Coal-fired power plant carbon capture coupled with electrodialysis for alkali production and sodium bicarbonate co-production system

Abstract

This application relates to the field of carbon capture and utilization and saline wastewater recycling and treatment technology, specifically disclosing a carbon capture coupled with electrodialysis system for alkali production and sodium bicarbonate co-production in a coal-fired power plant. The main purpose is to achieve synergistic linkage between carbon capture, by-product salt resource utilization, and high-value product co-production, balancing environmental protection and economic benefits. The main technical solution of this application is as follows: the system includes a carbon capture unit, a bipolar membrane electrodialysis unit, and a carbonization co-production unit; the carbon capture unit is used to capture carbon dioxide from the flue gas of a coal-fired power plant and uses the waste heat of the power plant as a heat source for the carbon dioxide desorption process; the bipolar membrane electrodialysis unit is driven by green electricity and is used to electrolyze industrial sodium sulfate solution to generate sodium hydroxide solution and sulfuric acid solution; the carbonization co-production unit is connected to the carbon capture unit and the bipolar membrane electrodialysis unit, and is used to perform a directional carbonization reaction between the carbon dioxide and the sodium hydroxide solution to produce sodium bicarbonate.

Description

Technical Field

[0001] This application belongs to the field of carbon capture and utilization and saline wastewater recycling and treatment technology, specifically relating to a carbon capture coupled with electrodialysis alkali production and sodium bicarbonate co-production system in a coal-fired power plant. Background Technology

[0002] In related technologies, the utilization methods after carbon dioxide capture are relatively simple, mainly focusing on storage, with insufficient utilization of high-value components. Storage not only requires significant investment in the construction of related equipment, energy consumption maintenance during operation, and long-term monitoring, but also struggles to generate direct economic benefits. This leads to practical problems such as financing difficulties and poor sustainability in the promotion of carbon dioxide capture projects.

[0003] Meanwhile, the resource utilization of industrial by-product salts has gradually become a key bottleneck restricting the sustainable development of production enterprises, with the treatment of industrial by-product sodium sulfate being particularly prominent. Specifically, on the one hand, if enterprises use conventional multi-effect concentration technology to process by-product sodium sulfate, salt separation requires multiple evaporation and crystallization processes. This process continuously consumes large amounts of steam or electricity, resulting in high energy consumption. For enterprises with large by-product salt production, continuing to use this technology long-term will impose a heavy economic burden. On the other hand, both the external sales and internal recycling of sodium sulfate are limited: influenced by the supply and demand patterns in the downstream market, by-product sodium sulfate generally suffers from poor sales; moreover, by-product sodium sulfate often has quality defects such as purity fluctuations and unstable impurity content, making its market competitiveness far lower than that of industrially refined sodium sulfate, hindering the smooth progress of its external resource utilization path. Summary of the Invention

[0004] In view of this, this application provides a carbon capture coupled with electrodialysis for alkali production and sodium bicarbonate co-production in a coal-fired power plant. The main purpose is to solve the dual pain points of insufficient high-value utilization of carbon dioxide capture, poor economic benefits of the storage mode, and high energy consumption and limited resource utilization of industrial by-product sodium sulfate in related technologies. It achieves synergistic linkage between carbon capture, by-product salt resource utilization and high-value product co-production, taking into account both environmental protection and economic benefits.

[0005] To achieve the above objectives, this application mainly provides the following technical solutions: This application provides a carbon capture coupled with electrodialysis system for alkali production and sodium bicarbonate co-production in a coal-fired power plant, including a carbon capture unit, a bipolar membrane electrodialysis unit, and a carbonization co-production unit. The carbon capture unit is used to capture carbon dioxide from the flue gas of a coal-fired power plant and to use the waste heat of the coal-fired power plant as a heat source for the carbon dioxide desorption process. The bipolar membrane electrodialysis unit is driven by green electricity and is used to electrolyze industrial sodium sulfate solution to generate sodium hydroxide solution and sulfuric acid solution. The carbonization co-production unit is connected to the carbon capture unit and the bipolar membrane electrodialysis unit, and is used to carry out a directional carbonization reaction between the carbon dioxide and the sodium hydroxide solution to obtain sodium bicarbonate product.

[0006] Optionally, the carbon capture unit includes an absorption tower, a lean-rich liquid heat exchanger, a desorption tower, a reboiler, a condenser, a regenerated gas separator, a purification device, and a carbon dioxide storage tank group. The absorption tower is used to spray lean amine solution to absorb carbon dioxide in the flue gas of coal-fired power plants. The rich amine solution output end of the absorption tower is connected to the refrigerant input end of the lean-rich solution heat exchanger via a rich solution pump. The lean-rich solution heat exchanger is used to preheat the rich amine solution and transport the preheated rich amine solution to the rich amine solution input end of the desorption tower through its refrigerant output end. The desorption tower is used to desorb the preheated rich amine solution to release carbon dioxide and regenerate the lean amine solution. The reboiler is connected to the desorption tower, and the reboiler is used to provide heat and separation power for the carbon dioxide desorption process of the desorption tower by utilizing the waste heat of the coal-fired power plant. The carbon dioxide output end of the desorption tower is connected to the input end of the condenser, and the output end of the condenser is connected to the regeneration gas separator. The regeneration gas separator is used to perform gas-liquid separation on the carbon dioxide mixture. The gas phase output end of the regeneration gas separator is connected to the purification device, which is used to remove impurities from the carbon dioxide. The output end of the purification device is connected to the carbon dioxide storage tank group via a compressor and a liquefier, which is used to store carbon dioxide.

[0007] Optionally, the carbon capture unit further includes a flash compression device and a lean liquid pump; the flash compression device is connected to the desorption tower, and is used to flash the lean amine solution in the desorption tower, and to pressurize and heat the secondary steam generated by flash evaporation and then send it back to the desorption tower; the input end of the lean liquid pump is connected to the lean amine solution output end of the flash compression device and the lean amine solution output end of the desorption tower, respectively, and the output end of the lean liquid pump is connected to the heat medium input end of the lean-rich liquid heat exchanger, and the heat medium output end of the lean-rich liquid heat exchanger is connected to the absorption tower, for transporting the lean amine solution to the absorption tower for circulating spraying.

[0008] Optionally, the carbon capture unit further includes a lean liquid cooler, which is connected between the heat medium output end of the lean-rich liquid heat exchanger and the lean amine liquid input end of the absorption tower. The lean liquid cooler is used to further cool the lean amine liquid after it has been cooled by the lean-rich liquid heat exchanger, so that the temperature of the lean amine liquid is adapted to the carbon dioxide absorption conditions of the absorption tower before it is delivered to the absorption tower for spraying.

[0009] Optionally, an interstage cooler is provided in the middle of the absorption tower body. The interstage cooler is used to cool the gas-liquid contact system in the absorption tower, so as to improve the absorption driving force and carbon dioxide load of the absorption tower for carbon dioxide in the flue gas of coal-fired power plants.

[0010] Optionally, the bipolar membrane electrodialysis unit includes a bipolar membrane electrodialysis stack, a brine tank, a pure water tank, and an electrode water storage tank; the brine tank stores pretreated industrial sodium sulfate solution, and is connected to the salt chamber of the bipolar membrane electrodialysis stack for supplying 10% sodium sulfate solution to the salt chamber; the pure water tank is connected to the acid and alkali chambers of the bipolar membrane electrodialysis stack for supplying pure water to the acid and alkali chambers; the electrode water storage tank is connected to the electrode chamber of the bipolar membrane electrodialysis stack for supplying 3% sodium sulfate dilute solution to the electrode chamber; the bipolar membrane electrodialysis stack is used to electrolyze the sodium sulfate solution into sodium hydroxide solution and sulfuric acid solution under green electricity drive.

[0011] Optionally, the bipolar membrane electrodialysis stack has a three-compartment configuration, including an anode, a cathode, a bipolar membrane, an anion exchange membrane, and a cation exchange membrane. The bipolar membrane, the anion exchange membrane, and the cation exchange membrane are arranged sequentially to form mutually independent acid chambers, alkali chambers, salt chambers, and electrode chambers. The bipolar membrane undergoes water dissociation to generate hydrogen ions and hydroxide ions. Sodium ions from the sodium sulfate solution dissociated in the salt chamber pass through the cation exchange membrane into the alkali chamber and combine with hydroxide ions to generate sodium hydroxide. Sulfate ions pass through the anion exchange membrane into the acid chamber and combine with hydrogen ions to generate sulfuric acid.

[0012] Optionally, the carbonization co-production unit includes a carbonization reactor, a cooling crystallization tank, a separation and drying device, and an alkali heat exchanger; the alkali heat exchanger is connected to the alkali chamber of the bipolar membrane electrodialysis stack and is used to preheat the sodium hydroxide solution output from the alkali chamber; the carbonization reactor is connected to the alkali heat exchanger and the carbon dioxide storage tank group respectively, and is used to cause the preheated sodium hydroxide solution to undergo a directional carbonization reaction with carbon dioxide to generate a sodium bicarbonate suspension; the cooling crystallization tank is connected to the carbonization reactor and is used to cool and crystallize the sodium bicarbonate suspension to precipitate sodium bicarbonate in crystalline form; the separation and drying device is connected to the cooling crystallization tank and is used to perform solid-liquid separation and drying of the sodium bicarbonate crystals to obtain sodium bicarbonate finished product.

[0013] Optionally, the carbonization reactor is equipped with a stirrer with a stirring speed of 40 to 60 revolutions per minute; the carbonization reactor is equipped with a thermostat to control the reaction temperature inside the carbonization reactor at about 30 degrees Celsius.

[0014] Optionally, the carbonization reactor is used to introduce carbon dioxide into the sodium hydroxide solution in stages, and to stop introducing carbon dioxide when the pH value of the solution reaches 8.0 to 8.5. After stirring and aging, a sodium bicarbonate suspension is generated. The cooling crystallization tank is used to control the temperature of the sodium bicarbonate suspension at 10 to 15 degrees Celsius, so that sodium bicarbonate precipitates in crystal form. A suspension pump is provided between the cooling crystallization tank and the carbonization reactor for transporting the sodium bicarbonate suspension.

[0015] By employing the above technical solution, this application has at least the following beneficial effects: The carbon capture coupled with electrodialysis system for alkali production and sodium bicarbonate co-production in coal-fired power plants provided in this application effectively solves the problems of insufficient high-value utilization of captured carbon dioxide and difficulties in the resource-based treatment of industrial by-product sodium sulfate through the synergistic cooperation of the carbon capture unit, bipolar membrane electrodialysis unit, and carbonization co-production unit. Specifically, the carbon capture unit can utilize the waste heat of the coal-fired power plant to provide a heat source for its own carbon dioxide desorption process, efficiently capturing carbon dioxide from the flue gas of the coal-fired power plant, providing directly usable high-purity carbon dioxide feedstock for subsequent resource utilization, thus achieving the initial resource utilization of carbon dioxide. At the same time, the steam is pressurized and heated using flash evaporation and steam recompression (MVR) technology and sent back to the desorption tower to reduce the amount of heating steam used in the reboiler, further reducing the operating energy consumption and cost of the carbon capture unit, and alleviating the problems of financing difficulties and poor sustainability of carbon capture projects. The bipolar membrane electrodialysis unit, driven by green electricity, can electrolyze industrial sodium sulfate solution to generate sodium hydroxide solution and sulfuric acid solution. Utilizing the water dissociation characteristics of the bipolar membrane, this technology can directly convert sodium sulfate solution into sodium hydroxide and sulfuric acid under an electric field. The market demand for these two products is stable year-round, and their added value is far higher than that of ordinary by-product sodium sulfate. Furthermore, this technology does not require stringent high-temperature and high-pressure operating conditions, significantly reducing energy consumption compared to traditional multi-effect concentration technology. The entire processing flow is closed-loop and controllable, with no secondary pollution. It eliminates the need for ordinary multi-effect concentration technology to treat industrial by-product sodium sulfate, avoiding the high energy consumption problems caused by multiple evaporation and crystallization processes, thus reducing the economic burden on enterprises. Simultaneously, it achieves the resource-based transformation of industrial by-product sodium sulfate, solving the problems of limited market sales and internal recycling. It not only efficiently solves the disposal problem of by-product sodium sulfate but also opens up new profit growth points for enterprises, truly achieving the core goal of resource utilization—treating waste with waste and turning waste into treasure. The carbonation co-production unit is connected to the carbon capture unit and the bipolar membrane electrodialysis unit. It enables a directional carbonation reaction between the carbon dioxide captured by the carbon capture unit and the sodium hydroxide solution generated by the bipolar membrane electrodialysis unit, producing sodium bicarbonate as a finished product. This further realizes the high-value utilization of carbon dioxide, improves the economic efficiency of the entire system, and directly contributes to carbon reduction in the industrial sector through carbon capture and resource utilization. It provides practical technical support for achieving carbon peaking and carbon neutrality goals. Furthermore, it can convert chemical solid waste sodium sulfate into a high-value-added usable resource, simultaneously realizing the reduction, resource utilization, and harmless treatment of industrial waste. In other words, the synergistic cooperation of the carbon capture unit, the bipolar membrane electrodialysis unit, and the carbonation co-production unit achieves efficient capture and resource utilization of carbon dioxide in the flue gas of coal-fired power plants, low-consumption and clean treatment of industrial by-product sodium sulfate, and co-production of sodium hydroxide solution, sulfuric acid solution, and sodium bicarbonate, balancing environmental and economic benefits and promoting the sustainable development of production enterprises. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a coal-fired power plant carbon capture coupled with electrodialysis for alkali production and sodium bicarbonate co-production, according to an optional embodiment of this application. Figure 2 This is a schematic diagram of the structure of a carbon capture unit according to an optional embodiment of this application; Figure 3 This is a schematic diagram of the structure of a bipolar membrane electrodialysis stack according to an optional embodiment of this application; Figure 4 This is a schematic diagram of the structure of a carbonization cogeneration unit according to an optional embodiment of this application.

[0017] The reference numerals in the attached figures are as follows: 1. Carbon capture unit; 101. Absorption tower; 102. Lean and rich liquor heat exchanger; 103. Desorption tower; 104. Reboiler; 105. Condenser; 106. Regenerated gas separator; 107. Purification unit; 108. Carbon dioxide storage tank group; 109. Rich liquor pump; 110. Compressor; 111. Liquefaction unit; 112. Flash compression unit; 113. Lean liquor pump; 114. Lean liquor cooler; 115. Interstage cooler; 116. Reflux pump; 2 1. Bipolar membrane electrodialysis unit; 201. Anode; 202. Cathode; 203. Bipolar membrane; 204. Anion exchange membrane; 205. Cation exchange membrane; 3. Carbonization co-production unit; 301. Carbonization reactor; 302. Cooling crystallizer; 303. Separation and drying equipment; 304. Alkali heat exchanger; 305. Stirrer; 306. Thermostat; 307. Suspension pump; 4. Feed liquid pretreatment device; 5. Cooling crystallizer; 6. Washing and drying unit. Detailed Implementation

[0018] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0020] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0021] The preferred embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0022] See also Figures 1 to 4 As shown in the embodiments of this application, a carbon capture coupled with electrodialysis system for producing sodium bicarbonate from a coal-fired power plant is provided, comprising a carbon capture unit 1, a bipolar membrane 203 electrodialysis unit 2, and a carbonation co-production unit 3. The carbon capture unit 1 is used to capture carbon dioxide from the flue gas of the coal-fired power plant and uses the waste heat of the coal-fired power plant as a heat source for the carbon dioxide desorption process. The bipolar membrane 203 electrodialysis unit 2 is driven by green electricity and is used to electrolyze industrial sodium sulfate solution to generate sodium hydroxide solution and sulfuric acid solution. The carbonation co-production unit 3 is connected to the carbon capture unit 1 and the bipolar membrane 203 electrodialysis unit 2 and is used to perform a directional carbonation reaction between carbon dioxide and sodium hydroxide solution to obtain sodium bicarbonate product.

[0023] The carbon capture coupled with electrodialysis system for alkali production and sodium bicarbonate co-production provided in this embodiment of the application effectively solves the problems of insufficient high-value utilization of captured carbon dioxide and difficulty in resource-based treatment of industrial by-product sodium sulfate through the synergistic cooperation of carbon capture unit 1, bipolar membrane 203 electrodialysis unit 2, and carbonization co-production unit 3. Specifically, carbon capture unit 1 can utilize the waste heat of the coal-fired power plant to provide a heat source for its own carbon dioxide desorption process, efficiently capturing carbon dioxide from the flue gas of the coal-fired power plant, providing a high-purity carbon dioxide feedstock that can be directly used for subsequent resource utilization, thereby realizing the initial resource utilization of carbon dioxide. At the same time, it makes full use of the waste heat resources of the coal-fired power plant, reducing the operating energy consumption and cost of carbon capture unit 1, and alleviating the problems of financing difficulties and poor sustainability of carbon capture projects. The bipolar membrane 203 electrodialysis unit 2 is driven by green electricity and can electrolyze industrial sodium sulfate solution to generate sodium hydroxide solution and sulfuric acid solution. Utilizing the water dissociation characteristics of the bipolar membrane 203, the bipolar membrane 203 electrodialysis technology can directly convert sodium sulfate solution into sodium hydroxide and sulfuric acid under an electric field. The market demand for these two products is stable year-round, and their added value is far higher than that of ordinary by-product sodium sulfate. Furthermore, this technology does not require stringent high-temperature and high-pressure operating conditions, significantly reducing energy consumption compared to traditional multi-effect concentration technology. The entire treatment process is closed-loop and controllable, with no secondary pollution. It eliminates the need for ordinary multi-effect concentration technology to treat industrial by-product sodium sulfate, avoiding the high energy consumption problems caused by multiple evaporation and crystallization processes, thus reducing the economic burden on enterprises. Simultaneously, it achieves the resource-based transformation of industrial by-product sodium sulfate, solving the problems of limited market sales and internal recycling. It not only efficiently solves the disposal problem of by-product sodium sulfate but also opens up new profit growth points for enterprises, truly achieving the core resource-based goal of treating waste with waste and turning waste into treasure. The carbonization co-production unit 3 is connected to the carbon capture unit 1 and the bipolar membrane 203 electrodialysis unit 2. It enables the directional carbonization reaction between the carbon dioxide captured by the carbon capture unit 1 and the sodium hydroxide solution generated by the bipolar membrane 203 electrodialysis unit 2, producing sodium bicarbonate. This further realizes the high-value utilization of carbon dioxide, improving the economic efficiency of the entire system. It not only directly contributes to carbon reduction in the industrial sector through carbon dioxide capture and resource utilization, providing practical technical support for achieving carbon peaking and carbon neutrality goals, but also converts chemical solid waste sodium sulfate into high-value-added usable resources, simultaneously realizing the reduction, resource utilization, and harmless treatment of industrial waste. In other words, the synergistic cooperation of the carbon capture unit 1, the bipolar membrane 203 electrodialysis unit 2, and the carbonization co-production unit 3 achieves efficient capture and resource utilization of carbon dioxide in the flue gas of coal-fired power plants, low-consumption and clean treatment of industrial by-product sodium sulfate, and co-production of sodium hydroxide solution, sulfuric acid solution, and sodium bicarbonate, balancing environmental and economic benefits and promoting the sustainable development of production enterprises.

[0024] It is understandable that the waste heat of the coal-fired power plant is specifically the low-grade waste steam heat generated after the steam turbine of the coal-fired power plant does work. This part of the waste heat can be recycled without additional energy consumption and used as the steam heat source for the carbon dioxide desorption process of the carbon capture unit 1. The green electricity is specifically the clean electricity generated by wind power generation and solar photovoltaic power generation, with no carbon emissions throughout the process, providing a green driving energy for the operation of the bipolar membrane 203 electrodialysis unit 2. The industrial sodium sulfate feed liquid is specifically the by-product sodium sulfate waste liquid generated during the industrial production process. After being pretreated by the feed liquid pretreatment device 4 supporting the bipolar membrane 203 electrodialysis unit 2, it can be used as the raw material of the bipolar membrane 203 electrodialysis unit 2. The feed liquid pretreatment device 4 mainly consists of a filtration component, an impurity removal module, a concentration adjustment unit and a pH adjustment unit, which are used to remove harmful components such as suspended impurities and heavy metal ions in the by-product sodium sulfate waste liquid, and adjust the concentration and pH value of the feed liquid to ensure that the feed liquid parameters meet the feeding requirements of the bipolar membrane 203 electrodialysis unit 2, and ensure the stability of the electrolysis process and the purity of the products. The carbon dioxide is specifically the high-purity gas separated and purified from the flue gas of the coal-fired power plant by the carbon capture unit 1. The sodium hydroxide solution and the sulfuric acid solution are the electrolysis products of the bipolar membrane 203 electrodialysis unit 2, and the finished product of sodium bicarbonate is the final product of the carbonization co-production unit 3. The working principle of the whole system is as follows: First, the carbon capture unit 1 uses the low-grade waste steam heat generated by the steam turbine of the coal-fired power plant to provide sufficient heat source for its own carbon dioxide desorption process, efficiently capture the carbon dioxide in the flue gas of the coal-fired power plant, and separate and purify the originally directly emitted carbon dioxide into available raw materials. At the same time, the bipolar membrane 203 electrodialysis unit 2 is driven by the green electricity generated by wind power generation and solar photovoltaic power generation, and electrolyzes the qualified industrial by-product sodium sulfate feed liquid treated by the feed liquid pretreatment device 4 to generate sodium hydroxide solution and sulfuric acid solution, realizing the resource conversion of industrial by-product sodium sulfate. Finally, the carbonization co-production unit 3 is respectively connected to the carbon capture unit 1 and the bipolar membrane 203 electrodialysis unit 2. The high-purity carbon dioxide captured by the carbon capture unit 1 and the sodium hydroxide solution generated by the bipolar membrane 203 electrodialysis unit 2 are introduced into the reaction system for directional carbonization reaction to produce a sodium bicarbonate suspension. The sodium bicarbonate suspension is sequentially processed by a cooling crystallizer 5 and a washing and drying device 6 to obtain the finished product of sodium bicarbonate. The cooling crystallizer 5 is used to cool the sodium bicarbonate suspension to an appropriate temperature to precipitate sodium bicarbonate in crystal form, and the washing and drying device 6 is used to wash and remove impurities and dry the precipitated sodium bicarbonate crystals to ensure the purity and quality of the finished product of sodium bicarbonate. The whole process realizes the coordinated linkage of carbon capture, industrial by-product resource utilization and high-value product co-production, taking into account environmental protection and economic benefits.

[0025] In some possible embodiments disclosed in the present application, refer to Figure 2As shown, the carbon capture unit 1 includes an absorption tower 101, a lean-rich liquid heat exchanger 102, a desorption tower 103, a reboiler 104, a condenser 105, a regenerated gas separator 106, a purification device 107, and a carbon dioxide storage tank group 108. The absorption tower 101 is used to spray lean amine liquid to absorb carbon dioxide from the flue gas of the coal-fired power plant. The rich amine liquid output end of the absorption tower 101 is connected to the refrigerant input end of the lean-rich liquid heat exchanger 102 via a rich liquid pump 109. The lean-rich liquid heat exchanger 102 is used to preheat the rich amine liquid and transport the preheated rich amine liquid to the rich amine liquid input end of the desorption tower 103 through its refrigerant output end. The desorption tower 103 is used to desorb the preheated rich amine liquid to release carbon dioxide and regenerate the lean amine liquid. The reboiler 104... 04 is connected to the desorption tower 103. The reboiler 104 is used to provide heat and separation power for the carbon dioxide desorption process of the desorption tower 103 by utilizing the waste heat of the coal-fired power plant. The carbon dioxide output end of the desorption tower 103 is connected to the input end of the condenser 105. The output end of the condenser 105 is connected to the regeneration gas separator 106. The regeneration gas separator 106 is used to perform gas-liquid separation on the carbon dioxide mixture. The gas phase output end of the regeneration gas separator 106 is connected to the purification device 107. The purification device 107 is used to remove impurities from the carbon dioxide. The output end of the purification device 107 is connected to the carbon dioxide storage tank group 108 via the compressor 110 and the liquefier 111. The carbon dioxide storage tank group 108 is used to store carbon dioxide.

[0026] In this embodiment, the absorption tower 101 can efficiently absorb carbon dioxide from the flue gas of a coal-fired power plant by spraying lean amine solution, laying the foundation for subsequent carbon dioxide desorption and purification, and ensuring the comprehensiveness of carbon dioxide capture; the rich solution pump 109 can stably transport the rich amine solution that has absorbed carbon dioxide in the absorption tower 101 to the lean-rich solution heat exchanger 102, ensuring the continuity and stability of the rich amine solution transportation; the lean-rich solution heat exchanger 102 can preheat the rich amine solution, reducing the heat consumption required for subsequent carbon dioxide desorption in the desorption tower 103, further reducing the operating energy consumption of the carbon capture unit 1, and improving efficiency. The desorption tower 103 improves energy utilization efficiency by desorbing the preheated rich amine liquid, effectively releasing the carbon dioxide absorbed in the liquid, and simultaneously regenerating the lean amine liquid, enabling its recycling and reducing absorbent consumption costs. The reboiler 104, connected to the desorption tower 103, fully utilizes the waste heat from the coal-fired power plant to provide sufficient heat and separation power for the carbon dioxide desorption process in the desorption tower 103, eliminating the need for additional energy consumption and further reducing the operating cost of the carbon capture unit 1. This also achieves resource utilization of waste heat from the coal-fired power plant, meeting the needs of energy conservation and emission reduction. The system comprises the following components: condenser 105 cools the carbon dioxide mixture released from desorption tower 103, preparing it for subsequent gas-liquid separation; regeneration gas separator 106 separates the carbon dioxide mixture cooled by condenser 105, removing liquid impurities and improving the initial purity of the carbon dioxide; purification device 107 further removes impurities from the carbon dioxide, ensuring that the output carbon dioxide meets high purity standards and satisfies the requirements of the directional carbonization reaction in the cogeneration unit 3; compressor 110 and liquefier 111 compress and liquefy the purified high-purity carbon dioxide, facilitating its storage and transportation; and carbon dioxide storage tank group 108 stably stores the liquefied high-purity carbon dioxide, preventing leakage and continuously providing reaction raw materials for the cogeneration unit 3, ensuring the continuous and stable operation of the entire system. Ultimately, this achieves efficient capture, purification, and stable storage of carbon dioxide, providing reliable support for the high-value utilization of carbon dioxide, while further reducing the operating energy consumption and cost of carbon capture unit 1, alleviating the difficulties in financing and the lack of sustainability of carbon capture projects.

[0027] Understandably, the absorption tower 101 is a vertical spray tower. Flue gas from the coal-fired power plant is fed into the bottom of the absorption tower 101 by a blower. A spray device is installed at the top of the absorption tower 101 to spray the lean amine solution. The lean amine solution can be a MEA-MDEA compound solution, which can efficiently absorb carbon dioxide from the flue gas. The rich amine solution output end is located at the bottom of the absorption tower 101 and is connected to the refrigerant input end of the rich and lean amine solution heat exchanger 102 via a rich solution pump 109. The rich solution pump 109 can be a corrosion-resistant centrifugal pump to ensure stable delivery of the rich amine solution. The rich and lean amine solution heat exchanger 102 can be a shell-and-tube heat exchanger. The refrigerant channel is used to transport the rich amine solution, and the heat medium channel is used for heat exchange for subsequent regeneration of the lean amine solution, achieving preheating of the rich amine solution. The desorption tower 103 is a plate tower or a packed tower. The rich amine solution enters from the top of the tower, and the regenerated lean amine solution exits from the bottom of the tower, used to complete the desorption of the rich amine solution and the regeneration of the lean amine solution. The reboiler 104 can be a shell-and-tube heat exchange structure, connected to... Waste heat from the coal-fired power plant, i.e., exhaust steam, is used for heat exchange to heat the lean amine liquid at the bottom of the desorption tower 103, providing heat and separation power for the desorption process. The condenser 105 can be a shell-and-tube condenser, used to cool and remove water from the carbon dioxide mixture discharged from the desorption tower 103. The regeneration gas separator 106 is a gravity gas-liquid separator, used to separate the cooled carbon dioxide mixture into gas and liquid components. The purification device 107 can adopt a three-stage impurity removal structure, with a pre-filtration section, a core adsorption section, and a post-fine filtration section set sequentially, used to accurately remove various impurities from the carbon dioxide. The compressor 110 can be a screw compressor 110, and the liquefier 111 can be a condensing liquefier 111, used to compress and liquefy the purified carbon dioxide. The carbon dioxide storage tank group 108 can be a high-pressure cryogenic storage tank, used to store the liquefied high-purity carbon dioxide, ensuring the supply of raw materials for subsequent carbonization reactions. The working principle of carbon capture unit 1 is as follows: First, the flue gas from the coal-fired power plant is purified by physical processes such as dust removal and demisting, and by chemical processes such as desulfurization and denitrification. It then enters the bottom of the absorption tower 101 through a blower. The spray device at the top of the absorption tower 101 continuously sprays the lean amine liquid. The flue gas comes into countercurrent contact with the lean amine liquid from bottom to top. The lean amine liquid fully absorbs the carbon dioxide in the flue gas. After absorbing the carbon dioxide, the lean amine liquid becomes a rich amine liquid. The rich amine liquid is discharged from the rich amine liquid output end of the absorption tower 101 and is transported to the refrigerant input end of the lean-rich liquid heat exchanger 102 by the rich liquid pump 109. After the lean-rich liquid heat exchanger 102 preheats the rich amine liquid, the preheated rich amine liquid is transported to the rich amine liquid input end of the desorption tower 103 through the refrigerant output end.After preheating, the rich amine solution enters the desorption tower 103 and flows from top to bottom. The reboiler 104 heats the lean amine solution at the bottom of the desorption tower 103 by exchanging heat with the exhaust steam from the coal-fired power plant, raising the temperature of the lean amine solution and causing partial vaporization. This forms a high-temperature gas-liquid mixture that flows back into the desorption tower 103. This process directly generates the core separation power required for desorption, specifically in two layers: first, the gas phase lift, i.e., fluid power. The large amount of steam generated by heating and vaporization flows upward, becoming a continuous upward steam flow within the desorption tower 103, providing upward fluid power for the counter-current contact of the gas and liquid phases within the tower. The foundation of current mass transfer separation lies in two aspects: first, the driving force of mass transfer; and second, the rising high-temperature steam flow and the downward-flowing amine-rich liquid within the tower, creating a temperature and concentration difference. Carbon dioxide in the amine-rich liquid desorbs at high temperature and escapes, merging with the rising steam flow. The steam flow continuously carries the desorbed carbon dioxide to the top of the tower, achieving efficient mass transfer separation between carbon dioxide and the amine liquid. This mass transfer trend, driven by the temperature and concentration difference, is the core driving force for the separation of carbon dioxide from the amine liquid. The carbon dioxide mixture discharged from the top of the desorption tower 103 enters the condenser 105, where it is cooled and dehydrated before being transported to the regeneration gas separator. Gas-liquid separation is performed in separator 106. The separated carbon dioxide gas enters purification unit 107 from the gas phase output end of regeneration gas separator 106. The separated amine liquid is transported back to desorption tower 103 for recycling via reflux pump 116. Purification unit 107 achieves precise removal of impurities through a three-stage impurity removal process. The first step is a pre-filtration section, which removes more than 90% of trace amine liquid droplets and salt particles from the gas through inertial collision and interception adsorption. When amine liquid droplets and salt solid particles pass through wire mesh or fiber packing with the airflow, they adhere to the surface of the packing due to inertial collision and gradually aggregate into liquid. The first step, involving droplets or granular clusters, flows along the surface of the packing material to the liquid collection tank at the bottom of the device. This is a periodic discharge and recovery process, a physical impurity removal method without consumables. The packing material can be regenerated through backflushing, preventing the amine solution from entering subsequent equipment and causing side reactions. The second step is the core adsorption section, filled with composite adsorbent or dilute alkali absorbent. This removes residual trace amounts of acidic gaseous free amine molecules and trace amounts of water through physical and chemical adsorption. The activated carbon, molecular sieve, and silica gel composite adsorbent adsorbs free amine molecules and trace amounts of water vapor through intermolecular forces. The molecular sieve selectively adsorbs water molecules to prevent freezing and blockage. If trace amounts of SO2 or NO remain in the gas... x Acidic gases can be converted into salts through the acid-base reaction of dilute sodium carbonate or sodium bicarbonate absorbent packing layer, thus removing impurities without introducing new impurity gases. The third step is a post-filtration section, which removes adsorbent powder and ultrafine salt particles entrained in the gas through a micron-level precision filter element. At the same time, the flow field of carbon dioxide gas is rectified to ensure that the gas enters the subsequent equipment smoothly. The high-purity carbon dioxide after being processed by the purification device 107 is compressed by the compressor 110 and liquefied by the liquefier 111 before being transported to the carbon dioxide storage tank group 108 for storage, completing the entire carbon capture process and providing qualified reaction raw materials for the carbonization co-production unit 3.

[0028] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 2 As shown, the carbon capture unit 1 also includes a flash compression device 112 and a lean liquid pump 113. The flash compression device 112 is connected to the desorption tower 103. The flash compression device 112 is used to flash the lean amine liquid in the desorption tower 103 and to pressurize and heat the secondary steam generated by flashing and then send it back to the desorption tower 103. The input end of the lean liquid pump 113 is connected to the lean amine liquid output end of the flash compression device 112 and the lean amine liquid output end of the desorption tower 103, respectively. The output end of the lean liquid pump 113 is connected to the heat medium input end of the lean and rich liquid heat exchanger 102. The heat medium output end of the lean and rich liquid heat exchanger 102 is connected to the absorption tower 101 and is used to transport the lean amine liquid to the absorption tower 101 for circulating spraying.

[0029] In this embodiment, the flash compression device 112 is connected to the desorption tower 103, enabling flash treatment of the lean amine solution in the desorption tower 103. The secondary steam generated by flash evaporation is pressurized and heated and then sent back to the desorption tower 103. This fully recovers the residual heat and steam in the lean amine solution, supplementing the heat and separation power required for the desorption process in the desorption tower 103, reducing the consumption of waste heat from the coal-fired power plant by the reboiler 104, further improving energy utilization efficiency, and reducing the operating load of the reboiler 104, thus extending the service life of the equipment. The input end of the lean solution pump 113 is connected to the lean amine solution output end of both the flash compression device 112 and the desorption tower 103, enabling the stable collection and transportation of the lean amine solution treated by the flash compression device 112 and the lean amine solution regenerated at the bottom of the desorption tower 103. This ensures the continuity and stability of the lean amine solution transportation and prevents interruptions in the transportation of the lean amine solution from affecting the entire carbon capture process. The operation of Unit 1: The output end of the lean liquid pump 113 is connected to the heat medium input end of the lean-rich liquid heat exchanger 102, which can transport the collected lean amine liquid to the heat medium channel of the lean-rich liquid heat exchanger 102 to exchange heat with the rich amine liquid in the cold medium channel. This not only preheats the rich amine liquid but also completes the initial cooling of the lean amine liquid, reducing the cooling energy consumption of the lean amine liquid before it enters the absorption tower 101. At the same time, the heat medium output end of the lean-rich liquid heat exchanger 102 is connected to the absorption tower 101. The lean amine liquid after heat exchange can be directly transported to the absorption tower 101 for circulation spraying, realizing the closed-loop recycling of the lean amine liquid. This significantly reduces the consumption cost of the lean amine liquid, improves the continuous operation stability of the carbon capture unit 1, further alleviates the financing difficulties and poor sustainability of the carbon capture project, and works in conjunction with the original components to achieve more efficient and low-consumption carbon dioxide capture, providing a stable high-purity carbon dioxide feedstock for the subsequent carbonization cogeneration unit 3.

[0030] It is understood that the flash compression unit 112 consists of a flash tank (i.e., a flash separation unit) and an MVR compressor (i.e., a vapor compression unit). The flash tank can be a vertical atmospheric pressure flash tank used for flash separation of the lean amine solution in the desorption tower 103. The feed end of the flash tank is connected to the desorption tower 103, and the discharge end is connected to the MVR compressor and the lean liquid pump 113, respectively. The MVR compressor can be a mechanical vapor recompression compressor used to pressurize and heat the low-pressure steam generated by flashing in the flash tank, increasing the steam's heat and pressure. Its output end is connected to the desorption tower 103, allowing the pressurized and heated steam to be returned to the desorption tower 103. The lean liquid pump 113 can be a corrosion-resistant centrifugal pump, compatible with the flash compression unit 112, the desorption tower 103, and the lean and rich liquid heat exchanger 102. Its input end is... The pump 113 is not connected to the lean amine liquid output end of the flash tank in the flash compression unit 112 or the lean amine liquid output end of the desorption tower 103. It can be used to collect the lean amine liquid from the two places for joint transportation, or to achieve selective transportation by setting a valve. That is, according to the system operation requirements, it can select to transport the lean amine liquid output from the flash tank alone, the lean amine liquid output from the desorption tower 103 alone, or transport the lean amine liquid from both places at the same time. The output end of the lean liquid pump 113 is connected to the heat medium input end of the lean and rich liquid heat exchanger 102 to ensure that the lean amine liquid is stably transported to the lean and rich liquid heat exchanger 102. The lean and rich liquid heat exchanger 102 can be a shell and tube heat exchanger. Its heat medium input end receives the lean amine liquid transported by the lean liquid pump 113, and its heat medium output end is connected to the absorption tower 101 to realize the circulation transportation of lean amine liquid to the absorption tower 101, and maintains coordinated compatibility with the original components.It should be noted that the cooperative working principle of the flash compression device 112 and the lean liquid pump 113 with the original components of the carbon capture unit 1 is as follows: After the desorption process of the rich amine liquid is completed in the desorption tower 103 and the lean amine liquid is regenerated, a portion of the lean amine liquid remains at the bottom of the desorption tower 103, while the other portion is transported to the flash tank of the flash compression device 112. The flash tank performs flash evaporation on the input lean amine liquid, releasing the residual heat in the lean amine liquid and causing some of the lean amine liquid to vaporize and generate low-pressure steam. The remaining lean amine liquid after flash evaporation is discharged from the lean amine liquid output end of the flash tank, and optionally, it flows into the input end of the lean liquid pump 113 along with the lean amine liquid at the bottom of the desorption tower 103. At the same time, the low-pressure steam generated by flash evaporation in the flash tank enters the MVR compressor. The MVR compressor pressurizes and heats the low-pressure steam, converting it into high-temperature and high-pressure steam, which is then sent back to the desorption tower 103. Inside, the heat and separation power required for the carbon dioxide desorption process in the desorption tower 103 are supplemented, reducing the consumption of waste heat from the coal-fired power plant by the reboiler 104; the lean liquid pump 113 stably delivers the collected lean amine liquid to the heat medium input end of the lean-rich liquid heat exchanger 102. The lean amine liquid flows in the heat medium channel of the lean-rich liquid heat exchanger 102 and exchanges heat with the rich amine liquid delivered from the absorption tower 101 in the cold medium channel. This not only achieves the preheating of the rich amine liquid, which helps to save energy in the subsequent desorption process, but also completes the initial cooling of the lean amine liquid itself; the lean amine liquid after heat exchange in the lean-rich liquid heat exchanger 102 is delivered to the absorption tower 101 through the heat medium output end of the lean-rich liquid heat exchanger 102 and recycled as lean amine liquid for spraying, realizing the closed-loop circulation of the lean amine liquid, further improving the energy utilization efficiency and continuous operation stability of the carbon capture unit 1, and working together with the original components to complete the efficient capture, purification and storage of carbon dioxide.

[0031] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 2 As shown, the carbon capture unit 1 also includes a lean liquid cooler 114. The lean liquid cooler 114 is connected between the heat medium output end of the lean-rich liquid heat exchanger 102 and the lean amine liquid input end of the absorption tower 101. It is used to further cool the lean amine liquid after heat exchange and cooling by the lean-rich liquid heat exchanger 102, so that the temperature of the lean amine liquid is adapted to the carbon dioxide absorption conditions of the absorption tower 101 and then it is sent to the absorption tower 101 for spraying.

[0032] In this embodiment, by setting up a lean liquid cooler 114, the lean amine liquid after heat exchange and cooling by the lean-rich liquid heat exchanger 102 can be further cooled, effectively reducing the temperature of the lean amine liquid and making its temperature precisely match the carbon dioxide absorption conditions of the absorption tower 101. This avoids a decrease in the absorption efficiency of the lean amine liquid for carbon dioxide in the absorption tower 101 due to excessively high temperature, ensuring that the lean amine liquid can efficiently absorb carbon dioxide from the flue gas of the coal-fired power plant and improve the capture efficiency of the entire carbon capture unit 1. At the same time, the lean amine liquid cooled by the lean liquid cooler 114 is transported to the absorption tower 101 for spraying, which can reduce the amine liquid volatilization loss caused by the high temperature of the lean amine liquid in the absorption tower 101, reduce the consumption cost of the lean amine liquid, and extend the service life of the spraying device in the absorption tower 101. In addition, The lean liquor cooler 114 works in synergy with the lean-rich liquor heat exchanger 102. The lean amine liquor is first initially cooled by the lean-rich liquor heat exchanger 102, and then precisely cooled by the lean liquor cooler 114. This eliminates the need to rely solely on the lean liquor cooler 114 for cooling, effectively reducing the operating load and energy consumption of the lean liquor cooler 114. In conjunction with components such as the lean liquor pump 113 and the flash compression device 112, it further improves the closed-loop circulation system of the lean amine liquor, enhances the continuous operation stability of the carbon capture unit 1, and ensures that the carbon capture unit 1 can continuously and efficiently capture high-purity carbon dioxide, providing a stable reaction feedstock for the subsequent carbonization co-production unit 3. At the same time, it further alleviates the financing difficulties and poor sustainability of the carbon capture project, helping the entire system achieve a synergistic improvement in environmental and economic benefits.

[0033] Understandably, the lean liquid cooler 114 can be a shell-and-tube cooler, with a structure compatible with the lean-rich liquid heat exchanger 102, facilitating system integration and installation. Its function is to further cool the lean amine liquid after its initial cooling by the lean-rich liquid heat exchanger 102, ensuring that the temperature of the lean amine liquid meets the carbon dioxide absorption conditions of the absorption tower 101. The heat medium channel of the lean liquid cooler 114 connects the heat medium output end of the lean-rich liquid heat exchanger 102 to the lean amine liquid input end of the absorption tower 101, forming a continuous transport channel for the lean amine liquid. The heat medium originates from the heat medium output end of the lean-rich liquid heat exchanger 102. The lean amine solution, which is the lean amine solution that has been initially cooled after exchanging heat with the rich amine solution in the lean-rich amine solution heat exchanger 102, enters the heat medium channel of the lean amine solution cooler 114. After cooling, it is discharged from the heat medium output end of the lean amine solution cooler 114 and directly transported to the lean amine solution input end of the absorption tower 101 for spraying within the absorption tower 101. The refrigerant input end of the lean amine solution cooler 114 is connected to the power plant's circulating cooling water system. The circulating cooling water cools the lean amine solution in the heat medium channel of the lean amine solution cooler 114 to ensure that the lean amine solution reaches the spraying temperature required by the absorption tower 101.

[0034] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 2As shown, an interstage cooler 115 is provided in the middle of the absorption tower 101. The interstage cooler 115 is used to cool the gas-liquid contact system in the absorption tower 101 to increase the absorption driving force and carbon dioxide load of the absorption tower 101 for carbon dioxide in the flue gas of coal-fired power plants.

[0035] In this embodiment, the interstage cooler 115 can cool the gas-liquid contact system within the absorption tower 101, effectively reducing the temperature of the gas-liquid contact area within the absorption tower 101. This, in turn, increases the absorption driving force and carbon dioxide load of the absorption tower 101 on carbon dioxide in the flue gas of the coal-fired power plant, preventing the decrease in carbon dioxide absorption driving force and insufficient carbon dioxide load of the lean amine liquid due to increased temperature in the gas-liquid contact system within the absorption tower 101. This ensures that the lean amine liquid can more fully absorb carbon dioxide from the flue gas, further improving the carbon dioxide absorption efficiency and absorption capacity of the absorption tower 101. Simultaneously, the cooling effect of the interstage cooler 115 on the gas-liquid contact system reduces the evaporation loss of the lean amine liquid within the absorption tower 101, lowering the consumption cost of the lean amine liquid, and alleviating the problems caused by excessively high temperatures in the spray device within the absorption tower 101. This reduces energy consumption and extends the service life of the spraying device. Furthermore, the interstage cooler 115 works in conjunction with the lean liquid cooler 114 and the lean-rich liquid heat exchanger 102 to form a staged cooling system. The lean liquid cooler 114 ensures the temperature of the lean amine solution entering the absorption tower 101 is suitable for the absorption conditions, while the interstage cooler 115 maintains a suitable temperature for the gas-liquid contact process within the absorption tower 101. This further improves the process conditions for the lean amine solution to absorb carbon dioxide, enhances the continuous operational stability of the carbon capture unit 1, and ensures that the carbon capture unit 1 can continuously and efficiently capture high-purity carbon dioxide, providing a stable reaction feedstock for the subsequent cogeneration unit 3. Simultaneously, it further reduces the operating energy consumption and cost of the carbon capture unit 1, alleviating the difficulties in financing and the poor sustainability of carbon capture projects, and helping the entire system achieve a synergistic improvement in both environmental and economic benefits.

[0036] Understandably, absorption tower 101 can be a vertical spray tower, with packing or trays inside. The packing material can be corrosion-resistant wire mesh packing or ceramic packing with a large specific surface area, and the trays can be sieve trays or floating valve trays to provide sufficient space for gas-liquid two-phase contact. Absorption tower 101 has a flue gas inlet at the bottom to receive the flue gas from the coal-fired power plant after dust removal, demisting, desulfurization, and denitrification pretreatment. A spray device is installed at the top of the tower to spray lean amine solution. The lean amine solution is a MEA-MDEA compound solution, which can efficiently react with carbon dioxide in the flue gas in an acid-base reaction. Absorption tower 101 has a rich amine solution outlet at the bottom to discharge the solution after carbon dioxide absorption. The amine-rich liquid is used, and a flue gas outlet is set at the top of the tower to discharge the flue gas after carbon dioxide absorption. The interstage cooler 115 can be a shell-and-tube cooler, which is installed in the gas-liquid contact core area in the middle of the absorption tower 101 and integrated with the absorption tower 101. Its cooling medium can be the circulating water of the coal-fired power plant. The cooling medium channel is connected to the power plant's circulating cooling water system to realize heat transfer and recovery. The cooling object of the interstage cooler 115 is the gas-liquid contact system in the absorption tower 101, rather than the flue gas or lean amine liquid alone, so as to accurately and uniformly cool the system and maintain the optimal operating conditions for amine method carbon dioxide absorption.It should be noted that the synergistic working principle of the absorber 101 and the interstage cooler 115 is as follows: The core process within the absorber 101 is the countercurrent contact between flue gas and lean amine liquid. The pretreated coal-fired flue gas flows upwards from the bottom of the absorber 101, while the top spray device continuously sprays the lean amine liquid, which flows downwards. The two components fully contact and mix at the packing or trays within the tower, forming a reaction system where the gas and liquid phases are in full contact. This system is the object cooled by the interstage cooler 115 and is also the core space for the acid-base reaction between the MEA-MDEA compound liquid and carbon dioxide. Due to the organic amine... The absorption reaction between carbon dioxide and flue gas is a strongly exothermic reaction, continuously releasing heat during the process. If not cooled in time, the temperature of the gas-liquid contact system inside the absorption tower 101 will continue to rise, thereby reducing the driving force and load of carbon dioxide absorption. Therefore, the interstage cooler 115 located in the middle of the absorption tower 101 begins to function. Its cooling medium, circulating water, flows in the cooling medium channel, efficiently exchanging heat with the gas-liquid contact system inside the absorption tower 101, directly cooling the entire gas-liquid mixed contact system. This stabilizes the system temperature within the amine absorption range. The optimal operating temperature for carbon dioxide absorption is 35 to 45°C. This temperature also ensures uniform cooling in the central region of the tower, preventing localized overheating caused by exothermic reactions during gas-liquid contact and thus protecting the overall absorption efficiency. The interstage cooler 115 effectively prevents the reaction equilibrium from shifting towards the reverse reaction direction, preventing the combined carbon dioxide from escaping from the amine solution again. Simultaneously, it increases the amount of carbon dioxide absorbed per unit volume of amine solution, improving amine utilization, reducing amine circulation, and lowering system energy consumption. Finally, the lean amine solution, having completed carbon dioxide absorption, becomes a rich amine solution, which is then removed from the absorption tower 101. The rich amine solution is discharged from the lower end and transported to the lean and rich solution heat exchanger 102 by the rich solution pump 109 to complete the subsequent desorption process. The flue gas that has completed the absorption process is discharged from the flue gas output end at the top of the absorption tower 101. The circulating water that has absorbed heat after heat exchange in the interstage cooler 115 is returned to the circulating cooling water system of the coal-fired power plant. After cooling treatment, it is recycled again to achieve reasonable heat recovery. The interstage cooler 115 works in conjunction with the absorption tower 101 and other components of the carbon capture unit 1 to further improve the carbon dioxide absorption efficiency and the economic efficiency of system operation, ensuring the stable and efficient operation of the carbon capture unit 1.

[0037] In some possible embodiments disclosed in this application, the bipolar membrane 203 electrodialysis unit 2 includes a bipolar membrane 203 electrodialysis stack, a brine tank, a pure water tank, and an electrode water storage tank; the brine tank stores pretreated industrial sodium sulfate solution, and is connected to the salt chamber of the bipolar membrane 203 electrodialysis stack for supplying 10% sodium sulfate solution to the salt chamber; the pure water tank is connected to the acid and alkali chambers of the bipolar membrane 203 electrodialysis stack for supplying pure water to the acid and alkali chambers; the electrode water storage tank is connected to the electrode chamber of the bipolar membrane 203 electrodialysis stack for supplying 3% sodium sulfate dilute solution to the electrode chamber; the bipolar membrane 203 electrodialysis stack is used to electrolyze the sodium sulfate solution into sodium hydroxide solution and sulfuric acid solution under green electricity drive.

[0038] In this embodiment, the brine tank stably stores the pretreated industrial sodium sulfate solution and precisely delivers 10% sodium sulfate solution by mass to the salt chamber of the bipolar membrane 203 electrodialysis stack, ensuring the stability of the raw material supply for the electrolysis reaction and laying the foundation for the continuous and efficient operation of the electrolysis process. The pure water tank is connected to the acid and alkali chambers of the bipolar membrane 203 electrodialysis stack, delivering pure water to them to provide a suitable reaction environment for the generation of sodium hydroxide and sulfuric acid solutions, ensuring the purity of the electrolytic products and preventing impurities from affecting product quality. The electrode water storage tank is connected to the electrode chambers of the bipolar membrane 203 electrodialysis stack, delivering 3% sodium sulfate dilute solution by mass, which stabilizes the reaction environment in the electrode chambers, helps maintain the electrolysis efficiency of the bipolar membrane 203 electrodialysis stack, extends the service life of the bipolar membrane 203 electrodialysis stack, and reduces equipment wear. The bipolar membrane 203 electrodialysis stack is driven by green electricity. The sodium sulfate solution transported from the brine tank is efficiently electrolyzed into sodium hydroxide solution and sulfuric acid solution without the need for harsh operating conditions of high temperature and high pressure. Compared with traditional multi-effect concentration technology, energy consumption is significantly reduced. The entire treatment process is closed-loop and controllable, with no secondary pollution. It not only realizes the resource conversion of industrial by-product sodium sulfate, solving the problem of limited market sales and internal recycling, but also produces sodium hydroxide solution and sulfuric acid solution with stable market demand and high added value, opening up new profit growth points for enterprises. At the same time, the sodium hydroxide solution generated by the bipolar membrane 203 electrodialysis unit 2 directly provides reaction raw materials for the carbonization co-production unit 3, and works in synergy with the carbon dioxide captured by the carbon capture unit 1 to complete the directional carbonization reaction, which helps to prepare sodium bicarbonate product. This realizes the synergistic linkage of all units in the entire system, further improving the overall economic and environmental benefits of the system, and promoting the reduction, resource utilization and harmless treatment of industrial waste.

[0039] In the above embodiments, see Figure 3As shown, the bipolar membrane 203 electrodialysis stack has a three-compartment configuration, including an anode 201, a cathode 202, a bipolar membrane 203, an anion exchange membrane 204, and a cation exchange membrane 205. The bipolar membrane 203, anion exchange membrane 204, and cation exchange membrane 205 are arranged sequentially to form independent acid chambers, alkali chambers, salt chambers, and polar chambers. The bipolar membrane 203 dissociates water to generate hydrogen ions and hydroxide ions. Sodium ions from the sodium sulfate solution dissociated in the salt chamber pass through the cation exchange membrane 205 into the alkali chamber and combine with hydroxide ions to generate sodium hydroxide. Sulfate ions pass through the anion exchange membrane 204 into the acid chamber and combine with hydrogen ions to generate sulfuric acid.

[0040] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 4 As shown, the carbonization co-production unit 3 includes a carbonization reactor 301, a cooling crystallization tank 302, a separation and drying device 303, and an alkali heat exchanger 304. The alkali heat exchanger 304 is connected to the alkali chamber of the bipolar membrane 203 electrodialysis stack and is used to preheat the sodium hydroxide solution output from the alkali chamber. The carbonization reactor 301 is connected to the alkali heat exchanger 304 and the carbon dioxide storage tank group 108, respectively, and is used to cause the preheated sodium hydroxide solution to undergo a directional carbonization reaction with carbon dioxide to generate a sodium bicarbonate suspension. The cooling crystallization tank 302 is connected to the carbonization reactor 301 and is used to cool and crystallize the sodium bicarbonate suspension to precipitate sodium bicarbonate in crystal form. The separation and drying device 303 is connected to the cooling crystallization tank 302 and is used to perform solid-liquid separation and drying of the sodium bicarbonate crystals to obtain sodium bicarbonate as a finished product.

[0041] In this embodiment, the alkali heat exchanger 304 is connected to the alkali chamber of the bipolar membrane 203 electrodialysis stack, which can preheat the sodium hydroxide solution output from the alkali chamber, providing suitable temperature conditions for the subsequent carbonization reaction, accelerating the carbonization reaction rate, improving reaction efficiency, and reducing heat consumption during the carbonization reaction process, thereby reducing system operating energy consumption. The carbonization reactor 301 is connected to the alkali heat exchanger 304 and the carbon dioxide storage tank group 108, respectively, and can receive the preheated sodium hydroxide solution and the high-purity carbon dioxide stored in the carbon capture unit 1, so that the two undergo a directional carbonization reaction to generate sodium bicarbonate suspension, realizing the efficient coupling and utilization of carbon dioxide and sodium hydroxide solution. This not only further promotes the high-value resource conversion of carbon dioxide, but also converts the product of the bipolar membrane 203 electrodialysis unit 2 into sodium bicarbonate, which has a higher market value, thus broadening the added value of the product. The cooling crystallization tank 302 is connected to the carbonization reactor 301, which can cool the sodium bicarbonate suspension. Crystallization treatment precipitates sodium bicarbonate in crystalline form, laying the foundation for the subsequent preparation of sodium bicarbonate. Precise temperature control ensures effective crystallization, improving the purity and yield of the sodium bicarbonate crystals. The separation and drying equipment 303, connected to the cooling crystallization tank 302, performs solid-liquid separation and drying of the precipitated sodium bicarbonate crystals, effectively removing moisture and impurities to produce qualified sodium bicarbonate, ensuring product quality meets market requirements. The entire carbonization and co-production unit 3, through the synergistic effect of its components, achieves a closed-loop process from raw material pretreatment and directional reaction to finished product preparation. It efficiently links the carbon capture unit 1 and the bipolar membrane 203 electrodialysis unit 2, solving the problem of insufficient high-value utilization of captured carbon dioxide and further upgrading the product of industrial by-product sodium sulfate resource conversion, improving the overall economic benefits of the system. Simultaneously, it contributes to carbon emission reduction in the industrial sector and promotes the coordinated reduction, resource utilization, and harmless treatment of industrial waste.

[0042] In the above embodiments, see Figure 4 As shown, a stirrer 305 is installed inside the carbonization reactor 301, and the stirring speed of the stirrer 305 is 40 to 60 revolutions per minute; a thermostat 306 is installed on the carbonization reactor 301, and the thermostat 306 is used to control the reaction temperature inside the carbonization reactor 301 at about 30 degrees Celsius.

[0043] Furthermore, the carbonization reactor 301 is used to introduce carbon dioxide into the sodium hydroxide solution in stages, and to stop introducing carbon dioxide when the pH value of the solution reaches 8.0 to 8.5. After stirring and aging, a sodium bicarbonate suspension is generated. The cooling crystallization tank 302 is used to control the temperature of the sodium bicarbonate suspension at 10 to 15 degrees Celsius, so that sodium bicarbonate precipitates in crystal form. A suspension pump 307 is provided between the cooling crystallization tank 302 and the carbonization reactor 301 for transporting the sodium bicarbonate suspension.

[0044] Understandably, the carbonization reactor 301 uses a staged method of introducing carbon dioxide into the sodium hydroxide solution, stopping the carbon dioxide flow when the solution's pH value reaches a specific range. After stirring and aging, a sodium bicarbonate suspension is generated. This method precisely controls the carbonization reaction process, avoiding problems such as incomplete reaction and decreased product purity due to insufficient carbon dioxide. It ensures that the sodium hydroxide solution and carbon dioxide react fully to generate sodium bicarbonate, while reducing raw material waste, improving reaction conversion rate, and guaranteeing the purity of subsequent sodium bicarbonate crystals. The cooling crystallization tank 302 controls the temperature of the sodium bicarbonate suspension within a specific range, providing suitable temperature conditions for the precipitation of sodium bicarbonate crystals. This promotes uniform and complete precipitation of sodium bicarbonate crystals, avoiding problems such as insufficient crystal precipitation due to excessively high temperatures and crystal agglomeration due to excessively low temperatures. This further improves the yield and purity of sodium bicarbonate crystals, laying the foundation for subsequent separation and drying to prepare sodium bicarbonate. A solid foundation is laid; the suspension pump 307 installed between the cooling crystallization tank 302 and the carbonization reactor 301 can stably and efficiently transport the sodium bicarbonate suspension generated in the carbonization reactor 301 to the cooling crystallization tank 302, ensuring the continuity and stability of the suspension transport, avoiding interruptions in the suspension transport that would affect the entire process flow of the carbonization co-production unit 3, while reducing the loss of the suspension during transport and ensuring smooth process connection; the synergistic effect of the above-mentioned related settings further improves the process system of the carbonization co-production unit 3, ensuring precise and controllable directional carbonization reaction and stable cooling crystallization effect, effectively improving the quality and yield of sodium bicarbonate product, reducing raw material consumption and system operating energy consumption, and working in conjunction with components such as the carbonization reactor 301, cooling crystallization tank 302, carbon capture unit 1, and bipolar membrane 203 electrodialysis unit 2, further improving the overall economic benefits and operational stability of the entire system.

[0045] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0046] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A carbon capture coupled with electrodialysis for alkali production and sodium bicarbonate co-production system in a coal-fired power plant, characterized in that, It includes a carbon capture unit, a bipolar membrane electrodialysis unit, and a carbonization co-production unit; The carbon capture unit is used to capture carbon dioxide from the flue gas of a coal-fired power plant and to use the waste heat of the coal-fired power plant as a heat source for the carbon dioxide desorption process. The bipolar membrane electrodialysis unit is driven by green electricity and is used to electrolyze industrial sodium sulfate solution to generate sodium hydroxide solution and sulfuric acid solution. The carbonization co-production unit is connected to the carbon capture unit and the bipolar membrane electrodialysis unit, and is used to carry out a directional carbonization reaction between the carbon dioxide and the sodium hydroxide solution to obtain sodium bicarbonate product.

2. The coal-fired power plant carbon capture coupled with electrodialysis for alkali production and sodium bicarbonate co-production system according to claim 1, characterized in that, The carbon capture unit includes an absorption tower, a lean and rich liquid heat exchanger, a desorption tower, a reboiler, a condenser, a regenerated gas separator, a purification device, and a carbon dioxide storage tank group. The absorption tower is used to spray lean amine solution to absorb carbon dioxide in the flue gas of coal-fired power plants. The rich amine solution output end of the absorption tower is connected to the refrigerant input end of the lean-rich solution heat exchanger via a rich solution pump. The lean-rich solution heat exchanger is used to preheat the rich amine solution and transport the preheated rich amine solution to the rich amine solution input end of the desorption tower through its refrigerant output end. The desorption tower is used to desorb the preheated rich amine solution to release carbon dioxide and regenerate the lean amine solution. The reboiler is connected to the desorption tower, and the reboiler is used to provide heat and separation power for the carbon dioxide desorption process of the desorption tower by utilizing the waste heat of the coal-fired power plant. The carbon dioxide output end of the desorption tower is connected to the input end of the condenser, and the output end of the condenser is connected to the regeneration gas separator. The regeneration gas separator is used to perform gas-liquid separation on the carbon dioxide mixture. The gas phase output end of the regeneration gas separator is connected to the purification device, which is used to remove impurities from the carbon dioxide. The output end of the purification device is connected to the carbon dioxide storage tank group via a compressor and a liquefier, which is used to store carbon dioxide.

3. The coal-fired power plant carbon capture coupled with electrodialysis for alkali production and sodium bicarbonate co-production system according to claim 2, characterized in that, The carbon capture unit also includes a flash compression device and a lean liquid pump. The flash compression device is connected to the desorption tower and is used to flash the lean amine solution in the desorption tower, and to pressurize and heat the secondary steam generated by flash evaporation before sending it back to the desorption tower. The input end of the lean liquid pump is connected to the lean amine solution output end of the flash compression device and the lean amine solution output end of the desorption tower, respectively. The output end of the lean liquid pump is connected to the heat medium input end of the lean-rich liquid heat exchanger, and the heat medium output end of the lean-rich liquid heat exchanger is connected to the absorption tower for conveying lean amine solution to the absorption tower for circulating spraying.

4. The coal-fired power plant carbon capture coupled with electrodialysis for alkali production and sodium bicarbonate co-production system according to claim 3, characterized in that, The carbon capture unit also includes a lean liquid cooler, which is connected between the heat medium output end of the lean-rich liquid heat exchanger and the lean amine liquid input end of the absorption tower. It is used to further cool the lean amine liquid after heat exchange and cooling by the lean-rich liquid heat exchanger, so that the temperature of the lean amine liquid is adapted to the carbon dioxide absorption conditions of the absorption tower before being transported to the absorption tower for spraying.

5. The coal-fired power plant carbon capture coupled with electrodialysis for alkali production and sodium bicarbonate co-production system according to claim 2, characterized in that, An interstage cooler is installed in the middle of the absorption tower. The interstage cooler is used to cool the gas-liquid contact system inside the absorption tower, so as to improve the absorption driving force and carbon dioxide load of the absorption tower for carbon dioxide in the flue gas of coal-fired power plants.

6. The carbon capture coupled with electrodialysis for alkali production and sodium bicarbonate co-production system in a coal-fired power plant according to claim 2, characterized in that, The bipolar membrane electrodialysis unit includes a bipolar membrane electrodialysis stack, a brine tank, a pure water tank, and an electrode water storage tank. The brine tank stores pretreated industrial sodium sulfate solution and is connected to the salt chamber of the bipolar membrane electrodialysis stack, used to supply 10% sodium sulfate solution to the salt chamber. The pure water tank is connected to the acid and alkali chambers of the bipolar membrane electrodialysis stack, used to supply pure water to the acid and alkali chambers. The electrode water storage tank is connected to the electrode chamber of the bipolar membrane electrodialysis stack, used to supply 3% sodium sulfate dilute solution to the electrode chamber. The bipolar membrane electrodialysis stack is used to electrolyze the sodium sulfate solution into sodium hydroxide solution and sulfuric acid solution under green electricity drive.

7. The coal-fired power plant carbon capture coupled with electrodialysis for alkali production and sodium bicarbonate co-production system according to claim 6, characterized in that, The bipolar membrane electrodialysis stack has a three-compartment configuration, including an anode, a cathode, a bipolar membrane, an anion exchange membrane, and a cation exchange membrane. The bipolar membrane, the anion exchange membrane, and the cation exchange membrane are arranged sequentially to form an independent acid chamber, an alkali chamber, a salt chamber, and an electrode chamber. The bipolar membrane dissociates water to generate hydrogen ions and hydroxide ions. Sodium ions from the sodium sulfate solution dissociated in the salt chamber pass through the cation exchange membrane into the alkali chamber and combine with hydroxide ions to generate sodium hydroxide. Sulfate ions pass through the anion exchange membrane into the acid chamber and combine with hydrogen ions to generate sulfuric acid.

8. The carbon capture coupled with electrodialysis for alkali production and sodium bicarbonate co-production system in a coal-fired power plant according to claim 6, characterized in that, The carbonization co-production unit includes a carbonization reactor, a cooling crystallization tank, a separation and drying device, and an alkali heat exchanger. The alkali heat exchanger is connected to the alkali chamber of the bipolar membrane electrodialysis stack and is used to preheat the sodium hydroxide solution output from the alkali chamber. The carbonization reactor is connected to the alkali heat exchanger and the carbon dioxide storage tank group, respectively, and is used to cause the preheated sodium hydroxide solution to undergo a directional carbonization reaction with carbon dioxide to generate a sodium bicarbonate suspension. The cooling crystallization tank is connected to the carbonization reactor and is used to cool and crystallize the sodium bicarbonate suspension, so that sodium bicarbonate precipitates in crystal form. The separation and drying device is connected to the cooling crystallization tank and is used to perform solid-liquid separation and drying of the sodium bicarbonate crystals to obtain sodium bicarbonate as the finished product.

9. The carbon capture coupled with electrodialysis for alkali production and sodium bicarbonate co-production system in a coal-fired power plant according to claim 8, characterized in that, The carbonization reactor is equipped with a stirrer with a stirring speed of 40 to 60 revolutions per minute; the carbonization reactor is also equipped with a thermostat to control the reaction temperature inside the carbonization reactor at around 30 degrees Celsius.

10. The coal-fired power plant carbon capture coupled with electrodialysis for alkali production and sodium bicarbonate co-production system according to claim 8, characterized in that, The carbonization reactor is used to introduce carbon dioxide into the sodium hydroxide solution in stages, and to stop introducing carbon dioxide when the pH value of the solution reaches 8.0 to 8.

5. After stirring and aging, a sodium bicarbonate suspension is generated. The cooling crystallization tank is used to control the temperature of the sodium bicarbonate suspension at 10 to 15 degrees Celsius, so that sodium bicarbonate precipitates in crystal form. A suspension pump is provided between the cooling crystallization tank and the carbonization reactor to transport the sodium bicarbonate suspension.

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