Apparatus and methods for improving the efficiency of powder airflow classification.

Abstract

This invention provides an apparatus and method for improving the efficiency of air classification of powders. The classification steps include: gas homogenization; particle size detection; air classification; particle size feedback; and dust removal. The apparatus includes several turbine classifiers connected in series. A drive shaft passes through both ends of the classifier cylinder. Turbines are mounted on the drive shaft. Two drive motors are configured. Each turbine includes an annular frame fixed to the drive shaft, several curved plates arranged around the annular frame, and a curved plate angle adjustment mechanism. The center of each curved plate is hinged to the annular frame to allow rotation. The curved plate angle adjustment mechanism is used to adjust the angle of the curved plates. Online particle size analyzers are installed at the material inlet and outlet. The rotation angle of the curved plates and the operating power of the drive motors are adjusted based on the measurement results from the online particle size analyzers. This invention improves the accuracy, efficiency, and intelligence of air classification technology, making it suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material classification, in particular to a device and method for improving the classification efficiency of powder airflow classification. BACKGROUND

[0002] When powder material is subjected to classification, a turbo classifier is usually used. The main function of the turbo classifier is to separate powder according to particle size by using the upward airflow and the influence of the turbine on the airflow.

[0003] The significance of classifying powder material is illustrated by the problem of wheat in actual harvesting: if wheat encounters continuous rainy days during the harvesting season or is not sufficiently dried during storage, the wheat will germinate. After the wheat germinates, the quality will deteriorate, the activity of hydrolytic enzymes such as amylase and protease will increase, the tenacity will weaken, and the processing quality and eating quality will obviously deteriorate, causing huge economic losses. Studies have shown that the quality of slightly germinated wheat flour is significantly improved after removing fine powder with a particle size of about 20 μm.

[0004] However, powder materials such as wheat flour have a relatively high water content, usually about 14%, and are more likely to agglomerate into clusters than other powders, which is not suitable for screening with a mesh. The existing airflow classification technology not only has low yield, but also has the "entrainment" phenomenon of coarse containing fine and fine containing coarse during the classification process.

[0005] Therefore, during the classification process, how to improve the yield and reduce the "entrainment" phenomenon, and thus improve the classification precision and classification efficiency is an important problem to be considered.

[0006] Currently, the main physical factors affecting powder airflow classification include:

[0007] 1. The rotational speed of the turbine in the commonly used turbo classifier is low, and the structure of the existing turbo classifier makes it difficult to improve the power of the turbine, such as Figure 1 As shown, the turbine in the existing turbo classifier is driven by a single motor, and the lower part is the feeding space and the coarse material discharge space. The power improvement can only rely on upgrading the motor power, which is too expensive;

[0008] 2. The main principle of turbine operation is to improve the centrifugal force by rotating the turbine. Coarse material is thrown to the cylinder wall under the action of centrifugal force and falls off, and fine material is attracted by the airflow and continues to rise, achieving separation. However, the upward airflow entering the turbine blade is prone to collision with the blade and cause turbulence, causing the fine material to lose speed and fall into the coarse material;

[0009] 3. The operating power of the turbo classifier is fixed and cannot be adjusted according to the characteristics of the incoming material, resulting in power mismatch and affecting the classification effect.

[0010] In order to solve the above problems, people have been seeking an ideal technical solution. SUMMARY

[0011] The present application aims at the deficiencies of the prior art, and provides a device and method for improving the classification efficiency of powder airflow classification, which can improve the turbine speed limit and the turbine classification effect.

[0012] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0013] A device for improving the classification efficiency of powder airflow classification, comprising a classifier barrel, a transmission shaft, a driving motor, a turbine, an online particle size determination device and a control device.

[0014] The top horizontal side of the classifier barrel is provided with a fine material outlet, the bottom end is provided with a coarse material outlet biased to one side, and the lower side of the side part is provided with a material inlet entering along the tangent direction of the inner wall of the classifier barrel.

[0015] The transmission shaft penetrates the upper and lower ends of the classifier barrel and is installed together with the upper and lower ends of the classifier barrel through bearings, the turbine is installed on the transmission shaft, and the turbine is located inside the classifier barrel and between the material inlet and the fine material outlet.

[0016] The driving motor is configured as two and is respectively arranged at the top end and the bottom end of the transmission shaft.

[0017] The turbine comprises a ring-shaped frame body fixed with the transmission shaft, a plurality of bent plates arranged around the ring-shaped frame body, and a bent plate angle adjusting mechanism, the center of the bent plate is hingedly connected with the ring-shaped frame body so that the bent plate can rotate at an angle, and the bent plate angle adjusting mechanism is used for adjusting the angle of the bent plate.

[0018] The online particle size determination device is respectively installed at the material inlet and outlet, and the control device feeds back and adjusts the rotation angle of the bent plate and the operating power of the driving motor according to the measurement results of the online particle size determination device.

[0019] As described above, the bent plate is an arc-shaped plate, and the two ends of the bent plate are hingedly connected with the ring-shaped frame body.

[0020] As described above, the bent plate angle adjusting mechanism comprises a radial support sleeve fitted on the transmission shaft, the distal end of each arm of the radial support is provided with a sliding block, the inner side of the arc of each bent plate is provided with a sliding groove, the sliding block is installed in the sliding groove, and the bent plate is driven to rotate by rotating the radial support.

[0021] As described above, the radial support and the transmission shaft are in a lockable and unlockable structure, in the locked state, the radial support rotates synchronously with the transmission shaft, in the unlocked state, the radial support and the transmission shaft can rotate relative to each other, and the rotating driving mechanism of the radial support is arranged outside the turbine.

[0022] As described above, the transmission shaft and the driving motor are driven in a direct connection mode.

[0023] As described above, the inner arc side of the bent plate faces the opposite direction of the turbine.

[0024] A method for improving the classification efficiency of powder airflow classification, comprising a plurality of sequentially connected devices for improving the classification efficiency of powder airflow classification, and the classification is carried out by the following method:

[0025] (1) Gas homogenization: through the gas homogenization device, the powder and air form a uniform gas-solid two-phase flow;

[0026] (2) Particle size detection: use an online particle size measuring device to detect the particle size distribution of the powder, and preliminarily set the parameters of each device for improving the classification efficiency of powder airflow classification according to the product requirements;

[0027] (3) Airflow classification: the airflow enters each device for improving the classification efficiency of powder airflow classification in sequence for classification;

[0028] (4) Particle size feedback: the particle size distribution of the powder at the discharge port of each device for improving the classification efficiency of powder airflow classification is detected in real time, and the parameters of each device for improving the classification efficiency of powder airflow classification are corrected;

[0029] (5) Dust removal: the gas after airflow classification is filtered by a dust removal device to remove dust and prevent air pollution.

[0030] As described above, the cutting particle size of each airflow classifier is preset according to the following formula:

[0031]

[0032] Wherein: d T Cutting particle size (m);

[0033] r - turbine radius (m);

[0034] δ - material density (kg / m 3);

[0035] ρ - airflow density (kg / m 3);

[0036] V t - turbine speed (m / s);

[0037] V r Air flow velocity (m / s);

[0038] η - Air viscosity (Pa·s).

[0039] As described above, in step (5), the parameters of the device for modifying the classification efficiency of the airflow classification of the powder at each stage include the rotational speed of the turbine and the angle of the curved plate.

[0040] The present application has the following advantages:

[0041] 1. The turbine is modified, the original blades of the turbine are removed and replaced with curved plates, the curved plates are arrayed along the circumference and the angle is adjustable, by adjusting the angle of the curved plate, in the process of rotating with the turbine, the fine particles can still enter the interior of the turbine and be separated along with the low-pressure airflow in the turbine due to the turbulent flow of the curved plate and the light texture, the coarse particles are thrown out by the centrifugal force under the disturbance of the turbine rotation and fall off due to the loss of speed, and are separated;

[0042] The angle of the curved plate in the turbine can be changed to change the angle of the airflow cutting into the interior, when the expansion angle of the curved plate is basically parallel to the cutting direction of the airflow, the effect of suppressing turbulence is better, so by flexible adjustment, a suitable balance point can be found to effectively improve the separation precision;

[0043] 2. On the basis of the traditional classifier, two driving motors are designed to drive a transmission shaft, the running speed of the transmission shaft can break through the original limit and reach a new height, significantly improving the performance of the classifier; the classification area can also be increased, so that the fine particles carried in the coarse particles that lose speed can meet the airflow of the incoming material during the falling process and be washed, and then re-enter the airflow.

[0044] Moreover, since the transmission shaft penetrates the entire classifier cylinder, a cylindrical space is naturally formed inside the classifier cylinder, and the vortex effect is more significant;

[0045] 3. Through the intervention of the online particle size determination device, the current classification effect of the classifier can be reflected in real time, and then the rotational speed of the classifier and the angle of the curved plate in the worm gear are adjusted by the control device to reach the target preset particle size value, and the intelligent degree is higher. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is a structural schematic diagram of a traditional airflow classifier in the background art of the present application.

[0047] Figure 2 is a structural schematic diagram of an airflow classifier in the present application.

[0048] Figure 3 This is one of the structural schematic diagrams of the turbine in this invention.

[0049] Figure 4 This is the second schematic diagram of the turbine structure in this invention.

[0050] In the diagram: 1. Classifier cylinder; 2. Drive shaft; 3. Drive motor; 4. Turbine; 5. Online particle size measuring device; 6. Fine material outlet; 7. Coarse material outlet; 8. Material inlet; 41. Annular frame; 42. Bending plate; 43. Radial support; 44. Sliding block. Detailed Implementation

[0051] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0052] like Figures 2-4 As shown, a device for improving the efficiency of powder airflow classification includes a classifier cylinder 1, a drive shaft 2, a drive motor 3, a turbine 4, an online particle size measuring device 5, and a control device.

[0053] The top of the classifier cylinder 1 is provided with a fine material outlet 6 on the horizontal side, and a coarse material outlet 7 is provided on the bottom side, which is biased to one side. The lower side is provided with a material inlet 8 that enters along the tangential direction of the inner wall of the classifier cylinder 1. The material inlet enters along the tangential direction and matches the airflow space inside the cylindrical cylinder to form a vortex. The powder rises spirally under the action of the vortex and is classified by action with the turbine.

[0054] The drive shaft 2 passes through the upper and lower ends of the classifier cylinder 1 and is mounted together with the upper and lower ends of the classifier cylinder 1 through bearings. The turbine 4 is mounted on the drive shaft 2. The turbine 4 is located inside the classifier cylinder 1 and between the material inlet 8 and the fine material outlet 6. The presence of the drive shaft 2 makes the cylinder form a cylindrical structure, and the annular channel is more likely to form a vortex shape.

[0055] Two drive motors 3 are configured and respectively located at the top and bottom of the transmission shaft 2. The transmission shaft and the drive motors are driven by direct connection, which can significantly increase the speed of the turbine and meet the power requirements of the stage.

[0056] The turbine 4 includes an annular frame 41 fixed to the drive shaft, a plurality of curved plates 42 arranged around the annular frame 41, and a curved plate angle adjustment mechanism.

[0057] The bending plate angle adjustment mechanism includes a radial bracket 43 mounted on the transmission shaft. Each arm of the radial bracket 43 is provided with a slider 44 at its distal end. Each bending plate 42 has a groove on its inner arc side. The slider 44 is installed in the groove. By rotating the radial bracket, the bending plate is driven to rotate.

[0058] Wherein, the radial support and the transmission shaft are lockable and unlockable structure, for example, with the ring-shaped sleeve with a latch or compression bolt structure, in the locked state, the radial support rotates synchronously with the transmission shaft, in the unlocked state, the radial support and the transmission shaft can be relative rotation, the rotation driving mechanism of the radial support is arranged outside the turbine, in the preferred embodiment, the ring-shaped sleeve extends to the space outside the turbine, the angle of the radial support is adjusted by the angle-adjusting motor or other driving mechanism.

[0059] The adjustment of the bending plate angle can reduce the turbulence phenomenon between the bending plate and the airflow, avoid the collision of fine particle materials, and improve the classification accuracy.

[0060] The bending plate is an arc-shaped plate, the two ends of the center of the bending plate 42 are hingedly connected with the ring-shaped frame body 41 so that the bending plate 42 can rotate an angle, the bending plate angle adjusting mechanism is used to adjust the angle of the bending plate 42, and the inner arc side of the bending plate 42 faces the opposite direction of the turning direction of the turbine 4, which can make the airflow pass more smoothly.

[0061] The online particle size measuring device 5 is respectively installed at the material inlet and outlet, and the control device adjusts the rotation angle of the bending plate 42 and the operating power of the driving motor according to the measurement results of the online particle size measuring device 5.

[0062] The method for improving the classification efficiency of powder airflow classification by using the above device includes the several sequentially connected devices for improving the classification efficiency of powder airflow classification, and the classification is performed by the following method:

[0063] (1) Gas homogenization: through the gas homogenization device, the powder and air form a uniform gas-solid two-phase flow;

[0064] (2) Particle size detection: the online particle size measuring device is used to detect the particle size distribution of the powder, and the parameters of each device for improving the classification efficiency of powder airflow classification are preliminarily set according to the product requirements;

[0065] The cutting particle size of each airflow classifier is preliminarily set according to the following formula:

[0066]

[0067] Wherein: d T Cutting particle size (m);

[0068] r - turbine radius (m);

[0069] δ - material density (kg / m3);

[0070] ρ - airflow density (kg / m 3);

[0071] V t Turbine speed (m / s);

[0072] V r Airflow speed (m / s);

[0073] η - Air viscosity (Pa·s).

[0074] The particle size distribution curve can be obtained by the formula, and the rotation speed of each turbine and the rotation angle of the curved plate are set according to the corresponding relationship of the particle size distribution curve, wherein the turbine radius data are used as the adjustment basis of the rotation angle of the curved plate.

[0075] (3) Airflow classification: the airflow enters each device for improving the classification efficiency of the airflow of the powder in turn for classification;

[0076] (4) Particle size feedback: the particle size distribution of the powder at the discharge port of each device for improving the classification efficiency of the airflow of the powder is detected in real time, and the parameters of each device for improving the classification efficiency of the airflow of the powder are corrected according to the feedback; when the feedback shows that the coarse material is seriously entrained with the fine material, the rotation angle of the curved plate is adjusted, the influence of the turbulent flow is reduced, and the classification precision is improved.

[0077] Finally, the coarse material is discharged from the coarse material outlet at the bottom end, and the fine material is discharged from the fine material outlet at the top end, so that the classification is realized.

[0078] (5) Dust removal: the gas after the airflow classification is filtered by a dust removal device to remove dust and prevent air pollution.

[0079] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or some technical features can be replaced by equivalent ones; without departing from the spirit of the technical solutions of the present application, they should be covered in the technical solution range of the present application.

Claims

1. A method for improving the classification efficiency of a powder air classifier, the method comprising: The application relates to a powder airflow classification device, which comprises a plurality of sequentially connected powder airflow classification devices for improving classification efficiency, a classifier cylinder, a transmission shaft, a driving motor, a turbine, an online particle size measuring device and a control device. ​ A fine material outlet is arranged on the horizontal side of the top end of the classifier cylinder, a coarse material outlet is arranged on the bottom end of the classifier cylinder, and a material inlet is arranged on the lower side of the side of the classifier cylinder and enters along the tangent direction of the inner wall of the classifier cylinder. The transmission shaft penetrates through the upper and lower ends of the classifier cylinder and is mounted with the upper and lower ends of the classifier cylinder through bearings, the turbine is mounted on the transmission shaft, and the turbine is located inside the classifier cylinder and between the material inlet and the fine material outlet. The driving motor is configured as two and is arranged on the top end and the bottom end of the transmission shaft respectively. The turbine comprises a ring-shaped frame body fixed with the transmission shaft, a plurality of bent plates arranged around the ring-shaped frame body and a bent plate angle adjusting mechanism, the center of the bent plate is hingedly connected with the ring-shaped frame body so that the bent plate can rotate at an angle, and the bent plate angle adjusting mechanism is used for adjusting the angle of the bent plate. The online particle size measuring device is arranged on the material inlet and outlet respectively and is used for detecting the particle size distribution of the powder, and the control device feeds back and adjusts the rotating angle of the bent plate and the operating power of the driving motor according to the measuring results of the online particle size measuring device and the finished product requirements. The classification is carried out through the following methods: (1) gas homogenization: the powder and air form a uniform gas-solid two-phase flow through a gas homogenization device; (2) particle size detection: the online particle size measuring device is used to detect the particle size distribution of the powder, and the parameters of the powder airflow classification devices are preliminarily set according to the finished product requirements; the cutting particle size of each airflow classifier is preset and the following formula is used: wherein: d T - cut particle size (m); r --- turbine radius (m); delta - material density (kg / m3) 3 ) ; p - gas flow density (kg / m3); and 3 ) V t - turbine speed (m / s); V r - air flow speed (m / s); eta --- air viscosity (Pa.s); (3) airflow classification: the airflow enters each powder airflow classification device for classification in sequence; (4) particle size feedback: the powder particle size distribution of the discharge port of each powder airflow classification device is detected in real time, and the parameters of each powder airflow classification device are fed back and corrected; the parameters of each powder airflow classification device are corrected, including the rotating speed of the turbine and the angle of the bent plate; (5) dust removal: the gas after airflow classification is filtered through a dust removal device to remove dust and prevent air pollution.

2. The method of improving the classification efficiency of a powder air classifier according to claim 1, wherein: The bent plate is an arc plate, and the two ends of the bent plate are hingedly connected with the ring-shaped frame body.

3. The method of improving the classification efficiency of a powder air classifier according to claim 2, wherein: The bent plate angle adjusting mechanism comprises a radial support which is sleeved on the transmission shaft, each support arm of the radial support is provided with a sliding block, the inner side of the arc of each bent plate is provided with a sliding groove, the sliding block is mounted in the sliding groove, and the bent plate is driven to rotate by rotating the radial support.

4. The method of improving the classification efficiency of a powder air classifier according to claim 3, wherein: The structure between the radial support and the transmission shaft is lockable and unlockable, in the locked state, the radial support rotates synchronously with the transmission shaft, in the unlocked state, the radial support can rotate relative to the transmission shaft, and the rotating driving mechanism of the radial support is arranged outside the turbine.

5. The method of improving the classification efficiency of a powder air classifier according to claim 4, wherein: The transmission shaft and the driving motor are driven through direct connection.

6. The method of improving the classification efficiency of a powder air classifier according to claim 5, wherein: The inner arc side of the bent plate faces the opposite direction of the turbine rotation.

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