Integrated system for carbon dioxide capture coupled with hydrogen production by electrolysis

Abstract

The utility model discloses a carbon dioxide capture coupling hydrogen production electrolysis regeneration integrated system, including the absorption unit, electrolysis regeneration unit and gas processing unit of connection in proper order through pipeline. The absorption unit is used to provide alkali absorption carbon dioxide and forms absorption rich liquid, the electrolysis regeneration unit carries out electrolysis and low temperature pyrolysis coupling regeneration to rich liquid through grading electrolytic cell and chemical decomposer, and hydrogen, carbon dioxide and oxygen are precipitated simultaneously, the gas processing unit carries out separation and purification to each gas. This carbon dioxide capture coupling hydrogen production electrolysis regeneration integrated system can realize the operation of low energy consumption, high efficiency, can also produce high purity hydrogen, oxygen and carbon dioxide in cooperation, and the economic benefit and energy efficiency of carbon dioxide capture are improved obviously.

Description

Technical Field

[0001] This utility model relates to the field of environmental protection and new energy equipment, specifically to an integrated system for carbon dioxide capture coupled with hydrogen production, electrolysis and regeneration. Background Technology

[0002] With the increasing severity of global climate change, controlling atmospheric carbon dioxide concentration has become a key task in achieving carbon neutrality. Carbon dioxide capture, utilization, and storage (CCUS) technology, as an important means of reducing carbon emissions, is of great significance, especially in the energy and industrial sectors. Direct air capture (DAC) technology, due to its independence from emission sources, has attracted increasing attention.

[0003] Currently, the mainstream direct air capture technologies mainly employ two approaches: solid-state amine adsorption and liquid alkaline solution absorption. While solid-state amine adsorption can effectively capture carbon dioxide, it requires high-temperature steam for desorption and regeneration, resulting in high energy consumption and potential additional carbon emissions. Liquid alkaline solution absorption typically relies on complex processes such as high-temperature calcination for absorbent regeneration, leading to significant equipment investment. Furthermore, the calcination process itself generates carbon dioxide, weakening the overall emission reduction effect.

[0004] Furthermore, existing carbon dioxide capture technologies are mostly designed solely for carbon dioxide capture, with relatively simple process flows that fail to effectively utilize potential byproducts generated during the capture process, resulting in poor system economics. Meanwhile, water electrolysis for hydrogen production, an important method for obtaining green hydrogen, is primarily constrained by electricity prices, and has not yet achieved large-scale widespread application. Utility Model Content

[0005] In view of the shortcomings of the existing technology, the technical problem to be solved by this utility model is to provide an integrated system for carbon dioxide capture coupled with hydrogen production, electrolysis and regeneration, which can achieve low energy consumption and high efficiency operation, and can also synergistically produce high-purity hydrogen, oxygen and carbon dioxide, significantly improving the economic benefits and energy efficiency of carbon dioxide capture.

[0006] To achieve the above objectives, this utility model is implemented through the following technical solution: an integrated system for carbon dioxide capture coupled with hydrogen production, electrolysis and regeneration, comprising an absorption unit, an electrolysis and regeneration unit and a gas processing unit connected sequentially by pipelines; The absorption unit is used to provide alkaline solution to absorb carbon dioxide and form an absorption-rich solution. The electrolytic regeneration unit is used to receive the absorbent solution discharged from the absorption unit and regenerate the alkaline solution through a coupled electrochemical and thermochemical decomposition process, simultaneously releasing hydrogen, carbon dioxide, and oxygen. A gas processing unit is used to separate and purify hydrogen, carbon dioxide and oxygen discharged from the electrolytic regeneration unit.

[0007] Furthermore, the absorption unit includes an absorption tower, which has an air inlet at the bottom and a purified air outlet at the top. An alkaline solution spraying system is installed at the top of the absorption tower and a rich solution tank is installed at the bottom. A circulating pump is connected between the rich solution tank and the spraying system. The alkaline solution spraying system and the rich solution tank are filled with packing material.

[0008] Furthermore, the absorption unit also includes a fan, which is installed inside the absorption tower to create negative pressure inside the absorption tower and guide air to flow towards the top of the absorption tower.

[0009] Furthermore, the electrolytic regeneration unit includes a staged electrolytic cell and a chemical decomposer. The inlet of the staged electrolytic cell is connected to the rich solution tank. The cathode chamber of the staged electrolytic cell can generate hydrogen gas through an electrochemical reaction. The anode chamber of the staged electrolytic cell can release carbon dioxide gas and oxygen gas through an electrochemical reaction. The inlet of the chemical decomposer is connected to the anode outlet of the staged electrolytic cell and can regenerate the alkaline solution while decomposing the liquid discharged from the anode outlet of the staged electrolytic cell to generate carbon dioxide gas. The alkaline solution is returned to the rich solution tank through a pipeline.

[0010] Furthermore, the electrolytic regeneration unit also includes a pretreatment purification device, the inlet of which is connected to the rich liquid tank via a transfer pump; the graded electrolytic cell is connected to the outlet of the pretreatment purification device, and the pretreatment purification device is used to remove dust, microorganisms and metal ions from the raw materials entering the pretreatment purification device.

[0011] Furthermore, the chemical decomposer is equipped with a temperature control heating device for controlling the temperature inside the chemical decomposer.

[0012] Furthermore, the gas processing unit includes a hydrogen purification device, a carbon dioxide purification device, and a carbon dioxide / oxygen separation device. The inlet of the hydrogen purification device is connected to the cathode outlet of the staged electrolyzer; the inlet of the carbon dioxide / oxygen separation device is connected to the anode outlet of the staged electrolyzer; and the inlet of the carbon dioxide purification device is connected to the outlet of the chemical decomposer.

[0013] Furthermore, it also includes a gas-liquid separator for gas-liquid separation. The gas outlet of the gas-liquid separator is connected in sequence to a demister and a carbon dioxide / oxygen separator via a pipeline. The liquid outlet of the gas-liquid separator is connected to the inlet of the chemical decomposer. The demister is used to remove liquid droplets entrained in the mixed gas flowing to the carbon dioxide / oxygen separator.

[0014] Furthermore, the hydrogen purification device also includes a buffer tank for stabilizing the hydrogen flow entering the hydrogen purification device.

[0015] Furthermore, the system also includes a regenerated alkali reflux pipe, which is connected between the outlet of the chemical decomposer and the alkaline solution spraying system of the absorption tower.

[0016] The beneficial effects of this utility model are: The aforementioned integrated system for carbon dioxide capture coupled with hydrogen production, electrolysis, and regeneration has at least the following advantages: 1. This system converts captured carbon dioxide into pure carbon dioxide products and couples them with the production of high-value hydrogen, transforming the burden of simple "emission reduction" into the benefit of "resource utilization". The high-purity hydrogen produced can be used as green energy or chemical raw material, greatly improving the economic efficiency of the process.

[0017] 2. This system tightly connects the three units through pipelines, and the reuse of the regenerated alkali solution forms a complete closed-loop material cycle of "absorption-regeneration-reuse". The absorbent is efficiently recycled and regenerated within the system, greatly reducing the consumption of fresh chemicals and the discharge of waste liquid. When the system is driven by renewable energy, the entire process not only achieves continuous carbon dioxide capture but also produces carbon-free green hydrogen, forming a truly synergistic system of "negative carbon emissions" and "green energy production".

[0018] 3. This system integrates carbon capture and hydrogen production into a compact and coherent device, which simplifies the process flow, reduces the equipment footprint, and lowers the complexity of initial investment and operation and maintenance. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of this utility model, the accompanying drawings used in the specific embodiments will be briefly described below. In all the drawings, the elements or parts are not necessarily drawn to scale.

[0020] Figure 1 A schematic diagram of an integrated carbon dioxide capture coupled with hydrogen production, electrolysis and regeneration system provided in an embodiment of this utility model; Figure 2 for Figure 1 The diagram shows a staged electrolyzer in an integrated system for carbon dioxide capture, coupled with hydrogen production, electrolysis, and regeneration. Figure label: 1. Absorption tower; 2. Fan; 3. Packing material; 4. Alkaline solution spraying system; 5. Rich solution tank; 6. Circulating pump; 7. Transfer pump; 8. Pretreatment purification device; 9. Staged electrolytic cell; 901. Anode chamber; 902. Cathode chamber; 903. Anode plate; 904. Cathode plate; 905. Ion exchange membrane; 10. Chemical decomposer; 1001. Heating jacket; 11. Carbon dioxide / oxygen separation device; 12. Hydrogen purification device; 13. Carbon dioxide purification device; 14. Hydrogen outlet; 15. Carbon dioxide outlet; 16. Oxygen outlet; 17. Regenerated alkali solution return pipe; 18. Air inlet; 19. Purified air outlet; 20. Buffer tank; 21. Deoxygenation column; 22. Dryer; 23. Rectifier and voltage regulator module; 24. Gas-liquid separator; 25. Demister. Detailed Implementation

[0021] To make the above-mentioned objectives, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0022] Please see Figures 1 to 2 The present invention provides an integrated system for carbon dioxide capture coupled with hydrogen production and electrolytic regeneration, comprising an absorption unit, an electrolytic regeneration unit, and a gas treatment unit connected sequentially by pipelines. The absorption unit provides an alkaline solution and captures carbon dioxide from air or low-concentration flue gas to form a rich absorbent solution. The electrolytic regeneration unit receives the rich absorbent solution and regenerates the absorbent through a coupling of electrochemical and thermochemical decomposition, simultaneously releasing hydrogen, carbon dioxide, and oxygen. The gas treatment unit separates and purifies the generated gas to obtain a high-purity product gas.

[0023] In operation, in the absorption unit, the alkaline solution reacts with carbon dioxide to produce carbonates. In the electrolytic regeneration unit, the rich absorbent solution first undergoes electrochemical decomposition in the staged electrolytic cell 9. The cathode chamber 902 of the staged electrolytic cell 9 produces hydrogen and hydroxide ions, while the anode chamber 901 produces carbon dioxide, oxygen, and bicarbonate. Subsequently, the bicarbonate solution enters the chemical decomposer 10 for thermal decomposition, releasing carbon dioxide and regenerating the alkaline solution. The gas treatment unit then separates and purifies various gaseous products using physical or chemical methods. The entire system forms a continuous closed loop, achieving synergistic carbon dioxide capture and hydrogen production.

[0024] This system integrates multiple processes such as carbon dioxide capture, absorbent regeneration, and hydrogen production into one system through integrated design, which significantly reduces the energy consumption of traditional high-temperature regeneration processes; at the same time, the system has a compact structure and is suitable for treating low-concentration carbon dioxide sources (such as air or industrial exhaust gas).

[0025] In this embodiment, the absorption unit includes an absorption tower 1, with an air inlet 18 at the bottom and a purified air outlet 19 at the top. An alkaline solution spraying system 4 is installed at the top of the tower, and a rich solution tank 5 is located at the bottom. A circulating pump 6 is connected between the rich solution tank 5 and the spraying system. The space between the alkaline solution spraying system 4 and the rich solution tank 5 is filled with packing material 3 to enhance gas-liquid contact. The packing material 3 can be one or more of polypropylene Pall rings, stainless steel wire mesh, or plastic corrugated plates.

[0026] During operation, air enters from the bottom inlet of the tower and flows upward; the alkaline solution is sprayed downward through the spray system, coming into counter-current contact with the air and absorbing the carbon dioxide to form carbonate: 2NaOH + CO2 → Na2CO3 + H2O. The purified air is discharged from the top outlet of the tower, while the rich absorbent solution is collected in the rich solution tank 5. The circulating pump 6 continuously pumps the rich solution to the spray system, realizing the recycling of the absorbent solution and ensuring efficient collection.

[0027] This approach, combined with the reversible flow operation and the packing 3 structure, significantly improves carbon dioxide absorption efficiency; the circulating pump 6 ensures continuous solution flow and stable system operation; the overall structure is simple, easy to maintain, and suitable for long-term capture of low-concentration carbon dioxide.

[0028] In practical implementation, a fan 2 can be installed on the inner wall of the ventilation absorption tower 1. The fan 2 draws air in at a constant flow rate into the absorption tower 1, ensuring uniform airflow distribution within the tower. Specifically, the fan 2 can be installed near the purified air outlet 19 to create a negative pressure environment, guiding the air in from the inlet and through the packing layer 3, ensuring full contact with the spray liquid before discharge.

[0029] In this embodiment, the electrolytic regeneration unit includes a staged electrolytic cell 9 and a chemical decomposer 10. The inlet of the staged electrolytic cell 9 is connected to the rich solution tank 5 of the absorption unit. Inside, it is divided into an anode chamber 901 and a cathode chamber 902 by an anode plate 903, a cathode plate 904, and an ion exchange membrane 905. The anode chamber 901 produces carbon dioxide and oxygen through an electrochemical reaction, while the cathode chamber 902 produces hydrogen through an electrochemical reaction. The inlet of the chemical decomposer 10 is connected to the anode outlet of the staged electrolytic cell 9. It is used to decompose bicarbonate in the anolyte to produce carbon dioxide gas while regenerating the alkaline solution. The alkaline solution is returned to the rich solution tank 5 through a pipeline.

[0030] In this embodiment, the anode plate 903 of the graded electrolytic cell 9 is preferably a titanium-coated ruthenium-iridium anode, and the cathode plate 904 is preferably a nickel-plated steel plate; the ion exchange membrane 905 is a perfluorosulfonic acid proton exchange membrane or anion exchange membrane 905.

[0031] The specific working process of the electrolytic regeneration unit is as follows: In cathode chamber 902: Water molecules gain electrons and are reduced to produce hydrogen gas and hydroxide ions. , ; In anode chamber 901: carbonate ions are oxidized to produce carbon dioxide and oxygen, and release electrons. ; Meanwhile, some With hydrolysis Combined to form A mixed solution containing NaHCO3 and a small amount of Na2CO3 discharged from the anode chamber 901 enters the chemical decomposer 10, where a decomposition reaction occurs under heating conditions. 2NaHCO3 → Na2CO3 + CO2↑ + H2O, The CO2 gas produced by decomposition is discharged from the top.

[0032] This method achieves efficient regeneration of the absorbent through electrolysis and pyrolysis coupling, avoiding the high energy consumption problem of traditional high-temperature processes; the design of the staged electrolytic cell 9 allows hydrogen, carbon dioxide and oxygen to be released in different chambers, reducing gas cross-contamination and improving product purity.

[0033] In practical implementation, the electrolytic regeneration unit also includes a pretreatment purification device 8. The inlet of the pretreatment purification device 8 is connected to the rich liquor tank 5 via a transfer pump 7, and the outlet is connected to the staged electrolytic cell 9. The pretreatment purification device 8 is used to remove dust, microorganisms, and metal ions from the raw materials entering it.

[0034] Specifically, the pretreatment purification device 8 typically includes a precision filter and ion exchange resin. After the rich solution is pumped in by the transfer pump 7, it first passes through the filter to remove suspended solids and microorganisms, and then passes through the ion exchange resin to adsorb metal ions such as calcium and magnesium, preventing these impurities from forming scale or poisoning the electrodes in the electrolytic cell. Pretreatment purification ensures the long-term stable operation of the electrolytic cell, extends the service life of the electrodes and ion exchange membrane 905, improves electrolysis efficiency, reduces maintenance frequency, and thus ensures the purity of the product gas.

[0035] In practical implementation, a temperature-controlled heating device, such as an electric heating jacket or a hot water jacket, can be added to the outer wall of the chemical decomposer 10, with its operating temperature controlled between 60℃ and 95℃. The temperature-controlled heating device heats the solution inside the chemical decomposer 10 through an external heat source, causing sodium bicarbonate to rapidly decompose into sodium carbonate, carbon dioxide, and water at a suitable temperature (e.g., 80℃). The temperature sensor is linked to the control system to ensure that the temperature remains stable within the set range.

[0036] In this embodiment, the gas processing unit includes a hydrogen purification device 12, a carbon dioxide purification device 13, and a carbon dioxide / oxygen separation device 11. The inlet of the hydrogen purification device 12 is connected to the cathode outlet of the staged electrolyzer 9 to process wet hydrogen. The inlet of the carbon dioxide / oxygen separation device 11 is connected to the anode outlet of the staged electrolyzer 9 to separate a CO2 / O2 mixture. The inlet of the carbon dioxide purification device 13 is connected to the outlet of the chemical decomposer 10 to process and purify the carbon dioxide produced by pyrolysis.

[0037] In a preferred embodiment, the device may further include a gas-liquid separator 24. The gas-liquid separator 24 is used for gas-liquid separation. The gas outlet of the gas-liquid separator 24 is connected in sequence to a demister 25 and a carbon dioxide / oxygen separator 11 via pipelines. The liquid outlet of the gas-liquid separator 24 is connected to the inlet of the chemical decomposer 10. The demister 25 is used to remove liquid droplets entrained in the mixed gas flowing to the carbon dioxide / oxygen separator 11. In use, the liquid discharged from the anode chamber 901 is a mixed solution containing NaHCO3 and a small amount of Na2CO3. This gas-liquid mixture first enters the gas-liquid separator 24 for separation. The separated gas (mainly CO2 and O2) enters the demister 25 to remove entrained liquid droplets, and then flows to the carbon dioxide / oxygen separator 11 for processing; the separated liquid (mainly NaHCO3 solution) enters the chemical decomposer 10, and the separated oxygen and carbon dioxide gases are discharged from the oxygen outlet 16 and carbon dioxide outlet 15, respectively.

[0038] As another preferred embodiment, the hydrogen purification device 12 further includes a buffer tank 20, which is used to stabilize the hydrogen flow entering the hydrogen purification device 12.

[0039] Additionally, the hydrogen purification device 12 also includes a deoxygenation column 21 and a dryer 22. The deoxygenation column 21 is used to remove trace amounts of oxygen from the hydrogen, and the dryer 22 is used to remove moisture from the hydrogen. The deoxygenation column 21 is filled with a catalyst to remove trace amounts of oxygen from the hydrogen; the dryer 22 uses an adsorbent (such as a molecular sieve) to remove moisture, thereby obtaining high-purity hydrogen (purity >99.99%), which is collected from the hydrogen outlet 14 and can be used as an energy source or chemical feedstock.

[0040] The specific work process is as follows: The wet hydrogen gas evolved from the cathode chamber 902 enters the hydrogen purification device 12, and is processed by the buffer tank 20, the deoxygenation column 21 and the dryer 22 to obtain high-purity hydrogen gas through buffering, deoxygenation, dehydration and impurity removal. The carbon dioxide and oxygen mixture precipitated from the anode chamber 901 first enters the gas-liquid separator 24 for separation. The separated gas (mainly CO2 and O2) enters the demister 25 to remove entrained droplets, and then flows to the carbon dioxide / oxygen separator 11 for further processing. The liquid separated by the gas-liquid separator 24 (mainly NaHCO3 solution) enters the chemical decomposer 10, and the carbon dioxide released by the chemical decomposer 10 enters the carbon dioxide purification device 13 to remove moisture and impurities.

[0041] This gas processing unit, through the coordinated operation of multiple devices, ensures the efficient separation and high-purity production of hydrogen, carbon dioxide, and oxygen; the produced gas products can be directly used in the energy or chemical industries, improving the system's economic efficiency.

[0042] In specific implementation, the hydrogen purification device 12 can preferably be a palladium membrane purifier or a catalytic deoxygenator combined with a dryer 22. The palladium membrane purifier utilizes the selective permeation characteristics of palladium alloy for hydrogen to achieve hydrogen purification; the catalytic deoxygenator removes oxygen through a chemical reaction, and the dryer 22 removes moisture. The carbon dioxide / oxygen separation device 11 can preferably be a pressure swing adsorption tower or a membrane separator. The pressure swing adsorption tower separates gases based on the difference in the adsorption capacity of the adsorbent at different pressures; the membrane separator separates gases based on the different permeation rates of the gas in the membrane.

[0043] In another preferred embodiment, the system further includes a regenerated alkali return pipe 17. The regenerated alkali return pipe 17 connects the outlet of the chemical decomposer 10 to the alkaline solution spraying system 4 of the absorption tower 1. The alkaline solution (mainly containing NaOH and Na2CO3) regenerated by the chemical decomposer 10 returns to the spraying system of the absorption tower 1 through the return pipe, and is reused for carbon dioxide capture, forming a complete material cycle. The regenerated alkali return pipe 17 realizes the recycling of the absorbent, significantly reducing the consumption of chemical reagents and waste liquid discharge.

[0044] In addition, as a preferred embodiment, the system may also include a rectifier and voltage regulator module 23. The rectifier and voltage regulator module 23 is electrically connected to the staged electrolyzer 9 and is used to convert externally input unstable DC or AC power into stable DC power to supply the electrolysis process. Specifically, the input interface of the rectifier and voltage regulator module 23 is connected to renewable energy power generation equipment, including photovoltaic power generation modules and / or wind power generation modules, to achieve green energy drive for the system.

[0045] The system connects to external renewable energy sources, such as photovoltaic or wind power modules, via a rectifier and voltage regulator module 23. The rectifier and voltage regulator module 23 converts the unstable DC or AC power generated by renewable energy into stable DC power, supplying it to the staged electrolyzer 9 to ensure efficient and stable electrolysis. This design not only reduces operating costs but also achieves zero-carbon emission operation of the system.

[0046] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model, and they should all be covered within the scope of the claims and specification of this utility model.

Claims

1. An integrated system for carbon dioxide capture coupled with hydrogen production, electrolysis, and regeneration, characterized in that, It includes an absorption unit, an electrolytic regeneration unit, and a gas processing unit connected sequentially by pipelines; The absorption unit is used to provide alkaline solution to absorb carbon dioxide and form an absorption-rich solution; The electrolytic regeneration unit is used to receive the absorbent liquid discharged from the absorption unit and regenerate the alkaline solution through a coupling of electrochemical decomposition and thermochemical decomposition, while simultaneously releasing hydrogen, carbon dioxide and oxygen. and A gas processing unit is used to separate and purify hydrogen, carbon dioxide and oxygen discharged from the electrolytic regeneration unit.

2. The system according to claim 1, characterized in that, The absorption unit includes an absorption tower, which has an air inlet at the bottom and a purified air outlet at the top. An alkaline solution spraying system is installed at the top of the absorption tower and a rich solution tank is installed at the bottom. A circulating pump is connected between the rich solution tank and the spraying system. The alkaline solution spraying system and the rich solution tank are filled with packing material.

3. The system according to claim 2, characterized in that, The absorption unit also includes a fan, which is installed inside the absorption tower to create negative pressure inside the absorption tower and guide air to flow towards the top of the absorption tower.

4. The system according to claim 2, characterized in that, The electrolytic regeneration unit includes a staged electrolytic cell and a chemical decomposer. The inlet of the staged electrolytic cell is connected to the rich liquid tank. The cathode chamber of the staged electrolytic cell can generate hydrogen gas through an electrochemical reaction. The anode chamber of the staged electrolytic cell can release carbon dioxide gas and oxygen gas through an electrochemical reaction. The inlet of the chemical decomposer is connected to the anode outlet of the staged electrolytic cell and can regenerate the alkaline solution while decomposing the liquid discharged from the anode outlet of the staged electrolytic cell to generate carbon dioxide gas. The alkaline solution is returned to the rich liquid tank through a pipeline.

5. The system according to claim 4, characterized in that, The electrolytic regeneration unit also includes a pretreatment purification device, the inlet of which is connected to the rich liquid tank via a transfer pump; the graded electrolytic cell is connected to the outlet of the pretreatment purification device, and the pretreatment purification device is used to remove dust, microorganisms and metal ions from the raw materials entering the pretreatment purification device.

6. The system according to claim 4, characterized in that, The chemical decomposer is equipped with a temperature control heating device to control the temperature inside the chemical decomposer.

7. The system according to claim 4, characterized in that, The gas processing unit includes a hydrogen purification device, a carbon dioxide purification device, and a carbon dioxide / oxygen separation device. The inlet of the hydrogen purification device is connected to the cathode outlet of the staged electrolyzer; the inlet of the carbon dioxide / oxygen separation device is connected to the anode outlet of the staged electrolyzer; and the inlet of the carbon dioxide purification device is connected to the outlet of the chemical decomposer.

8. The system according to claim 7, characterized in that, It also includes a gas-liquid separator, which is used for gas-liquid separation. The gas outlet of the gas-liquid separator is connected in sequence to a demister and a carbon dioxide / oxygen separation device via a pipeline. The liquid outlet of the gas-liquid separator is connected to the inlet of the chemical decomposer. The demister is used to remove liquid droplets entrained in the mixed gas flowing to the carbon dioxide / oxygen separation device.

9. The system according to claim 7, characterized in that, The hydrogen purification device also includes a buffer tank, which is used to stabilize the hydrogen flow entering the hydrogen purification device.

10. The system according to claim 4, characterized in that, The system also includes a regenerated alkali return pipe, which is connected between the outlet of the chemical decomposer and the alkaline solution spraying system of the absorption tower.

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