JPS6036170B2 - How to remove fine powder from granular material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for separating and removing fine powder contained in granules of synthetic polymers such as polyester and polyamide.

Among polyester and polyamide, fishing nets, ropes,
Polymers used in a wide range of general industrial materials, such as tire cords, are usually cooled once after completing the polymerization reaction, turned into chips, and then sent to a drying process to remove moisture.

To be used as the above-mentioned industrial materials, the chips are sent to a batch-type rotary vacuum dryer or a continuous fluidized bed to undergo solid phase polymerization at high temperature and high vacuum to increase their intrinsic viscosity. It will be done.

As described above, polyester and polyamide polymer chips used as general industrial materials are handled more frequently as chips than those used as fibers, so they undergo various processes such as chip transportation, drying, and solid phase polymerization. During this time, a large amount of fine powder is generated due to collision between chips or equipment.

This fine powder has an abnormally high melting point compared to normal product chips when the chips are put in an extruder to prevent threads, causing uneven viscosity of the molten polymer and causing thread breakage. Therefore, there are many process losses and the yield of the product is also reduced. In addition to the above-mentioned fine powders, some are also generated when the chips are made into cooled chips, and are separated and removed using a sieve, cyclone, etc. before being sent to the drying process.

However, such fine powders are generated in large quantities during the drying process and solid phase polymerization process rather than during the cooling chip process, and moreover, the size of the fine powder is less than a certain level, especially if it passes through a 24-mesh line. size (hereinafter 24
It has been found that fine powder (smaller than mesh) has a significant effect on thread protection condition.

Conventionally, fine powders have been separated and removed using sieves, cyclones, etc. as mentioned above, but due in part to electrical coupling due to charging of the powder particles, the fine powders described above have not been sufficiently removed. At present, the removal effect has not been achieved. In view of the current situation, the inventor of the present invention has conducted extensive studies on a method for efficiently removing fine powder from powder and granules, and has found that by ejecting gas from below to the falling powder and granules to cause interaction between the two, the inventors have found that It was discovered that the separation of fine powders can be carried out extremely effectively, and this led to the present invention.

That is, the present invention provides a method for removing fine powder from a synthetic polymer powder formed into a chip shape, in which a separation chamber having gas inflow and outflow holes is provided above and below the dispersion. After colliding with the dispersing body and dispersing the powder, the powder is brought into contact with a gas flow rising in the opposite direction while the powder is falling.
The gas is vacuum-suctioned from the suction hole through a fine powder collector, and the powder is discharged from the lower end of the separation chamber.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a process diagram suitable for carrying out the present invention. In the figure, the synthetic polymer powder (usually several flat rectangular or circular cross-section bodies) supplied from another process to the hopper 2 through the transport pipe 1 is transferred to the separation chamber located below by the rotary valve 3. 4 is continuously supplied in fixed quantities. The separation chamber 4 is provided with a spray nozzle 6 having a discharge head 6' in which a double cone-shaped dispersion material 5 is perforated with a large number of small holes below the center line of the dispersion material 5. The powder particles dropped through the supply pipe 7 located above the line collide with the dispersion body 5,
The reaction scatters in all directions and separates fine powders that adhere or are mixed together. Large particles scatter farther than small particles, but as shown in Figure 2, air or nitrogen gas sent through a conduit is injected from below the dispersion through the spray nozzle 6. The separated fine powder interacts with this rising air current, and the fine powder is carried upward by the rising air current, while other powder particles fall downward and are discharged from the outlet 8 at the lower end. A gas outflow hole 9 connected to a vacuum generator 11 via a fine powder collector 10 is provided in the upper part of the separation chamber 4, and the upward airflow that has captured the fine powder is accelerated by the vacuum suction force. It flows towards the outflow hole 9 and is led through the conduit 12 to the concentrator 101 where the fine powder is removed. What is important here is that the fine powder cannot be sufficiently removed only by injecting gas from below the dispersion body 5 with the spray nozzle 6 and vacuum suction from above.

It is necessary to apply vacuum from the top to induce acceleration.
Next, the powder discharged from the outlet 8 is forced by a blower 13 and sent to the next process through the piping at the switching valve 14, or from the switching valve 14 through the circulation piping 15 to the cyclone 1.
After being sent to hopper 6 and separated from the compressed air body, it is again supplied to hopper 2. By passing the material through the separation chamber multiple times in such a circulation system, the separation effect is greatly improved. Note that 17 is an air supply pipe. The method described above involves removal during the circulation of the granules, but it is also possible to remove the granules as described above during the transfer of the granules to another storage hopper or the like, i.e. during one normal period. The method is basically the same.

When such a removal method as in the present invention is carried out, 80% of the fine powder in the granular material is 24 mesh or less.
It is possible to remove the above, and the yarn protection condition is also improved significantly, and process loss is reduced.

Further, the removal effect according to the present invention will be specifically explained below.

Using the process and equipment shown in Figures 1 and 2, 4x
The fine powder in the 4×2 rectangular polyester chips was removed by changing the processing amount, the number of circulations, the amount of transportation, the amount of air pressure injected from the nozzle, etc. The results are shown in Table 1. The main dimensions of the equipment used are as follows.

Hopper 2: Capacity 300 Rotary valve 3: Capacity 1~
20kg/min Separation chamber 4 (unit side) Total length (height from outlet 8 to center of outflow hole 9): 700 Monthly length x maximum diameter (inner diameter) x parallel length: 550 x
260 x 150 Exit height: 1100 Outflow hole diameter: 1600 → 55 small (outlet) Dispersion body 5: Total length x maximum diameter: 200 x 140 small Dispersion head 6': Total length x maximum diameter: 40 x 50 small hole diameter x number: 1.5
0 x 60 Supply pipe: Total length x Flea: 400 x 850 Vacuum generator 11: Capacity 8/min x 2300 skin Aq Blower 13: Capacity 20/min x 800 skin Aq Table 1 In this way, the powder and granules are By circulating several times, preferably 10 times or more, fine powder of 24 mesh or less is reduced to 80%.
It can be seen that the above amount is removed.

In addition, the removal effect of powder and granules in one pass is about the same as that of circulation when the amount of powder and granules transported is small, but
As the amount of transport increases, the effect decreases.

In order to increase the removal effect of 80% or more in one pass, it depends on the amount of compressed air and the pressure of the compressed air, but generally 20k9/m
jn or less is desirable.

The removal effect due to circulation is usually 50k9/mi.
Up to n, it does not depend on the amount of transport, but rather depends on the number of circulations. In order to increase the removal effect of Sariko fine powder, it is effective to increase the amount and pressure of compressed air, but at the same time, the amount of powder and granules that come together with the fine powder increases, resulting in product loss. , the range shown in this example is preferable.

That is, the air volume and pressure of compressed air or nitrogen that can remove fine powder of 24 mesh or less in the powder or granular material very efficiently and does not entrain the powder or granular product is as follows: When pressure is expressed in terms of side Aq, its product is 2
000 to 500M is preferable. As described above, by the removal method according to the present invention, fine powder of 24 mesh or less is removed by about 8
When the powder from which 0% or more was removed was applied to an extruder to prevent threads, the thread protection was extremely good and the product yield was improved compared to when powder was removed using a conventional removal method.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing the implementation of the present invention, and FIG. 2 is an explanatory diagram of a separating section. 4... Separation chamber, 5... Dispersion, 6...
Spray nozzle, 7...supply pipe, 8...outlet, 9...outflow hole, 10...collector, 11
・・・・・・Vacuum generator. Tsutomu Figure 1 Figure 2

Claims (1)

[Claims] 1. A method for removing fine powder from a powder or granule of a synthetic polymer formed into chips, comprising: providing a separation chamber having gas inflow and outflow holes above and below the dispersion; The powder is collided with the dispersion body and dispersed, and while the powder is falling, it is brought into contact with a gas flow rising in the opposite direction, and then the gas is passed from the outlet hole through a fine powder collector into a vacuum. A method for removing fine powder from a powder or granule material, which is characterized by suction and discharging the powder or granule material from the lower end of a separation chamber. 2. A method for removing fine powder from a powder or granular material according to claim 1, wherein the fine powder has a size of 24 meshes or less. 3. A method for removing fine powder from a powder or granular material according to claim 1 or 2, wherein the dispersion has a double conical shape.