A flash drying and cooling structure for polyvinylidene fluoride (PVDF)

Abstract

This utility model relates to the field of polyvinylidene fluoride (PVDF) production technology, specifically disclosing a PVDF flash drying discharge cooling structure, including a bag filter. The upper outlet of the bag filter is connected to an induced draft fan I, and the lower part of the bag filter has an inlet pipe. Bags are installed inside the bag filter, and a discharge valve is located at the bottom of the bag filter, with a hopper connected below the discharge valve. A return air pipe is connected between the induced draft fan I and the outlet of the bag filter. A dehumidifier and an induced draft fan II are connected in series on the return air pipe. The outlet of the induced draft fan II is connected to the lower part of the bag filter through a pipe. The air from the induced draft fan II and the air from the inlet pipe enter the same chamber within the bag filter and mix. This utility model's technical solution can reduce the temperature and humidity in the collection chamber to a certain extent, lower the temperature of the deposited material, and reduce the impact of high internal temperature of the powder during the discharge process on the material's anti-aging properties.

Description

Technical Field

[0001] This utility model relates to the field of polyvinylidene fluoride (PVDF) production technology, specifically a flash drying and cooling structure for PVDF. Background Technology

[0002] In recent years, polyvinylidene fluoride (PVDF) has been increasingly widely used in lithium battery materials, engineering plastics, coatings, insulating materials, ion exchange membrane materials, and filter elements. With the expansion of the PVDF market and the extension of downstream applications, the importance of PVDF's antioxidant and aging resistance indicators has increased, as these indicators directly affect the service life of subsequent finished products. To improve the quality of PVDF products, the company has organized technical personnel to conduct in-depth research on improving the antioxidant and aging resistance of PVDF products.

[0003] In the production of polyvinylidene fluoride (PVDF) powder, the material discharged from the polymerization reactor needs to be washed with deionized water and filtered to remove impurities such as reaction aids. The filtered material then needs to be crushed and dried using a flash dryer to remove excess moisture. The flash dryer works by using hot air to subject the material to intense shearing, blowing, and rotation, causing it to be micronized through centrifugal force, shearing, and collision friction, thus enhancing mass and heat transfer. The material enters the dryer through a screw feeder, where it is dispersed under the intense action of a high-speed rotating agitator due to impact, friction, and shearing. Lumps are rapidly crushed, and the material comes into full contact with the hot air, becoming heated and dried. The dehydrated powder rises with the hot air and is collected by a cyclone separator for any undried or large pieces, then returned to the bottom of the dryer for further crushing and drying. The dried material is then carried by the airflow into a bag filter for collection and packaging.

[0004] During the drying process, the material is heated by hot air and the moisture is removed. When the material enters the bag filter and exits from the bottom outlet of the bag filter into the packaging barrel, there is still some residual heat. In addition, the heat dissipation of the packaging barrel is relatively poor, which leads to a longer heat accumulation time inside the packaging, which to some extent affects the aging resistance of the final product. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a flash drying and cooling structure for polyvinylidene fluoride.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A flash drying and cooling structure for polyvinylidene fluoride (PVDF) includes a baghouse dust collector. An induced draft fan I is connected to the upper outlet of the baghouse dust collector. An inlet pipe is located at the lower part of the baghouse dust collector. Bags are installed inside the baghouse dust collector. A discharge valve is located at the bottom of the baghouse dust collector, and a hopper is connected below the discharge valve. A return air pipe is connected between the induced draft fan I and the outlet of the baghouse dust collector. A dehumidifier and an induced draft fan II are connected in series on the return air pipe. The outlet of the induced draft fan II is connected to the lower part of the baghouse dust collector via a pipe. The air from the induced draft fan II and the air from the inlet pipe enter the same chamber within the baghouse dust collector and mix.

[0008] Furthermore, a heater is connected in parallel on the duct between the dehumidifier / cooler and the induced draft fan II on the return air duct. An electric butterfly valve I is installed at the outlet of the heater, and an electric butterfly valve II is connected in series on a section of the return air duct connected in parallel with the heater. With this design, when the outlet air temperature of the dehumidifier / cooler is too low, a portion of the air can be heated by the heater, preventing water vapor condensation at the outlet of the bag filter due to excessively low air temperature.

[0009] Furthermore, the bag filter dust collector is equipped with a bag assembly. The upper part of the bag assembly is a clean air chamber, and the lower part is a material collection chamber. The lower part of the material collection chamber is a funnel section with an opening at the bottom connected to a discharge valve. The outlet of the induced draft fan II is connected to the material collection chamber through a pipe. This design mixes the cooled air with the incoming air, reducing the material temperature inside the bag filter dust collector.

[0010] Furthermore, an annular cooling air inlet pipe is provided at the upper position of the funnel section in the collection chamber on the outer wall of the bag filter. Multiple air inlets are evenly arranged on the cooling air inlet pipe, and the air inlets open into the collection chamber and face downwards. The downward-facing air inlets can keep the cooling air in the lower position as much as possible, so that the deposited material is in a low-temperature environment, which is conducive to improving the cooling effect.

[0011] Furthermore, a downward-facing baffle is provided at the air inlet of the cooling air inlet duct, with the lower edge of the baffle extending downwards beyond the height of the air inlet. The air outlet of the cooling air inlet duct blows onto the inclined surface of the funnel section in the collection chamber. Blowing the air onto the inclined surface can accelerate the dispersion of the low-temperature air, achieving a uniform air distribution effect within a certain range.

[0012] Furthermore, the dehumidifier is equipped with a refrigerant pipeline for refrigerant circulation, and a filter screen for blocking floating water droplets is provided at the air outlet of the dehumidifier. The outer surface of the filter screen is sealed to the inner wall of the dehumidifier. A drain pipe is provided at the bottom of the dehumidifier, and a drain pump and a drain valve are connected in series on the drain pipe.

[0013] The dehumidifier / cooler has a funnel-shaped bottom with the drain pipe positioned at the lowest point. The upper end of the filter screen slopes upstream of the airflow, while the lower end of the filter screen is located on the inclined surface of the funnel-shaped portion at the bottom of the dehumidifier / cooler. This design allows for better collection of condensate and prevents suspended droplets from entering downstream pipes.

[0014] Compared with the prior art, the beneficial effects of this utility model are as follows: the clean air coming out of the bag filter is sent back to the bag filter through the induced draft fan II, without affecting the air volume of the entire system. By cooling and dehumidifying the return air, the air temperature and moisture content in the air are reduced. The cooled and dehumidified return air enters the lower collection chamber of the bag filter and mixes with the incoming air, which can reduce the temperature and humidity in the collection chamber to a certain extent, reduce the temperature of the deposited material, reduce the impact of the high temperature inside the powder in the discharge stage on the anti-aging performance of the material, and improve the drying effect of the material to a certain extent. The heater can effectively control the temperature of the return air and prevent water vapor from condensing in the bag filter due to the low temperature of the return air. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of this utility model;

[0016] Figure 2 A schematic diagram of the cooling air inlet duct and its vent structure.

[0017] In the diagram: 1. Baghouse dust collector; 2. Exhaust fan I; 3. Bag assembly; 4. Discharge valve; 5. Hopper; 6. Return air duct; 7. Dehumidifier and cooler; 8. Exhaust fan II; 9. Clean air chamber; 10. Collection chamber; 12. Cooling air inlet duct; 13. Baffle; 14. Heater; 15. Electric butterfly valve I; 16. Electric butterfly valve II; 17. Refrigerant pipeline; 18. Filter screen; 19. Drain pipe; 20. Drain pump; 21. Drain valve. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0019] Please see Figure 1 and Figure 2 A flash drying and cooling structure for polyvinylidene fluoride (PVDF) includes a bag filter 1. The upper outlet of the bag filter 1 is connected to an induced draft fan 12. An inlet pipe is located at the lower part of the bag filter 1. A bag assembly 3 is installed inside the bag filter 1. The upper part of the bag assembly is a clean air chamber 9, and the lower part is a collection chamber 10. The lower part of the collection chamber 10 is a funnel section with an opening at the bottom connected to a discharge valve 4. The lower part of the discharge valve 4 is connected to a hopper 5. The bag assembly 3 includes a partition with multiple round holes machined on it. The outer surface of the upper end of the bag opening is tightly fitted against the round holes.

[0020] A return air duct 6 is connected to the pipeline between the induced draft fan I2 and the outlet of the bag filter 1. A dehumidifier and a dehumidifier 7 and an induced draft fan II8 are connected in series on the return air duct 6. The outlet of the induced draft fan II8 is connected to the lower collection chamber 10 of the bag filter 1 via a pipeline. The air from the induced draft fan II8 and the air from the inlet duct enter the collection chamber 10 of the bag filter 1 and mix. To ensure more uniform airflow in the return air duct 6 and to concentrate the cooler air in the lower part of the collection chamber 10, a ring-shaped cooling inlet duct 12 is installed on the outer wall of the bag filter 1 at the corresponding position above the funnel section inside the collection chamber 10. Multiple air inlets are evenly arranged on the cooling inlet duct 12, opening into the collection chamber 10 and facing downwards. To prevent powder from entering the air inlets, a downward-facing baffle 13 is installed at the air inlet of the cooling inlet duct 12 inside the collection chamber 10, with the lower edge of the baffle 13 extending downwards beyond the height of the air inlet. The air vents can also be continuous annular vents with air distribution plates featuring multiple air outlets. In this case, the baffle 13 is a continuous annular baffle. During manufacturing, the lower edge of the vertical portion of the main body shell of the collecting chamber 10 can be extended downwards to form the baffle 13. The height of the cooling air inlet pipe 12 is designed so that the exhaust air blows onto the inclined surface of the funnel section inside the collecting chamber 10. Blowing the exhaust air onto the inclined surface accelerates the dispersion of the low-temperature air, achieving a uniform air distribution effect within a certain range.

[0021] To adjust the temperature of the air returning to the bag filter 1 through the return air duct 6, a heater 14 is connected in parallel to the duct between the dehumidifier / cooler 7 and the induced draft fan II 8. An electric heater is preferred. An electric butterfly valve I 15 is installed at the outlet of the heater 14, and an electric butterfly valve II 16 is connected in series on a section of the return air duct 6 connected in parallel with the heater 14. This allows a portion of the air to be heated by the heater 14 when the outlet air temperature of the dehumidifier / cooler 7 is too low, mixing with the air exiting the dehumidifier / cooler 7, thereby regulating the outlet air temperature at the end of the return air duct 6.

[0022] The dehumidifier 7 is equipped with a refrigerant pipe 17 for refrigerant circulation. To save energy, the refrigerant can be the return water from the -35℃ cold water pipe used for cooling materials in polyvinylidene fluoride production. The outlet air temperature of the dehumidifier 7 is controlled by controlling the cold water flow and air flow. A filter screen 18 is installed at the air outlet of the dehumidifier 7 to block floating water droplets. The outer surface of the filter screen 18 is sealed to the inner wall of the dehumidifier 7. A drain pipe 19 is provided at the bottom of the dehumidifier 7, and a drain pump 20 and a drain valve 21 are connected in series on the drain pipe 19. To facilitate the discharge of condensate, the bottom of the dehumidifier 7 is funnel-shaped, the drain pipe 19 is located at the lower position, the upper end of the filter screen 18 is inclined towards the upstream of the airflow, and the lower end of the filter screen 18 is located on the inclined surface of the funnel-shaped part at the bottom of the dehumidifier 7.

[0023] In operation, the induced draft fan II8 is turned on, and part of the clean air discharged from the bag filter 1 enters the return air duct 6. It then passes through the dehumidifier and cooler 7 for cooling and removal of some moisture. The opening of the electric butterfly valves I15 and II16 is controlled to adjust the mixing ratio of cold air and hot air from the heater 14, thereby adjusting the temperature of the air entering the bag filter 1 at the end of the return air duct 6. The cooler air in the return air duct 6 enters the collection chamber 10 evenly through the cooling inlet duct 12, mixing with the incoming air from bottom to top. This keeps the deposited powder in a lower-temperature environment, reducing the temperature of the material in the packaging drum and mitigating the impact of high temperatures on the product's anti-aging properties to some extent. Of course, this embodiment also requires temperature and humidity sensors to be installed in the collection chamber 10 of the bag filter 1, at the end of the return air duct 6, and at the outlet of the heater 14 to obtain real-time temperature and humidity information at key locations. This is conventional technology and will not be elaborated further.

[0024] The above are merely preferred embodiments of this utility model, but the scope of protection of this utility model is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this utility model, based on the technical solution and inventive concept of this utility model, should be included within the scope of protection of this utility model.

Claims

1. A flash drying and cooling structure for polyvinylidene fluoride (PVDF) includes a bag filter, an induced draft fan I connected to the upper outlet of the bag filter, an inlet pipe at the lower part of the bag filter, a bag assembly inside the bag filter, and a discharge valve at the bottom of the bag filter, with a hopper connected to the lower part of the discharge valve, characterized in that: A return air duct is connected to the pipeline between the induced draft fan I and the air outlet of the bag filter. A dehumidifier and induced draft fan II are connected in series on the return air duct. The air outlet of induced draft fan II is connected to the lower part of the bag filter through a pipeline. The air outlet of induced draft fan II and the air inlet of the inlet duct enter the same chamber in the bag filter and mix with each other.

2. The polyvinylidene fluoride flash drying outlet cooling structure according to claim 1, characterized in that: A heater is connected in parallel between the dehumidifier and the induced draft fan on the return air duct. An electric butterfly valve I is installed at the air outlet of the heater, and an electric butterfly valve II is connected in series on a section of the return air duct that is connected in parallel with the heater.

3. The polyvinylidene fluoride flash drying outlet cooling structure according to claim 1, characterized in that: The bag filter dust collector is equipped with a bag assembly. The upper part of the bag assembly is a clean air chamber, and the lower part is a material collection chamber. The lower part of the material collection chamber is a funnel. The bottom of the funnel is open and connected to a discharge valve. The air outlet of the induced draft fan II is connected to the material collection chamber through a pipe.

4. The polyvinylidene fluoride flash drying outlet cooling structure according to claim 3, characterized in that: The outer wall of the bag filter dust collector is provided with an annular cooling air inlet pipe at the upper position of the funnel part in the collection chamber. Multiple air inlets are evenly arranged on the cooling air inlet pipe, and the air inlets open into the collection chamber and face downwards.

5. The polyvinylidene fluoride flash drying discharge cooling structure according to claim 4, characterized in that: The cooling air inlet pipe has a downward baffle at its air outlet, with the lower edge of the baffle extending downward beyond the height of the air outlet. The air outlet of the cooling air inlet pipe blows onto the inclined surface of the funnel section in the collection chamber.

6. The polyvinylidene fluoride flash drying outlet temperature reducing structure according to claim 1, characterized in that: The dehumidifier is equipped with a refrigerant pipeline for refrigerant circulation. The air outlet of the dehumidifier is equipped with a filter screen to block floating water droplets. The outer surface of the filter screen is sealed to the inner wall of the dehumidifier. The bottom of the dehumidifier is equipped with a drain pipe, and a drain pump and a drain valve are connected in series on the drain pipe.

7. The polyvinylidene fluoride flash drying outlet cooling structure according to claim 6, characterized in that: The bottom of the dehumidifier is funnel-shaped, the drain pipe is located at the lower position, the upper end of the filter screen is inclined towards the upstream of the airflow, and the lower end of the filter screen is located on the inclined surface of the funnel-shaped part at the bottom of the dehumidifier.

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