JP2006263680A - Dewatering cyclone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a water content separated from a pellet from being redeposited to remove it. <P>SOLUTION: A cylindrical first perforated cylinder 14, a second perforated cylinder 15 and a third perforated cylinder 16 are coaxially provided continuously inside a cyclone 4 having an inner diameter whose diameter is made smaller in turn. The wall face of each perforated cylinder is formed by a punching metal 17. A ring-like first step face 22 is provided between the first perforated cylinder 14 and the second perforated cylinder 15, and the first perforated cylinder 14 in its vicinity is provided with an air nozzle 23 circumferentially at a predetermined interval. Air flow ejected from each air nozzle accelerates a flow rate of swirl flow and also blows off the water content accumulating on the first step face. Similarly, a second step face 26 is provided between the second perforated cylinder 15 and the third perforated cylinder 16, and the second perforated cylinder 15 in its vicinity is provided with air nozzles 27 circumferentially at a predetermined interval. The upside of the first perforated cylinder 14 is provided with a supply port 19 for supplying the swirl flow conveying the pellet, and the third perforated cylinder 16 is provided with a suction port 30 for sucking inside air to accelerate the swirl flow. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to pellet dehydration for producing a secondary product such as a pallet by dehydrating a pellet with moisture attached, for example, by pulverizing or cutting a synthetic resin product, etc. For cyclones.

In recent years, when recycling recycled materials such as various types of used synthetic resin products, recycling that pulverizes and granulates the product and heat-dissolves the pellets into a mold and recycles them into secondary products such as pallets. The system is adopted.
Usually, when a pellet is produced by pulverizing and cutting a used synthetic resin product, water is washed to remove the surface of the synthetic resin product. Also, in the process of cutting and crushing synthetic resin products with a blade, cooling water is applied as coolant to lower the cutting heat of the blade, or the blades rub against each other to generate frictional heat, so cooling water is applied to lower the temperature. Treatments such as improving the durability of the blade are performed. For this reason, moisture adheres to the surface of the crushed pellets, cracks, and the like.
Moreover, such pellets can be passed through a sieve according to size by passing through a mesh. Further, the pellets are sorted by specific gravity by light weight. For example, since olefinic resins such as polyethylene and polypropylene float on the water surface, light weight pellets are collected along the flow of water. Then, the pellets are pneumatically transported and the water adhering to the surface or the like is scattered and evaporated, and then stored in a bag called a flexible container.
The pellets collected in this manner are heated and melted, filled into a molding machine, and molded to produce a secondary product such as a pallet. When the pellet is heated and melted, if moisture remains on the surface or inside of the pellet, the moisture evaporates and a foaming state called water foaming occurs, and the foamed gas floats on the surface of the secondary product, which causes the product to be damaged. This has the disadvantage of becoming a defective product. Moisture that floats on the surface of the secondary product appears to shine, so it is said to be silver streak (silvery), and the appearance becomes abnormal.

In order to improve such a problem, usually, the lid of the flexible container is opened to wait for natural evaporation. However, this means has a disadvantage that it takes time and cannot perform an efficient treatment, and that the pellets in the vicinity of the inside of the container and in the interior are difficult to dry compared with the pellets near the surface.
Alternatively, it is carried out by air transportation or by blowing air forcibly to dry the water, but such means also increase the number of times of air transportation and increase the cost, and the number of processes is increased. There is a disadvantage that it increases.
Furthermore, there is one in which a cyclone is connected to a centrifugal dehydrator, such as a synthetic resin chip dehydration apparatus described in Patent Document 1 below. In this device, even if water is generated due to heat generated during dehydration when pellets are loaded into a centrifugal dehydrator and the dehydration basket is rotated, the water is transferred from the through holes to the outside air by the swirling flow of air and pellets in the cyclone. It can be released, and the surface adhering moisture content of the synthetic resin pellet can be reduced.
JP 2004-275851 A

However, in Patent Document 1, the dehydrator using centrifugal rotation has a complicated structure because pellets are put into a dehydrated basket and the dehydrated basket is rotated to separate water from the mesh of the dehydrated basket by centrifugal force. There was a problem that cost was high.
Also, since the cyclone is a punched metal plate and has a tapered shape or a truncated cone shape, pellets and air are thrown into the cyclone and swirled. When repelling, the moisture adhering to the metal plate flows downward along the punched metal mesh, and adheres again to the pellets sent downward by a swirl, so that the moisture adhesion rate to the pellets cannot be reduced much. there were.

  In view of such circumstances, an object of the present invention is to provide a dehydration cyclone that can prevent moisture once separated from a pellet from reattaching to the pellet.

A dehydration cyclone according to the present invention is a dehydration cyclone in which air is supplied into a porous chamber together with a pellet containing moisture to generate a spiral flow to dehydrate the pellet, and the inner surface of the porous chamber is separated from the pellet. A stepped portion for receiving the moisture is formed.
According to the present invention, air is supplied into a porous chamber together with a pellet containing moisture to generate a spiral flow, and the pellet is collided with the porous chamber to separate the moisture from the pellet. The remaining part is blown outside through the through hole, and the rest flows down along the wall surface of the perforated metal or the like forming the porous chamber and accumulates in the step portion. Therefore, once separated water flows down and does not adhere again to the pellets transported along the spiral flow, the moisture can be reliably separated from the pellets.

  The dehydration cyclone according to the present invention can separate moisture from the pellets, and the separated moisture flowing on the inner surface of the porous chamber accumulates in the stepped portion, so that the once separated moisture adheres again to the pellets conveyed along the spiral flow. It is possible to reliably separate the moisture from the pellet.

In the cyclone for dehydration according to the present invention, the porous chamber is preferably cylindrical, and the pellets conveyed by the spiral flow easily collide with the porous chamber, and the separated water easily flows down to the step portion.
In addition, an air discharge port is disposed in the vicinity of the stepped portion in the porous chamber so that the air ejected from the air discharge port flows in the same direction as the spiral flow for transporting the pellet in the porous chamber and blows to the stepped portion. It is preferred that
As a result, the water separated from the pellets and collected in the stepped portion is blown off by the air from the air discharge port and blown to the outside of the through hole, and the spiral flow in the porous chamber gradually flows while drawing a spiral. Although it decelerates, it is accelerated by the air flow from the air discharge port, so that it advances while colliding the pellet with the porous chamber while suppressing the deceleration of the spiral flow.

Further, the porous chamber may be provided with a plurality of porous chambers having different inner diameters successively and in communication, and a step portion may be provided between two adjacent porous chambers. In this case, the adjacent porous chambers may be provided. Since the region of the difference between the inner diameters is a stepped portion, the flow of pellets and air due to the swirl flow can proceed without obstructing.
Further, a supply port for a spiral flow for conveying pellets and air is provided on the upstream side of one or a plurality of porous chambers, and a suction port for sucking and discharging air is provided on the downstream side, and air is sucked from the suction port. The swirl flow may be accelerated with
The swirl flow that conveys the pellet can be accelerated by the air flow rate of the upstream side supplied from the supply port by the air flow rate sucked from the suction port, so that the flow rate of the swirl flow can be suppressed from decreasing in the porous chamber. Further, the flow velocity of the spiral flow can be accelerated by the air flow from the air discharge port, and the flow velocity reduction is suppressed. As a result, the pressure in the one or more porous chambers can be maintained at atmospheric pressure or slightly negative pressure to suppress a decrease in the flow rate of the spiral flow.

Hereinafter, a dehydrating cyclone according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2 are process diagrams for secondary molding of synthetic resin pellets, FIG. 3 is a longitudinal sectional view of a cyclone for dehydration, FIG. 4 is an explanatory view including a cross section taken along line AA of FIG. Is an explanatory view including a cross section taken along the line BB, FIG. 6 is an explanatory view including a cross section taken along the line CC, and FIG. 7 is a bottom view of the cyclone.
In the pellet secondary forming apparatus 1 shown in FIG. 1 and FIG. 2, pellets containing water obtained by pulverizing and washing with water, for example, a synthetic resin product made of a primary product used in the previous process are transferred from the flexible container 2. A hollow tank 3 for receiving the pellets, a cyclone 4 for dehydrating the pellets supplied from the barrow tank 3, a tank 5 for storing the dehydrated pellets, a silo 6 for storing the pellets supplied from the tank 5, A pretreatment device 7 that removes metal pieces mixed in the pellets supplied from the silo 6 and a pellet supplied from the pretreatment device 7 are heated and melted and filled to form a secondary product such as a pallet. And a molding machine 8.

The pellets to be supplied to the cyclone 4 are in a state of containing water or in a state where the surface is wet even though the plastic resin product is pulverized, cut or washed, and the air is transported by air transportation. Will be supplied.
In addition, each means and apparatus from the barrow tank 3 to the molding machine 8 are connected by the air flow path 9, and each conveys a pellet by air. A roots blower 10 for discharging air of a predetermined pressure is provided on the upstream side of the air flow path 9. Further, a rotary valve 11 for preventing the air pressure in the air flow path 9 from being transmitted to each means and device such as a tank and a silo in each process from the barrow tank 3 to the molding machine 8 is provided. Are measured and supplied to the air flow path 9.

Next, the cyclone 4 for dehydration according to the present embodiment will be described with reference to FIGS.
The cyclone 4 is provided with a substantially cylindrical outer cylinder 12 extending in the vertical direction, and has a configuration in which three straight cylinders or cylindrical porous cylinders 14, 15, 16 (porous chambers) are coaxially connected to the inside thereof. The uppermost one is the first porous cylinder 14, the middle one is the second porous cylinder 15, and the lowest one is the third porous cylinder 16. The peripheral surface of each porous cylinder 14, 15, 16 is formed of a punching metal 17 in which a large number of through holes are perforated. The through holes are at least smaller than the outer diameter of the pellets to be charged. For example, when the average pellet size is 5 mm × 5 mm to 10 mm × 10 mm, the hole diameter of the punching metal 17 is set to about φ2 mm.
The uppermost first porous cylinder 14 is provided with a lid 18 on the upper surface, a supply port 19 is formed in the vicinity of the lid 18, and the inflow cylinder 20 connected to the supply port 19 is circular in a plan view shown in FIG. The first porous cylinder 14 is provided from the outside so as to extend in the tangential direction of the inner surface of the first porous cylinder 14. Therefore, the air flow including the pellets supplied from the inflow cylinder 20 into the first porous cylinder 14 via the air flow path 9 draws a spiral while forming a spiral flow along the inner surface of the first porous cylinder 14. To the third porous cylinder 16 (downward). Therefore, the pellets conveyed by the air flow are struck against the punching metal 17 of each of the porous cylinders 14, 15, 16, and the water adhering to the surface is separated, a part is blown outside from the through holes, and the rest is each porous It is transmitted to the inner surfaces of the cylinders 14, 15, 16 and flows down.
The inflow cylinder 20 is connected to the air flow path 9.

A ring-shaped first step surface 22 based on the difference in inner diameter is formed at the connecting portion between the first porous cylinder 14 and the second porous cylinder 15. The first step surface 22 stores water flowing down the inner surface of the first porous cylinder 14. A plurality of, for example, eight air nozzles 23,... Are attached to the first porous cylinder 14 near the first step surface 22 at a predetermined interval in the circumferential direction.
As shown in FIG. 5, each air nozzle 23 is attached in a tangential direction of the first porous cylinder 14 in a direction along the spiral air flow supplied from the supply port 19. Therefore, the spiral air flow from the supply port 19 is compensated for gradually decelerating as it goes downward, and the spiral flow is accelerated. Each air nozzle 23 is connected to an air supply source (not shown) via a tube 24.
Similarly, a ring-shaped second step surface 26 based on the difference in inner diameter is formed at the connection portion between the second porous cylinder 15 and the third porous cylinder 16. Moisture flowing down the inner surface of the second porous cylinder 15 is stored in the second step surface 26. A plurality of, for example, six air nozzles 27,... Are attached to the second porous cylinder 15 in the vicinity of the second step surface 26 at a predetermined interval in the circumferential direction.
As shown in FIG. 6, each air nozzle 27 is attached in the tangential direction of the second porous cylinder 15 in the direction along the spiral air flow supplied from the supply port 19. Therefore, the spiral air flow is compensated for being decelerated as it goes downward, the spiral flow is accelerated, and the moisture on the second step surface 26 is blown off to the outside. Each air nozzle 27 is connected to an air supply source (not shown) via a tube 28.

A suction port 30 is provided on the inner peripheral surface in the vicinity of the lower portion of the third porous cylinder 16 and is guided to the outside through the suction cylinder 31 and connected to a suction source (not shown). The air inside the third porous cylinder 16 is sucked through the suction port 30 to re-accelerate the internal spiral flow, and the air flow supplied from the supply port 19 is discharged to the outside. Thus, by maintaining the pressure in the first to third porous cylinders 14 to 16 at atmospheric pressure (positive pressure) or a small negative pressure, the pellets can be placed in the respective porous cylinders 14, 15, without reducing the speed of the spiral flow. It is made to collide with 16 repeatedly and a water | moisture content is isolate | separated.
The third porous cylinder 16 made of the punching metal 17 connects the discharge cylinder 33 having the same diameter to the lower side of the suction port 30 and drops the pellet so as to guide it to the lower tank 5. Further, a drainage port 34 is provided in the lower part of the substantially cylindrical space between the outer cylinder 12 and the first to third porous cylinders 14 to 16, and collides with each of the porous cylinders 14 to 16 to separate from the pellets. The discharged water can be discharged.

The cyclone 4 according to the present embodiment has the above-described configuration, and the operation will be described next.
For example, in the pellet secondary forming apparatus 1 shown in FIG. 1, the used primary product is crushed and cut into pellets, which are weighed from the flexible container 2 through the barrow tank 3 by the rotary valve 11 and placed in the air flow path 9. Sent out. The pellets are supplied to the cyclone 4 together with the air flow in a state where the surface is wetted by water at the time of washing, crushing or cutting.
In the cyclone 4, an air flow including pellets flows from the air flow path 9 through the supply port 19 of the first porous cylinder 14 in the tangential direction of the inner surface of the first porous cylinder 14, and enters the inner surface of the first porous cylinder 14. It moves to the lower second porous cylinder 15 side while swirling along the spiral. At that time, the pellets in the air flow collide with the punching metal 17 constituting the first porous cylinder 14, and a part of the water is blown outward from the through holes, and the remaining moisture is transferred to the first porous cylinder 14. It flows downward along the punching metal 17 and accumulates on the first step surface 22 held horizontally. Since the spiral flow flows downward while colliding with the inner surface of the first porous cylinder 14, the flow velocity is slightly reduced.
On the other hand, in the first porous cylinder 14 in the vicinity of the first step surface 22, since the air is blown out from the eight air nozzles 23 along the direction of the spiral flow, the spiral flow is accelerated, and the speed reduction can be prevented. Moreover, the water accumulated on the first step surface 22 is blown off by the discharge air from each air nozzle 23 and blown out to the outside of the first porous cylinder 14 through the through hole. Therefore, it is possible to prevent water flowing on the wall surface of the first porous cylinder 14 from dropping down and adhering to the pellet again.

Next, the pellets fed into the second porous cylinder 15 along the spiral flow also collide with the punching metal 17 in the second porous cylinder 15 and the moisture is separated, and a part of the pellets outward from the through holes, The rest descends along the second porous cylinder 15 and accumulates on the horizontal second step surface 26. Also in this case, since the air is blown out from the six air nozzles 27 provided in the second porous cylinder 15 along the direction of the spiral flow, the spiral flow is accelerated and the speed reduction can be prevented. Moreover, the water accumulated on the second step surface 26 is blown off by the discharge air from each air nozzle 27 and blown out to the outside of the second porous cylinder 15 through the through hole.
And since the air flow containing the pellet sent into the 3rd porous cylinder 16 without reducing speed is attracted | sucked from the suction port 30, it is discharged | emitted from the suction cylinder 31 without reducing speed as a spiral flow. The pellets removed from the swirl flow pass through the discharge tube 33 and fall into the tank 5 without adhering once separated water.
When the flow of air pumped by the Roots blower 10 is seen, since the pellets containing moisture flow from the tank 3 through the air flow path 9 and are sent to the dehydration cyclone 4, the air supplied to the cyclone 4 is considerably high. Contains moisture. Therefore, if the suction air from the suction port 30 is small, the dehydrated pellets sent from the cyclone 4 to the tank 5 are mixed with air containing a lot of mist-like water in the tank 5, and the moisture content of the pellets is reduced. Will rise. If the space between the cyclone 4 and the tank 5 is not airtight, air may flow into the discharge cylinder 33.
Therefore, in FIG. 3, the total air volume of the air volume supplied from the supply port 19 and the injection nozzles 23 and 27 and the amount of air blown up from the inside of the discharge cylinder 33 located below the suction port 30 to the suction port 30 is obtained. On the other hand, by setting the air volume sucked from the suction port 30 to be equal to or higher than that, the moisture flowing into the tank 5 can be suppressed as much as possible to increase the moisture removal efficiency of the pellets. In this case, the inside of the dehydrating cyclone 4 is in an atmospheric pressure state or a slightly reduced pressure (negative pressure) state.
Further, when the space between the cyclone 4 and the tank 5 is airtight, the amount of suction air from the suction port 30 may be equal to or greater than the total amount of air supplied from the roots blower 10 and the injection nozzles 23 and 27.

The pellets with reduced moisture adhering in this way are sequentially passed through the silo 6 and the pretreatment device 7 by the air flow in the air flow path 9, and further adhering moisture is reduced by evaporation and separation. Then, the pellets conveyed from the pretreatment device 7 to the molding machine 8 are heated and melted, filled in the molding machine 8, and molded as a secondary product such as a pallet. At that time, since the moisture content can be reduced to 0.1% or less by passing through the cyclone 4 or the like, when the molten pellet is filled in the molding machine 8 and heat-molded, water foaming is performed on the surface of the secondary molded product. This can prevent the product from being damaged. Further, it is possible to prevent a phenomenon in which a thin film called silver streak (silver) is generated on the surface of the secondary product to reflect light and shine.
In addition, the water blown away between each of the porous cylinders 14 to 16 and the outer cylinder 12 through the through holes is discharged from the drain port 34.

  As described above, according to the cyclone 4 according to the present embodiment, the swirl flow including the pellets in the first to third through-hole cylinders 14 to 16 is caused to flow through the air nozzles 23 and 27 in the vicinity of the first step surface 22 and the second step surface 26. Since the air can be accelerated by air suction through the suction port 30, the pellet can collide with the through-hole cylinders 14 to 16 at a high speed to separate the moisture. In addition, since the water once separated is collected at the first and second step surfaces 22 and 26 and blown off by the air nozzles 23 and 27, it can be prevented from falling down and reattaching to the pellets. Therefore, it is possible to suppress the occurrence of defective products due to water foaming or silver streak in the secondary product molded by the molding machine 8.

[Test example]
A dehydration test was performed using the cyclone 4 according to this example.
(1) Cyclone dehydration test The pellet as a test product is an arbitrary shape because it is a primary product made of an olefin-based synthetic resin cut and pulverized with a cutter, but the size of each pellet is 5 mm x 5 mm ~ The range was set to 10 mm × 10 mm. The diameter of each through hole of the punching metal 17 used in each of the porous cylinders 14 to 16 of the cyclone 4 was φ2 mm. The outer dimension of the outer cylinder 12 of the cyclone 4 is φ470 mm × height 1096 mm, the inner diameter dimension of the first porous cylinder 14 is φ330 mm × height 420 mm, the inner diameter dimension of the second porous cylinder 15 is φ270 mm × height 330 mm, The inner diameter of the three-hole cylinder 16 was φ220 mm × height 310 mm. The inner diameter of the air flow supply port 19 was φ100 mm, and the inner diameter of the suction port 30 was φ150 mm.
The flow rate of the spiral flow of air supplied from the supply port 19 in the cyclone 4 is 45 m / s, the air suction air volume from the suction port 30 is 25 m ³ / m, and the air injection speed of each of the air nozzles 23 and 27 is 200 m / s. It was. The processing amount of the pellet by the cyclone 4 was 5 t / hour.
The moisture content of each pellet before passing through the cyclone was 2.4%, which is a normal content rate, and the moisture content of each pellet after being treated with the cyclone 4 was 0.4% to 0.5%. And after that, the moisture content of the pellet was reduced to 0.1% in a state of being charged into the molding machine 8 via the silo 6 and the pretreatment device 7 via the air flow path 9. Therefore, when a pellet was supplied to the thermoforming machine to produce a secondary product, silver could not be visually confirmed on the surface.

(2) Silver confirmation test In addition, the visual confirmation test was performed about the magnitude | size of the silver streak (silver shape) generate | occur | produced on the surface of the shape | molded pallet (secondary product) with respect to the moisture content of the pellet supplied to the molding machine 8. . The results are shown in Table 1 below. When the moisture content of the pellets was 3% to 1%, large silver was confirmed, which was a defective product. When the moisture content of the pellet was 0.5%, some silver was confirmed, which was also a defective product. When the moisture content of the pellets was 0.3% and 0.1%, silver was not confirmed on the pallet, and it was a good product.

  Therefore, by dehydrating with the cyclone 4 according to this test example, the pellets having a moisture content of 2.4% can be reduced to 0.4% to 0.5%, and then the air is conveyed by the air flow path 9. As a result, the moisture content can be reduced to 0.1% when supplied to the molding machine 8, so that it was confirmed that silver streaks could be prevented from occurring in secondary products such as pallets. Therefore, by dehydrating the pellets with the cyclone 4, it is possible to efficiently treat the pellets with a moisture content of about 2.4% without the need to spontaneously evaporate the moisture or air transport again to blow away the moisture. .

In the above-described embodiment, the porous cylinders 14 to 16 are arranged in three stages as the cyclone 4 and the two step surfaces 22 and 26 are provided between the adjacent porous cylinders 14 to 16 so as to be dehydrated and accumulated. However, the porous cylinder constituting the cyclone may be set in two stages, and one step surface may be provided between the two porous cylinders. Alternatively, four or more porous cylinders may be provided to form three or more step surfaces.
Further, although the porous cylinders 14 to 16 are formed in a cylindrical shape (straight barrel shape) in the embodiment, they may be formed in a tapered shape instead of this, and in this case, the punching metal 17 is formed at the lower part of each tapered porous cylinder. What is necessary is just to provide the horizontal level | step difference surface which receives the isolate | separated water | moisture content which flows through the wall surface with a through-hole which consists of this. Note that the stepped surface may be formed so as to protrude from the intermediate portion in the axial direction of the porous cylinder, not the connecting portion between adjacent porous cylinders. In this case, it is preferable to provide the air nozzles 22 in the vicinity of the upper portion at a predetermined interval.

It is a figure which shows the one part process of the secondary shaping | molding apparatus of the pellet containing the cyclone by the 1st Example of this invention. It is a figure which shows the remaining processes of the secondary shaping | molding apparatus following FIG. It is a longitudinal cross-sectional view of a dehydration cyclone. It is explanatory drawing containing the AA line cross section of the cyclone shown in FIG. It is explanatory drawing containing the BB line cross section of the cyclone shown in FIG. It is explanatory drawing containing the CC line cross section of the cyclone shown in FIG. It is a bottom view of the cyclone shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Secondary molding apparatus 4 Cyclone 9 Air flow path 14 1st porous cylinder (1st porous chamber; porous chamber)
15 Second porous cylinder (second porous chamber; porous chamber)
16 Third porous cylinder (third porous chamber; porous chamber)
19 Supply port 22 First step surface (step portion)
23, 27 Air nozzle (Air outlet)
26 Second step surface (step)
30 Suction port

Claims (4)

  A cyclone for dehydration in which air is supplied into a porous chamber together with pellets containing moisture to generate a spiral flow to dehydrate the pellets, and a step portion for receiving moisture separated from the pellets is provided on the inner surface of the porous chamber. A cyclone for dehydration characterized by being formed.   The cyclone for dehydration according to claim 1, wherein the porous chamber has a cylindrical shape.   An air discharge port is disposed in the vicinity of the stepped portion in the porous chamber, and the air ejected from the air discharge port flows in the same direction as the spiral flow for transporting the pellet in the porous chamber and blows on the stepped portion. The cyclone for dehydration according to claim 1 or 2. The dewatering cyclone according to any one of claims 1 to 3, wherein the porous chamber is continuously provided with a plurality of porous chambers having different inner diameters, and the step portion is provided between two adjacent porous chambers. .

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