Burner and operating method

Abstract

The present invention relates to a specific burner, in particular to an unpremixed or partially premixed fuel burner having the flexibility to oxygen-enrich the burner. Thus, the burner can be used in applications requiring burner operation in both air-fuel mode and / or oxygen-fuel mode and / or air-oxygen-fuel mode, depending on the operating requirements of the furnace. The present invention further relates to a furnace including a burner and a method of operating the burner.

Description

[[TECHNICAL FIELD]]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Non-Provisional Application No. 18 / 233,393 filed on August 14, 2023, which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a burner, particularly an industrial burner for gaseous fuel, and more particularly to a burner capable of operating as, for example, both an air-fuel burner or an air-oxygen-fuel burner. [[BACKGROUND ART]]

[0003] In the prior art, many high-temperature heating or melting preheating furnaces are designed with air-fuel burners in mind.

[0004] Due to increasing product demand, manufacturers are aiming to improve the productivity of currently operating plants. Furthermore, increasing scrutiny from emission regulatory authorities necessitates improving the efficiency of current furnace operation and reducing emission amounts.

[0005] Furthermore, the need for decarbonization has brought increasing pressure to shift to the use of low carbon intensity fuels such as hydrogen and ammonia in medium and high temperature application industries.

[0006] There are several potential approaches to address these challenges.

[0007] First, fuel-flexible burners that can operate using any gaseous fuel such as natural gas ("NG"), liquefied petroleum gas ("LPG"), biogas, syngas, hydrogen, ammonia or other gases, and meet emission and thermal performance requirements for heating furnaces or melting furnaces can be used. The design of fuel-flexible gaseous fuel burners faces several challenges depending on the type and design of the burner.

[0008] Aside from the wide variation in the combustion behavior of these fuels (which is well documented in the combustion literature), differences in the thermal values, reaction rates, and flammability limits of gaseous fuels, for example, present challenges when designing burners. For example, one challenge is that when NG is replaced with H2, the total volumetric flow rate of the gas begins to increase for the same MMBtu rating of the burner. The increased volumetric flow rate will affect the nozzle outlet velocity, which may influence flame stability, the heating profile of the flame, and the burner's discharge characteristics, depending on the burner design.

[0009] Secondly, air-oxygen-fuel (AOF) burners may be a viable solution because they use pure oxygen or oxygen-enriched air as the oxidizer, helping to replace a portion of the air as the oxidizer. AOF burners help improve plant productivity and thermal efficiency for several reasons, which are well documented in the literature [Baukal Jr, Charles E. Oxygen-enhanced combustion. CRC press, 2010]. The main reasons include increased plant thermal efficiency as diluted nitrogen decreases, thereby reducing the heat absorbed and carried by nitrogen, and higher peak temperatures that allow for higher heat transfer rates through flamethrowing.

[0010] The extent to which AOF burner benefits are utilized in a process depends on the total oxygen enrichment of the burner. Baukal Jr, Charles E., *Oxygen-enhanced combustion*, CRC press, 2010, shows plots of available energy versus oxidant composition at different exhaust temperatures. The inventors observe that available heat increases rapidly to 35%–45% at the initial air enrichment level, but with further increases in enrichment level, process benefits increase, though not at a nearly as rapid pace. This is considered important because available heat is an indirect measure of thermal efficiency. The plots provide specific guidance on where furnace operators can potentially choose to operate the burner and / or furnace at intermediate enrichment levels, thereby optimizing the balance between process benefits and oxygen costs.

[0011] A further challenge for AOF burners is NOx emissions, as the level of air enrichment increases the burner's tendency to form NOx due to the localized increase in oxygen concentration. Thermal NOx formation continues to increase up to a certain level of enrichment (potentially peaking somewhere between 40-60% enrichment, depending on the burner design). By further increasing the enrichment level beyond 40-60%, NOx emissions begin to decrease as the localized N2 concentration begins to decline, and NOx formation continues to decrease as the burner operation moves towards a pure air-fuel burner.

[0012] Therefore, a first object of the present invention is to provide an advantageous burner that mitigates or overcomes one or more of the above-mentioned problems. The present invention provides a fuel-flexible burner. This burner also allows operation in air-fuel and / or air-oxygen-fuel modes without modifying the burner. Furthermore, this burner generates low NOx under all of these operating conditions.

[0013] The design of a particular conventional burner can be summarized as follows:

[0014] EP3 967 925 A1 describes a burner having different internal sections compared to the present invention.

[0015] US5308239 and US5871343 disclose burners having air-oxygen fuel designs with different concepts and NOx design strategies, in contrast to the present invention.

[0016] US8727767 discloses a planar flame burner that operates in a different mode compared to the present invention.

[0017] AU 684296 B2 discloses air-fuel and air-oxygen-fuel burners having a different design compared to the present invention, in which air swirls around fuel and oxygen jets. [Overview of the Initiative]

[0018] In general, the present invention relates to burners, in particular to burners that can be used in high-heating applications, especially burners that require operation in air-fuel mode, oxygen-fuel mode, and / or air-oxygen-fuel mode, depending on the operating requirements of the furnace.

[0019] Specifically, the present invention relates to the subject matter as defined in the claims.

[0020] The present invention provides a burner that can be used in applications requiring burner operation in both air-fuel mode and air-oxygen-fuel mode, depending on the operating requirements of the furnace.

[0021] The burner of the present invention helps to solve the above problems by providing a novel burner design that is fuel flexible (for example, operating with NG or H2 and / or NG / H2 mixtures), providing operational flexibility between air-fuel mode and air-oxygen-fuel mode, as well as low NOx and CO emissions for air-fuel mode and air-oxygen-fuel mode.

[0022] In general, the burner of the present invention can be used in any application requiring high heating, specifically in applications such as steam methane reforming, reheating furnaces in the steel industry, or secondary melting furnaces.

[0023] In a general embodiment, the present invention provides a burner (1) comprising an ignition source (10) and a primary fuel conduit (20) having a primary fuel outlet (22) with a plurality of primary fuel outlet holes (23) for supplying primary fuel to an ignition chamber (25), the ignition chamber (25) being positioned within the primary fuel conduit (20) extending from the primary fuel outlet (22) to the primary fuel conduit end plane (24), the primary fuel conduit wall (29) having a plurality of bleed holes (28) at the location of the ignition chamber (25) and a primary oxide conduit (30) for supplying the primary oxide The burner comprises a main oxide conduit (30) located in the downstream portion (5) of the burner, the intermediate annular conduit (35) being configured to allow the main oxide to be divided into two parts, the first part of which is introduced into the ignition chamber (25) via a plurality of bleed holes (28) and mixed with the primary fuel, and the second part of which is introduced into the swivel vane section (33), the second part of which is further composed of a secondary fuel conduit (40) for supplying secondary fuel, and having a secondary fuel outlet (44) at its downstream end.

[0024] Further provided by the present invention are, in particular, a furnace including the burner of the present invention, and a method for operating the burner.

[0025] The specific (further) advantages of the burner of the present invention are disclosed below. [Brief explanation of the drawing]

[0026] The present invention will be described below in conjunction with the attached drawings, and similar reference numerals indicate similar elements. [Figure 1A] This is an exemplary side view of the downstream portion of an exemplary burner of the present invention, including its cross-section at the downstream end. Specifically, it shows a preferred arrangement having connectors and central axes for each conduit. [Figure 1B] It is an exemplary side cross-sectional view of the downstream portion of an exemplary burner according to the present invention, including the cross-section thereof at the downstream end. Specifically, it shows a preferred arrangement having connectors for respective conduits and a central axis. [Figure 2A] It is an exemplary side cross-sectional view of the downstream portion of the burner according to the present invention, showing the flow of various components such as primary fuel and secondary fuel, a main oxidant divided into a bleed hole section and a swirl vane section (e.g., air, oxygen, or a combination thereof), and optional staged oxidant. [Figure 2B] It is an exemplary cross-sectional view of the downstream portion of the burner according to the present invention, highlighting various components and optional components such as air bleed holes, turbulence generator plates, and conduits for staged oxidant. [Figure 3A] It is an exemplary side cross-sectional view of the downstream portion of the burner according to the present invention, highlighting specific distances, diameters and the like, including dimensions of various conduits (or pipes), and the specific distance between an outlet plane and a discharge port, respectively. [Figure 3B] It is an exemplary cross-sectional view of the downstream portion of the burner according to the present invention, highlighting specific distances, diameters and the like, while showing D0 as the diameter of a primary fuel outlet hole and D1 as the diameter of a purge air outlet hole. [Figure 4] It is an exemplary cross-sectional view of the downstream portion of the burner according to the present invention, highlighting, for example, angles β and θ, the use of a primary fuel plate as a primary fuel discharge port, and the use of an optional air purge plate for (a section of) the main oxidant. It further shows how consecutive holes in different rows of holes can be offset by half of the included angle between two consecutive holes in one row. [Figure 5] It includes a schematic diagram of a primary fuel conduit according to an embodiment of the present invention, highlighting the optional arrangement of bleed holes (with diameter P1), showing optional air premixing holes, and further highlighting angle α, that is, the angle between the centers of two consecutive holes measured at the center of the conduit. [Figure 6A] It is an exemplary side cross-sectional view of the downstream portion of the burner according to the present invention, highlighting, for example, the flow and interaction of primary fuel and main oxidant. [Figure 6B]The figure shows a corresponding embodiment that includes the optional feature of partial premixing described above. A purge hole in the wall of pipe 2 diverts a small portion of the main oxidizer to the primary fuel pipe. [Figure 6C] For example, this is a related diagram that highlights the interaction between secondary fuels and stepwise oxidizers. [Figure 7A] This is a schematic diagram illustrating the operation of a burner, showing various steps in one embodiment for operating the burner of the present invention. [Figure 7B] This is a schematic diagram illustrating the operation of a burner, showing various steps in one embodiment for operating the burner of the present invention. [Figure 8] This shows an exemplary burner of the present invention and a comparison of experimental results (normalized NOx data) obtained in the prior art. [Figure 9A] This is an illustrative cross-sectional view of an alternative embodiment of the present invention, which involves an alternative type of (partial) premixing of the primary fuel and main oxidizer (e.g., air), such as using a "step design." [Figure 9B] This is an illustrative cross-sectional view of an alternative embodiment of the present invention, which involves an alternative type of (partial) premixing of the primary fuel and main oxidizer (e.g., air), such as using a "step design." [Figure 9C] This is an illustrative cross-sectional view of an alternative embodiment of the present invention, which involves an alternative type of (partial) premixing of the primary fuel and main oxidizer (e.g., air), such as using a "step design." [Figure 10] An exemplary cross-sectional view of an embodiment of the present invention, including an ignition cup (75) and an air bleed cup (76), is shown, indicating the respective distances L0, L01, L1, etc. [Figure 11] The following are further examples of specific features of the burner of the present invention described in this embodiment 1 (such as the fixing point and stabilization surface). [Figure 12] Further burner designs mentioned in this embodiment are illustrated. [Modes for carrying out the invention]

[0027] The present invention generally provides a burner and further subject matter as defined in the claims.

[0028] The burner of the present invention overcomes the problems of the prior art described above in various ways.

[0029] For example, the burner can operate in air-fuel mode in a low-temperature furnace (average temperature < 400F during the burner start-up sequence) without requiring oxygen assistance or a continuous ignition source. The burner can also operate stably in lean fuel, low flame temperature modes. The burner generates a stable flame (without lift-off) over a very wide 1:30 turndown range, even with an equivalence ratio of 0.25 or less. This is a particularly important feature when refractories are being relined. The burner can operate in air-fuel mode to cure refractories using air-fuel mode, which typically produces a lower maximum flame temperature compared to oxygen-fuel or air-oxygen-fuel modes. These features allow for preheating of the process furnace at a controlled rate, enabling the process to start and reach a steady state within a timeframe determined by process requirements.

[0030] Furthermore, the oxidizer back pressure (air and oxygen and / or enriched air) within the burner of the present invention is such that there is no need for any external secondary compression device for these flows. This feature helps reduce the operating costs of the burner and the maintenance associated with such activities.

[0031] Furthermore, the burners of the present invention offer lower NOx performance while being able to operate at (relatively common) lower speeds compared to the requirement of a speed of Ma (Mach number) = 1 or higher for some burners that require high supply pressure. Increased supply requirements can potentially increase the operating costs of the burners. NOx formation occurs primarily through rapid and thermal NOx formation. As will be readily apparent to those skilled in the art, thermal NOx formation depends on three parameters: local oxygen concentration, local nitrogen concentration, and local temperature.

[0032] Current burners employ multiple strategies simultaneously to achieve low NOx performance. Three fluids, preferably air, fuel, and oxygen / oxygen-enriched air, are supplied through spatially separated outlets / ports, thereby simultaneously reducing the interaction of O2, N2, and high temperatures at local levels.

[0033] Furthermore, this burner design allows for localized interaction between either fuel / air or fuel / O2 combustion, thereby helping to increase the separation of the high-temperature zone (fuel / O2 combustion) from the air, and therefore from N2.

[0034] In addition, this burner design allows for rapid and complete mixing of a portion of the air-fuel mixture at the ignition point. This is made possible through air entrainment within the fuel jet via a unique burner cup tip (ignition chamber) design, thereby reducing the peak temperature compared to the typical characteristics of unpremixed burners. Lower peak temperatures compared to conventional unpremixed air-fuel combustion help reduce thermal NOx formation.

[0035] While fuel and / or oxidizer step feeding is a commonly known technique for reducing flame peak temperature and decreasing NOx formation, this burner may incorporate oxidizer step feeding to facilitate dispersed combustion to lower peak temperatures and thus NOx formation.

[0036] Furthermore, the burner of the present invention may be further optimized by a fixed fuel split ratio so as not to require active control when transitioning from air-fuel to air-oxygen-fuel mode, thereby reducing the cost of burner operation.

[0037] Finally, the two fuel supply ports play a crucial role in optimizing burner operation, taking into account changes in fuel composition based on the fuel supplier, for example, from NG or H2 to an NG / H2 fuel mixture.

[0038] This burner allows for starting / igniting the burner at a low equimolar ratio of 0.25 (lean fuel start), particularly in situations where it is impossible to reduce the airflow below a specific setpoint while the starting fuel flow rate is simultaneously minimized for safety reasons. The equimolar ratio is defined as the ratio of the actual fuel / air molar ratio to the stoichiometric fuel / air molar ratio.

[0039] In particular, a first aspect of this specification provides a burner (1) comprising an ignition source (10) and a primary fuel conduit (20) having a primary fuel outlet (22) with a plurality of primary fuel outlet holes (23) for supplying primary fuel to an ignition chamber (25), wherein the ignition chamber (25) is located within the primary fuel conduit (20) extending from the primary fuel outlet (22) to the primary fuel conduit end plane (24), and the primary fuel conduit wall (29) surrounding the ignition chamber (25) has a plurality of bleed holes (28) and a primary oxide conduit (30) for supplying a primary oxide, with an intermediate annular conduit (35) in the downstream portion (5) of the burner, The intermediate annular conduit (35) comprises a main oxide conduit (30) configured to allow the division of the main oxide so that a first portion is introduced into the ignition chamber (25) via a plurality of bleed holes (28) and mixed with the primary fuel, and a secondary fuel conduit (40) for supplying secondary fuel having a secondary fuel outlet (44) at its downstream end, wherein in at least the downstream portion (5) of the burner (1) where the primary fuel outlet (22), ignition chamber (25), intermediate annular conduit (35), and secondary fuel outlet (44) are located, the primary fuel conduit (20) is surrounded by the main oxide conduit (30) and the secondary fuel conduit (40).

[0040] As used herein, the “downstream portion of the burner” having a particular outlet refers to the downstream portion comprising all of the said outlets. Furthermore, the portion further comprises a swivel vane section and / or bleed holes.

[0041] The term “downstream portion” is used interchangeably with the term “downstream section” in this specification.

[0042] In preferred embodiments of this specification, in at least the downstream portion (5) of the burner (1) where the primary fuel outlet (22), ignition chamber (25), intermediate annular conduit (35), and secondary fuel outlet (44) are located, the main oxide conduit (30) and the secondary fuel conduit (40) are arranged essentially concentrically around the primary fuel conduit (20).

[0043] In a particular embodiment of the present invention, one or more given conduits are arranged (concentrically) around one or more other given conduits, the conduits are arranged around another in a section corresponding to at least 20%, preferably at least 30%, particularly at least 40%, particularly at least 50%, and in some embodiments at least 75% of the total length of the burner, the section including a primary fuel outlet, a main oxidizer outlet, a secondary fuel outlet, and an auxiliary oxidizer outlet. Furthermore, if a swirl vane section and / or bleed hole ring is additionally present, the portion preferably further includes the swirl vane section and / or bleed hole ring.

[0044] In this specification, the "total length" of the burner of the present invention is determined by establishing the distance between the furthest upstream end of all conduits and the furthest downstream end of all conduits.

[0045] In a further preferred embodiment, the primary fuel conduit, the main oxide conduit, and the secondary fuel conduit (and optionally the secondary oxide conduit) are arranged concentrically around a central ignition source along their entire length.

[0046] In a preferred embodiment of the present invention, if a given conduit is arranged concentrically around another conduit, this results in the formation of each ring.

[0047] Consequently, in preferred embodiments herein, the burner is configured such that one or more fuels or oxidizers flow through at least one ring. In the present invention, such rings may be further characterized by including further elements of the respective conduit (such as outlet holes, bleed holes, swirl vane sections, etc.) as defined elsewhere herein.

[0048] Similarly, in a preferred embodiment of this specification, the burner is characterized in that one or more outlets of the conduit are configured as an annular ring. In the present invention, such annular ring may be characterized by including further elements (such as an outlet hole, a bleed hole, a swivel vane section, etc.) as defined elsewhere in this specification.

[0049] In general, in the present invention, a particular conduit is described as being "surrounded" by a particular other conduit (or several other conduits, respectively) if the conduit is smaller in diameter than the other conduit and is located inside the other conduit.

[0050] However, in order to be “surrounded” by another conduit, a given conduit does not need to be completely surrounded by the other, but may extend further downstream and / or upstream from the other. Where it is said that a given element is “arranged” around another element, the respective definitions apply herein.

[0051] In a preferred embodiment, a conduit described as being surrounded by other conduits shares its longitudinal axis with those other conduits.

[0052] In a preferred embodiment, the ignition chamber (25) extends from the primary fuel conduit outlet plane (55) to the intermediate annular conduit outlet plane (56).

[0053] In certain preferred embodiments, the ignition chamber (25) is characterized by at least two (preferably two or three) steps in its wall, each step comprising a row of bleed holes (28).

[0054] In certain preferred embodiments, the ignition chamber (25) comprises a section having an outer diameter less than or equal to the inner diameter of the primary fuel conduit (20).

[0055] In certain preferred embodiments, the ignition chamber (25) further comprises a section having an inner diameter that is larger than the outer diameter of the primary fuel conduit (20) but smaller than the inner diameter of the intermediate annular conduit (35).

[0056] More specifically, in one set of particular embodiments, the burner is characterized in that the ignition chamber (25) extends from a primary fuel outlet (22) to an intermediate annular conduit outlet plane (56), and the wall surrounding the ignition chamber (25) includes at least two (preferably two or three) steps of an annular conduit with increasing diameter, each of which is provided with a plurality of bleed holes (28).

[0057] In another set of particular embodiments, the burner has an ignition chamber (25) extending from a primary fuel outlet (22) to an intermediate annular conduit outlet plane (56), and the wall surrounding the ignition chamber (25) comprises two sections: i) a first section extending from the primary fuel outlet (22) to the primary fuel conduit end plane (24), the primary fuel conduit wall (29) surrounding the section comprises a plurality of bleed holes (28); and ii) a second section having an inner diameter larger than the outer diameter of the primary fuel conduit (20), but the second section is an intermediate annular conduit (35) The burner is characterized in that it has an outer diameter smaller than its inner diameter and is further provided with a plurality of bleed holes (28), and optionally further comprises an air purge plate (73) having a purge hole (32) extending between the outer diameter of the first section and the inner diameter of the second section, and optionally further comprises two mechanical mixer plates (74) each located adjacent to each other downstream of the two sections, and optionally further comprises a purge plate (73) having a purge hole (32) located between the outer diameter of the second section and the inner diameter of the intermediate annular conduit (35).

[0058] Preferably, the mechanical mixer plate (74) has a disc-shaped structure that divides the fuel flow coming out of the fuel outlet hole (23). Specifically, the first mechanical mixer plate has a disc-shaped structure (mechanical mixer 1) that divides the fuel flow coming out of the "outer series" of fuel outlet holes (23). The disc divides these fuel jets and helps to rapidly mix the fuel and air inside the ignition chamber.

[0059] Preferably, the purge plate (73) is a disc having purge holes (32). More preferably, the plate / disc is located between the fuel conduit wall (29) and the intermediate conduit wall located inside the conduit (35).

[0060] In a further set of specific embodiments, the burner has an ignition chamber (25) extending from a primary fuel outlet (22) to an intermediate annular conduit outlet plane (56), and the wall surrounding the ignition chamber (25) comprises two sections: i) a first section having an outer diameter smaller than the inner diameter of the primary fuel conduit (20) and comprising a plurality of bleed holes (28); and a primary fuel conduit wall (29) surrounding the first section comprising a plurality of bleed holes (28), wherein the first section allows the main oxide to flow additionally into the ignition chamber (25) between two rings of the primary fuel outlet hole. The burner further comprises means to enable the following: ii) the second section has an inner diameter larger than the outer diameter of the primary fuel conduit (20), but the second section has an outer diameter smaller than the inner diameter of the intermediate annular conduit (35), and further comprises a plurality of bleed holes (28), and the burner further optionally comprises: iii) a purge plate (73) having purge holes (32) located between the outer diameter of the first section and the inner diameter of the second section; and iv) a purge plate (73) having purge holes (32) located between the outer diameter of the second section and the inner diameter of the intermediate annular conduit (35).

[0061] In certain preferred embodiments, the ignition chamber (25) comprises an ignition cup (75) and a bleed cup (76). Preferably, the ignition cup (75) is included in a first section of the ignition chamber (25), and the bleed cup (76) is included in a second section of the ignition chamber (25), the second section being located downstream of the first section.

[0062] More specifically, in one set of particular embodiments, the burner is characterized in that the ignition chamber (25) extends from the primary fuel outlet (22) to the intermediate annular conduit outlet plane (56), and the wall surrounding the ignition chamber (25) comprises two sections: i) the first section having an outer diameter less than or equal to the outer diameter of the primary fuel conduit (20) and comprising a plurality of bleed holes (28), the wall surrounding the first section comprising a plurality of bleed holes (28), the first section further comprising means for allowing the main oxidizer to enter the ignition chamber (25) in the flow direction; and ii) the second section having an inner diameter greater than the outer diameter of the primary fuel conduit (20), but the second section having an outer diameter smaller than the inner diameter of the intermediate annular conduit (35), and further comprising a plurality of bleed holes (28). Preferably, the burner further comprises a purge plate (73) having a purge hole (32) located between the outer diameter of the first section and the inner diameter of the second section. Preferably, the burner further comprises a purge plate (73) having a purge hole (32) located between the outer diameter of the second section and the inner diameter of the intermediate annular conduit (35). Preferably, the burner further optionally comprises a mechanical mixer plate (74) located adjacent to the first section downstream.

[0063] Preferably, as specified herein, the burner further comprises an ignition source (10) which preferably terminates in an ignition chamber (25).

[0064] In certain embodiments, the ignition source (10) is a central ignition source having a central axis (15) and a conduit end plane (16).

[0065] In a preferred embodiment of this specification, the main shaft (2) of the burner (1) coincides with the central axis (15) of the ignition source (10).

[0066] Preferably, at least in the downstream portion (5) of the burner (1), the central ignition source (10) is surrounded by a primary fuel conduit (20), a main oxide conduit (30), a secondary fuel conduit (40), and optionally a plurality of secondary oxide conduits (50).

[0067] In certain embodiments, the main shaft (2) of the burner (1) coincides with the central axis (15) of the ignition source (10).

[0068] Furthermore, with respect to the ignition source (10), it may be designated as “pipe 1” in this specification.

[0069] The (central) ignition source may also be referred to simply as the “igniter” in this specification.

[0070] In this specification, the outer diameter of the ignition source (10) may be defined as D2.

[0071] Therefore, the central ignition source wall (19) may have an outer diameter D2.

[0072] Furthermore, the central ignition source is preferably located in the center of the burner, preferably along its entire length, and in particular, the remaining conduits of the burner are arranged concentrically around the central ignition source.

[0073] Furthermore, with respect to the primary fuel conduit (20), the same may be designated herein as “pipe 2”, which is a gaseous fuel pipe.

[0074] In this specification, the inner diameter of the primary fuel conduit (20) may be defined as the distance D3.

[0075] Therefore, the primary fuel conduit wall (29) may have an inner diameter D3.

[0076] In certain embodiments, the primary fuel conduit end plane (24) corresponds to the ignition chamber end plane (26).

[0077] The primary fuel conduit (20) further comprises a primary fuel outlet (22). In certain embodiments, the primary fuel outlet (22) is configured as a plate having a primary fuel outlet hole (23), in particular as an air purge plate having a primary fuel outlet hole (23).

[0078] The primary fuel conduit (20) may further include a specific primary fuel connector (21).

[0079] In this specification, the distance between the primary fuel outlet (22) and the primary fuel conduit end plane (24) and / or the ignition chamber end plane (26) may be defined as L0. Thus, in certain embodiments, the primary fuel outlet (22) is recessed upstream from the primary fuel conduit end plane (24) by a distance L0. Preferably, the primary fuel conduit end plane (24) corresponds to the ignition chamber end plane (26).

[0080] In the burners described herein, the primary fuel conduit (20), more specifically the primary fuel outlet (22), further comprises a primary fuel outlet hole (23). Thus, the primary fuel outlet (22) may also be designated herein as a “fuel distribution nozzle.” The outlet / nozzle may be described as having a plurality of holes for introducing primary fuel into the ignition chamber.

[0081] In this specification, the diameter of the primary fuel outlet hole (23) may be defined as D0. Preferably, D0 / D2 is 0.04 to 0.5.

[0082] In certain embodiments, the primary fuel outlet holes (23) are located on concentric circles around the center of the primary fuel outlet plate. Preferably, the total number of concentric circles is in the range of 2 to 7, and more preferably, the total number of concentric circles is 2 to 5. Preferably, the holes are circular. The holes may have any other shape, such as a star, triangle, double star, rectangle, etc.

[0083] While not intended to be constrained by theory, such a size would significantly contribute to the ability to rapidly mix the fuel with the surrounding air.

[0084] In this specification, the circumferential angle defined by the central axis (2) of the burner and the centers of the two adjacent primary fuel outlet holes (23) may be defined as the angle theta.

[0085] In the burner described herein, the primary fuel conduit (20) further includes a bleed hole (28).

[0086] In this specification, the inner diameter of the exhaust port (28) may be defined as P1. Preferably, P1 / D2 is 0.05 to 0.4.

[0087] In certain embodiments, the bleed holes (28) are arranged in rows around the primary fuel conduit. Preferably, there are five rows or fewer bleed holes, more preferably three rows or fewer bleed holes. Preferably, the holes are circular. The holes may have any other shape, such as star, triangle, double star, or rectangle.

[0088] In this specification, the axial distance between two rows of bleed holes (28), measured between their centers, may be defined as H.

[0089] In this specification, the circumferential angle defined by the center of the burner's main shaft (2) and the two adjacent bleed holes (28) may be defined as angle alpha.

[0090] In certain embodiments of this specification, the primary fuel conduit (20) further comprises an air premixing port (27), preferably upstream of the primary fuel outlet (22).

[0091] In this specification, the diameter of the air premixing hole (27) may be defined as P0. Preferably, P0 / D2 is 0.02 to 0.2.

[0092] In certain embodiments, the air premixing holes (27) are arranged in rows around the primary fuel conduit. Preferably, there are no more than five rows of premixing holes. More preferably, there are no fewer than three rows of premixing holes. Preferably, the holes are circular. The holes may have any other shape, such as a star, triangle, double star, or rectangle.

[0093] In this specification, the distance between the primary fuel conduit wall (29) and the intermediate annular conduit wall (37) may be defined as L4.

[0094] Furthermore, with respect to the main oxidizer conduit (30), it may be designated herein as "pipe 3", in particular as an air pipe.

[0095] In this specification, the inner diameter of the main oxidizer conduit (30) may be defined as D4.

[0096] Therefore, the main oxidizer conduit wall (39) may have an inner diameter D4.

[0097] In this specification, the distance between the intermediate annular conduit end plane (36) and the main oxide conduit end plane (38) may be defined as L2. Thus, in certain embodiments, the intermediate annular conduit end plane (36) is recessed upstream from the main oxide conduit end plane (38) by a distance L2.

[0098] In the burner of this specification, the main oxidizer conduit (30) further comprises an intermediate annular conduit (35).

[0099] In the present invention, the intermediate annular conduit (35) is configured to allow the main oxide to be divided into two parts, the first of which is introduced into the ignition chamber (25) through the plurality of bleed holes (28) defined above.

[0100] The first portion is preferably about 20% of the total volumetric flow rate. In certain embodiments, the first portion is in the range of 2% to 40%, preferably in the range of 10% to 25%.

[0101] In a preferred embodiment of this specification, the first portion of the main oxide enters the ignition chamber perpendicular to the primary fuel outlet (through the peripheral wall of the chamber).

[0102] Therefore, in a preferred embodiment of this specification, the first portion of the main oxide enters the ignition chamber in a direction perpendicular to the flow direction of the primary fuel.

[0103] While not intended to be theoretically binding, this helps to actively mix the fuel and "ignition" air so that the peak flame temperature is reduced compared to a typical diffusion flame. This is considered important for minimizing flame-generated NOx emissions. Furthermore, the method of air introduction keeps the surrounding wall cool by protecting it from direct contact with the flame.

[0104] In this specification, the distance between the primary fuel conduit end plane (24) and the intermediate annular conduit end plane (36) may be defined as L1. Thus, in certain embodiments, the primary fuel conduit end plane (24) is recessed upstream from the intermediate annular conduit end plane (36) by a distance L1.

[0105] In a preferred embodiment of the present invention, the burner is characterized in that the main oxidizer conduit (30) further comprises a swivel vane section (33).

[0106] Therefore, the intermediate annular conduit (35) is preferably configured to allow the main oxide to be divided into two parts, the second of which is introduced into the swivel vane section (33).

[0107] In particular, in preferred embodiments of this specification, the annular conduit (35) is configured to allow the main oxide to be divided into two parts, with a first portion being introduced into the ignition chamber (25) via a plurality of bleed holes (28) and mixed with the primary fuel, and a second portion being introduced into the swivel vane section (33) and further comprising a main oxide conduit.

[0108] While not intended to be constrained by theory, the second portion of air introduced into the swivel section induces a strong tangential flow field within the combustion chamber, acting to increase the mixing rate between the oxidizer and the fuel, while simultaneously producing a compact flame and a flame that does not produce significant soot.

[0109] Again, without being constrained by theory, the use of swirl vanes to swirl air is well known in the field of combustion. The main function of the swirl is, for example, to provide a tangential flow to the air exiting pipe 3 and create a recirculation zone in the center that returns the hot combustion gases toward the burner outlet plane, providing a continuous ignition source for fresh reactants. The upper and lower limits of the swirl angle are determined by the length of the furnace, as well as the burner firing rate.

[0110] Preferably, the swivel angle is 5 to 60 degrees, preferably 30 to 45 degrees.

[0111] As used herein, “angle of rotation” is defined as the angle between a plane nominally tangent to the exit of the rotating blade and a plane parallel to the main axis of the burner.

[0112] Preferably, the number of turns (defined herein as the ratio of the axial velocity of tangential momentum to the axial velocity of axial momentum) is in the range of 0.1 to 1.5.

[0113] In certain embodiments, the main oxidizer conduit (30) further comprises purge holes (32) located on the air purge plate (73), particularly in a flow direction parallel to the main axis (2) of the burner.

[0114] In this specification, the diameter of the purge hole (32) may be defined as D1. Preferably, D1 / D2 is 0.04 to 0.5.

[0115] In certain embodiments, the purge holes (32) are arranged in a circular pattern on different concentric diameters, with 1 to 7 rows of holes, preferably 1 to 3 concentric diameters. Preferably, the holes are circular. The holes may have any other shape, such as a star, triangle, double star, or rectangle.

[0116] In this specification, the circumferential angle defined by the center of the burner's main shaft (2) and the two adjacent purge holes (32) may be defined as angle beta.

[0117] The main oxide conduit (30) may further comprise a specific main oxide connector (31).

[0118] Furthermore, with respect to the secondary fuel conduit (40), the same may be designated herein as “pipe 4”, which is a gaseous fuel pipe.

[0119] In this specification, the inner diameter of the secondary fuel conduit (40) may be defined as the distance D5.

[0120] Therefore, the secondary fuel conduit wall (49) may have an inner diameter D5.

[0121] In certain embodiments, the burner (1) further comprises a turbulence generator (47) within the secondary fuel conduit (40).

[0122] A turbulence generator may also be referred to herein as a means for generating turbulence or turbulence generator means. Each of these may comprise one or more turbulence generator disks or turbulence generator plates. Preferably, the turbulence generator means is located in an additional wall of a secondary fuel conduit positioned next to the wall of the main oxidizer conduit.

[0123] In this specification, the distance between the primary oxide conduit end plane (38) and the secondary fuel conduit end plane (46) may be defined as L3. Thus, in certain embodiments, the primary oxide conduit end plane (38) is recessed upstream from the secondary fuel conduit end plane (46) by a distance L3. Preferably, the secondary fuel conduit end plane (46) corresponds to the secondary oxide conduit end plane (56).

[0124] The secondary fuel conduit (40) may further comprise a specific secondary fuel connector (41).

[0125] In a preferred embodiment of the present invention, the burner further comprises a plurality of secondary oxidizer conduits (50) for supplying a secondary oxidizer (e.g., air, oxygen, or a combination thereof). In this specification, the latter may also be designated as “secondary oxidizer”.

[0126] Preferably, these conduits are arranged as an outer ring of the conduit. The conduits are used for oxygen enrichment. In preferred embodiments of the present invention, the secondary oxide conduits (50) may have turbulence generators (57) for increasing the mixing of the jet with the combustion atmosphere, and / or may be angled inward toward the center of the burner at a certain angle (preferably 0.2 to 25 degrees, more preferably 0.25 to 10.0 degrees, more preferably 0.5 to 5.0 degrees).

[0127] In a preferred embodiment, the secondary oxidizer is oxygen with a volume purity of 80% to 100%. In a preferred alternative embodiment, the secondary oxidizer is oxygen-enriched air with a volume purity of 23% to 50%.

[0128] Not intended to be constrained by theory, this configuration helps to spatially separate the oxygen / oxygen-enriched air inlet from the fuel inlet, thereby enabling delayed mixing and combustion, resulting in a flameless / low NOx burner.

[0129] In this specification, the distance between the centers of two secondary oxidizer conduits (50) located opposite each other with respect to the main axis (2) of the burner may be defined as D6.

[0130] In this specification, the inner diameter of the secondary oxide conduit (50) may be defined as D7.

[0131] Therefore, the secondary oxidized conduit wall (59) may have an inner diameter D7.

[0132] In this specification, the angle defined by the center of the burner's main axis (2) and the two adjacent secondary oxidizer conduits (50) may be defined as the angle eta.

[0133] The burner of the present invention is designed to operate using any gaseous fuel such as natural gas (NG), hydrogen (H2), LPG, biogas, synthesis gas, ammonia, or other gases.

[0134] Therefore, according to the present invention, the primary fuel used in the burner is any gaseous fuel. In preferred embodiments, it is selected from the group consisting of natural gas (NG), hydrogen (H2), LPG, biogas, synthesis gas, and ammonia. In other embodiments, it is selected from natural gas (NG), a mixture of NG / H2, and hydrogen.

[0135] According to the present invention, the secondary fuel is any gaseous fuel. In preferred embodiments, it is selected from the group consisting of natural gas (NG), hydrogen (H2), LPG, biogas, synthesis gas, and ammonia. In other embodiments, it is selected from natural gas (NG), a mixture of NG / H2, and hydrogen.

[0136] In a preferred embodiment, the main oxidizer is air.

[0137] In general, the specific properties of the fuel and oxidizer used with the burner of the present invention are not particularly limited in this specification. Furthermore, in some embodiments, the material flowing through a particular conduit (e.g., fuel or oxidizer) may be the same as those disclosed above or may be replaced with a different (e.g., oxidizer or fuel) material. For example, a secondary oxidizer may be used instead of secondary fuel in the burner (1). In this particular embodiment, the fuel flows through the primary fuel conduit (20) of the burner (1), while the oxidizer flows through the primary oxidizer conduit (30), the secondary fuel conduit (40), and optionally, the secondary oxidizer conduit (50). Alternatively, in some embodiments, secondary fuel can be used instead of the primary oxidizer. In this embodiment, the fuel flows through the primary fuel conduit (20) and the primary oxidizer conduit (30) of the burner (1), while the oxidizer or fuel flows through the secondary fuel conduit (40), and optionally, the secondary oxidizer conduit (50). In other words, any combination of fuel or oxidizer can flow through the primary fuel conduit (20), the main oxidizer conduit (30), the secondary fuel conduit (40), and optionally, the secondary oxidizer conduit of the burner (1).

[0138] As used herein, the “outlet plane” of a given conduit refers to a plane defined in a direction perpendicular to the main axis of the conduit at a downstream location where the fuel or oxidizer is no longer restricted by the two walls, respectively.

[0139] As used herein, the “conduit end plane” of a given conduit refers to a plane defined perpendicular to the principal axis of the conduit at the downstream end of the conduit.

[0140] In preferred embodiments of this specification, D3 / D2 is 1.5 to 4.5, particularly 2.0 to 3.0.

[0141] In preferred embodiments of this specification, D4 / D2 is 3.0 to 9.0, particularly 3.5 to 5.5.

[0142] In preferred embodiments of this specification, D5 / D2 is 5.0 to 11.0, particularly 5.5 to 7.0.

[0143] In preferred embodiments of this specification, L1 / L4 is 0.5 to 2.5, particularly 1.0 to 2.0.

[0144] In preferred embodiments of this specification, L0 / D3 is 0.25 to 1.0, particularly 0.4 to 0.6.

[0145] In preferred embodiments of this specification, (L1+L2) / D3 is 0.25 to 1.0, particularly 0.4 to 0.6.

[0146] In preferred embodiments of this specification, L3 / D4 is 0.05 to 0.25, particularly 0.1 to 0.2.

[0147] In preferred embodiments of this specification, D6 / D2 is 9.0 to 22.0, particularly 10.0 to 14.0.

[0148] In preferred embodiments of this specification, D6 / D5 is 1.75 to 2.5, particularly 1.8 to 2.1.

[0149] In preferred embodiments of this specification, D7 / D2 is 0.15 to 1.0, particularly 0.25 to 0.75.

[0150] In preferred embodiments of this specification, H / P1 is 1.25 to 2.5.

[0151] In preferred embodiments of this specification, the angle alpha is 3 to 30 degrees, for example, 10 to 20 degrees. The ratio of the area of ​​all bleed holes in one row to the surface area of ​​the cylinder with height P1 and bore diameter D2 is 10% to 55%.

[0152] While not intended to be theoretically binding, the lower limit of angle alpha helps to separate the holes so they are not too close together to interfere with the fuel-air mixture, and the upper limit of angle alpha prevents the holes from being too far apart, ensuring sufficient fluid communication between adjacent jets to enhance the fuel-air mixture and ignition inside the ignition chamber.

[0153] Each section may be symmetrically offset to provide a three-dimensional mixing effect. This mixing is important for providing reliable burner ignition at lean equivalent ratios as low as 0.25.

[0154] In preferred embodiments of this specification, the angle beta is 5 to 40 degrees.

[0155] The purge air plate (73) may have a porosity in the range of 2% to 15% (defined by dividing the total open area on the plate that allows air to flow by the cross-sectional area of ​​the plate).

[0156] While not intended to be constrained by theory, a lower range of angle beta helps separate the holes so they are not too close together to create an air-enriched region, while a higher range of angle beta prevents the holes from being too far apart, ensuring sufficient fluid communication between adjacent jets to support ignition and thereby provide each other with chemically active flame radicals that enhance flame stability. This creates a slow-speed and recirculation zone to provide sufficient air for the fuel-air mixture, as well as a flame fixing zone. This flame fixing location is critical to maintaining the flame without explosion, for example, under extreme conditions such as when the primary fuel is reduced to 10% of the burner's maximum ignition rating and the secondary fuel is cut off / shut down.

[0157] In some embodiments, the burner comprises a different series of holes, where consecutive holes in the different series of holes are offset by half an apex angle between two consecutive holes in the series.

[0158] In preferred embodiments of this specification, the angle theta is 10 to 40 degrees.

[0159] The primary fuel outlet plate (72) has a porosity in the range of 2% to 25% (defined by dividing the total open area on the plate that allows fuel to flow by the cross-sectional area of ​​the plate).

[0160] While not intended to be constrained by theory, the lower limit of the angle theta helps separate the holes so they are not too close together to prevent air entrainment within the fuel jets when the two fuel jets are too close, and a higher range of the angle theta prevents the holes from being too far apart, ensuring sufficient coupling between the development of the two jets to provide a wide range of turndown and equivolute ratios, resulting in an overall stable flame.

[0161] In preferred embodiments of this specification, the angle emitter is 10 to 70 degrees, particularly 40 to 60 degrees.

[0162] In some embodiments, the burner has holes in different rows, and the consecutive holes in different sets of holes are offset by half a vertex angle between two consecutive holes in one row.

[0163] In a preferred embodiment, the burner (1) is configured such that the velocity of the primary fuel at the outlet of the primary fuel outlet hole (23) is between 30 feet / second and 500 feet / second, particularly between 40 feet / second and 400 feet / second.

[0164] While not intended to be constrained by theory, it is determined that the velocity of the primary fuel significantly contributes to its ability to rapidly mix with the surrounding air. This velocity range provides a stable flame without lift-off.

[0165] In a preferred embodiment, the burner (1) is configured such that the velocity of the main oxidizer at the oxidizer section outlet (34) is 5 feet / second to 300 feet / second, particularly 10 feet / second to 200 feet / second.

[0166] While not intended to be theoretically constrained, the maximum achievable primary oxidizer (preferably air) velocity is typically determined by the available pressure from the air blower. The inventors have found that these velocities, along with a suitable swirl angle, provide sufficient mixing of air and the two fuels, maintaining a stable flame over a wide range of burner operations, even in low-temperature furnaces.

[0167] In a preferred embodiment, the burner (1) is configured such that the speed of the secondary fuel is 20 feet / second to 200 feet / second, and particularly 40 feet / second to 120 feet / second.

[0168] While not intended to be theoretically constrained, the secondary fuel velocity is determined to provide sufficient mixing with the air it swirls, thereby enabling a stable flame. If the secondary fuel velocity falls below the low-velocity limit, unreacted fuel may accumulate near the furnace wall. This fuel may then burn there, potentially causing overheating of the reformer upper wall. In a preferred embodiment, the burner (1) is configured such that the secondary oxidizer velocity is between 50 feet / second and 500 feet / second, particularly between 100 feet / second and 300 feet / second.

[0169] While not intended to be bound by theory, the rate of the stepwise oxidizer / secondary oxidizer typically remains high so that the enriched air or oxygen jet entrains ambient combustion gases and reduces the local concentration of oxygen before this high-oxygen-concentration jet fills the fuel and / or partially burned fuel / air mixture. This helps to slow down the mixing of fuel and oxidizer, contributing to broader combustion and reduced thermal NOx. The upper limit is determined so that the momentum is not high enough to cause delayed mixing and allow unburned fuel to exit the furnace. This is especially crucial when the furnace width or length is small. In addition, further increasing the rate increases the pressure requirements for the feed. Increased feed pressure necessitates a secondary compression device and increases the operating cost of the burner.

[0170] In a preferred embodiment, the burner of the present invention is i) During startup, approximately 100% of the burner's total thermal output (defined as the sum of the product of the heat value (higher or lower) and the flow rate of each fuel) is supplied by the primary fuel, and / or ii) The burner is operated in such a manner that during normal operation, approximately 25-65%, preferably 45-65%, of the burner's total heat value is supplied by the primary fuel, and the remainder is supplied by the secondary fuel. The remainder of each is preferably supplied by secondary fuel.

[0171] In a preferred embodiment, the burner is configured such that i) the volumetric flow rate of the ignition chamber oxidizer is about 5-25% of the total main oxidizer flow rate, and / or ii) the volumetric flow rate of the premixed oxidizer is about 2-10% of the total main oxidizer flow rate, and / or iii) the volumetric flow rate of the oxidizer diverted to the secondary oxidizer conduit (50) is about 2-5% of the main oxidizer flow rate.

[0172] In a particular conduit, the volumetric flow rate of any fluid is divided among different outlets by correlating the individual outlet cross-sectional areas with the total outlet cross-sectional area of ​​the conduit. In this way, the fluid pressure and the pressure difference between two adjacent conduits are important criteria for determining the directional flow of the fluid. For example, Figure 6B shows sample area notation for an oxidizer conduit. The cross-sectional areas of the exhaust port (28), air purge port (32), oxidizer section outlet (34), and premixing port (27) are A0, A1, A2, and A3.

[0173] A0 = (A0 + A1 + A2 + A3) 5-25%

[0174] A3 = (A0 + A1 + A2 + A3) 2-10%

[0175] Therefore, in preferred embodiments of this specification, the cross-sectional areas of the bleed hole (28), air purge hole (32), oxidizer section outlet (34), and premixing hole (27) are A0, A1, A2, and A3, respectively, where A0 = (A0 + A1 + A2 + A3) is 5 to 25%.

[0176] Similarly, in preferred embodiments of this specification, the cross-sectional areas of the bleed hole (28), air purge hole (32), oxidizer section outlet (34), and premixing hole (27) are A0, A1, A2, and A3, respectively, where A3 = 2 to 10% of (A0 + A1 + A2 + A3).

[0177] Preferably in this specification, the secondary fuel conduit (40) is adjacent to the main oxide conduit (30), and preferably D5 / D4 is 1.05 to 1.40, and more preferably D5 / D4 is 1.1 to 1.25. This allows the flow of secondary fuel and ignition to be initiated by heat from the primary fuel flame (which functions as a pilot flame for the secondary fuel) without requiring a furnace that exceeds the autoignition temperature of the secondary fuel and / or without requiring an ignition source to ignite the secondary fuel. Further specific embodiments of the present invention are shown in the drawings, outlined above, and can be described in more detail below.

[0178] For example, as shown in Figure 6a, a portion of the main oxidizer (typically 2% to 40%, preferably 10% to 25%, such as about 20% of the total) is introduced into the ignition chamber through the peripheral wall of the chamber, which is perpendicular to the fuel distribution nozzle. This helps to actively mix the fuel and "ignition" air to enable reliable and repeatable ignition with a gas mixture within the flammable range of fuel concentration, while allowing for a reduction in peak flame temperature compared to a typical diffusion flame. This is considered important for minimizing flame-generated NOx emissions. Furthermore, the method of air introduction keeps the peripheral wall cool by protecting it from direct contact with the flame. The fuel distribution plate (72) (this term may be used interchangeably with "primary fuel outlet plate" herein) is recessed by a length of L0 + L1 to give the fuel jet more length to partially or completely develop and partially premix with the "ignition cup" air.

[0179] More specifically, in a preferred embodiment, the distribution plate is recessed from the hot surface of the burner by a length of L0+L1+L2 or L01+L1+L2. More specifically, a portion of the main oxidizer (typically about 20% of the total amount) is introduced into the “ignition cup,” and the “oxidizer bleed cup” enters through the peripheral wall of the chamber, which is perpendicular to the fuel distribution nozzle. The first portion of the oxidizer entering the “ignition cup” can vigorously mix the portion of the fuel with the “ignition” oxidizer so that the mixed composition in the “ignition cup” can ignite the flame over a wide range of fuel and oxidizer flows. The second portion entering the “oxidizer bleed cup” can be mixed with the fuel so that the peak flame temperature can be reduced compared to a typical diffuse flame. This is considered important for minimizing flame-generated NOx emissions. Furthermore, the method of introducing the oxidizer also keeps the peripheral wall cool by protecting it from direct contact with the flame. The first portion of the fuel in the “ignition cup” mixes with the “ignition oxidizer.” The mechanical mixing plate divides the fuel jet in this first section and mixes it with the "ignition oxide." The second portion of fuel passing through the jet on plane 2 is recessed by L01+L1 to give the fuel jet enough length to fully or partially develop and partially premix with the oxide in the "oxide bleed cup." This feature helps stabilize the flame over a wide range of equivalence ratios.

[0180] For example, as shown in Figure 6b, the air premixing holes 27 allow fluid communication between the main oxidizer and the primary fuel upstream of the fuel distribution plate (72). These holes (number and diameter, rows of holes) may be predetermined based on the area ratio of holes A3 and the swirling air outlet region, as well as the pressures of the air and primary fuel. The predetermined ratio depends on the amount of air required for the primary fuel during startup.

[0181] For example, as highlighted in Figure 6c, there is the importance of the interaction between the secondary fuel and the stepwise oxidizer, and the importance of the primary / secondary fuel and oxidizer stepwise feeding. Primary and secondary fuels: In addition to helping reduce NOx emissions. In current designs, they also help adapt to changes in volumetric fuel flow when switching between NG and NG / H2 mixtures. Furthermore, the “secondary fuel” helps create a “pseudo” insulating blanket between the primary oxidizer and the stepwise oxidizer, which can be an oxygen purity of about 90-100%, potentially helping to reduce contact between the N2 present in the primary oxidizer and the high-concentration oxygen jet from the secondary oxidizer jet. It is considered important to spatially separate the oxygen / oxygen-enriched air port from the fuel port because the oxidizer stepwise feeding helps to slow down the mixing of fuel and oxidizer and achieve broad-range combustion, which helps reduce thermal NOx formation. Furthermore, the rate of the stepwise oxidizer is kept relatively high to help the oxygen / oxygen-enriched air jet contain reactor gases that help to lower local concentrations of oxygen, which helps to reduce thermal NOx emissions.

[0182] In general, the advantageous features of the present invention include, all of which correspond to other preferred embodiments of the first aspect. A burner of the first embodiment may be characterized by fuel flexibility (and, for example, allowing the use of NG, H2, or NG+H2 mixtures). This burner enables reliable starting in low-temperature furnaces (below the fuel autoignition temperature) using an air-fuel mode. A burner of the first embodiment may be characterized by its flexible operation (and, for example, being able to operate as an air-fuel or air-oxygen-fuel burner). Thus, the burner can be switched between an air-fuel ratio (holding mode) and an air-fuel ratio (melting mode) as needed, for example, due to the operational requirements of a reheating or secondary melting furnace, without significantly altering the burner's control system. The burner of the first embodiment may be characterized by not requiring water cooling. A burner of the first embodiment may be characterized by enabling, for example, maintaining NOx within environmental limits, in particular by low NOx design for both air-fuel and air-oxygen-fuel modes. A burner in the first embodiment may be characterized by its ability to maintain low CO levels in both air-fuel and air-oxygen-fuel modes. A burner in the first embodiment may be characterized by low back pressure of combustion air and oxygen, which eliminates the need for any secondary compression device. A burner of the first embodiment may be characterized by being able to operate in air-fuel mode when oxygen is unavailable, regardless of the average temperature of the furnace. A burner in a first embodiment may be characterized by the use of a single fuel, air, and secondary oxidizer flow for supplying fluid, which helps reduce the overall cost of skids, diverter valves, and / or any complex controller mechanisms. A burner of the first embodiment may be characterized by a turndown ratio of 1:30. The burner of the first embodiment facilitates the use of a lean, stable flame without flame blowout with high excess air (a low equivolute ratio of 0.25). A burner according to the first embodiment may be characterized by enabling stable and reliable ignition and combustion under low-temperature furnace conditions with a low equivalence ratio of 0.25. In certain embodiments of this specification, the burner of the first embodiment is characterized by low back pressure of the primary oxidizer and oxygen / oxygen-enriched airflow so as not to require a secondary compression device to increase the supply pressure.

[0183] A second aspect of the present invention provides a furnace equipped with a burner according to the first aspect of the present invention.

[0184] A preferred embodiment of the furnace of the present invention corresponds to the above-described embodiment of the burner of the present invention. Preferably, the furnace is further defined in accordance with any of the above embodiments of the burner, as described in relation to the first embodiment.

[0185] This includes embodiments relating to the above-mentioned advantages of the burner of the first embodiment, and also applies to each of the furnaces of the second embodiment as assumed herein.

[0186] In certain preferred embodiments, the furnace is selected from the group consisting of steam methane reforming furnaces, reheating furnaces in the steel industry, and secondary melting furnaces.

[0187] A third aspect of the present invention provides a method for operating a burner according to the first aspect and / or a furnace according to the second aspect.

[0188] The method is not particularly limited, as will be easily understood by those skilled in the art.

[0189] In certain embodiments, the method includes i) starting a burner; ii) ramping up the burner to firing speed; iii) starting a secondary fuel; iv) further ramping up the burner to the burner's firing speed; and v) optionally supplying a secondary oxide to the burner.

[0190] In a particular embodiment of the third aspect, step i) includes starting the main oxidizer, igniter, and primary fuel.

[0191] In general, further preferred embodiments of the method of the present invention correspond to the above-described embodiments of the burner of the present invention, and the burner used in the method is further defined by further product features. In other words, preferably, the method of the present invention is further defined in accordance with any of the above embodiments of the burner, as described in relation to the first aspect.

[0192] Furthermore, even more preferred embodiments of the method of the present invention include further method features based on any of the features described above in relation to the burner of the present invention.

[0193] Furthermore, the advantages of the present invention include the following, all of which correspond to further preferred embodiments of the third aspect. A third embodiment of the method may be characterized by fuel flexibility (and, for example, allowing the use of NG, H2, or NG+H2 mixtures). This enables reliable starting in low-temperature reactors, for example, using an air-fuel mode. A third embodiment of the method may be characterized by its flexible operation (and, for example, being able to operate as an air-fuel or air-oxygen-fuel burner). Thus, the method can be switched between an air-fuel ratio (holding mode) and an air-fuel ratio (melting mode) as needed, for example, depending on the operational requirements of a reheater or secondary melting furnace, without significantly altering the burner control system. The method of the third embodiment may be characterized by not requiring water cooling. A third embodiment of the method may be characterized by enabling, for example, maintaining NOx within environmental limits, and in particular, maintaining low NOx for both air-fuel and air-oxygen-fuel modes. The method of the third embodiment may be characterized in that the low back pressure of the combustion air and oxygen eliminates the need for any secondary compression device. The method of the third embodiment may be characterized by being able to be performed in air-fuel mode when oxygen is unavailable, regardless of the average temperature of the furnace. A third embodiment of the method may be characterized in that the use of a single fuel, air, and secondary oxide flow for supplying fluids helps to reduce the overall cost of skids, diverter valves, and / or any complex controller mechanisms.

[0194] Furthermore, generally speaking, any preferred embodiment of the second to fourth aspects of this specification corresponds to a preferred embodiment of the first aspect of this specification.

[0195] Generally, the articles “a” and “an” as used herein mean one or more when applied to any feature in embodiments of the invention described herein and in the claims. The use of “a” and “an” does not limit the meaning to a single feature unless such limitation is specifically stated. The article “the” preceding a singular or plural noun or noun phrase indicates a specific designated feature or a particular designated feature, and may have singular or plural implications depending on the context in which it is used. The adjective “any” means indiscriminately one, some, or all of any quantity.

[0196] Furthermore, where a particular embodiment is described in this specification by using the term “comprising” or such term, further embodiments are also assumed in this specification, and these are described by using the term “consisting of” or such term instead of the term “comprising” or such term.

[0197] Further specific embodiments The present invention also relates in particular to the following items.

[0198] Item 1: A burner (1) comprising a primary fuel conduit (20) having a primary fuel outlet (22) with a plurality of primary fuel outlet holes (23) for supplying primary fuel into an ignition chamber (25), wherein the wall surrounding the ignition chamber (25) comprises a primary fuel conduit (20) having a plurality of bleed holes (28), and a primary oxide conduit (30) for supplying a primary oxide, comprising an intermediate annular conduit (35) in the downstream portion (5) of the burner, wherein the first portion of the intermediate annular conduit (35) is connected to the ignition chamber via a plurality of bleed holes (28). A burner comprising: a main oxide conduit (30) introduced into a burner (25) and mixed with primary fuel, and configured to allow the splitting of the main oxide so that a second portion is optionally introduced into an oxide section (33); preferably, the burner further comprises a plurality of secondary oxide conduits (50) for supplying secondary oxides, in particular, a primary fuel conduit (20) surrounded by the main oxide conduit (30) and the plurality of secondary oxide conduits (50) at least in the downstream portion (5) of the burner (1).

[0199] Item 2. The burner according to Item 1, further comprising a secondary fuel conduit (40) for supplying secondary fuel, having a secondary fuel outlet (44) at its downstream end, wherein in at least the downstream portion (5) of the burner (1) where a primary fuel outlet (22), an ignition chamber (25), an intermediate annular conduit (35), and a secondary fuel outlet (44) are located, the primary fuel conduit (20) is surrounded by a main oxide conduit (30) and a secondary fuel conduit (40).

[0200] Item 3: The burner according to Item 1 or 2, wherein the burner further comprises a plurality of secondary oxide conduits (50) for supplying secondary oxides, and in particular, in the downstream portion (5) of the burner (1) further comprising a secondary oxidizer outlet (54), the primary fuel conduit (20) is surrounded by a main oxide conduit (30) and a secondary fuel conduit (40), and a plurality of secondary oxide conduits (50).

[0201] Item 4: A burner according to any one of the preceding items, wherein the burner (1) further comprises an ignition source (10), in particular the ignition source (10) terminating in an ignition chamber (25), in particular the ignition source (10) being a central ignition source having a central axis (15) and a conduit end plane (16), in particular the main axis (2) of the burner (1) coinciding with the central axis (15) of the ignition source (10), in particular the downstream portion (5) of the burner (1), the central ignition source (10) being surrounded by a primary fuel conduit (20), a main oxide conduit (30), and a secondary fuel conduit (40), and optionally a plurality of secondary oxide conduits (50).

[0202] Item 5: A burner according to any one of items 1 to 4, wherein the ignition chamber (25) is positioned within the primary fuel conduit (20), extends from the primary fuel outlet (22) to the primary fuel conduit end plane (24), the primary fuel conduit wall (29) surrounds the ignition chamber (25), and comprises a plurality of bleed holes (28).

[0203] Item 6 (see, for example, Figure 9A): A burner according to any one of items 1 to 4, wherein the ignition chamber (25) extends from a primary fuel outlet (22) to an intermediate annular conduit outlet plane (56), and the wall surrounding the ignition chamber (25) includes at least two (preferably two or three) steps of an annular conduit with increasing diameter, each of which step comprises a plurality of bleed holes (28).

[0204] Item 7 (see, for example, Figure 9B): The ignition chamber (25) extends from the primary fuel outlet (22) to the intermediate annular conduit outlet plane (56), and the wall surrounding the ignition chamber (25) comprises two sections: i) the first section extends from the primary fuel outlet (22) to the primary fuel conduit end plane (24), and the primary fuel conduit wall (29) surrounding the section comprises a plurality of bleed holes (28); and ii) the second section comprises the outer diameter of the primary fuel conduit (20). A burner according to any one of items 1 to 4, having an inner diameter larger than that of the first section, but the second section having an outer diameter smaller than the inner diameter of the intermediate annular conduit (35), and further comprising a plurality of bleed holes (28), and optionally further comprising: iii) an air purge plate (73) having a purge hole (32) extending between the outer diameter of the first section and the inner diameter of the second section; and iv) two mechanical mixer plates (74) each located adjacent to each other downstream of the two sections.

[0205] Item 8 (see, for example, Figure 9C): A burner according to any one of items 1 to 4, wherein the ignition chamber (25) extends from the primary fuel outlet (22) to the intermediate annular conduit outlet plane (56), and the wall surrounding the ignition chamber (25) comprises two sections: i) a first section having an outer diameter smaller than the inner diameter of the primary fuel conduit (20) and comprising a plurality of bleed holes (28); the main fuel conduit wall (29) surrounding the first section comprising a plurality of bleed holes (28); the first section further comprising means for allowing the main oxide to enter the ignition chamber (25) in the flow direction between two rings of the main fuel outlet hole; and ii) a second section having an inner diameter larger than the outer diameter of the primary fuel conduit (20), but the second section having an outer diameter smaller than the inner diameter of the intermediate annular conduit (35) and further comprising a plurality of bleed holes (28).

[0206] Item 9: A burner according to any one of the preceding items, wherein the ignition chamber (25) comprises an ignition cup (75) and an oxide bleed cup (76), preferably the ignition cup (75) is included in a first section of the ignition chamber (25), and the oxide bleed cup (76) is included in a second section of the ignition chamber (25), the second section being located downstream of the first section.

[0207] Item 10: i) The primary fuel conduit end plane (24) corresponds to the ignition chamber end plane (26), and / or ii) The primary fuel conduit further includes an air premixing port (27) upstream of the primary fuel outlet (22), and / or iii) The main oxidizer conduit (30) further comprises a purge hole (32) in the flow direction parallel to the main shaft (2) of the burner, and / or iv) The main oxide conduit (30) further comprises a swirl vane section (33), in particular an intermediate annular conduit (35) configured to allow the main oxide to be divided into two parts, the second part being introduced into the swirl vane section (33) and / or v) A burner according to any one of the preceding items, wherein the burner (1) further comprises a turbulence generator (47) in the secondary fuel conduit (40).

[0208] Item 11: A burner as described in any one of the above items, wherein the primary fuel conduit end plane (24) corresponds to the ignition chamber end plane (26).

[0209] Item 12: A burner according to any one of the preceding items, wherein the primary fuel conduit further comprises an air premixing port (27) upstream of the primary fuel outlet (22).

[0210] Item 13: A burner according to any one of the preceding items, wherein the main oxidizer conduit (30) further comprises a purge hole (32) in a flow direction parallel to the main shaft (2) of the burner.

[0211] Item 14: A burner according to any one of the preceding items, wherein the main oxide conduit (30) further comprises an oxide section (33) which is a swivel vane section (33), and in particular, an intermediate annular conduit (35) is configured to allow the main oxide to be divided into two parts, the second part of which is introduced into the swivel vane section (33).

[0212] Item 15: A burner according to any one of the preceding items, wherein the burner (1) further comprises a turbulence generator (47) in a secondary fuel conduit (40), and in particular the turbulence generator comprises one or more turbulence generator discs.

[0213] Item 16: i) The diameter of the primary fuel outlet hole (23) is defined as D0, and D0 / D2 is 0.04 to 0.5, and / or ii) The diameter of the purge hole (32) is defined as D1, and D1 / D2 is 0.04 to 0.5, and / or iii) The outer diameter of the ignition source (10) is defined as D2, the inner diameter of the primary fuel conduit (20) is defined as D3, and D3 / D2 is 1.5 to 4.5, in particular 2.0 to 3.0, and / or iv) The outer diameter of the ignition source (10) is defined as D2, the inner diameter of the main oxide conduit (30) is defined as D4, and D4 / D2 is 3.0 to 9.0, in particular 3.5 to 5.5, and / or v) The outer diameter of the ignition source (10) is defined as D2, the inner diameter of the secondary fuel conduit (40) is defined as D5, and D5 / D2 is 5.0 to 11.0, in particular 5.5 to 7.0, and / or vi) The outer diameter of the ignition source (10) is defined as D2, and the distance between the centers of the two secondary oxide conduits (50) located opposite each other with respect to the main shaft (2) of the burner is defined as D6, where D6 / D2 is 9.0 to 22.0, in particular 10.0 to 14.0, and / or vii) The inner diameter of the secondary fuel conduit (40) is defined as D5, and the distance between the centers of two secondary oxide conduits (50) located opposite each other with respect to the main shaft (2) of the burner is defined as D6, where D6 / D5 is 1.75 to 2.5, particularly 1.8 to 2.1, and / or viii) The diameter of the air premixing hole (27) is defined as P0, and P0 / D2 is 0.02 to 0.2, and / or ix) The inner diameter of the bleed hole (28) is defined as P1, and P1 / D2 is 0.05 to 0.4, and / or x) The distance between the primary fuel conduit end plane (24) and the intermediate annular conduit end plane (36) is defined as L1, and the distance between the primary fuel conduit wall (29) and the intermediate annular conduit wall (37) is defined as L4, and L1 / L4 is 0.5 to 2.5, in particular 1.0 to 2.0, and / or xi) The distance between the primary fuel conduit end plane (24) and the intermediate annular conduit end plane (36) is defined as L1, the distance between the intermediate annular conduit end plane (36) and the main oxide conduit end plane (38) is defined as L2, the inner diameter of the primary fuel conduit (20) is defined as D3, and (L1+L2) / D3 is 0.25~1.0, particularly 0.4~0.6, and / or xii) The distance between the main oxide conduit end plane (38) and the secondary fuel conduit end plane (46) is defined as L3, the inner diameter of the main oxide conduit (30) is defined as D4, and L3 / D4 is 0.05 to 0.25, particularly 0.1 to 0.2, and / or xiii) The distance between the primary fuel outlet (22) and the primary fuel conduit end plane (24) and / or the ignition chamber end plane (26) is defined as L0, the inner diameter of the primary fuel conduit (20) is defined as D3, and L0 / D3 is 0.25 to 1.0, in particular 0.4 to 0.6, and / or xiv) The distance between the centers of two rows of bleed holes (28) is defined as H, and the inner diameter of the bleed hole (28) is defined as P1, where H / P1 is 1.25 to 2.5 and / or xv) The angle defined by the burner's main shaft (2) and the centers of the two adjacent bleed holes (28) is defined as angle alpha, and angle alpha is between 3 and 30 degrees and / or xvi) The angle defined by the main shaft (2) of the burner and the centers of the two adjacent purge holes (32) is defined as angle beta, and angle beta is between 5 and 40 degrees and / or xvii) The angle defined by the center of the burner's main shaft (2) and two adjacent primary fuel outlet holes (23) is defined as the angle theta, and the angle theta is between 10 and 40 degrees and / or xviii) A burner as described in any one of the preceding items, wherein the angle defined by the center of the main axis (2) of the burner and the center of two adjacent secondary oxidizer conduits (50) is defined as the angle eta, and the angle eta is between 10 and 70 degrees, in particular between 40 and 60 degrees.

[0214] Item 17: A burner as described in any one of the above items, wherein the diameter of the primary fuel outlet hole (23) is defined as D0 / D2, and D0 is 0.04 to 0.5.

[0215] Item 18: A burner as described in any one of the above items, wherein the diameter of the purge hole (32) is defined as D1, and D1 / D2 is between 0.04 and 0.5.

[0216] Item 19: A burner as described in any one of the above items, wherein the outer diameter of the ignition source (10) is defined as D2, the inner diameter of the primary fuel conduit (20) is defined as D3, and D3 / D2 is between 1.5 and 4.5, in particular between 2.0 and 3.0.

[0217] Item 20: A burner as described in any one of the above items, wherein the outer diameter of the ignition source (10) is defined as D2, the inner diameter of the main oxide conduit (30) is defined as D4, and D4 / D2 is 3.0 to 9.0, in particular 3.5 to 5.5.

[0218] Item 21: A burner as described in any one of the above items, wherein the outer diameter of the ignition source (10) is defined as D2, the inner diameter of the secondary fuel conduit (40) is defined as D5, and D5 / D2 is between 5.0 and 11.0, in particular between 5.5 and 7.0.

[0219] Item 22: A burner as described in any one of the preceding items, wherein the outer diameter of the ignition source (10) is defined as D2, the distance between the centers of two secondary oxide conduits (50) located opposite each other with respect to the main shaft (2) of the burner is defined as D6, and D6 / D2 is between 9.0 and 22.0, in particular 10.0 and 14.0.

[0220] Item 23: A burner as described in any one of the above items, wherein the inner diameter of the secondary fuel conduit (40) is defined as D5, the distance between the centers of two secondary oxide conduits (50) located opposite each other with respect to the main shaft (2) of the burner is defined as D6, and D6 / D5 is 1.75 to 2.5, in particular 1.8 to 2.1.

[0221] Item 24: A burner as described in any of the above items, wherein the diameter of the air premixing hole (27) is defined as P0, and P0 / D2 is between 0.02 and 0.2.

[0222] Item 25: A burner as described in any one of the above items, wherein the inner diameter of the bleed hole (28) is defined as P1, and P1 / D2 is 0.05 to 0.4.

[0223] Item 26: A burner as described in any one of the above items, wherein the distance between the primary fuel conduit end plane (24) and the intermediate annular conduit end plane (36) is defined as L1, the distance between the primary fuel conduit wall (29) and the intermediate annular conduit wall (37) is defined as L4, and L1 / L4 is between 0.5 and 2.5, in particular between 1.0 and 2.0.

[0224] Item 27: A burner as described in any one of the above items, wherein the distance between the primary fuel conduit end plane (24) and the intermediate annular conduit end plane (36) is defined as L1, the distance between the intermediate annular conduit end plane (36) and the main oxidizer conduit end plane (38) is defined as L2, the inner diameter of the primary fuel conduit (20) is defined as D3, and (L1+L2) / D3 is 0.25 to 1.0, in particular 0.4 to 0.6.

[0225] Item 28: A burner as described in any one of the above items, wherein the distance between the main oxide conduit end plane (38) and the secondary fuel conduit end plane (46) is defined as L3, the inner diameter of the main oxide conduit (30) is defined as D4, and L3 / D4 is 0.05 to 0.25, in particular 0.1 to 0.2.

[0226] Item 29:) A burner as described in any one of the preceding items, wherein the distance between the primary fuel outlet (22) and the primary fuel conduit end plane (24) and / or the ignition chamber end plane (26) is defined as L0, the inner diameter of the primary fuel conduit (20) is defined as D3, and L0 / D3 is between 0.25 and 1.0, in particular between 0.4 and 0.6.

[0227] Item 30: A burner as described in any one of the above items, where the distance between the centers of two rows of bleed holes (28) is defined as H, the inner diameter of the bleed holes (28) is defined as P1, and H / P1 is between 1.25 and 2.5.

[0228] Item 31: A burner as described in any one of the preceding items, wherein the angle defined by the center of the burner's main shaft (2) and two adjacent bleed holes (28) is defined as angle alpha, and angle alpha is between 3 and 30 degrees.

[0229] Item 32: A burner as described in any one of the preceding items, wherein the angle defined by the center of the burner's main shaft (2) and two adjacent purge holes (32) is defined as angle beta, and angle beta is between 5 and 40 degrees.

[0230] Item 33: A burner as described in any one of the preceding items, wherein the angle defined by the center of the burner's main shaft (2) and two adjacent primary fuel outlet holes (23) is defined as the angle theta, and the angle theta is between 10 and 40 degrees.

[0231] Item 34: A burner as described in any one of the preceding items, wherein the angle defined by the center of the burner's main shaft (2) and two adjacent secondary oxidizer conduits (50) is defined as the angle eta, and the angle eta is between 10 and 70 degrees, in particular between 40 and 60 degrees.

[0232] Item 35: i) D3 / D2 is 1.5 to 4.5, especially 2.0 to 3.0, and / or ii) D4 / D2 is 3.0 to 9.0, especially 3.5 to 5.5, and / or iii) D5 / D2 is 5.0 to 11.0, especially 5.5 to 7.0, and / or iv) D6 / D2 is 9.0-22.0, especially 10.0-14.0, and / or v) A burner as described in any one of the above items 17-34, where D6 / D5 is 1.75-2.5, especially 1.8-2.1.

[0233] Item 36: i) L1 / L4 is 0.5 to 2.5, especially 1.0 to 2.0, and / or ii) L0 / D3 is 0.25 to 1.0, especially 0.4 to 0.6, and / or iii) (L1+L2) / D3 is 0.25 to 1.0, in particular 0.4 to 0.6, and / or iv) L3 / D4 is 0.05 to 0.25, especially 0.1 to 0.2, and / or v) A burner as described in any one of the above items 11 to 29, wherein H / P1 is 1.25 to 2.5.

[0234] Item 37: i) Angle alpha is between 3 and 30 degrees, and / or ii) The angle beta is between 5 and 40 degrees, and / or iii) The angle theta is between 10 and 40 degrees, and / or iv) A burner as described in any one of the preceding items 17-36, wherein the angle emission is 10-70 degrees, in particular 40-60 degrees.

[0235] Item 38: Burner (1) at the outlet of a given conduit, i) The velocity of the primary fuel (preferably at the outlet of hole 23) is 30 feet / second to 500 feet / second, particularly 40 feet / second to 400 feet / second, and / or ii) The rate of the main oxidizer is 5 feet / second to 300 feet / second, particularly 10 feet / second to 200 feet / second, and / or iii) The speed of the secondary fuel is 20 feet / second to 200 feet / second, particularly 40 feet / second to 120 feet / second, and / or iv) A burner as described in any one of the preceding items, optionally configured such that the rate of the secondary oxidizer is 50 feet / second to 500 feet / second, in particular 100 feet / second to 300 feet / second.

[0236] Item 39: A burner as described in any of the preceding items, wherein the primary fuel velocity is between 30 feet / second and 500 feet / second, and especially between 40 feet / second and 400 feet / second.

[0237] Item 40: A burner as described in any of the preceding items, wherein the rate of the main oxidizer is 5 feet / second to 300 feet / second, and in particular 10 feet / second to 200 feet / second.

[0238] Item 41: A burner as described in any of the preceding items, wherein the secondary fuel velocity is between 20 feet / second and 200 feet / second, and especially between 40 feet / second and 120 feet / second.

[0239] Item 42: A burner as described in any of the preceding items, wherein the rate of secondary oxidation is 50 feet / second to 500 feet / second, in particular 100 feet / second to 300 feet / second.

[0240] Item 43: A burner as described in any one of the preceding items, wherein the swivel angle is 5 to 60 degrees, preferably 30 to 45 degrees.

[0241] Item 44: Burner (1) i) During startup, approximately 100% of the burner's total heat output is supplied by the primary fuel, and / or ii) A burner as described in any one of the preceding items, which is operated in such a manner that during normal operation, approximately 25 to 65%, preferably 45 to 65%, of the total heat value of the burner is supplied by the primary fuel, and the remainder is supplied by the secondary fuel.

[0242] Item 45: Burner (1) is a burner as described in any one of the preceding items, configured such that during startup, approximately 100% of the burner's total thermal output is supplied by the primary fuel.

[0243] Item 46: A burner according to any one of the preceding items, wherein during normal operation, approximately 25–65%, preferably 45–65%, of the total heat output of the burner is supplied by a primary fuel.

[0244] Item 47: A burner as described in either Item 45 or 46, wherein the remainder is supplied by secondary fuel.

[0245] Item 48: Burner (1) i) The volumetric flow rate of the ignition chamber oxidizer is approximately 5-25% of the total main oxidizer flow rate, and / or ii) The volumetric flow rate of the premixed oxidizer is approximately 2-10% of the total main oxidizer flow rate, and / or iii) A burner as described in any one of the above items, configured such that the volumetric flow rate of the oxidizer diverted to the secondary oxidizer conduit (50) is approximately 2-5% of the main oxidizer flow rate.

[0246] Item 49: Burner (1) is a burner as described in any one of the above items, configured such that the volumetric flow rate of the ignition chamber oxidizer is approximately 5-25% of the total main oxidizer flow rate.

[0247] Item 50: A burner (1) as described in any one of the above items, configured such that the volumetric flow rate of the premixed oxidizer is approximately 2-10% of the total main oxidizer flow rate.

[0248] Item 51: A burner according to any one of the above items, wherein the burner (1) is configured such that the volume flow rate of the secondary oxidizer diverted to the secondary oxidizer conduit (50) is approximately 2-5% of the main oxidizer flow rate.

[0249] Item 52: Burner (1) is a burner as described in any one of the preceding items, configured to allow the burner to turn down from 100% design firing rate to approximately 1:30 turndown during normal operation, depending on the operating requirements.

[0250] Item 53: A burner (1) as described in any one of the preceding items, wherein the central ignition source (10) forms the “pipe 1” of the burner.

[0251] A burner (1) as described in any of the preceding items, wherein item 54, the primary fuel conduit (20), forms the “pipe 2” of the burner.

[0252] Item 55: A burner (1) as described in any one of the preceding items, wherein the main oxidizer conduit (30) forms a “pipe 3” of the burner, in particular an air pipe.

[0253] Item 56: A burner (1) as described in any of the preceding items, wherein a secondary fuel conduit (40) forms the “pipe 4” of the burner.

[0254] Item 57: A burner (1) as described in any one of the above items, wherein the secondary oxidizer conduit (50) is designated as either a "stepwise oxidizer conduit" or a "stepwise oxidizer".

[0255] Item 58: A burner (1) described in any of the above items, in which all conduits except for the secondary oxidized conduit (50) share a common central axis.

[0256] Item 59: A burner (1) as described in any one of the preceding items, wherein all conduits except for the secondary oxidizer conduit (50) are arranged concentrically around a common longitudinal axis in at least the downstream portion (5).

[0257] Item 60: The burner (1) according to any one of the preceding items, wherein all of the conduits are essentially straight.

[0258] Item 61: The burner (1) according to any one of the preceding items, wherein the burner (1) comprises a configuration essentially as shown in any one of the accompanying drawings or any combination thereof.

[0259] Item 62: A furnace comprising the burner (1) according to any one of items 1 to 61.

[0260] Item 63: The furnace according to item 62, wherein the furnace is selected from the group consisting of a steam methane reforming furnace, a reheating furnace in the iron and steel industry, and a secondary melting furnace.

[0261] Item 64: The furnace according to item 63, wherein the furnace is further characterized by any feature described in any one of items 1 to 61.

[0262] Item 65: A method for operating a burner (1) according to any one of items 1 to 61, or a method for operating a furnace according to any one of items 62 to 64, comprising: i) starting the burner; ii) optionally, ramping up the burner to a firing rate; iii) initiating secondary fuel; iv) ramping up the burner to the burner's firing rate; and v) optionally, supplying a secondary oxidant to the burner.

[0263] Item 66: The method according to item 65, wherein step i) comprises initiating a primary oxidant, an igniter, and a primary fuel. Examples

[0264] The following examples are used to further illustrate aspects of the present invention, but are not intended to be limiting in any way.

[0265] Example 1

[0266] The test burner was manufactured and tested in our industrial-scale combustion chamber at 5 MMB tu / hr using NG as the primary and secondary fuel, air as the primary oxidizer, and oxygen as the secondary oxidizer.

[0267] The burner was successfully tested in starting, ramp-up, air-fuel, and air-oxygen-fuel modes. The burner performed well, demonstrating its ability to produce a stable flame in both air-fuel and air-oxygen-fuel modes without external support.

[0268] The plot in Figure 8 shows a comparison of normalized NOx data from laboratory tests of the present invention with prior art (Figure 12). The normalized NOx value is defined as the ratio of NOx (ppm) generated by the burner type to the maximum NOx (ppm) generated from different burners. Here, in this embodiment, the NOx data is normalized by the NOx generated by the drilling technique because it generated the maximum NOx (ppm). The total ignition rate, burner equivalent ratio, and fuel composition of the burners are the same for both burners.

[0269] The results show that NOx emissions from the present invention are approximately 30% to 70% lower (depending on the oxygen enrichment level of the burner) compared to the prior art (no oxygen step supply and 75% oxygen step supply). CO emissions under these test conditions remained below 20 ppm in the exhaust flue.

[0270] The fact that this invention can produce significantly lower NOx in both air-fuel and air-oxygen-fuel modes is due to several unique features of this burner.

[0271] In air-fuel mode, the bleed hole (28) provides air in the igniton cup that can be coupled by the fuel jet before the fuel leaves the burner outlet plane, thus providing the burner with improved performance in terms of NOx emissions. This enhanced mixture, due to the unique burner cup tip (ignition chamber) design, can allow for a reduction in peak temperature compared to the common characteristics of unpremixed burners. The lower peak temperature of this burner flame mimics the peak temperature of partially premixed air-fuel combustion rather than unpremixed combustion.

[0272] In air-oxygen-fuel mode, the burner developed a stable flame while producing lower NOx compared to prior technologies.

[0273] The three fluids, air, fuel, and oxygen / oxygen-enriched air, are supplied through spatially separated, different outlets / ports, thereby simultaneously reducing the interaction of O2, N2, and high temperatures at local levels. Firstly, the central region of the burner operates in a fuel-rich environment, which can lower the peak temperature compared to stoichiometric combustion with an air-fuel ratio of 1. Secondly, the bleed hole (28) provides air in the ignition cup, which can be drawn in by the fuel jet before the fuel leaves the burner outlet plane. As discussed above, this enhanced mixture through the unique burner cup tip (ignition chamber) design allows for a reduction in peak temperature compared to an unpremixed burner. Lower peak temperatures help reduce thermal NOx formation.

[0274] In addition, the radial separation position of the oxygen injection nozzle from the central flame is crucial to minimizing thermal NOx formation. Firstly, radial separation of the oxidizer jet from the secondary fuel outlet allows for delayed mixing of the central fuel flame with the secondary oxidizer, enabling distributed combustion. Thermal NOx formation is primarily influenced by temperature, nitrogen concentration, and oxygen concentration. Delayed mixing allows for dispersed combustion, which lowers the peak combustion temperature. Furthermore, the feature of mixing in furnace gas to dilute the secondary oxidizer flow helps to reduce local oxygen concentrations before these high-oxygen-concentration jets reach the fuel and / or partially burned fuel / air mixture. Thus, the burner's tendency to form thermal NOx is reduced.

[0275] Finally, turbulence-induced injection of secondary fuel between the primary oxidizer (air) and secondary oxidizer allows for the creation of a "pseudo" insulating blanket of partially burned fuel between the primary and secondary oxidizers (near the burner outlet), which, in high-temperature air, potentially helps reduce contact between the N2 present in the primary oxidizer and the high-concentration O2 jet from the secondary oxidizer jet.

[0276] In air-fuel mode, the burner can produce a stable flame with a high turndown of 1:30 and an equivalence ratio of 0.25. This performance is due to the unique configuration of the burner hardware, including the position of the air purge plate (73), its stepped design, and the fact that air is allowed to flow axially over the air purge plate (73) to provide a robust flame fixing location. The burner provides multiple flame fixing locations based on the total firing velocity of the burner, as illustrated in Figure 11. In air-fuel mode, the flame is fixed in two locations: one near the air purge plate (73) and a second on the inner wall surrounding the swivel blade exit plane. In air-oxygen-fuel mode (higher oxygen enrichment levels) and in air-fuel mode under turndown conditions and a low equivalence ratio, a recirculation zone is established in the area created by the stepped design of the air purge plate (73), so the flame continues to be fixed in the location of the air purge plate (73) without blow-off. Furthermore, the air purge plate (73) is recessed by L1 from the swivel blade outlet plane (34), thereby ensuring that flame fixing is relatively unaffected by the furnace atmosphere.

[0277] A design feature allows for the radial and axial purging of the oxidizer within the ignition cup, keeping the surrounding walls cool by protecting it from direct contact with the flame.

[0278] The robust flame fixing mechanism of this burner, as described above, provides the burner operation with the additional advantage of being able to operate from air-fuel to air-oxygen-fuel mode without changing the burner. The stable fixing position allows for an increased proportion of oxygen supplied by the secondary oxidizer while maintaining a stable flame in the center without lift-off. The oxygen supplied by the secondary oxidizer can reach 90% of the total oxygen required for the stoichiometric combustion of the fuel. If the furnace is above the fuel's autoignition temperature, the burner can operate in full oxygen-fuel mode if necessary.

[0279] In the present invention, the two fuel supply conduits with unique injection technology (one conduit has a plurality of fuel jets, and the second conduit has the tip of a turbulence generator, and the aforementioned characteristics of the ignition cup) develop robust flame anchoring and provide fuel flexibility to the burner. For the same heat input of the burner, as the hydrogen fraction of the fuel in natural gas increases, the higher volumetric flow rate of hydrogen (heating value of hydrogen ~330 Btu / scf) required to match the heat input of NG (heating value of NG ~1000 Btu / scf) increases the fuel velocity. This increased velocity may cause flame lift-off or affect the heat release rate of the burner. In the novel burner, the flame anchoring site helps to generate a stable flame in the center. This stable flame in the center acts as a pilot flame for the fuel supplied by the secondary fuel conduit. As a result, the current burner can produce a stable flame with NG and / or NG / H₂ mixtures.

[0280] Finally, the burner ignites sufficiently at an equivalence ratio as low as 0.25. This allows the burner to be started / ignited at a low equivalence ratio (fuel-lean startup). This is enabled by the unique design of the ignition cup. The ignition cup provides a zone where ignition can be initiated and sustained while being below the lower flammability limit of natural gas for the global burner. A portion of the main oxidant is introduced into the ignition chamber through the peripheral wall of the chamber which is perpendicular to the fuel distribution nozzle. This helps to actively mix the fuel and the "ignition" air to enable reliable and repeated generation of a gas mixture having a fuel concentration within the flammable range.

[0281] Example 2

[0282] In the following example, as also shown in Figure 7, a non-limiting exemplary detailed method of operating the burner (1) of the present invention according to the present invention is described.

[0283] Step 1: start the main oxidant (which also allows air to pass through the cup), start the igniter located in the center of the burner, and initiate the primary fuel. This ignites the primary flame

[0284] Step 2: Once the flame is lit, the burner is lit at a firing rate up to a certain MMBtu / hr. At this point, the secondary fuel is started. Because the secondary fuel outlet port is located close to the primary fuel flame, the secondary fuel is ignited by the energy supplied by the combustion of the primary fuel.

[0285] Step 3: The burner's rate of fire is increased until it reaches the burner's rate of fire.

[0286] Step 4: If required by the process, the secondary oxide can be supplied to the burner.

Claims

1. Burner (1), A primary fuel conduit (20) having a primary fuel outlet (22) with a plurality of primary fuel outlet holes (23) for supplying primary fuel into an ignition chamber (25), wherein the wall surrounding the ignition chamber (25) has a plurality of bleed holes (28), and the primary fuel conduit (20) A main oxide conduit (30) for supplying the main oxide, comprising an intermediate annular conduit (35) in the downstream portion (5) of the burner, wherein the intermediate annular conduit (35) is configured to allow the main oxide to be divided such that a first portion is introduced into the ignition chamber (25) via the plurality of bleed holes (28) and mixed with the primary fuel, and a second portion is introduced into the oxide section (33), The burner further comprises a plurality of secondary oxide conduits (50) for supplying secondary oxides, In particular, the burner (1) wherein, at least in the downstream portion (5) of the burner (1), the primary fuel conduit (20) is surrounded by the main oxide conduit (30) and the plurality of secondary oxide conduits (50).

2. The burner further comprises a secondary fuel conduit (40) for supplying secondary fuel, having a secondary fuel outlet (44) at its downstream end. The burner according to claim 1, wherein in at least the downstream portion (5) of the burner (1) where a primary fuel outlet (22), an ignition chamber (25), an intermediate annular conduit (35), and a secondary fuel outlet (44) are located, the primary fuel conduit (20) is surrounded by the main oxidizer conduit (30) and the secondary fuel conduit (40).

3. The burner according to claim 2, wherein in at least the downstream portion (5) of the burner (1), the primary fuel conduit (20) is surrounded by the main oxide conduit (30), the secondary fuel conduit (40), and the plurality of secondary oxide conduits (50).

4. The burner according to any one of claims 1 to 3, wherein the ignition chamber (25) is positioned within the primary fuel conduit (20), extends from the primary fuel outlet (22) to the primary fuel conduit end plane (24), the primary fuel conduit wall (29) surrounds the ignition chamber (25), and comprises a plurality of bleed holes (28).

5. The burner according to any one of claims 1 to 3, wherein the ignition chamber (25) extends from the primary fuel outlet (22) to the intermediate annular conduit outlet plane (56), and the wall surrounding the ignition chamber (25) includes at least two (preferably two or three) steps of an annular conduit with increasing diameter, each of which step comprises a plurality of bleed holes (28).

6. The ignition chamber (25) extends from the primary fuel outlet (22) to the intermediate annular conduit outlet plane (56), and the wall surrounding the ignition chamber (25) comprises two sections. i) The first section extends from the primary fuel outlet (22) to the primary fuel conduit end plane (24), and the primary fuel conduit wall (29) surrounding the section is provided with a plurality of bleed holes (28), ii) The second section has an inner diameter larger than the outer diameter of the primary fuel conduit (20), but the second section has an outer diameter smaller than the inner diameter of the intermediate annular conduit (35), and further comprises a plurality of bleed holes (28), iii) The burner optionally further comprises an air purge plate (73) having a purge hole (32) extending between the outer diameter of the first section and the inner diameter of the second section, iv) The burner optionally further comprises two mechanical mixer plates (74) adjacent to each other, each downstream of the two sections, v) The burner according to any one of claims 1 to 3, wherein the burner optionally further comprises a purge plate (73) having a purge hole (32) located between the outer diameter of the second section and the inner diameter of the intermediate annular conduit (35).

7. The ignition chamber (25) extends from the primary fuel outlet (22) to the intermediate annular conduit outlet plane (56), and the wall surrounding the ignition chamber (25) comprises two sections. i) The first section has an outer diameter smaller than the inner diameter of the primary fuel conduit (20) and comprises a plurality of bleed holes (28), the primary fuel conduit wall (29) surrounding the first section comprises a plurality of bleed holes (28), and the first section further comprises means that allow the main oxide to flow additionally into the ignition chamber (25) between the two rings of the primary fuel outlet hole. ii) The second section has an inner diameter larger than the outer diameter of the primary fuel conduit (20), but the second section has an outer diameter smaller than the inner diameter of the intermediate annular conduit (35), and further comprises a plurality of bleed holes (28), iii) The burner optionally further comprises a purge plate (73) having a purge hole (32) located between the outer diameter of the first section and the inner diameter of the second section, iv) The burner according to any one of claims 1 to 3, further comprising optionally a purge plate (73) having a purge hole (32) located between the outer diameter of the second section and the inner diameter of the intermediate annular conduit (35).

8. The ignition chamber (25) comprises an ignition cup (75) and an oxide bleed cup (76), Preferably, the burner according to any one of the prior claims, wherein the ignition cup (75) is included in a first section of the ignition chamber (25), and the oxide bleed cup (76) is included in a second section of the ignition chamber (25), the second section being located downstream of the first section.

9. The burner (1) further comprises an ignition source (10), In particular, the ignition source (10) terminates within the ignition chamber (25), In particular, the ignition source (10) is a central ignition source having a central axis (15) and a conduit end plane (16), In particular, the main shaft (2) of the burner (1) coincides with the central shaft (15) of the ignition source (10), In particular, the burner according to any one of the prior claims, wherein in the downstream portion (5) of the burner (1), the central spark igniter (10) is surrounded by the primary fuel conduit (20), the main oxide conduit (30), the secondary fuel conduit (40), and the plurality of secondary oxide conduits (50).

10. i) The primary fuel conduit end plane (24) corresponds to the ignition chamber end plane (26) and / or ii) The primary fuel conduit further comprises an air premixing hole (27) upstream of the primary fuel outlet (22), and / or iii) The burner according to any one of the prior claims, wherein the main oxidizer conduit (30) further comprises a purge hole (32) in a flow direction parallel to the main shaft (2) of the burner.

11. i) The oxidized section (33) is a swivel vane section (33), and in particular, the intermediate annular conduit (35) is configured to allow the main oxidized material to be divided into two parts, the second part being introduced into the swivel vane section (33), and / or ii) the burner according to any one of the prior claims, wherein the burner (1) further comprises a turbulence generator (47) in the secondary fuel conduit (40).

12. i) The diameter of the primary fuel outlet hole (23) is defined as D0, and D0 / D2 is 0.04 to 0.5, and / or ii) The diameter of the purge hole (32) is defined as D1, and D1 / D2 is 0.04 to 0.5 and / or iii) The outer diameter of the ignition source (10) is defined as D2, the inner diameter of the primary fuel conduit (20) is defined as D3, and D3 / D2 is 1.5 to 4.5, particularly 2.0 to 3.0, and / or iv) The outer diameter of the ignition source (10) is defined as D2, the inner diameter of the main oxide conduit (30) is defined as D4, and D4 / D2 is 3.0 to 9.0, particularly 3.5 to 5.5, and / or v) The outer diameter of the ignition source (10) is defined as D2, the inner diameter of the secondary fuel conduit (40) is defined as D5, and D5 / D2 is 5.0 to 11.0, particularly 5.5 to 7.0, and / or vi) The outer diameter of the ignition source (10) is defined as D2, and the distance between the centers of two secondary oxide conduits (50) located opposite each other with respect to the main shaft (2) of the burner is defined as D6, where D6 / D2 is between 9.0 and 22.0, particularly between 10.0 and 14.0, and / or vii) The inner diameter of the secondary fuel conduit (40) is defined as D5, and the distance between the centers of two secondary oxide conduits (50) located on opposite sides of the main shaft (2) of the burner is defined as D6, where D6 / D5 is 1.75 to 2.5, particularly 1.8 to 2.1, and / or viiii) The diameter of the air premixing hole (27) is defined as P0, and P0 / D2 is 0.02 to 0.2, and / or ix) The inner diameter of the bleed hole (28) is defined as P1, and P1 / D2 is 0.05 to 0.4, and / or x) The distance between the primary fuel conduit end plane (24) and the intermediate annular conduit end plane (36) is defined as L1, the distance between the primary fuel conduit wall (29) and the intermediate annular conduit wall (37) is defined as L4, and L1 / L4 is 0.5 to 2.5, particularly 1.0 to 2.0, and / or xi) The distance between the primary fuel conduit end plane (24) and the intermediate annular conduit end plane (36) is defined as L1, the distance between the intermediate annular conduit end plane (36) and the main oxide conduit end plane (38) is defined as L2, the inner diameter of the primary fuel conduit (20) is defined as D3, and (L1 + L2) / D3 is 0.25 to 1.0, particularly 0.4 to 0.6, and / or xi) The distance between the main oxide conduit end plane (38) and the secondary fuel conduit end plane (46) is defined as L3, the inner diameter of the main oxide conduit (30) is defined as D4, and L3 / D4 is 0.05 to 0.25, particularly 0.1 to 0.2, and / or xiiii) The distance between the primary fuel outlet (22) and the primary fuel conduit end plane (24) and / or the ignition chamber end plane (26) is defined as L0, the inner diameter of the primary fuel conduit (20) is defined as D3, and L0 / D3 is 0.25 to 1.0, particularly 0.4 to 0.6, and / or xiv) The distance between the centers of two rows of bleed holes (28) is defined as H, and the inner diameter of the bleed holes (28) is defined as P1, where H / P1 is between 1.25 and 2.5 and / or xv) The burner according to any one of the prior claims, wherein the inner diameter of the secondary oxide conduit (50) is defined as D7, and D7 / D2 is 0.15 to 1.0, particularly 0.25 to 0.

75.

13. i) The ratio of the area of ​​all bleed holes in a single row to the surface area of ​​the cylinder with height, P1 and bore diameter, D2 is between 10% and 55%, and / or ii) The purge air plate (73) has a porosity limited to 2% to 15% (defined as the total open area on the plate that allows air to flow divided by the cross-sectional area of ​​the plate), and / or iii) The first fuel outlet plate (72) has a porosity in the range of 2% to 25% (defined by dividing the total open area on the plate that allows fuel to flow by the cross-sectional area of ​​the plate). iv) The burner according to any one of the prior claims, wherein the angle defined by the center of the main shaft (2) of the burner and the center of the two adjacent secondary oxide conduits (50) is defined as the angle eta, and the angle eta is between 10 and 70 degrees, in particular between 40 and 60 degrees.

14. The burner (1) is located at the outlet of a given conduit. i) The speed of the primary fuel is 30 feet / second to 500 feet / second, particularly 40 feet / second to 400 feet / second, and / or ii) The velocity of the main oxidizer is 5 feet / second to 300 feet / second, particularly 10 feet / second to 200 feet / second, and / or iii) The speed of the secondary fuel is 20 feet / second to 200 feet / second, particularly 40 feet / second to 120 feet / second, and / or iv) The burner according to any one of the prior claims, configured such that the rate of the secondary oxidizer is 50 feet / second to 500 feet / second, particularly 100 feet / second to 300 feet / second.

15. A burner according to any one of the prior claims, wherein the swivel angle is 5 to 60 degrees, preferably 30 to 45 degrees.

16. The aforementioned burner (1) is i) During startup, approximately 100% of the total heat output of the burner is supplied by the primary fuel, and / or ii) The burner (1) according to any one of the prior claims, which is operated such that during normal operation, about 25 to 65%, preferably 45 to 65%, of the total thermal output of the burner is supplied by the primary fuel, and the remainder is supplied by the secondary fuel.

17. The aforementioned burner (1) is i) The volumetric flow rate of the oxidizer in the ignition chamber is approximately 5 to 25% of the total main oxidizer flow rate, and / or ii) The volumetric flow rate of the premixed oxidizer is about 2 to 10% of the total main oxidizer flow rate, and / or iii) The burner according to any one of the prior claims, which is operated such that the volume flow rate of the oxidizer diverted to the secondary oxidizer conduit (50) is about 2 to 5% of the main oxidizer flow rate.

18. The burner (1) according to any one of the prior claims, wherein the burner (1) is operated in such a manner that, during normal operation, the burner can be turned down from 100% of its design firing rate to approximately 1:30 turndown, depending on the operating requirements.

19. A method for operating the burner (1) according to any one of claims 1 to 13, i) The step of starting the burner, ii) A step of ramping up the burner at the firing speed, iii) The step of starting the secondary fuel, iv) The step of further ramping up the burner to the firing speed of the burner, v) A method comprising the optional step of supplying the secondary oxide to the burner.

20. The method according to claim 19, wherein step i) includes starting the main oxidizer, the ignition source, and the primary fuel.

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