Burner and method for transient heating

Abstract

a first burner element having a first annular oxidizer nozzle surrounding a first inner fuel nozzle; a second burner element having a second annular oxidizer nozzle surrounding a second inner fuel nozzle, the second burner element being positioned adjacent to the first burner element and spaced apart from the first burner element; and a staging nozzle configured to flow a secondary oxidizer, the staging nozzle being positioned adjacent to the second burner element and spaced apart from the second burner element and separated from the first burner element by the second burner element, wherein the first inner nozzle and the second inner nozzle each have a major axis defined by a length L and a height h f and 5≦L / h f ≦15, the staging nozzle has a longitudinal axis, and the longitudinal axes of the first and second inner nozzles and the staging nozzle are substantially parallel to one another.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Non-Provisional Patent Application No. 17 / 854,782, filed June 30, 2022.

[0002] The present innovation relates to transient heating burners and methods, and apparatus (e.g., reverberatory furnaces, burners for reverberatory furnaces, etc.) that use the burners and methods for transient heating, as well as operating aspects of the apparatus, and methods for making and using them. [Background technology]

[0003] Oxy-fuel burners are known for providing primary or supplemental heat to furnaces for a wide range of industrial applications. The applicant owns several such patents, including U.S. Pat. Nos. 7,390,189, 8,806,897, and 10,584,051 (various designs and applications of flat-flame staging burners), as well as U.S. Pat. Nos. 9,360,257, 9,976,721, 9,657,945, and 9,689,312, and U.S. Patent Publication No. 2021 / 0116125 (various designs and applications of burners with multiple burner elements that can be active or passive to induce higher or lower levels of heat in specific portions of a furnace). Summary of the Invention

[0004] This application describes burner embodiments that selectively direct larger flames to one or more portions of the furnace and selectively direct smaller flames to another one or more portions of the furnace to allow for greater control of temperature distribution within the furnace.

[0005] Aspect 1. A burner for transient heating of a furnace, the burner comprising: a burner face configured to be positioned on an inner surface of the furnace when the burner is installed in the furnace, the burner face defining a burner face plane; a first burner element having a first annular nozzle configured to flow a primary oxidizer surrounding a first inner nozzle configured to flow a fuel; a second burner element having a second annular nozzle configured to flow the primary oxidizer surrounding a second inner nozzle configured to flow a fuel, the second burner element positioned adjacent to the first burner element and spaced apart from the first burner element; and a staging nozzle configured to flow a secondary oxidizer positioned adjacent to the second burner element. and a staging nozzle disposed between the first burner element and the second burner element and spaced apart from the second burner element, wherein the second burner element is positioned between the staging nozzle and the first burner element, wherein the first inner nozzle and the second inner nozzle each have a major axis defined by a major axis length L measured in the burner face plane, a minor axis defined by a minor axis height hf measured in the burner face plane, and a fuel nozzle aspect ratio of 5≦L / hf≦15, and the staging nozzle has a major axis defined by a major axis length X measured in the burner face plane and a minor axis defined by a minor axis height Y measured in the burner face plane, wherein the major axis of the first inner nozzle, the major axis of the second inner nozzle, and the major axis of the staging nozzle are substantially parallel to one another within a deviation of 5° or less.

[0006] Aspect 2. The burner of Aspect 1, wherein the staging nozzle has an aspect ratio of 10≦X / Y≦40.

[0007] Aspect 3. The burner of aspect 1 or 2, wherein 1≦X / L≦2.5.

[0008] Aspect 4. The burner of any one of Aspects 1-3, wherein the second burner element is spaced apart from the first burner element by a distance H1, where 2≦H1 / hf≦20, and the staging nozzle is spaced apart from the second burner element by a distance H2, where 2≦H2 / hf≦20.

[0009] Aspect 5. The minor axis of the first inner nozzle is offset from the minor axis of the second inner nozzle by a distance B, and

[0010] Aspect 6. The burner of any one of Aspects 1-5, further comprising a pilot flame port positioned adjacent to the first burner element and spaced a distance H3 from the first burner element, the first burner element being positioned between the second burner element and the pilot flame port, and wherein 2≦H3 / hf≦20.

[0011] Aspect 7. A first fuel conduit configured to supply fuel to a first inner nozzle, the first fuel conduit having a longitudinal axis aligned with a direction of fuel flow in the first fuel conduit, the longitudinal axis intersecting a burner face plane at an angle α to a normal to the first inner nozzle and at a complementary angle (90°-α) to the longitudinal axis of the first inner nozzle; and a second fuel conduit configured to supply fuel to a second inner nozzle, the second fuel conduit having a longitudinal axis aligned with a direction of fuel flow in the first fuel conduit, the longitudinal axis intersecting a burner face plane at an angle α to a normal to the first inner nozzle and at a complementary angle (90°-α) to the longitudinal axis of the first inner nozzle. 7. The burner of any one of aspects 1-6, further comprising: a second fuel conduit having a longitudinal axis aligned with a direction of fuel flow in the conduit, the longitudinal axis intersecting the burner face plane at an angle α relative to a normal to the second inner nozzle and at a complement angle (90°-α) to the longitudinal axis of the second inner nozzle, wherein the longitudinal axes of the first fuel conduit and the second fuel conduit are angled at an angle 2α relative to each other, where 0<α≦20°.

[0012] Embodiment 8. The burner of embodiment 7, wherein 5°<α≦20°. ​

[0013] Aspect 9. The burner of Aspect 7 or 8, wherein the longitudinal axis of the first fuel conduit intersects the plane defined by the major and minor axes of the first inner nozzle at an angle β relative to the normal to the first inner nozzle and at a complementary angle (90°-β) to the minor axis of the first inner nozzle, and the longitudinal axis of the second fuel conduit intersects the plane defined by the major and minor axes of the second inner nozzle at an angle β relative to the normal to the second inner nozzle and at a complementary angle (90°-β) to the minor axis of the second inner nozzle, and the longitudinal axis of the first fuel conduit and the longitudinal axis of the second fuel conduit are each angled away from the staging nozzle, and wherein 0<β≦10°.

[0014] Aspect 10. A first fuel conduit configured to supply fuel to a first inner nozzle, the first fuel conduit having a longitudinal axis aligned with a direction of fuel flow in the first fuel conduit, the longitudinal axis intersecting a burner face plane at an angle β to a normal to the first inner nozzle and at a complementary angle (90°-β) to a minor axis of the first inner nozzle; and a second fuel conduit configured to supply fuel to a second inner nozzle, the second fuel conduit having a longitudinal axis aligned with a direction of fuel flow in the first fuel conduit, the longitudinal axis intersecting a burner face plane at an angle β to a normal to the first inner nozzle and at a complementary angle (90°-β) to a minor axis of the first inner nozzle. 7. The burner of any one of aspects 1-6, further comprising: a second fuel conduit having a longitudinal axis aligned with the direction of fuel flow, the longitudinal axis intersecting the burner face plane at an angle β with respect to the normal to the second inner nozzle and at a complement angle (90°-β) with respect to the minor axis of the second inner nozzle, wherein the longitudinal axis of the first fuel conduit and the longitudinal axis of the second fuel conduit are each angled away from the staging nozzle, and wherein 0<β≦10°.

[0015] Embodiment 11. The burner of any one of embodiments 1-10, wherein a total fuel flow and a total oxidizer flow are provided to the burner in an equal ratio, an equivalence ratio of 1 indicating a stoichiometric ratio of fuel to oxidizer, an equivalence ratio greater than 1 indicating a fuel-rich stoichiometry, and an equivalence ratio less than 1 indicating a fuel-lean stoichiometry, and wherein the burner further comprises a controller, the controller being programmed to: independently control the fuel flow to each of the first inner nozzle and the second inner nozzle; and control a distribution of the total oxidizer flow to consist of a primary oxidizer flow distributed between the first annular nozzle and the second annular nozzle and a secondary oxidizer flow provided to the staging nozzle, and wherein the primary oxidizer flow is between 60% and 95% of the total oxidizer flow.

[0016] Aspect 12. The burner of aspect 11, wherein the primary oxidant flow is distributed between the first annular nozzle and the second annular nozzle in a ratio of 0.9 to 1.1.

[0017] Aspect 13. The burner of Aspects 11 or 12, wherein the controller is programmed to operate the burner in a proportional mode in which total fuel flow is supplied to the first inner nozzle and the second inner nozzle such that the equivalence ratio of the first burner element is between 1.05 and 1.5, and the equivalence ratio of the second burner element is between 1.05 and 1.5.

[0018] Aspect 14. The burner of any one of aspects 11-13, wherein the controller is programmed to operate the burner in an alternating mode in which the distribution of total fuel flow between the first inner nozzle and the second inner nozzle alternates back and forth between a first state in which the first burner element is active but the second burner element is passive, and a second state in which the first burner element is passive but the first burner element is active, wherein the active burner element is characterized by an equivalence ratio of 1.4 to 3 and the passive burner element is characterized by an equivalence ratio of 0.1 to 1.

[0019] Aspect 15. The burner of aspect 14, wherein the controller is programmed to switch between the first state and the second state based on one or more of the passage of a predetermined period of time and data from a sensor positioned to detect at least one condition in the furnace.

[0020] Aspect 16. The burner of any one of aspects 1-15, wherein the first and second annular nozzles each have major and minor axes that coincide with the major and minor axes of the first and second inner nozzles, respectively, the minor axis of each of the first and second annular nozzles being defined by a height ho, fuel exiting each of the first and second inner nozzles at a fuel velocity and primary oxidizer exiting each of the first and second annular nozzles at a primary oxidizer velocity, and the ratio ho / hf is sized to result in a ratio of fuel velocity to primary oxidizer velocity of 1-4.

[0021] Aspect 17. The burner assembly further comprises a pilot flame port positioned below the first burner element, wherein a top of the pilot flame port is vertically spaced a third vertical distance H3 from a bottom of the first annular nozzle, such that 2≦H3 / hf≦20; a bottom of the second burner element is spaced a first vertical distance H1 from a top of the first annular nozzle, such that 2≦H1 / hf≦20; a bottom of the staging nozzle is spaced a second vertical distance H2 from a top of the second annular nozzle, such that 2≦H2 / hf≦20; a minor axis of the first inner nozzle is offset a distance B from a minor axis of the second inner nozzle, such that 0

[0022] ​Aspect 18. A furnace comprising: a wall; a peak; a vessel of solid and / or liquid material; and a burner according to any one of aspects 1-17, wherein the burner is positioned on the wall such that the first burner element is closer to the vessel than the second burner element and the staging nozzle is closer to the peak than the second burner element.

[0023] Embodiment 19. A method of operating the burner of any one of embodiments 1-17 in a furnace, the method including: flowing a total oxidizer flow through the burner, the total oxidizer flow comprising a primary oxidizer flow distributed between a first annular nozzle and a second annular nozzle, and a secondary oxidizer flow provided to a staging nozzle, wherein the primary oxidizer flow is 60%-95% of the total oxidizer flow, and the primary oxidizer flow is distributed between the first annular nozzle and the second annular nozzle in a ratio of 0.9-1.1; flowing a total fuel flow through the burner; and switching operation of the burner between a proportional mode and an alternating mode, wherein in the proportional mode, the total fuel flow is 0.05-0.5 and the equivalence ratio of the first burner element is 1.05-1.5 and the equivalence ratio of the second burner element is 1. and wherein in an alternating mode, the total fuel flow distributed between the first inner nozzle and the second inner nozzle is switched back and forth between a first state in which the first burner element is active but the second burner element is passive, and a second state in which the first burner element is passive but the first burner element is active, the active burner element being characterized by an equivalence ratio of 1.4 to 3 and the passive burner element being characterized by an equivalence ratio of 0.1 to 1, an equivalence ratio of 1 indicating a fuel-to-oxidizer stoichiometry, an equivalence ratio greater than 1 indicating a fuel-rich stoichiometry, and an equivalence ratio less than 1 indicating a fuel-lean stoichiometry.

[0024] Conventional oxy-fuel burner technology is often for oxy-fuel burners that are either a single flame directed at the melt or that burn in the air space above the vessel surface. Most multi-flame burners currently available can be mounted at the top of a reverb furnace. However, in many furnaces, mounting the burner at the top is challenging and they are not considered to operate as fuel-flexible burners. Additionally, next-generation decarbonized, low-GHG-emission fuels may require burners that can be used with traditional fuels like natural gas, while also being flexible in the preferred fuel type, such as being able to operate with a natural gas / hydrogen blend or pure hydrogen.

[0025] It has also been found that melting furnaces often require uniform heat distribution within the furnace to improve the furnace's overall melting characteristics. Flameless combustion is one such approach that helps provide improved uniformity of heat distribution. However, flameless combustion does not generate soot, which can reduce overall heat transfer to the vessel surface due to the lack of radiative heat transfer from the soot to the vessel. It has been determined that in melting furnaces, it is desirable to increase the radiative heat flux from soot particles to the melt while also providing improved uniformity of heat distribution within the furnace. It can be important that the amount of soot generated is completely oxidized within the furnace volume, with no soot exiting through the furnace flue. Embodiments of the burner apparatus of the present invention can help to solve these problems.

[0026] New burner embodiments of the present invention can be configured as two-stage transient heating burners, which helps improve heat transfer to the bath / melt and reduce the possibility of melt overheating. Additionally, the burners can be fuel-flexible, running on decarbonized fuels such as hydrogen and hydrogen / natural gas mixtures. Furthermore, embodiments can utilize low-pressure oxygen, which can provide lower nitrous oxide (NOx) emissions compared to traditional oxy-fuel burners and help save on operating costs. New burner embodiments can be combined with other air-fuel or oxy-fuel burners, or used as a stand-alone oxy-fuel burner, in a melting furnace for improved furnace operation, which can provide faster melting times, increased energy efficiency, fuel savings, and potentially increased production.

[0027] Burner embodiments can be constructed and configured as both fuel-staged and oxidizer-staged. Dual staging can help achieve lower NOx production in the furnace compared to conventional single-fuel oxy-fuel burners. Oxidant staging of the burner can help reduce oxygen near the vessel surface, which can help avoid vessel surface oxidation. Avoidance or reduction of vessel surface oxidation compared to air-fuel burners or conventional oxy-fuel burners can maintain or improve furnace yield during furnace operation.

[0028] Additionally, new burner embodiments may be fuel flexible and may run on traditional fuels (e.g., natural gas) as well as low carbon intensity fuels (e.g., hydrogen) and / or mixtures of traditional fuels and emerging alternative fuels.

[0029] In plants where the top is not accessible, one embodiment of the burner of the present invention can be constructed as a sidewall-mounted flat-frame burner, which can provide a practical way to install the burner embodiment of the present invention. Additionally, the two configurations of the burner of the present invention (top-mountable and sidewall-mountable, which can also be considered as vertical and horizontal burner embodiments) can be used together in the same furnace to improve the overall functionality of the industrial melting furnace.

[0030] As discussed above, it has been found desirable to provide a furnace burner that helps mitigate, if not avoid, the generation of NOx during the combustion of fuel. Some burner embodiments may be configured to allow the burner to be retrofitted into existing furnaces (e.g., existing reverberatory furnaces, which may also be called reverberation furnaces). Burner embodiments may be configured to replace conventional burners in existing furnaces or may be utilized in combination with existing conventional burners to improve performance while also reducing NOx emissions. Other embodiments may be utilized to completely replace all of the conventional existing burners in a furnace, or may be included in new furnace installations that may be configured to provide transient heating.

[0031] In some configurations, embodiments can be provided in which burners can be positioned above the furnace vessel and on the sidewalls of the reverberatory furnace below the furnace ceiling (or peak). The burners can be adapted to allow the fuel supplied to the burners to be entirely natural gas, entirely hydrogen, or a mixture of hydrogen and natural gas. Other embodiments can utilize different mixtures of fuels that can include only hydrogen, hydrogen mixed with hydrocarbon fuels (e.g., natural gas, oil, etc.), and only hydrocarbon-based fuels (e.g., natural gas, oil, etc.). In some embodiments, the burners can be positionable to provide transient heating for metallic materials positioned in the vessel below the burners. In some configurations, the metallic material in the vessel can be metal for aluminum melting, iron melting, or other types of metal melting operations.

[0032] In some embodiments, the burner may utilize first and second burner elements positioned below an oxidizer nozzle positioned to output an oxidizer stream. The first and second burner elements may each include an inner opening for discharging fuel and an annular-shaped outer opening for discharging an oxidizer stream having oxygen therein, the outer opening surrounding the inner opening through which the fuel can be discharged. The first and second fuel burner elements may be connected to a fuel flow control manifold assembly configured to provide fuel to the first and second burner elements. The fuel may be, for example, hydrogen gas, natural gas, or a mixture of natural gas and hydrogen. The outer openings for the first and second fuel burner elements may be connected to a source of oxidizer for outputting oxygen. The oxidizer source may be the output from a cryogenic air separation unit that provides the oxygen stream to the burner elements, or may be another source of an oxidizer stream that may include oxygen therein (e.g., air, a gas mixture containing a sufficient concentration of oxygen, a fluid mixture containing a sufficient concentration of oxygen, etc.). The first and second burner elements may be positioned in a preselected alignment with one another to facilitate the formation of a stable flame having a low NOx emissions profile.

[0033] The burner elements may also be arranged and positioned to operate in combination with the upper oxidizer nozzle such that a preselected fuel rate, a preselected oxidizer flow rate, a preselected level of fuel staging, and a preselected level of oxidizer staging are provided to help facilitate the formation of a stable flame with a low NOx emissions profile. The preselected arrangement may include, for example, (1) offset positioning of the first lower burner element and the second upper burner element in the lateral dimension along the wall within a first preselected orientation threshold, while also including (2) a vertical spacing between the first burner element and the second burner element within a first preselected vertical spacing threshold, (3) a vertical spacing between the upper second burner element and the top oxidizer nozzle within a first preselected oxidizer nozzle spacing threshold, and (4) a vertical spacing between the lower first burner element and a pilot flame outlet located below the first burner element within a first preselected pilot flame spacing threshold. The lengths and widths of the different nozzles of the burner elements may also be within preselected length and width ranges and, working in combination with these preselected thresholds, help to facilitate the formation of a stable flame with a low NOx emission profile. The first and second burner elements may also be configured to include a preselected tilt angle ranging from -10° to 10° to provide upslope, horizontal, or downslope flow of fuel and oxidizer, and a preselected horizontal orientation, such that the burner elements may cause the fuel and / or oxidizer streams to exit at a horizontal angle ranging from 20° to 20° relative to a line from the wall (e.g., at an angle of 0°).

[0034] One or more burner embodiments included in the reverberatory furnace can help limit oxygen near the vessel surface. Such a feature can help reduce or maintain oxidation of the metal vessel at a baseline level. Embodiments can also provide low backpressure for the oxygen flow to avoid the need to use a high-pressure oxygen source for the oxidant flow. For example, some embodiments have been found to be capable of reducing NOx emissions by as much as 50%. These improved results can be achieved while improving the efficiency of furnace operation. In some embodiments, for example, it is believed that the efficiency of furnace operation in hybrid mode (replacing one air-fuel burner in the reverberatory furnace with one transient heating burner) can be improved by approximately 9%, production can be increased by approximately 26%, and fuel savings of approximately 26% can be achieved. While these improvements can be achieved, the furnace can be adapted to run on a decarbonized fuel source (e.g., hydrogen as fuel) to reduce carbon emissions in addition to reducing NOx emissions.

[0035] An apparatus for transient heating is provided. The apparatus may include at least one burner positionable on a wall or a top of the apparatus for transient heating above a vessel of the apparatus for transient heating. Each of the at least one burner may include a first burner element having a first outer oxidant flow outlet surrounding a first inner fuel outlet and a second burner element having a second outer oxidant flow outlet surrounding a second inner fuel outlet, the second burner element being positioned above the first burner element, and an upper oxidant flow nozzle being positioned above the second burner element.

[0036] An embodiment of the apparatus for transient heating may be a reverberatory furnace or other type of furnace or transient heating device. At least one burner may be positioned on a sidewall of the furnace above a vessel. The vessel may be positioned to hold a metal for melting. The metal may be aluminum, steel, or another type of metal.

[0037] Embodiments can be adapted so that one or more burners have a particular structure and arrangement. For example, a first inner fuel outlet for a burner can have a height hf and a length L measured at the burner face plane 10 fp, and a second inner fuel outlet can also have hf and L measured at the burner face plane 10 fp. The top of the first outer oxidizer outlet can be vertically spaced a first vertical distance H1 from the bottom of the second outer oxidizer outlet, and the top of the second outer oxidizer outlet can be vertically spaced a second vertical distance H2 from the bottom of the oxidizer outlet of the upper oxidizer flow nozzle such that (a) 2≦H1 / hf≦20, and (b) 2≦H2 / hf≦20, where ≦ is less than or equal to: The second inner fuel outlet and the first inner fuel outlet may also be positioned such that the center of the first inner fuel outlet is horizontally spaced apart from the center of the second inner fuel outlet by an offset distance B (such that 0≦B / L≦1.5).

[0038] Each burner may also include, in some embodiments, a pilot flame port positioned below the first burner element. The top of the pilot flame port may be vertically spaced a third vertical distance H3 (such that 2≦H3 / hf≦20) from the bottom of the first outer oxidant outlet.

[0039] The upper oxidant flow nozzle may have an oxidant outlet having a length X measured at the burner face plane 10 fp and a height Y measured at the burner face plane 10 fp, such that 10≦X / Y≦40 and 1≦X / L≦2.5. Other embodiments may utilize different length and height specifications for the oxidant outlet of the upper oxidant flow nozzle.

[0040] As noted above, the first inner fuel outlet can have a height hf and a length L, and the second inner fuel outlet can also have hf and L. The second inner fuel outlet and the first inner fuel outlet can be positioned such that the center of the first inner fuel outlet is horizontally spaced apart from the center of the second inner fuel outlet by an offset distance B (such that 0.0≦B / L≦1.5). In such an embodiment, the height hf and the length L can also be defined such that 5≦L / hf≦15.

[0041] Embodiments of the apparatus for transient heating may also include other elements. For example, embodiments may include a make-up conduit for the second inner fuel outlet of the second burner element, extending linearly from the fuel make-up conduit of the second burner element to the second inner fuel outlet of the second burner element at a first preselected horizontal angle relative to the horizontal direction in which the pilot flame make-up conduit extends linearly to the pilot flame port. Additionally, there may be a make-up conduit for the first inner fuel outlet, extending linearly from the fuel make-up conduit of the first burner element to the first inner fuel outlet at a second preselected horizontal angle relative to the horizontal direction in which the pilot flame make-up conduit extends linearly to the pilot flame port. The first preselected horizontal angle may be in the range of +5° to +20° or greater than 0° and less than 20°, and the second preselected horizontal angle may be in the range of -5° to -20° or less than 0° and less than -20°. Alternatively, the first preselected horizontal angle may be in the range of -5° to -20° or less than 0° and less than or equal to -20°, and the second preselected horizontal angle may be in the range of +5° to +20° or more than 0° and less than or equal to 20°. Other angle ranges for the first and second preselected horizontal angles may alternatively be utilized.

[0042] The burner elements can also be oriented and positioned to provide upslope or downslope output. For example, the first and second burner elements can be configured to include a preselected tilt angle ranging from -10° to 10° to provide upslope, horizontal, or downslope flow of fuel and oxidant. For example, the tilt angle of the make-up conduit or the first and second inner fuel outlets can be greater than 0° and less than or equal to +10°, or less than 0° and greater than or equal to -10°. The tilt angle of the first burner element (and first inner fuel outlet) can be different from the tilt angle of the second burner element (and second inner fuel outlet), or the tilt angle can be the same for the first and second burner elements (and first and second inner fuel outlets). The inclination angle of the first outer oxidant outlet may be the same as the inclination angle of the first burner element and / or the first inner fuel outlet, and the inclination angle of the second outer oxidant outlet may be the same as the inclination angle of the second burner element and / or the second inner fuel outlet (e.g., their inclination angles may be in the range of -10° to +10°, etc.).

[0043] As another example, embodiments of an apparatus for transient heating may also include a control system positioned to control operation of the burner to switch the operating modes of the first and second burner elements of the burner between an active mode and a passive mode of operation. The control system may have a feedback control loop defined to select between the active and passive modes of operation of the first and second burner elements based on sensor data from sensors positioned within the apparatus or positioned to detect one or more conditions within the apparatus.

[0044] A method of operating a transient heating apparatus is also provided. An embodiment of the method may include positioning at least one burner on a wall of the transient heating apparatus above a vessel of the transient heating apparatus. Each of the at least one burner may be an embodiment of the burner described above. For example, each burner may include a first burner element having a first outer oxidant flow outlet surrounding a first inner fuel outlet and a second burner element having a second outer oxidant flow outlet surrounding a second inner fuel outlet, the second burner element being positioned above the first burner element and the upper oxidant flow nozzle being positioned above the second burner element.

[0045] Embodiments of the method may include other steps. For example, the method may also include starting at least one burner such that the first burner element and the second burner element are in an active mode, such that the first and second burner elements operate at an equivalence ratio of 1.05 to 1.5. As another example, after the apparatus for transient heating operates at a preselected operating temperature above the autoignition temperature of the fuel refueling the at least one burner, the first burner element may be switched from an active mode to a passive mode. Thereafter, the first burner element may be switched from a passive mode to an active mode, while the second burner element may be switched from an active mode to a passive mode after a first preselected period of time. The active mode may be a mode in which the equivalence ratio is 1.4 to 3.0, and the passive mode may be a mode in which the equivalence ratio is 0.1 to 1.0.

[0046] Embodiments of the method may also include operating at least one burner such that (1) the oxidant output from the oxidant flow outlet of the upper oxidant flow nozzle is between 5% and 40% by volume of the total oxidant flow rate from the burner, and (2) the oxidant output from the first burner element is at a flow rate within 10% of the oxidant flow rate of the oxidant output from the second burner element.

[0047] Burner embodiments for transient heating devices are also provided. Burner embodiments can include the burner embodiments described above. For example, the burner can include a first burner element having a first outer oxidant flow outlet surrounding a first inner fuel outlet, and a second burner element having a second outer oxidant flow outlet surrounding a second inner fuel outlet, the second burner element being positioned above the first burner element, and the upper oxidant flow nozzle being positioned above the second burner element. Burner embodiments can also include other elements and features discussed above.

[0048] For example, a burner for transient heating of a furnace can include a burner face configured to be positionable on an inner surface of the furnace when the burner is installed in the furnace. The burner face can define a burner face plane. The burner can also include a first burner element having a first annular nozzle configured to flow a primary oxidant surrounding a first inner nozzle configured to flow a fuel, and a second burner element having a second annular nozzle configured to flow a primary oxidant surrounding a second inner nozzle configured to flow a fuel. The second burner element can be positioned adjacent to the first burner element and spaced apart from the first burner element. The staging nozzle can be configured to flow a secondary oxidant. The staging nozzle can be positioned adjacent to the second burner element and spaced apart from the second burner element such that the second burner element can be positioned between the staging nozzle and the first burner element. The first inner nozzle and the second inner nozzle may each have a major axis defined by a major axis length L measured at the burner face plane, a minor axis defined by a minor axis height hf measured at the burner face plane, and a fuel nozzle aspect ratio of 5≦L / hf≦15. The staging nozzle may have a major axis defined by a major axis length X measured at the burner face plane, and a minor axis defined by a minor axis height Y measured at the burner face plane. The major axes of the first inner nozzle, the second inner nozzle, and the staging nozzle may be substantially parallel to one another within a deviation of 5° or less.

[0049] The different dimensions of the first and second burner elements and the staging nozzle can be adapted to meet a preselected set of design criteria. For example, the length and height of the staging nozzle can be selected so that the staging nozzle has an aspect ratio of 10≦X / Y≦40. The burner elements and staging nozzle can also be sized and configured so that 1≦X / L≦2.5.

[0050] The burner elements and staging nozzles can also be spaced from one another to meet preselected design criteria. For example, the second burner element can be spaced from the first burner element by a distance H1, where 2≦H1 / hf≦20, and the staging nozzle can be spaced from the second burner element by a distance H2, where 2≦H2 / hf≦20. The burner can also include a pilot flame port positioned adjacent to the first burner element and spaced from the first burner element by a distance H3, where 2≦H3 / hf≦20.

[0051] The burner element may also have other spatial design criteria. For example, the minor axis of the first inner nozzle may also be 0.

[0052] As yet another example of space and sizing design criteria that may be utilized for the burner, the burner may also include a pilot flame port, as described above. The pilot flame port may be positioned below the first burner element. The top of the pilot flame port may be vertically spaced a third vertical distance H3 (such that 2≦H3 / hf≦20) from the bottom of the first annular nozzle. The bottom of the second burner element may be spaced a first vertical distance H1 from the top of the first annular nozzle, where 2≦H1 / hf≦20. The bottom of the staging nozzle may be spaced a second vertical distance H2 from the top of the second annular nozzle, where 2≦H2 / hf≦20. The minor axis of the first inner nozzle may also be spaced a third vertical distance H3 from the top of the first annular nozzle, where 2≦H1 / hf≦20.

[0053] ​​The burner may also include a fuel conduit that can supply fuel to the first and second inner nozzles of the first and second burner elements. For example, the burner may have a first fuel conduit configured to supply fuel to the first inner nozzle. The first fuel conduit may have a longitudinal axis aligned with the direction of fuel flow in the first fuel conduit. The longitudinal axis may intersect the burner face plane at an angle α relative to the normal to the first inner nozzle and at a complementary angle (90°-α) to the longitudinal axis of the first inner nozzle. The second fuel conduit may be configured to supply fuel to the second inner nozzle. The second fuel conduit may have a longitudinal axis aligned with the direction of fuel flow in the second fuel conduit. The longitudinal axis of the second fuel conduit may intersect the burner face plane at an angle α relative to the normal to the second inner nozzle and at a complementary angle (90°-α) to the longitudinal axis of the second inner nozzle. The longitudinal axis of the first fuel conduit and the longitudinal axis of the second fuel conduit may be angled relative to one another at an angle of 2α or other preselected angle value, and in some configurations, the angle α may be in the range of 0<α≦20° or 5°<α≦20°.

[0054] The first fuel conduit configured to supply fuel to the first inner nozzle and having a longitudinal axis aligned with the direction of fuel flow in the first fuel conduit can also be configured such that its longitudinal axis intersects the burner face plane at an angle β relative to the normal to the first inner nozzle and at a complementary angle (90°-β) to the minor axis of the first inner nozzle. Such a configuration can, for example, provide an inclination angle for the first fuel conduit. The second fuel conduit configured to supply fuel to the second inner nozzle and having a longitudinal axis aligned with the direction of fuel flow in the second fuel conduit can also be configured such that its longitudinal axis intersects the burner face plane at an angle β relative to the normal to the second inner nozzle and at a complementary angle (90°-β) to the minor axis of the second inner nozzle. In such a configuration, the longitudinal axis of the first fuel conduit and the longitudinal axis of the second fuel conduit may each be angled away from the staging nozzle, and the angle β may be in the range of 0<β≦10° or 0<β≦5°.

[0055] The total fuel flow and the total oxidizer flow can be provided to the burner in an equal ratio, with an equivalence ratio of 1 indicating a fuel-to-oxidizer stoichiometry, an equivalence ratio greater than 1 indicating a fuel-rich stoichiometry, and an equivalence ratio less than 1 indicating a fuel-lean stoichiometry. The controller can be programmed to independently control the fuel flow to each of the first and second inner nozzles and to control the distribution of the total oxidizer flow, consisting of a primary oxidizer flow distributed between the first and second annular nozzles and a secondary oxidizer flow provided to the staging nozzle, such that the primary oxidizer flow is 60% to 95% of the total oxidizer flow and the secondary oxidizer flow is the remainder (e.g., 5% to 40%) of the total oxidizer flow. The primary oxidizer flow can also be distributed between the first and second annular nozzles in a ratio of 0.9 to 1.1.

[0056] The controller can also be programmed to operate the burner in a proportional mode in which the total fuel flow is supplied to the first inner nozzle and the second inner nozzle such that the equivalence ratio of the first burner element is between 1.05 and 1.5 and the equivalence ratio of the second burner element is between 1.05 and 1.5.

[0057] The controller can be programmed to operate the burner in an alternating mode. For example, the controller can be programmed to operate the burner in an alternating mode in which the distribution of total fuel flow between the first inner nozzle and the second inner nozzle alternates between a first state in which the first burner element is active while the second burner element is passive, and a second state in which the first burner element is passive while the first burner element is active. The active burner element can be characterized by an equivalence ratio of 1.4 to 3, and the passive burner element can be characterized by an equivalence ratio of 0.1 to 1. The controller can be programmed to alternate between the first and second states based on one or more of the passage of a predetermined period of time and data from at least one sensor positioned to detect at least one condition in the furnace.

[0058] The first and second annular nozzles may each have a major axis and a minor axis that coincide with the major axis and minor axis of the first and second inner nozzles, respectively. The minor axis of each of the first and second annular nozzles may be defined by a height ho. Fuel may exit each of the first and second inner nozzles at a fuel velocity, and the primary oxidizer may exit each of the first and second annular nozzles at a primary oxidizer velocity, and the ratio ho / hf may be sized to result in a fuel velocity to primary oxidizer velocity ratio of 1 to 4.

[0059] A furnace is also provided. The furnace can include a wall, a peak, a vessel of solid and / or liquid material, and a burner embodiment positioned in the wall such that a first burner element is closer to the vessel than a second burner element and a staging nozzle is closer to the peak than the second burner element. The burner embodiment utilized in the furnace can be, for example, any of the embodiments discussed herein.

[0060] A method for operating a burner in a furnace is also provided. The method can include flowing a total oxidizer flow through the burner, the total oxidizer flow comprising a primary oxidizer flow distributed between a first annular nozzle and a second annular nozzle, and a secondary oxidizer flow provided to a staging nozzle, wherein the primary oxidizer flow is 60% to 95% of the total oxidizer flow, and the primary oxidizer flow is distributed between the first annular nozzle and the second annular nozzle in a ratio of 0.9 to 1.1. The secondary oxidizer flow can be 40% to 5% of the total oxidizer flow. The method can also include flowing a total fuel flow through the burner.

[0061] The method may also include switching the burner between a proportional mode and an alternating mode of operation. In the proportional mode, the total fuel flow may be apportioned between the first and second inner nozzles such that the first burner element has an equivalence ratio of 1.05 to 1.5 and the second burner element has an equivalence ratio of 1.05 to 1.5. In the alternating mode, the total fuel flow apportioned between the first and second inner nozzles may be switched back and forth between a first state in which the first burner element is active and the second burner element is passive, and a second state in which the first burner element is passive and the second burner element is active, the active burner element being characterized by an equivalence ratio of 1.4 to 3 and the passive burner element being characterized by an equivalence ratio of 0.1 to 1. In such embodiments of the method, an equivalence ratio of 1 indicates a stoichiometric ratio of fuel to oxidizer, an equivalence ratio greater than 1 indicates a fuel-rich stoichiometry, and an equivalence ratio less than 1 indicates a fuel-lean stoichiometry.

[0062] Other details, objects, and advantages of the method of transient heating, the apparatus for transient heating, the burner for a reverberatory furnace, and the methods of making and using the same will become apparent as the following description of specific exemplary embodiments thereof proceeds. [Brief explanation of the drawings]

[0063] Exemplary embodiments of burners for transient heating and methods of making and using them are illustrated in the drawings, in which like reference numerals identify like elements. [Figure 1] 1 is a schematic perspective view of a reverberatory furnace 1 with transient heating burners 10 mounted on a side wall 6. FIG. [Figure 2] 1 is a front perspective view of a first exemplary embodiment of a transient heating burner 10. FIG. [Figure 3] 3 is a schematic horizontal cross-sectional view of a first exemplary embodiment of the burner 10 of FIG. 2. [Figure 4] 3 is another schematic cross-sectional view of the first exemplary embodiment of the burner 10 of FIG. 2. [Figure 5] 2 is a schematic diagram of an exemplary fuel conduit arrangement for refueling the first burner element 13 and the second burner element 15 of the first exemplary embodiment of the burner 10. FIG. [Figure 6] 1 is a front view of a first exemplary embodiment of a burner 10. FIG. [Figure 7] FIG. 9 is an enlarged partial view of the second upper burner element 15 enclosed in circle F7 in FIGS. 6 and 8. [Figure 8] 1 is a front view of a first exemplary embodiment of a burner 10. FIG. [Figure 9] 9 is a front view of a first exemplary embodiment of the burner 10, similar to the views of FIGS. 6 and 8, illustrating an example of an alternative orientation of the first burner element 13 and the second burner element 15. FIG. [Figure 10] 1 illustrates results from a computational fluid dynamics evaluation of one embodiment of a burner 10 in a furnace. [Figure 11] 1 illustrates results from a computational fluid dynamics evaluation of one embodiment of a burner 10 in a furnace. [Figure 12] 1 is a graph comparing normalized NOx (pounds per million British thermal units (lbs / MMBtu)) as a function of air leakage rate in a furnace for a conventional oxy-fuel burner and a transient heat burner embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0064] 2-9, the transient heating burner 10 may include multiple burner elements and may be positioned between a lower pilot flame port 11 that may output a pilot flame and a staging nozzle 17 that may output an oxidant flow from an oxidant flow outlet 17o defined in a hot side 10h of the body of the burner 10. The hot side 10h of the body of the burner 10 may be positioned to face the inside of a chamber of the apparatus for transient heating above the vessel 2. The staging nozzle 17 may also be referred to as an upper oxidant flow nozzle 17 for some embodiments.

[0065] The plurality of burner elements can include a first burner element 13 spaced apart from a second upper burner element 15. The first lower burner element 13 can be between the lower pilot flame port 11 and the second burner element 15. The second burner element 15 can be positioned between the first burner element 13 and a staging nozzle 17 (e.g., upper oxidant flow nozzle 17).

[0066] The first lower burner element 13 may include a first inner nozzle 13IN having a first inner fuel outlet 13f that can output a fuel flow into a chamber above the vessel 2 and below the second upper burner element 15. The first inner fuel outlet 13f of the first inner nozzle 13IN may be surrounded by the first outer oxidant outlet 13o of the first annular nozzle 13AN of the first burner element 13 (e.g., the periphery of the first inner fuel outlet 13f may be completely surrounded or enveloped by the first outer oxidant outlet 13o). The first outer oxidant outlet 13o may output an oxidant flow into a chamber above the vessel 2. The fuel output from the inner fuel outlet 13f of the first burner element 13 may be within a preselected fuel flow range of the first burner element, and the oxidant flow output from the first outer oxidant outlet 13o may be within a preselected oxidant flow range of the first burner element. The oxidant stream output from the first outer oxidant stream outlet 13o can have a preselected oxygen concentration that is within a preselected first burner element oxidant stream oxygen concentration range. In some embodiments, the oxygen concentration of the oxidant stream output from the first outer oxidant stream outlet 13o can be between 90 volume percent (vol%) oxygen and 100 volume% oxygen. Other embodiments can utilize oxygen concentrations between 21 volume% and 100 volume% oxygen. Still other embodiments can utilize oxygen concentrations less than 21 volume% oxygen and greater than 10 volume% oxygen, or concentrations of at least 26 volume% oxygen, at least 40 volume% oxygen, at least 70 volume% oxygen, or at least 98 volume% oxygen.

[0067] The second burner element 15 may include a second inner nozzle 15IN positioned inside the second annular nozzle 15AN (e.g., the second annular nozzle may surround the second inner nozzle). For example, the second inner nozzle 15IN may have a second inner fuel outlet 15f that may output a fuel flow into a chamber above the vessel. The second inner fuel outlet 15f of the second burner element 15 may be surrounded by the second annular nozzle 15AN of the second burner element 15, which may be configured with a second outer oxidant outlet 15o. The second annular nozzle 15AN may output an oxidant flow into a chamber above the vessel 2 (e.g., the periphery of the second inner fuel outlet 15f may be completely surrounded or surrounded by the second outer oxidant outlet 15o). The fuel output from the inner fuel outlet 15f of the second burner element 15 can be within a preselected fuel flow rate range for the second burner element, and the oxidant stream output from the second outer oxidant outlet 15o can be within a preselected flow rate range for the second burner element. The oxidant stream output from the second outer oxidant outlet 15o can have a preselected oxygen concentration within the preselected oxidant stream oxygen concentration range for the second burner element. In some embodiments, the oxygen concentration of the oxidant stream output from the second outer oxidant outlet 15o can be between 90 volume percent (vol%) oxygen and 100 volume% oxygen. Other embodiments may utilize oxygen concentrations between 21 volume% and 100 volume% oxygen. Still other embodiments may utilize oxygen concentrations less than 21 volume% oxygen and greater than 10 volume% oxygen, or concentrations of at least 26 volume% oxygen, at least 40 volume% oxygen, at least 70 volume% oxygen, or at least 98 volume% oxygen.

[0068] The staging nozzle 17 may be configured as an oxidizer flow nozzle 17 and may include an oxidizer outlet 17o that outputs an oxidizer flow at a flow rate that may be within a preselected upper oxidizer flow rate range. The oxidizer flow from each of the first oxidizer nozzle 13o, the second oxidizer nozzle 15o, and the staging nozzle 17 typically has a volumetric concentration of molecular oxygen (O2) of 21% to 100% by volume. More generally, the oxidizer may be air, depleted air (i.e., gas having less than about 20.9% oxygen), oxygen-enriched air (i.e., gas having more than about 20.9% oxygen), or essentially pure oxygen (i.e., gas having approximately 100% oxygen). In preferred embodiments, the oxidizer is oxygen-enriched air having an oxygen concentration of at least 26% by volume oxygen, at least 40% by volume oxygen, at least 70% by volume oxygen, or at least 98% by volume oxygen.

[0069] Fuel and oxidizer are supplied to burner 10 by conduits that extend rearward through the burner body from burner face 10h and outward from rear side 10c, as shown in Figures 3 and 4. Oxidizer is supplied to the burner through oxidizer conduits that feed into an oxidizer plenum, which acts as a manifold for distributing oxidizer to first annular nozzle 13o, second annular nozzle 15o, and staging nozzle 17o. Approximately equal flow rates of oxidizer are distributed to each of first annular nozzle 13o and second annular nozzle 15o, while the amount of oxidizer distributed to staging nozzle 17o is controlled by a valve (not shown).

[0070] Fuel for the first burner element 13 is supplied to a first fuel conduit 13c, which defines a longitudinal axis 13L extending through a first inner nozzle 13f. Fuel for the second burner element 15 is supplied to a second fuel conduit 15c, which defines a longitudinal axis 15L extending through a second inner nozzle 15f.

[0071] Fuel is supplied to burner elements 13 and 15 by flow control devices as shown in Figure 5. A fuel supply 28 provides fuel to a first flow train having a valve 30 and a bypass 31b that bypasses the valve 30, and a second flow train having a valve 30 and a bypass 31b that bypasses the valve 30.

[0072] As shown in Figures 6A and 6B, the first flow row supplies fuel to the first inner nozzle 13f of the first burner element 13, while the second flow row supplies fuel to the second inner nozzle 15f of the second burner element 15.

[0073] When a valve 30 in a first flow train is open and fuel flows through both the valve 30 in the first flow train and its corresponding bypass 31b, fuel flow to the first inner nozzle 13f is greater than when the valve 30 is closed and fuel flows only through the bypass 31b. Similarly, when a valve 30 in a second flow train is open and fuel flows through both the valve 30 in the second flow train and the bypass 31b, fuel flow to the second inner nozzle 15f is greater than when the valve 30 is closed and fuel flows only through the bypass 31b.

[0074] The two valves 30 are controlled by a controller CTRL, which is programmed to operate the burner 10 in a manner such that at least one valve 30 is always open, and sometimes both valves 30 are open. When the valve 30 in the first flow train is open and the valve 30 in the second flow train is closed, the first burner element 13 is in active mode, but the second burner element 15 is in passive mode. Conversely, when the valve 30 in the first flow train is closed and the valve 30 in the second flow train is open, the first burner element 13 is in passive mode, but the second burner element 15 is in active mode. When both valves 30 are open, both burner elements 13 and 15 are in active mode. The burner 10 typically does not operate with both valves 30 closed, as this is not expected to be a useful mode of operation, but if later determined to be useful, the controller CTRL can be programmed to include that mode of operation for the burner 10.

[0075] Fuel is supplied separately to a pilot conduit 24 which connects to a pilot flame port which is used for ignition purposes and when the furnace is below the autoignition temperature of the fuel.

[0076] The cooler side 10c of the burner 10 may be opposite the hot side 10h. As best seen in Figures 3-5, the cooler side 10c of the burner 10 may include an arrangement of conduits through which fuel and oxidant flows may be transported to the lower pilot flame port 11, the first and second burner elements 13 and 15, and the staging nozzle 17 (which, in the illustrated embodiment, may be considered the upper oxidant flow nozzle 17). For example, fuel may be output from a fuel control manifold 28 for fueling a first burner element fuel supply conduit 29a and a second burner element fuel supply conduit 29b for fueling the first and second inner nozzles of the first and second burner elements 13 and 15 of the burner.

[0077] The oxidant stream may be supplied to the first burner element 13, the second burner element 15, and the staging nozzle 17 (e.g., upper oxidant stream nozzle 17) via an oxygen supply conduit that provides oxygen containing oxidant fluid from an oxygen source to the first annular nozzle 13AN of the first burner element 13, the second annular nozzle 15AN of the second burner element 15, and the staging nozzle 17, so that the oxidant stream may be output from the first outer oxidant outlet 13o, the second outer oxidant outlet 15o, and the staging nozzle 17. Examples of an oxygen source may be a cryogenic air separation unit that outputs one or more oxygen streams that may be supplied to the nozzles, or a vacuum swing adsorption (VSA) unit that may output at least one oxygen stream. Other sources of oxidant for the oxidant stream may be other plant units (e.g., compressors for making up air as the oxidant stream, compressors for making up oxygen-enriched air as the oxidant stream, etc.) that may provide an oxidant stream to the burner.

[0078] Burner 10 can operate on any gas fuel, including, but not limited to, natural gas (i.e., primarily methane), hydrogen, or a mixture of natural gas and hydrogen in any desired ratio. In some embodiments, the fuel provided by fuel control manifold 28 can include natural gas, hydrogen, or a mixture of hydrogen and natural gas. For example, a source of hydrogen 26 and a source of natural gas 25 can be connected to fuel control manifold 28 via refill conduits to replenish hydrogen and / or natural gas to fuel control manifold 28. The fuel control manifold can be configured to hold and / or mix fuels (e.g., when both hydrogen and natural gas are replenished to the fuel control manifold, the hydrogen can be mixed with the natural gas to provide a fuel comprising hydrogen and natural gas as the fuel) and replenish fuel to one or more refueling conduits via an arrangement of valves and one or more containers. The fuel control manifold 28 is connected to the first burner element 13 and the second burner element 15 of the burner 10 via fuel supply conduits (e.g., a fuel supply conduit 29a of the first burner element, a fuel supply conduit 29b of the second burner element, etc.) to supply fuel so that fuel can be output through the inner fuel openings of the inner nozzles of each burner element.

[0079] The first burner element make-up conduit 29a and the second burner element refueling conduit 29b can each include a conduit arrangement and a control valve 30 so that at least a minimum amount of fuel is refueled to the inner fuel nozzle opening to which the make-up conduit is connected. For example, fuel received from the fuel control manifold 28 can pass to the burner element make-up conduit downstream refueling conduit segment 31a so that the fuel can pass along the bypass flow conduit segment 31b and / or through the control valve 30 to the downstream conduit segment 31c connected to the inner fuel nozzle opening for outputting the fuel into the chamber above the vessel 2. The downstream refueling conduit segment 31a can be positioned between the control valve 30 and the fuel control manifold 28 so that it is upstream of the control valve 30 and downstream of the fuel control manifold 28. Bypass flow conduit segment 31b may be positioned between upstream refueling conduit segment 31a and downstream refueling conduit segment 31c so that fuel from upstream refueling conduit segment 31a can travel to downstream conduit segment 31c without flowing through control valve 30. Downstream conduit segment 31c may be positioned between the inner nozzle of the burner element to which the refueling conduit is connected and control valve 30. Downstream conduit segment 31c may also be positioned between the inner nozzle to which the refueling conduit is connected and the outlet of bypass flow conduit segment 31b.

[0080] To increase the flame coverage of the furnace, the first burner element 13 may be angled in one or both directions, i.e., relative to its major axis and / or relative to its minor axis. Similarly, to increase the flame coverage of the furnace, the second burner element 15 may be angled in one or both directions, i.e., relative to its major axis and / or relative to its minor axis.

[0081] 3 and 4, the first burner element 13 and the second burner element 15 may be aligned so that the fuel stream output from each of the first and second inner nozzles of these burner elements is at a horizontal angle α with respect to a central flat angle (e.g., 0° with respect to the wall on which the burner is mounted, or the angle at which the pilot flame outputs fuel for its flame through the pilot flame port 11). The horizontal angle α may range from + / −5° to + / −20°.

[0082] The lower and upper limits of the horizontal angle α can be defined or determined to ensure that the fuel is completely combusted before exiting the furnace. If the included angle is too large, the fuel and oxidizer will not mix properly within the furnace volume. If the angle is too small, the two flames may not fully cover the furnace width, leaving cold spots within the furnace. The final angle between the nozzles may be determined by the furnace width. Additionally, the furnace width is another parameter that determines such included horizontal angle α. Because it is desirable to prevent the flames output from the nozzles from impinging on the furnace walls, the width may affect the desired horizontal angle α.

[0083] For example, the make-up conduit 15c for the second inner fuel outlet 15f of the second burner element 15 may extend linearly from the fuel make-up conduit 29b of the second burner element to the second inner fuel outlet 15f of the second burner element 15 at a horizontal angle α relative to the horizontal direction in which the pilot flame make-up conduit 11c extends linearly to the pilot flame port 11. This horizontal angle may be considered the first preselected horizontal angle or the preselected horizontal angle of the second burner element 15. It should be understood that at least a portion of the make-up conduit 15c may include or be entirely the downstream conduit segment 31c.

[0084] The horizontal angle α for the second burner element 15 can also be considered as the angle α at which the longitudinal axis 15L of the supply conduit 15c for the second burner element 15 intersects the burner face plane 10fp at a complementary angle (90°-α) to the normal to the second inner nozzle 15IN of the second burner element 15 and to the major axis (e.g., the length L of the second inner fuel outlet 15f) of the second inner nozzle 15IN of the second burner element 15. In some embodiments, the angle α can be greater than 0° and less than or equal to 20°, or less than 0° and greater than or equal to -20°.

[0085] As another example, the make-up conduit 13c for the first inner fuel outlet 13f of the first burner element 13 may extend linearly from the fuel make-up conduit 29a of the first burner element to the first inner fuel outlet 13f of the first burner element 13 at a horizontal angle α relative to the horizontal direction in which the pilot flame make-up conduit 11c extends linearly to the pilot flame port 11. This horizontal angle may be considered a second preselected horizontal angle or the preselected horizontal angle of the first burner element 13. The horizontal angle α may be in the range of + / - 5° to + / - 20°. It should be understood that at least a portion of the make-up conduit 15c may include or be entirely the downstream conduit segment 31c.

[0086] The horizontal angle α for the first burner element 13 can also be considered as the angle α at which the longitudinal axis 13L of the supply conduit 13c for the first burner element 13 intersects the burner face plane 10fp at a complement angle (90°-α) to the normal to the first inner nozzle 13IN of the first burner element 13 and to the major axis (e.g., the length L of the first inner fuel outlet 13f) of the first inner nozzle 13IN of the first burner element 13. The angle α can be greater than 0° and less than or equal to 20° in some embodiments, or less than 0° and greater than or equal to -20° in some embodiments.

[0087] The longitudinal axis 15L of the make-up conduit 15c for the second burner element 15 may be an axis extending in the direction of fuel flow, which may be the direction in which fuel passes through the make-up conduit 15c to be output from the second inner fuel outlet 15f of the second inner nozzle 15. Also, the longitudinal axis 13L of the make-up conduit 13c for the first burner element 13 may be an axis extending in the direction of fuel flow, which may be the direction in which fuel passes through the make-up conduit 13c to be output from the first inner fuel outlet 13f of the first inner nozzle 13. In such an arrangement, the longitudinal axes 13L and 15L may be aligned with the direction of fuel flow for fuel passing through the make-up conduits 13c and 15c to be output from the first inner nozzle 13 and the second inner nozzle 15.

[0088] 3 and 4, in some embodiments, the horizontal angle α along which the refill conduit 15c for the second inner fuel outlet 15f extends linearly may be in the range of −5° to −20°, and the horizontal angle α along which the refill conduit 13c for the first inner fuel outlet 13f extends linearly may be in the range of 5° to 20°. In other embodiments, the horizontal angle α along which the refill conduit 15c for the second inner fuel outlet 15f extends linearly may be in the range of 5° to 20°, and the horizontal angle α along which the refill conduit 13c for the first inner fuel outlet 13f extends linearly may be in the range of −5° to −20°.

[0089] It should be understood that the value of the horizontal angle α may be the same nominal value for the first burner element 13 and the second burner element 15 (e.g., if the angle α is 5° and −5° for the burner elements, the same nominal value for the angle α is 5°, etc.). In such an embodiment, the longitudinal axis 13L of the supply conduit 13c for the first burner element 13 may be angled relative to the longitudinal axis 15L of the supply conduit 15c for the second burner element 13 by an angle that is twice the nominal value of the angle α (e.g., 2α, or 2*α).

[0090] The refill conduit 15c for the second inner fuel outlet 15f may be positioned to extend linearly so that the conduit 15c is in a horizontal orientation (e.g., no tilt angle) when extending from the second nozzle refueling conduit 29b to the second inner fuel outlet 15f. Alternatively, the refill conduit 15c for the second inner fuel outlet 15f may be positioned to extend linearly along a vertical angle (e.g., having a tilt angle of up to ±10° with respect to the horizontal). The vertical angle along which the refill conduit 15c for the second inner fuel outlet 15f may extend may be considered an tilt angle. The inclination angle may also be referred to as angle β, which is the angle at which the longitudinal axis 15L of the supply conduit 15c can intersect a plane defined by the major and minor axes of the second inner nozzle 15IN of the second burner element (e.g., a plane defined by the length L and height h of the second inner fuel outlet 15f) with respect to the normal to the second inner nozzle 15IN and at a complementary angle (90° to β) to the minor axis of the second inner nozzle 15IN (e.g., the height h of the second inner fuel outlet 15f). The inclination angle (or angle β) can be up to +10° relative to a horizontal orientation with no vertical component of direction, or up to −10° relative to a horizontal orientation with no vertical component of direction, so that the conduit 15c extends linearly along a vertical inclination angle ranging from −10° to +10°.

[0091] The refill conduit 13c for the first inner fuel outlet 13f can also be positioned to extend linearly, so that the conduit 13c is in a horizontal orientation (e.g., no tilt angle) when extending from the first nozzle fuel refill conduit 29a to the first inner fuel outlet 13f. Alternatively, the refill conduit 13c for the first inner fuel outlet 13f can be positioned to extend linearly along a vertical angle (e.g., having a tilt angle of up to ±10° with respect to the horizontal). The vertical angle along which the refill conduit 13c for the first inner fuel outlet 13f can extend can be considered an tilt angle. The inclination angle may also be referred to as angle β, which is the angle at which the longitudinal axis 13L of the supply conduit 13c can intersect a plane defined by the major and minor axes of the first inner nozzle 13IN of the first burner element (e.g., a plane defined by the length L and height h of the first inner fuel outlet 13f) with respect to the normal to the first inner nozzle 13IN and at a complementary angle (90° to β) to the minor axis of the first inner nozzle 13IN (e.g., the height h of the first inner fuel outlet 13f). The inclination angle (or angle β) can be up to +10° relative to a horizontal orientation with no vertical component of direction, or up to −10° relative to a horizontal orientation with no vertical component of direction, so that the conduit 13c extends linearly along a vertical inclination angle ranging from −10° to +10°. It should be understood that a tilt angle greater than 0° (e.g., +1° or +10°) may be considered an up-tilt direction that may direct fuel upward, and a tilt angle less than 0° (e.g., -1° or -10°) may be considered a down-tilt direction that may direct fuel downward.

[0092] In some embodiments, the inclination angle of the refill conduit 13c for the first inner fuel outlet 13f can be opposite to the inclination angle of the refill conduit 15c for the second inner fuel outlet 15f. For example, the inclination angle of the refill conduit 13c for the first inner fuel outlet 13f can be in a range of greater than 0° to +10°, and the inclination angle of the refill conduit 15c for the second inner fuel outlet 15c can be in a range of less than 0° to −10°. As another example, the inclination angle of the refill conduit 13c for the first inner fuel outlet 13f can be in a range of less than 0° to −10°, and the inclination angle of the refill conduit 15c for the second inner fuel outlet 15c can be in a range of greater than 0° to +10°. In other embodiments, the inclination angles of both the refill conduits 13c and 15c for the first inner fuel outlet 13f and the second inner fuel outlet 15f can each have a horizontal orientation with an inclination angle of 0°, or each can have the same type of inclination angle (e.g., both can have an inclination angle in the range of 0° to +10° or 0° to −10°). In some preferred embodiments, the inclination angles of the refill conduits 13c and 15c for the first inner fuel outlet 13f and the second inner fuel outlet 15f are oriented parallel to the tank surface (e.g., have an inclination angle of 0° or about 0°, which can be an inclination angle within 0° to 1°).

[0093] The longitudinal axis 13L of the supply conduit 13c may be angled away from the staging nozzle 17. The longitudinal axis 15L of the supply conduit 15c may also be angled away from the staging nozzle 17.

[0094] The second inner fuel outlet 15f of the second burner element 15 can be recessed relative to the second outer oxidant outlet 15o of the second burner element 15. For example, the second oxidant outlet 15o of the second burner element 15 can be positioned on the hot side 10h of the burner, but the second fuel outlet 15f of the second burner element is recessed 0.25 to 0.75 inches away from the hot side 10h of the burner (e.g., recessed 0.635 cm to 1.905 cm). As another example, the second oxidant outlet 15o of the second burner element 15 can be positioned on the hot side 10h of the burner, but the second fuel outlet 15f of the second burner element 15 is recessed 0.15 to 1.0 inch away from the hot side 10h of the burner (e.g., recessed 0.381 cm to 2.54 cm). The recessed positioning of the second inner fuel outlet 15f relative to the second outer oxidant outlet 15o can help protect the fuel lines (such as natural gas fuel lines) from any damage caused by corrosive furnace hot gases, which can help extend the life of the fuel lines before they need to be replaced.

[0095] The first inner fuel outlet 13f of the first burner element 13 can be recessed relative to the first outer oxidant outlet 13o of the first burner element 13. For example, the first oxidant outlet 13o of the first burner element 13 can be positioned on the hot side 10h of the burner, but the first fuel outlet 13f of the first burner element 13 is recessed 0.25 to 0.75 inches away from the hot side 10h of the burner (e.g., recessed 0.635 cm to 1.905 cm). As another example, the first oxidant outlet 13o of the first burner element 13 can be positioned on the hot side 10h of the burner, but the first fuel outlet 13f of the first burner element 13 is recessed 0.15 to 1.0 inch away from the hot side 10h of the burner (e.g., recessed 0.381 cm to 2.54 cm).

[0096] In addition to the tilt angle, horizontal angle α, and concave arrangement, the vertical and horizontal nozzle spacing and positioning (e.g., vertical spacing along the wall height, horizontal offset positioning, etc.) can be tailored to meet a particular set of design criteria for providing a stable flame capable of providing low NOx emissions while allowing the flame to be generated from a fuel that is natural gas, a fuel that is hydrogen, or a mixture of hydrogen and natural gas. For example, the horizontal positioning of the first burner element 13 and the second burner element 15 can be tailored to allow the burner elements to be aligned with each other's centers or to be horizontally offset within a preselected horizontal offset range.

[0097] For example, the horizontal length L of the first inner fuel outlet 13f and the horizontal length L of the second inner fuel outlet 15f may each be the same or similar (e.g., the length L of the first fuel outlet 13f may be 90% to 110% of the length L of the second inner fuel outlet 15f). The length L of each outlet may be the length of the major axis of the outlet. For example, the length L may define the major axis length measured in the burner face plane for the outlet of the first inner nozzle 13IN of the first burner element 13 (e.g., the first fuel outlet 13f), and the length L may define the major axis length measured in the burner face plane for the outlet of the second inner nozzle 15IN of the second burner element 15 (e.g., the second inner fuel outlet 15f). The longitudinal axis of the first inner nozzle 13IN having the first inner fuel outlet 13f may be substantially parallel to the longitudinal axis of the second inner nozzle 15IN having the second inner fuel outlet 15f such that the longitudinal axes are parallel or within 5° of being parallel.

[0098] The second upper fuel outlet 15f and the first lower fuel outlet 13f can be positioned such that the center of the first fuel outlet 13f is horizontally spaced apart from the center of the second fuel outlet 15f by an offset distance B. The offset distance B can be the distance between the minor axis of the first inner nozzle 13IN having the first inner fuel outlet 13f and the minor axis of the second inner nozzle 15IN having the second inner fuel outlet 15f. The minor axis can be defined by the height of the outlet. The height of the outlet can extend perpendicular to the length L of the outlet. The minor axis of the first inner nozzle 13IN having the first inner fuel outlet 13f can be substantially parallel to the minor axis of the second inner nozzle 15IN having the second inner fuel outlet 15f such that the minor axes are parallel or within 5° of being parallel.

[0099] 8 and 9, for example, illustrate examples of different offset distance B arrangements (it should be understood that FIG. 6 illustrates an offset distance B arrangement similar to that shown in FIG. 8). The overlapping feature of the first burner element 13 and the second burner element 15 can help facilitate mixing of the fuel and oxidizer within the furnace volume to completely combust the fuel before exiting the furnace outlet.

[0100] 7, the horizontal length L of the first inner fuel outlet 13f may be shorter than the horizontal length Lo of the first outer oxidant outlet 13o of the first burner element 13. Also, the height hf of the first inner fuel outlet 13f measured at the burner face plane 10fp may be shorter than the height ho of the first outer oxidant outlet 13o of the first burner element 13 measured at the burner face plane 10fp. As discussed above, each of these heights hf and ho may extend along a minor axis of the outlet that is perpendicular to the major axis of the outlet, which defines the length (L or Lo) of the outlet. The first outer oxidant outlet 13o of the first burner element 13 may be annular in shape so that the first inner fuel outlet 13f is positioned within a central opening of the first outer oxidant outlet 13o.

[0101] The horizontal length L of the second inner fuel outlet 15f may be shorter than the horizontal length Lo of the second outer oxidant outlet 15o of the second burner element 15 measured at the burner face plane 10fp. In addition, the height hf of the second inner fuel outlet 15f may be shorter than the height ho of the second outer oxidant outlet 15o of the second burner element 15 measured at the burner face plane 10fp. As discussed above, each of these heights hf and ho may extend along a minor axis of the outlet that is perpendicular to the major axis of the outlet, which defines the length of the outlet. The second outer oxidant outlet 15o of the second burner element 15 may be annular in shape so that the second inner fuel outlet 15f is positioned within the central opening of the second outer oxidant outlet 15o.

[0102] The size and shape of the first burner element 13 may be the same as the size and shape of the second burner element 15. For example, the size and shape of the second inner fuel outlet 15f a may be the same as the size and shape of the first inner fuel outlet 13f, and the size and shape of the first outer oxidant outlet 13o may be the same as the size and shape of the second outer oxidant outlet 15o.

[0103] The oxidant outlet 17o of the staging nozzle 17 (which may be configured and positioned as an upper oxidant flow nozzle 17) may have a length X and a height Y measured in the burner face plane 10fp. The length X may be defined such that the staging nozzle 17 has the oxidant outlet 17o extending from a left-most position of the first fuel outlet 13f and / or the second fuel outlet 15f to a right-most position of the first fuel outlet 13f and / or the second fuel outlet 15f. The height Y of the oxidant outlet 17o may be the perpendicular distance of the largest portion of the outlet, the height of the outlet, or the diameter of the outlet (depending on the shape of the outlet, which may be elliptical, circular, or polygonal). The length X of the oxidant outlet 17o can be defined such that the oxidant outlet 17o is positioned above the first and second burner elements and extends laterally across the entire length L of the first fuel outlet 13f, and also extends laterally across the entire length L of the second fuel outlet 15f at a position vertically spaced apart from and above the first inner fuel outlet 13f and the second inner fuel outlet 15f.

[0104] The vertical spacing between the first burner element 13 and the second burner element 15, and between the oxidizer outlet 17o of the upper oxidizer flow nozzle 17 and the pilot flame port 11, can also be defined to allow the flame to be generated from a fuel that is a natural gas fuel, a hydrogen fuel, or a mixture of hydrogen and natural gas, while meeting a preselected set of criteria to help facilitate the provision of a stable flame that can provide a low NOx emission profile. As best seen in FIG. 6 , the top of the first outer oxidizer outlet 13o of the first burner element 13 can be vertically spaced a first vertical distance H1 from the bottom of the second oxidizer outlet 15o of the second burner element 15. The top of the second outer oxidizer outlet 15o of the second burner element 15 can be vertically spaced a second vertical distance H2 from the bottom of the oxidizer outlet 17o of the upper oxidizer flow nozzle 17. The top of the pilot flame port 11 may also be vertically spaced apart from the bottom of the first outer oxidant outlet 13o of the first burner element 13 by a pilot flame vertical spacing H3 (which may also be considered as a third vertical spacing H3).

[0105] The nozzle positioning of the first and second burner elements 13, 15, pilot flame port 11, and upper oxidizer flow nozzle 17 can be arranged to meet the following criteria to provide improved performance, improved stability of the generated flame, and lower NOx emissions:

[0106] (a) 2≦H1 / hf≦20, where H1 / hf is the first vertical spacing H1 divided by the height hf of the inner fuel outlet;

[0107] (b) 2≦H2 / hf≦20, where H2 / hf is the second vertical spacing H2 divided by the height hf of the inner fuel outlet;

[0108] (c) 2≦H3 / hf≦20, where H3 / hf is the third vertical spacing H3 divided by the height hf of the inner fuel outlet;

[0109] (d) 0.0≦B / L≦1.5, where B is the offset distance B and L is the horizontal length L of the inner fuel outlet.

[0110] The nozzle overlap criterion of (d) above may help to avoid having the nozzles too far apart, which may help to ensure that the fuel and oxidizer mix well enough in the furnace to provide complete combustion of the fuel (or at least very near complete combustion of the fuel).

[0111] Additionally, the above design criteria (a), (b), and (c) can help ensure safe ignition practices for burners in low-temperature furnaces without CO breakout in the flue gases (ignition can be the state in which a flame is initially generated in a low-temperature furnace upon burner startup). An exemplary ignition sequence can be that the pilot burner 11 is utilized to facilitate ignition of the first lower nozzle fuel outlet 13f, followed by the flame from the first lower burner element 13 igniting the fuel output from the second fuel outlet 15f. While an upper operational limit for the initiation of flame generation via the ignition sequence can be near or at a state where incomplete combustion of fuel exiting the furnace during burner startup can occur, a lower operational limit can be defined to help reduce NOx production and minimize the effects of flow interaction between the flame and / or the upper oxidizer flow nozzle 17 and the first and second burner elements 13 and 15.

[0112] The nozzle positioning of criteria (a)-(d) above can be further improved by first and second fuel outlets 13f, 15f having the following dimensions (aspect ratio of 5≦L / hf≦15, where L is the horizontal length of the inner fuel outlet and hf is the height of the inner fuel outlet), operated such that fuel is output at a velocity range of 50 to 300 feet per second (ft / s) (15.24 meters per second (m / s) to 91.44 m / s) and oxidizer is output from first and second outer oxidizer outlets 13o, 15o at an oxygen velocity of 25 ft / s to 150 ft / s (7.62 m / s to 45.72 m / s). The L / hf ratio range can be defined to help develop a flat flame that covers a larger vessel surface area compared to conventional round-pipe, single-oxygen-fuel burners. The higher flame surface area facing the vessel face that can be formed helps radiate a higher surface area of ​​the vessel, thereby reducing cold spots on the furnace side of the vessel. Also, the ratio ho / hf can be sized for the first burner element 13 and the second burner element 15 to provide a ratio of 1 to 4 between the fuel velocity output from the burner element and the primary oxidant velocity output from the burner element.

[0113] Additionally, the oxidizer outlet 17o of the upper oxidizer flow nozzle 17 may have dimensions 10≦X / Y≦40, and 1≦X / L≦2.5, where L is the horizontal length L of the inner fuel outlet, X is the length of the upper oxidizer flow nozzle 17, and Y is the height of the upper oxidizer flow nozzle 17. The oxidizer velocity output from the oxidizer outlet 17o of the upper oxidizer flow nozzle 17 may range from 25 ft / s to 150 ft / s (velocity 7.62 m / s to 45.72 m / s).

[0114] The operation of the nozzle and the upper oxidizer flow nozzle 17 can be adapted to help facilitate the production of a stable flame with low NOx emissions and minimal CO breakout from the furnace. The lower and upper limits of oxidizer staging in the upper oxidizer flow nozzle 17 can be defined based on optimal burner operation in the furnace. For example, the oxidizer output from the oxidizer outlet 17o of the upper oxidizer flow nozzle 17 can be 5% to 30% of the total oxidizer flow output from the burner (e.g., 5% to 30% of the total oxidizer flow output from the first burner element 13, the second burner element 15, and the upper oxidizer flow nozzle 17). The upper limit of oxidizer staging can be set to prevent overheating of the furnace top wall and heat dissipation at the top of the furnace. This oxidant flow output condition can be tailored to the requirement that the oxidant output from the first burner element 13 be at the same or nearly the same oxidant flow rate as the oxidant output from the second burner element 15 (e.g., the oxidant output from the first outer oxidant outlet 13o is at the same output flow rate as the oxidant output from the second outer oxidant outlet 15o, or is within 10% or 15% of the same flow rate of the oxidant output from the oxidant outlet of the other burner element). Such output oxidant from the first burner element 13 and the second burner element 15 can be 95% to 70% of the total oxidant flow output from the first outer oxidant outlet 13o, the second outer oxidant outlet 15o, and the oxidant outlet 17o of the upper oxidant flow nozzle 17.

[0115] The first burner element 13 and the second burner element 15 may be configured to provide different types of fuel staging. For example, the flow rate of fuel output from the first fuel outlet 13f and the second fuel outlet 15f may be the same when both burner elements are in active mode. When one burner element is in active mode and the other is in passive mode, the fuel output from each burner element may be different. For example, the passive burner element may output fuel from its fuel outlet such that the fuel output from the active burner element is 65% to 95% of the total fuel output from the burner 10, and the fuel output from the passive burner element may be 35% to 5% of the total fuel output from the burner 10.

[0116] Active mode operation of a burner element (e.g., first burner element 13, second burner element 15, or both burner elements) can be understood from Figure 5. For example, in active mode, fuel can be output from fuel control manifold 28 and passed to the burner element operating in active mode such that control valve 30 opens and fuel is replenished to the burner element at a high rate above the minimum fuel flow rate. When the burner element is in passive mode, control valve 30 can be fully closed such that only a minimum fuel flow rate is replenished to the burner element via fuel allowed through bypass conduit segment 31b, which bypasses the closed control valve 30 and allows fuel to flow to the burner element.

[0117] The control valves 30 may be controlled to allow all burner elements to be in active mode simultaneously, or may be configured to switch which of the burner elements are in active mode and which are in passive mode (e.g., alternate between active and passive mode cycles for a preselected active mode time cycle). For example, the control valve for the first refueling conduit 29a may be fully open, and the control valve 30 for the second refueling conduit 29b may be fully closed for a first preselected active mode period (e.g., 15 seconds, 5 minutes, 3 hours, etc.). After this period has elapsed, the control valves may be adjusted to allow the control valve for the first refueling conduit 29a to be fully closed and the control valve 30 for the second refueling conduit 29b to be fully open for a second preselected active mode period (e.g., 15 seconds, 5 minutes, 3 hours, etc.). This switching of which burner elements are active and which are passive may continue for multiple cycles. Such cycling can help provide low emissions, prevent overheating of metal on the hot side 10h of the burner and / or near the sidewall where the burner is attached, and maintain or improve yield due to a low-oxygen atmosphere near the vessel surface. This is especially true after the heating device 1 is started and the average temperature exceeds the autoignition temperature of the fuel. In contrast, activating both burner elements can help prevent carbon monoxide (CO) breakouts and provide complete combustion during low-temperature furnace startup (e.g., while the heating device is below the autoignition temperature of the fuel).

[0118] Operation of the burners when both the first burner element 13 and the second burner element 15 are in active mode may be configured to provide an equivalence ratio between 1.05 and 1.5 (e.g., 1.05<equivalence ratio<1.5, or an equivalence ratio greater than or equal to 1.05 and less than or equal to 1.5). It should be understood that for a given fuel flow rate, the equivalence ratio may be determined as the ratio between the theoretical stoichiometric oxidant flow and the actual oxidant flow.

[0119] In situations where one burner element is in an active mode and the other is operated in a passive mode, each burner element can be operated at a different equivalence ratio. It should be understood that the equivalence ratio is the ratio of fuel to oxidizer, with an equivalence ratio of 1.0 being a fuel and oxidizer mixture for complete combustion, an equivalence ratio greater than 1 being a fuel and oxidizer mixture that is fuel-rich (e.g., more fuel compared to the oxidizer so that incomplete combustion of the fuel can occur), and an equivalence ratio less than 1 being a fuel and oxidizer-rich mixture (e.g., more oxidizer than needed for complete combustion). Rich and lean operation strategies for burner elements can help reduce thermal NOx produced in the combustion process compared to operating burner elements near stoichiometric conditions.

[0120] For example, the passive burner elements may be operated at an equivalence ratio between 0.1 and 1.0 (e.g., 0.1<equivalence ratio<1.0, or an equivalence ratio greater than or equal to 0.1 and less than or equal to 1.0), and the active burner elements may be operated at an equivalence ratio between 1.4 and 3.0 (e.g., 1.4<equivalence ratio<3.0, or an equivalence ratio greater than or equal to 1.4 and less than or equal to 3). It should be appreciated that the additional oxidizer that may be provided by the upper staging nozzle 17 may provide additional oxidizer to help facilitate complete combustion of the fuel, even though one or all of the burner elements may be operating in a fuel-rich condition (e.g., an equivalence ratio greater than 1).

[0121] The function of the control valve 30 may be controlled by a controller CTRL communicatively connected to the control valve. The controller may be communicatively connected to one or more sensors of the apparatus to monitor conditions within the furnace and / or conduits. At least one of the sensors may be positioned within the furnace or chamber above the vessel 2 or positioned to detect one or more conditions within the chamber above the vessel or within the furnace. Such sensors may include, for example, temperature sensors, pressure sensors, and flow or mass flow sensors. The controller may be configured to automatically control the opening and closing of the control valve 30 according to a predefined control algorithm defined in code stored in the non-transitory memory of the controller such that, when the processor of the controller executes code, the controller communicates with the control valve 30 and adjusts the position of the valve based on sensor data and any operator input, which may be provided via one or more input devices (e.g., a computer communicatively connected to the controller). The controller CTRL may be configured to monitor and / or control the operation of the burner 10 during start-up of at least one burner such that the first burner element 13 and the second burner element 15 are in an active mode such that the first and second burner elements operate at an equivalence ratio of 1.05 to 1.5.

[0122] After the apparatus for transient heating 1 is operating at a preselected operating temperature above the autoignition temperature of the fuel replenished to at least one burner, the controller can communicate with the control valve 30 to switch the first burner element 13 from an active mode to a passive mode, and then, after a first preselected period of time, switch the first burner element 13 from a passive mode to an active mode while switching the second burner element 15 from an active mode to a passive mode. Such switching between the active and passive modes of the first burner element 13 and the second burner element 15 can occur multiple times over multiple cycles. In some configurations, the controller CTRL and control valve 30 can be configured such that the active mode of the burner elements is a mode where the equivalence ratio is between 1.4 and 3.0, and the passive mode is a mode where the equivalence ratio is between 0.1 and 1.0.

[0123] The controller CTRL can also be configured to operate one or more burners 10 so that the oxidizer output from the oxidizer outlet 17o of the staging nozzle 17 is 5% to 30% of the total oxidizer flow output from the burner 10, and the oxidizer output from the first burner element 13 is at a flow rate that is within 10% of the oxidizer flow rate of the oxidizer output from the second burner element 15.

[0124] The controller CTRL independently controls the fuel flow to each of the first inner nozzle 13IN and the second inner nozzle 15IN of the first burner element 13 and the second burner element 15, and may also be configured to control the distribution of the total oxidizer flow, consisting of a primary oxidizer flow distributed between the first annular nozzle 13AN and the second annular nozzle 15AN (e.g., the first outer oxidizer outlet 13o and the second outer oxidizer outlet 15o) of the first burner element 13 and the second burner element 15, and a secondary oxidizer flow provided to the staging nozzle 17. The primary oxidizer flow may be 60% to 95% of the total oxidizer flow, and the secondary oxidizer flow may be the remainder (e.g., 40% to 5% of the total oxidizer flow). The primary oxidizer flow may be distributed between the first annular nozzle 13AN and the second annular nozzle 15AN for the first burner element 13 and the second burner element 15 in a ratio of 0.9 to 1.1.

[0125] The controller can also be programmed to operate the burner 10 in a proportional mode in which the total fuel flow is supplied to the first and second inner nozzles (e.g., first inner fuel outlet 13f and second inner fuel outlet 15f) of the first burner element 13 and the second burner element 15 so that the equivalence ratio of the first burner element is between 1.05 and 1.5 and the equivalence ratio of the second burner element is between 1.05 and 1.5.

[0126] The controller CTRL can be programmed to operate the burner 10 in an alternating mode in which the distribution of total fuel flow between the first inner nozzle (e.g., first inner fuel outlet 13f) of the first burner element 13 and the second inner nozzle (e.g., second inner fuel outlet 15f) of the second burner element 15 alternates back and forth between a first state in which the first burner element is active but the second burner element is passive, and a second state in which the first burner element is passive but the first burner element is active. In such operating states, the controller CTRL can be configured such that the active burner elements can be characterized by operation at an equivalence ratio of 1.4 to 3, and the passive burner elements can be characterized by operation at an equivalence ratio of 0.1 to 1.

[0127] The controller CTRL may be configured to control the flow of fuel and oxidant to the burner such that the burner switches between alternating mode and proportional mode. Such switching may occur based on preselected operating criteria, operator input, or other criteria. Switching between these operating modes may occur back and forth based on preselected cycles, usage input, and / or other criteria.

[0128] An embodiment of the controller CTRL may have or otherwise utilize a feedback control loop defined to select between active and passive modes of operation of the burner elements of the burner 10 based on sensor data from sensors positioned within the apparatus. Code executed by a processor of the controller may define the feedback control loop or at least partially define the control loop.

[0129] An embodiment of the controller may include a workstation executing an automated process control program that is also communicatively connected to the control valves 30, sensors, and other control elements. The controller may also include other types of computing devices having a processor connected to a non-transitory computer-readable medium on which the code of the control program is stored, and at least one transceiver for communicatively connecting to the control valves and sensors (e.g., via a network connection, a wireless network connection, a wired communication connection, etc.). One or more input devices may be connectable to the controller to allow a user to provide input to the controller. One or more output devices (e.g., a display, a printer, etc.) may similarly be communicatively connected to the controller to provide output to the user.

[0130] As shown in FIG. 1 , the burner 10 can be disposed in a furnace 1. The furnace 1 can be a reverberatory furnace or other type of furnace that can use the transient heating burner 10. The apparatus for transient heating, in some embodiments, can include a vessel that can be sized to hold metal for melting the metal via transient heating. Sidewalls 6 can extend vertically above the vessel and top, or a ceiling can be positioned above the vessel and attached to the sidewalls to enclose the vessel 2. An array of burners 3 can be positioned to combust fuel and provide a flame within a chamber above the vessel. Hot gases from the formed flame can swirl or otherwise flow within the chamber above the vessel of metal to provide transient heating to the metal for melting it within the vessel 2.

[0131] The metal may be, for example, iron, aluminum, a non-ferrous metal, or another type of metal. The hot gases of the flame may flow from the chamber toward a flue 5 for output away from the vessel 2. The output hot gases may be vented directly to the atmosphere or may be replenished to another plant process for other uses (e.g., as a heating medium in a heat exchanger, etc.).

[0132] At least one sidewall 6 and / or top portion can include at least one transient heating burner 10, which can be utilized in combination with and / or in place of other burners (e.g., oxy-fuel burners, regenerative burners, etc.). In some embodiments, each burner 10 in the array of burners can be such a burner 10. In other embodiments, one or more of the burners 10 can be a transient heating burner positioned to generate a flame in combination with other existing conventional burners 3, which can be positioned to generate a flame for transient heating of the metal in the vessel 2. The arrangement of the burners can be utilized in combination with controlled operation of the burners to provide a desired heating profile for the heated flow of hot gases in the chamber above the vessel for heating the metal in the vessel 2.

[0133] Each burner 10 may include a burner face configured to be positionable on the inner surface of the furnace. For example, the burner 10 may be mounted flush with the inner surface of the furnace. For example, the burner face for a burner may be configured to be flush with the side wall 6 when the burner 10 is mounted on the side wall 6. As another example, the burner face may also be configured to be flush with the top portion when the burner 10 is mounted on the top portion. As yet another example, the burner 10 may be mounted on the side wall 6 or the top portion so as to be positionable on the inner surface of the furnace to replenish fuel and oxidizer into the chamber above the vessel 2. The burner face 10f of the burner may define a burner face plane 10fp. The burner face plane 10fp may be the plane at which fuel and oxidizer are output from the burner 10 to be replenished into the chamber above the vessel 2.

[0134] Computational fluid dynamics (CFD) analyses were performed for a furnace having the configuration of the exemplary embodiment shown in FIG. 1 using different burner configurations. Two CFD simulations used the same conditions in the same type of furnace, but with different burner configurations. The first CFD evaluation was performed on an embodiment of a burner similar to the embodiment shown in FIG. 8. The second CFD evaluation was for a burner having a design similar to the embodiment shown in FIG. 8, but without the upper oxidizer flow nozzle 17. The fuel used in this simulation was natural gas, and 100% oxygen by volume was used as the oxidizer. The results of the suspended oxygen concentration near the vessel surface for these two CFD evaluations are shown in FIG. 10 (without the upper oxidizer flow nozzle 17) and FIG. 11 (with the upper oxidizer flow nozzle 17).

[0135] 10 and 11 each show a graph 2a of oxygen concentration at the surface of vessel 2. The graphs illustrate results from a CFD evaluation that was performed. FIG. 10 illustrates a high oxygen concentration region near burner 10. FIG. 11 shows that the use of upper oxidizer flow nozzle 17 allowed for the elimination of this region, providing a more uniform, low concentration of oxygen throughout vessel 2.

[0136] An evaluated embodiment of the present invention of the burner 10 using CFD analysis determined that the use of the upper oxidizer flow nozzle 17 can help reduce the oxygen concentration near the vessel surface to approximately 5% (when the nozzle is present) compared to approximately 15% (when the nozzle is omitted) when the upper oxidizer flow nozzle 17 is not utilized in the burner. The use of the upper oxidizer flow nozzle 17 can help reduce or maintain oxidation of the metal vessel at a baseline level. It was determined that positioning the upper oxidizer flow nozzle 17 above the first burner element 13 and the second burner element 15 (and / or any other additional third nozzles that may output fuel and oxygen) helps move oxygen away from the vessel surface because the nozzles located between the upper oxidizer flow nozzle 17 and the vessel surface create a blanket surface that helps prevent oxygen output from the burner 10 from flowing toward the vessel 2 below the pilot flame port 11.

[0137] Evaluation of performed burner embodiments of the present invention also showed that utilizing an upper oxidizer flow nozzle 17 on the first burner element 13 and the second burner element 15 (and / or any other additional third burner element that may output fuel and oxygen) helped to reduce NOx emissions. Use of the upper oxidizer flow nozzle 17 was found to reduce NOx emissions by as much as 50% compared to one burner embodiment utilizing only the first burner element 13 and the second burner element 15 without the upper oxidizer flow nozzle 17.

[0138] The exemplary burner 10 was also privately tested in an industrial-scale laboratory furnace of the present invention at a firing rate of 5 MMBtu / hr. The oxidizer used in the test was 100% oxygen by volume. Table 1 below presents the experimental test points and the corresponding exhaust gases obtained from the test conducted. In Table 1 below, fuel type NG is natural gas, fuel type H is hydrogen gas, CO is carbon dioxide present in the exhaust gas, O is oxygen present in the exhaust gas, NO is nitrous oxide in the exhaust gas, and CO is carbon monoxide in the exhaust gas. [Table 1]

[0139] Table 1 above shows that burner 10 can operate in both burner operating modes: first, where one inner fuel nozzle of one fuel burner element is active while the other inner fuel nozzle of the other burner element is passive; and second, where both first fuel burner element 13 and second fuel burner element 15 are active. This capability of burner 10 has been shown to help provide operational flexibility for burner 10 based on the plant's operational needs. Data obtained from testing indicates that embodiments of burner 10 can be fuel flexible (e.g., can run on natural gas and a mixture of natural gas and hydrogen as fuel). Additionally, NOx and CO emissions are very low, which is believed to be due to the dual-stage burner design and configuration. Dual staging and proper sizing of the burner in accordance with the above design criteria (a)-(d) helps, for example, to create two flames output from the burner 10 with minimal flame interaction, avoid stoichiometric operation of the individual burner elements of the burner 10, and provide near-complete combustion of the fuel output from the burner 10.

[0140] FIG. 12 is a graph illustrating a comparison of normalized NOx emissions (lbs / MMBtu) between a conventional oxy-fuel burner and an embodiment of the new transient heat burner of the present invention as a function of furnace air leakage percentage. Results for an embodiment of the transient heat burner of the present invention (with one burner element active and another passive in cyclic operation as discussed herein) are presented for two cases using two different types of fuel: one using natural gas (NG), labeled "New Transient Burner (NG Fuel)" in FIG. 12, and one using a 70% calorific value natural gas-30% calorific value hydrogen blend, labeled "New Transient Burner (NG / H Fuel)." The plot illustrated in FIG. 12 shows that the new transient burner embodiment produces 40% lower total NOx emissions compared to the conventional oxy-fuel burner. Total NOx emissions from the new transient burner are similar to those when operating on natural gas or natural-hydrogen fuel mixtures, taking into account measurement uncertainties and furnace operating factors.

[0141] Burner embodiments of the present invention have also been found to provide improved fuel efficiency and improved yields based on CFD analysis performed on several embodiments of the burner 10 and transient heating device 1.

[0142] For example, for a 62,000 lb (28,122.7 kg) batch load, two CFD simulations were performed using natural gas fuel for the burners in the furnace. The first CFD simulation used an air-fuel combustion system using conventional burners ("Air" in Table 2). The second CFD simulation was for an embodiment of the burner 10 of the present invention utilized in the furnace of FIG. 1, which was simulated using hybrid combustion provided via an embodiment of the multi-stage transient heating burner 10 of the present invention ("Hybrid" in Table 2, where one air-fuel burner is replaced with one multi-stage transient heating burner). Table 2 shows the energy balance of the furnace. It was found that the embodiment of the burner 10 of the present invention helped improve the efficiency of operation by approximately 9%. The melting time of the metal in the bath could be reduced from 4.1 hours to 3.0 hours (which provided an approximately 26% increase in production by speeding up production by 1.1 hours), and fuel consumption was reduced from 1328 British thermal units (BTU) per pound (lb) to 975 BTU / lb, providing a 26.6% reduction in fuel use. [Table 2]

[0143] The burner's application using natural gas as fuel was also compared to the burner's application using a mixture of 30% calorific value hydrogen (H2) and 70% calorific value natural gas (NG). Table 3 below shows the results of these analyses. As can be seen from Table 3, the burner 10 was able to maintain its performance using both natural gas and a natural gas / hydrogen mixture for the evaluations conducted. [Table 3]

[0144] Embodiments of burner 10 can also utilize additional burner elements. For example, there can be a third burner element between pilot flame port 11 and first burner element 13. This third nozzle can be positioned and aligned to output fuel and oxidant into heating device 1, so that the output is centrally aligned (e.g., at a tilt angle of 0° and a horizontal angle α0°). It is contemplated that other embodiments may also utilize one or more third burner elements, each having an inner fuel outlet surrounded by an outer oxidant outlet. The burner elements can be configured similarly to, for example, first burner element 13 and second burner element 15, but can be arranged to provide different fuel and / or oxidant flow paths (e.g., outputting fuel to provide a tilt angle of 0° and a horizontal angle α0°).

[0145] As can be appreciated from the above, apparatus for transient heating (e.g., reverberatory furnaces), and burners that may be incorporated into such devices, may be configured to include process control elements (e.g., temperature and pressure sensors, flow sensors, an automated process control system having at least one workstation including a processor, non-transitory memory, and at least one transceiver for communication with sensor elements, valves, and controllers, etc.) positioned and configured to monitor and control operation.

[0146] Embodiments of the burner 10 can utilize different types of fuels. For example, as an alternative (or in addition) to using natural gas and hydrogen as possible fuel sources, embodiments can utilize atomized liquid fuel or pulverized solid fuel (e.g., pulverized coal) in a carrier gas or other fuel source.

[0147] It should be understood that "≦" refers to less than or equal to, and "≧" refers to greater than or equal to. It should also be understood that the fuel may include a combustible material. Examples of fuel include natural gas, hydrogen gas, diesel, coal, or other fuel sources that can be combusted. The fuel may be passed through an inner nozzle of the burner element. The oxidizer may refer to a fluid that includes a concentration of oxygen that can be utilized for combustion of the fuel. The oxidizer may be passed through an annular nozzle of the burner element that surrounds the inner nozzle of the burner element. In some embodiments, fuel or other materials may be included with the oxidizer that is passed through the annular nozzle.

[0148] Embodiments may be tailored to specifically address a particular set of design criteria. For example, it is contemplated that particular features described either individually or as part of an embodiment may be combined with other individually described features or parts of other embodiments. Accordingly, elements and acts of various embodiments described herein may be combined to provide additional embodiments. Thus, while certain exemplary embodiments of a method of transient heating, an apparatus for transient heating, a burner for a reverberatory furnace, and methods of making and using the same have been shown and described above, it should be clearly understood that the invention is not limited thereto and may be variously embodied and practiced within the scope of the following claims.

Claims

1. 1. A burner for transient heating of a furnace, said burner comprising: a burner face configured to be positioned on an inner surface of the furnace when the burner is installed in the furnace, the burner face defining a burner face plane; a first burner element having a first annular nozzle configured to flow a primary oxidant surrounding a first inner nozzle configured to flow a fuel; a second burner element having a second annular nozzle configured to flow a primary oxidant surrounding a second inner nozzle configured to flow a fuel, the second burner element positioned adjacent to and spaced apart from the first burner element; a staging nozzle configured to flow a secondary oxidant, the staging nozzle positioned adjacent to and spaced apart from the second burner element; the second burner element is positioned between the staging nozzle and the first burner element; The first inner nozzle and the second inner nozzle each have a major axis defined by a major axis length L measured in the burner face plane and a minor axis height h measured in the burner face plane. ｆ and a minor axis defined by 5≦L / h ｆ a fuel nozzle aspect ratio of ≦15; the staging nozzle having a major axis defined by a major axis length X measured in the burner face plane and a minor axis defined by a minor axis height Y measured in the burner face plane; The burner, wherein the longitudinal axis of the first inner nozzle, the longitudinal axis of the second inner nozzle, and the longitudinal axis of the staging nozzle are substantially parallel to one another within a deviation of 5° or less.

2. 2. The burner of claim 1, wherein the staging nozzle has an aspect ratio of 10≦X / Y≦40.

3. 2. The burner of claim 1, wherein 1≦X / L≦2.

5.

4. The second burner element is spaced from the first burner element by a distance H1, and 2≦H1 / h ｆ ≦20, The staging nozzle is spaced a distance H2 from the second burner element, and 2≦H2 / h ｆ 2. The burner of claim 1, wherein:

5. the minor axis of the first inner nozzle is offset from the minor axis of the second inner nozzle by a distance B, where 0<B / L≦1.5; 2. The burner of claim 1, wherein the minor axis of the first inner nozzle and the minor axis of the second inner nozzle are substantially parallel to each other within a deviation of 5 degrees or less.

6. a pilot flame port positioned adjacent to the first burner element and spaced a distance H3 from the first burner element; the first burner element is positioned between the second burner element and the pilot flame port; 2≦H3 / h ｆ 2. The burner of claim 1, wherein:

7. a first fuel conduit configured to supply fuel to the first inner nozzle, the first fuel conduit having a longitudinal axis aligned with a direction of fuel flow in the first fuel conduit, the longitudinal axis intersecting the burner face plane at an angle α with respect to a normal to the first inner nozzle and at a complementary angle (90°-α) with respect to the longitudinal axis of the first inner nozzle; a second fuel conduit configured to supply fuel to the second inner nozzle, the second fuel conduit having a longitudinal axis aligned with a direction of fuel flow in the second fuel conduit, the longitudinal axis intersecting the burner face plane at an angle α to a normal to the second inner nozzle and at a complementary angle (90°-α) to the longitudinal axis of the second inner nozzle; the longitudinal axis of the first fuel conduit and the longitudinal axis of the second fuel conduit are angled at an angle 2α relative to one another; 2. The burner of claim 1, wherein 0<α≦20°.

8. 8. The burner of claim 7, wherein 5°<α≦20°.

9. the longitudinal axis of the first fuel conduit intersects a plane defined by the major and minor axes of the first inner nozzle at an angle β relative to the normal to the first inner nozzle and at a complement angle (90°-β) relative to the minor axis of the first inner nozzle; the longitudinal axis of the second fuel conduit intersects a plane defined by the major and minor axes of the second inner nozzle at an angle β relative to the normal to the second inner nozzle and at a complement angle (90°-β) to the minor axis of the second inner nozzle; a longitudinal axis of the first fuel conduit and a longitudinal axis of the second fuel conduit are each angled away from the staging nozzle; 8. The burner of claim 7, wherein 0<β≦10°.

10. a first fuel conduit configured to supply fuel to the first inner nozzle, the first fuel conduit having a longitudinal axis aligned with a direction of fuel flow in the first fuel conduit, the longitudinal axis intersecting the burner face plane at an angle β with respect to a normal to the first inner nozzle and at a complementary angle (90°-β) with respect to the minor axis of the first inner nozzle; a second fuel conduit configured to supply fuel to the second inner nozzle, the second fuel conduit having a longitudinal axis aligned with a direction of fuel flow in the second fuel conduit, the longitudinal axis intersecting the burner face plane at an angle β with respect to a normal to the second inner nozzle and at a complementary angle (90°-β) with respect to the minor axis of the second inner nozzle; a longitudinal axis of the first fuel conduit and a longitudinal axis of the second fuel conduit are each angled away from the staging nozzle; 2. The burner of claim 1, wherein 0<β≦10°.

11. a total fuel flow and a total oxidizer flow are provided to the burner in an equal ratio, an equivalence ratio of 1 indicating a fuel to oxidizer stoichiometry, an equivalence ratio greater than 1 indicating a fuel-rich stoichiometry, and an equivalence ratio less than 1 indicating a fuel-lean stoichiometry; and The method further comprises: Independently controlling fuel flow to each of the first inner nozzle and the second inner nozzle; and controlling a distribution of a total oxidant flow to consist of a primary oxidant flow distributed between the first annular nozzle and the second annular nozzle and a secondary oxidant flow provided to the staging nozzle, wherein the primary oxidant flow is between 60% and 95% of the total oxidant flow.

12. 12. The burner of claim 11, wherein the primary oxidant flow is distributed between the first annular nozzle and the second annular nozzle in a ratio of 0.9 to 1.

1.

13. 12. The burner of claim 11, wherein the controller is programmed to operate the burner in a proportional mode in which the total fuel flow is supplied to the first inner nozzle and the second inner nozzle such that the equivalence ratio of the first burner element is between 1.05 and 1.5 and the equivalence ratio of the second burner element is between 1.05 and 1.

5.

14. the controller is programmed to operate the burner in an alternating mode in which the distribution of the total fuel flow between the first inner nozzle and the second inner nozzle alternates back and forth between a first state in which the first burner element is active and the second burner element is passive, and a second state in which the first burner element is passive and the first burner element is active; 12. Burner according to claim 11, wherein the active burner elements are characterized by an equivalence ratio of 1.4 to 3 and the passive burner elements are characterized by an equivalence ratio of 0.1 to 1.

15. 15. The burner of claim 14, wherein the controller is programmed to switch between the first state and the second state based on one or more of the passage of a predetermined period of time and data from a sensor positioned to detect at least one condition in the furnace.

16. The first annular nozzle and the second annular nozzle each have a major axis and a minor axis that coincide with the major axis and the minor axis of the first inner nozzle and the second inner nozzle, respectively, and the minor axis of each of the first annular nozzle and the second annular nozzle has a height h ｏ It is defined by fuel exits each of the first inner nozzle and the second inner nozzle at a fuel velocity; a primary oxidant exits each of the first annular nozzle and the second annular nozzle at a primary oxidant velocity; ratio h ｏ / h ｆ 10. The burner of claim 1, wherein the ratio of the fuel velocity to the primary oxidizer velocity is between 1 and 4.

17. a pilot flame port positioned below the first burner element, the top of the pilot flame port being located at a distance of 2≦H3 / h from the bottom of the first annular nozzle; ｆ are vertically spaced apart by a third vertical distance H3 such that ≦20; The bottom of the second burner element is spaced a first vertical distance H1 from the top of the first annular nozzle, and 2≦H1 / h ｆ ≦20, The bottom of the staging nozzle is spaced a second vertical distance H2 from the top of the second annular nozzle, and 2≦H2 / h ｆ ≦20, the minor axis of the first inner nozzle is offset from the minor axis of the second inner nozzle by a distance B, where 0<B / L≦1.5; 2. The burner of claim 1, wherein the minor axis of the first inner nozzle and the minor axis of the second inner nozzle are substantially parallel to each other within a deviation of 5 degrees or less.

18. A furnace, The wall and The highest part and a reservoir of solid and / or liquid material; 2. A furnace comprising: a burner according to claim 1, wherein the first burner element is positioned on the wall so that it is closer to the vessel than the second burner element and the staging nozzle is closer to the highest point than the second burner element.

19. 10. A method of operating a burner in a furnace according to claim 1, said method comprising: flowing a total oxidant flow through the burner, the total oxidant flow comprising a primary oxidant flow distributed between the first annular nozzle and the second annular nozzle and a secondary oxidant flow provided to the staging nozzle, wherein the primary oxidant flow is 60% to 95% of the total oxidant flow, and the primary oxidant flow is distributed between the first annular nozzle and the second annular nozzle at a ratio of 0.9 to 1.1; flowing a total fuel flow through said burner; and switching the operation of the burner between a proportional mode and an alternating mode; in the proportional mode, the total fuel flow is apportioned between the first inner nozzle and the second inner nozzle such that the equivalence ratio of the first burner element is between 1.05 and 1.5 and the equivalence ratio of the second burner element is between 1.05 and 1.5; In the alternating mode, the total fuel flow distributed between the first inner nozzle and the second inner nozzle alternates back and forth between a first state in which the first burner element is active while the second burner element is passive, and a second state in which the first burner element is passive while the first burner element is active, wherein active burner elements are characterized by an equivalence ratio of 1.4 to 3 and passive burner elements are characterized by an equivalence ratio of 0.1 to 1; A method wherein an equivalence ratio of 1 indicates a fuel to oxidizer stoichiometry, an equivalence ratio greater than 1 indicates a fuel-rich stoichiometry, and an equivalence ratio less than 1 indicates a fuel-lean stoichiometry.

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