A skid-mounted micro-interface reinforced double-electrode displacement device for preparing alkylammonium by mixed salt

Abstract

This invention relates to the field of waste salt resource utilization and industrial waste gas treatment technology, and provides a skid-mounted micro-interface enhanced dual electro-displacement device for preparing ammonium alkali from mixed salts. The invention includes a selective electrodialysis unit, a micro / nano bubble generator unit, and at least two sets of parallel multi-chamber dual electro-displacement units. The selective electrodialysis unit separates a mixed salt solution of sodium chloride and sodium sulfate into sodium chloride and sodium sulfate stock solutions. This device integrates selective electrodialysis, the micro / nano bubble generator, and the dual electro-displacement unit in a skid-mounted configuration, forming an integrated continuous flow reaction system. This device achieves efficient and synergistic resource conversion of industrial waste salt and waste gas, producing sodium carbonate and ammonium salts with high purity that meet national standards. Furthermore, the process is energy-saving, environmentally friendly, and produces no secondary pollution.

Description

Technical Field

[0001] This invention relates to the field of waste salt resource utilization and industrial waste gas treatment technology, and provides a skid-mounted micro-interface enhanced dual electro-displacement device for preparing ammonium alkali by mixing salts. Background Technology

[0002] Industries such as coal chemical, pharmaceutical, pesticide, and fine chemical production generate large amounts of industrial waste salt during their processes. This waste salt, primarily a mixture of sodium chloride and sodium sulfate, is also known as mixed salt. Simultaneously, these industries emit significant amounts of industrial waste gas containing carbon dioxide and ammonia. For a long time, the treatment and resource utilization of this waste salt and waste gas have been major challenges hindering the green development of these industries. Currently, traditional disposal methods for mixed sodium chloride and sodium sulfate waste salt mainly include open-air stockpiling, landfilling, or high-temperature incineration. These methods not only occupy substantial land resources, but also allow soluble salts in the waste salt to seep into the soil and groundwater with rainwater, posing serious environmental risks. Some companies have attempted to recover individual salts from the mixed salt using evaporation crystallization or nanofiltration separation technologies. However, due to the complex composition and high impurity content of the mixed salt, the separation efficiency is low, energy consumption is high, and the purity of the recovered salt is difficult to meet industrial-grade requirements, resulting in a still low resource utilization rate. Existing technologies lack an integrated device capable of efficiently and cost-effectively converting mixed salt into high-value-added products. The prior art CN112850747A, published on May 28, 2021, provides a method and apparatus for preparing ammonium sulfate and sodium bicarbonate from sodium sulfate and ammonium bicarbonate. The method includes pretreatment of sodium sulfate stock solution and ammonium bicarbonate stock solution, allowing sodium sulfate and ammonium bicarbonate to pass through an electrodialysis unit set in an electric field. Sodium ions and sulfate ions in the sodium sulfate stock solution and ammonium ions and bicarbonate ions in the ammonium bicarbonate stock solution recombine to form ammonium sulfate solution and sodium bicarbonate solution. The ammonium sulfate solution and sodium bicarbonate solution are then discharged into an evaporation crystallization unit to obtain ammonium sulfate crystals and sodium bicarbonate crystals. Summary of the Invention

[0003] This invention achieves efficient and synergistic resource-based conversion of industrial waste salt and waste gas. The products, sodium carbonate and ammonium salt, have high purity and meet national standards. Moreover, the process is energy-saving, environmentally friendly, and produces no secondary pollution.

[0004] A skid-mounted micro-interface enhanced dual electro-exchange device for preparing ammonium carbonate from mixed salts includes a selective electrodialysis unit, a micro / nano bubble generator unit, and at least two sets of parallel multi-chamber dual electro-exchange units. The selective electrodialysis unit separates a mixed salt solution of sodium chloride and sodium sulfate into sodium chloride and sodium sulfate stock solutions. This device integrates the selective electrodialysis unit, the micro / nano bubble generator, and the dual electro-exchange unit in a skid-mounted configuration, forming an integrated continuous flow reaction system. First, industrial waste salt, mainly composed of a mixed salt solution of sodium chloride and sodium sulfate, enters the selective electrodialysis unit. Under the influence of an electric field, monovalent sodium ions are separated from chloride ions and divalent sulfate ions using monovalent and divalent selective ion exchange membranes, yielding sodium chloride and sodium sulfate stock solutions respectively. Simultaneously, industrial waste gas, mainly composed of ammonia and carbon dioxide, is mixed in a specific ratio and enters the micro / nano bubble generator. Through a Venturi jet and cavitation shearing action, a large number of micro / nano-sized bubbles are formed and uniformly dispersed in the aqueous phase, increasing the gas-liquid contact area and dissolution rate, rapidly generating an ammonium carbonate aqueous solution. Subsequently, two parallel dual-displacement units were introduced into ammonium carbonate and sodium chloride stock solutions and ammonium carbonate and sodium sulfate stock solutions, respectively. Under the drive of a DC electric field, ions migrated in a directional manner and underwent a dual displacement reaction, generating sodium carbonate and ammonium chloride, and sodium carbonate and ammonium sulfate, respectively.

[0005] The multi-chamber dual-electro-displacement unit further includes at least two product chambers and at least two raw material chambers. The product chambers include a first product chamber and a second product chamber, and the raw material chambers include a first raw material chamber and a second raw material chamber. In one multi-chamber dual-electro-displacement unit, an ammonium carbonate aqueous solution is introduced into the first raw material chamber, and a sodium chloride stock solution is introduced into the second raw material chamber to generate sodium carbonate and ammonium chloride. In another multi-chamber dual-electro-displacement unit, an ammonium carbonate aqueous solution is introduced into the first raw material chamber, and a sodium sulfate stock solution is introduced into the second raw material chamber to generate sodium carbonate and ammonium sulfate.

[0006] This integrated device achieves the synergistic resource conversion of waste salt and waste gas. The micro-interface enhancement significantly improves the gas-liquid mass transfer efficiency. The electro-displacement process does not require the addition of external chemical reagents, avoiding secondary pollution. The final products, sodium carbonate and ammonium salt, have high purity and meet industrial or agricultural standards. The sodium carbonate product can meet or be further purified to meet the first-grade technical indicators of "GB / T210-2022 Industrial Sodium Carbonate". The ammonium salt product meets the agricultural grade standards of "GB / T2946-2018 Ammonium Chloride" and "GB / T 535-2020 Fertilizer Grade Ammonium Sulfate".

[0007] Preferably, the total concentration of sodium chloride and sodium sulfate in the mixed salt solution is 1.0–2.5 mol / L. The concentration of the mixed salt solution directly affects the separation efficiency and energy consumption of selective electrodialysis. If the mixed salt concentration is too low, the ion migration flux is small, resulting in low separation efficiency; if the mixed salt concentration is too high, it may lead to increased concentration polarization of the electrodialysis membrane stack and an increased risk of membrane fouling. A concentration range of 1.0–2.5 mol / L can ensure sufficient ion migration flux while controlling the degree of concentration polarization on the membrane surface, maintaining stable current efficiency and separation selectivity. This concentration range also facilitates the matching of ion migration and reaction rates in subsequent electro-displacement units.

[0008] The selective electrodialysis unit can achieve efficient separation of sodium chloride and sodium sulfate with low energy consumption, improving the purity of the sodium chloride stock solution and ensuring stable sodium sulfate recovery. Simultaneously, appropriate concentrations can extend the lifespan of the ion exchange membrane, reduce membrane cleaning frequency, and enhance the stability of continuous system operation.

[0009] Preferably, the selective electrodialysis unit includes an electrodialysis power supply and an electrodialysis membrane stack. The electrodialysis membrane stack includes 4 to 30 electrodialysis exchange membranes. The voltage of the electrodialysis membrane stack is 5 to 50 V, the solution flow rate in the electrodialysis membrane stack is 1000 to 10000 mL / min, and the operating temperature is 20 to 40 °C.

[0010] The voltage of the electrodialysis membrane stack should be controlled between 5 and 50 V. Too low a voltage results in insufficient electric field force driving ion migration, leading to low separation efficiency; too high a voltage intensifies water decomposition, increases energy consumption, and may damage the membrane material. Adjusting the solution flow rate within the range of 1000–10000 mL / min allows for adjustment of the membrane boundary layer thickness, suppressing concentration polarization and improving ion migration rates. Maintaining the temperature between 20 and 40 °C reduces solution viscosity, increases the ion diffusion coefficient and membrane conductivity, and promotes selective ion migration. Optimized operating parameter combinations can significantly improve the separation efficiency and stability of selective electrodialysis. Temperature control also avoids low-temperature crystallization or high-temperature membrane degradation, extending the system's operating cycle.

[0011] Preferably, the selective electrodialysis unit also includes an electrode chamber water tank, in which the electrode solution is one of sodium sulfate, sodium chloride, or sodium nitrate solution, with a concentration of 0.01–0.5 mol / L. The selection of a sodium sulfate, sodium chloride, or sodium nitrate solution with a concentration of 0.01–0.5 mol / L is to maintain the stability of the electrode reaction and avoid the generation of large amounts of gas or drastic pH fluctuations.

[0012] The electrodialysis exchange membrane divides the electrodialysis membrane stack into at least six compartments. The membrane resistance of the electrodialysis exchange membrane is less than 10 Ω·cm², the exchange capacity is ≥1.3 mol / kg, and it is resistant to acids and alkalis with a pH range of 2–10. A membrane resistance below 10 Ω·cm² reduces ohmic voltage drop and improves current efficiency; an exchange capacity ≥1.3 mol / kg ensures good ion conductivity; and resistance to acids and alkalis with a pH range of 2–10 gives the electrodialysis exchange membrane adaptability to different process conditions, especially when using monovalent or divalent selective ion exchange membranes, maintaining long-term separation performance.

[0013] Preferably, the selective electrodialysis unit also includes a concentrate tank and a dilute tank. The concentrate tank contains a sodium chloride solution, and the dilute tank contains a mixed solution of sodium chloride and sodium sulfate. The electrode tank, concentrate tank, and dilute tank are connected to their respective compartments in the electrodialysis membrane stack to form corresponding circulations. The circulation of concentrate and dilute water continuously carries away ion migration products from the membrane surface, thereby maintaining the concentration gradient across the membrane and promoting continuous ion migration. Before the reaction begins, pure water is added to both the concentrate and dilute tanks to ensure that no impurities interfere with the separation process initially; the electrode circulation can promptly remove the gases and heat generated by the electrode reaction, maintaining electrode stability.

[0014] Preferably, the micro / nano bubble generating unit includes a Venturi jet injector; the inlet flow rate of the micro / nano bubble generating unit is 0.1–5.0 L / min, the operating temperature is 15–40 °C, the water pressure before the Venturi jet injector is 0.2–0.6 MPa, and the average particle size distribution of the micro / nano bubbles generated by the micro / nano bubble generating unit is between 100 nm and 50 μm, of which nano-sized bubbles with a particle size <1 μm account for no less than 30%. Micro / nano bubbles possess extremely high specific surface area and internal pressurization characteristics, which can significantly improve the dissolution rate and reaction rate of ammonia and carbon dioxide in water, rapidly generating ammonium carbonate. High concentrations of micro / nano bubbles can also inhibit the formation of ammonium bicarbonate, improving product purity.

[0015] Preferably, in the mixed gas containing ammonia and carbon dioxide, the molar ratio of ammonia to carbon dioxide is 1:1 to 3:1; the total volume ratio of the inlet gas to pure water in the micro / nano bubble generating unit is controlled at 5% to 20%, and the concentration of the generated ammonium carbonate aqueous solution is 1.0 to 2.0 mol / L. Controlling the molar ratio of ammonia to carbon dioxide in the mixed gas to 1:1 to 3:1, preferably 2.0:1 to 2.5:1, ensures that the reaction mainly produces ammonium carbonate rather than ammonium bicarbonate. Controlling the total volume ratio of the inlet gas to pure water to 5% to 20% allows adjustment of bubble density and reaction degree, stabilizing the ammonium carbonate concentration at 1.0 to 2.0 mol / L. Too low a ratio results in incomplete reaction, while too high a ratio easily leads to precipitation or bubble aggregation.

[0016] Preferably, the multi-chamber dual electro-displacement unit includes an electro-displacement power source and an electro-displacement membrane stack. The electro-displacement membrane stack includes 4 to 30 electro-displacement exchange membranes. The voltage of the electro-displacement membrane stack is 5 to 50 V, the solution flow rate in the electro-displacement membrane stack is 1000 to 10000 mL / min, and the operating temperature is 20 to 40 °C.

[0017] Preferably, the multi-chamber dual electro-exchange unit further includes an electrode chamber and an electro-exchange membrane. The electrode liquid in the electrode chamber is one of sodium sulfate, sodium chloride, or sodium nitrate solution, with a concentration of 0.01–0.5 mol / L. The electro-exchange membrane has a membrane resistance of less than 10 Ω·cm², an exchange capacity of ≥1.3 mol / kg, and an acid and alkali resistance pH of 2–10.

[0018] Preferably, the multi-chamber dual electro-displacement unit also includes at least two product chambers and at least two feed chambers. Each feed chamber and product chamber is connected to a corresponding compartment of the electro-displacement membrane stack to form a corresponding cycle. Before electro-displacement begins, the product chamber contains pure water. Before electro-displacement begins, pure water is added to each product chamber to ensure that ion migration has a clear receiving medium in the initial stage of the reaction, avoiding cross-contamination of products. An aqueous solution of ammonium carbonate is introduced into the first feed chamber, and a stock solution of sodium chloride or sodium sulfate is introduced into the second feed chamber. Under the action of an electric field, sodium ions and carbonate ions migrate to the first product chamber to form sodium carbonate, while ammonium ions and chloride or sulfate ions migrate to the second product chamber to form the corresponding ammonium salt.

[0019] This invention has the following significant advantages: Selective electrodialysis, under optimized voltage, flow rate, and temperature conditions, can efficiently separate mixed salts into high-purity sodium chloride and sodium sulfate stock solutions, resulting in low separation energy consumption and long membrane life. The micro / nano bubble generation unit utilizes Venturi jet and cavitation shearing to generate a large number of micro / nano-sized bubbles, increasing the gas-liquid contact area and dissolution rate, enabling ammonia and carbon dioxide to react rapidly to generate a 1.0–2.0 mol / L ammonium carbonate aqueous solution, while effectively inhibiting the formation of ammonium bicarbonate. Two parallel dual electro-displacement units, using ammonium carbonate and sodium chloride, and ammonium carbonate and sodium sulfate as raw materials respectively, undergo dual ion displacement under a DC electric field, eliminating the need for external chemical reagents. High-purity sodium carbonate, ammonium chloride, and ammonium sulfate are obtained in the product chamber. Attached Figure Description

[0020] 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 in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0021] Figure 1 This is a process flow diagram of the present invention.

[0022] Figure 2 This is a schematic diagram of the selective electrodialysis structure of the present invention.

[0023] Figure 3 This is a schematic diagram illustrating the principle of selective electrodialysis according to the present invention.

[0024] Figure 4 This is a schematic diagram of the dual electrodisplacement structure of the present invention.

[0025] Figure 5 This is a schematic diagram illustrating the principle of the dual electrodisplacement of the present invention.

[0026] Legend: 1. Electrodialysis power supply; 2. Electrodialysis membrane stack; 21. Electrodialysis cathode plate; 22. Electrodialysis first cation membrane; 23. Electrodialysis first anion membrane; 24. Electrodialysis second cation membrane; 25. Electrodialysis second anion membrane; 26. Electrodialysis third cation membrane; 27. Electrodialysis anode plate; 28. Dilute chamber water tank; 29. ​​Concentrate chamber water tank; 210. Electrode chamber water tank; 211. Cathode chamber; 212. Anode chamber; 213. Concentrate chamber; 214. Dilute chamber; 3. Electrodisplacement membrane stack; 31. Electrodisplacement cathode plate; 32. Electrodisplacement first anion membrane; 33. Electrodisplacement first cation membrane; 34. Electrodisplacement second anion membrane; 35. Electrodisplacement second cation membrane; 36. Electrodisplacement third anion membrane; 37. Electrodisplacement anode plate; 38. Electrolyte chamber; 39. First product chamber; 310. First raw material chamber; 311. Second product chamber; 312. Second raw material chamber; 4. Electrodisplacement power supply. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0028] like Figure 1 As shown, a skid-mounted micro-interface enhanced dual electro-displacement device for preparing ammonium alkali from mixed salts includes a selective electrodialysis unit, a micro / nano bubble generating unit, and at least two sets of parallel multi-chamber dual electro-displacement units. The selective electrodialysis unit is used to separate the mixed salt solution of sodium chloride and sodium sulfate into a sodium chloride stock solution and a sodium sulfate stock solution. This device integrates the selective electrodialysis, micro / nano bubble generator, and dual electro-displacement unit in a skid-mounted configuration to form an integrated continuous flow reaction system.

[0029] First, industrial waste salt, mainly composed of a mixed salt solution of sodium chloride and sodium sulfate, enters a selective electrodialysis unit. Under the influence of an electric field, monovalent sodium ions are separated from chloride ions and divalent sulfate ions using monovalent and divalent selective ion exchange membranes, yielding sodium chloride and sodium sulfate stock solutions, respectively. Simultaneously, industrial waste gas, mainly composed of ammonia and carbon dioxide, is mixed in a specific ratio and enters a micro / nano bubble generator. Through a Venturi jet and cavitation shearing action, a large number of micro / nano-sized bubbles are formed and uniformly dispersed in the aqueous phase, increasing the gas-liquid contact area and dissolution rate, rapidly generating an ammonium carbonate aqueous solution. Subsequently, two parallel dual electro-displacement units are introduced with ammonium carbonate and sodium chloride stock solutions, and ammonium carbonate and sodium sulfate stock solutions, respectively. Driven by a DC electric field, ions migrate directionally and undergo dual displacement reactions, generating sodium carbonate and ammonium chloride, and sodium carbonate and ammonium sulfate, respectively.

[0030] like Figure 2 and Figure 3 As shown, the selective electrodialysis unit includes an electrodialysis power supply 1 and an electrodialysis membrane stack 2. The electrodialysis membrane stack 2 includes 4 to 30 electrodialysis exchange membranes. The voltage of the electrodialysis membrane stack 2 is 5 to 50 V, the solution flow rate in the electrodialysis membrane stack 2 is 1000 to 10000 mL / min, and the operating temperature is 20 to 40 °C.

[0031] The voltage of the electrodialysis membrane stack 2 is controlled between 5 and 50 V. Too low a voltage results in insufficient electric field force driving ion migration, leading to low separation efficiency; too high a voltage intensifies water decomposition, increases energy consumption, and may damage the membrane material. The solution flow rate, within the range of 1000–10000 mL / min, can adjust the membrane boundary layer thickness, suppress concentration polarization, and improve ion migration rate. Temperature control within the range of 20–40 °C reduces solution viscosity, increases the ion diffusion coefficient and membrane conductivity, and promotes selective ion migration. The optimized combination of operating parameters significantly improves the separation efficiency and stability of selective electrodialysis. Temperature control also avoids low-temperature crystallization or high-temperature membrane degradation, extending the system's operating cycle.

[0032] The selective electrodialysis unit also includes an electrode chamber water tank 210. The electrode solution in the electrode chamber water tank 210 is one of sodium sulfate, sodium chloride, or sodium nitrate solution, and the concentration of the electrode solution is 0.01 to 0.5 mol / L. The concentration of the electrode solution is selected as 0.01 to 0.5 mol / L sodium sulfate, sodium chloride, or sodium nitrate solution to maintain the stability of the electrode reaction and avoid the generation of a large amount of gas or drastic pH fluctuations.

[0033] The electrodialysis exchange membrane divides the electrodialysis membrane stack 2 into at least six compartments. The compartment between the electrodialysis cathode plate 21 and the first cation membrane 22 is the cathode compartment 211; the compartment between the first cation membrane 22 and the first anion membrane 23 is the concentration compartment 213; the compartment between the first anion membrane 23 and the second cation membrane 24 is the dilute compartment 214; the compartment between the second cation membrane 24 and the second anion membrane 25 is the concentration compartment 213; the compartment between the second anion membrane 25 and the third cation membrane 26 is the dilute compartment 214; and the compartment between the third cation membrane 26 and the anode plate 27 is the anode compartment 212. The membrane resistance of the electrodialysis exchange membrane is less than 10 Ω·cm², the exchange capacity is ≥1.3 mol / kg, and the pH value for acid and alkali resistance is 2 to 10. An electrodialysis membrane resistance of less than 10 Ω·cm² can reduce ohmic voltage drop and improve current efficiency; an exchange capacity of ≥1.3 mol / kg ensures that the electrodialysis membrane has good ion conduction capability; and acid and alkali resistance of pH 2 to 10 endows the electrodialysis membrane with adaptability to different process conditions, especially when using monovalent and divalent selective ion exchange membranes, which can maintain long-term separation performance.

[0034] The selective electrodialysis unit also includes a concentrate tank 29 and a dilute tank 28. The concentrate tank 29 contains a sodium chloride solution, and the dilute tank 28 contains a mixed solution of sodium chloride and sodium sulfate. The electrode tank 210, concentrate tank 29, and dilute tank 28 are respectively connected to their corresponding compartments in the electrodialysis membrane stack 2 to form corresponding cycles. Figure 3 As shown, the electrode tank 210 is connected via a conduit to the cathode chamber 211 and anode chamber 212 on the electrodialysis cathode plate 21 and electrodialysis anode plate 27 located at both ends of the electrodialysis membrane stack 2, so that the electrode solution flows sequentially from the electrode tank 210 into the cathode chamber 211 and anode chamber 212 and then back to the electrode tank 210; the concentrate tank 29 stores the separated sodium chloride solution, and the concentrate tank 29 is connected via a conduit to the inlet and outlet of the concentrate chamber 213 located on the front of the membrane stack, so that the concentrate flows sequentially from the concentrate tank 29 into the membrane stack and then back to the concentrate tank 29; the dilute tank 28 stores a mixed solution of sodium chloride and sodium sulfate, and the dilute tank 28 is connected via a conduit to the inlet and outlet of the dilute chamber 214 located on the front of the electrodialysis membrane stack 2, so that the mixed solution flows sequentially from the dilute tank 28 into the electrodialysis membrane stack 2 and then back to the dilute tank 28.

[0035] The circulation of concentrate and desalination water continuously removes ion migration products from the membrane surface, thus maintaining the concentration gradient across the membrane and promoting continuous ion migration. Before the reaction begins, pure water is added to both the concentrate and desalination chambers to ensure that no impurities interfere with the separation process initially; the electrode circulation can promptly remove the gases and heat generated by the electrode reaction, maintaining electrode stability.

[0036] The total concentration of sodium chloride and sodium sulfate in the mixed salt solution is 1.0–2.5 mol / L. The concentration of the mixed salt solution directly affects the separation efficiency and energy consumption of selective electrodialysis. If the mixed salt concentration is too low, the ion migration flux is small, resulting in low separation efficiency; if the mixed salt concentration is too high, it may lead to increased concentration polarization of the electrodialysis membrane stack 2 and an increased risk of membrane fouling. A concentration range of 1.0–2.5 mol / L can ensure sufficient ion migration flux while controlling the degree of concentration polarization on the membrane surface, maintaining stable current efficiency and separation selectivity. This concentration range also facilitates the matching of ion migration and reaction rates in subsequent electro-displacement units.

[0037] The selective electrodialysis unit can achieve efficient separation of sodium chloride and sodium sulfate with low energy consumption, improving the purity of the sodium chloride stock solution and ensuring stable sodium sulfate recovery. Simultaneously, appropriate concentrations can extend the lifespan of the ion exchange membrane, reduce membrane cleaning frequency, and enhance the stability of continuous system operation.

[0038] The micro / nanobubble generating unit includes a Venturi jet injector. The inlet flow rate of the unit is 0.1–5.0 L / min, the operating temperature is 15–40 °C, and the water pressure before the Venturi jet injector is 0.2–0.6 MPa. The average particle size of the micro / nanobubbles generated by the unit ranges from 100 nm to 50 μm, with nano-sized bubbles <1 μm accounting for no less than 30%. These micro / nanobubbles possess extremely high specific surface area and internal pressurization characteristics, significantly enhancing the dissolution and reaction rates of ammonia and carbon dioxide in water, rapidly generating ammonium carbonate. High concentrations of micro / nanobubbles can also inhibit the formation of ammonium bicarbonate, improving product purity.

[0039] In a mixed gas containing ammonia and carbon dioxide, the molar ratio of ammonia to carbon dioxide is 1:1 to 3:1. The total volume ratio of the inlet gas to pure water in the micro / nano bubble generating unit is controlled at 5% to 20%, and the concentration of the generated ammonium carbonate aqueous solution is 1.0 to 2.0 mol / L. Controlling the molar ratio of ammonia to carbon dioxide in the mixed gas to 1:1 to 3:1, preferably 2.0:1 to 2.5:1, ensures that the reaction mainly produces ammonium carbonate rather than ammonium bicarbonate. Controlling the total volume ratio of the inlet gas to pure water to 5% to 20% allows adjustment of bubble density and reaction degree, stabilizing the ammonium carbonate concentration at 1.0 to 2.0 mol / L. Too low a ratio results in incomplete reaction, while too high a ratio easily leads to precipitation or bubble aggregation.

[0040] like Figure 4 and Figure 5As shown, the multi-chamber dual-electro-displacement unit further includes at least two product chambers and at least two raw material chambers. The product chambers include a first product chamber 39 and a second product chamber 311, and the raw material chambers include a first raw material chamber 310 and a second raw material chamber 312. In one multi-chamber dual-electro-displacement unit, the first raw material chamber 310 is purged with an ammonium carbonate aqueous solution, and the second raw material chamber 312 is purged with a sodium chloride stock solution to generate sodium carbonate and ammonium chloride. In another multi-chamber dual-electro-displacement unit, the first raw material chamber 310 is purged with an ammonium carbonate aqueous solution, and the second raw material chamber 312 is purged with a sodium sulfate stock solution to generate sodium carbonate and ammonium sulfate.

[0041] The multi-chamber dual electro-displacement device sequentially includes an electrode liquid chamber 38, a first product chamber 39, a first raw material chamber 310, a second product chamber 311, and a second raw material chamber 312; the electro-displacement membrane stack 3 includes an electro-displacement cathode plate 31, an electro-displacement first anion membrane 32, an electro-displacement first cation membrane 33, an electro-displacement second anion membrane 34, an electro-displacement second cation membrane 35, an electro-displacement third anion membrane 36, and an electro-displacement anode plate 37 stacked sequentially; this integrated device realizes the synergistic resource conversion of waste salt and waste gas, the micro-interface enhancement significantly improves the gas-liquid mass transfer efficiency, the electro-displacement process does not require the addition of external chemical reagents, avoiding secondary pollution, and the final products sodium carbonate and ammonium salt have high purity, meeting industrial or agricultural standards. The sodium carbonate product can meet or be further purified to meet the first-grade technical indicators of "GB / T210-2022 Industrial Sodium Carbonate", and the ammonium salt product meets the agricultural grade standards of "GB / T2946-2018 Ammonium Chloride" and "GB / T 535-2020 Fertilizer Grade Ammonium Sulfate".

[0042] The multi-compartment dual electro-displacement unit includes an electro-displacement power source 4 and an electro-displacement membrane stack 3. The electro-displacement membrane stack 3 includes 4 to 30 electro-displacement exchange membranes. The voltage of a single electro-displacement membrane stack 3 is 5 to 50 V. The solution flow rate in the electro-displacement membrane stack 3 is 1000 to 10000 mL / min. The operating temperature is 20 to 40 °C.

[0043] The multi-chamber dual electro-exchange unit also includes an electrode chamber 38 and an electro-exchange membrane. The electrode liquid in the electrode chamber 38 is one of sodium sulfate, sodium chloride, or sodium nitrate solution, with a concentration of 0.01–0.5 mol / L. The membrane resistance of the electro-exchange membrane is less than 10 Ω·cm², the exchange capacity is ≥1.3 mol / kg, and the pH value for acid and alkali resistance is 2–10.

[0044] The multi-chamber dual electro-displacement unit also includes at least two product chambers and at least two feed chambers. Each feed chamber and product chamber is connected to a corresponding compartment of the electro-displacement membrane stack 3 to form a corresponding cycle. Before the electro-displacement begins, the product chamber is filled with pure water. Before the electro-displacement begins, pure water is added to each product chamber to ensure that there is a clear receiving medium for ion migration in the initial stage of the reaction and to avoid cross-contamination of products. An ammonium carbonate aqueous solution is introduced into the first feed chamber 310, and a sodium chloride or sodium sulfate stock solution is introduced into the second feed chamber 312, respectively.

[0045] Under the influence of an electric field, sodium ions in the first raw material chamber 310 enter the first product chamber 39 through the first cation exchange membrane 33, and chloride ions enter the second product chamber 311 through the second anion exchange membrane 34. Simultaneously, ammonium ions in the second raw material chamber 312 enter the second product chamber 311 through the second cation exchange membrane 35, and carbonate ions enter the first product chamber 39 through the third anion exchange membrane 36. This converts sodium chloride and ammonium carbonate into sodium carbonate and ammonium chloride through electro-displacement. In another set of first product chambers 39 and second product chambers 311, pure water is added. Sodium sulfate stock solution and ammonium carbonate aqueous solution are added to the first raw material chamber 310 and second raw material chamber 312, respectively. Sodium ions in the first raw material chamber 310 enter the first product chamber 39 through the first cation exchange membrane 33, and sulfate ions enter the second product chamber 311 through the second anion exchange membrane 34. Simultaneously, ammonium ions in the second raw material chamber 312 enter the second product chamber 311 through the second cation exchange membrane 35, and carbonate ions enter the first product chamber 39 through the third anion exchange membrane 36. This allows sodium sulfate and ammonium carbonate to be converted into sodium carbonate and ammonium sulfate through electro-displacement.

[0046] Example 1 The waste brine was sourced from a coal chemical plant. A 2.0 mol / L mixed solution of sodium chloride and sodium sulfate was passed into a selective electrodialysis (SEM) unit. The membrane stack voltage was set to 15V, the flow rate to 5000 mL / min, and the operating temperature to 25℃. Separation was achieved using a divalent selective ion exchange membrane, yielding a high-purity sodium chloride stock solution in the concentrate chamber and a sodium sulfate stock solution in the desalination chamber. Ammonia and carbon dioxide from industrial waste gas were mixed at a molar ratio of 2:1. This mixed gas was then passed into a micro / nano bubble generator with an inlet flow rate of 2.0 L / min and a water pressure of 0.4 MPa before the Venturi jet. The generated micro / nano bubbles had an average particle size of 10-20 μm. After enhanced gas-liquid mass transfer, a 1.5 mol / L ammonium carbonate aqueous solution was produced. Finally, two four-chamber dual electrodialysis units were connected. In one unit, ammonium carbonate was introduced into the first feed chamber 310, and the sodium chloride stock solution was introduced into the second feed chamber 312. Under a DC electric field, sodium carbonate at a concentration of 1.2 mol / L is produced in the first product chamber 39, and ammonium chloride at a concentration of 1.2 mol / L is produced in the second product chamber 311. The sodium carbonate product meets the Grade I standard of GB / T210-2022, and the ammonium chloride meets the agricultural grade standard.

[0047] Example 2 Applications include treating low-concentration waste salts and processing at specific temperatures. The treatment of a 1.0 mol / L mixed salt solution was performed. The selective electrodialysis unit's membrane stack voltage was set to 20V, and the operating temperature was increased to 40℃ to enhance ion mobility. The ammonia to carbon dioxide molar ratio was adjusted to 2.5:1, and the total inlet gas volume to pure water volume ratio was controlled at 10%. Under these conditions, the proportion of nano-sized bubbles reached 45%, ensuring extremely high absorption efficiency and preventing ammonium bicarbonate precipitation. Sodium sulfate stock solution was introduced into the second feed chamber 312 of another electro-displacement unit. After the reaction, the product chamber obtained an ammonium sulfate molar concentration of 1.8 mol / L and a sodium carbonate concentration of 1.0 mol / L.

[0048] This invention has the following significant advantages: Selective electrodialysis, under optimized voltage, flow rate, and temperature conditions, can efficiently separate mixed salts into high-purity sodium chloride and sodium sulfate stock solutions, resulting in low separation energy consumption and long membrane life. The micro / nano bubble generation unit utilizes Venturi jet and cavitation shearing to generate a large number of micro / nano-sized bubbles, increasing the gas-liquid contact area and dissolution rate, enabling ammonia and carbon dioxide to react rapidly to generate a 1.0–2.0 mol / L ammonium carbonate aqueous solution, while effectively inhibiting the formation of ammonium bicarbonate. Two parallel dual electro-displacement units, using ammonium carbonate and sodium chloride, and ammonium carbonate and sodium sulfate as raw materials respectively, undergo dual ion displacement under a DC electric field, eliminating the need for external chemical reagents. High-purity sodium carbonate, ammonium chloride, and ammonium sulfate are obtained in the product chamber.

[0049] The above embodiments and / or implementation methods are only used to illustrate preferred embodiments and / or implementation methods of the present invention, and are not intended to limit the implementation methods of the present invention in any way. Any person skilled in the art can make some modifications to form other equivalent embodiments without departing from the technical means disclosed in the present invention, but these should still be regarded as the same technology or embodiments as the present invention.

Claims

1. A skid-mounted micro-interface enhanced dual electro-displacement device for preparing ammonium alkali using mixed salts, comprising a selective electrodialysis unit, a micro / nano bubble generating unit, and at least two sets of parallel multi-chamber dual electro-displacement units, characterized in that, The selective electrodialysis unit is used to separate a mixed salt solution of sodium chloride and sodium sulfate into a sodium chloride stock solution and a sodium sulfate stock solution. The micro-nano bubble generating unit is used to shear and break a mixed gas containing ammonia and carbon dioxide into micro-nano bubbles and disperse them in an aqueous phase to generate an ammonium carbonate aqueous solution. The multi-chamber dual-electro-displacement unit further includes at least two product chambers and at least two raw material chambers. The product chambers include a first product chamber (39) and a second product chamber (311). The raw material chambers include a first raw material chamber (310) and a second raw material chamber (312). In one set of the multi-chamber dual-electro-displacement units, the first raw material chamber (310) is conditioned with the ammonium carbonate aqueous solution and the second raw material chamber (312) is conditioned with the sodium chloride stock solution to generate sodium carbonate and ammonium chloride. In another set of the multi-chamber dual-electro-displacement units, the first raw material chamber (310) is conditioned with the ammonium carbonate aqueous solution and the second raw material chamber (312) is conditioned with the sodium sulfate stock solution to generate sodium carbonate and ammonium sulfate.

2. The skid-mounted micro-interface enhanced dual electrodisplacement device for preparing ammonium alkali by mixing salts according to claim 1, characterized in that, The total concentration of sodium chloride and sodium sulfate in the mixed salt solution is 1.0–2.5 mol / L.

3. The skid-mounted micro-interface enhanced dual electrodisplacement device for preparing ammonium alkali by mixing salts according to claim 1, characterized in that, The selective electrodialysis unit includes an electrodialysis power supply (1) and an electrodialysis membrane stack (2). The electrodialysis membrane stack (2) includes 4 to 30 electrodialysis exchange membranes. The voltage of a single electrodialysis membrane stack (2) is 5 to 50 V. The solution flow rate in the electrodialysis membrane stack (2) is 1000 to 10000 mL / min, and the operating temperature is 20 to 40 °C.

4. The skid-mounted micro-interface enhanced dual electrodisplacement device for preparing ammonium alkali by mixing salts according to claim 3, characterized in that, The selective electrodialysis unit also includes an electrode chamber water tank (210), wherein the electrode solution in the electrode chamber water tank (210) is one of sodium sulfate, sodium chloride or sodium nitrate solution, and the concentration of the electrode solution is 0.01 to 0.5 mol / L; The electrodialysis exchange membrane divides the electrodialysis membrane stack (2) into at least six compartments. The membrane resistance of the electrodialysis exchange membrane is less than 10 Ω·cm², the exchange capacity is ≥1.3 mol / kg, and the pH value of the acid and alkali resistant membrane is 2 to 10.

5. The skid-mounted micro-interface enhanced dual electrodisplacement device for preparing ammonium alkali by mixing salts according to claim 4, characterized in that, The selective electrodialysis unit further includes a concentration tank (29) and a dilute tank (28). The concentration tank (29) contains a sodium chloride solution, and the dilute tank (28) contains a mixed solution of sodium chloride and sodium sulfate. The electrode tank (210), the concentration tank (29), and the dilute tank (28) are respectively connected to the corresponding compartments of the electrodialysis membrane stack (2) to form corresponding cycles.

6. The skid-mounted micro-interface enhanced dual electrodisplacement device for preparing ammonium alkali by mixing salts according to claim 1, characterized in that, The micro / nano bubble generating unit includes a Venturi jet; the air inlet flow rate of the micro / nano bubble generating unit is 0.1–5.0 L / min, the operating temperature is 15–40 °C, the water pressure before the Venturi jet is 0.2–0.6 MPa, and the average particle size of the micro / nano bubbles generated by the micro / nano bubble generating unit is distributed between 100 nm and 50 μm, of which the proportion of nano-sized bubbles with a particle size <1 μm is not less than 30%.

7. The skid-mounted micro-interface enhanced dual electrodisplacement device for preparing ammonium alkali by mixing salts according to claim 6, characterized in that, In the mixed gas containing ammonia and carbon dioxide, the molar ratio of ammonia to carbon dioxide is 1:1 to 3:1; the total gas intake of the micro-nano bubble generating unit is controlled at a volume ratio of 5% to 20% of pure water, and the concentration of the generated ammonium carbonate aqueous solution is 1.0 to 2.0 mol / L.

8. The skid-mounted micro-interface enhanced dual electrodisplacement device for preparing ammonium alkali by mixing salts according to claim 1, characterized in that, The multi-chamber dual electro-displacement unit includes an electro-displacement power supply (4) and an electro-displacement membrane stack (3). The electro-displacement membrane stack (3) includes 4 to 30 electro-displacement exchange membranes. The voltage of the electro-displacement membrane stack (3) is 5 to 50V. The solution flow rate in the electro-displacement membrane stack (3) is 1000 to 10000 mL / min. The operating temperature is 20 to 40℃.

9. The skid-mounted micro-interface enhanced dual electrodisplacement device for preparing ammonium alkali by mixing salts according to claim 8, characterized in that, The multi-chamber dual electro-displacement unit further includes an electrode chamber (38), wherein the electrode liquid in the electrode chamber (38) is one of sodium sulfate, sodium chloride or sodium nitrate solution, and the concentration of the electrode liquid is 0.01 to 0.5 mol / L; The electro-displacement exchange membrane has a membrane resistance of less than 10 Ω·cm², an exchange capacity of ≥1.3 mol / kg, and an acid and alkali resistance pH of 2 to 10.

10. The skid-mounted micro-interface enhanced dual electrodisplacement device for preparing ammonium alkali by mixing salts according to claim 9, characterized in that, Each of the raw material chambers and product chambers is connected to the corresponding compartments of the electro-displacement membrane stack (3) to form a corresponding cycle. Before the electro-displacement begins, the product chamber contains pure water.

Images