Regenerated DMT decoloration recovery method and system

Abstract

The invention relates to a regenerated DMT decoloration recovery method and system, and the method comprises the following steps: a first purification tank, a second purification tank and a third purification tank are sequentially connected in series; dimethyl phthalate to be recycled is added into a first purification tank, a second purification tank and a third purification tank; monitoring the real-time temperatures of the dimethyl phthalate in the first purification tank, the second purification tank and the third purification tank, and heating the dimethyl phthalate in the first purification tank, the second purification tank and the third purification tank when the real-time temperatures of the dimethyl phthalate in the first purification tank, the second purification tank and the third purification tank are lower than a first preset value; compared with the prior art, the method has the advantages that the material flow direction is flexibly controlled according to the dimethyl phthalate purification degree; when the purifying agent of any one purification tank is replaced, normal work of the other two purification tanks is not affected, continuous decoloration can be achieved, efficiency can be improved, and dimethyl phthalate can be prevented from being converted into a solid state.

Description

Technical Field

[0001] This invention relates to the field of DMT (dimethyl phthalate) decolorization and recovery technology, and particularly to a method and system for regenerating DMT through decolorization and recovery. Background Technology

[0002] Polyethylene phthalate (PET) is commonly used in textiles, plastic bottles, and food packaging. However, with the widespread use of PET, the pollution problem caused by waste PET is becoming increasingly serious.

[0003] Currently, there are two main methods for recycling waste polyester textiles: physical and chemical. Compared to physical methods, chemical recycling produces higher quality recycled polyester with better product performance. However, chemical recycling also generates more byproducts and oligomers, resulting in lower purity DMT. Furthermore, most PET products contain dyes added during production, and these dyes are carried into the final product after depolymerization.

[0004] In the process of realizing this invention, the inventors discovered the following problems in the prior art:

[0005] Existing methods for regenerating DMT decolorization and recovery have poor decolorization effects and cannot control the flow of dimethyl phthalate according to the degree of purification. When the purification agent is replaced in the purification tank, it affects the normal operation of the purification tank. Summary of the Invention

[0006] Therefore, there is a need to provide a method and system for decolorizing and recovering regenerated DMT, which can solve the technical problems of poor decolorization effect of existing regenerated DMT decolorization and recovery methods, inability to control the flow of dimethyl phthalate according to the purification effect, and the impact on the normal operation of the purification tank when the purification agent is replaced.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a method for decolorizing and recovering regenerated DMT, comprising the following steps:

[0008] At least a first purification tank, a second purification tank, and a third purification tank are provided, and the first purification tank, the second purification tank, and the third purification tank are connected in series in the production sequence.

[0009] Dimethyl phthalate to be recovered is added to the first purification tank, the second purification tank, and the third purification tank;

[0010] Monitor the real-time temperature of dimethyl phthalate in the first purification tank, the second purification tank, and the third purification tank. When the real-time temperature of dimethyl phthalate in the first purification tank, the second purification tank, and the third purification tank is lower than the first preset value, heat the dimethyl phthalate in the first purification tank, the second purification tank, and the third purification tank.

[0011] To determine the degree of purification of dimethyl phthalate in the first purification tank, the purified dimethyl phthalate from the first purification tank is added to the second or third purification tank.

[0012] To determine the degree of purification of dimethyl phthalate in the second purification tank, add the purified dimethyl phthalate from the second purification tank to the third purification tank or the first purification tank.

[0013] Determine the degree of purification of dimethyl phthalate in the third purification tank, and add the purified product from the third purification tank into the first DMT filter or the first purification tank.

[0014] Unlike existing technologies, the technical solution of this application consists of a first purification tank, a second purification tank, and a third purification tank connected in series. The purification degree of dimethyl phthalate in the first purification tank is determined, and the purified dimethyl phthalate is added to either the second or third purification tank. The purification degree of dimethyl phthalate in the second purification tank is determined, and the purified dimethyl phthalate is added to either the third or first purification tank. The purification degree of dimethyl phthalate in the third purification tank is determined, and the purified dimethyl phthalate is added to either the first DMT filter or the first purification tank. This sequential series purification process... The tanks can perform multiple staged filtrations of dimethyl phthalate (DMT), resulting in better decolorization. Based on the degree of DMT purification, the flow direction of DMT in the first, second, and third purification tanks can be controlled, allowing for flexible material flow management. Changing the purifying agent in any one purification tank does not affect the normal operation of the remaining two tanks, enabling continuous decolorization and improving efficiency. The temperature of DMT in the purification tanks can be monitored in real time to prevent DMT from solidifying, ensuring that DMT is transported in liquid form within the decolorization system and improving DMT recovery efficiency.

[0015] As one embodiment of the present invention, the method further includes the following steps: after determining the degree of purification of dimethyl phthalate in the first purification tank, the purified dimethyl phthalate from the first purification tank is added to the first DMT filter.

[0016] After determining the degree of purification of dimethyl phthalate in the second purification tank, the purified dimethyl phthalate from the second purification tank is added to the first DMT filter;

[0017] Dimethyl phthalate filtered by the first DMT filter is then recycled into the pre-recovery tank.

[0018] In this way, after the dimethyl phthalate in the first purification tank and the second purification tank is purified, it can be directly added to the first DMT filter for filtration, and finally enters the recovery material tank for recovery. The material flow can be flexibly controlled, eliminating the need for step-by-step filtration and improving the dimethyl phthalate recovery efficiency.

[0019] In one embodiment of the present invention, the capacity of the first DMT filter is monitored. When the capacity of the first DMT filter exceeds a preset value, the dimethyl phthalate purified by the first purification tank, the second purification tank, and the third purification tank is added to the second DMT filter. The dimethyl phthalate filtered by the second DMT filter is then recycled into the recovery material tank.

[0020] Thus, when the capacity of the first DMT filter is detected to be overloaded, the second DMT filter can be activated for filtration without affecting the process of regenerating DMT decolorization and recycling.

[0021] As one embodiment of the present invention, the method further includes the following step: after determining the degree of purification of dimethyl phthalate in the third purification tank, the purified dimethyl phthalate from the third purification tank is added to the second purification tank.

[0022] In this way, dimethyl phthalate from the first purification tank can normally enter the second purification tank, or, depending on the purification status of dimethyl phthalate from the first purification tank, it can skip to the third purification tank; dimethyl phthalate from the second purification tank can normally enter the third purification tank, or, depending on the purification status of dimethyl phthalate from the second purification tank, it can be returned to the first purification tank for purification; dimethyl phthalate purified from the third purification tank can normally enter the first DMT filter, or it can be returned to either the first or second purification tank; the purification steps can be adjusted according to the degree of dimethyl phthalate purification in different purification tanks, flexibly controlling the flow of dimethyl phthalate and improving the recovery effect and efficiency of regenerated DMT decolorization and recovery.

[0023] As one embodiment of the present invention, the saturation level of the purifying agent in the first purification tank, the second purification tank, and the third purification tank is monitored respectively;

[0024] When the saturation level of the purifying agent in the first purification tank reaches the preset value, feeding into the first purification tank is stopped. The dimethyl phthalate to be recovered is added to the second or third purification tank. The purifying agent from the first purification tank is added to the purifying agent buffer tank. The real-time temperature of the purifying agent buffer tank is monitored. When the real-time temperature of the purifying agent buffer tank is lower than the first preset value, the purifying agent buffer tank is heated.

[0025] In this way, by monitoring the saturation level of the purifying agent in the first purification tank, when the saturation level of the purifying agent in the first purification tank reaches the preset value, the second or third purification tank can continue to be fed without affecting the purification of the second or third purification tank; by monitoring the real-time temperature of the purifying agent buffer tank, when the real-time temperature of the purifying agent buffer tank is lower than the first preset value, the purifying agent buffer tank can be heated to prevent the dimethyl phthalate in the purifying agent from solidifying when it gets cold, thus affecting the use of the purifying agent buffer tank.

[0026] In one embodiment of the present invention, when the saturation level of the purifying agent in the second purification tank or the third purification tank reaches a preset value, feeding into the second purification tank or the third purification tank is stopped, and the purifying agent in the second purification tank or the third purification tank is added into the purifying agent buffer tank.

[0027] Thus, when the saturation level of the purifying agent in the second or third purification tank reaches the preset value, feeding into the second or third purification tank can be suspended without affecting the operation of other purification tanks.

[0028] As one embodiment of the present invention, the purifying agent added to the purifying agent buffer tank is filtered to filter out dimethyl phthalate in the purifying agent.

[0029] Monitor the real-time temperature of dimethyl phthalate in the purification buffer tank. When the real-time temperature of dimethyl phthalate in the purification buffer tank is lower than the first preset value, heat the dimethyl phthalate in the purification buffer tank.

[0030] Thus, by monitoring the real-time temperature of dimethyl phthalate in the purification buffer tank, the dimethyl phthalate in the purification buffer tank is heated to keep the dimethyl phthalate in the purification buffer tank always in a liquid state. The purification buffer tank is equipped with a filter basket, through which the saturated purification agent is initially filtered to remove the liquid dimethyl phthalate. The top of the purification buffer tank is equipped with a steam inlet, and hot steam from above the filter basket forces out the remaining dimethyl phthalate adhering to the purification agent and filters it to the bottom of the filter basket, thus completing the filtration.

[0031] In one embodiment of the present invention, dimethyl phthalate in the purification buffer tank is recovered and added back into the first purification tank, the second purification tank, or the third purification tank.

[0032] In this way, the dimethyl phthalate filtered out by the purification buffer tank can be recycled back to the first, second, or third purification tank for reuse, thus avoiding waste of dimethyl phthalate.

[0033] In one embodiment of the present invention, valves are provided on all connecting pipes between the first purification tank, the second purification tank, and the third purification tank, and insulation jackets and heating units are provided on the inner side of all connecting pipes to make the temperature of the connecting pipes higher than a first preset value.

[0034] Thus, regenerated dimethyl phthalate is a special material. It is a highly fluid liquid above 141°C, but it also undergoes sublimation. Below 140°C, it rapidly transforms into a solid and condenses into lumps. All pipelines are equipped with heat-insulating jackets, and the inner side of the purification pipe is equipped with a heating coil to keep the temperature inside the pipeline and purification tank above 145°C, ensuring that dimethyl phthalate is transported in liquid form within the decolorization system. At the same time, a heating coil is installed at the top of the purification tank to prevent sublimated dimethyl phthalate from condensing at the top of the purification tank upon cooling.

[0035] To achieve the above objectives, in a second aspect, the inventors provide a regenerated DMT decolorization and recovery system for performing the regenerated DMT decolorization and recovery method as described in any of the above claims, comprising a first purification tank, a second purification tank, a third purification tank, a temperature monitoring unit, a controller, a heating unit, valves, and a first DMT filter;

[0036] The first purification tank, the second purification tank, and the third purification tank are connected in series, and valves are installed on all connecting pipes between the first purification tank, the second purification tank, and the third purification tank.

[0037] The temperature monitoring unit is used to monitor the real-time temperature of dimethyl phthalate in the first purification tank, the second purification tank, and the third purification tank.

[0038] The controller monitors the real-time temperature of dimethyl phthalate in the first purification tank, the second purification tank, and the third purification tank through the temperature monitoring unit, and controls the heating unit to heat the dimethyl phthalate in the first purification tank, the second purification tank, and the third purification tank.

[0039] The discharge ports of the first purification tank, the second purification tank, and the third purification tank are connected to the inlets of other purification tanks;

[0040] The discharge ports of the first purification tank, the second purification tank, and the third purification tank are connected to the first DMT filter.

[0041] Unlike existing technologies, the technical solution of this application utilizes a series of purification tanks to perform multiple stages of filtration on dimethyl phthalate, resulting in better decolorization. Based on the degree of dimethyl phthalate purification, the flow direction of dimethyl phthalate in the first, second, and third purification tanks can be controlled, allowing for flexible material flow management. Replacing the purifying agent in any one purification tank does not affect the normal operation of the remaining two tanks, enabling continuous decolorization and improving efficiency. The temperature of dimethyl phthalate in the purification tanks can be monitored in real time to prevent its conversion to a solid state, ensuring that dimethyl phthalate is transported in liquid form within the decolorization system and improving dimethyl phthalate recovery efficiency.

[0042] The above description of the invention is merely an overview of the technical solution of this application. In order to enable those skilled in the art to better understand the technical solution of this application and to implement it based on the description and drawings, and to make the above-mentioned objectives and other objectives, features and advantages of this application easier to understand, the following description is provided in conjunction with the specific embodiments and drawings of this application. Attached Figure Description

[0043] The accompanying drawings are only used to illustrate the principles, implementation methods, applications, features, and effects of specific embodiments of this application and other related content, and should not be considered as limitations on this application.

[0044] In the accompanying drawings of the instruction manual:

[0045] Figure 1 This is a schematic diagram of a method for decolorizing and recovering regenerated DMT according to an embodiment of this application;

[0046] Figure 2 This is a system block diagram of a regenerated DMT decolorization and recycling system according to an embodiment of this application;

[0047] Figure 3 This is a schematic diagram of the feeding of dimethyl phthalate to be recycled according to one embodiment of this application;

[0048] Figure 4 This is a schematic diagram of the material flow in the first purification tank, the second purification tank, and the third purification tank according to an embodiment of this application;

[0049] Figure 5 This is a schematic diagram of material return from the third purification tank according to an embodiment of this application;

[0050] Figure 6 This is a schematic diagram illustrating the material flow from the first purification tank to the third purification tank and the material return from the second purification tank, according to one embodiment of this application.

[0051] The reference numerals used in the above figures are explained as follows:

[0052] 1. Purification tank; 11. First inlet; 12. DMT feed pipe; 13. First outlet; 14. Second outlet; 15. First purification tank; 16. Second purification tank; 17. Third purification tank; 18. First pipe; 19. Second pipe; 20. Third pipe; 21. Fourth pipe; 22. Fifth pipe; 23. Sixth pipe; 24. Seventh pipe; 25. Eighth pipe.

[0053] 2. Purification reagent buffer tank,

[0054] 3. DMT filter,

[0055] 4. Material feed pipe,

[0056] 5. Valves,

[0057] 6. Hot water inlet pipe,

[0058] 7. Steam inlet pipe,

[0059] 8. Recycle material front tank. Detailed Implementation

[0060] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this application in detail, the following description, in conjunction with the listed specific embodiments and accompanying drawings, provides a detailed explanation. The embodiments described herein are merely illustrative of the technical solutions of this application and are therefore intended to limit the scope of protection of this application.

[0061] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0062] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0063] In the description of this application, the term "and / or" is used to describe a logical relationship between objects, indicating that three relationships can exist. For example, dimethyl phthalate and / or B means: dimethyl phthalate exists, B exists, and dimethyl phthalate and B exist simultaneously. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" logical relationship.

[0064] In this application, terms such as “first” and “second” are used only to distinguish one entity or operation from another, and do not necessarily require or imply any actual quantity, hierarchy or order relationship between these entities or operations.

[0065] Without further limitations, the use of terms such as “comprising,” “including,” “having,” or other similar open-ended expressions in this application is intended to cover non-exclusive inclusion, which does not exclude the presence of additional elements in a process, method, or product that includes the stated elements, such that a process, method, or product that includes a list of elements may include not only those defined elements but also other elements not expressly listed, or elements inherent to such a process, method, or product.

[0066] As understood in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceeding" are understood to exclude the stated number; expressions such as "above," "below," and "within" are understood to include the stated number. Furthermore, in the description of the embodiments in this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times," unless otherwise explicitly specified.

[0067] In the description of the embodiments of this application, the space-related expressions used, such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "vertical," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," indicate the orientation or positional relationship based on the orientation or positional relationship shown in the specific embodiments or drawings. They are only for the purpose of describing the specific embodiments of this application or for the reader's understanding, and do not indicate or imply that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0068] Unless otherwise expressly specified or limited, the terms "installation," "connection," "linking," "fixing," and "setting," as used in the description of the embodiments of this application, should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral arrangement; it can be a direct connection or an indirect connection through an intermediate medium; it can be a relationship of two components combined together, an interaction relationship between two components, or a connection within two structures. Those skilled in the art to which this application pertains can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0069] Existing methods for regenerating DMT decolorization and recovery have poor decolorization effects and cannot control the flow of dimethyl phthalate according to the degree of purification. When the purification agent is replaced in the purification tank, it affects the normal operation of the purification tank.

[0070] In view of this, embodiments of this application provide a method and system for decolorizing and recovering regenerated DMT, including the following steps: adding the dimethyl phthalate to be recovered into a first purification tank 15, a second purification tank 16, and a third purification tank 17; monitoring the real-time temperature of the dimethyl phthalate in the first purification tank 15, the second purification tank 16, and the third purification tank 17; when the real-time temperature of the dimethyl phthalate in the first purification tank 15, the second purification tank 16, and the third purification tank 17 is lower than a first preset value, and then... Dimethyl phthalate is heated, and the degree of purification of dimethyl phthalate in the first purification tank 15 is determined. The purified dimethyl phthalate in the first purification tank 15 is added to the second purification tank 16 or the third purification tank 17. The degree of purification of dimethyl phthalate in the second purification tank 16 is determined, and the purified dimethyl phthalate in the second purification tank 16 is added to the third purification tank 17 or the first purification tank 15. The degree of purification of dimethyl phthalate in the third purification tank 17 is determined, and the purified dimethyl phthalate in the third purification tank 17 is added to the first DMT filter or the first purification tank 15. Based on the degree of dimethyl phthalate purification, the flow direction of dimethyl phthalate in the first purification tank 15, the second purification tank 16, and the third purification tank 17 can be controlled, allowing for flexible control of the material flow. When the purifying agent is replaced in any one of the purification tanks, the normal operation of the remaining two purification tanks is not affected, enabling continuous decolorization and improving efficiency. The temperature of dimethyl phthalate in the purification tanks can be monitored in real time to prevent dimethyl phthalate from converting into a solid state, ensuring that dimethyl phthalate is transported in liquid form within the decolorization system and improving the dimethyl phthalate recovery efficiency.

[0071] According to some embodiments of this application, please refer to Figures 1 to 6 This embodiment relates to a method for decolorizing and recovering regenerated DMT, including the following steps:

[0072] At least a first purification tank 15, a second purification tank 16, and a third purification tank 17 are provided, and the first purification tank 15, the second purification tank 16, and the third purification tank 17 are connected in series in the production sequence.

[0073] Dimethyl phthalate to be recovered is added to the first purification tank 15, the second purification tank 16, and the third purification tank 17;

[0074] The real-time temperature of dimethyl phthalate in the first purification tank 15, the second purification tank 16, and the third purification tank 17 is monitored. When the real-time temperature of dimethyl phthalate in the first purification tank 15, the second purification tank 16, and the third purification tank 17 is lower than the first preset value, the dimethyl phthalate in the first purification tank 15, the second purification tank 16, and the third purification tank 17 is heated.

[0075] To determine the degree of purification of dimethyl phthalate in the first purification tank 15, the purified dimethyl phthalate in the first purification tank 15 is added to the second purification tank 16 or the third purification tank 17.

[0076] To determine the degree of purification of dimethyl phthalate in the second purification tank 16, the purified dimethyl phthalate in the second purification tank 16 is added to the third purification tank 17 or the first purification tank 15.

[0077] Determine the degree of purification of dimethyl phthalate in the third purification tank 17, and add the purified product from the third purification tank 17 into the first DMT filter or the first purification tank 15.

[0078] In this embodiment, under normal circumstances, dimethyl phthalate is purified and recovered sequentially through the first purification tank 15, the second purification tank 16, and the third purification tank 17. However, due to the fact that the concentration and parameters of the dimethyl phthalate in the feed cannot be guaranteed to be uniform each time, and that the purification agent in the first purification tank 15, the second purification tank 16, and the third purification tank 17 cannot be replaced in sequence, purification cannot be guaranteed to be carried out in this order, the flow direction of dimethyl phthalate can be adjusted according to the actual situation, the material flow direction can be flexibly controlled, and the normal operation of the remaining two purification tanks can be maintained when the purification agent in any one of the purification tanks is replaced, thus achieving continuous decolorization and improving efficiency.

[0079] Unlike existing technologies, the technical solution of this application consists of a first purification tank 15, a second purification tank 16, and a third purification tank 17 connected in series. The purification degree of dimethyl phthalate in the first purification tank 15 is determined, and the purified dimethyl phthalate from the first purification tank 15 is added to the second purification tank 16 or the third purification tank 17. The purification degree of dimethyl phthalate in the second purification tank 16 is determined, and the purified dimethyl phthalate from the second purification tank 16 is added to the third purification tank 17 or the first purification tank 15. The purification degree of dimethyl phthalate in the third purification tank 17 is determined, and the purified dimethyl phthalate from the third purification tank 17 is added to the first DMT filter or the first purification tank 15.

[0080] Thus, the sequentially connected purification tanks can perform multiple staged filtrations of dimethyl phthalate, resulting in better decolorization. Based on the degree of dimethyl phthalate purification, the flow direction of dimethyl phthalate in the first purification tank 15, the second purification tank 16, and the third purification tank 17 can be controlled, allowing for flexible control of the material flow. Replacing the purifying agent in any one purification tank does not affect the normal operation of the remaining two tanks, enabling continuous decolorization and improving efficiency. The temperature of dimethyl phthalate in the purification tanks can be monitored in real time to prevent the conversion of dimethyl phthalate into a solid state, ensuring that dimethyl phthalate is transported in liquid form within the decolorization system and improving dimethyl phthalate recovery efficiency.

[0081] According to some embodiments of this application, optionally, the following step is also included: after determining the degree of purification of dimethyl phthalate in the first purification tank 15, the purified dimethyl phthalate in the first purification tank 15 is added to the first DMT filter.

[0082] After determining the degree of purification of dimethyl phthalate in the second purification tank 16, the purified dimethyl phthalate in the second purification tank 16 is added to the first DMT filter;

[0083] Dimethyl phthalate filtered by the first DMT filter is fed into the recycling tank 8 for recovery.

[0084] Thus, after the dimethyl phthalate in the first purification tank 15 and the second purification tank 16 is purified, it can be directly added to the first DMT filter for filtration, and finally enters the recovery material tank 8 for recovery. The material flow can be flexibly controlled, eliminating the need for step-by-step filtration and improving the dimethyl phthalate recovery efficiency.

[0085] According to some embodiments of this application, optionally, the capacity of the first DMT filter is monitored. When the capacity of the first DMT filter exceeds a preset value, the dimethyl phthalate purified by the first purification tank 15, the second purification tank 16, and the third purification tank 17 is added to the second DMT filter. The dimethyl phthalate filtered by the second DMT filter enters the recovery material pre-tank 8 for recovery.

[0086] Thus, when the capacity of the first DMT filter is detected to be overloaded, the second DMT filter can be activated for filtration without affecting the process of regenerating DMT decolorization and recycling.

[0087] According to some embodiments of this application, optionally, the method further includes the following step: after determining the degree of purification of dimethyl phthalate in the third purification tank 17, the purified dimethyl phthalate in the third purification tank 17 is added to the second purification tank 16.

[0088] In this way, dimethyl phthalate from the first purification tank 15 can normally enter the second purification tank 16, or, depending on the purification status of dimethyl phthalate from the first purification tank 15, can skip to the third purification tank 17; dimethyl phthalate from the second purification tank 16 can normally enter the third purification tank 17, or, depending on the purification status of dimethyl phthalate from the second purification tank 16, can be returned to the first purification tank 15 for purification; dimethyl phthalate purified from the third purification tank 17 can normally enter the first DMT filter, or can be returned to the first purification tank 15 or the second purification tank 16; the purification steps can be adjusted according to the degree of dimethyl phthalate purification in different purification tanks, flexibly controlling the flow direction of dimethyl phthalate, and improving the recovery effect and efficiency of regenerated DMT decolorization and recovery.

[0089] According to some embodiments of this application, optionally, the saturation level of the purifying agent in the first purification tank 15, the second purification tank 16, and the third purification tank 17 is monitored respectively;

[0090] When the saturation level of the purifying agent in the first purification tank 15 reaches the preset value, feeding into the first purification tank 15 is stopped. The dimethyl phthalate to be recovered is added into the second purification tank 16 or the third purification tank 17. The purifying agent in the first purification tank 15 is added into the purifying agent buffer tank 2. The real-time temperature of the purifying agent buffer tank 2 is monitored. When the real-time temperature of the purifying agent buffer tank 2 is lower than the first preset value, the purifying agent buffer tank 2 is heated.

[0091] In this way, by monitoring the saturation level of the purifying agent in the first purification tank 15, when the saturation level of the purifying agent in the first purification tank 15 reaches the preset value, the second purification tank 16 or the third purification tank 17 can continue to be fed without affecting the purification of the second purification tank 16 or the third purification tank 17; by monitoring the real-time temperature of the purifying agent buffer tank 2, when the real-time temperature of the purifying agent buffer tank 2 is lower than the first preset value, the purifying agent buffer tank 2 can be heated to prevent the dimethyl phthalate in the purifying agent from solidifying when it is cooled, thus affecting the use of the purifying agent buffer tank 2.

[0092] According to some embodiments of this application, optionally, when the saturation level of the purifying agent in the second purification tank 16 or the third purification tank 17 reaches a preset value, feeding into the second purification tank 16 or the third purification tank 17 is suspended, and the purifying agent in the second purification tank 16 or the third purification tank 17 is added into the purifying agent buffer tank 2.

[0093] Thus, when the saturation level of the purifying agent in the second purification tank 16 or the third purification tank 17 reaches the preset value, feeding into the second purification tank 16 or the third purification tank 17 can be suspended without affecting the operation of other purification tanks.

[0094] According to some embodiments of this application, optionally, the purifying agent added to the purifying agent buffer tank 2 is filtered to filter out dimethyl phthalate in the purifying agent;

[0095] Monitor the real-time temperature of dimethyl phthalate in the purifier buffer tank 2. When the real-time temperature of dimethyl phthalate in the purifier buffer tank 2 is lower than the first preset value, heat the dimethyl phthalate in the purifier buffer tank 2.

[0096] Thus, by monitoring the real-time temperature of dimethyl phthalate in the purifying agent buffer tank 2, the dimethyl phthalate in the purifying agent buffer tank 2 is heated to keep the dimethyl phthalate in the purifying agent buffer tank 2 always in a liquid state. The purifying agent buffer tank 2 is equipped with a filter basket, and the saturated purifying agent is filtered through the filter basket to initially filter out the liquid dimethyl phthalate. The top of the purifying agent buffer tank 2 is equipped with a steam inlet, and the hot steam from above the filter basket forces out the remaining dimethyl phthalate attached to the purifying agent and filters it to the bottom of the filter basket, thus completing the filtration.

[0097] According to some embodiments of this application, optionally, the dimethyl phthalate in the purification buffer tank 2 is recovered and re-added into the first purification tank 15, the second purification tank 16, or the third purification tank 17.

[0098] In this way, the dimethyl phthalate filtered out by the purification buffer tank 2 can be recycled back to the first purification tank 15, the second purification tank 16, or the third purification tank 17 for reuse, thus avoiding waste of dimethyl phthalate.

[0099] According to some embodiments of this application, optionally, valves are provided on all connecting pipes between the first purification tank 15, the second purification tank 16, and the third purification tank 17, and heat insulation jackets and heating units are provided on the inner side of all connecting pipes, so that the temperature of the connecting pipes is higher than a first preset value.

[0100] Thus, regenerated dimethyl phthalate is a special material. It is a highly fluid liquid above 141°C, but it also undergoes sublimation. Below 140°C, it rapidly transforms into a solid and condenses into lumps. All pipelines are equipped with heat-insulating jackets, and the inner side of the purification pipe is equipped with a heating coil to keep the temperature inside the pipeline and purification tank above 145°C, ensuring that dimethyl phthalate is transported in liquid form within the decolorization system. At the same time, a heating coil is installed at the top of the purification tank to prevent sublimated dimethyl phthalate from condensing at the top of the purification tank upon cooling.

[0101] This embodiment also relates to a regenerated DMT decolorization and recovery system for performing the regenerated DMT decolorization and recovery method as described above, including a first purification tank 15, a second purification tank 16, a third purification tank 17, a temperature monitoring unit, a controller, a heating unit, valves, and a first DMT filter;

[0102] The first purification tank 15, the second purification tank 16, and the third purification tank 17 are connected in series, and valves are installed on all connecting pipes between the first purification tank 15, the second purification tank 16, and the third purification tank 17.

[0103] The temperature monitoring unit is used to monitor the real-time temperature of dimethyl phthalate in the first purification tank 15, the second purification tank 16, and the third purification tank 17.

[0104] The controller monitors the real-time temperature of dimethyl phthalate in the first purification tank 15, the second purification tank 16, and the third purification tank 17 through the temperature monitoring unit, and controls the heating unit to heat the dimethyl phthalate in the first purification tank 15, the second purification tank 16, and the third purification tank 17.

[0105] The outlets of the first purification tank 15, the second purification tank 16, and the third purification tank 17 are connected to the inlets of other purification tanks;

[0106] The outlets of the first purification tank 15, the second purification tank 16, and the third purification tank 17 are connected to the first DMT filter.

[0107] In this embodiment, the temperature monitoring unit is a temperature sensor, the heating unit is a coil, heating wire, etc., and the valve is an electronic valve; the principles of the temperature monitoring unit, controller, heating unit, and valve are conventional technical means, which will not be elaborated here.

[0108] For details, please refer to Figures 2 to 6This embodiment relates to a regenerated DMT decolorization and recovery system, including two or more purification tanks 1, a purification agent buffer tank 2, and two or more DMT filters 3. The two or more purification tanks 1 are connected in series. The top of the purification tank 1 is provided with a first inlet 11, which is connected to a DMT feed pipe 12. The bottom of the purification tank 1 is provided with a first outlet 13 and a second outlet 14. The second outlet 14 is used to discharge the purification agent. The second outlet 14 is connected to the purification agent buffer tank 2. The first outlet 13 is connected to the DMT filter 3, and the first outlet 13 of any purification tank 1 is connected to the first inlet 11 of other purification tanks 1.

[0109] The series-connected purification tanks 1 can perform multiple stages of filtration on DMT, resulting in better decolorization. Furthermore, all connecting pipes are equipped with valves 5, allowing for flexible control of material flow. Replacing the purifying agent in one purification tank 1 does not affect the normal operation of the remaining two purification tanks 1, enabling continuous decolorization and improving efficiency.

[0110] In this embodiment, the purification tank 1, purification agent buffer tank 2, and DMT filter 3 operate on conventional technical principles. Regenerated DMT is a special material; above 141°C, it is a highly fluid liquid, but it also undergoes sublimation. Below 140°C, it rapidly transforms into a solid and condenses into lumps. Therefore, all pipelines are equipped with insulation jackets to ensure the temperature of the regenerated DMT remains above 140°C, preventing DMT from condensing upon cooling.

[0111] According to some embodiments of this application, optionally, such as Figure 2 and Figure 3 As shown, the regenerated DMT decolorization and recovery system includes three purification tanks 1, two DMT filters 3, and a material feed pipe 4. The material feed pipe 4 is connected to the first inlet 11 of the three purification tanks 1 through the three DMT feed pipes 12, and the first outlet 13 of the three purification tanks 1 is connected to the two DMT filters 3.

[0112] In this way, the material feed pipe 4 can feed the three purification tanks 1, and the two DMT filters 3 can work together to improve work efficiency. Alternatively, one purification tank 1 can be repaired while the other purification tank 1 is working normally.

[0113] According to some embodiments of this application, optionally, such as Figure 4As shown, the three purification tanks 1 are the first purification tank 15, the second purification tank 16, and the third purification tank 17. The first outlet 13 of the first purification tank 15 is connected to the first inlet 11 of the second purification tank 16 through the first pipe 18. The first outlet 13 of the first purification tank 15 is connected to two DMT filters 3 through the second pipe 19. Valves 5 are respectively installed on the first pipe 18 and the second pipe 19.

[0114] Thus, the first purification tank 15 can supply material to the second purification tank 16 to achieve secondary filtration. The first purification tank 15 can also directly supply material to the two DMT filters 3. The valve 5 can be used to switch the first pipeline 18 and the second pipeline 19 on and off for easy use.

[0115] According to some embodiments of this application, optionally, the first outlet 13 of the second purification tank 16 is connected to the first inlet 11 of the third purification tank 17 through the third pipe 20, and the first outlet 13 of the second purification tank 16 is connected to two DMT filters 3 through the fourth pipe 21 respectively. Valves 5 are respectively provided on the third pipe 20 and the fourth pipe 21.

[0116] Thus, the second purification tank 16 can supply materials to the third purification tank 17 to achieve three-stage filtration. The second purification tank 16 can also directly supply materials to the two DMT filters 3. The valve 5 can be used to switch the third pipeline 20 and the fourth pipeline 21 on and off for easy use.

[0117] According to some embodiments of this application, optionally, such as Figure 5 As shown, the first outlet 13 of the third purification tank 17 is connected to the first inlet 11 of the first purification tank 15 and the first inlet 11 of the second purification tank 16 through the fifth pipe 22 and the sixth pipe 23, respectively. Valves 5 are respectively installed on the fifth pipe 22 and the sixth pipe 23.

[0118] Thus, the third purification tank 17 can supply materials to the first purification tank 15 and the second purification tank 16 through the fifth pipe 22 and the sixth pipe 23 to achieve secondary filtration, or when any one of the purification tanks is under maintenance, it will not affect the use of the other two purification tanks. The valve 5 controls the opening and closing of the fifth pipe 22 and the sixth pipe 23 for convenient use.

[0119] According to some embodiments of this application, optionally, such as Figure 6 As shown, the first outlet 13 of the second purification tank 16 is connected to the first inlet 11 of the first purification tank 15 through the seventh pipe 24, and the first outlet 13 of the second purification tank 16 is connected to the first inlet 11 of the third purification tank 17 through the eighth pipe 25. Valves 5 are respectively installed on the seventh pipe 24 and the eighth pipe 25.

[0120] Thus, the second purification tank 16 can supply material to the first purification tank 15, and the second purification tank 16 can also directly supply material to the third purification tank 17. Valve 5 controls the opening and closing of the seventh pipeline 24 and the eighth pipeline 25, making it convenient to use.

[0121] In this embodiment, valve 5 can be a mechanical valve, or more specifically, an electronic valve, which can be controlled from the back end.

[0122] According to some embodiments of this application, optionally, the regenerated DMT decolorization and recovery system further includes a hot water inlet pipe 6 and a steam inlet pipe 7. The hot water inlet pipe 6 is connected to the first feed port 11 of the purification tank 1 and the DMT filter 3, respectively. The steam inlet pipe 7 is connected to the first feed port 11 of the purification tank 1, the first discharge port 13 of the purification tank 1, and the DMT filter 3, respectively.

[0123] Hot water inlet pipe 6 and steam inlet pipe 7 provide hot water and steam to purification tank 1 and DMT filter 3, ensuring the temperature of purification tank 1 and DMT filter 3 and preventing DMT from converting into solid and condensing into lumpy material.

[0124] According to some embodiments of this application, optionally, the regenerated DMT decolorization and recovery system further includes a recovery material pre-tank 8, which is connected to the first discharge port 13 of the purification tank 1 and the DMT filter 3, respectively.

[0125] In this way, the materials in the purification tank 1 and the DMT filter 3 can be recovered through the recovery tank 8.

[0126] Unlike existing technologies, the technical solution of this application allows for multiple staged filtrations of dimethyl phthalate (DMT) using sequentially connected purification tanks, resulting in better decolorization. The flow direction of DMT in the first purification tank 15, the second purification tank 16, and the third purification tank 17 can be controlled according to the degree of DMT purification, enabling flexible control of the material flow. Replacing the purifying agent in any one purification tank does not affect the normal operation of the remaining two tanks, achieving continuous decolorization and improving efficiency. The temperature of DMT in the purification tanks can be monitored in real time to prevent DMT from solidifying, ensuring that DMT is transported in liquid form within the decolorization system and improving DMT recovery efficiency.

[0127] It should be noted that although the above embodiments have been described herein, this does not limit the scope of patent protection of the present invention. Therefore, any changes and modifications made to the embodiments described herein based on the innovative concept of the present invention, or equivalent structural or procedural transformations made using the content of the present invention's specification and drawings, directly or indirectly applying the above technical solutions to other related technical fields, are all included within the scope of patent protection of the present invention.

Claims

1. A method for decolorizing and recovering regenerated DMT, characterized in that, Includes the following steps: At least a first purification tank, a second purification tank, and a third purification tank are provided, and the first purification tank, the second purification tank, and the third purification tank are connected in series in the production sequence. Dimethyl phthalate to be recovered is added to the first purification tank, the second purification tank, and the third purification tank; Monitor the real-time temperature of dimethyl phthalate in the first purification tank, the second purification tank, and the third purification tank. When the real-time temperature of dimethyl phthalate in the first purification tank, the second purification tank, and the third purification tank is lower than the first preset value, heat the dimethyl phthalate in the first purification tank, the second purification tank, and the third purification tank. To determine the degree of purification of dimethyl phthalate in the first purification tank, the purified dimethyl phthalate from the first purification tank is added to the second or third purification tank. To determine the degree of purification of dimethyl phthalate in the second purification tank, add the purified dimethyl phthalate from the second purification tank to the third purification tank or the first purification tank. Determine the degree of purification of dimethyl phthalate in the third purification tank, and add the purified product from the third purification tank into the first DMT filter or the first purification tank.

2. The method for decolorizing and recovering regenerated DMT according to claim 1, characterized in that, It also includes the following steps: after determining the degree of purification of dimethyl phthalate in the first purification tank, the purified dimethyl phthalate from the first purification tank is added to the first DMT filter; After determining the degree of purification of dimethyl phthalate in the second purification tank, the purified dimethyl phthalate from the second purification tank is added to the first DMT filter; Dimethyl phthalate filtered by the first DMT filter is then recycled into the pre-recovery tank.

3. The method for decolorizing and recovering regenerated DMT according to claim 2, characterized in that, The capacity of the first DMT filter is monitored. When the capacity of the first DMT filter exceeds the preset value, the dimethyl phthalate purified by the first purification tank, the second purification tank, and the third purification tank is added to the second DMT filter. The dimethyl phthalate filtered by the second DMT filter enters the recovery material pre-tank for recovery.

4. The method for decolorizing and recovering regenerated DMT according to claim 1, characterized in that, The method also includes the following steps: after determining the degree of purification of dimethyl phthalate in the third purification tank, the purified dimethyl phthalate from the third purification tank is added to the second purification tank.

5. The method for decolorizing and recovering regenerated DMT according to claim 1, characterized in that, The saturation level of the purifying agent in the first purification tank, the second purification tank, and the third purification tank was monitored respectively; When the saturation level of the purifying agent in the first purification tank reaches the preset value, feeding into the first purification tank is stopped. The dimethyl phthalate to be recovered is added to the second or third purification tank. The purifying agent from the first purification tank is added to the purifying agent buffer tank. The real-time temperature of the purifying agent buffer tank is monitored. When the real-time temperature of the purifying agent buffer tank is lower than the first preset value, the purifying agent buffer tank is heated.

6. The method for decolorizing and recovering regenerated DMT according to claim 5, characterized in that, When the saturation level of the purifying agent in the second or third purification tank reaches the preset value, stop feeding the second or third purification tank and add the purifying agent from the second or third purification tank to the purifying agent buffer tank.

7. The method for decolorizing and recovering regenerated DMT according to claim 5, characterized in that, The purification agent added to the purification agent buffer tank is filtered to remove dimethyl phthalate from the purification agent; Monitor the real-time temperature of dimethyl phthalate in the purification buffer tank. When the real-time temperature of dimethyl phthalate in the purification buffer tank is lower than the first preset value, heat the dimethyl phthalate in the purification buffer tank.

8. The method for decolorizing and recovering regenerated DMT according to claim 7, characterized in that, Dimethyl phthalate in the purification buffer tank is recovered and added back into the first, second, or third purification tank.

9. The method for decolorizing and recovering regenerated DMT according to any one of claims 1-8, characterized in that, Valves are installed on all connecting pipes between the first purification tank, the second purification tank, and the third purification tank. Insulation jackets and heating units are installed on the inside of all connecting pipes to ensure that the temperature of the connecting pipes is higher than the first preset value.

10. A DMT decolorization and recycling system, characterized in that, The method for performing the regenerated DMT decolorization and recovery method as described in any one of claims 1-9 includes a first purification tank, a second purification tank, a third purification tank, a temperature monitoring unit, a controller, a heating unit, valves, and a first DMT filter. The first purification tank, the second purification tank, and the third purification tank are connected in series, and valves are installed on all connecting pipes between the first purification tank, the second purification tank, and the third purification tank. The temperature monitoring unit is used to monitor the real-time temperature of dimethyl phthalate in the first purification tank, the second purification tank, and the third purification tank. The controller monitors the real-time temperature of dimethyl phthalate in the first purification tank, the second purification tank, and the third purification tank through the temperature monitoring unit, and controls the heating unit to heat the dimethyl phthalate in the first purification tank, the second purification tank, and the third purification tank. The discharge ports of the first purification tank, the second purification tank, and the third purification tank are connected to the inlets of other purification tanks; The discharge ports of the first purification tank, the second purification tank, and the third purification tank are connected to the first DMT filter.

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