Carbon-sulfur co-capture and efficient separation device

Abstract

The application discloses a carbon-sulfur cooperative capture and efficient separation device and belongs to the technical field of flue gas treatment. The device comprises an absorption tower, a carbon dioxide desorption tower and a sulfur dioxide desorption tower which are connected in sequence, the liquid inlet of the absorption tower is connected with an ionic liquid feeding pump, the liquid outlet is connected with the liquid inlet of the carbon dioxide desorption tower through a heat exchanger, the carbon dioxide desorption tower is connected with a first solution reboiler, the liquid outlet of the carbon dioxide desorption tower is connected with the liquid inlet of the sulfur dioxide desorption tower, and the sulfur dioxide desorption tower is connected with a second solution reboiler. The device can realize the cooperative capture and efficient separation of CO2 and SO2.

Description

Technical Field

[0001] This application relates to the field of flue gas treatment technology, and in particular to a carbon-sulfur synergistic capture and efficient separation device. Background Technology

[0002] Currently, CO2 and SO2 capture technologies are relatively mature, but they typically capture CO2 or SO2 separately, and these technologies have already achieved industrial application. Capture technologies are broadly classified into four categories: dry methods, wet methods, membrane separation methods, and biological methods. Dry methods include adsorption methods using activated carbon and molecular sieves, as well as alkaline dry powder absorption methods. Wet methods include alkaline solution absorption, amine solution absorption, and ionic liquid absorption. Membrane separation methods use various organic and inorganic membranes to enrich CO2 and SO2; however, membrane separation is still in the laboratory research stage and has high development costs, preventing widespread application. Biological methods utilize microorganisms to absorb and convert CO2 and SO2, but cannot perform further separation. Currently, dry and wet methods have achieved stable industrial production and application, membrane separation is still in the research stage, and biological methods are only used in small-scale treatment of low-concentration CO2 and SO2 flue gas.

[0003] Conventional treatment of CO2 and SO2 involves processing them in batches. There are few research reports on co-capture technology for CO2 and SO2, and there is currently no industrial production or application.

[0004] The patent application with publication number CN102120137A describes an ammonia-based atmospheric pressure capture and absorption system and process for sulfur dioxide and carbon dioxide. The process involves two reaction processes: first, dilute ammonia water and sulfur dioxide react to generate ammonium sulfite, which is further converted into ammonium sulfate. Then, desalination is performed, and the regenerated ammonia water is used for carbon dioxide absorption. This is a multi-stage CO2 and SO2 capture and separation process.

[0005] The patent application with publication number CN114471124A describes a method for carbon and sulfur emission reduction and carbon and sulfur fixation. It also uses ammonia water to capture CO2 and SO2 in flue gas, generating a supersaturated solution of ammonium bicarbonate and ammonium sulfate, which then reacts with metal oxides to generate ammonia water and insoluble carbonates and sulfates, which are then sealed. However, it only captures CO2 and SO2, but cannot effectively separate them, and the capture efficiency is also low. The generated salts cannot be regenerated.

[0006] Patent application publication number CN110496517A describes a process for the synergistic removal of carbon, sulfur, and nitrates from industrial flue gas. It employs a chemical conversion method to remove carbon dioxide, sulfur dioxide, and nitrates from the flue gas through chemical reactions with absorbents in their respective absorption systems. The process involves adding absorbents to transform the components and achieve synergistic removal of carbon, sulfur, and nitrates. It uses an alkaline solution as the absorbent, which reacts with acidic gases to generate corresponding salts. These salts are difficult to regenerate and desorb, resulting in low absorption efficiency and an inability to effectively separate CO2 and SO2.

[0007] The patent with authorization announcement number CN214809690U describes a sulfur and carbon co-extraction tower that uses a tower layer segmentation technology to achieve the layered absorption of CO2 and SO2 rather than synergistic capture.

[0008] The patent with authorization announcement number CN212327453U introduces a low-temperature pentane flue gas washing system for simultaneous desulfurization and decarbonization. It utilizes the high melting point of CO2 to turn CO2 into dry ice using low-temperature pentane, thereby achieving the separation of CO2 and SO2. Although it can separate CO2 and SO2, the cost and energy consumption are too high, and SO2 in the flue gas is difficult to enrich, so it cannot achieve the target requirements well.

[0009] Some literature suggests using ammonia water in series for the absorption and enrichment of CO2 and SO2, but this does not conform to the principles of short process and synergistic capture, and the high energy consumption and high raw material input are not conducive to market development. Other literature uses calcium-based absorbents to achieve synergistic capture of CO2 / SO2, but its regeneration energy consumption is high, which is not conducive to industrial application, and the capture efficiency is also low.

[0010] In summary, while calcium-based mineralization and thermal alkali mineralization technologies can simultaneously capture CO2 and SO2, they cannot achieve effective separation. The resulting salts decompose at high temperatures, leading to very high regeneration energy consumption. Furthermore, mineralization technologies are suitable for one-time treatment of high-concentration CO2 and SO2 flue gas; for flue gas with low CO2 and SO2 content, the absorption efficiency is very limited. Typically, non-ferrous smelting flue gas contains around 10% CO2 and 20% SO2. Under these conditions, the cost-effectiveness of using mineralization technologies to capture CO2 and SO2 is very low, resulting in limited utilization and a single product, making it difficult to achieve the recycling and resource utilization of CO2 and SO2. Continuous input of raw materials leads to constantly increasing costs. In addition, the storage and transportation of raw materials and products are also problems that must be addressed, thus hindering industrial application.

[0011] Therefore, it is necessary to provide a device that can achieve synergistic capture and efficient separation of CO2 and SO2. Summary of the Invention

[0012] Therefore, according to one embodiment of this application, the objective is to provide a carbon-sulfur synergistic capture and efficient separation device. This device can achieve the synergistic capture and efficient separation of carbon dioxide and sulfur dioxide, especially for non-ferrous smelting flue gas with low concentrations of carbon dioxide and sulfur dioxide. The above objective can be achieved through the following technical solutions: According to one aspect of this application, a carbon-sulfur co-capture and high-efficiency separation device is provided, comprising an absorption tower, a carbon dioxide desorption tower, and a sulfur dioxide desorption tower connected in sequence; wherein, the inlet of the absorption tower is connected to an ionic liquid feed pump for feeding a functional ionic liquid, the gas inlet is connected to a flue gas induced draft fan, the outlet is connected to the inlet of the carbon dioxide desorption tower through a heat exchanger, a first solution reboiler is connected to the lower part of the carbon dioxide desorption tower, the outlet of the carbon dioxide desorption tower is connected to the inlet of the sulfur dioxide desorption tower, and a second solution reboiler is connected to the lower part of the sulfur dioxide desorption tower.

[0013] Optionally, the outlet of the sulfur dioxide desorption tower is connected to the return outlet of the absorption tower via a heat exchanger.

[0014] Optionally, the refrigerant inlet and outlet of the heat exchanger are connected to the liquid outlet of the absorption tower and the liquid inlet of the carbon dioxide desorption tower, respectively, and the heat medium inlet and outlet are connected to the liquid outlet of the sulfur dioxide desorption tower and the liquid return outlet of the absorption tower, respectively.

[0015] Optionally, the first solution reboiler has an inlet and an outlet, which are respectively connected to the outlet of the carbon dioxide desorption tower and the desorbed material return port; the second solution reboiler has an inlet and an outlet, which are respectively connected to the outlet of the sulfur dioxide desorption tower and the desorbed material return port.

[0016] Optionally, the first solution reboiler is used to heat the liquid entering it to 90-102°C for carbon dioxide desorption and return the desorbed material to the carbon dioxide desorption tower; the second solution reboiler is used to heat the liquid entering it to 103-106°C for sulfur dioxide desorption and return the desorbed material to the sulfur dioxide desorption tower.

[0017] Optionally, the desorbed material return port of the carbon dioxide desorption tower is higher than the outlet of the carbon dioxide desorption tower; the desorbed material return port of the sulfur dioxide desorption tower is higher than the outlet of the sulfur dioxide desorption tower.

[0018] Optionally, the outlet of the carbon dioxide desorption tower is connected to a first cooler, and the first cooler is connected to a carbon dioxide storage tank; the outlet of the sulfur dioxide desorption tower is connected to a second cooler, and the second cooler is connected to a sulfur dioxide storage tank.

[0019] Optionally, the system may also include a first transfer pump, a second transfer pump, and a third transfer pump, wherein the first transfer pump is located between the liquid outlet of the absorption tower and the heat exchanger; the second transfer pump is located between the carbon dioxide desorption tower and the sulfur dioxide desorption tower; and the third transfer pump is located between the heat exchanger and the return outlet of the absorption tower.

[0020] Optionally, a pH meter is also included, which is installed at the bottom of the absorption tower, carbon dioxide desorption tower and sulfur dioxide desorption tower respectively, to detect the pH of the ionic liquid in each tower.

[0021] Optionally, the absorption tower has a liquid inlet at the top, an air inlet at the bottom, a liquid outlet at the bottom, a return liquid outlet at the top, and a spray device at the top.

[0022] Optionally, the inlet of the carbon dioxide desorption tower is located at the top, the outlet is located at the top, the liquid outlet is located at the bottom, and the spray device is located at the top.

[0023] Optionally, the inlet of the sulfur dioxide desorption tower is located at the top, the outlet is located at the top, the liquid outlet is located at the bottom, and the spraying device is located at the top.

[0024] Optionally, the device also includes an ionic liquid storage device connected to the ionic liquid feed pump; the ionic liquid storage device contains a functional ionic liquid, wherein the functional ionic liquid has carbon dioxide-loving groups and sulfur dioxide-loving groups introduced on its anion and cation sites.

[0025] Beneficial Effects: The carbon-sulfur synergistic capture and high-efficiency separation device provided according to one embodiment of this application includes an absorption tower and two desorption towers, with the absorption tower connected sequentially to a carbon dioxide desorption tower and a sulfur dioxide desorption tower. A functional ionic liquid is fed into the absorption tower via an ionic liquid feed pump, and flue gas is introduced into the absorption tower by an induced draft fan, allowing the flue gas and functional ionic liquid to contact and be captured within the absorption tower. The captured carbon- and sulfur-rich ionic liquid is heated by a heat exchanger and first enters the carbon dioxide desorption tower, where carbon dioxide desorption is completed by a first solution reboiler connected to the carbon dioxide desorption tower. The desorbed carbon- and sulfur-rich ionic liquid from the carbon dioxide desorption tower enters the sulfur dioxide desorption tower, where sulfur dioxide desorption is completed by a second solution reboiler connected to the sulfur dioxide desorption tower. This achieves high-efficiency separation of carbon dioxide and sulfur dioxide. This device has the advantages of simple structure, small footprint, short processing steps, and low energy consumption.

[0026] Compared with the prior art, some embodiments of this application also have the following advantages: 1) The device has a simple structure, including one absorption tower and two desorption towers. It has a short processing step and is a short-process carbon-sulfur co-enrichment and separation device, which can realize the short-process treatment of acidic gases.

[0027] 2) It occupies a small area, taking up nearly 1 / 3 less space than traditional devices.

[0028] 3) By connecting the absorption tower to two desorption towers, the collection and desorption units are effectively coupled, enabling continuous online operation of collection and separation.

[0029] 4) By connecting the sulfur dioxide desorption tower to the absorption tower via a heat exchanger, the remaining lean ion liquid can be cooled down by exchanging heat with the carbon-rich sulfur ion liquid at the outlet of the absorption tower in the heat exchanger. After cooling, it can be returned to the absorption tower as a functional ion liquid for recycling, which can significantly reduce the steam consumption (for heat exchange) and cost input.

[0030] 5) This device can be used for the treatment of low-concentration CO2 and SO2 flue gas. Based on the design of each tower and its structure, the gas-liquid contact is sufficient, and trace amounts of CO2 and SO2 can fully react with the ionic liquid, thereby achieving efficient capture.

[0031] 6) By installing pH detectors at the bottom of each tower, the degree of capture / desorption can be monitored, thereby controlling the reaction process.

[0032] 7) By connecting solution reboilers to the lower part of the two desorption towers respectively, the desorption temperature can be precisely controlled by the solution reboilers, and the desorption of carbon dioxide and sulfur dioxide can be completed efficiently.

[0033] 8) Functional ionic liquid is fed through an ionic liquid feed pump. The functional ionic liquid is used as an absorbent. It has a stable structure, strong designability of anions and cations, large adsorption capacity for CO2 and SO2, low regeneration energy consumption, low regeneration loss, weak corrosion to equipment, and can be recycled. It has high energy utilization rate, low regeneration loss, and low regeneration temperature. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the connection structure of a carbon-sulfur synergistic capture and efficient separation device in one embodiment of this application.

[0035] Figure reference numerals: 1 Flue gas induced draft fan, 2 Ion liquid feed pump, 3 Absorption tower, 4 First transfer pump, 5 Heat exchanger, 6 Carbon dioxide desorption tower, 7 First solution reboiler, 8 First cooler, 9 Second transfer pump, 10 Sulfur dioxide desorption tower, 11 Second solution reboiler, 12 Second cooler, 13 Third transfer pump. Detailed Implementation

[0036] The technical solutions of this application will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0037] As described above, the inventors of this application recognize that existing technologies for treating gases containing carbon dioxide and sulfur dioxide still have shortcomings, failing to achieve synergistic capture, or even if they can achieve simultaneous capture, they cannot achieve efficient separation. Based on this, this application provides a device capable of synergistic capture and efficient separation of carbon dioxide and sulfur dioxide in flue gas. This device includes an absorption tower, a carbon dioxide desorption tower, and a sulfur dioxide desorption tower connected in sequence. The absorber has an inlet connected to an ionic liquid feed pump for feeding the functional ionic liquid, and an inlet connected to a flue gas induced draft fan. The functional ionic liquid is fed into the absorber by the ionic liquid feed pump, and the flue gas is introduced into the absorber by the induced draft fan, allowing the flue gas and functional ionic liquid to contact within the absorber, such as in a counter-current manner, thus completing the capture. The absorber's outlet is connected to the inlet of a carbon dioxide desorption tower via a heat exchanger. A first solution reboiler is connected to the lower part of the carbon dioxide desorption tower. The captured carbon-rich sulfur ionic liquid is heated by the heat exchanger and then enters the carbon dioxide desorption tower. The temperature is regulated by the first solution reboiler to complete the carbon dioxide desorption and collect the carbon dioxide. The outlet is connected to the inlet of the sulfur dioxide desorption tower. A second solution reboiler is connected to the lower part of the sulfur dioxide desorption tower. The carbon-poor and sulfur-rich ionic liquid desorbed from the carbon dioxide desorption tower enters the sulfur dioxide desorption tower, and the temperature is adjusted by the second solution reboiler to complete the desorption of sulfur dioxide and collect sulfur dioxide. This achieves efficient separation of carbon dioxide and sulfur dioxide, solving the problems of difficult co-capture and efficient separation of CO2 and SO2 in the prior art. This application provides a simple carbon-sulfur co-treatment device, especially for complex smelting flue gas with low concentrations of CO2 and SO2, which simplifies the system structure, shortens the process flow, and reduces investment and operating costs.

[0038] Furthermore, the outlet of the sulfur dioxide desorption tower is connected to the return outlet of the absorption tower via a heat exchanger. The remaining lean ion liquid after desorption (which exchanges heat with the carbon-rich sulfur ion liquid) is cooled and recycled as a functional ionic liquid. Using functional ionic liquids as absorbents for CO2 and SO2 has advantages such as regeneration, low regeneration loss, low regeneration energy consumption, and weak corrosiveness to equipment. By returning the remaining lean ion liquid after desorption, i.e., the regenerated liquid, and utilizing its waste heat, steam consumption and cost are significantly reduced.

[0039] Furthermore, based on the advantages of ionic liquids, such as structural stability and strong designability, the inventors of this application have increased the interaction sites between CO2 and SO2 and the ionic liquid by adjusting the structure of the anions and cations. This is achieved by introducing one or more carbon dioxide-loving groups, such as quaternary ammonium groups, imidazole groups, pyridinium groups, sulfonic acid groups, and amino groups, at the anion and cation sites, and simultaneously introducing one or more sulfur dioxide-loving groups, such as phenol groups, azole groups, ether groups, and amino groups. This increases the amount of carbon dioxide and sulfur dioxide captured by the ionic liquid. At the same time, the interaction between one component of CO2 or SO2 and the site enhances the absorption of the other component, resulting in a synergistic effect in the capture of the two components. The interaction also reduces the strong enthalpy of interaction between CO2 and SO2 and the ionic liquid at high temperatures. By controlling the desorption temperature, the weaker CO2 bonds and the stronger SO2 bonds are broken in a directional manner, achieving efficient separation of CO2 and SO2. Based on this, a carbon-sulfur synergistic capture and high-efficiency separation device was constructed. By fully contacting the flue gas and the functional ionic liquid in the absorption tower, the special functional groups on the ionic liquid combine with CO2 and SO2 in the flue gas to form chemical bonds. At the same time, the solution properties of the ionic liquid are utilized to physically adsorb CO2 and SO2, achieving large-capacity synergistic capture of CO2 and SO2. Given that the binding strength between CO2 and SO2 and the functional groups of the ionic liquid is different, and the van der Waals force binding strength is different when dissolved in solution, two desorption towers are set up in sequence and the temperature is controlled by a solution reboiler. First, CO2 is separated at low temperature in the carbon dioxide desorption tower, and then SO2 is separated at higher temperature in the sulfur dioxide desorption tower. The desorption temperatures of both components are low, the separation conditions are mild, and energy consumption is significantly reduced.

[0040] Unlike the typical adsorption (low-temperature adsorption) and desorption (intermediate-temperature release of SO2, high-temperature release of CO2) of gases by ionic liquids, the absorbent used in this application, namely the functional ionic liquid, exhibits stronger chemical or physical adsorption forces on SO2, resulting in more stable substances after adsorption. For example, the stability of sulfites / bisulfites formed by the functional groups of the ionic liquid with SO2 is greater than that of carbonates / bicarbonates formed with CO2. Therefore, higher energy is required for desorption to overcome the forces between the gas and the absorbent. Based on this, this application employs a sequential heating method to desorb the two components. The carbon dioxide desorption tower is connected to the absorption tower. In the carbon dioxide desorption tower, the temperature is adjusted to 95℃~102℃ using a solution reboiler to desorb CO2. Then, the solution enters the sulfur dioxide desorption tower, where the temperature is adjusted to 103℃~106℃ using a solution reboiler to desorb SO2.

[0041] Examples of specific functional ionic liquids include: 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate, wherein the carbon dioxide-loving group is an imidazolium group and the sulfur dioxide-loving group is an ether group (-O-). N-methyl-N-(2-aminoethyl)piperidine hydrogen sulfate, wherein the carbon dioxide-loving group is a quaternary ammonium group (formed by quaternization of the nitrogen atom of the piperidine ring) and the sulfur dioxide-loving group is an amino group. 4-(3-pyridyl)-1,2,4-triazole tetrafluoroborate, wherein the carbon dioxide-loving groups are pyridyl and triazolyl, and the sulfur dioxide-loving group is an azole group (1,2,4-triazolyl). The first type of alcohol-amine composite ionic liquid has carbon dioxide-loving groups of tertiary amine (-N(CH3)-) and secondary amine (-NH-), and sulfur dioxide-loving groups of amino (-NH2) and primary amine (-NH2). The "effective components" refer to MEDA (N-methyldiethanolamine), L-lysine, and triethylenetetramine. The second type of alcohol-amine composite ionic liquid has carbon dioxide-loving groups of tertiary amine (-N(CH3)-) and secondary amine (-NH-), and sulfur dioxide-loving groups of primary amine (-NH2). The "effective components" refer to diethylenetriamine, methyldiethanolamine, and dihydroxyethylpiperazine. It should be noted that the functional ionic liquids of this application are not limited to these. In practical applications, the concentration of the effective components in the functional ionic liquid can be controlled to 15-25%. Here, "effective components" specifically refers to the substances corresponding to the carbon dioxide-loving or sulfur dioxide-loving groups.

[0042] Figure 1 The diagram shows a schematic of a carbon-sulfur synergistic capture and efficient separation device provided in some embodiments of this application. It includes an absorption tower 3, a carbon dioxide desorption tower 6, and a sulfur dioxide desorption tower 10 connected in sequence, which sequentially perform carbon-sulfur capture, CO2 desorption, and SO2 desorption.

[0043] The liquid inlet of the absorption tower 3 is located at the top and connected to the ionic liquid feed pump 2, while the gas inlet is located at the bottom and connected to the flue gas induced draft fan 1. The functional ionic liquid is sprayed downwards from the top via a spray device, and flue gas is drawn into the absorption tower 3 from the bottom. The flue gas temperature is 60℃~80℃, the CO2 content is 6%~15%, and the SO2 content is 14%~20%. The flue gas and functional ionic liquid flow counter-currently, ensuring full contact and a two-phase reaction, achieving the synergistic capture of carbon dioxide and sulfur dioxide. An exhaust flue is also provided at the top of the absorption tower 3, through which the remaining gas after capture is discharged. Furthermore, the flow rate of the functional ionic liquid can be controlled by adjusting the spray volume of the spray device, and the flue gas velocity can be adjusted by regulating the induced draft fan, i.e., controlling the liquid-to-gas ratio to ensure stable reaction.

[0044] The reaction occurs within the absorption tower: The weakly acidic CO2 gas first dissolves in the aqueous solution to form weak carbonic acid (here, the aqueous solution refers to the water contained in the ionic liquid preparation process, a component of the functional ionic liquid). Subsequently, it combines with specific CO2-binding groups in the functional ionic liquid, forming stable adsorbed CO2 in the form of carbonate ions. Simultaneously, groups specifically binding to sulfite ions are exposed, increasing the number of sulfite binding sites. SO2 also dissolves in the aqueous solution to form sulfurous acid. Sulfite ions combine with the exposed specific sites, forming stable adsorbed SO2 in the form of sulfite ions. This increases the adsorption capacity of SO2, achieving synergistic capture of CO2 and SO2, with both CO2 and SO2 adsorption capacities exceeding 90%. The reverse mechanism also works: adsorbing SO2 first exposes more CO2 binding sites, thus increasing the CO2 adsorption capacity.

[0045] The liquid outlet of the absorption tower 3 is located at the bottom and is connected to the refrigerant inlet of the heat exchanger 5 through the first transfer pump 4. The carbon-rich sulfur ion liquid after being collected is heated by the heat exchanger 5 and then enters the carbon dioxide desorption tower 6. A pH meter is installed at the bottom of the absorption tower 3.

[0046] In practical applications, the pH of the ionic liquid in absorption tower 3 is monitored. When the pH of the ionic liquid in absorption tower 3 reaches 4.9–5.1, for example, 5.0, the ionic liquid at the bottom of absorption tower 3 is transferred to heat exchanger 5 and carbon dioxide desorption tower 6 via the first transfer pump 4. The carbon- and sulfur-rich ionic liquid is heated by the heat exchanger and then enters carbon dioxide desorption tower 6 for carbon dioxide desorption.

[0047] The liquid inlet of the carbon dioxide desorption tower 6 is located at the top and is connected to the refrigerant outlet of the heat exchanger 5. The gas outlet is located at the top and is connected to the first cooler 8. The first solution reboiler 7 equipped with a steam heat exchange system is connected to the lower part of the carbon dioxide desorption tower 6. The inlet and outlet of the first solution reboiler 7 are connected to the outlet of the carbon dioxide desorption tower 6 and the desorbed material return port, respectively. The desorbed material return port is higher than the outlet of the carbon dioxide desorption tower 6.

[0048] The carbon-rich sulfur ion liquid is heated from 20-30°C to 50-60°C through a heat exchanger. After heating, the carbon-rich sulfur ion liquid is pumped into the carbon dioxide desorption tower 6 and sprayed from the top. After being sprayed and dispersed by a spraying device, it flows through the packing layer of the carbon dioxide desorption tower and enters the bottom of the tower. After being heated to 90-102°C by a solution reboiler, CO2 is desorbed. The carbon-lean sulfur-rich ion liquid after CO2 desorption returns to the bottom of the carbon dioxide desorption tower 6. The desorbed high-heat CO2 gas (rising) and the carbon-rich sulfur ion liquid flowing down from the top of the tower exchange heat countercurrently at the packing layer of the tower, causing some of the CO2 in the carbon-rich sulfur ion liquid to desorb. The CO2 gas desorbed in the tower carries some water vapor and enters the first cooler 8 from the gas outlet at the top of the tower, causing the water vapor to condense and flow back. The enriched CO2 enters the next process or is stored in a carbon dioxide storage tank for later use.

[0049] The outlet of the carbon dioxide desorption tower 6 is located at the bottom and is connected to the inlet of the sulfur dioxide desorption tower 10 through the second transfer pump 9. The bottom of the carbon dioxide desorption tower 6 is equipped with a pH detector.

[0050] In practical applications, the pH of the ionic liquid at the bottom of the carbon dioxide desorption tower 6 is monitored. When the pH of the ionic liquid reaches 5.4 to 5.6, for example, 5.5, the carbon-poor and sulfur-rich ionic liquid at the bottom of the carbon dioxide desorption tower 6 is transferred to the sulfur dioxide desorption tower 10 via the second transfer pump 9.

[0051] The liquid inlet of the sulfur dioxide desorption tower 10 is located at the top and is connected to the outlet of the second transfer pump 9. The gas outlet is located at the top and is connected to the second cooler 12. A second solution reboiler 11 equipped with a steam heat exchange system is connected to the lower part of the sulfur dioxide desorption tower 10. The inlet and outlet of the second solution reboiler are connected to the outlet of the sulfur dioxide desorption tower 10 and the desorbed material return port, respectively. The desorbed material return port of the sulfur dioxide desorption tower is higher than its outlet.

[0052] After CO2 removal, the lean carbon and sulfur-rich ionic liquid is sprayed from the top of the sulfur dioxide desorption tower 10 by the second transfer pump 9 and dispersed by the spraying device. It then flows through the packing layer of the sulfur dioxide desorption tower and enters the bottom of the tower. After being heated to 103-106℃ by the second solution reboiler, SO2 is desorbed. The desorbed lean ionic liquid returns to the bottom of the sulfur dioxide desorption tower 10. The desorbed high-heat SO2 gas rises and exchanges heat countercurrently with the lean carbon and sulfur-rich ionic liquid flowing down from the top of the tower at the packing layer, causing some of the SO2 in the lean carbon and sulfur-rich ionic liquid to desorb. The desorbed SO2 gas in the tower carries some water vapor into the second cooler 12 at the top of the tower, where the water vapor is condensed and refluxed. The enriched SO2 enters the next process or is stored in the sulfur dioxide storage tank for later use.

[0053] The outlet of the sulfur dioxide desorption tower 10 is located at the bottom and is connected to the heat medium inlet of the heat exchanger 5. The heat medium outlet of the heat exchanger 5 is connected to the return outlet at the top of the absorption tower 3 through the third transfer pump 13. A pH meter is installed at the bottom of the sulfur dioxide desorption tower 10.

[0054] In practical applications, the pH of the ionic liquid at the bottom of the sulfur dioxide desorption tower is monitored. When the pH reaches 6.2–6.4, for example, 6.3, the lean ionic liquid at the bottom of the tower is transferred to the absorption tower via a third transfer pump. During the transfer to the absorption tower, the lean ionic liquid is cooled from 95–100°C to 50–60°C via heat exchanger 5. After cooling, it is transferred back to the absorption tower and sprayed downwards from the top for reuse. Furthermore, during application, the volume loss of the regenerated liquid can be observed and recorded for replenishment. The regenerated liquid refers to the regenerated functional ionic liquid, i.e., the lean ionic liquid that continues to be used as a functional ionic liquid after carbon and sulfur capture and separation. Volume loss is the reduction in volume relative to the original functional ionic liquid. Replenishment is performed when the volume loss reaches a certain proportion.

[0055] The application process of the device of this application is described below with reference to specific application embodiments: Application Example 1 To process gas volume of 10m³ 3 Taking / h as an example, the CO2 concentration in the flue gas is 10%, and the SO2 concentration is 15%. The application process is as follows: 1) After dust removal and cooling, the flue gas is drawn into the bottom of the absorption tower 3 by the flue gas induced draft fan 1. A 10kW fan is used for induced draft. A functional ionic liquid that can synergistically capture CO2 and SO2, with an effective component concentration of approximately 20%, is injected from the top of the absorption tower 3 through the ionic liquid feed pump 2 and sprayed downwards by a spray device at a rate of 500L / h. The flue gas and the ionic liquid are in countercurrent contact and undergo a two-phase reaction. The functional ionic liquid is an alcoholamine composite ionic liquid. The CO2-loving groups are tertiary amine groups (-N(CH3)-) and secondary amine groups (-NH-), and the SO2-loving groups are amino groups (-NH2) and primary amine groups (-NH2). The "effective component" refers to MEDA (N-methyldiethanolamine), L-lysine, and triethylenetetramine.

[0056] 2) When the pH of the ionic liquid captured by the absorption tower 3 reaches 5.0, the first transfer pump 4 is randomly turned on to transfer the ionic liquid enriched with CO2 and SO2 at the bottom of the absorption tower 3 to the sulfur dioxide desorption tower 10 through the heat exchanger 5.

[0057] 3) The CO2 and SO2 enriched ionic liquid is heated from 25°C to 55°C by heat exchanger 5. After heat exchange, it is sprayed from the top of the carbon dioxide desorption tower 6. After being dispersed by the spraying device, it flows through the packing layer of the carbon dioxide desorption tower and enters the bottom of the tower. After being heated to 100°C by the first solution reboiler 7, CO2 is desorbed. The desorbed CO2-poor and SO2-rich ionic liquid returns to the bottom of the tower, and the liquid temperature is maintained at about 100°C. The desorbed high-heat CO2 gas returns to the tower and rises. During the process, it exchanges heat countercurrently with the CO2 and SO2 enriched ionic liquid flowing down from the top of the tower, causing some of the CO2 in the enriched CO2 and SO2 ionic liquid to be desorbed. The CO2 gas desorbed in the tower carries some water vapor into the first cooler 8 at the top of the tower, so that the water vapor is condensed and refluxed. The enriched CO2 enters the next process, and the CO2 enrichment concentration reaches more than 90%.

[0058] 4) When the pH of the ionic liquid in CO2 desorption tower 6 reaches 5.5 after multiple CO2 desorptions, the second transfer pump 9 is randomly turned on to transfer the CO2-poor and SO2-rich ionic liquid to sulfur dioxide desorption tower 10.

[0059] 5) The CO2-lean and SO2-rich ionic liquid after CO2 removal is sprayed from the top of the sulfur dioxide desorption tower 10 by the second transfer pump 9. The liquid phase temperature is about 90℃. After being dispersed and sprayed by the spray device, it flows through the packing layer of the sulfur dioxide desorption tower and enters the bottom of the tower. After being heated to 105℃ by the second solution reboiler 11 equipped with a steam heat exchange system, SO2 is desorbed. The desorbed lean ionic liquid returns to the bottom of the sulfur dioxide desorption tower. The desorbed high-heat SO2 gas returns to the tower and exchanges heat countercurrently with the CO2-lean and sulfur-rich ionic liquid flowing down from the top of the tower during the rising process, so that some of the SO2 in the CO2-lean and SO2-rich ionic liquid is desorbed. The desorbed SO2 gas in the tower carries some water vapor into the second cooler 12 at the top of the tower, so that the water vapor is condensed and refluxed. The enriched SO2 enters the next process, and the enriched SO2 concentration reaches more than 90%.

[0060] 6) When the pH of the ionic liquid in the sulfur dioxide desorption tower 10 reaches 6.3 after multiple SO2 desorptions, the third transfer pump 13 is turned on to transfer the lean ionic liquid to the heat exchanger 5.

[0061] 7) The desorbed lean ion liquid is cooled by heat exchanger 5, with the liquid ion liquid decreasing in temperature from 98℃ to 55℃. It is then transported back to the top of absorption tower 3 by the third transfer pump 13 for spray reabsorption. The volume loss of the regenerated liquid is only 0.1%. After a certain reaction time, the ion liquid is replenished by the ion liquid feed pump. The above process is repeated.

[0062] Application Example 2 To process gas volume of 2m 3 Taking / h as an example, the CO2 concentration in the flue gas is 10%, and the SO2 concentration is 15%. The application process is as follows: 1) After dust removal and cooling, the flue gas is drawn into the bottom of the absorption tower by the flue gas induced draft fan 1. A 2kW fan is used for induced draft. A functional ionic liquid capable of synergistically capturing CO2 and SO2, with an effective component concentration of approximately 20%, is injected from the top of the absorption tower 3 through the ionic liquid feed pump 2 and sprayed downwards by a spray device at a rate of 50L / h. The flue gas and the ionic liquid come into countercurrent contact, resulting in a two-phase reaction. The functional ionic liquid is an alcoholamine composite ionic liquid. The CO2-loving groups are tertiary amine groups (-N(CH3)-) and secondary amine groups (-NH-), and the SO2-loving group is a primary amine group (-NH2). The "effective component" refers to diethylenetriamine, methyldiethanolamine, and dihydroxyethylpiperazine.

[0063] 2) When the pH of the ionic liquid captured by the absorption tower 3 reaches the specified value of 5.0, the rich liquid pump 4 is randomly turned on to transfer the ionic liquid enriched with CO2 and SO2 at the bottom of the absorption tower to the sulfur dioxide desorption tower 10 through the heat exchanger 5.

[0064] 3) The CO2 and SO2 enriched ionic liquid is heated by heat exchanger 5 from 27°C to 58°C. After heat exchange, it is sprayed from the top of the carbon dioxide desorption tower 6 and dispersed by the spraying device. It then flows through the packing layer of the carbon dioxide desorption tower and enters the bottom of the tower. After being heated to 100°C by the first solution reboiler 7, the CO2 is desorbed. The CO2-poor and SO2-rich ionic liquid returns to the bottom of the tower, and the liquid temperature is maintained at about 100°C. The desorbed high-heat CO2 gas returns to the tower and exchanges heat countercurrently with the CO2 and SO2 enriched ionic liquid flowing down from the top of the tower during the rising process. This causes some of the CO2 in the CO2 and SO2 enriched ionic liquid to be desorbed. The CO2 gas desorbed in the tower carries some water vapor into the first cooler 8 at the top of the tower, where the water vapor is condensed and refluxed. The enriched CO2 enters the next process, and the CO2 enrichment concentration reaches more than 90%.

[0065] 4) When the pH of the ionic liquid in the carbon dioxide desorption tower 6 reaches 5.5 after multiple CO2 desorptions, the semi-rich liquid pump 9 is randomly turned on to transfer the CO2-poor and SO2-rich ionic liquid to the sulfur dioxide desorption tower 10.

[0066] 5) The CO2-lean and SO2-rich ionic liquid after CO2 removal is sprayed from the top of the sulfur dioxide desorption tower 10 by the second transfer pump 9. The liquid phase temperature is about 90℃. After being dispersed and sprayed by the spray device, it flows through the packing layer of the sulfur dioxide desorption tower and enters the bottom of the tower. After being heated to 105℃ by the second solution reboiler 11, SO2 is desorbed. The desorbed lean ionic liquid returns to the bottom of the sulfur dioxide desorption tower. The desorbed high-heat SO2 gas returns to the tower and exchanges heat countercurrently with the CO2-lean and SO2-rich ionic liquid flowing down from the top of the tower during the rising process. This causes some of the SO2 in the CO2-lean and SO2-rich ionic liquid to be desorbed. The SO2 gas desorbed in the tower carries some water vapor into the second cooler 12 at the top of the tower, where the water vapor is condensed and refluxed. After enrichment, the SO2 enters the next process, and the enriched SO2 concentration reaches more than 90%.

[0067] 6) When the pH of the ionic liquid in the sulfur dioxide desorption tower 10 reaches 6.3 after multiple SO2 desorptions, the third transfer pump 13 is turned on to transfer the lean ionic liquid to the heat exchanger 5.

[0068] 7) The desorbed lean ion liquid is cooled by heat exchanger, with the liquid ion liquid decreasing in temperature from 95-100℃ to 50-60℃. It is then transported back to the top of absorption tower 3 by the third transfer pump 13 for spray reabsorption. The volume loss of the regenerated liquid is only 0.1%. After a certain reaction time, the regenerated liquid is replenished by the ion liquid feed pump. The above process is repeated.

[0069] The description in this application is given for illustrative purposes and is not intended to be exhaustive or to limit the application to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of this application and to enable those skilled in the art to understand this application and design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A carbon-sulfur synergistic capture and high-efficiency separation device, characterized in that, It includes an absorption tower, a carbon dioxide desorption tower and a sulfur dioxide desorption tower connected in sequence, as well as a first transfer pump, a second transfer pump and a third transfer pump; The absorption tower has an inlet connected to an ionic liquid feed pump for feeding functional ionic liquid, an inlet connected to a flue gas induced draft fan, and an outlet connected to the inlet of a carbon dioxide desorption tower via a heat exchanger. A first solution reboiler is connected to the lower part of the carbon dioxide desorption tower to control the carbon dioxide desorption temperature at 90–102°C. The outlet of the carbon dioxide desorption tower is connected to the inlet of a sulfur dioxide desorption tower. A second solution reboiler is connected to the lower part of the sulfur dioxide desorption tower to control the sulfur dioxide desorption temperature at 103–106°C. pH meters are installed at the lower parts of the absorption tower, carbon dioxide desorption tower, and sulfur dioxide desorption tower. A first delivery pump is located between the outlet of the absorption tower and the heat exchanger, a second delivery pump is located between the carbon dioxide desorption tower and the sulfur dioxide desorption tower, and a third delivery pump is located between the heat exchanger and the return outlet of the absorption tower. The first pump is used to transfer the ionic liquid at the bottom of the absorption tower to the heat exchanger and the carbon dioxide desorption tower when the pH detector in the absorption tower detects that the pH of the ionic liquid reaches 4.9-5.1; the second pump is used to transfer the carbon-lean and sulfur-rich ionic liquid at the bottom of the carbon dioxide desorption tower to the sulfur dioxide desorption tower when the pH detector at the bottom of the carbon dioxide desorption tower detects that the pH of the ionic liquid reaches 5.4-5.6; and the third pump is used to transfer the lean ionic liquid at the bottom of the sulfur dioxide desorption tower to the absorption tower when the pH detector at the bottom of the sulfur dioxide desorption tower detects that the pH of the ionic liquid reaches 6.2-6.

4.

2. The carbon-sulfur synergistic capture and high-efficiency separation device according to claim 1, characterized in that, The outlet of the sulfur dioxide desorption tower is connected to the return outlet of the absorption tower via a heat exchanger.

3. The carbon-sulfur synergistic capture and high-efficiency separation device according to claim 2, characterized in that, The refrigerant inlet and outlet of the heat exchanger are connected to the liquid outlet of the absorption tower and the liquid inlet of the carbon dioxide desorption tower, respectively, while the heat medium inlet and outlet are connected to the liquid outlet of the sulfur dioxide desorption tower and the liquid return outlet of the absorption tower, respectively.

4. The carbon-sulfur synergistic capture and high-efficiency separation device according to claim 2, characterized in that, The first solution reboiler has an inlet and an outlet, which are respectively connected to the outlet of the carbon dioxide desorption tower and the desorbed material return port; The second solution reboiler has an inlet and an outlet, which are respectively connected to the outlet of the sulfur dioxide desorption tower and the desorbed material return port.

5. The carbon-sulfur synergistic capture and high-efficiency separation device according to claim 4, characterized in that, The return port of the desorbed material in the carbon dioxide desorption tower is higher than the outlet of the carbon dioxide desorption tower; The return port of the desorbed material in the sulfur dioxide desorption tower is higher than the outlet of the sulfur dioxide desorption tower.

6. The carbon-sulfur synergistic capture and high-efficiency separation device according to claim 2, characterized in that, The outlet of the carbon dioxide desorption tower is connected to a first cooler, and the first cooler is connected to a carbon dioxide storage tank. The outlet of the sulfur dioxide desorption tower is connected to a second cooler, which is connected to a sulfur dioxide storage tank.

7. The carbon-sulfur synergistic capture and high-efficiency separation device according to claim 6, characterized in that, The absorption tower has its liquid inlet at the top, air inlet at the bottom, liquid outlet at the bottom, return outlet at the top, and spray device at the top. The inlet of the carbon dioxide desorption tower is located at the top, the outlet is located at the top, the liquid outlet is located at the bottom, and the spray device is located at the top. The sulfur dioxide desorption tower has its liquid inlet at the top, its gas outlet at the top, its liquid outlet at the bottom, and its spray device at the top.

8. The carbon-sulfur synergistic capture and high-efficiency separation device according to claim 1, characterized in that, It also includes an ionic liquid storage device connected to the ionic liquid feed pump; the ionic liquid storage device contains a functional ionic liquid, wherein the functional ionic liquid has carbon dioxide-loving groups and sulfur dioxide-loving groups introduced on its anion and cation sites.

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