JP2897905B2 - Classifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a classification device for classifying raw material powders of chemicals used in the ceramics industry and the filler industry into coarse powders and fine powders. In particular, the present invention relates to a classifier that separates raw material powders into a classifying chamber to improve the classifying effect.

[0002]

2. Description of the Related Art A classifier is designed to select a powder having a required particle size from a pulverized material obtained by a pulverizer by an air current to produce a product. The principle of the classification is gravity classification and inertia force. Classification is classified into classification and centrifugal force classification. Among them, centrifugal force classification suitable for large-scale classification of powder is classified into a free vortex type in which the air flow is swirled by making the shape of the classification chamber spiral, and a classification chamber There are two types: a forced vortex in which the airflow is forcibly swirled by rotating blades provided in the vortex, and a shared vortex in which a free vortex and a forced vortex are combined.

[0003] Further, a classifier is provided with a powder and granules pulverized by a pulverizer and provided separately and separately from the pulverizer, or a pulverizer provided with the pulverizer and provided in a pulverization chamber. There is an auxiliary type in which the granules are introduced into a classification chamber by air flow for classification, but the latter type is also widely used and is often used in conjunction with a pulverizer.

[0004] Recently, along with the diversification of pulverized raw materials and the increase in demand for ultrafine powder, the demand for the particle size distribution of products has become more sophisticated. Increasingly, there is a demand for products that keep the throughput of much smaller specified particle sizes within a certain ratio. As described above, under severe grinding conditions in which the average particle size of the product is small to some extent and the mixing ratio of the fine powder is not so large, the pulverized raw material containing a large amount of fine powder can be mixed with a pulverizer equipped with an ordinary classifier. If these were pulverized as they were, these conditions could not be achieved, and there were problems such as over-pulverization.

[0005] In order to solve the above-mentioned problems, the present applicant has proposed a classification device as disclosed in Japanese Patent Application No. 3-81053, for example. As shown in FIG. 5, the classifier includes a drive shaft 3 composed of a hollow tube rotatably supported at the center of a classifying chamber 2X, and a plurality of classifying blades 12 which rotate around the drive shaft 3 integrally therewith. A fine powder discharge pipe 17 is provided above the hollow pipe 3, and a plurality of guide vanes 13, which are rotatable about a vertical axis on the outer circumference of the classifying blade 12, for turning the classifying air, are provided on the circumference. In the classification device 2 which is provided concentrically with the hollow tube 3 and is connected to the guide vane 13 and provided with an inverted conical guide cone 14, the classification blades 12
And a horizontal disk-shaped dispersion plate 15 covering the guide vanes 13 is fixed to the hollow tube 3, and a plurality of circumferential scrapers 15 a orthogonal to the dispersion plate 15 are fixed on the dispersion plate 15. Supply pipe 16 for the pulverized raw material to the casing 2a of the classifying device 2 immediately above the dispersion plate 15 and the scraper 15a.
Is arranged. The operation of the classifier 2 will be described. The raw material is supplied to the classifying chamber 2X, falls onto the rotating dispersion plate 15, and overflows from the dispersion plate 15 almost uniformly around the circumference by the dispersion plate 15 and the scraper 15a. Most coarse particles fall down. Then, the fine powder contained in the falling raw material is swirled together with the rising airflow from the crusher 1 below the classification device 2, and passes through the guide vanes 13 to the classification blade 12. Here, classification is performed by the rotating classification blades 12,
The coarse powder in the fine powder is beaten down by the classifying blade 12 and cannot pass through the classifying blade 12, but falls along the wall surface of the lower guide cone 14 or the inner surface of the casing 2a and is pulverized by the pulverizer 1. Only the fine powder that has undergone the classification action and has passed through the classification blades 12 is discharged from the fine powder discharge pipe 17 through the hollow pipe 3 to the outside of the machine. In the pulverizer 1, the coarse particles of the new feed and the coarse powder after the classification are pulverized together, and only the powder having a relatively fine particle diameter is accompanied by the ascending airflow toward the guide vane 13 by the classification blade 12 in the same manner as described above. Classified.

[0006]

However, in the classifier described above, the fine powder after classification is discharged above the center of the device, and the supply pipe of the raw material powder to be supplied is not located at the center of the device. Since it is provided at a certain point on the outer periphery of the dispersion plate, the dispersion of the raw material powder overflowing from the dispersion plate is not uniform around the circumference. In particular, the ratio of the raw material supply amount to the air amount flowing through the classification chamber, When the concentration is high, there is a problem that the bias is large and the classification accuracy is reduced, and the fine powder yield is reduced when the high concentration powder is classified. Therefore, there has been a demand for a classifier capable of preventing high-priced, high-quality, high-concentration powder with a high fine powder yield and preventing the fine powder from being mixed into the coarse powder as much as possible.

[0007]

In order to solve the above-mentioned problems and to provide a classifier having a high fine powder yield, the classifier according to the present invention comprises a raw powder supply pipe at the center of the top of an upright cylindrical casing. A drive shaft comprising a hollow tube having a dispersion plate of raw powder fixed on the upper portion thereof and a plurality of classifying blades provided directly below the dispersion plate so as to be rotatable on a central axis of the casing. Support,
A fine powder discharge port for discharging dust-containing air containing fine powder classified by the classification blade is provided at the lower end of the hollow tube, and a donut-shaped horizontal disk is fixed to the inner peripheral side of the casing below the classification blade. Then, a plurality of circumferential stirring blades are fixed to the hollow tube between the classifying blade and the horizontal disk, and coarse powder discharged after classification is discharged to a casing opposed to the stirring blade. The pipes are connected tangentially, and an inlet pipe for the air flowing into the classifying blades is provided in a casing below the horizontal disk, and a cylindrical shape is provided immediately below the outer periphery of the dispersion plate with an appropriate distance from the outer periphery of the dispersion plate. The inner cylinder was coaxially fixed to the casing.

[0008]

In the classifying apparatus of the present invention, the raw powder fed from the center of the top of the apparatus is evenly distributed around the periphery of the dispersion plate by the rotating dispersion plate and falls to the outer periphery of the inner cylinder. The fine powder is directed to the classification blade by the suction force of the air flow, and undergoes the classification action, and the fine powder below the classification point passes down the hollow tube and is discharged from the fine powder discharge port together with air to the outside of the machine. On the other hand, among the fine powders introduced into the classifying blades, those finer than the classification point are hit by the classifying blades and fall freely. In addition, coarse powder and fine powder that fall freely between the inner cylinder and the casing against the rising air flow adhere to the surroundings.
On the way, it hits the stirring blade and separates into coarse powder and fine powder.
The fine powder rides on the ascending airflow, and the coarse powder is guided by the rotational force of the stirring blades and discharged out of the machine through a coarse powder discharge pipe tangentially mounted on the outer periphery of the casing.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings. 1 to 4 show an embodiment according to the present invention, FIG. 1 is a longitudinal sectional view of a classifier, FIG. 2 is a plan view of the classifier, FIG. 3 is an explanatory view showing the flow of powder in the classifier, FIG. 4 is a characteristic curve diagram showing a correlation between the powder concentration and the fine powder yield.
Solid arrows in the figure indicate the flow of the airflow. In the figure, the classifying apparatus 2 has a raw powder supply pipe 16 at the top of the center of an upright cylindrical casing 2a, and a classifying chamber 2X immediately below the supply pipe 16 has a hollow pipe (drive shaft) on the central axis of the apparatus. 3 is vertically supported via bearings 4 and 5, and is configured to be rotatable by a variable speed motor 9 via a V pulley 7a, a V belt 8a and a V pulley 10a attached to a lower portion of the hollow tube 3. . The bearings 4 and 5 are fixed and held by a gantry 6 supported by a support 6a. At the top of the hollow tube 3, a conical dispersion plate 15
Are fixed, and a plurality of scrapers 15a are vertically suspended radially around the circumference of the dispersion plate 15. Below the dispersion plate 15, a plurality (three in the embodiment of FIG. 1) of horizontal disks 11 are provided around the hollow tube 3 in multiple stages, and vertical classifying blades 12 are arranged between the horizontal disks 11 in a circle. It is arranged at equal intervals. Immediately below the dispersion plate 15, a cylindrical inner cylinder 30 having a diameter substantially equal to the diameter of the dispersion plate 15 is fixed to the outer periphery of the classification blade 12 from the casing 2 a via a support 30 a with an appropriate space therebetween. Below the classifying blade 15, a donut-shaped horizontal disk 80 is fixed to the casing 2a.
A plurality of stirring blades 70 made of a vertical flat plate are fixed to the hollow tube 3 at equal circumferential intervals so as to sweep over the upper surface of the horizontal disk 80 between the hollow tube 3 and the classifying blade 15. It is configured to rotate integrally. At one location on the peripheral surface of the casing 2a facing the stirring blade 70, a coarse powder discharge pipe 60 is provided tangentially and horizontally in the casing 2a as shown in FIG. Reference numeral 90 denotes a column base attached to a lower portion of the casing 2a. The support 6a is provided with a plurality of circumferentially attached air flow inlet pipes 50 that rise from below the casing 2a toward the stirring blade 70 and the classification blade 12. The classifying blades 12 may be radially radial, or may be retreating blades whose outer circumferential side retreats in the rotation direction.

Next, the classification device 2 constructed as described above
The operation of will be described. FIG. 3 shows the flow of the powder and air in the classifier 2. The raw powder (coarse and fine) dropped onto the rotating dispersion plate 15 is evenly distributed around the dispersion plate 15 by centrifugal force. Fall more freely. on the other hand,
Classifying blades 12 and stirring blades 7 integrally with the rotating hollow tube 3
0 is rotating, and the rising airflow flowing into the classifying blade 12 is always formed inside and outside the inner cylinder 12 while being swirled by the stirring blade 70, and the rising airflow rising in the introduction pipe 50 is always formed. The coarse powder (indicated by white circles in FIG. 3) overcomes these air currents or is bounced off by the classifying blades 12 and is discharged from the coarse powder discharge pipe, and the fine powder in the raw powder is classified by the classifying blades. In response to the classification operation of 12, only the fine powder below the classification point descends in the hollow tube 3 together with the inflowing air, is discharged from the fine powder discharge port 20 by the suction force of a suction fan (not shown), and is set at the downstream. Collected in the device. The fine powder adhering to the coarse powder is separated from the coarse powder when it is dropped on the horizontal disk 80 or struck by the stirring blade 70, so that the fine powder yield is further improved. The adjustment of the classification point is performed by controlling the rotation speed of the hollow tube 3 or controlling the air flow downstream of the hollow tube 3 and the air flow flowing through the coarse powder discharge tube 60.

The classification result obtained by the above operation was tested using a tester to obtain the same fine powder with the same raw powder (talc powder). When the inner cylinder was attached, the inner cylinder was removed. FIG. 4 shows the results of the tests performed together with the conventional test shown in FIG. 4, the fine powder yield N (the ratio of the fine powder weight below the classification point to the raw powder weight) for the same powder concentration M is smaller for the classifier according to the present invention (curve C) without the inner cylinder (curve C). It can be seen that it is superior to B) and the conventional machine (curve A).

As described above, in the classification device of the present invention, the fine powder after classification is caused to flow out below the central axis of the device, and the raw powder is dropped from above the axial center to the center of the dispersion plate. Is arranged below the dispersion plate, the dispersion of the raw material powder is very uniform, and the fine powder yield is improved. Moreover, even if the high-concentration powder was classified, the disadvantage of the conventional machine that the yield of fine powder was reduced was solved.

[0013]

According to the classification apparatus of the present invention, the homogenization of the dispersion of the raw powder is performed by performing the center feed, whereby the fine powder yield is improved and the high concentration classification can be performed without any trouble.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a classification device according to an embodiment of the present invention.

FIG. 2 is a plan view of a classification device according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a flow of a classification device according to an embodiment of the present invention.

FIG. 4 is a characteristic curve diagram showing a correlation between powder concentration and fine powder yield.

FIG. 5 is a longitudinal sectional view showing an example of a conventional classifier.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crusher 2 Classifier 2a Casing 2X Classification chamber 3 Hollow tube 4 Bearing 5 Bearing 6 Stand 6a Support 7 Chain wheel 7a V pulley 8 Roller chain 8a V belt 9 Variable speed motor 10 Chain wheel 10a V pulley 11 Horizontal disk 12 Classifier blade Guide vane 14 Guide cone 15 Dispersion plate 15a Scraper 16 Supply pipe 17 Discharge pipe 20 Fine powder discharge port 30 Inner cylinder 30a Support 50 Introduction pipe 60 Coarse powder discharge pipe 70 Stirring blade 80 Horizontal disk 90 Column base

Claims (1)

(57) [Claims] An upright cylindrical casing is provided with a raw powder supply pipe at the top center thereof, a raw powder dispersion plate is fixedly provided at an upper portion thereof, and a plurality of circumferential classifying blades are provided directly under the dispersion plate. A drive shaft composed of a hollow tube is rotatably supported on the central axis of the casing, and a fine powder discharge port for discharging dust-containing air containing fine powder classified by the classification blade is provided at a lower end of the hollow tube. With
A donut-shaped horizontal disk is fixed on the inner peripheral side of the casing below the classifying blade, and a plurality of circumferential stirring blades are fixed to the hollow tube between the classifying blade and the horizontal disk. , A coarse powder discharge pipe for discharging the coarse powder after classification is tangentially connected to a casing facing the stirring blade, and an intake pipe for air flowing into the classification blade is provided in a casing below the horizontal disk. A classifier, wherein a cylindrical inner cylinder is fixed coaxially with the casing just below the outer periphery of the dispersion plate and at an appropriate distance from the outer periphery of the dispersion plate.