An electrochemical carbon dioxide capture system and method coupled with high purity hydrogen production

Abstract

The application provides an electrochemical carbon dioxide capture system and method coupled with high-purity hydrogen production. The system absorbs carbon dioxide in flue gas through an absorption device, and the obtained absorption liquid enters an anode chamber to obtain a gas-liquid mixture containing carbon dioxide. The gas-liquid mixture enters a first gas-liquid separation device for separation to obtain carbon dioxide and a first separation liquid. The first separation liquid enters an intermediate chamber, and under the action of ion exchange, the absorption of the absorption agent is regenerated. The regenerated absorption agent returns to the absorption device to continue the absorption of carbon dioxide. The absorption and capture process of carbon dioxide in flue gas is coupled with the electrolytic hydrogen production process. Carbon dioxide is captured while hydrogen is collected, which improves energy efficiency, saves energy consumption, saves operation cost, and meets the green environmental protection concept. The purification and collection of hydrogen are carried out separately in a cathode chamber and do not participate in carbon dioxide capture, which can avoid the risk of explosion caused by the mixing of hydrogen and absorption liquid and entering the anode chamber to mix with oxygen, thereby increasing safety.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gas purification and separation, and particularly relates to an electrochemical carbon dioxide capture system and method coupled with high-purity hydrogen production. BACKGROUND

[0002] Carbon dioxide (CO2) is the main greenhouse gas causing global climate warming, and the capture, utilization and storage of CO2 have become one of the hot topics of international concern. The CO2 emission from coal-fired power generation accounts for about 50% of the total industrial emission, and the capture and separation of CO2 in flue gas of coal-fired power plants is an important field of greenhouse gas emission reduction. In addition, there are also a large number of CO2 capture or separation processes in the fields of steelmaking, cement, chemical industry (such as synthetic ammonia, hydrogen production, natural gas purification) and the like. The main methods for capturing CO2 include absorption method, adsorption method, membrane separation, low-temperature separation and the like, among which the absorption method is the most mature and promising CO2 capture and separation technology for large-scale commercial application.

[0003] The existing CO2 absorption method for capture and separation has high energy consumption and operating cost in the application process, especially the steam heat energy consumed for regenerating the absorbent accounts for a large proportion of the entire system energy consumption, which does not conform to the concept of green environmental protection. In addition, in the electrolysis regeneration link, the consumed electric energy is only used for regenerating the absorbent, and the energy utilization efficiency is low.

[0004] While capturing and separating carbon dioxide, oxygen and hydrogen are produced, among which hydrogen is also a target gas, but the existing CO2 absorption method for capture and separation does not purify and collect the produced hydrogen, which wastes resources. Moreover, after mixing with the circulating solution, the produced hydrogen is mixed with oxygen in the anode chamber, which is prone to explosion risk, and there is a safety hazard.

[0005] In view of the above problems, it is necessary to provide an electrochemical carbon dioxide capture system and method coupled with high-purity hydrogen production which is reasonable in design and effectively solves the above problems. SUMMARY

[0006] The present application aims to at least solve one of the technical problems existing in the prior art, and provides an electrochemical carbon dioxide capture system and method coupled with high-purity hydrogen production.

[0007] One aspect of the present application provides an electrochemical carbon dioxide capture system coupled with high-purity hydrogen production, comprising an absorption device, an electrolytic hydrogen production device, a first gas-liquid separation device and a second gas-liquid separation device.

[0008] The absorption device is provided with an absorbent therein for absorbing carbon dioxide, the electrolytic hydrogen production device comprises an anode chamber, an intermediate chamber and a cathode chamber which are arranged by being separated by an anion exchange membrane, wherein the anode chamber adopts an oxygen evolution electrode, and the cathode chamber adopts a hydrogen evolution electrode.

[0009] The first inlet of the absorption device is used to communicate with the flue gas containing carbon dioxide, the first outlet of the absorption device is communicated with the inlet of the anode chamber through the absorption liquid pipeline, the outlet of the anode chamber is communicated with the inlet of the first gas-liquid separation device through the gas-liquid mixture pipeline, the first outlet of the first gas-liquid separation device is communicated with the inlet of the intermediate chamber through the first separation liquid pipeline, and the outlet of the intermediate chamber is communicated with the second inlet of the absorption device through the absorbent pipeline, so as to realize the regeneration cycle of the absorbent.

[0010] The inlet of the second gas-liquid separation device is communicated with the outlet of the cathode chamber through the hydrogen-containing solution pipeline, the first outlet of the second gas-liquid separation device is communicated with the inlet of the cathode chamber through the second separation liquid pipeline, and the second outlet of the second gas-liquid separation device is communicated through the first exhaust pipeline, so as to realize the independent separation and discharge of hydrogen.

[0011] The second outlet of the first gas-liquid separation device is communicated with the second exhaust pipeline to discharge the separated carbon dioxide, and the second outlet of the absorption device is communicated with the purified gas pipeline to discharge the purified gas.

[0012] Optionally, the second gas-liquid separation device is a gas-liquid separator, which separates and purifies the hydrogen-containing solution to obtain purified hydrogen.

[0013] Optionally, the first gas-liquid separation device comprises a flash tank and a condenser.

[0014] The gas-liquid mixture inlet of the flash tank is communicated with the outlet of the anode chamber, the condensate gas inlet of the condenser is communicated with the condensate gas outlet of the flash tank, the condensate liquid inlet of the flash tank is communicated with the condensate liquid outlet of the condenser, and the inlet of the intermediate chamber is communicated with the separation liquid outlet of the flash tank.

[0015] The top of the condenser is communicated with the second exhaust pipeline to discharge the separated carbon dioxide.

[0016] Optionally, it further comprises a rinsing device.

[0017] The first inlet of the rinsing device is communicated with the second outlet of the absorption device through the purified gas pipeline.

[0018] The second inlet of the rinsing device is used to communicate with a rinsing water source.

[0019] The first outlet of the rinsing device is communicated with a gas discharge pipeline.

[0020] Optionally, it further comprises a desulfurization device.

[0021] The first inlet of the desulfurization device is used for communicating with flue gas containing carbon dioxide, and the first outlet of the desulfurization device communicates with the first inlet of the absorption device;

[0022] The second inlet of the desulfurization device communicates with the second outlet of the elution device;

[0023] The backflow outlet of the desulfurization device communicates with the backflow inlet of the elution device.

[0024] Optionally, the application further comprises a recovery device;

[0025] The inlet of the recovery device communicates with the backflow outlet of the desulfurization device, so that when the desulfurization liquid in the desulfurization device reaches saturation, the liquid substance in the desulfurization device is transported into the recovery device for treatment.

[0026] Optionally, the application further comprises a first heat exchange device;

[0027] The first heat exchange device respectively communicates with the elution device and the desulfurization device, and is used for heat exchange between the elution device and the desulfurization device.

[0028] Optionally, the application further comprises a second heat exchange device;

[0029] The second heat exchange device respectively communicates with the absorption device and the electrolysis device, and is used for heat exchange between the absorption device and the electrolysis device.

[0030] Optionally, the second heat exchange device comprises a cold end inlet, a cold end outlet, a hot end inlet and a hot end outlet;

[0031] The cold end inlet of the second heat exchange device communicates with the second outlet of the absorption device, the hot end outlet of the second heat exchange device communicates with the inlet of the anode chamber, the hot end inlet of the second heat exchange device communicates with the outlet of the intermediate chamber, and the cold end outlet of the second heat exchange device communicates with the second inlet of the absorption device.

[0032] Another aspect of the application provides an electrochemical carbon dioxide capture method coupled with high-purity hydrogen production, which adopts the electrochemical carbon dioxide capture system coupled with high-purity hydrogen production described above, and the method comprises:

[0033] Flue gas containing carbon dioxide is transported to the absorption device, and the carbon dioxide in the flue gas is absorbed by the absorbent in the absorption device to obtain absorption liquid and purified gas;

[0034] The absorption liquid is transported to the anode chamber of the electrolytic hydrogen production device, and a gas-liquid mixture containing carbon dioxide is obtained under the action of an oxygen evolution electrode;

[0035] The first gas-liquid separation device performs gas-liquid separation treatment on a gas-liquid mixture containing carbon dioxide to obtain carbon dioxide gas and a first separated liquid. The separated carbon dioxide is discharged and the separated liquid is transported to the intermediate chamber. The separated liquid in the intermediate chamber undergoes ion exchange through the anion exchange membrane to obtain an absorbent, thereby regenerating the absorbent. The regenerated absorbent is then transported to the absorption device to continue absorbing carbon dioxide.

[0036] The hydrogen-containing solution in the cathode chamber is transported to the first gas-liquid separation device to obtain hydrogen gas and a second separation liquid. The separated hydrogen gas is discharged through the first exhaust pipe and the second separation liquid is transported to the inlet of the cathode chamber to achieve independent separation and discharge of hydrogen gas.

[0037] The present invention relates to an electrochemical carbon dioxide capture system and method coupled with high-purity hydrogen production. The system couples the absorption and capture of carbon dioxide in flue gas with the electrolytic hydrogen production process. While capturing carbon dioxide, hydrogen is purified and collected simultaneously, improving energy efficiency, saving energy consumption, and reducing operating costs, thus aligning with the concept of green environmental protection. The purification and collection of hydrogen is carried out separately in the cathode chamber and does not participate in the carbon dioxide capture system. This avoids the risk of explosion caused by hydrogen mixing with the absorbent and then entering the anode chamber where it mixes with oxygen, increasing the safety of both the carbon dioxide capture and hydrogen production processes. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of an electrochemical carbon dioxide capture system coupled with high-purity hydrogen preparation according to an embodiment of the present invention;

[0039] Figure 2 This is a schematic flowchart of an electrochemical carbon dioxide capture method coupled with high-purity hydrogen preparation in another embodiment of the present invention. Detailed Implementation

[0040] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] like Figure 1 As shown, one aspect of the present invention provides an electrochemical carbon dioxide capture system coupled with high-purity hydrogen production, including an absorption device 1, an electrolytic hydrogen production device 2, a first gas-liquid separation device 3, and a second gas-liquid separation device 4.

[0042] The absorption device 1 is provided with an absorbent for absorbing carbon dioxide, and the electrolytic hydrogen production device 2 comprises an anode chamber 21, an intermediate chamber 22 and a cathode chamber 23 which are arranged in separation by an anion exchange membrane 24, wherein the anode chamber 21 adopts an oxygen evolution electrode and can produce oxygen in the anode chamber 21, and the cathode chamber 23 adopts a hydrogen evolution electrode and can produce hydrogen in the cathode chamber 23.

[0043] It should be noted that the absorbent can be an ammonia-containing solution, but the type of absorbent is not limited to ammonia, and can also be organic amine, amino acid, etc., which can be selected according to actual needs. In this embodiment, the absorbent is taken as an example of an ammonia-containing solution.

[0044] It should be further noted that the oxygen evolution electrode can be, but is not limited to, a ruthenium oxide electrode, an iridium oxide electrode, a nickel-iron alloy electrode, a nickel-iron oxide electrode, etc. The hydrogen evolution electrode can be, but is not limited to, a platinum-carbon electrode, a platinum-ruthenium-carbon electrode, a nickel-molybdenum alloy electrode, a nickel-molybdenum oxide electrode, etc. The materials of the oxygen evolution electrode and the hydrogen evolution electrode are not limited in this embodiment, and can be selected according to actual needs.

[0045] The first inlet of the absorption device 1 is used for communicating with flue gas containing carbon dioxide, the first outlet of the absorption device 1 is connected to the inlet of the anode chamber 21 through an absorption liquid pipeline 51, the outlet of the anode chamber 21 is connected to the inlet of the first gas-liquid separation device 3 through a gas-liquid mixture pipeline 52, the first outlet of the first gas-liquid separation device 3 is connected to the inlet of the intermediate chamber 22 through a first separation liquid pipeline 53, and the outlet of the intermediate chamber 22 is connected to the second inlet of the absorption device 1 through an absorbent pipeline 54, so as to realize the regeneration and circulation of the absorbent.

[0046] Specifically, as shown in Figure 1 The flue gas containing carbon dioxide enters the absorption device 1 through the first inlet of the absorption device 1, and the absorbent in the absorption device 1 absorbs the carbon dioxide to obtain absorption liquid and purified gas. The absorption liquid is a high-carbon dioxide-loaded liquid obtained after the absorbent absorbs the carbon dioxide, and the purified gas is the gas obtained after the flue gas is removed of carbon dioxide.

[0047] The absorption liquid enters the anode chamber 21 through the absorption liquid pipeline 51, and the absorption liquid produces oxygen at the oxygen evolution electrode in the anode chamber 21. The reaction of the oxygen evolution electrode is: 4OH - -4e - =O 2 ↑+2H2O, and the reaction of the hydrogen evolution electrode is: 4H2O+4e - =2H2↑+4OH - OH -As the concentration decreases, the acidity of the reaction solution increases, and CO2 is released, resulting in a gas-liquid mixture containing carbon dioxide. The gas-liquid mixture containing carbon dioxide in the anode chamber 21 is transported to the first gas-liquid separator 3 via the gas-liquid mixture pipeline 52 for separation, yielding carbon dioxide gas and a first separated liquid. The first separated liquid enters the intermediate chamber 22 via the first separated liquid pipeline 53, where OH- is generated at the hydrogen evolution cathode. - The solution then passes through the anion exchange membrane 24 into the intermediate chamber 23. The alkalinity of the solution in the intermediate chamber 23 increases, resulting in the absorption of the absorbent, thus regenerating it. The regenerated absorbent then enters the absorption device 1 from the intermediate chamber 22 through the absorbent pipe 54, continuing to supply absorbent to the absorption device 1 and continuing the absorption of carbon dioxide.

[0048] like Figure 1 As shown, the inlet of the second gas-liquid separator 4 is connected to the outlet of the cathode chamber 23 through a hydrogen-containing solution pipe 55, the first outlet of the second gas-liquid separator 4 is connected to the inlet of the cathode chamber 23 through a second separation liquid pipe 56, and the second outlet of the second gas-liquid separator 4 is connected through a first exhaust pipe 57, so as to realize the independent separation and discharge of hydrogen.

[0049] In this embodiment, the second gas-liquid separation device 4 is a gas-liquid separator that separates and purifies the hydrogen-containing solution to obtain purified hydrogen. Specifically, the hydrogen-containing solution generated in the cathode chamber 23 is transported to the second gas-liquid separation device 4 through the hydrogen-containing solution pipeline 55. The second gas-liquid separation device 4 purifies and separates the hydrogen-containing solution to obtain hydrogen and a second separated liquid. The obtained hydrogen is discharged through the first exhaust pipeline 57 for further hydrogen collection. The obtained second separated liquid re-enters the cathode chamber 23 through the second gas-liquid separation device 4 for further hydrogen preparation and purification, achieving independent separation and discharge of hydrogen.

[0050] In this embodiment, the purification and collection of hydrogen is carried out separately in the cathode chamber and does not participate in the carbon dioxide capture system. This avoids the risk of hydrogen mixing with the absorbent and then entering the anode chamber to mix with oxygen, which could lead to an explosion. This increases the safety of the carbon dioxide capture and hydrogen production process.

[0051] The second outlet of the first gas-liquid separator 3 is connected to the second exhaust pipe 58 to discharge the separated carbon dioxide, and the second outlet of the absorption device 1 is connected to the purified gas pipe 59 to discharge the purified gas.

[0052] The coupling high-purity hydrogen preparation electrochemical carbon dioxide capture system of the application couples the absorption and capture process of carbon dioxide in flue gas with the process of electrolytic hydrogen production, and purifies and collects hydrogen while capturing carbon dioxide, thereby improving energy efficiency, saving energy consumption, saving operation cost, and meeting the concept of green environmental protection; the purification and collection of hydrogen are separately performed in the cathode chamber and do not participate in the carbon dioxide capture system, so that the risk of explosion of hydrogen mixed with the absorption liquid and mixed with oxygen in the anode chamber can be avoided, and the safety in the processes of carbon dioxide capture and hydrogen production is improved.

[0053] As shown in Figure 1 The first gas-liquid separation device 3 includes a flash tank 31 and a condenser 32. The gas-liquid mixture inlet of the flash tank 31 is connected with the outlet of the anode chamber 21, the condenser 32 is connected with the condensate gas outlet of the flash tank 31, the condensate liquid inlet of the flash tank 31 is connected with the condensate liquid outlet of the condenser 32, and the inlet of the intermediate chamber 22 is connected with the separation liquid outlet of the flash tank 31. The top of the condenser 32 is connected with the second exhaust pipeline 58 to exhaust the separated carbon dioxide. The first separation liquid is a mixture of the initial separation liquid and the condensate liquid, the initial separation liquid is the liquid substance obtained by flashing in the flash tank 31, and the condensate liquid is the liquid substance obtained by condensing in the condenser 32.

[0054] In this embodiment, the gas-liquid separation unit 3 includes a flash tank 31 and a condenser 32, and the gas-liquid mixture can be separated by the flash tank 31 and the condenser 32, thereby reducing the loss of ammonia and reducing the energy consumption of the whole system.

[0055] As shown in Figure 1 The coupling high-purity hydrogen preparation electrochemical carbon dioxide capture system of the application further includes a washing device 5. The first inlet of the washing device 5 is connected with the second outlet of the absorption device 1 through the purified gas pipeline 59. The second inlet of the washing device 5 is connected with a washing water source. The first outlet of the washing device 5 is connected with a gas exhaust pipeline.

[0056] Specifically, the purified gas generated in the absorption device 1 still contains ammonia, the purified gas containing ammonia is transmitted to the washing device 5 through the purified gas pipeline 59, the washing water source enters the washing device 5 through the second inlet to wash the purified gas containing ammonia, so as to separate and recover the residual ammonia, the separated ammonia exists in the form of ammonia-containing washing liquid, and the absorbent and the exhaust gas are obtained. The exhaust gas is exhausted through the gas exhaust pipeline 46.

[0057] As shown in Figure 1As shown, the electrochemical carbon dioxide capture system of the present invention, coupled with high-purity hydrogen production, includes a desulfurization unit 6. The first inlet of the desulfurization unit 6 is connected to the carbon dioxide-containing flue gas. The carbon dioxide-containing flue gas first enters the desulfurization unit 6 for pretreatment to obtain a desulfurized liquid.

[0058] The first outlet of the desulfurization unit 6 is connected to the first inlet of the absorption unit 1. The flue gas after desulfurization enters the absorption unit 1 for carbon dioxide absorption and capture.

[0059] The second inlet of the desulfurization unit 6 is connected to the second outlet of the scrubbing unit 5. The ammonia gas separated in the scrubbing unit 5 is transported from the scrubbing unit 5 to the desulfurization unit 6 in the form of an ammonia-containing scrubbing liquid.

[0060] The reflux outlet of desulfurization unit 6 is connected to the reflux inlet of scrubbing unit 5. The height of the reflux inlet is lower than the height of the second inlet.

[0061] Specifically, the separated ammonia combines with sulfur dioxide in the flue gas to exist in the form of desulfurization liquid. The desulfurization liquid that has not reached saturation is returned from the desulfurization unit 6 to the scrubbing unit 5 to scrub the purified gas, and is transported from the scrubbing unit 5 to the desulfurization unit 6 along with the separated ammonia-containing scrubbing liquid, forming a circulation loop.

[0062] It should be noted that the purified gas can be rinsed with circulating desulfurization liquid, or with externally replenished water. Alternatively, the purified gas can be rinsed with both desulfurization liquid and externally replenished water, depending on the actual needs.

[0063] For example, such as Figure 1 As shown, the electrochemical carbon dioxide capture system of the present invention, which is coupled with high-purity hydrogen production, also includes a recovery device 7. The inlet of the recovery device 7 is connected to the reflux outlet of the desulfurization device 6, so that when the desulfurization liquid in the desulfurization unit reaches saturation, the liquid substance in the desulfurization device 6 is transported to the recovery device 7 for processing.

[0064] Specifically, when the desulfurization liquid reaches saturation, the liquid substance in the desulfurization unit 6 can be transported to the recovery unit 7 for processing to obtain a byproduct of sulfur dioxide utilization, such as ammonium sulfate fertilizer. The recovery unit 7 enables the recycling and reuse of the desulfurization liquid, thus saving resources.

[0065] For example, such as Figure 1 As shown, the electrochemical carbon dioxide capture system of the present invention, which is coupled with high-purity hydrogen production, further includes a first heat exchange device 8, which is connected to the scrubbing device 5 and the desulfurization device 6 respectively, and is used for heat exchange between the scrubbing device 5 and the desulfurization device 6.

[0066] Specifically, the ammonia-containing rinse solution and the desulfurization solution can be heat-exchanged by the first heat-exchange device 8, and the heat-exchange of the ammonia-containing rinse solution and the desulfurization solution is performed by the first heat-exchange device 8 for transferring the heat of the desulfurization solution to the ammonia-containing rinse solution. In addition, after the heat-exchange, the ammonia-containing rinse solution can be further heated by the heating assembly during the transportation to the desulfurization device 6, so as to promote the desulfurization process in the desulfurization device 6; and after the heat-exchange, the desulfurization solution can be further cooled by the cooling assembly during the transportation to the rinse device 5.

[0067] In the embodiment, the first heat-exchange device improves the heat utilization rate of the whole system and saves energy consumption.

[0068] For example, as shown in Figure 1 The electrochemical carbon dioxide capture system coupled with the preparation of high-purity hydrogen gas further comprises a second heat-exchange device 9, which is connected with the absorption device 1 and the electrolytic hydrogen production device 2 respectively, and is used for heat-exchange between the absorption device 1 and the electrolytic hydrogen production device 2.

[0069] Specifically, the second heat-exchange device 9 comprises a cold end inlet, a cold end outlet, a hot end inlet and a hot end outlet. The cold end inlet of the second heat-exchange device 9 is connected with the second outlet of the absorption device 1, the hot end outlet of the second heat-exchange device 9 is connected with the inlet of the anode chamber 21, the hot end inlet of the second heat-exchange device 9 is connected with the outlet of the intermediate chamber 23, and the cold end outlet of the second heat-exchange device 9 is connected with the second inlet of the absorption device 1.

[0070] In the embodiment, the heat-exchange between the absorbent and the absorption solution is performed only by the second heat-exchange device 9, and the heat of the absorbent is transferred to the absorption solution, and the absorbent and the absorption solution are isolated from each other in the second heat-exchange device 9. The transportation channel between the cold end outlet of the second heat-exchange device 9 and the absorbent inlet of the absorption device 1 is used for transporting the absorbent to the absorption device 1, and a cooling assembly can be installed on the transportation channel; and the transportation channel between the hot end outlet of the second heat-exchange device 9 and the inlet of the anode chamber 21 is used for transporting the absorption solution to the anode chamber 21, and a heating assembly can be installed on the transportation channel.

[0071] For example, the absorption device comprises an absorption part, a condensation part and a separation plate separating the absorption part and the condensation part. The absorption part is located at the bottom of the absorption device, and the condensation part is located at the top of the absorption device. The separation plate allows gas to pass through and blocks liquid substances from passing through. The material of the separation plate can be PTFE film, and preferably, the material of the separation plate can be Teflon PTFE film.

[0072] The flue gas inlet of the absorption part is used for communicating with the flue gas containing carbon dioxide, and the absorbent inlet of the absorption part is used for communicating with the outlet of the intermediate chamber. The absorption liquid outlet of the condensation part is communicated with the absorption liquid pipeline, and the gas outlet of the condensation part is communicated with the purified gas pipeline.

[0073] It should be noted that the specific structural features of the absorption device are not limited in this embodiment, and can be selected according to actual needs.

[0074] As Figure 2 shown, another aspect of the present application provides an electrochemical carbon dioxide capture method S100 coupled with high-purity hydrogen production, which uses the electrochemical carbon dioxide capture system coupled with high-purity hydrogen production described above. The specific structure of the electrochemical carbon dioxide capture system coupled with high-purity hydrogen production has been described in detail above, and will not be repeated here. The method S100 comprises:

[0075] S110, delivering the flue gas containing carbon dioxide to the absorption device, absorbing the carbon dioxide in the flue gas by the absorbent in the absorption device, and obtaining absorption liquid and purified gas.

[0076] Specifically, the ammonia-containing solution absorbent in the absorption device 1 can contain a supporting electrolyte, which can be potassium chloride, sodium chloride, sodium sulfate and the like. In addition, some additives can be added to the absorbent in the absorption unit 1, such as tetraethylammonium chloride, tetrapropylammonium chloride and other surfactants. The absorption liquid is a high-carbon dioxide-loaded liquid obtained after the absorbent absorbs carbon dioxide, and the purified gas is the gas obtained after the flue gas is removed of carbon dioxide.

[0077] S120, delivering the absorption liquid to the anode chamber of the electrolytic hydrogen production device, and obtaining a gas-liquid mixture containing carbon dioxide under the action of the oxygen evolution electrode.

[0078] Specifically, the absorption liquid enters the anode chamber 21 through the absorption liquid pipeline 51, and the absorption liquid generates oxygen at the oxygen evolution electrode in the anode chamber 21. The oxygen evolution electrode reacts: 4OH - -4e - =O 2 ↑+2H2O, and the hydrogen evolution electrode reacts: 4H2O+4e - =2H2↑+4OH - The concentration of OH - near the oxygen evolution electrode decreases, the acidity of the reaction solution increases, CO2 is resolved, and a gas-liquid mixture containing carbon dioxide is obtained.

[0079] S130, the gas-liquid mixture containing carbon dioxide is subjected to gas-liquid separation treatment through the first gas-liquid separation device, to obtain carbon dioxide gas and first separation liquid, the separated carbon dioxide is discharged, and the separation liquid is transported to the intermediate chamber, the separation liquid in the intermediate chamber is subjected to ion exchange through the anion exchange membrane to obtain an absorbent, regeneration of the absorbent is realized, and the regenerated absorbent is transported to the absorption device to continue the absorption of carbon dioxide.

[0080] Specifically, the gas-liquid mixture containing carbon dioxide in the anode chamber 21 is transported to the first gas-liquid separation device 3 through the gas-liquid mixture pipeline 52 for separation, to obtain carbon dioxide gas and first separation liquid. The first separation liquid enters the intermediate chamber 22 through the first separation liquid pipeline 53, and the hydrogen produced by the hydrogen evolution cathode is combined with OH - and then enters the intermediate chamber 23 through the anion exchange membrane 24, the alkalinity of the solution in the intermediate chamber 23 is enhanced, to obtain an absorbent, and regeneration of the absorbent is realized. The regenerated absorbent enters the absorption device 1 from the intermediate chamber 22 through the absorbent pipeline 54, to continue to provide the absorption device 1 with the absorbent, and to continue to realize the absorption of carbon dioxide.

[0081] S140, the hydrogen-containing solution in the cathode chamber is transported to the first gas-liquid separation device, to obtain hydrogen gas and second separation liquid, the separated hydrogen gas is discharged through the first exhaust pipeline, and the second separation liquid is transported to the inlet of the cathode chamber, to realize independent separation and discharge of hydrogen gas.

[0082] In this embodiment, the second gas-liquid separation device 4 is a gas-liquid separator, which separates and purifies the hydrogen-containing solution to obtain purified hydrogen gas. Specifically, the hydrogen-containing solution generated in the cathode chamber 23 is transported to the second gas-liquid separation device 4 through the hydrogen-containing solution pipeline 55, the second gas-liquid separation device 4 separates and purifies the hydrogen-containing solution to obtain hydrogen gas and second separation liquid, wherein the obtained hydrogen gas is discharged through the first exhaust pipeline 57 for next step of hydrogen gas collection. The obtained second separation liquid reenters the cathode chamber 23 through the second gas-liquid separation device 4, to realize again hydrogen gas preparation, separation and purification, and independent separation and discharge of hydrogen gas.

[0083] The electrochemical carbon dioxide capture method coupled with high-purity hydrogen production of the application couples the absorption and capture process of carbon dioxide in flue gas with the process of electrolytic hydrogen production, to purify and collect hydrogen gas while capturing carbon dioxide, to improve energy efficiency, save energy consumption, save operation cost, and meet the concept of green environmental protection; the purification and collection of hydrogen gas are independently carried out in the cathode chamber and do not participate in the carbon dioxide capture system, to avoid the risk of explosion caused by mixing of hydrogen gas with the absorption liquid and oxygen in the anode chamber, and to increase the safety in the processes of carbon dioxide capture and hydrogen production.

[0084] It is understood that the above embodiments are only exemplary for illustrating the principles of the present application, and the present application is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and scope of the present application, and these modifications and improvements are also considered as the protection scope of the present application.

Claims

1. An electrochemical carbon dioxide capture system coupled with high purity hydrogen production, characterized in that, The device comprises an absorption device, an electrolytic hydrogen production device, a first gas-liquid separation device and a second gas-liquid separation device. The absorption device is provided with an absorbent for absorbing carbon dioxide, and the electrolytic hydrogen production device comprises an anode chamber, an intermediate chamber and a cathode chamber separated by an anion exchange membrane, wherein the anode chamber adopts an oxygen evolution electrode and the cathode chamber adopts a hydrogen evolution electrode. A first inlet of the absorption device is connected with flue gas containing carbon dioxide, a first outlet of the absorption device is connected with an inlet of the anode chamber through an absorption liquid pipeline, an outlet of the anode chamber is connected with an inlet of the first gas-liquid separation device through a gas-liquid mixture pipeline, a first outlet of the first gas-liquid separation device is connected with an inlet of the intermediate chamber through a first separation liquid pipeline, and an outlet of the intermediate chamber is connected with a second inlet of the absorption device through an absorbent pipeline to realize the regeneration and circulation of the absorbent. An inlet of the second gas-liquid separation device is connected with an outlet of the cathode chamber through a hydrogen-containing solution pipeline, a first outlet of the second gas-liquid separation device is connected with an inlet of the cathode chamber through a second separation liquid pipeline, and a second outlet of the second gas-liquid separation device is connected with a first exhaust pipeline to realize the independent separation and discharge of hydrogen. A second outlet of the first gas-liquid separation device is connected with a second exhaust pipeline to discharge separated carbon dioxide, and a second outlet of the absorption device is connected with a purified gas pipeline to discharge purified gas.

2. The system of claim 1, wherein, The second gas-liquid separation device is a gas-liquid separator which separates and purifies the hydrogen-containing solution to obtain purified hydrogen.

3. The system of claim 1, wherein, The first gas-liquid separation device comprises a flash tank and a condenser. A gas-liquid mixture inlet of the flash tank is connected with an outlet of the anode chamber, a to-be-condensed gas inlet of the condenser is connected with a to-be-condensed gas outlet of the flash tank, a condensate inlet of the flash tank is connected with a condensate outlet of the condenser, an inlet of the intermediate chamber is connected with a separation liquid outlet of the flash tank. A top of the condenser is connected with the second exhaust pipeline to discharge separated carbon dioxide.

4. The system according to any one of claims 1 to 3, characterized in that, The device further comprises a rinsing device. A first inlet of the rinsing device is connected with a second outlet of the absorption device through the purified gas pipeline. A second inlet of the rinsing device is connected with a rinsing water source. A first outlet of the rinsing device is connected with a gas discharge pipeline.

5. The system of claim 4, wherein, The device further comprises a desulfurization device. A first inlet of the desulfurization device is connected with flue gas containing carbon dioxide, and a first outlet of the desulfurization device is connected with a first inlet of the absorption device. A second inlet of the desulfurization device is connected with a second outlet of the rinsing device. A backflow outlet of the desulfurization device is connected with a backflow inlet of the rinsing device.

6. The system of claim 5, wherein, The device further comprises a recovery device. An inlet of the recovery device is connected with a backflow outlet of the desulfurization device to transport liquid substances in the desulfurization device to the recovery device for treatment when the desulfurization liquid in the desulfurization device reaches saturation.

7. The system of claim 5, wherein, The device further comprises a first heat exchange device. The first heat exchange device is connected with the elution device and the desulfurization device respectively, and is used for heat exchange between the elution device and the desulfurization device.

8. The system of any one of claims 1 to 3, wherein, The second heat exchange device is further included. The second heat exchange device is connected with the absorption device and the electrolytic hydrogen production device respectively, and is used for heat exchange between the absorption device and the electrolytic hydrogen production device.

9. The system of claim 8, wherein, The second heat exchange device includes a cold end inlet, a cold end outlet, a hot end inlet and a hot end outlet. The cold end inlet of the second heat exchange device is connected with the second outlet of the absorption device, the hot end outlet of the second heat exchange device is connected with the inlet of the anode chamber, the hot end inlet of the second heat exchange device is connected with the outlet of the intermediate chamber, and the cold end outlet of the second heat exchange device is connected with the second inlet of the absorption device.

10. An electrochemical carbon dioxide capture process coupled to high purity hydrogen production, characterized in that, The electrochemical carbon dioxide capture system is prepared by coupling high-purity hydrogen according to any one of claims 1 to 9, and the method comprises: The flue gas containing carbon dioxide is transported to the absorption device, and the carbon dioxide in the flue gas is absorbed by the absorbent in the absorption device to obtain an absorption liquid and a purified gas; The absorption liquid is transported to the anode chamber of the electrolytic hydrogen production device, and a gas-liquid mixture containing carbon dioxide is obtained under the action of an oxygen evolution electrode; The gas-liquid mixture containing carbon dioxide is subjected to gas-liquid separation treatment by the first gas-liquid separation device to obtain carbon dioxide gas and a first separation liquid, the separated carbon dioxide is discharged, and the separation liquid is transported to the intermediate chamber, the separation liquid in the intermediate chamber is ion exchanged by the anion exchange membrane to obtain an absorbent, the regeneration of the absorbent is realized, and the regenerated absorbent is transported to the absorption device to continue the absorption of carbon dioxide; The hydrogen-containing solution of the cathode chamber is transported to the second gas-liquid separation device to obtain hydrogen and a second separation liquid, the separated hydrogen is discharged through a first exhaust pipeline, and the second separation liquid is transported to the inlet of the cathode chamber to realize the independent separation and discharge of hydrogen.

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