Modularized reaction device for preparing polyolefin by solution method

Abstract

The invention discloses a modularized reaction device for preparing polyolefin by a solution method, and belongs to the technical field of polyolefin preparation, and the modularized reaction device comprises a container which comprises a cylinder formed by vertically stacking a plurality of detachable module units; the stirring device is configured to mix the materials in the container; the heat removal system comprises inner coil pipes correspondingly arranged in the module units and is used for circulating a cooling medium to conduct heat in the barrel; and the feeding system comprises internally-inserted feeding pipes correspondingly arranged in the module units and is used for releasing materials into the container. According to the requirements of production scale, the capacity, the heat removal efficiency, the feeding rate and the like can be synchronously improved by increasing and decreasing the number of the module units, and convenient and rapid adjustment and adaptation to the production requirements are achieved.

Description

Technical Field

[0001] This invention belongs to the field of polyolefin preparation technology, specifically relating to a modular reaction apparatus for preparing polyolefins by solution method. Background Technology

[0002] Polyolefin elastomers (POEs) are main-chain saturated elastic materials polymerized from monoolefins such as ethylene and propylene as the main monomers. These materials are characterized by low density and narrow molecular weight distribution, and are typically prepared using a single-active-center catalyst and solution polymerization process. Polyolefin elastomers possess excellent toughness and good processability; they are mainly used in toughening and modification of automotive materials, construction, electronics, daily consumer goods, and medical devices. In recent years, they have also seen widespread application in high-performance photovoltaic films, leading to a growing demand for them in my country.

[0003] Currently, polyolefin elastomers are mainly produced through high-temperature solution polymerization, which requires strict control over the stable existence of comonomers in liquid form within the solution and their participation in polymerization. If the monomers become gaseous, the concentration and content of comonomers in the solution will decrease, leading to an increase in the overall viscosity of the solution, which may ultimately prevent the polymerization reaction from occurring. Furthermore, at high temperatures, the presence of long branches causes the product to easily swell and agglomerate in the solvent, resulting in high viscosity. This increases stirring resistance, leading to sticking to or even clogging of the reactor, affecting continuous production and resulting in low ethylene conversion rates. Additionally, the presence of "dead volume" zones with poor flowability in the reactor can lead to violent local reactions, uneven product distribution, high system viscosity, difficulty in polymer devolatilization, complex devolatilization processes, and high energy consumption.

[0004] Patent application number 202421552862.0 discloses an inclined blade stirring device for preparing polyolefins using a slurry method. Compared with existing technologies, this device employs an inclined blade paddle stirrer to achieve sufficient liquid flow during the reaction process, ensuring complete mixing of substances in the reaction system, avoiding dead zones, preventing sedimentation and accumulation of reactants, improving heat and mass transfer, and contributing to increased polymerization efficiency. However, the applicant believes that the device still has room for improvement in its technical solution. Polymer scale layers easily form on the inner wall of the reactor and the surface of internal components, leading to a reduction in effective reaction volume and affecting preparation efficiency with continued use. The scale layer adhering to the inner wall of the reactor also makes equipment cleaning difficult and reduces maintenance cycles. Summary of the Invention

[0005] The purpose of this application is to provide a modular reaction device for the solution preparation of polyolefins, which has the advantages of modularity and adjustability, high heat exchange efficiency, uniform material distribution and effective prevention of wall adhesion.

[0006] The technical solution adopted by the present invention to achieve the above objectives is as follows: A modular reaction apparatus for preparing polyolefins by solution method includes: a container, comprising a cylinder formed by vertically stacking multiple modular units; a stirring device configured to mix materials within the container; a heat removal system, including an inner coil correspondingly disposed within each modular unit for circulating a cooling medium to conduct heat to the inside of the cylinder; and a feeding system, including an inner feed pipe correspondingly disposed within each modular unit for releasing materials into the container.

[0007] Preferably, the modular units are detachably connected via flanges, and the total height and volume of the container can be adjusted by increasing or decreasing the number of modular units.

[0008] Preferably, the stirring device includes a stirring shaft extending from the top of the container, with at least three layers of stirring blades fixedly connected to the stirring shaft. The bottom layer consists of radial flow blades for radial diffusion of materials, and the remaining layers consist of axial flow blades for axial diffusion of materials.

[0009] Preferably, the heat dissipation system also includes vertical half-pipe jackets corresponding to each module unit outside the module unit. Each vertical half-pipe jacket is independent of each other but connected to the same cooling system for circulating cooling medium to dissipate heat to the outer wall of the cylinder.

[0010] Preferably, there is a gap between the inner wall of the cylinder and the outer edge of the inner coil. The inner feed pipe is vertically inserted into the gap. Finger-shaped tubes are axially spaced on the side of the inner feed pipe, and the finger-shaped tubes are connected to the inner feed pipe. The ends of the finger-shaped tubes are positioned downwards away from the inner wall of the cylinder. The axis of the finger-shaped tubes forms an angle with the axis of the inner feed pipe.

[0011] Preferably, the feeding system further includes an annular feeder, which is located at the bottom of the container and includes an annular tube. At least two sets of discharge holes are evenly distributed circumferentially above the tube wall of the annular tube. Each set of discharge holes includes at least two through holes, and the axes of the through holes in the same set intersect at a 90° angle.

[0012] Preferably, the inner wall of the module unit, the outer wall of the inner coil, and the surface of the agitator are all mechanically polished to achieve a surface roughness Ra≤0.2μm.

[0013] Preferably, each group of inner coils is independently equipped with a cooling medium inlet pipe and an outlet pipe, and the pipe walls of the inlet and outlet pipes do not interfere with the stirring device spatially.

[0014] Preferably, the container further includes end caps connected to the upper and lower ends of the cylinder, and the heat dissipation system further includes a spiral half-pipe jacket fitted to the outer wall of the end cap, wherein the spiral half-pipe jacket and each vertical half-pipe jacket work together to achieve heat conduction.

[0015] Preferably, each module unit is provided with a rinsing device at the top, including an annular rinsing pipe. The bottom of the annular rinsing pipe has rinsing holes along the circumference. The axis of the rinsing holes is at an angle to the vertical direction to ensure that the rinsing solvent can be effectively sprayed and covered to cover the inner wall of the module unit below and the surface of the inner coil.

[0016] Compared with existing technologies, this invention has the following advantages: the modular cylinder design allows for flexible volume adjustment by adding or removing units, solving the problem of fixed production capacity in traditional reactors and improving equipment adaptability; the stirring device uses a combination of radial and axial flow blades to enhance three-dimensional mixing, enabling rapid dispersion of feed and achieving uniform mixing, solving the problems of uneven mixing of high-viscosity feed and local reaction differences caused by local concentration gradients; the inner coil and outer half-pipe jacket form a dual heat exchange system, enabling zoned temperature control, improving heat transfer efficiency, and solving the problem of local overheating caused by uneven heat dissipation; the finger-shaped tube and annular distributor form a multi-directional feeding system, avoiding material accumulation and improving dispersion uniformity; the inner wall polishing treatment reduces wall adhesion and lowers cleaning difficulty; the adjustable stirring blade design enhances cleaning effect, improves heat transfer stability, and ensures stable fluid dynamic conditions for continuous production. Attached Figure Description

[0017] Figure 1 This is a schematic diagram showing the positions of the inner coil, stirring device, and flushing device inside the cylinder. Figure 2 This is a schematic diagram of a vertical half-tube jacket structure; Figure 3 This is a schematic diagram showing the positional relationship between the internal feed pipe, the internal coil, and the flushing device. Figure 4 This is a schematic diagram of the annular pipe and the discharge port; Figure 5 for Figure 4 Schematic diagram of the section where AA is located; Figure 6 This is a schematic diagram showing the distribution of flushing holes; Figure 7 This is a schematic diagram showing the positions of the spacer channel and the finger-shaped tube in Embodiment 2 of the present invention; Figure 8 This is a schematic diagram of the structure of Embodiment 3 of the present invention.

[0018] Reference numerals: Module unit 11; Head 12; Stirring shaft 21; Radial flow blade 22; Axial flow blade 23; Inner coil 3; Inlet pipe 31; Outlet pipe 32; Spacing channel 33; Vertical half-pipe jacket 4; Inlet manifold half-pipe 41; Outlet manifold half-pipe 42; Internal feed pipe 5; Finger-shaped pipe 51; Annular pipe 61; Inner hole 62; Outer hole 63; Spiral half-pipe jacket 7; Annular flushing pipe 81; Flushing hole 82; Collar 91; Retaining ring 92; Elastic reset component 93; Buoyancy drive component 94. Detailed Implementation

[0019] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings: Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] Example 1: See Figure 1 - Figure 3 A modular reaction apparatus for preparing polyolefins by solution method includes: a container, comprising a cylinder formed by vertically stacking multiple modular units 11; a stirring device configured to mix materials within the container; a heat removal system, including an inner coil 3 correspondingly disposed inside each modular unit 11 for circulating cooling medium to conduct heat to the inside of the cylinder; and a feeding system, including an inner feed pipe 5 correspondingly disposed inside each modular unit 11 for releasing materials into the container.

[0021] It should be noted that: Module unit 11 can be a detachable structural unit connected by a flange, and is implemented using a standardized ring-shaped metal component; the inner coil 3 refers to a spiral metal pipe embedded inside the module unit 11, which is made of stainless steel pipe bent into shape. Cooling medium is circulated into it to achieve directional heat dissipation in the reaction area inside the container. The cooling medium flowing in the inner coil 3 includes, but is not limited to, demineralized water; the inner feed pipe 5 has multiple feed holes; all the materials mentioned are liquid solvents. The inner feed pipe 5 releases materials into the container through the feed holes, and the various materials in the container are stirred and mixed by a stirring device.

[0022] Traditional reactors are monolithic structures with essentially fixed production capacity, making it impossible to adjust their volume according to production needs. Expanding or modifying the reactor to meet changing market demands or process optimizations is extremely difficult, inflexible, and time-consuming. In this application, by adding or removing module units 11, the container can be rapidly expanded or reduced in size, allowing for flexible volume adjustment to meet production scale requirements.

[0023] The modular unit 11 is detachably connected via flanges, and the total height and volume of the container can be adjusted by increasing or decreasing the number of modular units 11. The modular units 11 can also be connected by welding. Compared with existing technologies, traditional fixed reactors have non-adjustable volumes, requiring the replacement of the entire equipment to produce different specifications of products. This solution achieves linear expansion of reactor volume through modular design, avoiding resource waste caused by repeated equipment purchases, shortening equipment modification cycles, and solving the problem of poor production adaptability caused by fixed reactor structures. It allows the same equipment to flexibly match different batch production tasks, reducing equipment modification costs and improving equipment utilization.

[0024] The stirring device includes a stirring shaft 21 extending from the top of the container. At least three layers of stirring blades are fixedly connected to the stirring shaft 21. The bottom layer is a radial flow blade 22 for radial diffusion of materials, and the remaining layers are axial flow blades 23 for axial diffusion of materials.

[0025] It should be noted that: the stirring shaft 21 refers to the transmission component that runs through the inside of the container to drive the stirring paddle to rotate. It can be implemented by using a segmented shaft connected by a coupling to ensure that the shaft length matches the height of the modular cylinder. Radial flow blade 22 refers to a blade structure in which the blade plane is perpendicular to the axis of the stirring shaft 21. It can be achieved by using a straight blade or a folded blade design, and promotes the lateral dispersion of materials through radial shearing action. Axial flow blade 23 refers to a blade structure in which the blade plane is inclined at an angle to the axis of the stirring shaft 21. Specifically, it can be implemented by using propeller-type or turbine-type blades, which guide the material to flow axially through the inclined angle. A stirring shaft 21 extends vertically from the top of the container and is driven to rotate by an external drive device, including but not limited to a rotary motor. Radial flow blades 22 apply a shear force perpendicular to the axis to the material during rotation, diffusing the material towards the sidewalls of the container, preventing material accumulation at the bottom, and enhancing radial mixing and heat transfer. Axial flow blades 23 generate fluid motion along the axis during rotation, promoting vertical circulation and mixing of the material. Through the superposition of radial and axial flow fields, uniform material distribution in three-dimensional space is achieved. By layering and combining blade structures with different flow directions, radial dispersion and axial circulation are simultaneously enhanced within a limited space, effectively eliminating dead zones in the reactor. This solves the problem of uneven mixing of high-viscosity materials during solution polymerization, avoiding product performance differences caused by intense local reactions, while reducing stirring resistance and preventing wall adhesion. The synergistic effect of radial flow blades 22 and axial flow blades 23 results in a more uniform viscosity distribution in the reaction system, providing stable hydrodynamic conditions for continuous production.

[0026] The heat dissipation system also includes vertical half-pipe jackets 4 corresponding to each module unit 11 outside. Each vertical half-pipe jacket 4 is independent of each other but connected to the same cooling system for circulating cooling medium to dissipate heat to the outer wall of the cylinder.

[0027] It should be noted that the vertical half-pipe jacket 4 includes an inlet manifold 41 and an outlet manifold 42, as well as vertical half-pipes that are vertically attached to the outer wall of the module unit 11. The vertical half-pipes are equidistantly arranged along the axial direction of the module unit 11. The inlet manifold and the outlet manifold are connected through the vertical half-pipes. The cooling system distributes the cooling medium to each inlet manifold. The cooling medium flows through the inlet manifold, through each vertical half-pipe connected to it, and then collects at the outlet manifold before flowing out, thus achieving heat conduction to the container. The vertical half-pipe is a semi-circular cross-section pipe, and its arc surface is attached to the outer wall of the cylinder to form effective heat conduction to the container wall.

[0028] The cooling medium flowing inside the vertical half-pipe jacket 4 includes, but is not limited to, demineralized water and low-pressure steam.

[0029] In the initial stage of the reaction, the cooling system introduces low-pressure steam into the vertical half-pipe jacket 4 to conduct heat to the container and raise its temperature. When the polymerization reaction is stable, the cooling system introduces deionized water into the vertical half-pipe jacket 4 to remove heat from the container and lower its temperature.

[0030] When the cooling medium flows inside the vertical half-pipe jacket 4, heat is conducted through the metal wall of the cylinder. The independent connection of each vertical half-pipe jacket 4 allows for targeted adjustment of the cooling intensity of different module units 11 according to the temperature distribution differences in the reaction zone. For example, for the middle reaction zone with intense exothermic reaction, the cooling medium flow rate of the corresponding jacket can be increased, while the flow rate can be appropriately reduced for the lower and upper sections with lower temperatures. This scheme avoids the problem of medium flow deviation caused by uneven pressure in traditional integral jackets. At the same time, the external vertical half-pipe jacket 4 and the internal inner coil 3 form a dual heat exchange structure with internal and external cooperation. The combination of the two significantly increases the heat transfer area and heat transfer rate, effectively solving the problem of low heat transfer efficiency of high-viscosity polymer solutions. Furthermore, the external vertical half-pipe jacket 4 and the internal inner coil 3 independently control the cooling medium, and the heat dissipation intensity can be flexibly adjusted according to the needs of different reaction stages or module units 11, ensuring uniform temperature distribution in the reactor and avoiding local overheating or uneven reaction.

[0031] The outer jacket partitions correspond one-to-one with the modular units 11 that make up the cylinder. The inner coil 3 is adjusted synchronously with the addition or removal of the modular units 11, which, together with the modular cylinder structure, enables flexible expansion of production capacity while maintaining efficient heat dissipation capabilities and improving equipment adaptability. The arrangement of the inner coil 3, in conjunction with the stirring device, promotes material agitation, while the outer jacket enhances wall heat transfer. Together, they improve the flow and mixing effect of high-viscosity materials, indirectly reducing the risk of wall adhesion and improving reaction stability and product quality.

[0032] Compared to existing technologies, traditional reactors often employ an integral jacket or a single external coil, which cannot achieve zoned temperature control and has heat transfer dead zones. This solution, however, uses independently configured modular vertical half-pipe jackets 4 to ensure precise temperature control in each reaction zone, while the fully covered jacket structure eliminates heat transfer dead zones, making it particularly suitable for the rapid heat removal of high-viscosity material systems.

[0033] Through the above technical solution, this application effectively solves the problem of localized overheating caused by uneven heat dissipation in large reactors, preventing polymer adhesion to the walls or coking in high-temperature areas. The independent temperature control function for different zones maintains a balanced temperature in the reaction system, ensuring stable polymerization. Simultaneously, the modular jacket structure facilitates localized maintenance and replacement, significantly improving the reliability of equipment operation. There is a gap between the inner wall of the cylinder and the outer edge of the inner coil 3. The inner feed pipe 5 is vertically inserted into the gap. Finger-shaped tubes 51 are axially spaced on the side of the inner feed pipe 5. The finger-shaped tubes 51 are connected to the inner feed pipe 5. The ends of the finger-shaped tubes 51 are set downward away from the inner wall of the cylinder. There is an angle between the axis of the finger-shaped tubes 51 and the axis of the inner feed pipe 5.

[0034] It should be noted that the gap refers to the annular space formed between the inner wall of the cylinder and the outer edge of the inner coil 3, which is used to provide installation space for the inner feed pipe 5 and to avoid obstruction of material flow. Finger-shaped tube 51 refers to a branch tubular structure extending from the side wall of the inner feed tube 5. It is a thin tube with a diameter smaller than the main feed tube, and its end extends downwards to guide the material away from the inner wall of the container. The axial angle refers to the acute angle formed by the centerline of the inner feed tube 5 and the centerline of the finger-shaped tube 51. Specifically, it can be designed with an inclination angle of 30° to 60° to enhance the material dispersion effect by changing the fluid direction.

[0035] When the internal feed pipe 5 is inserted vertically into the module unit 11 along the axial direction of the cylinder, its body is located in the annular gap between the inner coil 3 and the cylinder wall. The outlet end of the finger-shaped pipe 51 is inclined downwards towards the center of the reaction zone, allowing the material to enter the reaction system at a tangential velocity component. This structure expands the feed point from a single top position to an axially multi-level distribution, while angle control prevents the material from directly impacting the inner wall of the container.

[0036] The above-described scheme achieves multi-directional injection of materials at different heights within the reactor by incorporating an internal feed pipe 5 that runs through multiple units within a modular cylindrical body, combined with a finger-shaped tube 51 structure with a specific inclination angle. Compared to a single feed inlet design, this structure reduces localized material accumulation and improves the uniformity of comonomer distribution in the solution.

[0037] Through the above technical solution, this application effectively solves the problem of local viscosity abrupt changes caused by uneven material distribution during high-temperature solution polymerization, and reduces the probability of polymer adhesion to the inner wall of the container. The multi-level distributed inclined finger tube 51 structure enhances the radial diffusion capability of the material, avoids the axial laminar flow phenomenon caused by traditional vertical feeding, and enables the comonomer to be quickly and uniformly dispersed in the reaction system.

[0038] See Figure 4 - Figure 5 The feeding system also includes an annular feeder, which is located at the bottom of the container and includes an annular tube 61. At least two sets of discharge holes are evenly distributed circumferentially above the tube wall of the annular tube 61. Each set of discharge holes includes at least two through holes, and the axes of the through holes in the same set intersect to form an included angle α.

[0039] It should be noted that: the annular pipe 61 refers to a closed pipe structure arranged circumferentially around the bottom of the container, made of stainless steel or corrosion-resistant alloy material, used to carry and distribute liquid materials; The through holes in the same group are on the same radial section of the annular tube 61, including an inner hole 62 and an outer hole 63. The inner hole 62 faces the center of the tube body and is close to the stirring shaft 21. The outer hole 63 is located away from the stirring shaft 21. The axes of the inner hole 62 and the outer hole 63 in the same group intersect to form an included angle α. The included angle α ranges from 10° to 90°. Preferably, this embodiment uses an included angle of 90°.

[0040] The annular distributor carries liquid material through an annular tube 61. Under pressure, the material is sprayed outward from two circular discharge holes. The discharge holes above the distributor tube cause the material to spray upward in an umbrella shape, forming a convective circulation with the bottom radial flow agitator. The umbrella-shaped dispersed material is forced against the tank wall by the radial flow blades 22 during its ascent, and then evenly distributed throughout the tank by the circulation action of the upper axial flow blades 23, solving the problem of sedimentation and agglomeration that is easily caused by traditional bottom feeding.

[0041] When the umbrella-shaped dispersed material flows through the spirally rising inner coil 3, a complex flow field of spiral scouring and radial disturbance is formed on the surface of the inner coil 3: the bottom radial flow blades 22 push the material upward along the vessel wall, generating a tangential velocity component with the outer curved surface of the spiral coil, which reduces the thickness of the attached boundary layer compared to a straight tube, thus improving the heat transfer coefficient of the inner coil 3. At the same time, the staggered jets at a 90° angle reduce the retention of material in the gaps of the inner coil 3, avoiding the risk of wall adhesion caused by local overheating.

[0042] The inner wall of module unit 11, the outer wall of inner coil 3, and the surface of the agitator are all mechanically polished to make the surface roughness Ra≤0.2μm.

[0043] It should be noted that mechanical polishing refers to the finishing process of a metal surface using a rotating polishing wheel and polishing paste. Specifically, it can be achieved using silicon carbide abrasive with a wool polishing pad, which reduces surface adhesion by removing microscopic protrusions. A surface roughness Ra ≤ 0.2 μm means that the arithmetic mean deviation of the surface profile does not exceed 0.2 micrometers. This can be detected using a laser interferometer, and the surface finish can be ensured to reach the set threshold by controlling the polishing process parameters.

[0044] During the solution polymerization of polyolefins, when the inner wall of module unit 11 comes into contact with high-viscosity materials, the mechanically polished surface forms a smooth contact surface, reducing the physical adsorption between polymer molecular chains and the metal surface. The smooth surface of the outer wall of the inner coil 3 reduces the amount of viscous material retained on the heat dissipation element, while the polished surface of the agitator weakens the shear adhesion effect of the polymer on the surface of the agitator element. The synergistic effect of the polished components ensures that the material maintains a continuous flow state during the reaction. This avoids the decrease in heat transfer efficiency and the abnormal increase in stirring resistance caused by material agglomeration, ensuring the temperature uniformity and material flowability of the reaction system, while reducing the difficulty of equipment cleaning and the frequency of downtime maintenance.

[0045] Each inner coil 3 is independently equipped with a cooling medium inlet pipe 31 and an outlet pipe 32. The walls of the inlet pipe 31 and the outlet pipe 32 do not interfere with the stirring device. The inner coil 3 extends in a continuous spiral shape and surrounds the stirring shaft 21 and the stirring paddle. The spiral inner coil 3, together with the three-layer stirring paddle, forms a composite flow field of spiral guidance and forced stirring. This allows high-viscosity materials to form a dynamically renewed flow boundary layer on the surface of the inner coil 3. Compared with straight pipes, this is beneficial to improving the heat transfer coefficient by more than 100%, solving the problem of low heat transfer efficiency of high-viscosity systems. At the same time, the spatial spiral path of the spiral inner coil 3 can cut the macroscopic flow field generated by stirring, forming local turbulent vortices. This, together with the umbrella-shaped dispersion feed of the bottom annular distributor and the turbulence of the finger-shaped tubes 51 inserted on the side, breaks the material agglomeration phenomenon, reduces the standard deviation of the concentration distribution of the reaction system, and improves the uniformity of the polymerization reaction.

[0046] The container also includes end caps 12 connected to the upper and lower ends of the cylinder. The heat dissipation system also includes a spiral half-pipe jacket 7 fitted to the outer wall of the end cap 12. The spiral half-pipe jacket 7 and each vertical half-pipe jacket 4 work together to achieve heat conduction.

[0047] Each module unit 11 is equipped with a rinsing device at the top, including an annular rinsing pipe 81. The bottom of the annular rinsing pipe 81 is provided with rinsing holes 82 along the circumferential direction. The axis of the rinsing holes 82 is at an angle to the vertical direction to ensure that the rinsing solvent can be effectively sprayed and covered to cover the inner wall of the module unit 11 below and the surface of the inner coil 3.

[0048] It should be noted that the annular flushing pipe 81 is fixed to the inner wall of the cylinder by angle steel support; The rinsing solvent is a hot melt agent, which is released through the rinsing hole 82 of the annular rinsing pipe 81 during the reaction. This hot melt agent does not participate in the polymerization reaction and is separated from the reaction product through subsequent processes.

[0049] The inclined flushing holes 82 at the bottom of the annular flushing pipe 81, circumferentially oriented, form an annular spray band. Combined with the spirally rising inner coil 3 structure, this creates a spiraling downward scouring flow field between the hot solvent and the outer wall of the inner coil 3 and the inner wall of the container. The flushing holes 82 are evenly arranged circumferentially along the annular flushing pipe 81, forming two circular tracks with different diameters. One circular track is located inside the other, with the flushing holes 82 of the inner circular track facing the stirring shaft 21, and the flushing holes 82 of the outer circular track facing the inner wall of the container.

[0050] The angle between the axis of the rinsing hole 82 and the vertical direction is in the range of 10° to 60°, so that the spray range can cover the inner wall of the lower module unit 11 and the surface of the inner coil 3. Combined with the low surface energy characteristics of the inner wall polishing treatment, the wall-adhering material is dislodged by the combination of solvent dissolution and flow shearing, further reducing the amount of residue and improving efficiency compared with traditional top spray cleaning.

[0051] Since each module unit 11 is independently equipped with an annular flushing pipe 81, when the volume of the container is adjusted by adding or removing module units 11, the flushing system can be expanded or reduced synchronously to ensure that the flushing power per unit volume remains stable, avoid insufficient cleaning in some areas due to increased production capacity, and solve the problem of cleaning dead corners after the capacity expansion of traditional integral reactors.

[0052] During the preparation process, the radial flow blades 22 of the stirring device throw the material toward the vessel wall. At the same time, the spiral structure of the inner coil 3 and the inclined spray of the flushing hole 82 form a spiral flushing path, causing the solvent to form a turbulent vortex in the gap of the inner coil 3, clearing the dead corners that are difficult to reach by the traditional straight pipe structure. In conjunction with the flow disturbance element of the finger tube 51, the boundary layer is destroyed, further reducing material deposition.

[0053] Example 2: See Figure 7 The pitch of the spiral structure of the inner coil 3 is greater than its outer diameter, so that the upper and lower tubes in the same radial section form a spacer channel 33 for fluid flow. The finger tubes 51 are arranged in a one-to-one correspondence with the spacer channel 33, and the finger tubes 51 are located on the side of the spacer channel 33 near the inner wall of the cylinder.

[0054] It should be noted that both the stirring shaft 21 and the stirring paddle are located within the cylindrical channel formed by the spiral structure, and the cylindrical channel can exchange with the water outside through the spacer channel 33.

[0055] A large amount of heat is generated during the polymerization reaction. The outer wall of the inner coil 3 is in contact with the solution and heat exchange is achieved through the cooling medium flowing inside it. The spacer channel 33 causes the fluid to form a spiral upward flow on the surface of the inner coil 3, which generates vortex superposition with the finger-shaped baffle rods on the inner wall of the module unit 11. This helps to reduce the boundary layer thickness and thus enhance the mass transfer efficiency between low viscosity solvent and high viscosity melt.

[0056] The inner feed pipe 5 releases a portion of the material into the container through the finger tubes 51. Since the inner feed pipe 5 and the finger tubes 51 are located between the inner coil 3 and the cylinder, and the finger tubes 51 are spaced apart from each of the interval channels 33, the material released by the finger tubes 51 can flow toward the interval channels 33. During the reaction, the rotation of the stirring paddle causes the solvent to diffuse outward from the inside of the channel formed by the spiral structure of the inner coil 3. The diffused material is released outward from the interval channels 33 to each finger tube 51, realizing the collision between the centrifugal material released from the annular channel and the new material sprayed by the finger tubes 51, forming a local high turbulence zone, which further reduces the average particle size of the liquid agglomerate and improves the mass transfer coefficient. At the same time, the radial vortex generated by the collision can penetrate into the interval channels 33 of the inner coil 3, allowing the material to pass through the inner side of the spiral structure successively; impact, fold back and remix and form a circulation path, shortening the mixing time between the reaction solvent and the newly injected material.

[0057] The above scheme reduces the radial concentration standard deviation through turbulent diffusion, avoiding the formation of byproducts caused by local overreaction. The finger tube 51, through its extension on the side of the inner feed tube 5, can achieve turbulence and cutting of materials at different heights. Combined with the turbulence generated at the end of the finger tube 51, it further improves the radial and axial distribution uniformity of the material and reduces the concentration gradient.

[0058] Example 3: See Figure 8 The outer wall of the stirring shaft 21 is provided with an axially extending guide groove. The axial flow blades 23 of the same layer are connected to the same collar 91. The collar 91 is sleeved on the stirring shaft 21, and its inner side is provided with a protrusion that slides with the guide groove. The collar 91 can slide along the stirring shaft 21 axially and rotate synchronously with it. The stirring shaft 21 is also provided with: a retaining ring 92, which is used to limit the axial displacement range of the collar 91; an elastic reset member 93, which is provided between the collar 91 and the retaining ring 92 and has an axial extension and retraction function; and a buoyancy drive member 94, which is connected to the upper outer side of the collar 91 and is configured to drive the collar 91 to move down along the stirring shaft 21 and compress the elastic reset member 93 under the action of the flushing solvent.

[0059] It should be noted that: each collar 91 is provided with a retaining ring 92 above and below it, and the collar 91 is connected to at least one of the retaining rings 92 above and below it by an elastic reset member 93; The elastic reset component 93 includes, but is not limited to, springs and elastic bellows; The buoyancy drive component 94 is a circular plate located between the axial flow blade 23 and the annular flushing pipe 81. The hot solution released from the flushing hole 82 can contact the upper surface of the circular plate.

[0060] The buoyancy plate generates downward impact force through the hot melt sprayed by the annular flushing pipe 81, driving the axial flow blades 23 downward. This causes the blade tips to swirl and impact different heights on the spiral inner side of the inner coil 3, solving the problem of traditional fixed blades only cleaning a single height and leaving residue on the upper part of the inner coil 3. It also avoids the possibility that residue on the outer wall of the inner coil 3, far from the axial flow blades 23, is difficult to peel off due to insufficient impact force. This increases the cleaning range of the outer wall of the inner coil 3, reduces the possibility of reduced heat transfer efficiency of the inner coil 3 for the polymerization reaction due to residue, improves the stability of the device in the preparation of polyolefins, and reduces the difficulty of disassembling and cleaning the inner coil 3. The above solution can precisely control the impact force by adjusting the flushing flow rate of the flushing pipe, thereby adjusting the height position of each axial flow blade 23 to achieve targeted flushing of areas with high residue.

[0061] After the multi-layer axial flow blades 23 move down synchronously, they form a stepped axial flow path at different heights. Combined with the circumferential diffusion of the bottom radial flow blades 22, the radial and axial velocity gradients of the material are reduced compared to traditional structures, thus avoiding material degradation caused by excessive local shearing.

[0062] During the downward movement of the collar 91, the axial flow blades 23 rapidly deliver the hot melt agent to the spacer channels 33 of each layer of the inner coil 3 through the pumping action generated by the rotation. Compared with the traditional method of relying on the axial circulation of materials in the container to reach the spacer channels 33 of each layer, the above scheme moves the fluid impact generated at a fixed height position to each layer. Combined with the hot melt agent to peel off the attached substances, a combination of physical impact and chemical degradation peeling is achieved at different height positions of the inner coil 3, further improving the peeling and cleaning effect of the hot melt agent on the inner coil 3 and the inner wall of the cylinder.

[0063] When the axial flow blade 23 moves downward, its lower surface comes into contact with the hot melt distributed in the container. At the same time, the rotation of the axial flow blade 23 promotes axial fluid circulation, causing the lower surface of the axial flow blade 23 to form a liquid impact with the axially circulating hot melt, achieving triple peeling of mechanical shearing, chemical dissolution and fluid impact, thus improving the cleanliness of the blade surface.

[0064] The counter-current flow field simultaneously drives the hot melt to diffuse to the bottom, which, in conjunction with the radial projection of the radial flow blade 22, improves the utilization rate of the hot melt, reduces the amount of hot melt used, and lowers the cleaning cost.

[0065] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A modular reaction apparatus for the solution polymerization of polyolefins, characterized in that, The application relates to a container, which comprises a cylinder formed by vertically stacking a plurality of module units (11), a stirring device configured to mix materials in the container, a heat removal system comprising an inner coil (3) arranged in each module unit (11) for heat conduction of the cylinder by circulating cooling medium, and a feeding system comprising an inner feeding pipe (5) arranged in each module unit (11) for releasing materials into the container. The module units (11) are detachably connected through flanges, and the total height and volume of the container can be adjusted by increasing or decreasing the number of the module units (11). The stirring device comprises a stirring shaft (21) extending into the container from the top, and at least three layers of stirring paddles are fixedly connected to the stirring shaft (21), wherein the bottom layer is a radial flow paddle (22) for radially diffusing materials, and the remaining layers are axial flow paddles (23) for axially diffusing materials. The heat removal system further comprises a vertical half-pipe jacket (4) arranged outside each module unit (11), each vertical half-pipe jacket (4) is independent of each other and connected to the same cooling system for heat dissipation of the outer wall of the cylinder by circulating cooling medium. There is a gap between the inner wall of the cylinder and the outer edge of the inner coil (3), the inner feeding pipe (5) is vertically inserted into the gap, and the side of the inner feeding pipe (5) is axially spaced apart from the finger-shaped pipe (51), the finger-shaped pipe (51) is connected to the inner feeding pipe (5), and the end of the finger-shaped pipe (51) is arranged below the inner wall of the cylinder.

2. A modular reaction apparatus for solution polymerization of polyolefins according to claim 1, characterized in that: The feeding system further comprises a ring distributor arranged at the bottom of the container, which comprises a ring pipe (61), and at least two groups of discharge holes are uniformly distributed on the pipe wall of the ring pipe (61) in the circumferential direction, each group of the discharge holes comprises at least two through holes, and the axes of the through holes intersect to form an included angle alpha.

3. A modular reaction apparatus for solution polymerization of polyolefins according to claim 1, characterized in that: The inner wall of the module unit (11), the outer wall of the inner coil (3) and the surface of the stirring paddle are all subjected to mechanical polishing treatment, so that the surface roughness Ra is less than or equal to 0.2 microns.

4. A modular reaction apparatus for solution polymerization of polyolefins according to claim 1, characterized in that: Each group of the inner coil (3) is independently provided with a cooling medium inlet pipe (31) and an outlet pipe (32), and the pipe wall of the inlet pipe (31) and the outlet pipe (32) does not interfere with the stirring device.

5. A modular reaction apparatus for solution polymerization of polyolefins according to claim 1, characterized in that: The container further comprises a head (12) connected to the upper and lower ends of the cylinder, and the heat removal system further comprises a spiral half-pipe jacket (7) arranged on the outer wall of the head (12), and the spiral half-pipe jacket (7) cooperates with each vertical half-pipe jacket (4) to realize heat conduction.

6. A modular reaction apparatus for solution polymerization of polyolefins according to claim 1, characterized in that: Each module unit (11) is provided with a flushing device at the top, which comprises a ring flushing pipe (81), and a flushing hole (82) is formed in the pipe wall of the ring flushing pipe (81) in the circumferential direction, and the axis of the flushing hole (82) has an included angle with the vertical direction, so that the flushing solvent can effectively spray and cover the inner wall of the module unit (11) and the surface of the inner coil (3) below.

7. A modular reaction apparatus for solution polymerization of polyolefins according to claim 1, characterized in that: ​ 8. A modular reaction apparatus for solution polymerization of polyolefins according to claim 1, characterized in that: ​ 9. A modular reaction apparatus for solution polymerization of polyolefins according to claim 4, characterized in that: ​ 10. A modular reaction apparatus for solution polymerization of polyolefins according to claim 1, characterized in that: ​

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