JP2014155901A - Cyclone classifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cyclone type powder classifier capable of enhancing classification efficiency by reducing a backflow region in a centrifugal separation chamber as much as possible.SOLUTION: In the cyclone type powder classifier where powders supplied into the centrifugal separation chamber in a cyclone column are separated to fine powders and coarse powders by swirling flow, a truncated cone-shaped rectification adapter is arranged at the top of an outflow pipe in the centrifugal separation chamber and a ring-shaped member with holes to take in outside air is arranged at the top of the cyclone column.

Description

  The present invention relates to a cyclone classifier using centrifugal force.

Conventionally, a cyclone classifier is known as a dry classifier for classifying powder (see, for example, Patent Document 1).
Such a cyclonic classifier performs classification by blowing powder into the upper part of the cyclone tower together with air, and has an advantage that the structure is simple and the burden of maintenance and inspection is small.

  Such classifiers are used in various industrial processes such as dust collection according to environmental regulations, particle size adjustment of abrasive materials for electronic materials, and separation of powder in resource recycling, but recently, 1.0 μm The following demands for particle classification are increasing, and improvement of the classification performance is desired.

As a factor that hinders the improvement of cyclone classification performance,
1) There is a region where the swirl flow in the cyclone is reversed.
2) The presence of particles discharged as fine powder from the outflow pipe without being affected by the swirling flow.

Note that the reverse flow of the swirling flow seems to be due to the turbulent flow caused by the collision of the downward flow and the upward flow.
On the other hand, in order to improve the efficiency of collecting the cyclone particles, as shown in FIG. 9, ideally, from the inflow pipe 2 for supplying the powder, into the centrifuge chamber 4 of the substantially cylindrical cyclone tower 3. It is known that a strong swirl flow 6 should be formed.

  However, if the swirling flow 6 flows backward in the centrifugal separation chamber 4 or if the swirling flow 6 is weak, the wound powder adheres to the outer peripheral surface of the outflow pipe 8 or the fine powder flows out. There is a problem in that it is discharged to the outside of the tube 8 as it is, and classification accuracy and classification efficiency are lowered.

  In addition, said backflow phenomenon can be confirmed by the visualization experiment using a bubble. That is, for example, if bubbles are attached in advance to a region where backflow is expected to occur, the cyclone is operated for a predetermined time, and then the remaining amount of bubbles is checked, the presence or absence of a backflow phenomenon can be confirmed. . As a result of experiments, it was confirmed that bubbles 9 were attached to the upper part of the outflow pipe 8 in the centrifugal separation chamber 4 where backflow was expected and the cyclone was operated for 30 seconds. As shown in FIG. 10, the bubbles 9 were attached. Bubbles 9 remained in the vicinity. As a result, a backflow is generated in the vicinity of the powder outlet of the inflow pipe 2, and this backflow causes a backflow phenomenon in the vicinity of the upper part of the outflow pipe 8, and as a result, the classification performance is impaired. It was done.

JP 2011-125801 A

  In view of such circumstances, an object of the present invention is to provide a cyclone type powder classification device that can reduce the backflow region in the centrifuge chamber as much as possible and improve the classification efficiency.

In order to achieve the above object, a cyclone type powder classifier according to the present invention comprises:
While supplying a powder having a particle size distribution to the centrifuge chamber of the cyclone tower having a substantially cylindrical peripheral wall via an inflow pipe to form a swirl flow in the centrifuge chamber,
In a cyclone type powder classifying apparatus that separates the powder into fine powder and coarse powder by sucking or discharging air in the centrifugal separation chamber through an outflow pipe communicating with the centrifugal separation chamber,
The inflow pipe communicates with the centrifuge chamber through an opening formed in the peripheral wall of the centrifuge chamber and is connected to the centrifuge chamber in a tangential direction.
Further, a rectifying adapter in the shape of a truncated truncated cone is placed on the upper part of the outflow pipe in the centrifuge chamber so that one end of the cut head side faces downward, and the cut head side Is arranged above the lower end of the outflow pipe located in the centrifuge chamber.

According to the present invention having such a configuration, the spiral of the swirling flow near the upper part of the centrifugal separation chamber is increased by the action of the rectifying adapter, and the backflow region can be reduced as much as possible.
As a result, a swirl flow is sufficiently generated around the upper part of the outflow pipe and can be guided downward without adhering fine particles.

In the present invention,
In the rectifying adapter formed in the truncated frustoconical shape,
A length protruding in the radial direction from the outer diameter of the outflow pipe at one end portion on the small diameter side of the truncated conical shape is a,
When the length protruding in the radial direction from the outer diameter of the outflow pipe at the other end portion on the large diameter side of the truncated truncated cone shape is b,
1.00 <b / a ≦ 2.00, preferably 1.29 ≦ b / a ≦ 1.57
It is preferable that it is the range of these.

It was confirmed by experiments that the classification performance is improved if b / a is set at such a ratio.
Here, in the centrifugal separator according to the present invention, a ring-shaped member is installed on the outer peripheral surface on the upper side of the centrifugal chamber, and air for introducing outside air to the ring-shaped member through the centrifugal chamber is introduced. It is preferable that a plurality of intake holes are formed.

With such a configuration, it has been confirmed by experiments that the particle size with a partial separation efficiency of 50% becomes small.
Furthermore, in the present invention, it is preferable that the air intake hole is formed in a tangential direction of the peripheral wall so as to follow the flow of the swirl flow.

With such a configuration, it becomes easy to take outside air into the centrifuge chamber.
In the present invention, the amount of the powder-containing air flowing into the centrifuge chamber from the inflow pipe is defined as Q (L / min),
When the amount of air flowing into the centrifuge chamber from the air intake hole of the ring-shaped member is q (L / min),
0.2 ≦ qc / Q [−] ≦ 0.8, preferably 0.2 ≦ qc / Q [−] ≦ 0.7.

  It has been confirmed by experiments that if outside air is introduced at such a ratio, it contributes to the improvement of the collection efficiency.

  According to the cyclone type powder classifying apparatus according to the present invention, the backflow region in the centrifuge chamber is reduced, and the powder does not remain attached to the upper part of the outflow pipe due to the rectification of the swirl flow in the centrifuge chamber. . As a result, the powder can be effectively guided downward, and the classification performance can be improved.

  In addition, the introduction of the outside air introduced from the air intake hole formed in the ring-shaped member makes it possible to increase the spiral of the swirling flow in the centrifugal separation chamber, and as a result, the particle collection efficiency can be improved. it can.

FIG. 1 is a schematic cross-sectional view of a cyclone type powder classification apparatus according to an embodiment of the present invention. FIG. 2 is a schematic sectional view of the cyclone tower shown in FIG. 3A is a schematic view showing a rectifying adapter installed on the upper part of the outflow pipe shown in FIG. 1, FIG. 3B is a top view of the rectifying adapter, and FIG. 3C is a cross-sectional view of the rectifying adapter. It is. FIG. 4 is a cross-sectional view of a main part of a cyclone type powder classifier equipped with a rectifying adapter according to an embodiment of the present invention. FIG. 5 is a graph of experimental results showing the relationship between pressure loss and 50% separation diameter when rectifying adapters of various shapes are installed. FIG. 6 is a schematic sectional view showing a cyclone classifier according to another embodiment of the present invention. FIG. 7 is a schematic sectional view of a ring-shaped member employed in the embodiment shown in FIG. FIG. 8 is a graph showing the total opening area of holes and the ratio of introduced air when holes are provided in the ring-shaped member. FIG. 9 is a schematic view showing the behavior of a conventional cyclone classifier. FIG. 10 is a schematic diagram of a visualization experiment showing a state after a bubble is attached to a portion where a backflow is considered to occur and is operated, which is a conventional example.

Hereinafter, a preferred embodiment of a cyclone type powder classification apparatus according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a cyclone type powder classifier 30 according to an embodiment of the present invention, and FIG. 2 is a schematic plan view of the cyclone tower 38 shown in FIG.

  The cyclone type powder classifier 30 includes a cyclone tower 38 having a substantially truncated cone shape whose apex is directed in the vertical direction. A centrifuge chamber 46 having a substantially cylindrical peripheral wall 42 is defined in the upper part of the cyclone tower 38. A collector 39 is provided at a lower portion of the cyclone tower 38 through a coarse powder outlet 52.

  An outflow pipe 48 is disposed on the central axis of the centrifuge chamber 46. The outflow pipe 48 extends downward to a position lower than the height of the inflow pipe 40 for supplying the powder into the centrifuge chamber 46, and the lower end of the outflow pipe 48 is opened into the cyclone tower 38 to be centrifuge chamber 46. The upper end of the outflow pipe 48 is extended outward from the upper part of the cyclone tower 38 to form a fine powder discharge port 50.

  Further, in the cyclone type powder classification apparatus 30 of the present embodiment, a rectifying adapter 54 constituting the main part of the present embodiment is installed on the upper outer peripheral surface of the outflow pipe 48 located in the centrifugal separation chamber 46.

Hereinafter, the rectifying adapter 54 will be described with reference to FIGS. 3 (A), (B), and (C).
As shown in FIGS. 3A, 3 </ b> B, and 3 </ b> C, the rectifying adapter 54 is formed in a truncated conical shape whose upper surface is larger in diameter than the lower surface.
The rectifying adapter 54 is attached to the outer peripheral surface of the outflow pipe 48 in a posture in which the cut end portion 54a on the head side faces downward. The outer diameter of the outflow pipe 48 is H.

Also, the length of one end portion (end portion on the small diameter side) 54a of the rectifying adapter 54 that protrudes in the radial direction from the outer diameter H of the outflow pipe 48 is a, and the radius is larger than the outer diameter H of the outflow pipe 48 of the other end portion 54b. When the length protruding in the direction is b,
1.00 <b / a ≦ 2.00, preferably 1.29 ≦ b / a ≦ 1.57.
Further, when the inner diameter of the substantially cylindrical portion (straight barrel portion) constituting the upper part of the cyclone tower 38 is D and the height of the rectifying adapter 54 is L, the relationship of 0.1 ≦ L / D ≦ 0.6 is established. It is preferable to satisfy.
In this embodiment, the inner diameter J of the inflow pipe 40 is 37 mm, the inner diameter D of the substantially cylindrical portion (straight barrel portion) constituting the upper part of the cyclone tower 38 is 72 mm, and the height L of the rectifying adapter 54 is 40 mm. Has been.

  Further, as shown in FIG. 1, in this embodiment, a fine powder collecting unit 51 is connected to a fine powder discharge port 50 of the outflow pipe 48 from a bag filter or the like, and a suction blower 53 is further connected. The suction blower 53 sucks the air in the centrifugal separation chamber 46 through the fine powder collecting part 51 and the fine powder discharge port 50. When suction is performed, the inside of the centrifugal separation chamber 46 becomes negative pressure.

  Further, in the cyclone type powder classification device 30 of the present embodiment, the powder to be classified stored in a hopper (not shown) is quantitatively discharged by the quantitative supply device 32 and, if necessary, the powder by the dispersion device 36. The body is dispersed in the air, and the dispersed powder-containing air is sucked into the centrifugal chamber 46 of the cyclone tower 38 via the inflow pipe 40 by suction by the suction blower 53. At this time, as shown in FIG. 2, since the inflow pipe 40 is arranged in a tangential direction with respect to the centrifugal separation chamber 46, a swirl flow R formed by powder and air is formed inside the centrifugal separation chamber 46. . Further, by installing a discharge blower (not shown) on the upstream side of the fixed amount supply device 32 instead of the suction blower 53, a swirl flow R made of powder and air is formed inside the centrifugal separation chamber 46. .

  The powder exposed to the swirling flow R is subjected to a separating action according to the particle size while being dispersed by swirling motion. As a result, fine powder having a particle size equal to or lower than the classification point is sucked into the outflow pipe 48 from the lower end of the outflow pipe 48 opened in the centrifugal separation chamber 46 together with the air flow, and the fine powder collection unit is passed through the fine powder outlet 50. 51 is collected.

  On the other hand, the coarse powder having a particle size larger than the classification point is not discharged upward from the fine powder outlet 50 but falls in the cyclone tower 38 having a substantially truncated cone shape, and is formed at the lower end of the cyclone tower 38. It is discharged from the coarse powder outlet 52 to the collector 39 and collected here.

Thus, in this embodiment, the powder having a particle size distribution is separated into fine powder and coarse powder.
Further, in this embodiment, the provision of the rectifying adapter 54 makes it possible to reduce the turbulent flow that has occurred so far due to the collision between the downward flow and the upward flow.

That is, in the vicinity of the upper part of the centrifugal separation chamber 46, an upward flow due to the suction blower 53 and a downward flow due to the swirl flow R are generated, but since the rectifying adapter 54 is disposed near the opening 43 of the inflow pipe 40, the swirl The disturbance of the flow R can be reduced.
The effect | action by this rectification | straightening adapter 54 can be confirmed by the visualization experiment using a bubble, for example.

  For example, as shown in FIG. 4, the rectifying adapter 54 is arranged on the upper part of the outflow pipe 48 located in the centrifuge chamber 46. And the bubble 9 was made to adhere so that the whole surrounding surface of the rectification adapter 54 might be covered similarly to the case of FIG. After the operation for 30 seconds, the state of the bubbles 9 was confirmed. As shown in FIG. 4, the bubbles 9 hardly remained and remained only slightly below the rectifying adapter 54.

  As a result of the visualization experiment using bubbles, it was confirmed that the backflow region of the swirl flow R was reduced as an effect of the rectifying adapter 54. That is, it becomes possible to generate a swirl flow R in the vicinity of the centrifuge chamber 46 of the inflow pipe 40, that is, near the upper part of FIG. 4, and the powder that has been easy to stay at that position by the swirl flow R until now. It was confirmed that it was led downward.

  In addition, in the shape of the rectifying adapter having the truncated frustoconical shape, a and b shown in FIG. 3C were changed, and what ratio of b / a was preferable was examined. Table 1 shows the dimensions and ratios.

As a result, it was confirmed that all but Type A ₃ were effective. Moreover, since type F, type G, and type H are preferable,
1.00 <b / a ≦ 2.00, preferably 1.29 ≦ b / a ≦ 1.57
It turns out that.

Also, the type A _3, E, with F, G, rectification adapter 54 H, shown in Figure 5 the results obtained by experiment in the pressure loss and the flow rate constant.
FIG. 5 is a result showing the relationship between the particle diameter of 50% partial separation efficiency and the pressure loss using the rectifying adapters 54 of types A3, E, F, G, and H in Table 1.

In FIG. 5, the horizontal axis indicates the ratio of b / a, the first vertical axis on the left indicates the particle diameter, and the second vertical axis on the right indicates the pressure loss.
From FIG. 5, it was found that the type G rectifying adapter can collect even the smallest particles.

In the above embodiment, the classification performance is improved by using the rectifying adapter 54, but the classification performance can also be improved by introducing outside air into the centrifuge chamber 46 from other than the inflow pipe 40. .
FIG. 6 shows a schematic view of an embodiment in which outside air is introduced into the centrifugal separation chamber 46 of the cyclone tower 38.

  In this embodiment, a ring-shaped member 60 is installed on the outer peripheral surface on the upper side of the cyclone tower 38 in such a manner as to expand the internal centrifugal separation chamber 46. It is the same.

A plurality of air intake holes 62 are formed in the ring-shaped member 60, and external air can be positively added into the centrifuge chamber 46 from the air intake holes 62.
As shown in FIG. 7, the air intake hole 62 formed in the ring-shaped member 60 is formed in the tangential direction of the peripheral wall 61 so as to follow the flow of the swirl flow R. The air intake holes 62 are not limited to the same diameter, and the opening on the outside air introduction side can be enlarged.

Therefore, the outside air introduced into the ring-shaped member 60 is absorbed substantially uniformly from the outer peripheral portion into the centrifuge chamber 46 as indicated by the arrow K in FIG.
Although the number of the air intake holes 62 is not limited, it is preferably formed at a point-symmetrical position with respect to the axis of the cyclone tower.

Qc (L / min), the amount of outside air introduced from the air intake hole,
When the amount of main compressed air introduced from the inflow pipe 40 into the centrifuge chamber 46 is Q (L / min),
It has been confirmed by experiments that the effect is in the range of 0.2 ≦ qc / Q [−] ≦ 0.8, preferably 0.2 ≦ qc / Q [−] ≦ 0.7.

  Table 2 is a list of samples in which the number (n) of holes provided in the ring-shaped member, the inlet width (W) of the holes, and the height (A) of the holes are changed.

It was investigated which type was preferable by using the ring-shaped members according to these shapes.
FIG. 8 is a graph showing the relationship between the diameter of the partial separation efficiency of 50% and qc / Q for each type in Table 2.
From FIG. 8, it was found that type C in Table 2 can separate the smallest powder.

  As described above, it has been found that when the ring-shaped member provided with holes is provided so as to expand the centrifugal separation chamber, the swirl flow becomes strong due to the outside air introduced into the inside. According to the result of the simulation, by introducing the outside air, the swirling flow R shown in FIG. 7 does not swivel in the vicinity of the outlet of the inflow pipe 40 but draws a large arc from the upper side to the lower side. It was found that a spiral was formed.

30 cyclone type powder classifier 38 cyclone tower 40 inflow pipe 42 peripheral wall 43 opening 46 centrifuge chamber 48 outflow pipe 54 rectifier adapter 54a one end 60 ring-shaped member 62 air intake hole R swirl flow

Claims (5)

While supplying a powder having a particle size distribution to the centrifuge chamber of the cyclone tower having a substantially cylindrical peripheral wall via an inflow pipe to form a swirl flow in the centrifuge chamber,
In a cyclone type powder classifying apparatus that separates the powder into fine powder and coarse powder by sucking or discharging air in the centrifugal separation chamber through an outflow pipe communicating with the centrifugal separation chamber,
The inflow pipe communicates with the centrifuge chamber through an opening formed in the peripheral wall of the centrifuge chamber and is connected to the centrifuge chamber in a tangential direction.
Further, a rectifying adapter in the shape of a truncated truncated cone is placed on the upper part of the outflow pipe in the centrifuge chamber so that one end of the cut head side faces downward, and the cut head side The cyclone type powder classifier is characterized in that one end of the cyclone is disposed above the lower end of the outflow pipe located in the centrifuge chamber. In the rectifying adapter formed in the truncated frustoconical shape,
A length protruding in the radial direction from the outer diameter of the outflow pipe at one end portion on the small diameter side of the truncated conical shape is a,
When the length protruding in the radial direction from the outer diameter of the outflow pipe at the other end portion on the large diameter side of the truncated truncated cone shape is b,
1.00 <b / a ≦ 2.00
The cyclone type powder classifier according to claim 1, characterized in that   A ring-shaped member is installed on the outer peripheral surface on the upper side of the centrifuge chamber, and a plurality of air intake holes that communicate with the centrifuge chamber and introduce outside air are formed in the ring-shaped member. The cyclone type powder classifier according to claim 1 or 2, characterized by the above.   The cyclone-type powder classifier according to claim 2, wherein the air intake hole is formed in a tangential direction of the peripheral wall so as to follow the flow of the swirling flow. Q (L / min), the amount of powder-containing air flowing into the centrifuge chamber from the inflow pipe,
When the amount of air flowing into the centrifuge chamber from the air intake hole of the ring-shaped member is qc (L / min),
The cyclone type powder classifier according to claim 3 or 4, wherein 0.2≤qc / Q [-] ≤0.8.

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