Method for decolorizing and purifying by-product ethylene glycol in process of regenerating polyester by chemical method

Abstract

The invention discloses a method for decolorizing and purifying a by-product ethylene glycol in a process of regenerating polyester by a chemical method, which comprises the following steps: firstly, adding an adsorbent and an ethylene glycol solution to be treated together, fully stirring and uniformly mixing, then heating and activating the uniformly mixed solution, and finally, putting the treated ethylene glycol mixed solution into a rectification system, according to the method, the pre-adsorption of the adsorbent is innovatively combined with the vacuum distillation technology, efficient decoloration and purification of ethylene glycol are realized by improving the pretreatment means of the adsorbent and optimizing the process parameters such as the distillation temperature and the distillation reflux ratio, and the method has the advantages of good decoloration effect, high product purity and the like, and is suitable for industrial production. The quality and the economic value of the regenerated ethylene glycol can be obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic resource utilization and high-value recycling, and more specifically, to a method for decolorizing and purifying ethylene glycol, a byproduct in a chemically regenerated polyester process. Background Art

[0002] As global resource shortages and environmental pollution become increasingly severe, the management of plastic waste has become a focus of international attention. Among them, polyethylene terephthalate (PET), as an important plastic material, is widely used in packaging, fiber and other industrial fields. The treatment of PET waste poses a huge challenge to environmental protection and resource recycling. PET causes long-term harm to the ecological environment because it is difficult to degrade naturally, especially the pollution caused by accumulation in soil, ocean and air. Promoting the efficient recycling and regeneration of PET can not only alleviate the environmental pressure caused by plastic waste, but also realize the recycling of resources.

[0003] The recycling of PET is mainly divided into two methods: physical recycling and chemical recycling. Physical recycling is widely used due to its low cost, but the performance of its recycled materials will gradually decrease with the increase in the number of recycling times, and its application areas are greatly limited. Chemical recycling can completely depolymerize PET into monomers, and the product quality is equivalent to that of the original monomers. Among the many chemical regeneration technologies, the combined treatment method of PET glycol hydrolysis and glycolysis (chemical regeneration polyester method) has been industrialized and has become an important way to efficiently recycle PET. However, the treatment of by-products in the chemical recycling process is still one of the key challenges restricting its further development. Taking glycol hydrolysis as an example, the by-product EG (ethylene glycol) usually contains a variety of complex impurities, such as dyes, additives and other raw material residues. These impurities not only significantly reduce the purity and quality of EG (ethylene glycol), but also interfere with the subsequent reuse process, seriously affecting its recycling value.

[0004] The current industrial purification methods for colored EG (ethylene glycol) have many limitations in efficiency, decolorization effect and cost control. It is imperative to develop an efficient EG (ethylene glycol) decolorization and purification method. Summary of the invention

[0005] The purpose of the present invention is to solve the needs of the above-mentioned prior art and provide a method for decolorizing and purifying ethylene glycol, a by-product in the chemical regeneration of polyester. The present invention innovatively combines adsorbent pre-adsorption with vacuum distillation technology, improves adsorbent pretreatment methods, optimizes process parameters such as distillation temperature and distillation reflux ratio, to achieve efficient decolorization and purification of ethylene glycol.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for decolorizing and purifying ethylene glycol, a byproduct of chemically regenerated polyester, comprises the following steps:

[0008] (a) adding the adsorbent and the ethylene glycol solution to be treated together and stirring them thoroughly;

[0009] (b) subjecting the mixed solution to a temperature-raising activation treatment;

[0010] (c) The treated ethylene glycol mixed liquid is put into a distillation system, which includes a distillation kettle and a distillation tower. The ethylene glycol mixed liquid is heated and distilled in the distillation system, and the ethylene glycol fraction is collected at the top of the distillation tower.

[0011] Furthermore, the adsorbent in step (a) includes activated carbon, molecular sieve, activated clay and clay mineral, the adsorbent solid particle size is 40 mesh to 200 mesh, the adsorbent dosage is 1 to 3wt% of the mass of the ethylene glycol solution to be treated, and the stirring and mixing time is ≥24h.

[0012] Furthermore, the mixed solution in step (b) is heated to 80-100° C. at a heating rate of 3-5° C. / min, kept for activation for 1-2 h, and then naturally cooled to room temperature.

[0013] Furthermore, the distillation kettle in step (c) is evacuated to -0.2 MPa.

[0014] Furthermore, the heating temperature of the distillation kettle in step (c) is controlled to 140-150°C, while the heating temperature of the distillation tower is controlled to 140-150°C, the height of the distillation tower is set to 1.2m, and the temperature of the top of the distillation tower is 120°C to 130°C.

[0015] Furthermore, the reflux ratio of the distillation operation in step (c) is set at 1:1 to 1:3, and the distillation time is 3 to 5 hours.

[0016] The stirring and mixing operation of the adsorbent and the ethylene glycol solution to be treated in step (a) is carried out in a mixing and stirring device, which includes a stirring platform, a lifting mechanism and a barrel cover element. A material barrel is placed on the stirring platform, and the adsorbent and the ethylene glycol solution to be treated can be placed in the material barrel. The lifting mechanism is installed on the stirring platform. The lifting mechanism includes a lifting column installed vertically, and a crossbeam is fixedly installed on the top side of the lifting column. The barrel cover element is fixedly connected to the bottom of the crossbeam. The barrel cover element is installed with two symmetrically arranged stirring mechanisms. The barrel cover element can cover the top opening of the material barrel, and the two stirring mechanisms can extend into the material barrel.

[0017] Furthermore, the barrel cover element includes a main cover body, a rotating seat and a rotating power assembly. The main cover body can be sealed and connected to the top flange of the material barrel. The rotating seat is rotatably installed at the central position of the main cover body. The rotating power assembly is transmission-connected to the rotating seat. The rotating power assembly can drive the rotating seat to perform planar rotating motion. The two stirring mechanisms are installed and connected to the rotating seat. The rotating seat can carry the two stirring mechanisms to rotate together. A self-rotating drive seat is installed on the main cover body. The self-rotating drive seat is transmission-connected to the two stirring mechanisms. The two stirring mechanisms can achieve a self-rotating effect.

[0018] Furthermore, a power box is fixedly installed above the main cover body, and the power box cover is installed on the outside of the rotating drive seat. The rotary power assembly includes a motor and a belt shaft. The motor is fixedly installed in the power box, and a first bevel gear is installed at the output end of the motor. The belt shaft is vertically installed, and the bottom of the belt shaft is fixedly connected to the central position of the rotating seat. The top of the belt shaft is connected to a second bevel gear, and the first bevel gear and the second bevel gear are meshed with each other.

[0019] Furthermore, the self-rotating drive seat is an annular seat, and a circle of driving toothed belt is installed in the inner hole of the self-rotating drive seat. The stirring mechanism includes a stirring main shaft and a transmission gear. The stirring main shaft is vertically installed on the rotating seat, and the stirring main shaft is rotatably connected to the rotating seat. The transmission gear is fixedly connected to the top of the stirring main shaft, and the transmission gear is meshed with the driving toothed belt. A plurality of paddle groups are connected and installed along the length direction of the stirring main shaft.

[0020] The beneficial effects of the present invention are:

[0021] 1. By combining adsorbent pretreatment with vacuum distillation, efficient decolorization and purification of ethylene glycol is achieved, and the product purity can be increased from 89% to 98%;

[0022] 2. The amount of activated carbon in the adsorbent is only 1 / 3-1 / 5 of that in the traditional adsorption method, which significantly reduces the processing cost;

[0023] 3. Use mild vacuum distillation conditions to avoid thermal decomposition of ethylene glycol and improve product yield;

[0024] 4. The process is simple, easy to implement industrially, and has good application prospects;

[0025] 5. The present invention innovatively combines adsorbent pre-adsorption with vacuum distillation technology, and realizes efficient decolorization and purification of ethylene glycol by improving adsorbent pretreatment means and optimizing process parameters such as distillation temperature and distillation reflux ratio. The method of the present invention has the advantages of good decolorization effect and high product purity, and can significantly improve the quality and economic value of regenerated ethylene glycol. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of a process flow of a method for decolorizing and purifying ethylene glycol, a byproduct of a chemically regenerated polyester process in this embodiment;

[0027] Figure 2 Schematic diagram of the appearance structure of a mixing and stirring device in this embodiment;

[0028] Figure 3 It is a cross-sectional structural diagram of the interior of a material barrel and a barrel cover component of a mixing and stirring device in this embodiment;

[0029] Figure 4 This is a top view of the transmission structure of the position of the rotation drive seat of a mixing and stirring device in this embodiment.

[0030] Figure numerals: mixing platform 1, material barrel 11, lifting mechanism 2, lifting column 21, crossbeam 22, barrel cover element 3, main cover body 31, rotating seat 32, rotating power assembly 33, motor 331, first bevel gear 332, belt shaft 333, second bevel gear 334, self-rotating drive seat 34, driving toothed belt 341, power box 35, mixing mechanism 4, mixing main shaft 41, transmission gear 42, blade group 43. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] A method for decolorizing and purifying ethylene glycol, a byproduct of chemically regenerated polyester, such as Figure 1 As shown, the following steps are included:

[0033] (a) Add the adsorbent and the ethylene glycol solution to be treated together and stir and mix thoroughly. The adsorbent includes activated carbon, molecular sieve, activated clay and clay minerals. The adsorbent is mainly composed of activated carbon (accounting for 60-80%), and is compounded with activated clay, molecular sieve (10-20%), or clay minerals (10-20%) and other components. Activated carbon is used as a non-polar adsorbent mainly to remove organic matter and pigments; activated clay and other polar adsorbents are mainly used to remove polar impurities and moisture. This composite adsorbent system can achieve synergistic adsorption and purification of multiple impurities in ethylene glycol. The particle size of the adsorbent solid particles is 40 mesh to 200 mesh, and the amount of the adsorbent is 1 to 3wt% of the mass of the ethylene glycol solution to be treated. The stirring and mixing time is ≥24h;

[0034] (b) The mixed solution is heated to 80-100°C at a heating rate of 3-5°C / min, and the temperature is kept for 1-2 hours, followed by natural cooling to room temperature. The adsorbent can remove moisture and other volatile impurities in the adsorbent during the heating activation process, significantly increasing the specific surface area and porosity of the adsorbent, thereby enhancing its adsorption capacity for impurities in ethylene glycol. The adsorption capacity of the activated adsorbent for pigment substances can be increased by 30-50%;

[0035] (c) The treated ethylene glycol mixed liquid is put into a distillation system, which includes a distillation kettle and a distillation tower. The ethylene glycol mixed liquid is heated and distilled in the distillation system. The distillation kettle is evacuated to -0.2MPa, and the heating temperature of the distillation kettle is controlled to 140-150°C. At the same time, the heating temperature of the distillation tower is controlled at 140-150°C. The distillation tower adopts a packed distillation tower with a height of 1.2m. The filler is a stainless steel Raschig ring. The temperature at the top of the distillation tower is 120°C~ 130℃, the reflux ratio of the distillation operation is set at 1:1~1:3, the distillation time is 3~5h, and the vacuum distillation is used to separate low-boiling point and near-boiling point impurities. The ethylene glycol fraction can be collected at the top of the distillation tower. In the distillation system, the distillation kettle is equipped with a temperature-controllable electric heating jacket to control the heating temperature. The distillation tower provides sufficient gas-liquid mass transfer area. A condenser is installed on the top of the distillation tower. The top condenser device is provided with a discharge port, which is connected to a collecting bottle. The ethylene glycol fraction is collected by setting a flow control valve.

[0036] The method of the present invention adopts a combined process of "adsorption + distillation" to achieve graded removal of different types of impurities through the synergistic effect of adsorption and distillation. Among them, the adsorbent pretreatment mainly removes macromolecular dyes and polar impurities, and the vacuum distillation is used to separate low-boiling point and near-boiling point impurities, so as to finally obtain a regenerated ethylene glycol product with good decolorization effect and high product purity.

[0037] A mixing and stirring device is used in a method for decolorizing and purifying ethylene glycol, a byproduct of a chemically regenerated polyester process. The device is used in step (a) of the aforementioned method to stir and mix an adsorbent with an ethylene glycol solution to be treated to form a mixed solution. Figure 2-Figure 4As shown, a mixing and stirring device includes a stirring platform 1, a lifting mechanism 2 and a barrel cover element 3. A material barrel 11 is placed on the stirring platform 1, and an adsorbent and a glycol solution to be treated can be put into the material barrel 11. The lifting mechanism 2 is installed on the stirring platform 1. The lifting mechanism 2 includes a lifting column 21 installed vertically, and the lifting column 21 can realize vertical lifting movement. The vertical lifting drive mechanism of the lifting column 21 is a common prior art, and the present invention does not make a specific discussion. A crossbeam 22 is fixedly installed on the top side of the lifting column 21, and the crossbeam 22 rises and falls with the lifting column 21. The barrel cover element 3 is fixedly connected to the bottom of the crossbeam 22. The barrel cover element 3 is installed with two symmetrically arranged stirring mechanisms 4. The crossbeam 22 can carry the barrel cover element 3 down together. The barrel cover element 3 after descending can cover the top opening of the material barrel 11. The two stirring mechanisms 4 can extend into the material barrel 11, and the two stirring mechanisms 4 can form a sufficient mixing and stirring effect on the adsorbent and the glycol solution to be treated.

[0038] like Figure 3 As shown, the barrel cover element 3 includes a main cover body 31, a swivel seat 32 and a swivel power assembly 33. The main cover body 31 can be sealed and connected with the top flange of the material barrel 11. The swivel seat 32 is rotatably installed at the central position of the main cover body 31. The swivel power assembly 33 is transmission-connected with the swivel seat 32. The swivel power assembly 33 can drive the swivel seat 32 to perform a planar swivel motion (relative to the main cover body 31). Two stirring mechanisms 4 are installed and connected to the swivel seat 32. The two stirring mechanisms 4 can be regarded as a whole. The swivel seat 32 can carry the two stirring mechanisms 4 to rotate together to form a whole. In order to achieve the effect of stirring the solution, a self-rotating drive seat 34 is installed on the main cover body 31, and the self-rotating drive seat 34 is transmission-connected with the two stirring mechanisms 4. Driven by the self-rotating drive seat 34, the two stirring mechanisms 4 can also achieve the effect of independent rotation. Under the above-mentioned design, the stirring mechanisms 4 can rotate as a whole and can also rotate independently, which can form the effect of fully stirring the solution. There is a gap between the two stirring mechanisms 4, and they will not interfere with each other's movement. The self-rotation can also cause the formation of turbulence in the solution, which can significantly improve the mixing quality of the solution and the adsorption and purification effect of the adsorbent.

[0039] like Figure 3As shown, a power box 35 is fixedly installed above the main cover body 31, and the power box 35 cover is installed on the outer side of the rotation drive seat 34. The power box 35 is directly fixedly connected to the cross beam 22. The rotary power assembly 33 includes a motor 331 and a belt shaft 333. The motor 331 is fixedly installed in the power box 35. A first bevel gear 332 is installed at the output end of the motor 331, and the belt shaft 333 is installed upright. The bottom of the belt shaft 333 is fixedly connected to the central position of the rotating seat 32, and the top of the belt shaft 333 is connected to the second bevel gear 334. The first bevel gear 332 and the second bevel gear 334 are meshed with each other. After the motor 331 is started, the rotation effect of the belt shaft 333 is formed by the meshing relationship between the first bevel gear 332 and the second bevel gear 334. When the belt shaft 333 rotates, it can drive the rotating seat 32 connected to it to do a planar rotation motion, and the two stirring mechanisms 4 connected to the rotating seat 32 are driven to rotate together to stir the solution.

[0040] like Figure 3 and Figure 4 As shown, the self-rotating driving seat 34 is an annular seat, and a circle of driving toothed belt 341 is installed in the inner hole of the self-rotating driving seat 34. The stirring mechanism 4 includes a stirring main shaft 41 and a transmission gear 42. The stirring main shaft 41 is vertically installed on the rotating seat 32, and the stirring main shaft 41 is rotatably connected to the rotating seat 32. The transmission gear 42 is fixedly connected to the top of the stirring main shaft 41, and the transmission gear 42 is meshed with the driving toothed belt 341. The rotating seat 32 can drive the stirring mechanism 4 to rotate as a whole without affecting the self-rotation drive of the stirring main shaft 41. The self-rotating driving seat 34 is in a fixed position state. When the stirring mechanism 4 rotates as a whole, the transmission gear 42 on the stirring main shaft 41 will mesh and rotate with the driving toothed belt 341, thereby forming a self-rotation effect of the stirring main shaft 41. A plurality of paddle groups 43 are connected and installed along the length direction of the stirring main shaft 41. When the stirring main shaft 41 rotates, the paddle group 43 can be driven to rotate, thereby forming a further effect of stirring the solution.

[0041] In the step (a) of the present invention, a physical stirring and mixing method is used to improve the adsorption and purification effect of the adsorbent, and in the step (b), an activation and heating method is used to further improve the adsorption capacity of the adsorbent for pigment substances. With the combination of the two, the pretreatment effect of the adsorbent and the ethylene glycol solution to be treated is significantly improved, which helps to obtain a regenerated ethylene glycol product with good decolorization effect and high product purity.

[0042] In the present invention, the initial purity of the ethylene glycol to be treated is 85-89%.

[0043] Example 1: Colored ethylene glycol (dark yellow in color) with an initial purity of 89% was mixed with 100-mesh activated carbon in a mass ratio of 2wt%, and the mixture was mixed and treated at a constant temperature of 25°C for 24h. The mixture was heated to 90°C at a heating rate of 4°C / min, kept warm for 1.5h, and then naturally cooled to room temperature. The mixture after activation pretreatment was transferred to a distillation kettle, and a mechanical vacuum pump was used to evacuate to -0.2MPa. The temperature of the distillation kettle was raised to 140°C, and the heating temperature of the distillation tower was controlled to be 140°C. The tower top temperature was maintained at 120°C. The distillation tower used was a packed distillation tower with a height of 1.2m, and the packing was φ6×6mm stainless steel Raschig rings, and the filling factor was 320m 2 / m 3 , distillation was carried out at a reflux ratio of 1:1, the process lasted for 4 hours, and the top fraction was collected. After gas chromatography detection, the product purity reached 95%, and the color changed from yellow to transparent and slightly light yellow (≤5Hazen), reaching the industrial grade ethylene glycol use standard, and the measured product yield was 92%.

[0044] Example 2: The method of Example 1 was followed, except that the reflux ratio was adjusted to 1:2, and other conditions remained unchanged. After testing, the purity of the product was increased to 96%, the chromaticity was <5 Hazen, the product was transparent, and the product yield was measured to be 90%.

[0045] According to the comparative experiments of Example 1 and Example 2, it is found that a high reflux ratio can further improve the product quality, but will slightly reduce the product yield.

[0046] Example 3: The method of Example 1 was followed, and the reflux ratio was adjusted to 1:3, and other conditions remained unchanged. After testing, the purity of the product reached 98%, the chromaticity was less than 2 Hazen, the product was completely transparent, and the product yield was 88%.

[0047] According to the results of Example 3, further increasing the reflux ratio can obtain a product with higher purity, but the yield will be reduced accordingly.

[0048] Example 4: The amount of adsorbent was reduced to 1wt%, and other conditions were the same as in Example 1. After 4h distillation, the product purity was 93%, the chromaticity was 10Hazen, and it was light yellow. The product yield was 94%.

[0049] According to the results of Example 4, reducing the amount of adsorbent will affect the decolorization effect, but can increase the product yield.

[0050] Example 5: The method of Example 1 was followed to replace the main component of activated carbon in the adsorbent with an equal mass of 4A molecular sieve. The product purity was measured to be 94%, the chromaticity was 8 Hazen, and the product yield was 91%.

[0051] Example 6: The method of Example 1 was used to operate, the temperature of the distillation kettle and the heating temperature of the distillation tower were increased to 150°C, and the top temperature was increased to 130°C. The product purity was measured to be 95.5%, the chromaticity was 15 Hazen, and the product yield was 85%.

[0052] The results of Example 5 and Example 6 show that the colorimetric effect of the product is not good.

[0053] Example 7: The method of Example 1 was followed, and the mixing time of the adsorbent was extended to 48 hours. The purity of the product was measured to be 95.2%, and the chromaticity and yield were basically the same as those of Example 1.

[0054] According to the results of Example 7, further extending the mixing time of the adsorbent and the ethylene glycol solution to be treated does not help to improve the product quality.

[0055] According to the comparison of the above 7 groups of embodiments, the method of Embodiment 2 has the highest cost performance and is most suitable for industrial application.

[0056] Therefore, the process parameters of Example 2 were used to carry out industrial scale-up test (Example 8):

[0057] 1) Processing capacity: 500kg / batch;

[0058] 2) Specifications of distillation tower: diameter 300mm, height 1.2m;

[0059] 3) The filler type and packing density are the same as in Example 1;

[0060] 4) Distillation time: 5h.

[0061] The final measured product purity was 95.8%, the chromaticity was less than 5 Hazen, and the product yield was 89%.

[0062] The results of Example 8 show that the method of the present invention has industrial application capabilities and can produce high-quality regenerated ethylene glycol products.

[0063] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for decolorizing and purifying ethylene glycol, a byproduct of chemically regenerated polyester, characterized in that: The steps include: (a) adding the adsorbent and the ethylene glycol solution to be treated together and stirring them thoroughly; (b) subjecting the mixed solution to a temperature-raising activation treatment; (c) The treated ethylene glycol mixed liquid is put into a distillation system, which includes a distillation kettle and a distillation tower. The ethylene glycol mixed liquid is heated and distilled in the distillation system, and the ethylene glycol fraction is collected at the top of the distillation tower.

2. The method for decolorizing and purifying ethylene glycol, a byproduct of chemical polyester regeneration according to claim 1, is characterized in that: The adsorbent in step (a) includes activated carbon, molecular sieve, activated clay and clay mineral. The particle size of the adsorbent solid particles is 40 mesh to 200 mesh. The amount of the adsorbent is 1 to 3 wt% of the mass of the ethylene glycol solution to be treated. The stirring and mixing time is ≥ 24 hours.

3. The method for decolorizing and purifying ethylene glycol, a byproduct of chemical polyester regeneration according to claim 1, is characterized in that: The mixed solution in step (b) is heated to 80-100° C. at a heating rate of 3-5° C. / min, kept for activation for 1-2 hours, and then naturally cooled to room temperature.

4. The method for decolorizing and purifying ethylene glycol, a byproduct of chemically regenerated polyester, according to claim 1, characterized in that: The distillation kettle in step (c) is evacuated to -0.2 MPa.

5. The method for decolorizing and purifying ethylene glycol, a byproduct of chemically regenerated polyester, according to claim 1, characterized in that: The heating temperature of the distillation kettle in step (c) is controlled to 140-150°C, while the heating temperature of the distillation tower is controlled to 140-150°C, the height of the distillation tower is set to 1.2m, and the temperature of the top of the distillation tower is 120°C to 130°C.

6. The method for decolorizing and purifying ethylene glycol, a byproduct of chemical polyester regeneration according to claim 1, characterized in that: The reflux ratio of the distillation operation in step (c) is set at 1:1 to 1:3, and the distillation time is 3 to 5 hours.

7. The method for decolorizing and purifying ethylene glycol, a byproduct of chemically regenerated polyester, according to claim 1, characterized in that: The stirring and mixing operation of the adsorbent and the ethylene glycol solution to be treated in step (a) is carried out in a mixing and stirring device, the mixing and stirring device comprising a stirring platform (1), a lifting mechanism (2) and a barrel cover element (3), a material barrel (11) is placed on the stirring platform (1), the adsorbent and the ethylene glycol solution to be treated can be placed in the material barrel (11), the lifting mechanism (2) is installed on the stirring platform (1), the lifting mechanism (2) comprises a lifting column (21) installed vertically, a crossbeam (22) is fixedly installed on the top side of the lifting column (21), the barrel cover element (3) is fixedly connected to the bottom of the crossbeam (22), the barrel cover element (3) is installed with two symmetrically arranged stirring mechanisms (4), the barrel cover element (3) can cover the top opening of the material barrel (11), and the two stirring mechanisms (4) can extend into the material barrel (11).

8. The method for decolorizing and purifying ethylene glycol, a byproduct of chemically regenerated polyester, according to claim 7, characterized in that: The barrel cover element (3) comprises a main cover body (31), a rotating seat (32) and a rotating power assembly (33); the main cover body (31) can be sealed and connected to the top flange of the material barrel (11); the rotating seat (32) is rotatably installed at the central position of the main cover body (31); the rotating power assembly (33) is transmission-connected to the rotating seat (32); the rotating power assembly (33) can drive the rotating seat (32) to perform a planar rotating motion; the two stirring mechanisms (4) are installed and connected to the rotating seat (32); the two stirring mechanisms (4) can be carried to rotate together through the rotating seat (32); a self-rotating drive seat (34) is installed on the main cover body (31); the self-rotating drive seat (34) is transmission-connected to the two stirring mechanisms (4); the two stirring mechanisms (4) can achieve a self-rotating effect.

9. The method for decolorizing and purifying ethylene glycol, a byproduct of chemical polyester regeneration according to claim 8, characterized in that: A power box (35) is fixedly installed above the main cover body (31), and the power box (35) is covered on the outside of the rotation drive seat (34). The rotary power assembly (33) comprises a motor (331) and a belt shaft (333). The motor (331) is fixedly installed in the power box (35). A first bevel gear (332) is installed at the output end of the motor (331). The belt shaft (333) is installed vertically, and the bottom of the belt shaft (333) is fixedly connected to the central position of the rotary seat (32). The top of the belt shaft (333) is connected to a second bevel gear (334), and the first bevel gear (332) and the second bevel gear (334) are meshed with each other.

10. The method for decolorizing and purifying ethylene glycol, a byproduct of chemically regenerated polyester, according to claim 8, characterized in that: The self-rotating driving seat (34) is an annular seat, and a circle of driving toothed belt (341) is installed in the inner hole of the self-rotating driving seat (34). The stirring mechanism (4) comprises a stirring main shaft (41) and a transmission gear (42). The stirring main shaft (41) is vertically installed on the rotating seat (32), and the stirring main shaft (41) is rotationally connected to the rotating seat (32). The transmission gear (42) is fixedly connected to the top of the stirring main shaft (41), and the transmission gear (42) is meshed with the driving toothed belt (341). A plurality of blade groups (43) are connected and installed along the length direction of the stirring main shaft (41).

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