| Apparatus for producing spherical powder, burner for treaitng powder, method for producing spherical powder, spherical oxide powder, and oxide powder -> Monitor Keywords |
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  Apparatus for producing spherical powder, burner for treaitng powder, method for producing spherical powder, spherical oxide powder, and oxide powderUSPTO Application #: 20060275723Title: Apparatus for producing spherical powder, burner for treaitng powder, method for producing spherical powder, spherical oxide powder, and oxide powder Abstract: There is provided an apparatus for producing a spherical powder, comprising a cylindrical chamber having an axis extending in the vertical direction and a burner 30 provided in the upper part of the chamber to generate a combustion flame in the chamber, characterized in that the aggregate-crushing gas G is injected from the periphery part of the first supply pipe 61, which constitutes a raw material powder supply route O, into the first supply pipe 61. This configuration can allow a raw material powder to be supplied to the combustion flame with an aggregate of the raw material powder crushed, and suppress generation of coarse particles or unmelted particles resulting from aggregation of particles. The raw material powder to be supplied to the apparatus for producing a spherical powder may have a treating agent such as stearic acid, or a coupling agent added thereto for preventing aggregation. (end of abstract) Agent: Hogan & Hartson L.L.P. - Los Angeles, CA, US Inventor: Shenglei Che Related Keywords: a.i., acid, burner, chamber, combustion, coupling, gas, route, suppress USPTO Applicaton #: 20060275723 - Class: 431159000 (USPTO) Related Patent Categories: Combustion, Fuel Disperser Installed In Furnace The Patent Description & Claims data below is from USPTO Patent Application 20060275723. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to an apparatus for producing a spherical powder, a method for producing a spherical powder, and the like. BACKGROUND ART [0002] In production of ceramic fillers for paints, composite materials and the like, the powder particles have been required to have various characteristics, e.g., sphericity and surface smoothness, to improve particle dispersibility, packing property and fluidity. [0003] Methods for producing spherical powder particles include those based on sol-gel process and spray pyrolysis to directly synthesize spherical particles. These methods, however, involve problems of high cost and amount of production is limited. [0004] Other methods for producing spherical powder particles include melting the particles while they are floating in a flame, e.g., combustion flame or thermal plasma, or in an electric furnace operating at high temperature, to make them spherical by utilizing surface tension of the liquid. A spherical powder has been commonly produced by melting a raw material powder in a flame (refer to, e.g., claims of Japanese Patent Laid-Open No. 2003-40680). [0005] Japanese Patent 3,312,228 discloses synthesis of inorganic spheres, in which a raw material powder is supplied into a combustion flame in a combustion chamber via a powder distributor provided with a number of small holes and located between a raw material powder supply route and the combustion chamber. [0006] Japanese Patent 3,001,561 discloses a raw material transfer pipe with a fanning-out opening. In the present specification, the term "powder" means collective entity of particles. The term "powder" is used when it is appropriate to indicate the collective entity. It is more appropriate in some cases to use the term "particle" as the constituent unit for powder. In this specification, however, the term "powder" is basically used, unless use of the term "particle" is more appropriate, because they substantially share the common basic unit. [0007] Next, the treatment flow in an apparatus for producing a spherical powder using a combustion flame is shown. First, a raw material powder supplied from a feeder is transferred by a carrier gas to a burner, to which oxygen and fuel gas (e.g., LPG) are supplied by a respective oxygen supplying means and fuel gas supplying means, to generate a combustion flame in a chamber provided under the burner. The raw material powder, after being melted into spheres in the combustion flame in the chamber, is recovered by a downstream cyclone or bag filter. [0008] The raw material powder size (diameter) is set in consideration of size (diameter) of the spherical powder as the final product. However, particles of a raw material powder will naturally aggregate while being held in a feeder, notably when the powder is fine. The resulting aggregate, when directly supplied to a burner to be melted, may cause problems, e.g., production of coarse particles having a several times larger diameter than intended, or unmelted particles due to locally lowered temperature in the combustion flame or other troubles mainly resulting from aggregation of the particles. [0009] One of the methods for crushing the aggregated particles is use of a powder distributor, as disclosed in Japanese Patent 3,312,228, mentioned earlier. However, such a powder distributor is difficult to crush the aggregated particles, because the particles may stick to the distributor itself while passing therethrough. [0010] A raw material transfer pipe with a fanning-out opening, as disclosed by Japanese Patent 3,001,561, cannot crush aggregated raw material powder particles, and is not an effective means for suppressing occurrence of coarse particles. [0011] A raw material powder sharply deteriorates in fluidity in a supply system for a spherical powder production apparatus, as it becomes finer. Deteriorated fluidity may cause various problems, e.g., bridging of the particles in a feeder hopper to stop feed supply, or clogging in a supply pipe leading to a burner or in a burner itself, to stop feed supply or cause significant pulsation. When pulsation occurs, a raw material powder is massively thrown into a flame all at once, which, in turn, causes problems, e.g., the product powder includes unmelted particles, or melting of large blocks to produce coarse particles. [0012] Therefore, how fluidity of a raw material powder is maintained to supply it in well-dispersed conditions is an important challenge in production of fine spherical powder. [0013] The present invention is developed to solve these technical problems. The objects of the present invention are to provide an apparatus for producing a spherical powder, capable of suppressing occurrence of coarse particles or unmelted particles resulting from aggregation of the particles; burner for treating a powder; and method for producing a spherical powder, capable of stably supplying a raw material powder in well-dispersed conditions to suppress occurrence of coarse particles or unmelted particles resulting from aggregation of the particles DISCLOSURE OF THE INVENTION [0014] The inventors of the present invention have found, after having extensively studied to supply a raw material powder into a combustion flame while keeping aggregated particles crushed, that injection of a gas from the outer periphery of a raw material transfer pipe into the pipe inside is very effective for crushing them. The present invention provides an apparatus for producing a spherical powder, comprising a cylindrical chamber having an axis extending in the vertical direction and burner provided in the upper part of the chamber to generate a combustion flame in the chamber, characterized in that the burner comprises a raw material transfer pipe through which a raw material powder is transferred to the combustion flame generated by the burner and also with a gas injection part in which a gas is injected from the outer periphery of the raw material transfer pipe into the raw material transfer pipe. The outer periphery of the raw material transfer pipe widely includes the outer and inner surfaces of the pipe wall and also pipe outside. Thus, the apparatus of the present invention for producing a spherical powder is designed to inject a gas from the outer periphery of the raw material transfer pipe, and can supply a raw material powder into a combustion flame while keeping aggregated particles crushed. [0015] The gas injection part for the apparatus of the present invention for producing a spherical powder may be provided with one or more notches on the raw material transfer pipe wall. [0016] The apparatus of the present invention for producing a spherical powder may be designed to have a gas passage through which a gas flows over the raw material transfer pipe and injected into the pipe inside through the one or more notches provided on the pipe wall. [0017] The present invention also provides a burner for treating raw material powder with combustion flame in a predetermined manner. It is a novel burner having a suitable structure for crushing aggregated raw material powder particles. The burner of the present invention for treating powder comprises a first supply pipe which has an opening at one end, and supplies the raw material powder to the combustion flame through the opening; second supply pipe which supplies an aggregate-crushing gas for crushing an aggregate of the raw material powder; and communication part which communicates the first supply pipe with the second supply pipe to direct the aggregate-crushing gas to the first supply pipe at a predetermined angle. The first supply pipe for the burner of the present invention, which functions as a raw material transfer pipe, can supply a raw material powder into a combustion flame, with aggregated particles crushed by an aggregate-crushing gas injected into the pipe via the communication part. This allows the aggregated raw material powder particles to be crushed and treated in a predetermined manner in a combustion flame. The treatment may be spheroidization, production of composite particles or oxidation of metal particles into the oxide particles. [0018] In the burner of the present invention for treating a powder, the second supply pipe has a double-layered pipe structure with the first supply pipe stored therein and the aggregate-crushing gas flows in the space between the first supply pipe and the second supply pipe. It is preferable that the first supply pipe can be detachably attached to the second supply pipe. The first supply pipe, which functions as a raw material transfer pipe, is eroded severely by friction with a raw material powder, and is preferably exchanged periodically. The above design such that the first supply pipe can be detachably attached to the second supply pipe, facilitates burner maintenance and reduces the equipment cost. [0019] The aggregate-crushing gas can effectively crush the aggregated raw material powder particles, when injected into the first supply pipe at a predetermined angle, 5 to 85.degree. to the first supply pipe axis. [0020] The present invention also provides a method for producing a spherical powder by melting a raw material powder in a combustion flame into spheres. It comprises steps of transferring the raw material powder to a combustion flame by a carrier gas; melting the transferred raw material powder in a combustion flame into spheres to obtain a melted product; and of solidifying the melted product by moving the melted product from the combustion flame to the outside thereof. In the transferring step, injection of a gas for imparting a shear stress to the raw material powder can very efficiently suppress occurrence of coarse particles or unmelted particles. [0021] The gas for imparting a shear stress may be the same kind as the carrier gas. When N.sub.2 gas is used as the carrier gas, then the gas for imparting a shear stress will be N.sub.2 gas. When air is used as the carrier gas, then the gas for imparting a shear stress will be air. Continue reading... Full patent description for Apparatus for producing spherical powder, burner for treaitng powder, method for producing spherical powder, spherical oxide powder, and oxide powder Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Apparatus for producing spherical powder, burner for treaitng powder, method for producing spherical powder, spherical oxide powder, and oxide powder patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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