Combustion – Burner having electrical heater or igniter – Spark electrode in front of or adjacent fuel discharger
Reexamination Certificate
2000-08-02
2002-11-26
Clarke, Sara (Department: 3743)
Combustion
Burner having electrical heater or igniter
Spark electrode in front of or adjacent fuel discharger
C431S265000, C239S429000, C239S434000, C239S498000
Reexamination Certificate
active
06485293
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to gas burners and, more particularly, relates to gas burner assemblies.
BACKGROUND OF THE INVENTION
Burners which combust gas, such as propane and natural gas, are well known and widely applied. For example, boilers, furnaces, kilns, incinerators, dryers, and food processing equipment all commonly rely upon the heat generated by such combustion for proper operation.
Prior art burner designs have been created to mix a combustible gas with air and provide a spark for the purpose of starting. Extensive attention has been directed to finding proper mixing ratios and to creating apparatus for obtaining such ratios to most efficiently burn the gas while maximizing BTU output.
One known type of burner includes a substantially cylindrical housing provided with an inlet and an outlet. A motor connected to a blower or a fan wheel is typically connected to the inlet to direct air needed for combustion therethrough. A gas supply conduit typically enters the inlet end of the housing as well, and terminates in a gas nozzle short of the housing outlet end. The area of the housing downstream of the nozzle defines a combustion chamber. An ignition source, such as a spark plug or rod, is positioned proximate the gas nozzle and can be energized as needed.
In order to generate a desired airflow through the housing to the combustion chamber to obtain the desired BTU output and flame shape, various retention or nozzle plates have been created. Such plates are typically provided transverse to the longitudinal axis of the housing, and are positioned slightly upstream of the nozzle. The plates typically include various aperture designs to direct forced air therethrough and thus create desired characteristics in the resulting flame.
Two such characteristics are BTU output and flame stability. BTU output is a measure of the strength of the flame and its resulting heat output, and is a function of, among other things, the amounts of air and gas combined and the ratio at which they are combined. Flame stability relates to the maintainability and controllability of the flame. If the gas/air ratio becomes too rich or too lean, the flame can be lost or can burn inefficiently. If the flame is not suitably confined, shaped, and directed, BTU output may be detrimentally effected.
In light of the foregoing, various aperture sizes, aperture patterns, and angles of incidence have been employed in prior art retention plates. Moreover, to ensure starting reliability, relatively complex pilot assemblies have typically been employed. Such pilots require extensive machining and assembly time, resulting in an expensive pilot.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention, a burner assembly is provided which comprises a substantially cylindrical combustion chamber, a gas supply provided in the combustion chamber and terminating in the gas supply outlet, an air supply in fluid communication with the combustion chamber, and a flame stabilizing plate disposed in the substantially cylindrical combustion chamber. The flame stabilizing plate includes a central hub from which a plurality of spokes radially extend. Major combustion air openings are defined by adjacent spokes and the combustion chamber. Minor combustion air openings are provided in each of the plurality of spokes.
In accordance with another aspect of the invention, a pilot assembly is provided which comprises a housing having a combustion chamber, a spark rod having an end plate disposed in the combustion chamber and spaced from an interior surface of the combustion chamber to form a circumferential sparking gap around the end plate, and a gas supply inlet in fluid communication with the combustion chamber.
In accordance with another aspect of the invention, a burner nozzle plate is provided which comprises a central hub, and a plurality of spokes extending radially from the central hub.
In accordance with another aspect of the invention, an improvement to a burner assembly of the type having a nozzle housing having an inlet and an outlet, a blower motor connected to the inlet, a gas supply conduit disposed in the nozzle housing, and a combustion chamber defined by the nozzle housing downstream of the gas supply conduit, is provided. The improvement comprises a nozzle plate disposed in the nozzle housing wherein the nozzle plate includes a central hub with a plurality of spokes radially extending therefrom, each spoke including at least one aperture, a plurality of major air pathways defined by adjacent spokes and the nozzle housing, and at least one minor air pathway defined by each of the spoke apertures.
These and other aspects and features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 1209261 (1916-12-01), Challiner
patent: 2465155 (1949-03-01), Higley
patent: 3469790 (1969-09-01), Duncan
patent: 3700173 (1972-10-01), Ketchum, Jr.
patent: 5494437 (1996-02-01), Kubota et al.
patent: 5984665 (1999-11-01), Loftus et al.
patent: 6041838 (2000-03-01), Al-Sabah
patent: 1304794 (1973-01-01), None
patent: 6-221528 (1994-08-01), None
Li Ceji
Yu Qin-Lai
Clarke Sara
Marshall Gerstein & Borun
Midco International, Inc.
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