Device and method for removing fine particles from powder collected by cyclone separator

Abstract

A device and method for removing fine particles from powder collected by a cyclone separator. The device comprises a secondary air guide ring, which comprises multiple secondary air inlets, and each secondary air inlet comprises a slit. Before particles enter a discharging port of a cyclone separator, the secondary air guide ring introduces upward airflow by means of the secondary air inlets, air feed is conducted by means of the slits to form an air knife, and the air knife tangentially enters the cyclone separator along a secondary air flow channel in the secondary air guide ring. The morphological parameters of the slits and the air velocity and flow rate of the air knife meet the following constraint conditions: the air knife does not damage the rotating flow field in the cyclone separator, and the air knife can break up particle agglomerates and further sort the particles while effectively preventing large particles in the cyclone separator from being removed.

Description

Device and method for removing small particles from powder collected by a cyclone separator TECHNICAL FIELD

[0001] The present invention relates to the field of gas-solid separation technology in powder, and particularly relates to a device and method for removing small particles from powder collected by a cyclone separator. BACKGROUND

[0002] When a mechanical crushing device is used to prepare powder, a large amount of small particles less than 5-10 μm will be produced. The existence of these small particles increases the width of the particle size distribution, and in many cases, seriously affects the performance of the powder. For example, when powder coating is prepared, the existence of a large amount of such particles will greatly reduce the flowability of the powder, making it difficult to spray.

[0003] Therefore, in order to improve the quality of the powder, the small particles less than 5-10 μm should be removed as much as possible to reduce the particle size distribution.

[0004] In the prior art, for products with a small average particle size, various classifiers are used to remove small particles during the collection process; for products with a large average particle size, traditional screening methods can be used to remove small particles. Multiple classification operations can further reduce the content of small particles. However, these methods have high cost, high energy consumption, and complex operation (such as traditional impeller-type classifiers), and even cannot be performed (such as using a screening method to screen small particles less than 10 μm).

[0005] The cyclone separator has a solid particle collection function, and is a device that collects particles entrained by rotating airflow by centrifugal force without any moving parts. This device has simple structure, low cost, and high efficiency, and is widely used in gas-solid separation operations. However, the existing cyclone separator has almost no particle classification function except for removing a small amount of small particles. Although there are existing solutions to improve the cyclone separator to classify particles, there are the following technical problems: complex design, high cost, and complex operation control. SUMMARY

[0006] To solve the above technical problems, the present invention discloses a device for removing small particles from powder collected by a cyclone separator, which comprises:

[0007] A secondary air guide ring comprising a plurality of secondary air inlets arranged, each secondary air inlet having a gap, wherein

[0008] Before the particles enter the discharge port of the cyclone separator, the secondary air guide ring uses the secondary air inlets to introduce upward airflow, and the wind knife is formed by the gap air inlet, which enters the interior of the cyclone separator along the secondary air flow channel in the secondary air guide ring,

[0009] The gap has a topological parameter, and the air speed and flow rate of the air knife satisfy the following constraints: the air knife does not destroy the rotating flow field inside the cyclone separator, and the air knife can effectively avoid the removal of large particles inside the cyclone separator while breaking the particle clusters and further separating the particles.

[0010] Preferably,

[0011] The gap is formed between every two adjacent guide vanes.

[0012] Preferably,

[0013] A plurality of secondary air inlets are uniformly and circumferentially distributed along the outermost side of the secondary air guide ring; each gap corresponding to the plurality of secondary air inlets extends from the outermost side of the secondary air guide ring to the innermost side edge of the secondary air guide ring.

[0014] The secondary air guide ring is arranged above the discharge port of the cyclone separator via a flange.

[0015] Preferably,

[0016] The secondary air guide ring is arranged directly above the discharge port of the cyclone separator and is bolted and clamped by a flange when installed.

[0017] Preferably,

[0018] The secondary air guide ring comprises a guide vane carrying ring piece for carrying guide vanes, and guide vanes carried by the guide vane carrying ring piece, wherein

[0019] The guide vane carrying ring piece is a sheet-shaped circular ring with an inner diameter and an outer diameter,

[0020] The guide vanes are used to form a secondary air flow channel.

[0021] Preferably,

[0022] The guide vanes are a plurality of,

[0023] The guide vane carrying ring piece is a single guide vane carrying ring piece or two opposite guide vane carrying ring pieces.

[0024] Preferably,

[0025] When the guide vane carrying ring piece is a single guide vane carrying ring piece, a plurality of guide vanes are uniformly attached to the guide vane carrying ring piece along its axial direction,

[0026] When the guide vane carrying ring piece is two guide vane carrying ring pieces, a plurality of guide vanes are uniformly attached between the two opposite guide vane carrying ring pieces along their axial directions.

[0027] Preferably,

[0028] The inner and outer diameters of the guide wire bearing ring piece are the same as those of the flange.

[0029] Preferably,

[0030] The inner and outer ends of each guide wire are located at the inner and outer diameter edges of the guide wire bearing ring piece, respectively.

[0031] Preferably,

[0032] The cross section of the guide wire is circular, square or other shapes,

[0033] The bending direction of the guide wire is convex, straight and concave.

[0034] Preferably,

[0035] The topographic parameters of the gap include the height of the gap, wherein the height of the gap is equal to the maximum radial dimension of the guide wire. For example, when the cross section of the guide wire is circular, the maximum radial dimension is equal to the diameter of the guide wire.

[0036] Preferably,

[0037] The topographic parameters of the gap include the width of the gap, wherein the width of the gap is equal to the distance between every two guide wires.

[0038] Preferably,

[0039] When the number of guide wires, the shape of the cross section, the width of the gap, and the bending direction and its angle are all constant, the secondary air guide ring can realize the separation of different particles by adjusting the height of the gap. Preferably,

[0040] The material of the guide wire bearing ring piece and the guide wire is a hard material.

[0041] Preferably,

[0042] The hard material includes metal and plastic.

[0043] Preferably,

[0044] The number of guide wires is greater than or equal to 4.

[0045] Preferably,

[0046] The height of the guide wire is 0.25-3mm.

[0047] Preferably,

[0048] The angle between the radius line through the outer end of the guide wire and the radius line through the inner end of the guide wire is 0-80°.

[0049] Further, the application also discloses a method for removing small particles in powder collected by a cyclone separator, comprising the following steps:

[0050] Before the particles enter the discharge port of the cyclone separator, the upward airflow is introduced by using the secondary air inlet, and the air knife is formed by the gap air inlet, the air knife enters the inside of the cyclone separator in the tangential direction of the secondary air flow channel,

[0051] The appearance parameters of the gap, the air speed and the flow of the air knife meet the following constraint conditions: the air knife does not destroy the rotating flow field inside the cyclone separator, and the air knife can effectively avoid that the large particles inside the cyclone separator are removed, and at the same time, the particle agglomerates are broken and the particles are further separated.

[0052] Compared with the prior art, the application has the following beneficial effects:

[0053] The device and the method for removing small particles in powder collected by a cyclone separator provided by the application have the advantages of simple scheme, convenient operation, and the like, and provide a simple, convenient, economical and feasible method for simultaneously realizing gas-solid separation and particle classification.

[0054] 1. The small particle agglomerates are broken by the air knife, which is beneficial to separate the fine small particles and ensure the removal efficiency of the fine small particles;

[0055] 2. The small flow upward airflow is used to remove the fine small particles, so that part of the large particles is not taken away by the large flow upward airflow, and the product yield is ensured;

[0056] 3. The channel formed between the guide vanes is used to force the secondary air to form the tangential air knife, so that the rotation direction of the secondary air is ensured to not destroy the flow field inside the cyclone separator, and the removal efficiency of the fine small particles and the product yield are improved.

[0057] 4. The structure is simple, the manufacturing cost is low, and the use is convenient, and the application provides a simple, convenient, economical and feasible method for simultaneously realizing gas-solid separation and particle classification.

[0058] In addition, the secondary air in the present application adopts a slit air inlet, and the gas enters the inside of the cyclone separator along a preset flow channel in a tangential direction in the secondary air guide ring, without destroying the internal rotating flow field; the gas is forced to enter the inside of the cyclone separator along the secondary air flow channel in the secondary air guide ring, the air knife with high gas speed and low flow rate in the slit can effectively break up particle clusters, and large particles are avoided to be removed, so that the removal of small particles is realized without loss of recovery rate as much as possible. BRIEF DESCRIPTION OF DRAWINGS

[0059] Fig. 1 is a schematic diagram of a cyclone separator and a device for removing small particles in the collected powder in the cyclone separator according to an embodiment of the present application;

[0060] Fig. 2 is a schematic diagram in another schematic manner of Fig. 1;

[0061] Fig. 3 is a schematic diagram of guide wires with different bending directions (such as convex, linear and concave) and different angles (exemplarily, three angles are taken as examples) according to embodiments of the present application;

[0062] The arrow direction in the figure is the gas flow direction of the secondary air. DETAILED DESCRIPTION

[0063] All the features disclosed in this specification, except for those mutually exclusive and / or steps, can be combined in any way. The present application will be described in detail below with reference to the accompanying drawings.

[0064] As shown in Fig. 1, it includes four parts a) to d), wherein part a) schematically shows a typical tangential introduction type cyclone separator, including a cylindrical cylinder in the upper part, a conical cylinder in the lower part, a gas inlet pipe above the cylindrical cylinder, an exhaust pipe inserted into the upper part of the cylindrical cylinder and a discharge port at the bottom of the conical cylinder. Before the cyclone separator is modified by the device of the present application, all particles enter the top of the cyclone separator along the tangential direction with the gas flow under the action of the exhaust port suction, and then flow downward along the inner wall of the cylindrical cylinder in a spiral shape under the action of gravity and centrifugal force. A part of the gas is discharged from the cyclone separator through the inner vortex, and the remaining gas containing particles forms an outer vortex on the inner wall of the cyclone separator. When close to the bottom of the separator, the gas flow rate is greatly reduced, and finally moves upward under the action of the exhaust port suction, forming an inner vortex in the center of the cyclone separator. The inner vortex continuously takes away the gas of the outer vortex in the movement process, a small amount of small particles subjected to the action of air force are also taken away, and the main particles fall into a closed collection tank or a star-shaped discharge device or other types of discharge devices as products under the action of gravity through the conical bottom outlet of the separator.

[0065] Referring to the b), c), d) parts of Fig. 1, Fig. 2 and Fig. 3, a secondary air guide ring is arranged above the discharge port between the upper and lower flanges. The secondary air guide ring is composed of one or two guide wire carrying ring pieces and a plurality of guide wires evenly attached on the separate guide wire carrying ring piece or between the two guide wire carrying ring pieces. The inner and outer diameters of the guide wire carrying ring piece are the same as the inner and outer diameters of the connecting flanges of the cyclone separator, and the inner end and outer end of the guide wire are located at the inner diameter edge and outer diameter edge of the guide wire carrying ring piece, respectively. The secondary air guide ring includes a plurality of secondary air inlets arranged, each secondary air inlet having a gap, wherein the gap is formed between each adjacent two guide wires. The channel formed between the guide wires is used to guide the direction of the inlet air, and the arrangement direction of the guide wires is consistent with the direction of the air flow in the cyclone separator. The shape of the guide wire is a straight line or a curve, and the included angle between the radius passing through the outer end of the guide wire and the radius passing through the inner end of the guide wire is 0 to 80°.

[0066] The application utilizes the secondary air inlet to introduce upward air flow, and utilizes the high-speed air flow formed by the gap inlet air to break up the particle clusters and further separate the particles before the particles enter the discharge port. At the same time, the guide effect of the guide ring makes the air rotate into the cyclone separator, avoiding the loss of large particles caused by simple upward air flow. The application realizes the removal of small particles while reducing the loss of recovery rate, reduces the width of the particle size distribution, improves the product quality, and provides a simple, convenient, economical and feasible method for simultaneously realizing gas-solid separation and particle classification.

[0067] Embodiment 1 of the device for removing small particles in the collected powder of a cyclone separator and the cyclone separator matched therewith according to the application:

[0068] In the cyclone separator shown in Fig. 1, a secondary air guide ring is added to the discharge port at the bottom of the conical cylinder. The guide ring is composed of guide wires and guide wire carrying ring pieces. The inner diameter of the guide wire carrying ring piece is 58 mm, and the outer diameter is 80 mm. Sixteen cylindrical guide wires are evenly arranged on the guide wire carrying ring piece, and the guide wires are placed downward to be attached to the guide wire carrying ring piece in the axial direction. The inclination direction of the guide wires is consistent with the direction of the air flow in the cyclone separator. The diameter of the guide wire (so that the height of the gap is 1 mm. The bending direction of the guide wire is convex, and the included angle between the radius passing through the outer end of the cylindrical guide wire and the radius passing through the inner end of the guide wire is 45°.

[0069] Embodiment 2 of the device for removing small particles in the collected powder of a cyclone separator and the cyclone separator matched therewith according to the application:

[0070] The rest of the parameters are the same as those in Example 1, except that: 8 square guide vanes are uniformly arranged on the guide vane bearing ring, the diameter of the guide vanes is 1.5 mm, the guide vanes are straight, and the angle between the radius passing through the outer end of the guide vanes and the radius passing through the inner end of the guide vanes is 70°.

[0071] An embodiment 3 of the device for removing small particles in the collected powder of a cyclone separator and a cyclone separator matched therewith according to the application is provided.

[0072] The rest of the parameters are the same as those in Example 1, except that: 12 square guide vanes are uniformly arranged on the guide vane bearing ring, the diameter of the guide vanes is 0.5 mm, the guide vanes are convex, and the angle between the radius passing through the outer end of the guide vanes and the radius passing through the inner end of the guide vanes is 30°.

[0073] An embodiment 4 of the device for removing small particles in the collected powder of a cyclone separator and a cyclone separator matched therewith according to the application is provided.

[0074] The rest of the parameters are the same as those in Example 1, except that: the diameter of the guide vanes is 0.7 mm, the guide vanes are concave, and the angle between the radius passing through the outer end of the guide vanes and the radius passing through the inner end of the guide vanes is 20°.

[0075] Further, through experiments, the diameter of the guide vanes can be 0.25-3 mm, and the angle between the radius passing through the outer end of the guide vanes and the radius passing through the inner end of the guide vanes can be 0-80°. As described above, in the application, the topographic parameters of the gap, the gas velocity and the flow rate of the air knife satisfy the following constraint conditions: the air knife does not destroy the rotating flow field inside the cyclone separator, and the air knife can effectively avoid the removal of large particles inside the cyclone separator while breaking the particle agglomerates and further separating the particles. Therefore, in specific application scenarios, appropriate guide vane diameters and various parameters can be selected according to requirements.

[0076] An embodiment 5 of the device for removing small particles in the collected powder of a cyclone separator and a cyclone separator matched therewith according to the application is provided.

[0077] The rest of the parameters are the same as those in Example 1, except that: the diameter of the guide vanes is 3 mm, the outer diameter of the guide vane bearing ring is 188 mm, and the inner diameter of the guide vane bearing ring is 134 mm.

[0078] It should be noted that the topographic parameters of the gap include the height of the gap, wherein the height of the gap is equal to the maximum radial dimension of the guide vanes. For example, when the cross section of the guide vanes is circular, the maximum radial dimension is equal to the diameter of the guide vanes.

[0079] Preferably,

[0080] The profile parameters of the gap include: the width of the gap, wherein the width of the gap is equal to the distance between every two guide vanes.

[0081] Preferably,

[0082] When the number of the plurality of guide vanes, the shape of the cross section, the width of the gap, and the bending direction and the angle thereof are all unchanged, the secondary air guide ring can realize the separation of different particles by adjusting the height of the gap.

[0083] Application Example 1

[0084] A small air classifier mill is selected, and the device of Example 1 and the cyclone separator matched therewith are connected at the end. The feed is polyester paint flakes with a diameter of 5-8 mm. Under a certain main mill speed and classifier frequency, polyester coarse powder paint is prepared.

[0085] Comparative Application Example 1-1

[0086] A small air classifier mill is selected, and the device of Example 1 and the cyclone separator matched therewith are connected at the end, but the guide vanes are removed. The raw material and operating conditions are the same as those of Application Example 1.

[0087] Comparative Application Example 1-2

[0088] A small air classifier mill is selected, and a cyclone separator is connected at the end, which has the same size as the cyclone separator mentioned in Example 1 but does not use the device described in the foregoing embodiments of the application. The raw material and operating conditions are the same as those of Application Example 1.

[0089] Application Example 2

[0090] A small air classifier mill is selected, and the device of Example 2 and the cyclone separator matched therewith are connected at the end. The feed is polyester paint flakes with a diameter of 5-8 mm. Under a certain main mill speed and classifier frequency, polyester fine powder particles are prepared.

[0091] Comparative Application Example 2

[0092] A small air classifier mill is selected, and a cyclone separator is connected at the end, which has the same size as the cyclone separator mentioned in Example 2 but does not use the device described in the foregoing embodiments of the application. The raw material and operating conditions are the same as those of Application Example 2.

[0093] Application Example 3

[0094] A small air classifier mill was used, with a cyclone separator attached at the end. The feed material was an epoxy paint with a median particle size of about 37 μm. The mill and classifier were operated at a low speed so that they did not have a grinding function, and the particles passed through the classifier of the mill itself and entered the cyclone separator. This was done to examine the effect of the present invention on the removal of over-fine powder from a coarse powder paint particle product.

[0095] Comparative application example 3

[0096] A small air classifier mill was used, with a cyclone separator attached at the end. The cyclone separator was the same size as the one mentioned in application example 3, but without the device described in the previous embodiments of the present invention. The feed material and operating conditions were the same as in application example 3.

[0097] Application example 4

[0098] A small air classifier mill was used, with the device of application example 4 and its associated cyclone separator attached at the end. The feed material was an epoxy paint with a median particle size of about 19 μm. The mill and classifier were operated at a low speed so that they did not have a grinding function, and the particles passed through the classifier of the mill itself and entered the cyclone separator. This was done to examine the effect of the present invention on the removal of over-fine powder from a fine powder paint particle product.

[0099] Comparative application example 4-1

[0100] A small air classifier mill was used, with the device of application example 4 and its associated cyclone separator attached at the end, but without the guide vanes. The feed material and operating conditions were the same as in application example 4.

[0101] Comparative application example 4-2

[0102] A small air classifier mill was used, with a cyclone separator attached at the end. The cyclone separator was the same size as the one mentioned in application example 4, but without the device described in the previous embodiments of the present invention. The feed material and operating conditions were the same as in application example 4.

[0103] Application example 5

[0104] A production air classifier mill was used, with the device of application example 5 and its associated cyclone separator attached at the end. The feed material was a polyester paint chip with a diameter of 5-8 mm. Polyester fine powder particles were produced at a certain mill speed and classifier frequency.

[0105] Comparative application example 5

[0106] A production air classifier mill was used, with a cyclone separator attached at the end. The cyclone separator was the same size as the one mentioned in application example 5, but without the device described in the previous embodiments of the present invention. The feed material and operating conditions were the same as in application example 5.

[0107] The effect evaluation is shown in Table 1 below:

[0108] The effect of the cyclone separator modification is represented by comparing the small particle size, particle size distribution and recovery rate of the products under different conditions. In Table 1, D 10 represents that the volume of particles less than this particle size accounts for 10% of the total volume of particles, the medium particle size D 50 represents that the particles greater than or less than this value each account for 50%, D 90 represents that the volume of particles less than this particle size accounts for 90% of the total volume of particles. The particle size span Span = (D 90 -D 10 ) / D 50 is used to represent the particle size distribution. In order to comprehensively verify the classification effect of the cyclone separator, both flaky and powder feedstocks are used in the present application, and the products are controlled to be within the coarse powder and fine powder particle ranges for investigation.

[0109] Table 1

[0110] As shown in Table 1, taking application example 1, comparative application example 1-1 and comparative application example 1-2 as examples, the device and method of the present application have excellent effect of removing excessively fine particles compared with comparative application example 1-2, and for various raw materials, the D 10 of the representative small particles is increased, the span Span of the representative particle size distribution is greatly reduced, and the decrease in the recovery rate is within an acceptable range; while for comparative application example 1-1, although compared with comparative application example 1-2, the D 10 is increased, the span Span is reduced, but the decrease in the recovery rate is relatively large, and the cost will be obviously increased because of more waste; and the span Span of application example 1 is the lowest among application example 1, comparative application example 1-1 and comparative application example 1-2, indicating that the classification effect is the best. Taking application example 1 and comparative application example 1-1 as examples, compared with the application scheme with a guide wire bearing ring piece and secondary air inlet without guide wire, the device and method of the present application have narrower particle distribution and higher product recovery rate. In summary, the present application reduces the particle distribution width and realizes particle classification without increasing additional energy consumption by a simple and low-cost scheme, and reduces the yield loss caused by secondary air classification of conventional equipment.

[0111] The above is the embodiment of the present application. The present application is not limited to the above-described embodiments, and any person should know that any structural changes made under the inspiration of the present application fall within the protection scope of the present application. Any technical scheme with the same or similar technical scheme as the present application falls within the protection scope of the present application.

Claims

1. A device for removing small particles from powder collected by a cyclone separator, characterized in that, The device comprises: A secondary air guide ring comprising a plurality of secondary air inlets arranged, each secondary air inlet having a slit, wherein, Before the particles enter the discharge port of the cyclone separator, the secondary air guide ring introduces upward airflow through the secondary air inlets and forms a wind knife through the slit inlet, and the wind knife enters the interior of the cyclone separator tangentially along the secondary air flow channel in the secondary air guide ring, The topography parameters of the slit, and the air speed and flow of the wind knife satisfy the following constraint conditions: the wind knife does not destroy the rotational flow field in the interior of the cyclone separator, and the wind knife can effectively prevent large particles in the interior of the cyclone separator from being removed while breaking up particle clusters and further separating particles.

2. The device according to claim 1, wherein A plurality of secondary air inlets are uniformly and circumferentially distributed along the outermost side of the secondary air guide ring, and each slit corresponding to the plurality of secondary air inlets extends from the outermost side of the secondary air guide ring to the innermost side edge of the secondary air guide ring.

3. The device according to claim 1, wherein The secondary air guide ring is arranged above the discharge port of the cyclone separator via a flange.

4. The device according to claim 1, wherein The secondary air guide ring comprises a guide wire carrying ring piece for carrying guide wires, and guide wires carried by the guide wire carrying ring piece, wherein The guide wire carrying ring piece is a sheet-shaped circular ring having an inner diameter and an outer diameter, The guide wires are used to form a secondary air flow channel.

5. The device according to claim 4, wherein The guide wires are a plurality of guide wires, The guide wire carrying ring piece is a single guide wire carrying ring piece or two opposite guide wire carrying ring pieces.

6. The device according to claim 5, wherein When the guide wire carrying ring piece is a single guide wire carrying ring piece, the plurality of guide wires are uniformly attached to the guide wire carrying ring piece along the axial direction thereof, When the guide wire carrying ring piece is two guide wire carrying ring pieces, the plurality of guide wires are uniformly attached between the two opposite guide wire carrying ring pieces along the axial direction thereof.

7. The device according to claim 4, wherein The inner diameter and the outer diameter of the guide wire carrying ring piece are the same as the inner diameter and the outer diameter of the flange.

8. The device according to claim 6, wherein The inner end and the outer end of each guide wire are located at the inner diameter edge and the outer diameter edge of the guide wire carrying ring piece, respectively.

9. The device according to claim 4, wherein The cross section of the guide wire is circular, square or other shapes, The bending direction of the guide wire is convex, straight and concave.

10. A method of removing small particles from a powder collected by a cyclone separator, characterized by, The method comprises the following steps: Before the particles enter the discharge port of the cyclone separator, the secondary air guide ring introduces upward airflow through the secondary air inlets and forms a wind knife through the slit inlet, and the wind knife enters the interior of the cyclone separator tangentially along the secondary air flow channel in the secondary air guide ring, The topography parameters of the slit, and the air speed and flow of the air knife satisfy the following constraint conditions: the air knife does not destroy the rotating flow field inside the cyclone separator, and the air knife can effectively avoid the large particles inside the cyclone separator from being removed, while breaking the particle agglomerates and further separating the particles.

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