Circulating airflow screening equipment

Abstract

The invention discloses circulating airflow screening equipment, which relates to the technical field of material screening and comprises a feeding device, a screening device, an airflow circulating device, a discharging device and a control system. The screening device adopts a multi-layer nested aperture-adjustable screen structure, the aperture can be continuously adjusted by adjusting the alignment degree of the hole sites of the inner and outer layers of screens, and an elastic expansion positioning mechanism ensures that the tension of the screens is uniform; the anti-blocking net cleaning assembly integrates an airflow pulse and flexible knocking composite structure and is matched with a heating heat preservation interlayer, and the problem of screen hole blocking is efficiently solved. And the airflow circulating device adopts a partitioned flow guide type airflow injection and Venturi tube cyclone separation backflow structure, so that the airflow utilization rate is increased, and the energy consumption is reduced. The defects that an existing equipment screen is poor in adaptability and prone to deformation, screen holes are prone to being blocked, airflow distribution is uneven, and energy consumption is high are overcome, efficient, stable and energy-saving screening of multi-granularity materials is achieved, and the multi-granularity material screening device is suitable for various material screening scenes in the chemical industry, the medicine industry, the food industry and the like.

Description

Technical Field

[0001] This invention relates to the field of material screening technology, and specifically to a circulating airflow screening device. Background Technology

[0002] Airflow screening equipment is widely used in material classification due to its advantages such as high screening efficiency and low pollution. Among them, horizontal airflow screens have become one of the mainstream equipment due to their compact structure and convenient operation. However, existing horizontal airflow screens still have many technical defects in practical applications, which seriously affect the screening effect and user experience: Regarding screen components, traditional screens have fixed apertures, only suitable for screening materials of a single particle size. When faced with screening tasks involving multiple particle sizes, frequent screen replacements are necessary. Furthermore, existing screens often use clamps for fixing, making installation and disassembly complex, time-consuming, and labor-intensive, significantly reducing production efficiency. Simultaneously, during long-term operation, the screen is subjected to the combined effects of airflow impact and material friction, easily leading to uneven tension and deformation, resulting in decreased screening accuracy and affecting product quality. Although some patents attempt to adjust screen tension using expansion rollers, this only achieves single-dimensional adjustment, limiting its adaptability.

[0003] Regarding screen clogging prevention, fine powders and sticky materials tend to adhere to the inner wall of the screen holes during the screening process, causing clogging. Existing screen cleaning structures mostly adopt a ball-tapping design, which not only has blind spots in the cleaning process and cannot completely remove residual materials inside the screen holes, but also the rigid balls can easily cause impact damage to the screen, shortening the screen's service life. In addition, the screen clogging problem is more prominent for high-temperature or humid materials. Humid materials tend to clump and adhere, and changes in material properties under high-temperature environments further aggravate clogging. Existing equipment lacks a targeted anti-clogging solution.

[0004] Regarding the airflow circulation system, existing equipment often uses a single-point or uniform distribution mode for airflow injection, which can easily cause airflow turbulence, resulting in uneven material dispersion, concentrated airflow in some areas and insufficient airflow in others, thus reducing the material's screening rate. At the same time, the design of the circulating return channel is simple and does not fully utilize the kinetic energy of the airflow. Coarse material return requires additional power, resulting in high energy consumption. Furthermore, the dust carried in the return airflow can easily cause secondary pollution, affecting the screening environment and product purity.

[0005] The aforementioned defects mean that the applicability, screening efficiency, stability, and energy efficiency of existing circulating airflow screening equipment cannot meet actual production needs. Therefore, there is an urgent need for a new type of circulating airflow screening equipment that can solve these problems. Summary of the Invention

[0006] This invention aims to overcome the shortcomings of existing circulating airflow screening equipment and provide a circulating airflow screening device that solves the technical problems of existing equipment, such as non-adjustable screen aperture, complicated replacement, easy deformation, easy clogging of screen holes, incomplete screen cleaning and easy damage to screen, uneven airflow distribution, high circulating energy consumption, and easy generation of secondary pollution. It achieves the goals of adapting to multi-particle-size materials, efficient anti-clogging screen cleaning, and energy-saving circulating screening.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A circulating airflow screening device includes a feeding device, a screening device, an airflow circulation device, a discharging device, and a control system. The devices work together to complete the continuous screening of materials.

[0008] Furthermore, the screening device includes a screen assembly and an anti-clogging and cleaning assembly. The screen assembly adopts a multi-layer nested adjustable aperture structure. The screen body is a double-layer cylindrical structure with an inner layer being a rotatable multi-hole adjusting cylinder and an outer layer being a fixed screen cylinder. The screening aperture is continuously adjustable by adjusting the alignment of the apertures of the inner multi-hole adjusting cylinder and the outer fixed screen cylinder. Elastic expansion positioning mechanisms are set at both ends of the screen, which automatically press against both ends of the screen through built-in expansion rollers and spring assemblies to ensure uniform tension of the screen during operation. The screen material and aperture gradient are optimized. The inner multi-hole adjusting cylinder is made of wear-resistant ceramic coating material, and the outer fixed screen cylinder is adapted to stainless steel or fiber screens according to the material characteristics, forming an integrated coarse and fine screening structure.

[0009] Furthermore, the anti-clogging screen cleaning component is a composite structure of airflow pulse and flexible tapping. Pulse jet nozzles are evenly arranged axially on the inner side of the screen. These nozzles are linked to the equipment's airflow system, periodically spraying high-pressure airflow in the opposite direction to the material passing through the screen. Traditional rigid balls are replaced with flexible balls encased in silicone. These flexible balls are connected to the impeller support via adjustable telescopic springs, allowing the spring force to be adjusted according to the screen aperture and material characteristics. A heating and insulation layer is added to the outer side of the screen. Spiral heating wires and temperature sensors are laid within this layer. Low-temperature heating prevents damp materials from adhering to the screen, and an insulation layer is installed on the outside of the heating and insulation layer to reduce heat loss.

[0010] Furthermore, the airflow circulation device adopts a zoned flow-guided airflow injection and recirculation structure. A conical diffusion-type airflow mixing chamber is installed at the feed end, with spiral guide vanes on the inner wall of the chamber for thorough atomization and mixing of the material and airflow, guiding the mixture spirally forward along the screen axis. The screening zone is divided into multiple slit-shaped nozzles along the screen length, each independently controllable, with a combination of vertical and 30° oblique injection angles. The recirculation channel adopts an integrated Venturi tube and cyclone separator structure, with a Venturi tube acceleration section between the coarse material outlet and the feed inlet of the feeding device, and a built-in cyclone separator within the Venturi tube acceleration section.

[0011] Furthermore, the control system is electrically connected to the feeding device, screening device, airflow circulation device, and discharge device respectively, and is used to control the operating parameters of each device, including screen aperture adjustment, pulse jet frequency, soft tapping force, heating temperature, airflow pressure and flow rate, etc.

[0012] The circulating airflow screening equipment of the present invention achieves efficient and stable screening of materials through the coordinated operation of various devices. Feeding stage: The material enters the conical diffuser airflow mixing chamber through the feeding device. At the same time, the airflow system introduces airflow into the conical diffuser airflow mixing chamber. Under the action of the spiral guide vanes, the material and airflow are fully atomized and mixed to form a uniform material-airflow mixture. The mixture is spirally propelled along the screen axis to avoid uneven material distribution caused by local airflow concentration.

[0013] Screening stage: The control system adjusts the rotation angle of the inner porous regulating cylinder according to the particle size requirements of the material to be screened, so that the holes of the inner porous regulating cylinder and the outer fixed screen cylinder are aligned at a specific degree, thereby obtaining the required screening aperture. After the material-airflow mixture enters the screening section, multiple independently controllable slit-shaped nozzles spray airflow. The combination of vertical incident and 30° oblique airflow evenly covers the screen surface. Under the action of airflow pressure, fine materials that meet the aperture requirements pass through the screen and enter the discharge device for discharge; coarse materials that do not meet the aperture requirements are conveyed forward along the inner wall of the screen cylinder to the coarse material outlet.

[0014] Anti-clogging and screen cleaning stage: During the screening process, the control system activates the anti-clogging and screen cleaning components based on the material characteristics. Pulse jet nozzles periodically spray high-pressure reverse airflow, precisely impacting the inner side of the screen to blow out residual material embedded in the screen holes. Simultaneously, flexible balls, driven by a fan, tap the outer side of the screen. Adjustable telescopic springs adapt to different screens and materials, preventing screen damage and thoroughly removing material adhering to the screen surface. For damp, easily agglomerated materials, the control system monitors the temperature inside the heating and insulation jacket in real time using a temperature sensor, controlling the spiral heating wires to provide low-temperature heating of 50-120℃ to prevent material agglomeration and adhesion to the screen. The insulation layer effectively reduces heat loss, ensuring stable heating performance.

[0015] Airflow circulation stage: Under the negative pressure generated by the venturi tube acceleration section, the coarse material at the coarse material outlet is automatically drawn to the return channel. During the return process, the built-in cyclone separator separates the coarse material from the dust in the return airflow. The dust is collected and treated to avoid secondary pollution. The separated coarse material re-enters the feeding device, mixes with the new feed, and is screened again. After the airflow is purified by the cyclone separator, part of it is returned to the airflow system for reuse, realizing efficient recovery of airflow kinetic energy and reducing additional power consumption.

[0016] Beneficial effects Continuously adjustable and highly adaptable screen aperture: Through the inner and outer double-layer cylindrical screen structure and aperture alignment adjustment, the screening aperture can be continuously adjusted from 80 to 530 mesh, meeting the screening needs of multi-particle-size materials without screen replacement, and greatly improving production efficiency; The elastic expansion positioning mechanism automatically maintains uniform screen tension, effectively avoiding screen deformation caused by airflow impact and material friction. Combined with the wear-resistant ceramic coating inner layer and the adaptable outer screen layer, the service life of the screen is extended and the screening accuracy is guaranteed to be stable.

[0017] The anti-clogging and screen cleaning effect is remarkable and there is no screen damage: The airflow pulse and flexible knocking composite screen cleaning structure uses reverse high-pressure airflow to accurately remove residual materials in the screen holes, and the flexible ball knocking has no dead angles and avoids screen damage, solving the problems of dead angles and screen damage in traditional screen cleaning methods; the heating and insulation jacket prevents the adhesion of damp and easily clumped materials, adapting to special working conditions such as high temperature and humidity, and broadening the scope of application of the equipment.

[0018] Highly efficient, energy-saving, and environmentally friendly airflow circulation: The zoned flow guidance design of the conical diffusion airflow mixing chamber and the multi-slit nozzle avoids airflow turbulence, ensuring uniform material dispersion and full airflow coverage, thereby improving the material screening rate; The integrated reflux structure of the Venturi tube and cyclone separator uses negative pressure to automatically pull coarse material back, recovering airflow energy, reducing energy consumption, and separating dust to avoid secondary pollution, thus achieving both energy saving and environmental protection.

[0019] Easy to operate and highly automated: The control system centrally controls various operating parameters, enabling precise regulation of screen aperture, cleaning intensity and frequency, heating temperature, airflow parameters, etc., making operation convenient, reducing labor costs, and ensuring stable equipment operation. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the left-side structure of the present invention; Figure 3 This is a schematic diagram of the transmission mechanism structure of the present invention; Figure 4 for Figure 3 Enlarged structural diagram at point A in the middle; Figure 5 This is a cross-sectional structural diagram of the present invention; Figure 6 for Figure 5 A front view structural diagram; Figure 7 This is a schematic diagram of the main structure of the screen of the present invention; Figure 8 This is a schematic diagram of the structure of the inner porous adjusting cylinder and the outer fixed screen cylinder of the present invention, showing the maximum mesh size of the screen holes. Figure 9 This is a schematic diagram of the inner porous adjusting cylinder and the outer fixed screen cylinder of the present invention, showing the alignment and adjustment state of the screen holes. Figure 10 This is a schematic diagram of the inner porous adjusting cylinder and the outer fixed screen cylinder of the present invention, showing the second state of aligning the screen holes. Figure 11 This is a schematic cross-sectional view of the screen body of the present invention; Figure 12 This is a schematic diagram of the internal structure of the inner porous regulating cylinder of the present invention; In the picture: 1 Feeding device, 2 Conical diffusion airflow mixing chamber, 3 Spiral guide vanes, 4 Screening device, 5 Screen body, 6 Inner porous regulating cylinder, 7 Outer fixed screen cylinder, 8 Elastic expansion positioning mechanism, 9 Expansion roller, 10 Spring assembly, 11 Anti-clogging screen cleaning assembly, 12 Pulse jet nozzle, 13 Flexible ball, 14 Adjustable telescopic spring, 15 Wind turbine support, 16 Heating and insulation jacket, 17 Spiral heating wire, 18 Temperature sensor, 19 Insulation layer, 20 Slit nozzle, 21 Airflow circulation device, 22 Venturi tube acceleration section, 23 Cyclone separator, 24 Coarse material outlet. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: like Figure 1-12 As shown: The circulating airflow screening equipment of this embodiment includes a feeding device 1, a screening device 4, an airflow circulation device 21, a discharge device, and a control system.

[0022] The feeding device 1 uses a screw conveyor to stably transport the material to be screened to the conical diffusion airflow mixing chamber 2. The inner wall of the conical diffusion airflow mixing chamber 2 is welded with spiral guide vanes 3. The pitch of the spiral guide vanes 3 is 150mm to ensure that the material and airflow are fully mixed and spirally propelled. The screen body 5 of the screening device 4 is a double-layer cylindrical structure. The outer diameter of the inner porous regulating cylinder 6 is 500mm and the length is 1800mm. It is made of wear-resistant ceramic coating material with a surface aperture of 80-530 mesh. The outer fixed screen cylinder 7 is made of 304 stainless steel screen according to the material characteristics. The aperture is matched with the inner porous regulating cylinder 6 to form an integrated coarse and fine screening structure. The elastic expansion positioning mechanism 8 at both ends of the screen includes an expansion roller 9 and a spring assembly 10. The expansion roller 9 is made of stainless steel with a diameter of 50mm. The elastic coefficient of the spring assembly 10 can be adjusted according to the screen tension requirements to ensure automatic clamping of both ends of the screen.

[0023] In the anti-clogging and screen cleaning assembly 11, pulse jet nozzles 12 are evenly arranged along the inner side of the screen axially with a spacing of 200mm. The jet pressure of the pulse jet nozzles 12 is 0.3-0.6MPa, and the jet frequency is 5-15 times / minute. They are connected to the airflow system through a pipe. The flexible ball 13 has a diameter of 30mm and is wrapped with a silicone layer with a thickness of 5mm. It is connected to the impeller bracket 15 through an adjustable telescopic spring 14. The telescopic range of the adjustable telescopic spring 14 is 50-100mm, and the elastic force adjustment range is 5-20N. The heating and insulation jacket 16 has a thickness of 80mm and is internally laid with a spiral heating wire 17 with a diameter of 3mm. The temperature sensor 18 adopts a PT100 type temperature sensor. The insulation layer 19 is made of rock wool with a thickness of 40mm. The heating temperature is controlled at 50-120℃.

[0024] In the airflow circulation device 21, the screening area is divided into 4 slit-shaped nozzles 20 along the length of the screen. Each slit-shaped nozzle 20 is 450mm long and 5mm wide. The nozzle angles are arranged with vertical incidence and 30° oblique incidence alternately. Each slit-shaped nozzle 20 is equipped with an independent flow regulating valve. The Venturi tube acceleration section 22 of the circulation return channel has an inlet diameter of 200mm, a throat diameter of 100mm, and an outlet diameter of 150mm. The built-in cyclone separator 23 has a separation efficiency of ≥95%. The dust discharge port of the cyclone separator 23 is connected to a dust collection device. The outlet of the Venturi tube acceleration section 22 is connected to the inlet of the feeding device 1 through a pipe.

[0025] The control system uses a PLC controller, which is electrically connected to the screw conveyor of the feeding device 1, the solenoid valve of the pulse jet nozzle 12, the adjustment mechanism of the adjustable telescopic spring 14, the temperature controller of the spiral heating wire 17, the temperature sensor 18, the flow regulating valve of the slit nozzle 20, and the pressure sensor of the venturi acceleration section 22, respectively, to realize the automatic control and adjustment of various operating parameters.

[0026] The working process of the circulating airflow screening equipment in this embodiment is as follows: After the equipment is started, the control system controls the inner porous adjusting cylinder 6 to rotate to a set angle according to the particle size requirements of the material to be screened, so that the alignment of the inner porous adjusting cylinder 6 with the outer fixed screen cylinder 7 reaches the target aperture (such as 200 mesh); at the same time, the pulse jet frequency is set to 10 times / minute and the striking force of the flexible ball 13 is set to 10N according to the material characteristics. If the material is wet, the heating temperature is set to 80℃.

[0027] The material to be screened is conveyed to the conical diffusion airflow mixing chamber 2 by the screw conveyor of the feeding device 1. The airflow system introduces compressed air into the mixing chamber. Under the action of the spiral guide vanes 3, the material and the airflow are fully atomized and mixed to form a uniform material-airflow mixture, which is then spirally propelled along the screen axis.

[0028] After the material-air mixture enters the screening section, the four slit-shaped nozzles 20 spray air at the set flow rate. The airflow, which combines vertical and 30° oblique injection, evenly covers the screen surface. Under the air pressure of 0.4 MPa, fine materials with a particle size of less than 200 mesh pass through the screen body 5 and enter the discharge device for discharge; coarse materials with a particle size of more than 200 mesh are transported along the inner wall of the screen cylinder to the coarse material outlet 24.

[0029] During the screening process, the pulse jet nozzle 12 periodically sprays reverse high-pressure airflow to remove residual materials inside the screen holes; the flexible ball 13, driven by the impeller, knocks on the outside of the screen to remove materials adhering to the surface; the temperature sensor 18 monitors the temperature inside the heating and insulation jacket 16 in real time, and the control system adjusts the power of the spiral heating wire 17 according to the monitoring data to maintain the temperature at 80℃ and prevent damp materials from clumping and adhering.

[0030] Under the negative pressure generated by the venturi tube acceleration section 22, the coarse material at the coarse material outlet 24 is drawn to the return channel. When passing through the cyclone separator 23, the coarse material is separated from the dust in the return airflow. The dust enters the collection device through the dust discharge port. The separated coarse material re-enters the feeding device 1, mixes with the new feed, and is screened again. The purified airflow is partially returned to the airflow system for reuse, realizing recycling and energy saving.

[0031] Through the above process, the circulating airflow screening equipment of this embodiment can achieve efficient screening of multi-size and easily clogged materials, with a screening efficiency of ≥90%, a screen service life extended by more than 30%, and an energy consumption reduction of more than %.

[0032] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A circulating gas stream screening apparatus characterized by, The application relates to a continuous screening device for material, which comprises feeding devices (1), screening devices (4), airflow circulating devices (21), discharging devices and control systems electrically connected with the devices respectively; the screening devices (4) are provided with adjustable aperture screen assembly and composite anti-blocking screen cleaning assembly (11); the airflow circulating devices (21) adopt a partitioned airflow guide type airflow injection structure and a backflow purification structure, and realize continuous screening operation of materials through linkage of the devices.

2. The circulating gas stream sizing apparatus of claim 1, wherein, The screen assembly of the screening devices (4) is a multi-layer nested structure, the anti-blocking screen cleaning assembly (11) is a composite structure of airflow pulse and flexible knocking, and the anti-blocking screen cleaning assembly (11) is provided with a heating and heat preservation structure.

3. The circulating gas stream sizing apparatus of claim 2, wherein, The screen body (5) of the screen assembly is a double-layer cylindrical structure, comprising an inner layer of porous adjusting cylinder (6) and an outer layer of fixed screen cylinder (7), the screen body (5) is provided with elastic expansion positioning mechanism (8) at both ends, and the elastic expansion positioning mechanism (8) comprises expansion rollers (9) and spring assemblies (10).

4. The circulating gas stream sizing apparatus of claim 3, wherein, The inner layer of porous adjusting cylinder (6) adopts wear-resistant ceramic coating material, the outer layer of fixed screen cylinder (7) is matched with stainless steel or fiber screen; the alignment degree of the aperture of the inner layer of porous adjusting cylinder (6) and the outer layer of fixed screen cylinder (7) can be adjusted, so that the continuous adjustable screening aperture of 80-530 meshes is realized.

5. The circulating gas stream sizing apparatus of claim 2, wherein, The anti-blocking screen cleaning assembly (11) comprises pulse air jet nozzles (12) arranged uniformly along the inner side of the screen in the axial direction, flexible bouncing balls (13) connected to the wind wheel support (15) through adjustable telescopic springs (14), and a heating and heat preservation interlayer (16) wrapped outside the screen; the pulse air jet nozzles (12) are linked with the airflow system, and the heating and heat preservation interlayer (16) is provided with spiral heating wires (17) and temperature sensors (18) laid in the heating and heat preservation interlayer (16) and is provided with a heat preservation layer (19) outside.

6. The circulating gas stream sizing apparatus of claim 5, wherein, The flexible bouncing ball (13) is a silica gel wrapped structure, the elastic force of the adjustable telescopic spring (14) can be adjusted according to the screen aperture and the material characteristics; the heating temperature of the heating and heat preservation interlayer (16) is 50-120 DEG C.

7. The circulating gas stream sizing apparatus of claim 1 wherein, The airflow circulating device (21) comprises a conical diffusion type airflow mixing cavity (2) arranged at the feeding end, a plurality of slotted jet pipes (20) arranged along the length direction of the screen, and a Venturi tube and cyclone separation integrated structure arranged between the coarse material outlet (24) and the feeding device (1); the inner wall of the conical diffusion type airflow mixing cavity (2) is provided with spiral guide vanes (3), and the Venturi tube and cyclone separation integrated structure comprises a Venturi tube accelerating section (22) and an embedded cyclone separator (23).

8. The circulating gas stream sizing apparatus of claim 7, wherein, The number of the slotted jet pipes (20) is 3-5, each section is independently controllable, and the jet pipe angle is combinedly arranged in the vertical incidence and 30 DEG oblique incidence; the cyclone separator (23) is used for separating dust in the backflow airflow, and the separation efficiency is greater than or equal to 95%.

9. The circulating gas stream sizing apparatus of claim 1 wherein, The control system is used for controlling the operation parameters, including the screen aperture adjusting parameter, the pulse air jet frequency, the flexible knocking force, the heating temperature of the heating and heat preservation interlayer (16), and the airflow pressure and flow of the airflow circulating device (21).

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