Coen Company, Inc.

John Zink Company, LLC

Corn Company, Inc.

Vladimir Lifshits

Steve B Londerville

Stephen Londerville

Kenneth Y Ahn

Martin Joseph Fry

Stephen B Londerville

A low NOx burner for installation on a furnace wall has an elongated tube connected to a combustion air supply, the furnace side end of which mounts a combustion air spinner that is spaced from the furnace wall. A plurality of air ports extend through the wall into the combustion chamber. Downstream ends of the air ports are spaced from the furnace wall as well as from the spinner, and they are configured to bias the discharged air flow towards the spinner. A plurality of first fuel gas spuds with fuel gas discharge orifices arranged about the spinner and discharges fuel gas into the combustion chamber downstream of the spinner. A second fuel gas spud is disposed in pockets between adjacent pairs of air ports which are closed against the furnace wall so that no combustion air flows through the pockets. The third gas spuds are placed inside the air ports.

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A burner assembly that produces very low NOemissions includes a plurality of furnace gas openings for receiving a portion of furnace gasses back into a combustion cylinder. The burner assembly includes the combustion cylinder, a plurality of combustion air inlet conduits that extend into the cylinder and a plurality of fuel gas discharge nozzles that also extend into the cylinder. The burner assembly is mounted within a combustion chamber of a furnace, wherein the walls of the combustion chamber are provided with or are made up of heat transfer pipes. Thus, in operation, furnace gasses exit the combustion cylinder and, due to combined aspirating action created by air jets as they exit the air conduits and fuel gas jets discharging from the fuel gas discharge nozzles inside the combustion cylinder and a pressure differential between the combustion cylinder and the combustion chamber, a portion of the furnace gasses flow from the outlet of the combustion cylinder and past the heat transfer pipes toward the proximal or upstream end of the combustion cylinder. Passage of the furnace gasses past the heat transfer pipes cools the furnace gasses and the furnace gasses then flow through the furnace gas openings and mix with the combustion air and fuel gas to provide a lower NOemission in an energy-efficient manner.

A burner for installation in a furnace having a combustion chamber defined by at least a furnace front wall, two side walls, a top wall and a bottom wall as well as heat transfer pipes through which a heat transfer medium flows and which are arranged on at least one of the top, bottom and side walls. A burner assembly is mounted to the furnace front wall and has a tubular member with an open distal end that is located inside the combustion chamber. The other end of the tubular member is attached to the furnace front wall. Several combustion air ports extend into the tubular member from the other, proximal end thereof and are coupled to a source of combustion air. Several fuel gas discharge nozzles also extend into the tubular member from the other end thereof and are coupled to a fuel source. Furnace gas openings formed in the tubular member are spaced apart from the distal end, are arranged about the tubular member's periphery, and are located relative to the combustion chamber so that furnace gases circulate past some of the heat transfer pipes before they reach the furnace gas openings to thereby form a mixture of combustion air, fuel gas and furnace gas. A spinner at the distal end of the tubular member creates a recirculation zone for the mixture downstream of the spinner and the tubular member.

Embodiments of the present invention are directed to a low NOx duct burner or heater for efficiently heating turbine exhaust gases (TEG) in a less polluting manner. In one embodiment, a heater for heating a gaseous stream flowing in a downstream direction through a duct comprises a heating gas supply pipe extending at least partially across the duct. The heating gas supply pipe includes a plurality of spaced-apart gas pipe outlets to discharge a portion of a heating gas into the duct generally in the downstream direction. A flame shield extends from a location at or near the heating gas supply pipe at least partially across the duct. A plurality of gas supply spuds are disposed upstream of the flame shield. The gas supply spuds include a plurality of gas spud outlets to discharge another portion of the heating gas into the duct. A plurality of jet pumps each extend from a jet pump inlet at an upstream location upstream of the flame shield to a jet pump outlet at a downstream location downstream of the flame shield. Each jet pump inlet is disposed near one of the gas spud outlets to receive the heating gas from the gas spud outlet and the duct gas from the gaseous stream for premixing of the heating gas and the duct gas in the jet pump.

Low NOx duct burner

A heat recovery system includes an upstream superheater section and a duct burner arranged to provide improved performance. The upstream superheater section and duct burner are arranged to reduce the negative effects of heat extraction by the upstream superheater section on the duct burner operation. The arrangement provides a downstream flow from the upstream SH section that is temperature stratified and positions the duct burner elements in the areas of maximum temperature. The tubes of the upstream superheater section and the duct burner elements are arranged in a variety of ways to provide temperature stratification, for example, in the horizontal or vertical directions.

Temperature stratified superheater and duct burner

A low NO.sub.x burner includes a refractory lined plate with a refractory side facing a combustion chamber. A multiplicity of combustion air passages extend through the plate toward the combustion chamber. A multiplicity of spaced-apart primary fuel nozzles each have a discharge opening being surrounded by one of the combustion air passages for directing fuel therethrough to mix with combustion air passing through the air passages. A multiplicity of anchor fuel nozzles project through the plate for directing fuel into the combustion chamber. The anchor fuel nozzles are spaced apart from each other and from the combustion air passages. The flows of fuel and combustion air through the primary and anchor nozzles and the air passages into the combustion chamber are controlled to generate a flame. In applications that require low excess air, such as boiler applications, the burner is modified by providing a secondary fuel and flue gas injection assembly to form a two-stage burner. In the preferred embodiment, the secondary injection assembly includes a plurality of discrete fuel and flue gas injection nozzles arranged around the primary and anchor fuel nozzles and combustion air passages. By varying the percentage and actual pattern of secondary fuel injection and by varying the configuration of the array of primary and anchor nozzles and the spacing between the nozzles, the flame shape may be easily tailored to the size and shape of practically any furnace. The flame can thus be optimized to achieve lower NO.sub.x and improved efficiency.

Vibration-resistant low NO.sub.x burner

An industrial fuel gas burner fired with a mixture of combustion air having up to about 45% flue gas which flows in a downstream direction along an annular combustion air conduit disposed about an axially movable core of the burner that terminates in an end cone that faces the combustion chamber of the furnace. Within the conduit and upstream of a discharge end thereof is a fuel gas discharge header formed by concentric, radially inner and outer tubular ring-shaped fuel gas headers which are concentrically disposed about an axis of the burner and in fluid communication with a source of pressurized fuel gas. The headers have a multiplicity of fuel gas discharge orifices which form three-dimensionally oriented gas streams directed into the combustion air-flue gas flow in the annular conduit. The orifices have a diameter of at least about 0.1 inch. The fuel gas has a pressure so that the fuel gas streams have sufficient energy to flow portions of the gas to a vicinity of the annular conduit walls to intimately mix the fuel gas with the combustion air and form a substantially uniform combustion air-flue gas-fuel gas mixture at a discharge end of the annular conduit. The end cone periphery mounts a number of blades that create enhanced, non-repetitively irregular turbulence in the flow discharged from the conduit, which causes irregular turbulence along the boundary between the flow and combustion gas which recirculate in the wake of the cone. The core of the burner including the blades can slide along a guide so that the discharge area between the throat and the cone can be varied with the firing rate, and the blades can be moved away from the conduit when the burner operates at full load.

Low NO.sub.x fuel gas burner

A low NO.sub.x burner includes a primary air and fuel discharge assembly which, in turn, includes a burner plate having a plurality of slots from which fuel gas jets and combustion air are discharged. The slots are arranged such that the width of the recirculation zones between adjacent slots substantially varies between the central region of the burner plate and its perimeter. With this construction, the local ignition patterns vary such that local oscillations of flame front occur at different frequencies so that vibrations are greatly dampened and resonance problems in the furnace minimized or eliminated. In applications where high excess air is not desirable, such as boiler applications, the burner is modified by providing a secondary fuel and flue gas injection assembly to form a two stage burner. In the preferred embodiment, the secondary injection assembly includes a plurality of discrete fuel and flue gas injection tubes arranged around the primary air and fuel gas discharge assembly. The secondary fuel and flue gases are directed radially inward and downstream from the burner plate so that they mix with the combustion air entering through the burner plate slots in a secondary combustion zone. The resulting delay in the combustion of the secondary fuel gas and the need for heating the flue gas lowers the overall combustion temperature, which in turn reduces the NO.sub.x formation in the second or downstream combustion zone.

A low NO.sub.x burner includes a burner plate having a plurality of slots from which fuel gas jets and combustion air are discharged. A plurality of fuel tubes are aligned with the slots for discharging the fuel gas therethrough. The fuel tubes are spaced from the slots so that combustion air, provided by a wind box, also can flow through the slots. The fuel gas and combustion air are discharged at high velocity, thereby generating very high turbulence in the combustion chamber downstream from the burner. The slots are arranged such that the width of the recirculation zones between adjacent slots substantially varies between the central region of the burner plate and its perimeter. With this construction, the local ignition patterns vary such that local oscillations of flame front occur at different frequencies and are not synchronized so that vibrations are greatly dampened and resonance problems in the furnace minimized or eliminated. Preferably a gas nozzle is arranged at the center of the burner plate and is provided with fuel gas discharge ports to direct fuel gas in a direction tangential to the nozzle so as to induce gas exiting therefrom to swirl downstream from the burner plate. A spinner also is arranged around this central gas nozzle to cause combustion air channeled around the nozzle to swirl downstream from the nozzle. In this way, flame stability without air preheat is achieved with up to 110% excess air.

A cooling system including a cooling duct adjacent to the hot air duct of an air heater. The cooling duct includes a first wall and a second wall spaced from the first wall such that a passageway is formed therebetween. A wire mesh sheet is arranged in the duct passageway. The wire mesh sheet comprises a plurality of layers of wire mesh and has an undulate configuration which together with its density prevents substantial heat radiation from the first wall of the cooling duct to the second wall without significantly impeding airflow through the cooling duct. Cooling air introduced into the cooling duct flows through the duct, removes heat, radiated by the first wall and absorbed by the wire mesh sheet, and carries that heat away from the duct as it exits through the outlet opening. In this way, the system cools the first wall and prevents any significant heat transfer to the second wall of the cooling duct and elements in the vicinity thereof.

Cooling system for air heaters and the like

A burner suitable for use in conjunction with an air heater. The burner has a burner plate including a plurality of slots. The burner plate slots are aligned with and spaced from fuel supply tubes. The tubes have spaced apart orifices that discharge fuel gas in conical patterns and direct the gas jets through the slots in the burner plate and into the combustion chamber downstream from the burner. A baffle plate is positioned above the fuel supply tubes and extends across an air supply plenum. The baffle plate includes air discharge orifices through which the air from the plenum enters the burner in substantially uniform flow. The baffle plate orifices direct the air toward the burner plate for cooling. The air heated by the burner plate eventually flows toward and through the burner plate slots where it forms a layer between the fuel gas jets and the perimetrical surfaces and edges of the burner plate slots and, thus, maintains the fuel gas spaced from these surfaces and edges. The gas velocity exceeds the air velocity to the extent that the gas and air flows are effectively kept separate before entering the combustion chamber. With this construction, very high fuel flow velocities can be used to generate very high turbulence, and a high intensity flame with reduced NO.sub.x emissions without flame flashback into the burner, within wide turndown.

Growing community of inventors

Redwood City, CA, United States of America

Vladimir Lifshits