North American Manufacturing Company, Inc.

Fives North American Combustion, Inc.

Bruce E Cain

Thomas F Robertson

John N Newby

John J Nowakowski

Mark C Hannum

Todd A Miller

Thomas B Neville

Brian J Schmotzer

Keith J Nieszczur

Richard D Sutton

Thomas F Robertston

Joseph P Brown

A method supplies reactants, including fuel gas, to burners that discharge the reactants into a furnace process chamber. In a stable flame mode of operation, stable flames are projected from the burners into the furnace process chamber. At a time when the furnace process chamber has a temperature at or above an autoignition temperature of the fuel gas, a diffuse combustion mode is initiated by supplying a selected burner with additional reactants, including reactants diverted from another burner, to blow off the stable flame at the selected burner.

Diffuse combustion method and apparatus

A low NOx combustion method includes steps of injecting reactants into a combustion chamber. A primary reactant stream, including fuel and combustion air premix, is injected from a premix burner port into the combustion chamber. A staged fuel stream is injected into the combustion chamber from a staged fuel injector port adjacent to the premix burner port. A stream of recirculated flue gas is injected into the combustion chamber from a flue gas injector port that is adjacent to the premix burner port and adjacent to the staged fuel injector port. In this manner, the stream of recirculated flue gas is injected into the combustion chamber unmixed with the primary reactant stream and unmixed with the staged fuel stream.

Low NOx combustion method and apparatus

A grate-kiln pelletizing furnace includes a grate that conveys pelletized material to a rotary kiln, a cooler that cools pelletized material from the rotary kiln, and a gas flow apparatus that directs a stream of gas from the cooler to the rotary kiln to provide preheated process air for pelletized material in the rotary kiln. The gas flow apparatus also directs a stream of gas from the grate to the rotary kiln to vitiate the preheated process air.

[object Object]

A NOx suppression apparatus is configured for use with a burner that injects fuel into a stream of process air flowing into and through a rotary kiln. The apparatus comprises a premix injection system that forms a premix of fuel gas and air, and injects the premix into the stream of process air upstream of the burner port. This enables premix products of combustion to suppress the production of NOx by vitiating a combustion air portion of the process air before the combustion air portion combusts with fuel injected from the burner port.

NOx suppression techniques for a rotary kiln

An indurating furnace has a heating station and an air passage leading to the heating station. A draft of preheated recirculation air is driven through the passage toward the heating station, and is mixed with fuel gas to form a combustible mixture of preheated recirculation air and fuel gas that ignites in the passage. This is accomplished by injecting the fuel gas into the passage in a stream that does not form a combustible mixture with the preheated recirculation air before entering the passage.

An apparatus includes a furnace structure defining a reaction zone. A burner structure communicates with the reaction zone through a burner port. The burner port is centered on a burner axis and has a radius. A fuel inlet structure communicates with the reaction zone through a fuel port. The fuel port is centered on a fuel port axis that is spaced radially from the burner axis a distance within a range from about twice the radius to about six times the radius. The fuel port axis is skewed relative to the burner axis to direct the fuel emerging from the fuel port to flow into the reaction zone along a spiral flow path.

Burner apparatus

A method includes the step of extinguishing a flame fired from a burner in a reaction zone upon determining that a sensed combustion chamber temperature is at or above the auto-ignition temperature of a fuel. A subsequent step is performed before the sensed combustion chamber temperature drops below the auto-ignition temperature. The subsequent step provides a flow of the fuel through the burner and into the combustion chamber through a reaction zone outlet. This initiates diffuse combustion of the fuel by auto-ignition in the combustion chamber in the absence of a flame fired from the burner in the reaction zone.

A burner apparatus is operated in a plurality of distinct modes. In a startup mode, flows of oxidant and primary fuel are ignited by an igniter and are provided simultaneously with a flow of secondary fuel until a process chamber reaches the auto-ignition temperature of the secondary fuel. In a subsequent mode, flows of oxidant and secondary fuel are provided simultaneously to the exclusion of a flow of primary fuel.

Burner apparatus and method

Primary fuel and preheated oxidant are injected into a combustion zone to produce a flame with a predetermined adiabatic flame temperature. The preheated oxidant is injected at a target rate of oxidant injection. The primary fuel is injected at a first reduced rate which is less than a corresponding target rate of fuel injection. Secondary fuel is simultaneously injected into the combustion zone separately from the flame at a second reduced rate which is equal to the difference between the first reduced rate and the target rate of fuel injection. In this manner, combustion of the fuel with the preheated oxidant provides the amount of heat expected from the target rates of injection, while maintaining an adiabatic flame temperature that is lower than it might otherwise be if the target rate of fuel injection were provided entirely at the flame. The lower adiabatic flame temperature provides a correspondingly lower rate of NOx production.

An apparatus including a housing defining a heating process chamber. The housing has an opening communicating the process chamber to the ambient atmosphere. A burner is included that fires into a combustion chamber to heat gas. Also included is a collector structure located outside the opening. The collector structure is configured to collect air and exfiltrated gas from an outside area adjacent to the opening. The apparatus also includes a duct structure communicating the collector structure with the burner so as to supply the collected air and exfiltrated gas to the burner and thereby to supply combustion oxidant to the burner.

Combustion gas and air recovery apparatus

A low NOx burner and related method are disclosed including the steps of supplying a first reactant stream and introducing a second reactant stream into the first reactant stream at a first point so as to produce co-flowing streams. This resulting fuel/oxidant stream is discharged into a furnace environment having inert combustion products substantially equilibrated to furnace temperature, so as to entrain the combustion products and mix them together with the co-flowing stream. The temperature of the co-flowing stream is increased by the entrained products until it ignites in a combustion region displaced from the first point. Thus ignition cannot occur until the reactant stream has been diluted by inert products of combustion, reducing both oxygen concentration and peak flame temperature, so as to suppress NOx production.

Growing community of inventors

Akron, OH, United States of America

Bruce E Cain