Oblique blade stirring device for preparing polyolefin by slurry method

Abstract

The utility model relates to an inclined blade stirring device for preparing polyolefin by a slurry method, which comprises a stirring reactor body, an inclined blade frame type stirrer is arranged in the stirring reactor body, the inclined blade frame type stirrer comprises a stirring shaft, at least one vertical paddle board and a plurality of transverse paddle boards, the vertical paddle board and the stirring shaft are arranged at intervals, and the transverse paddle boards are arranged at intervals. The transverse paddle plate is arranged between the vertical paddle plate and the stirring shaft and forms a hollow frame structure; and the transverse paddle plate is arranged by overturning a certain angle relative to a horizontal plane vertical to the stirring shaft. Compared with the prior art, the inclined blade frame type stirrer is adopted, so that sufficient flowing of liquid is realized in the reaction process, complete mixing of substances in a reaction system is ensured, local dead zones are avoided, sedimentation and accumulation of reaction materials are prevented, the heat transfer and mass transfer effects are improved, and the polymerization reaction efficiency is favorably improved.

Description

Technical Field

[0001] The utility model relates to the technical field of polyolefin preparation, in particular to an inclined blade stirring device for preparing polyolefin by a slurry process. Background Art

[0002] Ultra-high molecular weight polyethylene (UHMWPE) is a widely used product in polyolefins. Its production processes mainly include solution method, slurry method and gas phase method. Among them, the slurry method is relatively mature and has good product quality. It is the main method for producing UHMWPE. The slurry method is to mix aliphatic hydrocarbon solvents and ethylene to generate polymers under the action of catalysts, and the polymers are suspended in the solvent. According to the different forms of reactors, it is divided into tubular slurry method and kettle slurry method. At present, most of them use kettle slurry process. When preparing UHMWPE by kettle slurry method, the stirring reaction device is the core component of the preparation process, which directly determines the quality of UHMWPE products.

[0003] The more mature stirred reactors in the prior art are Figure 1 As shown, a three-layer radial turbine agitator is used. In the polymerization system with high viscosity of ultra-high molecular weight polyethylene, the stirring effect of this agitator is not ideal, the stirring is easy to be stratified, there is a dead zone, and the stirring is uneven and incomplete. In the polymerization process, UHMWPE is prone to sedimentation. In addition, the polymerization reaction is a strong exothermic reaction. In the case of poor dispersion effect and unsatisfactory heat removal effect, local hot spots are easily formed inside the reactor, resulting in problems such as implosion, material wall adhesion, and agglomeration. Therefore, how to provide an improved stirring device suitable for preparing ultra-high molecular weight polyethylene by slurry method has become a technical problem to be solved in this field. Utility Model Content

[0004] The purpose of the utility model is to solve the above problems and provide a slanted blade stirring device for preparing polyolefins by slurry process.

[0005] The purpose of the utility model is achieved through the following technical solutions:

[0006] A slurry method for preparing polyolefins by an inclined blade stirring device comprises a stirring reactor body, wherein a stirring device is arranged in the stirring reactor body, and the stirring device is an inclined blade frame stirrer.

[0007] The inclined blade frame agitator comprises a stirring shaft, at least one vertical paddle and a plurality of transverse paddles.

[0008] The vertical paddle plate is spaced apart from the stirring shaft, the transverse paddle plate is installed between the vertical paddle plate and the stirring shaft to form a hollow frame structure, and the transverse paddle plate is flipped at a certain angle relative to a horizontal plane perpendicular to the stirring shaft.

[0009] The vertical paddles of the inclined blade frame agitator cause the slurry to produce a large vortex, thereby forming a large circulation throughout the kettle. The flipping design of the horizontal paddles causes the liquid to produce an axial mixing effect, promoting the formation of a circulating flow. This structure of the agitator allows the liquid to fully flow and mix during the stirring process, thereby achieving a better stirring and dispersing effect, helping to disperse the reaction materials, promoting the reaction and improving the reaction efficiency.

[0010] As a preferred technical solution, 2-4 vertical paddles are provided, and further preferably, the vertical paddles are provided at equal intervals with the stirring shaft as the central axis. In a specific preferred embodiment, two vertical paddles are provided symmetrically with the stirring shaft as the symmetry axis.

[0011] As a preferred technical solution, the vertical paddle is a rectangular strip, and the vertical paddle is obliquely arranged at a certain angle to the central vertical plane of the stirring shaft, and the angle is 15-45°, such as 15°, 30°, 45°, etc.

[0012] As a preferred technical solution, the transverse paddle is arranged in parallel in the transverse direction between the stirring shaft and the vertical paddle, and the flip angle of the transverse paddle relative to the horizontal plane is 30-60°, such as 30°, 45°, 60°.

[0013] As a preferred technical solution, the transverse paddles are arranged in 3-6 rows, such as 3 rows, 4 rows, 5 rows, 6 rows, etc.

[0014] As a preferred technical solution, the transverse paddle plate is a flat plate or an arc-shaped plate, preferably an arc-shaped plate.

[0015] As a preferred technical solution, the transverse paddles are installed on both sides of the stirring shaft and are arranged in a centrally symmetrical manner, and the transverse paddles on both sides of the stirring shaft flip in opposite directions relative to the horizontal plane;

[0016] And / or, the directions in which the transverse paddle boards adjacent to each other in the upper and lower directions on the same side are flipped relative to the horizontal plane are opposite.

[0017] As a preferred technical solution, a bottom bearing is installed at the bottom of the reactor of the stirring reactor body through a bracket, and the bottom bearing is installed at the end of the stirring shaft.

[0018] The utility model adopts an inclined blade frame stirring structure in the preparation of ultra-high molecular weight polyethylene by the slurry method. The specific working process is: when the stirring shaft rotates, the vertical paddle and the transverse paddle rotate along with it and cooperate with each other to produce a complex flow field. The vertical paddle forms a radial flow, and the design of the transverse paddle flipping makes the liquid produce an effect of up and down axial flow, that is, this structure can make the liquid flow fully during the stirring process, thereby achieving a better stirring and dispersing effect, helping to mix the reaction substances, promote the reaction and improve the reaction efficiency. In addition, the transverse paddle is installed between the vertical paddle and the stirring shaft to form a hollow frame structure, which has a small flow resistance during rotation and enhances the shear performance of the central area during rotation, which is very suitable for the stirring system of ultra-high molecular weight polyethylene. Therefore, the utility model uses the unique structural design and working principle of the inclined blade frame stirring to enable the slurry liquid to flow fully during the stirring process, achieve a better stirring effect, improve the reaction efficiency, and solve the problems of unevenness, dead zone, sedimentation and uneven heat dissipation in the reaction process.

[0019] Compared with the prior art, the utility model has the following beneficial effects:

[0020] The inclined blade frame agitator is used to achieve the up and down flow of liquid in the slurry method for preparing ultra-high molecular weight polyethylene, and the stirring and dispersion are more sufficient. The inclined blade frame agitator runs through the reactor axially up and down, which can ensure that the substances in the reaction system are thoroughly mixed and avoid local dead zones, thereby ensuring the uniformity of the reaction. Through the action of the inclined blade frame agitator, the sedimentation and accumulation of the reaction substances are effectively prevented, the uniformity and stability of the reaction system are maintained, and the heat and mass transfer effects are improved, which helps to improve the efficiency of the polymerization reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of an existing turbine stirred reactor;

[0022] Figure 2 This is a schematic diagram of the structure of the stirring device of the utility model;

[0023] Figure 3 This is a schematic diagram of the main structure of a stirring device according to an embodiment of the utility model;

[0024] Figure 4 This is a schematic diagram of the top view of the stirring device according to one embodiment of the utility model;

[0025] Figure 5 Schematic diagram of the angle at which the transverse paddle board flips relative to the horizontal plane.

[0026] Figure numerals: 1-motor; 2-reducer; 3-bracket; 4-manhole; 5-feeding port; 6-support; 7-cylinder; 8-agitation shaft; 9-vertical paddle; 10-horizontal paddle; 11-discharging port; 12-bottom bearing. DETAILED DESCRIPTION

[0027] The following discloses a variety of different implementation methods or embodiments of the subject technical solution. To simplify the disclosure, specific examples of each element and arrangement are described below. Of course, these are only examples and are not intended to limit the scope of protection of the utility model. For example, the first feature subsequently recorded in the specification is formed above or on the second feature, which may include an implementation method in which the first and second features are formed in a directly connected manner, and may also include an implementation method in which an additional feature is formed between the first and second features, so that the first and second features may not be directly connected. In addition, the figure marks and / or letters may be repeated in different examples in these disclosures. This repetition is for simplicity and clarity, and does not itself represent the relationship between the various implementation methods and / or structures to be discussed. Further, when the first element is described in a manner connected or combined with the second element, the description includes an implementation method in which the first and second elements are directly connected or combined with each other, and also includes the use of one or more other intervening elements to indirectly connect or combine the first and second elements.

[0028] In addition, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description. Unless otherwise stated, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the utility model; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself, and the use of words such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above words have no special meanings, and therefore cannot be understood as limiting the scope of protection of the utility model.

[0029] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "some embodiments" mentioned twice or more in different positions in this specification do not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0030] The utility model is described in detail below. All the technical solutions not described in detail in the utility model are disclosed in the art.

[0031] Figure 1 The figure shows a more mature stirred reactor, which uses a turbine agitator. Three turbine agitators are set on the agitator shaft from top to bottom. This type of agitator is prone to stratification during agitation, dead zones exist, and the agitation is uneven and incomplete. When used in ultra-high molecular weight polyethylene polymerization systems, the dispersion effect is not ideal. UHMWPE has a very high molecular weight, generally above 200w. During the polymerization process, it is prone to sedimentation. In addition, the polymerization reaction is a highly exothermic reaction. If the dispersion effect is poor and the heat is not removed in time, local hot spots are likely to exist inside the reactor, causing material wall adhesion and agglomeration problems. In addition to affecting product quality, it is also easy to cause blockage of the subsequent system.

[0032] In order to solve the above technical problems, the inventors provide a new inclined blade stirring device for preparing polyolefins by slurry process. Figure 2 As shown, the stirring device includes a stirring reactor body, the main part of which is a cylindrical stirring reactor, and a stirring device is arranged inside the barrel 7 of the stirring reactor. A reducer 2 is installed at the upper end of the stirring reactor through a bracket 3, and a motor 1 is installed at the upper end of the reducer 2. The motor 1 is connected to the reducer 2 in a transmission manner, and the output end of the reducer 2 is connected to the stirring shaft 8 of the stirring device through a connecting shaft and drives the stirring device to rotate, so as to stir and disperse the reaction materials in the reactor. A support 6 for installation is arranged on the upper part of the reactor, a manhole 4 and at least one feed port 5 are arranged on the top, and at least one discharge port 11 is arranged at the lower end. These are all conventional auxiliary parts of the reactor and will not be described in detail here.

[0033] The stirring device of the utility model is provided with a stirring device in the stirring reactor body, specifically adopting an inclined blade frame type stirrer, referring to Figure 2 and Figure 3 The inclined blade frame agitator comprises a stirring shaft 8, at least one vertical paddle 9 and a plurality of transverse paddles 10. The vertical paddle 9 is arranged vertically at a certain interval from the stirring shaft 8, and the transverse paddle 10 is installed between the vertical paddle 9 and the stirring shaft 8 to form a hollow frame structure. Figure 5 , the transverse paddle 10 is set to be flipped at a certain angle β relative to the horizontal plane B perpendicular to the stirring shaft 8, for example, 30-60°, preferably 45°. When the stirring shaft 8 rotates, the vertical paddle 9 and the transverse paddle 10 rotate accordingly and cooperate with each other to produce a complex flow field: the vertical paddle 9 forms an annular slurry flow, and the flip design of the transverse paddle 10 relative to the horizontal plane causes the liquid to flow up and down, so that the liquid can flow fully during the stirring process, achieving a better stirring and dispersing effect, helping to mix the reaction substances, promote the reaction and improve the reaction efficiency. In addition, the transverse paddle 10 is installed on the vertical paddle 9 and forms a hollow frame structure with the stirring shaft 8, which has a small flow resistance during rotation and is more suitable for ultra-high molecular weight polyethylene reaction systems with higher viscosity.

[0034] As a preferred embodiment, 2-4 vertical paddles 9 can be provided as needed. More preferably, the vertical paddles 9 are arranged at equal intervals with the stirring shaft 8 as the central axis, for example, 4, 3 or 2 vertical paddles are arranged at equal intervals. Figure 3 Two vertical paddles 9 are symmetrically arranged with the stirring shaft 8 as the symmetry axis, and the vertical paddles 9 are rectangular long strips. Figure 4 As a more preferred embodiment, the vertical paddle 9 is tilted at a certain angle α to the central vertical plane A of the stirring shaft 8, and the angle α is 15-45°, for example, preferably 30°. This tilted arrangement increases the stirring area, and the liquid will be more disturbed and pushed during the stirring process, so that the stirring area is expanded, that is, the contact area between the liquid and the paddle is increased, and a stronger liquid driving force and shear force are generated during the stirring process, so that the liquid is more fully mixed. This increased stirring intensity helps to break up lumps in the liquid and promote uniform dispersion of the substance. In addition, the tilted vertical paddle 9 can reduce the dead zone in the agitator, and the liquid is more easily pushed and stirred to the dead zone, and it helps to eliminate tangential flow, reduce the heterogeneity in the reaction system, and improve the stirring effect.

[0035] As a preferred embodiment, the transverse paddle 10 is arranged in parallel between the stirring shaft 8 and the vertical paddle 9 in the transverse direction, and the transverse paddle 10 is arranged at a certain angle β relative to the horizontal plane. The transverse paddle 10 is arranged in 3-6 rows as required. For example, in a specific embodiment of the present invention, 5 rows are specifically arranged. Figure 3 As a preferred embodiment of the utility model, the transverse paddles 10 are symmetrically installed on both sides of the stirring shaft 8, and the transverse paddles 10 on both sides of the stirring shaft 8 are flipped in opposite directions relative to the horizontal plane. Alternatively, the transverse paddles 10 located on the same side and adjacent to each other in pairs can be flipped in opposite directions relative to the horizontal plane. Such a structure can generate a variety of axial flow fields with different flow directions near the transverse paddles 10, and the liquid stirring and dispersing effect is better. Furthermore, the transverse paddles 10 can be flat plates or curved plates, which are better than flat plates (refer to Figure 3 ). The use of curved plates allows the fluid to flow along a certain curve, which can smoothly guide the fluid movement and reduce the generation of vortices. In addition, the curved plates can generate stronger liquid driving force and shear force, reduce the dead zone in the agitator, and the liquid is easily pushed and stirred to the dead zone.

[0036] As a preferred embodiment, in order to improve the stability of the stirring device, the utility model installs a bottom bearing 12 at the bottom of the stirring reactor through a bracket. The bottom bearing 12 is installed at the end of the stirring shaft 8 of the stirring device to stabilize the stirring device.

[0037] The above description of the embodiments is to facilitate the understanding and use of the utility model by those skilled in the art. It is obvious that those familiar with the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the utility model is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the utility model without departing from the scope of the utility model should be within the scope of protection of the utility model.

Claims

1. A slurry process for preparing polyolefins by an inclined blade stirring device, comprising a stirring reactor body, wherein a stirring device is provided in the stirring reactor body, characterized in that: The stirring device is a pitch-blade frame stirrer. The inclined blade frame stirrer comprises a stirring shaft (8), at least one vertical paddle (9) and a plurality of transverse paddles (10). The vertical paddle plate (9) is spaced apart from the stirring shaft (8), the transverse paddle plate (10) is installed between the vertical paddle plate (9) and the stirring shaft (8) to form a hollow frame structure, and the transverse paddle plate (10) is flipped at a certain angle relative to a horizontal plane perpendicular to the stirring shaft (8).

2. The inclined blade stirring device for preparing polyolefin by slurry process according to claim 1, characterized in that: The number of the vertical paddle boards (9) is 2 to 4.

3. The inclined blade stirring device for preparing polyolefin by slurry process according to claim 2, characterized in that: The vertical paddles (9) are arranged at equal intervals with the stirring shaft (8) as the central axis.

4. The inclined blade stirring device for preparing polyolefin by slurry process according to claim 1, characterized in that: The vertical paddle plate (9) is a rectangular strip-shaped plate member, and the vertical paddle plate (9) is obliquely arranged at a certain angle to the central vertical plane of the stirring shaft (8), and the angle is in the range of 15-45°.

5. The inclined blade stirring device for preparing polyolefin by slurry process according to claim 1, characterized in that: The transverse paddle (10) is arranged in parallel in the transverse direction between the stirring shaft (8) and the vertical paddle (9), and the transverse paddle (10) is turned at an angle of 30-60° relative to the horizontal plane.

6. The inclined blade stirring device for preparing polyolefin by slurry process according to claim 5, characterized in that: The transverse paddles (10) are arranged in 3 to 6 rows.

7. The inclined blade stirring device for preparing polyolefin by slurry process according to claim 5, characterized in that: The transverse paddle board (10) is a flat plate or an arc-shaped plate.

8. The inclined blade stirring device for preparing polyolefin by slurry process according to claim 5, characterized in that: The transverse paddles (10) are installed on both sides of the stirring shaft (8) and are arranged in a centrally symmetrical manner, and the transverse paddles (10) on both sides of the stirring shaft (8) flip in opposite directions relative to the horizontal plane; And / or, the transverse paddle boards (10) adjacent to each other in pairs on the same side flip in opposite directions relative to the horizontal plane.

9. The inclined blade stirring device for preparing polyolefin by slurry process according to claim 1, characterized in that: The bottom of the reactor of the stirring reactor body is provided with a bottom bearing (12) through a bracket, and the bottom bearing (12) is installed at the end of the stirring shaft (8).

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