JP3000323B2 - Centrifugal spray device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal spraying device for a fluid using a rotating disk, and more particularly to a centrifugal spraying device for obtaining fine particles having a sharp particle size distribution.

[0002]

2. Description of the Related Art Fluids such as solutions, melts, slurries and emulsions are supplied onto a rotating disk and sprayed by centrifugal force to form droplets, which are dried or cooled and solidified. It is widely practiced to obtain mainly spherical powder. This granulation method has an advantage that the average particle size can be relatively easily changed by changing the rotation speed of the rotating disk. However, there is still a problem in sharpening the particle size distribution and obtaining fine particle powder.

[0003] Sharpening the particle size distribution is important in business. In general, in the use of such powders, the particle size distribution is often specified, and if the particle size distribution of the obtained powder is wide, classification must be performed. It cannot be used and is wasted. In general, the finer the powder, the higher the market price tends to be.

[0004] In order to obtain fine powder having a sharp particle size distribution by centrifugal spraying with a rotating disk, it is effective to spread the supplied fluid over the entire surface of the disk into a film having a uniform thickness. However, the liquid supplied on the rotating disk flows from the supplied position to the periphery of the disk as it is, so only a part of the disk is used for spraying, and the thickness of the flowing fluid is uniform. It does not become. In order to prevent this, liquid is supplied from several places on the rotating disk, and donut-shaped fluid supply pipes are provided around the axis of the disk, but it has a satisfactory sharp particle size distribution At present, fine particle powder has not been obtained.

[0005] An object of the present invention is to uniformly spread a fluid on a rotating disk and spray it to form uniform fine droplets.
An object is to obtain fine particle powder having a sharp particle size distribution. The present inventors have noticed that in order to spread the fluid uniformly, the liquid should be supplied to the center of the rotating disk where the centrifugal force is zero,
In addition, the present invention has been made in consideration of the fact that the rotation driving device for the disk should be provided above the rotary disk in order to facilitate the collection of the obtained powder.

[0006]

That is, according to the present invention, a fluid is supplied from below to a center portion of a lower surface of a rotating disk whose lower surface is rotated downward by a drive shaft from above. A centrifugal spray device using a disk is provided.

In the disk used in the present invention, since the fluid flows on the lower surface of the rotating disk due to centrifugal force, the lower surface of the rotating disk needs to be concave downward. Various modifications such as a sprocket shape can be added around the rotating disk.

Further, a heating or cooling gas can be blown from above and / or below the rotating disk. Particularly when the gas is blown from below, the fluid supply pipe can be passed through the gas supply pipe.

Further, if the rotating disk is heated by electromagnetic induction from above the disk, it is most advantageous to obtain a fine particle powder having a sharp particle size distribution by cooling granulation.

[0010]

According to the present invention, since the fluid uniformly spreads over the entire rotating disk, fine particle powder having a sharp particle size distribution can be produced.

[0011]

[Example] Okawara Kakoki Co., Ltd. spray dryer O
Performed using C-16. As shown in FIG. 1, hot nitrogen of 250 ° C. is blown from above and below the disk 1, and 5 kg / hour is applied to the center of a rotating disk (110 mmφ) from a fluid supply pipe passing through a nitrogen blow pipe below. Oligomers (number average molecular weight 4000) were supplied to molten nylon at 250 ° C. The rotating disk was heated to 300 ° C. by electromagnetic induction heating and rotated at 2500 rpm. The temperature of the cooling nitrogen was 40 ° C., and the nitrogen temperature at the nitrogen exhaust tube was 100 ° C.
In the obtained nylon, the oligomer powder is spherical, and a laser particle size distribution analyzer (SALD110 manufactured by Shimadzu Corporation)
According to 0), the portion having an average particle size of 20 μm and a particle size of 5 μm to 25 μm was 83% by weight.

[0012]

COMPARATIVE EXAMPLE As a rotating disk, a disk having a diameter of 110 mm was used, which was in the shape of a cap of an incandescent light bulb, and through which the fluid supplied from above passed through the hole of the rotating disk and flowed to the lower surface of the disk. As shown in FIG. 2, an oligomer powder was obtained on nylon under the same conditions as in the example except that a rotating disk was attached and nylon 12 oligomer was supplied from above. According to the same measurement as in Example 1, the powder was spherical and had an average particle size of 72 μm and 60 μm.
The fraction with a particle size of m to 80 μm was 32% by weight.

[Brief description of the drawings]

FIG. 1 is a diagram of a centrifugal spray device using a rotating disk according to the present invention.

FIG. 2 is a main part view of a centrifugal spray device for supplying a fluid from above.

[Explanation of symbols]

 Reference Signs List 1 rotating disk 2 motor 3 shaft 4 electromagnetic induction heating device 5 upper thermal nitrogen injection pipe 6 lower thermal nitrogen injection pipe 7 fluid supply pipe 8 cooling nitrogen injection pipe 9 nitrogen discharge pipe 10 hole through which fluid flows

Claims (1)

(57) [Claims] 1. A centrifugal spraying device using a rotating disk, wherein a fluid is supplied from below to a central portion of a lower surface of a rotating disk whose lower surface is rotated downward by a drive shaft from above and is centrifugally sprayed. .