Pbat polycondensation system

Abstract

The utility model discloses a PBAT polycondensation system relates to polyester production technical field, and the main purpose is to reduce finished product impurity, improve the qualified product rate. The main technical scheme of the utility model is: PBAT polycondensation system, and this system includes: the precondensation tower of connection in proper order, melt pump, import tee bend valve, double -cylinder filtration unit, export tee bend valve, final condensation cauldron and granulator, wherein, double -cylinder filtration unit includes two melt filters in parallel.

Description

Technical Field

[0001] This utility model relates to the field of polyester production technology, and in particular to a PBAT polycondensation system. Background Technology

[0002] In the continuous polymerization production of PBAT / PBT, after esterification or transesterification, the material enters the prepolymerization reactor for preliminary polymerization to form a prepolymer with low intrinsic viscosity. Then, it enters the final polymerization reactor to complete the final polymerization and then spins.

[0003] Traditional processes typically involve placing a filtration device between the polymerization terminal and the spinning process; however, this process often suffers from the following problems:

[0004] (1) The final filter needs to be switched every 8 days. During the switching period, production is unstable and the process fluctuates, resulting in waste discharge from the pelletizer and causing direct economic losses. After switching, the filter element has residual residue, which increases the amount of black spot material and produces off-grade material. In addition, high-frequency cleaning shortens the life of the filter element and increases production costs.

[0005] (2) Impurities remain in the final product, causing fish eyes or film breakage in PBAT end products, or reducing the strength of PBT engineering plastics. Utility Model Content

[0006] In view of this, the present invention provides a PBAT polycondensation system, the main purpose of which is to reduce impurities in the finished product and improve the yield of qualified products.

[0007] To achieve the above objectives, this utility model mainly provides the following technical solutions:

[0008] This utility model provides a PBAT polycondensation system, which includes: a pre-polycondensation tower, a melt pump, an inlet three-way valve, a dual-cylinder filter unit, an outlet three-way valve, a final polycondensation kettle, and a pelletizer connected in sequence.

[0009] The dual-cylinder filtration unit includes two melt filters connected in parallel.

[0010] The purpose of this utility model and the technical problems to be solved can be further achieved by the following technical measures.

[0011] Optionally, the melt filter has multiple filter tubes evenly distributed around its inner circumference. Each filter tube includes an outer tube body, a filter element body, and an inner tube body that are sequentially nested together. The tube walls of the outer tube body and the inner tube body are evenly distributed with multiple through holes. The filter element body is a pleated metal sintered felt layer.

[0012] Optionally, it also includes annular metal wires. The filter element body includes multiple circumferentially distributed sintered felt plates, which are connected in sequence. Each sintered felt plate extends along the diameter direction of the inner tube body, and the annular metal wires are fixedly connected to the multiple sintered felt plates respectively.

[0013] Optionally, the housing of the melt filter is provided with a first heat-conducting oil jacket.

[0014] Optionally, the housing of the inlet three-way valve and the housing of the outlet three-way valve are respectively provided with a second heat transfer oil jacket.

[0015] Optionally, a booster pump is also included, which is installed between the final shrinking vessel and the pelletizer.

[0016] Optionally, it also includes a temperature sensor and a first pressure sensor, which are sequentially installed in the melt pipeline between the melt pump and the inlet three-way valve.

[0017] Optionally, a second pressure sensor and a third pressure sensor are also included, wherein the second pressure sensor is installed in the inlet pipe of the inlet three-way valve and the third pressure sensor is installed in the outlet pipe of the outlet three-way valve.

[0018] By employing the above technical solution, this utility model has at least the following advantages:

[0019] In the prepolymerization tower, impurities such as gel particles and carbonized particles are often generated in the prepolymer melt due to local overheating, catalyst residue, etc. These impurities are pumped into one of the two melt filters along with the polyester melt. The impurities are intercepted by the filter element and will not enter the precision-structured final shrinkage vessel. This prevents impurities from being carried into the final shrinkage vessel, affecting the surface area renewal and vacuum devolatilization efficiency, and causing unstable product quality.

[0020] The above system, with its dual-cylinder parallel and online switching design, eliminates problems such as black spot material caused by untimely switching, process fluctuations caused by switching, and waste discharge, further reducing the impurity content of the finished polyester resin. Attached Figure Description

[0021] Figure 1 A schematic diagram of a PBAT polycondensation system provided in an embodiment of this utility model;

[0022] Figure 2 This is a schematic diagram of the structure of a melt filter;

[0023] Figure 3 for Figure 2 View from point AA;

[0024] Figure 4 for Figure 3 Enlarged view of section B.

[0025] The reference numerals in the accompanying drawings include: 1. Prepolymerization tower; 2. Melt pump; 3. Inlet three-way valve; 4. Outlet three-way valve; 5. Final shrinkage vessel; 6. Pelletizer; 7. Melt filter; 8. Final shrinkage filter; 9. Thermometer; 10. Filter tube; 10. Outer tube body; 1001. Filter element body; 1002. Inner tube body; 1003. Annular metal wire; 1004. Limiting plate; 1005. First heat transfer oil jacket; 11. Second heat transfer oil jacket; 12. Booster pump; 13. Temperature sensor; 14. First pressure sensor; 15. Second pressure sensor; 16. Third pressure sensor; 17. Detailed Implementation

[0026] To further illustrate the technical means and effects adopted by this utility model to achieve its intended purpose, the specific implementation methods, structures, features, and effects according to this utility model application are described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0028] like Figure 1 As shown, an embodiment of the present invention provides a PBAT polycondensation system, which includes: a pre-polycondensation tower 1, a melt pump 2, an inlet three-way valve 3, a dual-cylinder filter unit, an outlet three-way valve 4, a final polycondensation kettle 5, and a pelletizer 6 connected in sequence.

[0029] The dual-cylinder filter unit includes two melt filters 7 connected in parallel.

[0030] The working process of the PBAT polycondensation system is as follows:

[0031] In the prepolymerization tower 1, impurities such as gel particles and carbonized particles are often generated in the prepolymer melt due to local overheating, catalyst residue, etc. These impurities are carried by the polyester melt into one of the two melt filters 7 through the melt pump 2. The impurities are intercepted by the filter element and will not enter the precision-structured final shrinkage vessel 5, thus avoiding the impurities being carried into the final shrinkage vessel 5, which would affect the surface area renewal and vacuum devolatilization efficiency, resulting in unstable product quality.

[0032] The above system, with its dual-cylinder parallel and online switching design, eliminates problems such as black spot material caused by untimely switching, process fluctuations caused by switching, and waste discharge, further reducing the impurity content of the finished polyester resin.

[0033] Specifically, the advantages of this system are as follows:

[0034] (1) Precise protection of core equipment and extended operating cycle: Filters are installed at key locations between pre-condensation and final condensation to effectively intercept gel and carbonized particles, fundamentally avoiding clogging and contamination of the final condensation reactor 5. After installation, the switching cycle of the melt filter 7 is about 20 days / time, and the switching cycle of the final condensation filter 8 is extended from 8 days to 30 days / time, significantly improving the operating cycle.

[0035] (2) Significantly improved product quality: The purity of the material supplied to the final shrinkage reactor 5 is greatly improved, effectively reducing defects such as fisheye and film breakage in PBAT film and improving the mechanical properties of PBT engineering plastics; the melt flow channel adopts a low roughness design with Ra≤0.8μm, which can prevent material degradation. The yield of superior PBAT products is significantly improved.

[0036] (3) Reduce overall operation and maintenance costs: Reduce the frequency of shutdown and cleaning of the final shrinkage vessel 5, saving cleaning costs and material losses; the modular design of the filter makes maintenance convenient, reducing maintenance costs and time costs. The problem of shortened filter life caused by high-frequency cleaning is solved.

[0037] Specifically, thermometers 9 are installed in the housings of the two melt filters 7 respectively.

[0038] In a specific embodiment, the melt filter 7 has a plurality of filter tubes 10 evenly distributed around its inner circumference. Each filter tube 10 includes an outer tube body 1001, a filter element body 1002 and an inner tube body 1003 that are sequentially nested together. The tube walls of the outer tube body 1001 and the inner tube body 1003 are evenly distributed with a plurality of through holes. The filter element body 1002 is a pleated metal sintered felt layer.

[0039] In this embodiment, specifically, the filter element body 1002 adopts a pleated metal sintered felt filter element, and the filter element body 1002 has a diameter of 60mm, a length of 1215mm, and a filtration accuracy of 40μm.

[0040] Specifically, the outer tube 1001 and the inner tube 1003 constrain the shape of the filter element body 1002 to maintain a pleated state, preventing the filter element body 1002 from spreading out, thereby allowing the filter element body 1002 to maintain a large filtration surface area within a limited space.

[0041] like Figure 2 , Figure 3 , Figure 4 As shown, in a specific embodiment, it also includes annular metal wire 1004. The filter element body 1002 is composed of a plurality of sintered felt plates evenly distributed around the circumference. The plurality of sintered felt plates are connected in sequence. Each sintered felt plate extends along the diameter direction of the inner tube 1003. The annular metal wire 1004 is fixedly connected to the plurality of sintered felt plates respectively.

[0042] In this embodiment, specifically, the three adjacent sintering anvils are a first sintering anvil, a second sintering anvil, and a third sintering anvil. One side of the second sintering anvil is fixedly connected to the first sintering anvil, and the other side of the second sintering anvil is fixedly connected to the third sintering anvil. The center of the annular metal wire 1004 coincides with the center of the inner tube 1003. The annular metal wire 1004 is evenly distributed with multiple limiting pieces 1005 (the limiting pieces 1005 are fixedly welded to the annular metal wire 1004). Each sintering anvil is clamped between two adjacent limiting pieces 1005, thereby fixing the distance between two adjacent sintering anvils. This prevents the pressure generated by the melt flow on the filter element body 1002 from causing the two adjacent sintering anvils to move away from or close to each other, and prevents the two adjacent sintering felts from sticking together. This ensures that the melt flow rate between each pair of adjacent sintering anvils remains consistent, thereby making full use of each unit area of ​​the filter element body 1002.

[0043] Specifically, there are multiple annular metal wires 1004, which are arranged at equal intervals along the axial direction of the filter element body 1002. The limiting pieces 1005 on the multiple annular metal wires 1004 together fix the spacing between two adjacent sintering anvils.

[0044] like Figure 2 As shown in the specific embodiment, the shell of the melt filter 7 is provided with a first heat-conducting oil jacket 11.

[0045] In this embodiment, specifically, the first heat transfer oil jacket 11 is disposed on the periphery of the shell of the melt filter 7, so as to heat the polyester melt flowing through the melt filter 7, so that the polyester melt is in a viscous flow state with good fluidity, and at the same time, the polyester melt continues to undergo pre-condensation reaction in the melt filter 7.

[0046] like Figure 2 As shown, in a specific embodiment, the housing of the inlet three-way valve 3 and the housing of the outlet three-way valve 4 are respectively provided with a second heat transfer oil jacket 12.

[0047] In this embodiment, specifically, when the polyester melt flows through the inlet three-way valve 3 and the outlet three-way valve 4, the heat transfer oil can heat the flowing polyester melt, so that the polyester melt is in a viscous flow state with good fluidity.

[0048] like Figure 1 As shown, in a specific embodiment, a booster pump 13 is also included, which is installed between the final shrinkage tank 5 and the pelletizer 6.

[0049] In this embodiment, specifically, the polyester melt flowing out of the final shrinkage kettle 5 is pressurized by the booster pump 13, which enables it to stably and continuously output resin filaments in the pelletizer 6, thus facilitating the stable operation of the production system.

[0050] like Figure 1 As shown, in a specific embodiment, it also includes a temperature sensor 14 and a first pressure sensor 15, which are sequentially installed in the melt pipeline between the melt pump 2 and the inlet three-way valve 3.

[0051] In this embodiment, specifically, the temperature sensor 14 and the first pressure sensor 15 can be used to monitor the temperature and pressure of the polyester melt output by the melt pump 2 in real time, providing data support for optimizing operation and preventive maintenance.

[0052] like Figure 1 As shown, in a specific embodiment, a second pressure sensor 16 and a third pressure sensor 17 are also included. The second pressure sensor 16 is installed in the inlet pipe of the inlet three-way valve 3, and the third pressure sensor 17 is installed in the outlet pipe of the outlet three-way valve 4.

[0053] In this embodiment, specifically, a parallel, online switching design of dual melt filters 7 is adopted (electric inlet and outlet three-way valves 4, combined with the differential pressure monitoring formed by the second pressure sensor 16 and the third pressure sensor 17, to realize the non-stop operation of the filtration system), which greatly improves the continuity and stability of system operation and eliminates problems such as black spot material, process fluctuations and waste discharge caused by untimely switching.

[0054] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A PBAT polycondensation system, characterized in that, include: The prepolymerization tower, melt pump, inlet three-way valve, dual-cylinder filter unit, outlet three-way valve, final shrinkage kettle and pelletizer are connected in sequence. The dual-cylinder filter unit includes two melt filters connected in parallel.

2. The PBAT polycondensation system according to claim 1, characterized in that, The melt filter has multiple filter tubes evenly distributed around its inner circumference. Each filter tube includes an outer tube body, a filter element body, and an inner tube body that are sequentially nested together. The tube walls of the outer tube body and the inner tube body are evenly distributed with multiple through holes. The filter element body is a pleated metal sintered felt layer.

3. The PBAT polycondensation system according to claim 2, characterized in that, It also includes annular metal wires. The filter element body includes multiple circumferentially distributed sintered felt plates, which are connected in sequence. Each sintered felt plate extends along the diameter direction of the inner tube body, and the annular metal wires are fixedly connected to the multiple sintered felt plates respectively.

4. The PBAT polycondensation system according to claim 1, characterized in that, The shell of the melt filter is provided with a first heat-conducting oil jacket.

5. The PBAT polycondensation system according to claim 1, characterized in that, The housings of the inlet three-way valve and the outlet three-way valve are each provided with a second heat transfer oil jacket.

6. The PBAT polycondensation system according to claim 1, characterized in that, It also includes a booster pump, which is installed between the final shrinking vessel and the pelletizer.

7. The PBAT polycondensation system according to claim 1, characterized in that, It also includes a temperature sensor and a first pressure sensor, which are sequentially installed in the melt pipeline between the melt pump and the inlet three-way valve.

8. The PBAT polycondensation system according to claim 1, characterized in that, It also includes a second pressure sensor and a third pressure sensor, the second pressure sensor being installed in the inlet pipe of the inlet three-way valve, and the third pressure sensor being installed in the outlet pipe of the outlet three-way valve.

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