Anti-clogging free-jet burner and method

Abstract

A clog-resistant, highly stable free-jet burner and method that provides ultra-low NO emissions by using the following methods: x Emissions: (a) large free-spraying injection ports, (b) wide burner-to-burner spacing, and (c) auxiliary stabilizing burners within the burner throat, which are highly resistant to clogging and also produce very low levels of NO. x emission.

Description

Technical Field

[0001] This invention relates to free-jet burners and methods, as well as a method for manufacturing modified free-jet burners that prevent clogging, have high flame stability, and produce low levels of NO. x Other emissions. Background Technology

[0002] Industrial burners are commonly used in process heaters, boilers, furnaces, incinerators and other combustion heating systems to generate heat for oil refining, chemical production, petrochemical operations and other large-scale industrial processes.

[0003] Processing units in today's refineries, chemical plants, and other facilities must be able to operate for increasingly longer periods without downtime for major repairs and maintenance. In fact, maintenance cycles in many refineries and other facilities are now four years or longer. Therefore, the continuous and reliable operation of burners and other critical equipment over very long periods is becoming increasingly important.

[0004] One of the main causes of industrial burner downtime occurs when the fuel port of the burner nozzle becomes clogged with debris or residue. Clogged fuel ports can lead to reduced or completely restricted fuel gas flow.

[0005] Another problem with industrial burners is their increasing need to produce lower levels of NO. x Other emissions. Under otherwise identical conditions, NO x Emissions increase with increasing combustion process temperature. As the burner flame temperature rises, the stability of the covalent bonds in N2 in the burner air supply decreases, leading to increased free nitrogen production and thus increasing thermal NO emissions. x The generation of emissions. Therefore, reducing NO... x In ongoing efforts to reduce emissions, various types of burner designs and theories have been developed with the aim of lowering peak flame temperatures.

[0006] Hot NO x The reduction of combustion temperature is typically achieved by slowing down the combustion rate. Since combustion is a reaction between oxygen and the burner fuel, the purpose of delayed combustion is usually to reduce the rate at which fuel and oxygen mix and burn. The faster the oxygen and fuel mix, the faster the combustion rate and the higher the peak flame temperature.

[0007] A type of low-NOx fuel that is very effective in slowing down the combustion rate and reducing peak flame temperature. xThe burner is a free-jet burner. A free-jet burner typically includes: (i) a burner wall, (ii) an internal passage for delivering an airflow or other oxygen-containing gas flow out of the front end of the burner wall, and (iii) a series of external injectors positioned outside the burner wall to discharge the fuel flow as a free-jet stream to the burner flame. The flow momentum of the free-jet stream traveling outside the burner wall entrains a considerable amount of gaseous combustion products (exhaust gas) contained in the combustion heating system, thereby recirculating the exhaust gas back into the combustion zone to form a diluted combustion mixture that burns at a lower peak flame temperature. This NO x The reduction technology is known as Internal Exhaust Gas Recirculation (IFGR).

[0008] Unfortunately, with the development of increasingly lower levels of NO... x Improved free-injection burners for emissions control generally do not improve clogging resistance. On the contrary, in some cases, the burner's clogging resistance has deteriorated to some extent. One reason is that, in many cases, greater exhaust gas recirculation and NOx emissions have been achieved by using a larger number of external injectors. x For further emission reduction and greater stability, the external injectors have very small injection ports (typically only 1 / 16 inch in diameter), which are placed close to each other (i.e., spaced less than 2 inches apart, and more preferably only 1.5 to 1.8 inches apart). The small injection ports are necessary to prevent interference between adjacent fuel flow streams and to promote exhaust entrainment.

[0009] However, the small injection ports required by existing free-injection burners are prone to clogging. These small fuel injection ports can become clogged with tiny debris and / or limited deposits. Therefore, fuel coarse filters are generally not effective at preventing clogging, especially in systems with high levels of debris due to fuel line aging and / or other factors.

[0010] The use of auxiliary burner nozzles in free-jet burners and other burners has also been problematic in terms of both clogging and NOx emissions. An auxiliary burner nozzle is a gas nozzle used to improve the stability of the burner's main flame, particularly under abnormal conditions. Examples of abnormal conditions that can cause the burner flame to become unstable include, but are not limited to: (a) reducing the airflow to the burner to substoichiometric levels, (b) reducing the temperature loss in the combustion heating system to below the minimum temperature required to ignite the fuel, or (c) pressure excursion occurring in the combustion heating system.

[0011] In auxiliary burner nozzles currently used in this field, the combustion rate and peak flame temperature are typically high enough that using one or more auxiliary burners significantly improves the burner's NO₂ levels. x Emissions. Furthermore, auxiliary burners currently used in this field for flame stabilization purposes are particularly prone to clogging. The fuel gas ports of these burners are extremely small, typically 1 / 16 inch in diameter (i.e., the port flow area is only 0.0031 square inches). As a result, the auxiliary burners are easily clogged, even after filtration.

[0012] If a blockage occurs in the auxiliary burner nozzle, which is used to maintain the stability of the burner flame, the local temperature at the stable point can decrease until the flame stability can no longer be maintained and the flame disappears. When flame disappearance occurs in one or more burners of a multi-burner heating system, significant safety issues may arise, including the risk of explosion.

[0013] Therefore, there is a need for an improved free-jet burner that prevents clogging and provides high flame stability. The improved free-jet burner will also preferably produce very low levels of NO. x Other emissions, which are comparable to or better than the ultra-low emission levels of free-jet burners currently used in the field. Summary of the Invention

[0014] This invention provides an improved free-jet burner and its operating method, as well as a method for modifying an existing free-jet burner, which meets the needs and alleviates the problems discussed above. The improved or modified burner is highly resistant to clogging and provides high flame stability. The burner and method of this invention also provide ultra-low NO. x The emission levels are comparable to or better than those produced by free-jet burners currently used in the prior art, which require small fuel discharge ports and are prone to clogging.

[0015] In one aspect, a method for providing low NO is provided. xAn improved burner for emissions, wherein the burner is used in a heating system having exhaust gas therein, and the burner is of the type comprising: (i) a burner wall having a front end, (ii) an internal passage of the burner wall for air or other oxygen-containing gas to flow out from the front end of the burner wall, and (iii) a series of injectors positioned outside the burner wall to deliver fuel in the form of a free jet flow directly or indirectly from the injectors to the main burner flame located at and / or in front of the front end of the burner wall. For such a burner, the improvements preferably include: (a) using a large fuel injection port in the injector with a flow area of ​​at least 0.0068 square inches that provides anti-clogging; (b) using a wide burner-to-burner spacing of 2 to 14 inches between injectors, which provides enhanced recirculation of exhaust gas to the main burner flame for the free jet flow from the large fuel injection port; and (c) positioning one or more auxiliary burner burners in an internal passageway in the burner wall to stabilize the main burner flame, each of the auxiliary burner burners having a large fuel discharge port with a flow area of ​​at least 0.012 square inches that provides anti-clogging.

[0016] On the other hand, there is a method for operating the burner to achieve low NO. x An improved method for emissions, wherein (a) the burner includes a burner wall having a front end and an internal passage through which air or other oxygen-containing gas flows out of the front end of the burner wall, (b) the burner operates in a heating system, and (c) the method is of the type comprising the step of injecting fuel outside the burner wall from a series of injectors in a free jet flow directly or indirectly to a main burner flame located at and / or in front of the front end of the burner wall. For this method, the improvements preferably include: (i) increasing the injector's anti-clogging properties by using a large fuel injection port with a flow area of ​​at least 0.0068 square inches in the injector; (ii) enhancing the recirculation of exhaust gas in the heating system to the main burner flame for a free jet flow from the large fuel injection port of the injector by using a wide burner-to-burner spacing of 2 to 14 inches between the injectors; and (iii) enhancing the stability of the main burner flame by using one or more auxiliary burner nozzles located in an internal passageway in the burner wall, each of the auxiliary burner nozzles having a large fuel discharge port with a flow area of ​​at least 0.012 square inches, the large fuel discharge port providing anti-clogging properties.

[0017] On the other hand, it provides a solution to increase the anti-clogging properties of existing burners while maintaining low NOx levels. xThe method of emission, wherein the existing burner has (i) a burner wall, (ii) an internal passage of the burner wall through which air or other oxygen-containing gas flows out from the front end of the burner wall, and (iii) a series of x primary injectors positioned outside and spaced around the internal passage of the burner wall, and wherein the primary injectors deliver fuel from the injectors in a free jet flow directly or indirectly to the main burner flame at the front end of the burner wall and / or in front of the front end. The method preferably includes the following steps: (a) increasing the nozzle-to-nozzle spacing by removing every other primary injector such that the number of remaining injectors is (i) half the number of primary injectors x if the number of primary injectors x is even, or (ii) no greater than ((x-1) / 2)+1 if the number of primary injectors x is odd; (b) replacing each of the remaining injectors with an anti-clogging injector having a large fuel injection port with a flow area of ​​at least 0.0068 square inches; and (c) stabilizing the main burner flame by installing at least two auxiliary burner nozzles in an internal passage of the burner wall, each auxiliary burner nozzle having a large fuel discharge port with a flow area of ​​at least 0.012 square inches, which provides anti-clogging, and each of the auxiliary burner nozzles directs the auxiliary burner flame onto a surrounding shoulder at the front end of the burner wall or onto a flange or other internal feature of the burner wall.

[0018] Other aspects, features, and advantages of the invention will become apparent to those skilled in the art upon studying the accompanying drawings and reading the following detailed description of preferred embodiments. Attached Figure Description

[0019] Figure 1 This is an elevation side view of Embodiment 10 of the improved free-jet burner provided by the present invention.

[0020] Figure 2 This is a partial cross-sectional side view of the burner 10 of the present invention.

[0021] Figure 3 This is a cross-sectional side view of the burner 10 of the present invention.

[0022] Figure 4 This is a plan view of the burner 10 of the present invention.

[0023] Figure 5 This is a cross-sectional elevation view of the auxiliary burner nozzle 102 of the burner 10 used in the present invention.

[0024] Figure 6 From Figure 5The cross-sectional view of the flame deflector 112 of the auxiliary burner 102 shown in perspective 6-6.

[0025] Figure 7 This is a perspective view of the auxiliary burner nozzle 102.

[0026] Figure 8 An auxiliary burner nozzle 102 installed in the burner 10 of the present invention is shown schematically.

[0027] Figure 9 This is a partial sectional elevation side view of an alternative embodiment 55 of the improved free-jet burner provided by the present invention.

[0028] Figure 10 This is a partial sectional elevation side view of an alternative embodiment 66 of the improved free-jet burner provided by the present invention.

[0029] Figure 11 This is a plan view of an alternative embodiment 90 of the improved free-jet burner provided by the present invention.

[0030] Figure 12 This is a partial cross-sectional side view of an alternative embodiment of an improved burner of the present invention, which has an inner flange 81 formed at its outer end.

[0031] Figure 13 This is a partial cross-sectional side view of an alternative embodiment of an improved burner of the present invention, which has an internal beveled surface 88 formed at its outer end. Detailed Implementation

[0032] Before explaining the invention in detail, it is important to understand that the invention is not limited to the preferred embodiments and steps described herein in its application. The invention can have other embodiments and can be practiced or performed in various ways. It should be understood that the wording and terminology used herein are for descriptive purposes and not for limitation.

[0033] As will be understood by those skilled in the art, the term "free jet" as used herein and in the claims refers to a flow of fluid exiting from the port of an injector nozzle, tip, or other injector, which is more stagnant than the flow of a free jet. In this invention, the fluid exiting the injector may be a gaseous fuel and / or a liquid fuel, but preferably a gaseous fuel, and the substantially stagnant fluid is exhaust gas present within the heating system. For the purposes of this invention, the heating system may be a process heater, a boiler, or any other type of heating system commonly used in the art. The exhaust gas present within the system will include gaseous products of the combustion process.

[0034] As described above, the fuel used in the burner and method of the present invention is preferably a gaseous fuel, but may alternatively be a liquid fuel, or a fuel that has both a gaseous and a liquid phase. The gaseous fuel used in the burner and method of the present invention may be natural gas, refinery fuel gas, hydrogen, or any other type of gaseous fuel or gaseous fuel blend commonly used in process heaters, boilers, or other gas combustion heating systems. The free-jet flow operation employed in the system of the present invention entrains exhaust gas and ensures thorough mixing of the exhaust gas with the fuel streams as it travels towards the outlet end of the burner wall or in front of the main burner flame.

[0035] Now refer to the attached diagram, Figures 1-4 An embodiment 10 of the burner device of the present invention is shown. The burner 10 includes a housing 12 and a burner wall 20 having an outlet or front end 22, a base end 25, and an internal passage or throat 26 extending through and surrounding the burner wall 20. The outlet end 22 of the burner wall 20 communicates with the interior 27 of a furnace or other heating system housing where combustion occurs and thus contains combustion product gases (i.e., exhaust gases). The burner 10 is shown mounted through a base plate or other wall 32 of a heating system typically formed of metal. Insulation material 30 is typically fixed to the interior of the furnace base plate or wall 32.

[0036] The burner wall 20 is preferably made of high-temperature refractory burner brick material. However, it should be understood that the burner wall 20 may alternatively be formed or provided by a furnace bottom plate or other wall, metal strip, refractory strip or any other material or structure, which may be capable of (a) providing an acceptable flow path for air or other oxygen-containing gas entering the heating system housing 27 and (b) withstanding the high-temperature conditions therein.

[0037] Combustion air or other oxygen-containing gas 28 is contained within the housing 12 and guided by the housing 12 to the inlet end 24 of the burner throat 26. The air or other oxygen-containing gas 28 exits the burner 10 at its outlet end 22. The amount of combustion air or other oxygen-containing gas entering the housing 12 is regulated by the inlet damper 14. The air or other oxygen-containing gas 28 may be supplied to the housing 12 as needed via forced circulation, natural ventilation, a combination thereof, or any other means employed in the art.

[0038] A series of external burners, nozzles, or other fuel injectors 36 surround the burner wall 20. In embodiment 10 of the burner of the present invention, each injector 36 is described as comprising a fuel injection burner 36 fixed to the end of a fuel pipe 38. Each fuel pipe 38 communicates with a fuel supply manifold 34 and may extend through the lower skirt portion of the burner brick 20 or be fixed within the insulating material 30 attached to the furnace wall 32. Although the fuel pipe 38 is shown as a riser connected to the fuel supply manifold 34, it should be understood that any other type of fuel supply system may be used alternatively in the present invention.

[0039] Each injector 36 has an injection port 45 drilled or otherwise disposed therein, which is preferably oriented to directly (e.g., to inject the free-flowing fuel 50) Figure 2 (As shown) or indirectly, the fuel 50 is delivered to the main burner flame 46 at or in front of the front end 22 of the burner wall 20. Delivering the free-injected fuel stream 50 "indirectly" to the main burner flame 46 means, for example, that the injection ports 45 of one or more injectors 36 may alternatively be oriented to direct one or more fuel streams 50 at a more inward angle toward the burner wall 20 or at a more outward angle away from the burner wall, such that the momentum of the air or other oxygen-containing gas 28 draws the indirect fuel vapor 50 back into the main burner flame 46 as the air or other oxygen-containing gas flows out of the front end 22 of the burner wall 20. As each free-injected fuel stream 50 flows to the main burner flame 46, exhaust gases from the furnace casing are entrained therein and mixed with it.

[0040] The injectors 36 are located outside the internal passage 26 of the burner wall 20 and at least partially surround (preferably completely surround) the internal passage, such that the free-injected fuel flow 50 travels outside the burner wall 20. As shown in the figures, the injectors 36 are preferably located near the base 25 of the burner wall 20, such that they are positioned longitudinally rearward and laterally outward of the outer end or front end 22 of the burner wall 20.

[0041] The burner pilot 72 may optionally be located within the internal passage 26 to initiate combustion at the outer end 22 of the burner 10.

[0042] According to the improvements provided by the burner and method of the present invention, the anti-clogging property of the injector 36 of the burner 10 of the present invention is increased by using a large injection port 45 in the injector 36. The large fuel injection port 45 will preferably be a drilled port with a circular shape, but said drilled port may alternatively be square, elliptical, or any other desired shape. In each case, the large fuel port 45 of each injector 36 will preferably have a flow area of ​​at least 0.0068 square inches (i.e., at least 3 / 32 inch in diameter for a circular port), and will more preferably have a flow area of ​​at least 0.012 square inches (i.e., at least 1 / 8 inch in diameter for a circular port). The flow area of ​​each large fuel port 45 will more preferably be in the range of 0.012 to 0.096 square inches, and will most preferably be about 0.012 square inches (i.e., 1 / 8 inch in diameter for a circular port).

[0043] Also according to the improvements provided by the burner and method of the present invention, a wide spacing 37 between the injectors 36 (referred to herein as a wide nozzle-to-nozzle spacing) is used. The wide nozzle-to-nozzle spacing 37 between the injectors 36 will preferably be 2 to 14 inches, and more preferably 3.5 to 10 inches. The nozzle-to-nozzle spacing 37 between the injectors 36 will most preferably be approximately 3.5 to 6 inches.

[0044] These improvements, namely the use of a large fuel injection port 45 and a wide burner-to-burner spacing 37, are in line with conventional knowledge and industrial practices for reducing NO. x Current practices contradict those concerning emissions and the provision of burner stability. As mentioned above, it is believed in industry that NO reduction is best achieved by using a greater number of injectors. x To reduce burner size and improve burner stability, these injectors have very small injection ports with a diameter of only 1 / 16 inch, and are positioned very close together with a nozzle-to-nozzle spacing of less than 2 inches, and more preferably no more than 4 inches.

[0045] In the burner 10 of the present invention, all other things being equal, while the use of a large fuel port 45 in the injector 36 provides anti-clogging properties, it also reduces the amount of exhaust gas drawn into the combustion mixture by the momentum of the free jet stream 50 and the air or other oxygen-containing gas stream exiting the front end 22 of the burner wall 20. This, in turn, reduces the dilution of the combustion mixture, which undesirably accelerates the combustion process, increases the peak flame temperature, and increases the NO produced by the burner. x And the levels of other emissions.

[0046] In the burner 10 of the present invention, the amount of exhaust gas recirculated to the combustion mixture for the main burner flame 46 is increased and restored by using a wide nozzle-to-nozzle spacing 37 between the injectors 36. The increased nozzle-to-nozzle spacing 37 creates a wider flow channel for exhaust gas recirculation between the injectors 36, which in turn allows the momentum of the free jet stream 50 and air or other oxygen-containing gases to draw a certain amount of exhaust gas into the combustion mixture, this amount being substantially equal to or greater than the amount of IFGR achieved in conventional free-jet burners. Due to the amount of IFGR achieved in the burner 10 of the present invention, the NO produced by the burner 10 of the present invention... x The emissions will be at an ultra-low level of less than 10 ppmv in a natural gas-fired furnace with a furnace temperature of 1400°F, ambient air temperature, 10% excess air, and a fuel gas pressure of 30 psig, and will be more preferably in the range of 5 ppmv to 18 ppmv for most furnace applications.

[0047] However, although the injector 36 used in the burner 10 of the present invention provides anti-clogging properties, and the wide nozzle-to-nozzle spacing 37 of the injector 36 increases the amount of IFGR achieved in the combustion mixture, a reliable and improved device is still needed to maintain the stability of the main burner flame 46, especially during abnormal conditions. As mentioned above, if, for example, the burner experiences a significant reduction in airflow, or there is a significant temperature loss in the heating system, or a pressure shift occurs in the heating system, the loss of stability increases the chance of burner flame extinction. The possibility of flame loss in one or more burners of a multi-burner heating system poses significant safety hazards, including the risk of explosion.

[0048] Unfortunately, as mentioned above, the auxiliary burners used to improve stability in the field to date are themselves prone to clogging, which also poses a serious risk of flameout. Furthermore, the NO produced by existing auxiliary burner nozzles... x The level of emissions is unsatisfactory.

[0049] According to the improved burner and method of the present invention, the need to ensure the continuous stability of the main burner flame 46 is met by using one or more auxiliary burner nozzles 102 positioned in the burner wall 20 within the internal passage 26. These auxiliary burner nozzles are anti-clogging and therefore do not pose a risk of flameout. Furthermore, unlike existing auxiliary burner nozzles 102 used for various purposes in the prior art, each auxiliary burner nozzle 102 used in the burner and method of the present invention preferably produces very low levels of NO. x Emissions, which do not significantly contribute to the total emissions of the burner 10 of the present invention.

[0050] To prevent clogging, each auxiliary burner nozzle 102 in the burner 10 of the present invention has a large fuel discharge port 132, which preferably has a flow area of ​​at least 0.012 square inches (i.e., at least 1 / 8 inch in diameter for a circular port), and more preferably at least 0.049 square inches (i.e., at least 1 / 4 inch in diameter for a circular port). The flow area of ​​the large fuel discharge port 132 will more preferably be in the range of 0.049 to 0.06 square inches, and will most preferably be about 0.049 square inches. Similarly, to provide low levels of NO... x For emissions, each auxiliary burner nozzle 102 is preferably a substoichiometric graded air burner nozzle or a lean premixed burner nozzle.

[0051] The number of auxiliary burners 102 used in the burner 10 of the present invention can be any number y suitable for maintaining the stability of the burner flame 46, especially when subjected to abnormal conditions of the type described above. By way of example and not limitation, for a burner 10 having a heat output of less than 15 MMBtu / hour, and assuming that the burner 10 includes a burner igniter 72 located within an internal passage 26 for initiating combustion at the outer end 22 of the burner 10, two auxiliary burner burners 102 will preferably be included in the internal passage 26. For any y>1 auxiliary burner 102 used in the burner 10, assuming that the size and dimensions of the burner 10 of the present invention can range from small to very large depending on the service and required heat output of the burner 10, the spacing 65 between each pair of adjacent auxiliary burner burners 102 will typically be in the range of 5 to 24 inches or greater, and more preferably in the range of 10 to 18 inches.

[0052] Each auxiliary burner nozzle 120 used in the burner and method of the present invention is preferably as follows: Figures 5-8 The staged air sub-stoichiometric burner nozzle shown. The auxiliary burner nozzle 102 preferably includes: a nozzle shroud housing 104 having a longitudinal axis 106; a mixing chamber 108 contained within the shroud housing 104; a gas fuel inlet pipe 110 positioned to discharge gas fuel into the rear longitudinal end of the mixing chamber 108; and a flame deflector 112 on the front longitudinal end of the shroud housing 104.

[0053] The burner housing 104 preferably includes a longitudinally extending outer wall 114 surrounding the mixing chamber 108. The outer wall 114 is preferably cylindrical, but may alternatively have a square, elliptical, or other cross-sectional shape. A series of small openings 116 are preferably provided around and through the rear portion of the outer wall 114 to serve as emergency release openings for gas expansion in the event of combustion occurring within the housing 104 itself.

[0054] The transverse base wall 118 at the rear end of the mixing chamber 108 has at least a central opening 122 extending through it. When gaseous fuel is discharged to the rear end of the mixing chamber 108 via the gaseous fuel connector 110, the momentum of the gaseous fuel flow draws air or other oxygen-containing gas from the internal passage 26 of the burner 10 into the mixing chamber 108 through the central base opening 122. Furthermore, the momentum of the gaseous fuel preferably also draws air or other oxygen-containing gas into the mixing chamber 108 through a plurality of openings 124 formed around the central base opening 122 through the base wall 118 of the casing 104. The peripheral openings 124 are preferably smaller than the central base opening 122. The dimensions of the base openings 122 and 124 are preferably determined such that the total amount of air or other oxygen-containing gas drawn into the mixing chamber 108 is a substoichiometric amount, i.e., insufficient to burn all the amount of gaseous fuel discharged into the mixing chamber 108 by the gaseous fuel connector 110.

[0055] The flame stabilizing ring 120 at the front end of the mixing chamber 108 has a central discharge opening 126 through which it passes, which is smaller than the cross-sectional diameter or area of ​​the mixing chamber 108, such that the substoichiometric mixture of fuel and oxygen-containing gas flowing through the mixing chamber 108 creates a depressurization zone 128 on or near the stabilizing ring 120, which helps to maintain and otherwise stabilize the flame 130 of the auxiliary burner 102.

[0056] The gas fuel connector 110 includes a large fuel discharge port 132 at its front end for discharging gaseous fuel to the rear longitudinal end of the mixing chamber 108. The fuel discharge port 132 of the connector 10 is preferably positioned behind the base wall 118 of the housing 104, such that the connector 110 discharges gaseous fuel forward through the central opening 122 of the base wall 118. The fuel discharge port 132 may be formed directly at the front end of the gas fuel connector 110, or it may be formed in a plug placed at the front end of the connector 110.

[0057] In addition to using a large exhaust port 132, the gas fuel connector 110 is preferably connected to a gas fuel supply line or riser 134 having an orifice fitting 136 containing a flow orifice. The flow area of ​​the flow orifice is (a) preferably at least 0.0068 square inches (equivalent to at least 3 / 32 inch of circular orifice diameter), and more preferably at least 0.012 square inches (equivalent to at least 1 / 8 inch of circular orifice diameter), but (b) also preferably smaller than the size of the fuel connector exhaust port 132. The flow area of ​​the flow orifice is more preferably in the range of 0.012 square inches to about 0.014 square inches and most preferably about 0.012 square inches. In the event that the system contains debris of any size sufficient to clog even the large exhaust port 132 of the gas fuel connector 110, the debris will be blocked by the flow orifice in the orifice fitting 36, which will be located outside the combustion heating system and can be easily cleaned. The flow orifice can also be used to measure the flow rate of gaseous fuel from the external fuel supply manifold 34 to the auxiliary burner nozzle 102.

[0058] The flame deflector 112 on the front longitudinal end of the protective housing 104 preferably includes: a rearward opening 140; an internal flame space 142; a longitudinally extending sidewall 144 partially extending around the internal flame space 142; an endwall 145 at the front longitudinal end of the sidewall 144; and a lateral side opening 146. The endwall 145 is preferably a solid circular endwall that extends laterally over and covers the internal flame space 142. The longitudinally extending sidewall 144 of the flame deflector 12 has a semi-circular lateral cross-sectional shape extending from a first arc end point 148 to a second arc end point 150. The semi-circular cross-sectional shape of the longitudinally extending sidewall 144 is preferably an arc in the range of 120° to 270° from the first arc end point 148 to the second arc end point 150, and more preferably an arc of approximately 180°.

[0059] The lateral opening 146 of the flame diverter 112 preferably (a) extends from a first arcuate end 148 of the sidewall 144 to a second arcuate end 150 in the lateral cross-sectional plane, and (b) extends longitudinally from the lateral flame stabilizing ring 120 to the end wall 145 of the flame diverter 112. The lateral opening 146 is preferably oriented to laterally discharge the flame 130 of the auxiliary burner nozzle 102 at an angle of 60° to 120°, more preferably about 90°, relative to the longitudinal axis 106 of the burner shroud housing 104.

[0060] To maintain the stability of the main burner flame 46, the flame deflector 112 preferably laterally and outwardly deflects and guides the auxiliary burner flame 130 to (a) the front end 44 of the burner wall 20, (b) the internal flange, shoulder, or other internal feature of the burner wall 20, or (c) any other stable point of the burner 10. Furthermore, the deflection of the auxiliary burner flame 130 by the flame deflector 112 advantageously provides a staged air operation mode for the substoichiometric auxiliary burner 102, which reduces NO generated by the auxiliary burner 102. X emission.

[0061] In the staged air operation of the auxiliary burner nozzle 102, a substoichiometric, fuel-rich, gaseous fuel and oxygen-containing gas (preferably air) mixture flowing from the front end of the mixing chamber 108 begins combustion in a substoichiometric combustion zone 152 within the internal flame space 142, including the flame deflector 112. Next, the auxiliary burner flame 130 is laterally diverted outside the auxiliary burner 102 into the air or other oxygen-containing gas flowing through the internal passage 26 of the burner 10 of the present invention. This diversion of the auxiliary burner flame 130 into the air or other oxygen-containing gas flow creates a lean fuel combustion zone 154 outside the auxiliary burner 102, in which the remaining portion of the unburned gaseous fuel in the substoichiometric combustion zone 152 of the auxiliary burner 102 is burned.

[0062] By burning a first portion of the auxiliary burner fuel in the substoichiometric flame region 152, followed by burning the remaining fuel in the lean flame region 154, the provided staged air operation reduces the peak temperature of the auxiliary burner flame 130 in both regions, and thus reduces the NO produced by the auxiliary burner 102. X And the levels of other emissions.

[0063] Although the burner 10 of the present invention is shown in the drawings as being vertically oriented, it will be understood that the burner 10 may alternatively be oriented downward, horizontally, or at any other desired angle. Furthermore, although various elements and features of the burner 10 of the present invention are shown and may be described as having a cylindrical or circular shape, it will be understood that these elements and features may alternatively be square or elliptical in shape, or may be any other desired shape.

[0064] As illustrated in other embodiments shown and described herein, the burner wall 20 of the burner 10 of the present invention can be circular, square, rectangular, or generally any other desired shape. Furthermore, the series of fuel injectors 36 employed in the burner 10 of the present invention does not need to completely surround the burner wall 20. For example, in certain applications where the burner 10 of the present invention is used at a furnace sidewall location or is specifically configured to provide a desired flame shape, the series of injectors 36 may only partially surround the burner wall 20.

[0065] Furthermore, despite Figures 1-4 Only a single series of injectors 36 surrounding the burner wall 20 is shown, but it should be understood that the burner 10 may have one or more additional series of injectors radially outward and / or radially inward spaced from this series of injectors 36. The main burner flame 46 may also include a single combustion stage or multiple combustion stages. Additional fuel burners or premixed burners for the main burner flame 46 may also be included in the internal passages 26 of the burner wall 10. Furthermore, other possible additional components of the burner 10 may include regenerated bricks, swirlers, and / or stabilizing cones in the burner throat 26, particularly where liquid fuel injection is performed inside the front end of the burner throat 26 or just outside the front end of the burner throat 26.

[0066] To further promote the entrainment and mixing of exhaust gas with the fuel injection flow 50, the burner 10 of the present invention preferably includes one or more external impact structures 42a-c, which may be positioned at least partially within some or all of the path of the flow 50. Each such impact structure 42a-c can generally be any type of obstruction that will sufficiently reduce the flow momentum and / or increase the turbulence of the fuel flow 50 to promote exhaust gas entrainment and mixing, while allowing the resulting mixture to flow onto the main burner flame 46.

[0067] Although other types of impact structures 42a-c can be used, the impact structures 42a-c used in the burner 10 of the present invention are most preferably laminated flanges or other types of features that can be conveniently formed as part of and / or together with the burner wall 20 in the cast refractory material. Additionally, although in Figures 1-4 Three impact flanges 42a-c are shown, but it should be understood that the burner of the present invention may have one to n such stacked flanges 42, and the number n of stacked flanges used in the burner 10 of the present invention will preferably be in the range of 2 to 6.

[0068] The burner wall 20 used in the burner 10 of the present invention provides a particularly desirable layered external shape, wherein the diameter of the base 25 of the burner wall 20 is larger than that of its front end 22, and the exterior of the burner wall 20 has a series of concentric, spaced-apart impact flanges 42a-c. The outermost impact flange 42c is defined by a flat, radially circumferential shoulder 44 at the front end 22 of the burner wall 20. Then at least one, preferably at least two, additional impact flanges 42a and 42b are positioned on the exterior of the burner wall 20 between the injector 36 and the front shoulder / flange 42c. From the outer end 22 of the burner wall 20 to the base 25, each additional flange 42 is preferably wider in diameter than the preceding flange 42 and is longitudinally rearward and laterally outwardly spaced from the preceding flange.

[0069] Depending on the characteristics and dimensions of the heating system using the burner 10 of the present invention, and the required heat output, the size and dimensions of the burner 10 can vary from small to very large. Therefore, the longitudinal height 60a-c of each layered flange 42a-c of the burner 10 can range from 0.05 to 10 inches or greater. However, for most applications, the longitudinal height 60a-c of each flange 42a-c will preferably be in the range of 2 to 5 inches. Similarly, the radial width 62a-c of each impact flange 42a-c can range from 0.05 to 10 inches or greater. However, for most applications, the radial width 62a-c of each impact flange 42a-c will preferably be in the range of 0.5 to 3 inches, and more preferably in the range of 1 to 2 inches.

[0070] For example, such as Figure 1 As shown, the internal passage 26 extending through the burner wall 20 can be a conical throat, the diameter of which at the base 25 is larger than the diameter at the outer end 22 of the burner wall 20. Figure 1 The conical throat 26 of the type shown provides a blockage point for the flow of air or other oxygen-containing gases, which increases the flow velocity and creates even more pressure-reducing zones at the outer end 22 of the burner 10. This enhanced pressure-reducing zone helps to (a) keep the main burner flame 46 on or closely adjacent to the circumferential radial shoulder 44 at the front end 22 of the burner wall 20, and (b) draw additional exhaust gases into the main flame combustion mixture.

[0071] Because the total amount of fuel used in the burner 10 of the present invention is so well regulated by the furnace exhaust gas, combustion occurs at a significantly reduced rate and a lower flame temperature, thus resulting in lower NO. x emission,

[0072] Figure 9An alternative embodiment 55 of the burner of the present invention is shown. The burner 55 is substantially the same as the burner 10, except that the outer surface of the burner wall 20 is substantially cylindrical in shape, such that the burner wall 20 has only a single impact flange 42 disposed at its outer end 44. The longitudinal height 68 of the single impact flange 42 can range from 0.05 to 20 inches or greater, and will more typically range from 2 to 5 inches. The radial width 70 of the circumferential shoulder 42 at the front end of the burner wall 20 of the burner 55 can range from 0.05 to 15 inches or greater, and will more typically range from 0.2 to 2.25 inches.

[0073] Figure 10 Another alternative embodiment 66 of the burner of the present invention is shown, which is substantially the same as the burner 10 except that the burner 66 has an inclined impact surface 43 disposed on the exterior of the burner wall 20. The inclined surface 43 tapers inward toward the outer end 44. The longitudinal height 74 of the rear end 76 of the inclined surface 43 can be in the range of 0.05 to 20 inches or more, and will more typically be in the range of 2 to 5 inches. The longitudinal distance 77 from the rear end 76 of the inclined surface 43 to the outer end 44 of the burner wall 20 of the burner 66 can be in the range of 0.05 to 20 inches or more, and will more typically be in the range of 2 to 5 inches. The radial width 78 of the circumferential shoulder 44 at the front end of the burner wall of the burner 66 can be in the range of 0.05 to 15 inches or more, and will more typically be in the range of 0.2 to 2.25 inches.

[0074] Figure 11 Another alternative embodiment 90 of the burner of the present invention is shown, which is the same as the burner 10 except that the burner 90 is rectangular in shape instead of circular. Figure 11 This is a top view of a rectangular burner 90, wherein the burner wall 92 has multiple layered external impact flanges 98. Multiple fuel injector nozzles 96 are located on the outer periphery of the burner wall 92, and a pair of auxiliary burners 102 are positioned in an internal flow passage 94 as described above. A burner igniter 95 may optionally be located within the internal passage 94 to initiate combustion at the outer end 100 of the burner wall 92. The spacing of the fuel injector nozzles 96, the size of the injection ports, the spacing of the auxiliary burners 102, the dimensions of the impact flanges, etc., are preferably all the same as described above for burner 10.

[0075] Figure 12 and Figure 13 A type of structure is described that can be used desirably in any of the above embodiments to improve the decompression zone at the outer end of the burner wall. Figure 12The structure employed is an inner flange 81 that forms a radial shoulder directly inside the outer end 82 of an internal passage 83 for air or other oxygen-containing gas. The longitudinal depth 84 of the flange 81 can range from 0.05 to 5 inches or greater, and will more typically range from 0.25 to 1 inch. The radial width 85 of the flange 81 can range from 0.05 to 5 inches or greater, and will more typically range from 0.2 to 1.5 inches. The radial width 86 of the circumferential shoulder 87 at the front end 82 of the burner wall can range from 0.05 to 2 inches or greater, and will more typically range from 0.5 to 1.25 inches.

[0076] Figure 13 The structure employed is a skewed (tilted) outwardly radiating surface 88 formed directly inside the outer end 89 of the internal passage 91 for air or other oxygen-containing gas. The longitudinal depth 93 of the skewed surface can range from 0.05 inches to 5 inches or greater, and will more typically range from 0.25 inches to 1 inch. The radial width 97 of the skewed surface can range from 0.05 to 5 inches or greater, and will more typically range from 0.2 to 1.5 inches. The radial width 99 of the circumferential shoulder 101 at the front end 89 of the burner wall can range from 0.05 to 2 inches or greater, and will more typically range from 0.5 to 1.25 inches.

[0077] Figure 12 and Figure 13 Structure or similar Figure 12 and Figure 13 These structures further enhance the decompression zone at the outlet end of the airflow path to help stabilize the main burner flame by drawing and maintaining the combustion flame to the outside / front end of the burner wall. The decompression zone also helps mix combustion air or other oxygen-containing gases with the fuel stream and exhaust gas.

[0078] The burner 10 or other burner provided by this invention can be a novel burner, or it can be an existing free-jet burner in the prior art that has been improved to maintain low NO levels. x While venting, blockage is prevented. Existing burners typically include: (i) a burner wall, (ii) an internal passageway of the burner wall for air or other oxygen-containing gas to flow out of the front end of the burner wall, and (iii) a series of x primary injectors positioned outside and spaced around the internal passageway of the burner wall to deliver fuel from the injectors in a free jet flow directly or indirectly outside the burner wall to the main burner flame located at and / or in front of the front end of the burner wall.

[0079] According to another aspect of the method of the invention, the existing free-injection burner of the prior art is preferably improved by: (a) increasing the nozzle-to-nozzle spacing of the injectors by removing every other primary injector, such that the number of remaining injectors will (i) be half of the number x of the primary injectors if the number x of the primary injectors is even, or (ii) not greater than ((x-1) / 2)+1 if the number of the primary injectors is odd; (b) replacing each of the remaining injectors with an anti-clogging injector having a large fuel injection port with a flow area of ​​at least 0.0068 square inches; and (c) stabilizing the main burner flame by installing at least two auxiliary burner nozzles in the internal passage of the burner wall, each of the at least two auxiliary burner nozzles directing the auxiliary nozzle flame to a surrounding shoulder at the front end of the burner wall or to a flange or other internal feature of the burner wall.

[0080] Regarding the original injectors removed from the existing burner, a plug will preferably be used to seal the location of the riser in the external fuel supply manifold connecting these injectors. If the remaining injectors include injector nozzles positioned at the end of the fuel riser, the injection port will preferably be replaced by removing the original nozzle from the riser and installing a new nozzle with a larger injection port on the existing riser. The larger port of the new nozzle will preferably have a flow area of ​​at least 0.0068 square inches, as mentioned above, and will more preferably have a flow area of ​​at least 0.012 square inches.

[0081] The auxiliary burner nozzle can be any nozzle that prevents clogging and provides low NO. x The exhaust burner. Each auxiliary burner burner will preferably be a substoichiometric staged air burner burner or a lean premixed burner burner. Each auxiliary burner burner will more preferably be as described above and as... Figures 5-8 The substoichiometric graded air burner nozzle 102 is shown. Also as described above, the fuel supply line extending to the gas fuel connector 110 of each auxiliary burner nozzle 102 will preferably include an orifice connector 136 having a flow orifice therein. This orifice will preferably have a flow area of ​​at least 0.0068 square inches, more preferably at least 0.012 square inches, and the flow area of ​​the fuel port 132 of the gas fuel connector 110 will preferably be larger than the flow area of ​​the flow orifice.

[0082] Therefore, the present invention is highly suitable for achieving these objectives and obtaining the results and advantages mentioned above, as well as those inherent therein. While presently preferred embodiments have been described for the purposes of this disclosure, many changes and modifications will be apparent to those skilled in the art. These changes and modifications are included within the scope of the invention as defined by the claims.

Claims

1. A method for providing reduced NO x An exhaust combustor, wherein the combustor is used in a heating system in which exhaust gas is present, and the combustor includes (i) a combustor wall having a front end, (ii) an internal passage of the combustor wall for air or other oxygen-containing gas to flow out from the front end of the combustor wall, and (ii) a series of injectors positioned to deliver fuel from outside the combustor wall directly or indirectly to the main burner flame at and / or in front of the front end of the combustor wall in a free-flowing manner, the combustor comprising: The injector uses a large fuel injection port with a flow area of ​​at least 0.0068 square inches, which provides anti-clogging properties; The use of a wide nozzle-to-nozzle spacing, ranging from 2 to 14 inches, between the injectors provides enhanced recirculation of exhaust gas to the main combustor flame for the free jet flow from the large fuel injection ports. as well as One or more auxiliary burner nozzles are used in the internal passages of the burner wall to stabilize the main burner flame. Each auxiliary burner nozzle has a large fuel discharge port with a flow area of ​​at least 0.012 square inches, which provides anti-clogging properties. Each of the one or more auxiliary burner nozzles is a substoichiometric staged air burner nozzle or a lean premixed burner nozzle, and each of the one or more auxiliary burner nozzles comprises: A protective housing having a mixing chamber therein and a longitudinally extending outer wall surrounding the mixing chamber; A gas fuel connector, the gas fuel connector including the large fuel discharge port, the large fuel discharge port of the gas fuel connector being positioned to discharge gas fuel into the rear longitudinal end of the mixing chamber; The transverse base wall of the protective housing at the rear longitudinal end of the mixing chamber has at least a central opening extending through it, the size of which is determined such that the total amount of air or other oxygen-containing gas drawn into the mixing chamber is a substoichiometric amount. A transverse flame stabilizing ring of the shroud housing at the front longitudinal end of the mixing chamber, the flame stabilizing ring having a discharge opening through which it passes for the mixing chamber; and A flame deflector on the front longitudinal end of the protective housing, the flame deflector having an internal flame space forming a substoichiometric combustion zone in which a first portion of a substoichiometric mixture of air or other oxygen-containing gas and gaseous fuel is burned.

2. The burner according to claim 1, wherein, The flow area of ​​the large fuel injection port of the injector is at least 0.012 square inches.

3. The burner according to claim 2, wherein, The wide nozzle-to-nozzle spacing between the injectors ranges from 3.5 to 10 inches.

4. The burner according to claim 1, wherein, The large fuel injection port is positioned longitudinally rearward and laterally outward relative to the front end of the burner wall.

5. The burner according to claim 1, wherein, The large fuel discharge port of the gas fuel connector of each of the one or more auxiliary burner nozzles has a flow area of ​​at least 0.049 square inches.

6. The burner according to claim 1, wherein, The flame deflector of each of the one or more auxiliary burner nozzles includes: The transverse end wall at the front longitudinal end of the flame deflector; and Lateral side opening.

7. The burner according to claim 1, wherein, The burner also includes for each of the one or more auxiliary burner nozzles: Fuel supply lines extending to the gas fuel connector; Orifice fittings in the fuel supply line; as well as The flow orifice in the orifice connector.

8. The burner according to claim 7, wherein, For each of the one or more auxiliary burner nozzles: The large fuel discharge port of the gas fuel connector has a flow area of ​​at least 0.049 square inches; The flow orifice has a flow area of ​​at least 0.012 square inches; and The flow area of ​​the large fuel discharge port of the gas fuel connector is greater than the flow area of ​​the flow orifice.

9. An operation for low NO x A method for discharging fuel from a burner, wherein (a) the burner includes a burner wall having a front end and an internal passage through which an air stream or other oxygen-containing gas stream exits the front end of the burner wall; (b) the burner operates in a heating system; and (c) the method includes the step of: injecting fuel from a series of injectors in a free-flowing jet from outside the burner wall directly or indirectly onto a main burner flame located at and / or in front of the front end of the burner wall, the method comprising: The injector's anti-clogging capability is increased by using a large fuel injection port with a flow area of ​​at least 0.0068 square inches. By using a wide burner-to-burner spacing of 2 to 14 inches between the injectors, the recirculation of exhaust gas in the heating system to the main burner flame is enhanced against the free jet flow from the large fuel injection ports of the injectors; as well as The stability of the main burner flame is enhanced by using one or more auxiliary burner nozzles positioned in internal passages within the burner wall. Each auxiliary burner nozzle has a large fuel discharge port with a flow area of ​​at least 0.012 square inches, providing anti-clogging properties. The method further includes operating each of the one or more auxiliary burner nozzles using a method comprising the following steps: 1) Gas fuel is discharged from the large fuel discharge port into the rear longitudinal end of the mixing chamber of the auxiliary burner nozzle, the mixing chamber having a transverse base wall located at the rear longitudinal end of the mixing chamber, and the transverse base wall having at least a central opening formed therethrough; 2) Using the flow momentum of the gaseous fuel discharged in step (1), a substoichiometric amount of air or other oxygen-containing gas is drawn from the internal passage of the burner through at least the central opening of the transverse base wall to form a substoichiometric, fuel-rich mixture of the air or other oxygen-containing gas and the gaseous fuel in the mixing chamber. 3) A substoichiometric mixture of air or other oxygen-containing gas and gaseous fuel is discharged through a stabilizing ring at the front longitudinal end of the mixing chamber to form a decompression zone at or outside the front longitudinal end of the mixing chamber, stabilizing the auxiliary burner flame of the auxiliary burner nozzle, the auxiliary burner flame having an initial substoichiometric combustion zone in which a first portion of the gaseous fuel in the substoichiometric mixture of air or other oxygen-containing gas and gaseous fuel is burned; and 4) The flame is laterally and outwardly transferred to the airflow or other oxygen-containing gas flow in the internal passage of the burner to form a lean fuel combustion zone in which the remaining portion of the gaseous fuel is burned.

10. The method of claim 9, wherein the flow area of ​​the large fuel injection port of the injector is at least 0.012 square inches.

11. The method of claim 10, wherein the wide nozzle-to-nozzle spacing between the injectors is from 3.5 to 10 inches.

12. The method of claim 9, wherein each of the one or more auxiliary burner nozzles is a substoichiometric staged air burner nozzle or a lean premixed burner nozzle.

13. The method according to claim 9, wherein, The large fuel injection port is positioned longitudinally rearward and laterally outward relative to the front end of the burner wall.

14. The method of claim 9, further comprising operating each of the one or more auxiliary burner nozzles to direct the auxiliary burner flame onto a front end of the burner wall or onto a flange or other internal feature of the burner wall.

15. The method according to claim 9, wherein, Each of the auxiliary burner nozzles has a large fuel discharge port with a flow area of ​​at least 0.049 square inches.

16. The method of claim 15, further comprising, in operating each of the one or more auxiliary burner nozzles, delivering the gaseous fuel through a flow orifice to the large fuel discharge port used in step (1), the flow orifice having a flow area of ​​at least 0.0068 square inches, and the flow area of ​​the large fuel discharge port used in step (1) being greater than the flow area of ​​the flow orifice.

17. The method of claim 9, further comprising, in step (4) of operating each of the one or more auxiliary burner nozzles, laterally displaced the auxiliary burner flame using a flame deflector having a lateral side opening.

18. A method for improving the anti-clogging properties of existing burners while maintaining low NO content. x The method of emission, wherein the burner has (i) a burner wall, (ii) an internal passage in the burner wall for air or other oxygen-containing gas to flow out of the front end of the burner wall, and (iii) a series of x A primary injector, positioned outside and spaced apart from the internal passage of the burner wall, is used to deliver fuel from the injector in a free jet flow directly or indirectly to the front end of the burner wall and / or the main burner flame in front of the front end, the method comprising the following steps: a) Increase the nozzle-to-nozzle spacing by removing every other nozzle, such that the number of remaining nozzles will (i) if the number of the original nozzles x If it is an even number, then it is the number of the original injectors. x Half of, or (ii) if the number of the original injectors x If it is an odd number, then it is no greater than (( x -1) / 2) + 1; b) Replace each of the remaining injectors with an anti-clogging injector having a large fuel injection port with a flow area of ​​at least 0.0068 square inches; and c) The main burner flame is stabilized by installing at least two auxiliary burner nozzles in the internal passage of the burner wall. Each auxiliary burner nozzle has a large fuel discharge port with a flow area of ​​at least 0.012 square inches, which provides anti-clogging properties. Each auxiliary burner nozzle directs the auxiliary flame onto a surrounding shoulder at the front end of the burner wall or onto a flange or other internal feature of the burner wall. Each of the auxiliary burner nozzles is a substoichiometric staged air burner nozzle, comprising: A protective housing having a mixing chamber therein and a longitudinally extending outer wall surrounding the mixing chamber; A gas fuel connector including the large fuel discharge port, the large fuel discharge port being positioned to discharge gas fuel into the rear longitudinal end of the mixing chamber, the large fuel discharge port of the gas fuel connector having a flow area of ​​at least 0.049 square inches; The transverse base wall of the protective housing at the rear longitudinal end of the mixing chamber has at least a central opening through which it is disposed; A transverse flame stabilizing ring of the shroud housing at the front longitudinal end of the mixing chamber, the flame stabilizing ring having an outlet opening through which the mixing chamber is disposed; and A flame deflector, located at the front longitudinal end of the protective housing, laterally deflects the auxiliary burner flame onto the front end of the burner wall or onto the flange or other internal feature of the burner wall. The method further includes operating each of the auxiliary burner nozzles by the following steps. 1) Discharge the gaseous fuel from the large fuel discharge port of the gaseous fuel pipe into the rear longitudinal end of the mixing chamber; 2) Using the flow momentum of the gaseous fuel discharged in step (1), a substoichiometric amount of air or other oxygen-containing gas is drawn from the internal passage of the burner wall, so that it passes at least through the central opening of the transverse base wall, to form a substoichiometric, fuel-rich mixture of air or other oxygen-containing gas and the gaseous fuel in the mixing chamber. 3) Discharging the substoichiometric mixture of air or other oxygen-containing gas and the gaseous fuel through the stabilizing ring to form a depressurization zone at or outside the front longitudinal end of the mixing chamber, stabilizing the auxiliary burner flame, the auxiliary burner flame having an initial substoichiometric combustion zone, in which a first portion of the gaseous fuel in the substoichiometric mixture of air or other oxygen-containing gas and the gaseous fuel is burned; and 4) When the auxiliary burner flame turns laterally, the auxiliary burner flame comes into contact with the airflow or other oxygen-containing gas flow in the internal passage of the burner wall to form a lean combustion zone in which the remaining portion of the gaseous fuel is burned.

19. The method of claim 18, wherein the flow area of ​​the large fuel injection port of each of the anti-clogging injectors is at least 0.012 square inches.

20. The method of claim 18, wherein each of the auxiliary burner nozzles is a substoichiometric staged air burner nozzle or a lean premixed burner nozzle.

21. The method of claim 18, further comprising, for each of the auxiliary burner nozzles, delivering the gaseous fuel to the gaseous fuel connector through a flow orifice having a flow area of ​​at least 0.012 square inches, and wherein the flow area of ​​the large fuel discharge port of the gaseous fuel connector is greater than the flow area of ​​the flow orifice.

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