CN118615987A - A stirred tank reactor and process for producing polyolefins by slurry process - Google Patents

Abstract

The invention relates to a kettle type stirring reactor for producing polyolefin by a slurry method and a process thereof, wherein a top end socket of a stirring reactor body is provided with a plurality of circulating gas inlets and a plurality of circulating gas outlets, a bottom inserting pipe is arranged through the circulating gas inlets, a reactor shell is provided with at least one slurry outlet and at least one raw material feeding hole, the inner wall of the reactor shell is provided with an inner jacket heat removing mechanism, and an inclined She Kuangshi stirrer is adopted in the reactor. Compared with the prior art, the kettle type stirring reactor can realize the full mixing and scattering of liquid through the inclined She Kuangshi stirrer, ensure the complete mixing of substances in a reaction system, avoid local dead zones, prevent the settlement and accumulation of reaction substances, simultaneously combine with an inner jacket heat removal mechanism, improve the heat removal efficiency, promote the heat transfer and mass transfer effect, and effectively solve the technical problems of poor stirring and dispersing effect and low heat removal efficiency.

Description

A kind of kettle-type stirred reactor and process for producing polyolefin by slurry process

Technical Field

The invention relates to the technical field of polyolefins, and in particular to a kettle-type stirring reactor and a process for producing polyolefins by a slurry process.

Background Art

Polyolefins are a general term for a class of thermoplastic resins obtained by polymerizing or copolymerizing α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, and some cycloolefins. Among them, ultra-high molecular weight polyethylene (UHMWPE for short) has attracted particular attention. Ultra-high molecular weight polyethylene is a linear structural polyethylene with a relative molecular mass of more than 1.5 million g/mol. It exhibits excellent wear resistance, extremely high impact strength, excellent self-lubricating properties and low temperature resistance, and is widely used in industry.

The slurry process is a relatively mature process for producing polyolefins. Specifically, aliphatic hydrocarbon inert solvents and monomers are fused to generate polymers under the action of catalysts, and the polymers are suspended in the solvent. According to the different forms of reactors, it can be divided into tubular slurry process and kettle slurry process. At present, the kettle slurry process is mostly used. When preparing polyolefins by kettle slurry, the stirred reactor is the core device, which directly determines the product quality.

The stirring equipment in the kettle stirred reactor has an important influence on the polymerization process. The stirred reactor with relatively mature prior art is shown in Figure 1, which uses a turbine stirrer. In the ultra-high molecular weight polyolefin polymerization system, the stirring effect of this stirrer is not ideal, the stirring is easy to be stratified, and there is a certain dead zone, resulting in uneven and incomplete stirring. Especially in the preparation of UHMWPE, since UHMWPE has an ultra-high molecular weight and high viscosity, it is easy to settle during the polymerization process. 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 formed in the reactor, which are prone to explosion, material wall adhesion, and agglomeration problems.

In addition, timely removal of reaction heat is another key process to ensure smooth polymerization. Various heat removal methods are disclosed in the prior art, such as Chinese patent CN 117482875A discloses a production device for synthesizing 1-octene, which discloses that heat exchange is carried out by installing a heat exchange inner coil between the stirring paddle and the outer wall in the reactor, but the inner coil has a complex structure in the kettle, which easily leads to wall adhesion and agglomeration on the inner coil. Chinese patent CN 110918018A discloses a combined heat removal method for a kettle slurry polyethylene reactor, which discloses that the heat of polymerization is removed by adopting a combination of solvent evaporation, slurry external circulation and reactor clamps. However, the outer jacket used in the patent has a low heat exchange efficiency due to the wall thickness of the reactor shell. Chinese patent CN205046027U discloses a kettle slurry method olefin continuous polymerization device, which is provided with an inner jacket for filling liquid hexane and arranged on the inner wall of the reactor, but the specific structure of the inner jacket is not disclosed, and the hexane flow field as a heat exchange medium may have dead zones and short circuit phenomena. Therefore, further research is needed to provide a kettle-type stirred reactor and process suitable for the slurry process for producing polyolefins, especially for UHMWPE systems, to solve the problems of reactor stirring and dispersion and timely and efficient removal of reaction heat.

Summary of the invention

The object of the present invention is to provide a kettle-type stirred reactor and process for producing polyolefins by a slurry process in order to solve the above problems.

The purpose of the present invention is achieved through the following technical solutions:

A kettle-type stirred reactor for producing polyolefins by a slurry process comprises a stirred reactor body provided with a stirring device inside, a top cover of the stirred reactor body is provided with a plurality of circulating gas inlets and a plurality of circulating gas outlets, a bottom plug pipe for delivering raw gas to the bottom of the reactor is provided through the circulating gas inlet,

The reactor shell of the stirred reactor body is provided with at least one slurry outlet as overflow discharge, and at least one raw material feed port.

An inner jacket heat removal mechanism is arranged on the inner wall of the reactor shell of the stirring reactor body, and the stirring device adopts an inclined blade frame type stirrer.

As a preferred technical solution of the present invention, the bottom-inserted tube is arranged vertically, and the bottom of the bottom-inserted tube extends into the bottom of the reactor;

And/or, the bottom of the bottom tube is bent toward the center of the reactor, and the outlet of the bottom tube is close to the paddle of the inclined blade frame agitator. This structural arrangement enables the reaction gas raw material to be quickly dispersed. When the raw gas is discharged from the outlet, it is immediately broken up by the agitator and dispersed more quickly in the reaction slurry to avoid implosion. As a more preferred embodiment, the bottom tube can be further provided with a spoiler baffle, which is a thin round rod and is sequentially arranged on the bottom tube from top to bottom. The spoiler baffle has a spoiler effect and cooperates with the stirring equipment to further improve the dispersion effect of the reaction material.

And/or, the circulating gas inlets are provided with 6 to 10 pieces, which are arranged in a circular array on the top end cap, and the bottom plugs are provided with 6 to 10 pieces correspondingly, which are all installed vertically downward in the reactor;

And/or, at least two circulating gas outlets are provided, which are symmetrically arranged along the center;

And/or, the top cover of the stirred reactor body is also provided with at least one flushing solvent inlet, a flushing solvent feed pipe is arranged through the flushing solvent inlet and connected to the flushing dispersion disk; a solvent with a certain pressure is introduced from the top to flush the interior of the reactor (including the inner wall, stirring equipment, etc.).

As a preferred technical solution of the present invention, the inner jacket heat removal mechanism comprises a heat exchange wall surface, a gap is formed between the heat exchange wall surface and the inner wall of the reactor shell, and a flow guide support is spirally arranged in the gap.

Mutually connected chambers are formed between the flow guiding supports and between the flow guiding supports and the heat exchange wall surface and the inner wall of the reactor shell.

As a preferred technical solution of the present invention, the angle between the flow guide support and the reactor shell along the axial direction is 30-90°;

And/or, the flow guide supports adjacent to each other are arranged at a distance of 2-20 cm, and the gap thickness of the inner jacket heat removal mechanism along the radial direction of the reactor shell is 2-8 cm.

As a preferred technical solution of the present invention, the side surfaces of the flow guide support are irregularly provided with spoilers for increasing the turbulent flow of the heat exchange medium, and the spoilers are metal thorns, including needle-shaped metal fine needles.

And/or, the heat exchange wall surface is made of thin-walled stainless steel;

And/or, the upper part of the reactor shell is provided with a heat exchange medium outlet connected to the chamber, and the lower part is provided with a heat exchange medium inlet, and the cooling medium flows from bottom to top through the inner jacket heat removal mechanism, and the heat exchange fluid enters from bottom to top and exits from top to bottom, which helps to improve the heat exchange effect. The heat exchange medium outlet and the heat exchange medium inlet are provided with one or more groups.

As a preferred technical solution, in order to improve the heat exchange efficiency, the chambers are distributed up and down along the reactor shell to form a multi-stage parallel passage structure, and multiple groups of heat exchange medium inlets and outlets are set. As a preferred technical solution of the present invention, the inclined blade frame agitator includes a stirring shaft, at least one vertical paddle and multiple transverse paddles,

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.

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, achieving better stirring and dispersing effects, helping to disperse the reaction materials, promoting the reaction and improving the reaction efficiency.

As a preferred technical solution of the present invention, 2-4 vertical paddle boards are provided;

And/or, the vertical paddles are arranged at equal intervals with the stirring shaft as the central axis;

And/or, the vertical paddle plate is a rectangular strip-shaped plate, and the vertical paddle plate is obliquely arranged at a certain angle to the central vertical plane of the stirring shaft, and the angle is 15-45°.

As a preferred technical solution of the present invention, the transverse paddle boards are arranged in 3-6 rows;

And/or, the transverse paddle is arranged in parallel in the transverse direction between the stirring shaft and the vertical paddle, and the transverse paddle is flipped at an angle of 30-60° relative to the horizontal plane;

and/or, the transverse paddle board is a flat plate or a curved plate;

And/or, the transverse paddles are installed on both sides of the stirring shaft and are arranged in a centrally symmetrical manner, the transverse paddles on both sides of the stirring shaft flip in opposite directions relative to the horizontal plane, and/or, the transverse paddles adjacent to each other on the same side flip in opposite directions relative to the horizontal plane.

As a preferred technical solution of the present invention, 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.

A process for producing polyolefins by a slurry process, characterized in that the above-mentioned kettle-type stirred reactor is used for continuous slurry reaction, and the process comprises:

The monomer raw material gas is continuously fed in from the circulating gas inlet, and enters the slurry from the bottom of the reactor through the bottom plug pipe, and other raw materials including solvents and catalysts are continuously fed in from the raw material feed port;

All the reactant raw materials undergo polymerization reaction under the stirring action of the inclined blade frame stirrer, and after the reaction, the slurry containing the reaction product continuously overflows and discharges through the slurry outlet;

The evaporated solvent gas and unreacted raw material gas are continuously discharged from the circulating gas outlet along with the latent heat of vaporization. At the same time, the inner jacket heat removal mechanism removes the reaction heat out of the reaction system.

Compared with the prior art, the present invention has the following beneficial effects:

The invention adopts an inclined blade frame agitator, which realizes full flow of liquid and more complete stirring when preparing polyolefin by slurry method. The inclined blade frame agitator runs through the reactor up and down along the axial direction, ensuring that the materials in the reaction system are thoroughly and completely mixed, avoiding the occurrence of dead zones, thereby ensuring the uniformity of the reaction, and effectively preventing the sedimentation and accumulation of the reaction materials, improving the heat transfer and mass transfer effects, and helping to improve the polymerization reaction efficiency.

The present invention can greatly improve the total heat transfer coefficient and the heat removal efficiency by arranging an inner jacket heat removal mechanism on the inner wall of the stirred reactor, using a thin-walled material to make a heat exchange wall surface, which is directly in contact with the slurry reaction material inside the reactor. The flow guide support member spirally arranged in the inner jacket heat removal mechanism plays a supporting and guiding role, which can support the force of the thin-walled steel plate under the pressure-resistant working condition, and at the same time forms a spiral upward heat exchange medium channel. When the heat exchange medium (such as cold water) flows through, the flow field state is good, and it can be effectively circulated, avoiding dead corners and short circuits, and removing heat in time. In addition, a spoiler is arranged on the flow guide support member, which increases the turbulent flow condition of the heat exchange medium and further improves the heat exchange efficiency.

The kettle stirred reactor provided by the present invention solves the problems of poor stirring and dispersion effect and low heat removal efficiency commonly existing in the continuous preparation of polyolefins by the slurry method by using the stirring effect of the inclined blade frame stirrer, together with the combination of heat removal of the inner jacket and heat removal of latent heat of vaporization, when performing continuous slurry reaction to prepare polyolefins.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of an existing turbine kettle stirred reactor;

FIG2 is a schematic structural diagram of a slurry kettle stirred reactor according to the present invention;

FIG3 is a schematic top view of a slurry kettle stirred reactor;

FIG4 is a schematic diagram of the structure of the bottom tube provided with a spoiler bar;

FIG5 is a schematic diagram of the top view of the structure of the stirring device;

FIG6 is a schematic diagram of the flip angle of the lateral paddle board relative to the horizontal plane;

FIG7 is a schematic diagram of the arrangement of the flow guide support along the reactor shell;

FIG8 is a partial enlarged view of point I in FIG2;

FIG9 is a schematic diagram of slurry flow and heat removal in a reactor;

In the figure: 1-circulating gas inlet; 2-circulating gas outlet; 3-flushing solvent inlet; 4-flushing solvent feed pipe; 5-bottom tube; 501-spoiler baffle; 6-slurry outlet; 7-raw material feed inlet; 8-agitation shaft; 9-vertical paddle; 10-horizontal paddle; 11-heat exchange medium inlet; 12-bottom bearing; 13-flow guide support; 14-chamber; 15-heat exchange wall; 16-reactor shell; 17-spoiler; 18-heat exchange medium outlet.

DETAILED DESCRIPTION

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 present invention. 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 by direct connection, 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.

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 present invention 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 present invention; 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 present invention.

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.

The present invention is described in detail below with reference to the accompanying drawings. All matters not described in detail in the present invention are technical solutions disclosed in the art.

Figure 1 shows a mature kettle stirred reactor currently used for the production of polyolefins (including ultra-high molecular weight polyethylene). The reactor uses a turbine stirrer inside, and the stirring shaft is provided with three turbine stirring blades from top to bottom. This type of stirring equipment is prone to stratification during operation. There are a large number of dead zones in areas far from the stirring blades (such as the bottom of the reactor, near the reactor wall, etc.), resulting in uneven and incomplete stirring. Especially for the polymerization of ultra-high molecular weight polyethylene, the dispersion effect is very unsatisfactory and sedimentation is prone to occur. In addition, the heat removal effect of the kettle stirred reactor is also unsatisfactory. The poor dispersion effect and the poor heat removal effect result in a large number of local hot spots inside the reactor, which causes the reaction materials to agglomerate and stick to the wall, seriously affecting the product quality.

In order to solve the problem of poor stirring, dispersing and heat removal effects in the reactor, the inventor conducted in-depth mechanism analysis and research, and provided a new kettle stirred reactor for producing polyolefins by slurry method. The kettle stirred reactor replaces the turbine stirrer with a pitched blade frame stirrer as the stirring device, and an inner jacket heat removal mechanism is set on the inner wall of the reactor shell. The pitched blade frame stirrer can realize the left and right and up and down flow of liquid when preparing polyolefins by slurry method, ensure that the substances in the reaction system are fully mixed, avoid local dead zones, prevent the sedimentation and accumulation of reaction substances, and maintain the uniformity and stability of the reaction system; at the same time, the setting of the inner jacket heat removal mechanism greatly improves the heat removal efficiency, improves the heat transfer and mass transfer effects, improves the reaction efficiency, and effectively solves the technical problems of stirring, dispersing and removing reaction heat.

FIG2 shows a schematic diagram of the structure of a slurry kettle stirred reactor of the present invention, which includes a stirred reactor body, the main body of which is a cylindrical reactor shell 16, a stirring device installed in the reactor, a reducer installed at the upper end of the reactor through a bracket, a motor installed at the upper end of the reducer, the motor is connected to the reducer by transmission, and the output end of the reducer is connected to the stirring shaft of the stirring device by a connecting shaft and drives the stirring device to rotate, so as to stir and disperse the reaction materials in the kettle. The stirred reactor is provided with a support for installation, a manhole is provided at the top or bottom, etc., which are conventional accessories of the stirred reactor and will not be described in detail here.

Referring to Fig. 2 and Fig. 3, the stirred reactor is a continuous slurry reaction device, and the top end cap is provided with several circulating gas inlets 1 for introducing raw gas (such as ethylene), several circulating gas outlets 2 for discharging gas solvent and unreacted gas raw material, and at least one flushing solvent inlet 3. The reactor shell 16 is provided with at least one slurry outlet 6 as overflow discharge at the upper position (about 2/3 of the reactor height), and several raw material feed ports 7 are provided at the lower position (about 1/3 of the reactor height). The raw material feed ports 7 specifically include a high-pressure solvent inlet, a catalyst inlet, etc. According to specific operation needs, at least one mother liquor inlet is also provided at the middle position (about 1/2 of the reactor height). A bottom pipe 5 is provided through the circulating gas inlet 1. The bottom pipe 5 is parallel to the axial direction of the reactor, arranged vertically, and the bottom extends into the bottom of the reactor. The outlet end of the bottom pipe 5 is close to the stirring paddle at the bottom of the reactor. The reaction raw gas (such as ethylene) is sent to the bottom of the reactor from top to bottom through the bottom pipe 5, and enters the reaction slurry to participate in the reaction after being discharged from the outlet of the bottom pipe 5. The solvent enters through the high-pressure solvent inlet, the catalyst raw material enters through the catalyst inlet, the mother liquor enters through the mother liquor inlet, the slurry containing the reaction product is discharged through the slurry outlet 6, the solvent gas and the unreacted gas raw material are discharged through the top circulating gas outlet 2 and then collected and processed by the subsequent collection device.

In a specific embodiment, 6 to 10 circulating gas inlets 1 are arranged in a circular array on the top end cap, and correspondingly, 6 to 10 bottom plugs 5 are also arranged and installed vertically downward in the reactor. For example, in a certain embodiment, referring to FIG. 3 , 8 circulating gas inlets 1 are arranged, and correspondingly, 8 bottom plugs 5 are also arranged, and at least two circulating gas outlets 2 are arranged, preferably, they are arranged symmetrically along the center, and the diameter of the circulating gas outlet 2 is larger than the circulating gas inlet 1, so that the gas solvent and the unreacted gas raw material are discharged in time, and a large amount of latent heat of vaporization can be taken out at the same time. As a preferred embodiment, the bottom of the bottom plug 5 is arranged in a curved shape toward the center of the reactor, and its outlet end is close to the stirring plate slurry. With this structural arrangement, the reaction gas raw material can be quickly dispersed. When the raw gas is discharged from the outlet, it is immediately broken up by the agitator and dispersed more quickly in the reaction slurry to avoid local concentrated reaction. As a more preferred embodiment, referring to Figure 4, the bottom tube 5 can be further provided with a spoiler baffle 501, which is a thin round rod and is arranged on the bottom tube 5 from top to bottom. The spoiler baffle 501 has a spoiler effect and can cooperate with the stirring equipment to further improve the dispersion effect of the reaction materials.

As a preferred embodiment, a flushing solvent feed pipe 4 is set through the flushing solvent inlet 3 at the top and connected to the flushing dispersion disk. A solvent with a certain pressure is introduced from the top to flush the inside of the reactor (including the inner wall, stirring equipment, etc.) to avoid material adhesion.

In order to solve the problem of poor stirring, dispersing and heat removal effects of the reactor, the stirring device used in the present invention is a pitched blade frame stirrer. Referring to FIG2 , the pitched blade frame stirrer includes 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 with 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. Referring to FIG6 , the transverse paddle 10 is 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 (refer to FIG9 ): 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 produce an up-and-down flow effect, 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 small flow resistance during rotation and is suitable for stirring the ultra-high molecular weight polyethylene of the viscosity system.

As a preferred embodiment, 2-4 vertical paddles 9 can be provided as needed, and the vertical paddles 9 are arranged at equal intervals with the stirring shaft 8 as the central axis, for example, 4, 3 or 2 are arranged at equal intervals. For example, in a specific embodiment, referring to FIG. 2 , two vertical paddles 9 are symmetrically provided with the stirring shaft 8 as the symmetry axis, and the vertical paddles 9 are specifically rectangular long strips.

Referring to Figure 5, as a 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, 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, reducing the unevenness in the reaction system and improving the stirring effect.

As a preferred embodiment, the transverse paddle 10 is arranged in parallel along the transverse direction between the stirring shaft 8 and the vertical paddle 9, 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 needed. For example, in the specific embodiment of the present invention, 4 rows are specifically arranged. In the embodiment of the present invention, the transverse paddle 10 is 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. Such a structure can make the transverse paddles 10 on both sides produce up and down flow fields with different flow directions, and the liquid stirring and dispersing effect is better (refer to Figure 9). Furthermore, the transverse paddle 10 can be a flat plate or an arc plate, which is better than the flat arc plate. Referring to Figure 2, the transverse paddle 10 structure of the arc plate is shown. The use of an arc plate allows the fluid to flow along a certain curve, can smoothly guide the fluid movement, and can reduce the generation of vortices. The arc plate can also generate stronger liquid driving force and shear force, reduce the dead zone in the agitator, and the liquid is more easily pushed and stirred to the dead zone area, reducing the possibility of uneven mixing.

As a preferred embodiment, the bottom of the inclined blade frame agitator preferably adopts an arc bottom structure that is compatible with the bottom of the reactor, and a small gap can be retained with the bottom of the reactor. This will be beneficial to the stirring of the space at the bottom of the reactor, avoiding the sedimentation of product particles here and causing uneven slurry concentration in the upper and lower parts of the reactor, thereby ensuring the slurry concentration discharged from the overflow outlet.

As a preferred embodiment, in order to improve the stability of the stirring device, the present invention can install a bottom bearing 12 at the bottom of the stirred reactor through a bracket as needed. The bottom bearing 12 is installed at the end of the stirring shaft 8 of the stirring device to stabilize the stirring device.

In order to improve the reaction heat removal efficiency of the device, the present invention adopts the design of the inner jacket heat removal mechanism, and the specific technical scheme is as follows: with reference to FIG. 2 and FIG. 8, the inner jacket heat removal mechanism is arranged close to the inner wall of the reactor shell 16, and the inner jacket heat removal mechanism mainly includes a heat exchange wall 15 whose shape is adapted to the reactor cylinder, and the heat exchange wall 15 is arranged at intervals with the inner wall of the reactor shell 16, and is supported and connected by a flow guide support 13, that is, a flow guide support 13 is arranged between the heat exchange wall 15 and the inner wall of the reactor shell 16, and the flow guide support 13 is arranged in a spiral winding manner. On the cylindrical surface of the cylinder, the flow guide support 13 is arranged in a spiral winding and tilted manner (as shown in FIG. 7), and the angle between the flow guide support 13 and the shell along the axial direction is 30-60°, for example, in a specific embodiment, a 45° tilting arrangement is adopted. At the lower head of the reactor, the flow guide support 13 is arranged in a concentric circle manner. In practical applications, it is difficult to set up an inner jacket structure at the upper and lower heads due to too many openings and difficulty in manufacturing. The inner jacket can also be replaced by an outer jacket or a half-pipe jacket.

In this embodiment, the flow guide supports are arranged at an interval of 2-20 cm, preferably 2-10 cm, more preferably 3-6 cm, for example, 5 cm in a specific embodiment. The width of the flow guide support is 2-8 cm, preferably 3-5 cm, for example, 4 cm in a specific embodiment, and the gap width of the formed inner jacket cavity is the same as the width of the flow guide support. In addition, a channel or notch for the heat exchange medium to pass through is provided on the flow guide support 13, and mutually connected chambers 14 are formed between the flow guide support 13 and the flow guide support 13, and between the flow guide support 13 and the heat exchange wall 15 and the inner wall of the reactor shell 16. A heat exchange medium outlet 18 connected to the chamber 14 is provided at the upper end of the inner jacket, and a heat exchange medium inlet 11 connected to the chamber 14 is provided at the lower end. When working, the heat exchange medium (preferably cooling water) is introduced from the lower end inlet, and the heat exchange medium flows through each chamber 14, and finally flows out from the heat exchange medium outlet 18 at the upper end, and the heat exchange medium is connected to the external heat exchange equipment to complete the cyclic heat exchange. By setting in this way, a heat exchange medium channel spiraling upward can be formed on the surface of the reactor. This optimized flow channel structure helps to improve the flow field state, ensure that the fluid effectively exchanges heat between the flow guide support and the heat exchange wall, avoid dead zones and short circuits, and improve heat exchange efficiency.

As a specific implementation, in order to further improve the heat exchange efficiency, the chambers 14 are distributed up and down along the reactor shell 16 to form a multi-stage parallel passage structure, and each is provided with a heat exchange medium inlet and outlet. This arrangement form has a better heat exchange effect. For working conditions that require heat preservation, hot water can be introduced as needed to meet more complex operation and use requirements.

As a preferred embodiment, the heat exchange wall 15 is made of thin-walled stainless steel, and stainless steel with good thermal conductivity and corrosion resistance is selected to improve the heat exchange performance while meeting the slurry polymerization reaction. At the same time, due to the supporting effect of the guide support 13, the pressure bearing capacity per unit area of the heat exchange wall 15 is improved, and it can still withstand very high pressure in a relatively thin state, thereby meeting the use requirements of the slurry method under higher pressure.

As a preferred embodiment, referring to FIG. 8 , a spoiler 17 is provided on the flow guide support. For example, a plurality of metal thorns are irregularly provided on the side of the flow guide support 13. Specifically, a tack-shaped metal needle can be provided. When the heat exchange medium flows through, these spoilers 17 increase the Reynolds number of the heat exchange medium, increase the turbulent flow state of the heat exchange medium, and further improve the heat exchange efficiency.

When the kettle-type stirred reactor of the present invention continuously produces ultra-high molecular weight polyethylene by the slurry process, the reaction raw materials (including solvent hexane, raw materials ethylene, butene, hydrogen and catalyst, etc.) are continuously fed from various feed ports, and polymerization is carried out in the polymerization kettle under the stirring and dispersing action of the inclined blade frame stirrer, and the slurry containing the reaction product is continuously discharged from the slurry outlet and sent to the next process for further treatment. The schematic diagram of the process of slurry flow and heat removal in the reactor is shown in Figure 9. The inclined blade frame stirrer causes the liquid to produce a complex flow field and flow effect, achieving a better stirring and dispersing effect. At the same time, the inner jacket heat removal mechanism can timely and efficiently remove the reaction heat from the reaction system, and the evaporated solvent gas and a small amount of unreacted gas raw materials are discharged from the top circulating gas outlet with part of the latent heat, thereby ensuring the smooth progress of the polymerization reaction as a whole.

The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in 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 present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims (10)

1. A stirred reactor for producing polyolefins by a slurry process, comprising a stirred reactor body with a stirring device inside, characterized in that: The top cover of the stirring reactor body is provided with a plurality of circulating gas inlets (1) and a plurality of circulating gas outlets (2), and a bottom plug pipe (5) is provided through the circulating gas inlet (1) for delivering the raw material gas to the bottom of the reactor. The reactor shell (16) of the stirred reactor body is provided with at least one slurry outlet (6) for overflow discharge and at least one raw material feed port (7). An inner jacket heat removal mechanism is arranged on the inner wall of the reactor shell (16) of the stirring reactor body, and the stirring device adopts an inclined blade frame type stirrer. 2. The stirred tank reactor for producing polyolefins by a slurry process according to claim 1, characterized in that the bottom-inserted pipe (5) is arranged vertically, and the bottom of the bottom-inserted pipe (5) extends into the bottom of the reactor; And/or, the bottom of the bottom-inserted tube (5) is arranged in a curved shape toward the center of the reactor, and the outlet of the bottom-inserted tube (5) is close to the paddle of the inclined blade frame agitator; And/or, the circulating gas inlets (1) are provided with 6 to 10 pieces, which are arranged in a circular array on the top end cap, and the bottom plugs (5) are provided with 6 to 10 pieces correspondingly, which are all installed vertically downward in the reactor; And/or, at least two circulating gas outlets (2) are provided, which are symmetrically arranged along the center; And/or, the top cover of the stirred reactor body is also provided with at least one flushing solvent inlet (3), through which a flushing solvent feed pipe (4) is arranged and connected to a flushing dispersion disk. 3. A stirred tank reactor for producing polyolefins by a slurry process according to claim 1, characterized in that the inner jacket heat removal mechanism comprises a heat exchange wall surface (15), a gap is formed between the heat exchange wall surface (15) and the inner wall of the reactor shell (16), and a flow guide support (13) is spirally arranged in the gap, Interconnected chambers (14) are formed between the flow guide supports (13) and between the flow guide supports (13) and the heat exchange wall surface (15) and the inner wall of the reactor shell (16). 4. A stirred tank reactor for producing polyolefins by a slurry process according to claim 3, characterized in that the angle between the flow guide support (13) and the reactor shell (16) along the axial direction is 30-90°; And/or, the flow guide supports (13) are arranged adjacent to each other at a distance of 2 to 20 cm, and the gap thickness of the inner jacket heat removal mechanism along the radial direction of the reactor shell (16) is 2 to 8 cm. 5. The stirred tank reactor for producing polyolefins by a slurry process according to claim 3, characterized in that the side of the flow guide support (13) is irregularly provided with spoilers (17) for increasing the turbulent flow of the heat exchange medium; And/or, the heat exchange wall surface (15) is made of thin-walled stainless steel; And/or, the upper part of the reactor shell (16) is provided with a heat exchange medium outlet (18) connected to the chamber (14), and the lower part is provided with a heat exchange medium inlet (10), and the heat exchange medium outlet (18) and the heat exchange medium inlet (10) are provided with one or more groups, and the cooling medium flows from bottom to top through the inner jacket heat removal mechanism; And/or, the chambers (14) are distributed up and down along the reactor shell (16) to form a multi-section parallel passage structure. 6. The stirred tank reactor for producing polyolefins by a slurry process according to claim 1, characterized in that 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 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 tilted at a certain angle relative to a horizontal plane perpendicular to the stirring shaft (8). 7. A stirred tank reactor for producing polyolefins by a slurry process according to claim 6, characterized in that 2 to 4 vertical paddles (9) are provided; And/or, the vertical paddles (9) are arranged at equal intervals with the stirring shaft (8) as the central axis; And/or, the vertical paddle plate (9) is a rectangular strip-shaped plate, 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 15-45°. 8. A stirred tank reactor for producing polyolefins by a slurry process according to claim 6, characterized in that the transverse paddles (10) are arranged in 3-6 rows; And/or, 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; and/or, the transverse paddle plate (10) is a flat plate or an arc-shaped plate; And/or, 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 paddles (10) adjacent to each other on the same side flip in opposite directions relative to the horizontal plane. 9. A kettle-type stirred reactor for producing polyolefins by a slurry process according to claim 1, characterized in that a bottom bearing (12) is installed at the bottom of the reactor body of the stirred reactor through a bracket, and the bottom bearing (12) is installed at the end of the stirring shaft (8). 10. A process for producing polyolefins by a slurry process, characterized in that a continuous slurry reaction is carried out using the tank-type stirred reactor according to any one of claims 1 to 9, the process comprising: The monomer raw material gas is continuously fed in from the circulating gas inlet (1), and enters the slurry from the bottom of the reactor through the bottom plug pipe (5), and other raw materials including solvent and catalyst are continuously fed in from the raw material feed port (7); All the reactant raw materials are polymerized under the stirring action of the inclined blade frame stirrer, and after the reaction, the slurry containing the reaction product is continuously discharged through the slurry outlet (6); The evaporated solvent gas and unreacted raw material gas are continuously discharged from the circulating gas outlet (2) along with the latent heat of vaporization. At the same time, the inner jacket heat removal mechanism removes the reaction heat from the reaction system.