Stirred reactor for solution process polyolefins
Patent Information
- Application Number
- CN202620148755.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-02
- Publication Date
- 2026-11-03
- Estimated Expiration
- 2036-02-02
AI Technical Summary
Existing solution-based polyolefin polymerization reactors suffer from problems such as insufficient axial mixing, uneven mixing, and high-viscosity media adhering to the walls, which affect product quality and reactor operational stability.
It adopts a multi-stage, multi-functional impeller structure, including an anchor frame impeller, a scraper impeller, and a baffle. The anchor frame impeller scrapes the bottom and side walls, the scraper impeller rotates close to the inner wall, and the baffle converts the radial flow into the axial flow, generating strong shear and vortex, thus achieving uniform mixing of the medium.
It improves mixing efficiency, enhances mass and heat transfer, prevents adhesion to the reactor walls, ensures the uniformity of the medium within the reactor and the stability of the reaction process, and improves product quality.
Smart Images
Figure CN224926126U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of solution polyolefin equipment, and more specifically, relates to a stirred reactor for solution polyolefin. Background Technology
[0002] In solution-based polyolefin polymerization reactors, the high viscosity of the polymer solution and the large exothermic reaction easily lead to problems such as localized overheating, low mass and heat transfer efficiency, uneven product distribution, and scaling (wall adhesion) on the reactor wall. Existing agitators, such as anchor-frame and scraper-type agitators, while addressing the wall adhesion problem to some extent when handling high-viscosity media, often suffer from low mixing efficiency, particularly in axial mixing, making it difficult to ensure uniform mixing of the media within the reactor, thus affecting product quality and reactor operational stability. Traditional baffle structures are mostly fixed or simple paddle types, offering limited axial flow guidance and enhanced mixing effects for high-viscosity media, and may increase the risk of excessive localized shear or dead zones. Utility Model Content
[0003] To address the problems of insufficient axial mixing, uneven mixing, and difficulty in completely resolving the issue of high-viscosity media adhering to the walls in existing solution-process polyolefin polymerization reactors, this invention aims to provide a novel stirred reactor for solution-process polyolefins, which improves mixing efficiency, enhances mass and heat transfer, effectively prevents wall adhesion, and ensures the uniformity of the medium within the reactor.
[0004] The technical solution of this utility model is as follows: This invention provides a stirred reactor for solution-process polyolefins, comprising a reactor body and a stirring shaft disposed on the central axis of the reactor body. An anchor-frame stirring paddle is disposed at the lower part of the stirring shaft; multiple layers of scraper-type stirring paddles are disposed axially at the upper part of the stirring shaft; and baffle structures are disposed on the inner wall of the reactor body between each layer of scraper-type stirring paddles and between the scraper-type stirring paddles and the anchor-frame stirring paddles; the baffle structure comprises multiple baffles uniformly arranged circumferentially; the baffle is an open structure formed by a top plate, a first side plate, and a second side plate.
[0005] According to the preferred embodiment, the reactor body is vertically arranged, with elliptical end caps at both the top and bottom, and an outer jacket structure on the outside; the bottom of the reactor body is provided with a feed inlet, the side near the bottom is provided with a feeding port, and the top is provided with a discharge port.
[0006] According to a preferred embodiment, the first side plate and the second side plate are parallel to each other and are both vertically arranged, with one end of the first side plate and the second side plate connected to the inner wall of the reactor body; the top plate is vertically arranged and connected to the other end of the first side plate and the second side plate respectively.
[0007] According to the preferred embodiment, the top plate, the first side plate, and the second side plate are all steel plates.
[0008] According to a preferred embodiment, the angle γ between the diameter direction of the end of the top plate near the center of the reactor and the top plate is 15°~45°, that is, the vertical plane of the top plate does not pass through the central axis of the reactor; preferably, the aforementioned angle γ is 30°~40°.
[0009] According to a preferred embodiment, the outer surface of the top plate is oriented toward the rotation direction of the stirring shaft (i.e., the direction of incoming flow), so that the incoming flow impacts the top plate, realizing the conversion from radial flow to axial flow.
[0010] According to the preferred embodiment, each layer of baffle structure includes 6 baffles evenly arranged circumferentially.
[0011] According to a preferred embodiment, the height of the top plate is 0.05 to 0.08 times the height of the reactor; the width is 0.3 to 0.5 times the radius of the reactor; and the distance between the end of the top plate near the center of the reactor and the reactor axis is 0.4 to 0.6 times the radius of the reactor.
[0012] According to a preferred embodiment, the anchor-frame type stirring blade scraper is used to scrape the bottom and sidewalls of the reactor, and the distance between it and the inner wall of the reactor is 10~30mm, preferably 15~20mm.
[0013] According to the preferred embodiment, the scraper-type agitator rotates close to the inner wall of the reactor, and the distance between it and the inner wall of the reactor is 10~30mm, preferably 15~20mm.
[0014] The anchor-frame type agitator at the bottom of the stirring shaft in this reactor effectively scrapes the bottom and side walls of the reactor, preventing material accumulation at the bottom and initial wall adhesion. The scraper-type agitator at the top of the stirring shaft rotates closely against the inner wall of the reactor, effectively scraping off polymer from the wall surface and preventing wall adhesion.
[0015] The flow baffles inside the reactor of this invention convert radial flow into axial flow, generating strong shear and vortex currents, ensuring thorough mixing of the medium in both the axial and radial directions. This combination of multi-stage, multi-functional stirring paddles effectively solves the problems of uneven mixing and wall adhesion of high-viscosity media in solution-based polyolefin polymerization reactors, ensuring the stability of the reaction process and the uniformity of product quality. Attached Figure Description
[0016] Figure 1 A schematic diagram of the reactor of this utility model is shown.
[0017] Figure 2 A top view of the baffle arrangement of the reactor of this utility model is shown.
[0018] Figure 3 A top view of the baffle structure is shown.
[0019] Figure 4 A schematic diagram of the baffle plate structure is shown.
[0020] Figure 5 This is a schematic diagram showing the installation of the baffles and the rotation direction of the stirring shaft in the experimental group.
[0021] Figure 6 This is a schematic diagram of the installation of the baffle and the rotation direction of the stirring shaft in control experimental group 1.
[0022] Figure 7 This is a schematic diagram of the installation of the baffle and the rotation direction of the stirring shaft in control experimental group 2.
[0023] In the figure, the end cap is 1, the anchor frame agitator is 2, the scraper agitator is 3, the baffle is 4, the top plate is 41, the first side plate is 42, and the second side plate is 43. Detailed Implementation
[0024] Preferred embodiments of the present invention will now be described in more detail. While preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.
[0025] The stirred reactor for solution-based polyolefins proposed in this invention is mainly used in solution polymerization systems. Solution polymerization refers to the polymerization reaction in which monomers (ethylene, propylene, or higher α-olefins) are dissolved in a solvent (such as cyclohexane, hexane, etc.) under the action of a catalyst. After the reaction, the polymer also dissolves in the solvent to form a homogeneous solution. After solvent removal, separation, and drying, the polyolefin product is obtained.
[0026] like Figure 1 As shown, the stirred reactor for solution-process polyolefins in this embodiment mainly includes a reactor body and a stirring shaft disposed on the central axis of the reactor body. The reactor body is vertically arranged, and its main body is cylindrical with elliptical end caps 1 at both ends. An outer jacket structure is provided on the outside of the reactor body for heat exchange of the internal materials. Figure 1 As shown, the jacket medium inlet of the outer jacket structure is located at the bottom, and the jacket medium outlet is located at the upper side. The medium inside the jacket can be selected as needed, for example, it can be water.
[0027] like Figure 1 As shown, the reactor body has a feed inlet at the bottom, a feed outlet on the side near the bottom, and a discharge outlet at the top.
[0028] The stirring shaft is driven to rotate by a stirring motor. For example... Figure 1 As shown, an anchor-frame agitator 2 is installed at the lower part of the agitator shaft. The anchor-frame agitator can effectively scrape the bottom and side walls of the reactor, preventing material accumulation at the bottom and initial wall adhesion. The distance between the anchor-frame agitator and the inner wall of the reactor is 10~30mm. A multi-layer scraper-type agitator 3 is installed axially at the upper part of the agitator shaft. The scraper-type agitator can rotate close to the inner wall of the reactor, effectively scraping off polymer from the wall surface and preventing wall adhesion. The distance between the scraper-type agitator and the inner wall of the reactor is 10~30mm.
[0029] like Figure 1 As shown in the embodiment, a baffle structure is provided between each layer of scraper-type agitators and between the scraper-type agitators and the anchor-frame agitators. The baffle structure includes multiple baffles 4 evenly arranged circumferentially on the inner wall of the reactor body. The baffle is an open structure formed by three steel plates. Specifically, the baffle includes a top plate 41, a first side plate 42, and a second side plate 43. The top plate, the first side plate, and the second side plate are all flat plates, and the first side plate and the second side plate are parallel to each other and vertically arranged. The outer end is defined as the end of each plate away from the center of the reactor, and the corresponding inner end is the end closer to the center of the reactor. The outer ends of the first side plate and the second side plate are connected to the inner wall of the reactor body. The top plate is vertically arranged, and one side of it is connected to the inner end of the first side plate and the second side plate, respectively.
[0030] The baffle of this utility model is an open structure formed by a first side plate 42, a second side plate 43, and a top plate 41. All three plates are made of steel plates. Specifically, these three steel plates are connected by welding to form a channel-like structure with a certain height and width, with both ends open. The height of the top plate is 0.05 to 0.08 times the height of the reactor; the width (horizontal distance from the inner end to the outer end) is 0.3 to 0.5 times the radius of the reactor; and the distance between the inner end of the top plate and the reactor axis is 0.4 to 0.6 times the radius of the reactor.
[0031] like Figures 2 to 4 As shown, the top plate of the baffle is arranged obliquely to the axis. When viewed from above, the inner edge (inner end) of the top plate is closer to the stirring shaft, and the outer edge (outer end) is farther away from the stirring shaft, forming an inwardly inclined plane. That is, the top plate of this invention is not arranged along the diameter direction of a certain reactor.
[0032] Six baffles are evenly arranged along the circumference of the stirring shaft. For example... Figure 2 As shown, the angle γ between the top plate of each baffle and its inner end along the diameter direction is 15°~45°. Figure 3 As shown, since the first and second side plates are parallel, α + β = 180°. Figure 2 and Figure 3 It can be seen that, assuming the direction of rotation of the stirring shaft is clockwise, then Figure 3 The second side plate 43 is longer than the first side plate 42, so that the outer surface of the top plate is set to face (towards) the rotation direction of the stirring shaft (i.e. the direction of incoming flow), so that the incoming flow hits the top plate and realizes the conversion from radial flow to axial flow, that is, α is less than β. This tilt angle design is the key to realizing axial flow guidance.
[0033] In practice, the anchor-frame agitator is mainly responsible for mixing and scraping the walls of the high-viscosity medium at the bottom, while the scraper-type agitator is responsible for scraping the walls and radial mixing in the upper region. The baffles play a crucial role between the scraper-type agitators, converting radial flow into axial flow and generating strong shear and vortices, ensuring thorough mixing of the medium in both the axial and radial directions within the reactor. This combination of multi-stage, multi-functional agitators effectively solves the problems of uneven mixing and wall adhesion of high-viscosity media in solution-process polyolefin polymerization reactors, ensuring the stability of the reaction process and the uniformity of product quality.
[0034] The following is a verification of the effectiveness of the stirred reactor for solution-based polyolefins proposed in this invention. Figures 5-7 These are schematic diagrams showing the installation of baffles and the rotation direction of the stirring shaft in the experimental group, control group 1, and control group 2, respectively. The baffle structures in all three groups are identical, with α being 45°, the top plate dimensions being the same, and the dimensions of the stirred reactors being completely identical. The difference between control group 1 and the experimental group is that γ was adjusted to 61.78°, while γ in both the experimental group and control group 2 was 30°; control group 2 changed the rotation direction of the stirring shaft. Figure 5 and Figure 6 The stirring shaft rotates clockwise. Figure 7 (Counter-clockwise rotation was used), meaning the outer surface of the top plate of control group 2 was not oriented towards the direction of rotation of the stirring shaft. Mixing and mass transfer experiments were conducted using three groups. During the experiments, the liquid phase was methylcyclohexane, the gas phase was ethylene, the mass transfer temperature was 80℃, and the pressure was 2MPa. Ethylene was extracted from the reactor by an air compressor and then bubbled into the reactor from the bottom. The material viscosity was 200 cP, the stirring speed was 150 rpm, and data processing was performed on the radial section at the center height of the baffle. The separation index results for different stirring times are shown in Table 1 below.
[0035] Table 1 The separation index quantitatively describes the degree of uniform dispersion of different components in a mixture. Its value ranges from 0 to 1, with 0 representing an ideal, completely homogeneous mixture. A smaller value indicates better homogeneous mixing efficiency. Table 1 shows that, under different stirring times, the separation index of the experimental group was significantly lower than that of control groups 1 and 2. Further calculation of the volumetric mass transfer coefficient driven by the mole fraction difference yielded a value of 1.21 mol / (m³) for the experimental group. 2 ·s), control groups 1 and 2 were 1.01 mol / (m 2 ·s) and 1.09 mol / (m 2 The above results demonstrate that the present invention can effectively solve the problem of uneven mixing of high-viscosity media in solution-based polyolefin polymerization reactors.
[0036] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.
Claims
1. A stirred reactor for solution-process polyolefins, comprising a reactor body and a stirring shaft disposed on the central axis of the reactor body, characterized in that, The lower part of the stirring shaft is provided with an anchor frame stirring paddle; the upper part of the stirring shaft is provided with multiple scraper stirring paddles in the axial direction; and a baffle structure is provided on the inner wall of the reactor body between each layer of scraper stirring paddles and between the scraper stirring paddles and the anchor frame stirring paddles; the baffle structure includes multiple baffles evenly arranged in the circumferential direction; the baffle is an open structure formed by a top plate, a first side plate and a second side plate; the first side plate and the second side plate are parallel to each other and are both vertically arranged, and the top plate is vertically arranged; the angle γ between the diameter direction of the end of the top plate near the center of the reactor and the top plate is 15°~45°.
2. The stirred reactor for solution-process polyolefins according to claim 1, characterized in that, The reactor body is vertically arranged, with elliptical end caps at both the top and bottom, and an external jacket structure. The bottom of the reactor body has a feed inlet, the side near the bottom has a feed outlet, and the top has a discharge outlet.
3. The stirred reactor for solution-process polyolefins according to claim 1, characterized in that, One end of the first side plate and the second side plate are connected to the inner wall of the reactor body; the top plate is connected to the other end of the first side plate and the second side plate respectively.
4. The stirred reactor for solution-process polyolefins according to claim 1, characterized in that, The top plate, the first side plate, and the second side plate are all made of steel plates.
5. The stirred reactor for solution-process polyolefins according to claim 3, characterized in that, The angle γ between the diameter direction of the end of the top plate near the center of the reactor and the top plate is 30°~40°.
6. The stirred reactor for solution-process polyolefins according to claim 3, characterized in that, The outer surface of the top plate is arranged to face the direction of rotation of the stirring shaft.
7. The stirred reactor for solution-process polyolefins according to claim 3, characterized in that, Each layer of baffle structure includes 6 baffles evenly arranged circumferentially.
8. The stirred reactor for solution-process polyolefins according to claim 3, characterized in that, The height of the top plate is 0.05 to 0.08 times the height of the reactor; the width is 0.3 to 0.5 times the radius of the reactor; and the distance between the end of the top plate near the center of the reactor and the reactor axis is 0.4 to 0.6 times the radius of the reactor.
9. The stirred reactor for solution-process polyolefins according to claim 1, characterized in that, The anchor-frame type stirring blade scraper is used to scrape the bottom and side walls of the reactor, and its distance from the inner wall of the reactor is 10~30mm.
10. The stirred reactor for solution-process polyolefins according to claim 1, characterized in that, The scraper-type agitator rotates close to the inner wall of the reactor, with a distance of 10~30mm between it and the inner wall.