Efficient preparation method and equipment of anhydrous sodium acetate

Abstract

The invention provides a method and equipment for efficiently preparing anhydrous sodium acetate, and relates to the technical field of organic chemical product preparation, and the method comprises the following steps: (1) inputting food-grade glacial acetic acid and ionic membrane liquid sodium hydroxide into a pH self-adaptive neutralization reactor according to a molar ratio of 1: (1.02-1.05), dynamically adjusting the flow of alkali liquor through a PID (Proportion Integration Differentiation) controller, and maintaining the pH value to be 7.2 + / -0.05 and the temperature to be 60 + / -0.5 DEG C; (2) removing impurities from the reaction liquid through a cyclone filter, wherein a conical flow baffle and five layers of 316L stainless steel sintered mesh filter elements are arranged in the filter; (3) inputting the filtrate into a multifunctional evaporation drying kettle through a heat preservation pipeline, and sequentially completing concentration, crystallization and dehydration drying in the multifunctional evaporation drying kettle, the concentration, crystallization and dehydration drying are completed in the same multifunctional evaporation drying kettle, solid-liquid separation is not needed, no mother liquor is generated in the production process, no centrifugal separation procedure is needed, the technological process is simplified to the maximum extent, and the production cost is reduced. The production efficiency is improved, the production cost is reduced, and the product quality is stable.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical product preparation technology, and more specifically, it relates to a method and equipment for the efficient preparation of anhydrous sodium acetate. Background Technology

[0002] The production process of anhydrous sodium acetate typically involves: neutralizing acetic acid and alkali solution at a specific molar ratio; filtering to remove impurities and insoluble matter; concentrating under negative pressure; cooling and crystallizing; centrifuging to obtain sodium acetate trihydrate; and then drying at high temperature to remove free water and water of crystallization, thus obtaining anhydrous sodium acetate. This production process requires the organic combination of multiple production units. It suffers from numerous drawbacks, including a long process route, high investment, high energy consumption, a large number of operators, low production efficiency, and high manufacturing costs.

[0003] Process decomposition: The current process requires six independent steps: neutralization, filtration, concentration, crystallization, centrifugation, and high-temperature drying. The series connection of equipment results in frequent material transfers and significant heat loss. The centrifugation process generates 15% of the total volume of mother liquor containing sodium acetate, necessitating the addition of a mother liquor recovery system.

[0004] Equipment redundancy: The crystallization kettle, centrifuge, and fluidized bed dryer are placed separately, resulting in a large equipment footprint, increased maintenance costs, and the multi-level connection interface is prone to introducing impurities.

[0005] Insufficient product stability: Fluctuations in staged drying temperature lead to residual water of crystallization (>1%), and incomplete neutralization of free acid / base causes pH shifts in the product, affecting compliance in pharmaceutical / food applications. Technical bottleneck: While existing improved processes attempt to simplify the workflow, the physical processes of solid-liquid separation and high-temperature drying are disconnected, preventing process integration and hindering production efficiency and energy consumption optimization. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method and apparatus for the efficient preparation of anhydrous sodium acetate.

[0007] A method for the efficient preparation of anhydrous sodium acetate includes: (1) Food-grade glacial acetic acid and ion-exchange membrane liquid sodium hydroxide were fed into the pH adaptive neutralization reactor at a molar ratio of 1:1.02-1.05. The flow rate of the alkali solution was dynamically adjusted by the PID controller to maintain pH=7.2±0.05 and temperature 60±0.5℃. (2) The reaction liquid is filtered to remove impurities by a cyclone filter, which has a built-in conical baffle and a five-layer 316L stainless steel sintered mesh filter element. (3) The filtrate is fed into the multi-functional evaporation dryer through the heat-insulated pipe, and the concentration, crystallization and dehydration are completed sequentially in a single device.

[0008] Preferably, the annular conical baffle plate 22 of the cyclone filter has an angle of 45-60° with the axis, and is fixed to the inner wall of the shell with the large opening facing upward. The tangential liquid inlet induces cyclone centrifugal force. The filter element operates at a temperature of 70°C, with a pressure difference controlled at 0.12MPa and a backwash cycle of 3-5 hours. The scraping device 4 of the multifunctional evaporation dryer is installed on both sides of the H-shaped part of the stirring paddle by adjustable bolts. The distance between the scraper and the inner wall of the kettle is adjustable. The jacket of the heating device 2 is equipped with a spiral guide plate, and the heat medium is heat transfer oil.

[0009] In step (3), the concentration stage is carried out under a vacuum of -0.08 to -0.085 MPa, the crystallization stage is heated to 220°C and operated under a slight negative pressure, and the drying stage is heated to 240°C and dehydrated under a slight negative pressure.

[0010] An anhydrous sodium acetate production device includes a multi-functional evaporation dryer and a cyclone filter, which are directly connected by an insulated pipe. The stirring device 3 of the evaporation dryer is connected to a reducer 8 and a motor 9 via a coupling 6. A support device 15 is provided at the bottom of the dryer to stabilize the stirring shaft. The drain port 33 of the cyclone filter is equipped with a timed self-controlled solenoid valve. The discharge port 16 of the evaporation dryer is connected to a cooling and screening system. The pH adaptive neutralization reactor has a built-in pH sensor and flow meter to provide real-time feedback and adjust the amount of liquid alkali added.

[0011] Compared with the prior art, the present invention has the following beneficial effects: In this invention, the three processes of concentration, crystallization and drying are continuously integrated through a multi-functional evaporation dryer, completely eliminating the centrifugal separation step, eliminating the need for mother liquor recovery, shortening the process chain by more than 50%, and the cascade utilization mode of thermal energy significantly reduces the total energy consumption of the system.

[0012] In this invention, product quality is significantly improved. The pH adaptive neutralization mechanism eliminates the risk of residual free acid / alkali, the cyclone precision filtration ensures deep impurity retention, and the integrated drying process avoids intermediate contamination, ensuring that the crystal purity and moisture content meet pharmaceutical-grade standards.

[0013] In this invention, through process improvement, concentration, crystallization, dehydration and drying are completed in the same multi-functional evaporation dryer, eliminating the need for solid-liquid separation, generating no mother liquor during production, and eliminating the need for centrifugal separation. This greatly simplifies the process, improves production efficiency, reduces production costs, and ensures stable product quality. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a multi-functional steam drying kettle; Figure 2 This is a schematic diagram of the cyclone filter of the present invention.

[0015] In the diagram, the correspondence between component names and attached drawing numbers is as follows: 1. Kettle body; 2. Heating device; 3. Stirring device; 4. Scraping device; 5. Manhole; 6. Coupling; 7. Frame; 8. Reducer; 9. Motor; 10. Sealing device; 11. Base; 12. Feed inlet; 13. Exhaust port; 14. Heat medium outlet; 15. Support device; 16. Discharge port; 17. Heat medium inlet; 21. Conical shell; 22. Circular conical baffle plate; 23. Tangential feed inlet; 24. Cylindrical shell; 25. Sealing ring; 26. Top cover; 27. Metal sintered mesh filter element; 28. Fastener; 29. ​​Discharge port; 31. Filter element fixing plate; 33. Drainage port; 34. Electric ball valve. Detailed Implementation

[0016] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0017] Please see Figure 1 - Figure 2 This invention provides a method for the efficient preparation of anhydrous sodium acetate, comprising: (1) Food-grade glacial acetic acid and ion-exchange membrane liquid sodium hydroxide were fed into the pH adaptive neutralization reactor at a molar ratio of 1:1.02-1.05. The flow rate of the alkali solution was dynamically adjusted by the PID controller to maintain pH=7.2±0.05 and temperature 60±0.5℃. (2) The reaction liquid is filtered to remove impurities by a cyclone filter, which has a built-in conical baffle and a five-layer 316L stainless steel sintered mesh filter element. (3) The filtrate is fed into the multi-functional evaporation dryer through the heat-insulated pipe, and the concentration, crystallization and dehydration are completed sequentially in a single device.

[0018] The pH control in step (1) is controlled by the PID controller, which has good stability and can ensure that the reaction system can maintain good stability under different working conditions. The neutralization reactor in step (1) is a pH adaptive neutralization reactor. It can monitor the pH in real time through built-in sensors (pH, flow rate) and automatically adjust the amount of liquid sodium hydroxide added to accurately control the reaction process and ensure the neutralization effect. The glacial acetic acid and liquid sodium hydroxide in step (1) are food-grade glacial acetic acid and ion membrane liquid sodium hydroxide, respectively, with mass concentrations of 99.5% and 32%, respectively, a molar ratio of 1:1.02-1.05, a reaction pH of 7.2±0.05, a reaction temperature of 60±0.2℃, and a reaction time of 3 to 5 hours. Step (2) Cyclone Filter: Two to three baffles are installed inside the cylindrical shell. The baffles are annular cones with an angle of 45-60° between the annular wall and the axis. The larger opening of the annular cone baffle 22 faces upward, and its periphery is connected to the inner wall of the shell. The filter element is a five-layer sintered mesh filter element, which is made of five layers of 316L stainless steel wire mesh stacked and vacuum sintered. It has the characteristics of strong corrosion resistance, good permeability, high strength, easy cleaning and backwashing, uniform filtration accuracy, hygienic and clean filter material, and no wire mesh shedding. The liquid inlet is a tangential inlet connected to the reactor outlet 29, and a self-controlled solenoid valve is installed at the outlet 29. The liquid outlet is connected to the liquid inlet of the multi-functional evaporation dryer through a pipe. A self-controlled solenoid valve is installed at the drain outlet 33 to realize timed or automatic sewage discharge. The filter is integrated into the reactor outlet and maintained at 70°C to prevent sodium acetate precipitation and blockage.

[0019] Step (3) Evaporation dryer. The evaporation dryer is a special equipment designed and manufactured specifically for the production of anhydrous sodium acetate. The evaporation dryer consists of a body 1, a heating device 2, a stirring device 3, a scraping device 4, a sealing device 10, a transmission device, a support device 15, etc. The vessel body 1 consists of a cylindrical body and upper and lower end caps. The heating device 2 is a jacket with a spiral guide plate, which can better heat the material inside the vessel body 1. A heat medium outlet 14 is installed on one side of the upper end of the jacket, and a heat medium inlet 17 is installed on the lower end. The heat medium used is heat transfer oil. The stirring device 3 is a specially made stirrer, which is fastened to the stirring shaft. The scraping device 4 consists of two symmetrically installed scrapers, which are fixed to both sides of the H-shaped part of the stirring paddle with three bolts respectively. The scrapers have rectangular bolt holes to facilitate the adjustment of the distance between the scrapers and the inner wall of the vessel body 1, and to prevent the material from forming a thick scale on the inner wall of the vessel body 1. The sealing device 10 is a complete set of mechanical seal components. The transmission device consists of a motor 9, a reducer 8, and a frame 7, which is installed at the upper end of the evaporating vessel and connected to the stirring device 3 through a coupling 6. The support device 15 consists of a bearing, a bearing seat, and a bracket, which is installed at the lower end of the axial position inside the vessel body 1 to prevent the stirring device 3 from shaking. Using this evaporating vessel, concentration, crystallization, and drying dehydration can be completed sequentially, simplifying the process flow to the greatest extent.

[0020] The annular conical baffle plate 22 of the cyclone filter has an angle of 45-60° with the axis, and is fixed to the inner wall of the shell with the large opening facing upward. The tangential liquid inlet induces cyclone centrifugal force. The filter element working temperature is maintained at 70℃, the pressure difference is controlled at 0.12MPa, and the backwash cycle is 3-5h. The scraping device 4 of the multi-functional evaporation dryer is installed on both sides of the H-shaped part of the stirring paddle by adjustable bolts. The distance between the scraper and the inner wall of the kettle is adjustable. The jacket of the heating device 2 is equipped with a spiral guide plate, and the heat medium is heat transfer oil.

[0021] In step (3), the concentration stage is carried out under a vacuum of -0.08 to -0.085 MPa, the crystallization stage is heated to 220°C and operated under a slight negative pressure, and the drying stage is heated to 240°C and dehydrated under a slight negative pressure.

[0022] An anhydrous sodium acetate production device includes a multi-functional evaporation dryer and a cyclone filter, which are directly connected by an insulated pipe. The stirring device 3 of the evaporation dryer is connected to a reducer 8 and a motor 9 via a coupling 6. A support device 15 is provided at the bottom of the dryer to stabilize the stirring shaft. The drain port 33 of the cyclone filter is equipped with a timed self-controlled solenoid valve. The discharge port 16 of the evaporation dryer is connected to a cooling and screening system. The pH adaptive neutralization reactor has a built-in pH sensor and flow meter to provide real-time feedback and adjust the amount of liquid alkali added.

[0023] The evaporation dryer is a specialized piece of equipment designed and manufactured specifically for the production of anhydrous sodium acetate. Its structural diagram is shown below. Figure 1 The reactor consists of a vessel body 1, a heating device 2, a stirring device 3, a scraping device 4, a sealing device 10, a transmission device, and a support device 15. The vessel body 1 comprises a cylindrical body and upper and lower end caps. The heating device 2 is a jacketed structure with spiral guide plates, which better heats the material inside the vessel body 1. A heat medium outlet 14 is installed on one side of the upper end of the jacket, and a heat medium inlet 17 is installed on the lower end. The stirring device 3 consists of a stirring paddle, a stirring shaft, and a coupling 6. The scraping device 4 consists of two symmetrically installed scrapers, each fixed to both sides of the H-shaped section of the stirring paddle with three bolts. The holes on the scrapers for connecting to the bolts are rectangular, facilitating adjustment of the distance between the scraper and the inner wall of the vessel. The sealing device 10 is a complete mechanical seal assembly. The transmission device consists of a motor 9, a reducer 8, and a frame 7. The support device 15 consists of bearings, bearing seats, and a bracket. This drying reactor can sequentially complete concentration, crystallization, and drying dehydration, greatly simplifying the process flow.

[0024] Working principle: Using glacial acetic acid and sodium hydroxide as raw materials, a sodium acetate solution is generated in a pH adaptive neutralization reactor. After impurity removal by a cyclone filter, the solution enters a dedicated multi-functional evaporation dryer. Within this dryer, the following processes are sequentially completed: concentration → crystallization → dehydration and drying, achieving integrated production of these three steps. This significantly simplifies the production process, improves production efficiency, and reduces energy consumption by approximately 45%. A schematic diagram of the cyclone filter is shown below. Figure 1 The cylindrical shell 24 contains 2-3 annular conical baffles 22, with the angle between the annular wall and the axis being 45-60°. The larger opening of the annular conical baffles 22 faces upward, and its periphery is connected to the inner wall of the shell. The cyclone filter inlet is a tangential inlet connected to the reactor outlet 29, which is equipped with a self-regulating solenoid valve. The outlet is connected to the inlet of the multi-functional evaporation dryer. A manual ball valve or a self-regulating solenoid valve is installed at the drain outlet 33 to enable timed or automatic draining. The filter is integrated into the reactor outlet, maintaining a temperature of 70°C to prevent sodium acetate precipitation and blockage.

[0025] Example:

[0026] (1) Raw material preparation: Pump 2.5 tons of 99.5% glacial acetic acid (food grade) into the reactor and start stirring. Slowly add 1.82 tons of 32% ion-exchange membrane liquid sodium hydroxide (Fe content <1ppm) into the reactor, with the molar ratio controlled at CH3COOH:NaOH = 1:1.03.

[0027] (2) Neutralization reaction: The pH was maintained at 7.2±0.05 using a PID controller; the reaction temperature was 60±0.2℃ (cooling water ΔT=8℃), and the reaction time was controlled at 3-5 hours. Maintaining the temperature at around 60℃ effectively prevented the generation of irritating gases.

[0028] (3) Cyclone filtration: After the reaction is complete, open the inlet and outlet valves of the cyclone fine filter. The reaction liquid enters the multi-functional evaporation kettle after cyclone separation and fine filtration. Filter pressure difference: 0.12MPa (backwash cycle 3-5h), filtered impurities: ≤0.5mg / L (detected by laser particle size analyzer) (4) Operation of the drying kettle: Concentration: Start the stirring device (3), vacuum system, open the inlet and outlet valves of the heat transfer medium in the dryer, control the temperature of the heat transfer oil at 200±2℃, and concentrate until white crystals appear under a vacuum of -0.08 to -0.085MPa. Close the vacuum system, break the vacuum in the dryer, start the exhaust system, and make a slight negative pressure in the dryer.

[0029] Crystallization: The temperature of the heat transfer oil is raised to 220℃, and the reaction solution is heated under a slight negative pressure. The liquid in the reactor is gradually converted into a solid (wet sodium acetate) as it evaporates to dryness. Dehydration and drying: The temperature of the heat transfer oil is raised to 240℃, and the wet sodium acetate in the evaporation kettle is heated and dried under a slight negative pressure. The free water in the wet sodium acetate is gradually removed, and it becomes dry anhydrous sodium acetate.

[0030] (5) Post-processing: The anhydrous sodium acetate obtained by the above steps is cooled, sieved and packaged to obtain the finished anhydrous sodium acetate.

[0031] (6) Sampling and inspection results: Content (calculated as anhydrous sodium acetate) 99.9%, pH (5% aqueous solution at 25℃) 7.8; Water-insoluble matter: 0.001%; Loss on drying (120℃) 0.6%; Chloride (Cl) 0.015%; Phosphate (PO4) 0.0003%; Sulfate (SO2) 0.001%; Heavy metals (as Pb) 0.0005%; It meets the requirements of the national standard GB1886.65-2016 for food grade and the relevant indicators of the 2020 edition of the Chinese Pharmacopoeia.

[0032] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A method for the efficient preparation of anhydrous sodium acetate, characterized in that... include: (1) Food-grade glacial acetic acid and ion-exchange membrane liquid sodium hydroxide were fed into the pH adaptive neutralization reactor at a molar ratio of 1:1.02-1.

05. The flow rate of the alkali solution was dynamically adjusted by the PID controller to maintain pH=7.2±0.05 and temperature 60±0.5℃. (2) The reaction liquid is filtered to remove impurities by a cyclone filter, which has a built-in conical baffle and a five-layer 316L stainless steel sintered mesh filter element. (3) The filtrate is fed into the multi-functional evaporation dryer through the heat-insulated pipe, and the concentration, crystallization and dehydration are completed sequentially in a single device.

2. The method according to claim 1, characterized in that: The annular conical baffle (22) of the cyclone filter has an angle of 45-60° with the axis, and is fixed to the inner wall of the shell with the large opening facing upwards, and induces cyclone centrifugal force at the tangential liquid inlet.

3. The method according to claim 2, characterized in that: The filter element operates at a temperature of 70°C, with a differential pressure of 0.12 MPa and a backwash cycle of 3–5 hours.

4. The method according to claim 1, characterized in that: The scraping device (4) of the multi-functional steam dryer is installed on both sides of the H-shaped part of the stirring paddle by adjustable bolts, and the distance between the scraper and the inner wall of the kettle is adjustable.

5. The method according to claim 4, characterized in that: The heating device (2) has a spiral guide plate inside its jacket, and the heat transfer medium is heat transfer oil.

6. The method according to claim 1, characterized in that: In step (3), the concentration stage is carried out under a vacuum of -0.08 to -0.085 MPa, the crystallization stage is heated to 220°C and operated under a slight negative pressure, and the drying stage is heated to 240°C and dehydrated under a slight negative pressure.

7. An anhydrous sodium acetate production equipment, characterized in that: It includes the cyclone filter as described in claims 2-3 and the multifunctional evaporation dryer as described in claims 4-5, and the two are directly connected by an insulated pipe.

8. The device according to claim 7, characterized in that: The stirring device (3) of the evaporating kettle is connected to the reducer (8) and the motor (9) through the coupling (6), and the bottom of the kettle is provided with a support device (15) to stabilize the stirring shaft.

9. The device according to claim 7, characterized in that: The drain port (33) of the cyclone filter is equipped with a timed self-controlled solenoid valve, and the discharge port (16) of the evaporation kettle is connected to the cooling screening system.

10. The device according to claim 7, characterized in that: The pH adaptive neutralization reactor has a built-in pH sensor and flow meter to provide real-time feedback and adjust the amount of liquid alkali added.

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