JPH0337752Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a centrifugal classifier using an air flow that separates a supplied powder into coarse powder and fine powder by swirling flow and collects each powder. In particular, the present invention relates to a centrifugal classifier equipped with means for dismantling and dispersing aggregates of powder particles generated during the classification process, and for preventing adhesion of powder particles pushed to the inner circumferential surface by centrifugal force.

[Prior Art] One of the methods for centrifugally separating powder and granular material supplied to the classification chamber of a centrifugal classifier into coarse powder and fine powder by swirling flow is to A mechanism is known in which a rotor is rotated, a sizing fluid is fed into the rotor, and powder is also supplied.

This is achieved by feeding compressed air as a particle sizer fluid into the housing in which the rotor is rotating, and supplying powder and granules from the supply port provided in the annular ring part. The fine powder is pushed toward the inner peripheral surface of the annular ring part by the action of centrifugal force, moves in the direction of rotation, reaches the outlet passage, and is carried out along with the fluid, while the fine powder communicates with the sizing area of the opening near the outer circumference of the rotor. During the classification process, the powder particles are continuously dispersed and individually sized, and are carried out along with the fluid toward the outlet through an axial passage provided in the axial center of the rotor. Statistically uniform particle size is achieved throughout the classification process.

[Problem that the invention aims to solve] When classifying powders of various substances, the degree of agglomeration of all of them in air is quite high;
It is practically impossible to collect all dispersed particles as individual particles at the same time during the classification process. Therefore, the particles during the classification process contain agglomerates of various sizes. Since the powder is eventually recovered as coarse powder through the exit passage, the coarse powder also contains fine powder produced by agglomerates, and the accuracy of particle sizing is greatly reduced.

In addition, when the target is powder or granules of substances with strong adhesion, the degree of agglomeration is naturally high, and during classification, centrifugal force forces the inner peripheral surface of the annular ring part and it often sticks to the inner surface of the annular ring part. When these layers are stacked one on top of the other, there are problems such as the swirling flow is disturbed, making it impossible to divide the particles, and causing various problems.

[Means and actions for solving the problems] In order to solve these problems in a centrifugal classifier using a rotor, an annular ring with a width approximately the same as the opening width on the outer periphery of the rotor is provided throughout the inner periphery of the annular ring portion. A recess is provided, and from the powder inlet opening in the recess to the coarse powder outlet opening along the rotational direction of the rotor, the annular ring portion extends over the entire area adjacent to both openings. By creating a structure in which pressurized fluid is ejected from both sides of the annular recess in parallel to the inner circumferential surface, the coarse particles pushed outward by centrifugal force during the classification process are separated. As the granular fluid flows, it tries to contact the inner circumferential surface of the annular recess in the annular ring part, but it is not only blocked but also agitated by the pressure fluid that is ejected in the opposite direction while covering the surface, so that it is not only blocked but also agitated. The purpose is to break up and disperse mixed aggregates and prevent them from adhering to the inner peripheral surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A more detailed explanation will be given below based on embodiments of the present invention with reference to the drawings.

FIG. 1 is a schematic diagram showing a route for conveying powder and granules using compressed air as a sizing fluid in an apparatus related to a centrifugal classifier of the present invention.

The rotor in the housing 22 of the centrifugal classifier 10 is rotated in the direction of arrow A by a motor (not shown), and becomes operational when compressed air is supplied from the fluid source 11 through the inlet 12. Become. At this time, when the powder is supplied from the supply port 13, it enters the centrifugal classifier 10 from the inlet 14 and is divided into coarse powder and fine powder, and the coarse powder passes through the coarse powder outlet 15 and reaches the recovery department.
It is separated from the output fluid by a separator 16 and collected in a storage container 17. On the other hand, when the fluid that has finished being conveyed is turned back, it is sucked through the suction device 18 by compressed air sent separately from the fluid source 11.
3 provided in the housing 22 to join the compressed air.
It enters and circulates through separate entrances 19.

Further, the sized fine powder passes through an axial passage provided at the axial center of the rotor and is collected from the fine powder outlet 20 into the storage container 21, but the fluid that has been conveyed is transferred to the storage container 21. It is separated from fine powder and released into the atmosphere as a clean product.

FIG. 2 is a cutaway side view of the centrifugal classifier 10 according to the present invention, showing the cross section 2-2 in FIG.
The figure is also a front sectional view, and section 3 in Fig. 2.
-3 is shown.

The housing 22 is made up of a disc-shaped side wall with a flat surface on the outside, a body 23 formed by an annular wall integral with the side wall, and a disc-shaped cover 24 that closes the open end of the annular wall. to form a ventilation chamber. The rotor 25, which is mounted to rotate within the ventilation chamber by a drive shaft 27 supported by a bearing in the center of the housing 22, is rotated by two opposing symmetrical circular plates 25', 25''. It is fitted onto the shaft 27 while sandwiching a plurality of fins 26 arranged on the same circumference at equal radial intervals from the shaft center, and is tightly fixed with a nut 28.

Circular plate 25', 2 with rotor 25 assembled
5'' forms an opening 29 at a distance on the outer peripheral facing surface, and provides a space approximately the height of the fin 26 from the upper end of the fin 26 to the outer peripheral end of the rotor 25, and from the opening end to the upper part of the fin 26. The sides up to the vicinity of both ends are sloped surfaces, and the cross-sectional shape of the space formed by the circular plates 25' and 25'' is trapezoidal, forming a grain sizing area 30.

As shown in FIG. 8, an annular ring 31 which maintains a slight gap from the outer periphery of the rotor 25 and has an annular recess 32' on the entire inner periphery with approximately the same width corresponding to the opening 29.
are screwed to mounting seats provided in the body 23 at several locations. This annular ring 31 is formed by overlapping two rings cut in half in the shape of a ring, and as shown in FIG.
4 and a coarse powder outlet 15 are opened at the bottom circumferential surface of the annular recess 32', and three compressed air inlets 19 are provided. 25 along the rotation direction A of the coarse powder outlet 15, the two inlet and outlet passages are provided at an appropriate interval so as to communicate with an arc-shaped hollow chamber 32 which is provided in an adjacent range and whose inner circumferential side is completely open. It will be arranged in

Furthermore, on the open side of the hollow chamber 32, a band-shaped closing plate 33 curved so as to form the same circumferential surface as the annular recess 32' connected thereto is fitted in several places on both sides of the hollow chamber 32, as shown in FIG. Ring pieces 31', 3 cut in half through a U-shaped holding piece 34
The hollow chamber 32, which is formed with a diameter of 1", is fitted and held in opposing circumferential grooves 35 provided on both side walls. Therefore, most of the both sides of the closing plate 33, except for the holding piece 34, are in the circumferential groove. 35 and is in a floating state, the hollow chamber 32 is communicated with the outside by bending both sides of the closing plate 33 via the circumferential groove 35.

When the classifier 10 is in operation, compressed air used as a sizing fluid is introduced from the inlet 12, passes through the air passage 23' that goes around the outer periphery of the annular ring 31, fills the space inside the housing 22, and swirls. Since it flows toward the outlet as a stream, it flows into the opening 29 from both sides of the annular gap formed by the outer periphery of the rotor 25 and the annular ring 31, but the rotor 25 is rotated at a predetermined speed by the motor. Therefore, the swirling flow becomes even stronger due to the action of the fins 26, and the annular ring 31
The liquid flows out through the outlets 15 and 20 sequentially while swirling through the space of the particle sizing area 30 including the annular recess 32'.

The powder supply inlet 14 is provided in the tangential direction to the rotation direction A of the rotor 25 on the side where it is sucked by the swirling flow, and the coarse powder outlet 15 is provided on the side where it is pushed out. The annular recess 32' opens toward the opening 29 and forms a passage that communicates the body 22 and the annular ring 31.

The path leading to the fine powder outlet 20 passes between the radial intervals of the fins 26 toward the shaft center, passes through several communication holes 36 drilled in the shaft 27, and passes through an axial passage 37 provided in the shaft center. The fine powder outlet 20 is reached at the tip of a connecting cap 38 which is tightened and held by the cover 24 and takes over the passage 37 .

When powder or granular material is supplied from the supply port 13 to the classifier 10 in operation, it enters the housing 22 from the inlet 14, enters the sizing region 30 of the rotor 25 together with compressed air, and is dispersed by the circulating flow. , the fine grains are carried inward toward the axis and are carried out by the fluid through the outlet 20.

On the other hand, the coarse powder is pushed toward the annular ring 31 by the centrifugal force caused by the swirling flow, and tries to swirl, but the compressed air entering from the three inlets 19 passes through the hollow chamber 32 and blows out from both sides of the closing plate 33. Since it acts as an air curtain and covers the surface of the blocking plate 33, it not only prevents adhesion but also breaks up and disperses the aggregates mixed in the coarse powder by stirring, and the sized coarse powder is sent to the outlet 15. It is carried out by fluid.

[Effects of the invention] As an example showing that the recovery rate of fine powder was improved by the invention, a comparison test was conducted under the same conditions with a conventional type (without air curtain). Rotation speed 2600 rpm Air volume 1.8 m ³ /min Compressed air pressure (Kg/cm ² ) 0.8 1.2 2.0 Test time 15 ^min for each air pressure Test raw material Silica sand (-15 μ) Raw material supply amount 500 gr / 15 ^min Results: Fine powder recovery rate (Average of 3 times by air pressure) Conventional type 17.5% Invention 27.8% As mentioned above, the fine powder recovery rate has been significantly improved, proving that the effect is remarkable.

In addition, contact of swirling coarse powder on the inner circumferential surface of the annular ring is prevented, which eliminates various problems such as inability to size particles caused by adhesion of powder and stacking, and also prevents abrasion of the inner circumferential surface due to coarse powder. This eliminates the need to use expensive wear-resistant materials like in conventional types, and it has many excellent features that make it advantageous in terms of processability and cost.

It should be noted that the shape of the holding piece 34 shown in FIG. 5 that holds the closing plate 33 in the embodiment of the present invention may be modified as shown in FIG. Needless to say, various changes and modifications are possible without being limited to the embodiment, such as omitting the piece 34 and instead providing partial overhangs at several locations on the cover plate 33 to form an integrated structure. .

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a route for conveying powder and granules using compressed air as a sizing fluid in an apparatus related to a centrifugal classifier of the present invention, and Fig. 2 is a diagram showing a fracture of a centrifugal classifier according to an embodiment of the present invention. The side view shows cross section 2-2 in FIG. 3, and FIG. 3 is a front sectional view, showing cross section 3-3 in FIG. 2, and FIG. FIG. 5 is a perspective view of a holding piece according to an embodiment, FIG. 6 is a perspective view of an example holding piece deformed together with the clamping circumferential groove, and FIG. 7 is a partial perspective view of a holding piece in place of the holding piece. FIG. 8 is a partial perspective view of an example of an integrated closure plate, showing the cross section 8-8 in FIG. 3. 10: Centrifugal classifier, 12: Sizing fluid inlet, 1
4: Powder inlet, 15: Coarse powder outlet, 18: Aspirator, 19: Compressed air inlet, 20: Fine powder outlet, 2
2: housing, 25: rotor, 27: drive shaft,
29: Opening portion, 30: Grain sizing area, 31: Annular ring, 33: Closure plate, 34: Holding piece, 35: Circumferential groove, 3
2: Hollow chamber, 32': Annular depression.

Claims (1)

[Claims for Utility Model Registration] (1) In the housing that includes the annular ring part,
A rotor is attached to rotate inside the annular ring part and has a gap formed therebetween, and has an opening communicating with the gap, and the rotor is rotated, and the sizing fluid is fed from the fluid inlet of the housing. A swirling flow is generated by
By supplying powder fluid from the powder inlet provided in the annular ring part, the coarse powder is separated into coarse powder and fine powder by centrifugal force in the particle dividing area of the opening near the outer periphery of the rotor. , while being carried out from a coarse powder outlet disposed in front of the powder inlet with respect to the rotational direction of the rotor and communicating with the opening,
In a centrifugal classifier, the fine powder flows inward toward a coarse powder outlet through an axial passage provided at the axial center of the rotor in communication with the sizing region, and is carried out together with the fluid. , a concentric annular recess is provided on the inner periphery of the annular ring portion, with a constant width leaving a little on both sides of the annular ring portion, and
From the powder inlet opening in the recess to the coarse powder outlet opening along the rotational direction of the rotor, the entire area adjacent to both openings, on both sides of the annular recess of the annular ring portion. A centrifugal classifier characterized in that a means is added for ejecting pressurized fluid from the surface in parallel to the inner circumferential surface of the recess so as to cover the surface. (2) Registration of a utility model characterized in that a means is added for ejecting pressurized fluid from either side of both sides of the annular recess of the annular ring portion in a manner parallel to the inner circumferential surface of the recess and covering the surface. A centrifugal classifier according to claim 1.