An ultra-high purity polyolefin drum-type separation and purification device

Abstract

The utility model relates to a kind of ultra-high purity polyolefin rotary drum type separation and purification device, including rotary drum filtration unit, along the direction of rotation, the rotary drum filtration unit sequentially includes filtration process section, washing process section, drying process section and unloading process section, the filtration process section is injected by feed inlet pressurized polyolefin slurry;The washing process section includes multistage sectional type washing component, including alkane solvent washing section, acid liquid solvent washing section and after washing section;The drying process section is injected by import pressurized drying gas.Compared with prior art, the device realizes the continuous production of ultra-clean high-purity polyolefin product by the multistage optimization combination of washing section.

Description

Technical Field

[0001] This utility model relates to the field of ultra-high purity polyolefin technology, specifically to an ultra-high purity polyolefin rotary drum separation and purification device. Background Technology

[0002] Polyolefins, as a core raw material in the field of polymer materials, are widely used in injection molding, film manufacturing, pipe manufacturing, and other fields. Among them, high-end polyolefins, represented by ultra-clean and high-purity polyethylene, are used in high-value fields such as medical devices, new energy battery separators, and high-end filter materials due to their high technological content, excellent performance, and high market value. For example, ultra-high purity polyethylene is widely used in semiconductor packaging, medical implant materials, and high-end optical devices, and its purity and impurity content must meet stringent standards.

[0003] The slurry polymerization process is currently the mainstream and mature technology for producing polyolefins. This process involves adding monomers, comonomers, and hydrogen to an inert aliphatic hydrocarbon solvent, where polymerization occurs under the action of a catalyst. Polymer particles nucleate and grow at the active sites of the catalyst, forming solid particles suspended in the solvent, resulting in a "slurry" state for the entire system. Its advantages include simple design, mild operating conditions, easy temperature control, uniform mixing, high monomer conversion rate, and ease of handling.

[0004] In slurry processing, the slurry after reaction (containing the target polymer, solvent, oligomers, residual catalyst, co-catalyst, and other impurities) needs to be separated and purified to obtain the final product. Current processes typically use centrifuges to remove some of the solvent (e.g., Celanese's process for producing ultra-high molecular weight polyethylene), reducing the liquid content from approximately 65% ​​to below 30%, followed by nitrogen-based staged drying to remove residual solvent. However, centrifuges are energy-intensive, have a high failure rate, and offer limited solid-liquid separation, requiring further processing with a dryer, severely impacting the technical and economic efficiency of the equipment. Furthermore, to obtain a high-purity product, washing and solid-liquid separation steps are also necessary to remove impurities.

[0005] The above separation and purification process requires the combined use of multiple sets of equipment such as washing kettles, centrifuges, and dryers, as well as auxiliary equipment such as transfer pumps, fans, pipelines, fittings, and valves. This results in: (1) a lengthy and complex process flow with numerous operating steps and low efficiency; (2) prominent safety hazards, numerous equipment interfaces, and a high risk of solvent leakage; (3) a large footprint, high energy consumption, and large equipment size, leading to significant energy consumption during operation; and (4) poor operational stability, as the large number of equipment means an accumulation of failure risks, making it difficult to guarantee long-term continuous and stable operation. Therefore, the production equipment still needs continuous improvement to solve the above technical problems. Utility Model Content

[0006] The purpose of this invention is to provide an ultra-high purity polyolefin rotary drum separation and purification device to solve the above-mentioned problems.

[0007] The objective of this utility model is achieved through the following technical solution:

[0008] A rotary drum separation and purification device for ultra-high purity polyolefins includes a rotary drum filtration unit. Along the rotation direction, the rotary drum filtration unit sequentially includes a filtration process section, a washing process section, a drying process section, and a discharge process section. The filtration process section injects pressurized polyolefin slurry through the feed inlet. The washing process section includes a multi-stage segmented washing assembly, comprising an alkane solvent washing section, an acid solvent washing section, and a post-washing section. The drying process section injects pressurized drying gas through the inlet.

[0009] As a preferred technical solution, the alkane solvent washing section is connected to the alkane solvent storage unit via a pipeline; the acid solvent washing section is connected to the acid solvent storage unit via a pipeline; and the subsequent washing section is connected to the pure water storage unit via a pipeline.

[0010] As a preferred technical solution, the alkane solvent storage unit is filled with an inert alkane solvent, such as hexane or pentane; the acid solvent storage unit is filled with dilute nitric acid with a concentration of 0.1 to 0.5 wt%; and the pure water storage unit is filled with ultrapure water.

[0011] As a preferred technical solution, the drying process section is connected to the gas supply unit via pipeline.

[0012] As a preferred technical solution, the filtration process section is connected to the polyolefin slurry buffer unit via pipeline.

[0013] As a preferred technical solution, the working pressure of the filtration process section, washing process section, and drying process section is 0.1-0.8 MPa, preferably 0.3-0.5 MPa; and the working temperature is 60-70℃.

[0014] As a preferred technical solution, the rotary drum filter unit includes a housing, a rotary drum rotatably disposed within the housing, and a plurality of isolation sealing elements spaced apart along the circumference of the housing; the isolation sealing elements sequentially divide the annular cavity between the housing and the rotary drum into a plurality of independent partitioned chambers, and the rotary drum is provided with a plurality of flow pipes communicating with the partitioned chambers.

[0015] 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.

[0016] 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 media from different process sections independently and collects them into an independent recycling unit.

[0017] As a preferred technical solution, the unloading process section is equipped with a scraper mechanism and a flushing nozzle. The scraper mechanism is made of non-metallic material to avoid introducing metallic impurities.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This device achieves highly integrated and continuous production, combining the "filtration-washing-drying" process into a single integrated flow, significantly reducing the number of equipment and floor space required. Through multi-stage optimization of the washing section, it achieves deep impurity removal and purity breakthroughs in polyolefin slurry, enabling continuous production of ultra-clean, high-purity polyolefin products. In the multi-stage segmented washing process, the sequentially arranged alkane solvent section, acid solvent section, and post-washing section achieve graded and targeted removal of different types of impurities in polyolefin particles: the alkane solvent section effectively dissolves and washes away residual monomers, oligomers, oily organic impurities, and some catalyst residues; the acid solvent section efficiently complexes, dissolves, and removes metal ion impurities (such as residual metals from catalysts), significantly reducing product ash and metal content; the post-washing section removes residual acid, water-soluble metal salts, and microparticles, ensuring the final product is free of acid and alkali residues, achieving extreme product purification.

[0020] Rotary drum filtration operates under pressure, enhancing solvent penetration and washing efficiency. This ensures deep displacement and elution of impurities, facilitating the removal of impurities from within dense particles. A single rotary drum unit continuously completes all core process steps—filtration, multi-stage washing, drying, and unloading—eliminating the contamination risks and efficiency losses associated with material transfer in traditional batch operations. Furthermore, isolation seals strictly separate each process section into independent chambers, ensuring that different solvents, gases, and material flow paths do not interfere with each other, preventing cross-contamination, and enabling independent control and recovery of process media. The scraper mechanism and rinsing nozzles work together to achieve continuous, efficient, and low-residue unloading of dried ultra-high purity polyolefins, ensuring continuous, stable operation and high production capacity of the production line. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the ultra-high purity polyolefin rotary drum separation and purification device of this utility model;

[0022] In the diagram: 100-Drum filter unit; 200-Alkane solvent storage unit; 300-Acid solvent storage unit; 400-Pure water storage unit; 500-Gas supply unit; 600-Slurry buffer unit; 1-Shell; 2-Drum; 3-Isolation seal; 4-Cavity; 5-Flow pipe; 6-Scraper mechanism; 7-Flush nozzle; 8-Flow hole. Detailed Implementation

[0023] The present invention will now be described in detail. Any aspects not described in detail are technical solutions already disclosed in the field.

[0024] Reference Figure 1 This invention provides a rotary drum separation and purification device for ultra-high purity polyolefins, used for large-scale continuous production of ultra-clean high-purity polyolefin products. The rotary drum separation and purification device includes a rotary drum filtration unit 100, which includes a housing 1, a rotary drum 2 rotatably disposed within the housing 1, and multiple isolation sealing elements 3 spaced apart circumferentially along the housing 1. The isolation sealing elements 3 sequentially divide the annular chamber between the housing 1 and the rotary drum 2 into multiple independent compartments 4 as different process sections. Multiple flow pipes 5 communicating with the compartments 4 are provided inside the rotary drum 2. A flow hole 8 is opened at the bottom of each compartment 4. A control head is provided inside the rotary drum 2. One end of each flow pipe 5 is connected to the flow hole 8 at the bottom of the corresponding compartment 4, and the other end is connected to the control head. The control head independently discharges the media from different process sections, which are then collected to independent recovery units. At the center of the control head is a control core integrated with the rotary drum, and the outlets of all filtrate pipes inside the rotary drum are sequentially distributed 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 sections, thereby achieving separate and independent discharge of different filtrates.

[0025] The isolation seal 3 is a pneumatic isolation seal, including an isolation plate made of chemically resistant plastic. A filter plate is provided on the surface of the drum 2, and a support mesh and filter cloth are sequentially laid on the filter plate. The isolation seal 3 is configured to contact the drum 2 and divide the annular chamber into multiple chamber areas, sealing each chamber area 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. In actual design, the isolation seal 3 is configured to contact the drum 2 with a relatively suitable pressure to seal adjacent chamber areas without affecting the normal rotation of the drum 2 during operation. Under pneumatic pressure, the isolation plate of the isolation seal 3 adheres tightly to the drum surface, 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 PTFE and PEEK. 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.

[0026] Along the rotation direction, the drum filtration unit 100 sequentially includes a filtration process section A, a washing process section B, a drying process section C, and a discharge process section D. The filtration process section A is connected to the polyolefin slurry buffer unit 600 via pipelines, and pressurized polyolefin slurry is injected through the feed inlet. The washing process section B includes a multi-stage segmented washing assembly, comprising an alkane solvent washing section B1, an acid solvent washing section B2, and a downstream washing section B3. The alkane solvent washing section B1 is connected to the alkane solvent storage unit 200 via pipelines; the acid solvent washing section B2 is connected to the acid solvent storage unit 300 via pipelines; and the downstream washing section B3 is connected to the pure water storage unit 400 via pipelines. The alkane solvent storage unit 200 contains inert alkane solvents, such as hexane or pentane; the acid solvent storage unit 300 contains dilute nitric acid with a concentration of 0.1–0.5 wt%; and the pure water storage unit 400 contains ultrapure water. By sequentially configuring an alkane solvent section, an acid solvent section, and a post-washing section, the system can achieve graded and targeted removal of different types of impurities in polyolefin particles. Specifically: the alkane solvent section effectively dissolves and washes away residual monomers, oligomers, oily organic impurities, and some catalyst residues; the acid solvent section efficiently complexes, dissolves, and removes metal ion impurities, significantly reducing product ash and metal content; the post-washing section removes residual acid, water-soluble metal salts, and microparticles, ensuring the final product is free of acid and alkali residues and achieving extreme product purification. Drying section C is connected to a gas supply unit 500 (e.g., a nitrogen network) via pipelines to inject pressurized drying gas. During operation, external drying gas, such as compressed nitrogen, is injected into the cavity of drying section C to dry the material within. Filter components, including filter plates, are fixed in the filter cake trough of the rotating drum, serving to allow liquid flow while intercepting 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 sintered metal, etc. In practical applications, the appropriate material can be selected based on the temperature of the material to be filtered.

[0027] 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, and filter cake unloading is achieved in conjunction with gas backflushing. Multiple rinsing nozzles 7 are provided at the rinsing port to clean the surface of the drum after unloading, and filter cloth regeneration is achieved in conjunction with gas backflushing. 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. Preferably, the scraper mechanism 6 is made of non-metallic material, and a discharge spiral is provided downstream of the scraper mechanism 6 to break up the blocky filter cake for easy processing in the next step.

[0028] The operating pressure of filtration section A, washing section B, and drying section C is 0.1–0.8 MPa. Drum filtration is carried out under a certain pressure to enhance solvent penetration and washing efficiency, ensuring deep displacement and elution of impurities, which is beneficial for removing impurities from the interior of dense particles. Furthermore, the temperature of the filtration, washing, and drying sections is controlled at 60–70°C to prevent oligomer precipitation. As a preferred embodiment, drying section C can be configured as a multi-stage, segmented drying section, for example, using two drying sections, to further improve the drying effect.

[0029] Taking the slurry method for producing ultra-high purity ultra-high molecular weight polyethylene as an example, the specific working process is as follows:

[0030] The polyethylene slurry from the upstream polymerization unit (which can be first sent to the slurry buffer unit 600) is pumped to the drum filter unit 100 (drum 2 keeps rotating in the working state). The slurry is injected into the cavity of the filtration process section A at a certain pressure (about 0.3 MPa). The solid-liquid mixture slurry entering the cavity quickly fills the cavity. Due to the pressure difference between the partition chamber 4 and the flow pipe 5, and between the two sides of the filter component in the partition chamber 4 (along the circumferential direction of the drum 2), the liquid solvent in the slurry in the partition chamber 4 passes through the filter component, enters the flow pipe 5 through the flow hole 8 of the filtration process section A, and is discharged through the control head by the flow pipe 5. It is collected to an independent recovery unit and can be recycled after subsequent processing. The solid components are retained on the filter component on the surface of the drum in the form of filter cake.

[0031] As the drum 2 rotates, the drum 2 loaded with filter cake enters the cavity of the washing process section B for multi-stage graded washing: (1) In the alkane solvent washing section B1, clean hexane from the alkane solvent storage unit 200 is injected into the cavity of the alkane solvent washing section B1 at a certain pressure (about 0.3 MPa) to clean the filter cake on the filter component in the compartment 4. Residual monomers, oligomers, oils and other organic impurities that are easily soluble in hexane and some catalyst residues in the filter cake are washed off. Hexane carries these impurities through the flow hole into the flow pipe 5 and is discharged through the flow pipe 5 via the control head. It is collected to an independent recovery unit and can be recycled after subsequent processing. (2) The drum 2 continues to rotate, and the filter cake washed with hexane enters the acid solvent washing section B2. Dilute nitric acid (about 0.35 wt%) from the acid solvent storage unit 300 is injected into the cavity of the acid solvent washing section B2 at a certain pressure (about 0.3 MPa) to clean the filter cake. Dilute nitric acid has a certain oxidizing property and can complex, dissolve and remove metal ion impurities (mainly catalyst residual metals) in the polyethylene filter cake. By reacting dilute nitric acid with the residual metal elements in the ultra-high molecular weight polyethylene powder, the ash content and metal content of the product are significantly reduced. The acid solvent carrying impurities enters the flow pipe 5 through the flow hole and is discharged through the control head from the flow pipe 5. It is collected to an independent recovery unit and can be recycled after subsequent treatment. (3) Drum 2 continues to rotate. The filter cake, after being washed with acid, enters the downstream washing section B3. Ultrapure water from the pure water storage unit 400 is injected into the cavity of the downstream washing section B3 at a certain pressure (approximately 0.3 MPa) to wash the filter cake, removing residual acid, water-soluble metal salts, and small particles, ensuring that the final product is free of acid and alkali residues, and achieving extreme purification of the product. Wastewater carrying impurities enters the flow pipe 5 through the flow hole and is discharged through the control head from the flow pipe 5, and is collected to an independent recovery unit for further treatment.

[0032] The drum 2 continues to rotate, and 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 at a certain pressure (e.g., 0.1-0.3 MPa) to dry the filter cake. The drying gas passes through the filter cake and carries away the moisture in the filter cake. The gas enters the flow pipe 5 through the flow hole and is discharged from the flow pipe 5 and collected to an independent recovery unit.

[0033] Drum 2 continues to rotate, and the dried filter cake enters the unloading process section D. Unloading is carried out under normal pressure. At the discharge port of unloading process section D, the dried filter cake in the compartment 4 is broken by the agitation of the scraper mechanism 6, and the filter cake is unloaded by gas backflushing. The obtained polyethylene dry powder slides out of drum 2 and is collected. As drum 2 continues to rotate, it is rotated to the rinsing port, where multiple rinsing nozzles 7 are installed to clean the surface of the drum after unloading. The filter cloth is regenerated by gas backflushing. Then, it is rotated to the cavity area of ​​filtration process section A for the next "filtration-washing-drying" cycle. Through this device, ultra-clean, high-purity ultra-high molecular weight polyethylene (metal content less than 1 ppm, non-volatile residues less than 0.01%) can be produced on a large scale and continuously, which can meet the needs of high-end application scenarios such as semiconductor photoresist, medical filter materials, and medical implants.

[0034] 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 rotary drum separation and purification device for ultra-high purity polyolefins, comprising a rotary drum filtration unit (100), wherein, along the rotation direction, the rotary drum filtration unit (100) sequentially comprises a filtration process section (A), a washing process section (B), a drying process section (C), and a discharge process section (D), characterized in that, The filtration process section (A) injects pressurized polyolefin slurry through the feed inlet; The washing process section (B) includes a multi-stage segmented washing assembly, comprising an alkane solvent washing section (B1), an acid solvent washing section (B2), and a downstream washing section (B3). The drying process section (C) injects pressurized drying gas through the inlet.

2. The ultra-high purity polyolefin rotary drum separation and purification device according to claim 1, characterized in that, The alkane solvent washing section (B1) is connected to the alkane solvent storage unit (200) via a pipeline; The acid solvent washing section (B2) is connected to the acid solvent storage unit (300) via a pipeline; The downstream washing section (B3) is connected to the pure water storage unit (400) via pipeline.

3. The ultra-high purity polyolefin rotary drum separation and purification device according to claim 2, characterized in that, The alkane solvent storage unit (200) is filled with inert alkane solvent; The acid solvent storage unit (300) is filled with dilute nitric acid with a concentration of 0.1 to 0.5 wt%. The pure water storage unit (400) is filled with ultrapure water.

4. The ultra-high purity polyolefin rotary drum separation and purification device according to claim 1, characterized in that, The drying process section (C) is connected to the gas supply unit (500) via pipeline.

5. The ultra-high purity polyolefin rotary drum separation and purification device according to claim 1, characterized in that, The filtration process section (A) is connected to the polyolefin slurry buffer unit (600) via pipeline.

6. The ultra-high purity polyolefin rotary drum separation and purification device according to claim 1, characterized in that, The working pressure of the filtration process section (A), washing process section (B), and drying process section (C) is 0.1-0.8 MPa, and the working temperature is 60-70℃.

7. The ultra-high purity polyolefin rotary drum separation and purification device 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), and a plurality of isolation sealing elements (3) spaced apart along the circumference of the housing (1); The isolation seal (3) sequentially divides the annular cavity between the housing (1) and the drum (2) into multiple independent partition chambers (4), and the drum (2) is provided with multiple flow pipes (5) that connect the partition chambers (4).

8. The ultra-high purity polyolefin rotary drum separation and purification device according to claim 7, 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.

9. The ultra-high purity polyolefin rotary drum separation and purification device according to claim 7, characterized in that, The bottom of the partition chamber (4) is provided with a flow hole (8), and the drum (2) is provided with a control head. One end of the flow pipe (5) is connected to the flow hole (8) 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 and collects them into an independent recycling unit.

10. The ultra-high purity polyolefin rotary drum separation and purification device according to claim 1, characterized in that, The unloading process section (D) is equipped with a scraper mechanism (6) and a flushing nozzle (7).

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