Methods and systems for capturing and purifying carbon dioxide.

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 of related applications> This application is based on and claims priority from a Chinese application with application number 202210577489.3, filed on May 25, 2022. The disclosures of the said Chinese application are incorporated into this application as a whole. This invention relates to the technology of carbon dioxide capture, and more specifically to a method and system for capturing and purifying carbon dioxide. [Background technology]

[0002] As a major component of greenhouse gases, CO2 emissions are increasing, and the problem of global warming is attracting attention. CO2 capture technology can reduce CO2 emissions and effectively lower the concentration of CO2 in the atmosphere, so the development of efficient CO2 capture technology is a focus of research.

[0003] Currently, various carbon capture technologies are emerging from both domestic and international sources. For example, Carbon Engineering (CE) has developed a direct air capture process using KOH and Ca(OH)2 as the main absorbent solutions. This process uses a KOH solution to absorb CO2 from the air, converting the KOH solution into a K2CO3 solution. Subsequently, KOH is regenerated using a Ca(OH)2 solution. During the regeneration process, CaCO3 solid is generated from the Ca(OH)2 solution. The CaCO3 solid is calcined at high temperatures to obtain CaO, and then the CaO is reacted with H2O again to obtain a Ca(OH)2 solution. In the above process, a stable inorganic alkali is used as the absorbent, allowing for stable and continuous operation and enabling large-scale applications. However, the overall process flow is long, and there are problems with energy consumption during the regeneration process, particularly in the calcination of the CaCO3 solid, as well as secondary carbon emissions.

[0004] By electrolyzing a carbonate solution in an electrolysis process, the regeneration of an alkaline solution can be achieved, and the collected CO2 can be electrolytically extracted from the carbonate solution, which can to some extent replace the regeneration of the alkaline solution with a Ca(OH)2 solution and the calcination of CaCO3. However, when the carbonate solution added to the electrolytic cell contains unreacted hydroxide ions OH - in it, the hydroxide ions are discharged first in the electrolysis process, and carbonate ions are electrolyzed only after OH - is completely consumed. Also, electrolyzing carbonate ions until CO2 is generated involves the following two steps: namely, converting carbonate ions CO3 2- to bicarbonate ions HCO3 - , and then electrolyzing HCO3 - to CO2. Therefore, when the carbonate solution added to the electrolytic cell does not contain OH - and contains a predetermined amount of HCO3 - , the power consumption of the electrolytic cell in the electrolysis process can be reduced to some extent. However, when collecting CO2 with an alkaline solution, especially when collecting it from air with a low CO2 concentration, a high OH - concentration can guarantee the CO2 capture rate. Therefore, in order to obtain a high CO2 capture rate, usually, a predetermined amount of OH - is included in the carbonate solution after absorption, thereby increasing the power consumption of the electrolytic cell.

[0005] Also, theoretically, about 30% of O2 is mixed into the gaseous CO2 generated by electrolysis. When separating O2 and CO2 using a conventional CO2 separation tower, when obtaining a high-purity liquid CO2 product, a large amount of CO2 is carried out with the O2 discharged from the top of the tower, and the CO2 recovery rate cannot be guaranteed and the capture rate of the entire system decreases.

[0006] Therefore, the research and development of a carbon dioxide capture and purification method and system are of great significance for simultaneously satisfying a high carbon dioxide capture efficiency and low energy consumption.

Summary of the Invention

Problems to be Solved by the Invention

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

[0008] To achieve the above objective, the present invention provides a method for capturing and purifying carbon dioxide. The method for capturing and purifying carbon dioxide includes carbon dioxide capture, electrolysis, and carbon dioxide separation, and comprises the steps of: performing a carbon dioxide capture 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 volume content of carbon dioxide in the carbon dioxide-containing crude oxygen is 9.7 to 35.9 vol%; electrolyzing the bicarbonate-containing aqueous solution to obtain an 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 to 99.9999 vol% and the carbon dioxide content in the crude oxygen accounts for 5 to 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 apparatus, with an operating pressure of 10-60 bar, a molar reflux ratio of (1.4-4):1, and a molar ratio of (0.25-0.45):1 between the gas-phase sample at the top of the column and the raw material.

[0010] Furthermore, the electrolysis process temperature is 50-200°C, the electrolytic cell voltage is 1.1-4V, and the current density is 500-8000 A / m². 2Therefore, in an aqueous solution containing bicarbonate, 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.

[0011] Furthermore, prior to the carbon dioxide separation process, the carbon dioxide capture and purification method further includes a process of sequentially performing cooling, gas-liquid separation, compression, and drying dehydration on the anode gas.

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

[0013] Furthermore, the compression process and carbon dioxide Between the separation process and the carbon dioxide capture and purification method, there is a step of heat exchange between the anodic gas, which has undergone a compression process, and crude oxygen. moreover include.

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

[0015] Furthermore, the method of carbon dioxide capture and purification is at least a part of the carbon dioxide hydrogen The process further includes the step of returning a salt-containing aqueous solution and / or a regenerated alkaline solution to the carbon dioxide capture process for reuse.

[0016] To achieve the above object, another aspect of the present invention provides a carbon dioxide capture and purification system. The carbon dioxide capture and purification system 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. An alkaline solution inlet, a target component inlet, and a carbonate-containing aqueous solution discharge outlet are provided in the carbon dioxide capture device. A raw oxygen inlet, a carbonate-containing aqueous solution inlet, a bicarbonate-containing aqueous solution discharge outlet, and an oxygen gas discharge outlet are provided in the oxygen gas purification device, and the carbonate-containing aqueous solution inlet and the carbonate-containing aqueous solution discharge outlet are provided in communication. A bicarbonate-containing aqueous solution inlet, an anode gas discharge outlet, a hydrogen gas outlet, and a regenerated alkaline solution discharge outlet are provided in the electrolysis unit, and the bicarbonate-containing aqueous solution inlet and the bicarbonate-containing aqueous solution discharge outlet are communicated by a bicarbonate aqueous solution transport pipeline. An anode gas inlet, a liquid carbon dioxide outlet, and a raw oxygen outlet are provided in the carbon dioxide separation device, the anode gas inlet and the anode gas discharge outlet are communicated by an anode gas transport pipeline, and the raw oxygen outlet and the raw oxygen inlet are communicated by a raw oxygen transport pipeline. The carbon dioxide detection device is used to measure the content of carbon dioxide in the raw oxygen transport pipeline. The valve is provided in the raw oxygen transport pipeline and is located downstream of the carbon dioxide detection device. The valve is installed in conjunction with the carbon dioxide detection device, and when the content of carbon dioxide reaches a predetermined value, the valve opens.

[0017] Furthermore, the carbon dioxide capture device is further provided with reflux ports respectively communicating with the regenerated alkaline solution discharge outlet and the carbonate-containing aqueous solution discharge outlet. hydrogen Furthermore, the reflux port and the regenerated alkaline solution discharge outlet are communicated by a regenerated alkaline solution transport pipeline, and the carbon dioxide capture and purification system further includes a buffer tank and a first cooling device sequentially installed in the regenerated alkaline solution transport pipeline along the flow direction of the material.

[0018] Furthermore, an external water supply inlet for adjusting the concentration of the regenerated alkaline solution in the buffer tank is provided in the buffer tank.

[0019]

[0020] ​Furthermore, the carbon dioxide capture and purification system further includes a second cooling unit, a gas-liquid separator, a compressor, and a drying and dewatering unit, 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 compressor and the carbon dioxide separator and is configured to exchange heat between the anode gas and crude oxygen.

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

[0023] Furthermore, the compression system consists of 2 to 8 stages of compressors, with a third cooling device and a liquid separator installed between each stage of compressors.

[0024] Furthermore, a condenser and a reboiler are installed inside the carbon dioxide separation unit to regulate the carbon dioxide content in the crude oxygen transport pipeline. [Effects of the Invention]

[0025] Applying the technical solution of this application, carbon dioxide in the target component is converted into a carbonate-containing aqueous solution through a carbon dioxide capture process. Carbon dioxide in crude oxygen is absorbed using the carbonate-containing aqueous solution to produce bicarbonate. Salt-containing aqueous solutionThe carbon dioxide is converted to a carbonate solution, and then an electrolysis process is carried out. Compared to processes that use carbonate as the electrolyte for electrolysis, this invention effectively reduces 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 carbon dioxide content in the obtained crude oxygen product to the carbon dioxide content in the anode gas, and the dry-weighted content of oxygen and carbon dioxide in the crude oxygen gas are limited to a specific range. Furthermore, the carbon dioxide in the obtained crude oxygen product is absorbed using the carbonate-containing aqueous solution obtained in the carbon dioxide capture process. As a result, this process can obtain high-purity liquid carbon dioxide, maintain a high carbon dioxide recovery rate, reduce the process cost of the carbon dioxide capture and purification process, and further enhance its overall economic effect. [Brief explanation of the drawing]

[0026] The drawings forming part of this application are for the purpose of providing a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are for the purpose of interpreting the present invention and do not constitute an unreasonable limitation of the present invention. [Figure 1] This is a schematic diagram of the carbon dioxide capture and purification system structure in Example 1 of this application. [Modes for carrying out the invention]

[0027] Where there is no contradiction, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail in relation to the embodiments.

[0028] As explained in the background technology, in conventional carbon dioxide collection and utilization processes, in order to improve the yield of liquid carbon dioxide, the proportion of liquid carbon dioxide in the anode gas during the carbon dioxide separation process is usually increased as much as possible. However, as a result, a large amount of carbon dioxide contained in the crude oxygen obtained after separation is not effectively utilized, which leads to a low carbon dioxide collection and utilization rate and high energy consumption for the entire process. To solve the above problems, this application provides a method for carbon dioxide collection and purification, which includes carbon dioxide collection, electrolysis, and carbon dioxide separation. The carbon dioxide capture and purification method includes the steps of: performing a carbon dioxide capture 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 the carbon dioxide-containing crude oxygen generated in the carbon dioxide separation process to obtain a bicarbonate-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 bicarbonate-containing aqueous solution to obtain an 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 to 99.9999 vol% and the carbon dioxide content in the crude oxygen accounts for 5 to 40% of the carbon dioxide content in the anode gas.

[0029] The carbon dioxide capture process converts carbon dioxide in the target component into a carbonate-containing aqueous solution. The carbonate-containing aqueous solution absorbs carbon dioxide from crude oxygen and converts it into bicarbonate ions, after which an electrolysis process is carried out. Compared to processes that use carbonate as the electrolyte for electrolysis, this invention uses a bicarbonate-containing aqueous solution as the electrolyte, which effectively reduces energy consumption in the electrolysis process.

[0030] In the carbon dioxide separation process, the carbon dioxide content in the obtained crude oxygen product is proportional to the carbon dioxide content in the anode gas, and the oxygen and carbon dioxide content in the crude oxygen gas is limited to a specific range. Furthermore, the carbonate-containing aqueous solution obtained in the carbon dioxide collection process is used to absorb carbon dioxide from the obtained crude oxygen product to obtain a bicarbonate-containing aqueous solution (CO3 2- +CO2+H2O→HCO3 - By doing so, the process can obtain high-purity liquid carbon dioxide and maintain a high level of carbon dioxide recovery. Furthermore, it reduces the process costs of the carbon dioxide capture and purification process, thereby increasing its overall economic effectiveness.

[0031] In a preferred embodiment, the carbon dioxide separation process is carried out in a carbon dioxide separation apparatus, the operating pressure is 10 to 60 bar, the molar reflux ratio is (1.4 to 4):1, and the ratio of the amount of substance of the gas-phase sample at the top of the column to the raw material is (0.25 to 0.45):1. The operating pressure, molar reflux ratio, and the ratio of the amount of substance of the gas-phase sample at the top of the column to the raw material are within, but 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, the recovery rate of carbon dioxide in the entire process can be increased, and the economic effect can be improved.

[0032] In the electrolysis process, the anodic reaction involves the discharge of carbonate ions in an aqueous bicarbonate solution, generating carbon dioxide-containing crude oxygen, while the cathode reaction involves water molecules gaining electrons, generating hydrogen. The reaction equation is HCO3. - →CO2↑+O2↑+H + (Anode), H2O→H2↑+OH - This is the cathode. The hydroxide ions generated at the cathode combine with metal cations in the system to form a regenerated alkaline solution.

[0033] In a preferred embodiment, the electrolysis process temperature is 50-200°C, the electrolytic cell voltage is 1.1-4V, and the current density is 500-8000 A / m². 2Therefore, in an aqueous solution containing bicarbonate, the ratio of the amount of bicarbonate ions to the total amount of carbonate ions and bicarbonate ions is (0.1~1):1. The temperature, electrolytic cell voltage, and current density of the electrolysis process are within the above range, but are not limited to these. Limiting these to the above range is advantageous for improving the electrochemical reaction rate and current efficiency, as well as reducing the energy consumption of the electrolytic cell and lowering the process cost of the carbon dioxide capture and purification process.

[0034] In a preferred embodiment, prior to the carbon dioxide separation process, the carbon dioxide capture and purification method further includes a process of sequentially performing cooling, gas-liquid separation, compression, and drying dewatering on the anode gas. Sequentially employing the above treatment methods on the anode gas is advantageous in providing good preconditions for the subsequent carbon dioxide separation process, contributing to the execution of the carbon dioxide separation process and further improving the carbon dioxide separation efficiency.

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

[0036] In a preferred embodiment, a gas-liquid separation process yields a mixed gas containing oxygen, carbon dioxide, and water vapor, as well as condensed water. Here, the dry-based molar content of oxygen in the mixed gas is 15-45%.

[0037] In a preferred embodiment, the compression process and carbon dioxide Between the separation process and the carbon dioxide capture and purification method, there is a step of heat exchange between the anodic gas, which has undergone a compression process, and crude oxygen. moreover The above heat exchange method is advantageous for lowering the anode gas temperature and can also heat the crude oxygen gas, thereby improving the carbon dioxide absorption rate during the purification process.

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

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

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

[0041] A second aspect of this application further provides a carbon dioxide collection and purification system. This carbon dioxide collection and purification system includes a carbon dioxide collection 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 collection device 100 is equipped 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 equipped 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, with the carbonate-containing aqueous solution inlet 202 and the carbonate-containing aqueous solution outlet 103 being connected. The electrolysis unit 300 is equipped 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. 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 equipped with an anode gas inlet 401, a liquid carbon dioxide outlet 402, and a crude oxygen outlet 403. 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. A carbon dioxide detection device 500 is used to measure the carbon dioxide content in the crude oxygen transport pipeline. A valve 600 is installed in the crude oxygen transport pipeline and is located downstream of the carbon dioxide detection device 500. The valve 600 is installed in conjunction with the carbon dioxide detection device 500, and opens when the carbon dioxide content reaches a predetermined value.

[0042] The alkaline solution can capture carbon dioxide from the target component to obtain a carbonate-containing aqueous solution. The resulting carbonate-containing aqueous solution is discharged from the carbonate-containing aqueous solution outlet 103. The oxygen purification device 200 is equipped with a crude oxygen inlet 201, and the carbon dioxide-containing crude oxygen enters the oxygen gas purification device 200 through the crude oxygen inlet 201 to obtain oxygen gas. The obtained oxygen gas is discharged from the oxygen gas outlet 204. In addition, the carbon dioxide-containing crude oxygen reacts with some of the carbonate-containing aqueous solution to produce a bicarbonate-containing aqueous solution, which is discharged from the bicarbonate-containing aqueous solution outlet 203. The discharged bicarbonate-containing aqueous solution is sent to the electrolysis unit 300 via the bicarbonate aqueous solution transport pipeline and participates in the electrolysis process as an electrolyte. The anode gas obtained from electrolysis is discharged from the anode gas outlet 302 and sent to the anode gas inlet 401 via the anode gas transport pipeline. The hydrogen gas obtained from electrolysis is discharged via the hydrogen gas outlet 303, and the regenerated alkaline solution obtained from electrolysis is discharged via the regenerated alkaline solution outlet 304. To detect the carbon dioxide content in the crude oxygen product, a carbon dioxide detection device 500 is further installed in the system. By installing the valve 600 at the specified position, when the carbon dioxide content reaches a predetermined value, the valve 600 opens, and crude oxygen is discharged into the crude oxygen inlet. 201 It can be controlled so that the oxygen enters the oxygen purification device 200 in which it is installed.

[0043] The carbon dioxide capture device 100 can convert carbon dioxide in the target component into a carbonate-containing aqueous solution. Using the oxygen purification device 200, carbon dioxide in crude oxygen is absorbed into the carbonate-containing aqueous solution. A carbonate-containing aqueous solution Bicarbonate Salt-containing aqueous solution After conversion, the electrolysis process is carried out using the electrolysis unit 300. Compared to carrying out the electrolysis process using carbonate as the electrolyte, the electrolysis unit 300 of this application can effectively reduce the energy consumption of the electrolysis process by carrying out the electrolysis process using an aqueous solution containing bicarbonate as the electrolyte.

[0044] By installing a carbon dioxide detection device 500 and a valve 600, the carbon dioxide content in the obtained crude oxygen product is limited to a predetermined value, and the carbon dioxide within it is absorbed by a carbonate-containing aqueous solution obtained in the carbon dioxide capture process to produce a bicarbonate-containing aqueous solution (CO3 2- +CO2+H2O→HCO3 - This allows the process to obtain high-purity liquid carbon dioxide, maintain a high carbon dioxide recovery rate, and reduce the cost of the carbon dioxide capture and purification system, thereby increasing its overall economic effectiveness.

[0045] In a preferred embodiment, the carbon dioxide collection device 100 is further equipped with a reflux port 104, the reflux port 104 being connected to a regenerated alkaline solution outlet 304 and carbon dioxide hydrogen Salt-containing aqueous solution outlet 2 Each of the 03 ports is connected to and installed. The adoption of the above-mentioned reflux port 104 is advantageous in improving the absorption rate of the target component in the carbon dioxide capture process, further advantageous in improving the production rate of the carbonate-containing aqueous solution obtained after capture, and also advantageous in 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 buffer tanks 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 buffer tanks 310 and the first cooling device 320 is advantageous for controlling the pH and temperature changes of the alkaline solution to be maintained within a small fluctuation range, for suppressing excessive fluctuations in the physicochemical properties of the alkaline solution due to reflux of the regenerated alkaline solution, for improving the absorption rate of the alkaline solution to carbon dioxide gas in the air, and for improving the carbonate generation rate in the carbonate-containing aqueous solution.

[0047] In order to further suppress excessive fluctuations in the physicochemical properties of the alkaline solution due to reflux of the regenerated alkaline solution, and to further improve the absorption rate of the alkaline solution by carbon dioxide gas in the air, in a preferred embodiment, the buffer tank 310 is a buffer tank 310 An external water inlet 311 is installed to adjust the concentration of the regenerated alkaline solution.

[0048] In a preferred embodiment, the carbon dioxide capture and purification system further includes a second cooler 330, a gas-liquid separator 340, a compressor 350, and a drying and dewatering unit 360, which are sequentially installed in the anode gas transport pipeline along the material flow direction in the anode gas transport pipeline. The second cooler 330 can be used for cooling the anode gas, the gas-liquid separator 340 can be used for gas-liquid separation of the anode gas, the compressor 350 can be used to reduce the volume of the anode gas, and the drying and dewatering unit 360 can be used for drying the anode gas. Sequentially employing the above treatments on the anode gas is advantageous in providing good preconditions for the subsequent carbon dioxide separation process, thereby facilitating the carbon dioxide separation process and improving 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 compressor 350 and the carbon dioxide separator 400, and which exchanges heat between the anode gas and crude oxygen. Exchanging heat between the anode gas and crude oxygen using the heat exchanger is advantageous for lowering the anode gas temperature and can also heat the crude oxygen gas to improve the carbon dioxide absorption rate in the purification process.

[0050] In a preferred embodiment, the carbon dioxide capture and purification system further includes a bottom liquid flow rate regulator 210, which is installed in the bicarbonate aqueous solution transport pipeline. The installation of the bottom liquid flow rate regulator 210 is advantageous for adjusting and controlling the flow rate of the bicarbonate-containing aqueous solution to be within an appropriate range, and thus facilitates control of the progress of the electrolysis process in the electrolysis unit 300.

[0051] Multistage compressors can gradually increase the pressure of the anode gas, and compared to single-stage compressors, they generate more power from the air and have higher compression efficiency, making them suitable for larger-scale operations and continuous applications. In a preferred embodiment, the compressor 350 is a 2 to 8-stage compressor, with a third cooling device and a liquid separator installed between each stage of the compressor. The number of stages in the compressor 350 is within but not limited to the above range. Limiting it to the above range is advantageous for reducing energy consumption while increasing the anode gas pressure. Furthermore, installing a third cooling device between each stage of the compressor is advantageous for liquefying the compressed anode gas and generating 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 unit 400 to adjust the carbon dioxide content in the crude oxygen transport pipeline.

[0053] The present application will be described in more detail below in relation to specific embodiments, but these embodiments should not be understood as limitations on the scope of protection claimed in this application.

[0054] In this application, the unit kWh / kgCO2 represents the electrical energy (kWh) consumed to generate 1 kg of CO2 in the electrolytic cell during the electrolysis process. The carbon dioxide recovery rate refers to the weight percentage of the total weight of carbon dioxide collected in the carbon dioxide capture process that is accounted for by the weight of liquid carbon dioxide obtained in the carbon dioxide separation 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] The carbon dioxide capture and purification method includes the following: In the carbon dioxide collection device 100, carbon dioxide in the air is collected with a KOH solution (i.e., the carbon dioxide collection process is performed) to obtain an aqueous solution containing carbonate. Here, the alkaline solution is introduced into the carbon dioxide collection device 100 via the alkaline solution inlet 101, and the air is treated with the target component entrance The solution is introduced into the carbon dioxide collection device 100 via 102, and 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 crude oxygen generated during the carbon dioxide separation process to obtain a bicarbonate-containing aqueous solution and oxygen. In this 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 bicarbonate-containing aqueous solution obtained above is sent to the electrolysis unit 300 via a bicarbonate aqueous solution transport pipeline, and the flow rate of the bicarbonate-containing aqueous solution is adjusted by a bottom liquid flow rate adjustment device 210. In the electrolysis unit 300, the bicarbonate-containing aqueous solution obtained above is electrolyzed. The temperature of the electrolysis process is 60°C, the electrolytic cell voltage is 4V, and the current density is 8000 A / m². 2 The system is set up to achieve the following: After electrolysis, anode gas, hydrogen gas, and regenerated alkaline solution are obtained. The regenerated alkaline solution is returned to the carbon dioxide collection process for reuse, and the regenerated alkaline solution passes sequentially through the regenerated alkaline solution transport pipeline to the buffer tank 310 and the first cooling device 320, while water is supplied to the buffer tank 310 from the external water supply inlet 311, controlling the concentration of hydroxide in the alkaline solution to be maintained at 1 mol / L. 2nd cooling device 330The anode gas is cooled to a temperature of 20°C, and then the cooled anode gas is subjected to gas-liquid separation using a gas-liquid separator 340 to obtain a mixed gas containing oxygen, carbon dioxide, and water vapor, as well as condensed water. The dry-based molar content of oxygen gas in the mixed gas was detected to be 32.4 vol%. The compression process is carried out in a compressor 350, which is performed using a four-stage compressor, with a third cooling device and a liquid separator installed between each stage of the compressor. After being processed in a drying and dewatering device 360, the processed anode gas is obtained. The anode gas after the above treatment is introduced into a 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 amount of substance collected from the top gas phase to the amount of substance supplied 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 crude oxygen.

[0057] Tests revealed that the purity of the liquid carbon dioxide in this embodiment was 99.9999 vol%, the carbon dioxide content in crude oxygen accounted for 21% of the carbon dioxide content in the anode gas, the carbon dioxide recovery rate was 99.62%, and the power consumption of the electrolytic cell was 3.10 kWh / kgCO2.

[0058] [Example 2] Similar to Example 1, the carbon dioxide separation process is carried out in a carbon dioxide separation apparatus. 400 The procedure was carried out in the following ways, and compared to Example 1, it differed in that the operating pressure in the carbon dioxide separation process was 60 bar, the molar reflux ratio was 1.4:1, and the ratio of the amount of substance between the gas-phase sample at the top of the column and the raw material was 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 showed that the purity of the liquid carbon dioxide in this embodiment was 96.0383 vol%, the carbon dioxide content in the crude oxygen accounted for 16% of the carbon dioxide content in the anode gas, the carbon dioxide recovery rate was 99.99%, and the power consumption of the electrolytic cell was 3.4 kWh / kgCO2.

[0060] [Example 3] Similar to Example 1, the carbon dioxide separation process is carried out in a carbon dioxide separation apparatus. 400 The procedure was carried out in the following way, and compared to Example 1, it differed in that the operating pressure in the carbon dioxide separation process was 60 bar, the molar reflux ratio was 5:1, and the ratio of the amount of substance between the gas-phase sample at the top of the column and the raw material was 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 showed that the purity of the liquid carbon dioxide in this embodiment was 99.9999 vol%, the carbon dioxide content in the crude oxygen accounted for 25.7% of the carbon dioxide content in the anode gas, the carbon dioxide recovery rate was 90.61%, and the power consumption of the electrolytic cell was 2.93 kWh / kgCO2.

[0062] [Example 4] Compared to Example 1, the electrolysis process temperature was 95°C, the electrolytic cell voltage was 4V, and the current density was 500A / m². 2 They differ in that respect.

[0063] Tests revealed that the purity of the liquid carbon dioxide in this embodiment was 99.9968 vol%, the carbon dioxide recovery rate was 99.59%, and the power consumption of the electrolytic cell was 3.12 kWh / kgCO2.

[0064] [Example 5] Compared to Example 1, this example differs in that the temperature during the electrolysis process is 50°C.

[0065] Tests revealed that the purity of the liquid carbon dioxide in this embodiment was 99.9986 vol%, the carbon dioxide recovery rate was 99.70%, and the power consumption of the electrolytic cell was 3.16 kWh / kgCO2.

[0066] [Example 6] Compared to Example 1, this method differs in that the temperature during the electrolysis process is 200°C.

[0067] Tests revealed that the purity of the liquid carbon dioxide in this embodiment was 99.9938 vol%, the carbon dioxide recovery rate was 99.63%, and the power consumption of the electrolytic cell was 3.18 kWh / kgCO2.

[0068] [Example 7] Compared to Example 1, this example differs in that the electrolytic cell temperature is 25°C, the electrolytic cell voltage is 0.6V, and the current density is 300A / m2.

[0069] Tests revealed that the purity of the liquid carbon dioxide in this embodiment was 99.9971 vol%, the carbon dioxide recovery rate was 99.61%, and the electrolytic cell power consumption was 3.72 kWh / kgCO2.

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

[0071] Tests revealed that the purity of the liquid carbon dioxide in this embodiment was 99.9856 vol%, the carbon dioxide recovery rate was 99.66%, and the electrolytic cell power consumption was 4.08 kWh / kgCO2.

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

[0073] Tests revealed that 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 electrolytic cell was 3.96 kWh / kgCO2.

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

[0075] Tests revealed that the purity of the liquid carbon dioxide in this embodiment was 99.9905 vol%, the carbon dioxide recovery rate was 99.55%, and the power consumption of the electrolytic cell was 3.38 kWh / kgCO2.

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

[0077] Tests revealed that the purity of the liquid carbon dioxide in this embodiment was 99.9913 vol%, the carbon dioxide recovery rate was 99.69%, and the power consumption of the electrolytic cell was 3.98 kWh / kgCO2.

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

[0079] Tests revealed that 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 electrolytic cell was 4.43 kWh / kgCO2.

[0080] [Comparative Example 1] This method differs from Example 1 in that it uses an aqueous sodium hydroxide solution to capture carbon dioxide from the air to obtain a carbonate-containing aqueous solution, the ratio of the amount of bicarbonate ions to the total amount of carbonate and bicarbonate ions in the carbonate-containing aqueous solution is 0:1, and the carbonate-containing aqueous solution is used as the electrolyte in an electrolytic cell to obtain an oxygen-containing carbon dioxide mixed gas.

[0081] Tests revealed that the purity of the liquid carbon dioxide in this comparative example was 66.6718 vol%, the carbon dioxide recovery rate was 99.99%, and the power consumption of the electrolytic cell was 3.43 kWh / kgCO2.

[0082] Table 1 summarizes the carbon dioxide recovery rate and electrolytic cell power consumption measured in all of the above examples and comparative examples.

[0083] [Table 1]

[0084] From the above explanation, it can be seen that the above embodiment of the present invention achieves the following technical effects.

[0085] A comparison of Examples 1 to 3 shows that in the carbon dioxide separation process, the operating pressure, molar reflux ratio, and the ratio of the amount of substance of the gas-phase sample at the top of the column to the amount of substance of the raw material are included in but not limited to the preferred range of this application. However, by limiting them to the preferred range of the present invention, the separation efficiency of carbon dioxide and oxygen gas can be further improved, the purity of liquid carbon dioxide can be improved, and the recovery rate of carbon dioxide throughout the entire process can be maintained at a high level by installing an oxygen gas purification device, thereby improving economic efficiency.

[0086] Comparing Examples 1-3 and Comparative Example 1, the carbon dioxide capture process converts carbon dioxide in the air into a carbonate-containing aqueous solution. Using the carbonate-containing aqueous solution, carbon dioxide in crude oxygen is absorbed to produce bicarbonate. Containing aqueous solution After conversion, an electrolysis process was carried out. Compared to a process that uses carbonate as the electrolyte, this 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 ratio of the carbon dioxide content in the obtained crude oxygen product to the carbon dioxide content in the anode gas, and the dry-based content of oxygen and carbon dioxide in the crude oxygen gas are limited to a specific range, and the carbon dioxide in it is absorbed with a carbonate-containing aqueous solution obtained in the carbon dioxide collection process to obtain a bicarbonate-containing aqueous solution. As a result, 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 collection and purification process, thereby increasing its overall economic effect.

[0087] A comparison of Examples 1, 4-7 shows that the temperature, electrolytic cell voltage, and current density of the electrolysis process include, but are not limited to, the preferred range of the present invention. However, limiting them to the preferred range of this application is advantageous for improving the electrochemical reaction rate and current efficiency, and 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] A comparison of Examples 1, 8, 9, and 12 shows that limiting the hydroxide ion concentration in the alkaline solution to the preferred range of this application is advantageous in improving the collection efficiency of the alkaline solution from carbon dioxide gas in the air, compared to other ranges. Furthermore, limiting the concentrations of carbonate ions, hydroxide ions, and pH in the carbonate-containing aqueous solution to the preferred range of this application is advantageous in improving the bicarbonate ion content in the bicarbonate-containing solution obtained in the purification process, which is advantageous in providing a more sufficient electrolyte supply to the electrolysis process and further advantageous in reducing energy consumption.

[0089] A comparison of Examples 1, 10, and 11 shows that limiting the hydroxide ion concentration in the alkaline solution to the more preferred range of this application is advantageous for further improving the collection efficiency of the alkaline solution from carbon dioxide gas compared to other ranges. Furthermore, limiting the concentrations of carbonate ions and hydroxide ions, the ratio of the amount of substance of bicarbonate ions to the total amount of substance of carbonate ions and bicarbonate ions, and the pH in the carbonate-containing aqueous solution to the more preferred range of this application is advantageous for further improving the collection rate of the alkaline solution from carbon dioxide, while also being advantageous for further increasing the bicarbonate ion content in the bicarbonate-containing solution obtained in the purification process. This is advantageous for providing a more sufficient electrolyte supply to the electrolysis process and further advantageous for reducing energy consumption.

[0090] Furthermore, terms such as "first," "second," etc., used in the specification and claims of this application are for the purpose of distinguishing similar subjects and are not necessarily used to describe a specific order or sequence. These terms may be replaced as appropriate so that the embodiments of this application described herein can be implemented, for example, in an order other than that described herein.

[0091] The foregoing describes only preferred embodiments of the present invention and is not intended to limit it. Those skilled in the art will know that the present invention can be modified and altered in various ways. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be within the scope of protection. [Explanation of symbols]

[0092] 100 Carbon dioxide capture devices 101 Alkaline solution inlet 102 Target ingredient entry point 103 Carbonate-containing aqueous solution outlet 104 Reflux port 200 Oxygen Purifier 201 Crude oxygen inlet 202 Inlet for carbonate-containing aqueous solution 203 Outlet for aqueous solution containing bicarbonate 204 Oxygen outlet 210 Bottom liquid flow rate adjustment device 300 Electrolytic Units 301 Inlet for bicarbonate-containing aqueous solution 302 Anode gas outlet 303 Hydrogen gas outlet 304 Recycled alkaline solution outlet 310 buffer tank 311 External water inlet 320 1st cooling device 330 Second cooling device 340 Gas-liquid separation equipment 350 Compressor 360 Drying dehydration equipment 400 Carbon Dioxide Separator 401 Anode gas inlet 402 Liquid Carbon Dioxide Outlet 403 Crude oxygen outlet 500 carbon dioxide detection device.

Claims

1. A method for collecting and purifying carbon dioxide, including carbon dioxide collection, electrolysis, and carbon dioxide separation, The process involves using an alkaline solution to perform a carbon dioxide capture process on the target component to obtain an aqueous solution containing carbonate, A step of 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 volume content of carbon dioxide in the carbon dioxide-containing crude oxygen is 9.7 to 35.9 vol%. The steps include electrolyzing the aforementioned bicarbonate-containing aqueous solution to obtain an anode gas, hydrogen gas, and a regenerated alkaline solution, The process includes the step of performing the 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 to 99.9999 vol%, and the carbon dioxide content in the carbon dioxide-containing crude oxygen accounts for 5 to 40% of the carbon dioxide content in the anode gas. 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, 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. A method for capturing and purifying carbon dioxide, characterized by the following features.

2. The carbon dioxide separation process is carried out in a carbon dioxide separation apparatus, with an operating pressure of 10 to 60 bar, a molar reflux ratio of (1.4 to 4):1, and a molar ratio of the top gas phase sample to the raw material of (0.25 to 0.45):

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

3. The temperature during the electrolysis process is 50 to 200°C, the electrolytic cell voltage is 1.1 to 4V, and the current density is 500 to 8000 A / m². ２ In the aforementioned aqueous solution containing bicarbonate, 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 to 1):

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

4. Before carrying out the carbon dioxide separation process, the carbon dioxide collection and purification method is as follows: The process further includes sequentially performing cooling, gas-liquid separation, compression, and drying / dehydration on the anode gas, The method for capturing and purifying carbon dioxide according to feature 1.

5. After the cooling process described above, the temperature of the anode gas decreases to 5-50°C. The method for capturing and purifying carbon dioxide according to feature 4.

6. Between the compression process and the carbon dioxide separation process, the carbon dioxide collection and purification method is: The step further includes a step of exchanging heat between the anode gas that has undergone the compression process and the carbon dioxide-containing crude oxygen. The method for capturing and purifying carbon dioxide according to feature 4.

7. 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. The method for capturing and purifying carbon dioxide according to feature 1.

8. The aforementioned method of carbon dioxide collection and purification is The further step includes returning at least a portion of the bicarbonate-containing aqueous solution to the carbon dioxide capture process for reuse, and / or returning at least a portion of the regenerated alkaline solution to the carbon dioxide capture process for reuse. The method for capturing and purifying carbon dioxide according to feature 1.

9. A carbon dioxide capture and purification system, It includes a carbon dioxide collection 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 collection device (100) is equipped with an alkaline solution inlet (101), a target component inlet (102), and a carbonate-containing aqueous solution outlet (103). The oxygen gas purification apparatus (200) is equipped 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 connected to each other. The electrolysis unit (300) is equipped 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 aqueous solution outlet (203) are connected by a bicarbonate aqueous solution transport pipeline. The carbon dioxide separator (400) is equipped 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 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). 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) opens. The carbon dioxide collection device (100) is equipped with a recirculation port (104) that communicates with the regenerated alkaline liquid outlet (304). The return port (104) and the regenerated alkaline liquid outlet (304) are connected by a regenerated alkaline liquid transport pipeline, and a buffer tank (310) is installed in the regenerated alkaline liquid transport pipeline. The buffer tank (310) is provided with an external water inlet (311) for adjusting the concentration of the regenerated alkaline solution in the buffer tank (310). A system for capturing and purifying carbon dioxide.

10. The reflux port (104) is further connected to the outlet (203) of the bicarbonate-containing aqueous solution. The carbon dioxide capture and purification system according to feature 9.

11. A first cooling device (320) is further installed in the regenerated alkaline liquid transport pipeline, and in the regenerated alkaline liquid transport pipeline, the buffer tank (310) and the first cooling device (320) are sequentially installed along the material flow direction. The carbon dioxide capture and purification system according to feature 10.

12. The carbon dioxide collection and purification system further includes a second cooling device (330), a gas-liquid separator (340), a compressor (350), and a drying and dewatering device (360) which are sequentially installed in the anode gas transport pipeline along the material flow direction in the anode gas transport pipeline. The carbon dioxide capture and purification system according to feature 9.

13. The carbon dioxide collection and purification system further includes a heat exchanger, which is installed in the anode gas transport pipeline between the compressor (350) and the carbon dioxide separation device (400) and is used to exchange heat between the anode gas and crude oxygen. The carbon dioxide capture and purification system according to feature 12.

14. The carbon dioxide collection and purification system further includes a bottom liquid flow rate regulator (210) installed in the bicarbonate aqueous solution transport pipeline. The carbon dioxide capture and purification system according to feature 9.

15. The compressor (350) includes 2 to 8 stages of compressors, and a third cooling device and a liquid separator are installed between each stage of the compressors. The carbon dioxide capture and purification system according to feature 12.

16. A condenser and a reboiler are further installed inside the carbon dioxide separation apparatus (400) to adjust the carbon dioxide content in the crude oxygen transport pipeline. The carbon dioxide capture and purification system according to feature 9.

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