Continuous synthesis process of potassium propionate

Abstract

The invention discloses a potassium propionate continuous synthesis process, and relates to the technical field of potassium propionate synthesis, the process comprises the following steps: S1, raw material pretreatment: selecting fermentation waste liquid containing propionic acid and acetic acid and potassium ore leaching liquid containing potassium hydroxide and potassium carbonate as composite raw materials, adding a composite chelating agent into the potassium ore leaching liquid, and uniformly stirring; according to the method, the composite raw material system composed of the fermentation waste liquid and the potassium ore leaching liquid is adopted, and the composite chelating agent is added, so that resource utilization of industrial waste is achieved, the raw material cost is reduced, meanwhile, impurities are prevented from interfering with continuous reaction, and through gradient temperature control-pressure cooperative regulation and linkage regulation of the PLC system, the yield is increased. The problem of product deliquescence caused by local overheating is solved, volatilization loss of propionic acid is reduced, the adaptability of the technology to raw material batch fluctuation is improved through raw material concentration online detection and dynamic parameter adaptation, the continuous production stability is guaranteed, and finally synchronous improvement of the potassium propionate synthesis efficiency and the product quality is achieved.

Description

Technical Field

[0001] This invention relates to the field of potassium propionate synthesis technology, specifically a continuous synthesis process for potassium propionate. Background Technology

[0002] Potassium propionate is an important organic acid salt with functions such as preservation, freshness maintenance, and antibacterial properties, and is widely used in food processing, feed additives, and pharmaceutical intermediates. In the food industry, it can effectively inhibit the growth of microorganisms such as molds and yeasts, extend the shelf life of food, and has no toxic side effects on humans. In the feed industry, it can improve feed palatability and prevent feed spoilage, ensuring the healthy growth of farmed animals. Its application is of great significance to the quality improvement and safety assurance of related industries. Continuous synthesis of potassium propionate refers to a synthesis method that uses a continuous production process to sequentially and uninterruptedly carry out raw material pretreatment, reaction, separation, and purification. Compared with batch synthesis processes, continuous synthesis processes have advantages such as high production efficiency, stable product quality, low energy consumption, and high degree of automation, which can meet the needs of large-scale industrial production and is of key significance for reducing production costs and enhancing industrial competitiveness.

[0003] However, existing potassium propionate synthesis technologies still have certain shortcomings. The raw material selection is relatively limited, primarily using high-purity propionic acid and potassium hydroxide as reactants, resulting in high raw material costs and a lack of resource utilization of industrial waste. Process parameters are often controlled at constant levels, leading to localized overheating during the reaction and increasing the risk of product deliquescence. Furthermore, propionic acid is volatile, causing raw material loss and lacking adaptability to batch fluctuations in raw materials. In continuous production, stability is poor, affecting product conversion rate and quality consistency. In some processes, raw material impurities are not effectively treated, easily forming insoluble salts that interfere with the smooth progress of continuous reactions. Therefore, developing a continuous potassium propionate synthesis process is of great significance. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a continuous synthesis process for potassium propionate. This process utilizes a composite raw material system consisting of fermentation waste liquid and potassium ore leaching liquid, with the addition of a composite chelating agent, to achieve the resource utilization of industrial waste. Through gradient temperature control-pressure coordinated regulation and PLC system linkage adjustment, the loss of propionic acid volatilization is reduced. Through online detection of raw material concentration and dynamic parameter adaptation, the process's adaptability to batch fluctuations of raw materials is improved, ensuring the stability of continuous production. Ultimately, this achieves a simultaneous improvement in potassium propionate synthesis efficiency and product quality.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a continuous synthesis process for potassium propionate, the process comprising the following steps:

[0006] S1. Raw material pretreatment: Select fermentation waste liquid containing propionic acid and acetic acid and potassium ore leaching liquid containing potassium hydroxide and potassium carbonate as composite raw materials. Add composite chelating agent to potassium ore leaching liquid and stir evenly.

[0007] S2. Raw material mixing: The pretreated potassium ore leaching solution and fermentation waste liquid are fed into the raw material mixing tank, and the content of organic acid and available potassium in the mixed raw materials is monitored in real time by the online raw material concentration detection module.

[0008] S3, Gradient Temperature Control-Pressure Co-reaction: The mixed raw materials are continuously fed into the reaction device. The temperature in the reaction section is controlled at 30-40℃. Subsequently, the raw materials enter the evaporation section, where the temperature is gradually increased to 80-100℃. At the same time, the pressure is reduced from atmospheric pressure to 0.05MPa. The temperature and pressure matching degree is adjusted in real time through the PLC system.

[0009] S4. Dynamic parameter adaptation: Based on the monitoring data from the online raw material concentration detection module, the flow rate of the potassium alkali solution, the reaction flow rate, and the amount of chelating agent added are automatically adjusted.

[0010] S5. Product separation: Solid-liquid separation is performed on the evaporated material to obtain crude potassium propionate.

[0011] S6. Purification and Drying: After refining the crude potassium propionate, it is dried to obtain a high-purity potassium propionate product.

[0012] Furthermore, the composite chelating agent is selected from one or more of disodium EDTA, sodium citrate, and sodium pyrophosphate. The amount of the composite chelating agent added is 0.5%-1.0% of the mass of the potassium ore leaching solution. The stirring speed is controlled at 100-200 r / min and the stirring time is 20-30 min. The chelating agent is added in the form of an aqueous solution with a mass fraction of 10%-20%.

[0013] Furthermore, the fermentation waste liquid contains 10%-20% propionic acid and 2%-5% acetic acid by mass. The fermentation waste liquid is pretreated to remove suspended particulate matter, with a removal rate of not less than 98%. The potassium ore leaching solution contains 8%-15% potassium hydroxide and 3%-8% potassium carbonate by mass. The pH value of the leaching solution is controlled between 11 and 13. Suspended particulate matter is removed by filtration through a ceramic membrane with a pore size of 0.1-0.5 μm.

[0014] Furthermore, in step S3, the temperature control accuracy of the reaction section is ±0.5℃, and the temperature is regulated by a jacketed heat exchanger. The heating rate of the evaporation section is 5-10℃ / h. During the heating process, the viscosity change of the material is monitored in real time. When the viscosity reaches 50-100mPa・s, the heating is stopped and the temperature is maintained until the evaporation is completed. The heat exchange medium of the jacketed heat exchanger is an aqueous solution of ethylene glycol with a mass fraction of 30%-50%.

[0015] Furthermore, the linkage adjustment logic of the PLC system is as follows: when the temperature of the reaction section deviates from the set value by ±1℃ or the pressure of the evaporation section deviates from the set value by ±0.005MPa, the system automatically adjusts the heat exchange medium flow rate or vacuum degree, with an adjustment response time not exceeding 5s, the heat exchange medium flow rate adjustment range being 5%-15%, and the vacuum degree adjustment range being 0.002-0.008MPa.

[0016] Furthermore, the detection parameters of the online raw material concentration detection module include propionic acid concentration, acetic acid concentration, potassium hydroxide concentration, potassium carbonate concentration, and calcium and magnesium ion concentration. The detection frequency is once every 10-15 minutes, and the detection data is transmitted to the PLC system in real time. The online raw material concentration detection module uses a near-infrared spectrometer with a detection accuracy of ±0.1%.

[0017] Furthermore, the solid-liquid separation in step S5 adopts plate and frame filtration or centrifugal separation. When using plate and frame filtration, the filtration pressure is 0.3-0.5MPa and the filtration temperature is 40-50℃. When using centrifugal separation, the centrifugal speed is 3000-5000r / min and the centrifugation time is 10-15min. The plate and frame filter uses polypropylene filter cloth, and the centrifugal separation adopts a horizontal spiral sedimentation centrifuge.

[0018] Furthermore, the refining process in step S6 employs recrystallization, using deionized water as the recrystallization solvent. The mass ratio of solvent to crude product is 3:1-5:1, the dissolution temperature is 70-80℃, the cooling crystallization temperature is 0-5℃, and the crystallization time is 4-6 hours. The drying process utilizes hot air drying at 100-110℃ for 2-3 hours, with nitrogen gas introduced during the drying process. During the dissolution process, mechanical stirring is employed at a speed of 80-120 r / min, with a nitrogen gas introduction rate of 0.5-1.0 m / min. 3 / h.

[0019] Furthermore, in step S2, the mixing ratio of fermentation waste liquid and potassium ore leaching liquid is determined based on the molar ratio of organic acid to available potassium, and the molar ratio is controlled between 1:1.02 and 1:1.08. The flow rate of the two raw materials is controlled by a flow metering pump with a control accuracy of ±1%. The flow metering pump is a plunger type, and the inlet and outlet pressure fluctuation does not exceed ±0.02 MPa.

[0020] Compared with existing technologies, this continuous synthesis process for potassium propionate has the following advantages:

[0021] This invention utilizes a composite raw material system consisting of fermentation waste liquid and potassium ore leaching liquid, along with a composite chelating agent, to achieve resource utilization of industrial waste. This reduces raw material costs while avoiding impurities interfering with continuous reactions. Through gradient temperature and pressure coordinated regulation and PLC system linkage adjustment, the problem of product deliquescence caused by local overheating is solved, reducing propionic acid volatilization loss. Online detection of raw material concentration and dynamic parameter adaptation enhance the process's adaptability to batch fluctuations in raw materials, ensuring continuous production stability. Ultimately, this invention achieves simultaneous improvement in potassium propionate synthesis efficiency and product quality, solving the technical problems of traditional processes such as single raw material, high cost, high risk of product deliquescence, and poor continuous stability. It has significant economic and environmental benefits.

[0022] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0024] Figure 1 A flowchart of a continuous synthesis process for potassium propionate;

[0025] Figure 2 This is a flow chart of a continuous synthesis process for potassium propionate. Detailed Implementation

[0026] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0027] This invention provides a continuous synthesis process for potassium propionate, aiming to realize the resource utilization of industrial waste, improve synthesis efficiency and product quality. (See also...) Figure 1 and Figure 2 The specific technical details are as follows:

[0028] The raw materials selected are fermentation wastewater containing propionic acid and acetic acid, and potassium ore leaching solution containing potassium hydroxide and potassium carbonate as composite raw materials. The fermentation wastewater contains 10%-20% propionic acid and 2%-5% acetic acid, requiring pretreatment to remove suspended particulate matter, with a removal rate of not less than 98%. The potassium ore leaching solution contains 8%-15% potassium hydroxide and 3%-8% potassium carbonate, with the pH value controlled at 11-13. Suspended particulate matter is removed by filtration through a ceramic membrane with a pore size of 0.1-0.5 μm. A composite chelating agent, selected from one or more of disodium EDTA, sodium citrate, and sodium pyrophosphate, is added to the potassium ore leaching solution at a concentration of 0.5%-1.0% of the potassium ore leaching solution mass, in the form of a 10%-20% aqueous solution. The stirring speed is 100-200 r / min, and the stirring time is 20-30 min.

[0029] The two pretreated raw materials are fed into a raw material mixing tank. Based on a molar ratio of organic acid to available potassium of 1:1.02-1:1.08, the feed rate is controlled by a plunger-type flow metering pump with a control accuracy of ±1%, and the inlet and outlet pressure fluctuations do not exceed ±0.02 MPa. An online raw material concentration detection module uses a near-infrared spectrometer to detect the concentrations of propionic acid, acetic acid, potassium hydroxide, potassium carbonate, and calcium and magnesium ions every 10-15 minutes, with a detection accuracy of ±0.1%. The data is transmitted to the PLC system in real time.

[0030] The mixed raw materials are continuously fed into the reaction apparatus. In the reaction section, a jacketed heat exchanger using a 30%-50% (by mass) ethylene glycol aqueous solution as the heat exchange medium controls the temperature to 30-40℃ with a control accuracy of ±0.5℃. The raw materials then enter the evaporation section, where the temperature is increased to 80-100℃ at a rate of 5-10℃ / h, while the pressure is simultaneously reduced from atmospheric pressure to 0.05MPa. During the heating process, the material viscosity is monitored, and heating is stopped when it reaches 50-100 mPa·s and maintained until evaporation is complete. If the temperature in the reaction section deviates from the set value by ±1℃ or the pressure in the evaporation section deviates by ±0.005MPa, the PLC system automatically adjusts the heat exchange medium flow rate (range 5%-15%) or the vacuum level (range 0.002-0.008MPa) within 5 seconds.

[0031] Based on online monitoring data, the flow rate of the potassium alkali solution, the reaction flow rate, and the amount of chelating agent added are automatically adjusted. After evaporation, the material is separated into solid and liquid components by plate and frame filtration or centrifugation. The plate and frame filtration pressure is 0.3-0.5 MPa, the temperature is 40-50℃, and polypropylene filter cloth is used. The centrifugation speed is 3000-5000 r / min, and the time is 10-15 min, using a horizontal spiral sedimentation centrifuge to obtain crude potassium propionate.

[0032] The crude product is purified by recrystallization using deionized water as the solvent at a mass ratio of 3:1-5:1. The mixture is dissolved under mechanical stirring at 70-80℃ and a speed of 80-120 r / min, followed by crystallization at 0-5℃ for 4-6 hours. After purification, the product is dried by hot air at 100-110℃ for 2-3 hours, with a pressure of 0.5-1.0 m during the drying process. 3 Nitrogen gas was introduced at a rate of / h, and high-purity potassium propionate product was finally obtained.

[0033] Example 1

[0034] This embodiment provides a highly efficient and stable continuous synthesis process for potassium propionate. By precisely controlling the raw material ratio, reaction parameters, and purification process, it achieves resource utilization of industrial waste while ensuring high product purity and production continuity. It is suitable for large-scale industrial production. (See also...) Figure 1 and Figure 2 The specific technical solution is as follows:

[0035] Fermentation wastewater containing 15% propionic acid and 3% acetic acid was selected. A pretreatment process combining plate and frame filtration and precision filtration was used to remove suspended particulate matter. Laser particle size analyzer was used to ensure a suspended particulate matter removal rate of over 98%, preventing impurity deposition during subsequent reactions. Potassium ore leaching solution containing 12% potassium hydroxide and 5% potassium carbonate was selected. The pH of the leaching solution was controlled at a stable 12 using an online pH monitor. Cross-flow filtration was performed using a 0.3μm pore size ceramic membrane, with the filtration pressure controlled at 0.2MPa, effectively removing suspended particulate matter and some colloidal impurities from the leaching solution. A composite chelating agent, consisting of disodium EDTA and sodium citrate in a 1:1 mass ratio, was added to the potash ore leaching solution via a metering pump at a uniform rate. The amount added was 0.8% of the potash ore leaching solution mass. The solution was stirred in a mixing tank at 150 r / min for 25 min to ensure that the chelating agent fully complexed with the calcium and magnesium ions in the leaching solution, thus avoiding the formation of insoluble salts that could interfere with the continuous reaction.

[0036] The two pretreated raw materials are fed into a mixing tank. The flow rates of the fermentation waste liquid and potassium ore leaching solution are controlled separately using plunger-type flow metering pumps, with a molar ratio of organic acid to available potassium of 1:1.05. The metering pump control accuracy is ±1%, and the inlet and outlet pressure fluctuations are strictly controlled within ±0.02 MPa to ensure a stable mixing ratio. An online raw material concentration detection module uses a near-infrared spectrometer to detect the concentrations of propionic acid, acetic acid, potassium hydroxide, potassium carbonate, and calcium and magnesium ions in the mixed raw materials every 12 minutes, with a detection accuracy of ±0.1%. The detection data is transmitted in real-time to the PLC control system via a wireless transmission module, providing data support for parameter adjustments.

[0037] The mixed raw materials are continuously fed into the continuous reaction unit via pipeline. The reaction section uses a jacketed heat exchanger for temperature control, with a 40% (w / w) ethylene glycol aqueous solution as the heat exchange medium. A constant-temperature circulating pump maintains a stable medium flow rate, ensuring precise temperature control of the reaction section at 35℃ with an accuracy of ±0.5℃. The reacted material enters the evaporation section, where a programmed heating mode is used to gradually raise the temperature to 90℃ at a rate of 8℃ / h. Simultaneously, a vacuum system slowly reduces the pressure from atmospheric pressure to 0.05MPa. During the heating process, the material viscosity is monitored in real-time using an online viscometer. When the viscosity reaches 80 mPa·s, the PLC system automatically triggers a heating stop command, maintaining this temperature and pressure until evaporation is complete, ensuring sufficient material concentration and preventing localized overheating. The PLC system has built-in linkage control logic. When the reaction section temperature deviates from the set value by ±1℃ or the evaporation section pressure deviates from the set value by ±0.005MPa, the system automatically adjusts the heat exchange medium flow rate (adjustment range 10%) or the vacuum level (adjustment range 0.005MPa) within 5 seconds, quickly restoring stable process parameters.

[0038] Based on real-time data transmitted from the online raw material concentration detection module, the PLC system automatically calculates the raw material ratio deviation. It adjusts the flow rate of the potassium alkali solution by regulating the frequency of the plunger-type flow metering pump, simultaneously adjusting the speed of the feed pump in the reaction unit to control the reaction flow rate. Furthermore, it dynamically adjusts the chelating agent addition amount by regulating the flow rate of the chelating agent metering pump, ensuring the reaction system remains in an optimal state. After evaporation, the material is transported through pipelines to a solid-liquid separation device, where it is separated using a plate and frame filter. The filtration pressure is set at 0.4 MPa, the filtration temperature is controlled at 45℃, and a polypropylene filter cloth with a pore size of 1 μm is used to effectively trap solid impurities, yielding a high-purity crude potassium propionate.

[0039] The crude product is refined through recrystallization. Crude potassium propionate and deionized water are added to a crystallization reactor at a mass ratio of 1:4. The mixture is mechanically stirred at 100 rpm at 75°C until dissolved. After dissolution, the material temperature is gradually reduced to 3°C using a jacketed cooling system, and crystallization is maintained at this temperature for 5 hours to form uniform potassium propionate crystals. After crystallization, the wet crystals are separated by centrifugation and then sent to a hot air drying oven at 105°C for 2.5 hours. During the drying process, a 0.8 m... 3 Nitrogen gas is continuously introduced at a rate of / h. The nitrogen gas is dehumidified and purified to prevent the crystals from absorbing moisture, while also removing the water vapor generated during the drying process, ultimately yielding a high-purity potassium propionate product.

[0040] In summary, this embodiment achieves efficient resource utilization of fermentation waste liquid and potassium ore leaching liquid by optimizing raw material ratio, reaction temperature and purification parameters, combined with online detection and PLC dynamic control. It effectively avoids impurity interference and local overheating problems, reduces propionic acid volatilization loss, and achieves product purity of over 99.5%. The production process is continuous and stable, and the material conversion rate exceeds 98%, demonstrating good prospects for industrial application.

[0041] Example 2

[0042] This embodiment designs a continuous synthesis process for potassium propionate based on low-concentration raw material systems. By adjusting the amount of chelating agent, reaction rate, and purification conditions, it adapts to fluctuations in raw material concentration, ensuring synthesis efficiency and product quality. This process is suitable for the resource recovery of low-concentration industrial waste. (See also...) Figure 1 and Figure 2 The specific technical solution is as follows:

[0043] Fermentation wastewater containing 10% propionic acid and 2% acetic acid was selected. A pretreatment process was used to remove suspended particulate matter. After natural settling in a sedimentation tank, it was then filtered through a precision filter to ensure a suspended particulate matter removal rate of no less than 98%. Potassium ore leaching solution containing 8% potassium hydroxide and 3% potassium carbonate was selected. The pH of the leaching solution was controlled to be stable at 11 using a pH adjuster. Filtration was performed using a 0.1μm pore size ceramic membrane, and the transmembrane pressure difference was controlled at 0.15MPa during filtration to effectively remove suspended particulate matter and trace impurities from the leaching solution. A composite chelating agent, using sodium citrate as the chelating agent, was added to the potassium ore leaching solution as a 10% aqueous solution at a concentration of 0.5% of the potassium ore leaching solution mass. The solution was stirred at 100 rpm for 20 minutes in a stirring device to ensure sufficient dispersion of the chelating agent and its complexation with metal ions.

[0044] The two pretreated raw materials are fed into a mixing tank at a molar ratio of organic acid to available potassium of 1:1.02. The feed rate is controlled by a plunger-type flow metering pump with a metering accuracy of ±1%, and the inlet and outlet pressure fluctuations do not exceed ±0.02 MPa to ensure uniform mixing of the raw materials. An online raw material concentration detection module uses a near-infrared spectrometer to detect the concentrations of propionic acid, acetic acid, potassium hydroxide, potassium carbonate, and calcium and magnesium ions every 10 minutes with a detection accuracy of ±0.1%. The detection data is transmitted to the PLC system in real time, providing a basis for adjusting process parameters.

[0045] The mixed raw materials are continuously fed into a continuous reaction unit. The reaction section uses a jacketed heat exchanger for temperature control, with a 30% (w / w) ethylene glycol aqueous solution as the heat exchange medium. The temperature of the reaction section is precisely controlled at 30℃ with a control accuracy of ±0.5℃ by a temperature controller. The material then enters the evaporation section, where it is slowly heated to 80℃ at a rate of 5℃ / h. Simultaneously, the pressure is reduced from atmospheric pressure to 0.05MPa by a vacuum unit. During the heating process, the viscosity changes of the material are tracked in real time by an online viscosity monitor. When the viscosity reaches 50 mPa·s, the heating is stopped and maintained at this state until evaporation is complete to prevent excessive viscosity from affecting subsequent separation. The PLC system automatically adjusts according to preset logic. When process parameters deviate, it responds quickly and adjusts the heat exchange medium flow rate or vacuum level, with a response time of no more than 5 seconds.

[0046] Based on online monitoring data of raw material concentration, the PLC system automatically analyzes fluctuations in raw material concentration. By adjusting the output flow rate of the potassium alkali solution metering pump, the feed rate of the reaction device, and the operating parameters of the chelating agent addition pump, dynamic parameter adaptation is achieved to ensure complete reaction. After evaporation, the material is separated into solid and liquid components by centrifugation. A horizontal spiral sedimentation centrifuge is selected, with a speed set at 3000 r / min and a separation time of 10 min. Centrifugal force separates solid impurities from the potassium propionate solution to obtain crude potassium propionate.

[0047] The crude product was refined by recrystallization. Crude potassium propionate and deionized water were added to a crystallization tank at a mass ratio of 1:3 and dissolved by stirring at 70°C and 80 rpm. After dissolution, the material was cooled to 0°C using a cooling system and crystallized at this temperature for 4 hours. The crystals were then centrifuged and sent to a hot air drying device for drying at 100°C for 2 hours, with a spray speed of 0.5 m... 3 Nitrogen gas is introduced at a rate of / h, with a purity of not less than 99.9%, to prevent crystal oxidation and moisture absorption, ultimately yielding a potassium propionate product that meets the standards.

[0048] In summary, this embodiment optimizes process parameters for low-concentration raw materials. By reducing the amount of chelating agent added and adjusting the reaction and drying temperatures, it ensures the stability of continuous production while adapting to the characteristics of the raw materials. The product purity can reach over 98.8%, and the material conversion rate exceeds 95%. This effectively solves the problem of low resource utilization efficiency of low-concentration industrial waste and provides an effective solution for the continuous synthesis of potassium propionate from low-concentration raw material systems.

[0049] Example 3

[0050] This embodiment uses high-concentration composite raw materials and compound chelating agents to improve the reaction rate and product purity, and shorten the production cycle. It is suitable for large-scale production scenarios with high requirements for capacity and quality. See [link to relevant documentation]. Figure 1 and Figure 2 The specific technical solution is as follows:

[0051] Fermentation wastewater containing 20% ​​propionic acid and 5% acetic acid was selected. After pretreatment to remove suspended particulate matter, a combined process of high-efficiency sedimentation and precision filtration was employed. The sedimentation time was 1 hour, and the filtration precision was 0.5 μm, ensuring a suspended particulate matter removal rate of no less than 98%. Potassium ore leaching solution containing 15% potassium hydroxide and 8% potassium carbonate was selected. The pH of the leaching solution was controlled at 13, and cross-flow filtration was performed using a ceramic membrane with a pore size of 0.5 μm at a flow rate of 1.5 m / s, effectively removing suspended particulate matter and colloidal substances. A composite chelating agent, composed of disodium EDTA, sodium citrate, and sodium pyrophosphate in a mass ratio of 2:1:1, was added to the potassium ore leaching solution as a 20% aqueous solution via a metering pump at a concentration of 1.0% of the potassium ore leaching solution mass. The solution was stirred in a stirred tank at 200 rpm for 30 minutes to enhance the complexation reaction between the chelating agent and metallic impurities, thereby improving the impurity removal effect.

[0052] The two pretreated raw materials are fed into a mixing tank at a molar ratio of organic acid to available potassium of 1:1.08. The feed rate is controlled by a plunger-type flow metering pump with a metering accuracy of ±1%, and the inlet and outlet pressure fluctuations do not exceed ±0.02 MPa to ensure uniform mixing of the high-concentration raw materials. An online raw material concentration detection module uses a near-infrared spectrometer to detect relevant concentration parameters every 15 minutes with a detection accuracy of ±0.1%. The detection data is transmitted to the PLC system in real time for real-time monitoring of the raw material concentration.

[0053] The mixed raw materials are continuously fed into the reaction unit. The temperature in the reaction section is controlled by a jacketed heat exchanger using a 50% (w / w) ethylene glycol aqueous solution as the heat exchange medium, precisely controlling the reaction temperature at 40℃ with a control accuracy of ±0.5℃. The material then enters the evaporation section, where it is rapidly heated to 100℃ at a rate of 10℃ / h. Simultaneously, the pressure is reduced to 0.05MPa via a vacuum system. The material viscosity is monitored in real time during the heating process. When the viscosity reaches 100 mPa·s, heating is stopped and maintained until evaporation is complete, ensuring rapid concentration of the material without coking. The PLC system automatically adjusts the heat exchange medium flow rate or vacuum level according to set logic, with a response time of no more than 5 seconds, ensuring stable process parameters.

[0054] Based on online monitoring data of raw material concentration, the PLC system automatically adjusts the flow rate of the potassium alkali solution, the reaction flow rate, and the amount of chelating agent added to adapt to the reaction requirements of high-concentration raw materials and avoid excessively vigorous local reactions. After evaporation, the material is separated into solid and liquid components by centrifugation. A horizontal spiral sedimentation centrifuge is selected, with the speed set at 5000 r / min and the separation time at 15 min. The high-speed centrifugal force effectively separates solid impurities from the potassium propionate solution, yielding crude potassium propionate.

[0055] The crude product was refined by recrystallization. Crude potassium propionate and deionized water were added to a crystallization reactor at a mass ratio of 1:5 and mechanically stirred at 120 r / min at 80℃ to dissolve. After dissolution, the material temperature was reduced to 5℃ using a rapid cooling system, and the mixture was kept at this temperature for 6 hours to promote rapid crystal growth. After crystallization, the resulting wet crystals were separated by centrifugation and then sent to a hot air drying oven to dry at 110℃ for 3 hours. During the drying process, the mixture was dried at a pressure of 1.0 m... 3 Nitrogen gas is introduced at a rate of / h. The nitrogen gas is preheated to 80℃ before being introduced to improve drying efficiency, and finally high-purity potassium propionate product is obtained.

[0056] In summary, this embodiment improves reaction efficiency and impurity removal by using high-concentration raw materials and compound chelating agents, combined with rapid heating evaporation and efficient centrifugal separation. It also shortens crystallization and drying time, reducing the production cycle by more than 20% compared to conventional processes. The product purity can reach over 99.8%, and the material conversion rate exceeds 99%. This approach ensures high product purity while increasing production capacity, making it suitable for the continuous synthesis of large-scale, high-quality potassium propionate.

[0057] Comparative Example

[0058] This comparative example uses a traditional potassium propionate synthesis process, with high-purity propionic acid and potassium hydroxide as raw materials. It employs a constant parameter control mode, does not add chelating agents, and does not perform online raw material detection or dynamic parameter adjustment. It is used to compare the superiority of the process of this invention.

[0059] Industrial-grade propionic acid with a purity of over 99% and potassium hydroxide were selected as raw materials. Potassium hydroxide was added to deionized water and stirred to dissolve, preparing a 10% (w / w) potassium hydroxide aqueous solution. During dissolution, natural cooling was used to control the temperature to not exceed 40°C. The propionic acid and potassium hydroxide aqueous solution were introduced into a batch reactor at a 1:1 molar ratio. The reactor inlet was closed, and a mechanical stirrer was turned on at a speed of 150 r / min. Hot water was circulated through the reactor jacket to maintain the reaction system temperature at 50°C. The reaction was carried out at this constant temperature for 2 hours without parameter monitoring or adjustment. After the reaction, the reactor vent valve was opened, and the temperature was directly raised to 100°C for atmospheric pressure evaporation and concentration. Stirring was continuous during evaporation to prevent localized overheating and charring. Heating was stopped when the material became viscous. After natural cooling to room temperature, crystallization was carried out for 8 hours. Solid-liquid separation was performed using a vacuum filtration device to obtain crude potassium propionate.

[0060] The crude product was purified by recrystallization using deionized water as the solvent, with a solvent-to-crude product mass ratio of 4:1. The mixture was heated to 80°C and stirred to dissolve. After dissolution, it was naturally cooled to room temperature and kept at that temperature for 6 hours to crystallize. The resulting wet crystals were obtained by filtration and then placed in a hot air drying oven and dried at 105°C for 3 hours to obtain potassium propionate.

[0061] This comparative example uses traditional single raw materials and constant process parameters, does not utilize industrial waste, has high raw material costs, is prone to local overheating during the reaction process leading to product deliquescence, lacks adaptability to raw material fluctuations, has poor production stability, low product purity, and significant propionic acid volatilization loss.

[0062] Comparison Projects Example 1 Example 2 Example 3 Comparative Example Raw material type Fermentation waste liquid + potassium ore leaching solution Fermentation waste liquid + potassium ore leaching solution Fermentation waste liquid + potassium ore leaching solution High-purity propionic acid + potassium hydroxide Chelating agent use Compound chelating agents Single chelating agent Compound chelating agents none Online raw material testing have have have none Dynamic parameter adjustment have have have none Reaction temperature control Gradient temperature control from 35℃ to 90℃ Gradient temperature control from 30℃ to 80℃ Gradient temperature control from 40℃ to 100℃ Constant 50℃ Pressure regulation 0.05MPa reduced pressure evaporation 0.05MPa reduced pressure evaporation 0.05MPa reduced pressure evaporation Atmospheric pressure evaporation Product purity excellent good excellent generally Raw material costs Low Low lower high propionic acid loss Low lower Low high Environmental benefits excellent excellent excellent Difference

[0063] As shown in the comparison table above, all three examples use fermentation waste liquid and potassium ore leaching liquid as composite raw materials, realizing the resource utilization of industrial waste. The raw material cost is significantly lower than that of the comparative example using high-purity raw materials, and the environmental benefits are outstanding. Examples 1 and 3, through compound chelating agents, precise gradient temperature and pressure control, online detection and dynamic parameter adjustment, show excellent performance in terms of product purity, material conversion rate, production stability and propionic acid loss control. Among them, Example 3, due to the use of high-concentration raw materials and efficient processes, has a shorter production cycle and higher product purity and conversion rate. Example 2 optimizes parameters for low-concentration raw materials. Although the product purity, conversion rate and propionic acid loss control are slightly lower than those of Examples 1 and 3, they are still far superior to the comparative example and can be adapted to low-concentration raw material scenarios.

[0064] The comparative example, due to the use of a single high-purity raw material without chelating agents and the lack of online monitoring and dynamic adjustment mechanisms, resulted in high raw material costs, significant propionic acid loss, poor production stability, low product purity and material conversion rate, and failure to achieve waste resource utilization, leading to poor environmental benefits. In summary, the continuous potassium propionate synthesis process of this invention, through a composite raw material system, chelating agent addition, gradient temperature-pressure synergy, and dynamic parameter adaptation, comprehensively outperforms traditional processes in terms of product quality, production efficiency, cost control, and environmental benefits, demonstrating significant economic and technological advantages.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A continuous synthesis process for potassium propionate, characterized in that, The process includes the following steps: S1. Raw material pretreatment: Select fermentation waste liquid containing propionic acid and acetic acid and potassium ore leaching liquid containing potassium hydroxide and potassium carbonate as composite raw materials. Add composite chelating agent to potassium ore leaching liquid and stir evenly. S2. Raw material mixing: The pretreated potassium ore leaching solution and fermentation waste liquid are fed into the raw material mixing tank, and the content of organic acid and available potassium in the mixed raw materials is monitored in real time by the online raw material concentration detection module. S3, Gradient Temperature Control-Pressure Co-reaction: The mixed raw materials are continuously fed into the reaction device. The temperature in the reaction section is controlled at 30-40℃. Subsequently, the raw materials enter the evaporation section, where the temperature is gradually increased to 80-100℃. At the same time, the pressure is reduced from atmospheric pressure to 0.05MPa. The temperature and pressure matching degree is adjusted in real time through the PLC system. S4. Dynamic parameter adaptation: Based on the monitoring data from the online raw material concentration detection module, the flow rate of the potassium alkali solution, the reaction flow rate, and the amount of chelating agent added are automatically adjusted. S5. Product separation: Solid-liquid separation is performed on the evaporated material to obtain crude potassium propionate. S6. Purification and Drying: After refining the crude potassium propionate, it is dried to obtain a high-purity potassium propionate product.

2. The continuous synthesis process of potassium propionate according to claim 1, characterized in that, The composite chelating agent is selected from one or more of disodium EDTA, sodium citrate, and sodium pyrophosphate. The amount of the composite chelating agent added is 0.5%-1.0% of the mass of the potassium ore leaching solution. The stirring speed is controlled at 100-200 r / min and the stirring time is 20-30 min. The chelating agent is added in the form of an aqueous solution with a mass fraction of 10%-20%.

3. The continuous synthesis process of potassium propionate according to claim 1, characterized in that, The fermentation waste liquid contains 10%-20% propionic acid and 2%-5% acetic acid. The fermentation waste liquid is pretreated to remove suspended particulate matter, with a removal rate of not less than 98%. The potassium ore leaching solution contains 8%-15% potassium hydroxide and 3%-8% potassium carbonate. The pH value of the leaching solution is controlled between 11 and 13.

4. The continuous synthesis process of potassium propionate according to claim 1, characterized in that, In step S3, the temperature control accuracy of the reaction section is ±0.5℃. Temperature is regulated by a jacketed heat exchanger. The heating rate of the evaporation section is 5-10℃ / h. During the heating process, the viscosity change of the material is monitored in real time. When the viscosity reaches 50-100mPa・s, the heating is stopped and maintained at that temperature until the evaporation is completed.

5. The continuous synthesis process of potassium propionate according to claim 1, characterized in that, The linkage adjustment logic of the PLC system is as follows: when the temperature of the reaction section deviates from the set value by ±1℃ or the pressure of the evaporation section deviates from the set value by ±0.005MPa, the system automatically adjusts the flow rate of the heat exchange medium or the vacuum degree. The adjustment response time does not exceed 5s, the adjustment range of the heat exchange medium flow rate is 5%-15%, and the adjustment range of the vacuum degree is 0.002-0.008MPa.

6. The continuous synthesis process of potassium propionate according to claim 1, characterized in that, The online raw material concentration detection module detects parameters including propionic acid concentration, acetic acid concentration, potassium hydroxide concentration, potassium carbonate concentration, and calcium and magnesium ion concentration. The detection frequency is once every 10-15 minutes, and the detection data is transmitted to the PLC system in real time.

7. The continuous synthesis process of potassium propionate according to claim 1, characterized in that, The solid-liquid separation in step S5 is performed by plate and frame filtration or centrifugation. When plate and frame filtration is used, the filtration pressure is 0.3-0.5 MPa and the filtration temperature is 40-50℃. When centrifugation is used, the centrifugation speed is 3000-5000 r / min and the centrifugation time is 10-15 min.

8. The continuous synthesis process of potassium propionate according to claim 1, characterized in that, The refining process in step S6 employs recrystallization, using deionized water as the recrystallization solvent. The mass ratio of solvent to crude product is 3:1-5:

1. The dissolution temperature is 70-80℃, the cooling crystallization temperature is 0-5℃, and the crystallization time is 4-6 hours. Hot air drying is used at 100-110℃ for 2-3 hours, with nitrogen gas introduced during the drying process. Mechanical stirring is employed during the dissolution process at a speed of 80-120 r / min, with a nitrogen gas introduction rate of 0.5-1.0 m / min. 3 / h.

9. The continuous synthesis process of potassium propionate according to claim 1, characterized in that, In step S2, the mixing ratio of fermentation waste liquid and potassium ore leaching liquid is determined according to the molar ratio of organic acid to available potassium. The molar ratio is controlled between 1:1.02 and 1:1.

08. The flow rate of the two raw materials is controlled by a flow metering pump with a control accuracy of ±1%.

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