A heterogeneous continuous dewatering reaction apparatus and process

Abstract

The present application relates to a kind of heterogeneous continuous dewatering reaction device and process, the continuous dewatering reaction device includes continuous dewatering reaction device body, multiple layer stirring paddle, baffle, venting baffle, multi-section jacket, defoaming paddle and motor, multiple layer stirring paddle is spaced apart along stirring shaft, venting baffle is separated to form multiple relatively independent stirring unit, and multi-section jacket is used to segmented heating to reaction system.Heterogeneous material is continuously added from the upper part of device, flows downward under the action of gravity, is fully mixed in each stirring unit and exchanges heat with heating medium, and water generated by reaction is directly vaporized or forms azeotrope steam with water-carrying agent, escapes upward through venting baffle and is discharged from the top of device, and material completing dewatering reaction is continuously discharged from the bottom of device.The present application can realize the continuous dewatering reaction of liquid-liquid two-phase or liquid-liquid solid three-phase system, improve heat and mass transfer efficiency, strengthen vapor-liquid separation effect, reduce energy consumption, and improve production efficiency and continuous production level.

Description

Technical Field

[0001] This application relates to the field of chemical reaction equipment, and in particular to a heterogeneous continuous dehydration reaction device and process. Background Technology

[0002] In chemical reactions, there are many known reactions involving water generation, namely dehydration reactions, such as esterification, nitration, alcohol cyclization, aldol condensation, etc. In a dehydration reaction system, there is an equilibrium between the raw materials and the reaction products. As the reaction proceeds, the reaction rate gradually decreases under the influence of the generated water until an equilibrium is reached, at which point the reaction stops. Therefore, in dehydration reactions, the accumulation of generated water greatly limits the improvement of the reaction yield. In order to improve the reaction yield, technicians often use the following technical means: (1) adding a large amount of solvent to dilute the concentration of water generated in the reaction and reduce the influence of the equilibrium on the reaction; (2) adding a dehydrating agent that is inert to the reaction and removing the water generated in the reaction process by azeotropic distillation.

[0003] Patent CN85109641 discloses an apparatus and method for a dehydration reaction. The apparatus includes a reactor, a preheater, and an evaporator. A compressor compresses the water and organic solvent mixture vapor generated during the dehydration process to increase the heat grade of the vapor, which is then used to heat the evaporator, thereby reducing energy consumption in the dehydration process. Patent CN117138713 discloses a continuous synthesis of 2,5-dihydrofuran from 1,4-butenyl glycol using reactive distillation with a metal oxide catalyst. This patent completes the production of 2,5-dihydrofuran and the separation of the byproduct water within a single reactor. Timely dehydration enhances catalyst activity, thereby increasing product yield. Patent CN117924050 discloses a process for the reactive distillation of isopentenol and isopentenal to prepare 3-methyl-2-buten-1-aldehyde diisopentenyl acetal. Reactive distillation is carried out in a plate or packed column, with the reaction product continuously discharged from the bottom of the column; the water generated in the reaction is continuously collected from the top of the column, thereby increasing product yield. The aforementioned patents involve reaction raw materials that are all liquid phases and miscible with each other. This makes them unsuitable for two-phase (liquid-liquid) or three-phase (liquid-liquid-solid) reaction systems where the raw materials are immiscible. Conventional plate or packed reactive distillation columns cannot guarantee uniform mixing of the reaction raw materials, leading to liquid-liquid phase separation and solid powder deposition. This hinders the reaction and causes blockage of the trays or packing, preventing normal equipment operation. Existing heterogeneous dehydration reactions can only employ batch processes, slowly heating and dehydrating in a stirred tank until the reaction endpoint, resulting in long reaction cycles and low equipment utilization.

[0004] A novel device and process are provided for heterogeneous continuous dehydration reaction systems to ensure the uniformity of mixing during the reaction process and to continuously remove water, thereby ensuring the conversion rate of the reaction process. Summary of the Invention

[0005] In order to improve the technical problems in the prior art, this application provides a heterogeneous continuous dehydration reaction device and process.

[0006] The heterogeneous continuous dehydration reaction apparatus provided in this application adopts the following technical solution: In a first aspect, a heterogeneous continuous dehydration reaction device includes a continuous dehydration reaction device body, a multi-layer stirring paddle, a baffle, a venting baffle, a multi-section jacket, a defoaming paddle, and a motor. The continuous dehydration reaction device has a vertical cylindrical structure, with a feed inlet and a steam outlet at the top and a discharge outlet at the bottom. The motor is located at the top of the continuous dehydration reaction device and drives the vertically arranged stirring shaft to rotate. The multi-layer stirring paddle is fixedly mounted on the stirring shaft and is arranged at intervals along the axial direction of the stirring shaft inside the body of the continuous dehydration reaction device. The ventilation baffles are spaced apart along the height of the continuous dehydration reaction device body, and relatively independent stirring units are formed between adjacent ventilation baffles. The multi-layer stirring paddles are located in each stirring unit. The baffle is disposed on the inner wall of the continuous dehydration reaction device body; The multi-segment jacket is disposed on the outer wall of the continuous dehydration reaction device body and is used to provide heat to the reaction system; The defoaming paddle is mounted on the stirring shaft at the top of the continuous dehydration reaction device and is used to eliminate foam generated during the dehydration process.

[0007] By adopting the above technical solution, a continuous reaction space is constructed using the vertical continuous dehydration reactor body. Through the cooperation of multi-layer stirring paddles and ventilation baffles, the reaction area is divided into multiple relatively independent stirring units, realizing the full mixing, step-by-step transfer, and stable residence of heterogeneous materials in each unit. Baffles suppress the overall rotation of materials, improving stirring efficiency and mass transfer effect. Multi-stage jacketed segmented heating enhances the heat exchange between materials and heating medium, increasing the dehydration rate. At the same time, defoaming paddles promptly break up the foam generated during the reaction, ensuring smooth steam escape, realizing continuous dehydration reaction of liquid-liquid two-phase or liquid-liquid-solid three-phase systems, improving production efficiency, heat and mass transfer performance, and equipment operation stability.

[0008] Optionally, the multi-layered stirring paddle has no fewer than six layers, and the ratio of the spacing between adjacent ventilation baffles to the inner diameter of the continuous dehydration reaction device is 1 / 3 to 1.

[0009] By adopting the above technical solutions, the effective residence time of materials in the reaction device can be increased, improving the mixing uniformity and mass transfer efficiency of the heterogeneous system. At the same time, controlling the distance between adjacent ventilation baffles and the inner diameter of the device within the range of 1 / 3 to 1 helps to form multiple stable stirring units, enhances the vapor-liquid separation effect, and promotes the timely escape of dehydration steam, thereby improving the efficiency of continuous dehydration reaction and the stability of device operation.

[0010] Optionally, the blade diameter of the multi-layer agitator is 1 / 3 to 1 / 2 of the inner diameter of the continuous dehydration reaction device. The multi-layer agitator adopts one or more of the following structures: disc turbine propeller, axial flow propeller, inclined blade propeller, and closed turbine propeller.

[0011] By adopting the above technical solutions, the mixing coverage and energy consumption levels can be balanced, and the material circulation flow capacity can be improved. At the same time, depending on the characteristics of different heterogeneous systems, single or combined structures such as disc turbine propellers, axial flow propellers, inclined blade propellers or closed turbine propellers can be selected to achieve synergistic enhancement of radial and axial flow, enhance liquid-liquid dispersion, solid-liquid suspension and heat and mass transfer effects, thereby improving the efficiency of continuous dehydration reaction and process adaptability.

[0012] Optionally, the ventilation baffle has a central hole at its center for the stirring shaft to pass through, and the radial distance between the outer edge of the central hole and the outer edge of the stirring shaft is not less than 20 mm.

[0013] By adopting the above technical solution, a smooth upward channel can be provided for the steam generated during the dehydration process, reducing gas flow resistance and avoiding steam stagnation and local accumulation. At the same time, the influence of the stirring shaft rotation on airflow is reduced, improving the gas-liquid separation efficiency and the stability of the continuous dehydration reaction.

[0014] Optionally, the ventilation baffle is provided with multiple sieve holes in addition to the central hole, and the total opening rate of the sieve holes is 0 to 10%, and the opening rate of the sieve holes of each ventilation baffle gradually decreases from top to bottom along the body of the continuous dehydration reaction device.

[0015] By adopting the above technical solution, while ensuring the relative independence of each stirring unit, effective penetration and uniform distribution of steam can be achieved. At the same time, the gradual reduction of the sieve opening ratio from top to bottom along the device is conducive to forming a gradient gas guiding effect, reducing the degree of liquid backmixing, promoting the continuous rise and escape of steam, and improving the efficiency of vapor-liquid separation and the stability of continuous dehydration reaction.

[0016] Optionally, the number of multi-segment jackets is two or more, each multi-segment jacket is set independently, and each has a heating medium inlet and a heating medium outlet.

[0017] By adopting the above technical solution, the reaction system can be heated in zones along the height direction and the temperature can be precisely controlled, thereby improving the uniformity of material heating. At the same time, the heating intensity can be flexibly adjusted according to the heat demand of different reaction stages, thereby enhancing heat transfer efficiency, reducing energy consumption, and improving the continuous dehydration reaction rate and the stability of the equipment operation.

[0018] Optionally, the number of baffles is 2 to 6, which are evenly distributed along the inner circumference of the continuous dehydration reaction device body to suppress the overall rotational flow of the reaction system and improve the stirring efficiency.

[0019] By adopting the above technical solutions, the overall rotational flow of materials along the stirring shaft can be effectively suppressed, radial circulation and axial flow can be enhanced, and the degree of stirring turbulence can be increased. At the same time, it can promote the uniform dispersion and full contact of heterogeneous materials, enhance the heat and mass transfer effect, and improve the efficiency of continuous dehydration reaction and the stability of equipment operation.

[0020] Optionally, the defoaming paddle is positioned above the uppermost ventilated baffle, and the defoaming paddle adopts a radial blade structure, a mesh blade structure, or a serrated blade structure.

[0021] By adopting the above technical solutions, foam on the liquid surface can be quickly eliminated, ensuring stable gas-liquid exchange inside the tank and improving the stability of the reaction system.

[0022] Secondly, the heterogeneous continuous dehydration process of the heterogeneous continuous dehydration reactor includes the following steps: S1. Heterogeneous materials enter from the top of the continuous dehydration reaction unit, with the feed position higher than the top ventilation baffle. S2. Heterogeneous materials flow downwards under the action of gravity and are fully mixed by multiple layers of stirring blades in each stirring unit to achieve uniform dispersion of liquid-liquid two-phase or liquid-liquid-solid three-phase systems. S3. Introduce a heating medium into the multi-stage jacket to heat the reaction system in stages, so that the water generated in the reaction is directly vaporized, or the water and the dehydrating agent form azeotropic steam and escape, so as to promote the continuous dehydration reaction. S4. The steam generated during the dehydration process flows upward through the central hole and sieve holes on the ventilation baffle and is discharged from the top of the continuous dehydration reaction unit. The water-carrying agent is condensed and separated and then flows back to the upper part of the unit. S5. The material that has completed the dehydration reaction is continuously discharged from the bottom of the continuous dehydration reaction unit.

[0023] By adopting the above technical solution, this process achieves continuous dehydration based on the device structure. High-level material feeding combined with multi-layer agitators can efficiently disperse multiphase materials and improve contact reaction efficiency. Segmented jackets provide precise temperature control, promoting the vaporization of water or its azeotropic escape with the dehydrating agent, thus positively driving the dehydration reaction. Steam is discharged from the top through the baffle, the dehydrating agent is condensed and recycled, and the material is continuously discharged from the bottom. This process combines the comprehensive advantages of continuous and stable reaction, controllable energy consumption, high raw material utilization, thorough dehydration, and excellent production efficiency.

[0024] Optionally, the heterogeneous material is a liquid-liquid two-phase system or a liquid-liquid-solid three-phase system; the heating medium is one or a combination of two or more of hot water, saturated steam or heat transfer oil.

[0025] By adopting the above technical solutions, various types of heating media, such as hot water, steam, and heat transfer oil, can be flexibly selected to meet different temperature requirements, with strong temperature control adaptability, thereby improving the versatility and adaptability of the device to different operating conditions.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. This device uses a vertical cylinder with multiple layers of ventilation baffles to separate independent stirring units. Combined with multiple layers of stirring paddles and inner wall baffles to enhance the turbulent mixing of multiphase materials, it can stably achieve uniform dispersion of liquid-liquid and liquid-liquid-solid multi-systems, greatly improve heat and mass transfer efficiency, and ensure the smooth and continuous operation of continuous dehydration reaction. 2. The multi-section independent jacket allows for precise temperature control in different zones, and is compatible with various heating media to provide heat as needed. It can vaporize free water or remove it by azeotropic reaction with water-carrying agents to promote the dehydration reaction, and can also adjust the heat load as needed to reduce overall energy consumption, resulting in better uniform heating of materials. 3. The ventilation baffle is equipped with a central hole and a gradient opening screen with a decreasing opening rate from top to bottom. This not only prevents liquid phase backmixing and maintains the independence of each unit reaction, but also reduces the resistance to steam rise, improves the vapor-liquid separation efficiency, and ensures that water vapor is discharged smoothly upward. 4. The top-mounted defoaming paddle can promptly dissolve reaction foam, preventing foam from entraining materials and clogging the gas phase channel, stabilizing the gas-liquid exchange environment, eliminating water-carrying agent losses, and ensuring long-term continuous and stable operation of the device. 5. The specifications and types of the stirring paddles can be flexibly selected. With the optimization of the baffle spacing and aperture parameters, the material residence time and stirring power consumption can be precisely controlled, taking into account both the reaction conversion rate and the economic efficiency of equipment operation. 6. The supporting process enables a continuous process from feeding, reaction, vaporization dehydration, solvent reflux, to finished product discharge. The dehydrated agent is condensed, refluxed, and reused, resulting in high raw material utilization, fewer intermittent switching, and significantly higher efficiency in large-scale production compared to intermittent dehydration equipment. Attached Figure Description

[0027] Figure 1This is a schematic diagram of a heterogeneous continuous dehydration reaction device according to an embodiment of this application.

[0028] Explanation of reference numerals in the attached drawings: 1. Main body of the continuous dehydration reaction device; 2. Multi-layer stirring paddle; 3. Baffle; 4. Ventilation baffle; 5. Multi-section jacket; 6. Defoaming paddle; 7. Motor. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1 This application will be described in further detail.

[0030] The purpose of this application is to provide a continuous dehydration reaction apparatus and process suitable for heterogeneous systems.

[0031] Example 1

[0032] Reference Figure 1 A heterogeneous continuous dehydration reaction device includes a continuous dehydration reaction device body 1, multi-layer stirring paddles 2, baffles 3, venting baffles 4, multi-section jackets 5, defoaming paddles 6, and a motor 7. The continuous dehydration reaction device body 1 is manufactured with a vertical cylindrical structure and can be made of stainless steel 304, stainless steel 316L, or other corrosion-resistant metal materials. The top of the device is provided with a feed inlet and a steam outlet, and the bottom is provided with a discharge outlet. The feed inlet is used to continuously convey heterogeneous reaction materials into the device, the steam outlet is used to discharge the steam generated during the dehydration process, and the discharge outlet is used to continuously discharge the material after the dehydration reaction is completed. The motor 7 is installed on the top of the continuous dehydration reaction device 1 and drives the vertically arranged stirring shaft to rotate through a reduction mechanism. The motor 7 is preferably a variable frequency speed control motor to adapt to the viscosity and residence time requirements of different system materials. The stirring shaft is arranged along the central axis of the device. The multi-layer stirring blades 2 are fixedly installed on the stirring shaft. The multi-layer stirring blades 2 are arranged in six layers, and the blades of each layer are evenly distributed along the axial direction. A relatively independent stirring unit is formed between two adjacent layers of ventilation baffles 4. The ratio of the distance between adjacent ventilation baffles 4 to the inner diameter of the continuous dehydration reaction device body 1 is controlled at about 0.5. The multi-layer impeller 2 adopts a combination of disc turbine impellers and inclined blade impellers. The bottom two layers use disc turbine impellers, the middle three layers use inclined blade impellers, and the top layer uses axial flow impellers. The impeller diameter is about 0.4 times the inner diameter of the reactor. This can not only enhance the liquid-liquid dispersion effect, but also promote the suspension of solid particles and improve the overall mass transfer efficiency of the system. A venting baffle 4 is horizontally installed inside the device and fixedly connected to the inner wall of the continuous dehydration reaction device body 1. A central hole is provided in the center of the venting baffle 4 for the stirring shaft to pass through. A radial gap of no less than 20 mm is reserved between the edge of the central hole and the outer wall of the stirring shaft, allowing steam to flow smoothly upwards through this annular gap. In addition to the venting baffle 4, multiple sieve holes are evenly arranged, with the total opening rate controlled between 0% and 10%. The opening rate of the uppermost baffle is approximately 8%, the second baffle approximately 6%, the third baffle approximately 4%, the fourth baffle approximately 2%, and the lowermost baffle is unperforated. This gradient opening facilitates stable counter-current vapor-liquid flow, improves steam rising efficiency, and reduces liquid backmixing. The baffle 3 is welded and fixed to the inner wall of the continuous dehydration reaction device body 1. In this embodiment, four baffles 3 are provided. The four baffles are evenly distributed along the circumference. The width of the baffle is about 8% of the diameter of the device. The baffle 3 can effectively suppress the overall rotation of the material with the stirring shaft, improve the local shearing effect, and enhance the heat and mass transfer effect. Multiple jackets 5 are installed on the outer wall of the continuous dehydration reactor body 1, independently distributed along the height direction. Each jacket has an independent inlet and outlet for the heating medium. The heating medium can be hot water, saturated steam, or heat transfer oil. By controlling the temperature of each jacket separately, different temperature zones can be formed along the height direction. The temperature of the lower zone is controlled at about 180℃, the middle zone at about 160℃, and the top zone at about 140℃, thereby establishing a stable temperature gradient and improving the driving force of dehydration. The defoaming paddle 6 is installed above the uppermost ventilated baffle 4 and fixed at the top of the stirring shaft. The defoaming paddle 6 adopts a serrated defoaming structure. When the defoaming paddle 6 rotates at high speed, it can break the foam on the liquid surface, reduce foam entrainment, and improve the steam separation efficiency.

[0033] This application also provides a heterogeneous continuous dehydration process based on the above-mentioned device. The process includes the following steps: Step S1: The heterogeneous material to be dehydrated is continuously added from the top of the device. The feed inlet is higher than the top ventilation baffle 4. The material can be a liquid-liquid system or a liquid-liquid-solid system, such as esterification system, polyester system, biodiesel system, resin polycondensation system, etc. Step S2: After the material enters the first mixing unit, it forms a uniformly dispersed state under the action of the multi-layer mixing blades 2. Under the action of gravity, it gradually flows downward and passes through multiple mixing units in sequence. Each mixing unit completes local mixing, heat exchange and dehydration reaction. Step S3: Heat transfer oil is fed into the multi-segment jacket 5 respectively, and the heat required for dehydration is provided through segmented heating. The water generated during the reaction is directly evaporated. For systems using dehydrating agents, azeotropic vapor can be formed, such as by adding dehydrating agents such as toluene and xylene. Step S4: Steam flows upward along the central hole and sieve holes, and finally exits from the top steam outlet. After being condensed by the condenser, it enters the water separator, where the aqueous phase is discharged and the organic water-carrying agent flows back to the top of the device to continue participating in the reaction. Step S5: The product after continuous dehydration is continuously discharged from the bottom outlet, and the whole system realizes continuous feeding, continuous dehydration and continuous discharge.

[0034] Compared with traditional intermittent batch dehydration equipment, this application can significantly improve the production capacity per unit volume, improve heat utilization efficiency, reduce energy consumption, and shorten the production cycle. It is particularly suitable for large-scale industrial continuous production of liquid-liquid two-phase systems and liquid-liquid-solid three-phase systems.

[0035] The device has a built-in multi-layer stirring blade for mixing heterogeneous materials. The multi-layer stirring blade 2 has no less than 6 blade layers, and the blade diameter accounts for 1 / 3 to 1 / 2 of the diameter of the reaction device. The blade type can be one or a combination of disc turbine blade, axial flow blade, inclined blade blade, and closed turbine blade. Ventilation baffles 4 are installed between adjacent blades to divide the reaction device into relatively independent stirring units, so that the continuous dehydration reaction device forms a multi-vessel series flow pattern, thereby ensuring that the material flows downward in the form of a push flow, reducing the adverse effects of excessive residence time distribution on the reaction. The ratio of the distance between adjacent ventilation baffles to the reactor diameter is 1 / 3 to 1. A central hole is opened on the ventilation baffle 4, and the distance between the outer edge of the central hole and the outer edge of the stirring shaft is not less than 20 mm. The central hole is set to facilitate the downward flow of liquid or liquid-solid phase. In addition, multiple sieve holes are opened on the ventilation baffle 4 to facilitate the rise of gas. The opening rate is between 0 and 10%, and the opening rate gradually decreases as the height of the ventilation baffle decreases. The device is equipped with multiple jackets 5, with no fewer than two jackets 5. Hot water, saturated steam, heat transfer oil, etc. can be passed through the multiple jackets 5. The multiple jackets 5 can better control the degree of dehydration. Generally, the upper part of the device produces a larger amount of by-product water and requires a higher amount of steam. The continuous dehydration reactor is particularly suitable for heterogeneous reaction material systems such as liquid-liquid two-phase and liquid-liquid-solid three-phase systems. During operation, heterogeneous materials enter from the top of the reactor, with the feed position higher than the uppermost venting baffle. The materials flow downwards under gravity and are uniformly mixed in each stirring unit by stirring blades, which also enhances the heat transfer between the materials and the heating medium in the jacket. A suitable heating medium is introduced into the jacket of the reactor to directly vaporize the water generated by the reaction or to azeotropically vaporize the water with the dehydrating agent to drive the reaction. The steam generated during the dehydration process rises through the venting baffle and eventually leaves from the top of the device. The dehydrating agent can be returned from the top of the device after phase separation, and the materials that have completed the dehydration reaction are discharged from the bottom of the equipment. Through multi-layer stirring and continuous dehydration, the separation of by-product water is achieved, thereby reducing the impact of by-product water on the reaction process.

[0036] Comparative Example 1: Ketal compounds have developed rapidly in the last decade or so, possessing characteristics such as superior floral fragrance compared to the parent ketone, a wide variety of aroma types, and chemical stability. Among them, acetophenone ethylene glycol ketal is used as a fixative in fruity and woody daily fragrances, and can play a harmonizing role in floral fragrances. The traditional synthesis method of acetophenone ethylene glycol ketal uses a solid acid with an average particle size of 150 μm as a catalyst, acetophenone and ethylene glycol as raw materials, and toluene as a dehydrating agent. The reaction is carried out under stirring and heating under reflux. The batch reaction ends when almost no water is separated. Because the reactants ethylene glycol are incompatible with acetophenone and toluene, and a solid catalyst is present, the entire reaction system is a heterogeneous catalytic reaction. Currently, industrial production can only be carried out intermittently in a stirred tank. During the production process, acetophenone, ethylene glycol, catalyst, and toluene are added to the tank sequentially while stirring is on. The total feeding time is about 1 hour. The molar ratio of acetophenone to ethylene glycol is 1:1.1, the mass ratio of toluene to acetophenone is 0.75:1, and the catalyst accounts for 2% of the total material volume fraction. Then, heating is started and the temperature is gradually increased to the reflux dehydration state, with a heating time of about 0.5 hours. Then, the reaction is carried out for 1.5 hours under reflux dehydration state. The yield of the ketal reaction is 95.6%.

[0037] Example 2

[0038] Acetophenone ethylene glycol ketal is prepared in a continuous dehydration reactor. The reactor consists of a multi-layered agitator, baffles, venting baffles, a multi-section jacket, a defoaming impeller, and a motor. The multi-layered agitator has eight blade layers, with a blade diameter equal to 2 / 5 of the reactor diameter. The blades are six-bladed straight-blade disc turbines. Venting baffles are installed between adjacent blades, with the distance between adjacent baffles being half the reactor diameter. A central hole is formed in each venting baffle, with a 25mm gap between the outer edge of the central hole and the outer edge of the agitator shaft. In addition to the central hole, the venting baffles have multiple sieve holes. The opening rate decreases sequentially with the height of the venting baffle: 10%, 9%, 8%, 7%, 6%, 5%, 4%, and 3%. The continuous dehydration reactor has two jackets, through which saturated steam is introduced.

[0039] Acetophenone, ethylene glycol, toluene, and catalyst are continuously fed from the top of the unit. The molar ratio of acetophenone to ethylene glycol is 1:1.1, the mass ratio of toluene to acetophenone is 0.75:1, and the catalyst accounts for 2% of the total material volume. Toluene, acting as a dehydrating agent, azeotropically reacts with water, becoming a gaseous phase and exiting from the top. After condensation and water separation, it is returned to the top of the unit. The reactants are uniformly mixed in each stirring unit by the action of the impellers, and the reactants pass through each stirring unit sequentially in a near-plug flow pattern, finally exiting from the bottom. The reaction residence time is 1 hour, and the ketal yield is 98.4%.

[0040] Example 3

[0041] Acetophenone ethylene glycol ketal is prepared in a continuous dehydration reactor. The reactor consists of a multi-layered agitator, baffles, venting baffles, a multi-section jacket, a defoaming impeller, and a motor. The multi-layered agitator has 12 layers of blades, with a blade diameter equal to 2 / 5 of the reactor diameter. The agitator is a 6-blade straight-disc turbine. Venting baffles 4 are installed between adjacent blades, with the spacing between adjacent baffles being 1 / 3 of the reactor diameter. Each baffle 4 has a central hole, with a 25mm gap between the outer edge of the central hole and the outer edge of the agitator shaft. In addition to the central hole, the baffles also have multiple sieve holes. The opening rate decreases with the height of the baffles 4, successively increasing to 10%, 9%, 8%, 7%, 6%, 5%, 4%, and 3%. The continuous dehydration reactor has two jackets, through which saturated steam is introduced. Acetophenone, ethylene glycol, toluene, and catalyst are continuously fed from the top of the unit. The molar ratio of acetophenone to ethylene glycol is 1:1.1, the mass ratio of toluene to acetophenone is 0.75:1, and the catalyst accounts for 2% of the total material volume. Toluene, acting as a dehydrating agent, azeotropically reacts with water to form a gas phase, which is discharged from the top. After condensation and water separation, it is returned to the top of the unit. The reactants are uniformly mixed under the action of the stirring blades in each stirring unit. The reactants pass through each stirring unit in a near-horizontal plug flow pattern and are finally discharged from the bottom. The reaction residence time is 1 hour, and the ketal yield is 99.2%. Compared to Comparative Example 1, the continuous dehydration reactor provided in this application can save the feeding and heating time in the intermittent production process, thereby significantly shortening the production cycle and improving production efficiency. Furthermore, the multi-layer stirring paddle design of the continuous dehydration reactor provided by this invention can maintain the reactants and catalyst in a uniformly mixed state, thereby increasing the reaction yield. Moreover, in the continuous dehydration reactor, the heat transfer process is enhanced through multi-layer stirring, accelerating the dehydration rate, thus shortening the reaction residence time from 1.5 hours to 1 hour.

[0042] The implementation principle of the heterogeneous continuous dehydration reaction device and process in this application embodiment is as follows: In this embodiment, a vertical continuous dehydration reaction device body 1 is used to construct a reaction space that flows continuously from top to bottom, so that heterogeneous materials continuously enter from the top of the device under the action of gravity and flow downward step by step; inside the device, through the cooperation of multiple layers of stirring paddles 2 and ventilation baffles 4, the reaction space is divided into multiple relatively independent stirring units, so that the materials complete the dispersion, mixing and mass transfer processes in each unit, thereby improving the uniformity and reaction efficiency of the liquid-liquid two-phase or liquid-liquid-solid three-phase system; Meanwhile, the multi-segment jacket 5 provides segmented heating to different height areas of the device, so that the system forms a stable axial temperature gradient and improves the thermal driving force of the dehydration reaction. The water generated during the reaction is vaporized under the action of heat, or forms azeotropic steam with the water-removing agent. It is smoothly guided from bottom to top through the central hole and sieve structure of the ventilation baffle 4, so as to quickly leave the liquid phase system and continuously promote the dehydration reaction in the direction of generation. In addition, the overall rotational flow of the system is suppressed by the baffle 3, which enhances local turbulence and shearing and improves heat and mass transfer efficiency; the foam enrichment in the upper part is broken up by the defoaming paddle 6 to avoid foam accumulation affecting the steam discharge channel. This application achieves an efficient and stable continuous dehydration reaction process for heterogeneous systems through the synergistic effect of "segmented stirring enhancement + staged heating + directional vapor-liquid flow + continuous feeding and discharging", thereby improving reaction efficiency and industrial continuous production capacity.

[0043] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A heterogeneous continuous dehydration reaction apparatus, characterized in that, It includes the main body of the continuous dehydration reaction device (1), multi-layer stirring paddle (2), baffle (3), ventilation baffle (4), multi-section jacket (5), defoaming paddle (6) and motor (7); The continuous dehydration reaction device body (1) has a vertical cylindrical structure, with a feed inlet and a steam outlet at the top and a discharge outlet at the bottom; The motor (7) is located on the top of the continuous dehydration reaction device body (1) and drives the vertically arranged stirring shaft to rotate; The multi-layer stirring paddle (2) is fixedly mounted on the stirring shaft and is arranged at intervals along the stirring shaft inside the body (1) of the continuous dehydration reaction device; The ventilation baffles (4) are spaced apart along the height direction of the continuous dehydration reaction device body (1), and relatively independent stirring units are formed between adjacent ventilation baffles (4). The multi-layer stirring paddles (2) are located in each stirring unit respectively. The baffle (3) is disposed on the inner wall of the body (1) of the continuous dehydration reaction device; The multi-segment jacket (5) is disposed on the outer wall of the continuous dehydration reaction device body (1) and is used to provide heat to the reaction system; The defoaming paddle (6) is mounted on the stirring shaft on the upper part of the continuous dehydration reaction device body (1) and is used to eliminate the foam generated during the dehydration process.

2. The heterogeneous continuous dehydration reaction apparatus according to claim 1, characterized in that: The multi-layer stirring paddle (2) has no less than six layers, and the ratio of the distance between adjacent ventilation baffles (4) to the inner diameter of the continuous dehydration reaction device body (1) is 1 / 3 to 1.

3. The heterogeneous continuous dehydration reaction apparatus according to claim 1, characterized in that: The blade diameter of the multi-layer stirring blade (2) is 1 / 3 to 1 / 2 of the inner diameter of the continuous dehydration reaction device body (1). The multi-layer stirring blade (2) adopts one or more of the following structures: disc turbine blade, axial flow blade, oblique blade blade, and closed turbine blade.

4. The heterogeneous continuous dehydration reaction apparatus according to claim 1, characterized in that: The ventilation baffle (4) has a central hole for the stirring shaft to pass through, and the radial distance between the outer edge of the central hole and the outer edge of the stirring shaft is not less than 20 mm.

5. The heterogeneous continuous dehydration reaction apparatus according to claim 4, characterized in that: The ventilation baffle (4) has multiple sieve holes in addition to the central hole. The total opening rate of the sieve holes is 0 to 10%, and the opening rate of the sieve holes of each ventilation baffle (4) gradually decreases from top to bottom along the body (1) of the continuous dehydration reaction device.

6. The heterogeneous continuous dehydration reaction apparatus according to claim 1, characterized in that: The number of the multi-segment jackets (5) is two or more, each multi-segment jacket (5) is set independently, and each has a heating medium inlet and a heating medium outlet.

7. The heterogeneous continuous dehydration reaction apparatus according to claim 1, characterized in that: The number of baffles (3) is 2 to 6, which are evenly distributed along the inner circumference of the body (1) of the continuous dehydration reaction device to suppress the overall rotational flow of the reaction system and improve the stirring efficiency.

8. The heterogeneous continuous dehydration reaction apparatus according to claim 1, characterized in that: The defoaming paddle (6) is positioned above the uppermost ventilation baffle (4), and the defoaming paddle (6) adopts a radial blade structure, a mesh blade structure, or a serrated blade structure.

9. A heterogeneous continuous dehydration process based on the heterogeneous continuous dehydration reaction apparatus according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Non-homogeneous materials enter from the top of the continuous dehydration reaction device body (1), and the feed position is higher than the uppermost ventilation baffle (4). S2. The heterogeneous material flows downward under the action of gravity and is fully mixed in each stirring unit by multiple stirring paddles (2) to achieve uniform dispersion of the liquid-liquid two-phase or liquid-liquid-solid three-phase system. S3. Introduce heating medium into the multi-segment jacket (5) to heat the reaction system in segments, so that the water generated by the reaction is directly vaporized, or the water and the dehydrating agent form azeotropic steam and escape, so as to promote the dehydration reaction to continue. S4. The steam generated during the dehydration process flows upward through the central hole and sieve holes on the ventilation baffle (4) and is discharged from the top of the continuous dehydration reaction device body (1). The water-carrying agent is condensed and separated and then flows back to the upper part of the device. S5. The material that has completed the dehydration reaction is continuously discharged from the bottom of the continuous dehydration reaction device body (1).

10. A heterogeneous continuous dehydration process according to claim 9, characterized in that: The heterogeneous material is a liquid-liquid two-phase system or a liquid-liquid-solid three-phase system; the heating medium is one or more of hot water, saturated steam or heat transfer oil.

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