JP2764607B2 - Method and apparatus for drying powders - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for drying granules such as synthetic resin pellets by hot air.

[Conventional technology]

2. Description of the Related Art Conventionally, as a method of drying a granular material, for example, there are a method in which the granular material is simply dried with hot air and a method in which the granular material is simply heated and dried in a vacuum state.

The hot air drying of the powder in the former method is normal pressure drying, and the vacuum drying in the latter method is performed by storing the powder in a vacuum tank, and the vacuum tank removes moisture removed. Does not have an effective means for discharging water to the outside.

[Problems to be Solved by the Invention] By the way, in the former conventional method as described above, since the powder and granules are simply dried with hot air dried, it can be dried relatively quickly up to a certain degree of drying. As described above, this hot-air drying takes a long time to obtain a product with a high degree of drying due to normal-pressure drying, and is inefficient.

Further, in the latter method, the powder is simply heated and dried in a vacuum state, and the vacuum tank is not provided with an effective water discharging means for discharging the removed water to the outside. The water in the powdery granules is not sufficiently discharged from the vacuum tank, that is, it takes a long time to obtain a powder having a high degree of drying.

The present invention has been made on the background of such a conventional technique, and an object of the present invention is to provide a method and an apparatus for drying a granular material capable of obtaining a product having a high degree of drying in a relatively short time.

[Means for solving the problem]

According to the present invention, the granular material is supplied into a stationary drying hopper, the air is first dehumidified and dried, and then the granular material is first dried with hot air generated by drying. And drying the dried powder and granules in the drying hopper under a reduced pressure of 110 to 210 Torr under a reduced pressure of 110 to 210 Torr in a ventilation state of the dried hot air generated by heating after dehumidifying and drying the air. Drying method.

Further, the present invention provides a hot-air drying unit for primary drying a powder and a granule with a dry hot air generated by heating air after dehumidifying and drying in a stationary drying hopper; Air drying and decompression drying section for drying under reduced pressure of 110 to 210 Torr under a reduced pressure of 110 to 210 Torr in a ventilation state of dried hot air generated by heating after dehumidifying and drying the air in the drying hopper. It is intended to provide an apparatus for drying a granular material to be dried.

[Action]

In the method for drying a granular material according to the present invention, the granular material is first dried first with a dry hot air. This removes most of the water adhering to and / or contained in the granules.

Thereafter, the primary dried powder and granules are dried under reduced pressure in a hot air ventilation state, and then subjected to secondary drying. As a result, the residual moisture of the granular material is discharged to the outside according to the flow of the hot air in a ventilation state under reduced pressure, so that the residual moisture of the granular material can be efficiently removed.

Further, in the granule drying apparatus of the present invention, first, in a hot air drying section, hot air in a dry state is blown onto the granules to perform primary drying, whereby most of the particles adhered to and / or contained in the granules are dried. Remove moisture.

After that, the primary dried powder and granules are dried under reduced pressure in a ventilation and reduced pressure drying section in a hot air ventilation state, and then dried secondarily to remove residual moisture of the powder and granules.

By doing so, a powder having a high degree of dryness can be obtained in a relatively short time.

〔Example〕

Hereinafter, the method and apparatus for drying a granular material according to the present invention will be described in detail with reference to the drawings, but the present invention is not limited to this example.

In describing the examples, a method and an apparatus for drying a granular material for drying synthetic resin pellets will be described as an example.

First, an apparatus for drying a granular material used in the method for drying a granular material of the present invention will be described.

As shown in FIG. 1, the apparatus for drying a granular material according to the present invention includes a raw material supply unit 10, a drying hopper 20, a dry hot air unit 30, and a reduced-pressure ventilation drying unit 40.

The raw material supply unit 10 is a supply unit for supplying the granular material F serving as a raw material into the drying hopper 20. The raw material storage tank 11 and the granular material F in the raw material storage tank 11 are charged into the drying hopper 20. Prior to this, a hopper loader 12 for primary stocking and a raw material supply suction device 13 for sucking and supplying the granular material F to the hopper loader 12 are connected to each other.

In addition, as the powder F of this embodiment, for example, talc and / or mica, charcoal and the like added to polypropylene resin, polyamide resin, modified polyphenylene ether, polybutylene terephthalate, polyethylene terephthalate, polyethylene ether ketone, polyether Although pellets made of synthetic resin such as ketone are used, it is not necessarily limited to this, and other powders such as silica ceramics and zirconia, which do not like high-humidity drying, and fine ceramics and foods are used. The body can also be used.

The drying hopper 20 is a hopper for drying the granules F supplied from the hopper loader 12, and a receiving hopper 21 for the dried granules F is disposed on the discharge side of the granules F of the drying hopper 20. Have been.

The hot-air drying unit 30 is a primary drying unit that supplies dried hot air into the drying hopper 20 to dry the powder F stored in the drying hopper 20, and performs preliminary dehumidification of the external air taken in. Refrigerating machine 31, a dehumidifier 32 for highly dehumidifying the external air preliminarily dehumidified by the air refrigerating machine 31, and a circulation blower 33 for blowing the external air dehumidified by the dehumidifier 32 to the drying hopper 20 side. And a heater 34 for heating the dehumidified external air blown by the circulation blower 33, and a drying hopper 20
A hot air jet nozzle that jets external air stored in the inside and heated by the heater 34 into the drying hopper 20.
35, and a cyclone 36 for separating the hot air (external air) exhausted from the drying hopper 20 and the fine particles F mixed in the external air. Are connected to each other.

A part of the hot air (external air) separated and exhausted from the cyclone 36 is sucked into the circulation blower 33, while the rest is exhausted outside.

The hot air exhausted to the outside is returned to the air refrigerator 31 again.
It may be returned to and reused.

The aeration reduced-pressure drying unit 40 is a secondary drying unit configured to dry the granules first-dried in the hot-air drying unit 30 under reduced pressure in a hot-air ventilation state, and is connected to the drying hopper 20. And a needle valve 42 that keeps the inside of the drying hopper 20 in a hot air ventilation state while maintaining a predetermined reduced pressure state in the drying hopper 20 by reducing the amount of external air blown.

The needle valve 42 of this embodiment is arranged in a line between the dehumidifier 32 and the heater 34 in parallel with the circulation blower 33, but is disposed between the line from the external air inlet to the drying hopper 20. If so, the installation location is not limited.

In the figure, 101 is a valve for opening and closing the air supply for stopping the supply of the raw material and disposed between the line between the hopper loader 12 and the suction device 13 for supplying the raw material, and 102 is a powder disposed between the line and the hopper loader 12 and the drying hopper 20. A valve for charging the granules F, 201 is a valve arranged between the drying hopper 20 and the receiving hopper 21 for discharging the dried granules F to the hopper 21, and 301 is a dehumidifier 32. A valve for external air blowing disposed between the line of the circulation blower 33 and 302, a valve for external air blowing disposed between the line of the circulation blower 33 and the heater, and 303 is provided between the drying hopper 20 and the cyclone. A valve 304 for exhausting hot air (external air) disposed between the cyclone 36 and the circulation blower 33 is a valve for adjusting the amount of exhaust circulating air, 305 disposed between the cyclone 36 and the circulation blower 33. Is the dust collection at the bottom of the cyclone Valve for externally discharging end, the valve for discharging the air in the drying hopper 20 and drying hopper 20 disposed between lines of the vacuum pump 41 401, 402 a heater 34 and a needle valve 42
And a valve for opening the ventilation pressure reducing line disposed between the lines.

Next, a method for drying a granular material according to an embodiment of the present invention using the apparatus for drying a granular material will be described.

In the method for drying a granular material according to an embodiment of the present invention, as shown in FIG. 1, first, in a hot-air drying unit 30, primary air is dried by blowing hot air (external air) in a dry state on the granular material F. This removes most of the water adhering to and / or contained in the granules.

Specifically, the raw material supply suction device 13, the air refrigerator 31, the dehumidifier 32, the circulation blower 33, and the heater 34 are operated in advance,
And while closing the valves 101, 201, 305, 401, 402,
The valves 102, 301, 302, 303, 304 are opened.

By the operation of the raw material supply suction device 13, the granular material F in the raw material storage tank 11 is supplied into the hopper loader 12, and then the granular material F in the hopper loader 12 is charged into the drying hopper 20.

The valve 102 is closed when the drying hopper 20 is full.

In parallel with this, the external air sucked into the hot-air drying unit 30 by the circulation blower 34 first passes through the air refrigerator 31 and is preliminarily dehumidified, then is highly dehumidified by the dehumidifier 32, and is sent to the heater 34. It is hot weathered.

Next, the hot-airized external air that has passed through the heater 34 is jetted through the hot-air jet nozzle 35 into the drying hopper 20 into which the powder F has been charged, and the powder F is added to the outside.
Next, it is dried.

Next, in the hot air (external air) after the primary drying of the granular material F, the fine powder of the granular material F is separated and removed by the cyclone 36, and a part thereof is reused by the circulation blower 33. The rest is exhausted to the outside.

Note that the hot air exhausted to the outside is returned to the air refrigerator 31 again.
It may be blown to and reused.

Next, the primary-dried powder F is dried under reduced pressure in a ventilation vacuum drying section 40 in a hot-air ventilation state and dried secondarily to remove residual moisture of the powder F.

Specifically, first, valves 102, 201, 301, 302, 303, 3
04, 305, and 402 are closed, the valve 401 is opened, and the circulation blower 33 is deactivated, and the vacuum pump 41 is activated to evacuate the drying hopper 20.

After that, the valve 402 is opened, the amount of the external air that has been dehumidified is reduced by the needle valve 42, and then the needle valve is opened again.
The external air squeezed by 42 is heated by a heater 34 to generate hot air, and the hot air is blown into a reduced-pressure drying hopper 20 by a hot air jet nozzle.
Blow through 35 for secondary drying. The drying under reduced pressure in a hot air ventilation state is performed under reduced pressure of, for example, 110 to 210 Torr. The external air sucked by the vacuum pump 41 is exhausted outside.

As described above, by drying the primary-dried powdery granules F under reduced pressure in a hot-air-ventilated state, not only can the powdery powders F be dried well under reduced-pressure drying, but also the drying hopper 20 for drying the hot air in a ventilated state. Since the moisture evaporated inside is discharged to the outside without remaining, the drying efficiency of the granular material F becomes better as compared with simple hot air drying or vacuum drying.

By doing so, a powder having a high degree of dryness can be obtained in a relatively short time.

In addition, for example, 400 kg of polypropylene resin granules F, to which talc and mica having an initial moisture content of 600 ppm are added, can be dried to about 200 ppm by drying for 1 hour with the granule drying device of the present embodiment, and even in the rainy season, Granular powder F having a water content of 1,500 ppm can be dried to about 500 ppm.

Next, while closing the valves 401 and 402, a predetermined valve is opened to make the inside of the drying hopper 20 normal pressure, and then the valve 201 is opened to open the dried powdery granules F in the drying hopper 20. And is discharged into the hopper 21.

In this example, in order to further improve the drying efficiency, these primary drying and secondary drying are performed as one cycle, and several cycles are performed. Although the discharge is performed in a divided manner as described above, the present invention is not limited to this, and the drying can be performed in one cycle, and the dried granular material F can be discharged at a time.

The embodiments of the present invention have been described above. However, the present invention is not limited thereto, but includes any changes in the configuration and operation within the scope not departing from the gist of the present invention.

For example, it is not necessary to limit the specific method of drying the granular material to the method of the embodiment, and any method may be used as long as it performs hot air drying and aeration reduced pressure drying.

Further, the specific drying device for the granular material does not need to be limited to the one in this embodiment, and may be any device as long as it has a hot air drying unit and a ventilation reduced pressure drying unit. Good.

Furthermore, in describing this example, a method and an apparatus for drying a granular material for drying a synthetic resin pellet were taken as an example. However, the present invention is not limited to this. It can also be adopted in a method and an apparatus for performing the above.

〔The invention's effect〕

Since the present invention is such a method and an apparatus for drying a granular material, an effect that a granular material having a high degree of drying can be manufactured in a relatively short time can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an apparatus for drying a granular material according to an embodiment of the present invention. F; granular material 30; hot air drying section 40; ventilation reduced pressure drying section

Continuation of the front page (72) Inventor Masahiko Saito 2-1 Okawa-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Mitsubishi Kakoki Co., Ltd. (56) References JP-A-48-24018 (JP, A) JP-A-62 106280 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) F26B 3/06 F26B 5/04

Claims (2)

(57) [Claims] A powder is supplied into a stationary drying hopper. First, the air is dehumidified and dried, and then the powder is first dried with hot air generated by drying. Drying and drying the dried powder under reduced pressure under a reduced pressure of 110 to 210 Torr under a reduced pressure of 110 to 210 Torr in a drying state of the hot air generated by heating after dehumidifying and drying air in the drying hopper. How to dry the body. 2. A hot-air drying section for primary drying the powder and granules by a dry hot air generated by heating after dehumidifying and drying air in a stationary drying hopper; A decompression drying unit for drying under reduced pressure of 110 to 210 Torr under a reduced pressure of 110 to 210 Torr in a ventilation state of dried hot air generated by heating after dehumidifying and drying the air in the drying hopper, and a secondary drying is provided. Drying equipment for powders.