhead gas phase harvest and the raw material of (0.25-0.45):1. The operating pressure, molar reflux ratio, and the ratio of the amount of substance between the overhead gas phase harvest and the raw material include, but are not limited to, the above ranges. By limiting these to the above ranges, the separation efficiency of carbon dioxide and oxygen can be further improved, and the recovery rate of carbon dioxide in the entire process can be improved, thereby improving the economic effect.

[0032] In the electrolysis process, the anode reaction is when the carbonate ions in the bicarbonate solution are discharged to produce crude oxygen containing carbon dioxide, and the cathode reaction is when the water molecules gain electrons to produce hydrogen. The reaction formula is HCO 3 - →CO 2 ↑+O 2 ↑+H + (Anode), H 2 O→H 2 ↑+OH - The hydroxide ions generated at the cathode constitute the regenerated alkaline solution together with the metal cations in the system.

[0033] In a preferred embodiment, the temperature during the electrolysis is 50 to 200° C., the electrolytic cell voltage is 1.1 to 4 V, and the current density is 500 to 8000 A / m 2 In the bicarbonate-containing aqueous solution, the ratio of the amount of substance of bicarbonate ions to the total amount of substance of carbonate ions and bicarbonate ions is (0.1-1):1. The temperature, electrolytic cell voltage, and current density in the electrolysis process include, but are not limited to, the above-mentioned ranges. Limiting these to within the above-mentioned ranges is advantageous for improving the electrochemical reaction rate and current efficiency, and is also advantageous for reducing the energy consumption of the electrolytic cell and reducing the process cost of the carbon dioxide capture and purification process.

[0034] In a preferred embodiment, the method for capturing and purifying carbon dioxide further includes sequentially subjecting the anode gas to cooling, gas-liquid separation, compression and drying / dehydration prior to the carbon dioxide separation process. The sequential application of the above treatment methods to the anode gas is advantageous in providing a good precondition for the subsequent carbon dioxide separation process, which is conducive to the performance of the carbon dioxide separation process and further improves the efficiency of carbon dioxide separation.

[0035] In a preferred embodiment, after the cooling process, the temperature of the anode gas is reduced to 5-50°C. The temperature of the anode gas includes, but is not limited to, the above range. Limiting the temperature to the above range is advantageous for improving the separation effect between the anode gas and water vapor in the subsequent gas-liquid separation process, and further improving the subsequent carbon dioxide separation efficiency and the purity of the liquid carbon dioxide product.

[0036] In a preferred embodiment, a mixed gas containing oxygen, carbon dioxide and water vapor and condensed water are obtained through a gas-liquid separation process, in which the molar content of oxygen in the mixed gas is 15 to 45% on a dry basis.

[0037] In a preferred embodiment, the method for capturing and purifying carbon dioxide includes a step of exchanging heat between the anode gas that has been compressed and the crude oxygen between the compression step and the separation step. The heat exchange method is advantageous in lowering the temperature of the anode gas, and can heat the crude oxygen gas to improve the absorption rate of carbon dioxide in the purification step.

[0038] In a preferred embodiment, the concentration of hydroxide ions in the alkaline solution is 0.2-3 mol / L, the concentration of carbonate ions in the carbonate-containing aqueous solution is 0.2-6 mol / L, the concentration of hydroxide ions is 0-1.5 mol / L, and the pH of the carbonate-containing aqueous solution is 10-14. Limiting the concentration of hydroxide ions in the alkaline solution to the above ranges is advantageous for improving the efficiency of carbon dioxide gas collection by the alkaline solution, as compared with other ranges. Furthermore, limiting the concentrations of carbonate ions and hydroxide ions and the pH in the carbonate-containing aqueous solution to the above ranges is advantageous for improving the content of hydrogen carbonate ions in the hydrogen carbonate-containing solution obtained in the purification process, as compared with other ranges, which is advantageous for providing a more sufficient electrolyte supply source for the electrolysis process and is also advantageous for reducing energy consumption.

[0039] Preferably, the hydroxide ion concentration in the alkaline solution is 0.5-1.5 mol / L, the carbonate ion concentration in the carbonate-containing aqueous solution is 0.5-5.5 mol / L, the hydroxide concentration is 0-1 mol / L, and the pH of the carbonate-containing aqueous solution is 12-14. Limiting the hydroxide ion concentration in the alkaline solution to the above range is advantageous for further improving the efficiency of carbon dioxide gas capture by the alkaline solution compared to other ranges. Also, limiting the concentrations of carbonate ions and hydroxide ions in the carbonate-containing aqueous solution, the ratio of the substance amount of bicarbonate ions to the total substance amount of carbonate ions and bicarbonate ions, and the pH to the above ranges is advantageous for further improving the carbon dioxide capture rate by the alkaline solution, and is also advantageous for further improving the content of bicarbonate ions in the bicarbonate-containing solution obtained in the purification process, which is advantageous for providing a more sufficient supply source of electrolyte for the electrolysis process and is advantageous for further reducing energy consumption.

[0040] In a preferred embodiment, the method for capturing and purifying carbon dioxide further includes a step of returning at least a portion of the carbonate-containing aqueous solution and / or the regenerated alkaline solution to the carbon dioxide capture process for reuse. The above-mentioned reuse method is advantageous for improving the capture rate of the target component in the carbon dioxide capture process, and is also advantageous for improving the production rate of the carbonate-containing aqueous solution obtained after capture, as well as for further reducing process costs.

[0041] A second aspect of the present application further provides a system for carbon dioxide capture and purification. The system for carbon dioxide capture and purification includes a carbon dioxide capture device 100, an oxygen gas purification device 200, an electrolysis unit 300, a carbon dioxide separation device 400, a carbon dioxide detection device 500, and a valve 600. The carbon dioxide capture device 100 is provided with an alkaline solution inlet 101, a target component inlet 102, and a carbonate-containing aqueous solution outlet 103. The oxygen gas purification device 200 is provided with a crude oxygen inlet 201, a carbonate-containing aqueous solution inlet 202, a bicarbonate-containing aqueous solution outlet 203, and an oxygen gas outlet 204, and the carbonate-containing aqueous solution inlet 202 and the carbonate-containing aqueous solution outlet 103 are provided in communication with each other. The electrolysis unit 300 is provided with a bicarbonate-containing aqueous solution inlet 301, an anode gas outlet 302, a hydrogen gas outlet 303 and a regenerated alkaline solution outlet 304, and the bicarbonate-containing aqueous solution inlet 301 and the bicarbonate-containing aqueous solution outlet 203 are connected by a bicarbonate aqueous solution transport pipeline. The carbon dioxide separation device 400 is provided with an anode gas inlet 401, a liquid carbon dioxide outlet 402 and a crude oxygen outlet 403, and the anode gas inlet 401 and the anode gas outlet 302 are connected by an anode gas transport pipeline, and the crude oxygen outlet 403 and the crude oxygen inlet 201 are connected by a crude oxygen transport pipeline. The carbon dioxide detection device 500 is used to measure the carbon dioxide content in the crude oxygen transport pipeline. The valve 600 is installed in the crude oxygen transport pipeline and is located downstream of the carbon dioxide detection device 500, and the valve 600 is installed in conjunction with the carbon dioxide detection device 500, and when the carbon dioxide content reaches a predetermined value, the valve 600 is opened.

[0042] The alkaline solution can capture carbon dioxide in the target component to obtain a carbonate-containing aqueous solution, and the generated carbonate-containing aqueous solution is discharged from a carbonate-containing aqueous solution outlet 103. A crude oxygen inlet 201 is provided in the oxygen purification device 200, and the carbon dioxide-containing crude oxygen enters the oxygen gas purification device 200 from the crude oxygen inlet 201 to obtain oxygen gas, and the obtained oxygen gas is discharged from an oxygen gas outlet 204. In addition, the carbon dioxide-containing crude oxygen reacts with a part of the carbonate-containing aqueous solution to generate a bicarbonate-containing aqueous solution, and the bicarbonate-containing aqueous solution is discharged from a bicarbonate-containing aqueous solution outlet 203. The discharged bicarbonate-containing aqueous solution is fed to the electrolysis unit 300 through the aqueous bicarbonate solution transport pipeline and participates in the electrolysis process as an electrolyte; the anode gas obtained by electrolysis is discharged from the anode gas outlet 302 and fed to the anode gas inlet 401 through the anode gas transport pipeline; the hydrogen gas obtained by electrolysis is discharged through the hydrogen gas outlet 303; and the regenerated alkaline solution obtained by electrolysis is discharged through the regenerated alkaline solution outlet 304. A carbon dioxide detection device 500 is further installed in the system to detect the carbon dioxide content in the crude oxygen product. By installing the valve 600 at the specific position, it is possible to control that when the carbon dioxide content reaches a predetermined value, the valve 600 opens and the crude oxygen enters the oxygen purification device 200 where the crude oxygen inlet 403 is installed.

[0043] The carbon dioxide capture device 100 can convert the carbon dioxide in the target component into a carbonate-containing aqueous solution. The oxygen purification device 200 is used to absorb the carbon dioxide in the crude oxygen into a carbonate-containing aqueous solution to convert it into bicarbonate ions, and then the electrolysis process is performed using the electrolysis unit 300. Compared to performing the electrolysis process using carbonate as an electrolyte, the electrolysis unit 300 of the present application performs the electrolysis process using an aqueous solution containing bicarbonate as an electrolyte, thereby effectively reducing energy consumption in the electrolysis process.

[0044] By installing the carbon dioxide detector 500 and the valve 600, the carbon dioxide content in the obtained crude oxygen product is limited to a predetermined value, and the carbon dioxide in the crude oxygen product is absorbed by the carbonate-containing aqueous solution obtained in the carbon dioxide capture process to produce a hydrogen carbonate-containing aqueous solution (CO 3 2- +CO 2 +H 2 O→HCO 3 - As a result, this process can obtain high-purity liquid carbon dioxide while maintaining a high carbon dioxide recovery rate, and can also reduce the cost of the carbon dioxide capture and purification system, improving its overall economic effectiveness.

[0045] In a preferred embodiment, the carbon dioxide capture device 100 is further provided with a reflux port 104, which is provided in communication with the regenerated alkaline liquid outlet 304 and the carbonate-containing aqueous solution outlet 100. The use of the reflux port 104 is advantageous for improving the absorption rate of the target component in the carbon dioxide capture process, and is also advantageous for improving the production rate of the carbonate-containing aqueous solution obtained after capture, and is also advantageous for further reducing process costs.

[0046] In a preferred embodiment, the reflux port 104 and the regenerated alkaline solution outlet 304 are connected by a regenerated alkaline solution transport pipeline, and the carbon dioxide capture and purification system further includes a buffer tank 310 and a first cooling device 320, which are sequentially installed in the regenerated alkaline solution transport pipeline along the material flow direction. The installation of the buffer tank 310 and the first cooling device 320 is advantageous for controlling the pH change and temperature change of the alkaline solution to be maintained within a small fluctuation range, and for preventing the physicochemical properties of the alkaline solution from fluctuating too much due to the reflux of the regenerated alkaline solution, which is advantageous for improving the absorption rate of the alkaline solution for carbon dioxide gas in the air, and for improving the production rate of carbonate in the carbonate-containing aqueous solution.

[0047] In order to further prevent the physicochemical properties of the alkaline solution from fluctuating too much due to the reflux of the regenerated alkaline solution, and to further improve the absorption rate of the alkaline solution for carbon dioxide gas in the air, in a preferred embodiment, the buffer tank 310 is provided with an external water supply inlet 311 for adjusting the concentration of the regenerated alkaline solution in the buffer tank.

[0048] In a preferred embodiment, the carbon dioxide capture and purification system further includes a second cooling device 330, a gas-liquid separation device 340, a compression device 350, and a drying and dehydrating device 360, which are sequentially installed in the anode gas transport pipeline along the material flow direction in the anode gas transport pipeline. The second cooling device 330 can be used for cooling the anode gas, the gas-liquid separation device 340 can be used for gas-liquid separation of the anode gas, the compression device 350 can be used to reduce the volume of the anode gas, and the drying and dehydrating device 360 ​​can be used to dry the anode gas. The sequential use of the above treatments for the anode gas is advantageous in providing a good precondition for the subsequent carbon dioxide separation process, which makes the carbon dioxide separation process easier to carry out and improves the carbon dioxide separation efficiency.

[0049] In a preferred embodiment, the carbon dioxide capture and purification system further includes a heat exchanger, which is installed in the anode gas transport pipeline between the compression device 350 and the carbon dioxide separation device 400, and exchanges heat between the anode gas and the crude oxygen. Exchanging heat between the anode gas and the crude oxygen through the heat exchanger is advantageous for lowering the anode gas temperature, and can also heat the crude oxygen gas to improve the absorption rate of carbon dioxide in the purification process.

[0050] In a preferred embodiment, the carbon dioxide capture and purification system further includes a bottoms flow rate regulator 210, which is installed in the aqueous bicarbonate solution transport pipeline. The installation of the bottoms flow rate regulator 210 is advantageous for regulating and controlling the flow rate of the aqueous bicarbonate solution within an appropriate range, and therefore makes it easy to control the progress of the electrolysis process in the electrolysis unit 300.

[0051] The multi-stage compressor can increase the pressure of the anode gas in stages, and compared with a single-stage compressor, the multi-stage compressor generates higher air power and has higher compression efficiency, making it suitable for larger-scale operation and continuous application. In a preferred embodiment, the compressor 350 is a 2-8 stage compressor, and a third cooling device and a liquid separator are installed between each stage of the compressor. The number of stages of the compressor 350 includes, but is not limited to, the above range. Limiting the number of stages within the above range is advantageous for increasing the anode gas pressure while reducing energy consumption. In addition, installing a third cooling device between each stage of the compressor is advantageous for liquefying the compressed anode gas to generate more liquid carbon dioxide, and using a liquid separator is advantageous for separating more of the liquefied liquid carbon dioxide.

[0052] In a preferred embodiment, a condenser and a reboiler are further installed inside the carbon dioxide separation device 400 to adjust the carbon dioxide content in the crude oxygen transport line.

[0053] Hereinafter, the present application will be described in more detail with reference to specific examples, which should not be understood as limitations on the scope of protection claimed by the present application.

[0054] In this application, the unit is kWh / kgCO 2 In the electrolysis process, 1 kg of CO is electrolyzed in an electrolytic cell. 2 It represents the amount of electrical energy (kWh) consumed to generate the carbon dioxide. The carbon dioxide capture rate refers to the weight percentage of the liquid carbon dioxide obtained in the carbon dioxide separation process out of the total weight of carbon dioxide captured in the carbon dioxide capture process.

[0055] [Example 1] In this embodiment, the target component is air, the alkaline solution is potassium hydroxide solution, and the concentration of hydroxide ions in the alkaline solution is 1 mol / L.

[0056] Methods for carbon dioxide capture and purification include the following: In the carbon dioxide capture device 100, the carbon dioxide in the air is captured with a KOH solution (i.e., a carbon dioxide capture process is performed) to obtain a carbonate-containing aqueous solution. Here, an alkaline solution is fed into the carbon dioxide capture device 100 via an alkaline solution inlet 101, and air is fed into the carbon dioxide capture device 100 at a target component 102. The resulting carbonate-containing aqueous solution has a carbonate ion concentration of 4.2 mol / L, a hydroxide ion concentration of 0.8 mol / L, and a pH of 13.8. A portion of the carbonate-containing aqueous solution is mixed with the crude oxygen generated in the carbon dioxide separation process to obtain a bicarbonate-containing aqueous solution and oxygen. In the bicarbonate-containing aqueous solution, the ratio of the amount of bicarbonate ions to the total amount of carbonate ions and bicarbonate ions is 0.2:1. The volume content of carbon dioxide in the carbon dioxide-containing crude oxygen is 26.8 vol%, and the carbon dioxide content in the crude oxygen is measured by a carbon dioxide detection device 500. The hydrogen carbonate-containing aqueous solution obtained above is fed to the electrolysis unit 300 through a hydrogen carbonate aqueous solution transport pipeline, and the flow rate of the hydrogen carbonate-containing aqueous solution is adjusted by a tower bottom liquid flow rate adjustment device 210. In the electrolysis unit 300, the hydrogen carbonate-containing aqueous solution obtained above is electrolyzed. The temperature in the electrolysis process is 60° C., the electrolytic cell voltage is 4 V, and the current density is 8000 A / m 2 After electrolysis, anode gas, hydrogen gas and regenerated alkaline solution are obtained. The regenerated alkaline solution is returned to the carbon dioxide capture process for reuse, and the regenerated alkaline solution passes through a regenerated alkaline solution transport pipeline, sequentially through a buffer tank 310 and a first cooling device 320, and at the same time, water is fed from an external water supply inlet 311 to the buffer tank 310, and the hydroxide concentration in the alkaline solution is controlled to be maintained at 1 mol / L. The anode gas is cooled in the second cooling device 350 to lower the temperature of the anode gas to 20°C, and then the cooled anode gas is subjected to gas-liquid separation processing using the gas-liquid separator 340 to obtain a mixed gas containing oxygen gas, carbon dioxide and water vapor, and condensed water. The dry molar content of oxygen gas in the mixed gas was detected to be 32.4 vol%. The compression process is performed in the compression device 350, and the compression process is performed using a four-stage compressor, with a third cooling device and a liquid separator installed between each stage of the compressor, and the treated anode gas is obtained after being treated in the drying and dehydrating device 360. The treated anode gas is introduced into the carbon dioxide separation unit 400 to perform a carbon dioxide separation process to obtain liquid carbon dioxide and carbon dioxide-containing crude oxygen. Here, the operating pressure is 30 bar, the molar reflux ratio is 4:1, and the ratio of the overhead gas phase extraction to the amount of material fed is 0.45:1. A condenser and a reboiler are further installed inside the carbon dioxide separation unit 400, and a heat exchanger is used to exchange heat between the anode gas and the crude oxygen.

[0057] Tests have shown that the purity of the liquid carbon dioxide in this embodiment is 99.9999 vol%, the carbon dioxide content in the crude oxygen accounts for 21% of the carbon dioxide content in the anode gas, the carbon dioxide recovery rate is 99.62%, and the power consumption of the electrolytic cell is 3.10 kWh / kg CO 2 It is.

[0058] [Example 2] As in Example 1, the carbon dioxide separation process is carried out in a carbon dioxide separation apparatus, and compared with Example 1, the difference is that in the carbon dioxide separation process, the operating pressure is 60 bar, the molar reflux ratio is 1.4:1, and the mass ratio of the overhead gas phase extract to the raw material is 0.25:1.

[0059] A portion of the bicarbonate-containing aqueous solution is mixed with the crude oxygen generated in the carbon dioxide separation process to obtain a bicarbonate-containing aqueous solution and oxygen gas. In the bicarbonate-ion-containing aqueous solution used in the electrolysis process, the ratio of the amount of bicarbonate ions to the total amount of carbonate ions and bicarbonate ions is 0.01:1. Tests have shown that the purity of the liquid carbon dioxide in this embodiment is 96.0383 vol%, the carbon dioxide content in the crude oxygen accounts for 16% of the carbon dioxide content in the anode gas, the carbon dioxide recovery rate is 99.99%, and the power consumption of the electrolytic cell is 3.4 kWh / kgCO 2 It is.

[0060] [Example 3] As in Example 1, the carbon dioxide separation process is carried out in a carbon dioxide separation apparatus, and compared with Example 1, the difference is that in the carbon dioxide separation process, the operating pressure is 60 bar, the molar reflux ratio is 5:1, and the mass ratio of the overhead gas phase extract to the raw material is 0.5:1.

[0061] A portion of the bicarbonate-containing aqueous solution is mixed with the crude oxygen generated in the carbon dioxide separation process to obtain a bicarbonate-containing aqueous solution and oxygen gas. In the bicarbonate-ion-containing aqueous solution used in the electrolysis process, the ratio of the amount of bicarbonate ions to the total amount of carbonate ions and bicarbonate ions is 0.32:1. Tests have shown that the purity of the liquid carbon dioxide in this embodiment is 99.9999 vol%, the carbon dioxide content in the crude oxygen accounts for 25.7% of the carbon dioxide content in the anode gas, the carbon dioxide recovery rate is 90.61%, and the power consumption of the electrolytic cell is 2.93 kWh / kgCO 2 It is.

[0062] [Example 4] Compared with Example 1, the temperature during the electrolysis was 95°C, the electrolytic cell voltage was 4V, and the current density was 500A / m 2 The difference is that

[0063] Tests have shown that the purity of the liquid carbon dioxide in this embodiment is 99.9968 vol%, the carbon dioxide recovery rate is 99.59%, and the power consumption of the electrolyzer is 3.12 kWh / kg CO 2 It is.

[0064] [Example 5] Compared with Example 1, the difference is that the temperature in the electrolysis process is 50°C.

[0065] Tests have shown that the purity of the liquid carbon dioxide in this embodiment is 99.9986 vol%, the carbon dioxide recovery rate is 99.70%, and the power consumption of the electrolyzer is 3.16 kWh / kg CO 2 It is.

[0066] [Example 6] As compared with Example 1, the difference is that the temperature in the electrolysis process is 200°C.

[0067] Tests have shown that the purity of the liquid carbon dioxide in this embodiment is 99.9938 vol%, the carbon dioxide recovery rate is 99.63%, and the power consumption of the electrolyzer is 3.18 kWh / kg CO 2 It is.

[0068] [Example 7] Compared with Example 1, the electrolytic cell temperature was 25°C, the electrolytic cell voltage was 0.6V, and the current density was 300A / m 2 The difference is that

[0069] Tests have shown that the purity of the liquid carbon dioxide in this embodiment is 99.9971 vol%, the carbon dioxide recovery rate is 99.61%, and the electrolytic cell power consumption is 3.72 kWh / kg CO 2 It is.

[0070] [Example 8] Compared with Example 1, the concentration of hydroxide ions in the alkaline solution is 0.2 mol / L, the concentration of carbonate ions in the carbonate-containing aqueous solution is 0.47 mol / L, the concentration of hydroxide ions is 0.03 mol / L, and the pH of the carbonate-containing aqueous solution is 12.1.

[0071] Through testing, the purity of the liquid carbon dioxide in this embodiment is 99.9856 vol%, the carbon dioxide recovery rate is 99.66%, and the power consumption of the electrolyzer is 4.08 kWh / kg CO 2 It is.

[0072] [Example 9] Compared to Example 1, the difference is that the concentration of hydroxide ions in the alkaline solution is 3 mol / L, the concentration of carbonate ions in the carbonate-containing aqueous solution is 6 mol / L, the concentration of hydroxide ions is 0.9 mol / L, and the pH of the carbonate-containing aqueous solution is 14.

[0073] Through testing, the purity of the liquid carbon dioxide in this embodiment was 99.9816 vol%, the carbon dioxide recovery rate was 99.71%, and the power consumption of the electrolyzer was 3.96 kWh / kg CO 2 It is.

[0074] [Example 10] Compared to Example 1, the difference is that the concentration of hydroxide ions in the alkaline solution is 0.5 mol / L, the concentration of carbonate ions in the carbonate-containing aqueous solution is 2.1 mol / L, the concentration of hydroxide ions is 0 mol / L, and the pH of the carbonate-containing aqueous solution is 14.

[0075] Tests have shown that the purity of the liquid carbon dioxide in this embodiment is 99.9905 vol%, the carbon dioxide recovery rate is 99.55%, and the power consumption of the electrolyzer is 3.38 kWh / kg CO 2 It is.

[0076] [Example 11] Compared to Example 1, the difference is that the concentration of hydroxide ions in the alkaline solution is 1.5 mol / L, the concentration of carbonate ions in the carbonate-containing aqueous solution is 4.5 mol / L, the concentration of hydroxide ions is 0.9 mol / L, and the pH of the carbonate-containing aqueous solution is 10.

[0077] Tests have shown that the purity of the liquid carbon dioxide in this embodiment is 99.9913 vol%, the carbon dioxide recovery rate is 99.69%, and the power consumption of the electrolyzer is 3.98 kWh / kg CO 2 It is.

[0078] [Example 12] Compared to Example 1, the difference is that the concentration of hydroxide ions in the alkaline solution is 0.1 mol / L, while the concentration of carbonate ions in the carbonate-containing aqueous solution is 0.2 mol / L, the concentration of hydroxide ions is 0 mol / L, and the pH of the carbonate-containing aqueous solution is 10.9.

[0079] Through testing, the purity of the liquid carbon dioxide in this embodiment was 99.9953 vol%, the carbon dioxide recovery rate was 99.66%, and the power consumption of the electrolyzer was 4.43 kWh / kg CO 2 It is.

[0080] [Comparative Example 1] Compared with Example 1, this example differs in that carbon dioxide in the air is collected using an aqueous sodium hydroxide solution to obtain a carbonate-containing aqueous solution, that in the carbonate-containing aqueous solution, the ratio of the substance amount of bicarbonate ions to the total substance amount of carbonate ions and bicarbonate ions is 0:1, and that the carbonate-containing aqueous solution is used as an electrolyte and electrolyzed directly in an electrolytic cell to obtain an oxygen gas-containing carbon dioxide mixed gas.

[0081] Tests have shown that the purity of the liquid carbon dioxide in this comparative example is 66.6718 vol%, the carbon dioxide recovery rate is 99.99%, and the power consumption of the electrolyzer is 3.43 kWh / kg CO 2 It is.

[0082] The carbon dioxide recovery rates and electrolytic cell power consumptions measured in all the above examples and comparative examples are summarized in Table 1.

[0083] [Table 1]

[0084] From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects.

[0085] Comparing Examples 1 to 3, in the carbon dioxide separation process, the operating pressure, molar reflux ratio, and ratio of the overhead gas phase extract to the amount of raw material substance include, but are not limited to, the preferred ranges of the present application. By limiting these to the preferred ranges of the present invention, the separation efficiency of carbon dioxide and oxygen gas can be further improved and the purity of liquid carbon dioxide can be improved. In addition, by installing an oxygen gas purification device, the carbon dioxide recovery rate in the entire process can be maintained at a high level, and economic benefits can be improved.

[0086] Comparing Examples 1 to 3 and Comparative Example 1, the carbon dioxide in the air is converted into a carbonate-containing aqueous solution by the carbon dioxide capture process. The carbonate-containing aqueous solution is used to absorb the carbon dioxide in the crude oxygen and convert it into bicarbonate ions, and then the electrolysis process is performed. Compared with the process of electrolysis using carbonate as an electrolyte, the present application can effectively reduce the energy consumption in the electrolysis process by using a bicarbonate-containing aqueous solution as the electrolyte. In the carbon dioxide separation process, the ratio of the carbon dioxide content in the obtained crude oxygen product to the carbon dioxide content in the anode gas, and the dry basis contents of oxygen and carbon dioxide in the crude oxygen gas are limited within a specific range, and the carbon dioxide therein is absorbed by the carbonate-containing aqueous solution obtained in the carbon dioxide capture process to obtain a bicarbonate-containing aqueous solution. This process can obtain high-purity liquid carbon dioxide and maintain a high carbon dioxide recovery rate, and can also reduce the process cost of the carbon dioxide capture and purification process, and further improve the overall economic effect.

[0087] Comparing Examples 1 and 4 to 7, the temperature, electrolytic cell voltage and current density during the electrolysis process include, but are not limited to, the preferred ranges of the present invention. However, limiting them to the preferred ranges of the present application is advantageous for improving the electrochemical reaction rate and current efficiency, and is also advantageous for reducing the energy consumption of the electrolytic cell and thereby reducing the process cost of the carbon dioxide capture and purification process.

[0088] Comparing Examples 1, 8, 9 and 12, it is found that limiting the hydroxide ion concentration in the alkaline solution to the preferred range of the present application is more advantageous in improving the collection efficiency of the alkaline solution for carbon dioxide gas in the air than other ranges. Also, limiting the carbonate ion and hydroxide ion concentrations and pH in the carbonate-containing aqueous solution to the preferred range of the present application is more advantageous in improving the bicarbonate ion content in the bicarbonate-containing solution obtained in the purification process than other ranges, which is advantageous in providing a more sufficient electrolyte supply source for the electrolysis process and is also advantageous in reducing energy consumption.

[0089] Comparing Examples 1, 10 and 11, it is found that limiting the hydroxide ion concentration in the alkaline solution to the more preferred range of the present application is more advantageous in improving the collection efficiency of the alkaline solution for carbon dioxide gas than other ranges. Also, limiting the carbonate ion, hydroxide ion concentrations, the ratio of the substance amount of bicarbonate ion to the total substance amount of carbonate ion and bicarbonate ion, and pH in the carbonate-containing aqueous solution to the more preferred ranges of the present application is more advantageous in improving the collection efficiency of the alkaline solution for carbon dioxide gas than other ranges, while it is more advantageous in improving the content of bicarbonate ion in the bicarbonate-containing solution obtained in the purification process, which is more advantageous in providing a more sufficient electrolyte supply source for the electrolysis process and more advantageous in reducing energy consumption.

[0090] In addition, the terms "first," "second," and the like in the specification and claims of this application are used to distinguish between similar objects and are not necessarily used to describe a particular order or sequence. The terms used in this manner may be appropriately interchanged so that the embodiments of this application described herein can be implemented, for example, in an order other than that described herein.

[0091] The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. For those skilled in the art, the present invention can be modified and changed in various ways. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention. [Explanation of symbols]

[0092] 100 Carbon dioxide capture device 101 Alkaline solution inlet 102 Target component inlet 103 Carbonate-containing aqueous solution outlet 104 Reflux port 200 Oxygen Purification Equipment 201 Crude oxygen inlet 202 Carbonate-containing aqueous solution inlet 203 Hydrogen carbonate-containing aqueous solution outlet 204 Oxygen outlet 210 Bottom liquid flow rate adjustment device 300 Electrolysis Unit 301 Hydrogen carbonate-containing aqueous solution inlet 302 Anode gas outlet 303 Hydrogen gas outlet 304 Regenerated alkaline solution outlet 310 Buffer Tank 311 External water supply inlet 320 1st cooling device 330 Second cooling device 340 Gas-liquid separation equipment 350 Compression Device 360 Drying dehydration equipment 400 Carbon Dioxide Separator 401 Anode gas inlet 402 Liquid carbon dioxide outlet 403 Crude oxygen outlet 500 Carbon Dioxide Detector.

Claims

1. A method for carbon dioxide capture and purification, comprising carbon dioxide capture, electrolysis and carbon dioxide separation, comprising: performing a carbon dioxide capture process on the target component using an alkaline solution to obtain a carbonate-containing aqueous solution; A step of mixing at least a part of the carbonate-containing aqueous solution with the carbon dioxide-containing crude oxygen generated in the carbon dioxide separation process to obtain a hydrogencarbonate-containing aqueous solution and oxygen gas, wherein the volume content of carbon dioxide in the carbon dioxide-containing crude oxygen is 9.7 to 35.9 vol%; Electrolyzing the hydrogen carbonate-containing aqueous solution to obtain anode gas, hydrogen gas, and regenerated alkaline solution; performing the carbon dioxide separation process on the anode gas to obtain liquid carbon dioxide and the carbon dioxide-containing crude oxygen, the carbon dioxide content of the liquid carbon dioxide being 98.5-99.9999 vol%, and the carbon dioxide content of the crude oxygen being 5-40% of the carbon dioxide content of the anode gas; A method for capturing and purifying carbon dioxide.

2. The carbon dioxide separation process is carried out in a carbon dioxide separation device, the operating pressure is 10-60 bar, the molar reflux ratio is (1.4-4):1, and the mass ratio of the overhead gas phase extraction to the raw material is (0.25-0.45):1; 2. The method for capturing and purifying carbon dioxide according to claim 1 .

3. The temperature in the electrolysis process is 50-200° C., the electrolytic cell voltage is 1.1-4 V, and the current density is 500-8000 A / m ２ and in the bicarbonate-containing aqueous solution, the ratio of the amount of bicarbonate ions to the total amount of carbonate ions and bicarbonate ions is (0.1 to 1):

1.

3. The method for capturing and purifying carbon dioxide according to claim 1 or 2.

4. Before performing the carbon dioxide separation process, the carbon dioxide capture and purification method includes: The anode gas may further include a step of sequentially cooling, separating gas and liquid, compressing and drying the anode gas.

2. The method for capturing and purifying carbon dioxide according to claim 1 .

5. After the cooling process, the temperature of the anode gas is reduced to 5 to 50°C.

5. The method for capturing and purifying carbon dioxide according to claim 4.

6. Between the compression step and the separation step, the carbon dioxide capture and purification method further comprises: The method includes a step of exchanging heat between the compressed anode gas and the crude oxygen.

5. The method for capturing and purifying carbon dioxide according to claim 4.

7. the concentration of hydroxide ions in the alkaline solution is 0.2 to 3 mol / L, the concentration of carbonate ions in the carbonate-containing aqueous solution is 0.2 to 6 mol / L and the concentration of hydroxide ions is 0 to 1.5 mol / L, and the pH of the carbonate-containing aqueous solution is 10 to 14; Preferably, the concentration of hydroxide ions in the alkaline solution is 0.5 to 1.5 mol / L, the concentration of carbonate ions in the carbonate-containing aqueous solution is 0.5 to 5.5 mol / L, the concentration of hydroxide ions is 0 to 1 mol / L, and the pH of the carbonate-containing aqueous solution is 12 to 14.

2. The method for capturing and purifying carbon dioxide according to claim 1 .

8. The method for capturing and purifying carbon dioxide comprises the steps of: Further comprising a step of recycling at least a portion of the carbonate-containing aqueous solution and / or the regenerated alkaline solution back into the carbon dioxide capture process; 2. The method for capturing and purifying carbon dioxide according to claim 1 .

9. 1. A carbon dioxide capture and purification system, comprising: The system includes a carbon dioxide capture device (100), an oxygen gas purification device (200), an electrolysis unit (300), a carbon dioxide separation device (400), a carbon dioxide detection device (500), and a valve (600), The carbon dioxide capture device (100) is provided with an alkaline solution inlet (101), a target component inlet (102), and a carbonate-containing aqueous solution outlet (103); The oxygen gas purification device (200) is provided with a crude oxygen inlet (201), a carbonate-containing aqueous solution inlet (202), a hydrogencarbonate-containing aqueous solution outlet (203), and an oxygen gas outlet (204), and the carbonate-containing aqueous solution inlet (202) and the carbonate-containing aqueous solution outlet (103) are provided in communication with each other; The electrolysis unit (300) is provided with an inlet for a bicarbonate-containing aqueous solution (301), an anode gas outlet (302), a hydrogen gas outlet (303) and a regenerated alkaline solution outlet (304), and the inlet for a bicarbonate-containing aqueous solution (301) and the outlet for a bicarbonate aqueous solution (203) are connected to each other through a pipeline for transporting an aqueous bicarbonate solution; The carbon dioxide separation device (400) is provided with an anode gas inlet (401), a liquid carbon dioxide outlet (402) and a crude oxygen outlet (403), the anode gas inlet and the anode gas discharge outlet (302) are connected by an anode gas transport pipeline, and the crude oxygen outlet (403) and the crude oxygen inlet (201) are connected by a crude oxygen transport pipeline, The carbon dioxide detection device (500) is used to measure the carbon dioxide content in the crude oxygen transport pipeline; The valve (600) is installed in the crude oxygen transport pipeline and is located downstream of the carbon dioxide detection device (500), and the valve (600) is installed in association with the carbon dioxide detection device (500), and when the carbon dioxide content reaches a predetermined value, the valve (600) opens. Carbon dioxide capture and purification system.

10. The carbon dioxide capture device is provided with a reflux port (104) which is in communication with the regenerated alkaline liquid outlet (304) and the carbonate-containing aqueous solution outlet (103), 10. The carbon dioxide capture and purification system according to claim 9.

11. The reflux port (104) and the regenerated alkaline liquid discharge port (304) are connected to each other by a regenerated alkaline liquid transport pipe, The carbon dioxide capture and purification system further includes a buffer tank (310) and a first cooling device (320) sequentially installed in the regenerated alkaline liquid transport pipeline along the material flow direction.

11. The carbon dioxide capture and purification system of claim 10.

12. The buffer tank (310) is provided with an external water supply inlet (311) for adjusting the concentration of the regenerated alkaline solution in the buffer tank (310); 12. The carbon dioxide capture and purification system of claim 11.

13. The carbon dioxide capture and purification system further includes a second cooling device (330), a gas-liquid separation device (340), a compression device (350), and a drying and dehydrating device (360) that are sequentially installed in the anode gas transport pipeline along the material flow direction in the anode gas transport pipeline.

10. The carbon dioxide capture and purification system according to claim 9.

14. The carbon dioxide capture and purification system further includes a heat exchanger, the heat exchanger being installed in the anode gas transport pipeline between the compression device (350) and the carbon dioxide separation device and used for heat exchange between the anode gas and crude oxygen.

14. The carbon dioxide capture and purification system of claim 13.

15. The carbon dioxide capture and purification system further includes a column bottom liquid flow rate control device (210) installed in the aqueous bicarbonate solution transport pipeline.

10. The carbon dioxide capture and purification system according to claim 9.

16. The compression device (350) includes 2 to 8 stages of compressors, and a third cooling device and a liquid separation device are installed between each stage of the compressors.

14. The carbon dioxide capture and purification system of claim 13.

17. The carbon dioxide separation device (400) further includes a condenser and a reboiler for adjusting the carbon dioxide content in the crude oxygen transport line.

10. The carbon dioxide capture and purification system according to claim 9.

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