A system and method for capturing carbon dioxide from seawater

Abstract

The present application relates to a kind of system and method for capturing carbon dioxide from seawater, and the system for capturing carbon dioxide from seawater includes electrolytic device and degassing device;Electrolytic device includes first battery unit, first power supply, first switch and second switch, first battery unit has first electrolyte cavity, first power supply, first switch and first battery unit are connected in series, and second switch is connected with first battery unit in parallel;Degassing device is communicated with first electrolyte cavity, to remove gas in solution transported from first electrolyte cavity.The overall energy consumption of the scheme is lower, and there is no need to use high-cost components, low cost, and no toxic chemical reagent is used, safe and environmentally friendly, while there is no byproduct in the process of decarburization.

Description

Technical Field

[0001] This invention relates to the field of carbon capture technology, and more particularly to a system and method for capturing carbon dioxide from seawater. Background Technology

[0002] The concentration of carbon dioxide in the atmosphere and ocean is always in equilibrium. Removing carbon dioxide from seawater through carbon capture technology can effectively mitigate the downward trend of ocean pH and protect marine biodiversity. Currently, carbon dioxide capture technologies for seawater include electrolysis and bipolar membrane electrodialysis.

[0003] For example, patent CN217324342U discloses a device for membrane electrolysis of seawater to produce hydrogen and capture carbon dioxide. This device adds seawater into a hydrogen storage ion tank, a medium tank, and a second cathode tank through a water supply device, and adds fresh water into the electrolysis cell. When the power supply is turned on, the anode and cathode of the power supply electrolyze the fresh water in the first cathode tank and the seawater in the second cathode tank, respectively. Carbon dioxide in the flue gas dissolves in the alkaline seawater in the second cathode tank. At the same time, cations in the medium tank enter the second cathode tank to accelerate the dissolution of carbon dioxide. After the dissolution reaches saturation, the seawater in the hydrogen storage ion tank, the medium tank, and the second cathode tank is discharged through a discharge device, which improves the carbon dioxide capture efficiency of the equipment.

[0004] However, the system requires multiple ion-selective permeable membranes, and its high resistivity and high overpotential of the reaction result in high overall energy consumption in the decarbonization process. Summary of the Invention

[0005] In view of this, it is necessary to provide a system for capturing carbon dioxide from seawater to solve the technical problem of relatively high overall energy consumption of existing seawater carbon dioxide capture devices.

[0006] This invention provides a system for capturing carbon dioxide from seawater, the system comprising:

[0007] An electrolysis apparatus includes a first battery cell, a first power supply, a first switch, and a second switch. The first battery cell has a first electrolyte chamber. The first power supply, the first switch, and the first battery cell are connected in series. The second switch is connected in parallel with the first battery cell.

[0008] A degassing device, connected to the first electrolyte chamber, is used to remove gas from the solution transported from the first electrolyte chamber.

[0009] Optionally, the electrolysis device further includes a second battery unit, a second power supply, a third switch and a fourth switch. The second battery unit has a second electrolyte chamber. The second power supply, the third switch and the second battery unit are connected in series, and the fourth switch is connected in parallel with the second battery unit.

[0010] The degassing device is also connected to the second electrolyte chamber.

[0011] Optionally, the system for capturing carbon dioxide from seawater further includes a seawater pump, a seawater filter, a main input pipe, two input valves, and two input branch pipes. The two input branch pipes are respectively connected to the first electrolyte chamber and the second electrolyte chamber. One end of the main input pipe is connected to the two input branch pipes, and the other end is sequentially connected to the seawater filter and the seawater pump. The two input valves are respectively located on the two input branch pipes.

[0012] Optionally, the system for capturing carbon dioxide from seawater further includes two connecting pipes, two output pipes, and two output valves. One end of each of the two connecting pipes is connected to the first electrolyte chamber and the second electrolysis chamber, respectively, and the other end is connected to the two output pipes. The input branch pipe is connected to the connection between the connecting pipes and the output pipes, and the two output valves are respectively installed on the two output pipes.

[0013] Optionally, the system for capturing carbon dioxide from seawater further includes two first pH sensors, which are respectively disposed on the two connecting pipes.

[0014] Optionally, a second pH sensor is provided on the infusion line between the degassing device and the first electrolyte chamber; and / or, a third pH sensor is provided on the infusion line between the degassing device and the second electrolyte chamber.

[0015] Optionally, the inner cavity of the degassing device is provided with a carbon dioxide selective permeation membrane to divide the inner cavity of the degassing device into a solution cavity and a gas cavity;

[0016] The system for capturing carbon dioxide from seawater also includes a gas delivery pipe, a vacuum gauge, a vacuum pump, a carbon dioxide compressor, and a storage tank. One end of the gas delivery pipe is connected to the gas chamber, and the other end is connected to the storage tank. The vacuum gauge, the vacuum pump, and the carbon dioxide compressor are sequentially arranged on the gas delivery pipe in a direction away from the gas chamber.

[0017] Optionally, the carbon dioxide selective permeation membrane is a hollow fiber membrane.

[0018] Optionally, the positive and negative terminals of the first battery cell are respectively connected to fifth wires. The electrolysis device further includes a first wire, a second wire, and a first current sensor. The two ends of the first wire and the second wire are respectively electrically connected to two of the fifth wires. The first power supply and the first switch are located on the first wire, the second switch is located on the second wire, and the first current sensor is located on one of the fifth wires; and / or,

[0019] The positive and negative terminals of the second battery cell are respectively connected to a sixth wire. The electrolysis device also includes a third wire, a fourth wire, and a second current sensor. The two ends of the third wire and the fourth wire are respectively electrically connected to two of the sixth wires. The second power supply and the third switch are located on the third wire, the second switch is located on the fourth wire, and the second current sensor is located on one of the sixth wires.

[0020] Furthermore, the present invention also provides a method for capturing carbon dioxide from seawater, for use with the system for capturing carbon dioxide from seawater as described above, the method for capturing carbon dioxide from seawater comprising the following steps:

[0021] S1: Input carbon-rich seawater from the outside into the first electrolyte chamber, and disconnect the first switch and the fourth switch, and close the second switch and the third switch to acidify the carbon-rich seawater in the first electrolyte chamber.

[0022] S2: The seawater that has been acidified by the first electrolyte chamber is transported to the degassing device, which separates the acidified seawater from carbon dioxide;

[0023] S3: The decarbonated seawater from the degassing device is transported to the second electrolyte chamber, and the decarbonated seawater in the second electrolyte chamber is alkalized. The treated low-carbonated seawater with normal pH is then output to the external environment.

[0024] S4: Repeat steps S1 to S3 until the current in the loop of the second conductor is lower than the set value;

[0025] S5: When the current in the circuit of the second conductor is lower than the set value, the external carbon-rich seawater is input into the second electrolyte chamber, and the first switch and the fourth switch are closed, and the second switch and the third switch are opened, so as to acidify the carbon-rich seawater in the second electrolyte chamber.

[0026] S5: The seawater that has been acidified by the second electrolyte chamber is transported to the degassing device, which separates the acidified seawater from carbon dioxide;

[0027] S6: The decarbonated seawater from the degassing device is transported to the first electrolyte chamber, and the decarbonated seawater in the first electrolyte chamber is alkalized. Then, the treated low-carbonated seawater with normal pH is output to the external environment.

[0028] S7: Repeat steps S5 to S6 until the current in the loop of the third conductor is lower than the set value;

[0029] S8: When the current in the loop of the third conductor is lower than the set value, repeat the above steps S1 to S7.

[0030] Compared with existing technologies, the system for capturing carbon dioxide from seawater provided by this invention first transports carbon-rich seawater to a first electrolyte chamber, disconnects a first switch, and simultaneously closes a second switch, thereby acidifying the carbon-rich seawater in the first electrolyte chamber and enabling the capture of CO32- from the seawater. 2- and HCO3 - The equilibrium shifts towards CO2(g); then the acidified seawater is transported to a degassing device to effectively separate gaseous carbon dioxide from the seawater. The degassed, low-carbonated seawater is then transported to the first electrolyte chamber, and the first switch is closed while the second switch is opened, causing the seawater to alkalize until its pH returns to its initial state before being discharged into the external environment. In comparison, this invention requires only 122 kilojoules of energy to remove 1 mole of carbon dioxide, resulting in lower overall energy consumption. It also eliminates the need for expensive components, making it low-cost, safe, and environmentally friendly as it does not use toxic chemicals, and the decarbonization process produces no byproducts.

[0031] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail in the following embodiments and their accompanying drawings. Attached Figure Description

[0032] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0033] Figure 1 This is a schematic diagram of an embodiment of the system for capturing carbon dioxide from seawater provided by the present invention.

[0034] Explanation of reference numerals in the attached figures:

[0035] 100. A system for capturing carbon dioxide from seawater; 1. First battery cell; 11. Positive electrode of the first battery cell; 12. Negative electrode of the first battery cell; 13. First current sensor; 14. Second pH sensor; 15. First switch; 16. Second switch; 17. First power supply; 18. First adjustable resistor; 2. Degassing device; 21. Vacuum gauge; 22. Vacuum pump; 23. Carbon dioxide compressor; 24. Storage tank; 3. Second battery cell; 31. Positive electrode of the second battery cell; 32. Negative electrode of the second battery cell; 33. Second current sensor; 34. Third pH sensor; 35. Third switch; 36. Fourth switch; 37. Second power supply; 38. Second adjustable resistor; 4. Seawater pump; 41. Seawater filter; 42. First input valve; 43. Second input valve; 44. Main first pH sensor; 45. Secondary first pH sensor; 46. First output valve; 47. Second output valve. Detailed Implementation

[0036] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0037] Please see Figure 1 The system 100 for capturing carbon dioxide from seawater includes an electrolysis device and a degassing device 2. The electrolysis device includes a first battery unit 1, a first power supply 17, a first switch 15, and a second switch 16. The first battery unit 1 has a first electrolyte chamber. The first power supply 17, the first switch 15, and the first battery unit 1 are connected in series. The second switch 16 is connected in parallel with the first battery unit 1. The degassing device 2 is connected to the first electrolyte chamber to remove gas from the solution transported from the first electrolyte chamber. Specifically, the electrolysis device also includes a first wire and a second wire. The two ends of the first wire and the second wire are electrically connected to the positive electrode 11 and the negative electrode 12 of the first battery unit, respectively. The first power supply 17 is located on the first wire, with its positive electrode connected to the positive electrode 11 of the first battery unit and its negative electrode connected to the negative electrode 12 of the first battery unit. The first switch 15 is located on the first wire, and the second switch 16 is located on the second wire.

[0038] In the system 100 for capturing carbon dioxide from seawater provided by the present invention, carbon-rich seawater is first transported to a first electrolyte chamber, and a first switch 15 is disconnected while a second switch 16 is closed, thereby acidifying the carbon-rich seawater in the first electrolyte chamber and enabling the CO3 in the seawater to be captured. 2- and HCO 3-The equilibrium shifts towards CO2(g); then the acidified seawater is fed to degassing device 2 to effectively separate gaseous carbon dioxide from the seawater. The degassed, low-carbonated seawater from degassing device 2 is then fed into the first electrolyte chamber, and the first switch 15 is closed while the second switch 16 is opened, causing the seawater to alkalize until its pH returns to its initial state, before being discharged into the external environment. In comparison, this invention requires only 122 kilojoules of energy to remove 1 mole of carbon dioxide, resulting in lower overall energy consumption. It also eliminates the need for expensive components, is cost-effective, and does not use toxic chemicals, making it safe and environmentally friendly. Furthermore, the decarbonization process produces no byproducts.

[0039] It should be noted that, in this embodiment, adjustable resistors are provided on the second and fourth wires respectively. For ease of explanation, the adjustable resistor on the second wire is defined as the first adjustable resistor 18, and the adjustable resistor on the fourth wire is defined as the second adjustable resistor 38.

[0040] Furthermore, the electrolysis device also includes a second battery unit 3, a second power supply 37, a third switch 35, and a fourth switch 36. The second battery unit 3 has a second electrolyte chamber. The second power supply 37, the third switch 35, and the second battery unit 3 are connected in series, and the fourth switch 36 is connected in parallel with the second battery unit 3. The degassing device 2 is also connected to the second electrolyte chamber. The positive terminal of the second power supply 37 is electrically connected to the positive terminal 31 of the second battery unit, and the negative terminal of the second power supply 37 is electrically connected to the negative terminal 32 of the second battery unit. Specifically, the electrolysis device also includes a third wire and a fourth wire. The two ends of the third wire and the fourth wire are electrically connected to the positive terminal 31 and the negative terminal 32 of the second battery unit, respectively. The second power supply 37 is located on the third wire, with its positive terminal connected to the positive terminal 31 of the second battery unit and its negative terminal connected to the negative terminal 32 of the second battery unit. The third switch 35 is located on the third wire, and the fourth switch 36 is located on the fourth wire. In this scheme, two sets of battery units are set up at the same time to work together to improve the carbon dioxide capture efficiency. The specific capture process is described later in the method for capturing carbon dioxide from seawater.

[0041] Furthermore, the system 100 for capturing carbon dioxide from seawater also includes a seawater pump 4, a seawater filter 41, a main input pipe, two input valves, and two input branch pipes. The two input branch pipes are respectively connected to the first electrolyte chamber and the second electrolyte chamber. One end of the main input pipe is connected to the two input branch pipes, and the other end is sequentially connected to the seawater filter 41 and the seawater pump 4. The two input valves are respectively located on the two input branch pipes. In this way, the water delivery efficiency can be improved by the seawater pump 4, and foreign matter such as silt in the seawater can be filtered out by the seawater filter 41. It should be noted that, for ease of understanding, the input valve corresponding to the first battery unit 1 is defined as the first input valve 42, and the input valve corresponding to the second battery unit 3 is defined as the second input valve 43.

[0042] Furthermore, the system 100 for capturing carbon dioxide from seawater also includes two connecting pipes, two output pipes, and two output valves. One end of each connecting pipe is connected to the first electrolyte chamber and the second electrolysis chamber, respectively, and the other end is connected to the two output pipes. An input branch pipe is connected to the connection between the connecting pipes and the output pipes. The two output valves are respectively located on the two output pipes. It should be noted that the output valve corresponding to the first battery unit 1 is defined as the first output valve 46, and the output valve corresponding to the second battery unit 3 is defined as the second output valve 47.

[0043] Furthermore, the system 100 for capturing carbon dioxide from seawater also includes two first pH sensors, each mounted on a separate connecting pipe. This allows for real-time monitoring of the pH level of the seawater in the output pipe, ensuring the pH of the output seawater remains normal and improving safety. It should be noted that, for ease of understanding, the first pH sensor corresponding to the first battery unit 1 is defined as the primary first pH sensor 44, and the first pH sensor corresponding to the second battery unit 3 is defined as the secondary first pH sensor 45.

[0044] Furthermore, a second pH sensor 14 is installed on the inlet pipeline between the degassing device 2 and the first electrolyte chamber; and / or, a third pH sensor 34 is installed on the inlet pipeline between the degassing device 2 and the second electrolyte chamber. This allows operators to easily monitor the pH of seawater as it flows through the first electrolyte chamber, the degassing device 2, and the second electrolyte chamber in real time, thereby improving the accuracy of pH adjustment.

[0045] Furthermore, the inner cavity of the degassing device 2 is divided into a solution cavity and a gas cavity by a carbon dioxide selective permeation membrane. The system 100 for capturing carbon dioxide from seawater also includes a gas delivery pipe, a vacuum gauge 21, a vacuum pump 22, a carbon dioxide compressor 23, and a storage tank 24. One end of the gas delivery pipe is connected to the gas cavity, and the other end is connected to the storage tank 24. The vacuum gauge 21, the vacuum pump 22, and the carbon dioxide compressor 23 are sequentially arranged on the gas delivery pipe in a direction away from the gas cavity. In this way, the vacuum pump 22 can keep the gas cavity under negative pressure to improve the carbon dioxide capture efficiency. Specifically, in this scheme, the carbon dioxide selective permeation membrane is a hollow fiber membrane.

[0046] Furthermore, the positive electrode 11 and negative electrode 12 of the first battery unit are respectively connected to a fifth wire, and the two ends of the first and second wires are respectively connected to two fifth wires. The electrolysis device also includes a first current sensor 13, which is disposed on a fifth wire. The positive electrode 31 and negative electrode 32 of the second battery unit are respectively connected to a sixth wire, and the two ends of the third and fourth wires are respectively connected to two sixth wires. The electrolysis device also includes a second current sensor 33, which is disposed on a sixth wire. In this scheme, the acidification capacity of the electrolysis cell unit is judged in real time by the first current sensor 13 and the second current sensor 33, which facilitates the operator to adjust the flow direction of the carbon-rich seawater in a timely manner.

[0047] Furthermore, the present invention also provides a method for capturing carbon dioxide from seawater, for use in the system 100 for capturing carbon dioxide from seawater as described above, the method for capturing carbon dioxide from seawater comprising the following steps:

[0048] S1: Input the carbon-rich seawater from the outside into the first electrolyte chamber, and disconnect the first switch 15 and the fourth switch 36, and close the second switch 16 and the third switch 35 to acidify the carbon-rich seawater in the first electrolyte chamber.

[0049] S2: The seawater that has been acidified by the first electrolyte chamber is transported to the degassing device 2, where the degassing device 2 separates the acidified seawater from carbon dioxide;

[0050] S3: The low-carbonated seawater from the degassing device 2 is transported to the second electrolyte chamber, and the low-carbonated seawater in the second electrolyte chamber is alkalized. The treated low-carbonated seawater with normal pH is then output to the external environment.

[0051] S4: Repeat steps S1 to S3 until the current in the loop of the second conductor is lower than the set value;

[0052] S5: When the current in the circuit of the second conductor is lower than the set value, the external carbon-rich seawater is input into the second electrolyte chamber, and the first switch 15 and the fourth switch 36 are closed, and the second switch 16 and the third switch 35 are opened to acidify the carbon-rich seawater in the second electrolyte chamber.

[0053] S5: The seawater that has been acidified by the second electrolyte chamber is transported to the degassing device 2, where the acidified seawater and carbon dioxide are separated.

[0054] S6: The low-carbonated seawater from the degassing device 2 is transported to the first electrolyte chamber, and the low-carbonated seawater in the first electrolyte chamber is alkalized. Then, the treated low-carbonated seawater with normal pH is output to the external environment.

[0055] S7: Repeat steps S5 to S6 until the current in the loop of the third conductor is lower than the set value;

[0056] S8: When the current in the loop of the third conductor is lower than the set value, repeat the above steps S1 to S7.

[0057] It should be noted that, based on all the embodiments of the system 100 for capturing carbon dioxide from seawater described above, the specific steps and principles of the method for capturing carbon dioxide from seawater according to the present invention are explained as follows:

[0058] Carbon dioxide exists in seawater primarily in four forms: CO2, ... H2CO3 and CO3 2- The four forms of carbon dioxide exist in a balance as follows: under normal circumstances, the four forms of carbon dioxide in seawater are basically in equilibrium.

[0059]

[0060]

[0061]

[0062]

[0063] Meanwhile, according to the literature, carbon dioxide in seawater mainly exists as... and CO3 2- To simplify calculations, it is assumed that carbon dioxide exists entirely in seawater as CO3. 2- It exists in the form of carbon dioxide. The known content of carbon dioxide in seawater is approximately 2 × 10⁻⁶. -3 mol / L, then the CO3 in seawater 2- The content is also 2×10 -3 mol / L. At the same time, seawater is also rich in Cl. - .

[0064] From the balance relationship of the four components of carbon dioxide above, it can be seen that when H+ in seawater... + As the concentration of H+ in seawater increases, the pH value of the seawater decreases, leading to acidification. This shifts the equilibrium towards the formation of gaseous CO2 (i.e., CO2(g)), meaning carbon dioxide will desorb from the seawater into the atmosphere. Conversely, when the concentration of H+ in the seawater decreases... + When the ion concentration decreases, the pH value of seawater increases, the seawater becomes alkalized, and the reaction shifts towards the production of CO3. 2- Directional movement promotes the dissolution of carbon dioxide into seawater.

[0065] When the system 100 for capturing carbon dioxide from seawater in this scheme starts working, firstly, the seawater pump 4, the first input valve 42, and the second output valve 47 are turned on; then, the second input valve 43 and the first output valve 46 are closed; the first switch 15 is disconnected; the second switch 16 is closed; the third switch 35 is closed; and the fourth switch 36 is disconnected. The vacuum pump 22 and the carbon dioxide compressor 23 are then started. The system captures carbon-rich seawater from the external environment, containing CO32-. 2- The content is also 2×10 -3 The carbon-rich seawater has a concentration of mol / L, a flow rate of 1000 SL / min, and an initial pH of 8.2. After being pressurized to 0.3 MPa by seawater pump 4, it enters seawater filter 41 to remove impurities such as silt. It then passes through the first input valve 42 and the main first pH sensor 44 before entering the first electrolyte chamber. The positive electrode 11 of the first battery unit uses AgCl as the electrode material, and the negative electrode 12 uses Bi as the electrode material. When the carbon-rich seawater flows through the first electrolyte chamber, the first battery unit 1 is connected through the first adjustable resistor 18, meaning the first battery unit 1 discharges into the first adjustable resistor 18. At this time, the following reaction occurs inside the battery:

[0066] Positive electrode: AgCl + e - →Ag+Cl -

[0067] Negative electrode: Bi + Cl - +H₂O→BiOCl+2H + +3e -

[0068] Overall reaction:

[0069] Adjust the first adjustable resistor 18 and observe the battery discharge current through the first current sensor 13. Stop adjusting when the battery discharge current reaches 10A to maintain a stable current. At this time, 6.24 × 10⁻⁶ A / s. 19 4.16 × 10⁻⁶ electrons flow from the negative electrode 12 to the positive electrode 11 of the first battery cell. According to the above reaction equation, this is 4.16 × 10⁻⁶ electrons per second. 19 H + The electrolyte is transferred from the negative electrode to the battery electrolyte, specifically to the carbon-rich seawater flowing through the electrolyte chamber of the first battery cell 1. The above-mentioned H... + The entry of these substances causes seawater acidification, i.e., a decrease in pH. Based on the analysis above, this decrease in pH will cause carbon dioxide to desorb from the seawater, forming a mixture of seawater and carbon dioxide.

[0070] A mixture of seawater and carbon dioxide enters the degassing device 2 via the second pH sensor 14. The degassing device 2 uses a material with selective carbon dioxide permeability; in this embodiment, a hollow fiber membrane module is used. This hollow fiber membrane module contains a large number of hollow fibers with tiny pores on the fiber walls. Water molecules cannot pass through these pores, but carbon dioxide molecules can. The membrane fiber material is modified PP (polypropylene), with an inner diameter of 0.22 mm, an outer diameter of 0.3 mm, and a membrane area of ​​approximately 80 m². 2 Under the action of vacuum pump 22, a negative pressure of approximately 2000 Pa (absolute pressure) is generated inside the membrane module. Under this negative pressure, carbon dioxide gas is continuously separated from the mixed fluid. The separated carbon dioxide gas passes through vacuum gauge 21 and vacuum pump 22 before entering carbon dioxide compressor 23. At this point, the carbon dioxide gas is assumed to be at room temperature, approximately 20°C. Vacuum pump 22 compresses the carbon dioxide gas to approximately 5.8 MPa, at which point the carbon dioxide changes from a gaseous state to a liquid state. The liquefied carbon dioxide is then transported through pipelines to storage tank 24 for storage.

[0071] The decarbonized seawater enters the second electrolyte chamber of the second battery unit 3 via the third pH sensor 34. The positive electrode 31 of the second battery unit uses Ag as the electrode material, and the negative electrode 32 uses BiOCl as the electrode material. At this time, the second battery unit 3 is connected to the second power supply 37 via the third switch 35 and the third wire, meaning the second power supply 37 charges the second battery unit 3 through the third wire. During this time, the following reaction will occur inside the second battery unit 3:

[0072] Positive electrode: Ag + Cl - →AgCl+e -

[0073] Negative electrode: BiOCl + 2H + +3e - →Bi+Cl - +H2O

[0074] Overall reaction:

[0075] The charging current of the second battery cell 3 is controlled at 10A by the second power supply 37. At this time, 6.24 × 10⁻⁶ A / s will be charged per second. 19 4.16 × 10⁻⁶ electrons are transferred from the positive electrode 31 to the negative electrode 32 of the second battery cell. According to the battery reaction equation above, 4.16 × 10⁻⁶ electrons are transferred per second. 19 H + The electrolyte is transferred from the battery electrolyte, specifically from the low-carbon seawater flowing through the second battery cell 3, to the negative electrode 32. It loses H₂. +This causes the low-carbon seawater to become alkalized, i.e., its pH value increases. This is because the seawater receives H+ in the first battery cell 1. + The quantity, and the H lost by seawater in the second battery cell 3 + The quantity is the same, therefore, the seawater pH is restored to its initial state, that is, the pH value is restored to 8.2. The low-carbon seawater with a normal pH value from the second electrolyte chamber of the second battery unit 3 is returned to the external environment through the secondary first acid-base sensor 45 and the drain valve second output valve 47.

[0076] When the reading of the first current sensor 13 is lower than the set value (0.5A in this embodiment), it indicates that the first battery unit 1 is basically depleted. At this time, it is necessary to adjust the direction of the carbon-rich seawater. That is, keep the seawater pump 4, vacuum pump 22, and carbon dioxide compressor 23 on, close the first input valve 42 (seawater valve) and the second output valve 47, open the second input valve 43 and the first output valve 46, close the first switch 15, open the second switch 16, open the third switch 35, and close the fourth switch 36.

[0077] Carbon-rich seawater from the external environment is pressurized to 0.3 MPa by seawater pump 4 and enters seawater filter 41 at a flow rate of 1000 SL / min to filter out impurities such as silt. After passing through the second input valve 43 and the secondary first pH sensor 45, it enters the second electrolyte chamber of the second battery unit 3. After the initial reaction, the positive electrode material of the second battery unit has been converted to AgCl, and the negative electrode material has been converted to Bi. At this time, the second battery unit 3 is connected to the second adjustable resistor 38 through the fourth wire, that is, the second battery unit 3 discharges to the second adjustable resistor 38 through the fourth switch 36 and the fourth wire. At this time, the following reaction occurs inside the battery:

[0078] Positive electrode: AgCl + e - →Ag+Cl -

[0079] Negative electrode: Bi + Cl - +H₂O→BiOCl+2H + +3e -

[0080] Overall reaction:

[0081] Adjust the second adjustable resistor 38 and observe the battery discharge current through the second current sensor 33. Stop adjusting when the battery discharge current reaches 10A. At this time, 6.24 × 10⁻⁶ A / s. 19 4.16 × 10⁻⁶ electrons flow from the negative electrode 32 to the positive electrode 31 of the second battery cell 3. According to the above reaction equation, this is 4.16 × 10⁻⁶ electrons per second. 19 H +The electrolyte is transferred from the negative electrode to the battery electrolyte, specifically to the carbon-rich seawater flowing through the electrolyte chamber of the second battery cell 3. The above-mentioned H... + The entry of these substances causes seawater acidification, i.e., a decrease in pH. Based on the analysis above, this decrease in pH will cause carbon dioxide to desorb from the seawater, forming a mixture of seawater and carbon dioxide.

[0082] A mixture of seawater and carbon dioxide enters the degassing device 2 via a third pH sensor 34. The degassing device 2 uses a material with selective carbon dioxide permeability; in this embodiment, a hollow fiber membrane module is used. This hollow fiber membrane module contains a large number of hollow fibers with tiny pores on the fiber walls. Water molecules cannot pass through these pores, but carbon dioxide gas molecules can. The membrane fiber material is modified PP material, with an inner diameter of 0.22 mm, an outer diameter of 0.3 mm, and a membrane area of ​​approximately 80 m². 2 Under the action of vacuum pump 22, a negative pressure of approximately 2000 Pa (absolute pressure) is generated inside the membrane module. Under this negative pressure, carbon dioxide gas is continuously separated from the mixed fluid. The separated carbon dioxide gas passes through vacuum gauge 21 and vacuum pump 22 before entering carbon dioxide compressor 23. At this point, the carbon dioxide gas is assumed to be at room temperature, approximately 20°C. Vacuum pump 22 compresses the carbon dioxide gas to approximately 5.8 MPa, at which point the carbon dioxide changes from a gaseous state to a liquid state. The liquefied carbon dioxide is then transported through pipelines to storage tank 24 for storage.

[0083] Decarbonized seawater enters the electrolyte chamber of the first battery unit 1 via the second pH sensor 14. After a preliminary reaction, the positive electrode material 11 of the first battery unit is converted to Ag, and the negative electrode material 12 is converted to BiOCl. As the decarbonized seawater flows through the electrolyte chamber of the first battery unit 1, the first battery unit 1 is connected to the first power supply 17 via the first wire, meaning the first power supply 17 charges the first battery unit 1 through the first wire. At this time, the following reaction occurs inside the battery:

[0084] Positive electrode: Ag + Cl - →AgCl+e -

[0085] Negative electrode: BiOCl + 2H + +3e - →Bi+Cl - +H2O

[0086] Overall reaction:

[0087] The charging current of the first battery cell 1 is controlled at 10A by the first power supply 17. At this time, 6.24 × 10⁻⁶ A / s will be charged per second. 194.16 × 10⁻⁶ electrons are transferred from the positive electrode 11 to the negative electrode 12 of the first battery cell. According to the battery reaction equation above, 4.16 × 10⁻⁶ electrons are transferred per second. 19 H + The low-carbon seawater, flowing through the first battery cell 1, is transferred from the battery electrolyte to the negative electrode 12. The loss of H+ ions causes the low-carbon seawater to become alkalized, i.e., its pH value increases. This is because the seawater gains H+ ions in the second battery cell 3. + The quantity, and the H lost by seawater in the first battery cell 1 + The quantities are the same, therefore, the seawater pH value is restored to its initial state, that is, the pH value is restored to 8.2. The low-carbon seawater from the electrolyte chamber of the first battery unit 1 is returned to the external environment via the main first acid-base sensor 44 and the first output valve 46.

[0088] When the reading of the second current sensor 33 is lower than the set value (0.5A in this embodiment), it indicates that the second battery unit 3 is basically depleted of power. At this time, it is necessary to adjust the direction of the carbon-rich seawater.

[0089] By repeating the above steps, carbon dioxide can be continuously captured from seawater.

[0090] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A system for capturing carbon dioxide from seawater, characterized in that, It includes: An electrolysis device includes a first battery unit, a first power supply, a first switch and a second switch. The first battery unit has a first electrolyte chamber. The first power supply, the first switch and the first battery unit are connected in series. The second switch is connected in parallel with the first battery unit. and A degassing device, connected to the first electrolyte chamber, is used to remove gas from the solution transported from the first electrolyte chamber; The electrolysis device further includes a second battery unit, a second power supply, a third switch and a fourth switch. The second battery unit has a second electrolyte chamber. The second power supply, the third switch and the second battery unit are connected in series. The fourth switch is connected in parallel with the second battery unit. The degassing device is also connected to the second electrolyte chamber; The system for capturing carbon dioxide from seawater also includes a seawater pump, a seawater filter, a main input pipe, two input valves, and two input branch pipes. The two input branch pipes are respectively connected to the first electrolyte chamber and the second electrolyte chamber. One end of the main input pipe is connected to the two input branch pipes, and the other end is connected to the seawater filter and the seawater pump in sequence. The two input valves are respectively located on the two input branch pipes. The system for capturing carbon dioxide from seawater also includes two connecting pipes, two output pipes, and two output valves. One end of each of the two connecting pipes is connected to the first electrolyte chamber and the second electrolyte chamber, respectively, and the other end is connected to the two output pipes. The input branch pipe is connected to the connection between the connecting pipes and the output pipes, and the two output valves are respectively installed on the two output pipes. The positive electrode of the first battery cell uses AgCl as the electrode material, and the negative electrode of the first battery cell uses Bi as the electrode material. The positive electrode of the second battery cell uses Ag as the electrode material, and the negative electrode of the second battery cell uses BiOCl as the electrode material.

2. The system for capturing carbon dioxide from seawater according to claim 1, characterized in that, The system for capturing carbon dioxide from seawater also includes two first pH sensors, which are respectively mounted on the two connecting pipes.

3. The system for capturing carbon dioxide from seawater according to claim 1, characterized in that, A second pH sensor is provided on the infusion pipeline between the degassing device and the first electrolyte chamber; and / or, a third pH sensor is provided on the infusion pipeline between the degassing device and the second electrolyte chamber.

4. The system for capturing carbon dioxide from seawater according to claim 1, characterized in that, The degassing device is equipped with a carbon dioxide selective permeation membrane in its inner cavity, which divides the inner cavity of the degassing device into a solution cavity and a gas cavity. The system for capturing carbon dioxide from seawater also includes a gas delivery pipe, a vacuum gauge, a vacuum pump, a carbon dioxide compressor, and a storage tank. One end of the gas delivery pipe is connected to the gas chamber, and the other end is connected to the storage tank. The vacuum gauge, the vacuum pump, and the carbon dioxide compressor are sequentially arranged on the gas delivery pipe in a direction away from the gas chamber.

5. The system for capturing carbon dioxide from seawater according to claim 4, characterized in that, The carbon dioxide selective permeation membrane is a hollow fiber membrane.

6. The system for capturing carbon dioxide from seawater according to claim 1, characterized in that, The positive and negative terminals of the first battery cell are respectively connected to a fifth wire. The electrolysis device also includes a first wire, a second wire, and a first current sensor. The two ends of the first wire and the second wire are respectively electrically connected to the two fifth wires. The first power supply and the first switch are located on the first wire, the second switch is located on the second wire, and the first current sensor is located on one of the fifth wires. And / or, The positive and negative terminals of the second battery cell are respectively connected to a sixth wire. The electrolysis device also includes a third wire, a fourth wire, and a second current sensor. The two ends of the third wire and the fourth wire are respectively electrically connected to two of the sixth wires. The second power supply and the third switch are located on the third wire, the second switch is located on the fourth wire, and the second current sensor is located on one of the sixth wires.

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