Method and system for capturing CO2 in flue gas based on pH change
By regulating CO2 capture and release in electrolytic cells by using pH changes, the problems of high energy consumption and high cost in the prior art are solved, and efficient and stable CO2 capture and purity improvement are achieved, which is suitable for industrial-scale applications.
Patent Information
- Application Number
- CN202510040670.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-10
- Publication Date
- 2025-05-13
AI Technical Summary
The existing CO2 capture technology faces the problems of high costs and high energy consumption, and it is difficult to achieve large-scale promotion.
Using an electrochemical method based on pH change, by applying a voltage in the electrolytic cell, hydrogen ions and hydroxide ions are generated by ion-selective separator, the pH value of the gas treatment chamber is adjusted, and the dissolved CO2 in the alkaline electrolyte is converted into gaseous CO2 and separated.
It achieves efficient and stable CO2 capture, reduces energy consumption, improves CO2 product purity, and has good engineering adaptability, suitable for industrial-scale applications.
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Figure CN119971742A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of boiler environmental protection and atmospheric environmental protection, and in particular to a method and system for capturing CO2 in flue gas based on pH change. Background Art
[0002] People are paying more and more attention to controlling carbon dioxide emissions at the source and capturing and utilizing CO2 at the tail end. The annual CO2 emissions from my country's thermal power units account for more than 40% of the country's total emissions. Such concentrated CO2 needs to be treated urgently, and CCUS technology has emerged. The more mature method is the liquid amine capture method, which has achieved industrial demonstration and application in many thermal power units. In recent years, solid adsorption technology has also gradually matured, but it faces the problems of high cost and high energy consumption, and it is difficult to promote it on a large scale.
[0003] Electrochemical CO2 capture is to change the pH of the electrolyte through an electrochemical process to achieve directional capture and release of CO2. The reaction conditions are mild and widely adaptable. At the same time, the CO2 capture efficiency can be controlled by adjusting the current and voltage, and it has a high degree of adjustability. Its principle is to adjust the cathode potential to produce OH- or reducing active species with CO2 reactivity, thereby mediating the selective and efficient capture of CO2, and achieving efficient and controllable release through anode reaction coupling. The capture and release of CO2 occur in the cathode chamber and anode chamber of the electrolytic cell respectively, realizing the separation of capture and release space. At the same time, the synchronous reaction of the cathode and anode also realizes the synchronization of capture and release time, greatly improving the capture efficiency, and the released high-purity CO2 can be directly used for subsequent downstream applications. The advantage of electrochemical CO2 capture is that it effectively avoids the challenges of high energy consumption and low efficiency of the traditional CO2 capture process using amine and hydroxide solutions, as well as external high temperature and high pressure / vacuum input, and the corrosion of equipment and degradation of adsorbent materials caused by the use of a large amount of chemical reagents. Summary of the invention
[0004] In view of the above-mentioned problems, the present invention is proposed.
[0005] Therefore, the present invention provides a method and system for capturing CO2 in flue gas based on pH changes, which can solve the problems mentioned in the background technology.
[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for capturing CO2 in flue gas based on pH changes, comprising: passing flue gas containing CO2 into a gas treatment chamber of an electrolytic cell; the gas treatment chamber is filled with an alkaline electrolyte; applying voltage to the electrolytic cell so that the ion selective membrane in the electrolytic cell produces hydrogen ions and hydroxide ions, and the hydrogen ions and the hydroxide ions are respectively transported to corresponding electrode chambers through the ion selective membrane; the pH value of the gas treatment chamber is adjusted by the hydrogen ions, and the CO2 dissolved in the alkaline electrolyte is converted into gaseous CO2 and separated.
[0007] As a preferred embodiment of the method for capturing CO2 in flue gas based on pH change described in the present invention, the method comprises the following steps: introducing the flue gas containing CO2 into the gas treatment chamber of the electrolytic cell, and obtaining the flue gas containing CO2; introducing the flue gas containing CO2 into the gas treatment chamber, wherein the gas treatment chamber is filled with KHCO3 electrolyte; if the pressure value of the flue gas containing CO2 is lower than a first preset threshold value, starting the boosting device to increase the pressure value of the flue gas containing CO2 to above the first preset threshold value; adjusting the flow rate of the flue gas containing CO2 to the first preset value, so that the flue gas containing CO2 is in full contact with the KHCO3 electrolyte.
[0008] As a preferred embodiment of the method for capturing CO2 in flue gas based on pH change described in the present invention, wherein: applying a voltage to the electrolytic cell so that the ion selective membrane in the electrolytic cell generates hydrogen ions and hydroxide ions, and the hydrogen ions and the hydroxide ions are respectively transported to corresponding electrode chambers through the ion selective membrane, the following steps are included: applying a voltage of a second preset value to the electrolytic cell so that a potential difference is generated on both sides of the ion selective membrane; under the action of the potential difference, the ion selective membrane decomposes water molecules into hydrogen ions and hydroxide ions; if it is detected that the hydrogen ion concentration in the electrolytic cell reaches a second preset threshold value, the ion selective membrane is controlled to transport the hydrogen ions to the anode chamber and the hydroxide ions to the cathode chamber.
[0009] As a preferred embodiment of the method for capturing CO2 in flue gas based on pH change described in the present invention, wherein: under the action of the potential difference, the ion selective membrane decomposes water molecules into hydrogen ions and hydroxide ions, the method comprises the following steps: forming an electric field of the potential difference on both sides of the ion selective membrane, the field strength of the electric field being inversely proportional to the thickness of the ion selective membrane; under the action of the electric field, the water molecules on the surface of the ion selective membrane are polarized and arranged in a directional manner to form an ordered water molecule layer; according to the direction of the electric field, the hydrogen-oxygen bonds of the water molecules in the water molecule layer are broken to generate the hydrogen ions and the hydroxide ions; and the polarization degree of the water molecules in the water molecule layer is controlled so that the generation rate of the hydrogen ions and the hydroxide ions is adapted to the pH adjustment requirement of the system.
[0010] As a preferred embodiment of the method for capturing CO2 in flue gas based on pH change described in the present invention, the CO2 dissolved in the alkaline electrolyte is converted into gaseous CO2, comprising the following steps: the hydrogen ions generated by the anode chamber are introduced into the gas treatment chamber, thereby driving the pH value in the gas treatment chamber to decrease; if the pH value of the gas treatment chamber is higher than a third preset threshold value, the hydrogen ions continue to be introduced; otherwise, the introduction of the hydrogen ions is stopped, and a gas collection device is turned on at the same time; the gaseous CO2 precipitated in the gas treatment chamber is collected and separated by the gas collection device.
[0011] As a preferred embodiment of the method for capturing CO2 in flue gas based on pH changes described in the present invention, wherein: the pH value in the gas treatment chamber is monitored in real time by a pH detection device, and the pH value is compared with the third preset threshold value; the hydrogen ions are introduced into the gas treatment chamber, and the introduction rate of the hydrogen ions is proportional to the difference between the pH value and the third preset threshold value; if the pH detection device detects that the local pH value is lower than the third preset threshold value, the introduction position of the hydrogen ions is adjusted; if the concentration of dissolved CO2 in the gas treatment chamber is lower than the fourth preset threshold value, the introduction of the hydrogen ions is closed and the gas collection device is started.
[0012] As a preferred embodiment of the method for capturing CO2 in flue gas based on pH changes described in the present invention, the second preset threshold refers to the minimum concentration value at which hydrogen ions accumulate in the electrolytic cell to drive ion migration, which is set based on the ion exchange capacity and electrical migration rate of the ion selective membrane.
[0013] To further solve the above technical problems, the present invention provides the following technical solutions: A system for capturing CO2 in flue gas based on pH changes, comprising: a first conveying module, for passing flue gas containing CO2 into a gas treatment chamber of an electrolytic cell; a second conveying module, for applying voltage to the electrolytic cell, so that the ion selective membrane in the electrolytic cell produces hydrogen ions and hydroxide ions, and the hydrogen ions and the hydroxide ions are respectively transported to corresponding electrode chambers through the ion selective membrane; and a regulating and separating module, for regulating the pH value of the gas treatment chamber through the hydrogen ions, converting the CO2 dissolved in the alkaline electrolyte into gaseous CO2 and separating it.
[0014] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and wherein when the processor executes the computer program, the steps of the method for capturing CO2 in flue gas based on pH changes as described above are implemented.
[0015] A computer-readable storage medium having a computer program stored thereon, characterized in that when the computer program is executed by a processor, the steps of the method for capturing CO2 in flue gas based on pH changes as described above are implemented.
[0016] Beneficial effects of the present invention: The present invention has achieved significant progress in the field of CO2 capture. In terms of process design, an efficient and stable CO2 capture system is established by organically combining electrochemical pH regulation with gas-liquid separation technology. In terms of process control, an innovative multiple threshold linkage control strategy is adopted to achieve precise regulation of pH value and CO2 concentration, effectively solving the problems of local acidification and uneven CO2 release in traditional technologies. By optimizing the pH control mechanism under mild conditions, the high energy consumption problem of traditional thermal regeneration processes is avoided, while the purity of CO2 products is improved. The present invention has good engineering adaptability and can automatically adjust operating parameters according to different working conditions, providing reliable technical support for industrial-scale applications. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.
[0018] Figure 1 This is a schematic diagram of the overall process of a method for capturing CO2 in flue gas based on pH change proposed by the present invention;
[0019] Figure 2This is a diagram of the existence and conversion forms of CO2 under different pH conditions in the method for capturing CO2 in flue gas based on pH changes proposed by the present invention.
[0020] Figure 3 This is a CO2 capture flow chart of a method for capturing CO2 in flue gas based on pH changes proposed by the present invention. DETAILED DESCRIPTION
[0021] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.
[0022] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0023] Example 1, reference Figure 1 , which is an embodiment of the present invention, provides a method for capturing CO2 in flue gas based on pH changes.
[0024] S1: Flue gas containing CO2 is introduced into a gas treatment chamber of an electrolytic cell, wherein the gas treatment chamber is filled with an alkaline electrolyte.
[0025] S1.1: Desulfurization, denitrification and dust removal are performed on the flue gas to obtain flue gas containing CO2;
[0026] S1.2: Flue gas containing CO2 is passed into a gas treatment chamber, wherein the gas treatment chamber is filled with KHCO3 electrolyte;
[0027] S1.3: If the pressure value of the flue gas containing CO2 is lower than the first preset threshold, the booster device is started to increase the pressure value of the flue gas containing CO2 to above the first preset threshold; it should be noted that the first preset threshold refers to the minimum pressure value required before the flue gas enters the gas treatment chamber. The setting of this threshold is based on the following considerations: 1. Ensure that the flue gas can overcome the static pressure and surface tension of the electrolyte to form evenly dispersed bubbles; 2. Ensure that the solubility of the gas in the electrolyte reaches an ideal state; 3. Avoid increased energy consumption and equipment load caused by excessive pressure. The preferred range of the first preset threshold is 0.12-0.18MPa, and the specific value can be adjusted according to the electrolyte depth and system operating conditions.
[0028] S1.4: Adjust the flow rate of the flue gas containing CO2 to a first preset value so that the flue gas containing CO2 is fully in contact with the KHCO3 electrolyte.
[0029] It should be noted that KHCO3 electrolyte, as the core medium for CO2 capture, has unique advantages: its alkaline environment is conducive to the dissolution and conversion of CO2, and KHCO3 has good chemical stability and will not decompose or react during the electrochemical process. Compared with traditional amine absorbents, KHCO3 electrolyte can operate efficiently at room temperature and pressure, avoiding high-temperature regeneration process and significantly reducing energy consumption. The design of the gas treatment chamber adopts a special structure to maximize the contact area between flue gas and electrolyte. By setting the gas treatment chamber at the cell-2 position, it not only ensures sufficient contact with the electrolyte, but also facilitates the subsequent pH adjustment process, providing a spatial basis for the entire capture process.
[0030] Preferably, in step S1.2, the flue gas is directly introduced into a gas treatment chamber filled with KHCO3 electrolyte, breaking through the limitation of complex pretreatment required in traditional CCUS technology. This simplified process route significantly reduces equipment investment and operating costs, while improving the reliability of the system. Traditional CO2 capture technology often faces the problems of high energy consumption and low efficiency. The present invention achieves the optimal contact state between the gas and liquid phases by precisely controlling the flue gas flow rate in step S1.4. The pressure control mechanism in step S1.3 solves the problem of unstable capture efficiency caused by flue gas pressure fluctuations. Through the intelligent adjustment of the boosting device, the system pressure is kept higher than the first preset threshold value, ensuring the stable dissolution process of the gas in the electrolyte, which is crucial to maintaining the capture efficiency of the entire system.
[0031] S2: applying voltage to the electrolytic cell so that the ion selective membrane in the electrolytic cell generates hydrogen ions and hydroxide ions, and transports the hydrogen ions and hydroxide ions to corresponding electrode chambers through the ion selective membrane.
[0032] S2.1: Apply a voltage of the second preset value to the electrolytic cell to generate a potential difference on both sides of the ion selective diaphragm; it should be noted that the second preset threshold refers to the minimum concentration value of hydrogen ions accumulated in the electrolytic cell to drive ion migration, and the setting of this threshold is based on the ion exchange capacity and electrical migration rate of the ion selective diaphragm. When the hydrogen ion concentration reaches this threshold, it can ensure that the ions migrate stably and directional under the action of the electric field, avoiding the phenomenon of ion back diffusion during the migration process. The preferred second preset threshold range is 0.05-0.15mol / L, and the specific value needs to be adjusted according to factors such as the characteristics of the selected ion selective diaphragm material, the applied voltage, and the system operating temperature.
[0033] S2.2: Under the action of potential difference, the ion-selective membrane decomposes water molecules into hydrogen ions and hydroxide ions;
[0034] Specifically, an electric field with a potential difference is formed on both sides of the ion selective membrane, and the field strength of the electric field is inversely proportional to the thickness of the ion selective membrane;
[0035] Under the action of the electric field, the water molecules on the surface of the ion-selective membrane are polarized and arranged in a directional manner to form an ordered water molecule layer;
[0036] According to the direction of the electric field, the hydrogen-oxygen bonds of water molecules in the water molecule layer are broken to generate hydrogen ions and hydroxide ions;
[0037] The polarization degree of water molecules in the water molecule layer is controlled so that the generation rate of hydrogen ions and hydroxide ions is adapted to the pH adjustment requirements of the system.
[0038] S2.3: If it is detected that the hydrogen ion concentration in the electrolytic cell reaches a second preset threshold, the ion selective membrane is controlled to transport hydrogen ions to the anode chamber and hydroxide ions to the cathode chamber.
[0039] S3: The pH value of the gas treatment chamber is adjusted by hydrogen ions, and the CO2 dissolved in the alkaline electrolyte is converted into gaseous CO2 and separated.
[0040] S3.1: passing hydrogen ions generated in the anode chamber into the gas treatment chamber, thereby driving the pH value in the gas treatment chamber to decrease;
[0041] S3.2: If the pH value of the gas treatment chamber is higher than the third preset threshold, continue to introduce hydrogen ions; otherwise, stop introducing hydrogen ions and turn on the gas collection device at the same time; it should be noted that the third preset threshold refers to the critical pH value for controlling the phase transition of CO2 in the gas treatment chamber, which directly determines the efficiency of the conversion of dissolved CO2 to gaseous CO2. The setting of the threshold needs to take into account the existence form of CO2 under different pH conditions (dynamic balance of H2CO3, HCO3-, CO32-) and the buffering capacity of the KHCO3 electrolyte. In order to achieve efficient removal of CO2 and avoid corrosion of equipment by local acidification, the third preset threshold is preferably set between 5.5-6.5, which can be fine-tuned according to actual operating conditions and CO2 capture efficiency requirements.
[0042] Specifically, the pH value in the gas treatment chamber is monitored in real time by a pH detection device, and the pH value is compared with a third preset threshold value; hydrogen ions are introduced into the gas treatment chamber, and the introduction rate of hydrogen ions is proportional to the difference between the pH value and the third preset threshold value;
[0043] If the pH detection device detects that the local pH value is lower than the third preset threshold, the hydrogen ion entry position is adjusted; if the concentration of dissolved CO2 in the gas treatment chamber is lower than the fourth preset threshold, the hydrogen ion entry is closed and the gas collection device is started. It should be noted that the fourth preset threshold refers to the minimum concentration limit of dissolved CO2 in the gas treatment chamber, which is used to determine whether the CO2 release process is completed. The determination of the threshold requires a balance between CO2 capture efficiency and energy consumption, ensuring sufficient CO2 removal effect while avoiding excessive consumption of hydrogen ions. Based on the solubility of CO2 under weakly acidic conditions and actual engineering application experience, the fourth preset threshold is preferably set to 10%-15% of the initial dissolved CO2 concentration, that is, when the dissolved CO2 concentration is reduced to this range, it can be considered that the CO2 release process is basically completed.
[0044] S3.3: The gaseous CO2 released from the gas treatment chamber is collected and separated by the gas collection device.
[0045] Preferably, the S3 step of the present invention is designed based on the principle of the difference in the existence form of CO2 under different pH environments. Under alkaline conditions, CO2 mainly exists in the electrolyte in the form of carbonate (CO32-) and bicarbonate (HCO3-). By accurately controlling the introduction of hydrogen ions, the pH value of the solution is reduced to a specific range, destroying the chemical balance of the carbonate system, and promoting the conversion of dissolved CO2 to gaseous CO2. This process involves complex multiphase reaction kinetics and mass transfer processes, and it is necessary to achieve efficient removal of CO2 through precise pH regulation and gas-liquid separation. By adopting real-time pH monitoring and feedback control mechanism, the precise regulation of pH value is achieved by adjusting the introduction rate and position of hydrogen ions, avoiding the problems of local acidification and uneven CO2 release in traditional technologies. At the same time, the present invention combines the introduction of hydrogen ions with CO2 concentration monitoring, and establishes an intelligent control strategy based on dual thresholds, which not only ensures the full release of CO2, but also avoids excessive consumption of energy. In the gas collection link, the system achieves efficient collection of CO2 through an optimized gas-liquid separation device.
[0046] In summary, the present invention has achieved significant progress in the field of CO2 capture through systematic technological innovation. In terms of process design, an efficient and stable CO2 capture system is established by organically combining electrochemical pH regulation with gas-liquid separation technology. In terms of process control, an innovative multiple threshold linkage control strategy is adopted to achieve precise regulation of pH value and CO2 concentration, effectively solving the problems of local acidification and uneven CO2 release in traditional technologies. By optimizing the pH control mechanism under mild conditions, the high energy consumption problem of traditional thermal regeneration processes is avoided, while the purity of CO2 products is improved. The system has good engineering adaptability and can automatically adjust operating parameters according to different working conditions, providing reliable technical support for industrial-scale applications.
[0047] Embodiment 2 is an embodiment of the present invention, which provides a system for capturing CO2 in flue gas based on pH change, comprising:
[0048] A first conveying module, which passes flue gas containing CO2 into a gas treatment chamber of the electrolytic cell;
[0049] a second transport module, for applying a voltage to the electrolytic cell to cause the ion selective membrane in the electrolytic cell to generate hydrogen ions and hydroxide ions, and transporting the hydrogen ions and the hydroxide ions to corresponding electrode chambers through the ion selective membrane;
[0050] The regulating and separating module is used to regulate the pH value of the gas treatment chamber through the hydrogen ions, convert the CO2 dissolved in the alkaline electrolyte into gaseous CO2 and separate it.
[0051] Embodiment 3 is an embodiment of the present invention, which is different from the previous embodiment in that: if the function is implemented in the form of a software function unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.
[0052] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.
[0053] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.
[0054] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.
[0055] Example 4 is an embodiment of the present invention, which provides a method for capturing CO2 in flue gas based on pH changes. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.
[0056] The existence and transformation forms of CO2 under different pH conditions are as follows Figure 2 Shown
[0057] CO2 capture process Figure 3 As shown, the flue gas enters from cell-2, and the CO2 in the flue gas is fully dissolved by the KHCO3 electrolyte. After that, when voltage is applied to both ends of the electrode, the BMP (bipolar membrane) will produce OH- and H+, which enter cell-1 and cell-2 respectively. At this time, the pH of cell-2 begins to decrease, and HCO3- will be converted into gaseous CO2 and released. The OH- near the cathode can also be supplemented to Cell-2 through the AEM (anion exchange membrane). Similarly, the H+ near the anode can also be supplemented to Cell-1 through the CEM (cation exchange membrane). Under the condition of controlling the flue gas flow rate and current and voltage, the CO2 can be introduced and released simultaneously, which greatly improves the capture efficiency.
[0058] In order to verify the technical effect of the present invention, a systematic comparative experiment was designed in this embodiment. The experiment used simulated flue gas (CO2 concentration 15 vol%) as the gas source, and under the same air intake conditions, the electrochemical pH control system of the present invention and the traditional amine capture technology were used to carry out CO2 capture experiments. During the experiment, the inlet and outlet CO2 concentrations were monitored by an online gas analyzer, the solution pH value changes were recorded in real time using a high-precision pH meter, and the total power consumption of the system was measured by an energy consumption analyzer. The experiment lasted for 48 hours, and data was recorded every 4 hours to ensure the reliability and representativeness of the data.
[0059] In the experimental design, three core technical indicators were focused on: CO2 capture efficiency, system energy consumption and product purity. The electrochemical pH control system used in the present invention operates at room temperature and pressure, and realizes dynamic regulation of pH value by accurately controlling the rate and position of hydrogen ion introduction. During the experiment, this embodiment pays special attention to the uniformity of local pH distribution, and multiple pH detection points are set in the gas treatment chamber. The change trend of pH value is monitored and recorded in real time through the data acquisition system. At the same time, the purity of the collected CO2 product is analyzed by gas chromatograph to evaluate the separation effect of the system.
[0060] Table 1 CO2 capture system performance comparison data table
[0061] Test Parameters The present invention Traditional amine method Improved results Operating temperature(℃) 25 120 Lower operating temperature System pressure(MPa) 0.15 0.3 Reduce system pressure pH adjustment response time (s) 30 180 Improve responsiveness CO2 release cycle (min) 45 120 Shorten processing cycle Local pH deviation (%) ±3.5 ±12.5 Improve pH uniformity Solution regeneration energy consumption (kJ / molCO2) 55 95 Reduce energy consumption CO2 product purity (%) 95 85 Improve product purity System stable operation time (h) 168 72 Extended operating cycle
[0062] As shown in Table 1, by comparing the test data, it can be seen that the present invention shows significant advantages in multiple key technical indicators. First, in terms of operating conditions, the present invention realizes CO2 capture under mild conditions, the operating temperature is only 25°C, which is significantly lower than the 120°C of the traditional amine method, and the system pressure is also reduced by 50%. In terms of process control, the pH adjustment response time is shortened from 180s to 30s, indicating that the system has a faster dynamic adjustment capability. The CO2 release cycle is shortened by 62.5%, which greatly improves the treatment efficiency. It is particularly noteworthy that the present invention has outstanding performance in pH control uniformity, with a local pH deviation of only ±3.5%, which is much better than the ±12.5% of the traditional process. In terms of energy consumption, the solution regeneration energy consumption per mole of CO2 is reduced by 42.1%. In addition, the stable operation time of the system is extended to 168 hours, which is 2.33 times that of the traditional process, reflecting a high engineering reliability. In terms of product quality, the CO2 purity is increased to 95%, meeting the quality requirements for subsequent utilization. These data fully demonstrate the comprehensive advantages of the present invention in terms of process performance, energy efficiency and product quality.
[0063] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.
Claims
1. A method for capturing CO2 in flue gas based on pH changes, characterized in that: include: Passing flue gas containing CO2 into a gas treatment chamber of the electrolytic cell; The gas treatment chamber is filled with an alkaline electrolyte; applying a voltage to the electrolytic cell so that an ion selective membrane in the electrolytic cell generates hydrogen ions and hydroxide ions, and transporting the hydrogen ions and the hydroxide ions to corresponding electrode chambers through the ion selective membrane; The pH value of the gas treatment chamber is adjusted by the hydrogen ions, and the CO2 dissolved in the alkaline electrolyte is converted into gaseous CO2 and separated.
2. The method for capturing CO2 in flue gas based on pH change according to claim 1, characterized in that: The flue gas containing CO2 is introduced into the gas treatment chamber of the electrolytic cell, comprising the following steps: Performing desulfurization, denitrification and dust removal treatment on the flue gas to obtain the flue gas containing CO2; Passing the CO2-containing flue gas into the gas treatment chamber, wherein the gas treatment chamber is filled with KHCO3 electrolyte; If the pressure value of the flue gas containing CO2 is lower than a first preset threshold, starting the boosting device to increase the pressure value of the flue gas containing CO2 to above the first preset threshold; The flow rate of the flue gas containing CO2 is adjusted to a first preset value so that the flue gas containing CO2 is fully in contact with the KHCO3 electrolyte.
3. The method for capturing CO2 in flue gas based on pH change according to claim 2, characterized in that: Applying a voltage to the electrolytic cell so that the ion selective membrane in the electrolytic cell generates hydrogen ions and hydroxide ions, and transporting the hydrogen ions and the hydroxide ions to corresponding electrode chambers through the ion selective membrane, respectively, comprises the following steps: Applying a voltage of a second preset value to the electrolytic cell to generate a potential difference across the ion selective membrane; Under the action of the potential difference, the ion selective membrane decomposes water molecules into hydrogen ions and hydroxide ions; If it is detected that the hydrogen ion concentration in the electrolytic cell reaches a second preset threshold, the ion selective membrane is controlled to transport the hydrogen ions to the anode chamber and the hydroxide ions to the cathode chamber.
4. The method for capturing CO2 in flue gas based on pH change according to claim 3, characterized in that: Under the action of the potential difference, the ion selective membrane decomposes water molecules into hydrogen ions and hydroxide ions, comprising the following steps: An electric field with the potential difference is formed on both sides of the ion selective membrane, wherein the field strength of the electric field is inversely proportional to the thickness of the ion selective membrane; Under the action of the electric field, the water molecules on the surface of the ion selective membrane are polarized and arranged in a directional manner to form an ordered water molecule layer; According to the direction of the electric field, the hydrogen-oxygen bonds of the water molecules in the water molecule layer are broken to generate the hydrogen ions and the hydroxide ions; The polarization degree of the water molecules in the water molecule layer is controlled so that the generation rate of the hydrogen ions and the hydroxide ions is adapted to the pH adjustment requirement of the system.
5. The method for capturing CO2 in flue gas based on pH change according to claim 4, characterized in that: The CO2 dissolved in the alkaline electrolyte is converted into gaseous CO2, comprising the following steps: Passing hydrogen ions generated in the anode chamber into the gas treatment chamber to drive the pH value in the gas treatment chamber to decrease; If the pH value of the gas treatment chamber is higher than a third preset threshold, continue to introduce the hydrogen ions; otherwise, stop introducing the hydrogen ions and start the gas collection device at the same time; The gaseous CO2 released from the gas treatment chamber is collected and separated by the gas collecting device.
6. The method for capturing CO2 in flue gas based on pH change according to claim 5, characterized in that: monitoring the pH value in the gas treatment chamber in real time by a pH detection device, and comparing the pH value with the third preset threshold; introducing the hydrogen ions into the gas treatment chamber, wherein the rate of introduction of the hydrogen ions is proportional to the difference between the pH value and the third preset threshold value; If the pH detection device detects that the local pH value is lower than the third preset threshold, adjusting the hydrogen ion introduction position; If the concentration of dissolved CO2 in the gas processing chamber is lower than a fourth preset threshold, the introduction of hydrogen ions is closed and the gas collection device is started.
7. The method for capturing CO2 in flue gas based on pH change according to claim 6, characterized in that: The second preset threshold refers to the minimum concentration value of hydrogen ions accumulated in the electrolytic cell to drive ion migration, which is set based on the ion exchange capacity and electrical migration rate of the ion selective membrane.
8. A system for capturing CO2 in flue gas based on pH change, based on the method for capturing CO2 in flue gas based on pH change according to any one of claims 1 to 7, characterized in that: include, A first conveying module, which passes flue gas containing CO2 into a gas treatment chamber of the electrolytic cell; a second transport module, for applying a voltage to the electrolytic cell to cause the ion selective membrane in the electrolytic cell to generate hydrogen ions and hydroxide ions, and transporting the hydrogen ions and the hydroxide ions to corresponding electrode chambers through the ion selective membrane; The regulating and separating module is used to regulate the pH value of the gas treatment chamber through the hydrogen ions, convert the CO2 dissolved in the alkaline electrolyte into gaseous CO2 and separate it.
9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method for capturing CO 2 in flue gas based on pH change according to any one of claims 1 to 7 are implemented.
10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for capturing CO 2 in flue gas based on pH change according to any one of claims 1 to 7 are implemented.