JPH0314514B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a classification device for separating powder raw materials into coarse powder and fine powder.

[Conventional technology]

BACKGROUND ART Conventionally, a classification apparatus has been generally used that carries powder raw materials such as cement in an air stream, applies centrifugal force and centripetal force simultaneously, and sorts the powder raw materials in a desired particle size range. In such a powder raw material classification device, the powder raw material introduced from the raw material introduction section provided below the classification section is generally subjected to centrifugal force in the classification section, which is made up of a rotating body equipped with a plurality of classification blades. The coarse powder is discharged toward the outer circumference, and the fine powder is collected by the centripetal force caused by the drag force of the air flow discharged to the outside of the machine via the classification blades.
The powder raw material is separated and sorted into fine powder and coarse powder, and the fine powder is sent to the next process from a fine powder discharge section provided above the classification section.

[Problems with conventional technology]

However, in such conventional powder raw material classification equipment, the centrifugal force in the classification zone is stronger than the centripetal force, and the coarse particles released in the outer circumferential direction and the upward air flow dispersed in the crushing process in the previous stage The powder raw materials riding on the rotor repeatedly collide and mix on the outer periphery of the rotor, and the dust concentration on the outer periphery of the rotor increases markedly, and in some cases, the powder raw materials may re-agglomerate. Furthermore, since centrifugal force and centripetal force act continuously on the powder raw material inside the rotating body, particles with a particle size that balances centrifugal force and centripetal force become stagnant inside the rotating body. . Therefore, the dust concentration inside the rotating body increases and the powder raw material re-agglomerates, while the powder raw material tends to adhere to the classification blades. As a result, fine powder particles attached to coarse powder particles may be mixed into the coarse powder, or coarse powder particles may be mixed into the fine powder.
In particular, when the powder raw material is a fine powder on the order of several μm, there is a drawback that highly accurate classification cannot be performed. Furthermore, it also has the disadvantage that the power for rotating the rotating body and the power for the exhaust fan for discharging the fine powder to the outside of the machine are wasted.

Therefore, a technical object of the present invention is to provide a powder raw material classification apparatus that can perform classification with high precision and efficiency even in a classification range of several μm.

[Technical means for solving the above problems]

In order to solve this technical problem, in the present invention, the above-mentioned classification section is provided with a plurality of holes of a predetermined diameter,
A classifier having a plurality of disc-shaped rectifier plates arranged at predetermined intervals in the vertical direction and a plurality of classification blades provided radially in the circumferential direction from the center of rotation between the respective rectifier plates; Below the classification impeller, a raw material introduction pipe is provided that opens directly below the hole formed in the rectifier plate, while the classification section is isolated from and surrounded by the raw material introduction section, except for the raw material introduction pipe opening. It is equipped with a coarse powder collection and discharge section.

[Effect]

Therefore, in the powder raw material classification device according to the present invention, centrifugal force and centripetal force act on the powder raw material introduced into the classification section between the rectifying plates that constitute the classification section, and the coarse powder is The fine powder is discharged toward the outer periphery of the classification section by centrifugal force, and flows from the coarse powder collection/discharge section that surrounds the classification section to the coarse powder discharge port without mixing with the supplied powder raw material. The fine powder is directed from a gap provided at the center of rotation to the fine powder discharge port.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

As shown in FIG. 1, the powder raw material classification device 1 according to the present embodiment includes a classification section 2, and a material introduction section 3 with a truncated conical cross section provided below the classification section 2. , and a fine powder discharge section 4 provided above the classification section 2. And the above classification section 2
The classifier 20 is composed of a large fan formed into a substantially short cylindrical shape. In this embodiment, this classifier 20 is shown in FIGS.
As shown in FIGS. 3 and 4, four disc-shaped current plates 5, 6, 7, and 8 are arranged at predetermined equal intervals in the vertical direction; ,7,
8 and a plurality of classification blades 9 provided radially in the circumferential direction from the rotation center and attached at a predetermined angle in the counter-rotation direction. and,
Circular holes 10, 11, and 12 having different diameters are formed in the current plates 5, 6, 7, and 8, respectively.
As shown in FIGS. 3 and 4, these holes 10, 11, and 12 have the largest diameter in the hole 10 opened in the lowermost rectifying plate 5, and in the lower middle rectifying plate 6. The hole 11 opened in is of medium diameter,
The holes 12 of the upper middle rectifying plate 7 are formed to have a small diameter, and as shown in FIG. 2, no holes are formed in the uppermost rectifying plate 8. Further, a cylindrical cavity 13 is formed in the rotational center of the classifier 20, and a fine powder discharge part 4 is provided above the cavity 13. On the other hand, the coarse powder collecting and discharging section 14 is provided surrounding the classification section 2, and this coarse powder collecting and discharging section 14 consists of a cone section 15 and a pipe section 16 provided in the raw material introduction section 3, A coarse powder outlet 17 provided at the end of the pipe portion 16
is airlocked by a rotary valve 18. In addition, the cone section 15 below the classifier 20 is provided with the same number of raw material introduction pipes 19 as the holes 10 of the lowermost straightening plate, and these raw material introduction pipes 19 are connected to the plurality of holes 10. These raw material introduction pipes 19 are formed to open directly below, and connect between the raw material introduction section 3 and the classification section 2.

The coarse powder collecting and discharging section 14 is formed so as to surround the classifying section 2 separated from the raw material introducing section 3 by the cone section 15 and the pipe section 16, except for the raw material introducing pipe opening 25.

In the figure, reference numeral 21 is a motor that rotationally drives the classifier 20, and 22 is a shaft that transmits the driving force of the motor to the classifier 20. Although not shown, a raw material supply device such as an ejector is connected to the raw material introduction port 23 opened below the raw material introduction part 3, and supplies the raw material powder into the raw material introduction part 3 on an air flow. It is. Further, a windmill (not shown) is connected to the fine powder discharge hole 24 at the tip of the fine powder discharge portion 4 via a collector such as a bag filter.

Therefore, in the powder raw material classification device according to the present embodiment, the raw material powder 2 supplied with the airflow into the raw material introduction section 3 by the raw material supply device such as the ejector
6 is introduced into the classifier 20 via the raw material introduction pipe 19 and the hole 10 formed in the rectifier plate 5. In this case, the powder raw material 26 is subjected to centrifugal force within the classifier 20 due to the rotation of the classifier 20 (force acting in the direction indicated by the two-dot chain line in FIG. 1),
A centripetal force (a force acting in the direction indicated by the dashed line in FIG. 1) is exerted by the airflow toward the center of the classifier 20.
Therefore, the fine particles on which the centripetal force acts more strongly are sucked into the center of the classifier 20 together with the airflow, as shown by the solid line in FIG. It is collected separately from gas by a collector not shown.

On the other hand, coarse particles on which the centrifugal force acts more strongly are discharged toward the outer periphery of the classifier 20, as shown by the broken line in FIG. Then, it slides down the pipe section 16 and is discharged from the coarse powder outlet 17 to the outside of the apparatus.
In this case, the upward airflow containing the coarse powder particles and powder raw materials discharged to the outside of the classifier 20 is the cone portion 1
5 and the pipe section 16,
Unlike the conventional method, the coarse powder particles and the powder raw material do not repeatedly collide and mix. In addition, in the powder raw material classification device 1 according to the present embodiment, the raw material is intermittently supplied to the classifier 20 through the raw material introduction pipe 19 and the plurality of holes 10 formed in the current plate 5. Therefore, unlike the conventional case, the airflow sucked toward the center of the classifier 20 is also intermittent. Therefore, although centrifugal force is always acting on the powder raw material in the classifier 20, there is no particle size range in the classifier 20 where the centrifugal force and the centripetal force are balanced.

〔Effect of the invention〕

In the present invention, the coarse powder particles separated by the classifier and the supplied powder raw material do not mix, and unlike the conventional classifier, the particle size range where centrifugal force and centripetal force are balanced is achieved. Since these particles no longer exist, it is possible to prevent an increase in the dust concentration in the outer periphery of the classifier and the re-agglomeration of the powder raw material, and it is also possible to prevent the powder raw material from adhering to the classification blades. Therefore, in the powder raw material classification apparatus according to the present invention, even classification in a classification range of several μm can be performed with high precision and efficiency.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the powder raw material classification device according to the present invention, Fig. 2 is a sectional view taken along the line - - of Fig. 1 at the position of the upper rectifying plate, and Fig. 3 is a sectional view showing the middle rectifying plate. 1, and FIG. 4 is a sectional view taken along the line - 1 in FIG. 1 at the position of the lower rectifier plate. 1... Powder raw material classification device, 2... Classification section, 3
...raw material introduction section, 4...fine powder discharge section, 5, 6,
7, 8... Current plate, 9... Classifying blade, 10, 1
1, 12... Hole section, 14... Coarse powder collection and discharge section, 1
9... Raw material introduction pipe, 20... Classifier, 25...
...raw material introduction pipe opening.

Claims (1)

[Claims] 1 Comprising a classification section, a raw material introduction section provided below the classification section, a fine powder discharge section provided above the classification section, and a rotation drive section that drives a rotating body provided in the classification section. In a powder raw material classification device that separates powder raw materials into coarse powder and fine powder, the classification section is formed by a plurality of disc-shaped holes having a plurality of predetermined diameters and arranged at predetermined intervals in the vertical direction. The classifier has a current plate and a plurality of classification blades provided radially in the circumferential direction from the center of rotation between each current plate, and below the classifier there are holes formed in the current plate. A raw material introduction pipe that opens directly below the raw material introduction pipe is provided, and a coarse powder collection and discharge part that surrounds and isolates the classification part from the raw material introduction part except for the opening of the raw material introduction pipe is provided. Classifying device.