JP4097619B2 - Cyclone classifier - Google Patents

Description

  The present invention relates to an improvement of a cyclone classifier capable of adjusting a classification point according to the particle diameter of a powder.

  Conventionally, a cyclone classifier is known as a dry classifier for classifying powder. The cyclone classifier performs classification by blowing powder into the upper part of the cyclone tower together with air. That is, the coarse powder in the blown airflow receives centrifugal force by the swirling airflow, is separated from the airflow, reaches the peripheral wall, and is collected in the coarse powder collection chamber below the cyclone tower. On the other hand, the fine powder is sucked into the upper fine powder collecting tube by the negative pressure of the external blower and collected by the filter.

  The cyclonic classifier has the advantage that the structure is simple and there are no moving parts such as a rotating rotor like a rotor classifier and the burden of maintenance and inspection is small. However, the classification point is fixed by the structure of the cyclone tower, etc. Therefore, the classification point cannot be adjusted according to the particle diameter of the powder. For this reason, there is a problem that classification of powders having different classification points cannot be performed with one apparatus.

  In order to eliminate the drawbacks of the cyclonic classifier as described above, Patent Document 1 discloses that a conical inner guide is disposed upward between the cyclone tower and the coarse powder collecting chamber, and the inner guide cone is provided. A cover is provided in a range facing the shape guide surface, and an annular coarse powder discharge passage is formed long between the cover and the inner guide. In this cyclone classifier, blow-up air is blown into the coarse powder collecting chamber to reverse and raise the descending airflow in the cyclone tower to collect fine powder.

In the cyclonic classifier, the classification point can be changed by adjusting the vertical position of the inner guide and changing the width of the coarse powder discharge passage. However, the downflow to the coarse powder collection chamber and the upward flow of blow-up air collide with each other in the coarse powder discharge flow path, and the coarse powder is rolled up, resulting in a decrease in classification accuracy and classification efficiency. There was a problem.
JP 2001-179134 A (FIG. 2)

  The present invention has been made to solve the above-described conventional problems, and to provide a cyclone classifier having high classification accuracy and classification efficiency and easy adjustment of the classification point.

  The cyclonic classifier according to claim 1, which has been made to solve the above-mentioned problems, lifts the fine powder in the powder blown into the cyclone tower by blow-up air from the lower part of the cyclone tower and extracts it from above. In the cyclone classifier that collects the coarse powder from the coarse powder outlet at the lower part of the cyclone tower to the coarse powder collection chamber below the coarse powder outlet, an outer guide having an inner peripheral surface that widens toward the end of the coarse powder outlet is provided. The conical inner guide is disposed below the outer guide with the top thereof facing upward, and the inner peripheral surface of the outer guide and the conical guide surface of the inner guide are opposed to each other. An annular central partition is interposed between the peripheral surface and the conical guide surface, and a downflow passage through which coarse powder flows from the cyclone tower to the coarse powder collection chamber, and blow-up air from the coarse powder collection chamber. Flow in the cyclone tower It is characterized in that provided separately and increase flow passage to.

The cyclone classifier according to claim 2 is the cyclone classification device according to claim 1, wherein the conical air rectifying guide is provided on the bottom surface of the conical inner guide with the top thereof facing downward. .

The cyclonic classifier according to claim 3 is the invention according to claim 1 or 2, wherein a blow-up air blowing pipe is arranged in the coarse powder collecting chamber, and the air is blown into the blowing pipe in the blowing direction. Along with the provision of a rectifying path, an adjustment gate for adjusting the amount of blow-up air is provided at the inlet of the blowing pipe.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, either one or both of the central partition and the inner guide can be adjusted in the vertical direction. Furthermore, in the invention described in claim 1 or 2, a cylinder for guiding blow-up air to the upward flow passage can be connected to the lower end of the central partition wall.

  The cyclone classifier according to the present invention has an annular central partition disposed in a passage formed by the inner peripheral surface of the outer guide and the conical guide surface of the inner guide, and the downward flow in which the powder flows down the passage. Since the road and the upflow in which the blow-up air rises are divided, generation of turbulent flow due to the collision between the downflow and the upflow can be prevented, and thus the classification accuracy and the classification efficiency can be greatly improved. In the cyclone classifier of the present invention, the conical air rectifying guide is provided on the bottom surface of the inner guide with its top facing downward, so that blow-up air from below is turbulently flowed to the peripheral edge of the bottom surface of the inner guide. Can be sorted without causing it. In addition, a blow-up air blowing pipe is arranged in the coarse powder collecting chamber, and a rectifying path is provided in the blowing pipe along the air blowing direction, so that the blow-up air is rectified in the coarse powder collecting chamber. Can be blown up. In addition, since the adjustment gate is provided at the inlet of the blowing pipe, the amount of blow-up air can be easily adjusted.

  Moreover, since at least one of the central partition and the inner guide can be adjusted in the vertical direction, the classification point can be easily changed by adjusting the width of the downward flow passage and the width of the upward flow passage. Furthermore, since the cylinder is connected to the lower part of the central partition wall, the blow-up air can be reliably guided to the upward flow passage by this cylinder.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an outline of the configuration of a cyclone classifier according to the present invention, in which 1 is an injection material hopper for storing powder to be classified. The stored powder is quantitatively discharged by the injection material fixed supply device 2, but the powder is spirally formed at the upper part of the cyclone tower 5 by the air sent from the compressed air supply source 3 to the injection material dispersion nozzle 4. The powder is fed to the powder introduction unit 6.

  The cyclone tower 5 includes an upper straight cylindrical portion 5 a and a lower funnel-shaped tapered portion 5 b, and a coarse powder collecting chamber 7 is provided below the cyclone tower 5. At the lower end of the cyclone tower 5, a coarse powder outlet 8 for discharging the coarse powder to the coarse powder collecting chamber 7 is provided. Further, a fine powder collecting duct 9 for collecting fine powder is suspended from a ceiling portion of the cyclone tower 5 to a certain position of the straight cylinder portion 5a, and a negative pressure is applied to the cyclone tower 5 by the fan 11 of the dust collector 10. . The fine powder sucked into the fine powder collecting duct 9 is collected by the dust collector 10 through the fine powder collecting pipe 12. The coarse powder flows down the peripheral wall in the cyclone tower 5 and is collected from the coarse powder discharge port 8 to the coarse powder collection chamber 7 below.

  The detailed structure of the upper part of the coarse powder collecting chamber 7 is shown in FIG. The coarse powder outlet 8 is provided with an annular outer guide 21 having an inner peripheral surface 20 that expands downward toward the bottom. The outer guide 21 can be a tube with one end of the pipe expanded. Below the coarse powder outlet 8, a conical inner guide 22 is disposed with its sharp apex upward, and an inner peripheral surface 20 of the outer guide 21 and a conical guide surface 23 of the inner guide 22. It is opposed with a gap.

  Between the inner peripheral surface 20 and the conical guide surface 23, a conical annular central partition wall 24 having an upper opening smaller in diameter than the lower opening is interposed, and the inner peripheral surface 20 and the conical guide surface 23 are interposed. Two passages are formed in an annular shape by dividing the gap between the two passages. That is, between the inner peripheral surface 20 and the central partition wall 24, a downflow passage 26 is formed in which coarse powder that has flowed down along the peripheral wall of the tapered portion 5 b of the cyclone tower 5 flows downward. Between the surface 23 and the central partition wall 24, an upward flow passage 25 for blow-up air blown into the cyclone tower 5 is formed as described below.

  A cylinder 27 is connected to the lower end of the central partition wall 24. As shown in FIG. 3, a blow-up air blowing pipe 28 is disposed along the tangential direction of the side wall below the cylinder 27 and on the side wall of the coarse powder collecting chamber 7. Since the rectifying passages 32 partitioned in a lattice shape are formed in the blowing pipe 8, the blow-up air can be rectified and swirled into the coarse powder collecting chamber 7 to be blown. . The rectifying path 32 can be formed by inserting a plurality of pipes, and the blow-in pipe 28 can be a normal tubular one. Since the adjustment gate 33 is provided at the inlet of the blowing pipe 28, the blow-up rate (ratio of the blow-up air flow rate to the cyclone inlet air flow rate) can be easily adjusted by adjusting the blow-up air amount by opening and closing the adjustment gate 33. Can be changed.

  By blowing blow-up air from the blow pipe 28 arranged as described above, the blow-up air can be blown upward from the coarse powder outlet 8 at the lower end of the cyclone tower 5 through the upward flow passage 25. The fine powder that descends while turning in the cyclone tower 5 is reversed and raised, and the collection efficiency of the fine powder sucked into the fine powder collection duct 9 can be increased. In addition, since the downflow that transports the coarse powder by the blow-up air flowing into the cylinder 27 is sucked into the blow-up air, it is possible to improve the collection efficiency of the coarse powder by generating a smooth circulation flow. it can. By separating the downflow passage 25 and the upflow passage 26 in this manner, the generation of turbulence can be prevented, and the classification efficiency can be improved along with the classification accuracy.

  Since the central partition wall 24 and the inner guide 22 are attached to the support shafts 29 and 30, respectively, either one or both of the central partition wall 24 and the inner guide 22 are moved up and down by the support shafts 29 and 30. be able to. As a result, the widths of the downflow passage 26 and the upflow passage 25 can be adjusted as appropriate, so that the classification point can be easily adjusted in accordance with the particle size of the powder.

  FIG. 4 shows another type of cyclone classifier different from that described above. In this cyclonic classifier, a conical air rectifying guide 31 is provided on the bottom surface 22a of the inner guide 22 with its top facing downward. Support shafts 29 and 30 are attached to the top. By this air rectifying guide 31, blow-up air from below can be sorted without causing turbulent flow around the periphery of the bottom surface 22a of the inner guide 22.

In order to confirm the classification performance of the cyclonic classifier shown in FIGS. 1 and 2, the following tests were conducted.
Structure of the cyclone tower used Treatment air volume: 7.5m ³ / min
Cyclone trunk diameter: φ240mm
Cyclone straight tube length: 250mm
Cyclone taper length: 210mm
Coarse powder outlet diameter: φ96mm
Inner guide lower end diameter: φ125mm
Inner guide cone apex angle: 55 °
Particle size of powder discharge: Silicon carbide (particle size: median diameter 17 μm)
Powder supply rate: 250g / min
Powder blowing flow rate: 17m / min

In the cyclone classifier having the above-described configuration, the test was performed by changing the width of the upflow passage 25, the width of the downflow passage 26, and the blow-up rate, and the results as shown in Tables 1 to 3 and FIGS. Got. In Table 1, κ is a classification accuracy index (κ = D _p75 / D _p25 ), and the larger this value, the lower the classification accuracy. In the figure, H is the sum of the upflow passage 25 and the downflow passage 26 (hereinafter, the total passage width) h is the width of the downflow passage 26, and% is the blow-up rate.

  Table 1 shows the test results when the total passage width H is 20 mm and 40 mm. When the total passage width H is 20 mm, when the position of the central partition wall 24 is brought close to the conical inner guide 22 (in the direction in which h increases), a part of the blow-up air flow containing coarse powder enters the downflow passage 26. Although it flows, there is no reduction in classification accuracy even if the blow-up rate is small due to the effect of the central partition wall 24, and the 50% separation diameter is increased. Further, when the total passage width H is increased to 40 mm, the variable width of the 50% separation diameter is reduced even if the blow-up rate is increased. Therefore, when changing the 50% separation diameter over a wide range while preventing a reduction in classification accuracy, the gap: H between the outer guide 21 and the conical inner guide 22 is reduced, and the position of the central partition wall 24 and the blow-up rate are increased. The method of changing is effective.

  Table 2 shows the results of examining the variable width of the 50% separation diameter by changing the blow-up rate in order to see the effect of the central partition wall 24 with the total passage width H being 15 mm. In the absence of the central partition, the 50% separation diameter changes greatly with a slight change in blow-up rate, which is difficult to control in practice. On the other hand, due to the rectification effect by installing the central partition wall 24, the change of the 50% separation diameter is gradual with respect to the change of the blow-up rate, the control becomes easy, and the effect of the central partition wall 24 is recognized.

  Next, the effect of the air rectification guide 31 is shown in Table 3. The air rectifying guide 31 eliminates the collision of the blow-up air with the bottom surface 22a of the inner guide 22 and the sudden change in the flow direction when the air flows around the conical guide surface 23, and the air is straightened upward. Therefore, it was possible to increase the classification point while suppressing the degradation of the classification performance.

Further, a 50% separation diameter (D _p50 ) and classification accuracy are provided by providing a rectifying path 32 for rectifying blow-up air in the blow pipe 28 and an adjustment gate 33 for adjusting the amount of blow-up air at the inlet of the blow pipe 28. Table 4 shows the effect of improving (κ).

  As described above, according to the cyclone classifier according to the present invention, fine powder and coarse powder can be classified accurately and efficiently. In addition, since the classification point can be easily changed, it is not necessary to change the stage such as replacing the sieve screen for sieving. In addition, the cyclone classifier of the present invention has a great advantage that a powder with high added value can be obtained with a narrow particle size distribution width, and if this is used in an air blasting apparatus, the conventional blasting process can be used. The problem can be solved. In other words, in the conventional cyclone classifier, the injection material that has been crushed and made into fine powder after injection processing cannot be separated efficiently, so the particle size of the circulating injection material becomes gradually smaller, and the processing accuracy and processing efficiency are lowered and constant. There was a problem that the machining process could not be maintained. On the other hand, the cyclone classifier according to the present invention has the effect of accurately and efficiently classifying the fine powder side injection material that is crushed after the injection processing and becomes unnecessary and the reusable coarse powder side injection material. Therefore, the machining accuracy and machining efficiency are not lowered and a constant machining process can be maintained.

It is a schematic block diagram of the cyclone classifier of this invention. It is a principal part enlarged view of the cyclonic classifier of this invention. It is a bottom view which shows the inside of a coarse powder collection chamber. It is a principal part enlarged view which shows the cyclone classifier of a form different from the above. It is a graph which shows the effect of the position of the center partition on classification efficiency. It is a graph which shows the influence of blowup air when there is no central partition. It is a graph which shows the influence of blowup air in case there exists a center partition.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection material hopper 2 Injection material fixed supply apparatus 3 Compressed air supply source 4 Injection material dispersion nozzle 5 Cyclone tower 5a Straight cylinder part 5b Funnel-shaped taper part 6 Powder introduction part 7 Coarse powder collection chamber 8 Coarse powder discharge port 9 Fine powder Recovery duct 10 Dust collector 11 Fan 12 Fine powder transport pipe 20 Inner peripheral surface 21 Outer guide 22 Conical inner guide 22a Inner guide bottom surface 23 Conical guide surface 24 Central partition 25 Upflow passage 26 Downflow passage 27 Cylinder 28 Blow Up-air blowing pipes 29 and 30 Support shaft 31 Air rectification guide 32 Rectification path 33 Adjustment gate

Claims (5)

  The fine powder in the powder blown into the cyclone tower is blown up by blow-up air from the bottom of the cyclone tower and extracted from above, and the coarse powder is discharged from the coarse powder outlet at the bottom of the cyclone tower to the coarse powder collection chamber below it. In the cyclone classifier to be recovered, an outer guide having an inner peripheral surface that widens in a divergent shape is provided at the coarse powder outlet, and a conical inner guide is disposed below the outer guide with its top portion facing upward. The inner peripheral surface of the outer guide and the conical guide surface of the inner guide are opposed to each other, and an annular central partition wall is interposed between the inner peripheral surface and the conical guide surface. A cyclone characterized in that a downflow passage through which powder flows down from the cyclone tower to the coarse powder collection chamber and an upflow passage through which blow-up air flows from the coarse powder collection chamber into the cyclone tower are provided separately Type classification device. The cyclonic classifier according to claim 1, wherein a conical air rectifying guide is provided on the bottom surface of the conical inner guide with its top facing downward. An adjustment gate for arranging a blow-up air blowing pipe in the coarse powder collecting chamber, providing a rectification path in the blowing pipe along the air blowing direction, and adjusting the amount of blow-up air at the inlet of the blowing pipe The cyclonic classifier according to claim 1 or 2, wherein The cyclone classifier according to claim 1 or 2, wherein one or both of the central partition and the inner guide can be adjusted in the vertical direction. The cyclone classifier according to claim 1 or 2, wherein a cylinder for guiding blow-up air to the upward flow passage is connected to the lower end of the central partition wall.

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