An electrically driven membrane device for converting mixed salts into acid-base ammonium salts

Abstract

The application belongs to the technical field of industrial waste salt resource utilization and waste gas treatment, and specifically discloses an electrically driven membrane device for converting mixed salt into acid, alkali and ammonium salt. The device comprises: a selective separation unit for separating sodium chloride and sodium sulfate mixed salt; a gas-liquid mixed conversion unit for converting mixed gas containing ammonia and carbon dioxide into ammonium carbonate solution; a double electrode replacement unit for reacting sodium chloride with ammonium carbonate to generate sodium carbonate and ammonium chloride; and a bipolar membrane electrodialysis unit for converting sodium sulfate and ammonium chloride into ammonium sulfate and corresponding acid and alkali products. The application integrates a multi-stage electrically driven membrane process, realizes the synergistic high-value conversion of waste salt and waste gas, and has the advantages of high product purity, low energy consumption, environmental friendliness and the like.

Description

Technical Field

[0001] This invention belongs to the field of industrial waste salt resource utilization and waste gas treatment technology, and specifically discloses an electrically driven membrane device for converting mixed salts into acid-base ammonium salts. Background Technology

[0002] With the continued implementation of zero-discharge policies for wastewater from industries such as coal chemical, petrochemical, and coking, the evaporation and crystallization process of high-salt wastewater generates a large amount of mixed sodium chloride and sodium sulfate waste salt. Due to its complex composition and difficulty in separation, conventional landfilling or stockpiling of this mixed salt not only consumes land resources but also poses environmental risks. Converting it into economically valuable chemicals is an urgent need for the resource utilization of waste salt.

[0003] On the other hand, the tail gases from processes such as coking and ammonia synthesis typically contain ammonia and carbon dioxide. Traditional absorption processes often employ bubble columns or packed columns, which suffer from low gas-liquid mass transfer efficiency and high gas escape rates. Especially in the process of absorbing carbon dioxide with ammonia to prepare ammonium carbonate, the reaction between ammonia and carbon dioxide easily produces ammonium bicarbonate crystals with low solubility, causing blockages in pipelines and equipment, severely affecting the continuous operational stability of the unit.

[0004] In existing technologies, the separation of mixed salts mostly employs stepwise crystallization or chemical precipitation methods, but these methods suffer from drawbacks such as high reagent consumption, limited separation purity, and lengthy processes. Furthermore, the synergistic resource recovery pathway between waste gas absorption products and waste salts remains unclear, making it difficult to achieve high-value conversion of the two wastes within the same system. While some processes attempt to utilize electrodialysis to treat single salt solutions, existing technologies still lack efficient, compact, and engineerable solutions for the precise separation of monovalent and divalent anions in multi-component mixed salt systems, as well as for the integrated process of further electrochemically converting waste gas absorption products and the separated salt solution into acids, bases, and ammonium salts.

[0005] Therefore, developing a device that can efficiently separate sodium chloride / sodium sulfate mixed salts and co-convert them with ammonia / carbon dioxide-containing waste gas to simultaneously produce sodium carbonate, ammonium chloride, ammonium sulfate, and acid-base products is of great practical significance for improving the resource utilization rate of industrial waste salts and waste gases and reducing overall treatment costs. Summary of the Invention

[0006] The present invention aims to provide an electrically driven membrane integrated device that synergistically converts a mixture of sodium chloride and sodium sulfate with ammonia-containing carbon dioxide waste gas into sodium carbonate, ammonium chloride, ammonium sulfate and acid-base products, so as to improve the resource utilization rate of industrial waste salt and waste gas and reduce the overall treatment cost.

[0007] An electrically driven membrane device for converting mixed salts into acid-base ammonium salts, comprising: The selective separation unit is used to selectively separate a mixed salt solution of sodium chloride and sodium sulfate to obtain sodium chloride solution and sodium sulfate solution respectively; The gas-liquid mixing and conversion unit is used to mix a mixture of ammonia and carbon dioxide with water and break it up to generate an ammonium carbonate solution. The dual electro-displacement unit, connected to the selective separation unit and the gas-liquid mixing and conversion unit, is used to receive sodium chloride solution and ammonium carbonate solution, and under the action of DC electric field, it undergoes a dual electro-displacement reaction through the selective permeability of the ion exchange membrane to generate sodium carbonate solution and ammonium chloride solution. The bipolar membrane electrodialysis unit, connected to the selective separation unit and the dual electro-displacement unit, receives sodium sulfate and ammonium chloride solutions and generates ammonium sulfate and its corresponding acid and base products. The selective separation unit efficiently separates the mixed salt solutions of sodium chloride and sodium sulfate, obtaining high-purity sodium chloride and sodium sulfate solutions respectively, achieving precise separation of monovalent and divalent anions in the mixed salt. The gas-liquid mixing and conversion unit converts industrial waste gas containing ammonia and carbon dioxide into ammonium carbonate solution, effectively capturing the ammonia and carbon components in the waste gas and inhibiting the crystallization of ammonium bicarbonate. The dual electro-displacement unit uses sodium chloride and ammonium carbonate solutions as raw materials, simultaneously generating sodium carbonate and ammonium chloride solutions under a DC electric field drive. The reaction process requires no additional chemical reagents and produces few byproducts. The bipolar membrane electrodialysis unit further converts the sodium sulfate and ammonium chloride solutions into ammonium sulfate and its corresponding acid and base. The ammonium sulfate can be used as a chlorine-free nitrogen fertilizer for chlorine-sensitive crops. This device integrates mixed salt separation, waste gas absorption, metathesis reaction, and bipolar membrane water dissociation processes into a single system. The material circulation between each unit is closely linked, significantly improving the resource utilization rate of industrial waste salt and waste gas, reducing overall energy consumption and operating costs, and achieving both environmental and economic benefits. It should be noted that "high purity" in this invention refers to a substance purity of 95% or higher.

[0008] Optionally, the selective separation unit is a selective electrodialysis device, which includes: The first power source is electrically connected to the first cathode plate and the first anode plate; The first membrane stack consists of several (4 to 30) adjacent separation membrane pair units. Each separation membrane pair unit includes a first cation exchange membrane (CEM), a first monovalent anion exchange membrane (ACS), a second CEM, and a second ACS, which are stacked sequentially. A first electrode chamber is provided between the first anode plate, the first cathode plate and the first membrane stack; Freshwater chambers are formed between the first CEM and the first ACS, and between the second CEM and the second ACS; A concentrate chamber is formed between the first ACS and the second CEM, and between the second ACS and the first CEM; The first circulating fluid circuit system includes water tanks and circulating pumps that are respectively connected to each compartment.

[0009] The selective separation unit employs a specific membrane stack arrangement to achieve efficient separation of sodium chloride and sodium sulfate. Its core lies in the alternating arrangement of cation exchange membranes and monovalent / divalent selective anion exchange membranes within the membrane stack, forming multiple sets of alternating desalination and concentration chambers. When the mixed salt solution enters the desalination chamber, under the drive of a DC electric field, Na+... + With Cl - Due to its monovalent nature, SO42- can more easily pass through cation exchange membranes and monovalent / divalent selective anion exchange membranes and migrate into the concentrate chamber. 2- Due to their high divalent charge density and large hydration radius, ions are effectively retained in the desalination chamber by the steric hindrance and charge repulsion of the selective anion exchange membrane. This membrane arrangement avoids the problem of insufficient separation coefficients of monovalent and divalent anions caused by relying on only a single type of ion exchange membrane in conventional electrodialysis, significantly improving the selective separation efficiency of sodium chloride and sodium sulfate. Furthermore, by using homogeneous or alloy-type monovalent and divalent selective anion exchange membranes, the membrane resistivity is below 10 Ω / cm. 2 Furthermore, the exchange capacity is not less than 1.3 mol / kg, which further reduces operating energy consumption and increases ion flux, enabling the concentrate chamber to obtain high-purity sodium chloride solution and the desalination chamber to obtain high-purity sodium sulfate solution, providing stable and well-defined high-quality raw materials for subsequent multi-chamber dual electro-exchange and bipolar membrane electrodialysis processes.

[0010] Furthermore, the first circulating liquid circuit system includes a concentrate circulating system, a desalination circulating system, and a first electrode liquid circulating system; The concentrate circulation system includes a concentrate tank and a first circulation pump, which are connected to the concentrate chamber to form a circulation loop; The freshwater circulation system includes a freshwater tank and a second circulation pump, which are connected to the freshwater chamber to form a circulation loop; The first electrode liquid circulation system, including a first electrode liquid tank and a third circulation pump, is connected to the first electrode chamber to form a circulation loop. The concentrate circulation system within the first circulation system includes a concentrate tank and a first circulation pump. This concentrate tank contains pure water at the start of the reaction to receive chloride and sodium ions migrating across the membrane from the desalination chamber. Under the influence of a DC electric field, the sodium chloride and sodium sulfate mixed solution in the desalination chamber undergoes selective permeation through the cation exchange membrane and the divalent selective anion exchange membrane, controlling the Na+- ... + With Cl - Targeted migration into the concentrate chamber, SO4 2-The product is effectively retained in the desalination chamber by a divalent selective anion exchange membrane. As the first circulation pump continuously drives the liquid to circulate between the concentrate chamber and the concentrate tank at a flow rate of 1000 to 10000 mL / min, the composition of the liquid in the concentrate tank gradually changes from pure water to a sodium chloride-rich solution. The sodium chloride concentration can reach 1.0 to 2.5 mol / L, and the purity continuously increases with the reaction progress until it meets the feed requirements of subsequent processes. This circulation process not only achieves the enrichment and collection of the target product but also significantly weakens the concentration polarization layer on the membrane surface through forced convection, maintaining high flux and high selectivity for transmembrane ion migration.

[0011] The freshwater circulation system includes a freshwater tank and a second circulation pump. The freshwater tank initially contains a mixed salt solution of sodium chloride and sodium sulfate to be separated, with the total concentration of sodium chloride and sodium sulfate preferably between 1.0 and 2.5 mol / L. Driven by the second circulation pump, the mixed salt solution is continuously circulated between the freshwater chamber and the freshwater tank at a flow rate of 1000 to 10000 mL / min. Under the action of a DC electric field, the Na+ in the freshwater chamber... + With Cl - SO4 continuously migrates out and enters the adjacent concentrate chamber. 2- Due to the steric hindrance effect and the blocking effect of divalent charges, the sodium chloride is retained in the desalination chamber by the divalent selective anion exchange membrane. As the reaction proceeds, the sodium chloride concentration in the desalination tank gradually decreases while the relative concentration of sodium sulfate continuously increases, eventually transforming the liquid in the desalination tank into a solution with sodium sulfate as the main component, achieving a sodium sulfate purity of over 96%. The stable circulation rate provided by the second circulation pump ensures the homogeneity of the solution composition inside the desalination chamber, avoiding membrane stack voltage fluctuations and decreased separation efficiency caused by local ion depletion or accumulation.

[0012] The first electrode liquid circulation system includes a first electrode liquid tank and a third circulation pump. The first electrode liquid tank contains an electrolyte solution, specifically sodium sulfate, sodium chloride, or sodium nitrate solution, with a concentration controlled within the range of 0.05 to 0.1 mol / L. Driven by the third circulation pump, the electrode liquid forms a closed loop between the first electrode liquid tank and the first electrode chamber at a flow rate of 1000 to 10000 mL / min. The first electrode chamber is located in the region adjacent to the first cathode and first anode plates at both ends of the membrane stack. During energization, electrode reactions occur, accompanied by gas generation and heat release. The function of the electrode liquid circulation is to promptly remove the gas generated by the electrode reaction from the electrode chamber and out of the membrane stack, preventing bubble accumulation from physically interfering with ion migration in adjacent compartments. Simultaneously, the circulating electrode liquid acts as a highly efficient heat dissipation medium, carrying away the Joule heat generated by the electrode reaction and membrane stack resistance, and maintaining the operating temperature of the entire membrane stack within a preset range of 20 to 40°C. The continuous operation of the third circulation pump ensures the stability of the electrode fluid circulation and the cleanliness of the electrode environment, providing the necessary basic conditions for the long-term stable operation of the membrane stack under membrane stack voltage conditions of 5 to 50 V.

[0013] The concentrate chamber, desalination chamber, and electrode chamber are each equipped with an independent and closed circulating liquid circuit system, clearly defining the initial composition and final state transformation path of the materials in each tank. The concentrate tank converts pure water into a sodium chloride solution with a concentration of 1.0 to 2.5 mol / L. The desalination tank converts a mixed salt solution of sodium chloride and sodium sulfate with a total concentration of 1.0 to 2.5 mol / L into a sodium sulfate solution with a purity of over 96%. The electrode liquid in the first electrode tank, with a concentration of 0.05 to 0.1 mol / L, remains essentially unchanged but serves as a conductive and heat exchange carrier. The first, second, and third circulating pumps drive their respective liquid circuits to circulate within a flow rate range of 1000 to 10000 mL / min. The synergistic effect of these three pumps achieves the directional enrichment of target ions, the uniformity and stability of the feed solution components, and the isolation of byproducts and heat removal from the electrode reactions. This ensures the high efficiency of the selective electrodialysis separation process, the reliability of product quality, and the engineering adaptability for continuous operation of the entire device.

[0014] Optionally, the bipolar membrane electrodialysis unit is a bipolar membrane electrodialysis device, which includes: The second power source is electrically connected to the second anode plate and the second cathode plate; The second membrane stack consists of several adjacent electrodialysis membrane pair units (4 to 30 units). Each electrodialysis membrane pair unit includes a bipolar membrane (BPM), a first anion exchange membrane (AEM), a third CEM, a second AEM, and a fourth CEM stacked sequentially. A second electrode chamber is formed between the second anode plate, the second cathode plate, and the second membrane stack; An acid chamber is formed between the BPM and the first AEM; An ammonium chloride chamber is formed between the first AEM and the third CEM; An ammonium sulfate chamber is formed between the fourth CEM and the second AEM; A sodium sulfate chamber is formed between the second AEM and the fourth CEM; An alkaline chamber forms between the fourth CEM and BPM; The second circulating fluid system includes water tanks and circulating pumps that are respectively connected to each compartment.

[0015] Sodium sulfate solution produced by the selective separation unit is introduced into the sodium sulfate chamber, and ammonium chloride solution produced by the dual electrodisplacement unit is introduced into the ammonium chloride chamber. Under the drive of a DC electric field, water dissociation and metathesis reactions occur simultaneously inside the bipolar membrane electrodialysis device. Under the reverse bias of the BPM, water dissociation occurs at the interface layer, continuously supplying H₂ to the acid and alkali chambers, respectively. + Ions and OH - Ions. Meanwhile, Cl in the ammonium chloride chamber... - Ions migrate through the first AEM under the influence of an electric field and enter the acid chamber, where they interact with H+ provided by the BPM interface layer. + Ions combine to form hydrochloric acid; SO4 in the sodium sulfate chamber 2- Ions migrate through the second AEM into the ammonium sulfate chamber, while NH4 in the ammonium chloride chamber... + Ions migrate through the fourth CEM into the ammonium sulfate chamber, where they combine to form the target product, ammonium sulfate solution; Na+ in the sodium sulfate chamber... + Ions then migrate through the fourth CEM into the alkaline chamber 4f, where they interact with OH groups provided by the BPM interface layer. - Ions combine to form a sodium hydroxide solution. This ion migration pathway design integrates bipolar membrane water dissociation, selective migration of anions and cations, and metathesis reactions within a single membrane stack. This allows the three high-value products (ammonium sulfate, hydrochloric acid, and sodium hydroxide) to be generated simultaneously in spatially separated compartments, effectively preventing untargeted mixing or premature reaction of sulfate and ammonium ions, and sodium and chloride ions. This ensures the directional enrichment and high-purity production of each product in its corresponding compartment. In this bipolar membrane electrodialysis unit, the acid, ammonium sulfate, and alkali compartments initially contain pure water, which gradually transforms into hydrochloric acid, ammonium sulfate, and sodium hydroxide solutions under the influence of a DC electric field and ion migration. The product concentration continuously increases with the reaction progress, with ammonium sulfate concentration reaching over 1.0 mol / L and purity not less than 97%, while hydrochloric acid and sodium hydroxide concentrations simultaneously reach over 0.9 mol / L.

[0016] This membrane arrangement and compartment configuration eliminates the post-separation steps necessary for product mixing in traditional neutralization or metathesis reactions, significantly improving process selectivity, atom economy, and single-pass product yield. Furthermore, by configuring independent second-circulation liquid systems for the second electrode chamber, acid chamber, ammonium chloride chamber, ammonium sulfate chamber, sodium sulfate chamber, and alkali chamber, reaction mass transfer efficiency and operational robustness are further enhanced. The second-circulation liquid system drives the circulation of sodium sulfate electrode liquid at a concentration of 0.05 to 0.1 mol / L between the second cathode and second anode plates, promptly removing gases and heat generated by the electrode reactions, preventing bubbles from entering adjacent compartments and interfering with ion migration paths, and maintaining the membrane stack temperature within a preset range of 20 to 40°C. The acid, ammonium sulfate, and alkali circulation systems drive the liquids in their respective compartments to circulate between the compartments and corresponding water tanks at a flow rate of 1000 to 10000 mL / min. This promptly removes newly formed acid, alkali, and salt products from the membrane surface, preventing concentration polarization and fouling risks caused by excessively high local product concentrations, and maintaining high current efficiency and stable membrane stack voltage. The ammonium chloride and sodium sulfate circulation systems drive the feed solution to circulate between the feed chamber and corresponding water tanks at the same flow rate, ensuring that the Cl... - NH4 + Na + With SO4 2- A continuous and sufficient supply at the membrane interface prevents voltage increases and side reactions caused by ion depletion. Independent control of each circulating pump allows for dynamic optimization of temperature, flow rate, and concentration gradient within each compartment based on the feedstock conversion process, flexibly adapting to different processing scales and product concentration requirements. The bipolar membrane electrodialysis unit, through a specific BPM-AEM-CEM alternating stack arrangement and a six-compartment spatial structure, achieves the directional migration and precise pairing of four ions from sodium sulfate and ammonium chloride feedstocks, simultaneously completing the clean and efficient synthesis of three basic chemicals—ammonium sulfate, hydrochloric acid, and sodium hydroxide—within the same membrane stack. Combined with a multi-independent circulating liquid path system, the device effectively suppresses concentration polarization and membrane fouling, maintaining stable operation within a membrane stack voltage range of 5 to 50 V, achieving a current efficiency of over 80%, and producing ammonium sulfate products with extremely low chloride ion residues, directly meeting the application requirements of chlorine-sensitive crops. This technical solution significantly shortens the traditional metathesis reaction and acid-base preparation process, reduces equipment footprint and pipeline connections, and provides an efficient, compact and environmentally friendly engineering implementation path for the high-value conversion of waste salt and product refining processes in skid-mounted integrated devices.

[0017] Furthermore, the second circulating liquid system includes a second polar liquid circulating system, an acid circulating system, an ammonium chloride circulating system, an ammonium sulfate circulating system, a sodium sulfate circulating system, and an alkali circulating system; The second electrode liquid circulation system includes a second electrode liquid tank and a fourth circulation pump, which are connected to the second electrode chamber to form a circulation loop; The acid circulation system includes an acid tank and a fifth circulation pump, which are connected to the acid chamber to form a circulation loop; The ammonium chloride circulation system includes an ammonium chloride water tank and a sixth circulation pump, which are connected to the ammonium chloride chamber to form a circulation loop; The ammonium sulfate circulation system includes an ammonium sulfate water tank and a seventh circulation pump, which are connected to the ammonium sulfate chamber to form a circulation loop; The sodium sulfate circulation system includes a sodium sulfate water tank and an eighth circulation pump, which are connected to the sodium sulfate chamber to form a circulation loop; The alkali circulation system includes an alkali tank and a ninth circulation pump, which are connected to the alkali chamber to form a circulation loop.

[0018] The second electrode liquid circulation system includes a second electrode liquid tank and a fourth circulation pump. The second electrode liquid tank contains an electrolyte solution, specifically sodium sulfate, sodium chloride, or sodium nitrate solution, with a concentration controlled within the range of 0.05 to 0.1 mol / L. Driven by the fourth circulation pump, the electrode liquid forms a closed loop between the second electrode tank and the second electrode chamber formed by the second cathode and second anode plates at a flow rate of 1000 to 10000 mL / min. During the energization process, water electrolysis occurs in the second electrode chamber, accompanied by the generation of hydrogen and oxygen and the release of Joule heat. The function of the electrode liquid circulation is to rapidly remove the gases generated by the electrode reaction from the electrode chamber and out of the membrane stack, preventing gas bubbles from accumulating at the membrane interface and physically hindering ion migration in adjacent acid and alkali chambers. Simultaneously, the circulating electrode liquid acts as a highly efficient heat dissipation medium, continuously removing heat from the electrode reaction and membrane stack resistance, maintaining the membrane stack operating temperature within a preset range of 20 to 40°C, providing a fundamental guarantee for the long-term stable operation of the membrane stack under voltage conditions of 5 to 50 V.

[0019] The acid circulation system includes an acid tank and a fifth circulation pump. The acid tank contains pure water at the start of the reaction. Driven by the fifth circulation pump, the liquid circulates between the acid chamber and the acid tank at a flow rate of 1000 to 10000 mL / min. The acid chamber is located between the BPM and the first AEM. Under the influence of a DC electric field, the water in the BPM interface layer dissociates, generating H₂. + Ions enter the acid chamber, while Cl in the ammonium chloride chamber... - The product migrates through the first AEM and enters the acid chamber, where it combines to form hydrochloric acid. As the reaction progresses, the liquid in the acid tank gradually changes from pure water to a hydrochloric acid solution with a concentration exceeding 0.9 mol / L. The circulation action of the fifth circulation pump promotes the uniform dispersion and concentration homogenization of the newly formed hydrochloric acid in the acid chamber, effectively preventing the risk of concentration polarization and film corrosion caused by excessively high local product concentrations.

[0020] The ammonium chloride circulation system includes an ammonium chloride tank and a sixth circulation pump. The ammonium chloride tank contains an ammonium chloride solution produced by the dual electrodisplacement unit at a concentration of 1.0 to 2.5 mol / L during the initial reaction stage. Driven by the sixth circulation pump, the ammonium chloride solution circulates between the ammonium chloride chamber and the ammonium chloride tank at a flow rate of 1000 to 10000 mL / min. The ammonium chloride chamber is located between the first AEM and the fourth CEM. Under the influence of a DC electric field, NH4+... + Migrating towards the cathode, passing through the fourth CEM and entering the ammonium sulfate chamber, Cl - Ions migrate towards the anode, passing through the first AEM and entering the acid chamber. As the reaction continues, the concentration of ammonium chloride in the ammonium chloride tank gradually decreases. The stable circulation flow rate provided by the sixth circulation pump ensures that a sufficient ion supply concentration is always maintained at the membrane interface of the ammonium chloride chamber, avoiding the attenuation of ion migration flux and the increase in membrane stack voltage caused by concentration polarization.

[0021] The ammonium sulfate circulation system includes an ammonium sulfate tank and a seventh circulation pump. The ammonium sulfate tank contains pure water during the initial reaction stage. Driven by the seventh circulation pump, the liquid circulates between the ammonium sulfate chamber and the ammonium sulfate tank at a flow rate of 1000 to 10000 mL / min. The ammonium sulfate chamber is located between the fourth CEM and the second AEM, and simultaneously receives NH4 from the ammonium chloride chamber under the influence of a DC electric field. + Ions and SO4 from the sodium sulfate chamber 2- Two types of ions combine in the ammonium sulfate chamber to form ammonium sulfate. As the reaction progresses, the liquid in the ammonium sulfate tank gradually changes from pure water to an ammonium sulfate solution, with an ammonium sulfate concentration of over 1.0 mol / L and a purity of not less than 97%. The circulation action of the seventh circulation pump promotes the uniform dispersion and concentration homogenization of the newly formed ammonium sulfate in the ammonium sulfate chamber, effectively preventing the risk of film scaling caused by local supersaturation of the product.

[0022] The sodium sulfate circulation system includes a sodium sulfate tank and an eighth circulation pump. The sodium sulfate tank contains a sodium sulfate solution produced by the selective separation unit at a concentration of 1.0 to 2.5 mol / L during the initial stage of the reaction. Driven by the eighth circulation pump, the sodium sulfate solution circulates between the sodium sulfate chamber and the sodium sulfate tank at a flow rate of 1000 to 10000 mL / min. The sodium sulfate chamber is located between the second AEM and the fifth CEM. Under the influence of a DC electric field, Na... + Ions migrate towards the cathode, pass through the fifth CEM, and enter the alkali chamber; SO4 2- The solution migrates towards the anode, passing through the second AEM and entering the ammonium sulfate chamber. As the reaction proceeds, the sodium sulfate concentration in the sodium sulfate tank gradually decreases. The continuous operation of the eighth circulation pump keeps the solution composition in the sodium sulfate chamber uniform, avoiding the reduction in current efficiency and the risk of side reactions caused by the depletion of local sodium or sulfate ions.

[0023] The alkali circulation system includes an alkali tank and a ninth circulation pump. The alkali tank contains pure water during the initial reaction stage. Driven by the ninth circulation pump, the liquid circulates between the alkali chamber and the alkali tank at a flow rate of 1000 to 10000 mL / min. The alkali chamber is located between the fifth CEM and the BPM. Under the influence of a DC electric field, OH⁻ ions generated by the dissociation of water at the BPM interface layer enter the alkali chamber, while Na⁻ ions in the sodium sulfate chamber... + Ions migrate through the fifth CEM into the alkali chamber, where they combine to form sodium hydroxide. As the reaction progresses, the liquid in the alkali tank gradually transforms from pure water into a sodium hydroxide solution with a concentration exceeding 0.9 mol / L. The circulation action of the ninth circulation pump promotes the uniform dispersion and concentration homogenization of the newly formed sodium hydroxide in the alkali chamber, while forced convection reduces the concentration boundary layer thickness at the membrane surface to maintain high current efficiency.

[0024] Each functional compartment of the bipolar membrane electrodialysis unit is equipped with an independent closed-loop circulating liquid path system, clearly defining the initial composition and final transformation path of the materials in each tank. In the ammonium chloride tank, the concentration of ammonium chloride solution decreases with the reaction; in the sodium sulfate tank, the concentration of sodium sulfate solution decreases synchronously; in the acid tank, pure water is converted to hydrochloric acid solution; in the ammonium sulfate tank, pure water is converted to ammonium sulfate solution; in the alkali tank, pure water is converted to sodium hydroxide solution; and the composition of the electrode solution in the second electrode tank remains constant. The fourth to ninth circulation pumps drive the corresponding liquid paths to circulate within a flow rate range of 1000 to 10000 mL / min. The synergistic effect of the six circulation systems achieves continuous and directional supply of feed ions, efficient and directional collection of product ions, timely isolation and removal of electrode byproducts, and precise control of membrane stack temperature and concentration polarization. This ensures the engineering realization of high selectivity, high conversion rate, and long-term stable operation of the bipolar membrane electrodialysis unit in a skid-mounted multi-stage electrically driven membrane integrated device.

[0025] Optionally, the dual electro-displacement unit is a dual electrodialysis device, comprising: The third power source is electrically connected to the third cathode plate and the third anode plate; The third membrane stack consists of several adjacent electrodisplacement membrane pair units (numbering 4 to 30), and the electrodisplacement membrane pair units include the third AEM, the fifth CEM, the fourth AEM, and the sixth CEM stacked in sequence. A third electrode chamber is provided between the third cathode plate, the third anode plate and the third membrane stack; The first product chamber is formed between the third AEM and the fifth CEM; The first raw material chamber is formed between the fifth CEM and the fourth AEM; A second product chamber is formed between the fourth AEM and the sixth CEM; A second raw material chamber is formed between the sixth CEM and the third AEM; The third circulating fluid system includes water tanks and circulating pumps that are connected to each compartment respectively.

[0026] When a sodium chloride solution produced by the selective separation unit is introduced into the first raw material chamber and an ammonium carbonate solution prepared by the micro-nano bubble generator is introduced into the second raw material chamber, a synchronous double electrodisplacement reaction occurs under the drive of a DC electric field.

[0027] The dual electro-displacement unit, through a specific alternating stacked arrangement of anion and cation exchange membranes and a five-compartment spatial structure, achieves the directional migration and cross-pairing of four ions from ammonium carbonate and sodium chloride feedstocks, simultaneously completing the clean synthesis of these two high-value-added chemicals, sodium carbonate and ammonium chloride, within the same membrane stack. Coupled with a multi-independent circulating liquid path system, the device effectively suppresses concentration polarization and membrane fouling, maintaining stable operation within a membrane stack voltage range of 5 to 50 V, with a current efficiency exceeding 85%. This technical solution significantly shortens the process flow of traditional stepwise displacement reactions, reduces equipment footprint and the number of piping connections, and provides an efficient and compact engineering implementation path for the co-conversion of mixed salts and waste gas in integrated devices.

[0028] Furthermore, the third circulating liquid system includes a third polar liquid circulating system, a first product liquid circulating system, a first raw material liquid circulating system, a second product liquid circulating system, and a second raw material liquid circulating system; The third electrode liquid circulation system includes a third electrode liquid tank and a tenth circulation pump, which are connected to the third electrode chamber to form a circulation loop; The first product liquid circulation system includes a first product water tank and an eleventh circulation pump, which are connected to the first product chamber to form a circulation loop. The first raw material liquid circulation system includes a first raw material water tank and a twelfth circulation pump, which are connected to the first raw material chamber to form a circulation loop; The second product liquid circulation system includes a second product water tank and a thirteenth circulation pump, which are connected to the second product chamber to form a circulation loop. The second feed liquid circulation system includes a second feed water tank and a fourteenth circulation pump, which are connected to the second feed chamber to form a circulation loop. The third electrode liquid tank contains an electrolyte solution, specifically sodium sulfate solution, sodium chloride solution, or sodium nitrate solution, with a concentration controlled within the range of 0.05 to 0.1 mol / L. Driven by the tenth circulation pump, the electrode liquid forms a closed circulation loop between the third electrode liquid tank and the third electrode chamber formed by the third cathode plate and the third anode plate at a flow rate of 1000 to 10000 mL / min. During the energization process, water electrolysis occurs in the third electrode chamber, accompanied by the generation of hydrogen and oxygen and the release of Joule heat. The function of the electrode liquid circulation is to rapidly carry the gas generated by the electrode reaction away from the electrode chamber and out of the membrane stack, preventing gas bubbles from accumulating at the membrane interface and physically hindering ion migration in the adjacent first product chamber and second feed chamber. Meanwhile, the circulating electrode fluid acts as an efficient heat dissipation medium, continuously removing heat from the electrode reaction and the membrane stack resistance, maintaining the membrane stack operating temperature within the preset range of 20 to 40°C, and providing a fundamental guarantee for the long-term stable operation of the membrane stack under voltage conditions of 5 to 50 V.

[0029] The first feed tank contains a sodium chloride solution produced by the selective separation unit at the initial stage of the reaction, with a sodium chloride concentration of 1.0 to 2.5 mol / L. Driven by the twelfth circulation pump, the sodium chloride solution circulates between the first feed chamber and the first feed tank at a flow rate of 1000 to 10000 mL / min. The first feed chamber is located between the fifth CEM and the fourth AEM. Under the action of a DC electric field, Na... + Migrating towards the cathode, passing through the fifth CEM and entering the first product chamber, Cl - The Na+ migrates towards the anode, passing through the fourth AEM and entering the second product chamber. As the reaction continues, the Na+ in the first feed tank... + With Cl - As the concentration gradually decreases, the stable circulation rate provided by the twelfth circulation pump ensures that a sufficient ion supply concentration is always maintained at the membrane interface of the first feed chamber, avoiding the attenuation of ion migration flux and the increase of membrane stack voltage caused by concentration polarization.

[0030] The second raw material tank contains an ammonium carbonate solution prepared by a micro / nano bubble generator during the initial stage of the reaction, with a preferred ammonium carbonate concentration of 1.0 to 2.0 mol / L. Driven by the fourteenth circulating pump, the ammonium carbonate solution circulates between the second raw material chamber and the second raw material tank at a flow rate of 1000 to 10000 mL / min. The second raw material chamber is located between the sixth CEM and the third AEM. Under the influence of a DC electric field, NH4... + Ions migrate towards the cathode, pass through the sixth CEM, and enter the second product chamber; CO3 2-The ammonium carbonate migrates towards the anode, passing through the third AEM and entering the first product chamber of the adjacent electrodisplacement membrane unit. As the reaction proceeds, the concentration of ammonium carbonate in the second feed tank gradually decreases. The continuous operation of the fourteenth circulation pump keeps the solution composition in the second feed chamber uniform, avoiding the reduction in current efficiency and the risk of side reactions caused by local depletion of sodium or chloride ions.

[0031] The first product tank contains pure water at the start of the reaction. Driven by the eleventh circulation pump, the liquid circulates between the first product chamber and the first product tank at a flow rate of 1000 to 10000 mL / min. The first product chamber is located between the third AEM and the fifth CEM, and simultaneously receives Na from the first feedstock chamber under the action of a DC electric field. + CO3 from adjacent electrodisplacement membrane units 2- Two types of ions combine in the first product chamber to form sodium carbonate. As the reaction progresses, the liquid in the first product tank gradually transforms from pure water into a sodium carbonate solution with a concentration of over 1.0 mol / L and a purity of no less than 98%. The circulation action of the eleventh circulation pump promotes the uniform dispersion and concentration homogenization of the newly formed sodium carbonate in the first product chamber, effectively preventing the risk of film fouling caused by localized oversaturation of the product.

[0032] The second product tank contains pure water during the initial stage of the reaction. Driven by the thirteenth circulation pump, the liquid circulates between the second product chamber and the second product tank at a flow rate of 1000 to 10000 mL / min. The second product chamber is located between the fourth AEM and the sixth CEM, and simultaneously receives Cl from the first raw material chamber under the action of a DC electric field. - With NH4 from the second raw material chamber + The two ions combine in the second product chamber to form ammonium chloride. As the reaction progresses, the liquid in the second product tank gradually transforms from pure water into an ammonium chloride solution, with an ammonium chloride concentration exceeding 1.2 mol / L and a purity of no less than 98%. The circulation action of the thirteenth circulating pump ensures the supply of NH4+ in the second product chamber. + With Cl - This ensures sufficient contact reaction and uniform distribution of product concentration, while forced convection reduces the concentration boundary layer thickness on the membrane surface to maintain high current efficiency.

[0033] Each functional compartment of the dual electro-displacement unit constructs an independent closed-loop circulating liquid circuit system, clearly defining the initial composition and final conversion path of the materials in each tank. In the first feed tank, the concentration of ammonium carbonate solution decreases with the reaction; in the second feed tank, the concentration of sodium chloride solution decreases synchronously; in the first product tank, pure water is converted to sodium carbonate solution; in the second product tank, pure water is converted to ammonium chloride solution; and in the third electrode tank, the electrode liquid composition remains constant. The tenth to fourteenth circulation pumps drive the corresponding liquid circuits to circulate within a flow rate range of 1000 to 10000 mL / min. The five circulation systems work synergistically to achieve continuous and directional supply of feed ions, efficient and directional collection of product ions, timely isolation and removal of electrode byproducts, and precise control of membrane stack temperature and concentration polarization. This ensures the engineering realization of high selectivity, high conversion rate, and long-term stable operation of the dual electro-displacement unit in a skid-mounted multi-stage electro-driven membrane integrated device.

[0034] Optionally, the gas-liquid mixing conversion unit is a micro / nano bubble generator, comprising: The bubble generator contains a reaction aqueous phase. It has a water inlet pipe and an air inlet at the bottom, and a bubble collector at the top. The water inlet pipe houses a water pump 21d and a filter screen 21e, which contains a suspended solids filter and an activated carbon adsorption membrane. The bubble collector is connected to an output pipe 21f, which is equipped with a bubble check valve 21g (anti-backflow) and a bubble solenoid valve 21h. The final output pipe leads to a dual electro-displacement unit. A suspended level gauge 21i is installed on the side wall of the bubble collector to monitor the liquid level inside the tank and transmit the signal back to the control box.

[0035] A gas compressor is used to compress a gas mixture into primary microbubbles. The gas release device has an inlet end connected to a gas compressor via a gas delivery pipe and an outlet pipe extending to the bottom of the bubble generator. The gas release device has a gas phase and a liquid phase space, and an internal pump is connected to it to further shear and break the primary microbubbles into micro-nano-scale bubbles under semi-vacuum conditions. The control box contains a built-in regulating valve located on the gas outlet pipe. The control box is electrically connected to the gas compressor and gas release device. The space between the gas and liquid phases forms the core bubble-forming chamber within the gas release device, the central location for the generation of micro / nano bubbles and the formation of the gas-liquid interface. A stable semi-vacuum negative pressure environment is created between the gas and liquid phases by a pump. Combined with a gas pressure sensor, closed-loop control of the chamber pressure is achieved. This allows the primary microbubbles delivered by the gas compressor to be sheared, dispersed, and broken up at the gas-liquid interface, ultimately forming micron-sized and nano-sized bubbles with a particle size of less than 3 μm. The sole source of the liquid phase between the gas and liquid phases is the pre-stored reaction pure water in the bubble generator. Its entry and stabilization process is as follows: Before the device is started, the control box first starts the water inlet pump to pump the pretreated pure water into the bubble generator, forming a stable reaction aqueous phase. The suspension level monitor monitors the liquid level in the tank in real time, and automatically stops the pump when the preset height is reached. At this time, the outlet of the gas pipe is completely submerged below the pure water surface. After the pump is started, it continuously pumps air into the closed chamber between the gas and liquid phases to create a stable semi-vacuum negative pressure environment, making the pressure in the chamber significantly lower than the atmospheric pressure environment in the bubble generator, forming a clear pressure difference. Driven by the pressure difference, the pure water in the bubble generator is drawn back from bottom to top into the end of the chamber between the gas and liquid phases along the outlet pipe, forming a continuous and stable liquid phase zone in the chamber.

[0036] The gas inlet of the gas release device 23 is connected to the gas compressor 22 via a gas delivery pipe 23a, and the outlet pipe 23c extends to the bottom of the bubble generator 21 and is fully submerged below the surface of the aqueous phase in the bubble generator 21. The gas release device 23 has a gas phase and liquid phase space 23b inside, and a vacuum pump 24 is provided at the bottom of the gas release device 23. The vacuum pump 24 extends into the gas phase and liquid phase space 23b to create a stable semi-vacuum negative pressure environment in the gas phase and liquid phase space 23b region.

[0037] The gas phase and liquid phase space 23b is a closed chamber integrally formed within the inner cavity of the gas release device 23. Its inlet end is sealed and connected to the gas delivery pipe 23a, and its outlet end is sealed and connected to the outlet pipe 23c. A PTG500 gas pressure sensor [U1] is installed on the top of the chamber to monitor the negative pressure value in the chamber in real time and feed the signal back to the control box 25 to realize the dynamic adjustment of the power of the pump 24 and maintain the stability of the semi-vacuum environment in the chamber.

[0038] The sole source of the liquid phase between the gas and liquid phases is the pre-stored reaction pure water in the bubble generator. Its entry and stabilization process is as follows: Before the device is started, the control box first starts the water inlet pump to pump the pretreated pure water into the bubble generator, forming a stable reaction aqueous phase. The suspension level monitor monitors the liquid level in the tank in real time, and automatically stops the pump when the preset height is reached. At this time, the outlet of the gas pipe is completely submerged below the pure water surface. After the pump is started, it continuously pumps air into the closed chamber between the gas and liquid phases to create a stable semi-vacuum negative pressure environment, making the pressure in the chamber significantly lower than the atmospheric pressure environment in the bubble generator, forming a clear pressure difference. Driven by the pressure difference, the pure water in the bubble generator is drawn back from bottom to top into the end of the chamber between the gas and liquid phases along the outlet pipe, forming a continuous and stable liquid phase zone in the chamber.

[0039] Furthermore, the gas releaser has a hydrophobic anti-crystallization coating on the surface between the gas phase and the liquid phase and on the inner wall of the gas pipe in contact with the mixed gas. The gas releaser shell is equipped with a jacketed heat exchanger to maintain the internal temperature within a preset range (30~40℃) to suppress the crystallization of ammonium bicarbonate. The hydrophobic anti-crystallization coating is a polytetrafluoroethylene nano-coating.

[0040] Furthermore, the gas compressor's inlet end is equipped with an ammonia pipeline and a carbon dioxide pipeline. The ammonia pipeline is equipped with a first regulating valve, and the carbon dioxide pipeline is equipped with a second regulating valve. A non-dispersive infrared gas sensor is installed on the gas delivery pipeline to monitor the molar ratio of ammonia and carbon dioxide in the mixed gas in real time. The first regulating valve, the second regulating valve, the non-dispersive infrared gas sensor, and the control box are electrically connected. The control box compares the measured molar ratio fed back by the non-dispersive infrared gas sensor with the preset target molar ratio and dynamically adjusts the opening of the first regulating valve and the second regulating valve to achieve closed-loop precise control of the gas ratio.

[0041] Furthermore, the preset target molar ratio is 1:1 to 3:1 for ammonia to carbon dioxide, preferably 2:1 to 2.5:1; the control precision ensures that the deviation between the actual molar ratio and the target molar ratio does not exceed ±3%.

[0042] The gas-liquid mixing and conversion unit utilizes a micro-nano bubble generator to achieve efficient absorption of ammonia and carbon dioxide from industrial waste gas and directional preparation of ammonium carbonate solution. Through the coordinated operation of a gas compressor, gas release device, bubble generator, and control box, the device disperses the ammonia and carbon dioxide mixture into the aqueous phase as micro-nano bubbles, significantly increasing the gas-liquid contact area and extending the bubble residence time in the aqueous phase. This solves the technical challenges of low gas-liquid mass transfer efficiency, high gas escape rate, and easy formation of ammonium bicarbonate crystals that clog the equipment in traditional bubbling absorption processes.

[0043] A gas compressor is used to compress a mixture of ammonia and carbon dioxide to a preset pressure and deliver it to a gas release device. The gas compressor has ammonia and carbon dioxide pipelines, with a first regulating valve on the ammonia pipeline and a second regulating valve on the carbon dioxide pipeline. A non-dispersive infrared gas sensor is installed on the gas delivery pipeline to monitor the molar ratio of ammonia to carbon dioxide in the mixed gas in real time. The control box is electrically connected to the first and second regulating valves and the non-dispersive infrared gas sensor. Based on the deviation between the measured molar ratio fed back by the sensor and the preset target molar ratio of 1:1 to 3:1, the opening of the first and second regulating valves is dynamically adjusted to achieve closed-loop precise control of the ammonia to carbon dioxide ratio. The control accuracy ensures that the deviation between the actual molar ratio and the target molar ratio does not exceed three percent. This precise proportioning function ensures that the ammonia to carbon dioxide ratio in the gas entering the bubble generator is always within the optimal reaction measurement range, preferably 2:1 to 2.5:1, thereby effectively suppressing the tendency of ammonium bicarbonate formation and ensuring the high concentration and high purity of the subsequent ammonium carbonate solution.

[0044] The gas release unit's inlet is connected to a gas compressor via a gas delivery pipe, while the outlet pipe extends to the bottom of the bubble generator. The gas release unit contains a gas-liquid phase chamber connected to an external pump, which creates a semi-vacuum environment in this chamber. After being pressurized by the gas compressor, the primary bubble mixture enters the gas release unit and undergoes rapid expansion and turbulent shearing under semi-vacuum conditions in the gas-liquid phase chamber, further breaking down the primary bubbles into micro- and nano-sized bubbles. The gas release unit's outer shell is equipped with a jacketed heat exchanger to maintain the internal temperature within a preset range of 30 to 40°C. This temperature control effectively suppresses the risk of low-temperature crystallization of ammonium bicarbonate inside the gas release unit, ensuring the continuity and stability of the micro- and nano-bubble generation process. Simultaneously, the inner walls of the gas-liquid phase chamber and the inner walls of the gas delivery pipe in contact with the mixed gas are coated with a polytetrafluoroethylene (PTFE) nano-coating as a hydrophobic anti-crystallization coating, further reducing the probability of ammonium bicarbonate crystal adhesion and scaling on the surfaces of key flow components.

[0045] The bubble generator contains the aqueous reaction phase and has an inlet pipe and an air inlet at the bottom. The inlet pipe houses an inlet pump and a filter screen, which includes a suspended solids filter and an activated carbon adsorption membrane. This pre-treats the incoming pure water to remove suspended particles and trace organic matter, preventing impurities from affecting the quality of the ammonium carbonate solution. A bubble collector is located at the top of the bubble generator and connects to an outlet pipe. The outlet pipe is equipped with a bubble check valve to prevent gas backflow and a bubble solenoid valve to control the timing of ammonium carbonate solution output. A suspended level gauge is installed on the side wall of the bubble collector to monitor the liquid level in real time and transmit the signal back to the control box, enabling automatic control of the inlet pump's start and stop to maintain a stable liquid level in the tank. Micro- and nano-bubbles generated by the gas release device are released from the bottom of the tank and uniformly dispersed in the aqueous phase. Due to their small size, large specific surface area, and internal high pressure, these micro- and nano-bubbles rise extremely slowly in water and have a significantly prolonged residence time. The average particle size of the micro- and nano-bubbles is mainly distributed between 100 nm and 50 μm, with nano-sized bubbles smaller than 1 μm accounting for no less than 30%. This particle size distribution characteristic allows ammonia and carbon dioxide in the bubbles to be continuously transferred to the aqueous phase via molecular diffusion and react with water to form ammonium carbonate. The reaction formula can be expressed as 2NH3 + CO2 + H2O to produce (NH4)2CO3.

[0046] The control box is electrically connected to the gas compressor, gas release device, first regulating valve, second regulating valve, non-dispersive infrared gas sensor, and suspended liquid level gauge. It has a built-in programmable logic controller (PLC) to coordinate the operating parameters of each component. The control box automatically adjusts the inlet gas flow rate within the range of 0.1 to 5.0 L / min according to preset process requirements, and controls the volume ratio of the total inlet gas to pure water within the range of 5% to 20% to suppress the formation of ammonium bicarbonate. Under these operating conditions, an ammonium carbonate solution with a concentration of 1.0 to 2.0 mol / L can be generated from the aqueous phase in the bubble generator after 30 to 40 minutes of reaction.

[0047] This invention integrates four units—selective electrodialysis, micro / nano bubble gas-liquid conversion, dual electrodisplacement, and bipolar membrane electrodialysis—into a single system. This achieves precise separation of monovalent and divalent anions in a mixed sodium chloride and sodium sulfate salt solution, as well as efficient capture and conversion of ammonia-containing carbon dioxide waste gas. Simultaneously, it produces a variety of high-value chemicals, including sodium carbonate, ammonium chloride, ammonium sulfate, hydrochloric acid, and sodium hydroxide. Compared to traditional stepwise treatment processes, this device significantly shortens the process chain, reduces the addition of chemical reagents and equipment footprint, ensures close material circulation between units, minimizes byproducts, and eliminates secondary pollution. While improving the resource utilization rate of waste salt and waste gas, it also significantly reduces overall energy consumption and operating costs, demonstrating both significant environmental benefits and engineering economics. Attached Figure Description

[0048] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the overall device of the present invention.

[0050] Figure 2 This is a schematic diagram of the first power supply connection of the selective separation unit of the present invention to the first membrane stack.

[0051] Figure 3 This is a schematic diagram of the first membrane and the separation membrane pair unit of the selective separation unit of the present invention.

[0052] Figure 4 This is a schematic diagram of the first circulating liquid circuit system of the selective separation unit of the present invention.

[0053] Figure 5 This is a schematic diagram of the ion movement system inside the selective separation unit of the present invention.

[0054] Figure 6 This is a schematic diagram of the second power supply connection to the second membrane stack in the bipolar membrane electrodialysis unit of the present invention.

[0055] Figure 7 This is a schematic diagram of the second membrane stack and the electrodialysis membrane pair unit of the bipolar membrane electrodialysis unit of the present invention.

[0056] Figure 8 This is a schematic diagram of the second circulating liquid circuit system of the bipolar membrane electrodialysis unit of the present invention.

[0057] Figure 9 This is a schematic diagram of the internal ion movement system of the bipolar membrane electrodialysis unit of the present invention.

[0058] Figure 10 This is a schematic diagram of the third power source connecting the third membrane stack to the dual electro-displacement unit of the present invention.

[0059] Figure 11 This is a schematic diagram of the third membrane stack and the electrodisplacement membrane pair unit of the dual electrodisplacement unit of the present invention.

[0060] Figure 12 This is a schematic diagram of the third circulating fluid circuit system of the dual electrodisplacement unit of the present invention.

[0061] Figure 13 This is a schematic diagram of the internal ion movement system of the dual electrodisplacement unit of the present invention.

[0062] Figure 14This is a schematic diagram of the micro / nano bubble generator of the present invention.

[0063] Figure Descriptions: 1-Selective separation unit, 1a-First electrode chamber, 1b-Desalinated water chamber, 1c-Concentrated water chamber, 2-Gas-liquid mixing and conversion unit, 3-Dual electrodisplacement unit, 3a-First product chamber, 3b-First feedstock chamber, 3c-Second product chamber, 3d-Second feedstock chamber, 3e-Third electrode chamber, 4-Bipolar membrane electrodialysis unit, 4a-Second electrode chamber, 4b-Acid chamber, 4c-Ammonium chloride chamber, 4d-Ammonium sulfate chamber, 4e-Sodium sulfate chamber, 4f-Alkali chamber, 11-First power source, 12-Separation membrane pair unit, 19-Concentrated water tank, 21-Bubble generator, 21a-Inlet pipe, 21b-Air inlet, 21c-Bubble collector Device, 21d-Inlet pump, 21e-Filter screen, 21f-Outlet pipe, 21g-Bubble check valve, 21h-Bubble solenoid valve, 21i-Suspension level gauge, 22-Gas compressor, 22a-Ammonia pipeline, 22b-Carbon dioxide pipeline, 22e-Non-dispersive infrared gas sensor, 23-Gas release device, 23a-Gas delivery pipe, 23b-Gas and liquid phase interface, 23c-Outlet pipe, 24-Ejector, 25-Control box, 31-Third power supply, 32-Electro-displacement membrane pair unit, 41-Second power supply, 42-Electro-dialysis membrane pair unit, 51-First circulation pump, 52-Second circulation pump, 53-Third circulation pump 54-Fourth Circulation Pump, 55-Fifth Circulation Pump, 56-Sixth Circulation Pump, 57-Seventh Circulation Pump, 58-Eighth Circulation Pump, 59-Ninth Circulation Pump, 61-First CEM, 62-Second CEM, 63-Third CEM, 64-Fourth CEM, 65-Fifth CEM, 66-Sixth CEM, 71-First ACS, 72-Second ACS, 81-First AEM, 82-Second AEM, 83-Third AEM, 84-Fourth AEM, 91-BPM, 101-First Cathode Plate, 102-Second Cathode Plate, 103-Third Cathode Plate, 110-Freshwater Tank, 111-First Electrolytic Tank 112-Second anode plate, 113-Third anode plate, 114-First anode plate, 221-First regulating valve, 222-Second regulating valve, 311-Third electrode liquid tank, 312-First product water tank, 313-First raw material water tank, 314-Second product water tank, 315-Second raw material water tank, 411-Second electrode liquid tank, 412-Acid tank, 413-Ammonium chloride water tank, 414-Ammonium sulfate water tank, 415-Sodium sulfate water tank, 416-Alkali tank, 510-Tenth circulating pump, 511-Eleventh circulating pump, 512-Twelfth circulating pump, 513-Thirteenth circulating pump, 514-Fourteenth circulating pump. Detailed Implementation

[0064] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0065] The concepts involved in this application will first be described with reference to the accompanying drawings. It should be noted that the following descriptions of various concepts are only for the purpose of making the content of this application easier to understand and do not constitute a limitation on the scope of protection of this application; furthermore, the embodiments and features in the embodiments of this application can be combined with each other unless otherwise specified. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0066] Example 1: This embodiment provides an electrically driven membrane device for converting mixed salts into acid-base ammonium salts. The device includes a selective separation unit 1, a gas-liquid mixing and conversion unit 2, a dual electro-displacement unit 3, and a bipolar membrane electrodialysis unit 4. Each unit is sequentially connected via material pipelines to achieve the synergistic high-value conversion of sodium chloride and sodium sulfate mixed salts, as well as ammonia-containing carbon dioxide waste gas, simultaneously producing sodium carbonate, ammonium chloride, ammonium sulfate, hydrochloric acid, and sodium hydroxide products.

[0067] The selective separation unit 1 is a selective electrodialysis device. Its first membrane stack is composed of several adjacent separation membrane pairs 12. Each separation membrane pair 12 includes a first CEM61, a first ACS71, a second CEM62, and a second ACS72 stacked sequentially. A first electrode chamber 1a is provided between the first anode plate 114, the first cathode plate 101, and the first membrane stack. A desalination chamber 1b is formed between the first CEM61 and the first ACS71, and between the second CEM62 and the second ACS72. A concentrate chamber 1c is formed between the first ACS71 and the second CEM62, and between the second ACS72 and the first CEM61. The concentrate circulation system in the first circulating liquid circuit system is formed by the concentrate tank 19 and the first circulating pump 51 connected to the concentrate chamber 1c to form a circulation loop. The desalination circulation system is formed by the desalination tank 110 and the second circulating pump 52 connected to the desalination chamber 1b to form a circulation loop. The first electrode liquid circulation system is formed by the first electrode liquid tank 111 and the third circulating pump 53 connected to the first electrode chamber 1a to form a circulation loop. During operation, the freshwater tank 110 contains a mixed salt solution of sodium chloride and sodium sulfate with a total concentration of 1.0 to 2.5 mol / L, the concentrated water tank 19 initially contains pure water, and the first electrode liquid tank 111 contains an electrolyte solution with a concentration of 0.05 to 0.1 mol / L. The first power supply 11 applies a DC voltage of 5 to 50V to the first cathode plate 101 and the first anode plate 114. Under the condition that the first circulation pump 51, the second circulation pump 52, and the third circulation pump 53 drive the circulation of each liquid path at a flow rate of 1000 to 10000 mL / min, the Na in the freshwater chamber 1b... + Driven by an electric field, Cl passes through adjacent concentrate chambers 1c of the first CEM61 and the second CEM62 respectively. - Driven by the electric field, SO4 migrates through the first ACS71 and the second ACS72 into the adjacent concentrate chamber 1c, while SO42... 2- Due to their high divalent charge density and large hydration radius, the sodium chloride is effectively retained in the desalination chamber 1b by the first ACS71 and the second ACS72. After continuous circulation, the liquid in the concentrate tank 19 gradually transforms from pure water into a sodium chloride solution with a concentration of 1.0 to 2.5 mol / L, while the liquid in the desalination tank 110 transforms into a sodium sulfate solution with a purity of over 96%. The first electrode liquid circulation system continuously carries away the gas and heat generated by the electrode reaction from the membrane stack, maintaining the membrane stack temperature within the range of 20 to 40°C, thereby achieving efficient and selective separation of sodium chloride and sodium sulfate. The gas-liquid mixing and conversion unit 2 can be selected as a micro / nano bubble generator, the specific structure of which can be referred to in Example 2.

[0068] The dual electro-displacement unit 3 is a dual electrodialysis device. Its third membrane stack is composed of several adjacent electro-displacement membrane pair units 32. Each electro-displacement membrane pair unit 32 includes a third AEM83, a fifth CEM65, a fourth AEM84, and a sixth CEM66 stacked sequentially. A third electrode chamber 3e is provided between the third cathode plate 103, the third anode plate 113, and the third membrane stack. A first product chamber 3a is formed between the third AEM83 and the fifth CEM65. A first raw material chamber 3b is formed between the fifth CEM65 and the fourth AEM84. A second product chamber 3c is formed between the fourth AEM84 and the sixth CEM66. A second raw material chamber 3d is formed between the sixth CEM66 and the third AEM83. In the third circulating liquid system, the third electrode liquid circulating system is formed by the third electrode liquid tank 311 and the tenth circulating pump 510 connected to the third electrode chamber 3e to form a circulating loop. The first product liquid circulating system is formed by the first product water tank 312 and the eleventh circulating pump 511 connected to the first product chamber 3a to form a circulating loop. The first raw material liquid circulating system is formed by the first raw material water tank 313 and the twelfth circulating pump 512 connected to the first raw material chamber 3b to form a circulating loop. The second product liquid circulating system is formed by the second product water tank 314 and the thirteenth circulating pump 513 connected to the second product chamber 3c to form a circulating loop. The second raw material liquid circulating system is formed by the second raw material water tank 315 and the fourteenth circulating pump 514 connected to the second raw material chamber 3d to form a circulating loop. During operation, the first raw material tank 313 contains a sodium chloride solution with a concentration of 1.0 to 2.5 mol / L produced by the selective separation unit 1; the second raw material tank 315 contains an ammonium carbonate solution with a concentration of 1.0 to 2.0 mol / L produced by the gas-liquid mixing and conversion unit 2; the first product tank 312 and the second product tank 314 initially contain pure water; and the third electrode tank 311 contains an electrolyte solution with a concentration of 0.05 to 0.1 mol / L. The third power supply 31 applies a DC voltage of 5 to 50 V to the third cathode plate 103 and the third anode plate 113. Under the condition that the tenth to fourteenth circulation pumps 514 drive the circulation of each liquid path at a flow rate of 1000 to 10000 mL / min, the Na in the first raw material chamber 3b... + Migrating towards the cathode, passing through the fifth CEM65, and entering the first product chamber 3a, Cl - NH4 migrates towards the anode, passing through the fourth AEM84 and entering the second product chamber 3c, and the second raw material chamber 3d. + Migrating towards the cathode, passing through the sixth CEM66, and entering the second product chamber 3c, CO3 2- It migrates towards the anode direction through the third AEM83 and enters the first product chamber 3a of the adjacent electrodisplacement membrane pair unit 32. Na + With CO3 2- Sodium carbonate and NH4 are formed in the first product chamber 3a. + With Cl -Ammonium chloride is generated in the second product chamber 3c. After continuous circulation reaction, the liquid in the first product tank 312 is converted from pure water to a sodium carbonate solution with a sodium carbonate concentration of 1.0 mol / L or higher and a purity of not less than 98%. The liquid in the second product tank 314 is converted from pure water to an ammonium chloride solution with an ammonium chloride concentration of 1.2 mol / L or higher and a purity of not less than 98%. The third electrode liquid circulation system continuously carries away the gas and heat generated by the electrode reaction from the membrane stack, maintaining the membrane stack temperature in the range of 20 to 40°C, and the current efficiency can reach more than 85%.

[0069] The bipolar membrane electrodialysis unit 4 is a bipolar membrane electrodialysis device. Its second membrane stack is composed of several adjacent electrodialysis membrane pair units 42. Each electrodialysis membrane pair unit 42 includes BPM91, first AEM81, third CEM63, second AEM82, and fourth CEM64 stacked sequentially. A second electrode chamber 4a is formed between the second anode plate 112, the second cathode plate 102, and the second membrane stack. An acid chamber 4b is formed between BPM91 and the first AEM81. An ammonium chloride chamber 4c is formed between the first AEM81 and the third CEM63. An ammonium sulfate chamber 4d is formed between the third CEM63 and the second AEM82. A sodium sulfate chamber 4e is formed between the second AEM82 and the fourth CEM64. An alkali chamber 4f is formed between the fourth CEM64 and BPM91.

[0070] In the second circulating liquid system, the second electrode liquid circulation system is formed by connecting the second electrode liquid tank 411 and the fourth circulation pump 54 to the second electrode chamber 4a to form a circulation loop; the acid liquid circulation system is formed by connecting the acid liquid tank 412 and the fifth circulation pump 55 to the acid chamber 4b to form a circulation loop; the ammonium chloride circulation system is formed by connecting the ammonium chloride water tank 413 and the sixth circulation pump 56 to the ammonium chloride chamber 4c to form a circulation loop; the ammonium sulfate circulation system is formed by connecting the ammonium sulfate water tank 414 and the seventh circulation pump 57 to the ammonium sulfate chamber 4d to form a circulation loop; the sodium sulfate circulation system is formed by connecting the sodium sulfate water tank 415 and the eighth circulation pump 58 to the sodium sulfate chamber 4e to form a circulation loop; and the alkali liquid circulation system is formed by connecting the alkali liquid tank 416 and the ninth circulation pump 59 to the alkali chamber 4f to form a circulation loop. During operation, the sodium sulfate tank 415 contains a sodium sulfate solution with a concentration of 1.0 to 2.5 mol / L produced by the selective separation unit 1, the ammonium chloride tank 413 contains an ammonium chloride solution with a concentration of 1.0 to 2.5 mol / L produced by the dual electrodisplacement unit 3, the acid tank 412, the ammonium sulfate tank 414 and the alkali tank 416 initially contain pure water, and the second electrode tank 411 contains an electrolyte solution with a concentration of 0.05 to 0.1 mol / L.

[0071] The second power supply 41 applies a DC voltage of 5 to 50 V to the second anode plate 112 and the second cathode plate 102. Under the condition that the fourth circulation pump 54 to the ninth circulation pump 59 drive the circulation of each liquid path at a flow rate of 1000 to 10000 mL / min, the interface layer of BPM91 undergoes water dissociation under reverse bias, continuously supplying H⁺ to the acid chamber 4b and continuously supplying OH⁻ to the alkali chamber 4f. - The Cl in ammonium chloride chamber 4c - Migration through the first AEM81 into acid chamber 4b with H + Combine to form hydrochloric acid, NH4 + The SO42-dioxide migrates through the third CEM63 into the ammonium sulfate chamber 4d. SO42-dioxide is present in the sodium sulfate chamber 4e. 2- Migration through the second AEM82 into the ammonium sulfate chamber 4d with NH4 + Combine to form ammonium sulfate, Na + The gas migrates through the fourth CEM64 into the alkali chamber 4f and combines with OH⁻ to generate sodium hydroxide. After continuous circulation, the liquid in the acid tank 412 is converted from pure water to a hydrochloric acid solution with a concentration of 0.9 mol / L or higher; the liquid in the ammonium sulfate tank 414 is converted from pure water to an ammonium sulfate solution with a concentration of 1.0 mol / L or higher and a purity of not less than 97%; and the liquid in the alkali tank 416 is converted from pure water to a sodium hydroxide solution with a concentration of 0.9 mol / L or higher. The second electrode liquid circulation system removes the hydrogen and oxygen generated by the electrode reaction, as well as the Joule heat, from the membrane stack, maintaining the membrane stack temperature within the range of 20 to 40°C. The current efficiency can reach over 80%, and the residual chloride ion content in the ammonium sulfate product is extremely low, which can directly meet the application requirements of chlorine-sensitive crops.

[0072] Example 2: Reference Figure 1 , Figure 11As shown, this embodiment provides a micro / nano bubble generator for converting ammonia and carbon dioxide in industrial waste gas into ammonium carbonate solution. This device can serve as a gas-liquid mixing and conversion unit in a multi-stage electrically driven membrane system. The micro / nano bubble generator includes a bubble generating tank 21, a gas compressor 22, a gas release device 23, and a control box 25. The bubble generating tank 21 contains a reaction aqueous phase and has a water inlet pipe 21a and an air inlet 21b at its bottom, and a bubble collector 21c at its top. The water inlet pipe 21a contains a water pump 21d and a filter screen 21e. The filter screen 21e includes a suspended solids filter and an activated carbon adsorption membrane, used to pre-treat the pure water entering the tank to remove suspended particles and trace organic matter. The bubble collector 21c is connected to an output pipe 21f. The output pipe 21f is equipped with a bubble check valve 21g and a bubble solenoid valve 21h, whereby the bubble check valve 21g is used to prevent the ammonium carbonate solution from flowing back, and the bubble solenoid valve 21h is used to control the output timing. A suspended liquid level sensor 21i is provided on the side wall of the bubble collector 21c, which is used to monitor the liquid level in the tank in real time and transmit the signal back to the control box 25 to realize the automatic control of the start and stop of the water pump 21d to maintain the stability of the liquid level in the tank.

[0073] The gas compressor 22 is equipped with an ammonia pipeline 22a and a carbon dioxide pipeline 22b, used to introduce separated or pretreated NH3 and CO2 gases from industrial waste gas, respectively. A first regulating valve 221 is installed on the ammonia pipeline 22a, and a second regulating valve 222 is installed on the carbon dioxide pipeline 22b. A non-dispersive infrared gas sensor 22e is installed on the gas delivery pipe 23a to monitor the molar ratio of NH3 to CO2 in the mixed gas in real time. The first regulating valve 221, the second regulating valve 222, and the non-dispersive infrared gas sensor 22e are all electrically connected to the control box 25. The control box 25 has a built-in programmable logic controller (PLC) that compares the measured molar ratio fed back by the non-dispersive infrared gas sensor 22e with a preset target molar ratio, dynamically adjusting the opening of the first regulating valve 221 and the second regulating valve 222 to achieve closed-loop precise control of the gas ratio. The preset target molar ratio is NH3 to CO2 molar ratio 2:1, and the control accuracy ensures that the deviation between the actual molar ratio and the target molar ratio does not exceed ±3%. Gas compressor 22 is used to compress the proportionally mixed gas to a predetermined pressure to form primary microbubbles.

[0074] It should be noted that the multi-channel nondispersive infrared gas sensor 22e of this patent includes dual-channel narrowband filters, which correspond to the characteristic absorption peaks of ammonia (center wavelength approximately 10.3 μm) and carbon dioxide (center wavelength approximately 4.26 μm), respectively. The bandwidth of the filters is configured such that, under preset process conditions, the optical cross-interference between the two channels is lower than a predetermined threshold. In a more preferred manner, the built-in signal processing unit of the sensor is configured to execute a cross-interference compensation algorithm (refer to the prior art CN117871450A) to minimize the impact of cross-interference, thereby enabling the monitoring of the molar ratio to achieve an accuracy of not less than ±3%.

[0075] The inlet of the gas release device 23 is connected to the gas compressor 22 via a gas delivery pipe 23a, and the outlet pipe 23c extends to the bottom of the bubble generator 21. The gas release device 23 has a gas-liquid phase space 23b, which is connected to an external vacuum pump 24. The vacuum pump 24 is used to create a semi-vacuum environment in the gas-liquid phase space 23b. After the primary bubble mixture, pressurized by the gas compressor 22, enters the gas release device 23, it undergoes rapid expansion and turbulent shearing under semi-vacuum conditions in the gas-liquid phase space 23b, further breaking the primary bubbles into micro- and nano-sized bubbles. The outer shell of the gas release device 23 is equipped with a jacketed heat exchanger, which is connected to an external constant-temperature circulating water system to maintain the internal temperature of the gas release device 23 within a preset range of 30 to 40 °C, preferably 35 °C in this embodiment. This temperature control effectively suppresses the risk of low-temperature crystallization and precipitation of ammonium bicarbonate inside the gas release device 23. Meanwhile, the gas-liquid phase surface 23b of the gas release device 23 and the inner wall of the gas delivery pipe 23a in contact with the mixed gas are both coated with a hydrophobic anti-crystallization coating. This coating is a polytetrafluoroethylene nano-coating, which further reduces the probability of ammonium bicarbonate crystals adhering to and scaling on the surface of key flow components. The broken micro- and nano-sized bubbles are released from the bottom of the bubble generator 21 through the gas outlet pipe 23c and are uniformly dispersed in the aqueous phase. The average particle size of the generated micro- and nano-sized bubbles is mainly distributed between 100 nm and 50 μm. Due to their small size, large specific surface area, and high internal pressure characteristics, the micro- and nano-sized bubbles rise extremely slowly in water, and their residence time is significantly prolonged.

[0076] During operation, the target NH3 to CO2 molar ratio is first set to 2:1 via control box 25, and the inlet flow rate and G / L ratio (total inlet air volume to pure water volume ratio) are set within the preferred range. The inlet water pump 21d is started, and pure water enters the bubble generator 21 after pretreatment via inlet pipe 21a and filter screen 21e. When the suspension level sensor 21i detects that the liquid level has reached the preset height, control box 25 shuts off the inlet water pump 21d. The gas compressor 22 is started, and the first regulating valve 221 and the second regulating valve 222 are opened. The non-dispersive infrared gas sensor 22e monitors the concentrations of NH3 and CO2 in the mixed gas in real time and calculates the molar ratio. Control box 25 dynamically adjusts the opening of the first regulating valve 221 and the second regulating valve 222 according to the deviation between the measured value and the target value, stabilizing the molar ratio of the mixed gas near the target value. After being pressurized by the gas compressor 22, the mixed gas forms primary bubbles and enters the gas release device 23. The vacuum pump 24 maintains a semi-vacuum state in region 23b between the gas and liquid phases, where primary bubbles rapidly expand and are broken down into micro- and nano-sized bubbles by turbulent shearing. A jacketed heat exchanger maintains the internal temperature of the gas release device 23 at a preset temperature, and the anti-crystallization effect of the polytetrafluoroethylene nanocoating ensures no ammonium bicarbonate solids precipitate inside the gas release device 23. The micro- and nano-sized bubbles are released from the bottom of the bubble generator 21 through the outlet pipe 23c, slowly passing through the aqueous phase from bottom to top. NH3 and CO2 in the bubbles continuously transfer mass to the aqueous phase via molecular diffusion, undergoing a chemical reaction: 2NH3 + CO2 + H2O = (NH4)2CO3. Due to the large specific surface area and extremely long residence time of the micro- and nano-sized bubbles in water, the absorption efficiency of NH3 and CO2 is significantly improved. During the reaction, the control box 25 continuously monitors the signal of the suspended liquid level sensor 21i; if the liquid level drops, the water inlet pump 21d automatically starts to replenish pure water. After a period of reaction, the aqueous phase in the bubble generating tank 21 is converted into an ammonium carbonate solution with a concentration of 1.0 to 2.0 mol / L, and no ammonium bicarbonate precipitate is formed. At this time, the control box 25 opens the bubble solenoid valve 21h on the output pipe 21f, and the ammonium carbonate solution is transported to the subsequent dual electrodisplacement unit through the bubble collector 21c and the output pipe 21f (the bubble check valve 21g prevents liquid backflow).

[0077] The micro / nano bubble generator of this embodiment can operate flexibly within the following parameter range: The control box 25 automatically adjusts the opening of the first regulating valve 221 and the second regulating valve 222 based on the molar ratio signal fed back by the non-dispersive infrared gas sensor 22e, stabilizing the molar ratio of NH3 to CO2 between 1:1 and 3:1, preferably between 2:1 and 2.5:1. When the molar ratio is below 2:1, CO2 is relatively excessive, easily generating NH4HCO3; when the molar ratio is above 3:1, NH3 is excessive, causing ammonia escape and affecting product purity. The 2:1 molar ratio used in this embodiment is the ideal stoichiometric ratio for generating (NH4)2CO3, maximizing the target product yield and suppressing side reactions. Through the synergistic effect of the above structure and process, the micro-nano bubble generator provided in this embodiment achieves efficient capture and directional conversion of NH3 and CO2 in industrial waste gas, and can stably produce high-purity (NH4)2CO3 solution, providing high-quality raw materials for subsequent multi-chamber dual-electric displacement unit. Moreover, the entire process is free of secondary pollution and is suitable for the resource-based treatment of ammonia / carbon dioxide-containing industrial waste gas such as coking, synthetic ammonia, coal-fired flue gas, and chemical tail gas.

[0078] The embodiments and / or implementation methods described above are merely preferred embodiments and / or implementation methods for implementing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any way. Any person skilled in the art may make some modifications to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but these should still be regarded as the technology or embodiments that are substantially the same as the present invention. This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. An electrically driven membrane device for converting mixed salts into acid-base ammonium salts, characterized in that, include: Selective separation unit (1) is used to selectively separate sodium chloride and sodium sulfate mixed salt solutions to obtain sodium chloride solution and sodium sulfate solution respectively; The gas-liquid mixing and conversion unit (2) is used to mix a mixture of ammonia and carbon dioxide with water and break it up to generate an ammonium carbonate solution. The dual electro-displacement unit (3) is connected to the selective separation unit (1) and the gas-liquid mixing conversion unit (2) to receive the sodium chloride solution and the ammonium carbonate solution, and to perform a dual electro-displacement reaction through the selective permeability of the ion exchange membrane under the action of a DC electric field to generate sodium carbonate solution and ammonium chloride solution; The bipolar membrane electrodialysis unit (4) is connected to the selective separation unit (1) and the dual electrodisplacement unit (3) and is used to receive the sodium sulfate solution and the ammonium chloride solution and generate ammonium sulfate and corresponding acid and alkali products.

2. The electrically driven membrane device for converting mixed salts into acid-base ammonium salts according to claim 1, characterized in that, The selective separation unit (1) is a selective electrodialysis device, which includes: The first power source (11) is electrically connected to the first cathode plate (101) and the first anode plate (114). The first membrane stack is composed of several adjacent separation membrane pair units (12), each separation membrane pair unit (12) including a first CEM (61), a first ACS (71), a second CEM (62), and a second ACS (72) stacked in sequence. A first electrode chamber (1a) is provided between the first anode plate (114), the first cathode plate (101) and the first membrane stack; A freshwater chamber (1b) is formed between the first CEM (61) and the first ACS (71), and between the second CEM (62) and the second ACS (72). A concentrate chamber (1c) is formed between the first ACS (71) and the second CEM (62), and between the second ACS (72) and the first CEM (61). The first circulating fluid circuit system includes a water tank and a circulating pump that are respectively connected to each compartment.

3. The electrically driven membrane device for converting mixed salts into acid-base ammonium salts according to claim 2, characterized in that, The first circulating fluid system includes a concentrate circulation system, a desalination circulation system, and a first electrode fluid circulation system; wherein: The concentrate circulation system includes a concentrate tank (19) and a first circulation pump (51), which are connected to the concentrate chamber (1c) to form a circulation loop; The freshwater circulation system includes a freshwater tank (110) and a second circulation pump (52), which are connected to the freshwater chamber (1b) to form a circulation loop; The first polar liquid circulation system includes a first polar liquid tank (111) and a third circulation pump (53), which are connected to the first polar chamber (1a) to form a circulation loop.

4. The electrically driven membrane device for converting mixed salts into acid-base ammonium salts according to claim 1, characterized in that, The bipolar membrane electrodialysis unit (4) is a bipolar membrane electrodialysis device, which includes: The second power source (41) is electrically connected to the second anode plate (112) and the second cathode plate (102). The second membrane stack is composed of several adjacent electrodialysis membrane pair units (42), each electrodialysis membrane pair unit (42) including BPM (91), first AEM (81), third CEM (63), second AEM (82) and fourth CEM (64) stacked in sequence. A second electrode chamber (4a) is formed between the second anode plate (112), the second cathode plate (102) and the second membrane stack. An acid chamber (4b) is formed between the BPM (91) and the first AEM (81). An ammonium chloride chamber (4c) is formed between the first AEM (81) and the third CEM (63). An ammonium sulfate chamber (4d) is formed between the third CEM (63) and the second AEM (82); A sodium sulfate chamber (4e) is formed between the second AEM (82) and the fourth CEM (64); An alkaline chamber (4f) is formed between the fourth CEM (64) and BPM (91). The second circulating fluid circuit system includes water tanks and circulating pumps that are respectively connected to each compartment.

5. The electrically driven membrane device for converting mixed salts into acid-base ammonium salts according to claim 4, characterized in that, The second circulating liquid system includes a second electrode liquid circulating system, an acid circulating system, an ammonium chloride circulating system, an ammonium sulfate circulating system, a sodium sulfate circulating system, and an alkali circulating system; wherein: The second polar liquid circulation system includes a second polar liquid tank (411) and a fourth circulation pump (54), which are connected to the second polar chamber (4a) to form a circulation loop; The acid circulation system includes an acid tank (412) and a fifth circulation pump (55), which are connected to the acid chamber (4b) to form a circulation loop; The ammonium chloride circulation system includes an ammonium chloride tank (413) and a sixth circulation pump (56), which are connected to the ammonium chloride chamber (4c) to form a circulation loop; The ammonium sulfate circulation system includes an ammonium sulfate tank (414) and a seventh circulation pump (57), which are connected to the ammonium sulfate chamber (4d) to form a circulation loop; The sodium sulfate circulation system includes a sodium sulfate tank (415) and an eighth circulation pump (58), which are connected to the sodium sulfate chamber (4e) to form a circulation loop; The alkali circulation system includes an alkali tank (416) and a ninth circulation pump (59), which are connected to the alkali chamber (4f) to form a circulation loop.

6. The electrically driven membrane device for converting mixed salts into acid-base ammonium salts according to claim 1, characterized in that, The dual electro-displacement unit (3) is a dual electrodialysis device, comprising: The third power source (31) is electrically connected to the third cathode plate (103) and the third anode plate (113). The third membrane stack comprises several adjacent electrodisplacement membrane pair units (32), wherein the electrodisplacement membrane pair unit (32) includes a third AEM (83), a fifth CEM (65), a fourth AEM (84), and a sixth CEM (66) stacked sequentially. A third electrode chamber (3e) is provided between the third cathode plate (103), the third anode plate (113) and the third membrane stack. A first product chamber (3a) is formed between the third AEM (83) and the fifth CEM (65). A first raw material chamber (3b) is formed between the fifth CEM (65) and the fourth AEM (84); A second product chamber (3c) is formed between the fourth AEM (84) and the sixth CEM (66). A second raw material chamber (3d) is formed between the sixth CEM (66) and the third AEM (83); The third circulating fluid circuit system includes water tanks and circulating pumps that are respectively connected to each compartment.

7. The electrically driven membrane device for converting mixed salts into acid-base ammonium salts according to claim 6, characterized in that, The third circulating liquid system includes a third polar liquid circulating system, a first product liquid circulating system, a first raw material liquid circulating system, a second product liquid circulating system, and a second raw material liquid circulating system; wherein: The third electrode liquid circulation system includes a third electrode liquid tank (311) and a tenth circulation pump (510), which are connected to the third electrode chamber (3e) to form a circulation loop; The first product liquid circulation system includes a first product water tank (312) and an eleventh circulation pump (511), which are connected to the first product chamber (3a) to form a circulation loop; The first raw material liquid circulation system includes a first raw material water tank (313) and a twelfth circulation pump (512), which are connected to the first raw material chamber (3b) to form a circulation loop; The second product liquid circulation system includes a second product water tank (314) and a thirteenth circulation pump (513), which are connected to the second product chamber (3c) to form a circulation loop; The second raw material liquid circulation system includes a second raw material water tank (315) and a fourteenth circulation pump (514), which are connected to the second raw material chamber (3d) to form a circulation loop.

8. The electrically driven membrane device for converting mixed salts into acid-base ammonium salts according to claim 1, characterized in that, The gas-liquid mixing and conversion unit (2) is a micro / nano bubble generator, comprising: A bubble generator (21) contains a reaction aqueous phase, and is provided with a water inlet pipe (21a) and an air inlet (21b) at the bottom and a bubble collector (21c) at the top. Gas compressor (22) for compressing gas into microbubbles; The gas release device (23) has its inlet end connected to the gas compressor (22) through the gas delivery pipe (23a) and extends to the bottom of the bubble generator (21) through the outlet pipe (23c). The gas release device (23) is provided with a gas phase and liquid phase chamber (23b). The gas release device (23) is connected to an external vacuum pump (24). The control box (25) has a built-in regulating valve, which is located on the gas outlet pipe (23c). The control box (25) is electrically connected to the gas compressor (22) and the gas release device (23).

9. The electrically driven membrane device for converting mixed salts into acid-base ammonium salts according to claim 8, characterized in that, The gas release device (23) has a hydrophobic anti-crystallization coating on the inner wall of the chamber between the gas phase and the liquid phase (23b) and the inner wall of the gas delivery pipe (23a) in contact with the mixed gas. The outer shell of the gas release device (23) is equipped with a jacketed heat exchanger.

10. The electrically driven membrane device for converting mixed salts into acid-base ammonium salts according to claim 8, characterized in that, The gas compressor (22) has an ammonia pipeline (22a) and a carbon dioxide pipeline (22b) at its inlet. The ammonia pipeline (22a) is equipped with a first regulating valve (221), and the carbon dioxide pipeline (22b) is equipped with a second regulating valve (222). The gas delivery pipe (23a) is equipped with a non-dispersive infrared gas sensor (22e). The non-dispersive infrared gas sensor (22e) monitors the molar ratio of ammonia and carbon dioxide in the mixed gas in real time. The first regulating valve (221), the second regulating valve (222), the non-dispersive infrared gas sensor (22e), and the control box (25) are electrically connected. The control box (25) compares the measured molar ratio fed back by the non-dispersive infrared gas sensor (22e) with the preset target molar ratio and dynamically adjusts the opening of the first regulating valve (221) and the second regulating valve (222).

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