JP4963548B2 - Jet mill - Google Patents

Description

  The present invention relates to a horizontal swirling flow type jet mill suitable for ultrafine pulverization, in which a pulverizing zone and a classification zone are formed by a swirling flow using a high-pressure fluid among pulverizers.

  The basic structure of the jet mill consists of a mill body forming an annular cavity, a discharge part provided at the center of the cavity, a material supply means for introducing the material into the cavity, and a high-pressure fluid in the cavity A pulverizing zone for pulverizing the raw material introduced into the cavity chamber by the vortex flow through the irradiating means, and classifying the pulverized material pulverized in the pulverizing zone A classification zone is formed to allow more discharge. In the above jet mill, for example, various improvements have been made from the viewpoint of pulverization efficiency that enables pulverization in a shorter time or classification accuracy that reduces the particle size variation of the pulverized product. Among them, from the classification accuracy, the configuration is such that the angle of the nozzle that ejects the high-pressure fluid that is the ejection means can be changed (Patent Document 1), and the configuration in which rotationally driven classification blades are attached around the opening of the discharge portion ( Patent Document 2) and a configuration (Patent Document 3) in which a pulverization zone formed in a hollow chamber and a classification zone are communicated with each other through a narrow path are known.

JP 52-44450 A JP-A-63-319067 JP 2005-131633 A

  In the jet mill disclosed in Patent Document 1, the selection range of the pulverization particle size can be expanded by changing the nozzle angle in addition to the nozzle diameter and the number of nozzles for injecting the high pressure fluid, the pressure of the high pressure fluid, etc. The powder that has been thrown into the dead space (where vortex or turbulent flow does not become swirl) flows without being pulverized, and is discharged together with the pulverized material. The body had to be crushed again, and classification accuracy could not be improved. In the jet mill of Patent Document 2, the swirling flow caused by the high-pressure fluid and the swirling flow caused by the rotationally driven classification blades are different in speed and collide with each other, so that turbulence occurs and it is difficult to maintain a stable classification action. In the jet mill of Patent Document 3, for example, the classification action changes greatly depending on the setting of a narrow narrow channel (classification ring channel) provided between the pulverization zone and the classification zone, and the classification takes time, resulting in poor classification efficiency. easy.

  Accordingly, an object of the present invention is to provide a jet mill that can prevent the jumping phenomenon and improve the classification accuracy and reduce the particle size variation of the pulverized product while maintaining the simplification and compactness of the apparatus as compared with the above conventional structure. Is to provide.

In order to achieve the above object, the invention of claim 1 introduces a mill main body forming a substantially annular cavity chamber, a discharge portion provided substantially at the center of the cavity chamber, and introducing a raw material into the cavity chamber. A raw material supply means; and an injection means for forming a swirl flow by a high-pressure fluid in the hollow chamber, and a pulverization zone for pulverizing the raw material introduced by the swirl flow, and a pulverized product pulverized in the pulverization zone In the jet mill that forms a classification zone that can be discharged from the discharge portion, the discharge portion protrudes from one of the upper and lower wall portions that define the hollow chamber, and the hollow chamber the inner cylinder member Ru extending toward the other wall portion so as to cross the longitudinal direction, and the bottomed cylindrical outer tube member projecting into the cavity outside provided said other wall, one wall of the cavity chamber Projecting from the outside and communicating with the inner cylinder member And a connecting tube member that has a cylindrical portion which the inner tube member is arranged while keeping a discharge auxiliary channel and the gap for secondary classification in a recess of the outer cylinder member, the discharge auxiliary path It is a space formed between the outer periphery of the cylindrical part and the inner periphery of the outer cylinder member, and the secondary classification gap is along the inner periphery of the concave part of the outer cylinder member and the tip of the cylindrical part. A space defined between a horizontal cross section and an inner end surface of the recess facing the tip of the cylindrical portion, and the pulverized material passes from the classification zone through the discharge auxiliary path and the secondary classification gap. And entering the cylindrical portion of the inner cylindrical member.

The above jet mill is preferably embodied as follows. That is, the length of the cylindrical part is 1.3 times or more of the maximum distance between the upper and lower wall parts defining the hollow chamber (Claim 2).

In the invention of claim 1, the upper and lower wall portions defining the hollow chamber project from one wall portion and extend toward the other wall portion so as to cross the hollow chamber in the vertical direction. And a discharge cylindrical portion arranged with a predetermined gap in a concave portion attached to the portion and projecting out of the hollow chamber. Then, among the pulverized products pulverized in the pulverization zone, the pulverized product that has entered the classification zone is classified in the classification zone (only the particles that have reached the designed particle size or particle size are sent to the discharge section side, and the others) ) Again, and through the discharge auxiliary path and the secondary classification gap between the concave portion and the cylindrical portion, it is classified with high accuracy and can be discharged from the cylindrical portion. In other words, the structural features are that the pulverized material that has entered the classification zone is classified again with high accuracy (secondary classification) by passing through the path between the concave portion and the cylindrical portion in addition to the primary classification in the classification zone. Thus, as compared with the conventional structure, variation in particle size or particle size is suppressed without impairing simplification and compactness of the apparatus, and classification accuracy is improved.
Further, the present invention is simple because the discharge portion is composed of an inner cylinder member, an outer cylinder member, and a connection cylinder member, and can be easily maintained, and has a discharge auxiliary path and a secondary classification gap. Both can be easily formed, and the point that the space for forming the secondary classification gap is larger than the horizontal cross-sectional area of the discharge auxiliary path is also significant in performing the secondary classification of the present invention with certainty.
In the invention of claim 2, the length of the cylindrical portion is determined in consideration of the shape of the hollow chamber, the capacity, the strength of the swirling flow, etc., and the setting of the gap between the concave portion and the cylindrical portion. If it becomes smaller than 1.3 times the maximum distance between the upper and lower walls that define the hollow chamber, it will be difficult to maintain the accuracy of the secondary classification described above. There is significance in doing.

  A preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view schematically showing a jet mill according to an embodiment, and FIG. 2 is a sectional view taken along the line AA in FIG. FIG. 3 shows a modification of the jet mill.

(Equipment structure) The jet mill of the embodiment includes a mill main body 1 forming a main cavity chamber a on the center side and a sub-cavity chamber b on the outer periphery thereof, and a pulverized product pulverized and classified in the main cavity chamber a ( Product) through a discharge auxiliary path c and a secondary classification gap d to be described later, a raw material supply means 3 for introducing a raw material (powder raw material) into the main cavity chamber a, and a main cavity chamber a Injecting means 4 or the like for forming a swirling flow by a high-pressure fluid is provided therein, and the raw material introduced into the main cavity chamber a by the swirling flow formed through the injecting means 4 is pulverized in the main hollow chamber a. A pulverization zone and a classification zone that enables discharge from the discharge unit 2 while classifying the pulverized material pulverized in the pulverization zone are formed. The target jet mill may be a structure that satisfies the above basic requirements.

  The main part is one wall member (the lower wall member 11 in the form of FIG. 1, the upper wall member in the modification of FIG. 3) among the upper and lower wall members 10 and 11 in which the discharge part 2 defines the main cavity chamber a. 10) projecting to the other wall portion side (upper wall member 10 in the form of FIG. 1, lower wall member 11 in the modified example of FIG. 3) so as to traverse the main cavity chamber a in the vertical direction, and the other wall A cylindrical portion (an inner cylinder member 20 to be described later) disposed with a discharge auxiliary path c and a secondary classification gap d in a recess 21a provided outside the main cavity chamber a. The pulverized product pulverized in the pulverization zone is classified from the classification zone through the discharge auxiliary path c and the secondary classification gap d with high accuracy, and is then discharged into the cylindrical portion. 3 is a configuration in which the mill main body 1 is provided with the discharge portion 2 facing upward to discharge the product from the upper side, and the rest of the configuration is the same as the structure of FIGS. The same reference numerals are given to the same functional members.

  Here, in the mill body 1, the main hollow chamber a is defined inside the inner wall 12 by disposing the annular inner wall 12 and the annular outer wall 13 between the upper wall member 10 and the lower wall member 11. In addition, a sub-cavity b for the air supply chamber is defined between the inner wall 12 and the outer wall 13. The upper and lower wall members 10 and 11 of FIG. 1 are provided with a through hole 7 having a large diameter in the upper wall member 10 and a through hole 8 in the lower wall member 11 that are located in the center and penetrated on the coaxial line. A recess 11 a centering on the through hole 8 is provided inside the lower wall member 11. On the other hand, the upper and lower wall members 10 and 11 of FIG. 3 are provided with a through hole 5 of the upper wall member 10 and a large through hole 6 of the lower wall member 11 which are located in the center and penetrated on the coaxial line. In addition, a recess 10 a centering on the through hole 5 is provided inside the upper wall member 10. However, in addition to this, the mill body of the present invention omits the sub-cavity b as shown in Japanese Patent No. 3087201, or in the main cavity chamber a as shown in Patent Document 3. The structure which connects the crushing zone and classification zone which are formed via a narrow path may be sufficient.

  The raw material supply unit 3 includes a supply pipe 30 connected to the upper wall member 10 at a predetermined position and angle, a hopper 31 connected to the supply pipe 30, a nozzle 32, and the like. When entering the supply pipe 30 from the hopper 31, it is supplied together with the high-pressure fluid fed from the nozzle 32 to the grinding zone of the main cavity chamber a. However, the raw material supply means of the present invention includes, in addition to this, for example, a Laval nozzle configuration in which a high-pressure fluid supply pipe and an acceleration pipe are combined, or a configuration provided at a plurality of locations depending on the physical properties and supply amount of the raw material powder. .

The injection means 4 includes the above-described sub-cavity b, the air supply pipe 41 that introduces high-pressure fluid from the outside into the sub-cavity b, and the high-pressure fluid in the sub-cavity b that is assembled to the inner wall 12. And a nozzle 40 that injects into the nozzle. As inferred from FIG. 2, the nozzles 40 are respectively provided at four equal parts with respect to the periphery of the inner wall 12, and are provided in a state inclined by a predetermined angle with respect to the diameter direction of the inner wall 12 . However, the nozzle 40 may have a configuration in which the number or the diameter is changed, or an angle adjustment type as in Patent Document 1 is provided.

  When the high-pressure fluid is jetted from the nozzle 40, the above jetting means 4 forms a pulverization zone in the main cavity chamber a by the swirling flow caused by the jetting, away from the center, and forms a classification zone in the central side. For example, the subcavity b may be omitted and the high pressure fluid may be directly supplied to each nozzle 40. In the pulverization zone, the raw materials are accelerated and collide with each other or collide with the surrounding wall surface and are pulverized. In this case, as shown in Japanese Patent No. 3087201, the pulverization zone includes a collision plate for promoting pulverization and rectification A plate may be attached. In the classification zone, among the pulverized products pulverized in the pulverization zone, those having reached a predetermined particle size or particle size are transferred from the pulverization zone, and from the classification zone, the discharge auxiliary path c and the secondary classification gap d of the main part of the invention. After being classified again with high accuracy in the process of passing through the pipe, it is discharged to the outside through the inner cylinder member 20 and the connecting cylinder member 21 constituting the discharge portion 2.

  That is, the discharge part 2 of FIG. 1 protrudes inside the lower wall member 11 among the upper and lower wall members 10 and 11, and extends toward the upper wall member 10 so as to cross the inside of the main cavity chamber a in the vertical direction. The inner cylinder member 20 is provided on the outer side of the upper wall member 10 so as to protrude from the inner side of the inner cylinder member 20 with the discharge auxiliary path c and the secondary classification gap d at the front end side of the inner cylinder member 20 being received in the recess 21a inside the cylinder. The outer cylinder member 21 and the connecting cylinder member 22 projecting from the lower wall member 11 in communication with the inner cylinder member 20. The inner cylinder member 20, the outer cylinder member 21, and the connecting cylinder member 22 have flange portions 20a, 21b, and 22a in which the corresponding attachment end sides are bent. And the inner cylinder member 20 is arrange | positioned in the state by which the flange part 20a was fitted by the recess 11a with respect to the inner surface of the lower wall member 11. FIG. The connecting cylinder member 22 is arranged so that the inner diameter of the flange portion 22 a is located on the same axis as the through hole 8 and the inner cylinder member 20 with respect to the outer surface of the lower wall member 11. From this state, the fastener S1 is fastened and locked to the flange portion 22a, the corresponding portion of the lower wall member 11, and the flange portion 20a, so that the inner cylinder member 20 and the connecting cylinder member 22 are integrated with the lower wall member 11. Combined. On the other hand, after the outer cylinder member 21 is arranged so that the inner diameter of the flange portion 21b is located on the same axis as the through-hole 7 and the inner cylinder member 20 with respect to the outer surface of the upper wall member 10, the fastener S2 is removed from the flange portion 21b. The upper wall member 11 is integrally coupled to the upper wall member 10 by being fastened to the corresponding portion of the upper wall member 11. Here, the discharge auxiliary path c of the present invention is a space formed between the outer periphery of the inner cylinder member 20 and the inner periphery of the outer cylinder member 21. On the other hand, the secondary classification gap d is a space formed between the tip of the inner cylinder member 20 and the inner end surface of the recess 21a facing the tip. The speed of the granular material flowing through the discharge auxiliary path c from the classification zone described above is determined by the horizontal sectional area of the discharge auxiliary path. This area is designed to be smaller than the space forming the secondary classification gap. The mounting structure of the inner cylinder member 20, the outer cylinder member 21, and the connecting cylinder member 22 described above may be other means such as welding or welding.

  On the other hand, the discharge part 2 of FIG. 3 protrudes inside the upper wall member 10 among the upper and lower wall members 10 and 11, and extends toward the lower wall member 11 so as to cross the inside of the main cavity chamber a in the vertical direction. The inner cylinder member 20 is provided on the outer side of the lower wall member 11 so as to keep the discharge auxiliary path c and the secondary classification gap d on the front end side of the inner cylinder member 20 in the recess 21a inside the cylinder. The outer cylinder member 21 and the connecting cylinder member 22 projecting from the upper wall member 10 in communication with the inner cylinder member 20. The inner cylinder member 20, the outer cylinder member 21, and the connecting cylinder member 22 have flange portions 20a, 21b, and 22a in which the corresponding attachment end sides are bent. And the inner cylinder member 20 is arrange | positioned in the state by which the flange part 20a was fitted by the recess 10a with respect to the inner surface of the upper wall member 10. FIG. The connecting cylinder member 22 is arranged so that the inner diameter of the flange portion 22 a is located on the same axis as the through hole 5 and the inner cylinder member 20 with respect to the outer surface of the upper wall member 10. In this example, the fastener S1 is fastened and locked to the flange portion 22a, the corresponding portion of the upper wall member 10, and the flange portion 20a, so that the inner tube member 20 and the connecting tube member 22 are integrated with the upper wall member 10. Combined. On the other hand, after the outer cylinder member 21 is arranged so that the inner diameter of the flange portion 21b is located on the same axis as the through-hole 6 and the inner cylinder member 20 with respect to the outer surface of the lower wall member 11, the fastener S2 extends from the flange portion 21b. By being fastened and locked to the corresponding portion of the lower wall member 11, the lower wall member 11 is integrally coupled to the lower wall member 11.

(Operation) In the above jet mill, the raw material is supplied from the raw material supply means 3 to the inner peripheral side (grinding zone) of the main cavity chamber a. Then, the supplied raw material is accelerated in the pulverization zone formed in the inner peripheral side of the main cavity chamber a in the swirling flow of the high-pressure fluid injected from the plurality of nozzles 40 in the main cavity chamber a. Then, they are crushed while colliding with each other or colliding with the inner wall 12. The pulverized material is primarily classified in the classification zone formed at the center side of the main cavity chamber a, and in the process of reaching the inlet of the inner cylinder member 20 from the discharge auxiliary path c through the secondary classification gap d. Secondary classification is performed again, and finally the liquid is discharged to the outside through the inner cylinder member 20 and the connecting cylinder member 22.

  More specifically, in the above classification operation, the primary classification is performed in the same manner as in the past, and among the pulverized products that have entered the classification zone, the target particle size or a particle size close to the target particle size is directed toward the inner cylindrical member 20 side. Thereby, the coarse powder is thrown into the pulverization zone by the centrifugal force generated by the swirling and is pulverized again. A target particle size or a particle size close to the target particle size toward the inner cylinder member 20 enters the discharge auxiliary path c, enters the secondary classification gap d from the path c, and reaches the inlet of the inner cylinder member 20 again. After classification, only particles having a particle size or particle size closer to the intended purpose enter the same cylinder from the inlet of the inner cylindrical member 20 and are sent to the target location via the connecting cylindrical member 22 and a discharge pipe (not shown). The coarsely classified secondary powder is returned to the classification zone. Thus, in this structure, with a relatively simple configuration, in addition to the primary classification in the same classification zone as in the past, secondary classification is performed in the gap d provided on the downstream side of the discharge auxiliary path c. The desired pulverized product can be efficiently obtained with high accuracy while suppressing the variation in particle size or particle size.

  By the way, in the jet mill structure of FIGS. 1 and 2, the present inventors change the horizontal sectional area of the discharge auxiliary path c and the size of the secondary classification gap d, or change the length of the inner cylinder member 20. We investigated how classification accuracy would be when other conditions were the same. From the test, in terms of classification accuracy, the inner cylinder inner diameter is preferably set to about 1.1 to 1.2 times the inner cylinder outer diameter, and the length of the inner cylinder member 20 defines the main cavity chamber a. It is sufficient that the distance between the upper and lower wall members 10 and 11 is not less than the maximum distance, and 1.3 times or more of the upper and lower wall members 10 and 11 is more preferable. Of course, it goes without saying that this value varies depending on the raw material powder, the shape and capacity of the main cavity a, the strength of the swirling flow, and the like. Further, the present invention is not limited to the above-described embodiments, and it is sufficient that the requirements specified in claim 1 are satisfied, and the details can be variously modified and developed with reference to the above-described specific examples. It is.

It is a model longitudinal cross-sectional view of the jet mill of this invention form. It is sectional drawing along the AA line of FIG. It is a schematic cross section which shows a modification in the aspect similar to FIG.

1. Mill body (10 and 11 are upper and lower wall members, 12 and 13 are inner and outer walls)
2 ... discharge part (20 is an inner cylinder member, 21 is an outer cylinder member, 22 is a connection cylinder member)
3. Raw material supply means (30 is a supply pipe, 31 is a hopper, 32 is a nozzle)
4 ... injection means (b is sub-cavity chamber, 40 is nozzle, 41 is air supply pipe)
5-8 ... Through-hole a ... Main cavity chamber c ... Discharge auxiliary path d ... Secondary classification gap

Claims (2)

A mill main body forming a substantially annular cavity, a discharge portion provided substantially at the center of the cavity, a raw material supply means for introducing a raw material into the cavity, and swirling by a high-pressure fluid in the cavity A pulverizing zone for pulverizing the raw material introduced by the swirling flow, and a classification zone for allowing the pulverized material pulverized in the pulverizing zone to be discharged from the discharge unit In the forming jet mill,
The discharge section, of the upper and lower wall portion that defines a said hollow chamber, whereas the inner cylinder member is projected to the wall Ru extends to the other wall portion side so as to cross the hollow chamber in the longitudinal direction, the A bottomed cylindrical outer cylinder member provided on the other wall and projecting out of the cavity chamber, and a connecting cylinder member projecting outward from the one wall of the cavity chamber and communicating with the inner cylinder member And
The inner cylinder member has a cylindrical portion arranged in the recess of the outer cylinder member while maintaining a discharge auxiliary path and a secondary classification gap,
The discharge auxiliary path is a space formed between the outer periphery of the cylindrical portion and the inner periphery of the outer cylinder member;
The secondary classification gap is defined between the inner periphery of the recess of the outer cylinder member and a horizontal cross section along the tip of the cylindrical portion and the inner end surface of the recess facing the tip of the cylindrical portion. The jet mill is characterized in that the pulverized material enters the cylindrical portion of the inner cylinder member from the classification zone through the discharge auxiliary path and the secondary classification gap. 2. The jet mill according to claim 1, wherein the length of the cylindrical portion is 1.3 times or more of a maximum distance between the upper and lower wall portions defining the hollow chamber.

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