Reprocessing method and system for base-catalyzed polymerized polyether polyol high-chroma material

Abstract

The invention belongs to the technical field of polyether polyol production, and discloses a recycling treatment method and system for a high-chroma material of base-catalyzed polymerized polyether polyol. The invention aims to solve the problems of resource waste, high environmental protection pressure or high product quality risk when high-chroma unqualified materials are treated in the prior art. The method comprises the following steps: collecting and homogenizing a high-chromaticity unqualified material, feeding the high-chromaticity unqualified material into a polymerization kettle according to the proportion of 8-15%, and sequentially polymerizing the high-chromaticity unqualified material with epoxypropane and ethylene oxide at 95-125 DEG C; treating by a neutralization system containing 95-98% of theoretical amount of adipic acid, carrying out vacuum dehydration, and carrying out 1-10 [mu] m precision filtration to remove colored impurities; the treated materials are mixed and recycled with main process materials according to the proportion of 5%-15%, and multi-node quality monitoring is matched. 100% resource utilization of unqualified materials is achieved, the chromaticity of the treated product reaches the standard, the performance is stable, the technology is matched with an existing device, technical improvement is easy and convenient, the production cost is reduced, and environmental protection is achieved.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization and intelligent sorting equipment technology, specifically to a method and system for the recycling and treatment of high-color materials from alkali-catalyzed polymerized polyether polyols. Background Technology

[0002] Polyether polyols, as an important class of polymer intermediates, are widely used in polyurethane foams, elastomers, adhesives, and other fields. Their quality directly affects the performance and appearance of downstream products. In the industrial production of polyether polyols, various factors, such as fluctuations in raw material purity, unstable catalyst activity, deviations from set ranges in process parameters (e.g., reaction temperature, system pressure, moisture content, oxygen content in the reaction system), or improper operation, can easily lead to excessive color in the product. This is typically manifested as an overly dark color with a color value greater than 50 Hazen. Such substandard products are referred to as high-color polyether polyol materials.

[0003] The generation of high-color polyether polyols not only wastes raw material resources but also directly increases production costs for enterprises, placing significant economic pressure on them. Research indicates that excessive color in polyether polyols mainly stems from oxidation and degradation reactions of the polyether molecular chains under high-temperature environments or the influence of catalyst residues, or the formation of colored byproducts such as conjugated olefins, aldehydes, and ketones. The presence of these colored substances leads to increased product color and is difficult to remove through simple treatment.

[0004] Currently, the industry's methods for handling such substandard polyether polyols with high color intensity have significant flaws, as detailed below: Downgrading: Selling substandard high-color materials as low-grade products at low prices can recover some costs, but it seriously reduces the economic benefits of the products and cannot meet the needs of high-end application scenarios. Scrap disposal: Directly discarding substandard materials not only wastes both resources and production costs, but also faces enormous pressure in environmentally friendly waste disposal, which is inconsistent with the development concept of green production. Simple mixing: A small amount of substandard material with high color intensity is directly mixed into qualified products in an attempt to reduce the color intensity through "dilution". This method is a common means used by some companies to control costs, but it has extremely high quality risks - the colored substances in the substandard material are not effectively removed, which can easily lead to the color intensity of the entire batch of qualified products being raised, causing large-scale quality accidents, and it cannot fundamentally solve the core problem of excessive color intensity.

[0005] In summary, existing processing technologies are unable to achieve efficient and stable treatment of high-color-content substandard polyether polyols. There is a lack of a technical solution that can specifically remove colored byproducts while ensuring the treated material meets performance standards and can be safely reused in the main production process. Therefore, developing an efficient, economical, and environmentally friendly processing technology that enables the resource utilization of high-color-content substandard polyether polyols has become an urgent technical challenge to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to address the deficiencies of the prior art by providing a method and system for the recycling of high-color materials from alkali-catalyzed polymerized polyether polyols, thereby solving the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for reprocessing high-color materials from alkali-catalyzed polymerized polyether polyols, comprising the following steps: S1: Pretreatment homogenization and reactive polymerization: Collect high-color unqualified polyether polyols from different batches into an unqualified tank for circulation and mixing, so that the color deviation of different sampling points of the mixed material is ≤5%, the viscosity fluctuation range is ≤8%, and the difference between potassium ion concentration detection points is ≤10%; then, feed the homogenized high-color material as the feed head into the polymerization reactor at a ratio of 8%-15%, circulate and heat to 95-125℃, then add propylene oxide at a ratio of 55%-85% for 5-9 hours of polymerization maturation, and finally add ethylene oxide at a ratio of 1%-7% for end-capping to complete the polymerization; S2: Neutralization and Filtration Separation: The polymerized material is fed into an existing neutralization vessel. Under moderate stirring conditions at 80-110℃, an adipic acid aqueous solution with a neutralization amount of 95-98% is added. After vacuum dehydration to remove moisture and low-boiling substances, the material is transferred to a filter feed tank. The neutralized and dehydrated material is heated to 140-143℃ using heating steam from the filter feed tank, and then fed into a candle filter with a filtration accuracy of 1-10μm. The initial filtration pressure is controlled at 0.1-0.4MPa. Filtration is carried out for 2-4 hours to form a filter cake with a thickness of 3-8cm. Colored impurities are removed through physical and chemical adsorption of the filter cake. The filter cake mainly consists of potassium salts generated during neutralization and carrier particles. S3: Recycled fusion: The filtered material is fed into an intermediate tank after polymerization and before refining, and mixed with the main process material at a mass ratio of 5% to 15%. The ratio is automatically adjusted through linkage between the mass flow meter and the DCS system. During the mixing process, multi-node quality monitoring ensures product qualification.

[0008] As a preferred technical solution of the present invention, the polymerization reactor in step S1 has a volume of 50~250m³, adopts an anchor or paddle agitator with a rotation speed of 30~100rpm, a motor power of 25~75kW and has a variable frequency speed regulation function.

[0009] As a preferred embodiment of the present invention, the temperature range of the cyclic heating in step S1 is 105~118℃, and the feed ratio of the high-color material is 10%-13%.

[0010] As a preferred technical solution of the present invention, after processing 5 to 8 batches, the candle filter in step S2 is backflushed with nitrogen at 0.4 to 0.6 MPa. When the filtration differential pressure ΔP > 0.5 MPa, a differential pressure alarm is triggered to prompt cleaning.

[0011] As a preferred technical solution of the present invention, the multi-node quality monitoring in step S3 includes: online detection of color at the outlet of the feed tank; online monitoring of color, viscosity and potassium ion content at the outlet of the filter; and sampling and detection of color, hydroxyl value and acid value every 1 hour after the remelting access point.

[0012] A system for recycling high-color polyether polyol materials using alkali-catalyzed polymerization, implementing the aforementioned recycling treatment method, comprises a defect tank, a polymerization reactor, a neutralization reactor, a filter feed tank, a candle filter, and an intermediate tank connected in sequence. The defect tank is connected to the polymerization reactor, the polymerization reactor to the neutralization reactor, the neutralization reactor to the filter feed tank, the filter feed tank to the candle filter, and the candle filter to the intermediate tank via pipelines. Each pipeline is equipped with a feed pump. The intermediate tank is connected to the main process material pipeline via a pipeline equipped with a mass flow meter, which is electrically connected to a DCS control system. The defect tank is used to collect and circulate the high-color defective material. The polymerization reactor is used to realize the polymerization reaction of the high-color material with propylene oxide and ethylene oxide. The neutralization reactor is connected to an adipic acid preparation system for neutralizing the material. The candle filter is used to filter and remove colored impurities. The intermediate tank is used to temporarily store the treated material and to achieve mixing and recycling with the main process material.

[0013] As a preferred embodiment of the present invention, the unqualified tank, polymerization reactor, neutralization reactor, candle filter and intermediate tank are all made of alkali-resistant stainless steel 316L.

[0014] As a preferred embodiment of the present invention, the feed tank outlet is equipped with an online colorimeter, and the filter outlet is equipped with an online monitoring device for color, viscosity and potassium ions.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. Significant color reduction effect and stable and reliable product quality: This invention, through precise control of the feed ratio of high-color materials (8%-15%), polymerization reaction temperature (95-125℃), and homogenization process parameters, combined with the synergistic effect of neutralization reaction and precision filtration, can effectively remove colored byproducts such as conjugated olefins, aldehydes, and ketones generated by the oxidation and degradation of polyether molecular chains. Verification by examples shows that even unqualified materials with an initial color of up to 180 Hazen can have their final product color reduced to below 32 Hazen after treatment, fully meeting the qualified standard of color ≤50 Hazen; moreover, the residual potassium ion content of the product is controlled within 18 ppm, and key performance indicators such as hydroxyl value and acid value are stable, with no color rebound during storage. This solves the core problem of existing simple remixing methods that easily lead to the entire batch of products exceeding standards and poor stability, and can fully adapt to the diverse performance requirements of downstream customized grades.

[0016] 2. 100% Resource Utilization Rate, Achieving a Win-Win Situation for Economic and Environmental Benefits: This invention achieves full recycling of high-color-ratio substandard polyether polyols, completely abandoning the traditional extensive methods of downgrading and scrapping, thus avoiding resource waste and environmental disposal pressure. On the one hand, substandard materials do not need to be sold off at low prices, significantly reducing production costs and economic losses; on the other hand, it eliminates waste emissions, aligning with the concept of green production and achieving the resource utilization goal of "turning waste into treasure," creating significant economic value and environmental benefits for enterprises.

[0017] 3. Strong process adaptability and simple technical transformation implementation: The remelting system of this invention can maximize the reuse of existing polyether production equipment such as neutralization kettles, adipic acid preparation systems, and candle filters. Only a small number of connecting pipelines and control components need to be added, resulting in a small amount of technical transformation work and low investment costs. The system uses a mass flow meter and a DCS system to control the remelting ratio in conjunction with multi-node quality monitoring (online color detection, sampling and testing of hydroxyl / acid value every 1 hour, etc.), which can achieve automated and continuous operation. It is easy to operate and highly controllable, without the need for major adjustments to the existing production process, and is easy to promote and apply in industrial production.

[0018] 4. Scientific parameter design, balancing processing efficiency and product performance: This invention, through pilot-scale testing, determined the optimal range of key parameters such as the high-color material feed ratio (preferably 10%-13%) and reaction temperature (preferably 105-118℃). This ensures the reaction rate between polyether and propylene oxide and ethylene oxide while avoiding side reactions such as chain transfer and isomerization, ensuring uniform molecular weight distribution and stable hydroxyl value of the product. Simultaneously, the incomplete neutralization design of adipic acid during neutralization (95-98% of the theoretical amount) prevents acidification of the polyether during storage and precisely controls the product's acid value. The combined design of filter cake adsorption and precision filtration further improves the removal efficiency of colored impurities, achieving dual optimization of processing efficiency and product performance.

[0019] 5. Wide range of applications and strong adaptability: The recycling technology of this invention is not affected by batch differences in high-color materials. Through a circulating homogenization process, the color deviation of different batches of substandard materials is ≤5%, viscosity fluctuation is ≤8%, and potassium ion distribution difference is ≤10%, which can be adapted to the production needs of various grades of alkali-catalyzed polyether polyols. Its polymerization reactor volume (50-250m³) can be matched with a processing capacity of 12-22.5 tons per batch, which can meet the intermittent processing of small and medium-sized plants, as well as the continuous operation of large production lines. The applicable scope covers polyether production enterprises of different sizes. Attached Figure Description

[0020] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a system diagram of the present invention. Detailed Implementation

[0021] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0022] like Figure 2 As shown, this invention provides a system for recycling high-color materials from alkali-catalyzed polymerization of polyether polyols, with the following specific configuration: The remelting system of this invention is modularly built based on existing polyether production equipment. The core equipment includes a defect tank, a polymerization reactor, a neutralization reactor, a filter feed tank, a candle filter, and an intermediate tank. Each piece of equipment is connected sequentially through pipelines and a feed pump, as detailed below: Non-conforming container: Made of 316L stainless steel, used to collect different batches of high-color non-conforming polyether polyols, equipped with a circulating stirring device to ensure material homogenization effect; Polymerization reactor: 100m³ capacity (suitable for processing 15 tons of non-conforming material per batch), made of 316L stainless steel, using an anchor-type agitator with a speed of 50rpm, a motor power of 45kW and frequency conversion speed regulation function, which can achieve precise temperature control and pressure adjustment within the range of 95-125℃. Neutralization reactor: The neutralization reactor of the existing production equipment is reused and equipped with an adipic acid preparation system, which can achieve temperature control of 80-110℃ and stirring function; Candle filter: Reuses existing precision filtration equipment with a filtration accuracy of 5μm, equipped with a nitrogen backflushing device and a differential pressure alarm system (set to trigger an alarm when ΔP>0.5MPa); Intermediate tank: Located at the process node after polymerization and before refining, it is used to temporarily store processed materials. Its outlet pipeline is equipped with a mass flow meter, which is electrically connected to the DCS control system to realize automatic adjustment of the remelting ratio. Filter feed tank: The filter feed tank of the existing device is reused and equipped with stirring and heating steam to ensure that the temperature of the neutralized material is between 130-150℃, which ensures both the continuity of filtration and the filtration efficiency.

[0023] Monitoring devices: An online colorimeter is installed at the outlet of the feed tank, and the filter outlet is equipped with online monitoring devices for color, viscosity and potassium ions to ensure that key indicators are controllable in real time.

[0024] like Figure 1 As shown, this invention provides a method for reprocessing high-color materials from alkali-catalyzed polymerized polyether polyols. The specific process steps for the reprocessing are as follows: S1: Pretreatment homogenization and reactive polymerization: Collect high-color unqualified polyether polyols from different batches into an unqualified tank for circulation and mixing, so that the color deviation of different sampling points of the mixed material is ≤5%, the viscosity fluctuation range is ≤8%, and the difference between potassium ion concentration detection points is ≤10%; then, feed the homogenized high-color material as the feed head into the polymerization reactor at a ratio of 8%-15%, circulate and heat to 95-125℃, then add propylene oxide at a ratio of 55%-85% for 5-9 hours of polymerization maturation, and finally add ethylene oxide at a ratio of 1%-7% for end-capping to complete the polymerization; S2: Neutralization and Filtration Separation: The polymerized material is fed into an existing neutralization vessel. Under moderate stirring conditions at 80-110℃, an adipic acid aqueous solution with a neutralization capacity of 95-98% is added. After vacuum dehydration to remove moisture and low-boiling substances, the material is fed into a candle filter with a filtration accuracy of 1-10μm. The initial filtration pressure is controlled at 0.1-0.4MPa. Filtration is carried out for 2-4 hours to form a filter cake with a thickness of 3-8cm. Colored impurities are removed through physical and chemical adsorption of the filter cake. The filter cake mainly consists of potassium salts generated during neutralization and carrier particles. S3: Recycled fusion: The filtered material is fed into an intermediate tank after polymerization and before refining, and mixed with the main process material at a mass ratio of 5% to 15%. The ratio is automatically adjusted through linkage between the mass flow meter and the DCS system. During the mixing process, multi-node quality monitoring ensures product qualification.

[0025] Example 1: High-color material feed ratio 8%; Preprocessing and homogenization: High-color, substandard polyether polyols with a color intensity of 120 Hazen, a hydroxyl value of 56 mg KOH / g, and potassium ion concentration of 280 ppm were collected into a substandard container. A circulating stirring device was started, controlling the circulation rate at 80 m³ / h and the homogenization temperature at 60℃, and homogenization was continued for 60 minutes. After homogenization, the following tests were conducted: color deviation at different sampling points 3% (≤5%), viscosity fluctuation range 5% (≤8%), and potassium ion concentration difference between detection points 7% (≤10%), meeting the homogenization effect judgment criteria.

[0026] Reactive polymerization: The homogenized high-color material was fed into the polymerization reactor at a rate of 8% as the feedstock. The reactor heating system was started, and the temperature was circulated and raised to 118°C. After reaching the set temperature, propylene oxide (color ≤ 10 Hazen, purity ≥ 99.97%, water content ≤ 0.015%, oxygen content ≤ 0.00001%) was added at a rate of 77% (relative to the total material mass). The reaction pressure was controlled at 115 kPa, and polymerization was carried out for 8 hours. After the polymerization was completed, ethylene oxide (color ≤ 5 Hazen, purity ≥ 99.95%, water content ≤ 0.01%, carbon dioxide content ≤ 0.001%) was added at a rate of 5% for end-capping, completing the polymerization process.

[0027] Neutralization, filtration, and separation: The polymerized material is fed into a neutralization vessel, with the internal temperature controlled at 109°C. Under moderate stirring, 8900 kg of demineralized water and 500 kg of solid adipic acid (96% of the theoretical neutralization amount) are added to the adipic acid preparation tank. After thorough stirring and dissolution, the mixture is introduced into the neutralization vessel to react with the material. After the reaction is complete, a vacuum dehydration system (3 kPa) is started and dehydration is continued for 150 minutes to remove water, unreacted monomers, and low-boiling substances from the system. The material is then transferred to a filter feed tank, where the heating steam from the filter feed tank is used to heat the neutralized and dehydrated material to 140°C. Subsequently, it is fed into a candle filter, with the initial filtration pressure controlled at 0.2 MPa and the filtration flow rate at 3 m³ / h. Filtration is continued for 3 hours to form a 4 cm thick filter cake. Colored impurities are removed through physical adsorption (the porous structure traps pigment molecules) and chemical adsorption (the interaction between the alkaline sites on the potassium salt surface and acidic pigment molecules).

[0028] Refining and Fusion: The filtered material is fed into an intermediate tank and mixed with the main process material at an 8% mass ratio via a mass flow meter linked to the DCS system. During the mixing process, multi-node quality monitoring ensures product qualification: online color measurement at the feed tank outlet is 35 Hazen; online monitoring at the filter outlet shows a color of 32 Hazen, viscosity fluctuation ≤4%, and potassium ion concentration of 12 ppm; after the remelting inlet, samples are taken and tested every hour. The final product has a color of 28 Hazen (≤50 Hazen), a hydroxyl value of 55 mg KOH / g, and an acid value that meet the requirements of the customized grade, thus being judged as a qualified product.

[0029] Example 2: High-color material feed ratio 15%; Preprocessing and homogenization: High-color, substandard polyether polyols with a color of 180 Hazen, a hydroxyl value of 58 mg KOH / g, and potassium ion concentration of 320 ppm were collected into a non-compliant container. A circulating stirrer was started, controlling the circulation rate at 95 m³ / h and the homogenization temperature at 65℃, and homogenization was continued for 90 min. Post-homogenization testing showed: color deviation of 4%, viscosity fluctuation range of 6%, and potassium ion concentration difference of 8%, meeting the homogenization standards.

[0030] Reactive polymerization: The homogenized high-color material was fed into the polymerization reactor at a ratio of 15%, and the temperature was increased to 120°C. Propylene oxide of the above specifications was added at a ratio of 70%, and the reaction pressure was controlled at 118 kPa. After polymerization and maturation for 7 hours, ethylene oxide of the above specifications was added at a ratio of 5% to end-cap the polymerization, thus completing the polymerization.

[0031] Neutralization, filtration, and separation: The polymer material was fed into a neutralization reactor at a controlled temperature of 112°C. 9300 kg of deionized water and 565 kg of solid adipic acid (97% of the theoretical neutralization amount) were added to an adipic acid preparation tank and dissolved before being introduced into the neutralization reactor for reaction. Subsequently, the material was dehydrated for 170 min under a vacuum of 2.6 kPa. After dehydration, the material was transferred to a filter feed tank. The neutralized and dehydrated material was heated to 143°C using the heating steam from the filter feed tank, and then fed into a candle filter. The initial filtration pressure was controlled at 0.25 MPa, the filtration flow rate at 2.5 m³ / h, and filtration continued for 3.5 hours to form a 6 cm thick filter cake.

[0032] Refining and Fusion: The treated material is mixed with the main process material at a mass ratio of 12%, and after multi-node quality monitoring: the filter outlet color is 42 Hazen and potassium ion is 18 ppm; the final product has a color of 32 Hazen, a hydroxyl value of 57 mg KOH / g, and an acid value that meets the standards and performance requirements of the customized grade.

[0033] Comparative example: Simple redemption method; Using a simple remixing method commonly used in existing technologies, high-color-denying material (color 180 Hazen, potassium ion 320 ppm) of the same specifications as in Example 2 was directly added to the qualified product at a ratio of 5%, without undergoing the pretreatment homogenization, reactive polymerization, and neutralization filtration steps of this invention. Test results showed that the mixed material had a color of 85 Hazen (exceeding the standard), and after 72 hours of storage, the color further increased to 110 Hazen, with potassium ion residue at 45 ppm (too high). The product stability was poor and could not meet the requirements of downstream applications.

[0034] Summary: Explanation of Key Process Parameter Control Homogenization effect control: By coordinating the adjustment of the circulating stirring rate, homogenization temperature and time, the color deviation of the mixed material is ensured to be ≤5%, viscosity fluctuation to be ≤8%, and potassium ion distribution difference to be ≤10%, thus ensuring the stability of the subsequent polymerization reaction. Polymerization parameter control: The proportion of high-color materials in the feed is controlled at 8%-15% (preferably 10%-13%) to avoid color rebound and ensure product performance; the reaction temperature is controlled at 95-125℃ (preferably 105-118℃) to balance reaction rate and product quality and prevent side reactions. Neutralization process control: The amount of adipic acid added is 95-98% of the theoretical neutralization amount, retaining a trace amount of alkalinity to prevent acidification of polyether during storage. At the same time, moisture is thoroughly removed through vacuum dehydration to avoid hydrolysis side reactions. Filtration system maintenance: After processing every 6 batches of material, backflush the filter cake with 0.5MPa nitrogen to ensure stable filter throughput. If the differential pressure exceeds 0.5MPa, stop the machine for cleaning in time to avoid clogging and affecting processing efficiency. Recycled material ratio control: By linking the mass flow meter with the DCS system, the mixing ratio of recycled materials and main process materials is precisely controlled at 5%-15%. Combined with multi-node quality monitoring, the final product quality is ensured to be stable.

[0035] Through the above specific embodiments, this invention achieves efficient treatment and full recycling of high-color-denying polyether polyols. The treated products meet quality standards, the process is compatible with existing production equipment, the operation is simple and the cost is controllable, making it suitable for large-scale industrial applications.

[0036] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for recycling high-color materials from alkali-catalyzed polymerized polyether polyols, characterized in that, Includes the following steps: S1: Pretreatment homogenization and reactive polymerization: Collect high-color unqualified polyether polyols from different batches into an unqualified tank for circulation and mixing, so that the color deviation of different sampling points of the mixed material is ≤5%, the viscosity fluctuation range is ≤8%, and the difference between potassium ion concentration detection points is ≤10%; then, feed the homogenized high-color material as the feed head into the polymerization reactor at a ratio of 8%-15%, circulate and heat to 95-125℃, then add propylene oxide at a ratio of 55%-85% for 5-9 hours of polymerization maturation, and finally add ethylene oxide at a ratio of 1%-7% for end-capping to complete the polymerization; S2: Neutralization and Filtration Separation: The polymerized material is fed into an existing neutralization vessel. Under moderate stirring conditions at 80-110℃, an adipic acid aqueous solution with a neutralization amount of 95-98% is added. After vacuum dehydration to remove moisture and low-boiling substances, the material is transferred to a filter feed tank. The neutralized and dehydrated material is heated to 140-143℃ using heating steam from the filter feed tank, and then fed into a candle filter with a filtration accuracy of 1-10μm. The initial filtration pressure is controlled at 0.1-0.4MPa. Filtration is carried out for 2-4 hours to form a filter cake with a thickness of 3-8cm. Colored impurities are removed through physical and chemical adsorption of the filter cake. The filter cake mainly consists of potassium salts generated during neutralization and carrier particles. S3: Recycled fusion: The filtered material is fed into an intermediate tank after polymerization and before refining, and mixed with the main process material at a mass ratio of 5% to 15%. The ratio is automatically adjusted through linkage between the mass flow meter and the DCS system. During the mixing process, multi-node quality monitoring ensures product qualification.

2. The recycling process according to claim 1, characterized in that, The polymerization reactor in step S1 has a volume of 50~250m³, uses an anchor or paddle agitator with a speed of 30~100rpm, and a motor power of 25~75kW with variable frequency speed control function.

3. The recycling process according to claim 1, characterized in that, The temperature range of the cyclic heating in step S1 is 105~118℃, and the feed ratio of the high-color material is 10%-13%.

4. The recycling process according to claim 1, characterized in that, After processing 5 to 8 batches, the candle filter in step S2 is backflushed with nitrogen at 0.4 to 0.6 MPa. When the filtration differential pressure ΔP > 0.5 MPa, a differential pressure alarm is triggered to prompt cleaning.

5. The recycling process according to claim 1, characterized in that, The multi-node quality monitoring in step S3 includes: online detection of color at the feed tank outlet; online monitoring of color, viscosity, and potassium ion content at the filter outlet; and sampling and testing of color, hydroxyl value, and acid value every hour after the remelting access point.

6. A recycling system for high-color polyether polyol materials catalyzed by alkali catalysis for recycling according to any one of claims 1-5, characterized in that, The system comprises, in sequence, a defect tank, a polymerization reactor, a neutralization reactor, a filter feed tank, a candle filter, and an intermediate tank. The defect tank is connected to the polymerization reactor, the polymerization reactor to the neutralization reactor, the neutralization reactor to the filter feed tank, the filter feed tank to the candle filter, and the candle filter to the intermediate tank via pipelines. Each pipeline is equipped with a feed pump. The intermediate tank is connected to the main process material pipeline via a pipeline equipped with a mass flow meter, which is electrically connected to the DCS control system. The defect tank is used to collect and circulate high-color defective materials. The polymerization reactor is used to realize the polymerization reaction of high-color materials with propylene oxide and ethylene oxide. The neutralization reactor is connected to an adipic acid preparation system for neutralizing the materials. The candle filter is used to filter and remove colored impurities. The intermediate tank is used to temporarily store the treated materials and to mix them with the main process materials for recycling.

7. The remelting system according to claim 6, characterized in that, The substandard tanks, polymerization reactors, neutralization reactors, candle filters, and intermediate tanks are all made of alkali-resistant 316L stainless steel.

8. The remelting system according to claim 6, characterized in that, The feed tank outlet is equipped with an online colorimeter, and the filter outlet is equipped with an online monitoring device for color, viscosity, and potassium ions.

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