Combustion – Flame holder having protective flame enclosing or flame... – Tubular member delineates flame
Reexamination Certificate
2000-03-10
2001-05-29
Lazarus, Ira S. (Department: 3743)
Combustion
Flame holder having protective flame enclosing or flame...
Tubular member delineates flame
C126S27120R, C432S223000
Reexamination Certificate
active
06238207
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a burner for combustion of a gaseous fuel, comprising an elongated combustion chamber, the front end of which is open and the back end of which is closed with a back. The combustion chamber is connected with partly a fuel gas conduit and partly a combustion conduit, in their turn being arranged to pass a valve mechanism for control of the mixture of gas and combustion air.
BACKGROUND TECHNICS
Burners of the kind described in the preamble may be found in stationary combustion plants where the combustion chamber is located inside e.g. a central heater. The combustion gases, generated by combustion in the combustion chamber, are arranged to be absorbed by the surrounding walls of the combustion chamber or by tubes, if any, through which the combustion gases flow which then are diverted via an exhaust pipe and e.g. through a chimney.
In order to use a burner/heater according to the preamble for other purposes than e.g. for heating of water and generation of steam but instead for the heating of surfaces, e.g. the heating of a bitumen mass when laying roofing-board, the burner has to be manageable by hand and arranged in a way that no damage or injury on account of open flames or too high temperature of the nozzles or the like appear to the roof covering or to the person who handles the device. Modern gas burners work with an open flame that is directed towards the roof covering and might easily set fire to it.
So-called heat guns in which air is heated e.g. by an electrically heated incandescent spiral work without open flame but the heating effect in normally occurring embodiments is too low to use e.g. for laying roofing-board in cool weather. In order to get an increased heating effect from an electrically heated hot-air gun an electric current is needed, which normally is not available in buildings e.g. for housings.
DESCRIPTION OF THE INVENTION
The object of the present invention is to achieve a portable gas burner without the disadvantages of hitherto known portable burners/heaters. The gas burner according to the invention comprises an elongated combustion chamber, the front end of which is open and the back end of which is closed with a back that is connected with partly a fuel gas conduit, partly a combustion air conduit and that is enclosed by a concentric cooling jacket showing one or more chambers for the flow of a cooling medium. The cooling jacket shows a preferably annular exhaust opening at the open front end of the combustion chamber and is connected with a cooling air conduit for the delivery of cooling air, the cooling air conduit in its turn being connected with a compressed air source via a compressed air conduit. Gaseous fuel that is combusted inside the combustion chamber escapes through the front end of the combustion chamber and is mixed with cooling air that escapes from the opening in the cooling jacket. The length of the combustion chamber is adjusted to the amount of gaseous fuel to be combusted inside the chamber in that way that the combustion is completely finished inside the combustion chamber before the combustion gases escape and are mixed with the cooling air. As both the combustion air and the cooling air are pressurized from one or more compressed air sources a jet of heated gas is obtained from the combustion device which jet may be directed towards e.g. a roof covering to be heated.
The cooling jacket may show two or more concentric chambers that are connected in series, the cooling air conduit being preferably the connection to the outer of these chambers. That results in a gradually increased heating of the cooling air before it escapes from the cooling jacket and is mixed with the combustion gas. The cooling jacket increases the heat exchange from the combustion at the same time as it reduces the surface temperature of the burner, something that may permit the burner to be handled without any risk of burn injuries or may permit an additional exterior heat insulation of the cooling jacket consisting of a material that not has to withstand the high temperature inside the combustion chamber.
In order to reduce the consumption of compressed air the burner in an alternative embodiment may be provided with an air motor driven by the compressed air and connected with and arranged to drive a cooling blower by means of which cooling air may be taken from the ambient air and fed into the cooling jacket of the combustion chamber. The exhaust air from the air motor then may be used as combustion air and should be fed into the combustion chamber. The air motor preferably consists of a turbine that is connected with the cooling blower via a shaft. Increasing or decreasing of the amount of compressed air to the air motor acts on both the amount of combustion air and cooling air which results in the desired combustion and cooling with a simultaneous regulation of the amount of fuel gas fed into the combustion chamber.
The compressed air source consists preferably of a compressed-air compressor that may consist of a pressure vessel that has been loaded with air. It lies within the scope of the invention to also admix oxygen to the combustion air if in certain cases a particularly high temperature of the combustion gas is desired.
In addition to the feeding of fuel gas and compressed air the burner also may be provided with feed conduits for a fire extinguishing medium and/or protective gas. If the temperature of the gas that escapes from the combustion chamber at some occasion should get so high that e.g. a roof covering catches fire and starts to burn a valve for a fire extinguishing medium may be opened at the same time as the combustion is interrupted, whereby the fire can be extinguished. If the burner according to the invention is used e.g. for melting of metal as e.g. hard soldering of copper this can be done without oxidation by feeding protective gas annular around the outlet end of the combustion chamber.
The gas burner according to the invention is preferably intended to be portable, e.g. in the shape of a “gun”. Yet it lies within the scope of the invention to arrange the burner e.g. on a wheeled stand and also as a stationary assembly where the burner is accessible at work.
REFERENCES:
patent: 2396968 (1946-03-01), Phillips, Jr.
patent: 2418097 (1947-03-01), Ruff
patent: 2746529 (1956-05-01), Kamm et al.
patent: 2780218 (1957-02-01), Allen
patent: 4416613 (1983-11-01), Barisoff
patent: 5344314 (1994-09-01), Zagoroff et al.
patent: 5891404 (1999-04-01), Ibaraki et al.
patent: 476780 (1930-05-01), None
Clarke Sara
Fasth Roth
Fasth Law Offices
Lazarus Ira S.
SSD International Ltd.
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