Carbon dioxide recycling system

Abstract

A carbon dioxide recycling system includes an electrochemical reaction module to recycle carbon dioxide. The system is also provided with a carbon dioxide gas supply and humidification unit which provides humidified carbon dioxide gas as a reactant of the cathode of the electrochemical reaction module. The system is preferably provided with a plurality of control loops to improve the efficiency of the carbon dioxide gas conversion reaction.

Description

Technical Field

[0001] The present invention relates to a chemical reaction system, in particular to a carbon dioxide recycling system. Background Art

[0002] CO2 emission reduction technologies can be specifically divided into three methods: capture, storage and reuse. Among them, reuse technology can be divided into direct utilization and conversion utilization. Direct utilization of CO2 is used to manufacture products such as urea (nitrogen fertilizer), salicylic acid (drug additive), and carbonate (plastic). The conversion utilization of CO2 is to use the captured CO2 as a raw material to produce other chemical or energy products. CO2 conversion and reuse has the potential to become an emerging industry in the future.

[0003] With the help of a catalyst, carbon dioxide can be converted (reduced) into a low-carbon fuel (containing 1 to 3 carbon atoms). According to the way the energy is provided, it is further divided into photocatalysis, thermal catalysis, and electrocatalysis. "Water splitting electrolysis reaction" is a common electrocatalytic reaction. By providing electrical energy to water molecules, they are decomposed into hydrogen and oxygen. However, the products of water electrolysis are hydrogen and oxygen, which are not valuable in themselves. In addition, the energy conversion efficiency of the electrolysis reaction is not 100%. In addition, if CO2 is introduced as a reactant into the reduction reaction, it is difficult to completely react the CO2. Summary of the invention

[0004] The main purpose of the present invention is to provide a carbon dioxide recycling system, which uses electrochemical technology to decompose and recycle CO2. The system includes an electrochemical reaction module, which includes an anode, a cathode, and a separation membrane between the anode and the cathode. In addition, the anode chamber is located on one side of the anode and includes an electrolyte, which undergoes an oxidation reaction with the anode to produce oxygen. The cathode chamber is located on one side of the cathode and includes carbon dioxide, which undergoes a reduction reaction with the cathode to produce a carbonaceous product. The system also has a carbon dioxide gas supply and humidification unit, which is connected to the inlet of the cathode chamber to provide humidified carbon dioxide gas to the cathode chamber.

[0005] In some embodiments, the system further comprises an electrolyte supply and circulation unit and / or a cathode product dehumidification unit.

[0006] In some embodiments, in order to improve the reaction efficiency, the system further includes a main control loop, an electrolyte flow control loop, a carbon dioxide flow control loop, and / or a carbon dioxide humidity control loop. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 FIG. 1 is a schematic diagram showing an electrochemical reaction module according to an embodiment of the present invention.

[0008] Figure 2FIG. 4 is a schematic diagram showing a carbon dioxide recycling system according to an embodiment of the present invention.

[0009] Figure 3 FIG. 4 is a schematic diagram showing a carbon dioxide gas supply and humidification unit according to an embodiment of the present invention.

[0010] Figure 4 FIG. 4 is a schematic diagram showing a cathode product dehumidification unit according to an embodiment of the present invention.

[0011] Figure 5 Detailed description of the invention Figure 4 is a block diagram showing a carbon dioxide recycling system according to a preferred embodiment of the present invention.

[0012] Fig. 6A 1 is an experimental result, showing the relationship between the partial current of the cathode product and the supply voltage under different carbon dioxide supply flow rates for an electrochemical reaction module according to an embodiment of the present invention.

[0013] Figure 6B 1 is an experimental result, which shows the relationship between the peak current of the module and the supply flow rate (sccm) of carbon dioxide at different reaction areas for an electrochemical reaction module according to an embodiment of the present invention.

[0014] Fig. 7A 1 is an experimental result, showing the concentration of cathode exhaust gas under different input voltages for an electrochemical reaction module according to an embodiment of the present invention.

[0015] Figure 7B 1 is an experimental result, showing the concentration of cathode exhaust gas under different input voltages for an electrochemical reaction module according to an embodiment of the present invention.

[0016] Figure 8 FIG. 4 is a block diagram showing a main control loop of a carbon dioxide recycling system according to an embodiment of the present invention.

[0017] Fig. 9 FIG. 4 is a block diagram showing an anolyte flow control loop of a carbon dioxide reuse system according to an embodiment of the present invention.

[0018] Fig.10 FIG. 4 is a block diagram showing a cathode CO 2 flow control loop of a carbon dioxide recycling system according to an embodiment of the present invention.

[0019] Fig.11 FIG. 4 is a block diagram showing a cathode CO 2 humidity control loop of a carbon dioxide recycling system according to an embodiment of the present invention.

[0020]

Main component symbol description

[0021] 1: Electrochemical reaction module 2: Electrolyte supply and circulation unit

[0022] 3: Carbon dioxide gas supply and humidification unit 4: Cathode product dehumidification unit

[0023] 10: Anode 11: Cathode

[0024] 12: Separation membrane 13: Power supply

[0025] 14: Anode chamber 15: Cathode chamber

[0026] 20: Anode gas-liquid separator 21: Electrolyte storage tank

[0027] 22: Liquid delivery pump 23: Flow meter

[0028] 24: Float flowmeter 25: Valve

[0029] 26: Valve 27: Valve

[0030] 28: Valve 29: Temperature sensor

[0031] 30: CO2 gas supply source 31: First humidity adjustment device

[0032] 32: Water storage tank 33: Delivery pump

[0033] 34: Adjustable pressure gas filter 35: One-way valve

[0034] 36: Valve 37: Valve

[0035] 38: Valve 39: Humidity sensor

[0036] 40: Gas composition sensor 41: Second humidity adjustment device

[0037] 42: Gas delivery pump 43: Flow meter

[0038] 44: Adjustable pressure gas filter 45: One-way valve

[0039] 46: Valve 47: Valve

[0040] 48: Valve 49: Valve

[0041] 50: Valve 141: Inlet

[0042] 142: Exit 151: Entrance

[0043] 152:Export 310:Shell

[0044] 311: Inner tube 312: Channel

[0045] 370: Controller 400: Dry gas

[0046] 402: humid gas 410: shell

[0047] 411: Inner tube 412: Channel

[0048] 3101: Entrance 3102: Exit

[0049] 3111: Entrance 3112: Exit

[0050] 4101: Entrance 4102: Exit

[0051] 4111: Entrance 4112: Exit DETAILED DESCRIPTION

[0052] The following will describe in detail the various embodiments of the present invention, with accompanying drawings as examples. In addition to these detailed descriptions, the present invention can also be widely implemented in other embodiments, and any easy replacement, modification, and equivalent changes of the embodiment are included in the scope of the present case and are subject to the scope of the subsequent patent. In the description of the specification, many specific details are provided to enable the reader to have a more complete understanding of the present invention; however, the present invention may still be implemented under the premise of omitting some or all of these specific details. In addition, well-known procedural steps or elements are not described in detail to avoid unnecessary limitations on the present invention.

[0053] Some embodiments of the present invention provide a carbon dioxide recycling system, which includes an electrochemical reaction module to convert CO2 for utilization. Figure 1 FIG. 1 is a schematic diagram showing an electrochemical reaction module 1 according to an embodiment of the present invention. Figure 1As shown, the electrochemical reaction module 1 includes an anode 10, a cathode 11, a separation membrane 12, a power source 13, an anode chamber 14, and a cathode chamber 15. The power source 13 electrically connects the anode 10 and the cathode. The anode chamber 14 is located on one side of the anode 10, and the electrolyte enters the anode chamber 14 from the inlet 141 of the anode chamber 14 to perform an oxidation reaction therein, and its product includes oxygen and is taken out from the outlet 142 of the anode chamber 14 along with the electrolyte. The cathode chamber 15 is located on one side of the cathode 11, and the reactant includes carbon dioxide introduced from the inlet 151 of the cathode chamber 15 to perform a reduction reaction of carbon dioxide, and its product includes carbon-containing products and is discharged from the outlet 152 of the cathode chamber 15. The separation membrane 12 is located between the anode 10 and the cathode 11. The anode 10 and the cathode 11 can be modified to include a catalyst. Preferably, the separation membrane 12 is attached to the anode 10 and the cathode 11 to reduce the resistance of the electrochemical reaction module 1 to improve energy utilization efficiency. The function of the separation membrane 12 is to prevent the exchange of substances between the two chambers while allowing ions to pass through to maintain the electrical neutrality of the electrochemical reaction module 1. In a preferred embodiment, the separation membrane 12 is an anion exchange membrane (only anions can pass through).

[0054] In some embodiments, the electrochemical reaction module 1 performs a water decomposition reaction. Electric energy is provided to water, causing it to be decomposed into hydrogen and oxygen. The full water decomposition reaction formula, for example: 2H2O→O2+2H2, under acidic and alkaline reaction conditions, the cathode and anode half reactions are as follows:

[0055] Anode: 2H2O→O2+4H+4e - ; Cathode: 4H+4e - →2H2(acidic)

[0056] Anode: 4OH - →O2+2H2O+4e - ; Cathode: 4H2O+4e - →2H2+4OH - (Alkaline)

[0057] After carbon dioxide is introduced into the cathode chamber 15 as a cathode reactant, the overall reaction equation becomes: 2CO2→2CO+O2. In an alkaline environment, it can be disassembled into the anode: 4OH - →O2+2H2O+4e - ; Cathode: CO2+H2O+2e - →CO+2OH -. However, under acidic conditions, the occurrence of hydrogen evolution reaction (HER) at the cathode is favorable. Since the hydrogen evolution reaction at the cathode and the carbon dioxide reduction reaction are both competitive reactions, in order to maximize the carbon dioxide conversion efficiency, the occurrence of hydrogen evolution reaction should be suppressed as much as possible, which needs to be achieved by regulating the catalyst and / or reaction conditions. In some preferred embodiments, the electrolysis reaction is carried out in a neutral or alkaline environment, but is not limited thereto.

[0058] refer to Figure 1 , after the electrolyte flows into the anode chamber 14, an oxygen evolution reaction (OER) is carried out, and when the electrolyte flows out of the anode chamber 14, oxygen is taken out together. The selected electrolyte is generally a neutral alkaline electrolyte, such as but not limited to: potassium bicarbonate (KHCO3) aqueous solution. Since the acidic environment is not conducive to the reduction of carbon dioxide, and the alkaline environment will cause the carbon dioxide to neutralize with the acid and base and cause the consumption of carbon dioxide (the neutralized carbon dioxide cannot participate in the reduction reaction), a neutral electrolyte is selected in the best embodiment, but it is not limited to the use of a neutral electrolyte. In some embodiments, the electrolyte contains K2CO3 and CO2.

[0059] refer to Figure 1 After the carbon dioxide is introduced into the cathode chamber 15, a carbon dioxide reduction reaction is performed. By regulating the potential and selecting the catalyst, the carbon dioxide reduction reaction can obtain various carbon-containing products. Table 1 lists possible reduction reactions and carbon-containing products. Figure 1 In the embodiment shown, the cathode comprises a water reduction reaction and a carbon dioxide reduction reaction to obtain two products, hydrogen and carbon monoxide, respectively. However, different cathode products may be obtained according to different reaction conditions and catalysts.

[0060] Table 1

[0061]

[0062]

[0063] Figure 2Schematic diagram showing a carbon dioxide recycling system according to an embodiment of the present invention. In addition to the aforementioned electrochemical reaction module 1, the system also has an electrolyte supply and circulation unit 2. The main components of the electrolyte supply and circulation unit 2 include an anode gas-liquid separator 20, an electrolyte storage tank 21, and a liquid delivery pump 22. The anode gas-liquid separator 20 is connected to the outlet 142 of the anode chamber 14 to separate the gas product in the electrolyte, which is mainly oxygen and may also contain water vapor, a small amount of hydrogen, etc. The separated gas product can be recovered. The electrolyte storage tank 21 is connected to the anode gas-liquid separator 20 to store the degassed electrolyte. The liquid delivery pump 22 is connected to the electrolyte storage tank 21 and the inlet 141 of the anode chamber 14 to transport the electrolyte to the anode chamber 14.

[0064] See also Figure 2 In addition, a flow meter 23, such as a mass flow meter (MFM), may be provided at an appropriate position, such as between the liquid delivery pump 22 and the inlet 141 of the anode chamber 14, to measure the flow of the electrolyte. A float flow meter 24 may be provided near the inlet 141 and the outlet 142 of the anode chamber 14 to observe the flow of the electrolyte. Valves 25-28 may be provided at an appropriate position, such as between the above components. A temperature sensor 29 may be provided at an appropriate position, such as outside the anode chamber 14 of the electrochemical reaction module 1, to monitor the temperature of the electrochemical reaction module 1.

[0065] In a preferred embodiment, the carbon dioxide recycling system has a carbon dioxide gas supply and humidification unit to supply humidified CO2 gas as a reactant for the cathode. Figure 3 FIG. 2 is a schematic diagram showing a carbon dioxide gas supply and humidification unit 3 according to an embodiment of the present invention. Figure 3 The carbon dioxide gas supply and humidification unit 3 mainly includes a CO2 gas supply source 30, a first humidity adjustment device 31, a water storage tank 32, and a delivery pump 33. The CO2 gas supply source 30 supplies carbon dioxide to the first humidity adjustment device 31, and the delivery pump 33 supplies water in the water storage tank 32 to the first humidity adjustment device 31. In the first humidity adjustment device 31, a part of the water humidifies the carbon dioxide gas, and the rest flows back to the water storage tank 32. The water storage tank 32 may have a heater 321 to heat the water in the water storage tank 32.

[0066] See also Figure 3In some embodiments, the first humidity adjustment device 31 includes a housing 310 and an inner tube 311. The inner tube 311 is disposed in the housing 310, and the carbon dioxide gas enters from the inlet 3111 of the inner tube 311 and leaves from the outlet 3112 of the inner tube 311. The housing 310 has an inlet 3101 and an outlet 3102, and a channel 312 is formed between the inner tube 311 and the housing 310. The heated water is transported to the channel 312 through the inlet 3101 of the housing 310 by the delivery pump 33, and leaves from the outlet 3102 of the housing 310. The flow directions of carbon dioxide and water are opposite. The humidification process is driven by the humidity difference between the inside and outside of the inner tube 311. Because the water runs in the channel 312, the humidity of the outer surface of the inner tube 311 is greater than the humidity of the inner surface of the inner tube 311, resulting in the water being absorbed and infiltrated by the tube wall of the inner tube 311, thereby humidifying the carbon dioxide gas in the inner tube 311.

[0067] See also Figure 3 In some embodiments, the inner tube 311 may be, for example, a Nafion (registered trademark) tube from DuPont, whose tube wall is a polymer and contains sulfonic acid groups. Since the sulfonic acid groups of the Nafion tube wall in contact with water are always in a saturated state, the process of water changing from liquid phase to gas phase requires energy consumption, resulting in the cooling of the inner tube 311, thereby slightly reducing the humidity of the carbon dioxide gas, and slightly reducing the efficiency of water exchange. Therefore, preferably, the water storage tank 31 is heated by the heater 321, and the humidification operation is performed with hot water, so that the humidified carbon dioxide has the maximum relative humidity.

[0068] See also Figure 3 The carbon dioxide gas supply and humidification unit 3 may also include an adjustable pressure gas filter 34, a one-way valve 35, valves 36-38, a humidity sensor 39, and a controller 370. The adjustable pressure gas filter 34 is disposed between the first humidity adjustment device 31 and the CO2 gas supply source 30, the one-way valve 35 is disposed between the water storage tank 32 and the delivery pump 33, the valve 36 is disposed between the delivery pump 33 and the inlet 3101 of the housing 310, the valve 37 is disposed before the inlet 3111 of the inner tube 311, the valve 38 is disposed between the adjustable pressure gas filter 34 and the CO2 gas supply source 30, the controller 370 (such as a gas mass flow controller MFC) is disposed between the adjustable pressure gas filter 34 and the valve 37, and the humidity sensor 39 is disposed outside the outlet 3112 of the inner tube 311. The required humidity (%RH) of the carbon dioxide gas can be achieved by controlling the temperature of the heater 321, the water supply of the delivery pump 33, and / or the flow of the valve 36.

[0069] According to the reaction formula listed in Table 1, water can also be a co-reactant in the carbon dioxide reduction reaction, so the exchange membrane 12 that is in continuous operation will gradually be damaged due to water consumption. The carbon dioxide gas supply and humidification unit 3 of the embodiment of the present invention can not only improve the efficiency of the carbon dioxide conversion reaction, but also avoid damage to the exchange membrane 12.

[0070] In some embodiments, the carbon dioxide recycling system further includes a cathode product dehumidification unit to separate the gas phase and liquid phase products of the cathode product. Figure 4 FIG. 4 is a schematic diagram showing a cathode product dehumidification unit 4 according to an embodiment of the present invention. Figure 4 The cathode product dehumidification unit 4 mainly includes a second humidity adjustment device 41 and a gas delivery pump 42 (such as a diaphragm gas delivery pump). Figure 1 ) The gas discharged includes, for example, unreacted carbon dioxide, carbon-containing products (such as carbon monoxide, etc.), hydrogen, and water vapor, etc., and is divided into dry gas 400 and wet gas 402 after passing through the second humidity adjustment device 41.

[0071] See also Figure 4 In some embodiments, the second humidity adjustment device 41 includes a housing 410 and an inner tube 411. The inner tube 411 is disposed in the housing 410, and the gas discharged from the outlet 152 of the cathode chamber 15 enters from the inlet 4111 of the inner tube 411 and leaves from the outlet 4112 of the inner tube 411. The housing 410 has an inlet 4101 and an outlet 4102, and a channel 412 is formed between the inner tube 411 and the housing 410. The gas leaving from the outlet 4112 of the inner tube 411, that is, the dry gas 400, partially flows back into the channel 412 through the inlet 4101 of the housing 410 by the gas delivery pump 42, and leaves from the outlet 4102 of the housing 410. The flow direction of the refluxed dry gas 400 is opposite to that of the gas discharged from the outlet 152 of the cathode chamber 15. The dehumidification process is driven by the humidity difference between the inside and outside of the inner tube 411. Because the dry gas runs in the channel 412, the humidity of the inner surface of the inner tube 411 is greater than the humidity of the outer surface of the inner tube 411, resulting in the water vapor in the gas discharged from the outlet 152 of the cathode chamber 15 being absorbed and infiltrated by the tube wall of the inner tube 311 and escaping from the outer surface of the inner tube, so that the gas in the inner tube 311 is dehumidified, while the dry gas 400 in the channel 410 is humidified. Therefore, the wet gas 402 leaves from the outlet 4102 of the outer shell 410. The dry gas 400 that is not refluxed can be subsequently separated and recycled. In a preferred embodiment, the wet gas 402 is transported by the gas delivery pump 42 to the water storage tank 32 ( Figure 3 In some embodiments, the inner tube 411 may be, for example, a Nafion (registered trademark) tube from DuPont, the tube wall of which is a polymer and contains sulfonic acid groups.

[0072] See also Figure 4 , the cathode product dehumidification unit 4 may also have a flow meter 43, an adjustable pressure gas filter 44, a one-way valve 45, valves 46-50, and a gas composition sensor 40. The adjustable pressure gas filter 44 is disposed between the outlet 112 of the cathode chamber 110 and the inlet 4111 of the inner tube 411 of the second humidity adjustment device 41 to filter impurities in the gas. The flow meter 43 (e.g., a mass flow meter, MFM) is located at the outlet 4112 of the inner tube 411 of the second humidity adjustment device 41 to detect the quality of the cathode output gas and to determine the flow rate after chemical conversion. The one-way valve 45 is located between the outlet 4102 of the housing 410 of the second humidity adjustment device 41 and the gas delivery pump 42. Valves 46-50 are located on the pipeline between the components. Before the dry gas 400 enters the separation and recovery unit, there is a gas composition sensor 40, which is used to detect the composition (vol%) of carbon-containing products (e.g., CO) and CO2 and other gases, which will be used for the control of the carbon dioxide reuse system.

[0073] Figure 5 It is a block diagram showing a carbon dioxide recycling system according to a preferred embodiment of the present invention, which includes the aforementioned electrochemical reaction module 1, an electrolyte supply and circulation unit 2, a carbon dioxide gas supply and humidification unit 3, and a cathode product dehumidification unit 4.

[0074] Fig. 6A The experimental results show that for the electrochemical reaction module of one embodiment of the present invention, under different carbon dioxide supply flow rates (30, 60, 90 sccm), the partial current (partial current) of the cathode product (CO and H2 in this embodiment) and the supply voltage (applied potential) show a linear relationship. The slope of the characteristic line is affected by factors including the internal structure of the electrochemical reaction module, the reaction area, the structure of the chamber flow channel, etc. Under long-term operation conditions, as the chemicals inside / outside the electrochemical reaction module are consumed, its conversion efficiency will inevitably be attenuated to a certain extent, so the slope of the working characteristic line will gradually decrease. In a preferred embodiment, in order to prevent the composition (vol%) of the cathode product from being affected by the attenuation of module performance, feedback control is added to adjust the working conditions of the electrochemical reaction module in a timely manner, thereby maintaining the output ratio of the cathode product.

[0075] Figure 6B The experimental results show that the electrochemical reaction module of one embodiment of the present invention has different reaction areas (7×7cm 2 ; 10×10cm 2 ), the peak current of the module shows a linear relationship with the supply flow rate (sccm) of carbon dioxide.

[0076] Fig. 7A The experimental results show the concentration (vol%) of cathode exhaust gas (CO, H2, CO2 in this embodiment) at different input voltages for an electrochemical reaction module of an embodiment of the present invention. If the composition of the cathode product is required to fall into the desired ratio, the input voltage of the electrochemical reaction module must be controlled within a certain range.

[0077] Figure 7B The experimental results show the concentration (vol%) of the cathode exhaust gas (CO, H2, CO2 in this embodiment) at different input voltages for an electrochemical reaction module of an embodiment of the present invention. In some embodiments, by controlling the program parameters, the concentration of carbon-containing products (such as CO) in the cathode exhaust gas is greater than 70 vol%, the concentration of CO2 is less than 15 vol%, and the concentration of H2 is less than 15 vol%.

[0078] Figure 8 1 is a block diagram showing the main control loop of a carbon dioxide recycling system according to an embodiment of the present invention. The input command (target) of the main control loop is selected as the composition (vol%) of a carbon-containing product (such as CO), the control variable is the supply voltage of the power supply 13, and the feedback process variable is the gas proportion (vol%) of the carbon-containing product (such as CO) measured by the gas composition sensor 40. Because the entire system is in continuous and long-term operation, the gas composition obtained by the gas composition sensor 40 captures a moving average over a period of time as a feedback value. The PID controller (proportional-integral-differential controller) calculates a new control variable based on the error between the input command (target) and the feedback process variable. In addition, considering the consumption of chemicals inside / outside the electrochemical reaction module 1, the moving average change (ΔCO2%) of the CO2 composition (%) measured by the gas composition sensor 40 is fed back and used as a feedforward control quantity after adaptive gain tuning to compensate for changes in the CO2 reduction conversion characteristics.

[0079] In addition to the main control loop, the supply and control loop of the chemical raw materials for the anode and cathode of the electrochemical reaction module 1 must also be taken into consideration.

[0080] Fig. 92 is a block diagram showing an anode electrolyte flow control loop of a carbon dioxide recycling system according to an embodiment of the present invention. The input command (target) is the target flow rate of the electrolyte, the process variable (process variable) is the electrolyte flow rate measured by the flow meter 23, and the control variable is the speed of the liquid delivery pump 22. The PID controller calculates a new control variable based on the error between the input command (target) and the feedback process variable (process variable). In addition, the temperature of the electrochemical module 1 measured by the temperature sensor 29 is used as the basis for feedforward control. The speed of the liquid delivery pump 22 must be limited within a certain range according to the process requirements to ensure the rationality and safety of the operation.

[0081] Fig.10 : is a block diagram showing a cathode residual CO2 flow control loop of a carbon dioxide recycling system according to an embodiment of the present invention. The input command (target) is the residual carbon dioxide target flow rate of the cathode chamber, and the residual carbon dioxide refers to the unreacted carbon dioxide. The controller 370 (such as a mass flow controller MFC) serves as the main body of CO2 flow control, and the control variable is its flow input (flow command). The residual carbon dioxide flow rate measured by the flow meter 43 (such as a mass flow meter, MFM) is a process variable (process variable) and serves as a feedback value. The PID controller calculates a new control variable based on the error between the input command (target) and the feedback process variable (process variable). In addition, the change in the moving average value (ΔCO2%) of the CO2 composition (%) measured by the gas composition sensor 40 is proportionally adjusted (gain tuning) and used as the basis for feedforward control. The flow setting of the controller 370 must have an upper / limit.

[0082] Fig.111 is a block diagram showing a cathode CO2 humidity control loop of a carbon dioxide recycling system according to an embodiment of the present invention. The input command (target) is the target humidity value (%RH) of the carbon dioxide input to the cathode chamber. The first humidity adjustment device 31 is the main body of the CO2 humidity control, and the control variable can be one of the following variables: the temperature of the heater 321, the water supply of the delivery pump 33, and the flow rate of the valve 36. The process variable is the CO2 gas humidity measured by the humidity sensor 39, which is also used as the feedback value of the PID control. The PID controller calculates the new control variable based on the error between the input command (target) and the feedback process variable (process variable). The control of CO2 humidity must have an upper / lower limit setting. The change in the moving average value (ΔCO2%) of the CO2 composition (%) measured by the gas composition sensor 40 is proportionally adjusted (gain tuning) and used as the basis for feedforward control. In some embodiments, the relative humidity of the carbon dioxide input to the cathode chamber is controlled between 60% and 100%, and more preferably between 70% and 80%.

[0083] The control components of each circuit are organized into the following Table 2:

[0084] Table 2

[0085]

[0086] The carbon dioxide recycling system provided by the present invention can be small-scale or large-scale for ton-level carbon dioxide consumption. In some embodiments, the carbon dioxide recycling system can have multiple electrochemical reaction modules connected in parallel. Depending on the scale, the various devices mentioned in the carbon dioxide recycling system of the embodiment of the present invention can be replaced by other devices or units with the same function.

[0087] The above embodiments of the present invention are only for illustrating the technical ideas and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly. They cannot be used to limit the patent scope of the present invention. That is, all other equivalent changes or modifications that do not deviate from the spirit disclosed by the present invention are included in the scope disclosed by the present invention and should be included in the scope of the patent application.

Claims

1. A carbon dioxide recycling system, characterized in that: Include: Electrochemical reaction module, including: power supply; Anode, connected to the positive pole of the power supply; Cathode, connected to the negative pole of the power supply; an anode chamber, located on one side of the anode, containing an electrolyte that undergoes an oxidation reaction with the anode to produce oxygen; and a cathode chamber, located on one side of the cathode, containing carbon dioxide that undergoes a reduction reaction with the cathode to produce a carbonaceous product; as well as an exchange membrane located between the anode and the cathode; and The carbon dioxide gas supply and humidification unit is connected to the inlet of the cathode chamber to provide humidified carbon dioxide gas to the cathode chamber.

2. The carbon dioxide recycling system according to claim 1, characterized in that: It also includes an electrolyte supply and circulation unit, which includes: an anode gas-liquid separator connected to the outlet of the anode chamber to separate gaseous products in the electrolyte; An electrolyte storage tank connected to the anode gas-liquid separator to store the degassed electrolyte; as well as The liquid delivery pump is connected to the electrolyte storage tank and the inlet of the anode chamber to deliver the electrolyte to the anode chamber.

3. The carbon dioxide recycling system according to claim 1, characterized in that: The carbon dioxide gas supply and humidification unit includes a carbon dioxide gas supply source, a first humidity adjustment device, a water storage tank, and a delivery pump, wherein the carbon dioxide gas supply source supplies carbon dioxide gas to the first humidity adjustment device, and the delivery pump supplies water in the water storage tank to the first humidity adjustment device to humidify the carbon dioxide gas in the first humidity adjustment device.

4. The carbon dioxide recycling system according to claim 3, characterized in that: The water storage tank further includes a heater for heating the water in the water storage tank.

5. The carbon dioxide recycling system according to claim 3, characterized in that: It further comprises a cathode product dehumidification unit, which comprises a second humidity adjusting device. The gas discharged from the outlet of the cathode chamber flows through the second humidity adjusting device and then discharges dry gas, the humidity of the dry gas is lower than the humidity of the gas discharged from the outlet of the cathode chamber, and a part of the dry gas flows back into the second humidity adjusting device and is humidified by the gas discharged from the outlet of the cathode chamber and then discharges humid gas, the humidity of the humid gas is greater than the humidity of the dry gas.

6. The carbon dioxide recycling system according to claim 5, characterized in that: The humid gas is transported into the water storage tank.

7. The carbon dioxide recycling system according to claim 1, characterized in that: It also includes a main control loop, the input command of which is the target composition (vol%) of the carbon-containing product, the feedback process variable is the composition (vol%) of the carbon-containing product output by the cathode chamber, the control variable is the supply voltage of the power supply, and the main control loop further includes using the average value of the CO2 change output by the cathode chamber as the feedforward control of the main control loop.

8. The carbon dioxide recycling system according to claim 2, characterized in that: It also includes an anode electrolyte flow control loop, whose input command is the target flow of the electrolyte, the feedback process variable is the measured flow of the electrolyte, and the control variable is the rotational speed of the liquid delivery pump. The anode electrolyte flow control loop further includes using the measured temperature of the electrochemical reaction module as feedforward control of the anode electrolyte flow control loop.

9. The carbon dioxide recycling system according to claim 3, characterized in that: It also includes a residual carbon dioxide flow control loop, whose input command is the residual carbon dioxide target flow, the feedback process variable is the measured flow of the residual carbon dioxide output from the cathode chamber, and the control variable is the flow input value of the controller located between the carbon dioxide gas supply source and the first humidity adjustment device. The residual carbon dioxide flow control loop further includes using the average value of the CO2 change output from the cathode chamber as the feedforward control of the carbon dioxide flow control loop.

10. The carbon dioxide recycling system according to claim 4, characterized in that: It also includes a carbon dioxide humidity control loop, whose input command is the target CO2 humidity, the feedback process variable is the measured humidity of the carbon dioxide before the inlet of the cathode chamber, the control variable is the temperature of the heater, the water supply of the delivery pump, or the flow of the valve located between the first humidity adjustment device and the delivery pump, and the carbon dioxide humidity control loop further includes using the average value of the CO2 change output from the cathode chamber as the feedforward control of the carbon dioxide humidity control loop.

11. The carbon dioxide recycling system according to claim 1, characterized in that: The relative humidity of the carbon dioxide gas input into the cathode chamber is between 70% and 80%.

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