Small molecule devolatilization reactor

Abstract

The utility model discloses a small molecule devolatilization reactor which comprises an inner cylinder in the shape of a rotating body; the film scraping paddle is located in the inner cylinder, a rotating shaft connected with the film scraping paddle is coaxial with a rotating shaft of the inner cylinder rotating body, and the outer side edge of the film scraping paddle is matched with the inner side wall of the inner cylinder in shape and size. The gap between the outer side edge of the film scraping paddle and the inner side wall of the inner cylinder is not larger than 10 mm. The device further comprises a stirring paddle; the stirring paddle is coaxially connected with the film scraping paddle, and the stirring paddle is positioned below the inner side of the film scraping paddle. And the stirring paddle is spiral, and the action direction of the stirring paddle during working is the circumferential direction and the axial downward direction. The main body of the inner cylinder is a cylinder, and the lower part is a big-end-up cone; the high point of the film scraping paddle is not lower than half of the height of the cylinder, and the low point is not higher than the low point of the cylinder; the low point of the stirring paddle is close to the low point of the cone. The scheme has the beneficial effects that the double advantages of bubbling devolatilization and wiped film devolatilization are combined, and materials can be continuously treated with low consumption and high efficiency.

Description

Technical Field

[0001] This utility model relates to the field of direct processing technology of nylon 6 melt, specifically a small molecule devolatilization reactor for nylon 6. Background Technology

[0002] Nylon 6 (polyamide 6, PA6) is an important variety of chemical fiber and engineering plastic, especially in the chemical fiber field, where it is the second largest category of chemical fibers after polyester fiber in terms of usage. In actual nylon 6 polymer production, the monomer caprolactam hydrolysis polymerization method is mostly used. The product contains approximately 10% unreacted monomers, oligomers, and byproducts, collectively known as hot water extractables. These small molecules often have a certain impact on subsequent processing (spinning, film stretching, injection molding, etc.) and product quality. Currently, industrially, after polymerization, the melt is cooled and pelletized, and then the pellets undergo multi-stage hot water extraction and drying to remove most of the small molecule monomers and oligomers. The extract is then reused, and the small molecules in the extract are concentrated, cracked, and reused. This production method results in huge energy consumption, land and water waste, and high levels of waste gas, wastewater, and solid waste emissions.

[0003] Chinese patent document CN215855860U disclosed on February 18, 2022, "A Nylon 6 melt fine devolatilization device", comprising: a shell; an upper sealing plate covering the opening at the top of the shell; a melt feed pipe disposed on the upper sealing plate; a devolatilization distribution plate disposed inside the shell, the devolatilization distribution plate dividing the shell into upper and lower parts of a melt distribution chamber and a vacuum devolatilization chamber; a plurality of devolatilization holes distributed on the devolatilization distribution plate; a vacuuming mechanism; a heating mechanism; and a melt outlet disposed at the bottom of the shell.

[0004] The melting point of caprolactam monomer is 68-71℃, and its boiling point is 268℃. Nylon 6 spinning temperature is generally around 260℃. During spinning, the monomer vaporizes at the spinneret and creates weak points in the fiber, causing stress concentration during stretching and leading to fiber breakage. This significantly hinders the continuous production of nylon 6 filaments. Currently, nylon 6 fibers are produced using an intermittent spinning process involving dry chips after extraction. To achieve continuous production from polymerization to spinning, the most crucial aspect is reducing the content of small molecules in the melt. A devolatilization reactor can achieve the devolatilization of small molecules in the melt, making it a feasible method for direct spinning of nylon 6 melt, eliminating the energy-intensive processes of extraction, drying, chipping, and remelting. Devolatilization methods generally include foaming devolatilization and diffusion devolatilization. Foaming devolatilization is faster but requires a faster melt surface renewal rate to increase its rate, while subsequent diffusion devolatilization directly affects the final content of small molecules and product quality. Diffusion devolatilization is a homogeneous process, and the devolatilization efficiency is controlled by the diffusion mass transfer of volatiles. This requires both a rapid surface renewal rate and a thin film to accelerate molecular diffusion devolatilization. During this process, the viscosity of the polymer melt continuously increases with the devolatilization of smaller molecules, leading to decreased melt flowability and making the devolatilization of smaller molecules increasingly difficult. Summary of the Invention

[0005] Based on the above problems, this utility model provides a small molecule devolatilization reactor, which improves the structure of the traditional devolatilizer to reduce the motor power, while having a higher surface renewal rate and film area. It can be combined with different devolatilization methods to enhance the devolatilization reaction and improve and optimize the devolatilization efficiency.

[0006] To achieve the purpose of this invention, the present invention adopts the following technical solution: a small molecule devolatilization reactor, comprising:

[0007] The inner cylinder is a rotating body.

[0008] The scraper is located inside the inner cylinder. The rotating shaft connected to the scraper is coaxial with the rotating shaft of the inner cylinder, and the outer edge of the scraper is adapted to the shape, size, and clearance of the inner wall of the inner cylinder.

[0009] Preferably, the gap between the outer edge of the scraper and the inner wall of the inner cylinder is no more than 10 mm.

[0010] Preferably, the device also includes an agitator; the agitator is coaxially connected to the scraper, and the agitator is located below and inside the scraper.

[0011] Preferably, the impeller blades are spiral-shaped, rotating around an axis during operation, with the force applied in the axial downward direction.

[0012] Preferably, the inner cylinder is a cylinder with a cone-shaped lower part that is wider at the top and narrower at the bottom; the highest point of the scraper is not lower than half the height of the cylinder, and the lowest point is not higher than the lowest point of the cylinder; the lowest point of the agitator is close to the lowest point of the cone.

[0013] Preferably, the device also includes a distributor located above the scraper blade. The distributor is a cone with its bottom facing down, and the axis of the cone is coaxial with the rotation axis connected to the scraper blade.

[0014] Preferably, it also includes a material inlet; the lower end of the material inlet is connected to the tip of the cone-shaped distributor.

[0015] Preferably, the gap between the outer edge of the stirring paddle and the inner wall of the cone is 5~10cm.

[0016] Preferably, it also includes a jacket covering the outside of the inner cylinder; the heat transfer medium outlet is located above the jacket, and the heat transfer medium inlet is located below the jacket.

[0017] Preferably, the inner cylinder is provided with a vacuum port.

[0018] Preferably, the inner cylinder is equipped with a protective gas inlet.

[0019] The beneficial effects of this plan are:

[0020] (1) A scraper was added to artificially create a liquid film of the material, and the small molecules in the material were efficiently and in large quantities removed by scraping and devolatilization. During the continuous reaction devolatilization process, there is a certain liquid level in the reactor. The material is carried to the inner wall of the inner cylinder by stirring and rotating to form a film. Under high temperature and low pressure conditions, the small molecules are rapidly foamed or diffused and overflowed to achieve the purpose of efficient removal.

[0021] (2) Using a spiral agitator promotes uniform mixing of materials in the reactor and also promotes the rate of devolatilization. It has the advantage of promoting the discharge of high-viscosity melt after devolatilization, while also reducing stirring resistance and saving energy.

[0022] (3) The distributor adopts the throwing method, which throws the material onto the inner wall of the inner cylinder under centrifugal action, so that the film can be initially formed and the removal operation can begin immediately. It is highly efficient and does not affect the material that has already been removed. Therefore, this scheme can continuously feed and discharge materials, and its efficiency is much higher than that of the pulse discharge method. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of this utility model;

[0024] Figure 2 This is a schematic diagram of the stirring and scraping film devolatilization device of this utility model;

[0025] Figure 3This is a schematic diagram of the inner cylinder structure in this utility model;

[0026] Figure 4 This is a schematic diagram of the jacket structure in this utility model.

[0027] The components are as follows: 1. Inner cylinder; 101. Vacuum port; 102. Material inlet; 103. Protective gas inlet; 104. Material outlet; 2. Jacket; 201. Heat transfer medium outlet; 202. Heat transfer medium inlet; 3. Distributor; 4. Scraper; 5. Agitator; 6. Support; 7. Ear; 8. Thermometer; 9. Sight glass. Detailed Implementation

[0028] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0029] Example 1

[0030] Example 1 is a small molecule devolatilization reactor applied in a chemical fiber production enterprise. This example of a small molecule devolatilization reactor includes an inner cylinder 1 and a scraper blade 4.

[0031] See Figure 3 As shown, the inner cylinder 1 is designed as an ingenious openable and sealing structure. Its overall shape is that of a rotating body that can flexibly rotate around a vertical central axis. Specifically, this rotating body resembles a perfect sphere, which is not only aesthetically pleasing but also easy to operate. Above the sphere, a matching spherical cap is cleverly installed. This cap also has the dual functions of being openable and sealing, ensuring the airtightness and safety of the inner cylinder 1 during operation.

[0032] The main body of the inner cylinder 1 is meticulously crafted from high-quality stainless steel, a material renowned for its exceptional chemical stability, capable of maintaining stable performance under various complex environments. Particularly noteworthy is the high-standard polishing process applied to the inner wall of the inner cylinder 1, resulting in a mirror-like surface that significantly reduces the likelihood of material adhesion, thereby ensuring the purity and efficiency of material processing.

[0033] A cleverly designed inlet is located at the top of the cover to receive and introduce the material to be processed. Specifically, the material inlet 102 is designed to ensure both smooth material introduction and a tight seal, guaranteeing the smooth operation of the entire processing. In this example, the material to be processed is nylon 6 melt containing a large number of small molecule impurities. This material is precisely introduced into the inner cylinder 1 through the material inlet 102, preparing it for subsequent processing steps.

[0034] At the lowest point of the inner cylinder 1, a material outlet 104 is cleverly designed. This design not only facilitates the smooth discharge of processed materials but also effectively avoids material residue and waste during the discharge process. Through the material outlet 104, the processed nylon 6 melt is discharged cleanly and efficiently, providing strong support for subsequent production processes.

[0035] See Figure 2 As shown, the scraper blade 4 is securely connected to the stirring shaft, which is meticulously designed to ensure precise coaxiality with the rotation axis of the inner cylinder 1. This design not only guarantees stable operation of the equipment but also significantly improves the working efficiency of the scraper blade 4. Simultaneously, the outer edge of the scraper blade 4 is precision-machined to perfectly match the shape and dimensions of the inner wall of the inner cylinder 1, forming a micro-gap fit. This means that during the rotation of the scraper blade 4, the outer edge of its blade remains in close contact with the inner wall of the inner cylinder 1, maintaining only a tiny gap to maximize the scraping effect.

[0036] In this example, the scraper blade 4 is cleverly designed with three blades. These three blades are arranged at equal angles on the circumference, which not only ensures the uniformity of the scraping but also improves the mixing efficiency. In addition, the scraper blade 4 is also made of highly polished stainless steel. This material not only has excellent corrosion resistance and wear resistance but also further reduces the adhesion of materials to the blade surface, ensuring the smooth progress of the scraping process.

[0037] During operation, the material to be processed is introduced into the inner cylinder 1 through the material inlet 102. Driven by the motor, the material is scraped against the inner wall of the inner cylinder 1 by the rotation of the scraper blade 4, forming a thin and uniform film. The liquid surface area is greatly expanded. Under high vacuum, small molecules mixed in the material to be processed can quickly leave the liquid and form a gaseous state, thereby achieving the removal operation. As the scraper blade 4 continues to rotate, the processed material is continuously scraped into a film to remove small molecules. The processed material is then discharged downstream through the material outlet 104 for use.

[0038] This embodiment also features a structural variation where the scraper 4 is fixed, while the inner cylinder 1 rotates around its axis. Those skilled in the art can also use this solution if they have specific design requirements; both methods achieve comparable technical results.

[0039] Example 1 is the most basic configuration of this solution, and subsequent examples are further optimizations and evolutions of Example 1.

[0040] Example 2

[0041] Example 2 is another small molecule devolatilization reactor, which was applied in a chemical fiber production enterprise.

[0042] See Figure 3As shown, in this embodiment, the shape of the inner cylinder 1 has changed significantly compared to Embodiment 1. Its main body is a standard cylindrical shape, a design that not only facilitates stable material flow but also improves the equipment's processing capacity. Below the cylinder, it cleverly transitions into a cone shape with the tip pointing downwards. This design helps the material to drain smoothly during the mixing process, reducing residue and maintaining the material's heating effect. The spherical cap-shaped top cover is retained, maintaining the integrity of the equipment and ensuring the sealing of the mixing process.

[0043] See Figure 2 As shown, in conjunction with the specially shaped inner cylinder 1, the outer edge of the scraper blade 4 is designed with a vertical micro-gap to closely adhere to the inner wall of the inner cylinder 1, ensuring that the blade can tightly and effectively scrape off the material adhering to the inner wall during the scraping process. It is worth noting that the high point of the scraper blade 4 is carefully set, slightly higher than half the height of the inner cylinder 1, while the low point is slightly lower than the lower end of the cylindrical inner cylinder 1. This layout ensures that the blade can fully cover the inner wall of the inner cylinder 1, leaving no blind spots.

[0044] Crucially, the gap between the outer edge of the scraper blade 4 and the inner wall of the inner cylinder 1 in this example is strictly controlled to be no more than 10mm, and in this example it is precisely controlled to be 3mm. Such a small gap not only ensures the thoroughness of the scraping, but also avoids the problem of material accumulation caused by excessive gap, further improving the overall performance of the equipment.

[0045] Furthermore, this embodiment cleverly incorporates a stirring paddle 5 to further optimize the mixing effect. The stirring paddle 5 is also coaxially arranged with the scraper paddle 4, but its position is carefully positioned below and inside the scraper paddle 4, roughly corresponding to the conical portion of the inner cylinder 1 in this example. This layout design aims to ensure the uniformity of material mixing within the conical region, avoiding potential sedimentation or agglomeration in this area. Through the rotation of the stirring paddle 5, the material within the conical region can be effectively agitated and mixed, thereby improving the efficiency and effectiveness of the entire mixing process.

[0046] In this embodiment, a vacuum port 101 is specially added to the upper cover of the inner cylinder 1, a unique design. The main function of the vacuum port 101 is to depressurize the inner cylinder 1, creating an environment conducive to the escape of small molecules by reducing the working pressure inside the inner cylinder 1. Under such low-pressure conditions, small molecules can boil and escape from the material at a lower temperature, which greatly improves the efficiency and effectiveness of the removal operation.

[0047] Same as Example 1.

[0048] Example 3

[0049] Example 3 is another small molecule devolatilization reactor, which was applied in a chemical fiber production enterprise.

[0050] The most significant improvement in this embodiment is:

[0051] 1. A refined adjustment was made to the equipment layout, cleverly placing the material inlet 102 as close as possible to the axis of the inner cylinder 1. This design detail can be found in [reference needed]. Figure 1 As shown. This layout not only optimizes the path of materials entering the inner cylinder, but also ensures that materials can flow more directly and efficiently to the core processing area of ​​the equipment;

[0052] 2. An innovative distributor 3 is installed on the rotating shaft of the scraper paddle 4. This unique design is described in [reference needed]. Figure 2 As shown, the distributor 3 adopts a conical design, with the cone tip facing upwards and the base facing downwards. It is stably fixed at a position slightly above the rotating shaft and is coaxial with the rotating shaft of the scraper blade 4. The significance of this design is that when the material to be treated is introduced from the material inlet 102, the distributor 3 will also rotate along with the rotating shaft. When the material flows onto the conical surface of the distributor 3, it will be subjected to a strong centrifugal force, and will be evenly thrown to the periphery, naturally adhering to the inner wall of the inner cylinder 1 to form a uniform material film. This innovative design not only significantly advances the film formation time of the material, but also greatly increases the time window for the escape of small molecule impurities, thereby greatly improving the efficiency and effect of the removal operation. At the same time, throwing the material onto the inner wall of the inner cylinder 1 can also significantly reduce the rotational resistance of the scraper blade 4, which helps to save energy.

[0053] It should be noted that the optimal location for the material inlet 102 is directly above the cone tip of the distributor 3. For example, the upper section of the rotating shaft can be made into a hollow tube, and the material inlet 102 can be directly connected to the hollow tube. In this example, the location as close as possible to the axis of the inner cylinder 1 was chosen only due to the cost of parts processing. When implementing this solution, those skilled in the art should still recommend that the lower opening of the material inlet 102 be as close as possible to the cone tip of the distributor 3 to obtain the most uniform material ejection and film formation effect.

[0054] In addition, a thermometer 8 is installed in the lower conical part of the inner cylinder 1 to facilitate the observation and monitoring of the working temperature inside the inner cylinder 1.

[0055] In this example, a protective gas inlet 103 is also provided on the upper side wall of the cylindrical inner cylinder 1 for introducing a protective gas, such as nitrogen used in this embodiment.

[0056] In this example, two viewing mirrors 9 are also symmetrically placed on the inner cylinder 1 to observe the reaction inside the inner cylinder 1.

[0057] Same as Example 2.

[0058] Example 4

[0059] Example 4 is another small molecule devolatilization reactor, which was applied in a chemical fiber production enterprise.

[0060] This embodiment has two main improvements:

[0061] 1. To optimize the mixing effect and improve the efficiency of material handling, the mixing paddle 5 is carefully designed as a spiral mixing paddle. See [link / reference] Figure 2 As shown, its blades are single-bladed and arranged in a precise spiral pattern. During operation, the stirring paddle 5 rotates in a circular motion. This rotation not only drives the materials being stirred to move in a circular motion synchronously, but more importantly, it also promotes the materials to move primarily axially downwards. This unique design aims to achieve multiple objectives: firstly, to ensure uniform mixing of the deglossing materials, guaranteeing consistent product quality; secondly, to enhance the surface renewal rate of the materials, facilitating the expulsion of small molecules; and thirdly, to provide the materials with a continuous and stable downward force, ensuring continuous and stable output from the equipment.

[0062] Furthermore, the shape and dimensions of the rotating body of the stirring paddle 5 are precisely adapted to match the lower conical shape of the inner cylinder 1 to ensure smooth and efficient mixing. A reasonable gap is maintained between the outer edge of the stirring paddle 5 and the inner wall of the cone; this gap is set to 5-10 cm, and in this example, the actual gap is 5 cm. This design not only reduces resistance during mixing but also ensures that the stirring paddle 5 can fully cover all parts of the cone. In addition, the lowest point of the stirring paddle 5 is cleverly positioned close to the lowest point of the cone. This detail ensures that there are no dead corners during mixing, thereby further improving the uniformity and efficiency of mixing and promoting foaming and volatilization effects.

[0063] 2. The design of adding a jacket 2 has been improved, such as... Figure 4 As shown, the jacket 2 tightly covers the outer side of the inner cylinder 1, forming a protective outer layer. To ensure a stable connection between the jacket 2 and the inner cylinder 1, the two are connected and fixed by several sturdy support members 6. These support members not only enhance the stability of the structure, but also form a void layer between them, providing space for the flow of the heat transfer medium.

[0064] In the design of jacket 2, the flow path of the heat transfer medium was specifically considered. A heat transfer medium inlet 202 is cleverly positioned at a lower point below jacket 2, while a heat transfer medium outlet 201 is positioned at a higher point above it. This arrangement allows the heat transfer medium to circulate smoothly between the jacket 2 and the inner cylinder 1. Through the heat transfer medium inlet 202, a heat exchange medium, such as the hydrogenated terphenyl used in this example, can be introduced into this jacket. During circulation, this heat exchange medium effectively transfers heat to the inner cylinder 1, thereby achieving the function of heating or insulating the inner cylinder 1, precisely controlling the internal operating temperature of the inner cylinder 1, and meeting different process requirements.

[0065] All the auxiliary parts on the inner cylinder 1 mentioned above extend outside the jacket 2, and will not be described in detail again.

[0066] In addition, to enhance the stability of the entire structure and facilitate installation and fixing, several lugs 7 are specially provided on the outer wall of the jacket 2. These lugs not only provide additional support points for the jacket 2, but also make the entire device more convenient and safer to install and maintain.

[0067] Same as Example 3.

[0068] This embodiment is a more complete preferred embodiment of the proposed solution. For the final structure, please refer to [link / reference]. Figure 1 As shown.

[0069] The workflow of this embodiment is roughly as follows:

[0070] The nylon 6 melt to be processed is continuously and stably introduced into the inner cylinder 1 through the material inlet 102, flowing down at a uniform speed along the rotating shaft. It flows from top to bottom and from inside to outside at the conical surface of the distributor 3, and is then ejected by the high-speed rotating distributor 3 onto the inner wall of the inner cylinder 1, initially forming a material film. This film flows from top to bottom and is further thinned by the blades of the scraper 4. Throughout the process, the jacket 2 provides high temperature, while the vacuum port 101 provides low pressure, causing small molecule impurities within the material film to rapidly volatilize and escape, continuously being drawn out through the vacuum port 101 for further processing. After the scraping and volatilization process, the material slides freely down the side wall of the inner cylinder 1, where it is further agitated and foamed by the spiral blades of the stirring paddle 5 to remove residual small molecule impurities. Finally, the removed material is continuously discharged from the material outlet 104 to the next production process.

[0071] The advantage of this solution is that it combines the advantages of flash deglossing, foaming deglossing, and diffusion deglossing, enabling continuous material processing with low consumption and high efficiency.

Claims

1. A small molecule devolatilization reactor characterized by, The utility model relates to a kind of vacuum coating equipment, including: Inner cylinder (1), shape is rotary body; Scrape membrane paddle (4), located in inner cylinder (1), the rotation axis of the scrape membrane paddle (4) connection is coaxial with the rotation axis of the rotary body of inner cylinder (1), and the outside side of scrape membrane paddle (4) and the shape size clearance of the inner side wall of inner cylinder (1) are adapted.

2. The small molecule devolatilization reactor of claim 1, wherein, The clearance between the outside side of scrape membrane paddle (4) and the inner side wall of inner cylinder (1) is not more than 10mm.

3. The small molecule devolatilization reactor of claim 1 or 2, wherein, It also includes stirring paddle (5);Stirring paddle (5) is coaxially connected with scrape membrane paddle (4), and stirring paddle (5) is located in the inside below of scrape membrane paddle (4).

4. The small molecule devolatilization reactor of claim 3, wherein, The blade of stirring paddle (5) is spiral, rotates around shaft when working, and the direction of force is axial downward.

5. The small molecule devolatilization reactor of claim 1 or 2, wherein, Inner cylinder (1) main body is cylinder, lower part is the circular cone of big on top and small on bottom;The high point of scrape membrane paddle (4) is not lower than half of the height of cylinder, and the low point is not higher than the low point of cylinder;The low point of stirring paddle (5) is close to the low point of circular cone.

6. The small molecule devolatilization reactor of claim 5, wherein, It also includes distributor (3) located above scrape membrane paddle (4), and the shape of distributor (3) is conical shape with bottom, and the axis of conical shape is coaxial with the rotation axis of scrape membrane paddle (4) connection.

7. The small molecule devolatilization reactor of claim 6, wherein, It also includes material inlet (102);Material inlet (102) lower end leads to the conical tip of distributor (3) conical shape directly above.

8. The small molecule devolatilization reactor of claim 5, wherein, The clearance between the outside side of stirring paddle (5) and the inner side wall of circular cone is 5~10cm.

9. The small molecule devolatilization reactor of claim 1 or 2, wherein, It also includes jacket (2) coated in the outside of inner cylinder (1);Heat conducting medium outlet (201) is located above jacket (2), and heat conducting medium inlet (202) is located below jacket (2).

10. The small molecule devolatilization reactor of claim 1 or 2, wherein, Vacuum pipe mouth (101) is equipped on inner cylinder (1).

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