High-efficiency continuous cleaning system for recycling waste PET bottle flakes into polyester staple fibers

Abstract

This invention provides a highly efficient continuous cleaning system for waste PET bottle flakes used for recycling polyester staple fibers, relating to the field of resource recycling technology. It includes a three-stage linkage cleaning module, an integrated continuous conveying system, a wastewater recycling system, a precision sorting module, and an AI visual recognition + multi-sensor fusion control system. The three-stage linkage cleaning module employs a physical-chemical-biological synergistic approach to simultaneously remove three types of impurities from the bottle flake surface: label adhesive, grease, and stains. This invention constructs a three-stage linkage cleaning module that combines low-temperature embrittlement, enzymatic pre-degradation, and high-frequency ultrasound to achieve synergistic physical-chemical-biological decontamination, enabling the simultaneous and efficient removal of label adhesive, grease, and stains. Low-temperature embrittlement rapidly cracks the adhesive layer; enzymatic pre-degradation selectively degrades grease and protein-based stains under alkaline-free conditions, avoiding thermal degradation of the PET molecular chains.

Description

Technical Field

[0001] This invention relates to the field of resource recycling technology, and in particular to a highly efficient continuous cleaning system for waste PET bottle flakes used for recycling polyester staple fibers. Background Technology

[0002] With the rapid development of the recycled polyester staple fiber industry, waste PET bottles, as a core raw material, directly determine the performance and application scenarios of recycled fibers through their recycling and cleaning quality. Currently, the cleaning process for waste PET bottle flakes mainly adopts a single treatment mode of alkaline washing + high-pressure spraying, combined with intermittent stirring tanks for batch processing. Some production lines also use simple filtration devices to treat wastewater, employing single sorting equipment to remove impurities, and adjusting cleaning parameters manually or through simple PLC control. The washing process often employs extensive water washing, resulting in high water consumption and wastewater containing large amounts of oil and impurities, which can easily cause secondary pollution if discharged untreated. The sorting process relies heavily on single equipment, making it difficult to achieve high-precision sorting. Furthermore, the control process is relatively rudimentary, unable to dynamically adjust process parameters based on the contamination level of the bottle flakes.

[0003] Specifically, in existing technologies, label adhesive, grease, and stains cannot be removed simultaneously and efficiently. Alkaline washing methods easily lead to thermal degradation of PET molecular chains, producing harmful substances such as acetaldehyde. The amount of adhesive residue is difficult to control, affecting the quality of recycled fibers. Intermittent processing is inefficient, with cleaning solution evaporation and dust spillage during transportation, causing environmental pollution and resource waste, and high energy consumption. Wastewater treatment methods are simple, with low water resource utilization, large wastewater discharge, and high chemical consumption, resulting in high environmental pressure and production costs. Precision sorting is not accurate enough to effectively separate impurities with similar densities but different materials, making it difficult for the label content, ash content, and impurity content of finished bottle flakes to meet the requirements for food-grade rPET production. The cleaning process lacks intelligent control capabilities, cannot adapt to PET bottle flakes from different sources and with different pollution levels, has poor cleaning effect stability, and is difficult to achieve multi-purpose and intelligent adaptation. Therefore, this invention proposes a high-efficiency continuous cleaning system for waste PET bottle flakes used for recycled polyester staple fiber to solve the problems existing in the prior art. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a highly efficient continuous cleaning system for waste PET bottle flakes used for regenerating polyester staple fibers. This system comprises a three-stage linkage cleaning module consisting of low-temperature embrittlement, enzymatic pre-degradation, and high-frequency ultrasonic synergy, achieving synergistic physical, chemical, and biological decontamination. It simultaneously and efficiently removes three types of impurities: label adhesive, grease, and stains. Specifically, low-temperature embrittlement rapidly cracks the adhesive layer; enzymatic pre-degradation selectively degrades grease and protein stains under alkaline-free conditions, avoiding thermal degradation of the PET molecular chains.

[0005] To achieve the objectives of this invention, the following technical solution is provided: a highly efficient continuous cleaning system for waste PET bottle flakes used for recycling polyester staple fibers, comprising a three-stage linkage cleaning module, an integrated continuous conveying system, a wastewater recycling system, a precision sorting module, and an AI visual recognition + multi-sensor fusion control system. The three-stage linkage cleaning module employs a physical-chemical-biological synergistic approach to simultaneously remove three types of impurities from the bottle flake surface: label adhesive, grease, and stains. The integrated continuous conveying system enables continuous conveying of the bottle flakes from feeding to low-temperature drying, preventing the evaporation of cleaning solution and dust spillage. The wastewater recycling system performs multi-stage purification of the cleaning wastewater before recirculation and reuse.

[0006] The precision sorting module employs a dual sorting and collaborative method to remove impurities with abnormal material or color from the bottle flakes; the AI ​​visual recognition + multi-sensor fusion control system dynamically adjusts the cleaning process parameters to achieve intelligent adaptation of bottle flakes from different sources.

[0007] Further improvements are made in the following aspects: The three-stage linkage cleaning module includes a low-temperature embrittlement unit, an enzymatic pre-degradation unit, and a high-frequency ultrasonic cleaning unit connected in sequence; the low-temperature embrittlement unit uses a -10℃±2℃ cold airflow to perform low-temperature embrittlement treatment on the OPP / PE label surface of the bottle flakes, with the cold airflow action time being 10-15s, causing the adhesive layer to crack; the enzymatic pre-degradation unit uses a protease-lipase composite biological agent, with a protease to lipase mass ratio of 3:2 in the composite biological agent, selectively degrading protein-based stains and animal and vegetable oils under conditions of 40℃±2℃ and pH 7.5±0.2 without strong alkali; the high-frequency ultrasonic cleaning unit uses 28kHz±1kHz high-frequency ultrasound with an ultrasonic power density ≤0.3W / cm². 2 It forms microjets in the cleaning solution to peel off residual adhesive film and oil stains, avoiding thermal degradation of PET molecular chains; after cleaning, the residual adhesive on the bottle flakes is ≤8mg / bottle, and the acetaldehyde generation is ≤0.6ppm.

[0008] Further improvements include: the protease-lipase composite biological agent is further supplemented with 0.5-1.0% of a surfactant, which is a non-ionic surfactant, to enhance the permeability of the enzymatic reaction and improve the removal effect of grease and stains; the cleaning solution of the high-frequency ultrasonic cleaning unit is deionized water, and the cleaning solution circulation rate is 0.8-1.2 m / s to avoid excessive local temperature of the cleaning solution leading to degradation of PET molecular chains.

[0009] Further improvements include: the integrated continuous conveying system adopts an integrated structure for feeding, pre-washing, main washing, rinsing, dehydration, and low-temperature drying, with a core spiral-propelled stainless steel track; the spiral-propelled stainless steel track uses belt-type spiral blades and is equipped with a drive device consisting of a cycloidal pinwheel reducer and a flexible coupling, with the drive device located at the discharge end to keep the spiral shaft under tension; bottle flakes are continuously fed at a constant speed of 0.5m / min ± 0.05m / min, with a single-line processing capacity ≥ 3t / h; each process is connected to a negative pressure suction channel via an airtight isolation valve, which adopts a high-temperature resistant sealing structure, and the negative pressure value of the negative pressure suction channel is controlled at -0.02~-0.05MPa to prevent the evaporation of cleaning liquid and the overflow of dust; the washing area is equipped with five independent spray units, each with different pH and temperature gradients, ranging from 45℃, 55℃, 60℃, 50℃, to 40℃, with temperature fluctuations of ≤ ±1℃ in each section, achieving precise temperature control and gradient utilization of reagents.

[0010] Further improvements include: low-temperature drying uses hot air drying, with a hot air temperature of 60-70℃, a wind speed of 1.5-2.0m / s, and a drying time of 5-8min, resulting in a moisture content of ≤0.5% for the bottle flakes after drying; the surface of the spiral propulsion stainless steel track is equipped with anti-slip protrusions, with a protrusion height of 2-3mm and a spacing of 5-8mm, to prevent slippage during the transport of bottle flakes; the track is made of 304 stainless steel.

[0011] Further improvements include: the wastewater recycling treatment system comprises a bag filter, a ceramic membrane filter, an oil-water separator, a biodegradation tank, and a pH adjustment unit connected in sequence, and also includes an online monitoring device; the bag filter has a filtration accuracy of 100-150 mesh, used to remove large particulate impurities from the wastewater; the ceramic membrane filter has an accuracy of 0.1 μm, an operating pressure of 3.5 Bar, and a flow rate of 200 L / m³. 2 •h, used to remove tiny suspended solids from wastewater; the oil-water separator adopts coalescence + gravity separation technology, the coalescence material is oleophilic and hydrophobic fiber, and the gravity separation time is 30-40 min; the biodegradation tank is inoculated with a special microbial community for PET cleaning wastewater, with a community concentration of 10 6 -10 7 The system uses CFU / mL to degrade residual organic matter in wastewater; the pH adjustment unit controls the pH of the purified wastewater between 6.5 and 7.5 with an adjustment accuracy of ±0.1; the online monitoring device integrates turbidity and COD monitoring sensors, with a data sampling frequency of 1 time / second. When the water turbidity is >10 NTU or COD is >50 mg / L, the bypass treatment is automatically started.

[0012] Further improvements include: a stirring device is installed in the biodegradation tank with a stirring speed of 60-80 r / min to ensure sufficient contact between the microbial community and the wastewater; the bypass treatment uses an activated carbon adsorption device and an ultraviolet disinfection device, with an adsorption capacity of ≥80 mg / g for the activated carbon adsorption device and a power of 30-50 W for the ultraviolet disinfection device, and a disinfection time of 10-15 s to ensure that the wastewater after bypass treatment meets the recycling standards; the pH adjustment unit uses an automatic dosing device, with the reagent being dilute sulfuric acid or dilute sodium hydroxide solution, and the dosing accuracy being ±0.01 L / min.

[0013] Further improvements include: the precision sorting module employs a combined structure of an electrostatic separator and a near-infrared spectral separator; the electrostatic separator has an adjustable high-voltage electric field of 10-20kV, and the grid material is titanium alloy. It effectively separates PVC impurities of similar density but different materials from PET bottle flakes by utilizing the differences in the charging characteristics of different plastic materials in the high-voltage electric field; the near-infrared spectral separator has a detection wavelength range of 800-1200nm, and performs rapid identification and sorting based on the molecular vibrational characteristic spectra of different plastic materials, with an identification accuracy of ≤0.1mm, rejecting bottle flakes with abnormal color and material; the dual sorting works synergistically.

[0014] Further improvements are made in the following aspects: The AI ​​visual recognition + multi-sensor fusion control system includes a visual recognition unit, a sensor network unit, an edge computing unit, and a control algorithm unit. The visual recognition unit is based on the YOLOv8 deep learning model and integrates a PyQt5 visualization interface to identify the light / medium / heavy contamination level of the bottle flakes in real time and automatically switch the corresponding cleaning mode. The sensor network unit integrates five types of sensors: pH, conductivity, turbidity, temperature, and flow rate. Data is uploaded to the edge computing unit every second, with measurement accuracies of pH ±0.1, conductivity ±1μS / cm, turbidity ±0.1NTU, temperature ±0.1℃, and flow rate ±0.01m³. 3 / h; The control algorithm unit adopts fuzzy PID + genetic algorithm to dynamically adjust 12 parameters such as spray pressure, enzyme concentration, ultrasonic power, and water flow speed, so that the cleaning effect stability CV value is ≤3.5%; The system supports remote OTA upgrades and is compatible with PET bottle flakes from different sources; The error calculation formula of fuzzy PID control is:

[0015] e(t) = yd(t) - y(t),

[0016] In the formula: e(t) is the control error at time t, yd(t) is the target value of the cleaning effect at time t, including the amount of adhesive residue and turbidity, and y(t) is the actual value of the cleaning effect at time t.

[0017] A further improvement lies in the following: the genetic algorithm is used to optimize the parameters of the fuzzy PID controller. The objective function for optimization is the combined time and absolute error (ITAE), and the calculation formula is as follows:

[0018] ,

[0019] In the formula: ITAE(t) represents the combined time and absolute error, t represents the control time, and e(t) represents the control error at time t. The parameters of the genetic algorithm are set as follows: population size 50, mutation probability 0.2, crossover probability 0.9, and maximum number of iterations 500. This algorithm achieves optimal tuning of PID parameters and improves control accuracy.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. This invention constructs a three-stage linkage cleaning module combining low-temperature embrittlement, enzymatic pre-degradation, and high-frequency ultrasound to achieve synergistic physical, chemical, and biological decontamination. This module simultaneously and efficiently removes three types of impurities: label adhesive, grease, and stains. Low-temperature embrittlement rapidly cracks the adhesive layer; enzymatic pre-degradation selectively degrades grease and protein stains under alkaline-free conditions, avoiding thermal degradation of PET molecular chains; and high-frequency ultrasound further removes residual impurities, ensuring that the residual adhesive content after cleaning is ≤8mg / bottle and the acetaldehyde generation is ≤0.6ppm. This significantly improves the cleanliness of the bottle flakes, laying the foundation for high-quality production of recycled polyester staple fiber and effectively solving the problems of incomplete impurity removal and easy degradation of PET in existing technologies.

[0022] 2. This invention adopts an integrated continuous conveying system for feeding, pre-washing, main washing, rinsing, dehydration, and low-temperature drying. It uses a spiral-propelled stainless steel conveyor belt to replace the traditional intermittent mixing tank, and is equipped with an airtight isolation valve and a negative pressure suction channel to prevent the evaporation of cleaning liquid and the overflow of dust, thus improving the production environment. The pH and temperature gradient design of the five independent spray units enables efficient utilization of chemicals and energy. The constant-speed continuous feeding of bottle flakes has a single-line processing capacity of ≥3t / h, which improves cleaning efficiency, reduces energy consumption, and effectively solves the problems of low efficiency, high energy consumption, and serious environmental pollution of the intermittent processing technology in the prior art.

[0023] 3. This invention designs a multi-stage wastewater recycling system. Through the synergistic effect of bag filtration, ceramic membrane filtration, oil-water separation, biodegradation, and pH adjustment, it achieves efficient purification and recycling of cleaning wastewater. The recycling rate of the cleaning solution reaches over 90%, reducing wastewater discharge, reagent consumption, and energy consumption. At the same time, online monitoring devices ensure the quality of the recycled water, significantly reducing production costs and environmental pressure. This meets the requirements of energy-saving and environmentally friendly industrial development and effectively solves the problems of low water resource utilization and high environmental pressure in existing technologies.

[0024] 4. This invention employs a dual precision sorting structure combining an electrostatic separator and a near-infrared spectral separator. Electrostatic separation can effectively separate impurities such as PVC with similar densities but different materials, while near-infrared spectral separation can accurately remove bottle flakes with abnormal color and material. The dual synergy ensures that the label content of the finished bottle flakes is ≤5ppm, and the ash and impurity content meets the production requirements of food-grade rPET. This solves the problem of insufficient sorting precision in existing technologies and the inability to meet the needs of high-end recycling, thus broadening the application range of waste PET bottle flakes.

[0025] 5. This invention is equipped with an AI visual recognition + multi-sensor fusion control system. Based on the YOLOv8 model, it identifies the contamination level of bottle flakes in real time. Combining real-time data from five types of sensors, it dynamically adjusts 12 cleaning parameters through fuzzy PID + genetic algorithm, so that the cleaning effect stability is ≤3.5%. The system supports remote OTA upgrades and is compatible with PET bottle flakes from different sources. It solves the problems of rough control, poor adaptability and unstable effect of cleaning process in the prior art, and improves the intelligence level and versatility of the system. Attached Figure Description

[0026] Figure 1 This is the front view of the present invention. Detailed Implementation

[0027] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0028] Example 1

[0029] according to Figure 1 As shown in the figure, this embodiment proposes a highly efficient continuous cleaning system for waste PET bottle flakes used for recycled polyester staple fiber. The system includes a three-stage linkage cleaning module, an integrated continuous conveying system, a wastewater recycling system, a precision sorting module, and an AI visual recognition + multi-sensor fusion control system. The specific structure is as follows:

[0030] The three-stage linkage cleaning module includes: a low-temperature embrittlement unit using -10℃ cold airflow for 12 seconds to embrittle OPP / PE labels on bottle flakes, achieving a label peeling rate of 99.1%; an enzymatic pre-degradation unit using a protease-lipase composite biological agent (mass ratio 3:2) with 0.8% nonionic surfactant, degrading protein-based stains and animal and vegetable oils at 40℃ and pH 7.5, achieving an enzymatic hydrolysis efficiency of 92.3%; and a high-frequency ultrasonic cleaning unit using 28kHz high-frequency ultrasound with a power density of 0.25W / cm³. 2 The cleaning solution was deionized water, with a circulation flow rate of 1.0 m / s. It removed residual adhesive film and oil stains, and the amount of adhesive residue after cleaning was 7.2 mg / bottle, and the amount of acetaldehyde generated was 0.52 ppm.

[0031] Integrated continuous conveying system: Adopting an integrated structure of "feeding—pre-washing—main washing—rinsing—dehydration—low-temperature drying," the spiral-propelled stainless steel conveyor belt is made of 304 stainless steel with belt-type spiral blades, equipped with a cycloidal pinwheel reducer and flexible coupling. The drive unit is located at the discharge end. Bottle flakes are continuously fed at a constant speed of 0.5 m / min, with a single-line processing capacity of 3 t / h. Each process is connected to a negative pressure suction channel via an airtight isolation valve, with a negative pressure value of -0.03 MPa. The temperature gradient of the five-stage spray unit in the washing zone is 45℃→55℃→60℃→50℃→40℃, with pH gradients of 8.5, 7.5, 7.0, 6.5, and 6.0 respectively. The low-temperature drying unit uses 65℃ hot air at a wind speed of 1.8 m / s for 6 minutes, resulting in a bottle flake moisture content of 0.4% after drying. The system's energy consumption is reduced by 38% compared to traditional systems, and the cleaning efficiency is increased by 4.2 times compared to traditional batch systems.

[0032] Wastewater recycling system: Bag filter with a filtration accuracy of 120 mesh, removing large particulate impurities with a removal rate of 98.5%; Ceramic membrane filter with an accuracy of 0.1μm, operating pressure of 3.5 Bar, and flow rate of 200L / m³. 2 • h, removing minute suspended solids with a removal rate of 99.2%; the oil-water separator adopts coalescence + gravity separation technology, with coalescence material being oleophilic and hydrophobic fibers, gravity separation time of 35 min, and oil separation efficiency of 95.3%; the biodegradation tank is inoculated with a special microbial community for PET cleaning wastewater, with a community concentration of 10 6 The COD removal rate is 86% (CFU / mL); the pH adjustment unit controls the wastewater pH between 6.8 and 7.2 with an adjustment accuracy of ±0.1; the online monitoring device monitors turbidity and COD in real time, and automatically starts bypass treatment when turbidity > 10 NTU or COD > 50 mg / L; the cleaning solution recycling rate is 90.5%, wastewater discharge is reduced by 85%, reagent consumption is reduced by 40%, and energy consumption is reduced by 25%.

[0033] Precision sorting module: The electrostatic separator has a high-voltage electric field of 15kV and a grid material of titanium alloy, with a sorting efficiency of 98.6%; the near-infrared spectral separator has a detection wavelength of 800-1200nm and an identification accuracy of 0.08mm; after double sorting, the finished bottle label content is 4.2ppm, the ash content is 0.04%, and the impurity content is 0.025%, meeting the production requirements of food-grade rPET.

[0034] AI visual recognition + multi-sensor fusion control system: The visual recognition unit is based on the YOLOv8 model and integrates a PyQt5 visualization interface, achieving a 99.2% accuracy rate in identifying the contamination level of bottle flakes and automatically switching cleaning modes; the sensor network unit integrates five types of sensors, with data uploaded to the edge computing unit every second, ensuring measurement accuracy meets requirements; the control algorithm unit adopts fuzzy PID + genetic algorithm, with genetic algorithm parameters of a population size of 50, a mutation probability of 0.2, a crossover probability of 0.9, a maximum number of iterations of 500, dynamically adjusting 12 cleaning parameters, and achieving a cleaning effect stability CV value of 3.2%; the system supports remote OTA upgrades and is adaptable to the cleaning of PET bottle flakes from beverage bottles.

[0035] Example 2

[0036] according to Figure 1 As shown, this embodiment proposes a highly efficient continuous cleaning system for waste PET bottle flakes used for recycled polyester staple fiber. The core parameters of the three-stage linkage cleaning module are precisely optimized to significantly improve impurity removal efficiency and bottle flake cleanliness, adapting to the production needs of high-end recycled polyester staple fiber (such as medical-grade and food-contact-grade). The remaining system structure, connection methods, and basic parameters are completely consistent with Embodiment 1. Details of the optimized three-stage linkage cleaning module are as follows:

[0037] Low-temperature embrittlement unit: Compared to the -10℃ cold airflow in Example 1, this example uses a constant-temperature cold airflow of -8℃±0.5℃. The cold airflow is provided by a low-temperature refrigeration unit, with the outlet air velocity controlled at 3.5m / s and the action time extended to 15s. A uniform air distribution plate is installed within the cold airflow channel to ensure that the cold airflow evenly covers each PET bottle sheet, preventing localized areas where the label adhesive layer remains unembrittled. After optimization, the adhesive layer of the OPP / PE label on the bottle sheet surface is more thoroughly embrittled, and the label peeling rate increases from 99.1% in Example 1 to 99.3%. The size of the peeled label fragments is ≤5mm, allowing for rapid separation by a subsequent screening device, preventing secondary adhesion to the bottle sheet surface. Enzymatic pre-degradation unit: The protease-lipase composite biological agent is still used, with the mass ratio of protease to lipase remaining unchanged at 3:2. However, 1.0% of a nonionic surfactant (specifically fatty alcohol polyoxyethylene ether) is added to the composite biological agent. This surfactant reduces the surface tension of the cleaning solution, enhances the permeability of the enzymatic reaction, and allows the biological agent to quickly penetrate into the crevices and wrinkles on the bottle flake surface, fully contacting hidden protein stains and animal and vegetable oils. Simultaneously, the enzymatic pre-degradation temperature is adjusted to 42℃±0.3℃, and the pH value is adjusted to 7.7±0.1. This parameter combination has been verified through multiple experiments to maximize enzyme activity, increasing the enzymatic hydrolysis efficiency from 92.3% in Example 1 to 93.1%. This effectively degrades stubborn grease and protein stains on the bottle flake surface, especially the residual grease on edible oil bottle flakes, where the degradation effect is more significant. High-frequency ultrasonic cleaning unit: The ultrasonic frequency was adjusted to 29kHz±0.5kHz, and the power density was increased to 0.3W / cm² (still controlled within the safe range of ≤0.3W / cm²). Deionized water was still used as the cleaning solution, and the circulation speed of the cleaning solution was increased to 1.2m / s. By accelerating the circulation speed of the cleaning solution, residual adhesive film and oil stains removed by ultrasonic stripping were promptly removed, preventing residual impurities from accumulating in the cleaning solution and adhering to the bottle flake surface. After optimization, the residual adhesive content of the bottle flakes after cleaning was reduced to 6.8mg / bottle, and the acetaldehyde generation was reduced to 0.48ppm, both of which are better than the indicators in Example 1. Moreover, there were no scratches or damage on the bottle flake surface, and the PET molecular chain structure remained intact, which would not affect the spinning performance of the subsequent recycled polyester staple fiber.

[0038] In this embodiment, through precise optimization of the parameters of each unit in the three-stage linkage cleaning module, the impurity removal effect is further improved, the label peeling rate and enzymatic hydrolysis efficiency are steadily increased, the amount of adhesive residue and acetaldehyde generation are further reduced, and the cleanliness of the bottle flakes reaches a higher standard. This optimization scheme is particularly suitable for scenarios with extremely high requirements for the quality of recycled polyester staple fiber, such as the production of food contact polyester staple fiber and medical polyester staple fiber. It can effectively avoid the impact of impurities and harmful substances on the performance of the final product, while maintaining the original performance of the PET bottle flakes, providing a high-quality raw material guarantee for subsequent spinning processes. In addition, after parameter optimization, the operational stability of the three-stage linkage cleaning module is also improved, with no downtime due to malfunctions. After 72 hours of continuous operation, all indicators remain stable, meeting the needs of large-scale continuous production.

[0039] Example 3

[0040] according to Figure 1 As shown, this embodiment proposes a highly efficient continuous cleaning system for waste PET bottle flakes used for recycled polyester staple fiber. The focus is on optimizing the structural and operational parameters of the integrated continuous conveying system. The core objective is to improve conveying stability, production efficiency, and energy utilization, solving the problems of bottle flake slippage, uneven conveying, and high energy consumption in large-scale continuous production. The structure and parameters of the remaining system modules (three-stage linkage cleaning, wastewater circulation, precision sorting, and AI control) are consistent with those of Embodiment 1. Specific optimization details are as follows:

[0041] Optimization of the Spiral Propulsion Stainless Steel Track: Based on Example 1, the spiral propulsion stainless steel track has been structurally improved. Anti-slip protrusions are evenly distributed on the track surface, with a height of 2.5mm and a spacing of 6mm. The protrusion cross-section adopts an arc design, which effectively prevents bottle flakes from slipping and shifting during transport without scratching the surface of the bottle flakes. The track material remains 304 stainless steel, but a surface polishing treatment has been added, with a surface roughness ≤0.8μm. This not only improves the track's corrosion resistance and ease of cleaning but also reduces the friction between the bottle flakes and the track, lowering drive energy consumption. Simultaneously, the track width has been adjusted from 800mm in Example 1 to 1000mm, and the pitch of the spiral blades has been adjusted to 150mm. This is combined with a drive device consisting of a cycloidal pinwheel reducer (model XWD8-17-1.5) and a flexible coupling. The drive device is still located at the discharge end, keeping the spiral shaft under tension to reduce bending deformation and ensure smooth track operation. Conveying parameters were optimized: the conveying speed of the bottle flakes was adjusted from 0.5 m / min to 0.55 m / min ± 0.05 m / min. Calculations showed that the single-line processing capacity increased to 3.2 t / h, a 6.7% increase compared to Example 1, meeting the needs of larger-scale production. The negative pressure suction channels between processes were optimized, adjusting the negative pressure value to -0.04 MPa ± 0.005 MPa. Compared to -0.03 MPa in Example 1, the negative pressure suction is stronger, more thoroughly preventing the evaporation of cleaning fluid and dust spillage, improving the working environment in the production workshop, and preventing dust from entering subsequent processes and affecting the quality of the bottle flakes. Optimization of the washing zone spray unit: The five independent spray units in the washing zone have a temperature gradient adjusted to 46℃→56℃→61℃→51℃→41℃, with temperature fluctuations controlled within ≤±0.8℃ for each segment. This represents higher temperature control accuracy compared to ±1℃ in Example 1. Simultaneously, the pH gradient of each spray unit has been adjusted to 8.8, 7.8, 7.2, 6.8, and 6.2, respectively, resulting in a smoother gradient and more efficient use of the chemicals, reducing waste. Optimization of the low-temperature drying unit: The hot air temperature of the low-temperature drying unit has been increased to 70℃±1℃, the air velocity adjusted to 2.0m / s, and the drying time shortened to 5 minutes. By increasing the hot air temperature and air velocity, the evaporation rate of moisture on the surface of the PET flakes is accelerated, while avoiding excessive temperature that could lead to deformation and degradation of the PET flakes. After optimization, the moisture content of the dried PET flakes is reduced to 0.35%, lower than the 0.4% in Example 1, which is more conducive to subsequent precision sorting and recycled spinning processes. System energy consumption optimization: Through the above parameter and structural optimization, the overall operating energy consumption of the integrated continuous conveying system is reduced by 39% compared with the traditional system and by 1 percentage point compared with Example 1; the cleaning efficiency is increased by 4.4 times compared with the traditional batch system and by 0.2 times compared with Example 1, achieving dual optimization of efficiency and energy consumption.

[0042] In this embodiment, through structural improvements and parameter optimization of the integrated continuous conveying system, the system's conveying stability, production efficiency, and energy utilization rate are significantly improved. The anti-slip protrusion design effectively solves the slippage problem during bottle flake conveying, and the increased conveying speed and single-line processing capacity meet the needs of large-scale continuous production. Optimization of the negative pressure suction channel and spray unit not only improves the production environment but also achieves efficient utilization of reagents and energy. Optimization of the low-temperature drying unit shortens drying time, improves drying effect, and provides higher-quality bottle flake raw materials for subsequent processes. In addition, structural improvements and material optimization of the conveyor belt extend its service life, reduce equipment maintenance costs, and further enhance the economy and practicality of the entire cleaning system. This optimized solution is suitable for large-scale waste PET bottle flake recycling and processing plants, enabling efficient, continuous, and low-consumption production operation, significantly improving the company's production efficiency and market competitiveness.

[0043] Example 4

[0044] according to Figure 1 As shown, this embodiment proposes a highly efficient continuous cleaning system for waste PET bottle flakes used for recycled polyester staple fiber. The parameters and structure of each unit in the wastewater recycling system are comprehensively optimized, focusing on improving wastewater purification efficiency, water resource recycling rate, and reagent saving rate, further reducing production costs and environmental pressure, and adapting to production scenarios with strict environmental requirements. The structure and parameters of the remaining system modules are consistent with those in Embodiment 1. Specific optimization details are as follows:

[0045] Filtration unit optimization: The filtration precision of the bag filter has been improved from 120 mesh in Example 1 to 150 mesh. The filter bag is made of polypropylene, and its uniform pore size allows for more effective removal of large particulate impurities in wastewater (such as label fragments, bottle flakes, etc.). The removal rate of large particulate impurities has increased from 98.5% to 99%, preventing large particulate impurities from entering the subsequent ceramic membrane filter and causing membrane pore blockage, thus extending the service life of the ceramic membrane. The flux of the ceramic membrane filter has been increased from 200 L / m³. 2 h increased to 210L / m 2The operating pressure remained unchanged at 3.5 Bar. The ceramic membrane was made of alumina material with a pore size of 0.1 μm. By optimizing the membrane surface structure, the filtration efficiency and antifouling ability were improved, increasing the removal rate of fine suspended solids from 99.2% to 99.5%, ensuring that the clarity of the filtered wastewater met the requirements for subsequent treatment. Oil-water separation unit optimization: The oil-water separator still uses coalescence + gravity separation technology, but the gravity separation time was extended from 35 min to 40 min. The number of coalescence plates was increased, and the spacing between them was adjusted to 10 mm. The coalescence material remained oleophilic and hydrophobic fibers. By extending the separation time and increasing the coalescence area, the separation effect of oily impurities was further improved, increasing the oil separation efficiency from 95.3% to 96.2%. The separated oil can be recycled and reused, achieving secondary resource utilization. Biodegradation unit optimization: The concentration of special microbial flora for PET cleaning wastewater in the biodegradation tank was increased from 10... 6 CFU / mL increased to 10 7The bacterial flora, with a concentration of CFU / mL, is a blend of Bacillus, Pseudomonas, and yeast in a 2:2:1 ratio. This blend can more efficiently degrade residual organic matter in wastewater (such as enzyme residues and surfactant residues), increasing the COD removal rate from 86% to 88%. Simultaneously, a stirring device (model JBJ-500) is added to the biodegradation tank, with the stirring speed controlled at 70 r / min to ensure sufficient contact between the microbial flora and the wastewater, preventing bacterial sedimentation and improving the biodegradation effect. The pH adjustment and bypass treatment unit has been optimized: the pH adjustment unit controls the pH of the purified wastewater between 6.5 and 7.0, maintaining an adjustment accuracy of ±0.1. An automatic dosing device (model JY-100) is used, employing dilute sulfuric acid or dilute sodium hydroxide solution, with a dosing accuracy improved to ±0.005 L / min. This allows for more precise control of the wastewater pH value, ensuring stable circulating water quality. The bypass treatment unit has been upgraded. The activated carbon adsorption device uses columnar activated carbon, increasing the adsorption capacity from 80 mg / g to 85 mg / g, and the activated carbon filling amount has increased by 20%, enabling more effective adsorption of trace organic matter and pigments in the wastewater. The power of the ultraviolet disinfection device has been increased from 40W in Example 1 to 50W, the disinfection time has been adjusted to 12s, and the ultraviolet wavelength has been controlled at 254nm, which can thoroughly kill harmful microorganisms in the wastewater and ensure that the wastewater after bypass treatment meets the recycling standards. The online monitoring device has been optimized: the sampling frequency of the online monitoring device remains unchanged at 1 time / second, and a new conductivity monitoring sensor has been added, which can monitor the conductivity of the circulating water in real time, detect changes in the ion concentration in the water in a timely manner, avoid excessive addition of reagents, and further save reagent consumption. After the above optimization, the recycling rate of cleaning fluid increased from 90.5% to 92%, the wastewater discharge was reduced by 87% compared with the traditional system (2 percentage points higher than Example 1), the reagent consumption was reduced by 42% (2 percentage points higher than Example 1), and the energy consumption was reduced by 26% (1 percentage point higher than Example 1). The environmental and economic benefits were significantly improved.

[0046] In this embodiment, through comprehensive optimization of each unit of the wastewater recycling system, the wastewater purification effect, water resource recycling rate, and reagent saving rate have all been significantly improved, further reducing production costs and environmental pressure, and fully complying with national energy conservation and environmental protection industrial policies. Optimization of the filtration unit effectively extends the service life of the ceramic membrane and reduces equipment maintenance costs; optimization of the oil-water separation unit enables the recovery and reuse of grease, improving resource utilization; optimization of the biodegradation unit improves the degradation efficiency of organic matter, ensuring wastewater meets recycling standards; optimization of the pH adjustment and bypass treatment units further guarantees the quality of circulating water and avoids impacting subsequent cleaning processes. This optimized solution is particularly suitable for areas with strict environmental requirements and water shortages, helping enterprises achieve green production, reduce wastewater discharge and reagent consumption, while lowering production costs and enhancing their market competitiveness. Furthermore, the optimized wastewater recycling system operates stably, has a high degree of automation, requires minimal manual intervention, and can adapt to the needs of long-term continuous production, further improving the practicality and reliability of the entire cleaning system.

[0047] Example 5

[0048] according to Figure 1 As shown, this embodiment proposes a highly efficient continuous cleaning system for waste PET bottle flakes used for recycled polyester staple fiber. The parameters of the precision sorting module and the AI ​​vision recognition + multi-sensor fusion control system are simultaneously optimized, focusing on improving sorting accuracy, recognition accuracy, and system adaptability. This enables precise sorting and intelligent control of PET bottle flakes from different sources and with varying levels of contamination. It is particularly suitable for cleaning and sorting PET bottle flakes from edible oil bottles with high oil content and cosmetic bottles with complex compositions. The structure and parameters of the remaining system modules are consistent with those in Embodiment 1. Specific optimization details are as follows:

[0049] Precision sorting module optimization: The high-voltage electric field voltage of the electrostatic separator was increased from 15kV in Example 1 to 20kV±1kV. The grid material remained titanium alloy, but the grid spacing was adjusted to 50mm. By increasing the high-voltage electric field voltage and optimizing the grid spacing, the charge difference between different plastic materials was enhanced, enabling more effective separation of impurities such as PVC and PP with different materials but similar densities from PET bottle flakes. The sorting efficiency increased from 98.6% to 99%. Simultaneously, a vibrating cloth device was added to the feed inlet of the electrostatic separator to ensure uniform distribution of bottle flakes and prevent accumulation, further improving sorting accuracy. The near-infrared spectral separator underwent comprehensive optimization. While the detection wavelength range remained unchanged at 800-1200nm, the recognition accuracy was improved from 0.08mm to 0.06mm. A line scanning detection method was adopted, increasing the detection speed to 10m / min. This allows for rapid identification of color anomalies (such as yellowing, blackening, and mixed colors) and material anomalies (such as mixed PVC and PE fragments), achieving an accuracy rate of 99.8%. Furthermore, a secondary sorting channel was added to the discharge end of the near-infrared spectral sorter to perform a second screening of the bottle flakes after the initial sorting, further removing residual impurities and ensuring the sorting effect. After the above optimization, under the synergistic effect of dual sorting, the label content of the finished bottle flakes was reduced to 3.8 ppm, the ash content to 0.035%, and the impurity content to 0.02%, all of which are better than the indicators of Example 1, fully meeting the production requirements of food-grade rPET, and even meeting the raw material requirements of high-end food contact recycled polyester staple fiber. AI visual recognition + multi-sensor fusion control system optimization: The visual recognition unit is based on the YOLOv8 deep learning model. The model has been trained and optimized, and the contamination sample library of bottle flakes from different sources such as cooking oil bottles and cosmetic bottles has been expanded. The number of samples has increased by 50% compared to Example 1, and the recognition accuracy has improved from 99.2% to 99.5%. It can more accurately identify the contamination level (light / medium / heavy) of bottle flakes, especially for stubborn stains on the surface of cosmetic bottle flakes and grease residue on the surface of cooking oil bottle flakes. It can quickly identify and automatically switch the corresponding cleaning mode (e.g., in the heavy contamination mode, it automatically increases the enzyme concentration and ultrasonic power). The arrangement of the sensor network unit has been optimized. Sensors have been added to each unit of the three-level linkage cleaning module to realize real-time monitoring of the cleaning process. The data upload speed remains unchanged at 1 time / second, and the measurement accuracy has been further improved. The pH measurement accuracy reaches ±0.05, and the conductivity measurement accuracy reaches ±0.5μS / cm, ensuring the accuracy of the monitoring data. The control algorithm unit was optimized by increasing the maximum number of iterations of the genetic algorithm from 500 to 600, keeping the population size unchanged at 50, with a mutation probability of 0.2 and a crossover probability of 0.9. By increasing the number of iterations, the optimization accuracy of the PID parameters was further improved, and the stability of the cleaning effect (CV value) was reduced from 3.2% to 3.0%, ensuring the consistency of the cleaning effect.The system's adaptability has been optimized. Through remote OTA upgrades, dedicated cleaning parameter templates for PET flakes used in edible oil and cosmetic bottles have been added. Users can switch parameter templates with a single click based on the source of the flakes, eliminating the need for manual adjustments and achieving "one machine for multiple uses and intelligent adaptation." For edible oil bottle flakes with high oil content, the dedicated template automatically increases the enzyme concentration and reaction time of the enzymatic pre-degradation unit. For cosmetic bottle flakes with complex compositions, the ultrasonic power and spray pressure are automatically adjusted to ensure satisfactory cleaning results. Testing shows that the optimized system, when cleaning PET flakes from edible oil bottles, can control residual adhesive to below 7.0 mg / bottle, acetaldehyde generation ≤0.5 ppm, and impurity content after sorting ≤0.025%, fully meeting production requirements.

[0050] In this embodiment, through the simultaneous optimization of the precision sorting module and the AI ​​visual recognition + multi-sensor fusion control system, the system's sorting accuracy, recognition accuracy, and adaptability are significantly improved. The optimization of the precision sorting module further reduces the impurity content of the finished bottle flakes, improves the quality of the flakes, and broadens the application range of waste PET bottle flakes, making it suitable for the production of high-end recycled polyester staple fiber. The optimization of the AI ​​control system improves the accuracy of contamination identification and the precision of cleaning parameter control, resulting in more stable cleaning effects. It also enhances the system's adaptability to bottle flakes from different sources, especially for PET bottle flakes from edible oil bottles and cosmetic bottles with high oil content and complex compositions, enabling precise cleaning and sorting and solving the problems of poor adaptability and unstable cleaning effects in traditional systems. Furthermore, the optimized system has a further improved level of intelligence, making operation more convenient and requiring less manual intervention. It can adapt to the recycling and processing needs of different types of waste PET bottle flakes, reducing labor costs and improving production efficiency. This optimization scheme is suitable for diversified waste PET bottle flake recycling and processing enterprises. It can achieve efficient processing of bottle flakes from different sources and with different levels of contamination, improve the enterprise's production flexibility and market competitiveness, and promote the high-quality development of resource recycling and utilization of waste PET bottle flakes.

[0051] Validation data:

[0052] The present invention has been verified through five embodiments, and all technical indicators are superior to those of the prior art. The specific summary data is shown in the table below (based on Embodiment 1):

[0053]

[0054] In summary, this invention achieves efficient, continuous, and environmentally friendly cleaning and sorting of waste PET bottle flakes, with all technical indicators meeting food-grade production requirements. It significantly improves the resource recycling efficiency and quality of waste PET bottle flakes, while reducing production costs and environmental pressure.

[0055] This invention constructs a three-stage linkage cleaning module combining low-temperature embrittlement, enzymatic pre-degradation, and high-frequency ultrasound to achieve synergistic physical, chemical, and biological decontamination. This module simultaneously and efficiently removes three types of impurities: label adhesive, grease, and stains. Low-temperature embrittlement rapidly cracks the adhesive layer; enzymatic pre-degradation selectively degrades grease and protein stains under alkaline-free conditions, avoiding thermal degradation of PET molecular chains; and high-frequency ultrasound further removes residual impurities, ensuring that the residual adhesive content after cleaning is ≤8mg / bottle and the acetaldehyde generation is ≤0.6ppm. This significantly improves the cleanliness of the bottle flakes, laying the foundation for high-quality production of recycled polyester staple fiber and effectively solving the problems of incomplete impurity removal and easy degradation of PET in existing technologies. This invention employs an integrated continuous conveying system encompassing feeding, pre-washing, main washing, rinsing, dehydration, and low-temperature drying. It replaces the traditional intermittent mixing tank with a spiral-propelled stainless steel conveyor belt, coupled with an airtight isolation valve and negative pressure suction channel to prevent cleaning fluid evaporation and dust spillage, thus improving the production environment. The five independent spray units feature pH and temperature gradient design, achieving efficient utilization of chemicals and energy. Constant-speed continuous feeding of bottle flakes, with a single-line processing capacity ≥3t / h, enhances cleaning efficiency and reduces energy consumption, effectively solving the problems of low efficiency, high energy consumption, and severe environmental pollution associated with existing intermittent processing technologies. This invention also designs a multi-stage wastewater recycling system. Through the synergistic effects of bag filtration, ceramic membrane filtration, oil-water separation, biodegradation, and pH adjustment, it achieves efficient purification and recycling of cleaning wastewater, with a recycling rate exceeding 90%. This reduces wastewater discharge, chemical consumption, and energy consumption. Simultaneously, online monitoring devices ensure the quality of the recycled water, significantly reducing production costs and environmental pressure, meeting the requirements of energy-saving and environmentally friendly industrial development, and effectively solving the problems of low water resource utilization and high environmental pressure in existing technologies. This invention employs a dual precision sorting structure combining an electrostatic separator and a near-infrared spectral separator. Electrostatic sorting effectively separates impurities such as PVC with similar densities but different materials, while near-infrared spectral sorting precisely removes bottle flakes with abnormal color and material. This dual synergy ensures that the finished bottle flake label content is ≤5ppm, and the ash and impurity content meets the requirements for food-grade rPET production. This solves the problems of insufficient sorting precision and inability to meet high-end recycling needs in existing technologies, broadening the application range of waste PET bottle flakes. The invention is equipped with an AI visual recognition + multi-sensor fusion control system. Based on the YOLOv8 model, it identifies the contamination level of bottle flakes in real time. Combining real-time data from five types of sensors, it dynamically adjusts 12 cleaning parameters through fuzzy PID + genetic algorithm, achieving a cleaning effect stability of ≤3.5%. The system supports remote OTA upgrades and is adaptable to PET bottle flakes from different sources, solving the problems of crude cleaning process control, poor adaptability, and unstable effects in existing technologies, thus improving the system's intelligence and versatility.

[0056] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-efficiency continuous cleaning system for waste PET bottle flakes used for recycling polyester staple fibers, comprising a three-stage linkage cleaning module, an integrated continuous conveying system, a wastewater recycling system, a precision sorting module, and an AI visual recognition + multi-sensor fusion control system, characterized in that: The three-stage linkage cleaning module adopts a physical-chemical-biological synergistic approach to simultaneously remove three types of impurities from the surface of the bottle flakes: label adhesive, grease, and stains. The integrated continuous conveying system enables continuous conveying of the bottle flakes from feeding to low-temperature drying, preventing the evaporation of cleaning solution and the overflow of dust. The wastewater recycling system purifies the cleaning wastewater through multiple stages before recirculating it for reuse. The precision sorting module employs a dual sorting and collaborative method to remove impurities with abnormal material or color from the bottle flakes; the AI ​​visual recognition + multi-sensor fusion control system dynamically adjusts the cleaning process parameters to achieve intelligent adaptation of bottle flakes from different sources.

2. The efficient continuous cleaning system for waste PET bottle flakes used for recycling polyester staple fibers according to claim 1, characterized in that: The three-stage linkage cleaning module includes a low-temperature embrittlement unit, an enzymatic pre-degradation unit, and a high-frequency ultrasonic cleaning unit connected in sequence. The low-temperature embrittlement unit uses a -10℃±2℃ cold airflow to treat the OPP / PE labels on the bottle surface, with the cold airflow acting for 10-15 seconds, causing the adhesive layer to crack. The enzymatic pre-degradation unit uses a protease-lipase composite biological agent, with a protease to lipase mass ratio of 3:2, selectively degrading protein-based stains and animal and vegetable oils under conditions of 40℃±2℃ and pH 7.5±0.2 without strong alkali. The high-frequency ultrasonic cleaning unit uses 28kHz±1kHz high-frequency ultrasound with an ultrasonic power density ≤0.3W / cm². 2 It forms microjets in the cleaning solution to peel off residual adhesive film and oil stains, avoiding thermal degradation of PET molecular chains; after cleaning, the residual adhesive on the bottle flakes is ≤8mg / bottle, and the acetaldehyde generation is ≤0.6ppm.

3. The efficient continuous cleaning system for waste PET bottle flakes used for recycling polyester staple fibers according to claim 2, characterized in that: The protease-lipase composite biological agent also contains 0.5-1.0% surfactant, which is a nonionic surfactant, to enhance the permeability of the enzymatic reaction and improve the removal effect of grease and stains; the cleaning solution of the high-frequency ultrasonic cleaning unit is deionized water, and the cleaning solution circulation rate is 0.8-1.2m / s to avoid excessive local temperature of the cleaning solution leading to degradation of PET molecular chains.

4. The efficient continuous cleaning system for waste PET bottle flakes used for recycling polyester staple fibers according to claim 1, characterized in that: The integrated continuous conveying system adopts an integrated structure of feeding, pre-washing, main washing, rinsing, dehydration, and low-temperature drying. The core component is a spiral-propelled stainless steel conveyor belt. This belt uses belt-type spiral blades and is equipped with a drive unit consisting of a cycloidal pinwheel reducer and a flexible coupling. The drive unit is located at the discharge end, keeping the spiral shaft under tension. Bottle flakes are continuously fed at a constant speed of 0.5 m / min ± 0.05 m / min, with a single-line processing capacity ≥ 3 t / h. Each process is connected to a negative pressure suction channel via an airtight isolation valve. The airtight isolation valve uses a high-temperature resistant sealing structure, and the negative pressure value of the negative pressure suction channel is controlled at -0.02 to -0.05 MPa to prevent the evaporation of cleaning fluid and dust spillage. The washing area is equipped with five independent spray units, each with different pH and temperature gradients ranging from 45℃, 55℃, 60℃, 50℃, to 40℃. The temperature fluctuation of each section is ≤ ±1℃, achieving precise temperature control and gradient utilization of the reagents.

5. The efficient continuous cleaning system for waste PET bottle flakes used for recycling polyester staple fibers according to claim 4, characterized in that: Low-temperature drying uses hot air drying, with a hot air temperature of 60-70℃, a wind speed of 1.5-2.0m / s, and a drying time of 5-8min. After drying, the moisture content of the bottle flakes is ≤0.5%. The surface of the spiral propulsion stainless steel track is equipped with anti-slip protrusions with a protrusion height of 2-3mm and a spacing of 5-8mm to prevent the bottle flakes from slipping during transportation. The track is made of 304 stainless steel.

6. The efficient continuous cleaning system for waste PET bottle flakes used for recycling polyester staple fibers according to claim 1, characterized in that: The wastewater recycling system includes a bag filter, a ceramic membrane filter, an oil-water separator, a biodegradation tank, and a pH adjustment unit connected in sequence, and also includes an online monitoring device. The bag filter has a filtration accuracy of 100-150 mesh and is used to remove large particulate impurities from the wastewater. The ceramic membrane filter has an accuracy of 0.1 μm, an operating pressure of 3.5 Bar, and a flow rate of 200 L / m³. 2 •h, used to remove tiny suspended solids from wastewater; the oil-water separator adopts coalescence + gravity separation technology, the coalescence material is oleophilic and hydrophobic fiber, and the gravity separation time is 30-40 min; the biodegradation tank is inoculated with a special microbial community for PET cleaning wastewater, with a community concentration of 10 6 -10 7 The system uses CFU / mL to degrade residual organic matter in wastewater; the pH adjustment unit controls the pH of the purified wastewater between 6.5 and 7.5 with an adjustment accuracy of ±0.1; the online monitoring device integrates turbidity and COD monitoring sensors, with a data sampling frequency of 1 time / second. When the water turbidity is >10 NTU or COD is >50 mg / L, the bypass treatment is automatically started.

7. The efficient continuous cleaning system for waste PET bottle flakes used for recycling polyester staple fibers according to claim 6, characterized in that: The biodegradation tank is equipped with a stirring device with a stirring speed of 60-80 r / min to ensure sufficient contact between the microbial community and the wastewater. The bypass treatment uses an activated carbon adsorption device and an ultraviolet disinfection device. The adsorption capacity of the activated carbon adsorption device is ≥80 mg / g, and the power of the ultraviolet disinfection device is 30-50W with a disinfection time of 10-15s to ensure that the wastewater after bypass treatment meets the recycling standards. The pH adjustment unit uses an automatic dosing device with dilute sulfuric acid or dilute sodium hydroxide solution as the reagent, and the dosing accuracy is ±0.01L / min.

8. The efficient continuous cleaning system for waste PET bottle flakes used for recycling polyester staple fibers according to claim 1, characterized in that: The precision sorting module employs a combined structure of an electrostatic separator and a near-infrared spectral separator. The electrostatic separator features an adjustable high-voltage electric field of 10-20kV, with a titanium alloy grid. It effectively separates PVC impurities of similar density but different materials from PET bottle flakes by utilizing the differences in the charging characteristics of different plastic materials in the high-voltage electric field. The near-infrared spectral separator has a detection wavelength range of 800-1200nm and performs rapid identification and sorting based on the molecular vibrational characteristic spectra of different plastic materials, with an identification accuracy of ≤0.1mm, rejecting bottle flakes with abnormal color and material. The dual sorting mechanism works synergistically.

9. The efficient continuous cleaning system for waste PET bottle flakes used for recycling polyester staple fibers according to claim 1, characterized in that: The AI ​​visual recognition + multi-sensor fusion control system includes a visual recognition unit, a sensor network unit, an edge computing unit, and a control algorithm unit. The visual recognition unit, based on the YOLOv8 deep learning model and integrating a PyQt5 visualization interface, identifies the light / medium / heavy contamination level of the bottle flakes in real time and automatically switches the corresponding cleaning mode. The sensor network unit integrates five types of sensors: pH, conductivity, turbidity, temperature, and flow rate. Data is uploaded to the edge computing unit every second, with measurement accuracies of pH ±0.1, conductivity ±1μS / cm, turbidity ±0.1NTU, temperature ±0.1℃, and flow rate ±0.01m³. 3 / h; The control algorithm unit adopts fuzzy PID + genetic algorithm to dynamically adjust 12 parameters such as spray pressure, enzyme concentration, ultrasonic power, and water flow speed, so that the cleaning effect stability CV value is ≤3.5%; The system supports remote OTA upgrades and is compatible with PET bottle flakes from different sources; The error calculation formula of fuzzy PID control is: e(t) = yd(t) - y(t), In the formula: e(t) is the control error at time t, yd(t) is the target value of the cleaning effect at time t, including the amount of adhesive residue and turbidity, and y(t) is the actual value of the cleaning effect at time t.

10. The efficient continuous cleaning system for waste PET bottle flakes used for recycling polyester staple fibers according to claim 9, characterized in that: The genetic algorithm is used to optimize the parameters of a fuzzy PID controller. The objective function is the combined time and absolute error (ITAE), and the calculation formula is as follows: ， In the formula: ITAE(t) represents the combined time and absolute error, t represents the control time, and e(t) represents the control error at time t. The parameters of the genetic algorithm are set as follows: population size 50, mutation probability 0.2, crossover probability 0.9, and maximum number of iterations 500. This algorithm achieves optimal tuning of PID parameters and improves control accuracy.

Images