Coating apparatus – Projection or spray type – Coating moving mass of solid particulate work
Patent
1993-06-15
1995-09-05
Jones, W. Gary
Coating apparatus
Projection or spray type
Coating moving mass of solid particulate work
118315, 118326, 239424, 239336, B05B 706, B05B 714, B05C 500
Patent
active
054475678
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a granulating and coating technique, and more particularly to a technique effective for use in granulating, coating and drying of powdery material of which each particle has a comparatively minute diameter.
BACKGROUND ART
In general, among the granulating and coating techniques for powdery material, such a type of technique is known that respective spray nozzles for supplying powdery material as articles to be coated and for supplying a coating liquid as coating material are disposed to be opposed to each other in a diametral direction of a vertical coating cylinder and dry air stream such as hot air is supplied from thereunder.
Furthermore, there is also known another type where two spray nozzles are provided in erected postures and generally in parallel to each other.
However, according to the spray nozzle technique of the above-described opposedly disposed type, it is difficult to maintain equal blow-out force between these spray nozzles, when the articles to be coated and the coating material should collide with each other from opposite directions.
When, for example, the blow-out force of the coating liquid is stronger, such disadvantages occurs that the coating material adheres to an opposed inner wall surface of the coating apparatus to be solidified thereon, or, before solidifying of the coating material, the articles to be coated adhere onto the coating material on the wall to be agglomerated there.
Furthermore, due to the unbalance in the blow-out forces or in the blown-out rate, there may be disadvantage that the coating liquid becomes particles by itself through the so-called spray dry phenomenon without adhering to and forming coat on the articles to be coated.
Furthermore, according to the above-described technique of parallelly disposed spray nozzles, the powdery material and the coating liquid are supplied from the substantially same direction, so that the efficiency of contact therebetween may be in low level.
It is an object of the present invention to provide a technique wherein the probabilities of contact between the powdery material and the coating liquid is raised so that coating is performed efficiently.
It is another object of the present invention to provide a technique wherein reliable coating can be performed by use of one spray nozzle.
DISCLOSURE OF THE INVENTION
Out of inventions disclosed here, typical one will be outlined briefly hereunder.
That is, a coating apparatus according to the present invention is an apparatus wherein powdery material is coated by jet air stream blown out of a spray nozzle, and the spray nozzle comprises: an air stream from the axially central portion of a main body of the nozzle; for blowing out the coating liquid from the outer periphery of the powder blow-out path; and being tapered at least in the outlet portion thereof, for blowing out compressed air from the outer periphery of the coating liquid blow-out path.
A powder supply path coming out of a supply source of the powdery material may be communicated with the intermediate portion of the powder blow-out path which is formed in the axially central portion of the main body of the spray nozzle.
Further, the coating liquid blow-out path may be formed to have a tapered shape at least at the outlet portion thereof.
The outlet portion of the powder blow-out path may be constructed to have a reversely tapered shape toward the outlet, its cross-section being of a circular shape.
In the coating apparatus, the spray nozzle may be directed upwardly or downwardly in the axial direction in a coating chamber which is formed as a vertical tubular member.
In the above-described coating apparatus according to the present invention, the coating liquid blown out of the coating liquid blow-out path is atomized by the compressed air blown out of the compressed air blow-out path disposed on the outer periphery of the coating liquid blow-out path, converges once, and thereafter, is diffused, so that the probability of contact between the droplets of the coating liquid
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Kurita Kaoru
Takei Narimichi
Tanaka Nagahiko
Freund Industrial Co. Ltd.
Griffin Steven P.
Jones W. Gary
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