Burner and method for transitional heating

Abstract

A first burner element having a first annular oxidizer nozzle surrounding a first inner fuel nozzle, and a second burner element having a second annular oxidizer nozzle surrounding a second inner fuel nozzle, the second burner element being positioned adjacent to and spaced from the first burner element, a staging nozzle configured to flow secondary oxidizer, positioned adjacent to and spaced from the second burner element, and separated from the first burner element by the second burner element, the first inner nozzle and the second inner nozzle each having a major axis defined by a length L and a minor axis defined by a height h f and having a minor axis defined by a height h, where 5 ≦ L / h f ≦ 15, the staging nozzle having a major axis, and the major axes of the first and second inner nozzles and the staging nozzle being substantially parallel to each other.

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 on June 30, 2022.

[0002] This innovation relates to burners and methods for transient heating, devices (such as reverberatory furnaces, burners for reverberatory furnaces, etc.) using those burners and methods for transient heating, operating modes of the devices, and their manufacturing and usage methods.

Background Art

[0003] Oxygen - fuel burners for providing primary or auxiliary heat to a furnace are known for a wide range of industrial applications. The applicant owns several such patents, including U.S. Patent Nos. 7,390,189, 8,806,897, and 10,584,051 (various designs and uses of flat - flame staging burners), and U.S. Patent 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 uses of burners with multiple burner elements that can be made active or passive to induce higher or lower levels of heat in specific parts of a furnace).

Summary of the Invention

[0004] This application describes embodiments of a burner that selectively induces a larger flame to one or more parts of a furnace and a smaller flame to another one or more parts of the furnace to enable better control of the temperature distribution within the furnace.

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

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

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

[0008] Aspect 4. 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. The burner according to any one of Aspects 1 to 3.

[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, where 0 < B / L ≤ 1.5, and 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° or less. The burner according to any one of Aspects 1 to 4.

[0010] Aspect 6. Further comprising a pilot flame port positioned adjacent to and spaced apart from the first burner element by a distance H3, where the first burner element is positioned between the second burner element and the pilot flame port, and 2 ≤ H3 / hf ≤ 20. The burner according to any one of Aspects 1 to 5.

[0011] Aspect 7. A first fuel conduit configured to supply fuel to the first inner nozzle, having a longitudinal axis aligned with the direction of the fuel flow in the first fuel conduit, the longitudinal axis intersecting the burner surface plane at an angle α with respect to the perpendicular of the first inner nozzle and at a complementary angle (90° - α) with respect to the major axis of the first inner nozzle; and a second fuel conduit configured to supply fuel to the second inner nozzle, having a longitudinal axis aligned with the direction of the fuel flow in the second fuel conduit, the longitudinal axis intersecting the burner surface plane at an angle α with respect to the perpendicular of the second inner nozzle and at a complementary angle (90° - α) with respect to the major axis of the second inner nozzle. The longitudinal axes of the first fuel conduit and the second fuel conduit are angled with respect to each other at an angle of 2α, where 0 < α ≤ 20°. The burner according to any one of Aspects 1 to 6.

[0012] Aspect 8. The burner according to Aspect 7, where 5° < α ≤ 20°.

[0013] Aspect 9. 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 with respect to the perpendicular to the first inner nozzle and at a complementary angle (90°−β) with respect to the minor axis of the first inner nozzle. 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 with respect to the perpendicular to the second inner nozzle and at a complementary angle (90°−β) with respect to the minor axis of the second inner nozzle. The longitudinal axes of the first fuel conduit and the second fuel conduit are each angled away from the staging nozzle, and 0 < β ≤ 10°. The burner according to aspect 7 or 8.

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

[0015] Aspect 11. The total fuel flow and the total oxidizer flow are provided to the burner at an equivalence ratio, where the equivalence ratio 1 represents the stoichiometric ratio of fuel to oxidizer, greater than the equivalence ratio 1 represents a fuel-rich stoichiometry, and less than the equivalence ratio 1 represents a fuel-lean stoichiometry. The burner further comprises a controller, and the controller is programmed to independently control the fuel flow to each of the first inner nozzle and the second inner nozzle, and to control the distribution of the total oxidizer flow such that it consists 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. The burner according to any one of Aspects 1 to 10, wherein the primary oxidizer flow is 60% to 95% of the total oxidizer flow.

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

[0017] Aspect 13. The burner according to Aspect 11 or 12, 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 1.05 to 1.5 and the equivalence ratio of the second burner element is 1.05 to 1.5.

[0018] Aspect 14. The controller is programmed to operate the burner in an alternating mode that switches back and forth between a first state where the first burner element is active but the second burner element is passive and a second state where the first burner element is passive but the first burner element is active. 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. The burner according to any one of Aspects 11 to 13.

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

[0020] Aspect 16. The first annular nozzle and the second annular nozzle each have a major axis and a minor axis that respectively coincide with the major axis and the minor axis of the first inner nozzle and the second inner nozzle. The minor axis of each of the first annular nozzle and the second annular nozzle is defined by a height ho. Fuel exits from each of the first inner nozzle and the second inner nozzle at a fuel velocity, and primary oxidant exits from each of the first annular nozzle and the second annular nozzle at a primary oxidant velocity. The ratio ho / hf is sized to provide a ratio of fuel velocity to primary oxidant velocity of 1 to 4. The burner according to any one of aspects 1 to 15.

[0021] Aspect 17. Further comprising a pilot flame port positioned below the first burner element, the top of the pilot flame port being vertically spaced from the bottom of the first annular nozzle by a third vertical spacing H3 such that 2 ≦ H3 / hf ≦ 20. The bottom of the second burner element is spaced from the top of the first annular nozzle by a first vertical distance H1, where 2 ≦ H1 / hf ≦ 20. The bottom of the staging nozzle is spaced from the top of the second annular nozzle by a second vertical distance H2, where 2 ≦ H2 / hf ≦ 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. 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° or less. The burner according to any one of aspects 1 to 16.

[0022] Aspect 18. A furnace comprising a wall, a top portion, a tank for solid and / or liquid materials, and a burner as described in any one of Aspects 1 to 17, wherein a first burner element is positioned closer to the tank than a second burner element, and a staging nozzle is positioned closer to the top portion than the second burner element, on the wall.

[0023] Aspect 19. A method of operating a burner as described in any one of Aspects 1 to 17 within a furnace, the method comprising flowing a total oxidant stream, consisting of a primary oxidant stream distributed between a first annular nozzle and a second annular nozzle and a secondary oxidant stream provided to a staging nozzle, to the burner, wherein the primary oxidant stream is 60% to 95% of the total oxidant stream, and the primary oxidant stream 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 stream to the burner; and switching the operation of the burner between a proportional mode and an alternate mode. In the proportional mode, the total fuel stream is distributed between a first inner nozzle and a second inner nozzle such that the equivalence ratio of the first burner element is 1.05 to 1.5 and the equivalence ratio of the second burner element is 1.05 to 1.5. In the alternate mode, the total fuel stream distributed between the first inner nozzle and the second inner nozzle switches back and forth between a first state where the first burner element is active and the second burner element is passive, and a second state where the first burner element is passive and the second burner element is active. 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. An equivalence ratio of 1 represents the stoichiometric ratio of fuel to oxidant, an equivalence ratio greater than 1 represents a fuel-rich stoichiometry, and an equivalence ratio less than 1 represents a fuel-lean stoichiometry.

[0024] Conventional oxy-fuel burner technology is often for oxy-fuel burners that are either a single flame induced in the melt or burn in the space above the bath surface. Most of the currently available multi-frame burners can be installed at the top of a reverb furnace. However, in many furnaces, it is difficult to install the burner at the top and it is not considered to operate as a fuel-flexible burner. In addition, next-generation fuels that are decarbonized and have low greenhouse gas emissions may require burners that can be used with traditional fuels such as natural gas, while also being flexible with respect to suitable fuel types so that they can operate with a mixture of natural gas and hydrogen or pure hydrogen.

[0025] Also, it has been found that in many cases, melting furnaces need heat to be evenly distributed within the furnace in order to improve the overall melting characteristics of the furnace. Flameless combustion is one such way that helps to provide an improved uniformity of heat distribution. However, flameless combustion produces no soot, which can potentially reduce the overall heat transfer to the bath surface due to the absence of radiative heat transfer from the soot to the bath. In a melting furnace, it has been determined that it is desirable to increase the radiative heat flux from the soot particles to the melt while also providing an improvement in the uniformity of the heat distribution within the furnace. It may be important that the amount of soot generated is completely oxidized within the furnace volume and there is no soot exiting through the flue of the furnace. Embodiments of the burner device of the present invention can help to address these issues.

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

[0027] Embodiments of the burner can be constructed and configured as both fuel staging and oxidizer staging. The dual staging can help achieve low NOx production in the furnace compared to conventional single fuel oxy-fuel burners. The oxidizer staging of the burner can help reduce oxygen near the bath surface, which can help avoid oxidation of the bath surface. Avoiding or reducing bath surface oxidation compared to air-fuel burners or conventional oxy-fuel burners can maintain or improve the furnace yield during furnace operation.

[0028] Additionally, new embodiments of the burner can be fuel flexible and operate with traditional fuels (e.g., natural gas), low-carbon intensity fuels (e.g., hydrogen), and / or mixtures of traditional and emerging alternative fuels.

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

[0030] As described above, it has been found desirable to provide a furnace burner that, whether or not it avoids the generation of NOx during fuel combustion, helps to reduce it. Some embodiments of the burner can be configured to allow the burner to be retrofitted within an existing furnace (e.g., an existing reverberatory furnace, which may also be referred to as a reverberator). Embodiments of the burner can be configured to replace a conventional burner within an existing furnace or can be used in combination with an existing conventional burner to improve performance while also reducing NOx emissions. Other embodiments can be used to completely replace all existing burners of a furnace or can be included within new furnace equipment configured to provide transient heating.

[0031] In some configurations, embodiments can be provided such that the burner can be positioned on the sidewall of the reverberatory furnace above the bath of the furnace and below the ceiling (or top) of the furnace. The burner can be adapted to allow the fuel supplied to the burner 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 a hydrocarbon fuel (e.g., natural gas, petroleum, etc.), and only hydrocarbon-based fuels (e.g., natural gas, petroleum, etc.). In some embodiments, the burner can be positioned to provide transient heating for a metallic material positioned in a bath below the burner. In some configurations, the metallic material within the bath can be a metal for an aluminum melting, iron melting, or other type of metal melting operation.

[0032] In some embodiments, the burner can utilize first and second burner elements positioned below an oxidizer nozzle positioned to output a flow of oxidizer. The first and second burner elements can each include an inner opening for discharging fuel and an annular outer opening for discharging an oxidizer flow having oxygen therein, positioned to surround the inner opening through which the fuel can be discharged. The first and second fuel burner elements can be connected to a fuel flow control manifold assembly configured to provide fuel to the first and second burner elements. The fuel can 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 can be connected to a source of oxidizer for outputting oxygen. The oxidizer source can be an output from a cryogenic air separation unit that provides a flow of oxygen to the burner elements, or can be another source of an oxidizer flow that can contain 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 can be arranged to be in a preselected alignment with each other to facilitate the formation of a stable flame having a low NOx emission profile.

[0033] The burner element can also be arranged and positioned to operate in combination with an 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, which helps facilitate the formation of a stable flame having a low NOx emission profile. The preselected arrangement can include, for example, (1) an offset positioning of a first lower burner element and a second upper burner element in a lateral dimension along a wall that is within a range of a first preselected orientation threshold, while (2) a vertical spacing between the first burner element and the second burner element that is within a range of a first preselected vertical spacing threshold, (3) a vertical spacing between the second upper burner element and the top oxidizer nozzle that is within a range of a first preselected oxidizer nozzle spacing threshold, and (4) a vertical spacing between the first lower burner element and a pilot flame outlet located below the first burner element that is within a range of a first preselected pilot flame spacing threshold. The lengths and widths of the different nozzles of the burner element can also be within preselected ranges of lengths and widths, which can also work in combination with these preselected thresholds to help facilitate the formation of a stable flame having a low NOx emission profile. The first and second burner elements can also be configured to include a preselected tilt angle in the range of -10° to 10° and a preselected horizontal orientation for providing an upwardly inclined, horizontal, or downwardly inclined flow of fuel and oxidizer such that the burner element can cause the fuel flow and / or the oxidizer flow to exit at a horizontal angle in the range of 20° to 20° (e.g., at an angle of 0°) with respect to a straight line from the wall.

[0034] Embodiments of one or more burners included in a reverberatory furnace can help limit oxygen near the bath surface. Such features can help reduce or maintain the oxidation of the metal bath at a reference level. Embodiments can also provide a low backpressure of the oxygen flow to avoid the need to use a high-pressure oxygen source for the oxidant stream. For example, some embodiments have been found to be able to reduce NOx emissions by up to 50%. While these improved results can be obtained, the efficiency of the furnace operation can be improved. In some embodiments, for example, the efficiency of the furnace operation in (replacing one air-fuel burner in the reverberatory furnace with one transient heating burner) hybrid mode can be improved by about 9%, production can be increased by about 26%, and it is considered that a fuel savings of about 26% can be achieved. While these improvements can be achieved, the furnace can be operated with a decarbonized fuel source (e.g., hydrogen as fuel) and can be adapted to reduce carbon emissions in addition to reducing NOx emissions.

[0035] An apparatus for transient heating is provided. The apparatus can include at least one burner positionable on a wall or topmost part of the apparatus for transient heating above a bath of the apparatus for transient heating. Each of the at least one burner can include a first burner element having a first outer oxidant outlet surrounding a first inner fuel outlet, and a second burner element having a second outer oxidant 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] Embodiments of the apparatus for transient heating can be a reverberatory furnace or other type of furnace or transient heating device. The at least one burner can be positioned on a sidewall of the furnace above the bath. The bath can be positioned to hold metal for melting of the metal. The metal can be aluminum, steel, or other types of metal.

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

[0038] In some embodiments, each burner can also include a pilot flame port positioned below the first burner element. The top of the pilot flame port can be vertically spaced from the bottom of the first outer oxidizer outlet by a third vertical spacing H3 (such that 2 ≤ H3 / hf ≤ 20).

[0039] The upper oxidizer flow nozzle can have an oxidizer outlet having a length X measured in the burner surface plane 10fp and a height Y measured in the burner surface plane 10fp such that 10 ≤ X / Y ≤ 40 and 1 ≤ X / L ≤ 2.5. Other embodiments can utilize different length and height specifications for the oxidizer outlet of the upper oxidizer flow nozzle.

[0040] As described 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 arranged such that the center of the first inner fuel outlet is horizontally spaced 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 transitional heating can also include other elements. For example, an embodiment can include a supply conduit for the second inner fuel outlet of the second burner element that extends linearly from the fuel supply conduit of the second burner element to the second inner fuel outlet of the second burner element at a first preselected horizontal angle with respect to the horizontal direction in which the pilot flame supply conduit extends linearly to the pilot flame port. Additionally, there can be a supply conduit for the first inner fuel outlet that extends linearly from the fuel supply conduit of the first burner element to the first inner fuel outlet at a second preselected horizontal angle with respect to the horizontal direction in which the pilot flame supply conduit extends linearly to the pilot flame port. The first preselected horizontal angle can be in the range of +5° to +20° or greater than 0° and less than or equal to 20°, and the second preselected horizontal angle can be in the range of -5° to -20° or less than 0° and less than or equal to -20°. Alternatively, the first preselected horizontal angle can 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 can be in the range of +5° to +20° or greater than 0° and less than or equal to 20°. Other angular ranges for the first preselected horizontal angle and the second preselected horizontal angle can alternatively be utilized.

[0042] The burner element can also be oriented and positioned to provide an upward-sloping output or a downward-sloping output. For example, the first and second burner elements can be configured to include a preselected tilt angle in the range of -10° to 10° to provide an upward-sloping, horizontal, or downward-sloping flow of fuel and oxidant. For example, the tilt angle of the supply 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 the first inner fuel outlet) can be different from the tilt angle of the second burner element (and the second inner fuel outlet), or the tilt angles can be the same for the first and second burner elements (and the first and second inner fuel outlets). The tilt angle of the first outer oxidant outlet can be the same as the tilt angle of the first burner element and / or the first inner fuel outlet, and the tilt angle of the second outer oxidant outlet can be the same as the tilt angle of the second burner element and / or the second inner fuel outlet (for example, their tilt angles can be in the range of -10° to +10°, etc.).

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

[0044] A method of operating an apparatus for transient heating is also provided. Embodiments of the method may include positioning at least one burner on a wall of the apparatus for transient heating above a tank of the apparatus for transient heating. 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 outlet surrounding a first inner fuel outlet, and a second burner element having a second outer oxidant 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.

[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 that is above the autoignition temperature of the fuel supplied to the at least one burner, the first burner element can be switched from an active mode to a passive mode. Thereafter, the first burner element can be switched from the passive mode to the active mode, but the second burner element can be switched from the active mode to the passive mode after a first preselected period. The active mode may be a mode where the equivalence ratio is 1.4 to 3.0, and the passive mode may be a mode where 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 5 volume % to 40 volume % of the total oxidant flow rate from the burner, and (2) the oxidant output from the first burner element is within 10% of the oxidant flow rate of the oxidant output from the second burner element.

[0047] Embodiments of a burner for a transitional heating device are also provided. Embodiments of the burner can include the above-described embodiments of the burner. For example, the burner can include a first burner element having a first outer oxidant outlet surrounding a first inner fuel outlet, and a second burner element having a second outer oxidant 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. Embodiments of the burner can also include other elements and features discussed above.

[0048] For example, a burner for transient heating of a furnace can include a burner surface configured to be positionable against the inner surface of the furnace when the burner is attached to the furnace. The burner surface can define a burner surface 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 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 fuel. The second burner element can be positioned adjacent to and spaced from the first burner element. A staging nozzle can be configured to flow a secondary oxidant. The staging nozzle can be positioned adjacent to and spaced 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 can each have a major axis defined by a major axis length L measured in the burner surface plane, a minor axis defined by a minor axis height hf measured in the burner surface plane, and a fuel nozzle aspect ratio of 5 ≦ L / hf ≦ 15. The staging nozzle can have a major axis defined by a major axis length X measured in the burner surface plane and a minor axis defined by a minor axis height Y measured in the burner surface plane. The major axis of the first inner nozzle, the major axis of the second inner nozzle, and the major axis of the staging nozzle can be substantially parallel to each other 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 such that the staging nozzle has an aspect ratio of 10 ≦ X / Y ≦ 40. The burner elements and the staging nozzle can also be sized and configured such that 1 ≦ X / L ≦ 2.5.

[0050] The burner element and the staging nozzle can also be spaced apart from each other so as to meet preselected design criteria. For example, the second burner element can be spaced apart from the first burner element by a distance H1 such that 2 ≦ H1 / hf ≦ 20, and the staging nozzle can be spaced apart from the second burner element by a distance such that 2 ≦ H2 / hf ≦ 20. The burner can also include a pilot flame port that is positioned adjacent to the first burner element and is spaced apart from the first burner element by a distance H3 such that 2 ≦ H3 / hf ≦ 20.

[0051] The burner element can also have other spatial design criteria. For example, the minor axis of the first inner nozzle can also be offset from the minor axis of the second inner nozzle by a distance B such that 0 < B / L ≦ 1.5. The minor axis of the first inner nozzle and the minor axis of the second inner nozzle can be substantially parallel to each other within a deviation of 5° or less.

[0052] As yet another example of the spatial and sizing design criteria that can be utilized for the burner, the burner can also include a pilot flame port as described above. The pilot flame port can be positioned below the first burner element. The top of the pilot flame port can be vertically spaced apart from the bottom of the first annular nozzle by a third vertical spacing H3 such that (2 ≦ H3 / hf ≦ 20). The bottom of the second burner element can be spaced apart from the top of the first annular nozzle by a first vertical distance H1 such that 2 ≦ H1 / hf ≦ 20. The bottom of the staging nozzle can be spaced apart from the top of the second annular nozzle by a second vertical distance H2 such that 2 ≦ H2 / hf ≦ 20. The minor axis of the first inner nozzle can also be offset from the minor axis of the second inner nozzle by a distance B such that 0 < B / L ≦ 1.5. The minor axis of the first inner nozzle and the minor axis of the second inner nozzle can be substantially parallel to each other within a deviation of 5° or less.

[0053] The burner can 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, it can have a first fuel conduit configured to supply fuel to the first inner nozzle. The first fuel conduit can have a longitudinal axis that is aligned with the direction of fuel flow within the first fuel conduit. The longitudinal axis can intersect the burner surface plane at an angle α with respect to the perpendicular to the first inner nozzle and at a complementary angle (90°−α) with respect to the major axis of the first inner nozzle. The second fuel conduit can be configured to supply fuel to the second inner nozzle. The second fuel conduit can have a longitudinal axis that is aligned with the direction of fuel flow within the second fuel conduit. The longitudinal axis of the second fuel conduit can intersect the burner surface plane at an angle α with respect to the perpendicular to the second inner nozzle and at a complementary angle (90°−α) with respect to the major axis of the second inner nozzle. The longitudinal axis of the first fuel conduit and the longitudinal axis of the second fuel conduit can be angled with respect to each other at an angle of 2α or at some other preselected angular value. In some configurations, the angle α can be in the range of 0 < α ≤ 20° or 5 < α ≤ 20°.

[0054] The first fuel conduit, which is configured to supply fuel to the first inner nozzle and has a longitudinal axis aligned with the direction of fuel flow within the first fuel conduit, can also be configured such that the longitudinal axis intersects the burner surface plane at an angle β with respect to the perpendicular to the first inner nozzle and at a complementary angle (90°−β) with respect to the minor axis of the first inner nozzle. Such a configuration can provide, for example, an inclination angle to the first fuel conduit. The second fuel conduit, which is configured to supply fuel to the second inner nozzle and has a longitudinal axis aligned with the direction of fuel flow within the second fuel conduit, can also be configured such that the longitudinal axis intersects the burner surface plane at an angle β with respect to the perpendicular to the second inner nozzle and at a complementary angle (90°−β) with respect to the minor axis of the second inner nozzle. In such a configuration, the longitudinal axes of the first fuel conduit and the second fuel conduit can each be angled away from the staging nozzle, and the angle β can be in the range of 0 < β ≤ 10° or 0 < β ≤ 5°.

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

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

[0057] The controller can be programmed to operate the burner in an alternating mode. For example, the controller can program the burner to operate in an alternating mode that switches back and forth between a first state where the distribution of the total fuel flow between the first inner nozzle and the second inner nozzle is such that the first burner element is active and the second burner element is passive, and a second state where the first burner element is passive and the second burner element is active. The active burner element can be characterized by an equivalence ratio of 1.4 - 3, and the passive burner element can be characterized by an equivalence ratio of 0.1 - 1. The controller can be programmed to switch between the first state and the second state based on one or more of the passage of a predetermined period and data from at least one sensor positioned to detect at least one state in the furnace.

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

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

[0060] A method of operating a burner within a furnace is also provided. The method includes flowing a total oxidant stream, consisting of a primary oxidant stream distributed between a first annular nozzle and a second annular nozzle and a secondary oxidant stream provided to a staging nozzle, to the burner, wherein the primary oxidant stream is 60% to 95% of the total oxidant stream, and the primary oxidant stream is distributed between the first annular nozzle and the second annular nozzle at a ratio of 0.9 to 1.1. The secondary oxidant stream can be 40% to 5% of the total oxidant stream. The method can also include flowing a total fuel stream to the burner.

[0061] The method can also include switching the operation of the burner between a proportional mode and an alternating mode. In the proportional mode, the total fuel flow can be distributed 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 can switch back and forth between a first state where the first burner element is active and the second burner element is passive, and a second state where the first burner element is passive and the second burner element is active, with 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 an embodiment of the method, an equivalence ratio of 1 indicates the stoichiometric ratio of fuel to oxidant, 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 their manufacturing and usage methods will become apparent as the following description of their specific exemplary embodiments proceeds.

Brief Description of the Drawings

[0063] Exemplary embodiments of burners for transient heating, and their manufacturing and usage methods are shown in the drawings. Identical reference numerals in the drawings identify identical components.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

DETAILED DESCRIPTION OF THE INVENTION

[0064] As best seen in FIGS. 2 - 9, the transient heating burner 10 can include a plurality of burner elements and can be positioned between a lower pilot flame port 11 that can output a pilot flame and a staging nozzle 17 that can output a flow of oxidant from an oxidant outlet 17o defined on a high-temperature side 10h of the body of burner 10. The high-temperature side 10h of the body of burner 10 can be positioned to face the inside of a chamber of a device for transient heating above tank 2. The staging nozzle 17 can 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 that is spaced apart from the 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., an upper oxidizer flow nozzle 17).

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

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

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

[0069] As shown in FIGS. 3 and 4, the fuel and the oxidant are supplied to the burner 10 by conduits that extend rearwardly from the burner surface 10h through the burner body and outwardly from the rear side 10c. The oxidant is supplied to the burner through an oxidant conduit that replenishes the oxidant plenum, and the oxidant plenum functions as a manifold for distributing the oxidant to the first annular nozzle 13o, the second annular nozzle 15o, and the staging nozzle 17o. An approximately equal flow rate of oxidant is distributed to each of the first annular nozzle 13o and the second annular nozzle 15o, but the amount of oxidant distributed to the staging nozzle 17o is controlled by a valve (not shown).

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

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

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

[0073] When the valve 30 of the first flow train is open and fuel flows through both the valve 30 of the first flow train and its corresponding bypass 31b, the 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 the valve 30 of the second flow train is open and fuel flows through both the valve 30 of the second flow train and the bypass 31b, the 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 programmed to operate the burner 10 in such a way that at least one valve 30 is always open and sometimes both valves 30 are open. When the valve 30 of the first flow column is open and the valve 30 of the second flow column is closed, the first burner element 13 is in the active mode, but the second burner element 15 is in the passive mode. Conversely, when the valve 30 of the first flow column is closed and the valve 30 of the second flow column is open, the first burner element 13 is in the passive mode, but the second burner element 15 is in the active mode. When both valves 30 are open, both burner elements 13 and 15 are in the active mode. The burner 10 typically does not operate when both valves 30 are closed because it is not expected to be in a useful operating mode, but if it is later determined to be useful, the controller CTRL can be programmed to include that operating mode of the burner 10.

[0075] Fuel is separately supplied to a pilot conduit 24 connected to a pilot flame port for ignition purposes and when the self-ignition temperature of the fuel is below that of the furnace.

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

[0077] The oxidant stream supplies oxygen, which includes an 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 (e.g., the upper oxidant stream nozzle 17) via an oxygen supply conduit. Thus, the oxidant stream can be replenished to the first burner element 13, the second burner element 15, and the staging nozzle 17, and can be output from the first outer oxidant outlet 13o, the second outer oxidant outlet 15o, and the staging nozzle 17. Examples of the oxygen source can be a cryogenic air separation unit that outputs one or more oxygen streams that can be replenished to the nozzles, or a vacuum swing adsorption (VSA) unit that can output at least one oxygen stream. Other sources of oxidant for the oxidant stream can be other plant units that can supply an oxidant stream to the burner (e.g., a compressor for supplying air as the oxidant stream, a compressor for supplying oxygen-enriched air as the oxidant stream, etc.).

[0078] The burner 10 can operate with any gaseous fuel including, but not limited to, natural gas (i.e., mainly methane), hydrogen, or a mixture of natural gas and hydrogen in any desired ratio. In some embodiments, the fuel provided by the fuel control manifold 28 can include natural gas, hydrogen, or a mixture of hydrogen and natural gas. For example, a hydrogen supply source 26 and a natural gas supply source 25 can be connected to the fuel control manifold 28 via supply conduits to supply hydrogen and / or natural gas to the fuel control manifold 28. The fuel control manifold holds and / or mixes the fuel (e.g., when both hydrogen and natural gas are supplied to the fuel control manifold, it mixes the hydrogen with the natural gas to provide a fuel containing hydrogen and natural gas as fuel), and can be configured to supply fuel to one or more fuel supply conduits via the 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., the fuel supply conduit 29a for the first burner element, the fuel supply conduit 29b for the second burner element, etc.) to supply fuel, so that the fuel can be output through the inner fuel openings of the inner nozzles of each burner element.

[0079] The supply conduit 29a for the first burner element and the fuel supply conduit 29b for the second burner element can each include a conduit arrangement and a control valve 30, so that at least a minimum amount of fuel is supplied to the inner fuel nozzle opening to which the supply conduit is connected. For example, the fuel received from the fuel control manifold 28 can be passed to a fuel supply conduit segment 31a downstream of the supply conduit of the burner element, so that the fuel can be passed along a bypass flow conduit segment 31b and / or through the control valve 30 to a downstream conduit segment 31c connected to an inner fuel nozzle opening for outputting fuel into the chamber above the tank 2. The downstream fuel supply 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. The bypass flow conduit segment 31b can be positioned between the upstream fuel supply conduit segment 31a and the downstream fuel supply conduit segment 31c, so that fuel from the upstream fuel supply conduit segment 31a can move to the downstream conduit segment 31c without flowing through the control valve 30. The downstream conduit segment 31c can be positioned between the inner nozzle of the burner element to which the fuel supply conduit is connected and the control valve 30. The downstream conduit segment 31c can also be positioned between the inner nozzle to which the fuel supply conduit is connected and the outlet of the bypass flow conduit segment 31b.

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

[0081] As can be best understood from FIGS. 3 and 4, the first burner element 13 and the second burner element 15 can be positioned such that the flow of fuel 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., an angle of 0° with respect to the wall surface to which the burner is attached, or the angle at which the pilot flame outputs fuel for that flame) with respect to the central flat angle. The horizontal angle α can be in the range of + / −5° to + / −20°.

[0082] The lower and upper limits of the horizontal angle α can be defined or determined such that the fuel is completely burned 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 in the furnace. The final angle between the nozzles can be determined by the furnace width. In addition, the furnace width is another parameter that determines such an included horizontal angle α. Since it is desirable to prevent the flame output from the nozzle from colliding with the furnace wall, the width can affect the desired horizontal angle α.

[0083] For example, the supply conduit 15c for the second inner fuel outlet 15f of the second burner element 15 can extend linearly from the fuel supply 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 with respect to the horizontal direction in which the pilot flame supply conduit 11c extends linearly to the pilot flame port 11. This horizontal angle can be considered as 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 supply conduit 15c can include a downstream conduit segment 31c, or be completely this segment.

[0084] The horizontal angle α for the second burner element 15 can also be regarded as the angle α at which the longitudinal axis 15L of the supply conduit 15c for the second burner element 15 intersects the burner surface plane 10fp at a complementary angle (90° - α) with respect to the perpendicular to the second inner nozzle 15IN of the second burner element 15 and with respect to the major axis of the second inner nozzle 15IN of the second burner element 15 (e.g., the length L of the second inner fuel outlet 15f). 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 supply conduit 13c for the first inner fuel outlet 13f of the first burner element 13 can extend linearly from the fuel supply 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 with respect to the horizontal direction in which the pilot flame supply conduit 11c extends linearly to the pilot flame port 11. This horizontal angle can be regarded as the second preselected horizontal angle, or the preselected horizontal angle of the first burner element 13. The horizontal angle α can be in the range of + / -5° to + / -20°. It should be understood that at least a portion of the supply conduit 15c can include the downstream conduit segment 31c or can be entirely this segment.

[0086] The horizontal angle α for the first burner element 13 can also be regarded as the angle α at which the longitudinal axis 13L of the supply conduit 13c for the first burner element 13 intersects the burner surface plane 10fp at a complementary angle (90° - α) with respect to the perpendicular to the first inner nozzle 13IN of the first burner element 13 and with respect to the major axis of the first inner nozzle 13IN of the first burner element 13 (e.g., the length L of the first inner fuel outlet 13f). 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 supply conduit 15c for the second burner element 15 can be an axis extending in the direction of the fuel flow, which can be the direction in which fuel is passed through the supply conduit 15c for output from the second inner fuel outlet 15f of the second inner nozzle 15IN. Also, the longitudinal axis 13L of the supply conduit 13c for the first burner element 13 can be an axis extending in the direction of the fuel flow, which can be the direction in which fuel is passed through the supply conduit 13c for output from the first inner fuel outlet 13f of the first inner nozzle 13IN. In such an arrangement, the longitudinal axes 13L and 15L can be aligned with the direction of the fuel flow for the fuel passed through the supply conduits 13c and 15c for output from the first inner nozzle 13IN and the second inner nozzle 15IN.

[0088] As can be understood from FIGS. 3 and 4, in some embodiments, the horizontal angle α at which the supply conduit 15c for the second inner fuel outlet 15f extends linearly can range from -5° to -20°, and the horizontal angle α at which the supply conduit 13c for the first inner fuel outlet 13f extends linearly can range from 5° to 20°. In other embodiments, the horizontal angle α at which the supply conduit 15c for the second inner fuel outlet 15f extends linearly can range from 5° to 20°, and the horizontal angle α at which the supply conduit 13c for the first inner fuel outlet 13f extends linearly can range from -5° to -20°.

[0089] It should be understood that the value of the horizontal angle α can be the same nominal value for the first burner element 13 and the second burner element 15 (for example, when the angles α for the burner elements are 5° and -5°, the same nominal value for the angle α is 5°, etc.). In such embodiments, the longitudinal axis 13L of the supply conduit 13c for the first burner element 13 can be angled by an angle that is twice the nominal value of the angle α (for example, 2α, or 2*α) with respect to the longitudinal axis 15L of the supply conduit 15c for the second burner element 13.

[0090] The supply conduit 15c for the second inner fuel outlet 15f can 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 fuel supply conduit 29b to the second inner fuel outlet 15f. Alternatively, the supply conduit 15c for the second inner fuel outlet 15f 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 plane). The vertical angle along which the supply conduit 15c for the second inner fuel outlet 15f can extend can be regarded as a tilt angle. The tilt angle is also an angle β which can also be called, the longitudinal axis 15L of the supply conduit 15c intersects the plane defined by the major axis and the minor axis of the second inner nozzle 15IN of the second burner element (e.g., the plane defined by the length L and the height hf of the second inner fuel outlet 15f) at a complementary angle (90° - β) with respect to the perpendicular of the second inner nozzle 15IN and with respect to the minor axis of the second inner nozzle 15IN (e.g., the height hf of the second inner fuel outlet 15f). Since the tilt angle (or angle β) can be up to +10° with respect to a horizontal orientation having no vertical component of the direction, or up to -10° with respect to a horizontal orientation having no vertical component of the direction, the conduit 15c extends linearly along a vertical tilt angle in the range of -10° to +10°.

[0091] The supply conduit 13c for the first inner fuel outlet 13f can also be positioned to extend linearly, so that when the conduit 13c extends from the first nozzle fuel supply conduit 29a to the first inner fuel outlet 13f, it is in a horizontal orientation (e.g., no tilt angle). Alternatively, the supply 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 plane). The vertical angle along which the supply conduit 13c for the first inner fuel outlet 13f can extend can be regarded as a tilt angle. The tilt angle is also such that the longitudinal axis 13L of the supply conduit 13c intersects the plane defined by the major axis and the minor axis of the first inner nozzle 13IN of the first burner element (e.g., the plane defined by the length L and the height hf of the first inner fuel outlet 13f) at a complementary angle (90° - β) with respect to the perpendicular of the first inner nozzle 13IN and with respect to the minor axis of the first inner nozzle 13IN (e.g., at the height hf of the first inner fuel outlet 13f). The tilt angle (or, angle β) can be up to +10° with respect to a horizontal orientation having no vertical component of direction, or up to -10° with respect to a horizontal orientation having no vertical component of direction, so that the conduit 13c extends linearly along a vertical tilt angle in the range of -10° to +10°. It should be understood that a tilt angle greater than 0° (e.g., +1° or +10°, etc.) can be regarded as an upward tilt direction that can induce fuel upward, and a tilt angle less than 0° (e.g., -1° or -10°, etc.) can be regarded as a downward tilt direction that can induce fuel downward.

[0092] In some embodiments, the inclination angle of the supply conduit 13c for the first inner fuel outlet 13f can be a value opposite to the inclination angle of the supply conduit 15c for the second inner fuel outlet 15f. For example, the inclination angle of the supply conduit 13c for the first inner fuel outlet 13f can be in the range of greater than 0° to +10°, and the inclination angle of the supply conduit 15c for the second inner fuel outlet 15c can be in the range of less than 0° to -10°. As another example, the inclination angle of the supply conduit 13c for the first inner fuel outlet 13f can be in the range of less than 0° to -10°, and the inclination angle of the supply conduit 15c for the second inner fuel outlet 15c can be in the range of greater than 0° to +10°. In other embodiments, the inclination angles of both the supply 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 supply 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., having 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 can be angled away from the staging nozzle 17. The longitudinal axis 15L of the supply conduit 15c can 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 with respect 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 high-temperature side 10h of the burner, while the second fuel outlet 15f of the second burner element is recessed in a direction 0.25 inches to 0.75 inches away from the high-temperature side 10h of the burner (e.g., recessed by 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 high-temperature side 10h of the burner, while the second fuel outlet 15f of the second burner element 15 is recessed in a direction 0.15 inches to 1.0 inches away from the high-temperature side 10h of the burner (e.g., recessed by 0.381 cm to 2.54 cm). The positioning of the recess of the second inner fuel outlet 15f with respect to the second outer oxidant outlet 15o can help protect the fuel line (e.g., natural gas fuel line, etc.) from any damage caused by corrosive furnace high-temperature gas. This can help extend the life of the fuel line until replacement is necessary.

[0095] The first inner fuel outlet 13f of the first burner element 13 can be recessed with respect 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 high-temperature side 10h of the burner, while the first fuel outlet 13f of the first burner element 13 is recessed in a direction 0.25 inches to 0.75 inches away from the high-temperature side 10h of the burner (e.g., recessed by 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 high-temperature side 10h of the burner, while the first fuel outlet 13f of the first burner element 13 is recessed in a direction 0.15 inches to 1.0 inches away from the high-temperature side 10h of the burner (e.g., recessed by 0.381 cm to 2.54 cm).

[0096] In addition to the tilt angle, the horizontal angle α, and the recessed arrangement, the vertical and horizontal nozzle spacing and positioning (e.g., vertical spacing along the height of the wall, horizontal offset positioning, etc.) can be adapted to meet a set of specific design criteria for providing a stable flame that can provide low NOx emissions, while enabling a flame to be generated from a fuel that is natural gas fuel, hydrogen fuel, 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 adapted such that these burner elements can be aligned with each other's centers or offset horizontally 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 can each be the same or similar (e.g., the length L of the first fuel outlet 13f can be 90% to 110% of the length L of the second inner fuel outlet 15f). The length L of each outlet can be the length of the major axis of the outlet. For example, the length L can define the major axis length measured in the burner surface 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 can define the major axis length measured in the burner surface 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 major axis of the first inner nozzle 13IN having the first inner fuel outlet 13f can be substantially parallel to the major axis of the second inner nozzle 15IN having the second inner fuel outlet 15f such that these major axes are parallel or within 5° of being parallel.

[0098] The positioning of the second upper fuel outlet 15f and the first lower fuel outlet 13f can be arranged such that the center of the first fuel outlet 13f is horizontally spaced 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 these minor axes are parallel or within 5° from a parallel state.

[0099] Figures 8 and 9 illustrate, for example, examples of arrangements with different offset distances B (it should be understood that Figure 6 illustrates an arrangement with the same offset distance B as shown in Figure 8). The overlapping features of the first burner element 13 and the second burner element 15 can help facilitate the mixing of fuel and oxidant within the furnace volume in order to completely combust the fuel before it exits the furnace outlet.

[0100] In Figure 7, the horizontal length L of the first inner fuel outlet 13f can 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 in the burner plane 10fp can be lower than the height ho of the first outer oxidant outlet 13o of the first burner element 13 measured in the burner plane 10fp. As discussed above, each of these heights hf and ho can extend along the minor axis of the outlet that is perpendicular to the major axis of the outlet defining the length (L or Lo) of the outlet. The first outer oxidant outlet 13o of the first burner element 13 can be annular in shape such that the first inner fuel outlet 13f is positioned within the central opening of the first outer oxidant outlet 13o.

[0101] The horizontal length L of the second inner fuel outlet 15f can be shorter than the horizontal length Lo of the second outer oxidant outlet 15o of the second burner element 15 measured in the burner plane 10fp. Additionally, the height hf of the second inner fuel outlet 15f can be lower than the height ho of the second outer oxidant outlet 15o of the second burner element 15 measured in the burner plane 10fp. As discussed above, each of these heights hf and ho can extend along the minor axis of the outlet perpendicular to the major axis of the outlet that defines the length of the outlet. The second outer oxidant outlet 15o of the second burner element 15 can be annular such 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 can 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 can 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 can 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 can be configured and positioned as the upper oxidant flow nozzle 17) can have a length X and a height Y measured in the burner plane 10fp. The length X can be defined such that the staging nozzle 17 has an oxidant outlet 17o that extends from the leftmost position of the first fuel outlet 13f and / or the second fuel outlet 15f to the rightmost position of the first fuel outlet 13f and / or the second fuel outlet 15f. The height Y of the oxidant outlet 17o can be the vertical distance of the maximum part of the outlet, the height of the outlet, or the diameter of the outlet (depending on the shape of the outlet, which can 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 horizontally across the entire length L of the first fuel outlet 13f, and is vertically spaced from and above the first inner fuel outlet 13f and the second inner fuel outlet 15f, and also extends horizontally across the entire length L of the second fuel outlet 15f at a position above them.

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

[0105] The nozzle positioning of the first burner element 13, the second burner element 15, the pilot flame port 11, and the upper oxidant flow nozzle 17 can be arranged to meet the following criteria in order 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 interval H1 divided by the height hf of the inner fuel outlet.

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

[0108] (c) 2 ≤ H3 / hf ≤ 20, where H3 / hf is the third vertical interval 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 can help prevent the nozzles from being too far apart, as it can help ensure that the fuel and oxidant mix well enough in the furnace to provide complete combustion of the fuel (or at least very nearly complete combustion of the fuel).

[0111] In addition, the above design criteria (a), (b), and (c) can help ensure the implementation of safe ignition for burners in a low-temperature furnace without CO breakout in the flue gas (ignition can be a state where a flame is first generated in the low-temperature furnace at the start of the burner). An exemplary ignition sequence can be that the pilot burner 11 is utilized to facilitate the ignition of the first lower nozzle fuel outlet 13f, and then the flame from the first lower burner element 13 can ignite the fuel output from the second fuel outlet 15f. The operating upper limit for the start of flame generation via the ignition sequence can be near or at a state where incomplete combustion of the fuel exiting the furnace during burner startup can occur, while the operating lower limit can be defined to help reduce NOx generation and minimize the influence of the flow interaction between the flame and / or the upper oxidant flow nozzle 17, the first burner element 13, and the second burner element 15.

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

[0113] In addition, the oxidant outlet 17o of the upper oxidant flow nozzle 17 can have dimensions of 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 oxidant flow nozzle 17, and Y is the height of the upper oxidant flow nozzle 17). The oxidant velocity output from the oxidant outlet 17o of the upper oxidant flow nozzle 17 can be in the range of 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 oxidant flow nozzle 17 can be adapted to facilitate the generation of a stable flame with low NOx emissions from the furnace and minimal CO breakout. The lower and upper limits of the oxidant staging in the upper oxidant flow nozzle 17 can be defined based on the optimal burner operation in the furnace. For example, the oxidant output from the oxidant outlet 17o of the upper oxidant flow nozzle 17 can be 5% to 30% of the total oxidant flow rate output from the burner (e.g., 5% to 30% of the total oxidant flow from the first burner element 13, the second burner element 15, and the upper oxidant flow nozzle 17). The upper limit of the oxidant staging can be set to prevent overheating of the top wall of the furnace and heat dissipation at the top of the furnace. This oxidant output state can be adjusted to meet the requirement that the oxidant output from the first burner element 13 is the same flow rate or approximately 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 the same output flow rate as the oxidant output from the second outer oxidant outlet 15o, or within 10% or 15% of the same flow rate of the oxidant output from the oxidant outlets of other burner elements). Such output oxidants 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 can be configured to provide different types of fuel staging. For example, the fuel flow rates output from the first fuel outlet 13f and the second fuel outlet 15f can be the same when both burner elements are in the active mode. When one burner element is in the active mode and the other burner element is in the passive mode, the fuel output from each burner element can be different. For example, the passive burner element can output fuel from its fuel outlet such that the fuel output from its active burner element is 65% to 95% of the total fuel output from burner 10, and the fuel output from the passive burner element can be 35% to 5% of the total fuel output from burner 10.

[0116] The active mode operation of the burner element (e.g., the first burner element 13, the second burner element 15, or both burner elements, etc.) can be understood from FIG. 5. For example, in the active mode, fuel is output from the fuel control manifold 28, the control valve 30 is open, and the fuel can be passed to the burner element operating in the active mode so that the fuel is supplied to the burner element at a high rate exceeding the minimum fuel flow rate. When the burner element is in the passive mode, the control valve 30 can be fully closed such that only the minimum fuel flow rate is supplied to the burner element through fuel that can pass through a bypass conduit segment 31b that allows the minimum fuel flow rate to bypass the closed control valve 30 and flow to the burner element.

[0117] The control valve 30 can be controlled to allow all burner elements to be in the active mode simultaneously, or can be configured to switch which of the burner elements are in the active mode and which are in the passive mode (e.g., alternate between active mode cycles and passive mode cycles during a preselected active mode time cycle). For example, the control valve of the first fuel supply conduit 29a can be fully opened, and the control valve 30 of the second fuel supply conduit 29b can be fully closed during a first preselected active mode period (e.g., 15 seconds, 5 minutes, 3 hours, etc.). After this period has elapsed, the control valve can be adjusted so that the control valve of the first fuel supply conduit 29a can be fully closed and the control valve 30 of the second fuel supply conduit 29b can be fully opened during a second preselected active mode period (e.g., 15 seconds, 5 minutes, 3 hours, etc.). Such switching of which burner elements are active and which are passive can continue for multiple cycles. Such cycling can help provide low emissions, prevent overheating of the metal in the high temperature side 10h of the burner and / or in the vicinity of the side wall where the burner is attached, and maintain or improve the yield due to the low oxygen atmosphere near the surface of the tank. This is particularly applicable 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) breakout and can help provide complete combustion during startup of a low temperature furnace (e.g., while the heating device is below the autoignition temperature of the fuel).

[0118] The operation of the burner when both the first burner element 13 and the second burner element 15 are in the active mode can be configured to provide an equivalence ratio of 1.05 to 1.5 (e.g., 1.05 < equivalence ratio < 1.5, or an equivalence ratio of 1.05 or more and 1.5 or less). It should be understood that for a given fuel flow rate, the equivalence ratio can be determined as the ratio of the theoretical stoichiometric oxidizer flow to the actual oxidizer flow.

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

[0120] For example, the passive burner element can be operated at an equivalence ratio of 0.1 to 1.0 (e.g., 0.1 < equivalence ratio < 1.0, or an equivalence ratio of 0.1 or more and 1.0 or less), and the active burner element can be operated at an equivalence ratio of 1.4 to 3.0 (e.g., 1.4 < equivalence ratio < 3.0, or an equivalence ratio of 1.4 or more and 3 or less). It should be understood that the additional oxidant that can be provided by the upper staging nozzle 17 can help facilitate complete combustion of the fuel, even though one or all of the burner elements can operate in a fuel-rich state (e.g., an equivalence ratio greater than 1).

[0121] The function of the control valve 30 can be controlled by a controller CTRL communicatively connected to the control valve. The controller can be communicatively connected to one or more sensors of the device to monitor the state in the furnace and / or conduit. At least one of the sensors can be positioned in the furnace or chamber above the tank 2, or can be positioned to detect one or more states in the chamber above the tank or in the furnace. Such sensors can include, for example, temperature sensors, pressure sensors, and flow rate or mass flow rate sensors. When the processor of the controller executes the code, the controller is configured to automatically control the opening and closing of the control valve 30 according to a predefined control algorithm defined by the code stored in the non-transitory memory of the controller, based on the sensor data and any operator input that can be provided via one or more input devices (such as a computer communicatively connected to the controller), to adjust the position of the valve. The controller CTRL can be configured to monitor and / or control the operation of the burner 10 during startup of at least one burner such that the first burner element 13 and the second burner element 15 are in an active mode where the first and second burner elements operate at an equivalence ratio of 1.05 to 1.5.

[0122] After the device 1 for transitional heating operates at a preselected operating temperature that exceeds the autoignition temperature of the fuel supplied to at least one burner, the controller switches the first burner element 13 from the active mode to the passive mode, and then, after a first preselected period, switches the first burner element 13 from the passive mode to the active mode while communicating with a control valve 30 for switching the second burner element 15 from the active mode to the passive mode. Such switching of the active and passive modes of the first burner element 13 and the second burner element 15 can occur multiple times in a number of cycles. In some configurations, the controller CTRL and the control valve 30 can be configured such that the active mode of the burner element is a mode with an equivalence ratio of 1.4 to 3.0 and the passive mode is a mode with an equivalence ratio of 0.1 to 1.0.

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

[0124] The controller CTRL is configured to independently control the fuel flow to each of the first inner nozzles 13IN and 15IN of the first burner element 13 and the second burner element 15, and also to control the distribution of the total oxidant flow such that it consists of a primary oxidant flow distributed between the first annular nozzles 13AN and 15AN (e.g., the first outer oxidant outlets 13o and 15o) of the first burner element 13 and the second burner element 15, and a secondary oxidant flow provided to the staging nozzle 17. The primary oxidant flow can be 60% - 95% of the total oxidant flow, and the secondary oxidant flow can be the remainder (e.g., 40% - 5% of the total oxidant flow). The primary oxidant flow can be distributed between the first burner element and the second burner element at a ratio of 0.9 - 1.1 between the first annular nozzle 13AN and the second annular nozzle 15AN.

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

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

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

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

[0129] Embodiments of the controller can include a workstation that executes an automatic process control program communicatively connected to a control valve 30, sensors, and other control elements. The controller can also include a processor connected to a non-transitory computer-readable medium storing the code of the control program, and at least one transceiver for communication connections to the control valve and sensors (e.g., via a network connection, a wireless network connection, or a wired communication connection). One or more input devices can be connectable to the controller to enable a user to provide input to the controller. One or more output devices (e.g., a display, a printer, etc.) can similarly be communicatively connected to the controller to provide output to the user.

[0130] As shown in FIG. 1, a burner 10 can be deployed 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 can, in some embodiments, include a tank sized to hold a metal for melting the metal via transient heating. The sidewalls 6 can extend vertically above the tank and the top, or the ceiling can be positioned above the tank and attached to the sidewalls to surround the tank 2. An array of burners 3 can be positioned to combust fuel and provide a flame within a chamber above the tank. The hot gases from the formed flame can swirl or otherwise flow within the chamber above the metal tank to provide transient heating to the metal to melt the metal within the tank 2.

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

[0132] At least one side wall 6 and / or the topmost part can include at least one transient heating burner 10 that can be used in combination with and / or in place of other burners (such as oxy-fuel burners, regenerative burners, etc.). In some embodiments, each burner 10 of an 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 that can be positioned to generate a flame for transient heating of the metal in the bath 2. The burner arrangement, utilized in combination with the controlled operation of the burners, can provide a desired heating profile to the heated flow of hot gas in the chamber above the bath for heating the metal in the bath 2.

[0133] Each burner 10 can include a burner face configured to be positionable on the inner surface of the furnace. For example, the burner 10 can be mounted to be in the same plane as the inner surface of the furnace. For example, the burner face for the burner can be configured to be in the same plane as the side wall 6 when the burner 10 is mounted to the side wall 6. As another example, the burner face can also be configured to be in the same plane as the topmost part when the burner 10 is mounted to the topmost part. As yet another example, the burner 10 can be mounted to the side wall 6 or the topmost part so as to be positionable on the inner surface of the furnace for supplying fuel and oxidant into the chamber above the bath 2. The burner face 10f of the burner can define a burner face plane 10fp. The burner face plane 10fp can be the plane from which fuel and oxidant supplied into the chamber above the bath 2 are output from the burner 10.

[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 were performed using the same conditions in the same type of furnace but having different burner configurations. The first CFD evaluation was performed for one 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 oxidant flow nozzle 17. The fuel used in this simulation was natural gas, and 100 volume % oxygen was used as the oxidant. The results of the floating oxygen concentration near the bath surface for these two CFD evaluations are shown in FIG. 10 (without the upper oxidant flow nozzle 17) and FIG. 11 (with the upper oxidant flow nozzle 17).

[0135] FIGS. 10 and 11 each show a graph 2a of the oxygen concentration at the surface of the bath 2. The graphs illustrate the results from the CFD evaluations performed. FIG. 10 illustrates a high oxygen concentration region near the burner 10. FIG. 11 shows that by using the upper oxidant flow nozzle 17, it was possible to remove this region and a more uniform and lower concentration of oxygen was provided across the entire bath 2.

[0136] The evaluated embodiment of the burner 10 of the present invention using CFD analysis can help reduce the oxygen concentration near the bath surface to about 5% (when this nozzle is present) compared to about 15% (when this nozzle is omitted) when the upper oxidant flow nozzle 17 is not utilized within the burner. By using the upper oxidant flow nozzle 17, it can help reduce or maintain the oxidation of the metal bath at a reference level. Positioning the upper oxidant flow nozzle 17 above the first burner element 13 and the second burner element 15 (and / or any other additional third nozzle that can output fuel and oxygen) creates a blanket surface that helps avoid the oxygen output from the burner 10 from flowing towards the bath 2 under the pilot flame port 11 for the nozzles located between the upper oxidant flow nozzle 17 and the bath surface, and it has been found to be useful for moving oxygen away from the metal bath surface.

[0137] The evaluation of the embodiment of the burner of the present invention performed also showed that by utilizing the upper oxidant flow nozzle 17 above the first burner element 13 and the second burner element 15 (and / or any other additional third burner element that can output fuel and oxygen), it was useful for reducing NOx emissions. By using the upper oxidant flow nozzle 17, it has been found that the NOx emissions can be reduced by as much as 50% compared to an embodiment of the burner that utilizes only the first burner element 13 and the second burner element 15 without the upper oxidant flow nozzle 17.

[0138] The exemplary burner 10 was also tested privately in the industrial-scale laboratory furnace of the present invention at a firing rate of 5 MMBtu / hr. The oxidizer used in the test was 100% by volume oxygen. Table 1 below presents the experimental inspection points and the corresponding exhaust gases obtained from this test. In Table 1 below, the fuel type NG is natural gas, the fuel type H2 is hydrogen gas, CO2 is carbon dioxide present in the exhaust gas, O2 is oxygen present in the exhaust gas, NOx is nitrous oxide in the exhaust gas, and CO is carbon monoxide in the exhaust gas. [Table 1]

[0139] Table 1 above shows that in the first case, one inner fuel nozzle of the fuel burner element is active while the other inner fuel nozzle of the other burner element is passive, and in the second case, both the first fuel burner element 13 and the second fuel burner element 15 are active, indicating that the burner 10 can operate in both operating modes of the burner. This performance of the burner 10 has been shown to help provide operational flexibility to the burner 10 based on the operating needs of the plant. The data obtained from the test indicates that embodiments of the burner 10 can be fuel-flexible (e.g., can operate with natural gas as fuel and mixtures of natural gas and hydrogen). In addition, the NOx and CO emissions are very low, which is thought to be due to the structure and configuration of the dual-staging burner. The dual-staging and appropriate sizing of the burner according to the above design criteria (a)-(d) helps, for example, to create two flames output from the burner 10 with minimal flame interaction, avoid the 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] Figure 12 is a graph showing a comparison of the normalized NOx emissions (lbs / MMBtu) between a conventional oxy-fuel burner and an embodiment of the new transient heating burner of the present invention as a function of the rate of air leakage in the furnace. The results of the embodiment of the transient heating burner of the present invention (with one burner element active and another burner element passive in a periodic operation as considered herein) are presented for two cases using two different types of fuel: one using natural gas (NG), labeled "New Transient Burner (NG Fuel)" in Figure 12, and the other using a 70% heat content natural gas - 30% heat content hydrogen mixture, labeled "New Transient Burner (NG / H2 Fuel)". The plots shown in Figure 12 indicate that the embodiment of the new transient burner produces a total NOx emission that is 40% lower compared to the conventional oxy-fuel burner. The total NOx emissions from the new transient burner are similar when operating with natural gas or a natural-hydrogen fuel mixture, considering measurement uncertainties and furnace operating factors.

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

[0142] For example, for a batch load of 62,000 lbs (28,122.7 kg), two CFD simulations were performed using natural gas fuel for the burners in the furnace. The first CFD simulation used an air-fuel combustion device with a conventional burner ("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 is a hybrid combustion (the "Hybrid" in Table 2, where one air-fuel burner is replaced by one multi-stage staging transient heating burner) provided through an embodiment of the multi-stage staging transient heating burner 10 and was simulated to use hybrid combustion. Table 2 shows the energy balance of the furnace. The embodiment of the burner 10 of the present invention was found to help improve the efficiency of operation by about 9%. The melting time of the metal in the tank can be shortened from 4.1 hours to 3.0 hours (this provided an increase in production of about 26% by speeding up production by only 1.1 hours), and by reducing the fuel consumption from 1328 British Thermal Units (BTU) per pound (lb) to 975 BTU / lb, a 26.6% reduction in fuel usage was provided.

Table 2

[0143] Also, the use of a burner using natural gas as fuel was compared with the use of a burner using a mixture of 30% heat value hydrogen (H2) and 70% heat value natural gas (NG). Table 3 below shows the results of these analyses. As can be understood from Table 3, the burner 10 was able to maintain its performance using both natural gas and the natural gas / hydrogen mixture for the evaluations performed.

Table 3

[0144] Embodiments of the burner 10 can also utilize additional burner elements. For example, there may be a third burner element between the pilot flame port 11 and the first burner element 13. Since this third nozzle can be positioned and aligned to output fuel and oxidant into the heating device 1, it is output in a central alignment (e.g., at an inclination angle of 0° and a horizontal angle of α0°). Other embodiments are also contemplated to optionally 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 in the same manner as, for example, the first burner element 13 and the second burner element 15, but can be arranged to provide different fuel and / or oxidant flow paths (e.g., outputting fuel to provide an inclination angle of 0° and a horizontal angle of α0°).

[0145] As can be understood from the above, a device for transient heating (e.g., a reverberatory furnace), and a burner that can be incorporated into such a device, can be configured to include process control elements (e.g., at least one workstation including temperature sensors, pressure sensors, flow sensors, a processor, a non-transitory memory, and at least one transceiver for communicating with the sensors, valves, and controllers for providing a user interface to an automatic process control system operable on the system's workstation and / or another computer device) positioned and configured to monitor and control the operation.

[0146] Embodiments of the burner 10 can utilize different types of fuel. For example, as an alternative to (or in addition to) the use of 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 the following and "≧" refers to the above. It should also be understood that the fuel may contain combustible materials. Examples of fuels include natural gas, hydrogen gas, diesel, coal, or other fuel sources that can be burned. The fuel can be passed through the inner nozzle of the burner element. The oxidant can refer to a fluid that includes the concentration of oxygen available for the combustion of the fuel. The oxidant can be passed through the annular nozzle of the burner element surrounding the inner nozzle of the burner element. In some embodiments, the fuel or other materials can be included together with the oxidant passed through the annular nozzle.

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

Claims

1. A burner for transient heating of a furnace, the burner comprising: A burner surface configured to be positioned on the inner surface of the furnace when the burner is attached to the furnace, the burner surface defining a burner surface plane; A first burner element having a first annular nozzle configured to flow a primary oxidant surrounding a first inner nozzle configured to flow fuel; A second burner element having a second annular nozzle configured to flow a primary oxidant surrounding a second inner nozzle configured to flow fuel, the second burner element being positioned adjacent to and spaced from the first burner element; A staging nozzle configured to flow a secondary oxidant, the staging nozzle being positioned adjacent to and spaced 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 plane of the burner surface, and a minor axis height h measured in the plane of the burner surface ｆ defined by, a minor axis, and a fuel nozzle aspect ratio of 5 ≦ L / h ｆ ≦ 15, and The staging nozzle has a major axis defined by a major axis length X measured in the burner surface plane and a minor axis defined by a minor axis height Y measured in the burner surface plane; A burner, 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 each other within a deviation of 5° or less.

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

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

5.

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

5. The minor axis of the first inner nozzle is offset by a distance B from the minor axis of the second inner nozzle, 0 < B / L ≦ 1.5, The burner according to 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° or less.

6. Further comprising a pilot flame port positioned adjacent to and spaced from the first burner element by a distance H3; The first burner element is positioned between the second burner element and the pilot flame port; 2 ≤ H3 / h ｆ ≤ 20, the burner according to claim 1.

7. A first fuel conduit configured to supply fuel to the first inner nozzle, having a longitudinal axis aligned with the direction of fuel flow in the first fuel conduit, the longitudinal axis being at an angle α with respect to the perpendicular to the first inner nozzle and at a complementary angle (90° - α) with respect to the major axis of the first inner nozzle, and intersecting the burner surface plane, the first fuel conduit; A second fuel conduit configured to supply fuel to the second inner nozzle, having a longitudinal axis aligned with the direction of fuel flow in the second fuel conduit, the longitudinal axis being at an angle α with respect to the perpendicular to the second inner nozzle and at a complementary angle (90° - α) with respect to the major axis of the second inner nozzle, and intersecting the burner surface plane, the second fuel conduit; further comprising The longitudinal axis of the first fuel conduit and the longitudinal axis of the second fuel conduit are angled with respect to each other at an angle of 2α. The burner according to claim 1, wherein 0 < α ≦ 20°.

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

9. The longitudinal axis of the first fuel conduit is at an angle β with respect to the perpendicular to the first inner nozzle and at a complementary angle (90° - β) with respect to the minor axis of the first inner nozzle, and intersects the plane defined by the major axis and the minor axis of the first inner nozzle. The longitudinal axis of the second fuel conduit is at an angle β with respect to the perpendicular to the second inner nozzle and at a complementary angle (90° - β) with respect to the minor axis of the second inner nozzle, and intersects the plane defined by the major axis and the minor axis of the second inner nozzle. The longitudinal axis of the first fuel conduit and the longitudinal axis of the second fuel conduit are each angled in a direction away from the staging nozzle. The burner according to claim 7, wherein 0 < β ≦ 10°.

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

11. A total fuel flow and a total oxidant flow are provided to the burner in an equivalence ratio, where equivalence ratio 1 represents the stoichiometric ratio of fuel to oxidant, greater than equivalence ratio 1 represents a fuel-rich stoichiometry, less than equivalence ratio 1 represents a fuel-lean stoichiometry, and the burner Further comprises a controller, the controller Independently controls the fuel flow to each of the first inner nozzle and the second inner nozzle; Programmed to control the distribution of the total oxidant flow such that it consists 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, the primary oxidant flow being 60% to 95% of the total oxidant flow. The burner according to claim 1.

12. The burner according to 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. 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 1.05 to 1.5 and the equivalence ratio of the second burner element is 1.05 to 1.

5. The burner according to claim 11.

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

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

16. The first annular nozzle and the second annular nozzle each have a major axis and a minor axis that respectively coincide with the major axis and the minor axis of the first inner nozzle and the second inner nozzle, and the minor axis of each of the first annular nozzle and the second annular nozzle is defined by a height h ｏ which is defined by Fuel exits from each of the first inner nozzle and the second inner nozzle at a fuel velocity. Primary oxidant exits from each of the first annular nozzle and the second annular nozzle at a primary oxidant velocity. Ratio h ｏ / h ｆ is sized to provide a ratio of 1 to 4 of the fuel rate to the primary oxidant rate, the burner according to claim 1.

17. Further comprising a pilot flame port positioned below the first burner element, the top of the pilot flame port being vertically spaced from the bottom of the first annular nozzle by a third vertical interval H3 such that 2 ≦ H3 / h ｆ ≦ 20, The bottom of the second burner element is spaced apart from the top of the first annular nozzle by a first vertical distance H1, where 2 ≦ H1 / h ｆ ≦ 20, and The bottom of the staging nozzle is spaced from the top of the second annular nozzle by a second vertical distance H2, where 2 ≤ H2 / h ｆ ≤ 20, and The minor axis of the first inner nozzle is offset by a distance B from the minor axis of the second inner nozzle, where 0 < B / L ≤ 1.

5. The burner according to 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° or less.

18. A furnace comprising a wall, a top, a bath for solid and / or liquid material, a burner according to claim 1, wherein the first burner element is closer to the bath than the second burner element and the staging nozzle is closer to the top than the second burner element, the burner being positioned on the wall.

19. A method of operating the burner according to claim 1 in a furnace, the method comprising Flowing a total oxidant flow composed 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 into the burner, 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, and flowing the total oxidant flow, Flowing a total fuel flow into the burner, Including switching the operation of the burner between a proportional mode and an alternating mode, In the proportional mode, the total fuel flow is distributed between the first inner nozzle and the second inner nozzle such that the equivalence ratio of the first burner element is 1.05 to 1.5 and the equivalence ratio of the second burner element is 1.05 to 1.5, In the alternating mode, the total fuel flow distributed between the first inner nozzle and the second inner nozzle switches back and forth between a first state where the first burner element is active and the second burner element is passive, and a second state where the first burner element is passive and the first burner element is active, and 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, A method in which an equivalence ratio of 1 indicates a stoichiometric ratio of fuel to oxidant, 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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