JP4982601B2 - Airflow separation device - Google Patents

Description

  The present invention relates to an airflow separation device used for separating and removing light impurities mixed in granular materials such as synthetic resin pellets by airflow.

  In general, synthetic resin pellets used as a raw material for resin molding such as injection molding are often pneumatically transported through pipes, but it is inevitable that impurities called floss are mixed during the transportation. This floss is mainly composed of a resinous component that has adhered to the inner wall of the tube due to contact friction to form a film-like film that has been peeled into a string or thread. It also includes powders that are generated due to fine dust, collisions between pellets, rubbing with the inner wall of the pipe, and the like, which cause various problems. For example, since floss is much easier to melt than pellets in terms of shape or size, in resin molding using pellets containing floss, the floss that melted first will be thermally deteriorated until the pellets melt, reducing the quality of the molded product And yield will be reduced. Further, when the type of resin to be transported is changed, the froth of the resin component before being peeled off from the inner wall of the pipe is mixed as an impurity, which also leads to a decrease in the quality of the molded product. Furthermore, the floss may be entangled with a rotary valve or the like, resulting in malfunction or clogging.

  Therefore, conventionally, as a floss separator for separating the floss from the pellets, the floss-mixed pellets sent from the air transport pipe are sent together with the air flow into a vertical cylinder with a reduced diameter at the lower part, and spirally formed in the vertical cylinder A cyclone type separation device is widely used in which a light floss is guided to an upper discharge port together with an air flow while a heavy pellet is dropped by its own weight and guided to a lower outlet. Further, the air transported as primary air is sent obliquely upward into the vertical cylinder together with the floss-mixed pellets, and the secondary air and further the tertiary air are separately introduced from the lower side of the vertical cylinder to thereby reduce the floss. A method of separating in two or three stages has also been proposed (Patent Documents 1 and 2). In this specification, the expressions “heavy” and “light” do not represent the specific gravity as the physical quantity of the object, but the degree of ease of floating due to the wind pressure from below, and the particle size and bulk density of the material with the same specific gravity. Is smaller, and the lighter the easier it is to receive air resistance.

JP 2004-267939 A JP 2004-313994 A

  However, in the conventional general-purpose cyclone separator, the free state floss can be easily separated from the pellet, but it is difficult to separate the floss adhering to the pellet, particularly the powdered floss. Further, in the conventional proposed method of separating the floss in two or three steps, the froth removal rate can be increased. However, the separation efficiency becomes difficult as the material supply speed increases, and the processing efficiency cannot be set large. Since the structure of the air and tertiary air introduction part is complicated, the manufacturing cost is high, and in order to increase the froth removal rate, the introduction air volume of the secondary air and the tertiary air is subtly corresponding to the introduction air volume of the primary air. There is a drawback that an advanced control mechanism is necessary for adjustment.

  In view of the above-described circumstances, the present invention sets a high processing efficiency as an airflow separation device for separating and removing light impurities mixed in granular materials such as the above-mentioned synthetic resin pellets by an airflow, and also controls it. An object of the present invention is to provide an easily and stably high contaminant removal rate and a structure that is simple and inexpensive to manufacture.

If the means for achieving the above object is shown with reference numerals in the drawings, the air flow separation device according to the invention of claim 1 is of a vertical cylindrical shape having an exhaust port 11 at the upper part and a material outlet 12 at the lower end. A vertically short cylindrical baffle cylinder 2 with its upper and lower ends closed is concentrically disposed in an intermediate portion in the separator body 1, and upper and lower spaces 31 and 32 in the separator body 1 are disposed around the baffle cylinder 2. An annular space 30 that communicates is configured, and the cross-sectional area of the annular space 30 is 40 to 80% of the cross-sectional area of the upper space 31;
A material supply port 13 is provided in the peripheral wall portion of the separator body 1 so as to open the material supply direction tangential to the annular space 30;
The upper end portion 21 of the baffle cylinder 2 protrudes upward in a conical shape at a cone angle of 40 to 80 °, and the material supply port 13a opens toward the cylindrical portion 20 of the baffle cylinder 2,
Material supply means (material supply pipe 13, blower B1) for supplying granular material g containing light impurities (coarse floss f, powdered floss p) to material supply port 13a along with the air flow of primary air A1, and separation Primary air / secondary air to be introduced into the separator body, comprising secondary air introduction means (blower B2, secondary air introduction pipe 4) for introducing the secondary air A2 into the lower space 32 in the main body 1 Is set to a ratio of 1/1 to 1/5,
The granular material g containing light impurities fed into the separator main body 1 from the material supply port 13 rides on the primary air A1 and the secondary air A2 blowing up from below and spirally rises while circling the annular space 30. The granular material g reaches the upper space 31 in the separator body 1 and drops as the air flow rate decreases, while the released light impurities are discharged from the exhaust port 11 on the spirally rising air flow. At the same time, light impurities adhering to the falling granular material g are separated by the stirring action of the air A1 and A2 in the annular space 32 and carried upward, and only the granular material g is in the lower space in the separator body 1. 32 is configured to fall to the material carry-out port 12.

A second aspect of the present invention is the air flow separation device according to the first aspect, wherein the discharge port 4a for the secondary air A2 has a plurality of openings opened at the upper end of the secondary air introduction pipe 4 disposed in the center of the separator body 1. The small holes 40 are used.

  Next, effects of the present invention will be described with reference numerals in the drawings. First, in the air flow separation device according to the first aspect of the present invention, the granular material g containing light impurities (coarse floss f, powdered floss p) fed into the separator body 1 from the material supply port 13 is transported by the transport medium. The primary air A1 and the secondary air A2 blowing up from below are lifted up the annular space 30 to reach the upper space 31 in the separator body 1. At this time, the primary air A <b> 1 fed from the material supply port 13 flows in the tangential direction of the separator body 1 at a position facing the cylindrical portion 20 of the baffle cylinder 2 and is forced to flow along the circumferential direction by the annular space 30. In addition, since the flow velocity is increased by the narrow annular space 30 around the cylindrical portion 31, a strong spiral upward flow is generated in combination with the secondary air A <b> 2 blown from below, and the exhaust gas is exhausted even when reaching the upper space 31. A spiral upward flow is maintained up to the mouth 11. In the upper space 31, the flow velocity of the upward flow is greatly reduced due to the expansion of the flow path area, so that the heavy granular material g falls off the upward flow and falls while the loose light impurities are in a spiral shape. It is reliably carried to the exhaust port 11 and discharged while riding on the upward flow. Moreover, in the transition portion from the annular space 30 to the upper space 31, the flow passage area continuously increases due to the conical upper end 21 of the baffle cylinder 2, and the rising speed of the air A gradually decreases. Therefore, it is difficult for the spiral upward flow of the air A in the upper space 31 to be disturbed, so that the particulate material g can be prevented from being carried into the turbulent upward flow and being transported to the exhaust port 11, and as much as possible. As the removal rate is improved, the processing efficiency can be further increased.

  Further, the granular material g often has a part of light impurities mainly composed of powdered floss p, but when the falling granular material g passes through the annular space 30, the material supply port 13. Because of the intense stirring action caused by the collision between the circulating flow of the primary air A1 and the rising flow of the secondary air A2 from below, the adhering light impurities easily separate from the granular material g and rise. The air A is carried upward and discharged from the exhaust port 11. Accordingly, only the granular material g descends the annular space 30 and reaches the lower space 32. However, the upward flow of the secondary air A2 is weak in the lower space 32 having a large flow path area, and further from the outlet 4a of the secondary air A2. However, since there is no such upward flow at the lower level, there is no concern that it will rise again, and the granular material g will surely fall to the material outlet 12 at the lower end and be carried out.

Thus, according to this air flow separation device, the air volume ratio between the primary air A1 and the secondary air A2 introduced into the separator body 1 is in a specific range, and the cross-sectional area of the annular space 30 and the upper space 31 is specific. Since it is in the ratio range, the spiral upward flow of the air A from the annular space 30 to the upper space 31 has an appropriate rising speed, and sufficient stirring action can be obtained in the annular space 30, and the baffle cylinder 2 Since the cone angle α of the conical upper end portion 21 is in a specific range, the air A decreasing speed gradient at the transition portion that continuously expands the flow passage area from the annular space 30 to the upper space 31 in the separator body 1. In addition to the fact that the spiral upward flow of the air A in the upper space 31 becomes more stable, the separation of the contaminants progresses more efficiently , and a stable high contaminant removal rate can be secured. Provision of material g You can achieve high processing efficiency by setting a large speed. In addition, this air flow separation device has a vertically short cylindrical baffle tube 2 arranged concentrically in the separator body 1 and introduces secondary air A2 into the lower space 32 in the separator body 1. Therefore, there is an advantage that the structure can be manufactured simply and inexpensively, the air volume of the secondary air A2 can be easily set, an advanced control mechanism is not required, and the equipment cost can be reduced accordingly.

According to the second aspect of the present invention, the secondary air A2 discharge port 4a is located at the upper end of the secondary air introduction pipe 4 disposed at the center of the separator body 1, so that the secondary air A2 to the lower space 32 is provided. Of the secondary air A2 blown from the lower space 32 to the annular space 30 becomes even in the circumferential direction, so that fine impurities separated in the annular space 30 drop into the lower space 32 and the lower space 32. The granular material g that has reached the upper limit 31 can be reliably prevented from rising again, and the spiral upward flow of the air A in the upper space 31 is further stabilized, so that the separation efficiency between the granular material g and the released light contaminants is further increased. Get higher. Further, since the granular material g falls through the annular space 32 to the peripheral side of the lower space 32, the shape of the discharge port 4 a is avoided by the plurality of small holes 40 . Since it is configured, it is difficult for the granular material g to enter, so that it is possible to avoid uneven discharge of the secondary air A2 due to the blockage or partial clogging of the discharge port 4a by the granular material g.

It is a principal part fracture front view of the whole airflow separator concerning one embodiment of the present invention. It is a cross-sectional arrow view of the XX line of FIG. It is a cross-sectional arrow view of the YY line of FIG. It is a vertical front view which shows typically the separation state of the granular material and light impurities by the same airflow separator.

  Hereinafter, an embodiment of an airflow separation device according to the present invention will be specifically described with reference to the drawings. As shown in FIG. 1, this airflow separation device is arranged concentrically at a vertically short cylindrical separator body 1 whose upper end is closed by an end plate 1 a and in the middle in the height direction of the separator body 1. The vertical and short cylindrical baffle cylinder 2, the secondary air introduction pipe 4 that has entered the lower part 1 b of the separator body 1 with a reduced diameter from the outside, and the lower end of the separator body 1 are connected and integrated. And a rotary valve 5.

  The separator body 1 is provided with an exhaust port 11 opened laterally at the top, the lower end facing the rotary valve 5 constitutes a material carry-out port 12, and the material supply along the tangential direction at the outer periphery of the intermediate portion in the height direction The tube 13 is integrally projected. In the separator main body 1, an annular space 30 is formed between the inner periphery of the separator body 1 and the outer periphery of the baffle cylinder 2 in the intermediate portion in the height direction, and the upper space 31 and the lower space 32 are interposed via the annular space 30. And communicate with each other. The material supply port 13 a of the material supply pipe 13 is opened at a position near the upper portion of the annular space 30 so that the material supply direction is tangential to the annular space 30.

  The baffle cylinder 2 is configured such that both ends of the cylindrical portion 20 are closed by conical upper and lower end portions 21 and 22, and as shown in FIG. In each (three in the figure) attachment protrusions 23, the attachment protrusions 23 are attached to the support protrusions 14 protruding from the inner periphery of the separator body 1 via bolts and nuts 24. Since the bolt insertion portions of the support protrusions 14 of the separator main body 1 are vertically elongated holes 15 (see FIG. 1), the baffle cylinder 2 is vertically adjusted within the range of the elongated holes 15. Is possible.

  The secondary air introduction pipe 4 penetrates the peripheral wall portion of the lower portion 1b of the separator body 1 from the outside, and is bent upward at the center position in the separator body 1 and the upper end of the pipe body 40 The secondary air A2 discharge port 4a is constituted by a large number of punch holes in the cap 41. The pipe body 40 of the secondary air introduction pipe 4 is welded and fixed at a portion penetrating the peripheral wall portion of the separator body 1, and as shown in FIG. The discharge port 4a is fixed so as to be arranged at the center of the separator body 1 by a plurality of (four in the figure) horizontal support pieces 42 which are bridged with equal distribution in the circumferential direction between the inner periphery and the inner periphery. .

  The rotary valve 5 includes a plurality of blade plates 5a (four in the figure) arranged radially around the horizontal rotation axis, and is separated between the blade plates 5a facing upward by being rotated by a motor or the like. The granular material g (see FIG. 3) that has fallen from the material outlet 12 of the container body 1 is accommodated, and the granular material g is discharged from the outlet 5b that opens downward when rotated and turned downward. During driving and stopping, the blade 5a is always air-locked between the material outlet 12 and the outlet 5b.

  In order to separate and remove light impurities from the granular material such as synthetic resin pellets by the air flow separation device having the above configuration, an air transport pipe L is connected to the material supply pipe 13 as shown in FIG. The loaded material M is placed on the primary air A1 fed from the blower B1 of the material supply means, passes through the air transport pipe L and the material supply pipe 13, and is passed through the material supply port 13a to the annular space 30 in the separator body 1. Continuously. At the same time, the primary air A2 fed from the blower B2 of the secondary air introduction means is continuously upward from the center of the lower space 32 in the separator body 1 through the secondary air introduction pipe 4 through the discharge port 4a. To release.

  The material M fed into the annular space 30 from the material supply port 13a is a mixture of coarse floss f and powdered floss p as light impurities to be separated and removed into the granular material g to be recovered. It rides on the primary air A1 that is a transport medium and the secondary air A2 that blows up from below, and ascends the annular space 30 to reach the upper space 31 in the separator body 1. At this time, the primary air A1 fed from the material supply port 13 flows in the tangential direction into the annular space 30 and is forced to flow along the circumferential direction due to the annular shape of the annular space 30, and in the narrow annular space 30 Since the flow velocity is increased, a strong spiral upward flow is generated in combination with the secondary air A2 blowing from below, and a stable spiral upward flow is maintained up to the exhaust port 11 even when reaching the upper space 31. However, in this upper space 31, the flow velocity of the upward flow is greatly reduced due to the enlargement of the flow path area from the annular space 30, so that the heavy granular material g immediately escapes from the upward flow as the primary separation zone Z <b> 1. While falling, the released light impurities are reliably transported to the exhaust port 11 and discharged while riding on a stable spiral upward flow.

  In addition, the granular material g often has a part of light impurities mainly composed of the powdered floss p, but when the granular material g falling from the primary separation zone Z1 passes through the annular space 30. In addition, a vigorous stirring action is caused by the collision between the circulating flow of the primary air A1 fed from the material supply port 13 and the upward flow of the secondary air A2 from below. Therefore, in this annular space 30, as the secondary separation zone Z2, the light impurities adhering to the falling granular material g are easily separated and moved upward by the rising air A (primary air A1 + secondary air A2). And is discharged from the exhaust port 11, and only the granular material g descends and reaches the lower space 32. Since the upward flow of the secondary air A2 is weak in the lower space 32 with a large flow path area, the particulate material g that has reached the lower space 32 is not likely to turn up again, and the material outlet 12 at the lower end is surely provided. And is taken out from the outlet 5b by the rotary drive of the rotary valve 5.

  Therefore, according to this air flow separation device, the amount of introduced air of the secondary air A2 is set so that the rising speed of the air A on the lower side of the upper space 31 in the separator body 1 is lower than the floating speed of the granular material g. If set, light contaminants such as coarse floss f and powdered floss p can be separated and removed with extremely high efficiency and stability, and a high processing efficiency can be achieved by setting a large supply speed of the granular material g. In addition, this air flow separation device has a vertically short cylindrical baffle tube 2 arranged concentrically in the separator body 1 and introduces secondary air A2 into the lower space 32 in the separator body 1. Therefore, there is an advantage that the structure can be manufactured simply and inexpensively, the air volume of the secondary air A2 can be easily set, an advanced control mechanism is not required, and the equipment cost and running cost can be reduced accordingly. is there.

  The width of the annular space 30 in the separator body 1 is not particularly limited, but it is recommended that the cross-sectional area be in the range of 40 to 80% with respect to the cross-sectional area of the upper space 31. Further, it is recommended that the air volume ratio of the primary air A1 / secondary air A2 is in a range of 1/1 to 1/5. That is, the difference in the rising speed of the air in the annular space 30 and the upper space 31 is moderate depending on the former cross-sectional area ratio, and the spiral rise of the air A from the annular space 30 to the upper space 31 is determined by the latter air volume ratio. The flow is at a moderate upper layer velocity, which provides greater throughput with a stable high contaminant removal rate.

  In the air flow separation device of the present invention, the upper and lower end portions 21 and 22 of the baffle cylinder 2 are preferably convex, and the upper end portion 21 is particularly preferably conical as in the embodiment. This is because the conical upper end portion 21 prevents the granular material g and impurities from accumulating at the upper end portion 21, and the transition from the annular space 30 in the separator body 1 to the upper space 31. Since the flow passage area continuously increases at the portion, and the rising speed of the air A gradually decreases at the transition portion, the spiral upward flow of the air A in the upper space 31 is disturbed. This is because the particulate material g can be prevented from being entrained in the turbulent upward flow and carried to the exhaust port 11, thereby improving the contaminant removal rate and increasing the processing efficiency.

  By making the upper end portion 21 of the baffle tube 2 conical in this way, the first separation zone Z1 of the upper space 30 of the separator body 1 becomes the upper end of the cylindrical portion 20 of the baffle tube 2 as shown in FIG. To the conical apex of the upper end 21 and an airflow decelerating zone Z12 above the apex.

  Here, the conical upper end 21 of the baffle cylinder 2 is preferably an acute angle having a cone angle α in the range of 40 to 80 °. If the cone angle α of the upper end portion 21 is set to an acute angle in this way, the airflow deceleration zone Z11 becomes longer, and the decrease in the rising speed of the air A in the airflow deceleration zone Z11 is moderated accordingly. The spiral upward flow of the air A in the separation zone Z1) is further stabilized, and separation of light impurities such as the loose coarse floss g and the powdered floss p proceeds efficiently.

  On the other hand, the lower end portion 22 of the baffle cylinder 2 has a downward convex shape, so that the secondary air 2 </ b> A discharged from the discharge port 4 a disposed at the center of the lower space 32 in the separator body 1 blows up to the annular space 30. The resistance at the time is reduced, and the upward flow of the secondary air 2A is stabilized accordingly. Thus, the downward convex shape of the lower end portion 22 includes a conical shape and a convex spherical shape, but a conical shape is preferable from the machining surface, and an obtuse angle of conical angle β90 ° or more, more preferably 100 to 150 °. A conical shape is recommended. This is because the transition portion from the annular space 30 to the lower space 32 is short and the pressure gradient in the transition portion becomes steep because the lower end portion 22 has an obtuse conical shape. This is because the upward wind pressure with respect to the granular material g falling to 32 is suddenly reduced, so that the re-raising of the granular material g can be surely prevented.

  In the above embodiment, the mounting position of the baffle cylinder 2 in the separator main body 1 can be adjusted up and down, and the vertical space 30 above and below the annular space 30 around which the granular material g and the primary air A1 fed from the material supply port 13 circulate. Since the width changes, there is an advantage that the spiral upward flow in the primary separation zone Z1 can be easily set according to the particle size, specific gravity, supply speed, and the like of the granular material g.

  It is recommended that the secondary air A2 discharge port 4a be composed of a plurality of small holes opened at the upper end of the secondary air introduction pipe 4 arranged at the center of the separator body 1 as in the embodiment. Is done. One of the advantages is that the discharge amount of the secondary air A2 in the lower space 32 due to the discharge of the secondary air A2 from the central portion, and hence the flow rate of the secondary air A2 that blows up from the lower space 32 to the annular space 30 is obtained. Even in the circumferential direction, the fine impurities separated in the annular space 30 can be reliably prevented from dropping into the lower space 32 and the particulate material g reaching the lower space 32 can be prevented from rising again, and the air in the primary separation zone Z1 can be prevented. Since the spiral upward flow of A is further stabilized, the separation efficiency between the granular material g and the released light impurities is higher. Still another advantage is that the granular material g falls through the annular space 30 of the secondary separation zone Z2 to the peripheral side of the lower space 32, so that the discharge port 4a in the center is avoided, Since the discharge port 4a is a small hole, it is difficult for the granular material g to enter, and therefore, uneven discharge of the secondary air A2 due to blockage or partial clogging of the discharge port 4a by the granular material g can be avoided.

  In the embodiment, the material can be continuously carried out in an air-locked state by the rotary valve 5 provided at the material carry-out port 12. However, the airflow separation device of the present invention may be configured to carry out the material uncontinuously. For example, an opening / closing means such as a shutter or a damper is provided at the material outlet 12, and during the airflow separation, the granular material g falling in an air-locked state by closing the opening / closing means is stored, and after a predetermined amount of airflow separation is completed. The opening / closing means may be opened to carry out the material, and in this case, the amount of processing at one time can be increased by setting the volume of the storage portion large. In addition, as a material of the separator body 1, a metal material such as stainless steel is usually used, but glass, ceramic, synthetic resin, and the like can also be used. Therefore, in the separator main body 1 made of an opaque material, a viewing window fitted with a transparent plate may be provided at an important point so that the separated state can be visually recognized from the outside. In addition, the detailed configuration of the airflow separation device of the present invention can be variously modified in addition to the embodiment.

[Real machine test]
When the following two kinds of synthetic resin pellets P1 and P2 were removed from each of the following two kinds of synthetic resin pellets P1 and P2 under the following processing conditions using an airflow separation device of the following equipment specifications, the separation and removal rate was any of the pellets P1 and P2. Was almost 100%.

<Synthetic resin pellet>
Pellets P1 ... polyethylene pellets (average diameter about 3 mm, average length about 3 mm), floss contamination rate: average about 0.1 wt%
Pellets P2: Polypropylene pellets (average diameter of about 3 mm, average length of about 3 mm), froth mixture ratio: average of about 0.1% by weight

<Device specifications>
Separator body 1
Total length: about 2000 mm, inner diameter in the upper space 31: 400 mm
Distance from upper end of main body to center of material supply port 13a: about 1250 mm
Distance from the upper end of the main unit to the upper end of the reduced lower part 1a: about 1580 mm
Baffle tube 2
The outer diameter of the cylindrical portion 20: 250 mm, length: 250 mm
The cone angle α of the upper end portion 21 is 60 °, and the cone angle β of the lower end portion 22 is 120 °.
Upper end height of the cylindrical portion 20 with respect to the center of the material supply port 13a: 60 mm
Secondary air inlet tube Small diameter of discharge port 4a: 2mm
Distance between the top end of the porous cap 41 and the top end of the lower end portion 22 of the baffle cylinder 2: 45 mm
Ratio of the cross-sectional area of the annular space 30 to the upper space 31: about 60%

<Processing conditions>
Supply rate of granular material g: 22.5 kg / min Supply rate of primary air A1: 5 m ³ / min, supply rate of secondary air A2: 14 m ³ / min Floating speed of granular material g: about 7 m / sec Air rising speed in zone Z12: about 2.5 m / sec

  The air flow separation device of the present invention is suitable for separating and removing light contaminants mixed in granular materials such as synthetic resin pellets by air flow, but it is possible to use a mixture of granular materials and powders as well as sizes and forms. It can also be used to separate a light material and a heavy material as a treatment object by mixing a mixture of different materials having greatly different air resistances.

DESCRIPTION OF SYMBOLS 1 Separator main body 11 Exhaust port 12 Material carry-out port 13 Material supply pipe (material supply means)
13a Material supply port 2 Baffle tube 20 Cylindrical portion 21 Upper end portion 22 Lower end portion 30 Annular space 31 Upper space 32 Lower space 4 Secondary air introduction pipe (secondary air introduction means)
4a discharge port α, β cone angle A air A1 primary air A2 secondary air B1 blower (material supply means)
B2 blower (secondary air introduction means)
f Coarse floss (light impurities)
g granular material M material p powdered floss p (light impurities)

Claims (2)

A vertically short cylindrical baffle tube with the upper and lower ends closed is concentrically arranged in the middle of the vertical cylindrical separator body with an exhaust port at the top and a material outlet at the bottom, and around this baffle tube An annular space communicating with the upper and lower spaces in the separator body is configured, and the transverse area of the annular space is 40 to 80% of the transverse area of the upper space,
A material supply port that is opened so that a material supply direction is a battle direction with respect to the annular space is provided on the peripheral wall portion of the separator body,
The upper end portion of the baffle cylinder projects upward in a conical shape with a cone angle of 40 to 80 ° , and the material supply port opens facing the cylindrical portion of the baffle cylinder,
Material supply means for supplying particulate material containing light impurities to the material supply port with the air flow of primary air, and secondary air introduction means for introducing secondary air into the lower space in the separator body The primary air / secondary air volume ratio to be introduced into the separator body is set to a ratio of 1/1 to 1/5,
Particulate material containing light impurities fed into the separator body from the material supply port rises in a spiral manner while circulating around the annular space on the primary air and the secondary air blowing from below. The granular material reaches the upper space in the vessel body and drops as the air flow rate decreases, while the loose light impurities are discharged from the exhaust port on the spirally rising air flow and fall down Light impurities adhering to the material are separated by air stirring action in the annular space and carried upward, and only the granular material falls in the lower space in the separator body and reaches the material carry-out port. An airflow separation device configured.   2. The air flow separation device according to claim 1, wherein the secondary air discharge port includes a plurality of small holes opened at an upper end portion of a secondary air introduction pipe disposed in a central portion of the separator body.

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