A continuous devolatilization apparatus and process for a phase change polymer solution

Abstract

The application belongs to the technical field of polymer devolatilization, and discloses a continuous devolatilization equipment for phase-change polymer solution, which comprises a first devolatilization device in communication with a polymer solution feeding pipeline, a vacuum lock container, a buffer container, a feeding device, a second devolatilization device and a material storage container; a first valve is arranged on a pipeline between the first devolatilization device and the vacuum lock container; a second valve is arranged on a second discharging pipeline between the vacuum lock container and the buffer container; when the first valve is opened and the second valve is closed, materials in the first devolatilization device are discharged into the vacuum lock container; when the first valve is closed and the second valve is opened, materials in the vacuum lock container are discharged into the buffer container and then into the feeding device and the second devolatilization device. The equipment can realize two-stage continuous devolatilization for high-viscosity materials with phase change, avoid vacuum interference between two-stage equipment, reduce vacuum load and production cost. The application also discloses a continuous devolatilization process for phase-change polymer solution.

Description

Technical Field

[0001] This invention belongs to the field of polymer devolatilization technology, and in particular relates to a continuous devolatilization device and process for a phase change polymer solution. Background Technology

[0002] In the production of low-concentration polymers, removing volatile components from the solution, such as solvents, unreacted monomers, and byproducts (collectively referred to as "low-boiling matter"), is a key step in ensuring product performance. The content of low-boiling matter directly affects the purity, viscosity, mechanical properties, and safety of the polymer. Therefore, the efficiency and quality of the devolatilization process are of paramount importance to polymer products. From the perspective of the devolatilization mechanism, the devolatilization requirements of polymer solutions exhibit significant stage-specific differences: when the content of low-boiling-point substances is high in the early stages, if a single continuous devolatilizer is used to achieve deep devolatilization (requiring ultra-low content of low-boiling-point substances), a high vacuum and high-temperature environment must be maintained. However, the high vacuum state requires a very high vacuum pumping speed, which makes the vacuum equipment a bottleneck in the entire production process, significantly increasing equipment investment and operating costs, and making it difficult to achieve large-scale industrial production. At the same time, as the devolatilization process proceeds, the content of low-boiling-point substances inside the polymer solution gradually decreases, and the material state undergoes significant changes. Specifically, when the initial low-boiling-point substance content is high, the material is in a liquid state, but as low-boiling-point substances are continuously removed, the viscosity of the material continues to increase, and it may even undergo a phase change to transform into a powder. The devolatilization effect of the powder mainly depends on the coordinated control of devolatilization time, vacuum degree, and devolatilization temperature. Existing devolatilization devices are difficult to adapt to this dynamic change in material state, and are prone to problems such as incomplete devolatilization, material blockage, and unstable conveying.

[0003] Existing devolatilization technologies all have significant drawbacks. Some employ intermittent devolatilization methods, which, while ensuring a certain level of effectiveness, suffer from low production efficiency, making them unsuitable for large-scale production. Other continuous devolatilization technologies fail to consider the balance between material phase change and vacuum load, resulting in low devolatilization efficiency, substandard product purity, and excessively high energy consumption of the vacuum equipment, thus hindering industrialization. Furthermore, in some existing two-stage devolatilization technologies, the problem of continuous material transport between equipment with different vacuum levels remains unresolved, further limiting the industrial application of continuous devolatilization processes. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a continuous devolatilization device and process for polymer solutions with phase change, which enables two-stage continuous devolatilization operations for high-viscosity materials undergoing phase change, avoiding mutual vacuum interference between the two stages, thereby reducing vacuum load, lowering production costs, and increasing polymer yield.

[0005] The present invention provides a continuous devolatilization device for a phase change polymer solution, comprising a first devolatilization device, a vacuum-locked container, a buffer container, a feeding device, a second devolatilization device, and a material storage container, which are sequentially connected to the polymer solution feed pipeline.

[0006] A first valve is provided on the first discharge pipeline between the first devouring device and the vacuum-locked container;

[0007] A second valve is provided on the second discharge pipeline between the vacuum-locked container and the buffer container;

[0008] The vacuum level of the second devolatilization device is higher than that of the first devolatilization device, and the temperature of the second devolatilization device is higher than that of the first devolatilization device.

[0009] When the first valve is open and the second valve is closed, the vacuum lock container has the same vacuum level as the first devolatilization device. The material in the first devolatilization device is discharged into the vacuum lock container until the material in the vacuum lock container reaches a preset height. Then the first valve is closed and the second valve is opened.

[0010] When the first valve is closed and the second valve is open, the vacuum level in the vacuum-locked container is the same as that in the buffer container, the feeding device, the second devolatilization device, and the material storage container. The material in the vacuum-locked container is discharged into the buffer container and then sequentially enters the feeding device and the second devolatilization device. After deep devolatilization by the second devolatilization device, the material falls into the material storage container under gravity. After the discharge is completed, the second valve is closed, and then the first valve is opened to start the next cycle.

[0011] Preferably, in the above-mentioned continuous devolatilization equipment with phase change polymer solution, a buffer tank is provided in the first devolatilization device, the buffer tank is used to ensure that the material in the first devolatilization device is continuously discharged when the first valve is closed and the second valve is open.

[0012] Preferably, in the above-mentioned continuous devolatilization equipment for phase change polymer solutions, a material level sensor is also provided inside the vacuum-locked container to detect the material level.

[0013] Preferably, in the above-mentioned continuous devolatilization equipment with phase change polymer solution, the first devolatilization device is a horizontal biaxial self-cleaning reactor, and the second devolatilization device is a horizontal single-axis self-cleaning reactor or a horizontal biaxial self-cleaning reactor.

[0014] Preferably, in the above-mentioned continuous devolatilization equipment for phase change polymer solutions, the vacuum locking container is a vacuum locking chamber with an arch-breaking function and a stirring ribbon.

[0015] Preferably, in the above-mentioned continuous devolatilization equipment for phase change polymer solutions, the buffer container is a buffer vessel with an arch-breaking function and equipped with a stirring screw.

[0016] Preferably, in the above-mentioned continuous devolatilization equipment with phase change polymer solution, the feeding device is a screw feeder with a single screw or twin screw structure.

[0017] Preferably, in the above-mentioned continuous devolatilization equipment for phase change polymer solutions, the material storage container is a material storage tank with an arch-breaking function and equipped with a stirring screw.

[0018] This invention provides a continuous devolatilization process for phase change polymer solutions, utilizing the continuous devolatilization equipment for phase change polymer solutions as described in any of the above claims, comprising:

[0019] The polymer solution continuously enters the first devolatilization unit for most of the volatilization and evaporation, and undergoes a phase change, transforming from a liquid into a powder;

[0020] Open the first valve and close the second valve. The vacuum lock container has the same vacuum level as the first devolatilization device. The powder material in the first devolatilization device is discharged into the vacuum lock container.

[0021] After the material in the vacuum-locked container reaches a preset height, the first valve is closed, and then the second valve is opened. The vacuum degree in the vacuum-locked container is the same as that in the buffer container, the feeding device, the second devolatilization device, and the material storage container. The powder material in the vacuum-locked container is discharged into the buffer container and then sequentially enters the feeding device and the second devolatilization device.

[0022] After the remaining volatiles are deeply devoured using the second devouring device, the material falls into the material storage container under the action of gravity.

[0023] After the material discharge is completed, close the second valve and then open the first valve to start the next cycle.

[0024] Preferably, in the above-mentioned continuous devolatilization process of phase change polymer solution, the operating temperature of the first devolatilization device is 80°C to 300°C and the operating pressure is 5000Pa to 50000Pa, and the operating temperature of the second devolatilization device is 100°C to 350°C and the operating pressure is 50Pa to 5000Pa.

[0025] As described above, the continuous devolatilization device for phase change polymer solutions provided by the present invention has a first valve installed on the first discharge pipeline between the first devolatilization device and the vacuum-locked container; a second valve installed on the second discharge pipeline between the vacuum-locked container and the buffer container; the vacuum degree of the second devolatilization device is higher than that of the first devolatilization device, and the temperature of the second devolatilization device is higher than that of the first devolatilization device; when the first valve is open and the second valve is closed, the vacuum degree of the vacuum-locked container is the same as that of the first devolatilization device, and the material in the first devolatilization device is discharged into the vacuum-locked container until the material in the vacuum-locked container reaches a preset height, after which the first valve is closed, and then the second valve is opened. It is evident that the second valve at this time isolates the adverse effects of the high vacuum degree in the second devolatilization device on the first devolatilization device; and when the first valve is closed and the second valve is closed... When the valve is opened, the vacuum level in the vacuum-locked container, the buffer container, the feeding device, the second devolatilization device, and the material storage container is the same. The material in the vacuum-locked container is discharged into the buffer container and then sequentially enters the feeding device and the second devolatilization device. After deep devolatilization by the second devolatilization device, the material falls into the material storage container under gravity. After the discharge is completed, the second valve is closed, and then the first valve is opened to start the next cycle. It can be seen that the first valve isolates the adverse effects of the vacuum level of the first devolatilization device on the vacuum-locked container, facilitating the smooth falling of the powder material generated by the phase change after devolatilization by the first devolatilization device in the vacuum-locked container. Thus, this equipment can perform two-stage continuous devolatilization operation for high-viscosity materials with phase change, avoiding mutual interference between the vacuum levels of the two equipment, thereby reducing vacuum load, reducing production costs, and increasing polymer yield. The continuous devolatilization process for phase change polymer solutions provided by this invention has the same advantages as the above-described equipment. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of an embodiment of a continuous devolatilization device for a phase change polymer solution provided by the present invention;

[0028] Figure 2 This is an overall schematic diagram of a specific embodiment of a continuous devolatilization device for a phase change polymer solution;

[0029] Figure 3 This is a front cross-sectional view of a buffer tank in a specific embodiment of a continuous devolatilization apparatus for a phase change polymer solution.

[0030] Figure 4 This is a schematic diagram of an embodiment of a continuous devolatilization process for a phase change polymer solution provided by the present invention.

[0031] The annotations in the attached figures are explained as follows:

[0032] 1. Polymer solution feed line; 2. First devolatilization device; 3. Vacuum-locked container; 4. Buffer container; 5. Feeding device; 6. Second devolatilization device; 7. Material storage container; 8. First valve; 9. Second valve; 10. Buffer tank; 11. Material level sensor. Detailed Implementation

[0033] The core of this invention is to provide a continuous devolatilization device and process for polymer solutions with phase change, which can perform two-stage continuous devolatilization operations for high-viscosity materials with phase change in the process, and can obtain a final product with extremely low low-boiling components. It avoids mutual interference between the vacuum of the two-stage equipment, thereby reducing vacuum load, reducing production costs, and increasing polymer yield.

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0035] An embodiment of the continuous devolatilization apparatus for phase change polymer solutions provided by the present invention is as follows: Figure 1 As shown, Figure 1 This is a schematic diagram of an embodiment of a continuous devolatilization device for a phase change polymer solution provided by the present invention. The device may include a first devolatilization device 2, a vacuum-locked container 3, a buffer container 4, a feeding device 5, a second devolatilization device 6, and a material storage container 7, which are sequentially connected to the polymer solution feed line 1. The order of these devices from front to back corresponds to the order in which the material moves. Figure 1 It can also be seen that the material inlet of the vacuum-locked container 3 is located below the material outlet of the first devolatilization device 2, the material inlet of the buffer container 4 is located below the material outlet of the vacuum-locked container 3, the material inlet of the feeding device 5 is located below the material outlet of the buffer container 4, the material inlet of the second devolatilization device 6 is located below the material outlet of the feeding device 5, and the material inlet of the material storage container 7 is located below the material outlet of the second devolatilization device 6. The feeding device 5 can be connected to the feed flange of the second devolatilization device 6 via the discharge flange for a secure connection.

[0036] A first valve 8 is provided on the first discharge pipeline between the first devolatilization device 2 and the vacuum-locked container 3. This first valve 8 can control whether the material can enter the vacuum-locked container 3 from the first devolatilization device 2, and when it is closed, it can prevent the vacuum degree in the first devolatilization device 2 from affecting the environment inside the vacuum-locked container 3.

[0037] A second valve 9 is installed on the second discharge pipeline between the vacuum lock container 3 and the buffer container 4. This second valve 9 can control whether the material can enter the buffer container 4 from the vacuum lock container 3. Moreover, when it is closed, it can prevent the vacuum degree in the second devouring device 6 from affecting the environment inside the vacuum lock container 3. This can effectively prevent the different vacuum degrees in the two devouring devices from affecting each other and achieve an effective vacuum lock function.

[0038] The vacuum degree of the second devolatilization device 6 is higher than that of the first devolatilization device 2. This is because the second devolatilization device 6 is a further deep devolatilization based on the initial devolatilization of the first devolatilization device 2, so a higher vacuum degree is required. The temperature of the second devolatilization device 6 is higher than that of the first devolatilization device 2. This is also in coordination with the vacuum degree, because a higher temperature will allow more components to volatilize, thus facilitating deep devolatilization.

[0039] When the first valve 8 is open and the second valve 9 is closed, the vacuum lock container 3 and the first devolatilization device 2 have the same vacuum level. The material in the first devolatilization device 2 is discharged into the vacuum lock container 3 until the material in the vacuum lock container 3 reaches a preset height. Then the first valve 8 is closed and the second valve 9 is opened. It can be seen that during this process, the higher vacuum level in the second devolatilization device 6 will not affect the operation of discharging into the vacuum lock container 3, thereby effectively preventing communication between the two devices with different vacuum levels.

[0040] When the first valve 8 is closed and the second valve 9 is open, the vacuum level in the vacuum-locked container 3 is the same as that in the buffer container 4, the feeding device 5, the second devolatilization device 6, and the material storage container 7. The material in the vacuum-locked container 3 is discharged into the buffer container 4 and then sequentially enters the feeding device 5 and the second devolatilization device 6. Different conveying flow rates can be achieved by adjusting the rotation speed of the feeding device 5. At this time, the first valve 8 prevents the vacuum in the first devolatilization device 2 from affecting the environment inside the vacuum-locked container 3. After deep devolatilization by the second devolatilization device 6, the material falls into the material storage container 7 under the action of gravity. After the discharge is completed, the second valve 9 is closed, and then the first valve 8 is opened to start the next cycle.

[0041] It should be noted that the first valve 8 and the second valve 9 can be further preferably electric valves, and can be communicatively connected to a central control device. The central control device can then automatically control their opening and closing, eliminating the need for on-site personnel to operate them. Furthermore, the central control device can also be communicatively connected to a remote terminal, allowing the status of both valves to be monitored remotely. A remote control mode can also be set, allowing operators to control the opening and closing of the two valves anytime, anywhere. The devolatilization process using the above equipment can be as follows: The polymer solution enters the first devolatilization device 2, where most of the low-boiling compounds are removed. During this devolatilization process, phase... The liquid transforms into powder, which flows into the vacuum-locked container 3 under gravity. The inlet and outlet pipes of the vacuum-locked container 3 are equipped with a first valve 8 and a second valve 9, respectively. When the material level in the vacuum-locked container 3 is full, the first valve 8 is closed and the second valve 9 is opened. The material enters the buffer container 4 under gravity. The feeder 5 is connected to the bottom of the buffer container 4. The feeder 5 continuously feeds the material into the second devolatilization device 6 for deep devolatilization to remove the remaining volatiles in the polymer powder. After completion, the material falls into the material storage container 7 under gravity. It can be seen that this equipment solves the key problems of phase change treatment, output improvement, deep devolatilization and vacuum load bottleneck.

[0042] As described above, in the embodiments of the continuous devolatilization device for phase change polymer solutions provided by the present invention, a first valve 8 is provided on the first discharge pipeline between the first devolatilization device 2 and the vacuum-locked container 3; a second valve 9 is provided on the second discharge pipeline between the vacuum-locked container 3 and the buffer container 4; the vacuum degree of the second devolatilization device 6 is higher than that of the first devolatilization device 2, and the temperature of the second devolatilization device 6 is higher than that of the first devolatilization device 2; when the first valve 8 is open and the second valve 9 is closed, the vacuum degree of the vacuum-locked container 3 is the same as that of the first devolatilization device 2, and the material in the first devolatilization device 2 is discharged into the vacuum-locked container 3 until the material in the vacuum-locked container 3 reaches a preset height, then the first valve 8 is closed, and then the second valve 9 is opened. It can be seen that the second valve 9 at this time isolates the adverse effects of the high vacuum degree in the second devolatilization device 6 on the first devolatilization device 2; and when the first valve 8 is closed and the second valve 9 is closed, the vacuum degree of the vacuum-locked container 3 is higher than that of the first devolatilization device 2. When valve 9 is opened, the vacuum level in the vacuum-locked container, buffer container 4, feeding device 5, second devolatilization device 6, and material storage container 7 is the same. The material in the vacuum-locked container 3 is discharged into the buffer container 4 and then sequentially enters the feeding device 5 and the second devolatilization device 6. After deep devolatilization by the second devolatilization device 6, the material falls into the material storage container 7 under gravity. After the discharge is completed, the second valve 9 is closed, and then the first valve 8 is opened to start the next cycle. It can be seen that the first valve 8 is used to isolate the adverse effects of the vacuum level of the first devolatilization device 2 on the vacuum-locked container, so that the powder material generated by the phase change after devolatilization by the first devolatilization device 2 in the vacuum-locked container can fall smoothly. Thus, it can be seen that the equipment can perform two-stage continuous devolatilization operation for high-viscosity materials with phase change in the process, avoid mutual interference between the vacuum of the two-stage equipment, thereby reducing vacuum load, reducing production costs, and increasing polymer output.

[0043] refer to Figure 2 and Figure 3 , Figure 2 This is an overall schematic diagram of a specific embodiment of a continuous devolatilization device for phase change polymer solutions. Figure 3 This is a front cross-sectional view of a buffer tank in a specific embodiment of a continuous devolatilization device for a phase change polymer solution. In this specific embodiment, a buffer tank 10 is provided inside the first devolatilization device 2. The buffer tank 10 is used to ensure continuous discharge of material from the first devolatilization device 2 when the first valve 8 is closed and the second valve 9 is open. It can be seen that this buffer tank enables better continuous devolatilization. While the second devolatilization device 6 performs deep devolatilization, the first devolatilization device 2 can also perform preliminary devolatilization and discharge the resulting powdered material into the buffer tank 10, preventing the material from having nowhere to go. After the first valve 8 is subsequently opened, the material in the buffer tank 10 can still be discharged into the vacuum-locked container 3 along with the material in the first devolatilization device 2.

[0044] In another specific embodiment of the aforementioned continuous devolatilization apparatus containing phase change polymer solutions, reference continues... Figure 2 The vacuum-locked container 3 is also equipped with a material level sensor 11 for detecting the material level. This sensor automatically detects the material level within the container and issues an alarm when it reaches the preset height. This allows operators to switch the valves to continue discharging the material. In a further example, the sensor can be connected to the central control unit to transmit the material level in real time, allowing operators to remotely monitor the level. The central control unit can be configured to automatically switch the opening and closing states of the first and second valves when the material level reaches the preset height, proceeding to the next stage of the discharge process. This increases automation and effectively prevents material overflow and other abnormal situations.

[0045] In another specific embodiment of the continuous devolatilization equipment for phase change polymer solutions described above, the first devolatilization device 2 can be a horizontal twin-shaft self-cleaning reactor, which can be equipped with a jacket. The stirring shaft and the blades are filled with a heat transfer medium to give it a large heat exchange area. The self-cleaning hook plays a role in renewing and enhancing mass transfer and heat transfer during operation. It has an excellent devolatilization effect for high-viscosity materials. The loading coefficient can be 0.4 to 0.7. The reserved gas phase space is conducive to the desorption of low-boiling substances. Low-boiling substances are efficiently desorbed through vacuum, which can meet the continuous feeding and discharging of materials and can handle the phase change process. The heating medium can be any one of steam, molten salt and heat transfer oil, preferably heat transfer oil. The top of the first devolatilization device 2 can be equipped with a vacuum hood to increase the gas phase space and further facilitate devolatilization. The vacuum hood is equipped with a gas phase port connected to a vacuum pumping device through a pipeline. The length-to-diameter ratio can be selected as 5. The operating temperature can preferably be 80℃ to 300℃, and the operating pressure can be 5000Pa to 50000Pa. Here, the gas pressure refers to the absolute pressure.

[0046] Furthermore, the aforementioned second devolatilization device 6 can be a horizontal single-shaft self-cleaning reactor or a horizontal twin-shaft self-cleaning reactor. It can be equipped with a jacket, and the stirring shaft and impeller are filled with a heat transfer medium to provide a large heat exchange area. The self-cleaning hook plays a role in renewing and enhancing mass and heat transfer during operation. The loading coefficient can be 0.4 to 0.7. The reserved gas phase space is conducive to the removal of low-boiling substances. The remaining low-boiling substances are continuously removed by high vacuum, which can meet the continuous feeding and discharging of materials and can handle phase change processes. The heating medium can be any one of steam, molten salt, and heat transfer oil, preferably heat transfer oil. A vacuum hood can be set at the top to increase the gas phase space, which is more conducive to devolatilization. The vacuum hood is equipped with a gas phase port connected to a vacuum device through a pipeline. A dust filter can be set inside the vacuum hood to block fine powder of materials. The length-to-diameter ratio can preferably be 5. The operating temperature of the second devolatilization device 6 can preferably be 100℃ to 350℃, and the operating pressure can preferably be 50Pa to 5000Pa. Here, the gas pressure refers to absolute pressure.

[0047] The aforementioned vacuum-locked container 3 can preferably be a vacuum-locked chamber with an arch-breaking function, equipped with a stirring ribbon. It can be a vertical conical-bottom container or a horizontal container. It can be equipped with a stirring ribbon and has an arch-breaking function. Its cylinder can be jacketed. The working temperature and vacuum can be the same as the first devolatilization device 2. The heating medium can be any one of steam, molten salt and heat transfer oil, preferably heat transfer oil. Its top can be equipped with a gas phase port connected to the vacuum pumping device.

[0048] The aforementioned buffer container 4 can preferably be a buffer vessel with an arch-breaking function and a stirring screw. Specifically, it can preferably be a vertical conical bottom container or a horizontal container. It can be equipped with a screw ribbon for stirring and has an arch-breaking function. It can be equipped with a jacket. The working temperature and vacuum are the same as those of the second devolatilization device 6. The heating medium can be any one of steam, molten salt and heat transfer oil, and can be preferably heat transfer oil. The top of the container can be provided with a gas phase port connected to a vacuum pumping device.

[0049] The aforementioned feeding device 5 can preferably be a screw feeder with a single screw or twin screw structure, and can be equipped with a jacket. Its inlet is directly connected to the outlet flange of the buffer container 4, and its outlet is directly connected to the inlet flange of the second devouring device 6. The heating medium can be any one of steam, molten salt, and heat transfer oil, and can preferably be heat transfer oil.

[0050] The aforementioned material storage container 7 can preferably be a material storage tank with an arch-breaking function, equipped with a stirring screw. It can be a vertical conical bottom container with a screw ribbon stirring function. Its cylinder can be jacketed, and a cooling medium is introduced into the jacket. The vacuum is the same as that of the second devolatilization device 6. The cooling medium can be either circulating water or heat transfer oil, preferably circulating water. The top of this material storage container 7 can be provided with a gas phase port connected to the vacuum pumping device.

[0051] An embodiment of the continuous devolatilization process for phase change polymer solutions provided by this invention is as follows: Figure 4 As shown, Figure 4 This is a schematic diagram of an embodiment of a continuous devolatilization process for a phase change polymer solution provided by the present invention. Using the continuous devolatilization equipment for a phase change polymer solution as described above, the process may include the following steps:

[0052] S1: The polymer solution continuously enters the first devolatilization unit for most of the volatilization and evaporation, and undergoes a phase change, changing from a liquid to a powder;

[0053] S2: Open the first valve and close the second valve. The vacuum lock container has the same vacuum level as the first devolatilization device. The powder material in the first devolatilization device is discharged into the vacuum lock container.

[0054] Specifically, since the material inlet of the vacuum-locked container is located below the material outlet of the first devolatilization device, the devolatilized powder polymer will fall into the vacuum-locked container under the action of gravity.

[0055] S3: After the material in the vacuum-locked container reaches the preset height, the first valve is closed and the second valve is opened. The vacuum degree in the vacuum-locked container, the buffer container, the feeding device, the second devolatilization device, and the material storage container is the same. The powder material in the vacuum-locked container is discharged into the buffer container and then enters the feeding device and the second devolatilization device in sequence.

[0056] S4: After the remaining volatile matter is deeply devoured using the second devouring device, it falls into the material storage container under gravity.

[0057] S5: After the material discharge is completed, close the second valve and then open the first valve to start the next cycle.

[0058] It should be noted that the aforementioned polymers can be monomethyl methacrylate (MMA), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyacrylamide, isotactic polypropylene, or polylactic acid (PLA). The low-boiling-point substances in the polymer solution mainly consist of unreacted monomers, solvents, and byproducts, and their mass fraction in the polymer solution can range from 15% to 80%. In existing technologies using continuous devolatilization, achieving ultra-low low-boiling-point content in the final product requires a high vacuum and high-temperature environment. However, when the initial low-boiling-point content is high, this high vacuum requirement necessitates setting a huge vacuum pumping speed for the entire continuous devolatilization unit, resulting in high pressure on the vacuum equipment. This makes the vacuum equipment a bottleneck in the entire technology, hindering industrialization. The process provided in this application employs a two-stage devolatilization method, avoiding the problem of reduced vacuum pump capacity caused by high vacuum and prolonged devolatilization within the same devolatilization device, as in existing technologies, thus facilitating industrialization. Specifically, the process provided in this application involves segmented continuous operation. The first stage of devolatilization is performed under low vacuum, removing a large amount of low-boiling-point substances, which greatly reduces the vacuum load. Only in the second stage of devolatilization is a high vacuum used. Since only a small amount of remaining low-boiling-point substances need to be distilled off at this stage, the vacuum load is relatively small. Furthermore, this process achieves the locking of the two-stage vacuum environment through a vacuum locking chamber, ensuring that the two vacuum stages do not interfere with each other, thus solving the problem of continuous material transport between the two-stage devolatilization devices with different vacuum levels.

[0059] In summary, the above process enables continuous operation, facilitating increased production. The two-stage devolatilization reduces vacuum load, making it more suitable for materials undergoing phase changes and also applicable to the devolatilization of high-viscosity materials. It offers high operational flexibility, allowing the processing of polymer solutions with varying low-boiling-point content by adjusting process parameters.

[0060] In a specific embodiment of the above-described continuous devolatilization process for phase change polymer solutions, the operating temperature of the first devolatilization device is preferably between 80°C and 300°C, and the operating pressure is preferably between 5000 Pa and 50000 Pa. The operating temperature of the second devolatilization device is preferably between 100°C and 350°C, and the operating pressure is preferably between 50 Pa and 5000 Pa. It should be noted that the pressure here refers to absolute pressure, and these temperatures and pressures can be adaptively adjusted according to actual needs; this is not a limitation.

[0061] The above scheme is illustrated with an example below:

[0062] The polymer solution used is 50% monomaleic resin, and the first devolatilization device is a horizontal twin-shaft self-cleaning reactor with a loading volume of 1m³. 3 The heat exchange area is 22.2m². 2The vacuum level is 30 kPa, the operating temperature is 120°C, and heat transfer oil is used to heat the first devolatilization device. The volume of the buffer container and the vacuum locking chamber is 1 m³. 3 The second devolatilization unit is a horizontal, single-shaft, self-cleaning reactor with a volume of 1.5 m³. 3 The heat exchange area is 16m² 2 The vacuum degree is 1000Pa, the working temperature is 160℃, the initial low boiling content is 50%, a phase change occurs after the first stage of devolatilization, the low boiling content is about 5%, and after the second stage of devolatilization, the low boiling content is 700ppm.

[0063] In the comparative example, a single-unit continuous equipment was used, employing only one devolatilization device. The vacuum level was increased to 10 kPa, and the vacuum load was increased by 3 times. However, the content of low-boiling matter after devolatilization was only about 3%, which shows that it has obvious disadvantages.

[0064] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A continuous devolatilization process for a phase change polymer solution, characterized in that, A continuous devolatilization device for a phase change polymer solution is used. The continuous devolatilization device for a phase change polymer solution includes a first devolatilization device, a vacuum-locked container, a buffer container, a feeding device, a second devolatilization device, and a material storage container, which are sequentially connected to the polymer solution feed line. A first valve is provided on the first discharge pipeline between the first devouring device and the vacuum-locked container; A second valve is provided on the second discharge pipeline between the vacuum-locked container and the buffer container; The vacuum level of the second devolatilization device is higher than that of the first devolatilization device, and the temperature of the second devolatilization device is higher than that of the first devolatilization device. The continuous devolatilization process of the phase change polymer solution includes: The polymer solution continuously enters the first devolatilization device for most of the volatilization and evaporation, and undergoes a phase change, transforming from a liquid into a powder; The first valve is opened and the second valve is closed. The vacuum lock container has the same vacuum level as the first devolatilization device, and the powder material in the first devolatilization device is discharged into the vacuum lock container. After the material in the vacuum-locked container reaches a preset height, the first valve is closed, and then the second valve is opened. The vacuum degree in the vacuum-locked container is the same as that in the buffer container, the feeding device, the second devolatilization device, and the material storage container. The powder material in the vacuum-locked container is discharged into the buffer container and then sequentially enters the feeding device and the second devolatilization device. After the remaining volatiles are deeply devoured using the second devouring device, the material falls into the material storage container under the action of gravity. After the material discharge is completed, close the second valve and then open the first valve to start the next cycle.

2. The continuous devolatilization process for phase change polymer solutions according to claim 1, characterized in that, The first devolatilization device is equipped with a buffer tank, which is used to ensure that the material in the first devolatilization device is continuously discharged when the first valve is closed and the second valve is open.

3. The continuous devolatilization process for phase change polymer solutions according to claim 1, characterized in that, The vacuum-locked container is also equipped with a material level sensor to detect the material level.

4. The continuous devolatilization process for phase change polymer solutions according to claim 1, characterized in that, The first devolatilization device is a horizontal biaxial self-cleaning reactor, and the second devolatilization device is a horizontal single-axis self-cleaning reactor or a horizontal biaxial self-cleaning reactor.

5. The continuous devolatilization process for phase change polymer solutions according to claim 1, characterized in that, The vacuum-locked container is a vacuum-locked chamber with a stirring ribbon that has an arch-breaking function.

6. The continuous devolatilization process for phase change polymer solutions according to claim 1, characterized in that, The buffer container is a buffer vessel with an arch-breaking function, equipped with a stirring screw.

7. The continuous devolatilization process for phase change polymer solutions according to claim 1, characterized in that, The feeding device is a screw feeder with a single screw or twin screw structure.

8. The continuous devolatilization process for phase change polymer solutions according to claim 1, characterized in that, The material storage container is a material storage tank with an arch-breaking function, equipped with a stirring screw.

9. The continuous devolatilization process for phase change polymer solutions according to claim 1, characterized in that, The first devolatilization device operates at a temperature of 80°C to 300°C and a pressure of 5000Pa to 50000Pa, while the second devolatilization device operates at a temperature of 100°C to 350°C and a pressure of 50Pa to 5000Pa.

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