JPS649057B2 - - Google Patents

Description

[Detailed Description of the Invention] [Objective of the Invention] "Industrial Application Field" The present invention relates to a pulverizer for hard materials such as alumina, silicon carbide, silicon nitride, and zirconia, which are raw materials for new ceramics. The present invention relates to a pulverizer (hereinafter referred to as a jet mill) using fluid energy that enables the production of micron (1 micron or less) powder.

``Prior Art'' Currently, jet mills commonly used are classified into swing type (horizontal rotation and vertical rotation) jet mills and collision type (wall collision and nozzle facing) jet mills. A swirling jet mill has a great effect of rounding the crushed material, but once the crushed material is rounded, the crushing action is reduced and it is difficult to make the grain finer, so there is a limit to the amount of fine particles that can be obtained depending on the swirling action. The collision type has a great effect of crushing the crushed materials, but the crushed materials have sharp edges.
Depending on the purpose, it cannot be used as is. A collision-and-swing compound jet mill that eliminates this drawback is a jet mill that performs both collision and swirling operations. Special request 1987-
The invention disclosed in No. 157641 is a pulverizer of a type that uses both collision and rotation, and in this invention, the crushed material is crushed by the collision type mill part, and further crushed by the rotation type mill part. After that, it is classified to remove the fine powder, and the remaining part is crushed repeatedly.

Impingement-type jet mills other than the nozzle facing type (the same applies to the collision-type mill part of the composite type) crush the crushed material entrained in the jet flow by colliding it directly against a fixed wall, and its characteristics are based on the characteristics of the new ceramic raw material. It is well known that grinding is particularly suitable for grinding hard materials such as alumina and silicon carbide.

The material of the fixed wall used in an impingement-type pulverizer is generally ceramics or cemented carbide steel, and the fixed wall is provided facing perpendicularly to the jet flow.

``Problems to be Solved by the Invention'' When crushed particles, such as hard new ceramic raw materials, are collided with a jet flow against such a fixed wall, the colliding portions are worn away and a recess is formed, causing a short period of time. Fixed walls are worn out. That is, even if ceramics or cemented carbide steel are generally considered to have high wear resistance, they will have a short life as a fixed wall if they are collided at right angles.

For this reason, there is a fixed wall with a flat surface inclined to the jet flow, but in this case, the crushed material that collides with the fixed wall and is repulsed concentrates in one direction and flies away.
A tendency to disrupt the flow in the swirling grinding means occurs.

The present invention provides a pulverizer having the structure of an impact-type jet mill in which pulverized material accompanying a jet flow is directly collided with a fixed wall to achieve durable pulverization by improving the fixed wall. The purpose is to provide opportunities.

[Structure of the invention]

"Means for Solving the Problems" The present invention opens the tip of a nozzle through which high-pressure air is supplied to a solid-gas mixing chamber that communicates with a powder supply port, and accelerates air flow that communicates with the solid-gas mixing chamber in a straight line with the nozzle. A pulverizer comprising a tube and a collision plate facing the acceleration tube opening, characterized in that the collision plate is provided with a protrusion whose center most protrudes toward the center of the acceleration tube outlet. It is.

``Operation'' When the debris accompanying the jet stream ejected through the accelerating tube hits the protrusion of the collision plate, it eccentrically collides with the protrusion and is crushed. On the other hand, the debris moving toward the root side along the protrusion is crushed by collision with the debris moving straight ahead. After the collision, the debris scatters radially.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of an embodiment of the invention.

A solid-air mixing chamber 4 is formed by a head member 2 that forms a passage fixed to one end of the body 1 and a lid 3 that is fixed to the head member 2.
A nozzle 8 that communicates with the high-pressure header 6 via a compressed air pipe 7 and jets compressed air into the solid-air mixing chamber 4 is provided adjacently to the crushed material supply port 5 . At the other end of the body 1, a rotating crushing chamber 10 is formed by the body 1 and a circular dish-shaped bottom wall 9 fixed to the body 1, and each of the rotating crushing chambers 10 is provided with a compressed air pipe 1.
As shown in FIG. 3, a rotating crushing nozzle 12 that communicates with a high-pressure header 6 through a high-pressure header 6 and blows out compressed air is at an angle with respect to a radial line passing through its mounting portion and the center of the rotating crushing chamber 10, as shown in FIG. They are equally spaced on the outer periphery with α and are open. In addition, the rotating crushing chamber 10
A collision plate 13 is provided inside as a fixed wall facing the jet flow from the acceleration tube 14. This collision plate 13 is fitted and fixed into the center hole of the bottom wall 9 of the rotating crushing chamber. (Fixation method not shown).

An accelerating tube 14 is screwed and fixed to the head member 2, and the fixed mixing chamber 4 and the rotating crushing chamber 10 are communicated through the accelerating tube 14, which has an annular cross section and is concentric with the nozzle 8 for accelerating the solid-gas mixture flow. , its emitting tip,
This acceleration tube 14 is placed at an appropriate distance from the collision plate 13.
As shown in the illustration, the discharging tip is enlarged in a trumpet shape.

Further, an annular rectification zone 15 having a predetermined distance from the body 1 is provided on the outer periphery of the accelerating tube 14, and the rotating crushing chamber 10 is connected to the body 1 and the head member via this rectification zone 15. 2 and an accelerating tube 14.
It is connected to 6. Furthermore, the head member 2
An annular classification plate 17 is provided in the classification chamber 16 surrounding the accelerator tube 14 so as to divide the classification chamber 16 into two annular shapes, and for classifying fine powder and fine powder not suitable for a predetermined particle size. The powder chamber 18 is divided into a fine powder chamber 18 for classifying products with a smaller particle size, and a fine powder chamber 19 for introducing recirculation powder with a larger particle size on the outside. The two discharge holes 21 communicate with the collective discharge pipe 23 through each discharge pipe 22, while the fine powder chamber 19 communicates with the solid-gas mixing chamber 4 through circulation paths 24 arranged radially in the head member 2. has been done.

A protrusion 25 is provided on the collision plate 13 so as to face the acceleration tube 14 . FIG. 4 is an enlarged view of the collision plate 13 for explaining the protrusion 25. FIG. The center of the collision plate 13 and the center of the acceleration tube 14 having an annular cross section coincide with each other, and the protrusion 25 is located at the center of the collision plate 13. The center of the protrusion 25 is the most protruding toward the acceleration tube 14, and continues toward the base side to form a flat plate.
Continues smoothly to 6. The protrusion 25 is cone-like, and if its apex is θ ₁ , then the angle between the center of the collision plate 13 and the center of the collision plate 13 at any position on the generatrix of the protrusion 25 is θ > θ ₁ , and the angle θ is continuously the apex angle θ ₁ The angle further increases to 90 degrees and continues to the plane 26 of the collision plate 13, which is a flat plate. The root diameter D _B of the protrusion 25 at the point where this angle θ is 90 degrees is approximately 2D, assuming that the exit diameter D of the _acceleration tube 14 (excluding the tongue-like opening) is approximately 2D.
The height H of 5 is approximately D/2 to 2/3D.

Now, when compressed air is sent into the high-pressure header 6 from a high-pressure air source (not shown), the crushed material is solidified from the crushed material supply port 5 by the compressed air that passes through the compressed air pipe 7 and is jetted out at high speed from the nozzle 8. The gas is sucked into the gas mixing chamber 4, accelerated in the acceleration tube 14 in a solid-gas mixed state, and collides with the protrusion 25 of the collision plate. Further, compressed air in the header 6 is blown into the rotating crushing chamber 10 from a rotating crushing nozzle 12 through a compressed air pipe 11.
In the rotating crushing chamber 10, a vortex is generated around the acceleration tube 14. Since the protrusion 25 is approximately twice the diameter of the accelerating tube 14, the crushed material accompanying the jet flow from the accelerating tube 14 is shaped into a circle with a diameter D2 slightly larger than the diameter D due to the action of the flap-shaped end of the accelerating tube ₁₄ . It collides unevenly with the protrusion 25 in the range of . The angle formed by the generatrix of the protrusion 25 at the position of the outermost diameter D ₂ where the uneven collision occurs and the tangent to the flow velocity of the jet flow at that position is θ ₂ .

Therefore, the collision plate 13 made of ceramics is very fragile against the action of colliding at right angles, but the crushed material will absorb all the collision angles including the angles θ ₁ and θ ₂ formed with the generatrix of the protrusion 25. The surface of the protrusion 25 for collision at an angle θi < 90 degrees is rubbed and stuck, so there is less wear. It is appropriate that the angle of this eccentric collision is θi≦45 degrees. The projections 25 are directly biased by the debris accompanying the jet stream ejected from the acceleration tube 14 in a range slightly larger than the diameter D of the acceleration tube 14, but in addition to this, the debris collides biasedly with the projections 25 once and reaches the generatrix. The accelerating tube 14 that follows the crushed material repulses diagonally downward along the line or from the generatrix in Figures 1 and 4.
The crushed material that is sent almost in a straight line at high speed collides with each other. That is, the collision of the crushed particles occurs within the range of approximately the exit diameter D of the acceleration tube 14 of the protrusion 25 . This collision of the crushed materials with each other is only a crushing effect and hardly causes any wear on the collision plate 13. Such an action occurs three-dimensionally and radially from the center of the protrusion 25, and the crushed material crushed by the collision is finely crushed and hits the collision plate 13.
The particles are scattered radially in parallel on the plane 26 into the rotating grinding chamber 10. This scattered crushed material is accelerated by the jet flow from the rotating crushing nozzle 12, and the crushed powder collides and rubs against each other to be crushed. That is,
In the rotating crushing chamber 10, centrifugal force acts on the powder due to high-speed rotation, and large particles are further crushed by the rotating crushing nozzle while rotating on the outer wall side, becoming finer. The fine powder, which has been made fine by the collision and the rotational crushing action, loses its centrifugal force and passes through the nozzle 8 and the acceleration tube 14 into the rotational crushing chamber 10.
Accompanied by the flow of air to which the air that has entered zero is added, it reaches the classification chamber 16 while rotating at high speed through the rectifying zone 15 which is connected to the outer periphery of the aforementioned accelerating tube 14 from the swirling crushing chamber 10 . The crushed material subjected to collision crushing and rotational crushing is classified into fine powder with a larger particle size and fine particles with a smaller particle size in the classification chamber 16, and enters the fine powder chamber 19 and the fine powder chamber 18, and the fine powder passes through the discharge hole 21. ,
It passes through the discharge pipe 22, is collected in the collecting discharge pipe 23, and is collected by a collector (not shown) installed outside the machine. On the other hand, the fine powder classified in the classification chamber 16 is
It is sucked into the solid-gas mixing chamber 4 again through the circulation path 24,
Collision crushing and rotational crushing are repeated.

5 is a perspective view of another embodiment of the collision plate 13, FIG. 6 is a plan view of FIG. 5, and FIG. 7 is a line C-C of FIG. 6.
In the cross-sectional view, a protrusion 25 provided on the collision plate 13 has a plurality of spiral grooves 27 extending downstream from the center toward the outer periphery so as to follow the direction of the swirling crushing nozzle 12, that is, the direction of the swirling flow. is provided. As shown in FIG. 7, the right-angled cross section of the spiral groove 27 has a smooth bottom and edge, such as a circular arc. The spiral groove 27 starts slightly away from the tip of the protrusion 25 with a smaller width and depth,
The width and depth gradually become wider until reaching the middle part, the width becomes the same or wider towards the root part of the protrusion 25, and the depth becomes shallower towards the root part of the protrusion 25.
The depth at the base of the protrusion 25 is zero and is in contact with the plane 26 of the collision plate 13.

According to this embodiment, a part of the crushed material ejected from the accelerating tube 14 and colliding with the protrusion 25 is formed in the spiral groove 27.
The air flows from the center of the protrusion 25 to the base of the protrusion 25 while being given a swirling flow therein. Therefore, a pre-swirl is given to the crushed material supplied to the swirling crushing chamber 10, and a stronger swirling flow is generated in the swirling crushing chamber 10.

As explained above, by making the collision angle smaller than the right angle to the collision plate as a solid wall of the crushed material, the disadvantage of brittleness due to impact of ceramics can be overcome, and the maximum resistance to rubbing and scratching wear can be achieved. By demonstrating these characteristics, the life of the wear-resistant material can be extended.

Furthermore, in the crushing test conducted on the embodiment of the present invention, when the collision angle θ _i was in the range of 30° to 45°,
It has been confirmed that there is no significant difference in crushing ability compared to flat plates.

〔Effect of the invention〕

The present invention has an opening at the tip of a nozzle through which high-pressure air is supplied to a solid-gas mixing chamber that communicates with a crushed material supply port, an acceleration tube that communicates with the solid-gas mixing chamber in a straight line with the nozzle, and a nozzle that faces the acceleration tube outlet. A pulverizer equipped with a collision plate is characterized in that the collision plate is provided with a protrusion whose center part is most protruding toward the center of the outlet of the accelerator tube, so that the pulverizer has a collision-type jet mill function. In a pulverizer, the durability of the impact plate is significantly increased, and materials such as ceramics, which are not resistant to wear against direct impact of the crushed material, can be used as solid walls.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. 3 is a cross-sectional view taken along line B-B in FIG.
4 is a front view of the collision plate, FIG. 5 is a perspective view of another embodiment of the collision plate, FIG. 6 is a plan view of FIG. 5, and FIG. 7 is taken along C-C of FIG. 6. It is an enlarged sectional view. 1... Body, 2... Head member, 3... Lid, 4
... solid-gas mixing chamber, 5 ... crushed material supply port, 6 ... high pressure header, 7 ... compressed air pipe, 8 ... nozzle, 9 ...
...Bottom wall, 10... Rotating crushing chamber, 11... Compressed air pipe, 12... Rotating grinding nozzle, 13... Collision plate, 14... Accelerator tube, 15... Rectification zone, 16
... Classification room, 17 ... Classification room, 18 ... Fine powder room,
19...Fine powder chamber, 21...Discharge hole, 22...Discharge pipe, 23...Collective discharge pipe, 24...Circulation path, 25
... protrusion, 26 ... plane, 27 ... spiral groove.

Claims (1)

[Claims] 1 Open the tip of the nozzle that supplies high-pressure air to the solid-gas mixing chamber leading to the crushed material supply port, and provide an acceleration pipe that communicates with the solid-gas mixing chamber in a straight line with the nozzle, and collide against the acceleration pipe outlet. A pulverizer equipped with a plate, characterized in that the collision plate is provided with a protrusion whose center part is most protruding toward the center of the exit of the acceleration tube.