Ultrahigh-purity polyethylene slurry method production system

Abstract

The utility model relates to an ultra-pure polyethylene slurry method production system which comprises a reaction kettle provided with a slurry discharge port; the flash tank is connected with the slurry discharge hole of the reaction kettle, and a gas circulating pipeline is arranged at the top of the flash tank and is used for circulating flashed gas components to the reaction kettle; the rotary drum filtering unit is connected with a discharge hole of the flash tank and is used for sequentially filtering, washing and drying the flashed slurry, a filtrate outlet of the rotary drum filtering unit is connected with a solvent collecting tank, and the solvent collecting tank is communicated with the reaction kettle through a pipeline and is used for circulating a solvent to the reaction kettle. Compared with the prior art, the system has the advantages that the reaction kettle, the flash tank and the rotary drum filtering unit are efficiently connected, solvent and unreacted gas raw materials are recycled, a closed-loop material circulation system is formed, and waste and emission of the raw materials are reduced. According to the drum filter unit, the traditional dispersed procedures of filtering, washing and drying are integrated into an integrated process, so that the number of equipment and the occupied area are greatly reduced, and the operation and maintenance cost is reduced.

Description

Technical Field

[0001] This utility model relates to the field of ultra-high purity polyethylene preparation technology, specifically to an ultra-high purity polyethylene slurry production system. Background Technology

[0002] Polyolefins, as a core raw material in the field of polymer materials, are widely used in manufacturing sectors such as injection molding, film preparation, and pipe production. Among them, high-end polyolefins, represented by ultra-clean high-purity polyethylene, are high-tech, high-performance, and high-market-value polyolefin products, used in various high-value fields, including the medical field, new energy battery separator materials, and high-end filter materials. For example, ultra-high-purity polyethylene has important applications in semiconductor packaging, medical implant materials, and high-end optical devices, where its purity and impurity content must meet stringent standards.

[0003] The slurry polymerization process is currently a mature technology for producing polyolefins. Specifically, it involves dispersing aliphatic hydrocarbon inert solvents and monomers in a solvent, and then generating a polymer under the action of a catalyst. The polymer particles are suspended in the solvent, and the polyolefins synthesized by the slurry polymerization process precipitate out as fine dispersions, giving the entire polymerization system a slurry-like consistency, hence the name slurry polymerization. This process has become the mainstream production technology due to its advantages such as simple design, mild operating conditions, easy temperature control, uniform mixing, high monomer conversion rate, and relatively easy handling.

[0004] In slurry synthesis processes, the polymer slurry (containing the target product, solvent, oligomers, residual catalyst, and other impurities) after reaction needs to be separated to obtain the final product. Currently, most processes use centrifuges to remove some of the solvent, followed by nitrogen-based staged drying to remove and recover the remaining solvent, such as in the Celanese slurry process for producing ultra-high molecular weight polyethylene. However, centrifuges have high energy consumption, low capacity, and high failure rates, and nitrogen recovery is costly, severely impacting the technical and economic indicators of slurry process production equipment. To obtain high-purity polymer products, steps such as washing, filtration, and drying are usually required to remove impurities. However, to achieve these steps, multiple process units such as washing kettles / tanks, vacuum centrifuges, and dryers / drying kettles need to be used in combination. These units typically require auxiliary equipment such as transfer pumps and fans, along with their associated pipelines, fittings, and valves. The process flow is long, with numerous redundant operations, prone to solvent leaks, and poses significant safety hazards. In addition, these devices are large in size, occupy a large area, and consume a lot of energy. The more devices used, the greater the risk of device failure. It is difficult to guarantee the long-term continuous and stable operation of the process, and process improvement is still required. Utility Model Content

[0005] The purpose of this invention is to provide an ultra-high purity polyethylene slurry production system to solve the above-mentioned problems.

[0006] The objective of this utility model is achieved through the following technical solution:

[0007] A slurry production system for ultra-high purity polyethylene includes:

[0008] The reactor is equipped with a slurry discharge port;

[0009] A flash tank is connected to the slurry outlet of the reactor, and a gas circulation pipeline is provided on its top to circulate the flashed gas components back to the reactor.

[0010] The rotary drum filtration unit is connected to the outlet of the flash tank and is used to sequentially filter, wash and dry the flash-evaporated slurry. Its filtrate outlet is connected to a solvent collection tank, which is connected to the reaction vessel through a pipeline to circulate the solvent to the reaction vessel.

[0011] As a preferred technical solution of this utility model, the reaction vessel is a stirred reactor with a cooling jacket, preferably an inner jacket.

[0012] The reactor may be configured as one or more, and the multiple reactors may be configured in parallel or in series.

[0013] As a preferred technical solution of this utility model, a compressor is provided on the gas circulation pipeline of the flash tank.

[0014] As a preferred technical solution, a slurry shear pump is provided on the conveying pipeline between the reactor and the flash tank;

[0015] And / or, a dilution tank is also provided between the reactor and the flash tank, and the gas phase outlet of the dilution tank is connected to the reactor through a gas phase balance pipeline.

[0016] As a preferred technical solution, the raw material inlet of the reactor is connected to the raw material purification unit and the catalyst preparation unit respectively;

[0017] The raw material purification unit includes a packed adsorption tower;

[0018] The catalyst preparation unit includes a catalyst tank.

[0019] As a preferred technical solution, the drum filter unit includes a housing, a drum rotatably disposed within the housing, a plurality of isolation sealing elements spaced apart along the circumference of the housing, a plurality of partition chambers disposed on the surface of the drum, and a flow pipe communicating with the partition chambers.

[0020] Along the rotation direction of the drum, the isolation seal sequentially divides the annular cavity between the housing and the drum into an independently sealed filtration process section, washing process section, drying process section, and unloading process section.

[0021] As a preferred technical solution, the filtration process section is provided with a slurry inlet, which is connected to the flash tank through a pipeline;

[0022] The washing process section is equipped with a washing liquid inlet, which is connected to a washing liquid storage tank via a pipeline.

[0023] The drying process section is equipped with a drying gas inlet, which is connected to a drying gas storage tank via a pipeline.

[0024] As a preferred technical solution, ultrapure water can be used as the washing liquid and hot nitrogen can be used as the drying gas.

[0025] As a preferred technical solution, the unloading process section is equipped with a scraper mechanism and a flushing nozzle; the unloading process section unloads material through gas backflushing and the scraper mechanism, and regenerates the filter cloth through the flushing nozzle.

[0026] As a preferred technical solution, the isolation seal is a pneumatic isolation seal, including an isolation plate made of chemically resistant plastic, a filter plate on the surface of the drum, and a support mesh and filter cloth laid sequentially on the filter plate.

[0027] As a preferred technical solution, a flow passage is provided at the bottom of the partition chamber, and a control head is provided inside the drum. One end of the flow passage is connected to the flow passage at the bottom of the corresponding partition chamber, and the other end is connected to the control head. The control head discharges the filtrate from different process sections independently.

[0028] Compared with the prior art, the present invention has the following superior effects:

[0029] This invention achieves highly integrated and continuous production processes. The system, centered on a rotary drum filter unit, integrates the traditionally dispersed "filtration-washing-drying" processes into a single integrated flow, significantly reducing the number of equipment and floor space required, and lowering construction and maintenance costs. The reactor, flash tank, and rotary drum filter unit are efficiently connected via a circulation pipeline. The solvent is recycled through a collection tank, and flash gases (such as unreacted ethylene) are returned to the reactor via a compressor to participate in the reaction again, forming a closed-loop material circulation system that significantly reduces raw material waste and emissions. Simultaneously, the reactor can flexibly adopt multi-stage series or parallel structures, combined with dilution tanks and shear pumps to optimize slurry delivery, adapting to different production scales and complex operating conditions, ensuring continuous and stable system operation, and simultaneously improving production efficiency and economic benefits.

[0030] This novel system ensures ultra-high product purity through multiple purification processes and efficient treatment. The raw material purification unit (such as a packed adsorption tower) deeply removes impurities like water and carbon monoxide from ethylene, controlling purity at the source. The drum filtration unit employs ultrapure water washing technology to effectively dissolve and remove metal ions from the polymer. Combined with hot nitrogen pressurized drying, secondary contamination is avoided, ensuring extremely low metal content in the polyethylene product. Furthermore, solvent recycling, unreacted gas recovery, and the zoned sealed design of the drum filtration unit significantly reduce solvent consumption, gas emissions, and energy waste, achieving low-carbon production that is both economically efficient and environmentally friendly.

[0031] In this novel rotary drum filter unit, the isolation seal is made of chemically resistant PE / PEEK material, achieving strict sealing between process sections without hindering drum rotation. The filter cloth backflushing and regeneration technology, along with the scraper-gas combined unloading mechanism, ensures efficient filter cake removal and continuous filter cloth cleaning, extending service life. Simultaneously, automated control enables full-cycle automated operation, reducing manual intervention, improving process stability and operational safety, and meeting the stringent requirements of large-scale continuous production of ultra-high purity polyethylene. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the production system structure of this utility model;

[0033] Figure 2 This is a schematic diagram of the production system structure of the two series-connected reactors of this utility model;

[0034] Figure 3 This is a schematic diagram of the structure of the rotary drum filter unit of this utility model;

[0035] In the diagram: 100-Drum filtration unit; 200-Reaction vessel; 300-Flash tank; 400-Solvent collection tank; 500-Compressor; 600-Catalyst preparation unit; 700-Raw material purification unit; 1-Shell; 2-Drum; 3-Isolation seal; 4-Quarter; 5-Flow pipe; 6-Scraper mechanism; 7-Rinsing nozzle; 8-Slurry inlet; 9-Washing liquid inlet; 10-Drying gas inlet; 11-Washing liquid storage tank; 12-Drying gas storage tank; 13-Flow hole. Detailed Implementation

[0036] The present invention will now be described in detail. Any aspects not described in detail are technical solutions already disclosed in the field.

[0037] Reference Figure 1This invention provides a slurry production system for ultra-high purity polyethylene. The system includes a reactor 200, with the slurry outlet of the reactor 200 connected to a flash tank 300. The outlet of the flash tank 300 is connected to a rotary drum filter unit 100. The rotary drum filter unit 100 serves as a purification unit, performing a one-stop purification process of "filtration-washing-drying" on the slurry after flash evaporation to remove gas components, achieving continuous and stable production of ultra-high purity polyethylene products. Simultaneously, the filtered filtrate is collected in a solvent collection tank 400 and returned to the reactor 200 as a circulating solvent for reuse. The top of the flash tank 300 circulates the flashed gas components (mainly unreacted ethylene gas raw material) back to the reactor 200 through a gas circulation pipeline to participate in the polymerization reaction, greatly improving the system's production efficiency and benefits. This system has a simple structure. By using a rotary drum filter unit 100 as the purification unit and recycling various materials, it not only reduces the number of process equipment, saves production land, and lowers economic costs, but also effectively shortens the process operation flow, greatly improves work efficiency, has low energy consumption, and can achieve low-carbon production.

[0038] As a preferred embodiment, the reactor is a stirred tank reactor, which can preferably be a plate stirred tank reactor, and is equipped with a cooling jacket. Preferably, the cooling jacket is an inner jacket.

[0039] In a preferred embodiment, one or more reactors can be provided, for example, two, three, or more reactors can be connected in parallel or in series to meet more complex production conditions. Figure 2 A schematic diagram of two reactors connected in series is shown.

[0040] In a preferred embodiment, the flash tank 300 is connected to the raw material feeding pipeline via a feed pipeline equipped with a compressor 500, so that most of the flashed gas is returned to the reactor 100 for recycling of unreacted ethylene gas raw material.

[0041] In a preferred embodiment, the reactor 200 is connected to the flash tank 300 via a delivery pipeline equipped with a slurry shear pump. In a further preferred embodiment, a dilution tank (not shown in the figure) can also be installed between the reactor 100 and the flash tank 300 to separate the gas in the slurry, thereby avoiding long-distance gas-liquid two-phase transportation. The separated gas is returned to the reactor through a gas phase balance pipeline.

[0042] In a preferred embodiment, the raw material inlet of the reactor 200 is connected to the raw material purification unit 700 and the catalyst preparation unit 600 via a pipeline. Further, the raw material purification unit 700 includes a purification tower (e.g., a packed adsorption tower). After the raw materials such as ethylene are processed by the raw material purification unit 700, impurities such as water, carbon monoxide, and oxygen are removed to achieve high purity standards before entering the reactor to participate in the polymerization reaction. The slurry catalyst (e.g., TiCl4 and triethylaluminum) is prepared on demand in the catalyst preparation unit 600 (catalyst tank) and then sent to the reactor. The reactor is also replenished with fresh solvent (e.g., hexane) at any time through a feeding pipeline. This system realizes large-scale continuous production.

[0043] In a preferred embodiment, the drum filter unit 100 employs a pressurized drum filter, such as... Figure 3 As shown, the pressurized rotary drum filter includes a housing 1, a rotary drum 2, multiple isolation seals 3, multiple compartments 4, filter components, and multiple flow pipes 5. The rotary drum 2 is rotatably mounted inside the housing 1 around its axis, forming an annular chamber between the rotary drum 2 and the housing 1. Multiple isolation seals 3 are spaced apart along the circumference of the housing 1 on its inner wall, dividing the annular chamber into multiple independently sealed compartments. These compartments are sequentially divided along the rotation direction of the rotary drum 2 into: a filtration section A, a washing section B, a drying section C, and a discharge section D.

[0044] The isolation seal 3 is configured to contact the drum 2 and divide the annular chamber into multiple chambers, with the isolation seal 3 sealing each chamber relative to the others. In one embodiment, the long side of the isolation seal 3 on the side contacting the drum 2 extends axially along the housing 1.

[0045] In practical design, the isolation seal 3 is configured to contact the drum 2 with a relatively suitable pressure to seal adjacent chambers together without affecting the normal rotation of the drum 2 during operation. The isolation plate of the isolation seal 3 adheres tightly to the drum surface under air pressure, separating the two process sections into independent areas that do not interfere with each other or allow material to flow between them. The isolation plate is a long-cycle wear component, made of high-grade chemically resistant plastics such as PE and PEEK.

[0046] Multiple compartments 4 are arranged on the surface of the drum 2 to hold the material to be processed; filter components are set at the bottom of each compartment 4; multiple flow pipes 5 pass through the inner cavity of the drum 2 and are connected to the corresponding compartments 4.

[0047] The filtration process section A is equipped with a slurry inlet 8, which is connected to the flash tank 300 via a conveying pipeline. The washing process section B has a washing liquid inlet 9, which is connected to an external washing liquid storage tank 11 via a pipeline. The washing liquid in this system is purified water. Washing the filtered material with pure water removes most water-soluble metal ions, effectively reducing the metal content in polyethylene products.

[0048] In a preferred embodiment, the slurry inlet 8 and the washing liquid inlet 9 can be located at or near the beginning of the corresponding cavity area.

[0049] In this embodiment, the drying process section C is a pressurized drying process section. A drying gas inlet 10 is provided in the cavity of the drying process section C. The drying gas inlet 10 is connected to an external drying gas storage tank 12 through a pipeline. In the working state, the drying gas (e.g., heated nitrogen) from the external drying gas storage tank 12 is injected into the cavity of the drying process section C through the drying gas inlet 10 at a certain pressure, and the material to be dried in the cavity is dried.

[0050] Filter components, including filter plates, are fixed in the filter cake trough of the rotating drum, serving to allow liquid to pass through while trapping solids. The filter plates have filtrate channels, support mesh, and filter cloth. Depending on process requirements, the filter cloth material can be synthetic fiber or metal, etc. In practical applications, the appropriate material can be selected based on the temperature of the material to be filtered.

[0051] In addition, a flow passage 13 is provided at the bottom of the partition chamber 4. One end of the flow passage pipe 5 passes through the inner cavity of the drum 2 and connects to the flow passage 13 at the bottom of the corresponding partition chamber 4. The other end is connected to the control head located in the inner cavity of the drum 2 and fixedly connected to the drum 2. The control head is responsible for the separate discharge of different filtrates and provides backflushing gas for filter cake unloading and filter cloth rinsing. At the center of the control head is the control core integrated with the drum. The outlets of all filtrate pipes inside the drum are distributed sequentially on the surface of the control core. The annular cavity between the rotating control core and the housing where the control head is fixed is divided into several independent chambers by several isolation blocks. These chambers correspond one-to-one with the process sections on the filter housing and receive filtrate or media from the corresponding process section, thereby realizing the separate and independent discharge of different filtrates.

[0052] In this embodiment, the unloading process section D has a discharge port and a rinsing port. Unloading is carried out under normal pressure. A scraper mechanism 6 is provided at the discharge port, which, combined with gas backflushing, achieves filter cake unloading. Multiple rinsing nozzles 7 are provided at the rinsing port to clean the surface of the drum after unloading, and, combined with gas backflushing, achieve filter cloth regeneration. In the unloading zone, the filter cake is unloaded under normal pressure with the help of air, nitrogen, or steam backflushing. A spring-controlled, passively operated scraper is used to assist in unloading. At the rear lower part of the unloading zone, there is a filter cloth rinsing device for continuous or on-demand rinsing of the filter cloth.

[0053] Taking the production of ultra-high purity ultra-high molecular weight polyethylene as an example, the specific working principle of this system is as follows: raw materials, including solvent hexane and refined ethylene, are fed into reactor 200. The prepared catalyst is added to reactor 200 at the same time. The temperature inside reactor 200 is controlled at 70-85℃ and the pressure at 0.2-1.5MPa. Stirring is started to carry out the polymerization reaction. The polymer slurry generated by the reaction is discharged to flash tank 300 through the outlet to remove gas and light components. The gas and light components are discharged through the upper outlet of flash tank 300 and circulated back to reactor 200 through a pipeline with a compressor to participate in the polymerization reaction again. The slurry that has been degassed and removed of gas and light components is pressurized through the bottom outlet of flash tank 300 and sent to rotary drum filter unit 100 (rotary drum filter) for one-stop purification treatment of "filtration-washing-drying".

[0054] The specific process is as follows: the solid-liquid mixture is transported to the rotary drum filter unit 100 (the rotary drum 2 keeps rotating in the working state), and is injected into the cavity of the filtration process section A through the slurry inlet 8 at a certain pressure (e.g., 0.3-0.6 MPa). The solid-liquid mixture entering the cavity will quickly fill each compartment 4 in the cavity. Due to the pressure difference between the compartment 4 and the flow pipe 5, and between the two sides of the filter component in the compartment 4 (along the circumferential direction of the rotary drum 2), the liquid solvent in the solid-liquid mixture filling the compartment 4 is forced to pass through the filter component, enter the flow pipe through the flow hole, and be discharged from the flow pipe 5 and collected in the solvent collection tank 400, and then returned to the reactor 300 for recycling. The solid components in the solid-liquid mixture are retained on the filter component in the form of filter cake.

[0055] As the drum 2 rotates, the chamber 4 loaded with filter cake enters the cavity of the washing process section B. The washing liquid (e.g., ultrapure water) is injected into the cavity of the washing process section B through the washing liquid inlet 9 at a certain pressure (e.g., 0.3-0.6 MPa) and distributed to the chamber 4, which is located in the cavity at this time. The filter cake on the filter element in the chamber 4 is washed away, and the impurities (mainly soluble metal salts) in the filter cake are washed away. The washing liquid carrying the impurities enters the flow pipe 5 through the flow hole and is discharged and collected through the flow pipe 5. The drum 2 continues to rotate, and the chamber 4, which is loaded with the washed filter cake, enters the cavity of the drying process section C. Drying gas (e.g., hot nitrogen) is injected into the cavity of the drying process section C through the drying gas inlet 10 at a certain pressure (e.g., 0.3-0.6 MPa) and distributed to the chamber 4, which is located in the cavity at this time, to dry the filter cake on the filter element in the chamber 4. The drying gas passes through the filter cake and carries out the moisture in the filter cake, enters the flow pipe 5 through the flow hole, and is discharged from the flow pipe 5.

[0056] As drum 2 continues to rotate, chamber 4, loaded with dried filter cake, enters unloading section D. Unloading occurs under normal pressure. At the discharge port of unloading section D, the dried filter cake in chamber 4 is broken by the scraper mechanism 6, and combined with gas backflushing, the filter cake is unloaded, resulting in polyethylene dry powder that slides out of chamber 4 and is collected. As drum 2 continues to rotate, chamber 4 is rotated to the rinsing port, where multiple rinsing nozzles 7 are installed to clean the surface of the drum after unloading. Combined with gas backflushing, the filter cloth is regenerated. It is then rotated to the cavity area of ​​filtration section A for the next "filtration-washing-drying" cycle. This system is a continuous production process, enabling the large-scale continuous production of ultra-clean, high-purity polyethylene.

[0057] The above description of the embodiments is provided to enable those skilled in the art to understand and use the utility model. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present utility model is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present utility model without departing from its scope should be within the protection scope of the present utility model.

Claims

1. A slurry production system for ultra-high purity polyethylene, characterized in that, include: The reactor (200) is equipped with a slurry discharge port; A flash tank (300) is connected to the slurry outlet of the reactor (200), and a gas circulation pipeline is provided on its top to circulate the flashed gas components to the reactor (200). The rotary drum filter unit (100) is connected to the outlet of the flash tank (300) and is used to filter, wash and dry the flash slurry in sequence. Its filtrate outlet is connected to the solvent collection tank (400), which is connected to the reaction vessel (200) through a pipeline to circulate the solvent to the reaction vessel (200).

2. The ultra-high purity polyethylene slurry production system according to claim 1, characterized in that, The reactor (200) is a stirred tank reactor with a cooling jacket; The reactor (200) is configured as one or more, and the multiple reactors (200) are configured in parallel or in series.

3. The ultra-high purity polyethylene slurry production system according to claim 1, characterized in that, The flash tank (300) is equipped with a compressor (500) on its gas circulation pipeline.

4. The ultra-high purity polyethylene slurry production system according to claim 1, characterized in that, A slurry shear pump is installed on the conveying pipeline between the reactor (200) and the flash tank (300); And / or, a dilution tank is provided between the reactor (200) and the flash tank (300), and the gas phase outlet of the dilution tank is connected to the reactor (200) through a gas phase balance pipeline.

5. The ultra-high purity polyethylene slurry production system according to claim 1, characterized in that, The raw material inlet of the reactor (200) is connected to the raw material purification unit (700) and the catalyst preparation unit (600) respectively; The raw material purification unit (700) includes a packed adsorption tower; The catalyst preparation unit (600) includes a catalyst container.

6. The ultra-high purity polyethylene slurry production system according to claim 1, characterized in that, The rotary drum filter unit (100) includes a housing (1), a rotary drum (2) rotatably disposed in the housing (1), a plurality of isolation seals (3) spaced apart along the circumference of the housing (1), a plurality of partition chambers (4) disposed on the surface of the rotary drum (2), and a flow pipe (5) communicating with the partition chambers (4); Along the rotation direction of the drum (2), the isolation seal (3) sequentially divides the annular chamber between the housing (1) and the drum (2) into an independently sealed filtration process section (A), washing process section (B), drying process section (C) and unloading process section (D).

7. The ultra-high purity polyethylene slurry production system according to claim 6, characterized in that, The filtration process section (A) is equipped with a slurry inlet (8), which is connected to the flash tank (300) through a pipeline; The washing process section (B) is equipped with a washing liquid inlet (9) and is connected to a washing liquid storage tank (11) through a pipeline; The drying process section (C) is equipped with a drying gas inlet (10), which is connected to a drying gas storage tank (12) via a pipeline.

8. The ultra-high purity polyethylene slurry production system according to claim 6, characterized in that, The unloading process section (D) is equipped with a scraper mechanism (6) and a flushing nozzle (7).

9. The ultra-high purity polyethylene slurry production system according to claim 6, characterized in that, The isolation seal (3) is a pneumatic isolation seal, including an isolation plate. The isolation plate is made of chemically resistant plastic. The surface of the drum (2) is provided with a filter plate, and a support mesh and filter cloth are laid on the filter plate in sequence.

10. The ultra-high purity polyethylene slurry production system according to claim 6, characterized in that, The bottom of the partition chamber (4) is provided with a flow passage hole (13), and the drum (2) is provided with a control head. One end of the flow passage pipe (5) is connected to the flow passage hole (13) at the bottom of the corresponding partition chamber (4), and the other end is connected to the control head. The control head discharges the media of different process sections independently.

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