JPH0751629A - Classifier for vertical roller mill - Google Patents

Abstract

PURPOSE:To keep the accuracy of classification high and to effectively produce products stable in particle size in a classifier for a vertical roller mill for pulverizing coal, limestone, etc. CONSTITUTION:To the outer peripheral end part of upper support plates 9a of classifying blades 10, of a rotary classifier incorporated in an inner cone 5, plural auxiliary classifying blades 11 which are shorter than the classifying blades 10 are fitted. A crushed material 3 which does not receive turning force classifying action of turning vanes 6 of the inner cone 5 and advances straight from the inlet of the inner cone 5 is classified by the auxiliary classifying blades 11 into coarse powder 7a and fine powder 7b. The fine powder 7b is further reclassified by the classifying blades 10 supported by the upper support plates 9a and lower support plates 9b into very fine powder 7c and coarse particles 7d.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical roller mill or a dry tube mill classifying device for finely pulverizing coal, limestone or the like.

[0002]

2. Description of the Related Art FIG. 8 is a vertical sectional side view showing an example of a conventional vertical roller mill classifying device, and FIG. 9 is a horizontal sectional view taken along line IX-IX of FIG. Raw material (2) supplied from raw material supply pipe (1)
Is crushed by a crushing device (not shown) below the vertical roller mill, and the crushed material (3) rises in the mill casing (4) by carrier air (not shown), and the mill casing (4)
Enter the inside of the inner cone (5) built inside. This inner cone (5) is a type of cyclone,
The swirl vanes (6) attached to the inlet of the swirl vane (6) classify the pulverized product (3) into coarse powder (7a) and fine powder (7b). The fine powder (7b) is further mixed in the inner cone (5) with the upper support plate (9a) and the lower support plate (9).
by a rotary classifier comprising a plurality of classifying blades (10) supported on b) and rotating around a drive shaft (8),
The product is classified into a fine powder (7c) and a coarse particle (7d) discharged out of the mill. Coarse powder (7a) and coarse particles (7
With d), the inner wall of the inner cone (5) is dropped and re-crushed by a crusher (not shown) below the vertical roller mill.

[0003]

[Problems to be Solved by the Invention] Mill casing (4)
The pulverized material (3) rising in the inside is classified by the revolving vane (6) of the inner cone (5) to give a revolving force, and a part of the pulverized material (3) is revolved. Since it goes straight without receiving the classification of (6) and concentrates on the upper part of the classification blade (10) and collides, the imbalance of the concentration in the classification region becomes large, and the classification efficiency of the rotary classification device deteriorates. , Could not provide an efficient vertical roller mill. Further, there were coarse particles that short-passed through the gap between the upper support plate (9a) and the ceiling of the mill casing (4), which also deteriorated the classification efficiency.

[0004]

In order to solve the above-mentioned conventional problems, the present invention provides a plurality of classification blades rotating around a vertical axis inside an inner cone provided in a casing of a vertical roller mill. In the classifying device provided, a plurality of auxiliary classifying blades, which rotate integrally with the classifying blades, are provided outside the upper part of the classifying blades; and a classifying device for a vertical roller mill; and an upper part inside a casing of the vertical roller mill. In a classifying device having a plurality of classifying blades that rotate around a vertical axis, an annular protrusion that prevents radial flow in the gap between the upper surface of the upper support plate that supports the upper ends of the classifying blades and the ceiling of the mill casing. The present invention proposes a vertical roller mill classifying device characterized in that it is provided with means for ejecting sealing air into the gap.

[0005]

In the first means for solving the problems, the crushed material which goes straight from the inlet of the inner cone without being subjected to the turning force (classification effect) of the swirling vane of the inner cone is attached to the outside of the upper part of the classifying blade for classification. The auxiliary classifying blade that rotates integrally with the blade classifies the powder into coarse powder and fine powder, and the fine powder is reclassified by the inner classification blade. In this way, most of the pulverized material that is not subjected to the classification action by the swirl vanes of the inner cone can be classified by the auxiliary classification blade, and an efficient classification device can be provided.

Further, in the second means for solving the problems, the annular flow provided in the gap between the upper surface of the upper support plate and the ceiling of the mill casing prevents the radial flow, and the sealing air is jetted into this gap. By doing so, an effective air curtain is formed, so that short paths of coarse particles can be prevented.

[0007]

[First Embodiment] FIG. 1 is a vertical sectional side view showing a first embodiment of the present invention, FIG. 2 is a horizontal sectional view taken along line II-II of FIG. 1, and FIG. 3 is a perspective view showing a main portion. In these figures, the same parts as those of the conventional one described with reference to FIGS. 8 and 9 are given the same reference numerals to avoid redundancy, and detailed description thereof is omitted.

In this embodiment, the upper support plate (9) supporting the upper ends of the classifying blades (10) of the rotary classifier.
A plurality of auxiliary classification blades (11) are attached to the outer peripheral end of a), that is, outside the upper portion of the classification blade (10).
These auxiliary classifying blades (11) have a length of about 1/4 and a width, thickness and pitch substantially the same as those of the classifying blades (10). The attachment angle of the auxiliary classification blade (11) is the same as that of the classification blade (10) in terms of the inclination angle from the vertical direction (α in FIG. 1) and the inclination angle from the radial direction (β in FIG. 2). Further, it is inclined by about 30 degrees (γ in FIG. 3) from the vertical direction toward the rotation direction.

The crushed material (3) which has flowed in from the inlet of the inner cone (5) and has proceeded straight without being subjected to the swirling force of the swirling vanes (6) has an auxiliary classification blade () rotating around the drive shaft (8). 11) The coarse powder (7a) and the fine powder (7b) are classified, and the fine powder (7b) is further classified by the classifying blade (10) into the refined powder (7c) and the coarse particles (7d) which are the products. .

Since the auxiliary classification blade (11) is inclined about 30 degrees from the vertical direction toward the rotation direction, the particles colliding with the auxiliary classification blade (11) are slanted downward. Therefore, there is little interference with the pulverized material (3) flowing from the inlet of the inner cone (5), and efficient classification can be performed.

FIG. 4 is a diagram showing an example of the result of a comparative test of classification performance. This figure shows the refined flour (7
In c), the relationship between the weight percentage passing through the 200 mesh sieve [%] and the weight ratio on the 100 mesh sieve (based on the time when the weight passing through the 200 mesh sieve is 70%) [-] is shown. In the present embodiment, the weight on the 100-mesh sieve, which is an objective index, is reduced to about 1/2 of the conventional value, indicating that the present invention can provide an excellent classifying device.

The angle (γ in FIG. 3) at which the auxiliary classifying blade (11) is inclined from the vertical direction toward the rotation direction is about 30 degrees in the above embodiment, but this angle is practically 30 degrees.
It is effective in the range of 60 to 60 degrees. If it is less than 30 degrees or more than 60 degrees, the separation performance is deteriorated.

[0013]

[Second Embodiment] FIG. 5 is a vertical side view showing a second embodiment of the present invention, FIG. 6 is a horizontal sectional view taken along line VI-VI of FIG. 5, and FIG.
It is a II-VII sectional view. In these figures, the same parts as those described above are designated by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, annular projections (particle separating members) (20a), (2) are provided on the upper surface of the upper classifying blade support plate (9a) of the rotary classifier and the ceiling of the mill casing (4).
0b) are mutually provided. In this case, the rotary classifier is attached so that the particle separating member (20a) on the upper support plate (9a) side is located on the inner peripheral side of the particle separating member (20b) on the ceiling side of the mill casing (4). The particle separating member (20b) attached to the ceiling of the mill casing (4) is provided with a plurality of nozzles (21) opening downward. And the air filter (2
3) The compressed air (22) is guided to the particle separating member (20b) through the air flow rate adjusting valve (24) and the air pipe (25). The compressed air (22) passes through the inside of the particle separation member (20b) and is jetted from the nozzle (21) onto the upper surface of the upper support plate (9a) of the rotary classification device body. The inlet (27) through which the compressed air (22) enters the particle separating member (20b) is structured to be tangential to the nozzle.

With the above structure, a substantially uniform flow rate can be obtained for the plurality of nozzles (21). Then, compressed air (2) flows from the nozzle (21) to the upper surface of the upper support plate (9a).
By the operation of injecting 2) and the rotation of the main body of the rotary classifier, a sealing effect is produced and it is possible to prevent coarse particles from entering.

[0016]

According to the present invention, since the short path of coarse particles is eliminated, the classification accuracy of the classifier is maintained at a high level, and a product having a stable particle size can be efficiently manufactured.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a first embodiment of the present invention.

FIG. 2 is a horizontal sectional view taken along the line II-II of FIG.

FIG. 3 is a perspective view showing a main part of the above embodiment.

FIG. 4 is a diagram illustrating the results of a comparative test of the classification performance of the classifying apparatus of the above-described embodiment and the conventional classifying apparatus.

FIG. 5 is a vertical sectional side view showing a second embodiment of the present invention.

6 is a horizontal sectional view taken along the line VI-VI of FIG.

7 is a sectional view taken along line VII-VII of FIG.

FIG. 8 is a vertical cross-sectional side view showing an example of a conventional classification device.

9 is a horizontal sectional view taken along the line IX-IX in FIG.

[Explanation of symbols]

 (1) Raw material supply pipe (2) Raw material (3) Ground material (4) Mill casing (5) Inner cone (6) Swirling vane (7a) Coarse powder (7b) Fine powder (7c) Fine powder (7d) Coarse particles Object (8) Drive shaft (9a) Upper support plate (9b) Lower support plate (10) Classification blade (11) Auxiliary classification blade (12) Discharge pipe (13) Bearings (20a), (20b) Particle separation member (21) ) Air nozzle (22) Compressed air (23) Air filter (24) Compressed air flow rate control valve (25) Air piping (27) Compressed air inlet of particle separation member

Claims (2)

[Claims] 1. A classifying device comprising a plurality of classifying blades rotating around a vertical axis inside an inner cone provided in a casing of a vertical roller mill, wherein the same classifying blades are provided outside the upper part of the classifying blades. A vertical roller mill classifying device having a plurality of auxiliary classifying blades that rotate integrally. 2. A classifying device comprising a plurality of classifying blades rotating around a vertical axis in the upper part of the casing of a vertical roller mill, the upper surface of an upper support plate supporting the upper ends of the classifying blades, and the ceiling of the mill casing. A vertical roller mill classifying device characterized in that an annular projection for preventing a flow in the radial direction is provided in the gap and a means for ejecting sealing air is provided in the gap.