JP2014200721A - Jet mill apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a jet mill apparatus capable of reducing a variation in a particulate diameter by crushing treatment by stably generating a high speed swirling flow in a cavity chamber, though being an extremely simple structure.SOLUTION: The jet mill apparatus comprises a plurality of jet nozzles 13 embedded in a ring shape in an inner wall side surface of the cavity chamber 11, and crushes a crushing object injected into the cavity chamber in a fine particle by using the high speed swirling flow generated by high pressure gas jetted from the nozzles. A concentric coaxial cylinder of turning in the vertical upper direction is provided in a substantially central part of a ceiling surface of the cavity chamber, and the crushing object is injected into the cavity chamber by using negative pressure generated in an inner cylinder part 21 of the coaxial cylinder 21, and the crushed fine particle is also extracted from the inside of the cavity chamber by using positive pressure generated in an outer cylinder part 22 of the coaxial cylinder.

Description

  The present invention generates a high-speed swirling flow in the cavity chamber by the high-pressure gas injected from the jet nozzle, thereby pulverizing the object to be crushed into a fine powder and classifying it according to the particle diameter. The present invention relates to a jet mill apparatus that performs the above.

  In the hollow chamber, a high-speed swirling flow is generated by the high-pressure gas ejected from the jet nozzle, the powder that is the object to be crushed is entrained in this, and the powder particles are pulverized by collision between the particles constituting the powder. As what is performed, a so-called jet mill apparatus is known. Here, the general structure of the apparatus is shown in FIG. Incidentally, this figure shows a schematic cross-sectional view in the horizontal direction of the hollow chamber in which the pulverization process is performed in the apparatus.

  A crushing process is performed inside the hollow chamber 100 shown in the figure, and a plurality of jet nozzles 101 that are high-pressure gas injection ports are provided on the inner wall of the hollow chamber 100 at predetermined intervals. A high-speed swirling flow is generated inside the cavity chamber 100 by high-pressure gas (usually compressed air is used) injected from each jet nozzle.

  One of these jet nozzles (jet nozzle 102 shown in the figure) is connected to a hopper (not shown) for drawing the object to be crushed, and the object to be crushed through the jet nozzle. The powder is drawn into the hollow chamber 100 together with the high-pressure gas. The powder pulverized and finely divided inside the hollow chamber is sucked and extracted from the extraction port 103 provided at a substantially central portion of the ceiling surface of the hollow chamber.

  However, in the conventional jet mill apparatus as shown in FIG. 5, the powder to be crushed is drawn into the hollow chamber using one jet nozzle that is a jet port for high-pressure gas. The shape and size of the injection ports of the drawing nozzle 102 and the other high-pressure gas injection nozzle 101 are different, and turbulence tends to occur in the high-speed swirling flow generated in the cavity chamber. As a result, the pulverized fine particle diameter has a large variation, and improvement has been desired to obtain a uniform fine particle diameter.

  In order to solve such problems, for example, inventions as disclosed in Patent Documents 1 to 3 are disclosed. Incidentally, these inventions stabilize the flow of the high-speed swirling flow generated in the cavity chamber by providing a hopper for drawing the powder of the material to be pulverized separately from the jet nozzle that is the injection port of the high-pressure gas. Thus, the dispersion of the pulverized fine particle diameter is attempted to be suppressed.

JP 2007-196147 A JP 2008-168291 A JP 2010-094574 A

  However, the inventions disclosed in Patent Documents 1 to 3 have the disadvantage that the structure is complicated and the cost of the apparatus is increased as compared with the conventional jet mill apparatus. Moreover, although the variation in the fine particle diameter that has been pulverized by the jet mill apparatus having such a structure is reduced to some extent, there is still room for improvement in its effect.

  The present invention aims to solve such problems in the prior art. More specifically, the present invention stably generates a high-speed swirling flow in the cavity chamber despite the extremely simple structure. An object of the present invention is to provide a jet mill apparatus capable of reducing the variation in the particle diameter due to the pulverization treatment.

In order to solve the above problems, a jet mill device according to a first aspect of the present invention
A plurality of jet nozzles embedded in a ring shape on the inner wall side surface of the cavity chamber, and using a high-speed swirling flow generated by the high-pressure gas injected from the nozzle, the object to be crushed in the cavity chamber is minutely A jet mill for crushing into particles,
In the substantially central portion of the ceiling surface of the hollow chamber, a concentric coaxial cylinder is provided that extends in the vertical upward direction.
The object to be crushed is drawn into the hollow chamber using the negative pressure generated in the cylindrical inner cylindrical portion of the coaxial circle, and is pulverized from the hollow chamber using the positive pressure generated in the outer cylindrical portion of the coaxial cylinder. It is characterized by extracting fine particles.

The jet mill device according to the second aspect of the present invention is the above first aspect,
The shape of the hollow chamber is a rotationally symmetric shape including a disc shape, a cylindrical shape, a spherical shape, or a spindle shape with respect to a central axis in the vertical direction.

The jet mill device according to the third aspect of the present invention is the above first or second aspect,
A structural band in which a plurality of jet nozzles are embedded in a ring shape is provided on a side surface of the inner wall of the hollow chamber so as to overlap in a plurality of stages along the vertical direction.

A jet mill device according to a fourth aspect of the present invention provides the jet mill apparatus according to any one of the first to third aspects,
An angle formed by the jet direction of the jet nozzle and the radial normal of the hollow chamber is 30 to 85 degrees, or -30 to -85 degrees.

A jet mill device according to a fifth aspect of the present invention, in any one of the first to fourth aspects,
An injection pipe having a check valve structure is provided in a substantially central portion of the bottom surface of the hollow chamber, and an object to be crushed together with the high-pressure gas is injected and drawn into an inner cylinder portion of the coaxial cylinder through the injection pipe. .

  According to the jet mill apparatus of the present invention, it is possible to generate a stable high-speed swirling flow in the hollow chamber, despite the extremely simple and simple structure, and the particle diameter is finer and smaller than the conventional one. It is possible to produce a fine particle powder with a small variation in.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. First, FIG. 1 shows a partially transparent perspective view of a jet mill apparatus (hereinafter simply referred to as “the present apparatus”) which is one embodiment of the present invention. FIG. 2 is a schematic sectional view in the vertical direction of this apparatus, and FIG. 3 is a schematic sectional view in the horizontal direction related to the hollow chamber.

  As shown in each of these drawings, the present apparatus is mainly composed of a base part 1 and a powder inlet / outlet part 2 provided at the center of the upper surface of the base part 1. Further, inside the base portion 1, there are provided a main cavity chamber 11 in which powder is pulverized and a sub-cavity chamber 12 surrounding the main cavity chamber 11. In the present embodiment, a disk-like form is shown as the main cavity chamber 11, but the implementation of the present invention is not limited to such a case.

  For example, the main cavity chamber 11 can be formed in a cylindrical shape, a spherical shape, a hemispherical shape, a conical shape, or a spindle shape. That is, any configuration can be selected as long as the main cavity chamber 11 has a so-called rotationally symmetric shape with respect to the central axis in the vertical direction.

  On the other hand, a plurality of jet nozzles 13 are embedded in a ring shape at predetermined intervals on the inner wall side surface of the main cavity chamber 11, and the main cavity chamber 11 and the sub-cavity chamber 12 are connected via the jet nozzle 13. It is connected. That is, the high-pressure gas injected from the outside of the apparatus into the sub-cavity chamber 12 is jetted into the main cavity chamber 11 at a high speed from the jet nozzle 13 having the jet port of the jet valve structure. A high-speed swirling flow is formed inside the main cavity chamber 11 by the gas jet.

As shown in FIG. 3, the jet outlet of the jet nozzle 13 forms a predetermined angle θ with respect to a normal line in the radial direction connecting the jet outlet and the center point of the main cavity chamber 11.
The value of the angle θ is not particularly limited, but in an actual embodiment,
30 degrees ≤ θ ≤ 85 degrees or
It is preferable to set in the range of −30 degrees ≦ θ ≦ −85 degrees.

  Further, the number of jet nozzles 13 provided in a ring shape on the inner wall side surface of the main cavity chamber 11 is not particularly limited, and various values can be taken in an actual embodiment. However, in order to generate an ideal swirl flow inside the main cavity chamber 11, it is preferable to provide at least 10 or more, more preferably 12 or more jet nozzles at regular intervals in a ring shape.

  In the present embodiment, only one stage of the belt-like ring of the jet nozzle 13 is provided on the inner wall surface of the main cavity chamber 11, but the implementation of the present invention is not limited to such a case. That is, the number of overlapping stages in the vertical direction of the belt-like ring of the jet nozzle provided in the main cavity chamber is determined in combination with the structure of the main cavity chamber.

  For example, when the structure of the main cavity chamber 11 is not a disk shape as in the present embodiment, but is a cylindrical shape or a spindle shape extending in the vertical direction, or a spherical shape or a hemispherical shape, a plurality of stages are used. A belt-like ring extending over the inner cavity side surface of the main cavity chamber 11 may be provided so as to overlap. In this case, it is preferable that the number of jet nozzles provided in the belt-like ring at each stage is appropriately determined according to each embodiment.

  On the other hand, the powder inlet / outlet part 2 is provided substantially at the center of the base part 1 as described above, and is configured by a coaxial cylinder including an inner cylinder part 21 and an outer cylinder part 22 arranged concentrically. . As shown in the cross-sectional view of FIG. 2, the lower ends of the inner cylinder portion 21 and the outer cylinder portion 22 are inserted through the substantially central portion of the ceiling surface of the main cavity chamber 11. A powder hopper 23 is provided at the top of the apparatus. Moreover, the upper end of the outer cylinder part 22 is closed, and an extraction tube 24 for extracting powder pulverized into fine particles is connected to the side surface.

The values of the diameter ψ 1 of the inner cylinder portion 21, the diameter ψ 2 of the outer cylinder portion 22, and the diameter ψ 0 of the main cavity chamber 11 are not particularly limited, but in practical embodiments, the values are as follows: It is preferable to set in the range.
300mm ≧ ψ0 ≧ 50mm
20mm ≧ ψ1 ≧ 6mm
100mm ≧ ψ2 ≧ 20mm

  Incidentally, in the present embodiment, the above parameters are set to ψ0 = 300 mm, ψ1 = 10 mm, and ψ2 = 82 mm, respectively. The height (thickness) of the main cavity chamber 11 is set to 30 mm, and the number of jet nozzles is set to 12. In addition, the height (length) of the powder inlet / outlet part 2 shall be suitably selected according to an actual embodiment.

  Next, the operation of this apparatus will be described. First, high-pressure gas is continuously injected into the sub-cavity chamber 12 of the base unit 1 from a high-pressure gas supply source (not shown) provided outside the apparatus. Incidentally, various inert gases such as nitrogen and carbon dioxide can be used as the high-pressure gas, but it is very common to use compressed air as the high-pressure gas. In addition, as a supply source of high-pressure gas, you may make it discharge the compressed air stored in the cylinder, or you may make it supply compressed air continuously using gas compression apparatuses, such as a compressor.

The value of the pressure P (unit: MPa: megapascal) of the high-pressure gas supplied to the apparatus is not particularly limited.
1.2 MPa ≧ P ≧ 0.8 MPa
It is preferable to use a value of a degree from the viewpoint of increasing the efficiency of pulverization and making fine particles. Incidentally, in this embodiment, P is set to 1.0 MPa.

  The high-pressure gas injected into the sub-cavity chamber 12 from the high-pressure gas supply source maintains the above-mentioned predetermined angle θ with respect to the normal line in the radial direction of the main cavity chamber 11 via the jet nozzle 13, and the inside of the main cavity chamber 11. Is injected at high speed. As a result, a high-speed swirling flow is generated inside the main cavity chamber 11 like a tornado or typhoon.

  The high-pressure gas supplied from the outside of the apparatus is once introduced into the sub-cavity chamber 12 and then injected into the main cavity chamber 11 via the jet nozzle 13, so that each jet nozzle 13 A uniform jet can be formed. Further, by temporarily accumulating the high-pressure gas in the sub-cavity chamber 12, an effect of reducing the fluctuation of the gas injection amount from the high-pressure gas supply source can be obtained.

  If a swirling flow of high-pressure gas is generated in the main cavity chamber 11, the powder to be subjected to the pulverization process is gradually drawn from the hopper 23 provided at the top of the apparatus. The powder drawn from the hopper 23 passes through the inner cylinder portion 21 of the powder inlet / outlet portion 2 and falls to the center portion of the main cavity chamber 11 and is caught in the swirling flow generated inside the main cavity chamber 11. Will be. Note that negative pressure is generated at the center of the swirling flow on the same principle as the pressure drop generated in the eye of the typhoon. Therefore, when the powder falls inside the inner cylinder portion 21, this negative pressure is generated. There is no possibility of being sucked into the main cavity chamber 11 by the pressure and flowing backward in the direction of the hopper 23.

  While the powder entrained in the swirling flow in the main cavity chamber 11 flies at a high speed on the swirling flow, the particles of the powder collide with each other and are pulverized to reduce the particle diameter contained in the powder. Is promoted. Further, particles having a large particle size move to the outside of the swirling flow due to the centrifugal force generated by the swirling flow, and particles having a small particle diameter gather inside the swirling flow. That is, in this apparatus, the pulverization of the powder particles and the classification of the particle diameter are automatically performed in the course of the pulverization process.

  Naturally, the speed of the swirl flow is also fast outside the swirl flow, so that the pulverization process is further accelerated, and the pulverized and micronized particles gather inside the swirl flow. At the periphery of the center of the swirl flow corresponding to the typhoon eyes, a positive pressure is generated for the so-called typhoon eyes, as in the case of the typhoon. For this reason, the micronized particles gathered inside the swirling flow are pressurized by this positive pressure, rise inside the outer cylindrical portion 22 of the coaxial cylinder, and are extracted outside the apparatus through the extraction pipe 24. The

  As experimental data regarding the pulverization processing of the powder, a comparison of the pulverization processing results between this apparatus and a conventional jet mill apparatus is shown in the graph of FIG. In the figure, FIG. (4a) shows the case where the pulverization process is performed by this apparatus, and FIG. (4b) shows the case where the conventional apparatus is used. In addition, the vertical axis | shaft of a graph represents the frequency where the particle | grains of the said particle diameter are contained in the micronized powder after a grinding process.

  In addition, as the materials to be pulverized, 2000 grams of calcium hydroxide powder is used for both, and the time required for the pulverization is 5 minutes. The purpose of the pulverization process is to obtain a fine particle powder having a particle size of about 4 μm (micrometer). The particle size after pulverization was measured with a laser analysis type particle measuring device.

  As is apparent from FIG. 4, when this apparatus is used, the frequency of occurrence of the target particle diameter of about 4 μm (micrometer) is increased about twice as compared with the conventional apparatus. On the contrary, the width of variation in the vicinity of the target particle diameter of about 4 μm (micrometer) is reduced to about ½ of the conventional apparatus.

  In the embodiment described above, the powder of the material to be crushed is drawn into the hollow chamber from the hopper 23 provided at the top of the inner cylinder portion 21. Is not limited to such cases. For example, an injection pipe having a check valve structure is provided at the substantially central portion of the bottom surface of the cavity chamber 11, and the powder that is to be crushed is jetted into the inner cylinder portion 21 together with the high-pressure gas such as compressed air through the injection pipe. It is also possible to draw the object to be crushed into the hollow chamber 11.

  The structure of the injection port in the injection tube is a so-called check valve structure in which the injection port is opened only at the time of injection by the high-pressure gas applied to the injection tube, so that the powder of the material to be crushed can be hollow chamber 11. Will not leak to the outside. In this case, the upper end portion of the inner cylinder portion 21 is closed in the same manner as the outer cylinder portion 22.

  As described above, when this apparatus is used, it is possible to produce fine particle powder with less variation in particle diameter compared with the conventional jet mill apparatus, and the apparatus has a simple structure. Cost can be reduced.

  The present invention is not limited to each embodiment described above. For example, the shape and arrangement of each part constituting the present invention, or its material, etc., do not depart from the spirit of the present invention. Needless to say, it can be changed as appropriate according to the actual implementation.

The configuration of the present invention can be used in the field of producing a fine particle powder of a material by pulverizing various materials.

It is a partially transparent perspective view which shows the structure of the jet mill apparatus by a present Example. It is sectional drawing of the perpendicular direction of the jet mill apparatus by a present Example. It is sectional drawing of the horizontal direction of the jet mill apparatus by a present Example. It is a graph which shows the result of the grinding | pulverization process by this apparatus and a conventional apparatus. It is explanatory drawing showing the principle of the conventional jet mill apparatus.

DESCRIPTION OF SYMBOLS 1 ... Base part 11 ... Main cavity room 12 ... Sub cavity room 13 ... Jet nozzle 2 ... Powder inlet / outlet part 21 ... Inner cylinder part 22 ... Outer cylinder part 23 ... Hopper 24 ... Extraction pipe

Claims (5)

A plurality of jet nozzles embedded in a ring shape on the inner wall side surface of the cavity chamber, and using a high-speed swirling flow generated by the high-pressure gas injected from the nozzle, the object to be crushed in the cavity chamber is minutely A jet mill for crushing into particles,
In the substantially central portion of the ceiling surface of the hollow chamber, a concentric coaxial cylinder is provided that extends in the vertical upward direction.
The object to be crushed was drawn into the hollow chamber using the negative pressure generated in the inner cylindrical portion of the coaxial cylinder, and was pulverized from the hollow chamber using the positive pressure generated in the outer cylindrical portion of the coaxial cylinder. A jet mill apparatus for extracting fine particles.   3. The jet mill device according to claim 2, wherein the shape of the hollow chamber is a rotationally symmetric shape including a disc shape, a cylindrical shape, a spherical shape, or a spindle shape with respect to a central axis in the vertical direction.   3. The jet mill according to claim 1, wherein a structural band in which a plurality of jet nozzles are embedded in a ring shape is provided on a side surface of the inner wall of the hollow chamber so as to overlap a plurality of stages along a vertical direction. apparatus.   The angle formed between the jet direction of the jet nozzle and the radial normal line of the hollow chamber is 30 to 85 degrees, or -30 to -85 degrees. The jet mill apparatus as described in at least any one. An injection pipe having a check valve structure is provided in a substantially central portion of the bottom surface of the hollow chamber, and an object to be crushed together with the high-pressure gas is injected and drawn into an inner cylinder portion of the coaxial cylinder through the injection pipe. The jet mill device according to at least one of claims 1 to 4.

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