JPH0477633B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fine powder classification apparatus, and more particularly to a dry fine powder classification apparatus for solid materials entrained in gas.

[Prior Art] In response to the demand for the production of micron-level particles and submicron-level particles, the above-mentioned fine particles are obtained by pulverizing the fine particles using a crusher and classifying the pulverized fine powder. In particular, there is a strong demand for more precise classification.

Conventionally, various devices have been proposed as this type of fine powder classification device, depending on the operating force required for classification. Things are being suggested.

The Coanda effect is a phenomenon in which when a fluid flows along a wall surface at high speed, it adheres to a curved surface such as a cylindrical wall. (For example, "Mechanical Engineering Handbook" Revised 6th Edition (July 20, 1982), P8-15).

As a conventional fine powder classification device that utilizes inertial force and the Coanda effect, an elbow jet classifier and the like have been attempted. (For example, Chemical Engineering Society, "Powder and Granule Engineering," (November 1, 1986), Maki Shoten, P158).

Elbow-jet classifiers consist of a two-dimensional non-rotating classifier and do not require mechanical methods.
This method changes the direction of airflow using the Coanda effect, and uses the inertial force of the particles contained in the air as the operating force to perform classification. Air is sucked in to carry away the particles, and this fine Powder floats and moves on the streamlines of airflow, and coarse powder flows straight down due to inertial force, so fine powder can be classified into fine powder and coarse powder.

[Problems to be Solved by the Invention] However, in the conventional fine powder classification device described above, the supplied fine powder is sufficiently dispersed in the airflow before entering the classifier and is introduced from the inflow region. The wall flow on the surface of the classifier is excessive in relation to the layer thickness of the air flow that causes the Coanda effect, or the wall surface that restricts the air flow other than the wall surface that causes the Coanda effect causes turbulence in the air flow. Therefore, there was a problem in that the turbulence of the airflow interfered with the classification characteristics due to the Coanda effect, and the fine powder was rolled into the coarse powder side, reducing the classification performance including the classification accuracy of fine powder. .

The present invention solves such conventional problems by dividing the wall flow adhering to the surface of the classifier, thereby directing the airflow to the coarse powder side and the fine powder side without causing any turbulence in the airflow. The purpose of the present invention is to provide an excellent fine powder classifier that can make full use of the classification characteristics due to the Coanda effect and significantly improve the classification performance of the fine powder classifier. .

[Means for Solving the Problems] In order to achieve the above object, the present invention has an inflow region for an air flow containing particles, an annular region in the center following the inflow region, and a substantially semicircular shape. a classification body having an annular cross section, a flow dividing means for dividing a wall flow adhering to the surface of the classification body following the annular flow passing through the annular region into an inner edge flow and an outer edge flow; It is provided with a fine powder discharge port provided on the outer periphery for guiding the inner edge flow, and a coarse powder discharge port provided in the direction of the central axis of the flow dividing means for guiding the outer edge flow.

[Function] The present invention has the following effects due to the above configuration. In other words, when classifying fine powder that is accompanied by a gas, the gas containing particles passes through a narrow annular region provided in the center of the classifier, forming an annular flow, and then flowing onto the surface of the classification surface forming the classifier. By dividing the wall flow adhering to the wall surface into an inner edge flow and an outer edge flow using a dividing means, the inner edge flow and the outer edge flow are guided to the fine powder side discharge port and the coarse powder side discharge port, respectively, without turbulence of the airflow. Gas is reliably attached to the surface of the body due to the Coanda effect, and the classification characteristics due to the Coanda effect can be fully utilized, significantly improving the classification performance including the classification accuracy of the fine powder classification device. be able to.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

1 and 2 show the configuration of an embodiment of the present invention.

In Fig. 1, 10 indicates a classifier, and 12
14 represents the inflow area of the airflow containing particles, and 14 represents the classified body, and the surface of the classified body 14 is the inflow area 1.
2, an annular classification surface 16 having an approximately semicircular cross section is formed. Also, O-O
indicates the central axis of the classifier 10, and the center of the classifier 14 is arranged so as to coincide with the central axis OO. Furthermore, an inductor 1 is placed in the center of the classification body 14 so as to coincide with the central axis O-O.
8 is movably provided, and a flow path consisting of an annular region 21 with a narrow gap is formed between it and the inner surface of the classification surface 16, and by moving the inductor 18 on the central axis O-O, The gap between the regions 20 is made variable, and the airflow from the inlet region 12 passes through the narrow annular region 21 to form a laminar annular flow 23. Reference numeral 20 indicates a flow dividing means, which is provided below the classifier 14, and a flow divider 200 is provided at the end of the flow divider 20 on the classifier 14 side.
is fixed, and the gap between the classification surface 16 and the flow dividing material 200 is made variable by moving the flow dividing means 20 in the direction of the central axis OO using the adjustment tool 22. Classification surface 14 which is the surface of classification body 14
Above, a wall flow 24 following the annular flow 23 forms a classification surface 16.
The flow dividing material 200 is inserted so as to flow along the wall surface flow 24 and divide the layer thickness of the wall flow 24.
The inner edge flow 2 flowing close to the classification surface 16 due to
5 and an outer edge flow 26 that flows remotely to the classification surface 16. The flow dividing material 200 is particularly shaped and positioned so as not to disturb the above-mentioned airflow.

The flow dividing means 20 is provided with fine powder discharge ports 30 at two locations, for example, through a conductor plate 28 in order to guide the inner edge flow 25 on the outer circumference, and the outer edge flow is provided in the direction of the central axis O-O of the flow dividing means 20. A coarse powder outlet 38 is provided for guiding the powder 26. 32 is a casing of the classifier 10, which is provided with a seat 33 on the upper part for supporting the classifier 14, and furthermore, the classifier 14 is slightly moved along the central axis O-O by an adjusting tool 34.
Airflow flow can be adjusted.

In the above embodiment, the fine powder is supplied from the inflow region 12 as an airflow containing particles together with the airflow, and is sufficiently dispersed to be in a state suitable for classification.
A wall flow 24 following the annular flow 23 that has passed through the narrow annular region 21 flows along the surface of the classification surface 16 to form a flow due to the Coanda effect. Further, the inner edge flow 25 separated by the flow dividing material of the flow dividing means is guided to the fine powder discharge port 30 with fine powder floating and accompanying it, and the outer edge flow 26 causes the coarse powder to change to coarse powder corresponding to the speed of the air flow. The inertial force based on the speed acts as an operating force and is guided to the coarse powder discharge port 38 in the direction of the central axis O-O, where it is collected by a collection device (not shown) and the fine powder is classified. .

As described above, by dividing the wall flow that adheres to the surface of the classification surface of the classification body into the inner edge flow and the outer edge flow, the inner edge flow and the outer edge flow are transferred to the fine powder side without turbulence of the airflow. Since the gas is guided to the discharge port and the coarse powder side discharge port, gas is reliably attached to the surface of the classifier due to the Coanda effect, and the classification characteristics due to the Coanda effect can be fully utilized. The classification performance including the classification accuracy can be significantly improved.

Note that the annular region 21 and the classification surface 16 are configured with a three-dimensional space, and in order to increase the throughput of the classifier, the thickness of the flow paths of the annular flow 23 and wall flow 24 must be increased. Therefore, it is possible to suppress the occurrence of turbulence in the airflow and scale up to increase the processing capacity.

FIG. 2 shows details of the flow dividing means 20 in FIG. 1, and only the main parts will be explained.

FIG. 2a uses the fluid dividing section 200 of FIG. 1, and is made of an annular plate.

FIG. 2b uses a fluid divider 210, which is made of an annular curved plate.

FIG. 2c uses a fluid divider 220, which is composed of an annular wedge plate.

In FIG. 2d, the dividing fluid 230 is integrated with the dividing means 20 and has an annular shape.

In FIGS. 2b to 2d, the same reference numerals as in FIG. 2a will not be repeatedly described.

In Figure 2a, 16 indicates the classification surface, and c
is the center of the classification surface 16. f is the tip position of the flow dividing material 200, and the straight line V-V is a straight line passing through the classification surface center c and the tip position f. Further, d indicates a point on the classification plane 16. For the straight line V-V, the straight line H
-H is a straight line orthogonal at the tip position f,
The tip position f of the flow dividing material 200 is placed at a position with a gap e from the classification surface 16 on the straight line VV. Further, the flow dividing material 200 has a surface consisting of an inner surface angle θ ₁ and an outer surface angle θ ₂ with respect to the straight line H-H,
These are arranged in such a posture that 0°≦θ ₁ and θ ₂ ≦90°.

The surface of the flow dividing material 200 on the inner surface angle θ ₁ side is a wall flow 24
The surface on the side of the outer surface angle θ ₂ is in contact with the inner edge flow 25 branched from the wall flow 24
6, respectively. In this way, when dividing the wall flow 24, it is possible to prevent the above-mentioned airflow from being disturbed by the shape, posture, and arrangement of the divided flow.

In addition, the straight line V-V is shown as a vertical line passing through the point d on the classification surface 16, but the point d is on the classification surface 1.
It can even include any and all points where 6 exists.

Note that the embodiments of the present invention are not limited to the above-mentioned embodiments, and many embodiments such as a classifier, an adjusting means, a flow dividing means, etc. can be used.

[Effects of the Invention] As is clear from the above examples, the present invention improves the classification characteristics due to the Coanda effect by guiding each airflow to the coarse powder side and the fine powder side without turbulence of the airflow on the surface of the classifier. It has many practical effects, such as being able to make full use of the particles, significantly improving the classification performance of the fine powder classifier, and increasing the throughput of the classifier.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a fine powder classification apparatus according to an embodiment of the present invention, and FIG. 2 is a detailed explanatory diagram of a flow dividing means of the apparatus. 10...Classifier, 12...Inflow area, 14...
Classifier, 20... Diversion means, 21... Annular region, 2
3... Annular flow, 24... Wall flow, 25... Inner edge flow, 26... Outer edge flow, 30... Fine powder outlet, 38
...Coarse powder outlet.

Claims (1)

[Claims] 1. An inflow region for an air flow containing particles, an annular classification body having an annular region in the center following the inflow region and having an approximately semicircular cross section, and following the annular flow passing through the annular region. a flow dividing means for dividing the wall flow adhering to the surface of the classification body into an inner edge flow and an outer edge flow;
A fine powder characterized by having a fine powder discharge port provided on the outer periphery of the flow dividing means for guiding the inner edge flow, and a coarse powder discharge port provided in the direction of the central axis of the flow dividing means for guiding the outer edge flow. classification device.