JPH0716539A - Air classifier - Google Patents

Abstract

PURPOSE:To provide an air classifier capable of easily altering the number of rotations of a dispersing plate in matching relation to the aggregating properties of a powder to be classified. CONSTITUTION:This air classifier is constituted so that the rotary dispersing plate 6 dispersing the raw material W to be classified charged in a casing 1 and the rotary blade 7 forming revolving streams in the casing 1 are respectively rotated by separate rotary shafts 3, 4 and drive devices 10, 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air stream classifier, and more particularly to an air stream classifier capable of classifying the powder according to the agglomeration properties of the powder to be classified.

[0002]

2. Description of the Related Art Conventionally, pulverized powder or the like has been classified into coarse powder and fine powder in various industrial fields, and a method using an air stream classifier has been widely adopted as the classification method. ing.

Such an air stream classifier has, for example, the structure shown in FIG. 3, and the raw material to be classified W is charged from the raw material inlet 101, and the dispersed plate 10 which rotates the charged raw material to be classified W is introduced.
It is disentangled into primary particles by 2 and dropped into the classification chamber 103 while being scattered in the outer peripheral direction.

The raw material W dropped into the classification chamber 103 is
Classification is performed based on the balance between the centrifugal force due to the swirling flow formed in the casing 105 by the rotary blades 104 and the viscous force of the air flow that is swirling toward the center, and the coarse powder A has a higher centrifugal force than the internal force. While descending while turning in the cylinder 106,
It is discharged from the outlet 107 at the lower end. Further, the viscous force of the air flow prevails, and the fine powder B enters the duct 108 through the gap of the rotary blades 104 by riding on the air flow, and is collected by a collecting device (not shown).

Here, as is well known, the Stokes diameter D _pc of the separation limit particles of the coarse powder A and the fine powder B in the air stream classifier is expressed by the following equation.

[0006]

[Formula 1] Here, V _t is the peripheral speed of the rotor blade, μ is the viscosity of air, r is the radius of the rotor blade, V _r is the air velocity in the radial direction at the position of r, ρ
_p indicates the density of the powder to be classified.

The raw material W to be classified introduced into the air stream classifier is accurately classified into the coarse powder A and the fine powder B by the Stokes diameter (= D _pc ) of the separation limit particles represented by the above formula 1. In order to do so, it is a very important problem how the raw material W to be classified is dispersed in the classifying chamber 103 where the centrifugal force due to the swirling flow and the viscous force of the air flow act.

That is, if the raw material W to be classified is introduced into the classification chamber 103 in the state of being aggregated, the aggregated particles are
Even if the powder contains the powder having the particle diameter originally belonging to the fine powder B, it undergoes the classification operation as the coarse powder A in the classification chamber 103, and the coarse powder A after classification contains a large amount of the fine powder B. As a result, the classification accuracy of the airflow classifier is significantly reduced.

Therefore, in the air stream classifier, the function of the dispersion plate 102 for unraveling the raw material W to be classified into primary particles and introducing it into the classifying chamber 103 is very important. In the classifier, the rotary dispersion plate 102 and the rotary blades 104 that form a swirl flow in the casing 105 are fixed to a rotary shaft 110 that is rotated by the same drive motor 109.
The number of revolutions of the dispersion plate 102 cannot be independently changed according to the properties of the powder to be classified, particularly the agglomeration property, and the powder having a smaller particle size in recent years or the powder having the property of easily aggregating is used. It was not a device that could sufficiently meet the classification needs.

The present invention has been made in view of the problems of the above-mentioned prior art, and its object is to easily change the rotational speed of the dispersion plate according to the agglomeration property of the powder to be classified. It is to provide an airflow classifier that can.

[0011]

In order to achieve the above object, the present invention provides a rotary dispersion plate for dispersing a material to be classified put in a casing, and a rotary blade for forming a swirling flow in the casing. Were separately driven rotating bodies.

[0012]

According to the airflow classifier according to the present invention described above,
Since the rotary dispersion plate for dispersing the material to be classified and the rotating blades that affect the cut diameter of the material to be classified are driven separately, the property of the powder to be classified, for example, between particles like limestone particles When classifying powders that have strong adhesion and are prone to agglomeration, the rotation speed of the rotary dispersion plate can be increased independently to allow the agglomerated powders to be thoroughly disentangled before classification. On the contrary, in the case of classifying powder such as resin-based particles that easily causes agglomeration due to electrification, a state in which the rotational speed of the rotary blade that forms a swirling flow for classification in the casing is secured. It is also possible to classify powders of various different properties with high classification accuracy, since it is possible to perform classification while reducing the number of rotations of the rotary dispersion plate and suppressing charging of powders as much as possible. Becomes

[0013]

The present invention will be described in detail below with reference to examples of the present invention.

Here, FIG. 1 is a conceptual cross-sectional view showing an embodiment of an air classifier according to the present invention, in which 1 is a cylindrical casing and 2 is a casing 1. It is a stored hopper.

The ceiling portion 1a of the casing 1 is provided with a hollow shaft 3 rotatably penetrating the center of the ceiling portion 1a and a shaft 4 rotatably inserted in the hollow shaft 3. At the lower end of the hollow shaft 3, a disc-shaped dispersion plate 6 for dispersing the raw material W to be classified introduced from the chute 5 is fixed, and the lower end of the shaft 4 protruding below the lower end of the hollow shaft 3. A rotary blade 7 that forms a swirling flow in the casing 1 is fixed to the.

A pulley 8 is fixed to the upper end of the hollow shaft 3, and the endless belt 9 wound around the pulley 8 causes the rotation of the drive motor 10 to rotate.
And the dispersion plate 6 fixed to the lower end of the hollow shaft 3 is rotated. Further, a pulley 11 is fixed to the upper end of the shaft 4 which is present so as to project further upward from the upper end of the hollow shaft 3, and an endless belt 12 wound around the pulley 11 causes a drive motor different from the above. The rotation of 13 is transmitted to the shaft 4, and the shaft 4
The rotary blade 7 fixed to the rotor rotates.

Further, as shown in the drawing, a duct 15 communicating with the suction blower 14 is opened near the inner center of the rotary blade 6 forming a swirl flow in the casing 1, and the suction blower 14 is operated. , Forms a flow of air flowing into the duct 15 through the gap of the rotary blades 6 while swirling into the casing 1.

The airflow classifier according to the present invention constructed as described above is operated as follows.

First, based on the type of powder to be classified and the cut diameter of classification, the number of revolutions of the dispersion plate 6, the number of revolutions of the rotor blades 7 forming a swirling flow in the casing 1, and the suction blower 1
Each of the four rotation speeds is determined. At this time, since the airflow classifier according to the present invention is configured such that the dispersion plate 6 and the rotary vanes 7 are rotated by the independent shafts 3 and 4 and the drive devices 10 and 13 as described above. , The number of revolutions can be set to an optimum one according to the type of powder to be classified.

Next, the dispersion plate 6, the rotary blades 7, and the suction blower 14 are rotated at the determined respective rotation speeds, and when the air flow formed in the casing 1 is stabilized, the casing 5 is discharged from the chute 5. The raw material W to be classified is put into 1.

The raw material W to be classified is fed into the drive motor 1
The particles are efficiently disentangled into primary particles by the dispersion plate 6 rotating by 0, and fall into the classification chamber 16 where the centrifugal force and the viscous force of the air flow act while scattering in the outer peripheral direction.

The material W to be classified which has fallen into the classification chamber 16
Is classified based on the balance between the centrifugal force due to the swirling flow formed in the casing 1 by the action of the rotating blades 7 rotated by the drive motor 13 and the viscous force of the air flow toward the center while swirling by the action of the suction blower 14. Is done
The coarse powder A descends while swirling in the hopper 2 due to the above centrifugal force, and is discharged from the coarse powder outlet 17 at the lower side, while the fine powder B has a viscous force of the air flow and rides on the air flow. Through the gap between the rotary blades 7 into the duct 15 and is collected by a collecting device (not shown).

Using the apparatus having the above structure, with respect to limestone particles having a property that the adhesion between particles is strong and agglomeration easily occurs, the Stokes diameter of the separation limit particle of 3 μm,
A classification test was conducted. The result of the classification test is shown in FIG.
Shown as an omp curve.

The Tromp curve in FIG. 2A is
From the relationship between the Stokes diameter of the separation limit particles found from the above equation 1 and the rotor 7 and the suction blower 14, 3 μ
When the number of rotations of the rotary blade 7 and the suction blower 14 in which m is the Stokes diameter of the separation limit particles are calculated and the dispersion plate 6 is rotated at the same number of rotations as the rotary blade 7,
That is, it is a result when limestone particles are classified with a cut diameter of 3 μm, assuming a conventional airflow classifier that is rotated by the same drive means of the dispersion plate 6 and the rotary blade 7.

On the other hand, in the Tromp curve of FIG. 2B, the rotational speed of the dispersion plate 6 is the highest for the limestone particles as the material to be classified, regardless of the rotational speed of the rotary blade 7 calculated from the above equation 1. Set the number of revolutions to efficiently loosen the primary particles,
It is a result when limestone particles are classified with a cut diameter of 3 μm.

Tromps (a) and (b) shown in FIG.
From the curve, the dispersion plate 6 and the rotary blade 7 are driven separately, and the rotation speed of the dispersion plate 6 is set to the rotation speed at which the classified raw material is most efficiently disentangled into primary particles. It is found that the classification accuracy is dramatically improved when the classification is performed.

The embodiment of the present invention has been described above. However, the present invention is not limited to the above-mentioned embodiment,
Various modifications and changes can be made based on the technical idea of the present invention.

In particular, the structure of the airflow classifier described in the above embodiments is merely an example, and the present invention is applicable to all the airflow classifiers having both the rotary dispersion plate and the rotary blades. The idea, that is, the rotary dispersion plate and the rotary blade are separately driven, is included in the present invention.

[0029]

As described above, according to the air stream classifier according to the present invention, the rotational speed of the rotary dispersion plate can be arbitrarily changed according to the property of the powder to be classified, and thus various powders having different properties can be obtained. The device can classify the body with high accuracy.

[Brief description of drawings]

FIG. 1 is a conceptual vertical cross-sectional view showing an embodiment of an airflow classifier according to the present invention.

FIG. 2 is a diagram showing a Tromp curve.

FIG. 3 is a conceptual vertical cross-sectional view showing an example of an airflow classifier that has been conventionally used.

[Explanation of symbols]

 1 Casing 2 Hopper 3 Hollow shaft 4 Shaft 5 Chute 6 Dispersion plate 7 Rotor blade 8 Pulley 9 Endless belt 10 Drive motor 11 Pulley 12 Endless belt 13 Drive motor 14 Suction blower 15 Duct 16 Classification chamber 17 Coarse powder outlet

Claims (1)

[Claims] 1. An air flow characterized in that a rotary dispersion plate for dispersing the classified raw material charged in a casing and a rotary blade for forming a swirling flow in the casing are driven separately. Classifier.