A multi-stage dust separation device

Abstract

The utility model relates to the material separation technical field in the waste treatment, especially is the separation and purification device of recycling plastic film. More specifically, it is a dust separation device for plastic film recycling. The device includes a primary selection device for separating large particle impurities and a fine selection device for separating fine particles and dust. The primary selection device uses a feed fan and a circulating fan to send the material into the primary selection bin twice, and the particle impurities are separated from the plastic film through the impact of cyclone; after the material separated by the primary selection device is sent into the fine selection device, the cyclone blower is used to generate cyclone in the fine selection bin while pushing the material to circulate in the fine selection bin continuously until the desired cleanliness is achieved. The device separates large particle impurities through twice cyclone screening of the primary selection device, and further separates fine particles and dust through multiple cyclone circulation of the fine selection device, achieving the purpose of improving the recycling and impurity removal effect and reducing the particle and dust content. The screening effect can be adjusted as needed until the desired cleanliness is achieved.

Description

Technical Field

[0001] This utility model relates to the field of material separation technology in waste treatment, and in particular to a separation and purification device for recycling plastic film. More specifically, it is a multi-stage dust removal and separation device. Background Technology

[0002] The widespread use of plastic film in modern agricultural technology has led to "white pollution" in some areas due to the increasing usage and age of agricultural mulch film, becoming a prominent issue for green agricultural development. Therefore, promoting agricultural film recycling is urgent and important. Agricultural film recycling involves two stages: field collection and subsequent crushing. Field collection primarily involves collecting the film from the fields, performing simple sorting and cleaning, and finally packaging it for later crushing. In the crushing stage, impurities such as plant stalks, sand, and gravel embedded in the waste film must first be removed. Then, a shredder or shearing machine is used to break large pieces of film into smaller fragments. The sand and gravel embedded in the film not only affect the quality of the recycled material but also cause significant damage to the blades of the shredder and shearing machine. My other Chinese patent application, 2022115683049, discloses a "Plastic Film Crushing and Slag Removal Machine," publication number CN115890979A. This crushing and slag removal machine includes a crushing chamber, a cutter assembly installed inside the crushing chamber, and a drive motor driven by the cutter assembly. The crushing chamber has a feed inlet and a discharge outlet. The feed inlet is located at the upper end of the crushing chamber, and the lower end of the crushing chamber connects to a negative pressure chamber. The discharge outlet is located on the side wall of the negative pressure chamber. The cutter assembly is fixedly mounted on the upper end of a central shaft, and the lower end of the central shaft passes through the bottom plate of the negative pressure chamber and is driven by the drive motor. The negative pressure chamber is connected to a negative pressure generating device. This plastic film crushing and slag removal machine is not prone to material jamming, has good crushing effect, high efficiency, and also has a certain ability to separate impurities. However, its impurity separation ability is limited, and it requires high purity of raw materials. Its separation effect on sand and gravel is not ideal. My other Chinese patent application, 2024113358738, discloses a "Spiral Air Screen" (publication number CN118904717A). This spiral air screen includes a cylindrical outer shell, a discharge pipe located at the upper end of the shell, and a feed pipe located on the upper side wall of the shell below the discharge pipe. A vortex-generating disc is installed inside the shell's cavity to form a cyclone. A central pipe connecting the feed pipe is located above the vortex-generating disc, and the vortex-generating disc is connected to a drive mechanism. A booster blower is installed on the feed pipe, and a negative pressure blower is installed on the discharge pipe. This spiral air screen separates impurities through cyclone and centrifugal force, and is used to remove heavier impurities such as sand and gravel from plastic films that have a low specific gravity and are easily suspended in the air. In actual use, although preliminary screening is performed, the weight of impurities mixed in waste plastic film varies greatly. There are large particles of fine sand and gravel that are visible to the naked eye, as well as fine powder or even dust. This spiral air screen, which uses cyclone and centrifugal force to separate impurities, is difficult to separate gravel particles and dust at the same time. If the power of the turbulence plate is too high, dust will easily remain in the processed material. If the power is too low, gravel particles will easily be trapped. Utility Model Content

[0003] The purpose of this invention is to provide a multi-stage dust removal and separation device to further improve the impurity removal effect of recycled waste plastic film, reduce the particle and dust content in the material after impurity removal, and facilitate the reuse of recycled materials.

[0004] The multi-stage dust removal and separation device of this utility model includes a primary screening device for separating large particulate impurities and a secondary screening device for separating fine particles and dust. The secondary screening device includes... The cylindrical cleaning chamber has a cylindrical internal cavity. A cyclone pipe and a material return pipe are inserted through the outer wall of the cleaning chamber. The cyclone pipe is used to introduce external airflow into the internal cavity of the cleaning chamber, and the material return pipe is used to output the airflow from the internal cavity of the cleaning chamber. Multiple cyclone blowers are evenly distributed and fixedly installed at the lower end of the refining chamber, surrounding the axis of the refining chamber. The cyclone blowers provide power for the circulation of airflow. The air outlet of the cyclone blower is connected to the outer end of the cyclone tube, and the air inlet is connected to the outer end of the material return pipe. When the cyclone blower is working, air is drawn out from the inner cavity of the refining chamber through the material return pipe and then blown into the inner cavity of the refining chamber through the cyclone tube. A centrifugal disc is installed at the lower end of the inner cavity of the selection chamber. The centrifugal disc is rotatably mounted on the lower end cover of the selection chamber via a rotating shaft. The centrifugal disc is used to drive the air at the lower end of the inner cavity of the selection chamber to rotate and generate centrifugal force. The inner end of the material return pipe is connected to the upper edge of the centrifugal disc to facilitate the suction of air at the edge of the centrifugal disc. The drive motor is installed outside the selection chamber and is used to drive the centrifuge discs; The feed pipe is installed in the center of the refining bin, with its upper end inserted through the upper cover of the refining bin to feed raw materials into the refining bin. The discharge pipe is coaxially arranged with the feed pipe and located below the feed pipe. The inner diameter of the discharge pipe is larger than the outer diameter of the feed pipe. It is used to receive the raw materials input by the feed pipe. The lower end of the discharge pipe is located above the centrifugal disc and is used to transport the raw materials fed into the discharge pipe to the center of the centrifugal disc. The cyclone guide duct is installed on the inner wall of the fine selection chamber, connecting to the inner end of the cyclone pipe. It extends upward in an arc from the end connected to the cyclone pipe so that the airflow ejected from the upper end of the cyclone guide duct can connect with the upper end of the discharge pipe.

[0005] Through this solution, the centrifugal disc built into the refining device and the external cyclone blower work together to generate an upward spiral airflow in the refining chamber, while a downward airflow is generated in the feed pipe and discharge pipe. This propels the material to circulate continuously up and down and inside and outside the refining chamber. During the circulation process, the combined action of centrifugal force and gravity is used to separate the heavier particles and dust from the lighter waste plastic film, thereby improving the recycling and impurity removal effect and reducing the particle and dust content.

[0006] Preferably, the centrifuge disc is a horizontally arranged disc-shaped structure, with baffles connected and installed on the upper surface of the centrifuge disc. Multiple triangular baffles are evenly distributed around the center of the centrifuge disc, and a rotating shaft is fixedly connected to the center of the lower surface of the centrifuge disc. The rotating shaft is connected to a drive motor for transmission.

[0007] With this solution, when the drive motor rotates the centrifugal disc, it can also rotate the air and material at the center of the centrifugal disc, generating centrifugal force, causing the air and material to move to the periphery of the centrifugal disc, and generating negative pressure at the center of the centrifugal disc.

[0008] Preferably, the inner diameter of the discharge pipe is larger than the outer diameter of the feed pipe, there is a certain gap between the upper end of the discharge pipe and the upper end cover of the selection chamber, and the upper opening of the cyclone guide air duct is lower than the upper end face of the discharge pipe.

[0009] With this solution, materials in both the feed pipe and the discharge pipe can fall onto the centrifugal disc, and materials in the selection chamber that are higher than the discharge pipe will also be sucked into the discharge pipe by negative pressure and fall onto the centrifugal disc.

[0010] Preferably, a screen is fixedly installed in the inner cavity of the selection chamber by a support ring, and there is an interlayer that is vertically connected between the screen and the inner wall of the selection chamber. The lower end of the screen is in clearance fit with the edge of the centrifuge disc. The inner ends of the cyclone pipe and the material return pipe both pass through the interlayer between the screen and the selection chamber and are located inside the screen.

[0011] With this method, the separated particles and dust impurities enter the interlayer and no longer participate in the secondary circulation.

[0012] Preferably, a slag discharge pipe is inserted through the outer wall of the selection chamber below the centrifugal disc; an arc-shaped ramp connecting the slag discharge pipe is provided at the lower end of the interlayer between the screen and the selection chamber.

[0013] This solution allows for the removal of impurities from the interlayer at any time.

[0014] Preferably, the primary selection device includes a cylindrical primary selection chamber, a primary feed pipe and a primary discharge pipe disposed on the side wall of the primary selection chamber. The upper end of the primary selection chamber is equipped with a primary selection chamber cover, and the lower end is equipped with a slag discharge auger. A secondary feed pipe and a discharge pipe are inserted through the side wall of the primary selection chamber. The discharge pipe is located at the top of the primary selection chamber, and its inner end is connected to the inner cavity of the primary selection chamber and located at the highest end of the inner cavity of the primary selection chamber. The outer end of the discharge pipe is connected to the feed pipe of the secondary selection chamber. The secondary feed pipe is located between the primary discharge pipe and the discharge pipe. The inner ends of both the primary feed pipe and the secondary feed pipe extend into the inner cavity of the primary selection chamber and are respectively connected to an inclined upward-extending primary arc-shaped guide plate and a secondary arc-shaped guide plate. The outer end of the primary feed pipe is connected to the outlet of the primary feed fan, the outer end of the secondary feed pipe is connected to the outlet of the circulating fan, the inlet of the circulating fan is connected to the outer end of the primary discharge pipe, the inner end of the primary discharge pipe extends into the inner cavity of the primary selection chamber and is connected to the central pipe longitudinally arranged in the center of the primary selection chamber, the upper end of the central pipe is connected to the primary discharge pipe, and the lower end is connected to the screening hopper with clearance fit, the screening hopper has an inner cavity with a cone-shaped structure that is larger at the top and smaller at the bottom, the lower end of the primary selection chamber is connected to the upper port of the screening hopper, the lower end of the screening hopper is connected to the feed inlet of the slag discharge auger, and the lower end of the central pipe extends into the inner cavity of the screening hopper and is coaxially arranged with the lower port of the screening hopper.

[0015] With this solution, the material before fine selection is separated by a two-in-two-out cyclone screen, which can separate most of the large particle impurities and reduce the burden on the fine selection device.

[0016] Preferably, a U-shaped bend is provided between the outer end of the unloading pipe and the feed pipe of the refining bin, and an induced draft fan is provided at the upper end of the refining bin. The air inlet of the induced draft fan is connected to the U-shaped bend, and the air outlet is connected to the feed pipe.

[0017] This solution allows the U-shaped bend section to act as a gravity sink, which can trap some small particles and dust in the air at the bottom of the U-shaped bend section.

[0018] Preferably, the inner ends of the primary feed pipe and the secondary feed pipe are arranged along the tangent direction of the inner wall of the primary selection chamber. The width direction of the arc-shaped guide plate extends from the primary selection chamber towards the center and covers the diameter of the primary feed pipe or the secondary feed pipe, but is less than one-quarter of the inner diameter of the primary selection chamber. The length direction of the arc-shaped guide plate extends from the inner end of the primary feed pipe or the secondary feed pipe along a spiral upward trajectory of 30 degrees to 120 degrees. The highest point of the arc-shaped guide plate that connects to the primary feed pipe is lower than the inner end of the secondary feed pipe. The outer side of the arc-shaped guide plate is fixedly connected to the inner wall of the primary selection chamber.

[0019] With this solution, the airflow from the primary and secondary feed pipes is ejected along the tangential direction of the inner wall of the refining chamber. Under the combined action of the arc-shaped guide plate and the inner wall of the refining chamber, the airflow mixed with materials forms a spiral upward vortex.

[0020] In summary, the dust removal and separation device for plastic film recycling of this utility model separates large particulate impurities through two cyclone screenings in the initial screening device, and further separates fine particles and dust through multiple cyclone cycles in the fine screening device. This achieves the purpose of improving the recycling and impurity removal effect and reducing the particle and dust content. The screening effect can be adjusted as needed until a satisfactory cleanliness is achieved. Other features and advantages of this utility model will become clear from the following detailed description of exemplary embodiments of this utility model with reference to the accompanying drawings. Attached Figure Description

[0021] 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.

[0022] Figure 1 This is a three-dimensional structural schematic diagram of one embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the internal structure of the selected device after the outer casing has been removed.

[0024] Figure 3 yes Figure 1 A cross-sectional view of the selected device.

[0025] Figure 4 yes Figure 1 BB cross-sectional view of the selected device.

[0026] Figure 5 This is a three-dimensional structural diagram of the centrifugal disc and drive motor.

[0027] Figure 6 This is a schematic diagram of the internal structure of the preliminary selection device after the outer casing has been removed. Figure 7 This is a cross-sectional structural diagram of the central tube, screening hopper, and auger. Detailed Implementation

[0028] It should be noted that the following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use.

[0029] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0030] 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.

[0031] 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.

[0032] like Figure 1 As shown, the multi-stage dust removal and separation device of this utility model includes a primary selection device for separating large particulate impurities and a secondary selection device for separating fine particles and dust. The primary selection device removes large pieces of plant straw, sand, and gravel that are visible to the naked eye from the recycled waste plastic film. The plastic film that is still adhered to by fine particles and dust after preliminary cleaning is transported to the secondary selection device for further screening until the residual impurity index of the plastic film meets the requirements for recycling.

[0033] like Figure 1 , Figure 2 As shown, the refining device includes a cylindrical refining chamber 1, multiple cyclone blowers 2 evenly distributed around the axis of the refining chamber 1 and fixedly installed at the lower end of the refining chamber 1, centrifugal discs 4 installed inside the refining chamber 1, and drive motors 3 for driving the centrifugal discs 4; the refining chamber 1 is welded from metal plates, with an upper end cover and a lower end cover, and has a cylindrical internal cavity, which can be used as follows: Figure 1 The sidewall shown is a multi-segment, modular assembly structure composed of two or three cylinders, or it can be a one-piece structure. The cyclone blower 2 is preferably selected from... Figure 1 , Figure 2 The centrifugal fan shown can also be an axial flow fan; the cyclone blower 2 is evenly distributed around the axis of the selection chamber 1 and fixedly installed at the lower end of the selection chamber 1, providing power for the airflow circulation. The centrifugal disc 4 is horizontally set at the lower end of the selection chamber 1 and is driven to rotate by the drive motor 3. It is used to drive the air at the lower end of the inner cavity of the selection chamber 1 to rotate and generate centrifugal force, which drives the air and material to rotate at high speed at the lower end of the selection chamber 1, generating centrifugal force and pushing the air and material to the surroundings, so that a negative pressure is generated at the center of the centrifugal disc 4. The drive motor 3 is installed outside the selection chamber 1 and is used to drive the centrifugal disc 4. like Figure 2As shown, the center of the refining chamber 1 has a feed pipe 11 and a discharge pipe 12 arranged coaxially and longitudinally, with the feed pipe 11 located above the discharge pipe 12. The upper end of the feed pipe 11 is inserted through the upper end cover 13 of the refining chamber 1, and the lower end is connected to the upper port of the discharge pipe 12. The upper end of the feed pipe 11 is fixedly connected to the upper end cover 13 by welding or flange. The lower end of the feed pipe 11 is inserted into the upper port of the discharge pipe 12. The inner diameter of the discharge pipe 12 is larger than the outer diameter of the feed pipe 11, and the two are fitted with a gap, so that the discharge pipe 12 can both receive the material falling from the feed pipe 11 and absorb the airflow in the inner cavity of the refining chamber through the gap between the two. The lower end of the discharge pipe 12 is located above the centrifugal disc 4, and the central axis of the discharge pipe 12 is located at the central axis of the centrifugal disc 4. It is used to transport the raw materials fed into the discharge pipe 12 to the center of the centrifugal disc 4. The centrifugal disc 4 is rotatably mounted on the lower end cover 14 of the selection chamber 1 via a rotating shaft. The drive motor 3 installed outside the selection chamber 1 drives the rotating shaft and the centrifugal disc 4 to rotate via a belt pulley transmission mechanism, a gear transmission mechanism, or a chain transmission mechanism. Of course, as another embodiment of the present invention, the rotating shaft can also be directly driven to rotate by a variable frequency motor installed at the lower end of the rotating shaft.

[0034] like Figure 1 , Figure 2 As shown, a cyclone pipe 21 and a material return pipe 23 are inserted through the outer wall of the selection chamber 1. The cyclone pipe 21 is used to introduce external airflow into the inner cavity of the selection chamber 1, and the material return pipe 23 is used to output the airflow from the inner cavity of the selection chamber 1. The outer end of the cyclone pipe 21 is connected to the air outlet of the cyclone blower 2, and the inner end is connected to the arc-shaped upward-extending cyclone guide duct 22. The outer end of the material return pipe 23 is connected to the air inlet of the cyclone blower 2, and the inner end is connected to the upper edge of the centrifugal disc 4, so as to draw air from the edge of the centrifugal disc 4.

[0035] The cyclone guide duct 22 can be a pipe with a circular, square, or semi-circular cross-section. Its lower end connects to the inner end of the cyclone pipe 21 and extends obliquely upward in an arc-shaped spiral, with the spiral direction consistent with the rotation direction of the centrifugal disc 4. Figure 2As indicated by the arrow, when the cyclone blower 2 is working, it draws air from the upper edge of the centrifugal disc 4 through the material return pipe 23. The air enters the air inlet of the cyclone blower 2 through the material return pipe 23, and then is blown into the cyclone pipe 21 from the air outlet of the cyclone blower 2. The air blown into the inner cavity of the selection chamber 1 through the cyclone pipe 21 spirals upward along the cyclone guide channel 22 and is finally blown out from the upper end of the cyclone guide channel 22. The airflow blown to the higher position in the inner cavity of the selection chamber 1 either enters the material drop pipe 12 and is transported from top to bottom to the center of the centrifugal disc 4, where it is pushed to the surrounding area by the centrifugal disc 4, or it descends along the outer wall of the material drop pipe 12 to the surrounding area of ​​the centrifugal disc 4. This airflow is then drawn back into the cyclone blower 2 by the material return pipe 23 to enter the next cycle. Three to four sets of cyclone circulation devices, consisting of the cyclone blower 2, cyclone pipe 21, cyclone guide channel 22, and material return pipe 23, are evenly distributed around the central axis of the selection chamber 1. These cyclone circulation devices, when operating simultaneously, can create an upward cyclone within the cavity of the selection chamber 1, while simultaneously generating negative pressure at the lower end of the selection chamber 1, which is the center of the centrifugal disc 4.

[0036] When the selection chamber 1 is working, the material containing impurities is fed into the selection chamber 1 through the upper end of the feed pipe 11. Under the action of gravity, it falls through the discharge pipe 12 to the center of the centrifugal disc 4. At this time, the drive motor 3 and multiple cyclone circulation devices work simultaneously. The centrifugal disc 4 drives the material and air to rotate at high speed, pushing the material and air to the edge of the centrifugal disc 4. At the same time, a negative pressure is generated below the discharge pipe 12. The material and air that have moved to the edge of the centrifugal disc 4 are sucked into the material return pipe 23 by the adsorption of the cyclone circulation device and pass through the material return pipe 23. The plastic film and other materials carried by the airflow are accelerated by the push of the cyclone blower 2, and return to a higher position in the selection chamber 1 through the cyclone pipe 21 and the cyclone guide air channel 22. Under the action of the cyclone in the selection chamber 1, they float and rotate with the wind. During this process, the heavier particles are separated from the plastic film body under the dual action of gravity and centrifugal force. The plastic film falls along the inner wall of the selection chamber 1; dust adhering to the plastic film is also shaken off the plastic film. At this time, a relatively high-pressure area is formed at the upper end of the inner cavity of the selection chamber 1. Under the action of negative pressure at the lower end of the selection chamber 1, most of the plastic film enters the inside of the discharge pipe 12, and a small amount falls along the outer wall of the discharge pipe 12. When the plastic film falling along the outer wall of the discharge pipe 12 reaches the vicinity of the material return pipe 23, it is directly sucked away by the material return pipe 23 and enters the secondary cycle. When the plastic film that has entered the inside of the discharge pipe 12 falls onto the centrifugal disc 4, it is pushed by the rotating centrifugal disc 4 to the material return pipe 23, and then sucked away by the material return pipe 23 and enters the secondary cycle. As described above, as long as the upper cover 13 of the selection chamber 1 remains closed, the centrifugal disc 4 and the cyclone circulation device can drive the plastic film to continuously circulate between the selection chamber 1 and the cyclone blower 2, removing particles and dust until its cleanliness meets the requirements for recycling.

[0037] Furthermore, as a further improvement of this utility model, a screen 5 is fixedly installed in the inner cavity of the selection chamber 1 by a support ring 6, and the screen 5 has a vertically connected interlayer between it and the inner wall of the selection chamber 1. Figure 2 As shown, the screen 5 has a cylindrical structure and is coaxially arranged with the selection chamber 1. The screen 5 is fixedly attached to the inner ring surface of the annular support ring 6, while the chamber wall of the selection chamber 1 is attached to the outer ring surface of the support ring 6, forming a sandwich between the screen 5 and the inner wall of the selection chamber 1. The number of support rings 6 can be flexibly set according to the structural strength requirements. Figure 2 In this embodiment, a support ring 6 is provided at the top, middle, and bottom of the screen 5, and longitudinally arranged support rods 62 are fixedly connected between each support ring 6 to improve the structural strength. When the centrifugal disc 4 and the cyclone circulation device are working, the particulate impurities separated by the cyclone in the selection chamber 1 pass through the screen 5 and enter the interlayer under the action of centrifugal force. The support ring 6 has multiple through holes 61 that run vertically through the layers above and below the support ring 6. These through holes 61 connect the interlayer above and below the support ring 6, allowing particulate impurities above the interlayer to pass through the through holes 61 and settle to the bottom of the interlayer. The lower end of the screen 5 is fitted with the edge of the centrifugal disc 4 with a clearance, so that it can receive the material thrown out when the centrifugal disc 4 rotates without affecting the rotation of the centrifugal disc 4. In this embodiment, the inner ends of the cyclone pipe 21 and the material return pipe 23 both pass through the interlayer between the screen 5 and the selection chamber 1 and are located on the inner side of the screen 5. The cyclone guide channel 22 is fixedly connected to the inner wall of the screen 5.

[0038] like Figure 2 , Figure 5 As shown, the centrifugal disc 4 is a horizontally arranged disc-shaped structure. A baffle 41 is connected and installed on the upper surface of the centrifugal disc 4. Multiple triangular baffles 41 are vertically connected to the centrifugal disc 4 and evenly distributed around its center. A rotating shaft 43 is fixedly connected to the center of the lower surface of the centrifugal disc 4, and the rotating shaft 43 is connected to the drive motor 3. Alternatively, in other embodiments of the invention, the centrifugal disc 4 can also be a corrugated disc with radially arranged corrugated ribs on its upper surface. The function of these centrifugal discs 4 is to drive the air and material at the lower end of the selection chamber 1 to rotate at high speed, generating centrifugal force, pushing the air and material to the surrounding areas, and creating negative pressure at the center of the centrifugal disc 4.

[0039] In addition, such as Figure 5As shown, to facilitate the removal of particulate impurities from the edge of the centrifuge disc 4, an inclined screen 42 is provided along the edge of the centrifuge disc 4. The inclined screen 42 is a conical structure with a large opening at the top and a small opening at the bottom, and is coaxially arranged with the centrifuge disc 4. The lower end of the inclined screen 42 connects to the edge of the centrifuge disc 4, and the upper end expands outward. When a screen 5 is provided in the selection chamber 1, the upper end of the inclined screen 42 connects to the inner sidewall of the lower end of the screen 5. The annular sidewall of the inclined screen 42 with sieve holes is inclined around the centrifuge disc 4. Both the centrifuge disc 4 and the inclined screen 42 are made of metal and can be directly welded or fixed together with screws. When the centrifuge disc 4 rotates, it drives the inclined screen 42 to rotate together. At this time, the upper end of the inclined screen 42 and the lower end of the screen 5 are in clearance fit, and the two are not connected. Alternatively, the inclined screen 42 and the centrifuge disc 4 can be in clearance fit. When the centrifuge disc 4 rotates, the inclined screen 42 remains stationary. In this case, the upper end of the inclined screen 42 can be directly welded to the lower end of the screen 5.

[0040] As a further improvement of this utility model, the inner diameter of the discharge pipe 12 is larger than the outer diameter of the feed pipe 11, and there is a certain gap between the upper end of the discharge pipe 12 and the upper end cover 13 of the selection chamber 1. The upper opening of the cyclone guide channel 22 is lower than the upper end face of the discharge pipe 12. Both the upper and lower ends of the discharge pipe 12 are suspended, and its side wall is fixedly connected to the screen 5 or the inner wall of the selection chamber 1 by a horizontal tie rod 121. The upper end of the cyclone guide channel 22 is slightly lower than the upper end face of the discharge pipe 12, and there is a sufficiently large gap between the upper end face of the discharge pipe 12 and the upper end cover 13. The material sprayed from the cyclone guide channel 22 can have sufficient space to float with the wind between the discharge pipe 12 and the upper end cover 13, so that the material is impacted by the rotating airflow in this space, separating particles, dust and plastic film. In addition, a sufficiently large gap between the discharge pipe 12 and the upper end cover 13 can also ensure that there is a small negative pressure at the upper end of the discharge pipe 12, so that the floating material has enough time to float and is not sucked into the discharge pipe 12 as soon as it is sprayed out of the cyclone guide channel 22. Of course, the specific dimensions of the feed pipe 11, the discharge pipe 12, and the distance between the discharge pipe 12 and the upper end cover 13 can be obtained through experiments and calculations, and will not be described in detail here.

[0041] When centrifugal disc 4 and the cyclone circulation device are working, particulate impurities and dust will settle to the bottom of the selection chamber 1 under the combined action of centrifugal force and gravity. To clean these settled impurities, they can be removed as follows: Figure 1 As shown, an inspection hole 19 is provided at the bottom of the fine selection chamber 1, and an openable inspection door is provided on the inspection hole 19. When the cyclone circulation device is working, the inspection door is closed; the inspection door is opened periodically to clean the settled impurities through the inspection hole 19.

[0042] In order to facilitate the timely removal of settled impurities, as a further improvement to this utility model, such as Figure 2 As shown, a slag discharge pipe 7 is inserted through the outer wall of the selection chamber 1 below the centrifuge disc 4; an arc-shaped ramp 71 connecting the slag discharge pipe 7 is provided at the lower end of the interlayer between the screen 5 and the selection chamber 1. The arc-shaped ramp 71 is spirally arranged around the centrifuge disc 4. The outer ring surface of the arc-shaped ramp 71 is attached to the inner wall of the selection chamber 1, and the inner ring surface is attached to the outer wall of the screen 5 or the outer wall of a closed cylinder extending downward from the lower end of the screen 5; the upper end of the arc-shaped ramp 71 extends to the edge of the centrifuge disc 4; if the edge of the centrifuge disc 4 is provided with an inclined screen 42, then the upper end of the arc-shaped ramp 71 extends to the edge of the upper end face of the inclined screen 42; this allows the arc-shaped ramp 71 to connect with the interlayer between the screen 5 and the selection chamber 1, thereby catching the particulate impurities that settle in the interlayer; the lower end of the arc-shaped ramp 71 is connected to the inner cavity of the slag discharge pipe 7 through an opening opened on the side wall of the slag discharge pipe 7. When the cyclone circulation device is working, the impurities that settle in the interlayer between the screen 5 and the fine selection chamber 1 will flow along the arc-shaped ramp 71 into the slag discharge pipe 7 and be discharged through the slag discharge pipe 7.

[0043] In addition, for the embodiment where the centrifugal disc 4 has an inclined screen 42 on its edge, an auxiliary slag discharge ramp can be set inside the arc-shaped ramp 71 and below the inclined screen 42. The auxiliary slag discharge ramp is used to receive particulate impurities that fall through the inclined screen 42. The upper end of the auxiliary slag discharge ramp is connected to the edge of the centrifugal disc 4, and the lower end is connected to the slag discharge pipe 7.

[0044] like Figure 1 , Figure 6 As shown, the primary selection device includes a cylindrical primary selection chamber 9, a primary feed pipe 91 and a primary discharge pipe 92 disposed on the side wall of the primary selection chamber 9. Material entering the primary selection chamber 9 through the primary feed pipe 91 is discharged through the primary discharge pipe 92, completing one cycle. The primary selection chamber 9 has a primary selection chamber cover 93 at its upper end and a slag discharge auger 94 at its lower end. The primary selection chamber cover 93 is used to seal the upper end of the primary selection chamber 9, and the feed inlet of the slag discharge auger 94 is connected to the inner cavity of the primary selection chamber 9 for discharging impurities. A secondary feed pipe 95 and a discharge pipe 96 are inserted through the side wall of the primary selection chamber 9. Material entering the primary selection chamber 9 through the secondary feed pipe 95 is discharged through the discharge pipe 96, completing a secondary cycle. The discharge pipe 96 is located at the top of the primary selection chamber 9, with its inner end connected to the inner cavity of the primary selection chamber 9 and located at the highest point of the inner cavity. The outer end of the discharge pipe 96 is connected to the feed pipe 11 of the fine selection chamber 1. Figure 1 As shown, a U-shaped bend section 97 is provided between the outer end of the discharge pipe 96 and the feed pipe 11 of the refining bin 1. An induced draft fan 99 is provided at the upper end of the refining bin 1. The air inlet of the induced draft fan 99 is connected to the U-shaped bend section, and the air outlet is connected to the feed pipe 11. When the induced draft fan at the upper end of the refining bin 1 is working, a negative pressure is generated in the U-shaped bend section 97 and the discharge pipe 96, which draws the material that has completed the secondary circulation at the upper end of the primary refining bin 9 into the refining bin 1 through the discharge pipe 96.

[0045] The secondary feed pipe 95 is located between the primary discharge pipe 92 and the unloading pipe 96, and its position is higher than the primary discharge pipe 92 but lower than the unloading pipe 96. The inner ends of the primary feed pipe 91 and the secondary feed pipe 95 extend into the inner cavity of the primary selection chamber 9 and are respectively connected to the inclined upward extending primary arc guide plate 971 and secondary arc guide plate 972. The primary arc guide plate 971 and the secondary arc guide plate 972 can guide the airflow entering the primary selection chamber 9 through the primary feed pipe 91 and the secondary feed pipe 95 obliquely upward, and form an inclined upward cyclone in conjunction with the action of the inner wall of the primary selection chamber 9.

[0046] like Figure 2 As shown, the outer end of the primary feed pipe 91 is connected to the outlet of the primary feed fan 81, the outer end of the secondary feed pipe 95 is connected to the outlet of the circulating fan 82, the inlet of the circulating fan 82 is connected to the outer end of the primary discharge pipe 92, and the inner end of the primary discharge pipe 92 extends into the inner cavity of the primary selection chamber 9 and connects to the central pipe 83 longitudinally positioned at the center of the primary selection chamber 9. Both the feed fan 81 and the circulating fan 82 are centrifugal fans. Figure 2 As shown by the middle arrow, when the feed fan 81 is working, it draws material from the hopper 98 and blows it out from the outlet. The material blown out by the feed fan 81 enters the middle section of the primary selection chamber 9 through the primary feed pipe 91, and floats under the guidance of the primary arc guide plate 971 and the cyclone airflow. At this time, the plastic film with a smaller specific gravity descends very slowly, but the particulate impurities with a larger specific gravity quickly settle to the bottom of the primary selection chamber 9. When the circulating fan 82 is working, it draws air out through the primary discharge pipe 92 and the central pipe 83, creating a local negative pressure at the lower end of the central pipe 83. When the plastic film descends to the lower end of the central pipe 83, it is drawn into the central pipe 83 and enters the circulating fan 82 through the central pipe 83 and the primary discharge pipe 92, completing one cycle. Figure 2 As shown by the middle arrow, the material blown out by the circulating fan 82 enters the higher position of the primary selection chamber 9 through the secondary feed pipe 95, and floats under the guidance of the secondary arc guide plate 972 and the cyclone airflow. At this time, the heavier particulate impurities quickly sink to the bottom of the primary selection chamber 9, while the lighter plastic film is sucked into the discharge pipe 96 by the negative pressure generated by the discharge pipe 96, and is transported to the fine selection chamber 1 through the discharge pipe 96 to complete the secondary circulation.

[0047] In addition, the material processed by the primary screening unit contains a large number of larger particulate impurities, resulting in a significant amount of impurities settling out during equipment operation. To facilitate the timely collection and removal of impurities settling at the bottom of the primary screening chamber 9, a screening hopper 84 is installed at the bottom of the primary screening chamber 9. For example... Figure 7As shown, the upper end of the central tube 83 is connected to the primary discharge pipe 92, and the lower end is connected to the screening hopper 84 with a clearance fit. The screening hopper 84 has an inner cavity with a cone-shaped structure that is larger at the top and smaller at the bottom. The lower end of the primary selection chamber 9 is connected to the upper port of the screening hopper 84. The particulate impurities and plastic film that settle in the primary selection chamber 9 will fall into the screening hopper 84. The lower end of the screening hopper 84 is connected to the inlet of the slag discharge auger 94 so that the particulate impurities that fall into the screening hopper 84 can enter the slag discharge auger 94 under the influence of gravity and be discharged as the slag discharge auger 94 operates. The lower end of the central tube 83 extends into the inner cavity of the screening hopper 84 and is coaxially arranged with the lower port of the screening hopper 84. There is a certain gap between the lower end face of the central tube 83 and the lower port of the screening hopper 84. Due to the existence of this gap, the central tube 83 will not prevent the heavier particulate impurities from falling into the slag discharge auger 94 through the lower port of the screening hopper 84. At the same time, the negative pressure of the central tube 83 can draw smaller plastic films into the central tube 83.

[0048] As a further improvement of this utility model, the inner ends of the primary feed pipe 91 and the secondary feed pipe 95 are arranged along the tangential direction of the inner wall of the primary selection chamber 9, so that the inner ports of the primary feed pipe 91 and the secondary feed pipe 95 eject airflow in the tangential direction; the width direction of the primary arc-shaped guide plate 971 and the secondary arc-shaped guide plate 972 extends from the inner wall of the primary selection chamber 9 towards the center and covers the diameter of the primary feed pipe 91 or the secondary feed pipe 95, but is less than one-quarter of the inner diameter of the primary selection chamber 9, and the width of the arc-shaped guide plate 97 is sufficient to guide the primary feed. The airflow ejected from pipe 91 or secondary feed pipe 95 leaves sufficient space for the material to move downwards. The length direction of the primary arc guide plate 971 and secondary arc guide plate 972 extends 30-120 degrees from the inner end of the primary feed pipe 91 or secondary feed pipe 95 along a spiral upward trajectory. In this embodiment, 60 degrees is used, meaning that the length of a single arc guide plate occupies one-quarter of a circumference. This fully utilizes the impact force of the airflow ejected from the primary feed pipe 91 and secondary feed pipe 95 to push the material to a higher position. The highest point of the primary arc guide plate 971 is lower than the inner end of the secondary feed pipe 95, thus avoiding interference between the airflows guided by the primary arc guide plate 971 and secondary arc guide plate 972. The outer sides of the primary arc-shaped guide plate 971 and the secondary arc-shaped guide plate 972 are fixedly connected to the inner wall of the primary selection chamber 9. The surface of the arc-shaped guide plate is perpendicular to the inner wall of the primary selection chamber 9, forming a ramp that slopes upward along the inner wall of the primary selection chamber 9. The airflow ejected from the primary feed pipe 91 and the secondary feed pipe 95 blows the material to the top of the arc-shaped guide plate along their respective ramps, while generating an upward spiral airflow in the inner cavity of the primary selection chamber 9.

[0049] like Figure 1As shown, when the separation device of this utility model is used, the recycled plastic film material is first shredded into sufficiently small pieces so that it can be sucked into the primary selection chamber 9 by the primary selection feed fan 81. At the same time, sufficiently small pieces can avoid entanglement and affect the impurity removal effect. The shredded material is placed into the hopper 98. The feeding fan 81, the circulating fan 82, and the induced draft fan 99 are turned on. The feeding fan 81 draws the material from the hopper 98 and blows it into the primary feeding pipe 91, which then sends it into the primary selection chamber 9. At the same time, the circulating fan 82 generates negative pressure at the lower end of the central pipe 83, and the induced draft fan 99 generates negative pressure near the upper discharge pipe 96 of the primary selection chamber 9. The material blown in by the primary feeding pipe 91 is far from the negative pressure area at the upper end of the primary selection chamber 9 and is not attracted by the discharge pipe 96. At this time, the material is impacted by the cyclone, and the particulate impurities carried in the plastic film fragments are separated from the film body. The particulate impurities fall rapidly, while the plastic film falls slowly. The falling particulate impurities enter the auger 94 through the screening hopper 84 and are discharged as the auger 94 operates. The falling plastic film descends to the discharge port of the screening hopper 84 and is sucked into the central pipe 83 by the negative pressure. Then, it is blown back into the primary selection chamber 9 through the primary discharge pipe 92, the circulating fan 82, and the secondary feed pipe 95. At this time, because the secondary feed pipe 95 and the secondary arc guide plate 972 are at a higher position, the material entering the secondary chamber is closer to the negative pressure zone at the top of the primary selection chamber 9. The falling particulate impurities still fall into the screening hopper 84 and are discharged by the auger 94, but the plastic film is attracted by the negative pressure of the discharge pipe 96 and is sucked into the discharge pipe 96 and then enters the fine selection chamber 1 through the U-shaped bend section 97 and the induced draft fan 99. When the material passes through the U-shaped bend section 97, a small amount of particulate impurities will fall off the plastic film. These impurities will remain at the bend or lower part of the U-shaped bend section 97. An inspection hole can be opened in the U-shaped bend section 97, and a sealing door can be installed on the inspection hole. The impurities can be cleaned by opening the sealing door through the inspection hole periodically.

[0050] After the material enters the selection chamber 1, it falls onto the centrifugal disc 4 through the feed pipe 11 and the discharge pipe 12. At this time, the induced draft fan 99 is turned off, the drive motor 3 is turned on, and multiple cyclone circulation devices work simultaneously. The centrifugal disc 4 drives the material to rotate at high speed, pushing the material to the edge of the centrifugal disc 4. At the same time, a negative pressure is generated below the discharge pipe 12. Particles and impurities that fall off the plastic film will pass through the inclined screen 42 at the edge of the centrifugal disc 4, but the plastic film itself is blocked by the inclined screen 42. The material and air that have moved to the edge of the centrifugal disc 4 are sucked out of the selection chamber 1 by the cyclone blower 2 under the adsorption of the cyclone circulation device, and then return to a higher position in the selection chamber 1 through the cyclone pipe 21 and the cyclone guide air channel 22. Under the entrainment of the cyclone, they float and rotate with the wind, separating impurities again. The particles with a larger specific gravity are separated from the plastic film body under the dual action of gravity and centrifugal force, falling along the inner wall of the selection chamber 1, or passing through the screen 5 and entering the interlayer. At this time, a relatively high-pressure area is formed at the upper end of the inner cavity of the selection chamber 1. The plastic film floating with the wind moves downward under the negative pressure at the lower end of the selection chamber 1. Most of the plastic film enters the inside of the discharge pipe 12, and a small amount falls down along the outer wall of the discharge pipe 12. When the plastic film falling down along the outer wall of the discharge pipe 12 reaches the vicinity of the material return pipe 23, it is directly sucked away by the material return pipe 23 and enters the recirculation. When the plastic film that has entered the inside of the discharge pipe 12 falls onto the centrifugal disc 4, it is pushed by the rotating centrifugal disc 4 to the material return pipe 23, and then sucked away by the material return pipe 23 and enters the recirculation. As described above, as long as the upper cover 13 of the selection chamber 1 remains closed, the centrifugal disc 4 and the cyclone circulation device can drive the plastic film to continuously circulate between the selection chamber 1 and the cyclone blower 2, removing particles and dust, until the cleanliness of the material meets the requirements for recycling or the processing time of the material in the selection chamber 1 reaches the set value. Once the cleanliness of the material meets the requirements or the processing time reaches the required level, the material can be discharged through the discharge pipe 991 located at the upper end of the refining chamber 1 and the discharge fan connected to the discharge pipe 991. Although specific embodiments of this utility model have been described in detail above, those skilled in the art should understand that the above examples are for illustrative purposes only and not intended to limit the scope of protection of this utility model. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this utility model. The scope of protection of this utility model is defined by the appended claims.

Claims

1. A multi-stage dust removal and separation device, comprising a primary selection device for separating large particulate impurities and a secondary selection device for separating fine particles and dust, characterized in that, The selected device includes The cylindrical selection chamber (1) has a cylindrical internal cavity. A cyclone pipe (21) and a material return pipe (23) are inserted through the outer wall of the selection chamber (1). The cyclone pipe (21) is used to introduce external airflow into the internal cavity of the selection chamber (1), and the material return pipe (23) is used to output the airflow in the internal cavity of the selection chamber (1). Multiple cyclone blowers (2) are evenly distributed around the axis of the selection chamber (1) and fixedly installed at the lower end of the selection chamber (1). The cyclone blowers (2) provide power for the circulation of airflow. The air outlet of the cyclone blower (2) is connected to the outer end of the cyclone pipe (21), and the air inlet is connected to the outer end of the material return pipe (23). When the cyclone blower (2) is working, it draws air from the inner cavity of the selection chamber (1) through the material return pipe (23) and blows it into the inner cavity of the selection chamber (1) through the cyclone pipe (21). Centrifugal disc (4) is installed at the lower end of the inner cavity of the selection chamber (1). The centrifugal disc (4) is rotatably installed on the lower end cover of the selection chamber (1) via a rotating shaft. The centrifugal disc (4) is used to drive the air at the lower end of the inner cavity of the selection chamber (1) to rotate and generate centrifugal force. The inner end of the material return pipe (23) is connected to the upper edge of the centrifugal disc (4) to facilitate the suction of air at the edge of the centrifugal disc (4). A drive motor (3) is installed outside the selection chamber (1) and is used to drive the centrifugal disc (4). The feed pipe (11) is installed in the center of the fine selection chamber (1), and its upper end is inserted through the upper cover (13) of the fine selection chamber (1) to feed raw materials into the fine selection chamber (1). The discharge pipe (12) is coaxially arranged with the feed pipe (11) and located below the feed pipe (11). The inner diameter of the discharge pipe (12) is larger than the outer diameter of the feed pipe (11), and it is used to receive the raw material input by the feed pipe (11). The lower end of the discharge pipe (12) is located above the centrifugal disc (4), and it is used to transport the raw material fed into the discharge pipe (12) to the center of the centrifugal disc (4). Cyclone guide air duct (22) is set on the inner wall of the fine selection bin (1), and connects to the inner end of the cyclone pipe (21). It extends upward in an arc from the end connected to the cyclone pipe (21) so that the airflow ejected from the upper end of the cyclone guide air duct (22) can connect with the upper end of the drop pipe (12).

2. The multi-stage dust removal and separation device according to claim 1, characterized in that, The centrifugal disc (4) is a horizontally arranged disc-shaped structure. A baffle plate (41) is connected and installed on the upper surface of the centrifugal disc (4). Multiple triangular baffle plates (41) are evenly distributed around the center of the centrifugal disc (4). A rotating shaft (43) is fixedly connected to the center of the lower surface of the centrifugal disc (4). The rotating shaft (43) is connected to the drive motor (3) for transmission.

3. The multi-stage dust removal and separation device according to claim 1 or 2, characterized in that, The inner diameter of the discharge pipe (12) is larger than the outer diameter of the feed pipe (11). There is a gap between the upper end of the discharge pipe (12) and the upper end cover (13) of the selection bin (1). The upper opening of the cyclone guide channel (22) is lower than the upper end face of the discharge pipe (12).

4. A multi-stage dust removal and separation device according to claim 1 or 2, characterized in that, A screen (5) is fixedly installed in the inner cavity of the selection chamber (1) by a support ring (6). There is an interlayer between the screen (5) and the inner wall of the selection chamber (1). The lower end of the screen (5) is fitted with the edge of the centrifugal disc (4) with a gap. The inner ends of the cyclone pipe (21) and the material return pipe (23) pass through the interlayer between the screen (5) and the selection chamber (1) and are located inside the screen (5).

5. The multi-stage dust removal and separation device according to claim 4, characterized in that, A slag discharge pipe (7) is inserted through the outer wall of the selection chamber (1) below the centrifugal disc (4); an arc-shaped ramp (71) connecting the slag discharge pipe (7) is provided at the lower end of the interlayer between the screen (5) and the selection chamber (1).

6. A multi-stage dust removal and separation device according to claim 1 or 2, characterized in that, The primary selection device includes a cylindrical primary selection chamber (9), a primary feed pipe (91) and a primary discharge pipe (92) installed on the side wall of the primary selection chamber (9). The upper end of the primary selection chamber (9) is equipped with a primary selection chamber cover (93), and the lower end is equipped with a slag discharge auger (94). A secondary feed pipe (95) and a discharge pipe (96) are inserted through the side wall of the primary selection chamber (9). The discharge pipe (96) is located at the top of the primary selection chamber (9), and the inner end of the discharge pipe (96) is connected to... The primary selection chamber (9) is located at the highest point of its inner cavity, and the outer end of the discharge pipe (96) is connected to the feed pipe (11) of the secondary selection chamber (1). The secondary feed pipe (95) is located between the primary discharge pipe (92) and the discharge pipe (96). The inner ends of the primary feed pipe (91) and the secondary feed pipe (95) extend into the inner cavity of the primary selection chamber (9) and are respectively connected to the inclined upward-extending primary arc-shaped guide plate (971) and the secondary arc-shaped guide plate. (972); the outer end of the primary feed pipe (91) is connected to the outlet of the primary feed fan (81), the outer end of the secondary feed pipe (95) is connected to the outlet of the circulating fan (82), the inlet of the circulating fan (82) is connected to the outer end of the primary discharge pipe (92), the inner end of the primary discharge pipe (92) extends into the inner cavity of the primary selection chamber (9) and is connected to the central pipe (83) longitudinally arranged in the center of the primary selection chamber (9), the central pipe (872) 3) The upper end is connected to the primary discharge pipe (92), and the lower end is connected to the screening hopper (84) with a clearance fit. The screening hopper (84) has an inner cavity with a cone-shaped structure that is larger at the top and smaller at the bottom. The lower end of the primary selection chamber (9) is connected to the upper port of the screening hopper (84), and the lower end of the screening hopper (84) is connected to the feed inlet of the slag discharge auger (94). The lower end of the central tube (83) extends into the inner cavity of the screening hopper (84) and is coaxially set with the lower port of the screening hopper (84).

7. The multi-stage dust removal and separation device according to claim 6, characterized in that, A U-shaped bend section (97) is provided between the outer end of the unloading pipe (96) and the feed pipe (11) of the fine selection bin (1). An induced draft fan is provided at the upper end of the fine selection bin (1). The air inlet of the induced draft fan is connected to the U-shaped bend section, and the air outlet is connected to the feed pipe (11).

8. A multi-stage dust removal and separation device according to claim 6 or 7, characterized in that, The inner ends of the primary feed pipe (91) and the secondary feed pipe (95) are arranged along the tangential direction of the inner wall of the primary selection chamber (9). The width direction of the primary arc guide plate (971) and the secondary arc guide plate (972) extends from the center of the primary selection chamber (9) and covers the diameter of the primary feed pipe (91) or the secondary feed pipe (95), but is less than one-quarter of the inner diameter of the primary selection chamber (9). The length direction of the primary arc guide plate (971) and the secondary arc guide plate (972) extends from the inner end of the primary feed pipe (91) or the secondary feed pipe (95) along a spiral upward trajectory for 30 degrees to 120 degrees. The highest point of the primary arc guide plate (971) is lower than the inner end of the secondary feed pipe (95). The outer sides of the primary arc guide plate (971) and the secondary arc guide plate (972) are fixedly connected to the inner wall of the primary selection chamber (9).

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