Plate-type stirring reaction device and process for producing high-consistency polyethylene by slurry process

Abstract

The present invention relates to a plate-type stirring reaction device and process for producing high-consistency polyethylene by a slurry process, wherein a plurality of circulating gas inlets and a plurality of circulating gas outlets are arranged on the top end cap of the reactor, a bottom plug is arranged through the circulating gas inlet, at least one slurry outlet and at least one raw material feed port are arranged on the reactor shell, an inner jacket heat removal mechanism is arranged on the inner wall of the reactor shell, and a plate-type stirrer is adopted in the reactor. Compared with the prior art, the kettle-type stirring reactor is advantageous in improving the mixing efficiency and forming a uniform solid suspension by means of a plate-type stirrer with a through-flow hole, which is advantageous in the polymerization reaction of materials such as ethylene monomer and catalyst, and at the same time, combined with the inner jacket heat removal mechanism, the heat removal efficiency is improved, agglomeration and implosion phenomena are avoided, and it is advantageous in preparing polyethylene products with consistent molecular weight distribution and particle size.

Description

Technical Field

[0001] The invention relates to the technical field of polyolefins, and in particular to a plate-type stirring reaction device and a process for producing high-consistency polyethylene by a slurry process. Background Art

[0002] Polyethylene (PE) is a thermoplastic resin obtained by polymerization of ethylene monomers. Among them, ultra-high molecular weight polyethylene (UHMWPE) is a widely used type of polyethylene. Ultra-high molecular weight polyethylene is a linear 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.

[0003] The slurry process is a relatively mature process for producing polyethylene. Specifically, an aliphatic hydrocarbon inert solvent and a monomer are dispersed in a solvent, a polymer is generated under the action of a catalyst, and the polymer particles are suspended in the solvent. According to the different forms of reactors, it is divided into a tubular slurry process and a kettle slurry process. At present, the kettle slurry process is used in the vast majority. When preparing polyethylene in a kettle slurry, the stirred reactor is the core device, which directly determines the product quality.

[0004] The existing technology is more mature stirred reactor such as Figure 1 As shown, a turbine agitator is used. In the ultra-high molecular weight polyethylene system, the stirring effect of this agitator 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, due to the ultra-high molecular weight of UHMWPE, it is easy to swell and settle during the polymerization process, resulting in a gradient of slurry concentration in the kettle. 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.

[0005] 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 117482875 A discloses a production device for synthesizing 1-octene, which discloses heat exchange by installing a heat exchange inner coil between the stirring paddle and the outer wall in the reactor. However, 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 110918018 A discloses a combined heat removal method for a kettle-type slurry polyethylene reactor, which discloses the removal of polymerization reaction heat by using three combinations 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 thickness of the reactor shell.

[0006] High-end polyethylene is a polyolefin product with high technology content, high application performance and high market value. It is widely used in various high-value fields, including medical field, new energy battery diaphragm materials, high-end filter materials, etc. This places high demands on the super consistency of polyethylene (microstructure consistency, molecular weight consistency, particle size consistency). Due to the above problems existing in existing production equipment, it is difficult to meet the production of high-end polyethylene. Therefore, how to provide a plate stirring reaction device and process for producing high-consistency polyethylene by slurry method is an urgent problem to be solved in this field. Summary of the invention

[0007] The purpose of the present invention is to solve the above problems and provide a plate-type stirring reaction device and process for producing high-consistency polyethylene by a slurry process.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A plate-type stirring reaction device for producing high-consistency polyethylene by a slurry process, comprising a reactor body provided with a stirring device inside;

[0010] The reactor body is a kettle reactor, and a top head is provided with a plurality of circulating gas inlets and a plurality of circulating gas outlets, and a bottom plug pipe is provided through the circulating gas inlet to deliver the raw material gas to the bottom of the reactor;

[0011] The reactor shell of the reactor body is provided with at least one slurry outlet as overflow discharge and at least one raw material feed port;

[0012] An inner jacket heat removal mechanism is arranged on the inner wall of the reactor shell of the reactor body, and the stirring device adopts a multi-stage plate stirrer, and the paddle of the plate stirrer is a through-flow paddle plate with through-flow holes.

[0013] 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;

[0014] 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 plate agitator; this structural arrangement enables the reaction gas raw material to be quickly dispersed, and 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.

[0015] And / or, the bottom-inserted tube is provided with a jacket outside, through which a heat exchange medium can be introduced, and when the device is running stably, heat can be removed by introducing a cooling medium (such as cooling water);

[0016] 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 pipes are provided with 6 to 10 pieces correspondingly, which are all installed vertically downward in the reactor, and the multiple bottom pipes are conducive to the dispersion of the polymerization gas;

[0017] And / or, at least two circulating gas outlets are provided, which are symmetrically arranged along the center;

[0018] And / or, the top head of the 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 is connected to a flushing dispersion disk, and 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.).

[0019] As a preferred technical solution of the present invention, the plate agitator comprises:

[0020] A stirring shaft is vertically extended in the kettle reactor;

[0021] Multi-stage paddle blades are arranged along the axial direction of the stirring shaft and include a plurality of blade plates extending radially from the stirring shaft;

[0022] The blade plate is provided with an opening portion, and the blade plate is evenly provided with through-flow holes in the area outside the opening portion, so that the blade plate forms a through-flow paddle plate.

[0023] As a preferred technical solution of the present invention, the blade plate includes a root portion connected to the outer peripheral surface of the stirring shaft, and a substantially rectangular paddle portion radially arranged away from the stirring shaft and extending radially outward from the root portion;

[0024] The height of the root portion is less than the height of the corresponding paddle portion;

[0025] And / or, the roots may be arranged in a stepped manner, extending radially outward from the stirring shaft and gradually becoming wider.

[0026] As a preferred technical solution of the present invention, the height of the root portion is 30% to 50% of the height of the corresponding paddle portion, and the width of the root portion is 30% to 60% of the overall width of the corresponding blade plate;

[0027] and / or, the opening area of ​​the opening portion is 5-50%, preferably 10-20%, of the total area of ​​the corresponding blade plate, and the opening portion is arranged in the paddle portion or the middle area;

[0028] And / or, grille bars are arranged on the opening portion;

[0029] And / or, the diameter of the flow hole is 1-10 cm.

[0030] As a preferred technical solution of the present invention, the multi-stage paddle blades are arranged at 2 to 4 stages along the axial direction of the stirring shaft;

[0031] The lower wing of the blade plate at the lower layer is close to the bottom of the kettle reactor, and the contour of the lower wing is arc-shaped, matching the shape of the bottom of the kettle reactor.

[0032] As a preferred technical solution of the present invention, the multi-stage paddle blades gradually widen from top to bottom along the axial direction of the stirring shaft, and each layer of paddle blades is symmetrically arranged in a pair along the stirring shaft, and the upper and lower adjacent paddle blades are staggered at a certain angle, and the angle ranges from 15 to 90°.

[0033] 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;

[0034] 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.

[0035] 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°;

[0036] 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.

[0037] 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.

[0038] And / or, the heat exchange wall surface is made of thin-walled stainless steel;

[0039] 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, the heat exchange medium outlet and the heat exchange medium inlet are provided with one or more groups, 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 helps to improve the heat exchange effect, and the heat exchange medium outlet and the heat exchange medium inlet are provided with one or more groups.

[0040] And / or, 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 provided.

[0041] As a preferred technical solution of the present invention, a bottom bearing is installed at the bottom of the reactor body through a bracket, and the bottom bearing is installed at the end of the stirring shaft.

[0042] A process for producing high-consistency polyethylene by a slurry process, using the plate-type stirring reactor described above to carry out a continuous slurry reaction, the process comprising:

[0043] 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 solvent and catalyst are continuously fed in from the raw material feed port;

[0044] All the reactant raw materials undergo polymerization reaction under the stirring action of the plate stirrer, and after the reaction, the slurry containing the reaction product continuously overflows and discharges through the slurry outlet;

[0045] The evaporated solvent gas and unreacted raw material gas are continuously discharged from the circulating gas outlet and take away the latent heat of vaporization of the solvent. At the same time, the inner jacket heat removal mechanism continuously removes the reaction heat (through circulating water) out of the reaction system.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The present invention adopts a plate agitator with multi-stage paddle blades. The paddle blades arranged along the axial direction of the stirring shaft cause the slurry in the kettle reactor to generate a large-scale vortex, forming a uniform mixing of the slurry in the whole kettle range, and achieving better heat transfer, mass transfer, stirring and dispersing effects. The blade plate is provided with a hollow opening portion, which can better adapt to the polyethylene polymerization reaction system, and at the same time help to form a complex flow field, which is beneficial to the reaction. The through-flow holes are evenly arranged on the blade plate to form a through-flow paddle plate, and a strong tail vortex is generated behind the through-flow hole, which will obtain some additional driving force, increase the turbulent kinetic energy and dissipation rate of the fluid in the slurry, improve the mixing efficiency, help to achieve the suspension of particles at a lower power, and form a particle suspension with a uniform slurry concentration in the whole kettle range, which is very beneficial to the reaction to obtain a high-consistency polyethylene product with consistent molecular weight distribution and particle size, and at the same time improve the slurry's lifting ability for polyethylene, and achieve uniform suspension of particles with less power.

[0048] 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 and making the heat exchange wall surface with thin-walled material, which is in direct 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 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.

[0049] The kettle-type stirred reactor provided by the present invention, when carrying out continuous slurry reaction to prepare polyolefins, effectively solves the problems commonly existing in the continuous preparation of polyolefins by the slurry method, such as poor stirring and dispersion effect, gradient of slurry concentration in the kettle, low heat removal efficiency, etc., through the stirring effect of the plate stirrer, together with the combination of heat removal by the inner jacket and heat removal by latent heat of vaporization, and is conducive to the production of polyethylene with super consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a structural schematic diagram of an existing turbine kettle stirred reactor;

[0051] Figure 2 A schematic cross-sectional structure diagram of a plate-type stirring reaction device according to an embodiment of the present invention;

[0052] Figure 3 It is a top view schematic diagram of a plate-type stirring reaction device according to an embodiment of the present invention;

[0053] Figure 4 This is a schematic diagram of the main structure of a plate-type agitator according to an embodiment of the present invention;

[0054] Figure 5 It is a schematic diagram of the top view of the plate-type agitator according to an embodiment of the present invention;

[0055] Figure 6 for Figure 2 A partial enlarged view of point I in the middle;

[0056] Figure 7 This is a schematic structural diagram of a bottom insert pipe according to an embodiment of the present invention;

[0057] 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 bar; 502-jacket; 6-slurry outlet; 7-raw material feed inlet; 8-agitation shaft; 9-narrow paddle blades; 10-wide paddle blades; 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; 100-blade plate; 1001-opening portion; 1002-through-flow hole; 1003-root; 1004-paddle portion. DETAILED DESCRIPTION

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] Figure 1 This is an existing kettle-type stirred reactor used for the production of ultra-high molecular weight polyethylene. A turbine agitator is used inside the reactor, and three turbine stirring blades are arranged in sequence from top to bottom on the stirring shaft. 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, very unsatisfactory dispersion effect, easy sedimentation, and a gradient of slurry concentration in the reactor. In addition, the heat removal effect of the kettle-type stirred reactor is also unsatisfactory. The poor dispersion effect and poor heat removal effect result in a large number of local hot spots inside the reactor, which cause the reaction materials to agglomerate and stick to the wall, making it difficult to produce and prepare polyethylene products with super consistency.

[0063] The present invention provides a kettle-type stirring reaction device for producing super-consistent polyethylene by a slurry process. The kettle-type stirring reactor replaces the turbine stirrer with a plate stirrer as a stirring device, and an inner jacket heat removal mechanism is arranged on the inner wall of the reactor shell. The reaction device adopts a plate stirrer with multi-stage paddle blades, and through-flow holes are evenly arranged on the blade plate to form a through-flow paddle plate. A strong tail vortex is generated behind the through-flow hole, which is conducive to the polymerization reaction of ethylene monomer and materials such as catalysts, and helps to obtain a high-consistency polyethylene product with consistent molecular weight distribution and particle size. 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.

[0064] Figure 2The schematic diagram of the structure of a plate-type stirring reaction device provided by the present invention is shown, including a reactor body, the main body of which is a cylindrical reactor shell 16, a stirring device is installed in the reactor, a reducer is installed at the upper end of the reactor through a bracket, a motor is 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 reactor. The stirring reactor is provided with a support for installation, a manhole is provided at the top or bottom, etc., which are conventional accessories of the stirring reactor and will not be described in detail here.

[0065] Reference Figure 2 and Figure 3 The stirred reactor is a continuous slurry reaction device, and its top head is provided with several circulating gas inlets 1 for introducing ethylene raw material gas, several circulating gas outlets 2 for discharging gas solvent hexane 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 material 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.

[0066] 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. Figure 3 , 8 circulating gas inlets 1 are provided, and correspondingly 8 bottom plug pipes 5 are also provided;

[0067] At least two circulating gas outlets 2 are provided, preferably, they are symmetrically arranged 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 unreacted gas raw materials can be discharged in time, and a large amount of latent heat of vaporization can be taken out at the same time.

[0068] As a preferred embodiment, the bottom of the bottom-inserted tube 5 is bent toward the center of the reactor, and its outlet 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 stirrer and more quickly dispersed and absorbed in the reaction slurry to avoid local concentrated reaction. As a more preferred embodiment, refer to Figure 7 The bottom tube 5 can be further provided with a spoiler bar 501, which is a thin round rod and is arranged on the bottom tube 5 from top to bottom. The spoiler bar 501 has a spoiler effect and can cooperate with the stirring device to further improve the dispersion effect of the reaction material. More preferably, the bottom tube 5 is provided with a jacket 502, through which a heat exchange medium (such as cooling water) can be introduced. When the device is running smoothly, the polymerization reaction heat can be further removed by introducing a cooling medium.

[0069] 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.

[0070] The present invention adopts a multi-stage plate stirrer, referring to Figure 2 , Figure 4 , including: a stirring shaft 8, which is vertically extended in the reactor; a multi-stage paddle blade, arranged along the axial direction of the stirring shaft 8, including a plurality of blade plates 100 extending radially from the stirring shaft 8, wherein the blade plate 100 is provided with an opening portion 1001, and the blade plate 100 is evenly provided with through-flow holes 1002 in the area outside the opening portion 1001, so that the blade plate 100 forms a through-flow paddle plate.

[0071] The present invention provides a plate stirrer with multi-stage paddle blades. Figure 1 The traditional turbine agitator shown, the paddle blades arranged along the axial direction of the stirring shaft 8 can cause the slurry in the reactor to produce a large-scale vortex, forming a slurry flow mixing in the whole kettle, and achieving better heat transfer, mass transfer, stirring and dispersion effects. The blade plate 100 is provided with a hollow opening portion 1001, which can make the plate agitator better adapt to the polyethylene polymerization reaction system, help to form a more complex flow field, which is beneficial to the reaction. The through-flow paddle plate formed by the through-flow holes 1002 evenly arranged on the blade plate 100 generates a strong tail vortex behind the through-flow holes 1002, which helps to achieve particle suspension at a lower power, and form a particle suspension with a uniform slurry concentration in the whole kettle, which helps to improve the consistency of the product, which is very beneficial to the reaction to obtain a high-consistency polyethylene product with consistent molecular weight distribution and particle size.

[0072] As a preferred embodiment, the blade plate 100 includes a root portion 1003 connected to the outer peripheral surface of the stirring shaft 8, and a substantially rectangular paddle portion 1004 radially arranged away from the stirring shaft 8 and extending radially outward from the root portion 1003. The height of the root portion 1003 is less than the height of the corresponding paddle portion 1004. The root portion 1003 can be arranged in a stepped manner, extending radially outward from the stirring shaft 8 and gradually widening (such as Figure 4 ).

[0073] Preferably, the height of the root 1003 is 30% to 50% of the height of the corresponding paddle portion 1004, for example, 45%, and the width of the root 1003 is 30% to 60%, for example, 50%, of the overall width of the corresponding blade plate 100. The height of the root 1003 is less than the height of the corresponding paddle portion 1004.

[0074] As a preferred embodiment, the opening area of ​​the opening portion 1001 is 5-50% of the total area of ​​the corresponding blade plate 100, preferably 10-20%. The opening portion 1001 is preferably arranged in the paddle portion 1004 or the middle area. The shape of the opening portion 1001 is not particularly limited, including square, rectangular or circular. The hollow opening portion 1001 can make the plate agitator better adapt to the polyethylene polymerization reaction system, and also help to form a more complex flow field, which is beneficial to the reaction. As a modified or more preferred embodiment, grid bars can be arranged on the opening portion 1001, which can further divide the fluid and increase the turbulence. The grid bars can provide a path for the strong downward flow along the axial direction of the paddle blades, which helps to form a flow pattern of large axial circulation of the entire kettle within the entire kettle, that is, the slurry flows upward at the bottom of the kettle, and changes direction at the liquid surface, forming a rapid downward flow on the stirring axis.

[0075] As a preferred embodiment, the aperture of the through-flow hole 1002 is 1~10cm, preferably 4~8cm. The aperture of the through-flow hole 1002 affects the flow field. If the aperture is too large, the hole flow velocity is small, and sufficient shear stress cannot be generated, and a sufficiently small vortex cannot be generated, and the local eddy diffusion intensity is insufficient; if the aperture is too small, the energy dissipation caused by the friction between the fluid and the hole increases, thereby affecting the effect of enhancing the eddy diffusion.

[0076] As a preferred embodiment, the multi-stage paddle blades are arranged in 2 to 4 stages along the axial direction of the stirring shaft 8, and the multi-stage paddle blades gradually become wider from top to bottom along the axial direction of the stirring shaft 8. Each layer of paddle blades is symmetrically arranged in a pair along the stirring shaft 8, and the upper and lower adjacent paddle blades are staggered at a certain angle, and the angle ranges from 15 to 90°.

[0077] like Figure 2 , Figure 4As shown, in a specific embodiment, a two-stage plate agitator is used, and the paddle blades are provided with two layers along the axial direction of the stirring shaft 8, including narrow paddle blades 9 on the upper layer and wide paddle blades 10 on the lower layer. Polyethylene is prepared by a continuous slurry method, and the raw materials enter from the bottom. The large paddle blades on the lower layer help to form a large circulation flow in the entire kettle. The particles are transported from the bottom of the kettle to the liquid surface through the circulation loop in the kettle, making the slurry concentration in the kettle more uniform. At the same time, the large blades at the bottom also make the local heat transfer coefficient of the reactor wall evenly distributed, improving the heat transfer coefficient. Paddle blades of different sizes are also conducive to maintaining the balance of the pumping capacity of the upper and lower paddle plates. The narrow paddle blade 9 is provided with a long strip opening portion on its paddle portion, and a through-flow hole is provided in the inner area of ​​the long strip opening portion; the wide paddle blade 10 is provided with a square opening portion in the middle area of ​​the blade plate, and a through-flow hole is provided in the area outside the square opening portion. The through-flow hole helps to obtain a high-consistency polyethylene product with consistent molecular weight distribution and particle size. The root of the wide paddle blade 10 is stepped, and the lower wing of the blade plate of the wide paddle blade 10 is arc-shaped, matching the bottom shape of the kettle reactor, and the lower wing is close to the bottom of the reactor. The upper and lower paddle blades are staggered at an angle of about 35° (such as Figure 5 As shown in the figure, the paddle blades arranged at an angle form a complex flow field distribution, which is conducive to uniform stirring of the slurry.

[0078] 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.

[0079] 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. The specific technical scheme is as follows: Figure 2 , Figure 6 , an 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, 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, an inclined arrangement of 45° is adopted. At the lower head of the reactor, the flow guide support 13 is arranged in a concentric circle manner. In practical applications, at the upper and lower heads, due to too many openings and great manufacturing difficulty, it is difficult to set the structure of the inner jacket, and the inner jacket can also be replaced by an outer jacket or a half-tube jacket.

[0080] 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 spiral upward heat exchange medium channel 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.

[0081] 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. Such a configuration has a better heat exchange effect. For working conditions that require heat preservation or heating (such as when starting work), hot water can be introduced as needed to meet complex operating requirements.

[0082] 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.

[0083] As a preferred embodiment, refer to Figure 6 A spoiler 17 is arranged on the guide support. For example, a plurality of metal thorns are irregularly arranged on the side of the guide support 13. Specifically, a rod-shaped metal needle can be arranged. 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.

[0084] 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 plate 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 plate stirrer causes the liquid to produce a large-scale circulating flow field and flow effect in the kettle, 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, which ensures the smooth progress of the polymerization reaction as a whole.

[0085] 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

1. A plate-type stirring reactor for producing high-consistency polyethylene by a slurry process, comprising a reactor body with a stirring device inside, characterized in that: The reactor body is a kettle-type reactor, and a plurality of circulating gas inlets (1) and a plurality of circulating gas outlets (2) are arranged on the top cover. A bottom plug (5) is arranged through the circulating gas inlet (1) to deliver the raw material gas to the bottom of the reactor. The reactor shell (16) of the reactor body is provided with at least one slurry outlet (6) as 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 reactor body, and the stirring device adopts a multi-stage plate stirrer, wherein the paddle of the plate stirrer is a through-flow paddle with through-flow holes; The plate stirrer comprises: A stirring shaft (8) is vertically extended in the reactor; Multi-stage paddle blades are arranged along the axial direction of the stirring shaft (8), and include a plurality of blade plates (100) extending radially from the stirring shaft (8); The blade plate (100) is provided with an opening portion (1001), and the blade plate (100) is evenly provided with through-flow holes (1002) in an area outside the opening portion (1001), so that the blade plate (100) forms a through-flow paddle plate; The aperture of the flow hole (1002) is 1-10 cm; The blade plate (100) comprises a root portion (1003) connected to the outer peripheral surface of the stirring shaft (8), and a rectangular paddle portion (1004) arranged radially away from the stirring shaft (8) and extending radially outward from the root portion (1003); The height of the root portion (1003) is smaller than the height of the corresponding paddle portion (1004); The opening portion (1001) is provided with grille bars; The multi-stage paddle blades gradually widen from top to bottom along the axial direction of the stirring shaft (8), and a pair of paddle blades in each layer are symmetrically arranged along the stirring shaft (8); The lower wing of the blade plate (100) at the lower layer is close to the bottom of the reactor, and the contour of the lower wing is arc-shaped, matching the shape of the bottom of the reactor; 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).

2. The plate-type stirring reaction device according to claim 1, characterized in that: The bottom-inserted tube (5) is arranged vertically, and the bottom of the bottom-inserted tube (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 plate-type agitator; And / or, the bottom insert tube (5) is provided with a jacket outside; 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 reactor body is further 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. The plate-type stirring reaction device according to claim 1, characterized in that: The root portion (1003) is arranged in a stepped manner, extending radially outward from the stirring shaft (8) and gradually becoming wider.

4. The plate-type stirring reaction device according to claim 3, characterized in that: The height of the root portion (1003) is 30% to 50% of the height of the corresponding paddle portion (1004), and the width of the root portion (1003) is 30% to 60% of the overall width of the corresponding blade plate (100); And / or, the opening area of ​​the opening portion (1001) is 5-50% of the total area of ​​the corresponding blade plate (100), and the opening portion (1001) is arranged in the paddle portion (1004) or in the middle area.

5. The plate-type stirring reaction device according to claim 1, characterized in that: The multi-stage paddle blades are arranged in 2 to 4 stages along the axial direction of the stirring shaft (8).

6. The plate-type stirring reaction device according to claim 5, characterized in that: The upper and lower adjacent blades are staggered at a certain angle, and the angle ranges from 15 to 90 degrees.

7. The plate-type stirring reaction device according to claim 1, 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) 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 (16) is 2-8 cm.

8. The plate-type stirring reaction device according to claim 1, characterized in that: The side surfaces of the flow guide support (13) are 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 portion of the reactor shell (16) is provided with a heat exchange medium outlet (18) connected to the chamber (14), and the lower portion is provided with a heat exchange medium inlet (11), and the heat exchange medium outlet (18) and the heat exchange medium inlet (11) 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.

9. A process for producing high-consistency polyethylene by a slurry process, characterized in that: A continuous slurry reaction is carried out using a plate-type stirring reactor as described in any one of claims 1 to 8, wherein the process comprises: 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 undergo a polymerization reaction under the stirring action of the plate stirrer, and after the reaction, a slurry containing the reaction product continuously overflows and is discharged through the slurry outlet (6); The evaporated solvent gas and unreacted raw material gas are continuously discharged from the circulating gas outlet (2) and take away the latent heat of vaporization of the solvent. At the same time, the inner jacket heat removal mechanism continuously removes the reaction heat from the reaction system.

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