A feeding precision control system for synthesizing sulfur dioxide and a process thereof
Patent Information
- Application Number
- CN202610309429.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-13
- Publication Date
- 2026-07-10
Smart Images
Figure CN122352121A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fine chemical synthesis technology, and more specifically to a precise feeding control system and process for synthesizing thiourea dioxide. Background Technology
[0002] Thiourea dioxide is an important chemical reducing product, widely used in textile printing and dyeing, papermaking, and chemical synthesis. In the synthesis reaction of thiourea dioxide, the molar ratio and feeding precision of the raw materials thiourea, hydrogen peroxide, and deionized water directly determine the reaction conversion rate, product yield, production cost, and product quality stability.
[0003] In existing thiourea dioxide synthesis processes, the raw material ratios are mostly determined by experience, and no precise and controllable ratio scheme has been formed. This easily leads to problems such as excessive hydrogen peroxide causing raw material waste, and unreasonable water volume causing the reaction system to become viscous or the materials to be unevenly dispersed. At the same time, the feeding process is mostly controlled by manual operation or conventional metering equipment, resulting in low feeding accuracy and making it impossible to achieve precise addition of raw materials.
[0004] The above problems collectively lead to high raw material losses, low reaction conversion rates, high production costs, and poor product quality consistency.
[0005] In view of this, the present invention is proposed. Summary of the Invention
[0006] The purpose of this invention is to provide a precise feeding control system and process for synthesizing thiourea dioxide in order to solve the problems mentioned in the background art.
[0007] To achieve the above objectives, the present invention specifically adopts the following technical solution: A precise feeding control system for the synthesis of thiourea dioxide includes a control unit, a solid feeding unit, and a liquid feeding unit; The control unit controls the solid feeding unit and the liquid feeding unit according to the molar ratio of the reaction raw materials; wherein the reaction raw materials include thiourea, hydrogen peroxide and deionized water; The solid feeding unit is used to control the amount of thiourea fed, and the feeding accuracy of thiourea is ±0.1%. The liquid feeding unit is used to control the amount of hydrogen peroxide and deionized water fed. The feeding accuracy of hydrogen peroxide is ±0.05%, and the feeding accuracy of deionized water is ±0.1%.
[0008] Preferably, the solid feeding unit includes an anti-bridging silo, a vacuum feeder, and a loss-in-weight metering feeder. The anti-bridging silo is used to store thiourea and prevent thiourea from caking and bridging. The loss-in-weight metering feeder is used to meter and feed the thiourea so that the feeding accuracy of thiourea reaches ±0.1%. The vacuum feeder is used to transport the thiourea from the anti-bridging silo to the loss-in-weight metering feeder.
[0009] Preferably, the liquid feeding unit includes two sets of mass flow meters and volumetric metering tanks, one set of mass flow meters and volumetric metering tanks is used to meter hydrogen peroxide, and the other set of mass flow meters and volumetric metering tanks is used to meter deionized water.
[0010] As having the same inventive concept as the above-described technical solutions, this invention also claims protection for a process employing the precise feeding control system for synthesizing thiourea dioxide as described in any of the above claims, comprising the following steps: S1. After calibrating the precision of the solid feeding unit and liquid feeding unit of the feeding precision control system, add thiourea, hydrogen peroxide and deionized water into the reactor at a molar ratio of 1:1.06~1.08:3.5~4.0, and react at a constant temperature of 25~35℃ for 2.0~2.5h. S2. After aging at 10~15℃ for 0.5~1.0h, vacuum filtration, washing and drying are performed sequentially to obtain thiourea dioxide.
[0011] Preferably, the molar ratio of thiourea, hydrogen peroxide and deionized water is 1:1.07:3.8.
[0012] Preferably, the reaction temperature in S1 is 30°C and the reaction time is 2.2 h.
[0013] Preferably, the aging temperature in S2 is 12h, the aging time is 0.7h, the vacuum filtration temperature is 10~15℃, and the drying temperature is 50~60℃.
[0014] Preferably, the time for adding thiourea, hydrogen peroxide and deionized water into the reactor is 30-40 minutes, and the stirring speed in the reactor is 20-30 r / min.
[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By adopting a precise feeding control system, the feeding accuracy of hydrogen peroxide is ensured to be ±0.05%, and the feeding accuracy of deionized water is ±0.1%, thus guaranteeing the stability and controllability of the reaction system; 2. By limiting the molar ratio of thiourea, hydrogen peroxide, and deionized water to 1:1.06~1.08:3.5~4.0, the problem of excessive hydrogen peroxide easily causing side reactions such as peroxidation and decomposition, leading to a decrease in product content, an increase in impurities, and a deterioration in stability is avoided. At the same time, the problem of too little water causing the system to become viscous, difficult to stir, and local overheating is avoided, as well as the problem of too much water causing the reaction concentration to be too low, the reaction rate to be slow, and the yield to be reduced. 3. The reaction is first carried out at a medium temperature of 25~35℃, without the need for low temperature and additives, which simplifies the process, reduces energy consumption, and improves production safety; then, it is aged at 10~15℃ for 0.5~1.0h, which can promote the full and slow crystallization of thiourea dioxide, so that the crystals grow completely and have uniform particle size, reduce the generation of microcrystals and fine powder, and avoid crystals encapsulating raw materials or impurities; at the same time, it can further improve the reaction conversion rate and product yield, improve crystal flowability and separation performance, and enhance the purity and quality stability of the final product. Attached Figure Description
[0016] Figure 1 This is a flowchart of the precise feeding control system of the present invention. Detailed Implementation
[0017] 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 skilled in the art without creative effort are within the scope of protection of the present invention. The materials and instruments used in the following embodiments are all commercially available.
[0018] Firstly, such as Figure 1 As shown, an embodiment of the present invention provides a precise feeding control system for the synthesis of thiourea dioxide, including a control unit, a solid feeding unit, and a liquid feeding unit.
[0019] The control unit controls the solid feeding unit and the liquid feeding unit according to the molar ratio of the reaction raw materials; wherein the reaction raw materials include thiourea, hydrogen peroxide and deionized water.
[0020] The solid feeding unit is used to control the amount of thiourea fed, and the feeding accuracy of thiourea is ±0.1%. The solid feeding unit includes an anti-bridging silo, a vacuum feeder, and a loss-in-weight metering feeder. The anti-bridging silo is used to store thiourea and prevent thiourea from caking and bridging. The loss-in-weight metering feeder is used to meter and feed thiourea so that the feeding accuracy of thiourea reaches ±0.1%. The range of the loss-in-weight metering feeder is 5~10t, the weighing response time is ≤1s, and the quantitative feeding speed is 0.5~1t / h. The vacuum feeder is used to transport thiourea from the anti-bridging silo to the loss-in-weight metering feeder.
[0021] The liquid dispensing unit controls the dispensing rates of hydrogen peroxide and deionized water. The dispensing accuracy for hydrogen peroxide is ±0.05%, and for deionized water, it is ±0.1%. The unit includes two sets of mass flow meters and volumetric metering tanks. One set is used to meter the hydrogen peroxide, and the other set is used to meter the deionized water. The mass flow metering range is 0~5m.3 / h, metering error ≤0.05%, the uniform dripping acceleration rate of hydrogen peroxide and deionized water is matched with the feeding rate of thiourea.
[0022] The control unit, vacuum feeder, loss-in-weight metering feeder, mass flow meter, and volumetric metering tank are all conventional existing technologies in this field. For example, the control unit uses a DCS automatic control system, model JX-300XP. The control unit is pre-programmed with a reaction raw material ratio calculation model and a real-time feedback adjustment model. The ratio calculation model can automatically calculate the precise feeding amount of thiourea, hydrogen peroxide, and deionized water according to the preset molar ratio of thiourea, hydrogen peroxide, and deionized water according to this invention and generate a feeding command. The real-time feedback adjustment model can receive the real-time feeding data from the loss-in-weight metering feeder, mass flow meter, and volumetric metering tank and perform real-time comparison calculations with the preset feeding amount. The vacuum feeder is model STZK-X5 from Shanghai Shihe Electromechanical Equipment Co., Ltd., the loss-in-weight metering feeder is model Mettler Toledo LIW-2000DHC, the mass flow meter is model Emerson CMF010, and the volumetric metering tank is model Zhongsi Lifu JC-500. Further details will not be provided here.
[0023] Secondly, embodiments of the present invention provide a process for a precise feeding control system for synthesizing thiourea dioxide as described in any of the above claims, comprising steps S1 to S3.
[0024] S1. After calibrating the precision of the solid feeding unit and liquid feeding unit of the feeding precision control system, add thiourea, hydrogen peroxide and deionized water into the reactor at a molar ratio of 1:1.06~1.08:3.5~4.0, and react at a constant temperature of 25~35℃ for 2.0~2.5h. This synthesis process uses a molar ratio of thiourea, hydrogen peroxide, and deionized water of 1:1.06~1.08:3.5~4.0. This avoids the side reactions such as peroxidation and decomposition that can easily occur with excess hydrogen peroxide, leading to decreased product content, increased impurities, and poor stability. Simultaneously, it avoids the problems of excessively low water content causing a viscous system, difficulty in stirring, and localized overheating, as well as excessively high water content causing excessively low reaction concentration, slow reaction rate, and reduced yield. The reaction is carried out at a medium temperature of 25~35℃, eliminating the need for low-temperature treatment and auxiliary agents, simplifying the process, reducing energy consumption, and improving production safety.
[0025] Furthermore, the preferred molar ratio of thiourea, hydrogen peroxide, and deionized water is 1:1.07:3.8; Furthermore, the time for adding thiourea, hydrogen peroxide, and deionized water into the reactor is 30-40 minutes, and the stirring speed in the reactor is 20-30 r / min. Furthermore, the preferred reaction temperature is 30°C and the preferred reaction time is 2.2 h.
[0026] S2. After aging at 10~15℃ for 0.5~1.0h, vacuum filtration, washing and drying are performed sequentially to obtain thiourea dioxide; After the reaction is complete, the reaction system is cooled to 10-15℃ and aged for 0.5-1.0 h. This allows the incompletely crystallized thiourea dioxide component in the reaction system to fully crystallize, resulting in complete crystal growth and uniform particle size. Simultaneously, it allows trace amounts of unreacted raw materials to further complete the reaction, improving product yield. This temperature range avoids crystal dissolution and fine particle size due to excessively high temperatures, and also prevents excessively rapid crystallization, irregular crystal shapes, and impurity inclusions due to excessively low temperatures. Combined with an appropriate aging time, this effectively improves the integrity, uniformity, and flowability of thiourea dioxide crystals, reduces impurity inclusions and moisture content in the product, resulting in thiourea dioxide with high main content and good stability. Furthermore, the aging temperature is preferably 12℃, the aging time is preferably 0.7h, the vacuum filtration temperature is 10~15℃, and the drying temperature is 50~60℃.
[0027] The present invention will be further described below with reference to specific embodiments and comparative examples; Example 1 S1. After calibrating the solid feeding unit and liquid feeding unit of the precise feeding control system, add thiourea, industrial-grade hydrogen peroxide (mass fraction of 30%) and deionized water into a 5000L reactor at a molar ratio of 1:1.06:3.5, and react at a constant temperature of 25℃ for 2.0h. S2. After aging at 10℃ for 0.5h, vacuum filtration, washing and drying were carried out in sequence to obtain thiourea dioxide with a moisture content of 0.05% and a reaction conversion rate of 99.2%.
[0028] Example 2 S1. After calibrating the solid feeding unit and liquid feeding unit of the precise feeding control system, add thiourea, industrial-grade hydrogen peroxide (mass fraction of 30%) and deionized water into a 5000L reactor at a molar ratio of 1:1.08:4.0, and react at a constant temperature of 35℃ for 2.5h. S2. After aging at 15℃ for 1.0 h, vacuum filtration, washing and drying were carried out in sequence to obtain thiourea dioxide with a moisture content of 0.05% and a reaction conversion rate of 99.5%.
[0029] Example 3 S1. After calibrating the solid feeding unit and liquid feeding unit of the precise feeding control system, add thiourea, industrial-grade hydrogen peroxide (mass fraction of 30%) and deionized water into a 5000L reactor at a molar ratio of 1:1.07:3.8, and react at a constant temperature of 30℃ for 2.2h. S2. After aging at 12℃ for 0.7h, vacuum filtration, washing and drying were carried out in sequence to obtain thiourea dioxide with a moisture content of 0.04% and a reaction conversion rate of 99.6%.
[0030] The following is a comparative analysis of Examples 1-3. The data results of Examples 1-3 are shown in Table 1: Table 1 Data Results of Examples 1-3 As shown in Table 1, after calibrating the solid and liquid feeding units of the precision feeding control system, the present invention adds thiourea, industrial-grade hydrogen peroxide (mass fraction of 30%), and deionized water at a molar ratio of 1:1.06~1.08:3.5~4.0, and reacts at a constant temperature of 25~35℃ for 2.0~2.5h; then, after aging at 10~15℃ for 0.5~1.0h, vacuum filtration, washing, and drying are performed sequentially to obtain thiourea dioxide. Among them, the moisture content of thiourea dioxide is ≤0.05% and the reaction conversion rate is ≥99.2%. The moisture content of thiourea dioxide obtained in each example is low and the reaction conversion rate is high. Example 3 is the most preferred embodiment compared to Examples 1-2. Under the conditions of Example 3, the thiourea dioxide obtained by the present invention has the lowest moisture content and the highest reaction conversion rate.
[0031] Comparative Example 1 The difference between this comparative example and Example 1 is that thiourea, industrial-grade hydrogen peroxide (mass fraction of 30%), and deionized water were added in a molar ratio of 1:1.1~1.2:3.0~5.0. Comparative Example 2 The difference between this comparative example and Example 1 is that the reaction temperature in step S1 is set to 10°C. Comparative Example 3 The difference between this comparative example and Example 1 is that the aging process in S2 is not performed. Comparative Example 4 The difference between this comparative example and Example 1 is that: a precise feeding control system was not used, and the traditional weighing method was used for feeding.
[0032] The following is a comparative analysis of Example 1 and Comparative Examples 1-4. The data results for Comparative Examples 1-4 are shown in Table 2: Table 2 Comparative Examples 1-4 Data Results As can be seen from Example 1, Table 2 and Comparative Example 1, the molar ratio of thiourea, industrial-grade hydrogen peroxide (mass fraction of 30%) and deionized water in Comparative Example 1 is 1:1.1~1.2:3.0~5.0. The molar ratio of the feed deviates from the preferred range, resulting in incomplete reaction, decreased reaction conversion rate, and increased moisture content of thiourea dioxide. As can be seen from Example 1, Table 2 and Comparative Example 2, the reaction temperature in step S1 of Comparative Example 2 was too low, which led to a significant decrease in the reaction rate, resulting in an incomplete reaction and a significant decrease in the reaction conversion rate. In addition, the low temperature caused the product crystallization effect to be poor and the moisture content to be too high. As can be seen from Example 1, Table 2 and Comparative Example 3, the omission of aging in step S2 in Comparative Example 3 resulted in insufficient crystallization of the product, making it difficult to remove residual water in the crystals and significantly increasing the water content. At the same time, the lack of aging led to the incomplete conversion of some raw materials, resulting in a decrease in the reaction conversion rate.
[0033] As can be seen from Example 1, Table 2 and Comparative Example 4, Comparative Example 4 uses the traditional weighing method for feeding, which has a large error and causes a significant deviation in the feeding ratio, which in turn leads to a decrease in reaction conversion rate and an increase in moisture content.
[0034] In summary, this invention, on the one hand, ensures the accuracy of hydrogen peroxide addition to ±0.05% and deionized water addition to ±0.1% by employing a precise feeding control system, thus guaranteeing the stability and controllability of the reaction system; on the other hand, by selecting specific molar ratios of reaction raw materials and process parameters, it improves the moisture content of thiourea dioxide and simultaneously increases the reaction conversion rate.
Claims
1. A precise feeding control system for the synthesis of thiourea dioxide, characterized in that, Includes a control unit, a solid feeding unit, and a liquid feeding unit; The control unit controls the solid feeding unit and the liquid feeding unit according to the molar ratio of the reaction raw materials; wherein the reaction raw materials include thiourea, hydrogen peroxide and deionized water; The solid feeding unit is used to control the amount of thiourea fed, and the feeding accuracy of thiourea is ±0.1%. The liquid feeding unit is used to control the amount of hydrogen peroxide and deionized water fed. The feeding accuracy of hydrogen peroxide is ±0.05%, and the feeding accuracy of deionized water is ±0.1%.
2. The precise feeding control system for synthesizing thiourea dioxide as described in claim 1, characterized in that, The solid feeding unit includes an anti-bridging silo, a vacuum feeder, and a loss-in-weight metering feeder. The anti-bridging silo is used to store thiourea and prevent thiourea from caking and bridging. The loss-in-weight metering feeder is used to meter and feed thiourea so that the feeding accuracy of thiourea reaches ±0.1%. The vacuum feeder is used to transport thiourea from the anti-bridging silo to the loss-in-weight metering feeder.
3. The precise feeding control system for synthesizing thiourea dioxide as described in claim 1, characterized in that, The liquid feeding unit includes two sets of mass flow meters and volumetric metering tanks. One set of mass flow meters and volumetric metering tanks is used to meter hydrogen peroxide, and the other set of mass flow meters and volumetric metering tanks is used to meter deionized water.
4. A process employing a precise feeding control system for the synthesis of thiourea dioxide as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. After calibrating the precision of the solid feeding unit and liquid feeding unit of the feeding precision control system, add thiourea, hydrogen peroxide and deionized water into the reactor at a molar ratio of 1:1.06~1.08:3.5~4.0, and react at a constant temperature of 25~35℃ for 2.0~2.5h. S2. After aging at 10~15℃ for 0.5~1.0h, vacuum filtration, washing and drying are performed sequentially to obtain thiourea dioxide.
5. The process for synthesizing thiourea dioxide according to claim 4, characterized in that, The preferred molar ratio of thiourea, hydrogen peroxide, and deionized water is 1:1.07:3.
8.
6. The process for synthesizing thiourea dioxide as described in claim 4, characterized in that, The preferred reaction temperature in S1 is 30℃, and the preferred reaction time is 2.2h.
7. The process for synthesizing thiourea dioxide as described in claim 4, characterized in that, The preferred aging temperature in S2 is 12h, the preferred aging time is 0.7h, the vacuum filtration temperature is 10~15℃, and the drying temperature is 50~60℃.
8. The process for synthesizing thiourea dioxide according to claim 4, characterized in that, The time for adding thiourea, hydrogen peroxide and deionized water into the reactor is 30-40 minutes, and the stirring speed in the reactor is 20-30 r / min.