Filtering device and filtering method for an underwater dicer

Abstract

This invention discloses a filtration device and method for an underwater pelletizer, relating to the field of pellet recycling technology. The filtration device includes a housing, a rinsing assembly, a conveying frame, a first filtration assembly, and a second filtration assembly. The rinsing assembly sprays primary filtrate collected from the first filtration assembly or external clean water onto the first filtration assembly and rinses the first filter residue from the first filtration assembly onto the conveying frame. The second filtration assembly filters the rinsing liquid conveyed by the conveying frame into secondary filtrate and a second filter residue. The second filtration assembly includes a second filter cylinder, an extrusion shaft, and a second filtration motor. The second filtration motor drives the extrusion shaft to rotate around a first direction to extrude the second filter residue from the second filter cylinder. This invention solves the problem of poor wastewater filtration in existing underwater pelletizer filtration devices.

Description

Technical Field

[0001] This invention relates to the field of granule recycling technology, and in particular to a filtration device and filtration method for an underwater pelletizer. Background Technology

[0002] Underwater pelletizers are key equipment in polymer (such as plastics and rubber) granulation production. They introduce molten polymer strips into an underwater cooling medium for simultaneous cooling and cutting, forming regular pellets. During this process, the cooling water (usually temperature-controlled process water) comes into direct contact with the high-temperature material, inevitably carrying away some fine particles (commonly known as "water powder"), low-molecular-weight precipitates, processing aids (such as lubricants and antioxidants), and trace metal shavings generated by cutting abrasion, forming process wastewater containing complex pollutants.

[0003] In existing technologies, traditional filtration devices for underwater pelletizers generally employ primary filtration systems, such as fixed screens or bag filters. Their main purpose is to recover pellets with larger particle sizes (typically >0.5mm) and prevent them from entering the wastewater system and causing economic losses. However, because the wastewater is only filtered once, the filtered water still contains a significant amount of waste residue, resulting in poor filtration efficiency.

[0004] It is evident that the existing underwater pelletizer filtration devices suffer from poor wastewater filtration performance. Summary of the Invention

[0005] The purpose of this invention is to provide a filtration device and filtration method for an underwater pelletizer, which solves the problem of poor wastewater filtration effect in the existing underwater pelletizer filtration devices.

[0006] To achieve this objective, the present invention adopts the following technical solution: According to a first aspect, the present invention provides a filtration device for an underwater pelletizer, comprising a housing, a rinsing assembly, a first filtration assembly, and a second filtration assembly. A conveying frame is provided between the first filtration assembly and the second filtration assembly. The rinsing assembly is used to spray primary filtrate collected from the first filtration assembly or external clean water onto the first filtration assembly and to rinse the first filter residue retained by the first filtration assembly onto the conveying frame. The second filtration assembly is used to filter the rinsing liquid conveyed by the conveying frame into secondary filtrate and second filter residue. The conveyor frame has a liquid outlet at one end near the second filter assembly. The second filter assembly includes a second filter cylinder, an extrusion shaft, and a second filter motor. The second filter motor is used to drive the extrusion shaft to rotate around a first direction to extrude the second filter residue in the second filter cylinder.

[0007] Optionally, the first filter assembly includes a first filter cartridge and a first filter motor. The first filter cartridge is rotatably connected inside the housing, and the first filter motor is installed on the outer wall of the housing and is used to drive the first filter cartridge to rotate around a third direction. The first direction, the second direction, and the third direction are perpendicular to each other.

[0008] Optionally, the first filter cartridge includes a first filter housing, on which a plurality of filter screens are mounted circumferentially. The plurality of filter screens are used to be alternately rinsed by primary filtrate sprayed by the rinsing assembly or external clean water according to the rotational movement of the first filter housing around a third direction. The end of the conveyor frame away from the second filter assembly is embedded in the first filter housing, and the conveyor frame is fixedly connected to the housing.

[0009] Optionally, the conveyor frame includes a first conveying section, a second conveying section, and a connecting section, wherein the first conveying section is connected to the second conveying section and is used to convey the rinsing liquid after the first filter component has been rinsed; The connecting section is fastened to the housing by screws or welding, a portion of the first conveying section is inserted into the first filter housing, and the liquid outlet is located in the second conveying section.

[0010] Optionally, the housing is provided with a reflux assembly, which is used to return the primary filtrate filtered by the first filtration assembly to the conveyor frame.

[0011] Optionally, the reflux assembly includes a reflux nozzle and a reflux pipe communicating with the reflux nozzle. The reflux nozzle is installed at the end of the conveyor frame away from the liquid outlet, and the reflux pipe is installed at the bottom of the conveyor frame and is used to reflux the primary filtrate filtered by the first filtration assembly.

[0012] Optionally, the rinsing assembly includes a spray support, a spray pipe, and nozzles. The spray pipe is mounted on the spray support, which is fixedly connected to the housing. A plurality of nozzles are arranged in a straight line and mounted on the spray pipe. The nozzles are used to spray the primary filtrate in the spray pipe onto the first filtration assembly.

[0013] Optionally, the height of each nozzle along the second direction is higher than the height of the first filter assembly along the second direction. A first cover and a second cover are sequentially installed on the housing. The first cover is used to cover the first filter assembly and the rinsing assembly, and the second cover is used to cover the second filter assembly.

[0014] Optionally, the housing is provided with a first cavity and a second cavity. The first cavity is used to contain the primary filtrate filtered by the first filter assembly, and the second cavity is used to contain the waste raw liquid injected by the inlet and the secondary filtrate filtered by the second filter assembly. The outer wall of the housing is fixed with an inclined guide plate, which is used to receive the second waste residue extruded by the extrusion shaft.

[0015] According to a second aspect, the present invention provides a filtration method applied to the filtration device of the underwater pelletizer described in the first aspect, comprising: Step S1: The waste raw liquid after being filtered by the first filter component or external clean water is sprayed onto the first filter component through the rinsing component to rinse the first filter residue trapped by the first filter component onto the conveyor frame. In step S2, the rinsing liquid is conveyed to the second filter assembly via the conveyor frame, and the rinsing liquid flows from the outlet of the conveyor frame into the inlet of the second filter cylinder by gravity; the height of the outlet along the second direction is higher than the height of the inlet along the second direction. Step S3: Filter the incoming rinsing liquid in the second filter cartridge to obtain secondary filtrate and second filter residue retained in the second filter cartridge. Step S4: The second filter motor drives the extrusion shaft to rotate around the first direction to extrude the second filter residue inside the second filter cylinder.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a filtration device and method for an underwater pelletizer. By setting up a conveyor frame, an orderly fluid transport channel is established between the first and second filter components, ensuring that the primary filtrate, after preliminary treatment by the first filter component, can be smoothly and controllably introduced into the second filter component for secondary treatment. This structure avoids liquid splashing or short-circuiting during the filtration process, ensuring the continuity and stability of the two-stage filtration process, thereby improving the reliability and processing efficiency of the entire filtration device. A combined design of the second filter cylinder and extrusion shaft is adopted. Driven by a second filter motor, the extrusion shaft rotates around a first direction, actively and mechanically extruding the filter residue from the second filter cylinder, achieving automatic cleaning and collection of the filter residue. By setting the height of the liquid outlet on the conveyor frame along the second direction to be higher than the height of the liquid inlet on the second filter cylinder, a clever structure utilizing the gravitational potential energy of the liquid is formed to assist the flow. This height difference allows the primary filtrate to form a natural liquid level difference and smooth flow direction when flowing from the conveyor frame to the second filter cylinder, reducing impurity adhesion near the liquid inlet, further optimizing the liquid transfer process, and improving the smoothness and energy efficiency of the system operation. Therefore, the present invention solves the problem of poor wastewater filtration effect in the filtration device of the underwater pelletizer in the prior art. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0019] Figure 1 This is a three-dimensional structural schematic diagram of a filtration device for an underwater pelletizer provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the internal structure of a filtration device for an underwater pelletizer provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the rinsing component and the first filter component in a filtration device of an underwater pelletizer provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the second filter component in the filter device of an underwater pelletizer provided in an embodiment of the present invention; Figure 5 This is a first cross-sectional structural schematic diagram of a filtration device for an underwater pelletizer provided in an embodiment of the present invention; Figure 6 This is a second cross-sectional structural diagram of a filtration device for an underwater pelletizer provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the conveyor frame and reflux assembly in the filtration device of an underwater pelletizer provided in an embodiment of the present invention; Figure 8 for Figure 5 A magnified structural diagram at point A; Figure 9 This is a flowchart illustrating a filtering method provided in an embodiment of the present invention.

[0020] Illustration: 10. Casing; 11. First cover; 12. Second cover; 13. First cavity; 14. Second cavity; 15. Slag guide plate; 16. Support wheel; 17. Liquid inlet; 20. Flushing assembly; 21. Spraying support; 22. Spraying pipe; 23. Nozzle; 30. First filter assembly; 31. First filter cartridge; 311. First filter housing; 312. Filter screen; 313. Scraper; 32. First filter motor; 40. Second filter assembly; 41. Second filter cartridge; 411. Liquid inlet; 42. Extrusion shaft; 43. Second filter motor; 50. Conveyor frame; 51. First conveyor section; 511. First conveyor trough; 512. Baffle; 52. Second conveyor section; 521. Liquid outlet; 522. Second conveyor trough; 53. Connecting section; 60. Recirculation assembly; 61. Recirculation nozzle; 62. Recirculation pipe. Detailed Implementation

[0021] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the connection.

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] The first aspect of this invention provides a filtration device for an underwater pelletizer, such as... Figures 1 to 8 As shown, it includes a housing 10, a rinsing assembly 20, a first filter assembly 30, and a second filter assembly 40. A conveyor frame 50 is provided between the first filter assembly 30 and the second filter assembly 40. The rinsing assembly 20 is used to spray the primary filtrate or external clean water after the first filter assembly 30 filters the waste raw liquid onto the first filter assembly 30, and to rinse the first filter residue trapped by the first filter assembly 30 onto the conveyor frame 50. The second filter assembly 40 is used to filter the rinsing liquid conveyed by the conveyor frame 50 into a secondary filtrate and a second filter residue. The conveyor frame 50 is provided with a liquid outlet 521 at one end near the second filter assembly 40. The second filter assembly 40 includes a second filter cylinder 41, an extrusion shaft 42 and a second filter motor 43. The second filter motor 43 is used to drive the extrusion shaft 42 to rotate around a first direction to extrude the second filter residue in the second filter cylinder 41. The second filter cartridge 41 is provided with an inlet hole 411 corresponding to the outlet hole 521. The height of the outlet hole 521 along the second direction is higher than the height of the inlet hole 411 along the second direction. The first direction and the second direction are perpendicular to each other. In this embodiment, the second direction is the direction of gravity. The primary filtrate is the liquid filtered by the first filter assembly 30, and the waste liquid is the waste liquid produced by the underwater pelletizer. The plastic particles of the waste liquid can be recovered through the filtration device of this embodiment.

[0025] It should be noted that the filtration device for an underwater pelletizer provided by this invention establishes an orderly fluid transport channel between the first filter assembly 30 and the second filter assembly 40 through the setting of the conveyor frame 50. This ensures that the rinsing liquid after the first filter assembly 30 is rinsed by the rinsing assembly 20 can be smoothly and controllably introduced into the second filter assembly 40 for secondary treatment. This structure avoids liquid splashing or short-circuiting in the filtration process, ensuring the continuity and stability of the two-stage filtration process, thereby improving the reliability and processing efficiency of the entire filtration device. The combined design of the second filter cylinder 41 and the extrusion shaft 42, driven by the second filter motor 43 to rotate the extrusion shaft 42 around a first direction, actively and mechanically extrudes the filter residue from the second filter cylinder 41, realizing automatic cleaning and collection of the filter residue. By setting the height of the liquid outlet 521 on the conveyor frame 50 along the second direction to be higher than the height of the liquid inlet 411 on the second filter cylinder 41, a clever structure is formed that utilizes the gravitational potential energy of the liquid to assist the flow. This height difference allows the primary filtered liquid to form a natural liquid level difference and smooth flow direction when flowing from the conveyor frame 50 to the second filter cylinder 41, reducing the adhesion of impurities near the liquid inlet 411, further optimizing the liquid transfer process, and improving the smoothness and energy efficiency of the system operation. Therefore, this invention solves the problem of poor wastewater filtration effect in the existing underwater pelletizer filtration device.

[0026] like Figures 2 to 7 As shown, the first filter assembly 30 includes a first filter cartridge 31 and a first filter motor 32. The first filter cartridge 31 is rotatably connected inside the housing 10. The first filter motor 32 is mounted on the outer wall of the housing 10 and is used to drive the first filter cartridge 31 to rotate around a third direction. The first direction, the second direction, and the third direction are perpendicular to each other. In this embodiment, a support wheel 16 is rotatably connected inside the housing 10 and rolls in contact with the first filter cartridge 31.

[0027] In specific implementation, the first filter cylinder 31 is driven by the first filter motor 32 to rotate around a third direction, so that the first-stage filtration process changes from static interception to dynamic sieving. The centrifugal force generated by the rotation helps to accelerate the liquid through the filter screen 312 and enables the intercepted first filter residue to be evenly distributed and agitated on the cylinder wall, effectively preventing the filter residue from accumulating rapidly in a localized area and clogging the filter screen. This achieves synchronous self-cleaning during the filtration process, greatly improving the efficiency and continuity of primary filtration. This embodiment clearly defines that the first direction (the direction of movement of the extrusion shaft 42), the second direction (the direction of gravity), and the third direction (the direction of rotation of the first filter cylinder 31) are mutually perpendicular. This orthogonal spatial motion relationship design ensures that the arrangement of the driving components, the natural flow direction of the liquid, and the core motion of the filter element do not interfere with each other and work together efficiently. As a result, the structure of the entire filtration device is optimally planned in three-dimensional space, which is not only reasonable in layout and direct in transmission, but also greatly improves the space utilization of the equipment, making the overall device more compact.

[0028] The rotating first filter cartridge 31, while filtering, also agitates and disperses the incoming waste liquid. This not only more effectively breaks up materials that may clump together, ensuring that particles of all sizes contact the filter screen more evenly and improving interception efficiency, but also serves as an active pretreatment step, providing a more stable primary filtrate in terms of flow rate and impurity distribution for the subsequent second-stage fine filtration. This enhances the synergistic treatment effect of the entire two-stage filtration system and the stability of the final effluent quality. Designing the first-stage filtration as a motor-driven rotary mechanical structure, combined with the automatic filtration and sludge removal function of the second filter component 40, constitutes a highly automated filtration system. This reduces reliance on manual intervention, lowers the risk of unplanned downtime due to filter screen clogging, and makes the entire process from primary recovery to large particle removal, fine filtration of small impurities, and finally, filter cake discharge, smoother and more reliable, meeting the needs of modern continuous production.

[0029] like Figures 1 to 5 As shown, the first filter cylinder 31 includes a first filter shell 311, and a plurality of filter screens 312 are installed around the first filter shell 311. The plurality of filter screens 312 are used to be alternately rinsed by the primary filtrate sprayed by the rinsing assembly 20 or external clean water according to the rotational movement of the first filter shell 311 around a third direction. The end of the conveying frame 50 away from the second filter assembly 40 is embedded in the first filter shell 311, and the conveying frame 50 is fixedly connected to the housing 10. In this embodiment, a scraper 313 arranged along a third direction is fixedly installed on the inner side of the first filter shell 311. With the setting of the scraper 313, when the first filter cylinder 31 rotates for filtration, the scraper 313 can drive part of the first filter residue to move. Then, through the rinsing action of the rinsing assembly 20, the first filter residue in the first filter cylinder 31 is rinsed into the conveying frame 50.

[0030] In practical implementation, by installing several filter screens 312 circumferentially around the first filter housing 311, and having the filter screens 312 alternately receive waste liquid for filtration as the first filter housing 311 rotates, this design creates a work-standby cycle. While some filter screens 312 are performing filtration tasks, others are in a state of being disconnected from the liquid flow or can be rinsed. This alternating working mechanism effectively avoids rapid saturation and clogging caused by the continuous operation of a single filter screen 312, allowing the filtration, draining, and even preliminary cleaning processes to be carried out cyclically during rotation. This eliminates the operational interruptions caused by shutdown for sludge removal in traditional filtration, achieving uninterrupted, continuous, and efficient filtration. Since one end of the conveyor frame 50 is embedded in the first filter housing 311, and the conveyor frame 50 is fixedly connected to the housing 10, this design forms a clever combination of movement and stillness: the rotating first filter housing 311 and the fixed conveyor frame 50 generate relative movement. After the first filter residue is effectively separated inside the filter screen 312, the primary filtrate enters the housing 10, and the first filter residue can be washed into the conveyor frame 50 by the rinsing component 20, thus realizing the rapid and orderly separation of the filtration product (first filter residue) from the rotating filter component.

[0031] like Figures 2 to 7 As shown, the conveyor frame 50 includes a first conveying section 51, a second conveying section 52, and a connecting section 53. The first conveying section 51 is connected to the second conveying section 52 and is used to convey the rinsing liquid after the first filter assembly 30 has been rinsed. The connecting section 53 is fastened to the housing 10 by screws or welding. A portion of the first conveying section 51 is inserted into the first filter housing 311, and the liquid outlet 521 is located in the second conveying section 52. In this embodiment, the first conveying section 51, the second conveying section 52, and the connecting section 53 are integrally formed. The first conveying section 51 has a first conveying groove 511, and the second conveying section 52 has a second conveying groove 522 that communicates with the first conveying groove 511 and the liquid outlet 521, respectively. The first conveying section 51 is arranged along a third direction, and the second conveying section 52 is arranged along a first direction. The first conveying groove 511 is inclined, and the height of the end of the first conveying groove 511 away from the second conveying groove 522 is higher than the height of the end of the first conveying groove 511 near the second conveying groove 522, so that the primary filtrate in the first conveying groove 511 automatically flows to the second conveying groove 522 under gravity.

[0032] In practical implementation, since part of the first conveying section 51 is inserted into the rotating first filter shell 311, the first conveying section 51 can immediately and closely receive the rinsing liquid flushed from the filter screen 312. This directly embedded collection method minimizes liquid splashing or leakage, ensuring that the rinsing liquid containing the first filter residue is efficiently and completely captured and introduced into the conveying system, providing a stable flow basis for subsequent treatment. Due to the interconnected design of the first conveying tank 511 and the second conveying tank 522, and their precise docking with the liquid outlet 521, a complete and smooth internal conveying channel is formed from the collection point to the discharge point. The liquid has low flow resistance and no dead zones in the channel, effectively preventing particulate matter deposition and liquid stagnation, ensuring the continuity and thoroughness of the conveying, and creating ideal conditions for smooth flow out from the liquid outlet 521 by gravity. The first conveying section 51 is arranged along a third direction (the arrangement direction of the first filter cylinder 31), and the second conveying section 52 is arranged along a first direction (the arrangement direction of the extrusion shaft 42). This design cleverly utilizes the internal space of the device; it coordinates the conveying path with the rotation direction of the filter and the direction of the slag extrusion movement, achieving efficient use of space. This makes the layout of the entire filter device extremely compact and reasonable, reduces unnecessary pipe bends, and is conducive to the compactness and integration of the equipment.

[0033] like Figure 2 and Figure 7 As shown, a reflux assembly 60 is provided inside the housing 10. The reflux assembly 60 is used to return the primary filtrate filtered by the first filter assembly 30 to the conveyor frame 50. The reflux assembly 60 includes a reflux nozzle 61 and a reflux pipe 62 communicating with the reflux nozzle 61. The reflux nozzle 61 is installed at the end of the conveyor frame 50 away from the liquid outlet 521, and the reflux pipe 62 is installed at the bottom of the conveyor frame 50 and is used to return the primary filtrate filtered by the first filter assembly 30. In this embodiment, a reflux pump communicating with the reflux pipe 62 is installed inside the housing 10. By setting the reflux pump, the reflux power is provided for the primary filtrate filtered by the first filter assembly 30. A baffle 512 is provided on the first conveying section 51 to block the reflux nozzle 61 and is located in the first conveying trough 511.

[0034] In practice, by directly injecting the return liquid (primary filtrate) into the interior of the conveyor frame 50 (especially through the return nozzle 61 located at the far end), an additional internal circulation or disturbance can be formed within the conveying tank. This artificially introduced fluid dynamics breaks the "dead zone" that may be caused by laminar flow in one direction, causing the liquid to generate a moderate turbulence or stirring effect during the conveying process. This effectively suspends and carries away any fine particulate impurities that may deposit, thereby significantly reducing the risk of impurities depositing, accumulating, or even clogging at the bottom or corners of the conveyor frame 50, ensuring the long-term unobstructed flow of the conveying channel. The injection of the return liquid also serves to mix and homogenize the rinsing liquid within the conveyor frame 50 online. This can harmonize any local differences or fluctuations in the concentration, temperature, or composition of the rinsing liquid, making the liquid state in the inlet hole 411 of the second filter cartridge 41 more uniform and stable. This provides better and more predictable feeding conditions for the second-stage fine filtration, helping the second filter assembly 40 maintain stable and efficient filtration performance, thereby improving the overall quality of the final secondary filtrate and the stability of the system's treatment effect. This backflow not only acts as a physical stirrer, but its convergence with the main liquid flow also helps maintain a more stable and continuous fluid dynamic throughout the entire transport path. This makes the process of the liquid being collected from the first filter element 30, transported, and then flowing into the second filter element 40 by gravity smoother and more natural, reducing flow obstruction and improving the smoothness and energy efficiency of the entire filtration process.

[0035] Furthermore, the reflux assembly 60 selects to reflux the primary filtrate, providing operators with flexible means to adjust the internal conditions of the conveyor frame 50. For example, refluxing the primary filtrate can perform a certain degree of "self-cleaning" inside the conveyor frame 50; adjusting the reflux ratio under specific operating conditions can optimize the internal flow pattern or material concentration. This flexibility allows the device to better adapt to changes in different contaminant characteristics or production loads. The reflux pipe 62 is directly installed at the bottom of the conveyor frame 50, forming an integrated or tightly integrated structure with the conveyor frame 50. This design achieves the aforementioned important fluid optimization functions through simple piping connections without increasing additional space occupation or complexity, demonstrating ingenious structural design and functional integration, and significantly improving the reliability and performance of the system at a lower cost.

[0036] like Figure 2 and Figure 3As shown, the rinsing assembly 20 includes a spray support 21, a spray pipe 22, and nozzles 23. The spray pipe 22 is mounted on the spray support 21, which is fixedly connected to the housing 10. Several nozzles 23 are arranged in a straight line and mounted on the spray pipe 22. The nozzles 23 are used to spray the primary filtrate in the spray pipe 22 onto the first filter assembly 30. In this embodiment, the nozzles 23 are used to spray the primary filtrate in the spray pipe 22 at an angle onto the filter screen 312. The primary filtrate in the housing 10 is pumped into the spray pipe 22 by an external water pump. In this embodiment, the installation angle of the nozzles 23 can be adjusted according to the actual rinsing conditions and is not limited here.

[0037] In practical implementation, by using several nozzles 23 arranged in a straight line, the waste liquid can be evenly covered in one or more parallel liquid streams to cover a specific working area of ​​the first filter component 30 (such as filter screen 312). This design avoids uneven load on the filter screen 312 caused by single-point or local spraying, effectively utilizes the effective filtration area of ​​the filter screen 312, and prevents local overload or underutilization, thereby significantly improving the uniformity and stability of the primary filtration treatment.

[0038] Because nozzle 23 sprays the primary filtrate at an angle onto the first filter assembly 30, this angled impact method has multiple advantages: First, the angle of inclination can decompose the impact force, reducing vertical impact damage to the filter screen 312; second, the angled spray can generate a forward shearing and spreading force on the high-temperature viscous molten polymer strips or pre-cooled strips, which helps to disperse them and better mix them with cooling water, promoting preliminary solidification and granulation; third, combined with the rotational motion of the first filter cylinder 31, the liquid flow from the angled spray can form a better interaction with the cylinder wall, enhancing the "washing" and solid-liquid separation effect on the material, creating favorable conditions for producing a purer primary filtrate. The spray pipe 22 is integrated on the spray support 21, and multiple nozzles 23 are arranged in a straight line. This structural layout is clear and the pipeline is simple; it not only facilitates manufacturing and installation, but also makes the operation more intuitive and convenient when cleaning or replacing specific nozzles 23 is required. At the same time, the precise and controllable spraying method helps to reduce the ineffective spraying or splashing of waste raw liquid, saving materials and energy to a certain extent, reflecting the rationality and economy of the design.

[0039] like Figures 1 to 6As shown, the height of each nozzle 23 along the second direction is higher than the height of the first filter assembly 30 along the second direction. A first cover 11 and a second cover 12 are sequentially installed on the housing 10. The first cover 11 is used to cover the first filter assembly 30 and the rinsing assembly 20, and the second cover 12 is used to cover the second filter assembly 40. The housing 10 is provided with an inlet 17, a first cavity 13, and a second cavity 14 communicating with the inlet 17. The first cavity 13 is used to contain the primary filtrate filtered by the first filter assembly 30, and the second cavity 14 is used to contain the waste raw liquid injected by the inlet 17 and the secondary filtrate filtered by the second filter assembly 40. An inclined guide plate 15 is fixed on the outer wall of the housing 10. The guide plate 15 is used to receive the second waste residue extruded by the extrusion shaft 42.

[0040] In practical implementation, by setting the height of each nozzle 23 along the second direction to be higher than that of the first filter assembly 30, the waste liquid gains better pouring kinetic energy under gravity assistance, enhancing the spray coverage and penetration effect. Simultaneously, this height difference forms a natural liquid level barrier, effectively preventing backflow of filtrate or water vapor into the spray system due to pressure fluctuations during filtration. The first cover 11 and the second cover 12 independently cover the first filter assembly 30 and the second filter assembly 40 respectively. This partitioned encapsulation design physically separates the two core stages of the filtration process, forming a clear maintenance unit. When it is necessary to inspect, clean, or repair a certain stage of the filter component, only the corresponding cover can be opened without exposing and affecting the entire system. This not only greatly facilitates maintenance operations and shortens downtime but also effectively isolates internal moving parts from the water vapor environment, improving operator safety and equipment protection levels. The casing 10 is divided into a first cavity 13 and a second cavity 14, which are used to collect the primary and secondary filtrates, respectively. The second cavity 14 provides an entry space for the waste raw liquid, allowing both the waste raw liquid and the secondary filtrate to smoothly enter the first filter cartridge 31. This physically separated collection method achieves immediate and thorough separation of solid waste and clean filtrate, avoiding mixing and secondary pollution. It enables the valuable pelleted product (large particles in the first filter residue) to be dried and recovered, resulting in a clear and orderly internal logistics flow, significantly improving resource recovery rate and on-site management level.

[0041] It should also be noted that an inclined guide plate 15 is fixedly connected to the outer wall of the housing 10. The guide plate 15 is used to receive the second waste residue extruded from the second filter assembly 40. The second waste residue is recycled plastic granules. The inclined plate surface automatically guides the waste residue to a designated collection container or area by gravity, realizing the directional recycling of waste residue.

[0042] A second aspect of this invention provides a filtration method applied to the filtration device of the underwater pelletizer described in the first aspect, such as... Figure 9 As shown, it includes: Step S1: The waste raw liquid after being filtered by the first filter assembly 30 is sprayed into the first filter assembly 30 through the flushing assembly 20, so as to flush the first filter residue trapped by the first filter assembly 30 to the conveyor frame 50. In step S2, the rinsing liquid is conveyed to the second filter assembly 40 via the conveyor frame 50, and the rinsing liquid flows into the inlet hole 411 of the second filter cylinder 41 from the outlet hole 521 of the conveyor frame 50 by gravity; the height of the outlet hole 521 along the second direction is higher than the height of the inlet hole 411 along the second direction. Step S3: The rinsing liquid flowing in is filtered in the second filter cylinder 41 to obtain secondary filtrate and second filter residue retained in the second filter cylinder 41. In this embodiment, the secondary filtrate enters the second cavity 14 and then follows the waste liquid into the first filter cylinder 31. The filtered primary filtrate enters the first cavity 13. In step S4, the second filter motor 43 drives the extrusion shaft 42 to rotate around the first direction to extrude the second filter residue in the second filter cylinder 41; wherein the first direction and the second direction are perpendicular to each other.

[0043] It should be noted that step S1 uses its own primary filtrate to backwash the first filter element 30, effectively removing the first filter residue accumulated on its surface, preventing clogging, ensuring the continuous and efficient operation of the first-stage filtration, and reducing the frequency of downtime for cleaning. Step S2 clearly stipulates that the flushing liquid flows from the higher outlet hole 521 to the lower inlet hole 411 by gravity. This method does not require additional pumping power; it only relies on the natural liquid level difference to achieve a stable and continuous transport of liquid between the two filter elements. This not only simplifies the system structure and reduces energy consumption but also avoids turbulence or impurity breakage that may be caused by power transport, ensuring the stability and reliability of the filtration process. Step S4 controls the second filter motor 43 to drive the extrusion shaft 42 to rotate, which can actively and mechanically expel the second filter residue accumulated in the second filter cylinder 41. This periodic or timed automatic cleaning method completely solves the problem of easy clogging of filter elements and the need for frequent manual cleaning in traditional filtration, ensuring the continuous and efficient operation of the second-stage filtration and significantly improving the automation level and maintenance efficiency of the entire filtration device.

[0044] Working Principle: The filtration device and method for an underwater pelletizer provided by this invention establishes an orderly fluid transport channel between the first filter assembly 30 and the second filter assembly 40 through the setting of the conveyor frame 50. This ensures that the rinsing filtrate after the first filter assembly 30 is rinsed by the rinsing assembly 20 can be smoothly and controllably introduced into the second filter assembly 40 for secondary treatment. This structure avoids liquid splashing or short-circuiting in the filtration process, ensuring the continuity and stability of the two-stage filtration process, thereby improving the reliability and processing efficiency of the entire filtration device. A combined design of the second filter cylinder 41 and the extrusion shaft 42 is adopted. The second filter motor 43 drives the extrusion shaft 42 to rotate around a first direction, which actively and mechanically extrudes the filter residue from the second filter cylinder 41, realizing automatic cleaning and collection of the filter residue. By setting the height of the liquid outlet 521 on the conveyor frame 50 along the second direction to be higher than the height of the liquid inlet 411 on the second filter cylinder 41, a clever structure is formed that utilizes the gravitational potential energy of the liquid to assist the flow. This height difference allows the primary filtered liquid to form a natural liquid level difference and smooth flow direction when flowing from the conveyor frame 50 to the second filter cylinder 41, reducing the adhesion of impurities near the liquid inlet 411, further optimizing the liquid transfer process, and improving the smoothness and energy efficiency of the system operation. Therefore, this invention solves the problem of poor wastewater filtration effect in the existing underwater pelletizer filtration device.

[0045] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A filtration device for an underwater pelletizer, characterized in that, The device includes a housing (10), a rinsing assembly (20), a first filter assembly (30), and a second filter assembly (40). A conveyor frame (50) is provided between the first filter assembly (30) and the second filter assembly (40). The rinsing assembly (20) is used to spray the primary filtrate collected from the first filter assembly (30) or external clean water onto the first filter assembly (30) and to rinse the first filter residue trapped by the first filter assembly (30) onto the conveyor frame (50). The second filter assembly (40) is used to filter the rinsing liquid conveyed by the conveyor frame (50) into a secondary filtrate and a second filter residue. The conveyor frame (50) is provided with a liquid outlet hole (521). The second filter assembly (40) includes a second filter cylinder (41), an extrusion shaft (42), and a second filter motor (43). The second filter motor (43) is used to drive the extrusion shaft (42) to rotate around a first direction. The second filter cylinder (41) is provided with a liquid inlet hole (411) corresponding to the liquid outlet hole (521).

2. The filtration device for the underwater pelletizer according to claim 1, characterized in that, The first filter assembly (30) includes a first filter cartridge (31) and a first filter motor (32). The first filter cartridge (31) is rotatably connected inside the housing (10). The first filter motor (32) is installed on the outer wall of the housing (10) and is used to drive the first filter cartridge (31) to rotate.

3. The filtration device for the underwater pelletizer according to claim 2, characterized in that, The first filter cartridge (31) includes a first filter housing (311), and a plurality of filter screens (312) are installed on the first filter housing (311) along its circumference. The plurality of filter screens (312) are used to be alternately rinsed by the primary filtrate sprayed by the rinsing assembly (20) or external clean water according to the rotational movement of the first filter housing (311) around a third direction. The end of the conveyor frame (50) away from the second filter assembly (40) is embedded in the first filter housing (311), and the conveyor frame (50) is fixedly connected to the housing (10).

4. The filtration device for the underwater pelletizer according to claim 3, characterized in that, The conveyor frame (50) includes a first conveying section (51), a second conveying section (52), and a connecting section (53). The first conveying section (51) is connected to the second conveying section (52) and is used to convey the rinsing liquid after the first filter assembly (30) has been rinsed. The connecting section (53) is fastened to the housing (10) by screws or welding, a portion of the first conveying section (51) is inserted into the first filter housing (311), and the liquid outlet (521) is opened in the second conveying section (52).

5. The filtration device for an underwater pelletizer according to any one of claims 1 to 4, characterized in that, The housing (10) is provided with a reflux assembly (60), which is used to return the primary filtrate filtered by the first filter assembly (30) to the conveyor frame (50).

6. The filtration device for the underwater pelletizer according to claim 5, characterized in that, The reflux assembly (60) includes a reflux nozzle (61) and a reflux pipe (62) communicating with the reflux nozzle (61). The reflux nozzle (61) is installed at one end of the conveyor frame (50) away from the liquid outlet (521). The reflux pipe (62) is installed at the bottom of the conveyor frame (50) and is used to reflux the primary filtrate filtered by the first filter assembly (30).

7. The filtration device for an underwater pelletizer according to any one of claims 1 to 4, characterized in that, The rinsing assembly (20) includes a spray support (21), a spray pipe (22), and a nozzle (23). The spray pipe (22) is mounted on the spray support (21), and the spray support (21) is fixedly connected to the housing (10). A plurality of nozzles (23) are arranged in a straight line and mounted on the spray pipe (22). The nozzles (23) are used to spray the primary filtrate in the spray pipe (22) onto the first filtration assembly (30).

8. The filtration device for the underwater pelletizer according to claim 7, characterized in that, Each of the nozzles (23) is higher in the second direction than the first filter assembly (30) in the second direction. A first cover (11) and a second cover (12) are installed on the housing (10) in sequence. The first cover (11) is used to cover the first filter assembly (30) and the flushing assembly (20), and the second cover (12) is used to cover the second filter assembly (40).

9. The filtration device for the underwater pelletizer according to claim 1, characterized in that, The housing (10) is provided with a liquid inlet (17), a first cavity (13) and a second cavity (14) communicating with the liquid inlet (17). The first cavity (13) is used to contain the primary filtrate filtered by the first filter assembly (30). The second cavity (14) is used to contain the waste raw liquid injected by the liquid inlet (17) and the secondary filtrate filtered by the second filter assembly (40). The outer wall of the housing (10) is fixed with a slag guide plate (15) arranged in an inclined manner. The slag guide plate (15) is used to receive the second waste residue extruded by the extrusion shaft (42).

10. A filtration method, applied to the filtration device of the underwater pelletizer according to any one of claims 1 to 9, characterized in that, include: Step S1: The primary filtrate or external clean water collected from the first filter assembly (30) is sprayed onto the first filter assembly (30) through the rinsing assembly (20) to rinse the first filter residue trapped by the first filter assembly (30) onto the conveyor frame (50). In step S2, the rinsing liquid is conveyed to the second filter assembly (40) via the conveyor (50), and the rinsing liquid flows into the inlet (411) of the second filter cartridge (41) from the outlet (521) of the conveyor (50) by gravity. Step S3: The incoming rinsing liquid is filtered in the second filter cylinder (41) to obtain secondary filtrate and second filter residue retained in the second filter cylinder (41); In step S4, the second filter motor (43) drives the extrusion shaft (42) to rotate around the first direction to extrude the second filter residue in the second filter cylinder (41).

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