JPH0615072B2 - Leakage prevention device for classification device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing a part of coarse powder from leaking into a fine powder discharge duct of a classification device for separating a classification raw material into fine powder and coarse powder. .

Conventional technology A rotating classification impeller and a fixed guide vane on the outside of the machine body, or casing, are installed to separate the introduced classification raw material into coarse powder and fine powder, and the fine powder flows into the classification impeller together with the air flow. A classifying device that allows the particles to pass through and be collected outside the machine is widely known.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in such a conventional classifying device, a gap is formed in the boundary portion between the rotating rotary classification impeller and the fine powder discharge duct on the end surface of the fixed casing, and the fine powder is discharged from this gap. There is a phenomenon that coarse powder leaks into the duct.

Therefore, in order to prevent the coarse powder from leaking from the clearance at the boundary between the rotary classification impeller and the fine powder discharge duct, a labyrinth structure or a mechanical seal is conventionally provided in the clearance at the boundary. Alternatively, a means such as blowing a sealing gas is adopted. However, none of the means can completely prevent the leakage, and there are problems such as insufficient results.

That is, in the labyrinth structure, the airflow caused by the pressure difference between the inside and outside of the labyrinth is repeatedly expanded and compressed by the maze structure so as to attenuate the pressure, but it is not a perfect seal structure, but in the case of a gas mixture. There is a problem that powder may accumulate in the labyrinth and cause seizure, and in mechanical seals, the sliding part where the rotating side and the fixed side are in contact and slide easily wears out, especially with a vapor mixture. If the particles are trapped, they will be greatly damaged, and the structure will be complicated and expensive. Further, when the seal gas is blown, high-pressure gas is blown into the boundary portion of the fine powder and coarse powder, and in order to prevent the leak air flow by this flow, the coarse powder may be pushed into the fine powder duct depending on the blowing position of the seal gas. However, there is a drawback that the performance and cost are greatly affected by the excess and deficiency of the injection amount.

Therefore, in order to solve such a problem in the prior art, the present invention is designed to prevent the coarse particles from leaking together with the airflow from the boundary portion between the fine powder discharge duct and the rotating rotary classification impeller. A rotary seal member is provided on the upper plate of the classification impeller, and the upper portion of the rotary seal member is projected outward from the opening of the casing top plate to prevent the powder from leaking from the outer side in the radial direction to the fine powder discharge duct side. It is an object of the present invention to provide a leakage prevention device for a classification device which is designed to prevent the leakage.

Means for Solving the Problems In order to achieve the above-mentioned object, according to the present invention, a leakage prevention device of a classifying device has a rotary classifying impeller in a casing, and a fine powder selected is made to flow. In the classifying device of the type in which the rotary classification impeller is made to flow into and pass through the rotary classification impeller and is discharged to the outside of the casing, the rotary seal member is provided on the upper plate of the rotary classification impeller so as to be located at the boundary between the rotary classification impeller and the fine powder discharge duct. It is characterized in that the rotary seal member is mounted on the upper side and the upper portion of the rotary seal member is projected outward from the opening of the casing top plate to prevent the powder on the radially outer side from leaking into the fine powder discharge duct side.

Therefore, according to the present invention, according to the above-mentioned means, in the boundary portion between the rotary classification impeller and the fine powder discharge duct of the classification device,
The upper part of the rotary seal member provided on the upper plate of the rotating rotary classification impeller is projected outward from the opening of the top plate of the casing, and the powder in the raw material classification chamber on the radially outer side is discharged to the side of the fine powder discharge duct. Leakage can be prevented.

Other objects, features and advantages of the present invention will become apparent from the detailed description below with reference to the accompanying drawings.

First Embodiment FIGS. 1 and 2 of the drawings show a first embodiment of a classifying device equipped with a leakage prevention device according to the present invention. This classifying device has a generally cylindrical upper part and a generally lower part. A casing 1 having a conical hopper shape is provided, and an air inlet 2 for classification is provided in a tangential direction on a side surface of a cylindrical portion of the casing 1, and
A raw material charging port 3 is provided at the top of the casing 1, and a rotary vertical shaft 4 is provided at the center of the casing 1. The rotary vertical shaft 4 is provided with a rotor having a classification blade 6, that is, a rotary classification impeller 5. Also, casing 1
A plurality of fixed guide vanes 7 are arranged concentrically with the rotary shaft 4 at a constant angle between the inner wall of the cylindrical part of the rotary impeller 5 and the rotary impeller 5, and the raw material on the periphery of the upper plate of the rotary classification impeller 5 is arranged. An annular collision plate 8 is provided inside the casing 1 so as to surround the dispersion chamber 10.
Are provided concentrically with the rotating vertical shaft 4. Furthermore, at the center of the top of the casing 1, a fine powder discharge duct 9 for surrounding the rotary shaft 4 and discharging the classified fine powder is provided.

In such a classification device, the leak prevention device 20 of the present invention is provided at the boundary between the rotary classification impeller 5 and the fine powder discharge duct 9. That is, as clearly shown in FIGS. 1 and 2, the leakage prevention device 20 includes the rotary classification impeller 5 at the boundary between the upper plate of the rotary classification impeller 5 and the end of the fine powder discharge duct 9. An upper part of the rotary seal member 21 is provided with an annular rotary seal member 21 fixed to the upper plate.
Is projected outward from the opening 12 of the top plate 11 of the casing 1 to separate the fine powder discharge duct 9 and the raw material dispersion chamber 10. Further, the projecting length of the upper portion 22 of the rotary seal member 21 is appropriately determined so as to slightly project from the top plate 11 of the casing 1, and the opening 1 of the casing 1 and the top plate 11 is determined.
It is appropriately determined so that the gap between the two and 2 is small. Furthermore,
A sealing material 24 can be provided on the upper portion 22 of the rotary seal member 21 as required. If necessary, a plurality of ribs 29 may be provided around the upper plate of the rotary classification impeller 5 to enhance the effect of dispersing the charged raw material.

Further, FIGS. 3 to 5 of the drawings show a second and an embodiment of the classifying device provided with the leakage prevention device of the present invention. In this embodiment, the upper portion of the outer peripheral surface of the rotary seal member 21 is In addition, a plurality of small blades 26 are arranged on a circle concentric with the rotary shaft 4 so that external air can be sucked in from the gap of the opening 12 of the top plate 11 of the casing 1 to further enhance the sealing effect. There is. The length of these small blades 26 is preferably about ⅕ or more and equal to or less than the height of the raw material classifying chamber 10, and there is some gap with the top plate 11 of the casing 1 from the opening 12. It is designed to allow external air to flow in. In addition, as shown in FIG.
6'is arranged like the blade of an axial fan at an appropriate angle in the axial direction with respect to the outer peripheral surface of the rotary seal member 21, so that the intake of external air can be further improved.

In the classifying device having the leakage prevention device 20 of the present invention configured as described above, first, the classification raw material is introduced through the raw material introduction port 3 and the classification air is introduced through the air intake port 2 and the fixed guide vane is introduced. A vortex flow is formed by the classification blade 6 attached to the rotary dispersing impeller 7. The charged raw material falls onto the upper plate of the rotary classification impeller 5, is bounced off by the rotation of the rotary classification impeller 5, and is collided and dispersed by the collision plate 8.
It falls into the classified air vortex. The particles of the raw material that ride on the vortex receive the centrifugal force due to the swirling of the vortex and the resistance force according to the inward component velocity, and the balance between these forces sorts out coarse particles to the outside and fine particles to the inside. .

The fine particles thus selected pass through the rotary classification impeller 5 and are discharged through the fine powder discharge duct 9. On the other hand, the coarse particles fall while swirling inside the guide vanes 7 and discharged from the conical hopper in the lower part of the casing 1 to the outside of the machine. At this time, the pressure drops toward the center of the classifying device due to the formation of a vortex and the fan effect of the classifying blades 6 of the rotary classifier impeller 5. Therefore, the pressure of the fine powder discharge duct 9 becomes lower than the pressure of the outside, that is, the raw material dispersion chamber 10. On the other hand, a boundary portion between the fine powder discharge duct 9 and the rotary classification impeller 5 needs to be provided with a gap or have a sliding structure so as not to hinder the rotation of the rotary classification impeller 5. But, as I said,
The sliding structure is not suitable for sealing the solid-gas mixture, and when a gap is provided, an air flow is generated toward the fine powder discharge duct 9 through the boundary portion composed of the raw material falling portion due to the pressure difference,
Coarse particles in the raw material may leak along with this air flow.

In addition, in the leakage prevention device 20 of the present invention, the rotary seal member 2 is provided on the upper plate of the rotary classification impeller 5 at the boundary between the rotary classification impeller 5 and the fine powder discharge duct 9.
1 is installed and the upper part 22 is attached to the top plate 11 of the casing 1.
Of the low pressure fine powder discharge duct 9 and the high pressure raw material dispersion chamber 10 are completely separated by projecting outward from the opening 12 to prevent an air flow from the raw material dispersion chamber 10 toward the fine powder discharge duct 9 through the boundary portion. The opening 1 of the top plate 11 of the casing 1
2 has a structure in which a small amount of air flows into the fine powder discharge duct 9 side and into the raw material dispersion chamber 10 side through a gap between the rotary seal member 21 and the rotary seal member 1.
The outer air is sucked radially outward from the opening 12, that is, in the raw material dispersion chamber 10 in the present embodiment by a plurality of small blades 15 provided on the outer periphery of the raw material classification chamber 10 toward the fine powder discharge duct 9 side. It is possible to reliably prevent the powder from leaking, and it is possible to completely prevent the coarse powder of the unclassified powder from being mixed into the fine powder in the fine powder discharge duct 9.

As described above, in the leakage prevention device of the classifying device of the present invention, the upper part of the rotary seal member provided on the upper plate of the rotary classifying impeller is projected upward through the opening of the top plate of the casing to form fine powder. The exhaust duct and the raw material dispersion chamber are completely separated, and the desired sealing effect is achieved by sucking external air into the raw material dispersion chamber on the raw material input side by a plurality of small blades provided on the outer periphery of the rotary seal member. In addition, it is possible to obtain the effect that it is more economical because it sucks and seals the external air, and that the structure is simple, the manufacturing is easy and the manufacturing cost is low. Furthermore, the leakage prevention device of the classifying device of the present invention is particularly useful for those in which the inclusion of coarse particles such as fillers and fine ceramic raw materials causes a serious quality defect, and does not require a special external device. It is possible to completely prevent the leakage, and it is possible to greatly improve the quality and reduce the cost when applied to these fields.

In the present embodiment, the classifying device of the type in which the raw material feeding port 3 is provided at the top of the casing has been described, but the raw material feeding method is not limited to this, or together with this, the casing tangential direction or from below the casing. Needless to say, the present invention can be applied to a classifying device of a throwing-in type, in short, it is applied to a device for preventing leakage into the fine powder discharge duct from the gap between the casing top and the classifying impeller upper plate without passing through the inside of the classifying impeller. it can.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a first embodiment of a classifying device provided with a leakage prevention device of the present invention, and FIG. 2 is an enlarged sectional partial view of a leakage prevention device portion in FIG. 1, FIG. Is a longitudinal sectional view of a second embodiment provided with a leakage prevention device of the present invention, FIG. 4 is an enlarged sectional partial view of the leakage prevention device of FIG. 3, and FIG. 5 is V- of FIG. FIG. 6 is a side view seen along the line V, and FIG. 6 is a side view showing a modified example of the small blade in FIG. In the figure, 1: casing, 2: air inlet, 3: raw material inlet, 4: rotating vertical shaft, 5: rotary classifying impeller, 6: classifying blade, 7: guide blade, 8: collision plate, 9: fine powder Exhaust duct,
10: Raw material dispersion chamber, 11: Top plate, 12: Opening, 20, 2
0 ': leak prevention device, 21: rotary seal member, 2
2: upper part, 24: seal member, 26, 26 ': small blade,
29: Rib.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-51-44368 (JP, A) real-open Sho-64-8982 (JP, U) real-open Sho-63-9277 (JP, U) real-open Sho-53- 105075 (JP, U)

Claims (3)

[Claims] 1. A classifying device of the type having a rotary classification impeller in a casing, wherein selected fine powder flows into and passes through a rotary classification impeller together with an air stream and is discharged to the outside of the casing. The rotary seal member is mounted on the upper plate of the rotary classifying impeller so as to be located at the boundary with the duct, and the upper part of the rotary seal member is projected outward from the opening of the casing top plate so that the powder on the radially outer side is A leak prevention device for a classification device, characterized in that it is designed to prevent the body from leaking to the side of the fine powder discharge duct. 2. The leak prevention device for a classifying device according to claim 1, wherein the upper portion of the rotary seal member projecting outward from the casing top plate is sealed by a sealing material on the casing storage plate. 3. The leakage prevention device for a classifying device according to claim 1, wherein a plurality of small blades are provided on the outer periphery of the rotary seal member attached to the upper plate of the rotary classifying impeller.