Filtering device for separating lactide

Abstract

The utility model discloses a kind of filtering devices for separating propylene lactone, it is related to propylene lactone production device technical field, the upper portion of cylinder is equipped with feed inlet and hot nitrogen inlet, the lower portion of cylinder one side is equipped with discharge port, the jacket of cylinder is equipped with cylinder heat source import valve and cylinder heat source export valve, the lower head outside jacket of cylinder is equipped with head heat source import valve and head heat source export valve;Stirring shaft is equipped in cylinder, driving motor is connected with the upper end of stirring shaft through speed reducer, and a plurality of stirring blades are arranged on stirring shaft, and filter screen is arranged on the lower portion of cylinder at discharge port. Feed inlet and hot nitrogen inlet are arranged on the upper portion of cylinder, feed inlet can accurately control material input, and hot nitrogen inlet can utilize the drying and heating characteristics of hot nitrogen, create suitable separation environment, prevent material from damp and promote propylene lactone gasification or sublimation, conducive to subsequent separation. Discharge port of the lower portion of cylinder one side is convenient for propylene lactone finished product after separation to discharge.

Description

Technical Field

[0001] This utility model relates to the technical field of lactide production equipment, specifically to a filtration device for lactide separation. Background Technology

[0002] Degradable polylactic acid (PLA) materials are essential for alleviating global environmental and energy problems. On the one hand, their raw materials come from renewable plant resources, reducing dependence on traditional fossil fuels; on the other hand, their biodegradability reduces plastic waste pollution, which is significant for achieving sustainable development. As a key intermediate in the synthesis of PLA, the synthesis and purification process of lactide is a key research focus in the industry. The purity of lactide directly affects the degree of polymerization of PLA. To obtain higher molecular weights and product performance, suspension crystallization, as a novel high-purity purification technology, has received widespread attention, especially in the field of lactide purification, where it has significant advantages. Suspension crystallization generally consists of a crystallization unit and a separation unit. After crystallization, the final lactide crystals are obtained by separation equipment; therefore, the selection of solid-liquid separation equipment is particularly important.

[0003] Lactide is an intermediate raw material for the synthesis of high molecular weight polylactic acid (PLA). Its chemical purity determines the molecular weight and molecular weight distribution of PLA, while its optical purity affects the mechanical properties of PLA materials. Therefore, the purification and refining of lactide is a crucial step in PLA synthesis. Suspension melt crystallization, as a novel high-purity purification technology, has attracted widespread attention, especially in the purification of thermosensitive systems, where it demonstrates significant advantages. Separation equipment is the core component of suspension crystallization. Three-in-one filters are commonly used in the pharmaceutical field, integrating filtration, washing, and drying functions into a single device. In existing technologies, filters can only be used for solid-liquid separation of low-melting-point materials, while lactide slurry has a high melting point; below a certain temperature, the material will solidify.

[0004] Chinese Patent 202420047373.3 discloses a cone filter for lactide separation, with a jacketed heating system and a discharge valve at the bottom of the cone. It can achieve lactide crystal slurry separation, washing, and drying. However, during the separation process, the filtrate accumulates at the discharge valve at the bottom of the vessel. The discharge valve temperature is low, causing the filtrate to solidify. After separation, the discharge valve is often difficult to open due to material solidification. Furthermore, the bottom material contains a large amount of mother liquor due to the accumulation of filtrate, leading to unstable product specifications. Summary of the Invention

[0005] The technical problem to be solved by this utility model is to provide a filtration device for separating lactide, which has good solid-liquid separation effect and stable product quality, in order to address the shortcomings of the existing technology.

[0006] To solve the above-mentioned technical problems, the technical solution of this utility model is as follows:

[0007] A filtration device for separating lactide includes a cylindrical body, with an inlet and a hot nitrogen inlet at the upper part of the cylindrical body, a discharge port on one side of the lower part of the cylindrical body, a jacket of the cylindrical body equipped with a cylindrical body heat source inlet valve and a cylindrical body heat source outlet valve, and a jacket of the lower end cap of the cylindrical body equipped with an end cap heat source inlet valve and an end cap heat source outlet valve.

[0008] The cylinder is equipped with a stirring shaft, and the upper end of the stirring shaft is connected to a drive motor through a speed reducer. The stirring shaft is equipped with several stirring blades, and the cylinder is equipped with a filter screen at the lower part of the discharge port.

[0009] As an improved technical solution, the stirring blade is a three-bladed swept blade.

[0010] As an improved technical solution, a temperature sensor is provided inside the cylinder, and the cylinder heat source inlet valve, the cylinder heat source outlet valve, the end cap heat source inlet valve, and the end cap heat source outlet valve are interlocked with the temperature sensor to the control system.

[0011] As an improved technical solution, a liquid level sensor is provided inside the cylinder, and a feed valve is provided at the feed inlet. The liquid level sensor and the feed valve are interlocked to the control system.

[0012] As an improved technical solution, the bottom of the cylinder is provided with a mother liquor outlet.

[0013] As an improved technical solution, the stirring shaft is provided with a first cavity, the outer side of the stirring shaft is provided with a heat tracing sleeve, and a second cavity is provided between the outer wall of the stirring shaft and the heat tracing sleeve. The first cavity is connected to a heat medium inlet, and the second cavity is connected to a heat medium outlet.

[0014] As a preferred technical solution, the discharge port is connected to a discharge valve via a pipeline, and the discharge valve is a heat-traced plunger valve.

[0015] As a preferred technical solution, the filter screen has a size of 2*10mm.

[0016] Due to the adoption of the above technical solution, the beneficial effects of this utility model are:

[0017] This utility model discloses a filtration device for separating lactide, comprising a cylindrical body. The upper part of the cylindrical body has a feed inlet and a hot nitrogen inlet, while the lower part of the cylindrical body has a discharge port. The jacket of the cylindrical body is equipped with a heat source inlet valve and a heat source outlet valve. The outer jacket of the lower end cap of the cylindrical body is equipped with a head heat source inlet valve and a head heat source outlet valve. A stirring shaft is installed inside the cylindrical body, and a drive motor is connected to the upper end of the stirring shaft via a reducer. The stirring shaft has several stirring blades. A filter screen is installed below the discharge port of the cylindrical body. The feed inlet and hot nitrogen inlet at the upper part of the cylindrical body allow for precise control of material input. The hot nitrogen inlet utilizes the drying and heating properties of hot nitrogen to create a suitable separation environment, preventing the material from becoming damp and promoting the vaporization or sublimation of lactide, which is beneficial for subsequent separation. The discharge port on the lower part of the cylindrical body facilitates the discharge of the separated lactide product.

[0018] The cylinder jacket and the outer jacket of the lower head are equipped with heat source inlet and outlet valves, allowing for comprehensive and precise temperature control within the cylinder. This maintains the stable temperature required for lactide separation, preventing product quality issues caused by temperature fluctuations. The stirring shaft inside the cylinder is driven by a motor via a reducer, causing the stirring blades to rotate. This ensures thorough mixing of the materials, accelerating the separation of lactide from other components and improving separation efficiency and uniformity. A filter screen is installed at the bottom of the discharge port to effectively intercept unseparated impurities, ensuring the purity of the discharged lactide product and meeting the production requirements for high-quality products.

[0019] The stirring blades of this invention are three-bladed swept-back blades. The special shape design of the three-bladed swept-back blades effectively reduces energy consumption during the stirring process and improves stirring efficiency. Compared to ordinary blades, they can more evenly stir the materials in the cylinder, allowing lactide to mix thoroughly with other components. This helps the lactide pass through the filter screen more smoothly during subsequent filtration and separation, improving the separation effect. At the same time, the three-bladed swept-back blades generate a gentler stirring flow field, reducing damage to the lactide crystal structure and ensuring the quality of the lactide product.

[0020] A temperature sensor is installed inside the cylinder. The cylinder heat source inlet valve, cylinder heat source outlet valve, end cap heat source inlet valve, and end cap heat source outlet valve are interlocked with the temperature sensor to the control system. The temperature sensor can monitor the temperature inside the cylinder in real time. By interlocking with each heat source inlet and outlet valve to the control system, the heat source flow rate of the cylinder jacket and the outer jacket of the lower end cap can be precisely adjusted, thereby accurately controlling the temperature inside the cylinder. For the separation process of lactide, a suitable and stable temperature is a key factor in ensuring separation effect and product quality. A stable temperature environment can prevent lactide from crystallizing abnormally or decomposing due to temperature fluctuations, ensuring the smooth progress of the entire separation process and improving product purity and yield.

[0021] The cylinder is equipped with a liquid level sensor, and the feed inlet is equipped with a feed valve. The liquid level sensor and the feed valve are interlocked with the control system. The liquid level sensor can provide real-time feedback on the liquid level inside the cylinder. When the liquid level reaches the set upper limit, the liquid level sensor transmits a signal to the control system, and the control system automatically closes the feed valve to prevent material overflow. When the liquid level falls below the set lower limit, the control system can automatically open the feed valve to replenish material. This interlocking control mechanism can maintain a stable liquid level inside the cylinder, ensuring the safety and continuity of equipment operation. A stable liquid level is beneficial for uniform mixing and subsequent filtration operations, avoiding the impact of excessively high or low liquid levels on the separation effect of lactide and the normal operation of the equipment.

[0022] The bottom of the cylinder is equipped with a mother liquor discharge port. During the lactide separation process, incompletely separated lactide and other impurities may remain in the mother liquor. The bottom discharge port facilitates timely discharge of the mother liquor, allowing for subsequent processing such as further lactide recovery or impurity removal. This not only improves the lactide recovery rate and reduces resource waste, but also prevents the accumulation of mother liquor within the cylinder from affecting subsequent separation operations, ensuring long-term stable operation of the equipment and improving overall production efficiency.

[0023] The stirring shaft has a first cavity, and a heat tracing sleeve is provided on the outer side of the stirring shaft. A second cavity is provided between the outer wall of the stirring shaft and the heat tracing sleeve. The first cavity is connected to a heat medium inlet, and the second cavity is connected to a heat medium outlet. Heat medium is introduced into the first cavity through the heat medium inlet, flowing within the first cavity to heat the interior of the stirring shaft. Simultaneously, the heat medium flows out from the heat medium outlet of the second cavity. During this process, the heat medium heats the space between the outer wall of the stirring shaft and the heat tracing sleeve. This design enables the stirring shaft itself to have a heat tracing function, effectively preventing material from adhering to or crystallizing on the stirring shaft, ensuring the normal rotation of the stirring shaft. During lactide separation, it avoids the accumulation of material on the stirring shaft, which could affect the stirring effect and separation efficiency, maintaining stable equipment operation.

[0024] The discharge port is connected to a discharge valve via a pipeline, and the discharge valve is a heated plunger valve. The heated plunger valve heats the discharge valve and its connecting pipeline, preventing lactide from crystallizing and clogging the valve and pipeline due to temperature drop during discharge. This ensures a smooth discharge process, guaranteeing the equipment can continuously and stably discharge the separated lactide, thus improving production efficiency. Simultaneously, the plunger valve's structural features provide excellent sealing and regulating performance, enabling precise control of the discharge flow rate to meet the discharge speed requirements of different production processes.

[0025] The filter screen has a specification of 2*10mm. This 2*10mm size effectively intercepts impurity particles in lactide, ensuring the purity of the filtered lactide product. The mesh size of this filter screen is rationally designed to avoid both excessively large meshes that prevent effective impurity interception and affect product quality, and excessively small meshes that cause filter clogging and reduce filtration efficiency. This suitable filter screen specification maintains a high filtration speed while ensuring filtration effectiveness, meeting the dual requirements of output and quality in the production process. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Figure 1 This is a structural schematic diagram of an embodiment of the present utility model;

[0028] Figure 2 yes Figure 1 Schematic diagram of the structure of the stirring shaft;

[0029] Figure 3 yes Figure 2 Enlarged view of part of the structure of the central stirring shaft;

[0030] The components are as follows: 1. Cylinder; 2. Feed inlet; 3. Hot nitrogen inlet; 4. Discharge outlet; 5. Cylinder heat source inlet valve; 6. Cylinder heat source outlet valve; 7. Lower head; 8. Head heat source inlet valve; 9. Head heat source outlet valve; 10. Stirring shaft; 11. Reducer; 12. Drive motor; 13. Stirring blades; 14. Filter screen; 15. Temperature sensor; 16. Liquid level sensor; 17. Feed valve; 18. Mother liquor outlet; 19. First cavity; 20. Heating jacket; 21. Second cavity; 22. Heat medium inlet; 23. Heat medium outlet; 24. Discharge valve; 25. Sealed bearing; 26. Sleeve; 27. Third cavity; 28. Fourth cavity. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] like Figure 1-3As shown, a filtration device for separating lactide includes a cylindrical body 1. The upper part of the cylindrical body 1 has a feed inlet 2 and a hot nitrogen inlet 3. A discharge port 4 is located on one side of the lower part of the cylindrical body 1. A heat source inlet valve 5 and a heat source outlet valve 6 are provided in the jacket of the cylindrical body 1. A heat source inlet valve 8 and a heat source outlet valve 9 are provided in the jacket outside the lower end cap 7 of the cylindrical body 1. A stirring shaft 10 is installed inside the cylindrical body 1. The upper end of the stirring shaft 10 is connected to a drive motor 12 via a reducer 11. Several stirring blades 13 are provided on the stirring shaft 10. A filter screen 14 is provided below the discharge port 4 in the cylindrical body 1. The feed inlet 2 and the hot nitrogen inlet 3 at the upper part of the cylindrical body 1 allow for precise control of material input. The hot nitrogen inlet 3 utilizes the drying and heating properties of hot nitrogen to create a suitable separation environment, preventing the material from becoming damp and promoting the vaporization or sublimation of lactide, which is beneficial for subsequent separation. The discharge port 4 on one side of the lower part of the cylinder 1 facilitates the discharge of the separated lactide product.

[0033] Heat source inlet and outlet valves are respectively installed in the jacket of cylinder 1 and the outer jacket of the lower end cap 7, which can comprehensively and precisely control the temperature inside cylinder 1, maintain the stable temperature required for lactide separation, and avoid product quality problems caused by temperature fluctuations. The stirring shaft 10 inside cylinder 1 is driven by drive motor 12 through reducer 11, and the stirring blades 13 rotate accordingly, which can fully stir the materials, accelerate the separation of lactide from other components, and improve separation efficiency and uniformity. A filter screen 14 is installed at the bottom of the discharge port 4, which can effectively intercept unseparated impurities, ensure the purity of the discharged lactide product, and meet the production requirements for high-quality products.

[0034] The stirring blade 13 of this invention is a three-bladed swept-back blade. The special shape design of the three-bladed swept-back blade effectively reduces energy consumption during the stirring process and improves stirring efficiency. Compared to ordinary blades, it can more evenly stir the material inside the cylinder 1, allowing lactide to mix thoroughly with other components. This helps the lactide pass more smoothly through the filter screen 14 during subsequent filtration and separation, improving the separation effect. At the same time, the three-bladed swept-back blade generates a gentler stirring flow field, reducing damage to the lactide crystal structure and ensuring the quality of the lactide product.

[0035] A temperature sensor 15 is installed inside the cylinder 1. The cylinder heat source inlet valve 5, the cylinder heat source outlet valve 6, the end cap heat source inlet valve 8, and the end cap heat source outlet valve 9 are interlocked with the temperature sensor 15 to the control system. The temperature sensor 15 can monitor the temperature inside the cylinder 1 in real time. By interlocking with each heat source inlet and outlet valve to the control system, the heat source flow rate of the jacket of the cylinder 1 and the outer jacket of the lower end cap 7 can be precisely adjusted, thereby accurately controlling the temperature inside the cylinder 1. For the separation process of lactide, a suitable and stable temperature is a key factor in ensuring the separation effect and product quality. A stable temperature environment can prevent lactide from crystallizing abnormally or decomposing due to temperature fluctuations, ensuring the smooth progress of the entire separation process and improving the purity and yield of the product.

[0036] A liquid level sensor 16 is installed inside the cylinder 1, and a feed valve 17 is installed at the feed inlet 2. The liquid level sensor 16 and the feed valve 17 are interlocked with the control system. The liquid level sensor 16 can provide real-time feedback on the liquid level inside the cylinder 1. When the liquid level reaches the set upper limit, the liquid level sensor 16 transmits a signal to the control system, and the control system automatically closes the feed valve 17 to prevent material overflow. When the liquid level is lower than the set lower limit, the control system can automatically open the feed valve 17 to replenish the material. This interlocking control mechanism can maintain a stable liquid level inside the cylinder 1, ensuring the safety and continuity of equipment operation. A stable liquid level is beneficial for uniform stirring and subsequent filtration operations, avoiding the impact of excessively high or low liquid levels on the separation effect of lactide and the normal operation of the equipment.

[0037] The bottom of the cylinder 1 is equipped with a mother liquor outlet 18. During the lactide separation process, incompletely separated lactide and other impurities may remain in the mother liquor. The mother liquor outlet 18 at the bottom facilitates timely discharge of the mother liquor, allowing for subsequent processing such as further lactide recovery or impurity removal. This not only improves the lactide recovery rate and reduces resource waste, but also prevents the accumulation of mother liquor within the cylinder 1 from affecting subsequent separation operations, ensuring long-term stable operation of the equipment and improving overall production efficiency.

[0038] The stirring shaft 10 has a first cavity 19, and a heat tracing sleeve 20 is provided on the outer side of the stirring shaft 10. A second cavity 21 is provided between the outer wall of the stirring shaft 10 and the heat tracing sleeve 20. A sleeve 26 is provided on the upper side of the stirring shaft 10. The sleeve 26 has a third cavity 27 and a fourth cavity 28 corresponding to the first cavity 19 and the second cavity 21 of the stirring shaft 10, respectively. Sealed bearings 25 are provided at the top of opposite ends of the stirring shaft 10 and the sleeve 26, so that the stirring shaft 10 can rotate under the action of the drive motor 12 and the reducer 11, but the sleeve 26 is fixed. However, there is no leakage at the contact point between the stirring shaft 10 and the sleeve 26. The third cavity 27 is connected to a heat medium inlet 22, and the fourth cavity 28 is connected to a heat medium outlet 23. Heat medium is introduced into the third cavity 27 through the heat medium inlet 22 and flows into the first cavity 19, which can heat the inside of the stirring shaft 10. Simultaneously, the heat medium flows out from the heat medium outlet 23 of the fourth cavity 28. During this process, the heat medium heats the space between the outer wall of the stirring shaft 10 and the heat tracing jacket 20. This design enables the stirring shaft 10 to have its own heat tracing function, effectively preventing materials from adhering to or crystallizing on the stirring shaft 10, and ensuring the normal rotation of the stirring shaft 10. In the lactide separation process, it can avoid the accumulation of materials on the stirring shaft 10, which would affect the stirring effect and separation efficiency, and maintain the stable operation of the equipment.

[0039] The discharge port 4 is connected to a discharge valve 24 via a pipe. The discharge valve 24 is a heated plunger valve. The heating function of the heated plunger valve heats the discharge valve 24 and its connecting pipes, preventing lactide from crystallizing and clogging the valve and pipes due to temperature drop during discharge. This ensures smooth discharge, guaranteeing the equipment can continuously and stably discharge the separated lactide, thus improving production efficiency. Simultaneously, the plunger valve's structural features provide excellent sealing and regulating performance, enabling precise control of the discharge flow rate to meet the discharge speed requirements of different production processes.

[0040] The filter screen 14 has a specification of 2*10mm. This 2*10mm specification effectively intercepts impurity particles in lactide, ensuring the purity of the filtered lactide product. The mesh size of this filter screen 14 is rationally designed, avoiding both excessively large meshes that would prevent effective impurity interception and affect product quality, and excessively small meshes that would cause clogging and reduce filtration efficiency. This suitable filter screen 14 specification maintains a high filtration speed while ensuring filtration effectiveness, meeting the dual requirements of output and quality in the production process.

[0041] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A filtration device for separating lactide, comprising a cylindrical body, wherein the upper part of the cylindrical body is provided with a feed inlet and a hot nitrogen inlet, and the lower part of the cylindrical body is provided with a discharge outlet; the jacket of the cylindrical body is provided with a cylindrical body heat source inlet valve and a cylindrical body heat source outlet valve, characterized in that: The outer sleeve of the lower end cap of the cylinder is equipped with an end cap heat source inlet valve and an end cap heat source outlet valve; The cylinder is equipped with a stirring shaft, and the upper end of the stirring shaft is connected to a drive motor through a reducer. The stirring shaft is equipped with several stirring blades, and the cylinder is equipped with a filter screen at the lower part of the discharge port. The stirring shaft has a first cavity, and a heat tracing sleeve is provided on the outside of the stirring shaft. A second cavity is provided between the outer wall of the stirring shaft and the heat tracing sleeve. The first cavity is connected to a heat medium inlet, and the second cavity is connected to a heat medium outlet.

2. The filtration device for separating lactide as described in claim 1, characterized in that: The stirring blades are three-bladed swept blades.

3. The filtration device for separating lactide as described in claim 1, characterized in that: A temperature sensor is installed inside the cylinder. The cylinder heat source inlet valve, the cylinder heat source outlet valve, the end cap heat source inlet valve, and the end cap heat source outlet valve are interlocked with the temperature sensor to the control system.

4. The filtration device for separating lactide as described in claim 1, characterized in that: The cylinder is equipped with a liquid level sensor, and the feed inlet is equipped with a feed valve. The liquid level sensor and the feed valve are interlocked to the control system.

5. A filtration device for separating lactide as described in claim 1, characterized in that: The bottom of the cylinder is provided with a mother liquor outlet.

6. The filtration device for separating lactide as described in claim 1, characterized in that: The discharge port is connected to a discharge valve via a pipe, and the discharge valve is a heated plunger valve.

7. A filtration device for separating lactide as described in claim 1, characterized in that: The filter screen has a size of 2*10mm.

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