JPH0615073B2 - 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 discharged and 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 fixed casing end surface, and the fine powder is discharged from this gap. There is a phenomenon that coarse powder leaks into the exhaust duct.

Therefore, in order to prevent the coarse powder from leaking through the gap 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 boundary. Alternatively, a means such as injecting a seal gas is adopted. However, there is a problem that the slipping means cannot completely prevent the leak and cannot obtain a sufficient result.

That is, in the labyrinth structure, the air flow caused by the pressure difference between the inside and outside of the labyrinth is expanded and compressed by the maze structure so that the pressure is attenuated, but it is not a perfect seal structure, but a 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 are drawbacks such as the performance and cost being greatly affected by the excess and deficiency of the injection amount.

On the other hand, in the leak prevention device of the classifying device described in the specification of Japanese Patent Application No. 63-6776, which was previously filed, the above-mentioned leak is prevented by an extremely simple device, but the following problems occur. There is also. That is, generally, the pressure on the side of the fine powder discharge duct is lower than the pressure on the outside of the casing, and it is normal for air to flow from the outside to the side of the discharge duct. In response to this, this force overcomes the aerodynamic force flowing from the outside of the casing to the exhaust duct side, and conversely the powder is ejected from the exhaust duct side to the outside of the casing, which not only reduces the fine powder recovery but also causes the problem of environmental pollution. Can be seen.

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 having an annular groove is provided on the upper plate of the classifying impeller, and the upper portion of the rotary seal member is projected outward from the opening of the casing top plate so as to extend from the outer side in the radial direction to the fine powder discharge duct side. An object of the present invention is to provide a leak prevention device for a classifying device that prevents the powder from leaking.

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 a classifying device of a type in which the rotary classification impeller is allowed to pass through and discharged to the outside of the casing, a rotary seal member having an annular groove is positioned at the boundary between the rotary classification impeller and the fine powder discharge duct. It was mounted on the top plate of the vehicle, and the upper part of the rotary seal member was projected outward from the opening of the casing top plate to prevent the powder outside on the radial direction from leaking to the fine powder discharge duct side. It has a feature.

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, which has an annular groove provided on the upper plate of the rotating rotary classification impeller, protrudes outward from the opening of the top plate of the casing to finely powder the powder in the raw material classification chamber on the outer side in the radial direction. It is possible to prevent leakage into the exhaust duct side, and from the outside of the casing to the exhaust duct side without being affected by the centrifugal force received by the fine powder classified by the U-tube structure of the rotary seal member. To prevent the fine powder from spouting outside the casing, and to prevent the powder from leaking to the fine powder discharge duct side. From the outside of the casing, adjust the gap between the lower end of the fine powder discharge duct and the rotary seal member, which forms the fixed seal part, so that the flow velocity of the incoming air is equal to or higher than the wind velocity in the fine powder discharge duct. The force on the exhaust duct side is predominant.

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, an air inlet 2 for classification is provided in a tangential direction on the side surface of the cylindrical portion of the casing 1, and a raw material inlet 3 is provided at the top of the casing 1 and inside the casing 1. A rotary vertical shaft 4 is provided at the center of.
The rotary vertical shaft 4 is provided with a rotor having a classification blade 6, that is, a rotary classification impeller 5. In addition, 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 portion of the casing 1 and the rotary impeller 5, and the upper plate of the rotary classification impeller 5 is An annular collision plate 8 is provided inside the casing 1 so as to surround the raw material dispersion chamber 10 on the periphery and concentrically with the rotary 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 classifying device, the leaking device 20 of the present invention is provided at the boundary between the rotary classifying impeller 5 and the fine powder discharge duct 9.
Will be provided. 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 annular rotary seal member 21 fixed to the upper plate is provided, and an upper portion 22 of the rotary seal member 21 is projected outward from the opening 12 of the top plate 11 of the casing 1, and the fine powder discharge duct 9 and the raw material dispersion Separated from the chamber 10. Further, the protruding 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 gap between the top plate 11 of the casing 1 and the opening 12 is appropriately small. Determined.

In addition, the rotary seal member 21 of the leak prevention device 20.
Has an annular seal structure having a gap to the lower end of the fine powder discharge duct 9 forming a fixed seal portion, and the fine powder discharge side of the rotary seal member 21 has a U-shaped pipe structure 23. The tube structure 23 has a structure in which the tip end portion of the lower end of the fine powder discharge duct 9 is wrapped. The length of the rotary seal member 21 of the leakage prevention device 20 on the fine powder discharge side may be about 1/5 of the length from the top plate 11 portion of the casing 1 so as to wrap the lower end portion of the fine powder discharge duct 9 in a U shape. The tip of the tube structure 23 may have any of a rectangular shape, a round shape, and a round shape. It is more preferable that the tip of the rotary seal member 21 has an inclined acute angle structure 23 ', and centrifugal force is generated by the internal vortex flow. The received fine powder is discharged along the fine powder discharge duct 9 to smooth the flow to the rotary seal member 21 and the discharge duct 9, and no air turbulence occurs between the rotary seal member 21 and the discharge duct 9 for discharge. As described above, the tip of the rotary seal member 21 can have an acute angle structure 23 '. If necessary, a plurality of dispersion plates 29 may be provided around the upper plate of the rotary classification impeller 5 to enhance the dispersion effect of the introduced raw material.

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 is formed by 7 and the classification blade 6 attached to the rotary classification impeller 5. The charged raw material falls on the upper plate of the rotary classification impeller 5, is splashed by the rotation of the rotary classification impeller 5, is collided and dispersed by the collision plate 8, and falls into the classification air vortex. The particles of the raw material riding on the vortex receive a centrifugal force due to the swirling of the vortex and a resistance force according to the inward component velocity, and by the balance between these forces, coarse particles are sorted to the outside and fine particles are sorted to the inside.

The fine particles thus selected pass through the rotary classification impeller 5, and the fine particles that have been subjected to the centrifugal force by the internal vortex flow are discharged along 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 classification device due to the formation of a vortex and the fan effect of the classification blade 6 of the rotary classification 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. However, as described above, the sliding structure is not suitable for sealing the solid-gas mixture, and when a gap is provided, the air flow from the raw material falling portion to the fine powder discharge duct 9 via the boundary portion due to the pressure difference. And the coarse particles may leak into the raw material due to 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
A small amount of air flows into the fine powder discharge duct 9 through the gap between the rotary seal member 21 and the rotary seal member 21, and has an air flow velocity equal to or higher than the wind speed in the fine powder discharge duct 9. Further, it has a structure in which an appropriate amount of air flows into the raw material dispersion chamber 10 side, and external air is sucked into the raw material dispersion chamber 10 in the radial direction from the opening 12, that is, in the present embodiment, so that the fine powder is fed from the raw material classification chamber 10. It is possible to reliably prevent the powder from leaking into the discharge duct 9 side, and completely prevent the coarse powder of the unclassified powder from being mixed into the fine powder in the fine powder discharge duct 9.

On the other hand, since the rotary seal member has a U-shaped structure, the fine powder classified is prevented from being spouted to the outside of the casing due to the influence of the centrifugal force, and environmental pollution can be reliably prevented.

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 can be achieved by sucking the external air into the raw material dispersion chamber on the raw material input side, and it is more economical because the external air is sucked and sealed. Thus, it is possible to obtain effects such as a simple structure, easy manufacturing, and low cost. Furthermore, the leakage preventive device of the dispersion device of the present invention is particularly effective for those in which coarse particles such as fillers and fine ceramic raw materials become a serious quality defect, and coarse powder can be obtained without requiring a special external device. Can be completely prevented from leaking, and when applied to these fields, the quality can be greatly improved and the cost can be reduced.

In the present embodiment, the classifying device of the type in which the raw material feeding port is provided at the top of the casing has been described, but the raw material feeding method is not limited to this, or the raw material is introduced from the tangential direction of the casing or from below the casing. Needless to say, the present invention can be applied to a classifying device of the type described above. .

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an 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 the leakage prevention device portion in FIG. In the figure,
1: casing, 2: air inlet, 3: raw material inlet,
4: rotary vertical shaft, 5: rotary classification impeller, 6: classification blade,
7: guide vane, 8: collision plate, 9: fine powder discharge duct, 10:
Raw material dispersion chamber, 11: Top plate, 12: Opening, 20: Leakage prevention device, 21: Rotating seal member, 22: Upper part, 29:
Dispersion plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-184086 (JP, A) JP-A-184085 (JP, A) JP-A-1-184084 (JP, A) JP-A-51- 44368 (JP, A) Actually opened 64-8982 (JP, U) Actually opened 63-9277 (JP, U) Actually opened 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 is allowed to flow into the rotary classification impeller together with an air stream and is discharged to the outside of the casing. A rotary seal member having an annular groove so as to be located at the boundary with the duct is mounted on the upper plate of the rotary classification impeller, and the upper part of the rotary seal member is projected outward from the opening of the casing top plate, A leak prevention device for a classifying device, characterized in that it prevents the powder on the radially outer side from leaking into the fine powder discharge duct side. 2. The leak of the classifying device according to claim 1, wherein the annular groove in the lower portion of the rotary seal member, the upper portion of which protrudes outward from the casing top plate, is structured to wrap and seal the lower portion of the fine powder discharge duct. Intrusion prevention device. 3. The leak prevention device for a classifying device according to claim 1, wherein the end portion of the rotary seal member on the fine powder discharge side has a square, round or inclined acute angle structure.