JPH0810706A - Pneumatic sorter - Google Patents

Abstract

PURPOSE:To provide a pneumatic sorter having the structure capable of preventing a particle from being entrained by the air flowing in from a labyrinthic sealing part. CONSTITUTION:A raw material to be sorted charged into a casing from the upper part is revolved by the centrifugal force resulting from turning air current formed in the casing by a cage rotor and the suction force of a blower and sorted into the coarse powder and fine powder by the balance with the resistance force of an air current flowing into the duct set around the center of the cage rotor. In this pneumatic sorter, the duct 10 to be set around the center of the cage rotor 6 is set on the lower face side of the rotor 6 through a labyrinthic seal 11, and an annular portrusion 12 is formed on the lower face of the rotor 6 to surround the outer periphery of the seal 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air flow classifier, and more particularly to air directed toward the center of a cage type rotor while being swirled by a centrifugal force generated by a swirling air flow formed in a casing by a cage type rotor and a suction force of a blower. The present invention relates to an airflow classifier having a structure in which classification is performed based on the balance with the flow resistance.

[0002]

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

Such an air stream classifier has, for example, the structure shown in FIG. 3, and is an upper surface of a cage type rotor 102 for feeding a classified raw material W from a raw material feeding port 101 and rotating the introduced classified raw material W. Dispersed by 102a into primary particles,
It is dropped in the lower classification part 103 while being scattered in the outer peripheral direction.

The raw material W dropped into the classifying section 103 is
From the balance between the centrifugal force due to the swirling airflow formed in the casing 104 by the cage type rotor 102 and the resistance force of the air flow toward the center of the cage type rotor 102 while swirling by the suction force of a suction blower (not shown). As a result of the classification, the above-mentioned centrifugal force causes the coarse powder A to collide with the inner wall surface of the casing 104, after which it falls freely and is discharged from the coarse powder discharge port 105 at the lower end. Further, the fine powder B is
The resistance of the air flow is superior, the air flow rides on the air flow, passes between the blades of the cage rotor 102, enters the duct 106, and is collected by a collecting device (not shown).

In the airflow classifier, the cage rotor 102 is rotated by a drive motor (not shown), and the exhaust duct 106 for the fine powder B is installed near the center of the cage rotor 102. Between,
Since there is a connecting portion between the rotating member 102 and the stationary member 106, a labyrinth seal 107 is generally applied to this portion in order to secure the sealing property of the connecting portion.

The structure of the labyrinth seal 107 is as follows.
As is well known, there is a seal structure for forming a curved passage between a rotary member and a stationary member to reduce gas inflow or conversely gas leakage. With this seal structure, the rotary member and the stationary member are completely separated. It is very difficult to secure the sealing property of the connecting portion due to problems such as processing accuracy and processing cost. Usually, in the airflow classifier described above, in the air volume in the duct 106 sucked by the suction blower, 0.
The inflowing air X from the labyrinth seal 107 is present at about 5 to 3.0%.

The inflowing air X from the labyrinth seal 107 part into the duct 106 is used in an apparatus in which the labyrinth seal 107 part exists near the raw material inlet 101 like the conventional air flow classifier shown in FIG. Means that part of the unclassified raw material W fed from the raw material feeding port 101 is entrained by the inflow air X from the labyrinth seal 107 and flows into the discharge duct 106 of the fine powder B after the classification. Therefore, a large amount of coarse particles in the raw material W, which is originally separated as coarse powder A in the classifying unit 103, also enters the fine powder B to be the product, and the classification accuracy as an air stream classifier and the reliability as a classifier are high. It was a factor that significantly deteriorated the sex.

Conventionally, in order to prevent particles from being entrained by the inflowing air from the labyrinth seal portion,
Blow compressed air into the labyrinth seal portion, or open the labyrinth seal portion to the atmosphere,
By changing the route of the inflowing air from the labyrinth seal portion into the duct 106, the classified raw material W before classification is
Although a device with a structure that does not entrap is proposed and partially put into practical use, such a device requires elaborate machining of the labyrinth seal part and is also used in a device that blows compressed air. Had a problem that the operating cost was further increased.

The present invention has been made in view of the inconvenience caused by the inflowing air from the labyrinth seal portion which is difficult to be eradicated in the above-mentioned air stream classifier, and its purpose is to change the structure of the labyrinth seal portion itself. It is another object of the present invention to provide at low cost an air flow classifier having a structure capable of preventing particles from being entrained by inflowing air from the labyrinth seal portion.

[0010]

In order to achieve the above-mentioned object, the present invention provides a centrifugal force generated by a swirling air flow formed in a casing by a cage type rotor for a material to be classified introduced from above into the casing. And an air flow classifier having a structure for classifying coarse powder and fine powder from the balance with the resistance of the air flow toward the duct installed near the center of the cage-type rotor while swirling by the suction force of the blower, A duct installed near the center of the cage type rotor is installed on the lower surface side of the cage type rotor via a labyrinth seal, and in a state of enclosing the outer periphery of the labyrinth seal, an annular protrusion is provided on the lower surface side of the cage type rotor. The formed air flow classifier was used.

[0011]

According to the airflow classifier according to the present invention described above,
First, because the duct installed near the center of the cage type rotor, which is the outlet for fine powder, is installed on the lower surface side of the cage type rotor via the labyrinth seal, contrary to the conventional air flow classifier, The material to be classified put into the casing has a structure in which it is not caught in the inflowing air in the labyrinth seal portion. Further, in the airflow classifier according to the present invention, in a state of enclosing the outer periphery of the labyrinth seal portion existing on the lower surface side of the cage type rotor, since it has a structure in which an annular projection is formed on the lower surface side of the cage type rotor, Coarse powder after classification is also prevented from approaching the labyrinth seal area by the annular projection,
After all, the structure is such that it is not caught by the inflowing air in the labyrinth seal portion.

[0012]

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

FIG. 1 is a conceptual cross-sectional view showing an embodiment of an air classifier according to the present invention. In the figure, 1 is a casing whose lower part is squeezed into a cone shape, and 2 is the casing. Air inlets 3 formed on the side wall of 1 are coarse powder outlets formed on the lower end of the casing 1.

The top plate 1a of the casing 1 is provided with a raw material inlet 4, and a shaft 5 rotatably penetrating through the center of the top plate 1a is provided. The cage rotor 6 is fixed to the lower end at the center of the upper surface side.

Further, a drive motor 7 is attached to the upper end of the shaft 5, and by rotating the drive motor 7, the cage rotor 6 fixed to the lower end of the shaft 5 is rotated and the inside of the casing 1 is rotated. It creates a swirling air flow.

A hole 8 formed near the center of the lower surface side of the cage type rotor 6 which forms a swirling airflow in the casing 1.
As shown, a duct 10 communicating with the suction blower 9 is installed via a labyrinth seal 11, and the casing 1 is operated by operating the suction blower 9.
It forms a flow of air flowing into the duct 10 through the blades of the cage rotor 6 while swirling inward.

Further, on the lower surface side near the outermost periphery of the cage type rotor 6, an annular projection 12 is formed so as to surround the labyrinth seal 11 part.

The air stream classifier according to the present invention constructed as described above is operated as follows to classify the raw material W to be classified into coarse powder A and fine powder B.

First, based on the type of powder to be classified and the cut diameter of the classification, the number of revolutions of the cage rotor 6 which forms a swirling airflow in the casing 1 and the blades of the cage rotor 6 while swirling. The rotational speed of the suction blower 9 that forms the flow of air flowing into the duct 10 is determined.

Next, the cage rotor 6 and the suction blower 9 are rotated at each of the determined rotational speeds, and when the air flow formed in the casing 1 becomes stable, the casing 1 is fed from the raw material inlet 4 to the casing 1. The raw material W to be classified is charged therein.

The raw material W to be classified is fed into the drive motor 7.
The primary particles are unraveled by the upper surface side of the cage type rotor 6 which rotates by the above, and fall into the classifying portion 13 on which the centrifugal force and the resistance force of the air flow act while scattering in the outer peripheral direction. At this time, in the airflow classifier according to the present invention,
As described above, since the labyrinth seal 11 part is present on the lower surface side of the cage type rotor 6, the classified material W introduced into the inflow air in the labyrinth seal 11 part is not caught, All of the classified raw material W falls into the classifying unit 13.

The material W to be classified, which has fallen into the classifying section 13,
Is the centrifugal force due to the swirling air flow formed in the casing 1 by the action of the cage rotor 6 rotated by the drive motor 7 as in the conventional air flow classifier, and the suction blower 9
Classification is performed from the balance with the resistance of the air flow toward the center of the cage rotor 6 while turning by the action of
The coarse powder A collides with the inner wall surface side of the casing 1 due to the centrifugal force, then falls freely and is discharged from the lower coarse powder discharge port 3, and the fine powder B has an excellent resistance to the air flow. It rides on the air flow, passes between the blades of the cage rotor 6, enters the duct 10, and is collected by a collecting device (not shown).

In this case, since the air flow classifier according to the present invention has a structure in which the labyrinth seal 11 part is present on the lower surface side of the cage rotor 6, the labyrinth seal 11 part of the coarse powder A after classification is used. Although there is a concern that it will be caught in the airflow classifier, the airflow classifier according to the present invention has a structure in which an annular projection 12 is formed on the lower surface side near the outermost periphery of the cage rotor 6 while further surrounding the labyrinth seal 11 part. Therefore, due to the existence of the annular projection 12,
The coarse powder A is prevented from approaching the labyrinth seal 11 part,
The coarse powder A is discharged from the coarse powder discharge port 3 at the lower end without being caught in the inflowing air in the labyrinth seal 11 part.

The operation of the annular projection 12 will be theoretically described with reference to FIG. 2. The classified coarse powder A receives the centrifugal force of the swirling airflow and collides with the inner wall surface of the casing 1 and then falls freely. In the drawing, the route shown by the solid line is taken to discharge from the coarse powder discharge port 3 at the lower end. On the other hand, the inflowing air X in the labyrinth seal 11 part is
In the space 14 defined by the duct 2 and the duct 10, the labyrinth seal 1 becomes an updraft as shown by a chain line in the figure.
It flows into part 1.

Here, in order for the coarse powder A to be caught in the inflowing air X in the labyrinth seal 11 part, the coarse powder A is required.
First, since the annular projection 12 first blocks the horizontal approach to the labyrinth seal 11 part, the vertical flow must approach the labyrinth seal 11 part by riding on the rising airflow of the inflowing air X. However, the flow velocity of this ascending air flow takes the cross-sectional area of the space 14 defined by the annular projection 12 and the duct 10 as wide as possible (that is, the annular projection 12 is formed near the outermost periphery of the cage rotor 6). Therefore, the flow velocity of the ascending air current is not so high as to actually transport the coarse powder A upward by overcoming its gravity settling,
The coarse powder A cannot approach the labyrinth seal 11 part even in the vertical direction, and the coarse powder A is not caught in the inflow air X in the labyrinth seal 11 part.

When the above is applied to the air classifier which is generally used for cement classification in the cement industry, the wind speed in the duct 10 is about 16 m / s.
At about ec, the amount of inflowing air X in the labyrinth seal 11 is about 1% of the air volume in the duct 10. Here, for example, the cross-sectional area of the duct 10 and the annular projection 12
When the cross-sectional area of the space 14 defined by and the duct 10 is the same, the flow velocity of the ascending air current in the space 14 due to the inflowing air X is about 0.16 m / sec. The maximum diameter of particles that can reach the labyrinth seal 11 part by riding an ascending air current is about 40 μm, and the labyrinth seal 11 of coarse particles (that is, particles of 150 μm or more) that must be reliably excluded from the product as coarse powder A. Mixing from the part is impossible in the airflow classifier having the structure according to the present invention.

As a result, the air stream classifier according to the present invention can prevent the raw material W to be classified from being entrained by the inflowing air X from the labyrinth seal 11 part which is difficult to eradicate, or the entrainment of the coarse powder A after the classification, and the air stream classification. The raw material W to be classified can be classified into the coarse powder A and the fine powder B by the original classification performance of the machine.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment,
It goes without saying that various modifications and changes can be made based on the technical idea of the present invention.

[0029]

As described above, according to the airflow classifier according to the present invention described above, it is possible to prevent the particles from being entrained by the inflowing air from the labyrinth seal portion and to provide the airflow classifier having a high classification accuracy with any special mechanism. There is an effect that it can be provided at the same cost as the conventional one without the need of.

[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 vertical cross-sectional view of a conceptual airflow classifier for explaining the operation of the airflow classifier according to the present invention.

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 Air inlet 3 Coarse powder outlet 4 Raw material inlet 5 Shaft 6 Cage type rotor 7 Drive motor 8 Hole formed in the lower side of the cage type rotor 9 Suction blower 10 Duct 11 Labyrinth seal 12 Annular protrusion 13 Classification section 14 Space defined by annular protrusion and duct W Classified raw material A Coarse powder B Fine powder X Labyrinth seal air inflow

Claims (2)

[Claims] 1. The cage-shaped rotor is swirled by a centrifugal force generated by a swirling air flow formed in the casing by a cage-type rotor and the suction force of a blower, and the vicinity of the center of the cage-type rotor is fed into the casing from above. In the airflow classifier having a structure for classifying coarse powder and fine powder from the balance with the resistance force of the air flow toward the duct installed in the duct, the duct installed near the center of the cage rotor is a cage rotor. An air flow classifier, which is installed on the lower surface side of the cage via a labyrinth seal, and has an annular projection formed on the lower surface side of the cage rotor while enclosing the outer periphery of the labyrinth seal. 2. The cage-shaped rotor is formed on the lower surface side near the outermost periphery of the cage-shaped rotor,
The airflow classifier according to claim 1.