A duplex bag filter apparatus

Abstract

The utility model discloses a kind of duplex bag filtering equipment for lithium iron phosphate positive electrode production, the equipment includes: main body;Filtering cylinder is coaxially arranged in main body;One bottom deslagging mechanism is reversibly arranged at the bottom of filtering cylinder, the mechanism has the closing state of sealing connection and the opening state of gap connection;One self-rotatable cleaning device;And a control system.When the pressure difference of equipment feed inlet and discharge port exceeds preset threshold value, control system automatically switches bottom deslagging mechanism from closing state to opening state, and simultaneously starts cleaning device.Impurities and waste liquid generated by cleaning are directly discharged through the opened bottom deslagging mechanism.The utility model can automatically, efficiently complete the online cleaning and deslagging of filter, significantly shorten cleaning time, improve production efficiency, and avoid material waste caused by blockage, especially suitable for large-scale continuous production line.

Description

Technical Field

[0001] This utility model relates to the technical field of battery cathode material production equipment, and in particular to a double-bag filtration device for lithium iron phosphate cathode production. Background Technology

[0002] The cathode material is the most expensive component in a lithium-ion battery, and its performance directly determines key indicators such as energy density, cycle life, and safety. Lithium iron phosphate cathode materials have gained widespread application in power batteries and energy storage due to their advantages such as structural stability, high safety performance, long cycle life, and relatively low cost.

[0003] In the industrial production of lithium iron phosphate cathode materials, the solid-phase mixing method is the most mainstream process route. The wet preparation stage of this process typically includes premixing, dispersion, primary grinding, secondary grinding, slurry iron removal, and spray drying. To ensure slurry purity and prevent impurities introduced during feeding or grinding media (such as zirconium balls) from the grinding equipment from entering downstream processes, almost every process unit is followed by a double-bag filter. However, with continuous optimization of production processes, such as increasing the solid content of the slurry to improve production efficiency, the overall viscosity of the slurry has increased significantly. Existing traditional double-bag filters are prone to clogging when faced with such high-solids, high-viscosity slurries. Once clogged, the only solution is to stop the machine, have operators manually remove the filter top cover, remove the internal filter bags for cleaning or replacement, and then reinstall them. This method is time-consuming and labor-intensive, severely disrupting the rhythm of continuous production, wasting valuable production time, and leading to significant consumption of human resources and unavoidable slurry loss during the cleaning process.

[0004] Therefore, how to provide a filtration device that can automatically and efficiently clean itself to solve the problems of frequent filter clogging, time-consuming manual cleaning, and impact on production cycle in existing technologies has become a technical challenge that urgently needs to be solved in this field. Utility Model Content

[0005] The purpose of this invention is to provide a dual-bag filtration device for the production of lithium iron phosphate cathodes, in order to solve the technical problem mentioned in the background art that requires time-consuming manual cleaning due to filter clogging, which affects production efficiency and causes resource waste.

[0006] This utility model provides a dual-bag filtration device, comprising:

[0007] The main body has a receiving cavity, with a feeding port at the top and a discharging port at the bottom;

[0008] The filter cartridge is coaxially arranged in the receiving cavity, with its top connected to the feed inlet and its side wall having a filter surface for intercepting impurities in the slurry to be filtered.

[0009] The bottom slag discharge mechanism is rotatably installed at the bottom of the filter cylinder, and has a closed state that is sealed to the bottom of the filter cylinder and an open state that is gapped to the bottom of the filter cylinder.

[0010] A cleaning device, installed inside the receiving cavity, is capable of self-rotating to clean the filter surface and / or the bottom slag discharge mechanism;

[0011] The control system is connected to the bottom slag discharge mechanism and the cleaning device respectively. It can control the bottom slag discharge mechanism to switch between open and closed states based on the pressure difference between the discharge port and the inlet, and start the cleaning device to discharge impurities when the bottom slag discharge mechanism is in the open state.

[0012] Optionally, the bottom slag discharge mechanism includes an electric motor and a butterfly-shaped flap installed at the bottom of the filter cylinder. The electric motor is connected to the control system and can drive the butterfly-shaped flap to rotate to switch between the closed and open states.

[0013] Optionally, the butterfly petal includes a skeleton and a filter fixed to the skeleton.

[0014] Optionally, the mesh size of the filter screen is greater than or equal to the mesh size of the filter surface.

[0015] Optionally, when the bottom slag discharge mechanism is in the open state, the butterfly-shaped petals are inclined at an angle of 80° to 90° with the horizontal plane.

[0016] Optionally, pressure sensors are installed at the feed inlet and the discharge outlet, and each pressure sensor is connected to the control system signal. When the pressure difference between the feed inlet and the discharge outlet exceeds a preset threshold, the control system controls the bottom slag discharge mechanism to switch to the open state.

[0017] Optionally, the cleaning device includes: a rotatable spray head; a turbine disposed inside the spray head and connected to a high-pressure water source; and an output shaft connecting the turbine and the spray head; wherein the turbine can rotate under the fluid impact of the high-pressure water source and drive the spray head to rotate through the output shaft.

[0018] Optionally, a cleaning valve is installed at the outlet of the high-pressure water source. The cleaning valve is connected to the control system signal. When the pressure difference between the inlet and outlet exceeds a preset threshold, the control system opens the cleaning valve synchronously.

[0019] Optionally, the preset threshold is 0.5MPa, the cleaning valve is a pneumatic valve with an opening pressure ≥0.3MPa, and the turbine speed is 60-80r / min.

[0020] Optionally, the end of the discharge port is also connected to a first branch and a second branch arranged in parallel. The first branch is provided with a discharge valve connected to the discharge port, and the second branch is provided with a slag discharge valve connected to the slag discharge port. The discharge valve and the slag discharge valve are respectively connected to the control system signal. When the bottom slag discharge mechanism is in the closed state, the control system controls the discharge valve to open. When the bottom slag discharge mechanism is in the open state, the control system controls the slag discharge valve to open.

[0021] Based on the technical content disclosed in this utility model, the following beneficial effects are achieved:

[0022] This utility model provides a double-bag filter for lithium iron phosphate cathode production. By incorporating an automatically opening and closing bottom slag discharge mechanism at the bottom of the filter cartridge, coupled with an automated cleaning device, it changes the traditional method of manual disassembly and cleaning of filters. When the equipment becomes clogged or requires preventative cleaning according to a preset program, the equipment can automatically complete the entire cleaning process without stopping. This shortens cleaning and maintenance time and ensures continuous and stable operation of the production line. Simultaneously, the highly efficient automatic cleaning capability enables high-frequency preventative cleaning, effectively avoiding severe clogging caused by excessive filter cake buildup. This fundamentally guarantees product yield, reduces material waste, and lowers labor intensity, achieving significant economic benefits in terms of production efficiency, labor costs, and material revenue.

[0023] Other features and advantages of the present invention will become clear from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the present invention and, together with their description, serve to explain the principles of the present invention.

[0025] Figure 1 This is a schematic diagram of the structure of a filtration device provided in an embodiment of the present utility model.

[0026] Figure 2 This is a top view of a filtration device provided in an embodiment of the present utility model.

[0027] Figure 3 This is a schematic diagram of a filter cylinder structure provided for an embodiment of the present utility model.

[0028] Figure 4 This is a schematic diagram of the structure of the butterfly-shaped petals at the bottom of the filter cylinder in an embodiment of this utility model.

[0029] Figure 5 This is a cross-sectional view of the internal structure of the cleaning device in an embodiment of this utility model.

[0030] Explanation of reference numerals in the attached drawings: 1. Pressure gauge; 2. Blind flange; 3. Main body; 4. Filter cylinder; 41. Circular steel ring; 42. Support rod; 5. Filter cloth bag; 6. Butterfly flap; 7. Butterfly valve flange; 8. Electric butterfly valve; 9. Water inlet; 10. Cleaning valve; 11. Breathing valve; 12. Rotary spray device; 121. Spray head; 121a. Spray hole; 121b. Cavity; 122. Turbine; 123. Output shaft; 124. Base; 13. Feed inlet; 14. Discharge outlet; 15. Discharge valve; 16. Discharge port; 17. Slag discharge valve; 18. Slag discharge port. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0032] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0033] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0034] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0036] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. When referring to a dual-bag filter device, it usually refers to a device composed of two identical individual filter units connected in parallel, which can be switched via valves for online maintenance. The structure and working principle of a single filter unit will be described in detail below; this principle also applies to dual-bag devices composed of parallel units.

[0037] Please see Figures 1 to 4 This utility model provides a double-bag filtration device. The device mainly includes a main body 3, a filter cartridge 4 disposed inside the main body 3, a cleaning device for cleaning the filter cartridge 4, and a control system for automated control (not shown in the figure). The overall design of the device aims to achieve rapid switching between filtration and automatic online cleaning modes.

[0038] Combination Figures 1 to 2 The equipment is topped with a removable blind flange 2, serving as the equipment's top cover. The blind flange 2 integrates several functional components, including: a pressure gauge 1 for real-time monitoring of the equipment's internal pressure; a water inlet 9 for connecting to the cleaning water source; a breather valve 11 for balancing the internal and external pressures of the equipment; and a rotating spray device 12 as the cleaning unit. The water inlet 9 is connected to an external pure water pipeline via a cleaning valve 10. The opening and closing of the cleaning valve 10 controls the start and end of the entire cleaning process. The cleaning valve 10 is a pure water pneumatic valve with an opening pressure ≥0.3MPa.

[0039] The main body 3 is a cylindrical structure with a receiving cavity. Its top area is sealed by a blind flange 2 and receives the lithium iron phosphate slurry to be filtered through an inlet 13. In this embodiment, for easy connection with production line pipelines, the inlet 13 is specifically located on the side wall of the upper section of the main body. An outlet 14 is provided at its lower part. Downstream of the outlet 14, two branches branch off via pipes and valves: one controlled by a discharge valve 15 and leading to a discharge port 16, used to discharge qualified slurry during normal production; the other controlled by a slag discharge valve 17 and leading to a slag discharge port 18, used to discharge waste liquid containing filter residue during cleaning mode. To adapt to the weakly acidic and high particulate matter environment of the lithium iron phosphate slurry, the main body 3 and all internal components in contact with the slurry are preferably lined with polytetrafluoroethylene (PTFE), or directly made of high-grade corrosion-resistant materials such as 316L stainless steel.

[0040] Combination Figure 3 and Figure 4 The filter cartridge 4 is the core component for material filtration. It is coaxially installed within the receiving cavity of the main body 3, with its top connected to the feed inlet 13 of the main body. The filter cartridge 4 has a rigid structure, with its frame consisting of two circular steel rings 41 and multiple longitudinal support rods 42 to ensure structural stability even under the impact of high-viscosity slurries. The sides of the frame are wrapped with filter cloth bags 5 of a specific mesh size, forming the filter surface.

[0041] The key innovation of this utility model lies in the bottom structure of the filter cylinder 4. Unlike the closed bottom of traditional filter bags, it employs a bottom slag discharge mechanism that can be flipped up and installed at the bottom of the filter cylinder 4 for sealing and opening. In a preferred embodiment, this mechanism is an electric butterfly valve 8 driven by an electric actuator, its valve body precisely connected to the butterfly valve flange 7 at the bottom of the main body 3. Here, the electric actuator can be understood as a drive device connected to the control system signal, such as a motor with a rotating output shaft. The butterfly flap 6 is the opening and closing element of the electric butterfly valve 8, which can rotate under the drive of the electric actuator to achieve a closed state with a sealed connection to the bottom of the filter cylinder 4, and an open state forming a slag discharge gap with the bottom of the filter cylinder 4. (Refer to...) Figure 4The butterfly-shaped valve 6 has a specially designed structure; it is not a traditional solid valve plate. It comprises a reinforced frame consisting of a circular skeleton and a cross-shaped skeleton, on which filter screens or filter cloth materials (filter cloth bags 5 with a specific mesh size can be selected) are fixed. The outer side of the circular skeleton of the butterfly-shaped valve 6 can also be covered with a sealing ring made of EPDM rubber or similar material to ensure a tight fit with the bottom of the filter cylinder when closed, achieving a reliable seal. Preferably, the mesh size of the filter screen on the butterfly-shaped valve 6 is greater than or equal to the mesh size of the filter surface, which makes the butterfly-shaped valve not only a sealing element but also a filtration barrier when closed.

[0042] The cleaning device is a rotary spray device 12, which is installed on the blind plate 2 at the top of the equipment and connected to the water inlet 9 (see...). Figure 1 Specifically, the rotary spray device 12 mainly consists of a rotary joint and a rotatable spray head 121. The rotary joint (its specific structure is not shown in the figure) is connected between the fixed water inlet 9 at the top of the device and the upper central water inlet of the spray head 121, and its function is to allow high-pressure water to flow from the stationary pipe into a rotatable spray head.

[0043] Please see Figure 5 The rotary spray device 12 also includes a base 124 as a mounting base, on which the spray head 121 is rotatably mounted. To achieve a stable and reliable rotary connection, the upper part of the base 124 is provided with an inner ring groove, and the bottom of the spray head 121 is correspondingly provided with an annular flange, which is rotatably embedded in the inner ring groove.

[0044] The spray head 121 has an internal cavity 121b, on which multiple water spray holes 121a are evenly distributed. A turbine 122 is installed at the bottom of the cavity 121b to drive the spray head to rotate. The function of the water spray holes 121a is that, in automatic cleaning mode, after the high-pressure cleaning fluid enters the rotating spray device 12 from the inlet 9, it forms a 360° high-pressure water flow without dead angles. Its working principle is as follows: when the high-pressure cleaning fluid impacts the turbine 122, the turbine rotates at high speed, and transmits its rotational power to the spray head 121 through an output shaft 123, thereby driving the spray head to perform 360° rotational cleaning. Preferably, the turbine speed can reach 60-80 r / min to achieve efficient all-around rinsing.

[0045] Equipment workflow: The workflow of this equipment is fully automatically controlled by a control system (such as a PLC, not shown in the figure), which is mainly divided into filtration mode and cleaning mode.

[0046] Filtering mode:

[0047] During normal production, the equipment is in filtration mode. The control system controls the bottom slag discharge mechanism (i.e., electric butterfly valve 8) to close the butterfly flap 6, thereby sealing the bottom of the filter cylinder. Simultaneously, the control system opens the discharge valve 15 on the first branch and closes the slag discharge valve 17 on the second branch. Lithium iron phosphate slurry enters through the inlet 13 and is directly injected into the filter cylinder 4. Under the pressure of the delivery pump, the qualified clean slurry passes through the filter surface and the filter screen inside the butterfly flap 6, entering the gap between the main body 3 and the filter cylinder 4. This gap connects to the outlet 14, and the material flows out from the outlet 14 through the discharge port 16 of the first branch, proceeding to the next process. Larger impurities in the slurry are effectively trapped inside the filter cylinder 4.

[0048] Automatic Cleaning Mode: As the filtration process continues, intercepted impurities gradually accumulate on the inner surface of the filter, forming a filter cake layer. This leads to a significant increase in filtration resistance, manifested as a continuous rise in the pressure difference between the inlet 13 and the outlet 14. This equipment is equipped with pressure sensors (not shown in the figure) at both the inlet 13 and the outlet 14. These pressure sensors are connected to the control system signal to monitor the pressure difference in real time. When the pressure difference exceeds a preset alarm threshold (e.g., 0.5 MPa), the control system determines that the filter is clogged and automatically triggers the cleaning mode, executing the following series of chain actions:

[0049] a) The control system first closes the discharge valve 15 on the first branch and simultaneously opens the slag discharge valve 17 on the second branch, switching the material flow of the equipment from the discharge port 16 to the slag discharge port 18.

[0050] b) Next, the control system sends a signal to the electric actuator of the bottom sludge discharge mechanism, causing the butterfly flap 6 to rotate to the open state. In a preferred embodiment, the butterfly flap 6 rotates to an angle of 80°-90° with the horizontal plane. This angle is optimized to form a completely unobstructed sludge discharge channel, allowing the viscous filter cake to slide smoothly out under its own weight and the combined action of the subsequent water flow.

[0051] c) Subsequently, the control system synchronously opens the cleaning valve 10, and high-pressure cleaning fluid (e.g., pure water with a pressure of not less than 0.3 MPa) is injected into the rotary spray device 12 from the inlet 9. The powerful water flow impacts its internal turbine, causing the spray head to rotate at high speed (e.g., reaching 60 r / min or more), forming a 360° high-pressure water flow without dead angles, which powerfully backwashes the filter surface. The intercepted impurities and filter cake layer are rapidly peeled off and detached from the filter cloth surface under the impact of the powerful water flow.

[0052] d) The detached filter residue is discharged from the equipment along with the cleaning fluid through the opened slag discharge channel and slag discharge port 18, and can be collected and treated uniformly by an external container.

[0053] e) After the cleaning process has lasted for a preset time (e.g., 5 minutes), the control system closes the cleaning valve 10 and stops spraying. After a short wait for the waste liquid to be basically drained, the electric butterfly valve 8 rotates in the opposite direction to close the butterfly flap 6, the slag discharge valve 17 closes, and the material discharge valve 15 reopens. At this point, the equipment automatically returns to the initial filtration mode, and a complete fully automatic cleaning and slag discharge cycle ends.

[0054] Example 1

[0055] The equipment using this invention has a main body 3 with a diameter of 500mm and a cylindrical section with a height of 1100mm. The internal filter cylinder 4 has a keel diameter of 200mm and a height of 700mm, and its filter surface uses an 80-mesh screen. The bottom butterfly valve 6 is controlled by an electric butterfly valve 8 with a diameter of 180mm and is sealed with a rubber ring. After the equipment runs continuously on the lithium iron phosphate production line for one day, the differential pressure reaches the alarm value, and it automatically switches to the cleaning mode. The discharge valve closes, the slag discharge valve opens, the butterfly valve opens, and the top rotating spray device starts spraying for 5 minutes. The entire cleaning process, including valve switching and discharge time, lasts for a total of 7 minutes. After sedimentation and drying, 4.5Kg of impurities and dry material contained in the discharged waste slurry are removed.

[0056] Comparative Example

[0057] The conventional double-bag filter, with the same main body and filter cartridge dimensions as in Example 1, and the filter bag 5 using an 80-mesh screen, lacks any automatic cleaning function. After running continuously for one day under the same conditions, the equipment showed obvious signs of blockage, requiring manual shutdown for cleaning. Preparatory work, such as disassembling the filter top cover and lifting the filter bags, took approximately 11 minutes. Cleaning the accumulated material inside the filter bags with tools such as a high-pressure water gun took approximately 4 minutes. Reinstalling the filter bags and top cover after cleaning took approximately 7 minutes, for a total downtime of 22 minutes. The cleaned-out accumulated material, after drying, weighed 4.9 kg.

[0058] The comparison shows that the equipment using this invention significantly reduces the cleaning time per cycle from 22 minutes manually to 7 minutes automatically, while maintaining a cleaning effect essentially the same as manual cleaning. This makes high-frequency preventative cleaning possible, thereby fundamentally avoiding severe material blockage, ensuring production continuity, and significantly saving labor costs and material losses.

[0059] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A double-bag filtration device, characterized in that, include: The main body has a receiving cavity, with a feeding port at the top and a discharging port at the bottom; A filter cartridge is coaxially disposed in the receiving cavity, with its top communicating with the feed inlet and its sidewall having a filter surface for intercepting impurities in the slurry to be filtered. The bottom slag discharge mechanism is rotatably disposed at the bottom of the filter cylinder, and has a closed state that is sealed to the bottom of the filter cylinder and an open state that is gapped to the bottom of the filter cylinder. A cleaning device, disposed within the receiving cavity, is capable of rotatably cleaning the filter surface and / or the bottom slag discharge mechanism; The control system is connected to the bottom slag discharge mechanism and the cleaning device respectively. It can control the bottom slag discharge mechanism to switch between open and closed states based on the pressure difference between the discharge port and the inlet port, and start the cleaning device to discharge impurities when the bottom slag discharge mechanism is in the open state.

2. The double-bag filter device according to claim 1, characterized in that, The bottom slag discharge mechanism includes an electric motor and a butterfly-shaped petal installed at the bottom of the filter cylinder. The electric motor is connected to the control system and can drive the butterfly-shaped petal to rotate to switch between the closed state and the open state.

3. The double-bag filter device according to claim 2, characterized in that, The butterfly-shaped petals include a skeleton and a filter screen fixed to the skeleton.

4. The double-bag filter device according to claim 3, characterized in that, The mesh size of the filter screen is greater than or equal to the mesh size of the filter surface.

5. The double-bag filter device according to claim 2, characterized in that, When the bottom slag discharge mechanism is in the open state, the butterfly-shaped petals are inclined at an angle of 80° to 90° with the horizontal plane.

6. The double-bag filter device according to claim 1, characterized in that, Pressure sensors are installed at the feed inlet and the discharge outlet, and each pressure sensor is connected to the control system. When the pressure difference between the feed inlet and the discharge outlet exceeds a preset threshold, the control system controls the bottom slag discharge mechanism to switch to the open state.

7. The double-bag filter device according to claim 6, characterized in that, The cleaning device includes: Rotatable spray head; A turbine disposed inside the spray head and connected to a high-pressure water source; and The output shaft connects the turbine to the spray head; The turbine can rotate under the fluid impact of the high-pressure water source and drive the spray head to rotate through the output shaft.

8. The double-bag filter device according to claim 7, characterized in that, A cleaning valve is installed at the outlet of the high-pressure water source. The cleaning valve is connected to the control system. When the pressure difference between the inlet and the outlet exceeds the preset threshold, the control system opens the cleaning valve simultaneously.

9. The double-bag filter device according to claim 8, characterized in that, The preset threshold is 0.5MPa, the cleaning valve is a pneumatic valve with an opening pressure ≥0.3MPa, and the turbine speed is 60-80r / min.

10. The double-bag filter device according to claim 1, characterized in that, The end of the discharge port is also connected to a first branch and a second branch arranged in parallel. The first branch is provided with a discharge valve connected to the discharge port, and the second branch is provided with a slag discharge valve connected to the slag discharge port. The discharge valve and the slag discharge valve are respectively connected to the control system signal. When the bottom slag discharge mechanism is in the closed state, the control system controls the discharge valve to open; when the bottom slag discharge mechanism is in the open state, the control system controls the slag discharge valve to open.

Images