Abstract: In a burner for operating a combustion chamber, which burner essentially comprises a swirl generator (100), a transition piece (200) arranged downstream of the swirl generator, and a mixing tube (20), transition piece (200) and mixing tube (20) forming the mixing section of the burner and being arranged upstream of a combustion space (30). A pilot-burner system (300) is arranged in the lower region of the mixing tube (20), which pilot-burner system (300), at minimized pollutant emissions, stabilizes the flame front, in particular in the transient load ranges. At least one ignition device (311) is integrated in the pilot-burner system (300).

Abstract: A structure is disclosed that will quench a flame front during a flashback event in a gas turbine while simultaneously providing a mixing function during normal operations. The device disclosed consists of two monoliths one upstream of the other. In the basic embodiment of the invention the downstream monolith acts as a mixer while the combination of the upstream monolith and the downstream monolith act as the flashback arrestor. Other embodiments of the device also allow the downstream monolith to be a flameholder.

Abstract: This invention relates to an apparatus and method for increasing the reactivity of a fuel/air mixture prior to homogenous combustion of the mixture. More specifically, this invention is a pilot for a gas turbine combustor which utilizes the heat of combustion within the pilot to increase the reactivity of a portion of the fuel/air mixture utilized by the pilot.

Abstract: A device and a method for burning fuel in air. The device includes an annular passage for directing the air in a meridional flow with regard to an axis. A swirl cascade is provided for imposing a swirl on the flow, and a mixer for intermixing the fuel with the flow for forming an essentially homogeneous mixture. Also present is an air flow delayer for delaying a portion of the flow that lies radially on the outside with regard to the axis relative to other portions of the flow. The device is configured in particular as a premix burner, for example for use in a gas-turbine plant.

Abstract: A compound spin vane (CSV) for use in an air passage of a fossil fuel-fired burner. In one embodiment, the CSV is a multi-piece construction of platelike outer and inner vane elements connected to an intermediate platelike rail element. In another embodiment, the CSV includes at least two and possibly three vane portions, rigidly interconnected in spaced lateral relationship with respect to each other. If desired, the vane portions may be simple, curved planar surfaces, and may be arranged with trailing edges arranged at angles with respect to each other. The invention may be employed as a replacement for flat spin vanes found in secondary air passages of known single and dual register burners. When used in such manner in a single register burner, the invention changes secondary air flow characteristics so as to mimic those commonly found in a dual register burner.

Abstract: A process for burning fuel which is formed of free hydrocarbons and/or fine-grained to dusty solid fuels, with a view to obtaining thorough mixing of the oxygen with the fuel in a manner as free of turbulences as possible, is characterized in that, into a main jet of oxygen or an oxygen-containing gas which is approximately cylindrical or slightly conically widening in the jet direction, several fuel jets oriented in a skew manner relative to the central longitudinal axis of the main jet are blown, which fuel jets are formed to surround the main jet peripherally, penetrate into the main jet and are sucked into the main jet.

Abstract: A method for changing the length of a coherent jet by establishing a coherent jet using a flame envelope generated using gaseous fuel and changing the flowrate of the gaseous fuel, preferably using inert gas for make up to maintain a constant total flowrate of fuel and inert gas.

Abstract: A method of operating a pulverized coal-firing furnace is provided which includes injecting air from an upper compartment generally in opposition to a swirling fireball. The method also provides the step of sensing a temperature characteristic of one side of a convection pass of the furnace. The sensed value, in accordance with the method of the present invention, is then evaluated to determine if the sensed value of the temperature characteristic exceeds an allowable value. In response to a determination that the temperature characteristic exceeds the allowable value, the momentum of the air injected through the upper air compartment is changed. After the step of changing the momentum of the air injected through the upper air compartment, the temperature characteristic of the one convection pass location is sensed to obtain a post adjustment value of the temperature characteristic and compared to an allowable value.

Abstract: In a premix burner, the swirl-stabilized interior space (18) has a conical inner body (13) running in the direction of flow. The outer casing of the interior space (18) is pierced by tangentially arranged air-inlet ducts (11a, 12a) through which a combustion-air flow (16) flows into the interior space (18). The swirl flow (23) forming in the interior space (18) is enriched with a fuel via at least one fuel lance (17). The mixture of the two media is then formed in the downstream mixing tube (21). The mixing tube (21) then merges into a combustion space (31) via a jump in cross section, a backflow zone (32) forming in the region of the plane of the jump in cross section, which backflow zone (32) ensures the stability of the combustion.

Abstract: A combustion method in which a coal/primary air mixture is discharged from burners located in the corners of the furnace towards an imaginary circle disposed in the center of the furnace. Air is discharged from air nozzles also located in the corners of the furnace in two flow streams--one directed towards the center of the furnace in a combustion-supporting relation to the fuel, and the other along the inner surfaces of the furnace boundary walls to maintain an oxidizing atmosphere and minimize corrosion and slagging.

Abstract: The present invention relates to an apparatus and method for improving the economics of flue gas recirculation. In particular, the present invention relates to an apparatus for the minimization of oxides of nitrogen ("NO.sub.x ") in the exhaust gas of various combustion processes via balanced pressure drops of the recirculation gas, and a method for the calculation of flue gas recirculation percentage. The flue gas recirculation system achieves the balanced pressure drops by sizing the air intake line and recirculation line associated with the system.

Abstract: A high efficiency, Vortex Inertial Staged Air (VIStA) combustor provides ultra-low NO.sub.X production of about 20 ppmvd or less with CO emissions of less than 50 ppmvd, both at 3% O.sub.2. Prompt NO.sub.X production is reduced by partially reforming the fuel in a first combustion stage to CO and H.sub.2. This is achieved in the first stage by operating with a fuel rich mixture, and by recirculating partially oxidized combustion products, with control over stoichiometry, recirculation rate and residence time. Thermal NO.sub.X production is reduced in the first stage by reducing the occurrence of high temperature combustion gas regions. This is achieved by providing the first stage burner with a thoroughly pre-mixed fuel/oxidant composition, and by recirculating part of the combustion products to further mix the gases and provide a more uniform temperature in the first stage. In a second stage combustor thermal NO.sub.

Abstract: A method and apparatus for reducing NO.sub.x emissions from the combustion of carbonaceous fuels using three stages of oxidation. In the first stage, a partial oxidation combustor is used to partially combust the fuel in the presence of heated combustion air. The fuel gas produced in the partial oxidation process is passed to a second stage partial oxidation combustor while molten slag is removed and disposed of. A second preheated combustion air is introduced into the second stage combustor to produce a reducing flue gas. A third combustion air is mixed with the flue gas in a third stage combustor to substantially complete the combustion process. Preheated steam may be added at any or all of the combustion stages. The stochiometric ratios at each stage of combustion are controlled to minimize overall NO.sub.x emissions to acceptable levels.

Abstract: In a method for operating a corner burner of a tangential burner system, at least a first air stream of coal dust and primary air is tangentially introduced to a imaginary horizontal circle in the combustion chamber of the tangential burner system via a nozzle of the corner burner. An additional air stream is introduced into the combustion chamber in a direction toward a chamber wall of the combustion chamber at an adjustable offset angle relative to the first air stream. The offset angle can be adjusted by providing the additional air stream as mixed air stream of at least two partial air streams of different adjustable flow velocity. A first partial air stream within the nozzle flows straight into the outlet opening of the nozzle, and the second partial air stream flows angularly into the first partial air stream upstream of the outlet opening. The nozzle has a mixing chamber arranged upstream of the outlet opening.

Abstract: A combustion chamber is provided that has a vertically oriented body with an inner surface defining an inner combustion area. A burner is disposed adjacent one end of the body so that the flame of the burner when lit will extend into the combustion area. A first annular insert is disposed in the combustion area and generally surrounds the flame of the burner. The annular insert defines a first secondary gas introduction zone for introducing secondary gases into the combustion area so that the secondary gases can be oxidized by the burner flame. The insert has an inner surface presenting at least one opening for allowing fluid communication between the introduction zone and the combustion area. A second annular insert is disposed in the combustion area below the first insert. The second insert defines a secondary gas extraction zone and a second secondary gas introduction zone located below the extraction zone. The gas extraction zone and second secondary gas introduction zone are separated by a divider plate.

Abstract: A process and apparatus for combusting fuel which results in reduction of nitrogen oxides and carbon monoxides emissions. Fuel and primary air are preferably premixed and introduced into a combustion chamber. Secondary air is introduced through a plurality of secondary air ports, each preferably shaped as a slot, which are positioned about a venturi nozzle or flame holder disk mounted with respect to a combustion chamber wall. The secondary air flowing through the secondary air ports forms relatively high velocity and momentum secondary air jets that promote rapid mixing of the fuel and primary air mixture into the secondary air flow, such that a combustion flame is established at a partial periphery of the secondary air jets.

Abstract: A burner apparatus is provided in accordance with the present invention that includes a case coupled to an air supply and a nozzle positioned to lie in case and coupled to a fuel supply. Nozzle defines at least one air-flow cavity inside case. Nozzle is formed to include a fuel-distribution chamber and at least one fuel-discharge port to communicate fuel from fuel-distribution chamber into air passing from air supply through each air-flow cavity. Fuel) mixes with air in each air-flow cavity to produce a combustible air-and-fuel mixture therein which can be ignited to produce a flame in case.

Abstract: This invention relates to an apparatus and method for increasing the reactivity of a fuel/air mixture prior to homogenous combustion of the mixture. More specifically, this invention is a pilot for a gas turbine combustor which utilizes the heat of combustion within the pilot to increase the reactivity of a portion of the fuel/air mixture utilized by the pilot.

Abstract: A method is provided for converting the hydrogen sulfide in a hydrogen sulfide containing feed gas into elemental sulfur by oxidizing the hydrogen sulfide with an oxygen containing gas to produce elemental sulfur in a Claus plant, wherein the oxygen containing gas is axially introduced into an end portion of the reaction cylinder of the Claus plant and the hydrogen sulfide containing gas is introduced through at least one gas inlet in the side wall of the reaction cylinder at an oblique or perpendicular angle with respect to the direction of the flow of the oxygen containing gas so that the hydrogen sulfide containing gas introduced through the side wall surrounds and swirls about the oxygen containing gas, thereby allowing higher combustion temperatures to be achieved within the reaction cylinder which enhances the efficiency of the combustion and enhances the efficiency of decomposing any ammonia in the gas while keeping the very hot zones away from the refractory material lining the interior of the reactio

Abstract: A low NOx burner having a burner body, to which an electric fan for supplying air for combustion is connected and which includes an exhaust gas recirculation passage for supplying combustion gas from the burner body to air for combustion, the low NOx burner including an exclusive exhaust-gas recirculation fan provided for the exhaust gas recirculation passage and arranged to forcibly recirculate exhaust gas, and a bypass passage formed between the exhaust gas recirculation passage and a passage for air for combustion formed in the burner body.

Abstract: A nozzle for a recuperative radiant tube burner system is constructed to provide uniform combustion along the length of the inner tube. The nozzle includes combustion air ports disposed at compound angles and having different axial components to provide staged mixing of air and fuel. The staged mixing produces a combustible mixture along the length of the tube to produce a more uniform flame. The nozzle further has an outer wall disposed normal to the combustion air ports to improve air flow through the ports. A fuel outlet tube has relief ports for continuing fuel flow in the event that a main orifice is plugged, which may result from air pressure fluctuations in the burner system.

Abstract: The operational life of a synthesis gas generation reactor burner nozzle is improved, at least about 14%, by a faired lip around the nozzle discharge orifice projecting about 0.95 cm from the nozzle end face. The lip is faired with a 45.degree. conical angle from the nozzle face. A smooth transition of recirculated gas flow across the nozzle face into the reactive material discharge column is believed to promote an attached static or laminar flowing boundary layer of cooled gas that insulates the nozzle face, to a degree, from the emissive heat of the combustion reaction.

Abstract: A low NO.sub.x combustion process is carried out by reacting low concentrations of combustibles with low concentrations of oxygen. These low concentrations are obtained by injecting high velocity fuel and oxidant streams through port openings that are spatially separated.

Abstract: A gas fired burner is provided for use in applications such as chemical process furnaces for process heaters in refineries and chemical plants, and the like. The burner is provided with a plurality of fuel gas inlets for enabling manipulation of the flame shape and combustion characteristics of the burner, based upon variation in the distribution of fuel gas between the various fuel gas inlets.A combination pilot and flame holder for a burner, such as may be used in process heaters and furnaces for refineries, chemical plants and the like, is also provided. The pilot is mounted atop a supply pipe for premixed fuel and air, which is positioned in the bore of a burner quarl. The pilot includes a radially outwardly extending flange which is upstream of a surface combustion flame holder for establishing a radially directed surface combustion flame.The present invention also provides a low-emissions burner and pilot system for use in such process heaters and furnaces.

Abstract: A burner for liquid and/or gaseous fuels (A, B, C) for a premixing combustion system in graduated load operation of a combustion chamber includes at least one inner partial body (2) that extends in the flow direction; at least one outer partial body (4) which extends conically opposite to the inner partial body (2); and at least one other surrounding pipe (8). The inner and outer partial bodies form a central flow structure, whereby the two are supplied with the flow in effective connection with each other with combustion air (13, 14, 15). The main part of this combustion air (13) then flows through the two partial bodies through air inlet slits (11, 12) and forms one rotational flow in each of the adjoining flow chamber (5, 7).

Abstract: A gas fired burner is provided for use in applications such as chemical process furnaces for process heaters in refineries and chemical plants, and the like. The burner is provided with a plurality of fuel gas inlets for enabling manipulation of the flame shape and combustion characteristics of the burner, based upon variation in the distribution of fuel gas between the various fuel gas inlets.A combination pilot and flame holder for a burner, such as may be used in process heaters and furnaces for refineries, chemical plants and the like, is also provided. The pilot is mounted atop a supply pipe for premixed fuel and air, which is positioned in the bore of a burner quarl. The pilot includes a radially outwardly extending flange which is upstream of a surface combustion flame holder for establishing a radially directed surface combustion flame.The present invention also provides a low-emissions burner and pilot system for use in such process heaters and furnaces.

Abstract: A combustor for a gas turbine having a centrally located fuel nozzle and inner, middle and outer concentric cylindrical liners, the inner liner enclosing a primary combustion zone. The combustor has an air inlet that forms two passages for pre-mixing primary fuel and air to be supplied to the primary combustion zone. Each of the pre-mixing passages has a circumferential array of swirl vanes. A plurality of primary fuel tube assemblies extend through both pre-mixing passages, with each primary fuel tube assembly located between a pair of swirl vanes. Each primary fuel tube assembly is comprised of two tubular members. The first member supplies fuel to the first pre-mixing passage, while the second member, which extends through the first member, supplies fuel to the second pre-mixing passage. An annular fuel manifold is divided into first and second chambers by a circumferentially extending baffle.

Abstract: A combustion system having a combustion chamber having a fuel inlet, a preheating chamber surrounding the combustion chamber, an air inlet for tangentially feeding combustion air to the preheating chamber, the combustion chamber having an elongate slot for tangentially admitting preheated air in circulating motion to the combustion chamber, a plasma chamber coupled to the combustion chamber having an inlet aperture for receiving combusting fuel-air plasma from the combustion chamber, and an outlet aperture for expelling combusted gas, the plasma chamber having an inverted end wall surrounding the outlet aperture operative for forming an imploding vortex in the plasma chamber.

Abstract: Heating fluid in a chamber comprising a floor or ceiling and an upwardly or downwardly extending heat receiving wall by positioning a vortex burner substantially at or above the chamber floor in proximity to the heat receiving wall, delivering fuel and air to the vortex nozzle and burning the fuel to make a combustion product, imparting a swirling flow to the combustion product while directing the swirling flow along an elongated path, jetting fuel at a location positioned adjacent the vortex burner, and burning the jet fuel, thereby forming jet flow combustion products that mix with the vortex burner combustion products, and directing the resulting hot mixture generally vertically adjacent to the heat receiving wall for transferring heat thereto.

Abstract: A liquid fuel burner is provided with a central fuel outlet having a generally divergent conical inner surface, formed of two contiguous divergent conical surfaces of different angles of divergence, and a plurality of oxygen outlets shaped and positioned for creating a converging, rotating stream of oxygen which intersects with any liquid fuel issuing from the fuel outlet. Such oxygen/fuel interaction results in two zones of combustion and a recirculation effect which assists in the complete or substantially complete combustion of undesirable exhaust gas components. The oxygen and fuel are preferably supplied such that their velocities are approximately equal at the point at which the two zones of combustion meet.

Abstract: An apparatus and method for establishing a stable pilot flame at a wide range of operating conditions, having a main fuel tube, an outer tube concentrically enclosing the main fuel tube, a swirler located downstream from the outer tube, an ignitor, and several fuel manifold tubes connected to the main fuel tube, are disclosed. The fuel manifold tubes direct a portion of the pilot gas fuel stream radially outward from the remainder of the pilot fuel. The axial momentum of the radially displaced fuel stream is greater than the average axial momentum of the remainder of the pilot gas streams. This relationship between the axial momenta of the gas steams promotes flame recirculation and stabilizes the pilot flame over a wide range of operating conditions.

Abstract: A process for combustion of a combustible material in which a primary combustible material is introduced into a combustion chamber having an upstream region and a downstream region, and ignited, forming a primary combustion zone. A secondary combustible material is partially combusted in a partial combustor, forming partial combustion products which are then injected into the combustion chamber downstream of the primary combustion zone, forming an oxygen deficient zone downstream of the primary combustion zone.

Abstract: A powered multi-fuel burner has a burner assembly which utilizes an air aspirated nozzle. An air compressor provides air to the air aspirated nozzle and to a fuel-holding tank where the fuel within the tank is put under air pressure thereby to enhance its flow to the air aspirated nozzle. A bleed valve is positioned between the air compressor and the fuel thank thereby to increase or decrease the air pressure within the fuel tank. By increasing and decreasing the air pressure within the tank, the burner can produce heat over a range of operation.

Abstract: An improved staged combustion method useful with oxy-fuel combustion and in a furnace which contains a charge, wherein substoichiometric combustion and secondary oxidant injection are carried out in an orientation which forms a more oxidizing atmosphere proximate the charge surface and oxidizing gas recirculates from the secondary oxidant stream to the charge surface and back to the secondary oxidant stream.

Abstract: A combustor for a heat engine, such as a Stirling cycle heat engine, incorporating a number of nozzles mounted between a pair of plates. Fuel is introduced from above the plates into mixing chambers within the nozzles. Combustion inlet air passing between the plates is introduced into the mixing chambers and create a swirling motion in the fuel/air mixture. The fuel/air mixture passes through an expansion chamber before being discharged to a common combustion chamber. The combustor has been designed to allow the use of high temperature combustion inlet air and to have low NOx emission characteristics.

Abstract: An apparatus for burning crude oil has a conduit (12) without a flow restriction orifice and which receives oil to be burned. The conduit (12) has a plurality of inclined nozzles (28) which are also arranged about the longitudinal axis of the bore (30) so as to be substantially tangential to the interior surface. A supply of high velocity air is passed through an inlet manifold (32) and inside a housing (18) surrounding the conduit (12) in the vicinity of the nozzles (28) where it passes through the nozzles (28) into the bore (30) of the conduit (12). The high velocity air breaks the fuel up into particles and pounds the particles with an angular velocity causing the particles to swirl or rotate as a fine mist in one direction about the longitudinal axis at the outlet (16).

Abstract: A burner is provided with a central fuel outlet and a plurality of oxygen outlets shaped and positioned for creating a converging, rotating stream of oxygen which intersects with any fuel issuing from the fuel outlet. Such oxygen/fuel interaction results in two zones of combustion and a recirculation effect which assists in the complete or substantially complete combustion of undesirable exhaust gas components.

Abstract: Disclosed is a mechanical swirler for generating diverging flow in lean premixed fuel burners. The swirler of the present invention includes a central passage with an entrance for accepting a feed gas, a flow balancing insert that introduces additional pressure drop beyond that occurring in the central passage in the absence of the flow balancing insert, and an exit aligned to direct the feed gas into a combustor. The swirler also has an annular passage about the central passage and including one or more vanes oriented to impart angular momentum to feed gas exiting the annular passage. The diverging flow generated by the swirler stabilizes lean combustion thus allowing for lower production of pollutants, particularly oxides of nitrogen.

Abstract: A method of reducing pressure fluctuations in the combustor of a gas turbine engine resulting from the combustion of fuel and air therein comprises combusting a fuel/air mixture in a combustor downstream of the exit plane of a fuel nozzle assembly such that such recirculation zones generated by the fuel nozzle assembly are in spaced relation to the exit plane and the combustion products are isolated from the fuel and air in the mixing zone at all operating conditions of the engine.

Abstract: A furnace gas injection apparatus and process for delivering gaseous fuel to a furnace at a compound angle wherein one angle .alpha. of the compound angle is directed outwardly from the furnace burner centerline at an angle of between 75.degree. and 120.degree. to a line extending radially from the furnace burner centerline to the gas discharge openings of the gas injection means.

Abstract: A combustion system having a combustion chamber having a fuel inlet, a preheating chamber surrounding the combustion chamber, an air inlet for tangentially feeding combustion air to the preheating chamber, the combustion chamber having an elongate slot for tangentially admitting preheated air in circulating motion to the combustion chamber, a plasma chamber coupled to the combustion chamber having an inlet aperture for receiving combusting fuel-air plasma from the combustion chamber, and an outlet aperture for expelling combusted gas, the plasma chamber having an inverted end wall surrounding the outlet aperture operative for forming an imploding vortex in the plasma chamber.

Abstract: A burner having lower emissions and lower unburned fuel losses by implementing a transition zone in a low NO.sub.x burner. The improved burner includes a pulverized fuel transport nozzle surrounded by the transition zone which shields the central oxygen-lean fuel devolatilization zone from the swirling secondary combustion air. The transition zone acts as a buffer between the primary and the secondary air streams to improve the control of near-burner mixing and flame stability by providing limited recirculation regions between primary and secondary air streams. These limited recirculation regions transport evolved NO.sub.x back towards the oxygen-lean fuel pyrolysis zone for reduction to molecular nitrogen. Alternate embodiments include natural gas and fuel oil firing.

Abstract: Waste/industrial effluents containing contaminating amounts of organic and/or inorganic species, for example effluents containing sulfate or sulfuric acid values, or effluents emanating from the production of methionine, are safely and effectively purified in high yield, by first establishing, in a first reaction zone, an axially helically descending flowstream defining a phase of combustion, this phase of combustion comprising ignited admixture of a first oxidizing fluid and a combustible fuel; ejecting the phase of combustion through a port of restricted flow passage to impart an axially symmetrical vortex flow thereto and flash-expanding same into a second reaction zone; introducing effluent to be purified into the axially symmetrical vortex thus formed; and also introducing additional oxidizing fluid into such axially symmetrical vortex, whereby the effluent is disintegrated into a multitude of droplets entrained in unit volumes of the phase of combustion and thermally treated in the second reaction zone.

Abstract: A flat flame burner is disclosed having flow passages for admitting fuel and air to a burner tile. A structure for producing a rotational flow cooperates with a divergent burner tile in order to produce a radially-divergent flame with a very small axial component and a high degree of entrainment of inert combustion products in a furnace. A portion of the fuel is injected into the entrained furnace products, in order to suppress the rate of combustion, so as to produce an ultra low NOx flat flame burner. The present invention also permits greater versatility and improved operability over previous flat flame burners.

Abstract: In a method and a device for burning fuels in a combustion air main stream, the combustion air is passed in a channel over at least one deltoid body. The deltoid body consists of at least one essentially triangular vortex generator area and a downstream, trapezoid flame stabilizer area. In the region of the vortex generator area, fuel is introduced into the turbulent combustion air. The vortex generator area is set via a half sweep angle and an angle of attack relative to the main stream in such a way that the spin of the longitudinal vortexes induced in the main stream is smaller than the critical spin for generating a recirculation zone. The flame stabilization area is set via a half sweep angle and an angle of attack relative to the stream in such a way that the spin of the longitudinal vortexes induced in the stream is greater than the critical spin, so that for each deltoid body, a pair of concave recirculation zones is generated, and the ignited combustion air-fuel mixture is stabilized.

Abstract: In a burner of the double-cone design, bores (27) are arranged in the burner sickle (26), via which bores (27) the gaseous fuel (16), to the extent of about 3 to 8% of the total mass fuel flow, is mixed into the outer recirculation zone (28) of the burner. This leads to additional outer stabilization of the flame and to an extended operating range of the burner.

Abstract: A burner for the combustion of fuel and air in an industrial furnace, for use in connection with preheated combustion air, is provided having an equal number of evenly spaced air jets and fuel jets. The air jets and fuel jets are discharged so that they initially diverge away from one another, but eventually, the fuel jets are entrained by the air jets. During the course of their trajectories, before meeting, the air jets and fuel jets entrain resident furnace gases which results in heavy dilution of the fuel and air before combustion. The dilution causes off-stoichiometric combustion conditions and results in a lower flame temperature. This is similar in effect to external flue gas recirculation. As well, the fuel jets undergo pyrolysis in the course of their trajectories before entrainment occurs. This creates a reducing zone in which the NOx in the resident furnace gases being entrained is reduced, in part, back to molecular nitrogen.

Abstract: The invention relates to a water heating apparatus which uses a submergible, pressurized combustion chamber having multiple external heating surfaces, a forced draft burner and a flue collector that collects and passively recirculates a portion of the flue gases back into the burner air intake region. An improved burner array more completely mixes the combustible gases in the combustion region and operates over a wide range of input demands.

Abstract: Process is described for reducing emissions of nitrogen oxides and carbon monoxide from fuel gas fired boilers by using a computer to closely control the flow rate of combustion air and by installing a duct to allow flue gas to recirculate into the air intake of the boiler. In most cases strict emission standards can be met without making any other mechanical modifications to the boiler. A computer controller maps burner characteristics and controls both a variable speed drive and the damper on the combustion air fan, and a damper on recirculated flue gas to meet emission requirements over the various firing rates while maintaining a stable flame free of pulsations. In some burners a simple cone structure placed in the burner provides additional flame stability.

Abstract: This invention involves an improved technique for the modulation of waste an actively controlled compact waste incinerator afterburner. This improved technique utilizes acoustic driving to affect indirect modulation of waste flow velocities. The waste surrogate gases are modulated indirectly by periodic entrainment created by the roll-up of the main air vortex as well as indirect acoustic excitation of secondary air injection. One of the main advantages of this new configuration is the acoustic drivers used to phase inject the waste into the vortex for proper combustion are not in direct contact with the hot waste and therefore can be less expensive and more durable over the long term.