Furnaces – Including fluid fuel burner – Powdered solid fuel
Reexamination Certificate
1998-03-19
2001-05-29
Lazarus, Ira S. (Department: 3743)
Furnaces
Including fluid fuel burner
Powdered solid fuel
C110S263000, C110S234000, C110S347000, C431S188000, C431S284000
Reexamination Certificate
active
06237510
ABSTRACT:
TECHNICAL FIELD
This invention relates to a combustion burner. This invention also relates to a combustion apparatus provided with a combustion burner, such as a boiler, a heating furnace and a hot blast-producing furnace.
BACKGROUND ART
A combustion burner of the type described comprises a mixture nozzle defining a mixture fluid passage through which a mixture fluid, containing solid fuel and primary gas for transferring purposes, flows toward a furnace, and a gas supply nozzle defining a gas passage through which secondary gas or secondary and tertiary gases flow. The secondary and the tertiary gases flow to surround the mixture gas. An oil burner for ignition purposes is provided within the mixture nozzle.
In a conventional combustion burner, a flame stabilizer ring is provided in the vicinity of an outlet end of the mixture nozzle, and the secondary and the tertiary gases are swirled by swirl-producing devices, and are injected from the gas supply nozzles.
During the operation of the combustion burner, a reduction region, including an ignition region and an unignition region inside the ignition region, is formed in the vicinity of the outlet of the mixture nozzle, and further an air-rich region, containing a larger amount of oxygen, is formed to surround the reduction region. By enhancing the combustion rate at the reduction region, the low-NOx combustion can be achieved.
Recently, combustion burners have been required to achieve the low-NOx combustion, and also have been required to have a large capacity. As a result, the diameter of the mixture nozzle of the combustion burners has been increased.
When the diameter of the mixture nozzle increases, the ignition region of the reduction region is relatively decreased accordingly. As a result, the low-NOx combustion in the reduction region is suppressed.
DISCLOSURE OF INVENTION
It is therefore an object of this invention to provide a combustion burner which can achieve the low-NOx combustion even if the combustion burner has a large capacity.
To this end according to the present invention, there is provided a combustion burner comprising: a mixture nozzle defining a mixture fluid passage through which a mixture fluid, containing powdered solid fuel and transfer gas for transferring the solid fuel, flows toward a furnace; a gas passage surrounding the mixture nozzle, through which oxygen-containing combustion gas flows; and means for directing high-temperature gas, present in the vicinity of an outer periphery of a distal end of the mixture nozzle, into the mixture fluid.
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Jimbo Tadashi
Kiyama Kenji
Kobayashi Hironobu
Kuramashi Koji
Mine Toshihiko
Antonelli Terry Stout & Kraus LLP
Babcock-Hitachi Kabushiki Kaisha
Ciric Ljiljana V.
Lazarus Ira S.
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