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

Abstract

The invention 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 present 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 Art

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

[0003] Thermal power plants are the main source of carbon dioxide emissions in my country, and the demand for emission reduction using CCUS technology is very urgent. At present, the most commercialized carbon dioxide capture technology is chemical absorption, which is a process in which carbon dioxide reacts with an absorbent and then the absorbent is regenerated by heat, humidity or pressure to obtain carbon dioxide. Among them, amine absorbents have developed rapidly and have been commercialized, but there are still problems such as high energy consumption for absorbent regeneration and easy loss of absorbents. Another major category is alkaline solution absorbents. Although this type of technology is relatively mature and has high absorption efficiency, it still has problems such as high temperature required for absorbent regeneration, high energy consumption and serious water loss. In order to better promote carbon capture technology and promote large-scale commercial applications, it is urgent to solve the problems of high energy consumption and easy loss of absorbent regeneration. Summary of the invention

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

[0005] In order to solve the above problems, the embodiment of the present 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 carbon dioxide desorption system and an electrochemical carbon dioxide conversion system connected in sequence;

[0006] Wherein, the carbon dioxide absorption system comprises an absorption tower and an alkali solution circulation channel; the absorption tower comprises an air inlet, a liquid inlet, a liquid outlet and an air outlet, the air inlet is used to introduce flue gas to be absorbed with carbon dioxide, the liquid inlet is used to introduce alkali solution, and the air outlet is used to discharge the flue gas after absorbing carbon dioxide; the liquid inlet of the alkali solution circulation channel is connected with the liquid outlet of the absorption tower, and the liquid outlet of the alkali solution circulation channel is connected with the liquid inlet of the absorption tower, so as to make the alkali solution circulate and absorb carbon dioxide; the liquid outlet is also connected with the electrochemical desorption carbon dioxide system to pass the solution after absorbing carbon dioxide into the electrochemical desorption carbon dioxide system;

[0007] The electrochemical desorption carbon dioxide system comprises an electrochemical reactor based on an ion exchange membrane, an electrode liquid circulation system and a gas-liquid separation device; the electrochemical reactor is used to use the solution discharged from the absorption tower to perform an electrochemical reaction 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 through the gas-liquid separation device; the electrode liquid circulation system is used to realize the circulation of the electrode liquid of the electrochemical reactor;

[0008] The electrochemical carbon dioxide conversion system includes a three-chamber electrochemical reactor based on an ion exchange membrane and an anolyte circulation channel; the three-chamber electrochemical reactor is used to utilize the carbon dioxide generated by the electrochemical reactor to carry out an electrochemical reaction to generate carbon-containing products; the anolyte circulation channel is used to realize the circulation of the anolyte of the electrochemical reactor.

[0009] Based on the above ion exchange membrane-based carbon dioxide electrochemical capture and utilization system, optionally, the electrochemical reactor includes 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 partitions and ion exchange membranes; the liquid inlet of the material chamber is connected to the liquid outlet of the carbon dioxide absorption system, the liquid outlet of the material chamber is connected to the electrochemical carbon dioxide conversion system, the liquid outlet of the alkali chamber is connected to the liquid inlet of the absorption tower, and the liquid outlet of the acid chamber is connected to 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 includes a second anode chamber, an intermediate chamber and a second cathode chamber arranged in sequence, and adjacent chambers are separated by partitions, hydrophilic inert microporous membranes and ion exchange membranes; the liquid inlet of the second anode chamber is connected to the liquid outlet of the gas-liquid separation device, the air inlet of the second cathode chamber is connected to the air outlet of the gas-liquid separation device, and the liquid inlet of the intermediate chamber is used to introduce 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 to the liquid outlet of the material chamber or is connected to the 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 opens to allow the solution after carbon dioxide absorption in the absorption tower to pass 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 impurity and hardness removal system is provided between the carbon dioxide absorption system and the electrochemical carbon dioxide desorption system to reduce water hardness.

[0014] Based on the above ion exchange membrane-based carbon dioxide electrochemical capture and utilization system, optionally, a deoxygenation system is provided between the electrochemical carbon dioxide desorption system and the electrochemical carbon dioxide conversion system to reduce the oxygen content in the 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, it also includes a temperature control system for maintaining 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 solution provided by this application has the following beneficial effects:

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

[0020] The accompanying drawings herein are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification are used to explain the principles of the present application. In addition, these drawings and text descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application for those skilled in the art by referring to specific embodiments.

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

[0022] Figure 2 A schematic diagram of the structure of a carbon dioxide absorption system provided in one embodiment of the present application;

[0023] Figure 3 A schematic diagram of the structure of an electrochemical carbon dioxide desorption system provided in one embodiment of the present application;

[0024] Figure 4 A schematic diagram of the structure of an electrochemical carbon dioxide conversion system provided for one embodiment of the present application.

[0025] Description of reference numerals:

[0026] 1-carbon dioxide absorption system; 11-absorption tower; 111-air inlet of absorption tower; 112-liquid outlet of absorption tower; 113-liquid inlet of absorption tower; 114-air outlet of absorption tower; 12-alkali solution circulation channel; 121-liquid inlet of alkali solution circulation channel; 122-liquid outlet of alkali solution circulation channel; 2-electrochemical desorption carbon dioxide system; 21-electrochemical reactor; 211-first anode chamber; 212-acid chamber; 2122-liquid outlet of acid chamber; 213-feed chamber; 2131-liquid inlet of feed chamber; 2132-liquid outlet of feed 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 conversion carbon dioxide 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 pipe; L2- flue gas outlet pipe; L3- rich liquid pipe; L4- alkali liquid pipe; L5- acid liquid pipe; L6- feed liquid pipe; L7- gas pipe; L8- liquid pipe; L9- product pipe. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0029] As described in the background technology section, when using alkaline solution absorbent to absorb carbon dioxide in flue gas, there are problems such as high energy consumption and easy loss of absorbent regeneration, which affect the commercial application and promotion of carbon capture technology. In response to this problem, the present application provides a carbon dioxide electrochemical capture and utilization system based on ion exchange membrane. After using alkaline solution to capture carbon dioxide, carbon dioxide is desorbed from the absorption liquid by electrochemical technology, and then converted into high value-added carbon-containing products such as chemicals or fuels through 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 and high-energy-consuming high-temperature desorption be avoided, but also resource utilization of carbon dioxide in flue gas can be realized, and the cost of alkaline absorption liquid and electrolyte when converting carbon dioxide can be saved. The following is a non-restrictive description of the specific implementation scheme through several examples or embodiments.

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

[0031] Among them, the carbon dioxide absorption system 1 is responsible for absorbing carbon dioxide in the flue gas. Figure 1 As shown, the flue gas to be absorbed with carbon dioxide (preferably the flue gas after desulfurization and denitrification) enters the carbon dioxide absorption system 1 through the flue gas inlet pipe L1, and the alkali liquid is passed into the carbon dioxide absorption system 1 through the alkali liquid pipe L4. The alkali liquid can be a hydroxide solution at the beginning, such as a sodium hydroxide solution, a potassium hydroxide solution, etc. In the carbon dioxide absorption system 1, the alkali liquid can react chemically with carbon dioxide to generate carbonates or bicarbonates to achieve the capture of carbon dioxide. After that, the flue gas absorbed with carbon dioxide can be discharged from the carbon dioxide absorption system 1 through the flue gas outlet pipe L2. In addition, the solution (rich liquid) that has absorbed enough carbon dioxide is passed through the rich liquid pipe L3 to the electrochemical desorption carbon dioxide system 2 for electrochemical desorption to obtain carbon dioxide. At the same time, alkali liquid will also be generated in the process of desorbing carbon dioxide, and the generated alkali liquid can enter the carbon dioxide absorption system 1 again through the alkali liquid pipe L4 for the next recycling. In this way, since carbon dioxide can be desorbed at room temperature through the electrochemical reaction, high-temperature desorption with high energy consumption can be avoided. At the same time, the regeneration of the alkaline absorption liquid can also be achieved, thereby saving the cost of the alkaline absorption liquid.

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

[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 hydroxide ions and facilitate the separate recovery and utilization of acid and base products.

[0034] The working principle of the carbon dioxide electrochemical capture and utilization system is described above. The specific structure of each component of the system is further described below in conjunction with the accompanying drawings.

[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 to be absorbed with carbon dioxide, the liquid inlet 113 is used to introduce alkaline solution, and the air outlet 114 is used to discharge the flue gas after absorbing carbon dioxide; the liquid outlet 112 is connected to the electrochemical desorption carbon dioxide system 2 to pass the solution after absorbing carbon dioxide into the electrochemical desorption carbon dioxide system 2. Typically, the air inlet 111 of the absorption tower is arranged at the lower part of the absorption tower 11, and the air outlet 114 of the absorption tower is arranged at the upper part of the absorption tower 11, so that 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 of the absorption tower, so that the alkaline solution and the carbon dioxide in the flue gas can contact and react more fully; the air outlet 114 of the absorption tower is arranged at the top of the absorption tower 11, which is convenient for the discharge of flue gas; in addition, the liquid outlet 112 of the absorption tower is also arranged at the lower part of the absorption tower 11, which is convenient for the discharge of rich liquid.

[0036] In addition, in order to facilitate the alkali solution to fully absorb carbon dioxide, such as Figure 2As shown, the carbon dioxide absorption system 1 also includes an alkali liquid circulation channel 12, the liquid inlet 121 of the alkali liquid circulation channel is connected to the liquid outlet 112 of the absorption tower, and the liquid outlet 122 of the alkali liquid circulation channel is connected to the liquid inlet 113 of the absorption tower, so as to make the alkali liquid circulate and absorb carbon dioxide. Finally, after multiple cycles, the solution discharged at the liquid outlet 112 of the absorption tower is mainly a bicarbonate solution, which is basically no longer able to absorb carbon dioxide, so it can be passed into the electrochemical desorption carbon dioxide system 2 for electrochemical desorption.

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

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

[0039] Among them, the first anode chamber 211 is provided with an anode plate, which is connected to the anode electrode, and the first cathode chamber 215 is provided with a cathode plate, which is connected to the cathode electrode. The first anode chamber 211 and the first cathode chamber 215 are equipped with an electrode liquid circulation system 22, and the electrode liquid circulation system 22 includes a cathode liquid tank, an anode liquid tank and a corresponding circulation channel. 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 alternately stacked with a partition plate and a cation exchange membrane, a zwitterion exchange membrane, and an anion exchange membrane to form an alkali chamber 214, a material chamber 213 and an acid chamber 212. The three chambers and the electrode chamber are provided with a liquid inlet at the lower part and a liquid outlet at the upper part.

[0040] Initially, the initial solution is passed in the alkali chamber 214 and the acid chamber 212, and the initial solution can generally be a carbonate solution of low concentration. When starting work, the rich solution discharged by the liquid outlet of the carbon dioxide absorption system 1 enters the material chamber 213, and then electric current is passed respectively on the cathode electrode and the anode electrode, and under the action of electric current, water molecules are dissociated into hydrogen ions and hydroxide ions by amphoteric ion exchange membranes respectively in the acid chamber 212 and the alkali chamber 214, and 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. Wherein, cations enter the alkali chamber 214 and hydroxide to form alkali solution by cation exchange membranes, and then are discharged from the liquid outlet 2142 of the alkali chamber, and enter the absorption tower 11 by the liquid inlet 113 of the absorption tower. The anions of the material chamber 213 enter the acid chamber 212 and hydrogen ions to form acid solution by anion exchange membranes. As the concentration of hydrogen ions increases, part of the carbonic acid decomposes into carbon dioxide, and then the acidic solution and carbon dioxide gas enter the gas-liquid separation device 23 through the liquid outlet 2122 of the acid chamber to achieve gas-liquid separation. The acidic solution and carbon dioxide gas after gas-liquid separation are respectively introduced into different chambers of the electrochemical carbon dioxide conversion system 3 to generate carbon-containing products under electrolysis. Among them, the gas-liquid separation device 23 can be a gas-liquid separator or a membrane contactor, etc., which can achieve gas-liquid separation.

[0041] In addition, if Figure 4 As shown, the electrochemical carbon dioxide conversion system 3 includes a three-chamber electrochemical reactor 31 based on an ion exchange membrane and an anolyte circulation channel 32; the three-chamber electrochemical reactor 31 is used to use the carbon dioxide generated by the electrochemical reactor 21 to perform an electrochemical reaction to generate a carbon-containing product. In addition, the anolyte circulation channel 32 is used to realize the circulation of the anolyte of the electrochemical reactor 21.

[0042] Furthermore, the three-chamber electrochemical reactor 31 includes a second anode chamber 311, an intermediate chamber 312 and a second cathode chamber 313 which are arranged in sequence, and adjacent chambers are separated by partitions, hydrophilic inert microporous membranes and ion exchange membranes; the liquid inlet 3111 of the second anode chamber is connected to the liquid outlet 232 of the gas-liquid separation device, the air inlet 3131 of the second cathode chamber is connected to the air outlet 233 of the gas-liquid separation device, and the liquid inlet 3121 of the intermediate chamber is used for introducing electrolyte.

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

[0044] Among them, in the three-chamber electrochemical reactor 31, carbon dioxide can be reduced by electrolysis to generate carbon-containing products. Among them, a catalyst can be set in the intermediate chamber 312, and the generated carbon-containing products will be different depending on the electrode material, current parameters, electrolyte and catalyst, etc., 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 eventually flow out through the liquid outlet of the intermediate chamber 312 and can be used according to the actual product situation.

[0045] In addition, the liquid inlet 3121 of the middle chamber is connected to the liquid outlet 2132 of the material chamber or to the alkali liquid tank. According to different connection conditions, the electrolyte of the middle chamber 312 of the three-chamber electrochemical reactor 31 is different, and the main carbon-containing products finally generated are also different. That is, the electrolyte of the middle chamber 312 of the three-chamber electrochemical reactor 31 can be replaced according to the main product demand.

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

[0047] In addition, in some embodiments, a pH meter and an electric valve are provided at the liquid outlet 112 of the absorption tower, and the electric valve is provided on a side (not shown) closer to the electrochemical desorption carbon dioxide system 2 relative to the connection between the alkali liquid circulation channel 12 and the rich liquid pipeline L3, to ensure that the alkali liquid circulation channel 12 can operate normally when the electric valve is closed. Moreover, when the pH value detected by the pH meter is less than the set threshold value, the electric valve is opened so that the solution after the absorption of carbon dioxide in the absorption tower 11 can pass 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 solution circulation channel 12, it continuously reacts with carbon dioxide, and the composition of the alkali solution gradually changes (hydroxide decreases, carbonates and bicarbonates increase), and the pH value continuously decreases. When it decreases to a certain extent, it basically no longer reacts with carbon dioxide, that is, it can no longer absorb carbon dioxide. Therefore, at this time, the electric valve can be controlled to open, and the solution after absorbing enough carbon dioxide is passed into the electrochemical desorption carbon dioxide system 2 for desorption. Based on this, in this embodiment, the pH value of the solution at the liquid outlet 112 of the absorption tower is detected by a pH meter, and when the detected pH value is less than the set threshold value, the electric valve can be controlled to open. Among them, the set threshold value corresponding to the pH value can be 8.1, and can also be adjusted according to actual needs.

[0049] In addition, in some embodiments, a water impurity and hardness removal system is provided between the carbon dioxide absorption system 1 and the electrochemical desorption carbon dioxide system 2 to reduce the water hardness, thereby being more conducive to the stable operation of the electrochemical reactor 21 of the electrochemical desorption carbon dioxide system 2. Among them, chemical agents, nanofiltration membranes or cation exchange resins can be selected according to the water hardness to reduce the hardness.

[0050] In addition, in some embodiments, a deoxygenation system is provided between the electrochemical desorption carbon dioxide system 2 and the electrochemical conversion carbon dioxide system 3 to reduce the oxygen content in carbon dioxide. Among them, chemical adsorption deoxygenation, electrochemical oxygen reduction or membrane separation can be selected according to the oxygen content to reduce the oxygen content in carbon dioxide to avoid reducing the efficiency of electroreduction of carbon dioxide.

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

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

[0053] For a better understanding, the following is a specific example of applying the above-mentioned ion exchange membrane-based carbon dioxide electric capture and utilization system.

[0054] In this embodiment, simulated flue gas (carbon dioxide concentration 10%) is absorbed at room temperature and pressure, and the absorbent is an alkaline hydroxide solution (mass fraction 30%). After multiple cycles of flue gas absorption, the average carbon dioxide absorption efficiency is >70%, and the rich liquid pH is <8.1 before entering the material chamber of the electrochemical reactor of the electrochemical desorption carbon dioxide system. The electrochemical reactor of the electrochemical desorption carbon dioxide system contains 8 membrane pairs, the electrode liquid is a 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 working current density is set to 30 mA / cm 2After a period of constant current electrolysis, bubbles begin to appear in the acid chamber. The gas outlet of the gas-liquid separator is monitored in real time by a carbon dioxide flowmeter and a carbon dioxide sensor. The flow and purity of the desorbed carbon dioxide gradually increase and tend to stabilize at a flow rate of 400mL / min and a purity of 99%. At the same time, the alkali chamber generates alkaline solution. The pH meter detects in real time that the pH value rises and is greater than 13, and the conductivity of the liquid at the outlet of the material chamber decreases. The carbon dioxide produced by the electrochemical desorption of carbon dioxide is introduced into the cathode air inlet of the three-chamber electrochemical reactor, and the alkaline solution produced in the alkali chamber flows to the liquid inlet of the absorption tower. The acid solution produced in the acid chamber flows to the anode of the three-chamber electrochemical carbon dioxide reactor through the liquid outlet of the gas-liquid separator. The outlet solution of the material chamber flows to the intermediate chamber of the three-chamber electrochemical carbon dioxide reactor. The carbon dioxide flow rate is set to 300mL / min, the intermediate chamber flow rate is 200mL / min, and the current density is set to 100mA / cm 2 Synthesis gas (CO and H) was detected at the outlet of the intermediate chamber. 2 )(Faraday efficiency greater than 80%).

[0055] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0056] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0057] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A carbon dioxide electrochemical capture and utilization system based on ion exchange membrane, characterized in that: include: A carbon dioxide absorption system, an electrochemical carbon dioxide desorption system and an electrochemical carbon dioxide conversion system connected in sequence; Wherein, the carbon dioxide absorption system comprises an absorption tower and an alkali solution circulation channel; the absorption tower comprises an air inlet, a liquid inlet, a liquid outlet and an air outlet, the air inlet is used to introduce flue gas to be absorbed with carbon dioxide, the liquid inlet is used to introduce alkali solution, and the air outlet is used to discharge the flue gas after absorbing carbon dioxide; the liquid inlet of the alkali solution circulation channel is connected with the liquid outlet of the absorption tower, and the liquid outlet of the alkali solution circulation channel is connected with the liquid inlet of the absorption tower, so as to make the alkali solution circulate and absorb carbon dioxide; the liquid outlet is also connected with the electrochemical desorption carbon dioxide system to pass the solution after absorbing carbon dioxide into the electrochemical desorption carbon dioxide system; The electrochemical desorption carbon dioxide system comprises an electrochemical reactor based on an ion exchange membrane, an electrode liquid circulation system and a gas-liquid separation device; the electrochemical reactor is used to use the solution discharged from the absorption tower to perform an electrochemical reaction 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 through the gas-liquid separation device; the electrode liquid circulation system is used to realize the circulation of the electrode liquid of the electrochemical reactor; The electrochemical carbon dioxide conversion system comprises a three-chamber electrochemical reactor based on an ion exchange membrane and an anolyte circulation channel; the three-chamber electrochemical reactor is used to utilize the carbon dioxide generated by the electrochemical reactor to perform an electrochemical reaction to generate a carbon-containing product; The anolyte circulation channel is used to realize the circulation of the anolyte of the electrochemical reactor.

2. The carbon dioxide electrochemical capture and utilization system based on ion exchange membrane according to claim 1 is characterized in that: The electrochemical reactor comprises a first anode chamber, an acid chamber, a feed chamber, an alkali chamber and a first cathode chamber which are arranged in sequence, and adjacent chambers are separated by partitions and ion exchange membranes; the liquid inlet of the feed chamber is connected to the liquid outlet of the carbon dioxide absorption system, the liquid outlet of the feed chamber is connected to the electrochemical carbon dioxide conversion system, the liquid outlet of the alkali chamber is connected to the liquid inlet of the absorption tower, and the liquid outlet of the acid chamber is connected to the liquid inlet of the gas-liquid separation device.

3. The carbon dioxide electrochemical capture and utilization system based on ion exchange membrane according to claim 2 is characterized in that: The three-chamber electrochemical reactor includes a second anode chamber, an intermediate chamber and a second cathode chamber which are arranged in sequence, and adjacent chambers are separated by a partition, a hydrophilic inert microporous membrane and an ion exchange membrane; the liquid inlet of the second anode chamber is connected to the liquid outlet of the gas-liquid separation device, the air inlet of the second cathode chamber is connected to the air outlet of the gas-liquid separation device, and the liquid inlet of the intermediate chamber is used to introduce an electrolyte.

4. The carbon dioxide electrochemical capture and utilization system based on ion exchange membrane according to claim 3 is characterized in that: The liquid inlet of the intermediate chamber is connected with the liquid outlet of the material chamber or is connected with the alkali liquid tank.

5. The carbon dioxide electrochemical capture and utilization system based on ion exchange membrane according to claim 1, characterized in that: 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, the electric valve opens to allow the solution after carbon dioxide absorption in the absorption tower to pass into the electrochemical carbon dioxide desorption system.

6. The carbon dioxide electrochemical capture and utilization system based on ion exchange membrane according to claim 1, characterized in that: A water impurity and hardness removal system is arranged between the carbon dioxide absorption system and the electrochemical carbon dioxide desorption system to reduce the water hardness.

7. The carbon dioxide electrochemical capture and utilization system based on ion exchange membrane according to claim 1, characterized in that: A deoxygenation system is provided 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 carbon dioxide electrochemical capture and utilization system based on ion exchange membrane according to claim 1, characterized in that: The electrode liquid tank of the electrochemical carbon dioxide desorption system is provided with a liquid level meter for monitoring and indicating the liquid level.

9. The carbon dioxide electrochemical capture and utilization system based on ion exchange membrane according to claim 1, characterized in that: The system also includes a temperature control system for maintaining the temperature of the electrode liquid tank of the electrochemical carbon dioxide desorption system within a set temperature range.

10. The carbon dioxide electrochemical capture and utilization system based on ion exchange membrane according to claim 1, characterized in that: The gas-liquid separation device is a gas-liquid separator or a membrane contactor.

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