Carbon dioxide electrochemical trapping and utilizing system based on ion exchange membrane

Abstract

The utility model provides a carbon dioxide electrochemical trapping and utilizing system based on an ion exchange membrane. Wherein the carbon dioxide in the flue gas is absorbed by the alkali liquor, the carbon dioxide is desorbed by the absorption liquor through the electrochemical reactor based on the ion exchange membrane, and then the carbon dioxide is converted through the three-chamber electrochemical reactor based on the ion exchange membrane, so that chemicals or fuels with high added values are generated. Therefore, the system not only can realize normal-temperature desorption of carbon dioxide and avoid high-temperature desorption with high energy consumption, but also can realize resource utilization of the carbon dioxide in the flue gas to generate an added value. In addition, alkali liquor (alkaline products) can be generated in the process of desorbing the carbon dioxide, so that the cost of alkaline absorption liquor and electrolyte during conversion of the carbon dioxide is saved.

Description

TECHNICAL FIELD

[0001] The application relates to a carbon dioxide electrochemical capture and utilization system based on an ion exchange membrane and belongs to the technical field of carbon dioxide capture and utilization. BACKGROUND

[0002] Carbon dioxide is the main component of greenhouse gases, and the greenhouse effect caused by carbon dioxide has triggered a series of ecological problems. In order to alleviate these negative effects, it is crucial to reduce carbon dioxide emissions. Carbon capture and storage (CCUS) technology plays a crucial role in addressing global climate change. It not only reduces carbon dioxide emissions but also promotes the recycling of carbon dioxide, achieving sustainable and low-carbon utilization of fossil energy.

[0003] Thermal power plants are the main source of carbon dioxide emissions in China, and there is an urgent need for CCUS technology to reduce emissions. The most commercially advanced carbon dioxide capture technology is the chemical absorption method, which involves a chemical reaction between carbon dioxide and an absorbent, and then regenerating the absorbent through heat, humidity, or pressure to obtain carbon dioxide. Amine absorbents have developed rapidly and have achieved commercial application, but there are still problems such as high energy consumption for absorbent regeneration and easy loss of absorbent. Another major category is alkaline solution absorbents, which are relatively mature and have high absorption efficiency, but still have problems such as high temperature and high energy consumption required for absorbent regeneration, and severe water loss. In order to better promote carbon capture technology and promote large-scale commercial application, it is urgent to solve the problems of high energy consumption for absorbent regeneration and easy loss of absorbent. CONTENT OF THE UTILITY MODEL

[0004] The application provides a carbon dioxide electrochemical capture and utilization system based on an ion exchange membrane to solve the problems of high energy consumption for carbon dioxide absorbent regeneration and easy loss.

[0005] To solve the above problems, the application provides a carbon dioxide electrochemical capture and utilization system based on an ion exchange membrane, which comprises a carbon dioxide absorption system, an electrochemical desorption carbon dioxide system, and an electrochemical conversion carbon dioxide system connected in sequence.

[0006] The carbon dioxide absorption system comprises an absorption tower and an alkali liquor circulation channel. The absorption tower comprises a gas inlet, a liquid inlet, a liquid outlet, and a gas outlet. The gas inlet is used to introduce flue gas to be absorbed. The liquid inlet is used to introduce alkali liquor. The gas outlet is used to discharge flue gas after absorbing carbon dioxide. The liquid inlet of the alkali liquor circulation channel is in communication with the liquid outlet of the absorption tower. The liquid outlet of the alkali liquor circulation channel is in communication with the liquid inlet of the absorption tower, and is used to circulate the alkali liquor to absorb carbon dioxide. The liquid outlet is also in communication with the electrochemical desorption carbon dioxide system to introduce the solution after absorbing carbon dioxide into the electrochemical desorption carbon dioxide system.

[0007] The electrochemical desorption carbon dioxide system comprises an ion exchange membrane-based electrochemical reactor, an electrode liquid circulation system and a gas-liquid separation device; the electrochemical reactor is used for electrochemical reaction by using the solution discharged from the absorption tower to generate basic products and acidic products, the basic products are introduced into the absorption tower through the liquid inlet of the absorption tower, and the acidic products are introduced into the electrochemical conversion carbon dioxide system after gas-liquid separation by the gas-liquid separation device; the electrode liquid circulation system is used for realizing the circulation of the electrode liquid of the electrochemical reactor.

[0008] The electrochemical conversion carbon dioxide system comprises an ion exchange membrane-based three-chamber electrochemical reactor and an anode liquid circulation channel; the three-chamber electrochemical reactor is used for electrochemical reaction by using the carbon dioxide generated by the electrochemical reactor to generate carbon-containing products; and the anode liquid circulation channel is used for realizing the circulation of the anode liquid of the electrochemical reactor.

[0009] Based on the above ion exchange membrane-based carbon dioxide electrochemical capture and utilization system, optionally, the electrochemical reactor comprises a first anode chamber, an acid chamber, a material chamber, an alkali chamber and a first cathode chamber arranged in sequence, and adjacent chambers are separated by a partition plate and an ion exchange membrane; the liquid inlet of the material chamber is connected with the liquid outlet of the carbon dioxide absorption system, the liquid outlet of the material chamber is connected with the electrochemical conversion carbon dioxide system, the liquid outlet of the alkali chamber is connected with the liquid inlet of the absorption tower, and the liquid outlet of the acid chamber is connected with the liquid inlet of the gas-liquid separation device.

[0010] Based on the above ion exchange membrane-based carbon dioxide electrochemical capture and utilization system, optionally, the three-chamber electrochemical reactor comprises a second anode chamber, an intermediate chamber and a second cathode chamber arranged in sequence, and adjacent chambers are separated by a partition plate, a hydrophilic inert microporous membrane and an ion exchange membrane; the liquid inlet of the second anode chamber is connected with the liquid outlet of the gas-liquid separation device, the gas inlet of the second cathode chamber is connected with the gas outlet of the gas-liquid separation device, and the liquid inlet of the intermediate chamber is used for introducing electrolyte.

[0011] Based on the above ion exchange membrane-based carbon dioxide electrochemical capture and utilization system, optionally, the liquid inlet of the intermediate chamber is connected with the liquid outlet of the material chamber or connected with an alkali liquid tank.

[0012] Based on the above ion exchange membrane-based carbon dioxide electrochemical capture and utilization system, optionally, the liquid outlet of the absorption tower is provided with a pH meter and an electric valve, when the pH value detected by the pH meter is less than a set threshold value, the electric valve is opened, so that the solution after absorbing carbon dioxide in the absorption tower can be introduced into the electrochemical desorption carbon dioxide system.

[0013] Based on the above ion exchange membrane-based carbon dioxide electrochemical capture and utilization system, optionally, a water quality impurity removal and hardness removal system is arranged between the carbon dioxide absorption system and the electrochemical desorption carbon dioxide system for reducing water quality hardness.

[0014] Based on the above ion exchange membrane-based carbon dioxide electrochemical capture and utilization system, optionally, an oxygen removal system is arranged between the electrochemical desorption carbon dioxide system and the electrochemical conversion carbon dioxide system for reducing the content of oxygen in carbon dioxide.

[0015] Based on the above ion exchange membrane-based carbon dioxide electrochemical capture and utilization system, optionally, the electrode liquid tank of the electrochemical desorption carbon dioxide system is provided with a liquid level meter for monitoring and indicating the liquid level.

[0016] Based on the above ion exchange membrane-based carbon dioxide electrochemical capture and utilization system, optionally, a temperature control system is further included for keeping the temperature of the electrode liquid tank of the electrochemical desorption carbon dioxide system within a set temperature range.

[0017] Based on the above ion exchange membrane-based carbon dioxide electrochemical capture and utilization system, optionally, the gas-liquid separation device is a gas-liquid separator or a membrane contactor.

[0018] The technical scheme provided in the present application has the following beneficial effects:

[0019] In the ion exchange membrane-based carbon dioxide electrochemical capture and utilization system provided in the present application, the alkali liquor absorbs carbon dioxide in flue gas, the absorption liquid is desorbed of carbon dioxide by the ion exchange membrane-based electrochemical reactor, and the carbon dioxide is converted by the ion exchange membrane-based three-chamber electrochemical reactor to generate high-value-added chemicals or fuels. In this way, the system not only can realize carbon dioxide desorption at room temperature to avoid high-temperature desorption with high energy consumption, but also can realize resource utilization of carbon dioxide in flue gas to generate additional value. In addition, alkali liquor (alkaline product) can also be generated in the process of desorbing carbon dioxide, thereby saving the cost of alkaline absorption liquid and electrolyte in the process of converting carbon dioxide. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application. In addition, these drawings and the associated description are not intended to limit the scope of the inventive concepts in any way.

[0021] Figure 1 A structure schematic diagram of the ion exchange membrane-based carbon dioxide electrochemical capture and utilization system provided in an embodiment of the present application;

[0022] Figure 2 Structure diagram of a carbon dioxide absorption system according to an embodiment of the present application;

[0023] Figure 3 Structure diagram of an electrochemical carbon dioxide desorption system according to an embodiment of the present application;

[0024] Figure 4 Structure diagram of an electrochemical carbon dioxide conversion system according to an embodiment of the present application.

[0025] Legend of reference signs:

[0026] 1 - carbon dioxide absorption system; 11 - absorption tower; 111 - gas inlet of the absorption tower; 112 - liquid outlet of the absorption tower; 113 - liquid inlet of the absorption tower; 114 - gas outlet of the absorption tower; 12 - alkali liquid circulation channel; 121 - liquid inlet of the alkali liquid circulation channel; 122 - liquid outlet of the alkali liquid circulation channel; 2 - electrochemical carbon dioxide desorption system; 21 - electrochemical reactor; 211 - first anode chamber; 212 - acid chamber; 2122 - liquid outlet of the acid chamber; 213 - material chamber; 2131 - liquid inlet of the material chamber; 2132 - liquid outlet of the material chamber; 214 - alkali chamber; 2142 - liquid outlet of the alkali chamber; 215 - first cathode chamber; 22 - electrode liquid circulation system; 23 - gas-liquid separation device; 231 - liquid inlet of the gas-liquid separation device; 232 - liquid outlet of the gas-liquid separation device; 233 - gas outlet of the gas-liquid separation device; 3 - electrochemical carbon dioxide conversion system; 31 - three-chamber electrochemical reactor; 311 - second anode chamber; 3111 - liquid inlet of the second anode chamber; 312 - intermediate chamber; 3121 - liquid inlet of the intermediate chamber; 313 - second cathode chamber; 3131 - gas inlet of the second cathode chamber; 32 - anode liquid circulation channel;

[0027] L1 - flue gas inlet pipeline; L2 - flue gas outlet pipeline; L3 - rich liquid pipeline; L4 - alkali liquid pipeline; L5 - acid liquid pipeline; L6 - material liquid pipeline; L7 - gas pipeline; L8 - liquid pipeline; L9 - product pipeline. DETAILED DESCRIPTION

[0028] In order to make the objects, technical solutions and advantages of the present application clearer, the following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application. In the case of no conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0029] As described in the background section, when absorbing carbon dioxide in flue gas by using alkaline solution absorbent, there are problems such as high energy consumption for regeneration of absorbent and easy loss, thereby affecting the commercial application and popularization of carbon capture technology. In view of this problem, the present application provides a carbon dioxide electrochemical capture and utilization system based on ion exchange membrane. After capturing carbon dioxide by using alkaline solution, carbon dioxide is desorbed from the absorption solution by electrochemical technology, and then converted into high value-added carbon-containing products such as chemicals or fuels by a three-chamber electrochemical reactor based on ion exchange membrane. In addition, alkaline solution can also be generated during the desorption of carbon dioxide. In this way, not only can carbon dioxide be desorbed at room temperature to avoid high-temperature desorption with high energy consumption, but also the resource utilization of carbon dioxide in flue gas can be realized, and the cost of alkaline absorption solution and electrolyte during carbon dioxide conversion can be saved. The following non-limiting description of the specific implementation scheme is made through several examples or embodiments.

[0030] Some embodiments of the present application provide a carbon dioxide electrochemical capture and utilization system based on ion exchange membrane. Referring to Figure 1 , the carbon dioxide electrochemical capture and utilization system based on ion exchange membrane of the present embodiment comprises a carbon dioxide absorption system 1, an electrochemical desorption carbon dioxide system 2 and an electrochemical conversion carbon dioxide system 3 connected in sequence.

[0031] Among them, the carbon dioxide absorption system 1 is responsible for absorbing carbon dioxide in flue gas, such as Figure 1 As shown, the flue gas to be absorbed (preferably flue gas after desulfurization and denitrification) enters the carbon dioxide absorption system 1 through the flue gas inlet pipeline L1, and the alkaline solution enters the carbon dioxide absorption system 1 through the alkaline solution pipeline L4. The alkaline solution can be a hydroxide solution, such as sodium hydroxide solution, potassium hydroxide solution, etc., at the beginning. In the carbon dioxide absorption system 1, the alkaline solution can react with carbon dioxide to generate carbonate or bicarbonate, thereby capturing carbon dioxide. Then, the flue gas absorbed with carbon dioxide can be discharged from the carbon dioxide absorption system 1 through the flue gas outlet pipeline L2. In addition, the solution (rich solution) absorbed with enough carbon dioxide can be introduced into the electrochemical desorption carbon dioxide system 2 through the rich solution pipeline L3 to obtain carbon dioxide by electrochemical desorption. At the same time, alkaline solution can also be generated during the desorption of carbon dioxide, and the generated alkaline solution can enter the carbon dioxide absorption system 1 again through the alkaline solution pipeline L4 for the next cycle. In this way, since the electrochemical reaction can realize the desorption of carbon dioxide at room temperature, high-temperature desorption with high energy consumption can be avoided. At the same time, the regeneration of alkaline absorption solution can also be realized, thereby saving the cost of alkaline absorption solution.

[0032] Furthermore, the carbon dioxide obtained by electrochemical desorption of carbon dioxide in the electrochemical desorption system 2 enters the gas-liquid separation device 23 through the acid pipe L5 for gas-liquid separation. After gas-liquid separation, the carbon dioxide and other gases enter one electrode chamber of the electrochemical conversion carbon dioxide system 3 through the gas pipe L7, while the liquid portion enters the other electrode chamber of the electrochemical conversion carbon dioxide system 3 through the liquid pipe L8. The remaining liquid after electrolysis in the electrochemical desorption system 2 is introduced into the electrochemical conversion carbon dioxide system 3 through the liquid pipe L6 as an electrolyte (other electrolytes can also be used). The electrochemical conversion carbon dioxide system 3 ultimately uses the electrolyte to reduce carbon dioxide into carbon-containing products with high added value (C1 or C2 products, etc.), such as chemicals or fuels. The generated carbon-containing products flow out through the product pipe L9. In this way, the resource utilization of carbon dioxide in flue gas can be realized, generating added value and further solving the problem of system operating costs.

[0033] In addition, the electrochemical reactor 21 of the electrochemical desorption carbon dioxide system 2 and the electrochemical reactor 31 of the electrochemical conversion carbon dioxide system 3 adopt an ion exchange membrane-based design, which can effectively isolate the generated hydrogen and oxygen ions and facilitate the separate recovery and utilization of acid and alkali products.

[0034] The working principle of the carbon dioxide electrochemical capture and utilization system has been explained above. The following section, with reference to the accompanying drawings, provides a further explanation of the specific structure of each component of the system.

[0035] First, refer to Figure 2 As shown, in some embodiments, the carbon dioxide absorption system 1 includes an absorption tower 11; the absorption tower 11 includes an air inlet 111, a liquid outlet 112, a liquid inlet 113, and an air outlet 114. The air inlet 111 is used to introduce flue gas containing carbon dioxide to be absorbed, the liquid inlet 113 is used to introduce alkaline solution, and the air outlet 114 is used to discharge the flue gas after carbon dioxide absorption; the liquid outlet 112 is connected to the electrochemical carbon dioxide desorption system 2 to introduce the solution after carbon dioxide absorption into the electrochemical carbon dioxide desorption system 2. Typically, the air inlet 111 of the absorption tower is located at the lower part of the absorption tower 11, and the air outlet 114 of the absorption tower is located at the upper part of the absorption tower 11. Thus, the flue gas flows upward after entering the absorption tower 11, and the alkaline solution is sprayed from top to bottom after entering the absorption tower 11 through the liquid inlet 113, so that the alkaline solution and carbon dioxide in the flue gas can have more complete contact and reaction. The air outlet 114 of the absorption tower is located at the top of the absorption tower 11 to facilitate the discharge of flue gas. In addition, the liquid outlet 112 of the absorption tower is also located at the lower part of the absorption tower 11 to facilitate the discharge of rich liquid.

[0036] In addition, to facilitate the full absorption of carbon dioxide by the alkaline solution, such as Figure 2As shown, the carbon dioxide absorption system 1 further comprises a lye circulation channel 12, the inlet 121 of which is connected to the outlet 112 of the absorption tower, and the outlet 122 of which is connected to the inlet 113 of the absorption tower, for circulating the lye to absorb carbon dioxide. After multiple cycles, the solution discharged from the outlet 112 of the absorption tower is mainly bicarbonate solution, which can no longer absorb carbon dioxide, and thus can be introduced into the electrochemical desorption system 2 for electrochemical desorption.

[0037] As shown, Figure 3 The electrochemical desorption system 2 comprises an ion exchange membrane-based electrochemical reactor 21, an electrode liquid circulation system 22, and a gas-liquid separation device 23. The electrochemical reactor 21 is used to generate alkaline products (lye) and acidic products (carbon dioxide and carbonic acid, etc.) by electrochemical reaction using the solution discharged from the absorption tower 11, the alkaline products are introduced into the absorption tower 11 through the inlet 113 of the absorption tower, and the acidic products are introduced into the electrochemical conversion carbon dioxide system 3 after gas-liquid separation by the gas-liquid separation device 23. The electrode liquid circulation system 22 is used to realize the circulation of the electrode liquid of the electrochemical reactor 21.

[0038] Further, the electrochemical reactor 21 comprises a first anode chamber 211, an acid chamber 212, a material chamber 213, an alkali chamber 214, and a first cathode chamber 215 arranged in sequence, and the adjacent chambers are separated by a partition and an ion exchange membrane. The inlet 2131 of the material chamber is connected to the outlet of the carbon dioxide absorption system 1, the outlet 2132 of the material chamber is connected to the electrochemical conversion carbon dioxide system 3, the outlet 2142 of the alkali chamber is connected to the inlet 113 of the absorption tower, and the outlet 2122 of the acid chamber is connected to the inlet 231 of the gas-liquid separation device.

[0039] The first anode chamber 211 is provided with an anode plate connected to an anode electrode, and the first cathode chamber 215 is provided with a cathode plate connected to a cathode electrode. The first anode chamber 211 and the first cathode chamber 215 are configured with an electrode liquid circulation system 22, which comprises a cathode liquid tank, an anode liquid tank, and corresponding circulation channels. The anode liquid tank is connected to the first anode chamber 211, and the cathode liquid tank is connected to the first cathode chamber 215. A plurality of membrane pairs are arranged between the first cathode chamber 215 and the first anode chamber 211, and the membrane pairs are composed of the partition and the cation exchange membrane, the amphoteric ion exchange membrane, and the anion exchange membrane alternately stacked to form the alkali chamber 214, the material chamber 213, and the acid chamber 212. The three chambers and the electrode chamber are respectively provided with an inlet at the lower part and an outlet at the upper part.

[0040] At the beginning, the initial solution is introduced into the alkali chamber 214 and the acid chamber 212, which can be a low-concentration carbonate solution. When the system starts to work, the rich solution discharged from the outlet of the carbon dioxide absorption system 1 enters the material chamber 213, and then the current is introduced into the cathode electrode and the anode electrode, respectively. Under the action of the current, water molecules are dissociated into hydrogen ions and hydroxyl ions by the amphoteric ion exchange membrane into the acid chamber 212 and the alkali chamber 214, respectively. The rich solution (mainly bicarbonate and a small amount of carbonate that may exist) in the material chamber 213 is dissociated into cations and anions. The cations enter the alkali chamber 214 through the cation exchange membrane and form an alkali solution with the hydroxyl ions, which is then discharged from the outlet 2142 of the alkali chamber and enters the absorption tower 11 through the inlet 113 of the absorption tower. The anions in the material chamber 213 enter the acid chamber 212 through the anion exchange membrane and form an acid solution with the hydrogen ions. As the concentration of hydrogen ions increases, part of the carbon dioxide is decomposed into carbon dioxide, and then the acidic solution and the carbon dioxide gas enter the gas-liquid separation device 23 through the outlet 2122 of the acid chamber to realize gas-liquid separation. The acidic solution and the carbon dioxide gas after gas-liquid separation are introduced into different chambers of the electrochemical conversion carbon dioxide system 3 to generate carbon-containing products under the action of electrolysis. The gas-liquid separation device 23 can be a gas-liquid separator or a membrane contactor that can realize gas-liquid separation.

[0041] In addition, as shown in Figure 4 The electrochemical conversion carbon dioxide system 3 includes a three-chamber electrochemical reactor 31 based on ion exchange membranes and an anode liquid circulation channel 32. The three-chamber electrochemical reactor 31 is used to generate carbon-containing products by electrochemical reaction using the carbon dioxide generated by the electrochemical reactor 21. In addition, the anode liquid circulation channel 32 is used to realize the circulation of the anode liquid of the electrochemical reactor 21.

[0042] Further, the three-chamber electrochemical reactor 31 includes a second anode chamber 311, an intermediate chamber 312 and a second cathode chamber 313 arranged in sequence, and the adjacent chambers are separated by a partition, a hydrophilic inert microporous membrane and an ion exchange membrane. The inlet 3111 of the second anode chamber is connected with the outlet 232 of the gas-liquid separation device, the gas inlet 3131 of the second cathode chamber is connected with the gas outlet 233 of the gas-liquid separation device, and the liquid inlet 3121 of the intermediate chamber is used to introduce the electrolyte.

[0043] The second anode chamber 311 is connected with the anode liquid through the anode liquid circulation channel 32, and is provided with an anode plate connected to the anode electrode. At the same time, the second cathode chamber 313 is connected with the cathode liquid, and is provided with a cathode plate connected to the cathode electrode. The intermediate chamber 312 between the second cathode chamber 313 and the second anode chamber 311 is composed of a hydrophilic inert microporous membrane, a partition and an ion exchange membrane.

[0044] In the three-chamber electrochemical reactor 31, carbon dioxide can be reduced by electrolysis to generate carbon-containing products. In the intermediate chamber 312, a catalyst can be arranged, and depending on the electrode material, current parameters, electrolyte and catalyst, etc., the carbon-containing products generated can be different, which can be C1 products (i.e., compounds containing one carbon) or C2 products (i.e., compounds containing two carbons). The generated carbon-containing products finally flow out through the outlet of the intermediate chamber 312, which can be used according to the actual product situation.

[0045] In addition, the inlet 3121 of the intermediate chamber is connected to the outlet 2132 of the material chamber or connected to the alkali tank. Depending on the connection, the electrolyte in the intermediate chamber 312 of the three-chamber electrochemical reactor 31 is different, and the main carbon-containing products generated are also different. That is, the intermediate chamber 312 of the three-chamber electrochemical reactor 31 can replace the electrolyte according to the demand of the main product.

[0046] For example, Figure 1 In the system shown, the low-concentration bicarbonate solution discharged from the outlet 2132 of the material chamber of the electrochemical reactor 21 of the electrochemical desorption carbon dioxide system 2 is introduced into the intermediate chamber 312 as an electrolyte, and in this scheme, C1 products can be finally prepared. If the inlet 3121 of the intermediate chamber is changed to be connected to the alkali tank (this scenario is not shown), C2 products can be prepared.

[0047] In addition, in some embodiments, a pH meter and an electric valve are arranged at the outlet 112 of the absorption tower, and the electric valve is arranged on the side closer to the electrochemical desorption carbon dioxide system 2 relative to the connection of the alkali circulation channel 12 and the rich liquid pipeline L3 (not shown), so as to ensure that the alkali circulation channel 12 can normally operate when the electric valve is closed. When the pH value detected by the pH meter is less than a set threshold value, the electric valve is opened to enable the solution after absorbing carbon dioxide in the absorption tower 11 to be introduced into the electrochemical desorption carbon dioxide system 2.

[0048] Specifically, in practice, as the alkali solution continuously circulates in the absorption tower 11 through the alkali circulation channel 12 and continuously reacts with carbon dioxide, the composition of the alkali solution gradually changes (hydroxide decreases, carbonate and bicarbonate increase), and the pH value continuously decreases. When it decreases to a certain extent, it basically no longer reacts with carbon dioxide, i.e., it can no longer absorb carbon dioxide, and therefore, at this time, the electric valve can be controlled to be opened to introduce the solution after absorbing sufficient carbon dioxide into the electrochemical desorption carbon dioxide system 2 for desorption. Based on this, in this embodiment, the pH value of the solution at the outlet 112 of the absorption tower is detected by the pH meter, and when the detected pH value is less than a set threshold value, the electric valve can be controlled to be opened. The set threshold value corresponding to the pH value can be 8.1, or can be adjusted according to actual needs.

[0049] In some embodiments, a water quality impurity and hardness removal system is provided between the carbon dioxide absorption system 1 and the electrochemical carbon dioxide desorption system 2 to reduce the hardness of the water quality, thereby facilitating the stable operation of the electrochemical reactor 21 of the electrochemical carbon dioxide desorption system 2. In this regard, the chemical agent, nanofiltration membrane or cation exchange resin can be selected according to the hardness of the water quality to reduce the hardness.

[0050] In some embodiments, an oxygen removal system is provided between the electrochemical carbon dioxide desorption system 2 and the electrochemical carbon dioxide conversion system 3 to reduce the oxygen content in the carbon dioxide. In this regard, the chemical adsorption oxygen removal, electrochemical oxygen reduction or membrane separation can be selected according to the oxygen content to reduce the oxygen content in the carbon dioxide, thereby avoiding the reduction of the efficiency of the electrochemical reduction of carbon dioxide.

[0051] In some embodiments, the electrode liquid tank (anode liquid tank and cathode liquid tank) of the electrochemical carbon dioxide desorption system 2 is provided with a liquid level gauge for monitoring and indicating the liquid level. When the liquid level is below the set limit, the user can be prompted to replenish the liquid.

[0052] In some embodiments, a temperature control system is further included to maintain the temperature of the electrode liquid tank of the electrochemical carbon dioxide desorption system within a set temperature range. The temperature control system includes a temperature sensor provided in the electrode liquid tank and a cooling device provided externally to ensure that the temperature of the electrode liquid tank is maintained within the set temperature range. For example, in some embodiments, the temperature of the electrode liquid tank needs to be maintained at 25-40°C.

[0053] For better understanding, the following are specific embodiments of the application of the above-mentioned carbon dioxide electro-capture and utilization system based on ion exchange membrane.

[0054] In this embodiment, the simulated flue gas (carbon dioxide concentration of 10%) is absorbed at room temperature and normal pressure, and the absorbent is an alkaline hydroxide solution (mass fraction of 30%). After multiple cycles of absorbing flue gas, the average carbon dioxide absorption efficiency is >70%, and when the pH of the rich liquid is <8.1, the material chamber of the electrochemical reactor of the electrochemical carbon dioxide desorption system is passed. The electrochemical reactor of the electrochemical carbon dioxide desorption system contains 8 membrane pairs, and the electrode liquid is 0.1 mol / L sodium sulfate solution. The initial solution of the alkali chamber and the acid chamber is a low-concentration carbonate solution, and the set working current density is 30 mA / cm 2, the gas-liquid separator gas outlet was monitored by a carbon dioxide flow meter and a carbon dioxide sensor in real time, the flow and purity of the desorbed carbon dioxide gradually increased and tended to be stable at a flow of 400 mL / min and a purity of 99%. At the same time, the alkaline solution was generated in the alkaline chamber, the pH meter detected the increase of the pH value in real time and the pH value was greater than 13, and the conductivity of the solution at the outlet of the material chamber decreased. The carbon dioxide generated by the electrochemical desorption of carbon dioxide was introduced into the cathode gas inlet of the three-chamber electrochemical reactor, the alkaline solution generated in the alkaline chamber flowed into the liquid inlet of the absorption tower, the acid solution generated in the acid chamber flowed out of the liquid outlet of the gas-liquid separator and flowed into the anode of the three-chamber electrochemical carbon dioxide reactor, and the solution at the outlet of the material chamber flowed into the middle chamber of the three-chamber electrochemical carbon dioxide reactor. The carbon dioxide flow was set to 300 mL / min, the middle chamber flow was 200 mL / min, and the current density was set to 100 mA / cm 2 , the synthesis gas (CO and H2) at the outlet of the middle chamber was detected (the Faraday efficiency was greater than 80%).

[0055] It can be understood that the same or similar parts in the above-mentioned embodiments can be mutually referred to, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0056] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0057] Although the embodiments of the present application have been shown and described above, it can be understood that the above-mentioned embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-mentioned embodiments within the scope of the present application.

Claims

1. A system for electrochemical capture and utilization of carbon dioxide based on ion exchange membranes, characterized in that, The system comprises, in sequence, a carbon dioxide absorption system, an electrochemical carbon dioxide desorption system, and an electrochemical carbon dioxide conversion system. The carbon dioxide absorption system comprises an absorption tower and an alkali solution circulation channel; the absorption tower comprises a gas inlet, a liquid inlet, a liquid outlet, and a gas outlet, the gas inlet is used for introducing flue gas to be absorbed by carbon dioxide, the liquid inlet is used for introducing alkali solution, and the gas outlet is used for discharging flue gas after absorption of carbon dioxide; the liquid inlet of the alkali solution circulation channel is in communication with the liquid outlet of the absorption tower, and the liquid outlet of the alkali solution circulation channel is in communication with the liquid inlet of the absorption tower, so as to circulate the alkali solution to absorb carbon dioxide; the liquid outlet is also in communication with the electrochemical carbon dioxide desorption system, so as to introduce the solution after absorption of carbon dioxide into the electrochemical carbon dioxide desorption system. The electrochemical carbon dioxide desorption system comprises an ion exchange membrane-based electrochemical reactor, an electrode liquid circulation system, and a gas-liquid separation device; the electrochemical reactor is used for performing electrochemical reaction by using the solution discharged from the absorption tower, to generate alkaline products and acidic products, the alkaline products are introduced into the absorption tower through the liquid inlet of the absorption tower, and the acidic products are introduced into the electrochemical carbon dioxide conversion system after gas-liquid separation by the gas-liquid separation device; the electrode liquid circulation system is used for realizing circulation of electrode liquid of the electrochemical reactor. The electrochemical carbon dioxide conversion system comprises an ion exchange membrane-based three-chamber electrochemical reactor and an anode liquid circulation channel; the three-chamber electrochemical reactor is used for performing electrochemical reaction by using carbon dioxide generated by the electrochemical reactor, to generate carbon-containing products. The anode liquid circulation channel is used for realizing circulation of anode liquid of the electrochemical reactor. The electrochemical reactor comprises, in sequence, a first anode chamber, an acid chamber, a material chamber, an alkali chamber, and a first cathode chamber, and adjacent chambers are separated by a partition plate and an ion exchange membrane; the liquid inlet of the material chamber is in communication with the liquid outlet of the carbon dioxide absorption system, the liquid outlet of the material chamber is in communication with the electrochemical carbon dioxide conversion system, the liquid outlet of the alkali chamber is in communication with the liquid inlet of the absorption tower, and the liquid outlet of the acid chamber is in communication with the liquid inlet of the gas-liquid separation device.

2. The ion-exchange membrane based system for electrochemical capture and utilization of carbon dioxide according to claim 1, wherein, The three-chamber electrochemical reactor comprises, in sequence, a second anode chamber, an intermediate chamber, and a second cathode chamber, and adjacent chambers are separated by a partition plate, a hydrophilic inert microporous membrane, and an ion exchange membrane; the liquid inlet of the second anode chamber is in communication with the liquid outlet of the gas-liquid separation device, the gas inlet of the second cathode chamber is in communication with the gas outlet of the gas-liquid separation device, and the liquid inlet of the intermediate chamber is used for introducing electrolyte.

3. The ion-exchange membrane based system for electrochemical capture and utilization of carbon dioxide according to claim 2, wherein, The liquid inlet of the intermediate chamber is in communication with the liquid outlet of the material chamber or an alkali solution tank.

4. The ion-exchange membrane based system for electrochemical capture and utilization of carbon dioxide according to claim 3, wherein, The liquid outlet of the absorption tower is provided with a pH meter and an electric valve, when the pH value detected by the pH meter is less than a set threshold value, the electric valve is opened, so that the solution after absorption of carbon dioxide in the absorption tower can be introduced into the electrochemical carbon dioxide desorption system.

5. The ion-exchange membrane based system for electrochemical capture and utilization of carbon dioxide according to claim 1, wherein, ​ 6. The ion-exchange membrane based system for electrochemical capture and utilization of carbon dioxide of claim 1, wherein, A water quality impurity and hardness removal system is arranged between the carbon dioxide absorption system and the electrochemical carbon dioxide desorption system to reduce water hardness.

7. The ion-exchange membrane based system for electrochemical capture and utilization of carbon dioxide of claim 1, wherein, An oxygen removal system is arranged between the electrochemical carbon dioxide desorption system and the electrochemical carbon dioxide conversion system to reduce the oxygen content in the carbon dioxide.

8. The ion-exchange membrane based system of claim 1, wherein, A liquid level meter is arranged on the electrode liquid tank of the electrochemical carbon dioxide desorption system to monitor and indicate the liquid level.

9. The ion-exchange membrane based system of claim 1, wherein, A temperature control system is further included to maintain the temperature of the electrode liquid tank of the electrochemical carbon dioxide desorption system within a set temperature range.

10. The ion-exchange membrane based system for electrochemical capture and utilization of carbon dioxide of claim 1, wherein, The gas-liquid separation device is a gas-liquid separator or a membrane contactor.

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