Combustion – Porous – capillary – particulate or sievelike flame holder,... – Means supplying fuel for passage through the flame holding...
Reexamination Certificate
1999-08-10
2001-04-10
Price, Carl D. (Department: 3743)
Combustion
Porous, capillary, particulate or sievelike flame holder,...
Means supplying fuel for passage through the flame holding...
C126S0920AC, C431S344000, C431S354000
Reexamination Certificate
active
06213761
ABSTRACT:
FIELD OF THE INVENTION
The present application relates generally to heating devices, particularly to heating devices in which a highly efficient catalytic combustion apparatus is employed to generate heat from a vaporous fuel with reduced toxic emissions.
BACKGROUND INFORMATION
A typical catalytic combustion apparatus oxidizes a gaseous fuel, such as methane, butane or propane, at room temperature to generate heat. Generally, the fuel is introduced into a gas-tight housing where the fuel expands to completely fill the housing. As the fuel diffuses through a catalyst-containing support located at an outlet of the housing, ambient air mixes with the diffused fuel. The fuel-air mixture is then oxidized by a reaction promoted by the catalyst to produce heat. Such catalysts typically include noble metals such as platinum group metals or compounds containing the same. The substrates upon which the catalysts are supported are typically made from glass fibers, porous metals or ceramics such as ceramic wool or ceramic board and the like.
The products of the catalyst-enhanced oxidation reaction, such as carbon dioxide and water vapor, are discharged through the outside surface of the catalyst-containing substrate. Convection currents disperse the reaction products and draw in ambient air to provide oxygen to sustain the reaction. The reaction is normally started by igniting the reactants, by means of a flame (e.g. a pilot light) or a spark induced, for example, by an electrical ignition.
A drawback of such known combustion apparatuses is reliance on convection currents to circulate the reactants (air and fuel) and to remove combustion products from the catalyst-containing reaction zone. A factor which contributes to controlling the rate of oxygen available per unit area of catalyst is the rate of convection flow over the active catalytic surface. Convection currents often produce irregular and erratic flows of reactants over the active catalytic surface. Under such conditions, there is typically an uneven distribution of oxygen and/or fuel within the reaction zone containing the catalyst. Consequently, when oxygen is available in less than a stoichiometric amount relative to the fuel, incomplete combustion of the fuel occurs resulting in harmful by-products including carbon monoxide, unburned fuel and the like. As carbon monoxide and unreacted fuel accumulate, a dangerous health hazard arises that could result in serious injury or death to occupants of an enclosed space in which the heating apparatus is used.
SUMMARY OF THE INVENTION
The present invention is generally directed to a heating apparatus comprising a fuel source and an air inlet in communication with a mixing means for creating a uniform fuel-air mixture with a desirable ratio of air to fuel, before being combusted in a catalyst-containing combustion chamber for generating heat. Such pre-mixing of the fuel and air provides for a cleaner and more efficient heat generating combustion resulting in substantially reduced emissions of toxic substances such as carbon monoxide, unreacted fuel and the like, increased safety and an improved operating life of the apparatus.
In particular, one aspect of the present invention is directed to a heating apparatus which includes a combustion chamber having an inlet for receiving a uniform fuel-air mixture, and an outlet. The combustion chamber further includes a catalyst-containing substrate for initiating combustion of the fuel-air mixture. A fuel source and an air inlet are provided in communication with a mixing means for mixing the fuel and air under conditions which provide for a uniform fuel-air mixture, and for delivering the uniform fuel-air mixture through the inlet to the substrate in the combustion chamber to produce heat with minimal production of harmful by-products.
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Kramer Levin Naftalis & Frankel LLP
Price Carl D.
The Coleman Company Inc.
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