A waste polyester recycling intelligent process system and regeneration preparation method thereof

Abstract

The present invention belongs to the field of polyester recycling, and specifically discloses an intelligent process system for recycling waste polyester and a method for intelligently regenerating waste polyester materials using the system. The waste polyester is mainly recycled with high viscosity and stability through an online viscosity detector and a multi-stage viscosity control system, thereby avoiding the problem of limited application range caused by low melt viscosity or large fluctuation range of the recycled polyester material. The present invention conducts a comprehensive investigation on the parameter fluctuation range of the waste polyester recycling material, and upgrades and transforms the traditional equipment by using an automated algorithm. The equipment has a small investment and a high degree of automation, can realize stable regeneration and processing of the waste polyester material, effectively reduces the production cost, and has broad market application prospects.

Description

Technical Field

[0001] The invention belongs to the field of waste polyester recycling, and in particular relates to an intelligent process system for recycling waste polyester and a regeneration preparation method thereof. Background Art

[0002] The continuous accumulation of plastics in the natural environment causes ecological damage and is not in line with the sustainable development strategy. Under this policy background, the recycling and reuse of waste polyester materials is in line with the current resource-circulating economy. The more mature methods for recycling waste polyester materials include mechanical recycling, chemical recycling, and biodegradation. Among them, mechanical recycling of waste polyester materials has the advantages of low energy consumption, short cycle, and low cost. However, since waste polyester materials usually have problems such as a significant decrease in viscosity during processing and use, it is difficult to achieve high value-added applications of waste polyester materials obtained by mechanical recycling.

[0003] In response to this problem, there are currently existing patents that use the method of adding chain extenders to increase the viscosity of waste polyester materials. However, due to the complex sources of waste polyester materials, the purity, viscosity, and end group content of different batches of waste polyester materials vary greatly. If chain extenders are directly added to increase the viscosity of recycled polyester materials, there will be problems such as obvious fluctuations in the viscosity of different batches of products. Therefore, quantitative multi-level viscosity control of recycled polyester materials is conducive to the performance consistency of different batches of recycled products. Summary of the invention

[0004] In view of the technical problem of large fluctuations in the melt viscosity of waste polyester materials mechanically recycled in the prior art, the present application discloses an intelligent process system for recycling waste polyester and a regeneration preparation method thereof, which aims to monitor and control the real-time melt viscosity of the recycled product based on an online viscosity and additive feeding instrument, thereby achieving control of the melt viscosity stability of the recycled polyester material, and finally achieving the regeneration of a polyester material with high viscosity and melt stability through drawing, air cooling, and granulation. The present invention can reduce the viscosity fluctuation of the recycled polyester material, help reproduce the performance of different batches of products, and is of great significance for downstream processing and the application of recycled polyester materials.

[0005] In a first aspect, the present invention provides an intelligent process system for recycling waste polyester, comprising a twin-screw extruder, a first online viscometer, an automatic feeder, a second online viscometer, a control center and a granulation device, wherein the inlet of the twin-screw extruder is connected to the feed port of the waste polyester, and the outlet thereof is connected to the granulation device;

[0006] Installing the first online viscometer at the inlet of the twin-screw extruder;

[0007] Installing the second online viscometer at the outlet of the twin-screw extruder;

[0008] Installing a first control valve between the twin-screw extruder inlet and the waste polyester feed port;

[0009] A second control valve is installed between the twin-screw extruder outlet and the granulation device;

[0010] The automatic feeder is installed on the side wall of the twin-screw extruder and is used to add additives into the twin-screw extruder;

[0011] The control center is communicatively connected with the output motor of the twin-screw extruder, the first online viscometer, the second online viscometer, the first control valve, the second control valve and the automatic feeder;

[0012] The control center receives the first melt viscosity value of the first viscometer, calculates the type and amount of the additive according to the in-situ additive addition algorithm, controls the automatic feeder to add the additive, and adjusts the viscosity;

[0013] The control center receives a first melt viscosity value of the first online viscometer and a second melt viscosity value of the second online viscometer, and controls the opening and closing of the first control valve and the second control valve and the direction of rotation of the output motor according to a target viscosity accuracy deviation value algorithm.

[0014] Furthermore, the algorithm for adding additives in situ is:

[0015] (1) Calculate the type of additives added:

[0016] When the absolute value of the difference between the target viscosity and the first melt viscosity value is less than or equal to 0.005 dL / g, no additive is added;

[0017] When the absolute value of the difference between the target viscosity and the first melt viscosity value is greater than 0.005 dL / g, and the target viscosity> the first melt viscosity value, the type of additive added is a chain extender; when the absolute value of the difference between the target viscosity and the first melt viscosity value is greater than 0.005 dL / g, and the target viscosity< the first melt viscosity value, the type of additive added is a plasticizer;

[0018] (2) Calculate the amount of additives to be added:

[0019] When the absolute value of the difference between the target viscosity and the second melt viscosity is not less than 0.1 dL / g, the amount of additive required within one melt cycle is 0.5 wt%, and the addition rate is calculated using the following formula:

[0020] The unit is g / min;

[0021] When the absolute value of the difference between the target viscosity and the second melt viscosity is in the range of 0.01-0.1 dL / g (excluding the endpoint), the amount of additive required within one melt cycle is 0.1 wt%, and the addition rate is calculated using the following formula:

[0022] The unit is g / min;

[0023] When the absolute value of the difference between the target viscosity and the second melt viscosity is in the range of 0.005-0.01 dL / g (excluding the endpoint), the amount of additive required within one melt cycle is 0.01wt%, and the addition rate is calculated using the following formula:

[0024] The unit is g / min;

[0025] The melt cycle refers to the melt processing process of the twin-screw extruder within the duration of one cycle.

[0026] The duration of one melt cycle is The unit is min;

[0027] Where W a is the mass of additives required for one melt cycle, in g / min, L is the length of the processing zone of the twin-screw extruder, in cm, L s is the pitch length of the twin-screw extruder, in cm / rad, W is the capacity of the twin-screw extruder within one cycle without melt circulation, in g, R ev is the speed of the twin-screw extruder, in rad / min.

[0028] Furthermore, the first online viscometer and the second online viscometer are for timed viscosity measurement, and the viscosity measurement cycle is the duration of one melt cycle.

[0029] Furthermore, the target viscosity accuracy deviation value algorithm is as follows: each time the control center receives the second melt viscosity value, the algorithm is started once; when the difference between the second melt viscosity value and the target viscosity is greater than 0.005dL / g, the control center executes closing of the first control valve and the second control valve, and the twin-screw extruder first rotates forward and then rotates reversely; when the difference between the second melt viscosity and the target viscosity is less than or equal to 0.005dL / g, the control center executes opening of the first control valve and the second control valve, and the twin-screw extruder rotates forward.

[0030] Furthermore, the first online viscometer and the second online viscometer measure melt viscosity simultaneously.

[0031] Furthermore, the reverse rotation time is at least 0.5-0.8 times of melt cycle time.

[0032] Furthermore, there are multiple automatic feeders, which are evenly installed on the side wall of the twin-screw extruder.

[0033] Furthermore, a filtering system is installed at the outlet of the twin-screw extruder.

[0034] In a second aspect, the present invention proposes an intelligent regeneration method for waste polyester materials, which specifically comprises the following steps:

[0035] S1. Melt blending: waste polyesters from different sources are sorted, sterilized, and crushed, and then directly added into a twin-screw extruder to obtain a recycled polyester melt;

[0036] S2, viscosity measurement: a first online viscometer measures the viscosity of the recycled polyester melt to obtain a first melt viscosity; a second online viscometer measures the recycled polyester melt to obtain a second melt viscosity;

[0037] S3, viscosity control and melt circulation judgment: the control center quantitatively adds additives according to the difference between the first melt viscosity and the target viscosity according to the in-situ additive addition algorithm, and controls the operation of the equipment according to the target viscosity accuracy deviation algorithm, specifically;

[0038] When the difference between the second melt viscosity and the target viscosity is greater than 0.005 dL / g, the control center quantitatively adds additives according to the in-situ additive addition algorithm, executes the first control valve closing, the second control valve closing, and the twin-screw extruder first reverses and then rotates forward for a total of one timing cycle; the one timing cycle is the duration of one melt cycle of the twin-screw extruder;

[0039] When the difference between the second melt viscosity and the target viscosity is less than or equal to 0.005 dL / g, the control center opens the first control valve and the second control valve, and the twin-screw extruder rotates forward for one timing cycle, and the recycled polyester melt is transported out of the twin-screw extruder;

[0040] S4, extrusion granulation: the recycled polyester melt is transported to a granulation device for granulation to achieve the preparation of a recycled polyester material with stable viscosity.

[0041] Furthermore, before operation, the operating parameters of the twin-screw extruder are input into the control center, and the operating parameters are specifically: the length of the processing zone of the twin-screw extruder L, in cm, the pitch length of the twin-screw extruder L s , in cm / rad, the capacity of the twin-screw extruder within one cycle W, in g, the speed of the twin-screw extruder R ev , unit is rad / min, constant speed extrusion; target viscosity value, unit is dL / g, accuracy is 0.01.

[0042] Furthermore, in step S1, the waste polyester used is selected from at least one of polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene furandicarboxylate, polytrimethylene furandicarboxylate, polybutylene furandicarboxylate, poly(bisphenol A carbonate), polyarylate, polybutylene carbonate, polypropylene carbonate, polytrimethylene carbonate, polybutylene terephthalate-co-butylene carbonate, polybutylene terephthalate-co-butylene succinate, and polybutylene terephthalate-co-butylene adipate.

[0043] Furthermore, in step S1, the viscosity of the waste polyester is 0.2-2.0 dL / g.

[0044] Furthermore, in the steps S2 and S3, the chain extender used is selected from at least one of styrene-methacrylate glycidyl ester, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, pyromellitic dianhydride, phthalic anhydride, and 2,2'-bis(2-bisoxazoline).

[0045] Furthermore, in steps S2 and S3, the plasticizer used is selected from at least one of dimethyl phthalate, diethyl phthalate, butyl benzyl phthalate, di-n-butyl phthalate, di(2-ethyl)hexyl phthalate, di-n-octyl phthalate, diisononyl phthalate, diisodecyl phthalate, trioctyl phosphate, dioctyl adipate, and acetyl tributyl citrate.

[0046] Further, when step S3 is completed, the fluctuation range does not exceed 0.005 dL / g;

[0047] Furthermore, in step S4, the viscosity of the obtained recycled polyester does not exceed 2.0 dL / g.

[0048] Beneficial effects:

[0049] Based on the online viscosity detection system and the twin-screw extruder reversing circulation system, the mechanical recycling and manufacturing equipment of waste polyester materials was transformed, and an intelligent regeneration device for waste polyester materials was designed. The melt viscosity of the recycled polyester was regulated in multiple stages by automatically adding chain extenders or plasticizers in situ, and finally waste polyester materials with good performance consistency were obtained, which is of great significance for the stable processing of waste polyester materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the process flow of the present invention;

[0051] Figure 2 It is a control flow diagram of the present invention.

[0052] Among them: 1-recycled polyester feed port; 2-first control valve; 3-twin-screw extruder; 4-first online viscometer; 5-automatic feeder; 6-filtration system; 7-second online viscometer; 8-control center; 9-second control valve; 10-pelletizer. DETAILED DESCRIPTION

[0053] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0054] Example 1

[0055] The present invention provides an intelligent process system for recycling waste polyester, comprising a twin-screw extruder 3, a first online viscometer 4, an automatic feeder 5, a second online viscometer 7, a control center 8 and a granulation device 10, a first control valve 2, a second control valve 9 and the control center 8, the inlet of the twin-screw extruder is connected to a recycled polyester feed port 1, and the outlet is connected to the granulation device 10; the melt circulation system depends on the reversing rotation of the twin-screw extruder 3, and the outlet of the twin-screw extruder 3 is connected to a granulator 10;

[0056] A first online viscometer 4 is installed in the middle of the twin-screw extruder 3;

[0057] A second automatic viscometer 7 is installed at the outlet of the twin-screw extruder 3;

[0058] A first control valve 2 is installed between the inlet of the twin-screw extruder 3 and the waste polyester feed port 1;

[0059] An automatic feeder 5 is installed on the side wall of the twin-screw extruder 3;

[0060] The second control valve 9 is installed on the pipeline between the outlet of the twin-screw extruder 3 and the granulation device 10;

[0061] The control center 8 receives the real-time viscosity value of the first online viscometer 4, calculates and controls the automatic feeder 5 to add the additive to adjust the viscosity according to the in-situ additive addition algorithm;

[0062] The control center 8 receives the real-time viscosity value of the second online viscometer 7, and controls the first control valve 2, the second control valve 9 and the direction of the output motor of the twin-screw extruder 3 according to the target viscosity deviation value;

[0063] The control center 8 is in communication connection with the output motor of the twin-screw extruder 3, the first online viscometer 4, the second online viscometer 7, the first control valve 2, the second control valve 9 and the automatic feeder 5;

[0064] The control center 8 receives the first viscosity value of the first online viscometer 7, calculates the type and amount of the additive according to the in-situ additive addition algorithm, controls the automatic feeder 5 to add the additive, and adjusts the viscosity;

[0065] The control center 8 receives the first melt viscosity value of the first online viscometer 4 and the second melt viscosity value of the second online viscometer 7, and controls the opening and closing of the first control valve 2 and the second control valve 9 and the direction of the output motor according to the target viscosity accuracy deviation value algorithm.

[0066] Furthermore, the algorithm for adding additives in situ is:

[0067] When the absolute value of the difference between the target viscosity and the first melt viscosity value is less than or equal to 0.005 dL / g, no additive is added;

[0068] When the absolute value of the difference between the target viscosity and the first melt viscosity value is greater than 0.005 dL / g, and the target viscosity> the first melt viscosity value, the type of additive added is a chain extender; when the absolute value of the difference between the target viscosity and the first melt viscosity value is greater than 0.005 dL / g, and the target viscosity< the first melt viscosity value, the type of additive added is a plasticizer;

[0069] When the absolute value of the difference between the target viscosity and the second melt viscosity is not less than 0.1 dL / g, the amount of additive required for each melt cycle is 0.5wt%, and the addition rate is calculated using the following formula:

[0070] The unit is g / min;

[0071] When the absolute value of the difference between the target viscosity and the second melt viscosity is in the range of 0.01-0.1 dL / g, the amount of additive required for each melt cycle is 0.1 wt%, and the addition rate is calculated using the following formula:

[0072] The unit is g / min;

[0073] When the absolute value of the difference between the target viscosity and the second melt viscosity is in the range of 0.005-0.01 dL / g, the amount of additive required within one melt cycle is 0.01 wt%, and the addition rate is calculated using the following formula:

[0074] The unit is g / min;

[0075] The melt cycle refers to the melt processing process of the twin-screw extruder within the duration of one cycle.

[0076] The duration of one melt cycle is The unit is min;

[0077] Where W a is the mass of additives required for one melt cycle, in g / min, L is the length of the processing zone of the twin-screw extruder, in cm, L s is the pitch length of the twin-screw extruder, in cm / rad, W is the capacity of the twin-screw extruder within one cycle without melt circulation, in g, R ev is the speed of the twin-screw extruder, in rad / min.

[0078] Furthermore, the target viscosity accuracy deviation value algorithm is as follows: when the difference between the second melt viscosity and the target viscosity is greater than 0.005dL / g, the control center 8 executes the closing of the first control valve 2 and the second control valve 9, and the twin-screw extruder 3 rotates first in the reverse direction and then in the forward direction; when the difference between the second melt viscosity and the target viscosity is less than 0.005dL / g, the control center 8 executes the opening of the first control valve 2 and the second control valve 9, and the twin-screw extruder 3 rotates in the forward direction.

[0079] Furthermore, the first online viscometer 4 and the second online viscometer 7 are used for timed viscosity measurement, and the viscosity measurement cycle is the duration of one melt cycle.

[0080] Furthermore, there are multiple automatic feeders 5 , which are evenly installed on the side wall of the twin-screw extruder 3 .

[0081] Furthermore, a filtering system 6 is installed at the outlet of the twin-screw extruder 3 .

[0082] Example 2

[0083] This embodiment intends to prepare recycled polybutylene terephthalate-co-butylene adipate with a target viscosity of 1.50 dL / g. The length of the twin-screw processing zone used is 3m, the twin-screw pitch length is 1cm / rad, the production capacity is 30kg / h, the twin-screw speed is 300rad / min, and the time required for each melt cycle is 1min.

[0084] S1, melt blending: 0.5 kg of sterilized and crushed waste polybutylene terephthalate-co-butylene adipate is added to the feed port of the intelligent recycling system of waste polyester materials in Example 1, and enters the twin-screw extruder 3, and the processing temperature is 180° C.;

[0085] S2, viscosity measurement: a first online viscometer monitors the viscosity of the recycled polyester melt to obtain a first melt viscosity, and after filtering the polybutylene terephthalate-co-butylene adipate viscosity is 1.392 dL / g; a second online viscometer monitors the recycled polyester melt to obtain a second melt viscosity;

[0086] S3, viscosity control and melt circulation judgment: The amount of chain extender or plasticizer required for the first melt circulation is calculated as 0.5wt%, 2.5g of hexamethylene diisocyanate is added, and the viscosity of the obtained regenerated polybutylene terephthalate-co-butylene adipate is 1.441dL / g;

[0087] Then, according to the S3 additive adding algorithm, 0.5 g of hexamethylene diisocyanate was added, and the twin screw was rotated in the reverse and forward directions for one timing cycle; the resulting melt circulation viscosity was 1.490 dL / g;

[0088] 0.05 g of hexamethylene diisocyanate was added, and the viscosity of the obtained polybutylene terephthalate-co-butylene adipate was 1.498 dL / g after the twin screws rotated in reverse and forward directions;

[0089] At this time, the viscosity deviation value of polybutylene terephthalate-co-butylene adipate is 0.002 dL / g, and it enters the granulation equipment according to the algorithm;

[0090] S4, extrusion granulation: The recycled polybutylene terephthalate-co-butylene adipate melt obtained in S3 is passed through a granulation system to achieve stable high-viscosity product regeneration of waste polyester materials.

[0091] Example 3

[0092] This embodiment intends to prepare recycled polybutylene terephthalate-co-butylene adipate with a target viscosity of 1.50 dL / g. The length of the twin-screw processing zone used is 3m, the twin-screw pitch length is 1cm / rad, the production capacity is 30kg / h, the twin-screw speed is 300rad / min, and the time required for each melt cycle is 1min.

[0093] S1, melt blending: 0.5 kg of sterilized and crushed waste polybutylene terephthalate-co-butylene adipate is added to the feed port of the intelligent recycling system of waste polyester materials in Example 1, and enters the twin-screw extruder 3, and the processing temperature is 180° C.;

[0094] S2, viscosity measurement: a first online viscometer monitors the viscosity of the recycled polyester melt to obtain a first melt viscosity of 1.698 dL / g; a second online viscometer monitors the recycled polyester melt to obtain a second melt viscosity;

[0095] S3. Viscosity control and melt circulation judgment:

[0096] Based on the calculation that the amount of chain extender or plasticizer required for each melt cycle is 0.5wt%, 2.5g of dimethyl phthalate is added, and the viscosity of the obtained recycled polybutylene terephthalate-co-butylene adipate is 1.553dL / g;

[0097] 0.5 g of dimethyl phthalate was added, and the viscosity of the resulting melt-cycled polybutylene terephthalate-co-butylene adipate was 1.501 dL / g;

[0098] At this time, the viscosity deviation value of polybutylene terephthalate-co-butylene adipate is 0.001 dL / g, and it enters the granulation equipment according to the algorithm;

[0099] S4, extrusion granulation: The recycled polybutylene terephthalate-co-butylene adipate melt obtained in S3 is passed through a granulation system to achieve stable high-viscosity product regeneration of waste polyester materials.

[0100] Example 4

[0101] This embodiment intends to prepare recycled polybutylene terephthalate-co-butylene adipate with a target viscosity of 1.50 dL / g. The length of the twin-screw processing zone used is 3m, the twin-screw pitch length is 1cm / rad, the production capacity is 30kg / h, the twin-screw speed is 300rad / min, and the time required for each melt cycle is 1min.

[0102] S1, melt blending: 0.5 kg of sterilized and crushed waste polybutylene terephthalate-co-butylene adipate is added to the feed port of the intelligent recycling system of waste polyester materials in Example 1, and enters the twin-screw extruder 3, the processing temperature is 180° C., and the polybutylene terephthalate-co-butylene adipate with a viscosity of 1.007 dL / g is obtained through a filtration system;

[0103] S2, viscosity measurement: a first online viscometer monitors the viscosity of the recycled polyester melt to obtain a first melt viscosity of 1.007 dL / g; a second online viscometer monitors the recycled polyester melt to obtain a second melt viscosity;

[0104] S3. Viscosity control and melt circulation judgment:

[0105] Based on the calculation that the amount of chain extender or plasticizer required for each melt cycle is 0.5wt%, 2.5g of hexamethylene diisocyanate is added, and the viscosity of the obtained regenerated polybutylene terephthalate-co-butylene adipate is 1.229dL / g;

[0106] and adding 2.5 g of dimethyl phthalate, the viscosity of the resulting melt-cycled polybutylene terephthalate-co-butylene adipate was 1.334 dL / g;

[0107] and adding 2.5 g of hexamethylene diisocyanate, the viscosity of the resulting melt-cycled polybutylene terephthalate-co-butylene adipate was 1.477 dL / g;

[0108] 0.5 g of hexamethylene diisocyanate was added, and the viscosity of the resulting melt-cycled polybutylene terephthalate-co-butylene adipate was 1.511 dL / g;

[0109] 0.05 g of dimethyl phthalate was added, and the viscosity of the resulting melt-cycled polybutylene terephthalate-co-butylene adipate was 1.495 dL / g;

[0110] At this time, the viscosity deviation value of polybutylene terephthalate-co-butylene adipate is 0.005 dL / g, and it enters the granulation equipment according to the algorithm;

[0111] S4, extrusion granulation: The recycled polybutylene terephthalate-co-butylene adipate melt obtained in S3 is passed through a granulation system to achieve stable high-viscosity product regeneration of waste polyester materials.

[0112] Comparative Example 1 (Preparation of recycled polyester using a device without a control system and using a shear rate to control melt viscosity)

[0113] S1, melt blending: 5 kg of sterilized and crushed polyethylene terephthalate waste bottle flakes were added into a twin-screw extruder equipped with an online viscosity detector, the processing temperature was 260° C., and a polyethylene terephthalate co-melt with a viscosity of 0.682 dL / g was obtained through a reverse osmosis filtration system;

[0114] S2, viscosity control: the polyethylene terephthalate co-melt prepared in S1 is conveyed to the viscosity control section, and the viscosity of the regenerated polyethylene terephthalate obtained by twin-screw melt extrusion is 0.660 dL / g by increasing the shear rate;

[0115] S4, fiber-forming stage: the recycled polyethylene terephthalate melt obtained in S2 enters the spinning composite assembly through a metering pump, and undergoes fiber forming processes such as spinning, drawing, shaping, and curling to obtain polyethylene terephthalate filaments using recycled polyester as raw material, with a breakage rate of 11.6%.

[0116] Result analysis:

[0117] Compared with Comparative Example 1, Examples 1-3 are as follows: Based on an online viscosity detector and a multi-stage circulation control system, the viscosity of the recycled polyester melt is monitored in real time, and the viscosity of the polyester melt is regulated by automatically adding chain extenders or plasticizers in situ to improve the stability of the recycled polyester melt, which helps to regenerate high-viscosity waste polyester materials and is of great significance for the downstream stability processing of waste polyester materials.

[0118] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. An intelligent process system for recycling waste polyester, characterized in that: It includes a twin-screw extruder, a first online viscometer, an automatic feeder, a second online viscometer, a control center and a granulation device, wherein the inlet of the twin-screw extruder is connected to the feed port of the waste polyester, and the outlet thereof is connected to the granulation device; Installing the first online viscometer at the inlet of the twin-screw extruder; Installing the second online viscometer at the outlet of the twin-screw extruder; Installing a first control valve between the twin-screw extruder inlet and the waste polyester feed port; A second control valve is installed between the twin-screw extruder outlet and the granulation device; The automatic feeder is installed on the side wall of the twin-screw extruder; The control center is communicatively connected with the output motor of the twin-screw extruder, the first online viscometer, the second online viscometer, the first control valve, the second control valve and the automatic feeder; The control center receives the first melt viscosity value of the first viscometer, calculates the type and amount of the additive according to the in-situ additive addition algorithm, controls the automatic feeder to add the additive, and adjusts the viscosity; The control center receives a first melt viscosity value of the first online viscometer and a second melt viscosity value of the second online viscometer, and controls the opening and closing of the first control valve and the second control valve and the direction of the output motor according to a target viscosity accuracy deviation value algorithm; The algorithm for adding additives in situ is: (1) Calculate the type of additives added: When the absolute value of the difference between the target viscosity and the first melt viscosity value is less than or equal to 0.005 dL / g, no additive is added; When the absolute value of the difference between the target viscosity and the first melt viscosity value is greater than 0.005 dL / g, and the target viscosity is greater than the first melt viscosity value, the type of additive added is a chain extender; When the absolute value of the difference between the target viscosity and the first melt viscosity value is greater than 0.005 dL / g, and the target viscosity is less than the first melt viscosity value, the type of additive added is a plasticizer; (2) Calculate the amount of additives to be added: When the absolute value of the difference between the target viscosity and the second melt viscosity is not less than 0.1 dL / g, the amount of additive required within one melt cycle is 0.5 wt%, and the addition rate is calculated using the following formula: The unit is g / min; When the absolute value of the difference between the target viscosity and the second melt viscosity is in the range of 0.01-0.1 dL / g, the amount of additive required within one melt cycle is 0.1 wt%, and the addition rate is calculated using the following formula: The unit is g / min; When the absolute value of the difference between the target viscosity and the second melt viscosity is in the range of 0.005-0.01 dL / g, the amount of additive required within one melt cycle is 0.01 wt%, and the addition rate is calculated using the following formula: The unit is g / min; Where W a is the mass of additives required for one melt cycle, in g / min, L is the length of the processing zone of the twin-screw extruder, in cm, L s is the pitch length of the twin-screw extruder, in cm / rad, W is the capacity of the twin-screw extruder within one cycle without melt circulation, in g, R ev is the speed of the twin-screw extruder, in rad / min; The melt cycle refers to the melt processing process of the twin-screw extruder within the duration of one cycle. The duration of one melt cycle is The unit is min; The target viscosity accuracy deviation value algorithm is as follows: each time the control center receives the second melt viscosity value, the algorithm is started once; when the difference between the second melt viscosity value and the target viscosity is greater than 0.005dL / g, the control center executes closing of the first control valve and the second control valve, and the twin-screw extruder first rotates forward and then rotates reversely; when the difference between the second melt viscosity and the target viscosity is less than or equal to 0.005dL / g, the control center executes opening of the first control valve and the second control valve, and the twin-screw extruder rotates forward.

2. The waste polyester recycling intelligent process system according to claim 1 is characterized in that: The first online viscometer and the second online viscometer are for timed viscosity measurement, and the viscosity measurement cycle is the duration of one melt cycle.

3. A method for intelligently regenerating waste polyester materials using the waste polyester recycling intelligent process system according to any one of claims 1-2, characterized in that: The following steps are involved: S1. Melt blending: waste polyesters from different sources are sorted, sterilized, and crushed, and then directly added into a twin-screw extruder to obtain a recycled polyester melt; S2, viscosity measurement: a first online viscometer measures the viscosity of the recycled polyester melt to obtain a first melt viscosity; a second online viscometer measures the recycled polyester melt to obtain a second melt viscosity; S3, viscosity control and melt circulation judgment: the control center quantitatively adds additives according to the difference between the first melt viscosity and the target viscosity according to the in-situ additive addition algorithm, and controls the operation of the equipment according to the target viscosity accuracy deviation algorithm, specifically; When the difference between the second melt viscosity and the target viscosity is greater than 0.005 dL / g, the control center quantitatively adds additives according to the in-situ additive addition algorithm, executes the first control valve closing, the second control valve closing, and the twin-screw extruder first reverses and then rotates forward for a total of one timing cycle; the one timing cycle is the duration of one melt cycle of the twin-screw extruder; When the difference between the second melt viscosity and the target viscosity is less than or equal to 0.005 dL / g, the control center opens the first control valve and the second control valve, and the twin-screw extruder rotates forward for one timing cycle, and the recycled polyester melt is transported out of the twin-screw extruder; S4, extrusion granulation: the recycled polyester melt is transported to a granulation device for granulation to achieve the preparation of a recycled polyester material with stable viscosity.

4. The method according to claim 3, characterized in that Before operation, the operating parameters of the twin-screw extruder are input into the control center. The operating parameters are as follows: the length of the processing zone of the twin-screw extruder L, in cm, the pitch length K of the twin-screw extruder s , in cm / rad, the capacity of the twin-screw extruder within one cycle W, in g, the speed of the twin-screw extruder R ev , the unit is rad / min, constant speed extrusion; Target viscosity value, in dL / g, with an accuracy of 0.

01.

5. The method according to claim 3, characterized in that: In the step S1, the waste polyester used is selected from at least one of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene furandicarboxylate, polypropylene furandicarboxylate, polybutylene furandicarboxylate, poly(bisphenol A carbonate), and polyarylate.

6. The method according to claim 3, characterized in that In the step S3, the chain extender used is selected from at least one of styrene-methacrylate glycidyl ester, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, pyromellitic dianhydride, phthalic anhydride, and 2,2'-bis(2-bisoxazoline).

7. The method according to claim 3, characterized in that In the step S3, the plasticizer used is selected from at least one of dimethyl phthalate, diethyl phthalate, butyl benzyl phthalate, di-n-butyl phthalate, di(2-ethyl)hexyl phthalate, di-n-octyl phthalate, diisononyl phthalate, diisodecyl phthalate, trioctyl phosphate, dioctyl adipate, and acetyl tributyl citrate.

8. The method according to claim 3, characterized in that When step S3 is completed, the fluctuation range does not exceed 0.005 dL / g.

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