JP2010149090A - Air flow classifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air flow classifier which can classify powders sharply and accurately. <P>SOLUTION: A classification plate 2 is installed in a casing 1, a coarse powder outlet 3 is formed on the periphery of the classification plate 2, and a fine powder discharge pipe 4 is connected to the central part of the classification plate 2. In the casing 1, a primary classification chamber 5 is set on the upper side of the classification plate 2, and a secondary small diameter classification chamber 8 is set on the primary classification chamber 5. A plurality of air nozzles 15 are set at equal intervals on the periphery of the primary classification chamber 5, a solid-gas mixed fluid is jetted in the peripheral part circumference direction of the primary classification chamber 5 from each air nozzle 15, and the powder is whirled in the primary classification chamber 5 to be separated centrifugally into coarse powder and intermediate powder containing fine powder. The intermediate powder is whirled along the peripheral wall inner surface of the secondary classification chamber 8, high pressure air is jetted from a plurality of accelerating air nozzles 16 installed on the peripheral wall of the secondary classification chamber 8 during the whirling, and the whirling velocity of the intermediate powder is accelerated. The intermediate powder ascending while whirling in the secondary classification chamber 8 is moved inward in the radial direction along the ceiling surface and separated centrifugally into coarse powder by forming a strong downward whirling eddy in the central part of the secondary classification chamber 8, and fine powder is sucked into the fine powder discharge pipe 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an airflow classifier that classifies powder such as developing toner of a copying machine into fine powder and coarse powder.

  In an air classifier that rotates powder at high speed in a classification chamber formed inside the casing and centrifuges it into fine powder and coarse powder, it usually has a dispersion chamber and a single classification chamber, and the dispersion Since the powder dispersed in the chamber is guided to the classification chamber and the powder is classified, coarse powder is likely to be mixed in the fine powder, and sharp classification cannot be performed.

  For this reason, in a toner production plant used for an image forming apparatus such as a copying machine, the fine powder classified by the first airflow classifier is usually supplied to the second airflow classifier and classified again. ing. In this case, since two airflow classifiers are required, there is a problem that the equipment cost and the running cost increase.

  In order to solve such problems, the present applicant has proposed an airflow classifier in Patent Documents 1 and 2 that can perform a sharp classification process.

  FIG. 9 shows an airflow classifier described in Patent Document 1. In this airflow classifier, a primary classifying chamber 82 and a secondary classifying chamber 83 having a diameter smaller than that of the primary classifying chamber 82 are coaxially provided on a classifying plate 81 provided inside the casing 80, and the primary classifying chamber described above. A solid-gas mixed fluid of powder and high-pressure air is jetted from a plurality of jet nozzles 84 provided on the peripheral wall 82 and swirled into the primary classification chamber, and the powder is made into fine powder (hereinafter referred to as coarse powder and coarse powder). And the intermediate powder is allowed to flow into the secondary classification chamber 83, swirled in the secondary classification chamber 83, and the intermediate powder is centrifuged into fine powder and coarse powder. The fine powder that flows downward along the downward swirling vortex formed at the center of the classification chamber 83 and the primary classification chamber 82 is sucked into the fine powder discharge cylinder 85 connected to the central portion of the classification plate 81 and collected. I have to.

  FIG. 10 shows an air classifier described in Patent Document 2. In this airflow classifier, similarly to the airflow classifier shown in FIG. 9, a primary classifying chamber 92 on a classifying plate 91 provided inside the casing 90 and a secondary classifying chamber 93 having a smaller diameter than the primary classifying chamber 92. The tertiary classification chamber 97 is provided coaxially, and high-pressure air is injected into the primary classification chamber 92 from a plurality of air nozzles 94 provided on the peripheral wall of the primary classification chamber 92, or external air is sucked into the primary classification chamber 92. A swirling airflow is formed in each of the chamber 92 and the secondary classification chamber 93, and a powder is supplied from an annular powder supply header 95 provided on the outer peripheral portion of the peripheral wall of the secondary classification chamber 93 to a lower portion in the secondary classification chamber 93. The powder is swirled in the secondary classification chamber 93 to be centrifuged into coarse powder and intermediate powder, and the coarse powder flowing down into the primary classification chamber 92 is swirled in the primary classification chamber 92. Centrifugation into coarse powder and fine powder contained in coarse powder I have to so that.

  Then, the fine powder moving inward of the primary classification chamber 92 is caused to enter the secondary classification chamber 93 and merge with the intermediate powder, and the intermediate powder is removed by swirling movement in the secondary classification chamber 93 and the tertiary classification chamber 97. The coarse powder and the fine powder are centrifuged again, and the fine powder that flows downward along the downward swirling vortex formed at the center of the tertiary classification chamber 97, the secondary classification chamber 93, and the primary classification chamber 92 is classified into the classification plate 91. The fine powder discharge cylinder 96 connected to the center of the vacuum is sucked and collected.

  In any of the above airflow classifiers, the powder is primarily classified in the lower classification chamber, and the intermediate powder separated by the primary classification is secondarily classified in the upper classification chamber to obtain fine powder. There is a feature that a coarse classification process can be performed with very little contamination of the coarse powder or very little of the fine powder.

JP 2007-862 A International Publication No. 2007/145207 Pamphlet

  By the way, since any of the conventional airflow classifiers is configured to form a swirling airflow only by high-pressure air injected into the primary classification chambers 82 or 92 or air flowing from the outside, the primary classification chambers 82 and 92 and It is difficult to maintain a vigorous swirling flow over the entire secondary classification chambers 83 and 93, and as the swirling air flow rises, energy is consumed due to contact with the inner peripheral surface of the classification chamber and the momentum gradually weakens. Become.

  In particular, when the swirling airflow enters the secondary classifying chambers 83, 93 from the primary classifying chambers 82, 92, the swirling diameter decreases and the swirling speed increases, but as the inside of the secondary classifying chambers 83, 93 is decelerated, It becomes slower than the swirling speed of the swirling airflow at the air supply position for the primary classification chambers 82 and 92. For this reason, a large centrifugal force cannot be imparted to the powder in the secondary classification chambers 83 and 93, and there remains a point to be improved in applying a sharp classification.

  An object of the present invention is to classify the powder sharply with high accuracy so that the powder can always be swung at a high speed in the classification chamber of each stage.

  In order to solve the above-described problems, in the airflow classifier according to the present invention, a classification plate is provided in the casing, and a plurality of cylindrical classification chambers having a smaller diameter toward the upper stage are coaxially arranged on the classification plate. A swirling airflow forming air nozzle is installed at the bottom of the peripheral wall of the lowermost classification chamber, and high pressure air is injected from the air nozzle into the lowermost classification chamber, or external air is sucked into the outer periphery of each classification chamber. A swirling airflow that rises at the center and descends at the center is formed, powder is supplied into the swirling airflow, and the powder swirling with the swirling airflow is centrifuged into coarse powder and fine powder, and the outer periphery of the classification chamber The coarse powder that descends while swirling in the section flows out from the coarse powder discharge port formed between the outer periphery of the classification plate and the inner peripheral surface of the casing, and the fine powder that descends while swirling in the center of the uppermost classification chamber Fine powder discharge connected to the center of the classification plate In the airflow classifier adapted to be sucked and discharged into the inside, toward the turning direction of the swirling airflow swirling in the inner classification chamber on the peripheral wall of at least one other classification chamber other than the lowermost classification chamber A configuration in which a plurality of acceleration air nozzles that inject high-pressure air or suck external air to accelerate the swirling airflow is employed.

  In the airflow classifier configured as described above, high-pressure air is injected from the swirling airflow forming air nozzle toward the outer periphery of the lowermost classification chamber in a state in which suction force is applied to the fine powder discharge cylinder, or external air is applied. When sucked, a swirling airflow is formed in the lowermost classification chamber. The swirling airflow ascends in the lowermost classification chamber, reaches the ceiling surface of the classification chamber, flows in a radially inward direction, and moves to the position of the lower end opening of the next classification chamber. And moves upward while turning along the inner surface of the peripheral wall of the classification chamber.

  As described above, when the swirling airflow moves upward and hits the ceiling surface of the classification chamber, the direction of the swirling airflow changes inward in the radial direction, so that the swirling airflow is formed in the classification chamber of each stage. At this time, the swirling airflow gradually weakens as it reaches the uppermost classification chamber.

  Therefore, by injecting high-pressure air from the acceleration air nozzle provided on the peripheral wall of at least one other classification chamber other than the lowermost classification chamber to the inner classification chamber, or by sucking external air, The swirling airflow can be accelerated, and a vigorous swirling airflow can be formed.

  When the swirling airflow in the uppermost classification chamber rises and comes into contact with the ceiling surface, the direction changes radially inward. At this time, a suction force is applied to the fine powder discharge cylinder, and the suction force acts on the center part of the classification chamber of each stage. The flow changes downward in the center and descends while creating a swirling vortex.

  As described above, in a state where a swirling airflow is formed in the classification chamber of each stage, when powder is supplied into the swirling airflow, the powder swirls along the flow of the swirling airflow, and the classification chamber of each stage , The powder is centrifuged into coarse powder and fine powder.

  The coarse powder centrifuged in the lowermost classification chamber descends while turning around the outer periphery, and is discharged to the coarse powder discharge port. On the other hand, the intermediate powder as fine powder including coarse powder enters the classification chamber of the next stage and is classified again in the classification chamber, and the intermediate powder that continues to rise is classified one after another in the classification chamber on the upper stage side. .

  At this time, in at least one of the upper classification chambers excluding the lowermost classification chamber, the turning speed is lowered because the acceleration is accelerated by the high-pressure air ejected from the acceleration air nozzle or the sucked external air. The intermediate powder is effectively centrifuged into a fine powder and a coarse powder.

  The fine powder centrifuged in each stage of the classification chamber moves inward, descends on a swirl vortex formed in the center of the classification chamber, and is sucked and discharged from the fine powder discharge cylinder together with air.

  Here, when supplying powder to the swirling airflow, an annular powder supply header is provided around the outer peripheral wall of the lowermost classification chamber, and the powder is directed toward the circumferential direction of the inner periphery of the powder supply header. And a powder supply cylinder that supplies a solid-air mixed fluid of high-pressure air, and an air nozzle for forming a swirling airflow is connected to the inner peripheral wall of the powder supply header. A solid-gas mixed fluid may be injected into the room.

  An annular powder supply header is provided on the outer peripheral portion of the peripheral wall of the upper classification chamber located on the lowermost classification chamber, and the powder is supplied to the powder supply header in the circumferential direction of the inner outer periphery. A powder supply cylinder may be connected, a slit-shaped supply port may be formed in the inner peripheral wall of the powder supply header, and the supply port may be swirled into the upper classification chamber.

  As described above, in the airflow classifier according to the present invention, the acceleration air nozzle is provided on the peripheral wall of at least one other classification chamber other than the lowermost classification chamber, and the high-pressure air is supplied from the acceleration air nozzle to the classification chamber. As a result, a vigorous swirling airflow can be formed in the classification chamber of each stage, and the coarse powder is less likely to be mixed into the fine powder. The amount of fine powder mixed into the powder is reduced, and the powder can be classified sharply and with high accuracy.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3 show the air classifier A ₁ according to the present invention. The air classifier A ₁ has a casing 1, inside thereof is classifying plate 2 is provided.

  The upper surface of the classification plate 2 has a conical shape inclined with an upward gradient from the outer periphery toward the center, and an annular coarse powder discharge port 3 is provided between the outer periphery and the inner periphery of the casing 1. In the embodiment, the classification plate 2 has a conical shape, but may have a flat plate shape.

  The upper part of the fine powder discharge cylinder 4 is connected to the center of the classification plate 2. The fine powder discharge cylinder 4 has an L shape, and a tip portion penetrates a part of the casing 1 and faces the outside.

  A skirt portion 6 that forms a primary classification chamber 5 is formed between the casing 1 and the outer peripheral portion of the upper surface of the classification plate 2, and the inner side of the cylindrical portion 7 rising from the inner diameter portion of the skirt portion 6 is the secondary classification chamber 8. It is said that.

  Here, the skirt portion 6 has an inclination parallel to the classifying plate 2, but may be a horizontal plane having no inclination.

  The cylindrical part 7 has a ceiling wall 9 in the upper part, and a center core 10 is provided so as to penetrate the central part of the ceiling wall 9. The center core 10 is provided with a conical surface 11 at the lower end located in the secondary classification chamber 8. Further, exhaust holes 12 that open at the upper and lower ends of the center core 10 are formed on the axis of the center core 10.

  As shown in FIG. 4, the exhaust hole 12 may be omitted by providing a conical center core 10 at the center of the lower surface of the ceiling wall 9. The center core 10 may be cylindrical.

  An annular powder supply header 13 is provided on the outer periphery of the peripheral wall of the primary classification chamber 5, and a powder supply cylinder 14 is connected to the outer peripheral position of the powder supply header 13.

  A plurality of air nozzles 15 for swirling flow are provided at equal intervals on the inner periphery of the powder supply header 13. Each air nozzle 15 injects the solid-gas mixed fluid of the powder supplied into the powder supply header 13 and the high-pressure air toward the outer circumferential portion in the primary classification chamber 5. A swirling airflow is formed in the primary classification chamber 5 by jetting the mixed fluid.

  A plurality of acceleration air nozzles 16 are provided at equal intervals in the circumferential direction on the peripheral wall of the secondary classification chamber 8. The acceleration air nozzle 16 injects high-pressure air toward the outer periphery of the secondary classification chamber 8. The injection direction is the same as the swirling direction of the swirling airflow swirling in the secondary classification chamber 8.

Figure 5 shows a classification plant employing the air classifier A ₁ having the above-described configuration. In this classification the plant, connects the powder supplying device 20 to the powder supply tube 14 of the air classifier A _1. The powder supply device 20 sucks the powder stored in the hopper 23 by the high-pressure air injected from the air injection nozzle 21 into the powder supply pipe 22, passes through the powder supply pipe 22, and passes through the powder supply cylinder 14. To send it to.

Are classified by the air classifier A _1, fines are sucked and discharged to the fine powder discharge tube 4 is adapted to be fed into the cyclone separator 32 as a solid-gas separator from fine feed tube 31.

The cyclone separator 32 separates the mixed fluid mixed with fine powder into fine powder and air. Fine powder as a product is discharged from an outlet 33 at the lower end, and air is sent from an air supply path 34 to a bag filter 40 as a dust collector. Here, the air supply passage 34 is also the exhaust gas discharged from the exhaust hole 12 of the air classifier A ₁ is adapted to feed the bag filter 40.

The bag filter 40 collects the powder contained in the air. The clarified air is sucked by the blower 50 and discharged to the outside. 51 shows a blower for supplying high pressure air to the acceleration air nozzle 16 of the air classifier A _1.

Now, to run the blower 50 and 51, in a state that applies suction to the fine powder discharge tube 4, the powder and the high-pressure air solid-gas mixed fluid to the powder supply tube 14 of the air classifier A ₁ shown in FIG. 1 When supplied, the solid-gas mixed fluid is ejected from the plurality of air nozzles 15 in the circumferential direction of the outer periphery of the primary classification chamber 5.

  At this time, since the plurality of air nozzles 15 are provided at equal intervals, the solid-gas mixed fluid to be classified is supplied into the primary classification chamber 5 in a uniform state, and swirls at a high speed in the primary classification chamber 5. Create an air flow. The powder in the swirling airflow is centrifuged into coarse powder and intermediate powder by the swirling motion, and the coarse powder descends while swirling around the outer periphery of the primary classification chamber 5 and is discharged from the coarse powder discharge port 3. The

  On the other hand, the intermediate powder rises with the swirling airflow and moves in the radially inward direction when reaching the lower surface of the skirt portion 6. And if it moves to the position which opposes the lower end opening of the secondary classification chamber 8, most will move upwards, turning along the inner peripheral wall inner surface of the secondary classification chamber 8. FIG. A part of the fine fine powder moves toward the center of the casing 1 and is sucked into the fine powder discharge cylinder 4.

  When the intermediate powder swirls in the secondary classification chamber 8, since the high-pressure air is injected from the acceleration air nozzle 16 into the secondary classification chamber 8, the intermediate powder is accelerated and swirled at a high speed, and is included in the intermediate powder. The coarse powder is separated. The coarse powder descends along the outer peripheral wall and enters the primary classification chamber 5, and is classified again in the primary classification chamber 5.

  On the other hand, the fine powder rises while swirling in the secondary classification chamber 8, and changes its direction inward in the radial direction when reaching the lower surface of the ceiling wall 9.

  Here, if the intersection of the inner peripheral surface of the secondary classification chamber 8 and the lower surface of the ceiling wall 9 is angular, the direction change lacks smoothness, and powder adheres and accumulates at the intersection, Since there is a possibility that a peeled material may be mixed, it is preferable to round the intersection.

  The fine powder that has moved inward in the radial direction along the lower surface of the ceiling wall 9 changes its flow downward along the conical surface 11 of the center core 10. At this time, since the suction force of the blower 50 is acting on the fine powder discharge cylinder 4, the fine powder whose flow is changed downwardly descends while forming a swirl vortex. The inner diameter of the swirl vortex is a small diameter that is almost equal to the inner diameter of the fine powder discharge cylinder 4, and is very small compared to the swirl vortex diameter at the time of ascent. Effectively centrifuged.

  The separated coarse powder swirls and descends while spreading outward in the radial direction, reflows into the primary classification chamber 5, moves to the outer periphery, and is discharged from the coarse powder discharge port 3.

  On the other hand, the fine powder descends along the swirl vortex, or descends along the hollow portion formed at the center of the swirl vortex and is sucked into the fine powder discharge cylinder 4.

  As described above, the powder is centrifuged in the primary classification chamber 5 and the secondary classification chamber 8, and in the secondary classification chamber 8, the powder is centrifuged while being accelerated by the high-pressure air ejected from the acceleration air nozzle 16. Therefore, efficient classification can be performed, and a sharp classification process can be performed with little mixing of the fine powder on the coarse powder side and almost no mixing of the coarse powder on the fine powder side.

  In addition, the intermediate powder flowing into the secondary classification chamber 8 is classified in a state in which most of the coarse powder is removed and accelerated in the primary classification, and the swirl vortex formed in the center of the secondary classification chamber 8 Is a swirl vortex with a small inner diameter, and because the swirl speed is fast, it is possible to classify the powder with extremely high accuracy.

  As shown in FIG. 1, a plurality of acceleration air nozzles 17 are provided at equal intervals in the circumferential direction on the upper peripheral wall of the primary classification chamber 5, and high-pressure air is injected from each acceleration air nozzle 17 into the primary classification chamber 5. If the swirl flow is accelerated, the powder can be classified more effectively. The acceleration air nozzles 16 and 17 may be fed directly with compressed air from a compressor.

In Figure 5, but so as to impart suction to the air classifier A ₁ by the blower 50, an air classifier A ₁ by feeding high pressure air to the powder supply tube 14 from the blower 52 shown by a chain line in FIG The powder may be pushed inside and blown.

Further, as shown in FIG. 5, a jet mill 60 for pulverizing coarse powder discharged from the lower end outlet 1a of the casing 1 of the airflow classifier A ₁ is connected, and the powder pulverized by the jet mill 60 is used. fed from the circulation path 61 to the powder supply tube 14, may be fed back to the air classifier a _1.

As described above, crushing the treated powder by classification treatment by feeding again air classifier A _1, it is possible to obtain a product of accurate particle size distribution.

  Here, the peripheral walls of the primary classifying chamber 5 and the secondary classifying chamber 8 shown in FIG. 1 are combined with a plurality of split rings, and the primary classifying chamber 5 and the secondary classifying chamber are formed by increasing or decreasing the number of the split rings. Since the height dimension of 8 can be adjusted, the flow velocity of the swirling flow can be adjusted, so that the classification point can be adjusted.

In air classifier A ₁ shown in FIG. 1, is provided with the two classifying chamber of the classifying plate 2 primary classification chamber 5 on the secondary classification chamber 8, the number of the classifying chamber is not limited thereto. For example, in order from the bottom, the primary classification chamber 5, the secondary classification chamber 8, the tertiary classification chamber 18, and three classification chambers may be provided, and the powder may be tertiary classified.

  In this case, the inner diameter is reduced from the primary classification chamber 5 to the tertiary classification chamber 18. The center core 10 is provided at the center of the ceiling wall of the tertiary classification chamber 18.

Here, in the air classifier A ₂ shown in FIG. 6, as shown in FIGS. 6 and 7, an annular powder feed header 70 provided on the peripheral wall outer periphery of the tertiary classification chamber 18, the powder supply header 70 A plurality of powder supply cylinders 71 are connected to each other in the tangential direction, and powder is supplied from the powder supply apparatus 20 connected to each powder supply cylinder 71 into the powder supply header 70. The powder swirling is supplied into the tertiary classification chamber 18 through a slit-like supply port 72 formed in the inner peripheral wall of the powder supply header 70 in the circumferential direction.

  In this case, as shown in FIG. 8, a plurality of swirling flow air nozzles 73 are provided at equal intervals in the circumferential direction on the peripheral wall of the primary classification chamber 5, and high-pressure air is injected into the primary classification chamber 5 from each air nozzle 73. A swirling airflow is formed in the primary classification chamber 5.

In the airflow classifier A ₂ shown in FIG. 6, when high-pressure air is injected from the swirling flow air nozzle 73 and the acceleration air nozzle 16 into the primary classification chamber 5 and the secondary classification chamber 8, the primary classification chamber 5 and the secondary classification chamber 8. A swirling airflow is formed in the secondary classification chamber 8, and the swirling airflow in the secondary classification chamber 8 rises and enters the tertiary classification chamber 18. Thus, the swirling airflow is also formed in the tertiary classification chamber 18.

  As described above, when powder is supplied from the powder supply device 20 into the powder supply header 70 in a state where a swirling airflow is formed in each of the classification chambers 5, 8, 18, the powder is supplied from the supply port 72. The swirl flows into the tertiary classification chamber 18 and swirls on the flow of the swirling airflow formed in the tertiary classification chamber 18.

  By the swirling flow of the powder in the tertiary classification chamber 18, the powder is centrifuged into coarse powder and intermediate powder (fine powder partially containing the coarse powder), and the coarse powder descends while swirling. The primary classification chamber 5 and the secondary classification chamber 8 flow down into the primary classification chamber 5 and are dispersed and reclassified by the swirling airflow swirling in the secondary classification chamber 8 and the primary classification chamber 5. Fine powder is removed and swirled while swirling on the inner peripheral portion, and the coarse powder is discharged from the coarse powder discharge port 3.

  On the other hand, the fine powder separated from the coarse powder rises while swirling, enters the secondary classification chamber 8, and merges with the fine powder swirling in the secondary classification chamber 8.

  The fine powder that rises while swirling in the secondary classification chamber 8 enters the tertiary classification chamber 18 and merges with the intermediate powder, and the intermediate powder that rises while swirling in the tertiary classification chamber 18 is the ceiling of the tertiary classification chamber 18. When it reaches the surface, it turns inward in the radial direction along the ceiling surface.

  The intermediate powder moving radially inward along the ceiling surface changes its flow downward along the conical surface 11 of the center core 10. At this time, since the suction force is acting on the fine powder discharge cylinder 4, the intermediate powder whose flow has been changed downward is lowered while forming a swirling vortex.

  Since the inner diameter of the swirl vortex is very small compared to the swirl vortex diameter when ascending in the tertiary classification chamber 18, the flow speed of the swirl vortex is high, and the coarse powder slightly contained in the fine powder is effectively centrifuged.

  The separated coarse powder swirls and descends while spreading outward in the radial direction and re-enters the secondary classification chamber 8, while the fine powder descends on the swirl vortex and is sucked into the fine powder discharge cylinder 4. The

  Thus, the powder is continuously centrifuged several times in the primary classification chamber 5, the secondary classification chamber 8 and the tertiary classification chamber 18, and is injected from the acceleration air nozzle 16 in the secondary classification chamber 8. Because it is centrifuged in a state accelerated by high-pressure air, it enables efficient classification and enables sharp classification processing with almost no contamination of fine powder on the coarse powder side and coarse powder on the fine powder side. Can do.

  In FIG. 6, high-pressure air is jetted from each of the air nozzles 16 and 73 to form a swirling airflow in the primary classification chamber 5 and the secondary classification chamber 8, but suction applied to the fine powder discharge cylinder 4 A swirling airflow may be formed by sucking external air from the air nozzles 16 and 73 by force.

Schematic showing an embodiment of an air classifier according to the present invention Sectional view along the line II-II in FIG. Sectional view along line III-III in FIG. Schematic showing another example of air classifier Schematic diagram of a classification plant using the air classifier shown in FIG. Schematic showing another example of air classifier Sectional drawing along the VII-VII line of FIG. Sectional view along line VIII-VIII in FIG. Schematic showing a conventional air classifier Schematic showing another example of a conventional air classifier

Explanation of symbols

A ₁ airflow classifier A ₂ airflow classifier 1 casing 1a outlet 2 classification plate 3 coarse powder discharge port 4 fine powder discharge cylinder 5 primary classification chamber 8 secondary classification chamber 10 center core 12 exhaust hole 13 powder supply header 14 powder supply cylinder 15 Air nozzle for swirling flow 16 Air nozzle for acceleration 17 Air nozzle for acceleration 18 Tertiary classification chamber 32 Cyclone separator (solid-gas separator)
40 Bag filter (dust collector)
50 Blower 51 Blower 52 Blower 70 Powder Supply Header 71 Powder Supply Tube 72 Supply Port 73 Air Nozzle

Claims (3)

A classification plate is provided in the casing, and a plurality of cylindrical classification chambers having a diameter that decreases in size toward the upper stage are coaxially provided on the classification plate, and an air nozzle for forming a swirl airflow is provided at the lower peripheral wall of the lowermost classification chamber. High-pressure air is jetted from the air nozzle into the lowermost classification chamber, or external air is sucked into the classification chamber at each stage to rise at the outer periphery and form a swirling airflow that moves downward at the center, Powder is supplied into the airflow, the powder swirling with the swirling airflow is centrifuged into coarse powder and fine powder, and the coarse powder descending while swirling around the outer periphery of the classification chamber is separated from the outer periphery of the classification plate and the casing. The fine powder that flows out from the coarse powder discharge port formed between the peripheral surfaces and descends while swirling in the central part of the uppermost classification chamber is sucked and discharged into the fine powder discharge cylinder connected to the central part of the classification plate In the air classifier
High-pressure air is sprayed on the peripheral wall of at least one other classification chamber other than the lowermost classification chamber in the direction of the swirling airflow swirling in the inner classification chamber, or external air is sucked in. An airflow classifier provided with a plurality of acceleration air nozzles for accelerating the swirling airflow.   An annular powder supply header is provided around the outer periphery of the peripheral wall of the lowermost classification chamber, and the powder supplying header is supplied with a solid-gas mixed fluid of powder and high-pressure air in the circumferential direction of the inner periphery. A body supply cylinder is connected, and the swirling air flow forming air nozzle is connected to the inner peripheral wall of the powder supply header so that the solid-gas mixed fluid is supplied from the swirling air flow forming air nozzle into the lowermost classification chamber. The air classifier according to claim 1.   An annular powder supply header is provided around the peripheral wall in the upper classification chamber located on the lowermost classification chamber, and the powder is supplied to the powder supply header in the circumferential direction of the inner periphery. 2. A body supply cylinder is connected, and a supply port is formed in the inner peripheral wall of the powder supply header to swirl and flow the powder swirling in the same direction as the swirling airflow in the powder supply header into the upper classification chamber. The air classifier described in 1.

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