JP2018192424A - Classifier - Google Patents

Abstract

To provide a classifier allowing for reduction in cost of seal air and easily providing even powder of a smaller particle diameter, while maintaining classification accuracy of the powder.SOLUTION: The classifier comprises a classification rotor 4 for classifying powder, a discharge pipe 7 for taking out the powder classified by the classification rotor 4 to the outside and seal air supply means 11 for supplying seal air A to a clearance between the classification rotor 4 and the discharge pipe 7. A seal air outflow part 13 for causing the seal air A to flow out to the inside of the classification rotor 4 is formed along the outer periphery of an end part on the discharge flow passage inlet 10-side in the discharge pipe 7, and a value of a diameter D of the seal air outflow part 13/an inner diameter R of the classification rotor 4×100% is 75% or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for classifying powder.

  As a conventional classifier, what is described in the following patent documents 1 and 2 is known, for example. The classifiers described in these patent documents supply coarse air to a gap between a classification rotor for classifying powder and a discharge pipe for taking out the classified powder to the outside. It is comprised so that it may prevent flowing into the inside of a discharge pipe from the crevice.

Japanese Patent No. 4601555 Japanese Patent No. 4225705

In the conventional classifier described above, it is necessary to supply a predetermined amount of seal air in order to improve the powder classification accuracy, and there is room for improvement in terms of reducing utility costs for operating a seal air supply device such as an air compressor. There is. In addition, if the amount of seal air supplied is increased in order to prevent mixing of coarse particles, the particle size of the powder obtained by classification tends to increase, and it is not so much when trying to obtain a powder with a smaller particle size. May not be suitable. Further, when a larger amount of seal air is supplied, the total air volume increases, and it is necessary to increase the size of the dust collector and blower for collecting the classified fine powder, which increases the equipment cost.
Accordingly, an object of the present invention is to provide a classifier that can reduce the cost associated with seal air while maintaining the accuracy of classification of powder, and can easily obtain powder with a smaller particle diameter. .

  The classifier of the present invention has a classification rotor for classifying powder, a discharge pipe for taking out the powder classified by the classification rotor, and a gap between the classification rotor and the discharge pipe. A seal air supply means for supplying seal air, wherein a seal air outflow portion for allowing the seal air to flow out into the classification rotor is formed along an outer periphery of an end portion of the discharge pipe on the discharge channel inlet side; The value of the diameter of the outflow portion / the inner diameter of the classification rotor × 100% is 75% or more.

  A further characteristic configuration of the classifier of the present invention is that the value of the diameter of the seal air outflow portion / the inner diameter of the classifying rotor × 100% is 90% to 95%.

  A further characteristic configuration of the classifier of the present invention is that the value of (diameter of the seal air outflow portion−diameter of the discharge channel inlet) / inner diameter of the classification rotor × 100% is 15% or more.

  A further characteristic configuration of the classifier according to the present invention is that the value of (diameter of the sealing air outflow portion−diameter of the discharge passage inlet) / inner diameter of the classification rotor × 100% is 20% to 50%. is there.

According to the present invention, the seal air outflow portion is provided at a position outside the conventional classifier in the radial direction of the classifying rotor. As a result, even if coarse particles flow into the classification rotor from the gap between the classification rotor and the discharge pipe, they are easily discharged to the outside of the classification rotor again. Therefore, according to the present invention, it is possible to reduce the supply amount of seal air while maintaining the classification accuracy. Therefore, not only can the utility cost for operating the seal air supply device such as an air compressor be reduced and the size of the device such as the air compressor can be reduced, but also the equipment cost of the dust collector and blower after the classifier. This makes it possible to reduce the cost and the size of the apparatus. Furthermore, it becomes easier to obtain a powder having a smaller particle diameter as the supply amount of the seal air decreases.

It is sectional drawing which shows schematic structure of the classifier which concerns on this invention. It is sectional drawing which shows the principal part of the classifier which concerns on this invention. It is sectional drawing which shows the principal part of the conventional classifier (comparative example 1). It is sectional drawing which shows the principal part of the conventional classifier (comparative example 2). It is a graph which shows the relationship between sealing air supply amount and the coarse particle mixing amount. It is a graph which shows the particle diameter distribution of the powder classified by the conventional classifier (comparative example 1) (sealing air supply amount: 0.93 Nm < ³ > / min). It is a graph which shows the particle diameter distribution of the powder classified by the conventional classifier (comparative example 1) (sealing air supply amount: 0.74Nm < ³ > / min). It is a graph which shows the particle size distribution of the powder classified by the conventional classifier (comparative example 1) (sealing air supply amount: 0.65Nm < ³ > / min). It is a graph which shows the particle diameter distribution of the powder classified by the conventional classifier (comparative example 2) (sealing air supply amount: 0.93 Nm < ³ > / min). It is a graph which shows the particle diameter distribution of the powder classified by the conventional classifier (comparative example 2) (sealing air supply amount: 0.56Nm < ³ > / min). It is a graph which shows the particle diameter distribution of the powder classified by the conventional classifier (comparative example 2) (sealing air supply amount: 0.46Nm < ³ > / min). It is a graph which shows the particle size distribution of the powder classified by the classifier (Example) which concerns on this invention (seal air supply amount: 0.56Nm < ³ > / min). It is a graph which shows the particle size distribution of the powder classified by the classifier (Example) which concerns on this invention (sealing air supply amount: 0.28Nm < ³ > / min). It is a graph which shows the particle diameter distribution of the powder classified by the classifier (Example) which concerns on this invention (sealing air supply amount: 0.09Nm < ³ > / min).

[Embodiment]
Embodiments of the present invention will be described below.
(Classifier)
As shown in FIG. 1, the classifier 1 includes an apparatus main body 2, a classification rotor 4, a rotation drive unit 6, a discharge pipe 7, a seal air supply unit 11, and a suction unit (not shown).

  A classification rotor 4 is provided inside the apparatus main body 2. The classifying rotor 4 is formed with an opening 16 on one side in the direction of the rotation axis X, and a rotation driving means 6 is connected to the other side in the direction of the rotation axis X. One end of the discharge pipe 7 is connected to the opening 16 of the classification rotor 4, and suction means (not shown) is provided on the other end side of the discharge pipe 7.

  For example, a general blower may be used as the suction means. In this case, it is desirable that the suction force can be freely changed. For example, by changing the rotation speed of the suction fan, the flow rate of air during suction can be changed as appropriate.

(Device body)
The apparatus main body 2 constitutes the outermost part of the classifier 1, and the inside thereof is a processing chamber 3 for classifying powder. The powder to be classified is input from a powder input unit (not shown) provided in the apparatus main body 2.

(Classification rotor)
The classification rotor 4 has a plurality of blades 5 and is provided in the processing chamber 3 so as to be capable of high-speed rotation around the rotation axis X. In the present embodiment, a so-called horizontal classification rotor that rotates around a rotation axis X in the horizontal direction is shown. The classification rotor 4 is rotated at a high speed by a rotation driving means 6 provided outside the processing chamber 3, thereby classifying the powder. As the rotation driving means 6, for example, a known drive motor may be used, and it is desirable that the rotation speed is appropriately changeable.

(Discharge pipe)
The inside of the discharge pipe 7 is configured as a discharge flow path 8 for taking out the powder classified by the classification rotor 4 to the outside. Further, a narrowed portion 9 is formed at the end of the discharge pipe 7 on the classifying rotor 4 side. The discharge pipe 7 includes a jacket 11 on the outer periphery thereof.

  The throttle portion 9 is provided in a state of entering the inside of the classifying rotor 4 from the opening 16 of the classifying rotor 4. ing. In the present embodiment, the discharge channel inlet 10 into which the classified powder flows is constituted by the tip portion of the throttle portion 9 having the smallest inner diameter.

(Sealing air supply means)
The seal air supply means includes a jacket 11 and a known air supply source (not shown). An air supply path 12 is formed inside the jacket 11, and seal air (air) from an air supply source is supplied to the gap S between the classification rotor 4 and the discharge pipe 7 through the air supply path 12. The As a result, the gap S is sealed, and coarse particles are prevented from being mixed. As an air supply source, for example, a known air compressor may be used, but the air may be naturally sucked without using a compressor or the like.

(Classification process)
When the raw material powder is charged into the processing chamber 3 of the apparatus main body 2 from the powder charging unit, it is classified by the classification rotor 4 that rotates at high speed, and powder having a predetermined particle diameter or less is taken out from the discharge pipe 7 ( (See the white arrow in FIG. 1). Specifically, by driving the suction means, the air inside the classification rotor 4 is sucked, so that the air inside the processing chamber 3 passes between the blades 5 of the classification rotor 4 that rotates at high speed. It is drawn into the classification rotor 4. At this time, powder having a predetermined particle diameter or less is taken into the classification rotor 4, but coarse particles having an excessive particle diameter are prevented from flowing into the classification rotor 4 by the rotating blades 5. Thereafter, the powder classified by the classification rotor 4 flows into the discharge flow path 8 from the discharge flow path inlet 10 and is guided to a collecting means such as a back filter, for example, and taken out as a product.

(Seal configuration)
Opposing surfaces 14 and 15 that are annular surfaces are formed on the end portion of the jacket 11 of the discharge pipe 7 and the end portion of the classifying rotor 4, respectively. The opposing surfaces 14 and 15 are arranged close to each other while maintaining a predetermined gap S. A seal air outflow portion 13 that blows out the seal air A is provided at the end of the facing surface 14 of the jacket 11 (end on the radially inner side of the jacket 11). The seal air outflow portion 13 is formed in an annular shape along the outer periphery of the end portion of the discharge pipe 7 on the discharge channel inlet 10 side.

  As shown in FIG. 2, the seal air A that has flowed from the air supply source through the air supply path 12 is divided into the gap S between the facing surfaces 14 and 15 and the seal air outflow portion 13. Seal air A that flows into the gap S between the opposed surfaces 14 and 15 flows out into the processing chamber 3, and the seal air A that flows into the seal air outflow portion 13 flows out into the classification rotor 4. As a result, the gap S is sealed, so that coarse particles are prevented from being mixed.

(Relationship between seal air outflow position and seal performance)
Unlike the conventional classifier 1, the classifier 1 according to the present invention is characterized in that a seal air outflow portion 13 is provided at an outer position in the radial direction of the classifying rotor 4. By providing this feature, it is possible to reduce the cost of sealing air while maintaining the powder classification accuracy, and it is easy to obtain powder with a smaller particle diameter.

  Specifically, as shown in FIGS. 1 and 2, the diameter D of the seal air outflow portion 13 / the value of the inner diameter R × 100% of the classification rotor 4 is 75% or more, more preferably 90% to 95%. The seal air outflow part 13 is provided in the position. Further, in this case, the value of (diameter D of the seal air outflow portion 13−diameter d of the discharge passage inlet 10) / inner diameter R × 100% of the classification rotor 4 is 15% or more, more preferably 20% to 50%. It is still better to configure as follows. Note that the inner diameter R of the classification rotor 4 in the present embodiment refers to the distance between the inner surfaces of the blades 5 in the classification rotor 4.

[Other Embodiments]
1. In the above-described embodiment, the example applied to the so-called horizontal classifying rotor 4 rotating around the rotation axis X in the horizontal direction is shown, but the present invention is not limited to this, and other than this, The present invention may also be applied to a classification rotor that rotates around the rotation axis in the direction.
2. The classifier according to the present invention can be applied to a small machine or a large machine regardless of its size.
3. The classifier according to the present invention can be applied to a pulverizer, a dryer, a particle design apparatus, and the like.

(Examination of position of seal air outflow part)
As shown in Table 1 below, in FIG. 2, the diameter D of the sealing air outflow portion / the value of the inner diameter R × 100% of the classification rotor, and (the diameter D of the sealing air outflow portion−the diameter d of the discharge channel inlet) / Test machines with various values of the inner diameter R × 100% of the classification rotor were prepared, and the sealing performances were compared.

  The test was performed using a fluidized bed type opposed jet mill (manufactured by Hosokawa Micron Co., Ltd.) with a different classification section as a tester. As the raw material powder, talc (average particle diameter D50 = 20 μm) was used, and the rotation speed of the classification rotor was 10500 rpm. The seal performance was evaluated by reducing the amount of seal air supplied stepwise and comparing the mixing rate of coarse particles contained in the classified product. The powder supply amount was about 3 kg per condition for the seal air supply amount, and the test time was 2 hours per condition for the seal air supply amount.

  As shown in Table 1, if the value of D / R × 100 is about 80% or more and the value of (D−d) / R × 100% is 15% or more, the sealing performance is maintained and the product is maintained. It was confirmed that mixing of coarse particles was prevented. In particular, if the value of D / R × 100 is 90% to 95% and the value of (D−d) / R × 100% is 20% to 50%, very high sealing performance is exhibited. Was also confirmed. In addition, when the value of d became too small, the pressure loss of the classifying rotor was increased, and the sealing performance tended to be lowered.

(Classification performance comparison test)
Next, the classification performance of the classifier (Example) of the present invention and the conventional classifier (Comparative Example 1 and Comparative Example 2) were measured and compared.

  As a classifier, a test was performed using a fluidized bed type opposed jet mill (manufactured by Hosokawa Micron Co., Ltd.) with a different classification part. As the raw material powder, talc (average particle diameter D50 = 20 μm) was used, and the rotation speed of the classification rotor was 10500 rpm. The amount of seal air supplied was reduced stepwise, and the mixing ratio of coarse particles contained in the products after classification was compared. The powder supply amount was about 3 kg per condition for the seal air supply amount, and the test time was 2 hours per condition for the seal air supply amount.

  The classifier (Example) of the present invention used in this comparative test is the tester No. 1 in Table 1 above. 1 and the value of D / R × 100 was 93.3%, and the value of (D−d) / R × 100% was 45.6%.

  FIG. 3 shows the main part of the comparative example 1. In this classifier, the seal air outflow part 13 opens toward the discharge flow path 8 of the discharge pipe. Therefore, the seal air A that has flowed from the air supply source through the air supply path 12 is configured to flow separately into the processing chamber 3 and the discharge flow path 8.

FIG. 4 shows the main part of Comparative Example 2. In this classifier, the seal air outflow part 13 is located at a position inside the classifier according to the present invention in the radial direction of the classifying rotor 4. Is provided. Specifically, the classifier of this comparative example 2 is the test machine No. 8. The value of D / R × 100 is 54%, and the value of (D−d) / R × 100% is 6.3%
Met. In the classifier of this comparative example 2, as in the classifier of the present invention, the seal air A that has flowed from the air supply source through the air supply path 12 is introduced into the processing chamber 3 and the classifying rotor 4. It is configured to flow separately.

  The classification performances of Comparative Example 1, Comparative Example 2, and Examples are shown in Tables 2 to 4 below. The particle size D50 in the table means the product particle size after classification when the particle size distribution is accumulated from the fine side and becomes 50%. The particle size D97 means the particle size distribution on the fine side. It means the product particle size after classification when it becomes 97% when accumulated from the above. Moreover, the value of D97 / D50 indicates the mixing rate of coarse particles contained in the product after classification, and the closer this value is to 1, the less coarse particles are mixed and the higher the classification performance. .

  As shown in Table 2 and FIG. 5, in the classifier of Comparative Example 1, as the amount of seal air supplied was decreased, the amount of coarse particles mixed up significantly increased. Further, as shown in FIGS. 6 to 8, in the classifier of Comparative Example 1, when the seal air supply amount is decreased, the peak shape indicating the particle size distribution of the powder becomes broad, and the classification accuracy is improved. It was greatly reduced.

  As shown in Table 3 and FIG. 5, in the classifier of Comparative Example 2, when the seal air supply amount is decreased, the amount of coarse particles mixed is also increased, although not as much as that of the classifier of Comparative Example 1. It was. Further, as shown in FIGS. 9 to 11, in the classifier of Comparative Example 2, when the seal air supply amount is decreased, the peak shape indicating the particle size distribution of the powder is the same as that of the classifier of Comparative Example 1. Although it was not, it was still broad and classification accuracy was reduced.

  On the other hand, as shown in Table 4 and FIG. 5, in the classifier (Example) according to the present invention, even if the seal air supply amount was decreased, there was hardly any increase in the particle mixing amount. Further, as shown in FIGS. 12 to 14, in the classifier (example) according to the present invention, the peak shape indicating the particle size distribution of the powder is in a broad state even when the seal air supply amount is decreased. The classification accuracy was maintained.

  The present invention can be suitably used in the technical field of classifying powder.

DESCRIPTION OF SYMBOLS 1 Classifier 2 Apparatus main body 3 Processing chamber 4 Classification rotor 5 Blade 6 Rotation drive means 7 Discharge pipe 8 Discharge flow path 9 Restriction part 10 Discharge flow path inlet 11 Jacket (seal air supply means)
12 Air supply path 13 Seal air outflow portions 14 and 15 Opposing surface 16 Opening portion A Seal air X Rotating shaft center S Clearance

Claims (4)

A classification rotor for classifying powder, a discharge pipe for taking out the powder classified by the classification rotor to the outside, and a seal air supply means for supplying seal air to a gap between the classification rotor and the discharge pipe,
A seal air outflow portion for allowing seal air to flow out into the classification rotor is formed along an outer periphery of an end of the discharge pipe on the discharge channel inlet side;
A classifier having a value of diameter of the seal air outflow portion / inner diameter of the classification rotor × 100% is 75% or more.   2. The classifier according to claim 1, wherein a value of diameter of the seal air outflow portion / inner diameter of the classification rotor × 100% is 90% to 95%.   3. The classifier according to claim 1, wherein a value of (diameter of the seal air outflow portion−diameter of the discharge channel inlet) / inner diameter of the classification rotor × 100% is 15% or more.   4. The classifier according to claim 3, wherein a value of (diameter of the seal air outflow portion−diameter of the discharge passage inlet) / inner diameter of the classification rotor × 100% is 20% to 50%.

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