JPH053353B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an air classifier, and in particular, the present invention relates to an air classifier, particularly when the substance to be classified is a combustible or explosive substance.
For example, air classifiers that have a special structure to prevent the substances to be classified from igniting, burning, or exploding in the case of fine powder of organic substances such as coal or minute metal pieces. It is.

Conventional Technology When solid fuel such as coal or coke is charged into a charging pipe, it falls onto a rigid mill and is pulverized by balls, rollers, or the like.

Coal and the like that have been pulverized into powder rise on the conveying air toward the classification chamber of the air classifier, and are separated into coarse powder and fine powder by rotating classification blades in the classification chamber. Then, the coarse powder falls onto a vertical mill and is pulverized again, and the fine powder is discharged outside the machine through an exhaust pipe.

If the substance to be classified is flammable or explosive, powder ignition or explosion accidents are likely to occur during classification.To prevent these accidents, the classification blades should be Completely eliminate the accumulation of powder on the upper ring plate and bottom plate that are held together, and completely prevent the generation of local high temperature areas due to frictional heat due to direct contact between a part of the rotating body and a part of the fixed part. It is important to prevent

In addition, in order to improve the classification performance, it is necessary that all the substances to be classified that are transported to the classification chamber pass through the classification blades.

Therefore, as shown in FIG. 9, a labyrinth 3 is provided in the gap d between the upper ring plate 1a of the rotating body 1 and the top plate 2a of the casing 2 to seal the gap d.
The dust-containing gas A containing the substance to be classified is prevented from flowing directly into the exhaust pipe 5 without passing through the classification blade 4.

In FIG. 9, reference numeral 6 indicates a hopper fixed to the guide vane 7, reference numeral 8 indicates a charging pipe for charging solid fuel onto the rigid mill, and reference numeral 9 indicates the rotation axis of the rotating body 1.

Problems to be Solved by the Invention In the conventional air classifier, in order to avoid solid contact between the plates 3a and 3b inside the labyrinth, the plates 3a and 3b are
The gap α between a and 3b must be increased to some extent.

However, when the gap α is increased in this manner, the dust-containing gas that enters the gap d flows into the exhaust pipe 5 through the gap α of the labyrinth 3.

That is, a part of the dust-containing gas A does not pass through the classification blade 4, but instead passes through.

Therefore, the classification accuracy deteriorates, and the powder carried by the gas A is inside the labyrinth 3 or
It accumulates at the outlet and does not fall even when the rotating body 1 rotates.

Also, when the dust-containing gas A passes through the rotating body,
A stagnation occurs in the flow of the dust-containing gas at the central lower part 9a of the rotating body 1, and fine powder is deposited there. This fine powder is
Since it is deposited near the center of the rotating body 1, only a small centrifugal force is applied even when the rotating body rotates.

Therefore, the refined powder remains on the bottom plate 1b without being discharged to the outside of the rotating body 1.

If fine powder is deposited in this manner, there is a risk of ignition or explosion, which is a safety problem.

In view of the above circumstances, it is an object of the present invention to allow all of the dust-containing gas flowing into the classification chamber to pass through the classification blades. Another purpose is to prevent powder from accumulating on the top ring plate and bottom plate of the rotating body.

Means for Solving the Problems This invention provides a classification blade provided on the outer periphery of a rotating body protruding into a casing and sandwiched between an upper ring plate and a bottom plate; a classification chamber provided on the outer periphery of the classification blade; A guide vane provided through the casing and fixed to the top plate of the casing; A hopper fixed to the lower end of the guide vane; An exhaust pipe communicating with the classification chamber via the classification blade; Communicating with the classification chamber and the exhaust pipe and a gap formed between the upper ring plate of the rotating body and the top plate of the casing; a protruding blade disposed on the upper ring plate and spaced apart from the top plate of the casing; a bottom plate; The above purpose is achieved by comprising: an inclined plate having a portion inclined at an angle of 40 degrees or more on the upper surface, and whose lower end is located within 1/5 of the diameter of the rotating body from the outer peripheral edge of the bottom plate; This is what we are trying to achieve.

Function When the dust-containing gas containing the powder to be classified passes through the guide vanes, it is directed into a circular orbit approximately concentric with the central axis of the classifier, and is accelerated and begins a rotating motion. Furthermore, it flows into the classification chamber and is classified into fine powder and coarse powder, and the coarse powder falls into the hopper by gravity, while the fine powder is simultaneously classified by the inward flow while swirling on the swirling flow. It passes through the blades, rises inside the rotating body, and flows out into the exhaust pipe.

At this time, some of the powder in the classification chamber tries to flow into the gap between the upper ring plate of the rotating body and the top plate of the casing, but since a fan effect occurs due to the rotation of the protruding blades, The gas inside is given kinetic energy that causes it to flow toward the classification chamber side, that is, the gap entrance side.

Therefore, the gas pressure at the entrance of the gap becomes equal to the gas pressure in the classification chamber, so that powder does not flow into the gap.

Further, even if powder were to flow into the gap, the protruding blades would apply centrifugal force to the powder and scatter it into the classification chamber, so that the powder would not be deposited on the upper ring plate of the rotating body.

Furthermore, the dust-containing gas passing through the rotating body is smoothly changed from a swirling horizontal flow to a swirling vertical flow by the inclined plate, and the gas velocity is designed to prevent powder accumulation on the bottom plate and the inclined plate, as described above. Furthermore, stagnation of the dust-containing gas flow does not occur.

However, when the amount of dust-containing gas decreases and the gas velocity decreases, some of the powder may fall onto the bottom plate and the inclined plate, but even in this case, the present invention prevents the powder from accumulating as follows. is prevented. The inclined plate has a portion that is inclined at an angle of 40 degrees or more with respect to the horizontal, and the centrifugal force effect due to rotation is also large, so powder that falls onto the plate slides down without accumulating on the inclined plate.

A ring-shaped bottom plate is connected to the outer periphery of the lower end of the inclined plate, and the length L in the radial direction of this bottom plate is
The powder is kept within 1/5 of the diameter of the rotating body, and due to the effect of the classification plate as a vertical plate, the powder is given a centrifugal force, scattering around the outer periphery, and not being deposited on the plate. .

This scattered powder is again carried by the dust-containing gas flow within the classification chamber, or falls and enters the crushing mechanism again through the hopper.

Embodiments Embodiments of the present invention will be described with reference to the accompanying drawings, where the same reference numerals have the same names and functions.

A charging pipe 12 is provided protruding from the center of the casing 11, and a ball lace mill 13 is disposed below the charging pipe 12 at a distance sufficient for a worker to enter. A rotating shaft 15 of a rotating body 14 is rotatably fitted into the input tube 12, a lower end of a classification blade 16 is fixed to the outer peripheral edge of a bottom plate 19a of the rotating body 14, and an upper end thereof is fixed to an upper ring plate 19. This classification blade 16
As shown in FIG. 2, a plurality of classification blades 16 are provided at intervals in the circumferential direction, and each classification blade 16 faces in the radial direction.

On the outer periphery of the rotating body 14, via the classification chamber 17,
A guide vane 18 is provided.

A plurality of guide vanes 18 are provided at intervals in the circumferential direction, and since each guide vane 18 is rotatable, the inclination angle can be freely adjusted.

Upper ring plate 19 of rotating body 14 and casing 1
A gap 21 is provided between the top plate 20 of No. 1 and the top plate 20 of No. 1. This upper ring plate 19 has a
As shown in the figure, a plurality of protruding blades 22 are arranged at intervals in the circumferential direction.

The protruding blade 22 has a rectangular shape and faces in the radial direction, but its shape and orientation may be changed as necessary.

A lower end 50 of the inclined plate 50 is provided on the upper surface of the bottom plate 19a.
a is fixed, but the lower end 50a is attached to the bottom plate 1.
It is spaced a distance L from the outer peripheral edge of 9a.

This distance L is selected within 1/5 of the diameter D of the rotating body 14.

Due to the rotation of the rotating body 14, the fine powder deposited on the bottom plate 19a is subjected to a larger centrifugal force as the distance from the rotating shaft 15 increases, that is, the closer it gets to the outer periphery of the rotating body 14. This distance L is set within the range in which the ball is thrown.

Since the upper end of the inclined plate 50 is fixed to the rotating shaft 15, the lower center of the rotating body 14 is connected to the inclined plate 5.
covered by 0.

Therefore, there is no fear of fine powder entering there. Further, it is also possible to omit the portion of the bottom plate covered by the sloped plate, that is, the portion that overlaps with the sloped plate, and to integrate the bottom plate portion having a distance L with the sloped plate.

The inclined plate 50 is inclined by 40 degrees or more with respect to the bottom plate 19a, and the inclination angle θ is appropriately selected from the viewpoint of rectifying the gas and preventing the accumulation of fine powder contained in the gas. For example, the tilt angle θ=
45 degrees is chosen.

An air chamber 23 is formed in the upper part of the casing 11, and this air chamber 23 communicates with the exhaust pipe 24 and the rotating body 14.

The lower end of the guide vane 18 is provided to an inverted conical outer hopper 26 via a support ring 25. Support ring 25 to prevent powder build-up
The upper part 25a of the outer hopper 25a is elongated, for example, the upper part is formed to have a width of 5 mm compared to the lower part of 12 mm.
6 is inclined at 50 to 70 degrees, for example, 60 degrees with respect to the horizontal.

A conical inner hopper 27 is provided at the bottom of the input pipe 12.
An air sealing plate 28 is provided at the lower end of the inner hopper 27 and is in contact with the outer hopper 26.
is jointed at pin 30.

31 is the ball of the ball lace mill 13, 32
shows the rotary disk of the ball lace mill 13, and this rotary disk 32 is designed to allow inspection and repair work.
It is spaced apart enough from the lower end of the outer hopper 26 to allow a worker to enter.

At the bottom of the ball lace mill 13, there is an air inlet 3.
3 is provided, and the conveying air G jetted out from this air inlet 33 flows into the guide vane 18 and the classification chamber 17 via a conveying passage 34 passing through the side of the ball lace mill 13.

The operation of this embodiment will be explained.

The solid fuel M input from the input pipe 12 falls onto the ball race mill 13 and is pulverized. The pulverized powder M is thrown outward from the outer periphery of the rotary disk 32 by centrifugal force.

The conveying air G passing through the conveying passage 34 on the side of the rotary disk 32 carries the powder M, and when it reaches near the top plate 20 of the casing 11, it changes direction horizontally and inward, and when it passes through the guide vanes 18. , is directed in a circular orbit approximately concentric with the central axis of the classifier, and is accelerated and begins a rotating motion.

The circumferential speed of the classification blade 16 is controlled, and the powder M is classified into fine powder M ₁ and coarse powder M ₂ in a classification chamber 17 between the guide vane and the classification blade 16 . That is,
The fine powder M ₁ rotates on the swirling flow and at the same time passes through the classification blade 16 by an inward flow and passes through the inclined plate 50.
While being rectified, the air rises inside the rotating body 14, is carried out from the air chamber 23 above the top plate 20 through the exhaust pipe 24, and is collected by a dust collector (not shown).

If the amount of dust-containing gas decreases and the gas velocity decreases, some of the powder may fall onto the bottom plate and the inclined plate, but even in this case, it is subjected to a large centrifugal force due to the rotation of the rotating body 14, It jumps out from the outer peripheral edge of the bottom plate 19a and falls into the classification chamber 17.

On the other hand, the dust-removed gas is either released into the atmosphere or blown into the combustion chamber as it is.

Since the centrifugal force exerted by the swirling flow is greater than the conveyance force caused by the inward flow, the coarse powder M ₂ falls from the classification chamber 17 due to gravity, flows down along the outer hopper 26, and While pushing aside the plate 28, it falls from the lower end of the outer hopper 26 to the center of the ball lace mill 13, mixes with the new feed, and is re-pulverized.

At this time, while the rotating body 14 is rotating, the protruding blades 22 exert a fan effect, and as shown in FIG. gives the dust-containing gas kinetic energy to cause it to flow toward.

Therefore, the total pressure of the gas at point c (the sum of static pressure and dynamic pressure) is higher than the total pressure at point e, and the design is such that the difference is equal to the total pressure difference between points a and e. As a result, the total pressures at points a and c are balanced, and short passes of dust-containing gas from point a to points c, d, and e are prevented.

Furthermore, even if some of the gas passes through the shot, most of the powder is given centrifugal force by the rotating protruding blades 22 and returned to point c, and then returned to the classification chamber 1.
Fall to 7.

Further, the powder settled on the upper ring plate 19 is similarly applied with centrifugal force, returned to point c, and falls into the classification chamber 17.

The embodiment of the present invention is not limited to the above, but for example, as shown in FIG.
Alternatively, a small protruding blade 16A may be attached to the outside of the upper part of the classification blade 16, and the powder passing through this part and being shot will be shot at a peripheral speed higher than the peripheral speed of the classification blade 16. By applying centrifugal force to blow the powder outward from the blades 16, it is possible to more completely prevent the dust-containing gas from passing through.

In addition, as shown in FIG. 6, the inclined plate 50 is bent in the shape of <, so that the inclination angle β of the lower side 50b with respect to the bottom plate 19a is about 30 degrees, and the upper side 50c of the bottom plate 19 is bent.
The inclination angle γ with respect to a is 40 degrees or more, for example, 60 degrees,
You may also do so. That is, the inclined plate may include a portion of 40 degrees or more. FIGS. 7 and 8 show another example of the inclined plate. That is, when the diameter D of the rotating body 14 is considerably larger than its height, an upper horizontal plate 60 is provided connected to the rotating shaft 15.

In this case, a plurality of protruding rings 61 are provided on the horizontal plate 60 in the radial direction or in a direction with a receding angle, and centrifugal force is applied to the powder falling from the dust-containing gas.
Since it protrudes from the outer periphery of the horizontal plate 60, the plate 60
It does not accumulate on top.

Furthermore, some of the powder that has flown out is carried away again by the dust-containing gas flow, and the rest falls onto the inclined plate.
This will not slide down and accumulate as described above.

Effects of the Invention Since the present invention is configured as described above, it has the following remarkable effects.

(1) Since the projecting blades are installed on the upper ring plate of the rotating body and spaced apart from the top plate of the casing, a fan effect occurs when the rotating body rotates, and the ring plate and the top plate are separated. The gas in the gap between them is given kinetic energy that causes it to flow toward the classification chamber.

Therefore, the gas pressure between the gap inlet and the classification chamber is
Since they are equal, it is possible to prevent gas from the classification chamber side from flowing into the gap.

Therefore, powder does not accumulate on the upper ring plate, and even if gas flows into the gap and the powder settles, the powder will be scattered by the centrifugal force exerted by the protruding blades. , no accumulation occurs.

(2) An incline that has a part inclined at an angle of 40° or more on the top surface of the bottom plate, with the top end fixed to the rotating shaft and the bottom end located within 1/5 of the diameter of the rotating body from the outer periphery of the bottom plate. Since the plate is provided, the dust-containing gas passing through the rotating body is sent to the exhaust pipe while being rectified by this inclined plate.

Therefore, unlike the conventional example, stagnation of the dust-containing gas flow does not occur. If the amount of dust-containing gas decreases and the gas velocity decreases, even if some of the powder falls onto the sloped plate, it will fall along the slope and tend to accumulate on the outer periphery of the bottom plate. is applied with a large centrifugal force generated by the rotation of the rotating body, and flies out from the outer circumference and falls into the classification chamber.

Therefore, there is no possibility that fine powder will accumulate on the bottom plate.

(3) If the lower end of the guide vane is fixed to a tapered guide vane support ring, powder may accumulate in the narrow groove space created by the lower part of the adjacent guide vane and the tip of the support ring. There is no.

(4) The classification blade is equipped with a protruding blade that protrudes into the classification chamber, and centrifugal force is applied to the powder that passes through this part and is about to be shot at a circumferential speed higher than the circumferential speed of the classification blade. The powder is blown out of the classification blades.

Therefore, the shot path of the dust-containing gas can be more completely prevented, and the accumulation of powder on the upper ring plate can be prevented.

(5) If the hopper is 50 to 70 degrees from the horizontal, e.g.
If the hopper is tilted at 60 degrees, powder will not adhere to the inner wall of the hopper.

(6) By providing a conical inner hopper located inside the outer hopper and at the bottom of the input pipe, the total height of the hopper can be significantly lowered than in the conventional example, making it possible to improve the ball lace mill. There is sufficient space for inspection and repair work.

In other words, the hopper needs to have an inclination angle of 50 to 70 degrees with respect to the horizontal in order to avoid powder accumulation inside it, so it is necessary to
If only one is used, the overall height of the hopper will increase due to the sealing at its lower end, and the lower part of the hopper will block the space in the center of the ball lace mill. Therefore, there was not enough space for the above-mentioned inspection and repair, but this problem has been solved by the present invention.

Although the description has been mainly given to a ball lace mill, the present invention is not limited thereto, and can be applied to various rigid mills such as a roller lace mill, and can be used as appropriate without departing from the spirit of the present invention.

[Brief explanation of drawings]

1 to 4 are diagrams showing an embodiment of the present invention, in which FIG. 1 is a longitudinal sectional view, and FIG. 2 is a -
Line sectional view, Figure 3 is an enlarged sectional view of the main part of Figure 1, Figure 4 is an enlarged plan view of the upper ring plate, Figures 5 to 8.
The figures are enlarged sectional views showing other embodiments, and FIG. 9 is an enlarged vertical sectional view showing a conventional example. 11...Casing, 12...Injection pipe, 14...
...Rotating body, 16... Classifying blade, 17... Classifying chamber,
18... Guide vane, 19... Upper ring plate,
20...Top plate, 21...Gap, 22...Protruding blade, 24...Exhaust pipe, 26...Outer hopper, 27...
...Inner hopper, 34...Transportation path, 50...Slanted plate.

Claims (1)

[Claims] 1. A classification blade provided on the outer periphery of the rotating body protruding into the casing and sandwiched between the upper ring plate and the bottom plate; provided on the outer periphery of the classification blade via a classification chamber. , and a guide vane fixed to the top plate of the casing; a hopper fixed to the lower end of the guide vane; an exhaust pipe communicating with the classification chamber via the classification blade; communicating with the classification chamber and the exhaust pipe, and A gap formed between the upper ring plate of the rotating body and the top plate of the casing; a protruding blade arranged on the upper ring plate and spaced apart from the top plate of the casing; a 40-degree gap formed on the top surface of the bottom plate 1. An air classifier comprising: an inclined plate having a portion inclined as above, and a lower end of which is located within 1/5 of the diameter of the rotating body from the outer peripheral edge of the bottom plate. 2. The air classifier according to claim 1, wherein the lower end of the guide vane is fixed to the hopper via a tapered guide vane support ring. 3. The air classifier according to claim 1, wherein the classification blade includes a protruding blade that protrudes into the classification chamber. 4. The air classifier according to claim 1, wherein the hopper is inclined at an angle of 50 degrees to 70 degrees with respect to the horizontal. 5. The air classifier according to claim 1, wherein the inclined plate is formed in a dogleg shape. 6. The air classifier according to claim 1, wherein the inclined plate is formed in an arc shape. 7. The air classifier according to claim 1, wherein the inclined plate has an upper end fixed to a rotating shaft. 8. A charging pipe protruding from the center of the casing; a rotating body rotatably fitted into the charging pipe and provided within the casing; a classification blade provided on the outer periphery of the rotating body; , a guide vane provided through the classification chamber and fixed to the top plate of the casing; an outer hopper fixed to the lower end of the guide vane; an exhaust pipe communicating with the classification chamber via the classification blade; a classification chamber and communicates with the exhaust pipe, and
A gap formed between the upper ring plate of the rotating body and the top plate of the casing; a protruding blade arranged on the upper ring plate and spaced apart from the top plate of the casing; An inclined plate whose lower end is located within 1/5 of the diameter of the rotating body from the outer periphery of the bottom plate; disposed inside the outer hopper and connected to the input pipe An air classifier characterized in that it is equipped with: a conical inner hopper provided at a lower portion; a crushing mechanism provided spaced apart at a lower portion of the outer hopper; 9 The outer hopper and inner hopper are each 50~
Claim 8, characterized in that the slope is 70 degrees.
Air classifier as described. 10. The air classifier according to claim 8, wherein a conveyance passage is provided on the side of the crushing mechanism to communicate the air inlet with the guide vane.