Demuron drying solvent recovery process

Abstract

The invention relates to the technical field of diuron post-treatment, and discloses a process for recovering a diuron drying solvent. Aiming at the problems of high drying energy consumption, high solvent residue and high toluene consumption caused by adopting toluene as a solvent in the existing diuron production, the process comprises the following steps: carrying out solid-liquid separation to obtain a diuron filter cake, carrying out sealed conveying, and sequentially carrying out vacuum belt type primary drying and far infrared radiation secondary drying, diffusion and desorption of residual toluene are promoted by utilizing a molecular resonance effect; generated toluene-containing steam is subjected to two-stage condensation recovery and modified activated carbon adsorption treatment, and drying parameters are dynamically adjusted in combination with an LSTM algorithm to ensure that the process is in a diuron thermal stability interval. According to the process, energy consumption and solvent consumption are effectively reduced, solvent residues are reduced, cost reduction and efficiency improvement are achieved, and product competitiveness is improved.

Description

Technical Field

[0001] This invention relates to the field of diuron post-processing technology, and more specifically, to a process for solvent recovery during diuron drying. Background Technology

[0002] Diuron is a substituted urea broad-spectrum herbicide with high efficiency, long-lasting effect, and unique mechanism of action. Its trade name is Karmex, CAS Registry Number is 330-54-1, and its chemical name is N'-(3,4-dichlorophenyl)-N,N-dimethylurea. Its chemical structural formula is shown below:

[0003]

[0004] Diuron, a herbicide widely used in dryland crops such as cotton, corn, soybeans, tea plantations, orchards, and rubber plantations, is a white crystalline solid in its pure form. The industrial grade has a melting point above 135℃ and a vapor pressure of 4.13 × 10⁻⁶ at 50℃. -4 Pa exhibits specific solubility characteristics: readily soluble in hot alcohol, with a solubility of 5.3% in acetone at 27°C, slightly soluble in ethyl acetate, ethanol, and hot benzene, but only 42 ppm in water at 25°C. This substance is stable in air and exhibits low hydrolysis at room temperature, but the hydrolysis rate accelerates significantly under heated and alkaline conditions, and decomposes at 189-190°C. These physicochemical properties impose strict requirements on the drying and solvent recovery processes in its production. Currently, diuron is synthesized industrially using 3,4-dichloroaniline as the starting material, with toluene as the main solvent. However, significant technical defects exist in the post-drying processing: on the one hand, the limited separation efficiency between toluene and diuron results in high solvent residue in the product, affecting product quality; on the other hand, traditional processes, such as flash drying, require operation at high temperatures of 120-150°C, which is close to the thermal decomposition threshold of diuron, severely restricting the market competitiveness of diuron products. Therefore, this invention provides a solvent recovery process for diuron drying to solve the aforementioned technical problems. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a solvent recovery process for diuron drying. This process solves the problems of high energy consumption, high solvent residue, and high toluene consumption in existing diuron production due to the use of toluene as a solvent. It effectively reduces energy consumption and solvent consumption, minimizes solvent residue, achieves cost reduction and efficiency improvement, and enhances product competitiveness.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A process for solvent recovery during diuron drying includes the following steps:

[0008] S1. The wet material produced in the diuron synthesis process is subjected to solid-liquid separation at a pressure of 0.4-0.8 MPa to obtain diuron filter cake, which is then transferred to the feed hopper of a vacuum belt dryer via a closed conveying system.

[0009] S2. Spread the filter cake evenly on the conveyor belt of the vacuum belt dryer with a thickness of 5-15mm, maintain the vacuum degree of the drying chamber at -0.08 to -0.095MPa, control the material layer temperature at 45-52℃, and adjust the conveyor belt speed to 0.8-2.0m / min.

[0010] S3. Transfer the primary dried product obtained from S2 to a far-infrared radiation cavity with a wavelength of 2.5-15 μm and a radiation power density of 0.5-2.0 W / cm². 2 To ensure that the radiation penetration depth is ≥5.0cm, the internal temperature of the material is monitored and maintained at 45-50℃, and continuous irradiation is carried out for 15-20min. The resonance absorption effect of the CH bond in the diuron molecule on a specific wavelength is utilized to promote the diffusion of residual toluene molecules inside the crystal to the surface, while the surface solvent molecules are desorbed under the action of radiative heat.

[0011] S4. The toluene-containing vapor generated during the drying process is introduced into a two-stage condensation system. The first-stage condensation uses a refrigerant at -10 to 0°C, and the second-stage cryogenic condensation uses a cryogenic medium at -40.0 to -35.0°C. The uncondensed gas phase component is introduced into the modified activated carbon adsorption tower at an apparent gas velocity of 0.8-1.2 m / s. The particle size of the modified activated carbon ranges from 1.7 to 4.8 mm.

[0012] S5. A diuron drying kinetic model based on LSTM is used to collect real-time data on material moisture content, gas phase toluene concentration, and material temperature distribution. The moisture content monitoring accuracy is ±0.2%, the toluene concentration monitoring accuracy is ±5ppm, the temperature field distribution is monitored with a resolution of 0.5℃, the system vacuum fluctuation range is dynamically adjusted to ±0.005MPa, the conveyor belt speed adjustment range is ±0.1m / min, and the infrared radiation power change is ±5%, ensuring that the entire drying process is within the diuron thermal stability window of 45-52℃.

[0013] Preferably, the preparation step of the modified adsorbent in step S4 is as follows:

[0014] (1) Dissolve trimethylolpropane, polyethylene glycol monomethyl ether and 2,2-dimethylolpropionic acid in toluene, add p-toluenesulfonic acid and tetrabutyl titanate under nitrogen protection, reflux at 110-120℃ for 4-6 h, and distill under reduced pressure to obtain the intermediate.

[0015] (2) Take the intermediate, 3-mercaptopropionic acid glycidyl ester and 4-dimethylaminopyridine and dissolve them in tetrahydrofuran. Add ascorbic acid and stir the reaction at 25-30℃ for 12-15h. After precipitation, filtration, washing and vacuum drying, the functional additive is obtained.

[0016] (3) Dissolve terephthalic acid, trimesic acid and cerium nitrate in a mixed solvent of DMF and ethylene glycol, react at a constant temperature of 120-130℃ for 20-24h, and then cool, wash, activate by soaking in methanol and vacuum dry. The resulting product is labeled as MOF.

[0017] (4) Take coconut shell activated carbon, immerse it in 7-9% nitric acid solution, stir and oxidize it at 58-65℃ for 0.8-2.5h, filter it and wash it until neutral, then immerse it in 4-7% ammonia solution, stir and treat it at 35-45℃ for 3.5-5h, filter it and wash it with deionized water until neutral, and vacuum dry it to obtain pretreated modified activated carbon.

[0018] (5) Take the pretreated modified activated carbon, immerse it in an ethanol solution containing 5-8wt% functional additives, stir and react at 70-80℃ for 6-8h, filter and wash, add MOF, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, sodium polyacrylate and deionized water, adjust the pH to 4-6, sonicate at 50-60KHz at 45-50℃ for 1-2.5h, filter, wash until neutral, and vacuum dry to obtain modified activated carbon.

[0019] Preferably, in step (1), the ingredients by weight are 0.4-0.6 parts of trimethylolpropane, 3-6 parts of polyethylene glycol monomethyl ether, 3-5 parts of 2,2-dimethylolpropionic acid, 25-30 parts of toluene, 0.05-0.08 parts of p-toluenesulfonic acid and 0.03-0.05 parts of tetrabutyl titanate.

[0020] Preferably, in step (2), the components by weight are 8-12 parts of intermediate, 4-6 parts of glycidyl 3-mercaptopropionate, 0.1-0.3 parts of 4-dimethylaminopyridine, 50-55 parts of tetrahydrofuran and 0.5-0.6 parts of ascorbic acid.

[0021] Preferably, in step (3), the components by weight are 5-7 parts terephthalic acid, 1-3 parts trimesic acid, 12-15 parts cerium nitrate, 63-72 parts DMF and 7-8 parts ethylene glycol.

[0022] Preferably, in step (4), the components by weight are 10-15 parts coconut shell activated carbon, 90-95 parts 7-9% nitric acid solution and 90-95 parts 4-7% ammonia solution.

[0023] Preferably, in step (5), the components by weight are 10-15 parts of pretreated modified activated carbon, 80-90 parts of an ethanol solution containing 5-8 wt% functional additives, 1-3 parts of MOF, 0.5-0.9 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, 0.07-0.087 parts of sodium polyacrylate, and 70-80 parts of deionized water.

[0024] Preferably, the specific conditions for primary drying in step S2 are: vacuum degree of drying chamber -0.08 to -0.095 MPa, material layer temperature 45-52℃, and conveyor belt speed 0.8-2.0 m / min.

[0025] Preferably, in step S3, the wavelength range of the far-infrared radiation is 2.5-15μm, the radiation power density is 0.5-2.0W / cm², the radiation penetration depth is ≥5.0cm, the internal temperature of the material is maintained at 45-50℃, and the irradiation time is 15-20min.

[0026] Preferably, the adjustment accuracy of the drying kinetic model in step S5 is as follows: moisture content monitoring accuracy ±0.2%, toluene concentration monitoring accuracy ±5ppm, temperature field distribution resolution 0.5℃, vacuum degree adjustment fluctuation range ±0.005MPa, conveyor belt speed adjustment range ±0.1m / min, and infrared radiation power change ±5%.

[0027] Preferably, the thermal stability temperature range of diuron is 45-52℃, within which the diuron decomposition rate is ≤0.1wt% and the final product has a toluene residue of ≤75ppm.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. This invention achieves deep dehydration at temperatures far below the decomposition threshold of diuron through the synergistic effect of vacuum belt drying and far-infrared molecular resonance. The vacuum environment significantly lowers the azeotropic point of toluene and water, avoiding the risks of diuron molecular hydrolysis and lattice distortion caused by high temperatures. Far-infrared radiation precisely excites the vibrational resonance of the CH bonds in diuron molecules, promoting the directional migration of residual solvent from the crystal interior to the surface. Simultaneously, radiative heat energy is used to achieve instantaneous desorption of surface solvents. This dual drying mechanism completely solves the problems of solvent encapsulation effect and crystal structure damage caused by traditional high-temperature processes. In addition, a recovery path combining stepped condensation and deep adsorption is adopted to enhance the collection efficiency of gaseous solvents, significantly reducing the environmental escape and process loss of organic solvents. Furthermore, a dynamic control model is constructed based on deep learning algorithms, and through real-time collaborative optimization of multiple parameters, the drying process is precisely maintained within the thermally stable range, ensuring consistent product quality. This process reduces energy consumption per unit product while effectively controlling the residual solvent level in the final product, simultaneously improving solvent recycling rate and optimizing production and operating costs, significantly enhancing the product's market competitiveness.

[0030] 2. This invention prepares intermediates and functional additives from raw materials such as trimethylolpropane and polyethylene glycol monomethyl ether through reaction, and simultaneously synthesizes MOF materials. Coconut shell activated carbon is pretreated by sequential nitric acid oxidation and ammonia treatment, then loaded with functional additives and composited with MOF to obtain modified activated carbon. When this modified activated carbon is used as an adsorbent to treat uncondensed toluene gas phase components, it combines the chemical adsorption sites of the functional additives with the porous adsorption structure of MOF. Through the synergistic effect of physical and chemical adsorption, it enhances the capture capacity of toluene, effectively improving the adsorption efficiency of residual toluene in the exhaust gas, reducing solvent loss, and further increasing the toluene recovery rate. Simultaneously, its stable structural characteristics ensure long-term adsorption performance, reducing the frequency of adsorbent replacement, and forming a highly efficient solvent recovery closed loop with a two-stage condensation system. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the experimental materials used, unless otherwise specified, were all purchased from conventional biochemical reagent stores. All quantitative experiments in the following examples were performed in triplicate, and the data are the average of the three replicates or the average ± standard deviation.

[0033] Polyethylene glycol monomethyl ether, purchased from Tianmen Hengchang Chemical Co., Ltd., product number HC4383;

[0034] Sodium polyacrylate, purchased from Hubei Zhonglong Kangcheng Fine Chemical Co., Ltd., CAS No. RN9003-04-7;

[0035] Coconut shell activated carbon was purchased from Wuhan Penglei Biotechnology Co., Ltd.

[0036] Preparation Example 1

[0037] The preparation steps of the modified adsorbent in step S4 are as follows:

[0038] (1) Dissolve 0.4 parts of trimethylolpropane, 3 parts of polyethylene glycol monomethyl ether and 3 parts of 2,2-dimethylolpropionic acid in 25 parts of toluene, add 0.05 parts of p-toluenesulfonic acid and 0.03 parts of tetrabutyl titanate under nitrogen protection, reflux at 110°C for 6 hours, and distill under reduced pressure to obtain the intermediate.

[0039] (2) Take 8 parts of intermediate, 4 parts of 3-mercaptopropionic acid glycidyl ester and 0.1 parts of 4-dimethylaminopyridine and dissolve them in 50 parts of tetrahydrofuran. Add 0.5 parts of ascorbic acid and stir at 25°C for 15 hours. After precipitation, filtration, washing and vacuum drying, functional additive is obtained.

[0040] (3) Dissolve 5 parts of terephthalic acid, 1 part of trimesic acid and 12 parts of cerium nitrate in a mixed solvent of 63 parts of DMF and 7 parts of ethylene glycol, react at 120°C for 24 hours, and then cool, wash, activate by soaking in methanol and vacuum dry. The resulting product is labeled as MOF.

[0041] (4) Take 10 parts of coconut shell activated carbon, immerse it in 90 parts of 9% nitric acid solution, stir and oxidize at 58°C for 2.5h, filter and wash until neutral, then immerse it in 90 parts of 7% ammonia solution, stir and treat at 35°C for 5h, filter and wash with deionized water until neutral, and vacuum dry to obtain pretreated modified activated carbon.

[0042] (5) Take 10 parts of pretreated modified activated carbon, immerse it in 80 parts of ethanol solution containing 8wt% functional additives, stir and react at 70℃ for 8h, filter and wash, add 1 part of MOF, 0.5 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, 0.07 parts of sodium polyacrylate and 70 parts of deionized water, adjust the pH to 4, sonicate at 50KHz at 45℃ for 2.5h, filter, wash until neutral, and vacuum dry to obtain modified activated carbon.

[0043] Preparation Example 2

[0044] The preparation steps of the modified adsorbent in step S4 are as follows:

[0045] (1) Dissolve 0.6 parts of trimethylolpropane, 6 parts of polyethylene glycol monomethyl ether and 5 parts of 2,2-dimethylolpropionic acid in 30 parts of toluene, add 0.08 parts of p-toluenesulfonic acid and 0.05 parts of tetrabutyl titanate under nitrogen protection, reflux at 120°C for 4 hours, and distill under reduced pressure to obtain the intermediate.

[0046] (2) Take 12 parts of intermediate, 6 parts of 3-mercaptopropionic acid glycidyl ester and 0.3 parts of 4-dimethylaminopyridine and dissolve them in 55 parts of tetrahydrofuran. Add 0.6 parts of ascorbic acid and stir at 30°C for 12 hours. After precipitation, filtration, washing and vacuum drying, functional additive is obtained.

[0047] (3) Dissolve 7 parts of terephthalic acid, 3 parts of trimesic acid and 15 parts of cerium nitrate in a mixed solvent of 72 parts of DMF and 8 parts of ethylene glycol, react at 130°C for 20 h, and then cool, wash, activate by soaking in methanol and vacuum dry. The resulting product is labeled as MOF.

[0048] (4) Take 15 parts of coconut shell activated carbon, immerse it in 95 parts of 7% nitric acid solution, stir and oxidize at 65°C for 0.8h, filter and wash until neutral, then immerse it in 95 parts of 4% ammonia solution, stir and treat at 45°C for 3.5h, filter and wash with deionized water until neutral, and vacuum dry to obtain pretreated modified activated carbon.

[0049] (5) Take 15 parts of pretreated modified activated carbon, immerse it in 90 parts of ethanol solution containing 5wt% functional additives, stir and react at 80℃ for 6h, filter and wash, add 3 parts of MOF, 0.9 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, 0.087 parts of sodium polyacrylate and 80 parts of deionized water, adjust the pH to 6, sonicate at 60KHz at 50℃ for 1h, filter, wash until neutral, and vacuum dry to obtain modified activated carbon.

[0050] Preparation Example 3

[0051] The preparation steps of the modified adsorbent in step S4 are as follows:

[0052] (1) Dissolve 0.6 parts of trimethylolpropane, 4 parts of polyethylene glycol monomethyl ether and 5 parts of 2,2-dimethylolpropionic acid in 30 parts of toluene, add 0.08 parts of p-toluenesulfonic acid and 0.04 parts of tetrabutyl titanate under nitrogen protection, heat to 120°C and reflux for 4 hours, and distill under reduced pressure to obtain the intermediate.

[0053] (2) Take 10 parts of intermediate, 6 parts of 3-mercaptopropionic acid glycidyl ester and 0.2 parts of 4-dimethylaminopyridine and dissolve them in 55 parts of tetrahydrofuran. Add 0.6 parts of ascorbic acid and stir at 30°C for 12 hours. After precipitation, filtration, washing and vacuum drying, functional additive is obtained.

[0054] (3) Dissolve 6 parts of terephthalic acid, 3 parts of trimesic acid and 12 parts of cerium nitrate in a mixed solvent of 70 parts of DMF and 7 parts of ethylene glycol, react at 130°C for 20 h, and then cool, wash, activate by soaking in methanol and vacuum dry. The resulting product is labeled as MOF.

[0055] (4) Take 15 parts of coconut shell activated carbon, immerse it in 90 parts of 8% nitric acid solution, stir and oxidize at 65°C for 1 hour, filter and wash until neutral, then immerse it in 90 parts of 5% ammonia solution, stir and treat at 45°C for 4 hours, filter and wash with deionized water until neutral, and vacuum dry to obtain pretreated modified activated carbon.

[0056] (5) Take 15 parts of pretreated modified activated carbon, immerse it in 80 parts of ethanol solution containing 6wt% functional additives, stir and react at 80℃ for 6h, filter and wash, add 3 parts of MOF, 0.8 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, 0.08 parts of sodium polyacrylate and 80 parts of deionized water, adjust the pH to 6, sonicate at 60KHz at 50℃ for 1.2h, filter, wash until neutral, and vacuum dry to obtain modified activated carbon.

[0057] Comparative Preparation Example 1

[0058] Compared with Preparation Example 3, no functional additives are added in step (5), and the remaining steps and parameters are the same.

[0059] Comparative Preparation Example 2

[0060] Compared with the modified activated carbon 3 prepared in Example 3, no modified activated carbon MOF is added in step (5), and the other steps and parameters are the same.

[0061] Comparative preparation example 3

[0062] Compared with the modified activated carbon 3 prepared in Example 3, the nitric acid oxidation and ammonia treatment in step (4) are omitted, and coconut shell activated carbon is used directly in step (5). The remaining steps and parameters are the same.

[0063] Example 1

[0064] A process for solvent recovery during diuron drying includes the following steps:

[0065] S1. Take the wet material produced in the diuron synthesis process and use a filter press for solid-liquid separation. Set the filter press pressure to 0.4MPa and the filter press time to 30min to obtain diuron filter cake. The filter cake is transferred to the feed hopper of the vacuum belt dryer via a jacketed closed screw conveyor. The temperature of the conveyor jacket is controlled at 30℃. The stirring device in the feed hopper continuously stirs at a speed of 30rpm to prevent the filter cake from clumping.

[0066] S2. The filter cake is evenly spread on the conveyor belt of the vacuum belt dryer with a thickness of 5mm. The vacuum degree of the drying chamber is set to -0.08MPa, the material layer temperature is 45℃, and the conveyor belt speed is 0.8m / min. After drying for 30min, the primary dried product is obtained.

[0067] S3. Transfer the primary dried product to the far-infrared radiation cavity, set the radiation wavelength to 2.5μm, the radiation power density to 0.5W / cm², the radiation penetration depth to 5.0cm, maintain the internal temperature of the material at 45℃, and irradiate continuously for 20min. During this period, monitor the temperature distribution in real time with an infrared thermal imager to ensure that there is no local overheating.

[0068] S4. The toluene-containing vapor generated in S2 and S3 is introduced into a two-stage condensation system. The first-stage condensation uses -10℃ calcium chloride frozen brine, and the second-stage cryogenic condensation uses -40℃ ethylene glycol aqueous solution. The uncondensed gas phase component is introduced into the modified activated carbon adsorption tower prepared in Preparation Example 1 at an apparent gas velocity of 0.8 m / s. The modified activated carbon in the adsorption tower has a particle size of 4.8 mm.

[0069] S5. The LSTM drying kinetic model was activated, and data was collected in real time. The moisture content monitoring accuracy was ±0.2%, the toluene concentration monitoring accuracy was ±5ppm, the temperature field resolution was 0.5℃, the vacuum fluctuation range was dynamically adjusted to ±0.005MPa, the conveyor belt speed was stabilized at 0.8m / min, and the infrared radiation power fluctuation range was ±5%, ensuring the drying process remained within the thermally stable range of 45℃. Testing revealed that this batch of diuron had a moisture content of 0.15% and a toluene residue of 75ppm.

[0070] Example 2

[0071] A process for solvent recovery during diuron drying includes the following steps:

[0072] S1. Take wet material of the same batch of diuron and use a filter press for solid-liquid separation. The filter press pressure is 0.5MPa and the filter press time is 28min to obtain diuron filter cake. The filter cake is transferred to the feed hopper by a closed screw conveyor. The temperature of the conveyor jacket is 32℃. The stirring device in the feed hopper is stirring at a speed of 35rpm.

[0073] S2. The filter cake is evenly spread on the conveyor belt with a thickness of 8 mm. The vacuum degree of the drying chamber is -0.085 MPa, the material layer temperature is 47℃, the conveyor belt speed is 1.0 m / min, and after drying for 26 min, the primary dried product is obtained.

[0074] S3. Transfer the primary dried product to the far-infrared radiation cavity, set the radiation wavelength to 5μm, the radiation power density to 0.8W / cm², the radiation penetration depth to 5.2cm, the material temperature to 46℃, and irradiate continuously for 18min. During this period, the temperature distribution is monitored in real time by an infrared thermal imager to ensure that there is no local overheating.

[0075] S4. The toluene-containing vapors generated in S2 and S3 are introduced into a two-stage condensation system. The first-stage condensation uses -8℃ calcium chloride frozen brine, and the second-stage cryogenic condensation uses -39℃ ethylene glycol aqueous solution. The uncondensed gas phase components are introduced into the modified activated carbon adsorption tower prepared in Preparation Example 1 at an apparent gas velocity of 0.9 m / s. The modified activated carbon in the adsorption tower has a particle size of 4.0 mm.

[0076] S5. Activate the LSTM drying kinetic model, dynamically adjust the vacuum fluctuation range to ±0.005MPa, stabilize the conveyor belt speed at 1.0m / min, and the infrared radiation power fluctuation range to ±5%, ensuring the drying process remains within the thermally stable range of 47℃. Testing revealed that this batch of diuron had a moisture content of 0.18% and a toluene residue of 68ppm.

[0077] Example 3

[0078] A process for solvent recovery during diuron drying includes the following steps:

[0079] S1. Take wet material of the same batch of diuron and use a filter press for solid-liquid separation. The filter press pressure is 0.6MPa and the filter press time is 25min to obtain diuron filter cake. The filter cake is transferred to the feed hopper by a closed screw conveyor. The temperature of the conveyor jacket is 33℃. The stirring device in the feed hopper is stirring at a speed of 40rpm.

[0080] S2. The filter cake is evenly spread on the conveyor belt with a thickness of 10 mm. The vacuum degree of the drying chamber is -0.088 MPa, the material layer temperature is 48℃, the conveyor belt speed is 1.2 m / min, and after drying for 18 min, the primary dried product is obtained.

[0081] S3. Transfer the primary dried product to the far-infrared radiation cavity, set the radiation wavelength to 8μm, the radiation power density to 1.2W / cm², the radiation penetration depth to 5.5cm, the material temperature to 47℃, and irradiate continuously for 17min. During this period, the temperature distribution is monitored in real time by an infrared thermal imager to ensure that there is no local overheating.

[0082] S4. The toluene-containing vapors generated in S2 and S3 are introduced into a two-stage condensation system. The first-stage condensation uses -5℃ calcium chloride frozen brine, and the second-stage cryogenic condensation uses -38℃ ethylene glycol aqueous solution. The uncondensed gas phase components are introduced into the modified activated carbon adsorption tower prepared in Preparation Example 2 at an apparent gas velocity of 1.0 m / s. The modified activated carbon in the adsorption tower has a particle size of 3.5 mm.

[0083] S5. Activate the LSTM drying kinetic model and dynamically adjust various parameters to ensure that the drying process remains within the thermally stable range of 48℃, and that the moisture content, toluene concentration, and temperature field monitoring accuracy all meet the set requirements. Testing revealed that this batch of diuron had a moisture content of 0.12% and a toluene residue of 50 ppm.

[0084] Example 4

[0085] A process for solvent recovery during diuron drying includes the following steps:

[0086] S1. Take wet material of the same batch of diuron and use a filter press for solid-liquid separation. The filter press pressure is 0.7MPa and the filter press time is 20min to obtain diuron filter cake. The filter cake is transferred to the feed hopper by a closed screw conveyor. The temperature of the conveyor jacket is 34℃. The stirring device in the feed hopper is stirring at a speed of 45rpm.

[0087] S2. The filter cake is evenly spread on the conveyor belt with a thickness of 12mm. The vacuum degree of the drying chamber is -0.090MPa, the material layer temperature is 50℃, the conveyor belt speed is 1.5m / min, and after drying for 15min, the primary dried product is obtained.

[0088] S3. Transfer the primary dried product to the far-infrared radiation cavity, set the radiation wavelength to 10μm, the radiation power density to 1.5W / cm², the radiation penetration depth to 5.8cm, the material temperature to 48℃, and irradiate continuously for 16min. During this period, the temperature distribution is monitored in real time by an infrared thermal imager to ensure that there is no local overheating.

[0089] S4. The toluene-containing vapor generated in S2 and S3 is introduced into a two-stage condensation system. The first-stage condensation uses -3℃ calcium chloride frozen brine, and the second-stage cryogenic condensation uses -37℃ ethylene glycol aqueous solution. The uncondensed gas phase component is introduced into the modified activated carbon adsorption tower prepared in Preparation Example 2 at an apparent gas velocity of 1.1 m / s. The modified activated carbon in the adsorption tower has a particle size of 2.5 mm.

[0090] S5. Activate the LSTM drying kinetic model, collect and adjust parameters in real time to ensure that the drying process remains within the thermally stable range of 50℃, and that the fluctuation range of each parameter meets the set requirements. Testing revealed that this batch of diuron had a moisture content of 0.10% and a toluene residue of 55 ppm.

[0091] Example 5

[0092] A process for solvent recovery during diuron drying includes the following steps:

[0093] S1. Take wet material of the same batch of diuron and use a filter press for solid-liquid separation. The filter press pressure is 0.8MPa and the filter press time is 12min to obtain diuron filter cake. The filter cake is transferred to the feed hopper by a closed screw conveyor. The temperature of the conveyor jacket is 38℃. The stirring device in the feed hopper is stirring at a speed of 47rpm.

[0094] S2. The filter cake is evenly spread on the conveyor belt with a thickness of 15mm. The vacuum degree of the drying chamber is -0.095MPa, the material layer temperature is 52℃, the conveyor belt speed is 2m / min, and after drying for 10min, the primary dried product is obtained.

[0095] S3. Transfer the primary dried product to the far-infrared radiation cavity, set the radiation wavelength to 15μm, the radiation power density to 2W / cm², the radiation penetration depth to 6cm, the material temperature to 50℃, and irradiate continuously for 15min. During this period, the temperature distribution is monitored in real time by an infrared thermal imager to ensure that there is no local overheating.

[0096] S4. The toluene-containing vapor generated in S2 and S3 is introduced into a two-stage condensation system. The first-stage condensation uses -10℃ calcium chloride frozen brine, and the second-stage cryogenic condensation uses -40℃ ethylene glycol aqueous solution. The uncondensed gas phase component is introduced into the modified activated carbon adsorption tower prepared in Preparation Example 3 at an apparent gas velocity of 1.2 m / s. The modified activated carbon in the adsorption tower has a particle size of 1.7 mm.

[0097] S5. Activate the LSTM drying kinetic model, collect and adjust parameters in real time to ensure that the drying process remains within the thermally stable range of 52℃, and that the fluctuation range of each parameter meets the set requirements. Testing revealed that this batch of diuron had a moisture content of 0.19% and a toluene residue of 60 ppm.

[0098] Example 6

[0099] A process for solvent recovery during diuron drying includes the following steps:

[0100] S1. Take wet material of the same batch of diuron and use a plate and frame filter press for solid-liquid separation. The filter pressure is 0.8MPa and the filter time is 14min to obtain diuron filter cake. The filter cake is transferred to the feed hopper by a closed screw conveyor. The temperature of the conveyor jacket is 35℃. The stirring device in the feed hopper is stirred at a speed of 45rpm.

[0101] S2. The filter cake is evenly spread on the conveyor belt with a thickness of 12mm. The vacuum degree of the drying chamber is -0.095MPa, the material layer temperature is 50℃, the conveyor belt speed is 1.8m / min, and after drying for 12min, the primary dried product is obtained.

[0102] S3. Transfer the primary dried product to the far-infrared radiation cavity, set the radiation wavelength to 10μm, the radiation power density to 2.0W / cm², the radiation penetration depth to 5.5cm, the internal temperature of the material to 50℃, and irradiate continuously for 18min. During this period, the temperature distribution is monitored in real time by an infrared thermal imager to ensure that there is no local overheating.

[0103] S4. The toluene-containing vapor generated in S2 and S3 is introduced into a two-stage condensation system. The first-stage condensation uses -10℃ calcium chloride frozen brine, and the second-stage cryogenic condensation uses -35℃ ethylene glycol aqueous solution. The uncondensed gas phase component is introduced into the modified activated carbon adsorption tower prepared in Preparation Example 3 at an apparent gas velocity of 1.2 m / s. The modified activated carbon in the adsorption tower has a particle size of 1.7 mm.

[0104] S5. Start the LSTM drying kinetic model, collect and adjust parameters in real time to ensure that the temperature remains stable within the 50℃ thermal stability range throughout the process, and that the fluctuation range of each parameter meets the set requirements. After testing, the moisture content of this batch of diuron is 0.14%, and the toluene residue is 58ppm.

[0105] Comparative Example 1

[0106] The same process steps and parameters as those used for modified activated carbon in Example 6 were employed, except that the modified activated carbon prepared by Comparative Preparation Example 1 was used in step S4. Testing revealed that this batch of diuron had a moisture content of 0.15% and a toluene residue of 135 ppm.

[0107] Comparative Example 2

[0108] The same process steps and parameters as those used for modified activated carbon in Example 6 were employed, except that the modified activated carbon prepared by Comparative Preparation Example 2 was used in step S4. Testing revealed that this batch of diuron had a moisture content of 0.16% and a toluene residue of 128 ppm.

[0109] Comparative Example 3

[0110] The same process steps and parameters as those used for modified activated carbon in Example 6 were employed, except that the modified activated carbon prepared by Comparative Preparation Example 3 was used in step S4. Testing revealed that this batch of diuron had a moisture content of 0.16% and a toluene residue of 142 ppm.

[0111] Comparative Example 4

[0112] The same process steps and parameters as those used for modified activated carbon in Example 6 were employed, except that unmodified coconut shell activated carbon was used directly in step S4. Testing revealed that this batch of diuron had a moisture content of 0.20% and a toluene residue of 205 ppm.

[0113] The solvent recovery process for diuron drying provided by this invention achieves efficient drying and solvent recovery of diuron within the thermal stability range of 45-52℃ through the synergistic effect of vacuum belt primary drying and far-infrared molecular resonance secondary drying, combined with two-stage condensation recovery and deep adsorption treatment with modified activated carbon. Furthermore, it utilizes an LSTM algorithm to dynamically control drying parameters. Based on the data from the examples, the diuron product treated with this process maintains a stable moisture content of 0.10%-0.19%, and the toluene residue is controlled at 50ppm-75ppm, fully meeting the low residue requirements.

[0114] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A solvent recovery process for diuron drying, characterized in that, Includes the following steps: S1. The wet material produced in the diuron synthesis process is subjected to solid-liquid separation to obtain diuron filter cake, which is then transferred to the feed hopper of a vacuum belt dryer via a closed conveying system. S2. The filter cake is evenly spread on the conveyor belt of a vacuum belt dryer with a thickness of 5-15mm, and then dried in a vacuum environment to obtain the primary dried product. S3. The primary dried product is transferred to a far-infrared radiation cavity for secondary drying by far-infrared radiation. The vibrational resonance effect of diuron molecular bonds is used to promote the diffusion of residual toluene inside the product to the surface, while the surface solvent molecules are desorbed under the action of radiant heat. S4. The toluene-containing vapors generated in steps S2 and S3 are introduced into a two-stage condensation system for condensation and recovery, and the uncondensed gaseous components are passed into modified activated carbon for treatment. S5. A drying kinetic model based on the LSTM algorithm is established to collect data on material moisture content, gas phase toluene concentration and material temperature distribution in real time, and dynamically adjust the vacuum degree, conveyor belt speed and far-infrared radiation power to keep the drying process within the thermally stable temperature range of diuron.

2. The solvent recovery process for diuron drying according to claim 1, characterized in that, The specific conditions for primary drying in step S2 are: vacuum degree of drying chamber -0.08 to -0.095 MPa, material layer temperature 45-52℃, and conveyor belt speed 0.8-2.0 m / min.

3. The solvent recovery process for diuron drying according to claim 1, characterized in that, In step S3, the wavelength range of far-infrared radiation is 2.5-15μm, the radiation power density is 0.5-2.0W / cm², the radiation penetration depth is ≥5.0cm, the internal temperature of the material is maintained at 45-50℃, and the irradiation time is 15-20min.

4. The solvent recovery process for diuron drying according to claim 1, characterized in that, The adjustment accuracy of the drying kinetic model in step S5 is as follows: moisture content monitoring accuracy ±0.2%, toluene concentration monitoring accuracy ±5ppm, temperature field distribution resolution 0.5℃, vacuum degree adjustment fluctuation range ±0.005MPa, conveyor belt speed adjustment range ±0.1m / min, and infrared radiation power change ±5%.

5. The solvent recovery process for diuron drying according to claim 1, characterized in that, The preparation steps of the modified adsorbent in step S4 are as follows: (1) Dissolve trimethylolpropane, polyethylene glycol monomethyl ether and 2,2-dimethylolpropionic acid in toluene, add p-toluenesulfonic acid and tetrabutyl titanate under nitrogen protection, reflux the reaction and then distill under reduced pressure to obtain the intermediate. (2) Take the intermediate, 3-mercaptopropionic acid glycidyl ester and 4-dimethylaminopyridine, dissolve them in tetrahydrofuran, add ascorbic acid, stir and react, and then precipitate, filter, wash and vacuum dry to obtain the functional additive. (3) Terephthalic acid, trimesic acid and cerium nitrate were dissolved in a mixed solvent of DMF and ethylene glycol. After reacting at a constant temperature, the mixture was cooled, washed, activated by soaking in methanol and dried under vacuum. The resulting product was labeled as MOF. (4) Take coconut shell activated carbon, immerse it in nitric acid solution, stir and oxidize it, filter and wash it until neutral, then immerse it in ammonia solution, stir and filter it, wash it with deionized water until neutral, and vacuum dry it to obtain pretreated modified activated carbon. (5) Take the pretreated modified activated carbon, immerse it in an ethanol solution containing functional additives, stir and react, filter and wash, then add MOF, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, sodium polyacrylate and deionized water, adjust the pH and sonicate, filter, wash until neutral, and vacuum dry to obtain modified activated carbon.

6. The solvent recovery process for diuron drying according to claim 2, characterized in that, In step (1), the ingredients by weight are 0.4-0.6 parts of trimethylolpropane, 3-6 parts of polyethylene glycol monomethyl ether, 3-5 parts of 2,2-dimethylolpropionic acid, 25-30 parts of toluene, 0.05-0.08 parts of p-toluenesulfonic acid and 0.03-0.05 parts of tetrabutyl titanate.

7. The solvent recovery process for diuron drying according to claim 2, characterized in that, In step (2), the components by weight are 8-12 parts of intermediate, 4-6 parts of glycidyl 3-mercaptopropionic acid, 0.1-0.3 parts of 4-dimethylaminopyridine, 50-55 parts of tetrahydrofuran, and 0.5-0.6 parts of ascorbic acid.

8. The solvent recovery process for diuron drying according to claim 2, characterized in that, In step (3), the components by weight are 5-7 parts terephthalic acid, 1-3 parts trimesic acid, 12-15 parts cerium nitrate, 63-72 parts DMF and 7-8 parts ethylene glycol.

9. The solvent recovery process for diuron drying according to claim 2, characterized in that, In step (4), the components by weight are 10-15 parts coconut shell activated carbon, 90-95 parts 7-9% nitric acid solution and 90-95 parts 4-7% ammonia solution.

10. The solvent recovery process for diuron drying according to claim 2, characterized in that, In step (5), the components by weight are 10-15 parts of pretreated modified activated carbon, 80-90 parts of an ethanol solution containing 5-8 wt% functional additives, 1-3 parts of MOF, 0.5-0.9 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, 0.07-0.087 parts of sodium polyacrylate, and 70-80 parts of deionized water.

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