Abstract: A burner or furnace including a combustion chamber and two or more fuel injection ports. The fuel injection ports inject fuel at non-radial injection angles into the combustion chamber. Preferably, the injection ports feed fuel substantially tangentially to a cyclonic vortex in the burner or furnace during operation. Also preferably, the injection ports are angled downward 5 to 15 degrees from a plane perpendicular to an axis of the burner or furnace.

Abstract: A new burner apparatus and method of combusting fossils fuels for commercial and industrial application is provided wherein the new burner apparatus achieves low NOx emissions by supplying oxygen to the center of the burner flame in as manners so as to create a fuel rich internal combustion zone within the burner flame.

Abstract: A lance (3) for introducing a fuel into a mixing path (2) of a burner (1) which is provided with a swirler for producing a swirled combustion air flow, especially a burner of a turbine plant, includes a lance head (5), a fuel feed (8) and an oxidator feed (10). The lance head (5) projects into the mixing path (2), has at least one fuel nozzle (6) for injection of the fuel into the mixing path (2), and also has at least one oxidator outlet orifice (7) for introducing an oxidator into the mixing path (2). The fuel feed (8) extends in the lance (3) and is connected to the at least one fuel nozzle (6). The oxidator feed (10) extends in the lance head (5) and is connected to the at least one oxidator outlet orifice (7).

Abstract: A premixing burner is disclosed for operating a combustion chamber with a liquid and/or gaseous fuel, with a swirl generator for a combustion inflow air stream for forming a swirl flow, and with injection of fuel into the swirl flow. The swirl generator is adjacent to the combustion chamber indirectly via a mixing zone or directly, in each case via a burner outlet, a cross-sectional widening at the burner outlet being provided which, is discontinuous in the flow direction of the swirl flow and through which the swirl flow bursts open so as to form a backflow zone. A contour locally narrowing the flow cross section of the swirl generator or of the mixing zone in the flow direction can be provided upstream of the burner outlet.

Abstract: A method for combusting a combustible fuel includes providing a vessel having an opening near a proximate end and a closed distal end defining a combustion chamber. A combustible reactants mixture is presented into the combustion chamber. The combustible reactants mixture is ignited creating a flame and combustion products. The closed end of the combustion chamber is utilized for directing combustion products toward the opening of the combustion chamber creating a reverse flow of combustion products within the combustion chamber. The reverse flow of combustion products is intermixed with combustible reactants mixture to maintain the flame.

Abstract: 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.

Abstract: A low NOx burner for installation on a furnace wall. The burner has an elongated tube connected to a combustion air supply, the furnace side end of which mounts a combustion air spinner that is spaced a substantial distance from the furnace wall. A plurality of typically six elongated air ports extend through the wall from the windbox of the furnace into the combustion chamber and supply most of the required combustion air. 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 is 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.

Abstract: A combustion apparatus according to the present invention can positively control and generate burnt gas recirculation with a simple structure. The combustion apparatus has an annular container (12) having an inner cylindrical portion (15) forming an inner circumferential side surface, an outer cylindrical portion (13) forming an outer circumferential side surface, an open end (26), and a close end (10). A flow (28) of air is formed so as to have a velocity component in the direction of a central axis (J) from the open end (26) to the close end (10) and a velocity component to swirl in a circumferential direction of the annular container (12). Fuel (23) is injected so as to have a velocity component in the direction of the central axis (J) from the close end (10) to the open end (26) and a velocity component directed radially outward.

Abstract: A high velocity pressure burner system burns air and gas thereby creating a flue gas. The system comprises a blower for pressurizing the air; a control for adjusting the pressure of the pressurized air; a combustion chamber having a flue gas outlet; and a burner disposed on the combustion chamber. The burner includes an air orifice for receiving the pressurized air; a gas orifice for receiving the gas; the air orifice causing the pressured air to flow over the gas orifice to form an air/gas mixture; at least one spinner vane disposed upstream of the gas orifice creating turbulence in the air/gas mixture; and a retender disposed downstream of the gas orifice creating turbulence in the air/gas mixture. The flue gas outlet is sized to create a back pressure on the burning air/gas mixture. The flue gas from the combustion of the air/gas mixture in the combustion chamber increases in velocity as the flue gas passes through the flue gas exit.

Abstract: A method comprises providing a combustion apparatus having an outer vessel and an inner conduit. The outer vessel has a first wall that defines an internal volume. The inner conduit is at least partially positioned within the internal volume and provides a fluid passageway that is in communication therewith. The method further comprises introducing oxygen into the internal volume in a manner such that the oxygen swirls within the internal volume and around the inner conduit. Furthermore, the method comprises introducing fuel into the internal volume, and combusting the fuel and oxygen at least partially therewithin. The combustion of the fuel and oxygen produces reaction products and the method further comprises discharging at least some of the reaction products from the internal volume via the fluid passageway of the inner conduit.

Abstract: In one embodiment, a method for generating heat energy includes injecting a stream having a concentration of at least 50% oxygen (O2 stream) into a primary gas stream through a mixer, the mixer discharging the O2 stream as two or more spaced jets traversing the primary stream, thereby enriching the primary gas stream. The method further includes mixing fuel with the enriched primary gas stream, thereby forming a fuel stream; and combusting the fuel stream, thereby forming a flue gas stream.

Abstract: An air swirler capable of liquid fuel atomization for a fuel fired burner in a furnace or boiler having a hollow guide pipe supporting several swirl blades at an end adjacent to the furnace. Openings connected by tunnels to the inside of the guide pipe are provided in the trailing edges of each swirl blade. A fuel pipe is concentric with the guide pipe forming an annular space therebetween. Gaseous substances such as oxygen or natural gas are provided through the annular space and liquid fuel is provided through the fuel pipe. The fuel and gaseous substances travel through the tunnels to the openings for liquid fuel atomization and pre-mixing at the burner throat to reduce NOx formation.

Abstract: A burner for producing a plug-like flow and low NOx emissions. The burner has a central air jet and plural staged fuel jets surrounding the central jet. The ratio of the sum of the momentums of vector components of the staged jets along respective axes parallel to the central longitudinal axis of the central jet to the momentum of the central jet along that axis is within the range of 0.5 to 1.5 and most preferably 0.8.

Abstract: A method and apparatus for optimizing boilers with high flue gas recirculation rate based with laser based diagnostic technology. A tunable diode laser is emitted from a launcher, is altered by the absorption spectra of the gas species that it intersects, and encounters a receiver. The signal is processed, then the information is used to modulate the flowrate of hydrogen blended fuel or oxygen enriched air into the burner.

Abstract: The present application relates in general to an apparatus and to methods for testing the performance of an automotive catalytic converter under conditions simulating those which occur in motor vehicles over extended driving conditions. The application provides a novel swirl plate and a novel fuel injector which enable the burner to run stoichiometric for extended periods of time.

Abstract: The combustion system for implementing the process has a combustion grate, hoppers below the combustion grate for supplying primary combustion gas through the grate and nozzles that lead into the furnace above the combustion grate to supply secondary combustion gas. At least one extraction duct for flue gas is provided at the rear end of the furnace above the combustion grate. This duct is connected to the suction side of a fan. The pressure side is connected to nozzles arranged in the upper area of the flue gas pass. The nozzle height allows the flue gases a residence time of at least 1 second after secondary gas is supplied.

Abstract: A method for reducing NOx emissions from a furnace having multiple burners, each burner including at least one chamber for supplying a flow of combustion air and means to adjust the flow of air to the at least one chamber. The method includes the steps of measuring a parameter correlative of combustion air flow; adjusting the flow of combustion air to the at least one chamber so that the parameter is within a predetermined tolerance; and repeating the aforementioned steps for a plurality of burners.

Abstract: A gas burner apparatus for discharging a mixture of fuel gas, air and flue gas into a furnace space of a furnace wherein the mixture is burned and flue gas having a low content of nitrous oxides and carbon monoxide is formed is provided. The burner tile includes at least one gas circulation port extending though the wall of the tile. The interior surface of the wall of the tile includes a Coanda surface. Fuel gas and/or flue gas conducted through the gas circulation port follows the path of the Coanda surface which allows more flue gas to be introduced into the stream. The exterior surface of the wall of the tile also includes a Coanda surface for facilitating the creation of a staged combustion zone. Also provided are improved burner tiles, improved gas tips and methods of burning a mixture of air, fuel gas and flue gas in a furnace space.

Abstract: A furnace is heated by a burner that can be selectively operated by either air-fuel or oxy-fuel combustion. The burner comprises a conduit for fuel, a conduit for air, a conduit for oxidant, and control means for regulating flow through the air and oxidant conduits. An air-fuel fired furnace can be modified by addition of the oxidant and fuel conduits and the control means for regulating flow through air and oxidant conduits.

Abstract: The invention relates to a burner with a burner head (1) and a gas feed pipe (2) that is located in the burner head (1) and that is surrounded by an ring channel (3) for feed of another gas. In the gas feed pipe (2) and in the ring channel (3), there are means (10, 11) for producing a swirl of the gas flowing through the gas feed pipe (2) and that flowing through the ring channel (3).

Abstract: A method and apparatus provide combustion in a radiant tube in first, second and third stages, with flue gas recirculation that begins at the second stage.

Abstract: Compact low NOx gas burner apparatus and methods for discharging fuel gas and air mixtures into furnace spaces wherein the mixture is burned in folded flame patterns and flue gases having low NOx content are formed are provided. A burner apparatus of the invention is basically comprised of a housing having a burner tile attached thereto and means for introducing air therein. The burner tile has an opening therein with a wall surrounding the opening which extends into a furnace space. The exterior sides of the wall are divided into sections by radially positioned baffles with alternate sections having the same or different heights and slanting towards the opening at the same or different angles. Primary fuel gas mixed with flue gases and air is discharged through the burner tile. Secondary fuel gas is discharged adjacent to the external slanted wall sections whereby the secondary fuel gas mixes with flue gases in the furnace space.

Abstract: A method for gasifying carbonaceous materials to fuel gases comprises the formation of an ultra-superheated steam (USS) composition substantially containing water vapor, carbon dioxide and highly reactive free radicals thereof, at a temperature of about 2400° F. (1316° C.) to about 5000° F. (2760° C.). The USS composition comprising a high temperature clear, colorless flame is contacted with a carbonaceous material for rapid gasification/reforming thereof. The need for significant superstoichiometric steam addition for temperature control. Methods for controlling a gasification/reforming system to enhance efficiency are described. A USS burner for a fluidized bed gasification/reforming reactor, and methods of construction, are described.

Abstract: Compact low NOx gas burner apparatus and methods for discharging fuel gas and air mixtures into furnace spaces wherein the mixture is burned in folded flame patterns and flue gases having low NOx content are formed are provided. A burner apparatus of the invention is basically comprised of a housing having a burner tile attached thereto and means for introducing air therein. The burner tile has an opening therein with a wall surrounding the opening which extends into a furnace space. The exterior sides of the wall are divided into sections by radially positioned baffles with alternate sections having the same or different heights and slanting towards the opening at the same or different angles. Primary fuel gas mixed with flue gases and air is discharged through the burner tile. Secondary fuel gas is discharged adjacent to the external slanted wall sections whereby the secondary fuel gas mixes with flue gases in the furnace space.

Abstract: An apparatus and method for using staged air combustion. The apparatus includes a burner body (10) secured to a port block (42), and a fuel passageway (12) extending through the burner body (10), terminating in a fuel nozzle (22), which injects fuel into the burner throat (40). Primary air jets (20) are configured to inject primary air into a primary combustion region (24), which is normally in the burner throat (40). A dish with a dish surface (28) is connected to the burner throat (40); the dish surface (28) extending in a divergent angle with respect to a burner centerline (35). Secondary air jets (34) are connected to the air passageway (14) and extend through the port block (42). The secondary air jets (34) inject secondary air into a secondary combustion region (38), which may be at the dish surface (28) or the hot face (30) of the burner.

Abstract: A pyrolysis heater particularly for the cracking of hydrocarbons in the production of olefins has a burner arrangement in the firebox which includes staged combustion low NOx hearth burners firing upwardly in the firebox adjacent to the walls. Wall stabilizing gas fuel injection tips, located at an elevation above the hearth burners, inject fuel upwardly between the walls and the flame from the hearth burners. This prevents rollover of the flame onto the process heater coil and overheating of the coil.

Abstract: The present invention provides a fuel feeding apparatus and method for improving the controllability of mixing process and mixing ratio of fuel and combustion air, and a combustion system and method for effecting new combustion properties. The fuel feeding apparatus of the combustion system has fuel feeding means, combustion gas extraction means, steam supply means, mixing means and fuel gas introduction means. The combustion gas extraction means extracts combustion gas of a combustion area therefrom. The mixing means mixes the fuel of fuel feeding means with at least one of combustion gas extracted from the furnace and steam of a steam generator. The fuel gas introduction means introduces a mixed fluid of combustion gas, steam and fuel to the combustion area as a fuel gas, and allows the fuel gas to be mixed with the combustion air.

Abstract: The invention relates to recirculation flow combustors having a generally curved recirculation chamber and unobstructed flow along the periphery of the boundary layer of the vortex flow in this chamber, and methods of operating such combustors. Such combustors further have a border interface area of low turbulence between the vortex flow and the main flow in the combustor, in which chemical reactions take place which are highly advantageous to the combustion process, and which promote a thermal nozzle effect within the combustor. A combustor of this type may be used for burning lean and super-lean fuel and air mixtures for use in gas turbine engines, jet and rocket engines and thermal plants such as boilers, heat exchanges plants, chemical reactors, and the like. The apparatus and methods of the invention may also be operated under conditions that favor fuel reformation rather than combustion, where such a reaction is desired.

Abstract: An improved process for burning solid fuel particles in a combustion chamber and creating a flue gas is disclosed. The method comprises creating a fuel gas stream by mixing the solid fuel particles with a conveying gas, transporting the fuel gas stream through a fuel duct terminating at the combustion chamber at a fuel exit plane and injecting an oxygen stream through an injection device into said fuel gas at an oxygen injection location selected to create a mixing zone to mix the oxygen stream and the fuel gas stream immediately prior to or coincident with combustion of the fuel. Operating parameters of the process can be varied to optimally reduce NOx emissions.

Abstract: An improved burner and a method for combusting fuel in burners used in furnaces, such as those used in steam cracking, are disclosed. The burner includes a burner tube having an upstream end, a downstream end and a venturi intermediate said upstream and downstream ends, the venturi including a throat portion having substantially constant internal cross-sectional dimensions such that the ratio of the length to maximum internal cross-sectional dimension of the throat portion is at least 3. A burner tip is mounted on the downstream end of the burner tube adjacent a first opening in the furnace, so that combustion of the fuel gas takes place downstream of said burner tip.

Abstract: Methods and apparatus for combustion of a hydrocarbon fuel in a combustion chamber of a furnace or boiler are presented, the combustion normally using only air as an oxidant, part of the air entering the combustion chamber through one or more burners, and a remaining portion of air entering the combustion chamber at a plurality of locations downstream of the burners. The methods comprise injecting oxygen-enriched gas through a plurality of lances into the combustion chamber at a plurality of downstream locations, the oxygen-enriched gas injected at a velocity ranging from subsonic to supersonic, and the oxygen-enriched gas being present in an amount sufficient to provide an oxygen concentration of no more than 2% on a volume basis greater than when air is used alone as oxidant.

Abstract: Method and apparatus for use in burners of furnaces such as those used in steam cracking. The apparatus includes a burner tube having a downstream end and an upstream end for receiving fuel and air, flue gas or mixtures thereof. A burner tip is mounted on the downstream end of the burner tube adjacent a first opening in the furnace, so that combustion of the fuel takes place downstream of the burner tip. At least one passageway has a first end at a second opening in the furnace and a second end in a primary air chamber adjacent the upstream end of the burner tube. The passageway also has structure for injecting steam into the passageway and a means for drawing flue gas from the furnace through the passageway.

Abstract: A swirl-type internal flame recirculation burner apparatus and method as used to fire asphalt plant aggregate dryers, air heaters and calcining kilns and method includes a compressed air oil atomizer assembly. The burning and swirling fuel and primary main combustion air mixture recirculates upstream along the burner axis. The secondary main combustion air may be swirled. The burner may also be fired on gas or a combination of gas and oil.

Abstract: A dual fuel burner including an elongated supply pipe and a gas injector for a boiler furnace having a plurality of peripheral openings around a center opening. The peripheral openings are pitched radially away from the longitudinal axis of the gas injector and also pitched either clockwise or counter-clockwise, to impart a swirling motion to gaseous fuel exiting the injector through the openings. A first sleeve member is concentrically spaced about the supply pipe and the gas injector to form an inner annular passageway for conveying a mixture of primary air and pulverized coal to the furnace combustion zone. A second sleeve member is concentrically spaced about the first sleeve member to form an outer annular passageway for conveying secondary air to the furnace combustion zone, and a plurality of circumferentially spaced vanes mounted within the outer annular passageway for inducing a swirling motion to the secondary air discharging from the outer annular passageway into the furnace combustion zone.

Abstract: An improved burner and a method for combusting fuel in burners used in furnaces such as those found in steam cracking.

Abstract: In a combustion method, in a burner (12, 20), a fuel/air mixture flowing through a flow passage (13) is made to react in a first combustion stage in a catalytic reactor (15), and downstream of the catalytic reactor (15) fuel is burnt together with the exhaust gas from the catalytic reactor (15) in a second combustion stage to form a homogenous flame (17) by self-ignition. If the fuel from the fuel/air mixture is only partially burnt in the first combustion stage in the catalytic reactor (15), and the unburnt remainder of the fuel is burnt in the second combustion stage, combustion can be stabilized by virtue of the fact that the fuel-containing exhaust gas from the catalytic reactor (15), between the outlet of the catalytic reactor (15) and the homogenous flame (17) is passed through devices 916, 19) which aerodynamically stabilize the homogenous flame (17).

Abstract: An improved burner and a method for combusting fuel in a burner used in furnaces such as those found in steam cracking. The burner includes a burner tube having a downstream end and an upstream end, the burner tube having a venturi therein; a fuel spud located adjacent the upstream end of the burner tube, for introducing fuel gas into the burner tube; a burner tip mounted on the downstream end of the burner tube adjacent a first opening in the furnace; at least one passageway having a first end and a second end adjacent the upstream end of the burner tube; means for drawing flue gas from the furnace, through the passageway, in response to an inspirating effect of uncombusted fuel gas exiting the fuel spud, the uncombusted fuel gas flowing through the burner tube from its upstream end towards its downstream end; and means for increasing the inspirating effect of uncombusted fuel gas exiting the fuel spud.

Abstract: A staged-air burner for use in furnaces such as in steam cracking. The burner includes a burner tube including (i) a downstream end, (ii) an upstream end for receiving fuel and air, flue gas or mixtures thereof from a primary air chamber, and (iii) a burner tip mounted on the downstream end of said burner tube and directed to the first flame opening in the furnace, so that combustion of the fuel takes place downstream of said burner tip; a secondary air chamber for supplying a second portion of combustion air, said secondary air chamber in fluid communication with at least one air port; and a wall peripherally surrounding said burner tip to provide a barrier between a base of a flame at said burner tip and said at least one air port.

Abstract: A burner for use in furnaces such as the type employed in steam cracking.

Abstract: A gas burner for use with a Claus furnace made up of at least five concentric tubes and the spaces formed between them. The diameters of the tubes increase radially outward so that the first tube has a smaller diameter than the fifth tube. At the end of the burner closest to the furnace, the tube ends of the third, fourth, and fifth tubes lie in the same plane. The first and the second tubes are fastened together and capable of movement along the central longitudinal axis of the burner, but their ends closest the furnace are not capable of moving past the plane formed by the third, fourth, and fifth tubes. An injector is located between the first and second tubes at the end closest the furnace. The injector is oriented towards the periphery of the burner.

Abstract: A burner for use in furnaces such as in steam cracking. The burner includes a burner tube having a downstream end and an upstream end. A burner tip is mounted on the burner tube adjacent a first opening in the furnace, so that combustion of the fuel takes place downstream of the burner tip. A fuel orifice located adjacent the upstream end of the burner tube is included for introducing fuel into the burner tube. The burner may also include at least one passageway for supplying flue gas from the furnace into a primary air chamber. The burner also has a structure responsive to an inspirating effect created by uncombusted fuel exiting the fuel orifice for drawing flue gas from the furnace through the passageway and the primary air chamber. The burner also includes a plate for centering the fuel orifice with the burner tube, the centering plate being perforated to permit flow therethrough.

Abstract: A catalytically operating burner with a catalyzer structure (4), useful in particular for a gas turbine system, has a heat-resistant carrier material (10) that forms the walls of several adjoining channels (13). The channels (13) pervade the catalyzer structure (4) in longitudinal direction and permit that a gaseous reaction mixture flows through the catalyzer structure (4). The walls are coated at least in part with a catalyst. In order to improve the catalytic conversion within the catalyzer structure (4), communicating openings (14) are constructed in the walls between an inlet end and an outlet end of the catalyzer structure (4). Adjoining channels (13) are able to communicate with each other through the communicating openings (14).

Abstract: A burner for use in furnaces such as in steam cracking. The burner includes a primary air chamber; a burner tube including (i) a downstream end, (ii) an upstream end in fluid communication with the primary air chamber, and (iii) a burner tip mounted on the downstream end of the burner tube and directed to a first opening in the furnace, so that combustion of fuel takes place downstream of the burner tip; at least one flue gas recirculation duct having a first end at a second opening in the furnace and a second end opening into the primary air chamber, the first end being spaced an effective distance from the first opening for minimizing entrainment of a burner flame into the second opening.

Abstract: An improved burner and a method for combusting fuel in burners used in furnaces, such as those used in steam cracking, are disclosed. The burner includes a burner tube having an upstream end, a downstream end and a venturi intermediate said upstream and downstream ends, the venturi including a throat portion having substantially constant internal cross-sectional dimensions such that the ratio of the length to maximum internal cross-sectional dimension of the throat portion is at least 3. A burner tip is mounted on the downstream end of the burner tube adjacent a first opening in the furnace, so that combustion of the fuel gas takes place downstream of said burner tip.

Abstract: A burner for use in furnaces such as in steam cracking. The burner includes a primary air chamber; a burner tube having an upstream end, a downstream end and a venturi intermediate said upstream and downstream ends, said venturi including a throat portion having substantially constant internal cross-sectional dimensions such that the ratio of the length to maximum internal cross-sectional dimension of said throat portion is at least 3; a burner tip mounted on the downstream end of said burner tube adjacent a first opening in the furnace, so that combustion of the fuel takes place downstream of said burner tip; and a fuel orifice located adjacent the upstream end of said burner tube, for introducing fuel into said burner tube.

Abstract: A miniature combustor comprising a combustion chamber having at least one critical dimension that is sub-centimeter. Combustion is confined within the chamber by injecting a liquid fuel as a film over substantially the entire area of the chamber walls. In a preferred embodiment, a swirl or vortex generator may be included at the entrance of the chamber to cause the in-flowing oxidizing gases to swirl within the chamber. The liquid fuel may be applied as a film through one or more orifices or a porous wall material, or may be applied by spraying the fuel on a surface within the chamber. The liquid fuel may be augmented with an inert liquid such as water.

Abstract: Combustion method and apparatus for NOx reduction and CO reduction which are capable of easily achieving super NOx reduction with the value of exhaust NOx under 10 ppm. The combustion method for NOx reduction by controlling the temperature of combustion gas derived from a burner includes in combination the steps of suppressing combustion gas temperature by heat absorbers; suppressing the combustion gas temperature by recirculating burning-completed gas to a combustion-gas burning reaction zone; and suppressing the combustion gas temperature by adding water or steam to combustion-use air of the burner, whereby the temperature of the combustion gas derived from the burner is suppressed.

Abstract: An improved burner assembly and process for operating same using a burner design that produces very low levels of undesirable nitrogen oxides is provided. The burner assembly premixes primary fuel and air in a venturi system and recirculates combustion gases back to the burner through a plurality of recirculation conduits where it is mixed with the premix of fuel and air and secondary air prior to combustion in a primary combustion zone. Rapid premixing of the primary fuel and air in the venturi system and the dispersion of the recirculated furnace gases is believed to result in lower peak flame temperatures and therefore minimizing the formation of the pollutants, such as nitrogen oxides.

Abstract: A U-tube diffusion flame burner assembly having improved flame stabilization with no undesirable acoustic effects. The burners are axial units comprised of flame holders and combustors. The flame holders includes secondary air tubes to support the flow of secondary air that have helical walls forming helical passageways along at least a portion of its inner diameter to impart a swirl to the secondary air. The helical passageways impart a swirl to the secondary air exiting the passageways while simultaneously acting as a heat exchanger to heat primary air. The flame holders includes fuel tubes having first ends connected to a fuel supply and second flame ends. A plurality of radially oriented apertures are located at the second flame ends to distribute fuel in a radial direction. Primary air tube surrounds at least the flame ends of the fuel tubes and extend axially from first air supply ends to second flame ends.

Abstract: A burner assembly is provided for combining oxygen and fuel to produce a flame. The burner assembly includes a burner block formed to include a flame chamber having inlet and outlet openings, a bypass structure for conducting oxygen outside of the flame chamber to the outlet opening of the flame chamber and structure for discharging fuel into the flame chamber formed in the burner block.