Cleaning method suitable for filter screen on spinneret plate in lyocell fiber production process

Abstract

The invention discloses a cleaning method suitable for a filter screen on a spinneret plate in a lyocell fiber production process, and relates to the technical field of lyocell fiber production, the cleaning method comprises the following steps: S1, assembly disassembly; s2, soaking and cooking; s3, calcining and carbonizing; s4, performing high-pressure spraying; s5, ultrasonic cleaning; s6, washing and drying; impurities and carbides in the filter screen can be well stripped, so that the filter screen can recover to the original performance, and the filter screen has the effect of repeated use. The lyocell fiber spinneret plate filter screen cleaning device can effectively clean the lyocell fiber spinneret plate filter screen and reuse the spinneret plate filter screen, so that the consumption of the lyocell fiber production filter screen is reduced, and the lyocell fiber production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of lyocell fiber production technology, and in particular to a cleaning method for the filter screen on the spinneret in the lyocell fiber production process. Background Technology

[0002] Currently, lyocell fibers are produced using a dry-jet wet spinning method. During the spinning process, the sizing solution is transported through pipelines to a spinning metering pump. After metering, it is spun from the spinneret into an air bath, and then enters the coagulation bath to form the fibers. Because the sizing solution contains fine impurities, if the sizing solution is directly spun from the spinneret, it can cause the spinneret holes to become clogged or even damaged. Therefore, a filter assembly needs to be added to the front end of the spinneret. This filter assembly consists of multiple layers of filter screens with different mesh sizes, which can effectively filter the sizing solution, reduce the clogging of the spinneret holes by impurities in the sizing solution, and effectively extend the service life of the spinneret.

[0003] However, as the filter screen is used for a longer period, its filtration efficiency deteriorates after a certain time, failing to meet production process requirements. Therefore, the filter screen needs to be replaced to ensure production processes continue. Due to the properties of lyocell adhesive, a large amount of adhesive adheres to the surface and interior of used filter screens. Conventional cleaning methods cannot completely remove the residual adhesive. Therefore, most lyocell fiber spinneret filter screens used by manufacturers are currently single-use and are discarded as consumables after replacement.

[0004] Because spinneret filters have a limited lifespan and need to be replaced after reaching that point, as well as after prolonged production stoppages or emergency shutdowns, the consumption of filters is very high. However, since the filters are disposable and not recycled, their production costs are extremely high, ultimately contributing to the high production costs of lyocell fibers. Therefore, there is an urgent need to find a method or technology to solve the problem of the inability to reuse lyocell fiber spinneret filters.

[0005] Currently, the filter assembly in the spinneret unit of Lyocell manufacturers consists of 3-5 layers of single-layer filters with different mesh sizes. The filter assembly has a circular structure, with multiple layers of filters fixed together by filter seals on the inner and outer surfaces of the ring. Each layer of filter has a small mesh size, and after each use, the inner and outer layers of the filter are covered with cellulose-containing adhesive, which directly clogs the filter pores, making it unusable. Conventional cleaning methods cannot remove the attached cellulose, so the filter assembly in the existing spinneret unit is for single use only.

[0006] Patent publication number CN115161780A discloses a cleaning process for spinnerets in lyocell fiber spinning, belonging to the technical field of lyocell fiber production methods. The process includes the following steps: component disassembly, primary soaking, secondary soaking, primary high-pressure purging, high-pressure cleaning, ultrasonic cleaning, low-pressure cleaning, secondary high-pressure purging, and drying. This invention utilizes the combined effects of high-pressure purging, high-pressure cleaning, and ultrasonic cleaning to thoroughly clean residue from the spinneret's orifices, leaving no blind spots and effectively protecting the spinneret surface from scratches. Low-pressure cleaning and secondary high-pressure purging further remove residue adhering to the spinneret surface after high-pressure cleaning, leaving the spinneret bright and new. This ensures effective cleaning while protecting the spinneret's integrity, reducing damage during the cleaning process, and greatly guaranteeing normalized and continuous production.

[0007] However, this patent describes a cleaning method for spinnerets, which is not applicable to filter cleaning. Spinnerets have straight-through pores, while filter assemblies have a multi-layered structure with small gaps between layers that are easily blocked by adhesive. The high-pressure purging and cleaning fluids cannot penetrate these layers. The tiny gaps between layers easily accumulate adhesive, forming a sealed blockage. The high-pressure purging and cleaning fluids cannot overcome the resistance of the interlayer and can only clean the surface. More importantly, Lyocell adhesive requires temperatures above 280°C to decompose. This patent only uses medium-temperature immersion, which can only slightly soften the surface adhesive and cannot destroy the solidified adhesive in the filter pores and interlayer, ultimately rendering the filter unusable. Furthermore, its purely physical cleaning method cannot remove residual adhesive from the filter pores and sealing gaps, and cannot restore the filter's permeability. Summary of the Invention

[0008] The present invention aims to provide a cleaning method for the spinneret filter screen in the lyocell fiber production process, which effectively cleans the lyocell fiber spinneret filter screen, allows the spinneret filter screen to be reused, reduces the consumption of lyocell fiber production filter screen, and lowers the production cost of lyocell fiber.

[0009] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows: A method for cleaning the filter screen on the spinneret in the production process of lyocell fiber includes the following steps: S1. Component disassembly: Disassemble the filter assembly from the spinneret unit; S2. Soaking and boiling: Place the disassembled filter assembly in the boiling tank for boiling. After boiling, remove the cleaning basket and let it cool naturally to room temperature. Then use a scraper to clean the adhesive residue on the surface of the filter assembly. S3. Calcination and carbonization: After removing the adhesive residue from the filter screen assembly, place it in a calcination furnace and calcine for 4-8 hours. After natural cooling, remove the assembly. S4. High-pressure spraying: The calcined filter screen assembly is cleaned by high-pressure water spraying. S5. Ultrasonic cleaning: The filter assembly after high-pressure spraying is immersed in alkaline cleaning solution and acidic cleaning solution respectively under ultrasonic action at 40℃-50℃ for 30min-60min. S6. Washing and drying: Soak the ultrasonically cleaned filter assembly in clean water for 10-40 minutes, then remove it and dry it at 60℃-90℃ to complete the cleaning.

[0010] In step S2, the cooking temperature is 60℃-100℃; the cooking time is 30min-120min. In step S3, the calcination temperature is 350℃-500℃; In step S4, the high-pressure spraying pressure is 1.0MPa-1.4MPa; the spraying time is 3min-6min. In step S5, the alkaline cleaning solution is a NaOH solution with a concentration of 0.1 mol / L to 1 mol / L; In step S5, the acidic cleaning solution is a sulfuric acid solution with a concentration of 0.1 mol / L to 0.5 mol / L; In step S5, the ultrasonic frequency is 20kHz-40kHz.

[0011] The beneficial effects of this invention are: 1. In this invention, the NMMO and water in cellulose in Lyocell adhesive separate and regenerate into a gel-like substance after soaking and boiling, thus peeling off the adhesive blocks adhering to both sides of the filter assembly. This property allows for better peeling, reduces dust generation in subsequent steps, and removes approximately 30% of impurities. Calcination and carbonization oxidize and decompose the adhesive blocks inside the multi-layer filter assembly into tiny carbon particles at high temperatures. These small carbon particles have a diameter smaller than the filter pore size and can be removed in subsequent steps. Calcination and carbonization removes approximately 50% of the residue from the filter assembly. High-pressure spraying removes approximately 10% of the residue, with the cleaning time controlled at 3-6 minutes, flushing out particles adhering to the filter assembly from both the inner and outer sides. The purpose of alkaline ultrasonic cleaning is to dissolve the remaining approximately 10% of residue that can be cleaned physically in the alkaline solution, and to use ultrasound to wash away the carbides adhering to the inside and outside of the filter assembly. The purpose of acid ultrasonic cleaning is to remove the black carbides from the surface of the metal filter assembly, restoring its original color and performance. Water washing and drying removes the residual acid washing solution after acid cleaning by immersion, and then drying ensures it is dry for storage and use. The immersion time should not be too long, otherwise the metal filter assembly is prone to rust. The drying temperature should not be too low or too high; too low a temperature will result in poor drying, while too high a temperature will cause the surface to turn black again.

[0012] 2. In this invention, the purpose of soaking and cooking is to utilize the property that the NMMO and water in cellulose will separate and regenerate into a glue-like substance when the glue solution is heated from low temperature to high temperature to peel off the glue blocks attached to both sides of the filter screen assembly. This property can achieve a better peeling effect and reduce the generation of a large amount of dust in the calcination furnace during the subsequent calcination step. This step can remove the cellulose attached to the surface of the filter screen assembly, with a cleaning rate of about 30%.

[0013] The purpose of calcination is to oxidize and decompose the adhesive blocks inside the multi-layer filter assembly at high temperatures into tiny carbon particles. These small carbon particles have a diameter smaller than the pore size of the filter assembly and can be removed through subsequent cleaning steps. Calcination and carbonization can remove approximately 50% of the residue from the filter assembly.

[0014] The purpose of high-pressure spraying is to flush out the particles attached to the inside and outside of the filter screen assembly after calcination. This step can clean out about 10% of the particles from the filter screen assembly.

[0015] The purpose of acid washing, alkaline washing, and ultrasonic washing is to dissolve the remaining approximately 10% of residue that cannot be cleaned physically in the alkaline solution, and to use ultrasound to wash away the carbides adhering to the inside and outside of the filter assembly. The purpose of acid washing and ultrasonic washing is to remove the black carbides from the surface of the metal filter assembly, restoring it to its original color and performance. The order of alkaline washing followed by acid washing must not be reversed, as their purposes are inconsistent and will affect the service life of the filter assembly.

[0016] 3. Analysis of the beneficial economic benefits of this invention: Through cleaning experiments, each filter element can be reused at least once, and the annual cost of filter element consumables can be reduced from RMB 1.8827 million to RMB 941,400, saving more than 50% of the consumption of new filter elements and effectively reducing the production cost of lyocell fiber.

[0017] 4. In this invention, calcination decomposes the cellulose in the inner and outer layers of the filter (especially the inner layer, which contains carbon compounds that cannot be cleaned using conventional methods) into carbon compounds without damaging the filter's performance; the ultrasonic alkaline washing method dissolves and decomposes the large-molecule carbon compounds in the inner layer of the filter into small-molecule carbon compounds, while simultaneously using a specific ultrasonic frequency and temperature in the alkaline washing bath to improve the filter's cleaning pass rate; the ultrasonic acid washing method restores the discolored filter to its original color and performance, making it indistinguishable from a new filter.

[0018] 5. In this invention, boiling and soaking at 80℃-100℃ quickly softens the adhesive on the surface and in the crevices of the filter screen, breaking its initial adhesion to the filter screen. Secondly, high-temperature calcination at 350℃-500℃ completely decomposes the solidified adhesive in the multi-layered filter screen layers and micron-sized pores into loose carbides, solving the problem of traditional methods being unable to penetrate deep layers of adhesive buildup. Subsequently, high-pressure spraying peels off the loose surface carbides, opening channels for chemical cleaning; alkaline washing dissolves the carbide skeleton, while acid washing specifically removes the oxide layer and residual impurities from the filter screen's metal substrate. This dual chemical action achieves thorough cleaning without dead angles; finally, water washing and drying completely remove chemical residues and ensure the filter screen is dry and rust-proof, guaranteeing safe reuse. This progressive logic of "softening-decomposition-peeling-purification-protection" comprehensively solves the problem of adhesive adhesion, achieving filter screen performance regeneration. Attached Figure Description

[0019] Figure 1 This is a schematic flowchart of the cleaning method for the filter assembly on the spinneret in the production process of lyocell fiber, applicable to the present invention.

[0020] Figure 2 This is a microscopic imaging diagram of the cleaned filter assembly in Embodiment 1 of the present invention.

[0021] Figure 3 This is a microscopic imaging diagram of the cleaned filter assembly in Embodiment 2 of the present invention.

[0022] Figure 4 This is a microscopic imaging diagram of the cleaned filter assembly in Embodiment 3 of the present invention.

[0023] Figure 5 This is a microscopic imaging schematic diagram of the cleaned filter assembly in Comparative Example 1 of the present invention.

[0024] Figure 6 This is a microscopic imaging schematic diagram of the cleaned filter assembly in Comparative Example 2 of the present invention.

[0025] Figure 7 This is a microscopic imaging schematic diagram of the cleaned filter assembly in Comparative Example 3 of the present invention.

[0026] Figure 8 This is a microscopic imaging schematic diagram of the cleaned filter assembly in Comparative Example 4 of the present invention.

[0027] Figure 9 This is a microscopic imaging schematic diagram of the cleaned filter assembly in Comparative Example 5 of the present invention.

[0028] Figure 10 This is a microscopic imaging schematic diagram of the cleaned filter assembly in Comparative Example 6 of the present invention.

[0029] Figure 11This is a microscopic imaging schematic diagram of the cleaned filter assembly in Comparative Example 7 of the present invention.

[0030] Figure 12 This is a schematic diagram of a microscopic image of the new filter assembly.

[0031] Figure 13 This is a schematic diagram of the new filter assembly.

[0032] Figure 14 This is a schematic diagram of the cleaned filter assembly in Embodiment 1 of the present invention.

[0033] Figure 15 This is a schematic diagram of the cleaned filter assembly in Comparative Example 2 of the present invention.

[0034] Figure 16 This is a schematic diagram of the cleaned filter assembly in Comparative Example 4 of the present invention. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0036] Example 1 This embodiment provides a method such as Figure 1 The cleaning method shown for the filter assembly on the spinneret in the lyocell fiber production process includes the following steps: S1. Component disassembly: Disassemble the filter assembly from the spinneret unit; S2. Soaking and boiling: Place the disassembled filter assembly in the boiling tank for boiling. After boiling, remove the cleaning basket and allow it to cool naturally to room temperature. Then, use a scraper to clean the adhesive residue from the surface of the filter assembly. The boiling temperature is 80℃ and the boiling time is 60 minutes. S3. Calcination and carbonization: After removing the adhesive residue from the filter screen assembly, place it in a calcination furnace and calcine for 5 hours. After natural cooling, remove the assembly. The calcination temperature is 450℃. S4. High-pressure spraying: The calcined filter screen assembly is cleaned by high-pressure water spraying; the high-pressure spraying pressure is 1.2 MPa; the spraying time is 5 minutes. S5. Ultrasonic cleaning: After high-pressure spraying, the filter assembly is immersed in alkaline cleaning solution at 45°C for 50 minutes under the action of 30kHz ultrasound. Then it is taken out and immersed in acidic cleaning solution at 40°C for 60 minutes under the action of 20kHz ultrasound. The alkaline cleaning solution is a 0.5 mol / L NaOH solution; The acidic cleaning solution is a 0.1 mol / L sulfuric acid solution; S6. Washing and drying: After ultrasonic cleaning, the filter assembly is placed in clean water for 30 minutes to wash and soak. Then, it is dried at 80°C to complete the cleaning.

[0037] In this embodiment, the filter assembly is placed at an angle in the calcination furnace to prevent the calcined carbides from falling into the filter seal.

[0038] Example 2 This embodiment provides a method for cleaning filter assemblies on spinnerets in lyocell fiber production processes, including the following steps: S1. Component disassembly: Disassemble the filter assembly from the spinneret unit; S2. Soaking and boiling: Place the disassembled filter assembly in the boiling tank for boiling. After boiling, remove the cleaning basket and allow it to cool naturally to room temperature. Then, use a scraper to clean the adhesive residue from the surface of the filter assembly. The boiling temperature is 60℃ and the boiling time is 120 minutes. S3. Calcination and carbonization: After removing the adhesive residue from the filter screen assembly, place it in a calcination furnace and calcine for 8 hours. After natural cooling, remove the assembly. The calcination temperature is 350℃. S4. High-pressure spraying: The calcined filter screen assembly is cleaned by high-pressure water spraying; the high-pressure spraying pressure is 1.4 MPa; the spraying time is 3 minutes. S5. Ultrasonic cleaning: After high-pressure spraying, the filter assembly is immersed in alkaline cleaning solution at 50°C for 30 minutes under the action of 40kHz ultrasound. Then it is taken out and immersed in acidic cleaning solution at 45°C for 40 minutes under the action of 30kHz ultrasound. The alkaline cleaning solution is a 1 mol / L NaOH solution; The acidic cleaning solution is a 0.3 mol / L sulfuric acid solution; S6. Washing and drying: After ultrasonic cleaning, the filter assembly is placed in clean water for 10 minutes to wash and soak. Then, it is dried at 60°C to complete the cleaning.

[0039] Example 3 This embodiment provides a method for cleaning filter assemblies on spinnerets in lyocell fiber production processes, including the following steps: S1. Component disassembly: Disassemble the filter assembly from the spinneret unit; S2. Soaking and boiling: Place the disassembled filter assembly in the boiling tank for boiling. After boiling, remove the cleaning basket and allow it to cool naturally to room temperature. Then, use a scraper to clean the adhesive residue from the surface of the filter assembly. The boiling temperature is 100℃ and the boiling time is 30 minutes. S3. Calcination and carbonization: After removing the adhesive residue from the filter screen assembly, place it in a calcination furnace and calcine for 4 hours. After natural cooling, remove the assembly. The calcination temperature is 500℃. S4. High-pressure spraying: The calcined filter screen assembly is cleaned by high-pressure water spraying; the high-pressure spraying pressure is 1.0 MPa; the spraying time is 6 minutes. S5. Ultrasonic cleaning: After high-pressure spraying, the filter assembly is immersed in alkaline cleaning solution at 40°C for 60 minutes under the action of 20kHz ultrasound. Then it is taken out and immersed in acidic cleaning solution at 50°C for 30 minutes under the action of 40kHz ultrasound. The alkaline cleaning solution is a 0.1 mol / L NaOH solution; The acidic cleaning solution is a 0.5 mol / L sulfuric acid solution; S6. Washing and drying: After ultrasonic cleaning, the filter assembly is placed in clean water for 40 minutes to wash and soak. Then, it is dried at 90°C to complete the cleaning.

[0040] Comparative Example 1 The difference between this comparative example and Example 1 is that in this comparative example, the cooking temperature in step S2 is 150°C; the other conditions are the same as in Example 1.

[0041] Comparative Example 2 The difference between this comparative example and Example 1 is that in this comparative example, the calcination temperature in step S3 is 600°C; the other conditions are the same as in Example 1.

[0042] Comparative Example 3 The difference between this comparative example and Example 1 is that the high-pressure spraying step in step S4 is removed in this comparative example, while the other conditions are the same as in Example 1.

[0043] Comparative Example 4 The difference between this comparative example and Example 1 is that the acidic cleaning solution soaking step in step S5 is removed in this comparative example, while the other conditions are the same as in Example 1.

[0044] Comparative Example 5 The difference between this comparative example and Example 1 is that the alkaline cleaning solution soaking step in step S5 is removed in this comparative example, while the other conditions are the same as in Example 1.

[0045] Comparative Example 6 The difference between this comparative example and Example 1 is that, in this comparative example, ultrasonic treatment was not used when the filter assembly was immersed in both acidic and alkaline cleaning solutions in step S5, while the other conditions were the same as in Example 1.

[0046] Comparative Example 7 The difference between this comparative example and Example 1 is that the order of step S2 soaking and cooking and step S3 calcination and carbonization in Example 1 is reversed, while the other conditions are the same as in Example 1.

[0047] Experimental Example In this experimental example, the cleaned filter assemblies of Examples 1-3 and Comparative Examples 1-7 were subjected to the following performance tests, and the test results are shown in Table 1.

[0048] Performance test items: Residual impurities: By observing the imaging effect of the filter assembly under a microscope, observe whether there are impurities and impurities inside its pores; For any deformation: Observe its appearance and the inside of the filter screen for any deformation or cracks; Filter assembly appearance and color: Observe whether the filter can be restored to its original color and performance; Machine usage time: The most important test item, which directly affects its later usage cycle and cost; like Figure 2 The image shown is a microscopic imaging schematic diagram of the cleaned filter assembly in Embodiment 1 of the present invention.

[0049] like Figure 3 The image shown is a microscopic imaging schematic of the cleaned filter assembly in Embodiment 2 of the present invention.

[0050] like Figure 4 The image shown is a microscopic imaging schematic of the cleaned filter assembly in Embodiment 3 of the present invention.

[0051] like Figure 5 The image shown is a microscopic imaging schematic of the cleaned filter assembly in Comparative Example 1 of the present invention.

[0052] like Figure 6 The image shown is a microscopic imaging schematic of the cleaned filter assembly in Comparative Example 2 of the present invention.

[0053] like Figure 7 The image shown is a microscopic imaging schematic of the cleaned filter assembly in Comparative Example 3 of the present invention.

[0054] like Figure 8 The image shown is a microscopic imaging schematic diagram of the cleaned filter assembly in Comparative Example 4 of the present invention.

[0055] like Figure 9 The image shown is a microscopic imaging schematic diagram of the cleaned filter assembly in Comparative Example 5 of the present invention.

[0056] like Figure 10 The image shown is a microscopic imaging schematic of the cleaned filter assembly in Comparative Example 6 of the present invention.

[0057] like Figure 11The image shown is a microscopic imaging schematic of the cleaned filter assembly in Comparative Example 7 of the present invention.

[0058] like Figure 12 The image shown is a schematic diagram of the new filter assembly under a microscope.

[0059] like Figure 13 The diagram shown is a schematic of the new filter assembly.

[0060] like Figure 14 The diagram shown is a schematic of the cleaned filter assembly in Embodiment 1 of the present invention.

[0061] like Figure 15 The diagram shown is a schematic of the cleaned filter assembly in Comparative Example 2 of the present invention.

[0062] like Figure 16 The diagram shown is a schematic of the cleaned filter assembly in Comparative Example 4 of the present invention.

[0063] Table 1 Performance test results of the cleaned filter assemblies in Examples 1-3 and Comparative Examples 1-8 Performance tests were conducted under the same spinning process conditions, specifically a spinning speed of 34.04 m / min, no change in process air parameters, and fiber specifications of 1.33 dtex × 38 mm. The filter assembly was cleaned under the same spinning process.

[0064]

[0065] As can be seen from Table 1: Compared with the example, Comparative Example 1 has a higher degree of cellulose hardening due to the higher cooking temperature, which makes the cellulose too tightly connected to the filter screen assembly. This makes it difficult to handle during degumming, causing the filter screen assembly to deform and reducing the machine's service life.

[0066] Compared with the example, Comparative Example 2 suffered from internal cracking of the filter assembly due to its high calcination temperature. Its stainless steel could only withstand a maximum temperature of 500°C, and the carbonized filter assembly turned silver-black, resulting in poor filtration performance and reduced machine life.

[0067] Compared with the example, Comparative Example 3 has a shorter reinstallation time on the machine because it does not have high-pressure spray to strongly wash away the carbides adhering to the filter pores.

[0068] Compared with the example, Comparative Example 4 was brass-colored because it was not pickled. Under a microscope, its filter screen assembly was also relatively coarse. It can be concluded that the yellowing of the filter screen assembly was caused by the contact of carbides with metal, and the filter screen assembly needs to be cleaned by "chemical rust removal".

[0069] Compared with the embodiment, Comparative Example 5 has a large amount of carbon deposits inside its filter assembly, resulting in a reduced machine life. This is because the carbon deposits inside the filter assembly were not dissolved by alkaline washing, leading to a reduced life.

[0070] Compared with the embodiment, Comparative Example 6 has a shorter machine usage time. This is because the ultrasonic cleaner was not used to remove the carbon deposits from the inner and outer layers of the filter assembly. As a result, the carbon deposits entered the spinneret along with the adhesive during machine use, causing the spinneret to become clogged and reducing the usage time.

[0071] Compared with the example, Comparative Example 7 had its order reversed. Microscopic observation revealed that a large number of filter pores inside its filter assembly were clogged, resulting in a reduced service life. It can be seen that calcination followed by steaming prevented the timely removal of a large amount of carbonaceous material inside.

[0072] from Figures 2-11 It can be seen that all the comparative examples ( Figures 5-11 The filter assemblies prepared by [the aforementioned comparative examples] exhibit significant defects in macroscopic appearance, microstructure, and contaminant residue. These visual evidences directly correspond to deficiencies in the process parameters or steps of the aforementioned comparative examples. The illustrated results consistently show that the comparative examples, due to deviations in their processes from the key technical points of this invention (such as deviations in process temperature, missing steps, or incorrect sequence), ultimately resulted in poor performance of the filter assemblies in terms of cleanliness, structural integrity, or surface characteristics, thus all pointing to a core result: a significant reduction in the effective operating time of the machine.

[0073] Specifically, the illustrated evidence confirms: Structural damage and blockage: Comparative images of Examples 1, 2, and 7 ( Figure 5 , 6 11) The deformation, internal cracking, or large-area blockage of the filter components can be observed, which directly explains the reason for the sharp drop in its service life.

[0074] Contaminant residues: Comparative images of Examples 3, 5, and 6 ( Figure 6 , 9 The results (e.g., 10) indicate that a large amount of carbides are still attached or not removed inside the filter pores or in the interlayer of the components, which is consistent with the process defects of "no high-pressure spraying", "no alkaline washing" and "no ultrasonication".

[0075] Surface anomalies and component residues: Images from Comparative Example 4 ( Figure 8 , Figure 14 The brass color and relatively rough surface morphology of the filter components directly confirm the problem of carbon-metal composite residues caused by the lack of acid washing.

[0076] These visual comparisons strongly demonstrate that the embodiments of the present invention ( Figure 2-4The complete process sequence and precise parameter control established (as shown) are necessary conditions for obtaining filter components with intact structure, thorough cleaning, and long-lasting performance. The omission of any critical step, the reversal of the order, or the deviation of process conditions will leave observable defects in the filter component and ultimately impair its core performance.

[0077] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A method for cleaning the filter screen on the spinneret in the production process of lyocell fiber, characterized in that: Includes the following steps: S1. Component disassembly: Disassemble the filter assembly from the spinneret unit; S2. Soaking and boiling: Place the disassembled filter assembly in the boiling tank for boiling. After boiling, remove the cleaning basket and let it cool naturally to room temperature. Then use a scraper to clean the adhesive residue on the surface of the filter assembly. S3. Calcination and carbonization: After removing the adhesive residue from the filter screen assembly, place it in a calcination furnace and calcine for 4-8 hours. After natural cooling, remove the assembly. S4. High-pressure spraying: The calcined filter screen assembly is cleaned by high-pressure water spraying. S5. Ultrasonic cleaning: The filter assembly after high-pressure spraying is immersed in alkaline cleaning solution and acidic cleaning solution respectively under ultrasonic action at 40℃-50℃ for 30min-60min. S6. Washing and drying: Soak the ultrasonically cleaned filter assembly in clean water for 10-40 minutes, then remove it and dry it at 60℃-90℃ to complete the cleaning.

2. The cleaning method for the filter screen on the spinneret in the lyocell fiber production process according to claim 1, characterized in that: In step S2, the cooking temperature is 60℃-100℃; the cooking time is 30min-120min.

3. The cleaning method for the filter screen on the spinneret in the lyocell fiber production process according to claim 1, characterized in that: In step S3, the calcination temperature is 350℃-500℃.

4. The cleaning method for the filter screen on the spinneret in the lyocell fiber production process according to claim 1, characterized in that: In step S4, the high-pressure spraying pressure is 1.0MPa-1.4MPa; the spraying time is 3min-6min.

5. The cleaning method for the filter screen on the spinneret in the lyocell fiber production process according to claim 1, characterized in that: In step S5, the alkaline cleaning solution is a NaOH solution with a concentration of 0.1 mol / L to 1 mol / L.

6. The cleaning method for the filter screen on the spinneret in the lyocell fiber production process according to claim 1, characterized in that: In step S5, the acidic cleaning solution is a sulfuric acid solution with a concentration of 0.1 mol / L to 0.5 mol / L.

7. The cleaning method for the filter screen on the spinneret in the lyocell fiber production process according to claim 1, characterized in that: In step S5, the ultrasonic frequency is 20kHz-40kHz.

Images