JPH0326103B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a vertical pulverizer that pulverizes cement raw materials, coal, chemicals, etc. through cooperation between a rotating table and pulverizing rollers.

[Prior Art] Vertical pulverizers equipped with a rotary table and pulverizing rollers are widely used as a type of pulverizer for finely pulverizing fluids such as cement raw materials, coal, and chemicals into powder. This type of crusher has a disc-shaped rotary table that rotates at low speed driven by a motor with a speed reducer in the lower part of a cylindrical casing, and pressure compressors using hydraulic pressure etc. at points that equally divide the outer periphery of the upper surface in the circumferential direction. It is equipped with a plurality of rollers that are driven and rotated.

For example, in FIG. 6, which shows a conventional vertical crusher, the crusher, which is designated as a whole by reference numeral 1, is visually formed as a single tower, with an electric motor 2 and a speed reducer 17 at its base. A rotary table 3 to be rotated is arranged. A plurality of conical crushing rollers 4 are arranged to rotate in sliding contact with the rotary table 3, and the crushing rollers 4 are rotatably supported on a support arm 5. The support arm 5 is fixed to a support shaft 6 rotatably supported on the crusher side. This support shaft 6
Furthermore, one end of a rotating arm 7 is fixed, and this rotating arm 7 extends downwardly through the side of a casing 8 surrounding the rotary table 3, and faces the lower space of the crusher. The lower end of the rotary arm 7 is rotatably supported on the tip of a rod 10 of a pressure cylinder 9 whose lower end is rotatably supported on the base of the crusher 1.

The fluid as a raw material supplied to the center of the rotary table 3 through a supply pipe (not shown) is caught between the driven roller 4 and the rotary table 3 by rotation of the table, and is pulverized. On the other hand, hot air is guided into the casing 8 by a duct (not shown), and this hot air flows into the annular space 14 between the rotary table 3, the outer peripheral surface, and the inner peripheral surface of the casing 8.
As a result, the fine powder rises inside the crusher 1 while being dried, and is discharged from the discharge pipe 16 as a mixture with hot air and sent to the next process.

Note that some of the coarse particles also rise within the crusher 1, but are classified by the rotating blades 15 of the upper separator and returned onto the rotating table 3.

One type of separator that is widely used is a rotary separator, in which a rotating shaft 13 is provided in the classification section, and rotating blades 15
are fixed to the rotating shaft 13 at equal pitches, and are rotated together with the shaft at an arbitrary number of rotations.

FIG. 7 is a horizontal sectional view showing a schematic arrangement of the blades 15 of the rotary separator.
has a substantially L-shaped cross-section, and is arranged in an annular and radial manner so that the L-shaped bent portion is located inside the separator.

As the blades 15 rotate together with the rotating shaft 13, fine particles are separated from the airflow that passes between the blades 15 and flows into the separator.The principle of this classification will be outlined with reference to FIG. .

In Fig. 8, when the rotating blade is rotating counterclockwise at a constant rotation speed (rotational speed V), particles flowing from an arbitrary point P on the arc CD formed by the outer diameter end of the rotating blade are The separator moves along an arbitrary trajectory according to the particle size, receiving the combined forces of the resistance force (inward flow) caused by the airflow, the centrifugal force (outward force), and the influence of the air layer between adjacent rotating blades. Head inside. In other words, fine powder with a small particle size draws a trajectory a ₁ and passes between A and E, intermediate powder draws a trajectory a ₃ between A and B, coarse powder draws a trajectory a ₅ between B and C, and rotates. It reaches the inner wall of the blade 15.

The particles that come into contact between B and C do not lose their kinetic energy, and are then ejected radially outward along between B and C due to the action of centrifugal force.

On the other hand, among the intermediate particles that have arrived between A and B, those that move outward due to centrifugal force escape along the BC wall to the outside of the separator in the same way as the particles that abutted between B and C above. However, if the inward force due to the airflow balances with the centrifugal force between A and B, or if the inward force exceeds the centrifugal force, the particles fall along the line between A and B and are returned below the separator.

As shown in FIG. 6, the conventional rotary separator has a shape in which the diameter increases toward the top. In this case, since each rotating blade rotates integrally, the rotational circumferential speed of the rotating blade increases as it moves upward. Further, since the airflow rising inside the casing sequentially passes between the rotating blades starting from the lower part of the separator, the remaining airflow passes between the rotating blades as the separator moves upward. In other words, the amount of air passing through the separator becomes smaller as it goes above the separator, and therefore the flow velocity of the air flow also becomes smaller as it moves above the separator.

[Problems to be solved by the invention] In the rotary separator configured as described above, the inflow air volume, inflow velocity, particle size distribution of the dust-containing airflow passing between the rotary blades, and the separator's Even if the rotational speed is constant and does not change, the slope of the classification point of the classification performance characteristic curve is gentle as shown in FIG. 4, and the classification accuracy, in other words, the sharpness of classification, is not so great. That is, a large amount of coarse powder is mixed into the fine powder, and a considerable amount of fine powder is mixed into the returned powder.

Therefore, the quality of the fine powder is low, and the poor classification accuracy causes negative effects such as a decrease in the crushing capacity of the crusher and an increase in running costs.

In addition, in FIG. 4 and FIG. 5, which will be described later, the horizontal axis is the particle diameter, and the vertical axis is the distribution ratio (partial classification efficiency), which shows the ratio of amounts of returned powder to incoming powder for a certain particle size D.

[Means for Solving the Problems] The present invention provides a vertical crusher equipped with a rotary separator in the upper part of the casing, in which the diameter of the rotary separator is made smaller in the upper part, and the diameter of the rotary separator is made smaller in the upper part, and A circumferential extension is provided on the edge,
The spacing between the leading edges is smaller than the spacing between the trailing edges.

[Function] In a rotary separator, an increase in the rotational speed of the separator and a decrease in the airflow velocity when passing between the blades of the separator are factors that reduce the classification point (particle size). Acts as. On the other hand, a decrease in the rotational circumferential speed of the separator and an increase in the airflow velocity act as factors that increase the diameter of the classification point.

However, in the conventional vertical crusher, the sixth
As shown in the figure, the rotary separator has a shape that expands upward. In such a rotary separator, the particle size at the classification point rapidly shifts toward the smaller diameter side as the particle size at the classification point increases as the rotation peripheral speed increases and the airflow velocity decreases. Conversely, the classification point is located on the larger diameter side in the lower part of the separator, and the classification point is located in the smaller diameter side as it moves upward.

Therefore, when looking at the separator as a whole, the classification points are distributed over a wide range,
Classification had to be slow.

In contrast, in the present invention, the rotary separator has a smaller diameter toward the top.

Therefore, the rotational circumferential speed becomes smaller toward the top, and the factor that increases the diameter of the classification point caused by this is
Offsetting the factor of reducing the size of the classification point due to the decrease in airflow velocity,
As a whole, the classification points of the upper and lower portions of the separator are approximately the same, so that sharp classification is achieved. Furthermore, sharp classification can also be achieved by making the leading edge of the rotary blade narrower than the trailing edge.

[Example] Examples will be described below with reference to the drawings.

FIG. 1 is a side view showing a schematic configuration of a rotary separator used in a separator according to an embodiment of the present invention, and FIG. 2 is a partially enlarged horizontal cross-sectional view of the separator.

As shown in FIG. 1, in the present invention, the rotary separator has a configuration in which the diameter becomes smaller toward the top. In addition, in this embodiment, as shown in FIG. 2, each rotary blade 15 has an L-shaped cross section, and has one or both of the leading edge and the trailing edge (Figure a shows only the trailing edge, b,
Pockets (circumferentially extending portions) 15a and 15c are provided on both the leading edge and the trailing edge (in Figure c), and the blade spacing on the front edge side is set smaller than the blade spacing on the trailing edge side. .

The overall configuration of a vertical crusher incorporating such a separator is the same as that shown in FIG. 6 above, so a description thereof will be omitted.

The classification effect of the separators shown in FIGS. 1 and 2 will be explained.

First, the effect of configuring the rotating separator so that the diameter becomes smaller in the upper part will be explained.

In this case, as mentioned above, the higher the separator, the
The circumferential rotational speed decreases, which acts as a factor that increases the diameter of the classification point. Furthermore, the higher the position, the lower the velocity of the airflow passing between the rotating blades, which acts as a factor that reduces the diameter of the classification point. In the present invention, these contradictory effects cancel each other out, and even when reaching the upper part, the classification point is almost the same as the lower part of the separator, and the separator as a whole can perform sharp classification.

Next, the functions of the pockets 15a and 15c will be explained with reference to FIG.

In FIG. 9, particles P have flowed at a predetermined speed between the rotating blades 15 of the separator.
is subjected to an inward force due to the inward airflow, a centrifugal force caused by the rotation of the gas confined between the rotating blades, and an apparent force in the opposite direction of rotation in the circumferential direction caused by the rotation of the rotating blades. And in Figure 9,
Particles of any particle size that have passed through point P draw trajectories such as b ₁ , b ₂ , and b ₃ depending on the particle size. That is,
The fine powder b ₁ passes through the separator, and the coarse powder hits the rotating blades as shown in b ₂ and b ₃ , and then enters the pocket 15a at the inner diameter end of the rotating blade and the pocket 15c at the outer diameter part.
After that, it slides downward or falls freely due to its own weight, and is returned to the rotary table. By providing the pockets 15a and 15c in this way, the particles accommodated in these pockets are prevented from being agitated by the airflow and scattered again, and classification with a sharp classification curve is possible. be.

Incidentally, in the rotary blades with a simple L-shaped cross-section shown in Figures 7 and 8, the particle group falling along the area between A and B is constantly exposed to the inward airflow and is likely to be re-dispersed. . Furthermore, the particles returned to the outside of the separator from between BC can also be carried by the airflow again and flow into the separator.

Due to the above-mentioned phenomenon, particles that should normally be classified as coarse particles are mixed in fine particles, resulting in the classification characteristics shown in Figure 4, where the gradient near the classification point is gentle and the classification accuracy (classification (relaxation) decreases.

In contrast, in this embodiment, pockets 15a, 15c are provided on one or both edges of the rotating blade.
A pocket 15 is provided to collect the coarse powder that has reached the rotating blade.
a, 15c and reliably returns it to the crushing section.

In other words, among the particles starting from point P in Fig. 9, fine powder traces a trajectory b ₁ toward the fine powder side, and particles with a larger particle size follow a trajectory b ₂ or b ₃ and hit the rotating blade. After contacting the powder, it slides down the pocket 15a, corner B, pocket 15c, etc., and becomes returned powder. Further, there is no re-scattering during this fall, and even sharper classification is performed.

Next, the effect of narrowing the leading edge side of the rotating blade will be explained.

The above particle trajectory is obtained when the incident position of the particle on the separator is an arbitrary point P. Then,
When the particle is incident closer to point D than point P shown in FIG. 8 (when point P moves to the left), the particle size range that passes between EA becomes wider and the fine powder becomes coarser. Conversely, if point P is on the right side and closer to point C, the fine powder becomes finer. Therefore, by narrowing the interval on the leading edge side, the particle size range that passes between the blades 15 is reduced, and even sharper classification becomes possible.

The separator of this example improves classification efficiency by making the diameter of the separator smaller toward the top, as well as improving classification efficiency by pocketing and narrowing the leading edge side, as described above. This allows for extremely sharp classification.

Note that the configuration shown in FIG. 2a is simple and extremely easy to implement. However, in this case, pressure loss may increase due to the orifice effect. On the other hand, the pressure loss can be reduced by gradually widening the interval toward the trailing edge as shown in Figure b or Figure C. Also c
In the case shown in the figure, it is easy to manufacture by combining a perforated pipe and an angle.

Furthermore, as a countermeasure to the above-mentioned fluctuation in the classified particle diameter due to the difference in the incident position between the rotary blades at the entrance of the separator, it is possible to increase the number of blades and reduce the arc length of one pitch of the circumference. In the present invention, an excellent classification effect can be obtained without increasing the number of blades.

Furthermore, in the present invention, as shown in FIG.
The opening angle of the L-shaped corner of the rotating blade 15 is
It may be 90° or more. In this case, compared to the rotating blade shown in Fig. 1, for example, the particles on the trajectory _b2 move more easily to the pocket 15a, and the number of particles that inevitably fall near the corner B is reduced, and there is no chance of re-scattering. Further decrease.

[Effects of the Invention] As described above, according to the present invention, the classification accuracy of the rotary separator is improved, the incorporation of coarse powder into fine powder is suppressed to a minimum, and a product with a sharply polarized particle size structure can be obtained. This improves product quality.
In addition, improved classification accuracy increases crushing capacity,
Running costs can also be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of a separator showing one embodiment of the present invention, FIG. 2 is a partially enlarged horizontal cross-sectional view of a rotating blade, and FIG. 3 is a rotating blade showing another embodiment of the present invention. FIGS. 4 and 5 are diagrams showing classification characteristics of fine powder in the conventional method and in the present invention. 6 to 8 relate to a conventional example, in which FIG. 6 is a schematic vertical sectional view, FIG. 7 is a sectional view, and FIG. 8 is a partially enlarged view of FIG. 7. Moreover, FIG. 9 is an explanatory diagram of the classification action. 3...Rotary table, 4...Crushing roller, 15
... Separator rotating vane, 16 ... Discharge pipe, 15
a, 15c...pocket, a ₁ , a ₂ , a ₃ , a ₄ , a ₅ ,
b ₁ , b ₂ , b ₃ ...Particle trajectory, P...Particle incident position.

Claims (1)

[Claims] 1. The top of the casing is provided with an opening for the air flow of refined powder, and a separator is installed in the upper part of the casing. In a vertical crusher that is a rotary separator supported by the rotating shaft and having rotating blades having a substantially L-shaped horizontal cross section and arranged annularly and radially around the rotating shaft, The diameter of the rotary separator is gradually reduced upward, and a circumferentially extending portion is provided on the leading edge side of adjacent rotating blades, and the interval between the leading edges is made smaller than the interval between the trailing edges. Vertical crusher with special features.