Abstract: 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.

Abstract: A primary reactant stream is injected from a burner port into a combustion chamber along an axis. Staged reactant streams are injected into the combustion chamber adjacent to the primary reactant stream in differing configurations. The differences between the configurations of the staged reactant streams include differences in radial distance from the burner port, axial distance from the burner port, and direction relative to the axis. The reactant streams are shifted between differing modes, with differences between the modes including the presence or absence of a flame at the burner port, differences in fuel flow rates, and differences in combustion air flow rates. A heat release profile developed by combustion of the primary reactant stream, or the length of a flame developed by combustion of the primary reactant stream, can be controlled by shifting between the differing modes with reference to the heat release profile or the length of the flame.

Abstract: 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.

Abstract: A method delivers fuel gas to a furnace combustion chamber from a premix burner having a reaction zone with an outlet to the furnace combustion chamber. This includes the steps of injecting a premix of primary fuel gas and combustion air into the reaction zone, and combusting the premix to provide combustion products including vitiated combustion air in the reaction zone. Further steps include injecting staged fuel gas into the reaction zone separately from the premix, discharging the staged fuel gas and vitiated combustion air from the reaction zone through the outlet to the furnace combustion chamber, and combusting the staged fuel gas and vitiated combustion air in the furnace combustion chamber. This enables low NOx combustion in the furnace combustion chamber to be achieved as a result of interacting the staged fuel gas with the vitiated combustion air in the reaction zone.

Abstract: A flow of air is provided from a hot air main into a combustion chamber at a time when a burner is firing into the combustion chamber to heat a bed of regenerative media. The flow of air into the combustion chamber helps to keep products of combustion from flowing into the hot air main. In preferred embodiments, sensors sense pressure in the combustion chamber and the hot air main. A controller shifts a valve back and forth within a range of open conditions to regulate the flow of air in response to the sensed pressures.

Abstract: 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.

Abstract: A method includes the steps of operating a regenerative burner in cycles, including a firing cycle in which fuel and combustion air are discharged from the burner into a process chamber, and a nonfiring cycle in which a quantity of gas is withdrawn from the process chamber through a regenerative bed associated with the burner. The method further includes steps of detecting and responding to a temperature that differs from a predetermined temperature at a location in the process chamber. In a first step of responding to the detected temperature, a flue damper system is operated to vary a flow of gas within the process chamber relative to the location of the detected temperature. A second step of responding to the detected temperature reduces the quantity of gas to be withdrawn from the process chamber through the regenerative bed in a subsequent nonfiring cycle.

Abstract: 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.

Abstract: An apparatus includes a furnace structure defining a combustion zone, and a tube that discharges fuel-oxidant premix into the combustion zone through an outlet from the tube. A reactant supply system provides the tube with unmixed fuel and oxidant for forming the premix. A flashback control means inhibits or extinguishes flashback in the tube.

Abstract: A method of combusting non-gaseous fuel to heat a load in a process chamber includes the steps of injecting reactant streams into a combustion chamber. The combustion chamber does not contain a load to be heated, but communicates with the process chamber through a burner port. A first reactant stream includes the non-gaseous fuel, and is injected into the combustion chamber to cause the non-gaseous fuel to volatilize in the combustion chamber. A second reactant stream, which includes a premix of gaseous fuel and primary oxidant, also is injected into the combustion chamber. The first and second reactant streams then combust together to yield products of combustion that flow through the burner port from the combustion chamber to the process chamber. Importantly, the second reactant stream is injected into the combustion chamber adjacent to the first reactant stream.

Abstract: A combustion system is operated with reference to compliant values of a governmentally regulated exhaust emission parameter. If an alarm condition is detected during an ordinary mode of operation, the combustion system is shifted into an assured compliance mode of operation. The shift to the assured compliance mode is made while continuing to operate the combustion system without a shut-down interruption.

Abstract: A combustion system is operated with reference to compliant values of a governmentally regulated exhaust emission parameter. If an alarm condition is detected during an ordinary mode of operation, the combustion system is shifted into an assured compliance mode of operation. The shift to the assured compliance mode is made while continuing to operate the combustion system without a shut-down interruption.

Abstract: Hot products of combustion are provided beside an outer surface of a load to be heated, and are given a non-uniform temperature profile in a control direction extending across the outer surface of the load. The non-uniform temperature profile of the hot products of combustion is varied within a range that is predetermined relative to the distance that the outer surface of the load extends in the control direction, whereby the load can be given a predetermined temperature profile in the control direction.

Abstract: A method of firing a burner into a furnace process chamber supplies the burner with fuel and combustion air at a ratio that provides a level of excess air. The method includes the steps of reducing the flow rate of combustion air, and maintaining the level of excess air when the flow rate of combustion air is being reduced. Other steps include withdrawing exhaust gas from the process chamber, and supplying the burner with the exhaust gas at an increasing flow rate when the flow rate of combustion air is being reduced.

Abstract: A submerged combustion vaporizer may include a premix burner with multiple integral mixers for forming premix and discharging the premix into the duct system that communicates the burner with the sparger tubes. The SCV may further include a NOx suppression system that injects a staged fuel stream into the exhaust in the duct system, and/or a NOx suppression system that mixes water with the premix.

Abstract: A burner has a port facing into a combustion chamber along an axis. A secondary fuel injector structure has secondary fuel injection ports that face into the combustion chamber at locations spaced radially outward from the burner port. A tertiary fuel injector structure has tertiary fuel injection ports that face into the combustion chamber in directions perpendicular to the axis at locations spaced axially downstream from the secondary fuel injection ports.

Abstract: A burner has a port facing into a combustion chamber along an axis. A secondary fuel injector structure has secondary fuel injection ports that face into the combustion chamber at locations spaced radially outward from the burner port. A tertiary fuel injector structure has tertiary fuel injection ports that face into the combustion chamber in directions perpendicular to the axis at locations spaced axially downstream from the secondary fuel injection ports.

Abstract: A burner has a port facing into a combustion chamber along an axis. A secondary fuel injector structure has secondary fuel injection ports that face into the combustion chamber at locations spaced radially outward from the burner port. A tertiary fuel injector structure has tertiary fuel injection ports that face into the combustion chamber in directions perpendicular to the axis at locations spaced axially downstream from the secondary fuel injection ports.

Abstract: A submerged combustion vaporizer may include a premix burner with multiple integral mixers for forming premix and discharging the premix into the duct system that communicates the burner with the sparger tubes. The SCV may further include a NOx suppression system that injects a staged fuel stream into the exhaust in the duct system, and/or a NOx suppression system that mixes water with the premix.

Abstract: 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.