Dual fuel burner and method of operation

Abstract

The present invention relates to particular combustors, and e.g., to a combustor comprising a central primary fuel lance, a pilot fuel conduit, a primary oxidant conduit, a secondary oxidant conduit, and optionally a secondary fuel conduit, which are arranged in a particular and advantageous manner so as to surround each other at least in their downstream sections. The invention also relates to a furnace comprising the burner and a method of operating the burner. The burner according to the invention provides, in particular, a particularly advantageous way that comprises a pilot burner as part of the main burner in order to ignite a liquid fuel flame in a cold furnace. If desired, the pilot flame may help extend the flammability limit or operating range of the liquid fuel burner.

Description

[0001] Cross-reference to related applications This application claims priority to U.S. nonprovisional application 18 / 233,367, filed August 14, 2023, which is incorporated herein by reference. Technical Field

[0002] The present invention relates to burners, and more particularly to industrial burners configured to use at least liquid fuel and employing an ignition burner. Background Technology

[0003] The present invention relates to burners that can be used in applications involving the combustion of at least liquid fuels, and particularly to burners for industrial applications.

[0004] Igniting liquid fuel in a cold furnace during burner operation is often a challenge.

[0005] In the prior art, an ignition burner is typically used to ignite liquid fuels. Such an ignition burner is a separate burner that ignites the liquid fuel from one side. However, using an external ignition burner can lead to asymmetric effects in the flame, which may result in uneven heat flux, flame impingement on the sidewalls, or, in the worst case, flame extinguishing when the ignition fuel is turned off.

[0006] In other instances in this field, the furnace is first heated using a separate burner that burns gaseous fuel to reach the auto-ignition temperature of the liquid fuel burner before the liquid fuel supply is started. However, this results in increased overall cost of the burner and associated equipment, increased start-up time, and so on.

[0007] Therefore, the first object of the present invention is to provide an advantageous burner that mitigates or overcomes the above-mentioned problems.

[0008] Another challenge with industrial burners is that combustion often needs to be completed within a small space, especially when using small furnaces, such as in steam methane reforming. It is important that the flame length be shorter than the furnace length. However, when using nearly identical burners, liquid fuels typically have longer flame lengths than gaseous fuels. There are several reasons for this, but two are paramount: First, liquid fuels typically need to be atomized before the fuel droplets can mix with the oxidizer / air and burn to produce a stable flame. Second, liquid fuels often have a high volume fraction of aromatic compounds and high molecular weight fuels, which produce soot, and the soot produced by burning or fully oxidizing them over a short distance is challenging.

[0009] Therefore, another object of the present invention is to provide a burner that meets this challenge.

[0010] The specific existing technology design of the burner can be summarized as follows: US20070172784 (see US7901204B2) describes a dual burner for liquid and gaseous fuels, but does not discuss the mechanism for starting the burner operation using liquid fuel, nor does it provide details about the corresponding ignition burner.

[0011] US20120315586 (see US889996) describes a dual-fuel burner method and staged combustion, but makes no mention of an ignition burner as part of the main burner, nor of burning, for example, low-Btu gaseous fuels. Furthermore, the liquid fuel is preheated (flashed), while our burner does not require any preheated liquid fuel.

[0012] US20180216828A1 (see US889996) describes a dual-fuel premixed burner for gaseous and liquid fuels, but makes no mention of an ignition burner.

[0013] US20040234912 (see US6951454) describes a dual-fuel burner for pulverized coal and natural gas that produces a short flame and low emissions, but it does not include liquid fuels and does not mention an integrated ignition burner port.

[0014] US4748919A claims protection for a multi-fuel burner in which solid fuel is in a central conduit, a liquid nozzle is in a first conduit, a second conduit is for another fuel, and air is in an external conduit. It uses a known type of igniter assembly in the burner, which still requires an external ignition assembly. More specifically, when using a liquid nozzle, the igniter originates from a side port. Summary of the Invention

[0015] In general, the present invention relates to the subject matter as defined in the claims.

[0016] This invention is specifically based on the discovery that the objectives described above can be achieved by integrating the ignition burner into the main burner. Therefore, according to the specific features of this burner, the main fuel conduit is surrounded by the ignition fuel conduit.

[0017] Specifically, the present invention provides a burner comprising: a central main fuel nozzle for supplying atomized liquid fuel, the central main fuel nozzle having a main fuel outlet at its downstream end; a main oxidizer conduit for supplying main oxidizer, the main oxidizer conduit having a main oxidizer outlet at its downstream end; an ignition fuel conduit for supplying gaseous ignition fuel, the ignition fuel conduit having an ignition fuel outlet at its downstream end; and an auxiliary oxidizer conduit for supplying auxiliary oxidizer, the auxiliary oxidizer conduit having an auxiliary oxidizer outlet at its downstream end, wherein at least a main fuel outlet and a main oxidizer outlet are present therein. In the downstream portion of the burner with igniter outlet, ignition fuel outlet, and auxiliary oxidizer outlet, the ignition fuel conduit, auxiliary oxidizer conduit, and main oxidizer conduit are concentrically arranged around a central main fuel nozzle, such that the central main fuel nozzle is surrounded by the ignition fuel conduit, auxiliary oxidizer conduit, and main oxidizer conduit. At least in the downstream portion of the burner, the central main fuel nozzle, ignition fuel conduit, and auxiliary oxidizer conduit are surrounded by the main oxidizer conduit, and the component for igniting the ignition fuel is located inside the ignition fuel conduit and / or the auxiliary oxidizer conduit, upstream of the main fuel outlet. Variations and embodiments of the burner of the present invention are disclosed in detail below.

[0018] Generally, the burner of the present invention can be used in any application, such as applications requiring high heating, such as steam methane reforming, reheating furnaces in the steel industry, and secondary smelting furnaces.

[0019] As will be readily understood by those skilled in the art, the burner of the present invention advantageously relates to the use of an ignition fuel conduit and an auxiliary oxidizer conduit as a specific ignition burner, which is an integral part of the (main) burner itself. The auxiliary oxidizer conduit can also be used to provide (additional) oxidizer to the main fuel, such as a liquid fuel.

[0020] The present invention also provides, in particular, a furnace including the burner of the present invention and a method for operating the burner.

[0021] The burner of the present invention is designed to advantageously initiate burner operation by using a specific design of the ignition burner, which is an integral part of the burner. This allows for reliable and reproducible ignition of the main fuel (liquid fuel) in a symmetrical and stable manner, and also allows for combustion over a relatively short length, thus overcoming the prior art problems described above. Specifically, the ignition gas fuel generates a small flame near the main fuel lance (such as an oil lance) during startup, which helps to reliably and safely ignite the air-atomized liquid fuel, even in a cold furnace. Furthermore, the ignition gas fuel can advantageously be shut off after the liquid fuel flame has been ignited.

[0022] Furthermore, if needed, the ignition burner associated with the burner of this invention can also assist in the very low turndown ratio of liquid fuel lance operation by providing a continuous ignition source. This enables a wider operating range for liquid fuel combustion.

[0023] Furthermore, according to specific embodiments of the invention, in particular the combination of the low discharge velocity of the liquid fuel and the size characteristics of the (swirling) air, as well as the presence of a low-velocity auxiliary oxidant (e.g., ignition air) near the liquid fuel nozzle, helps to anchor the liquid fuel flame in a cold furnace while also producing a short flame across a wider range of tuned ratios, thereby overcoming the prior art problems described above.

[0024] Furthermore, the burner can operate in a cold furnace (i.e., at an average temperature <400 F during the burner's start-up sequence) without oxygen assistance or a continuous ignition source. The burner can also operate stably in lean fuel, low flame temperature modes. The burner produces a stable flame (without any flaring) over a wide range of equivalence ratios, even as low as 0.25. These characteristics enable controlled preheating of the process furnace, allowing the process to start up and reach steady-state conditions within the timeframe dominated by process requirements. The equivalence ratio is defined as the ratio of the actual fuel / air molar ratio to the stoichiometric fuel / air molar ratio.

[0025] The burner allows the furnace to operate over a wide range of primary to secondary fuel total heat output ratios (i.e., combustion rate ratios).

[0026] The following discloses specific (additional) advantages of the burner of the present invention. Attached Figure Description

[0027] The invention will now be described in conjunction with the accompanying drawings, wherein similar reference numerals denote similar elements.

[0028] Figure 1a is a side cross-sectional view of an embodiment of the burner of the present invention, which is configured to optionally include a common control valve for the main and auxiliary oxidizer conduits, and shows exemplary locations of the fuel connector and the oxidizer connector.

[0029] Figure 1b is an exemplary detailed side cross-sectional view of the downstream sections of various conduits and unique features of the implementation scheme, such as air as an oxidant, oil as a primary fuel, and exhaust gas as a secondary fuel.

[0030] Figure 1c is an exemplary detailed cross-sectional view of the embodiment depicted in Figure 1b, illustrating optional features such as the air exhaust port of the main oxidizer duct and the turbulence generator plate of the secondary fuel duct.

[0031] Figure 2a is an exemplary detailed side cross-sectional view of various conduits and downstream sections of a burner according to an exemplary embodiment of the present invention, highlighting diameters D1 to D5 and distances L1 to L3 according to a particular embodiment defined herein, wherein the conduits are named according to the particular embodiment, and wherein the oxidizer (again: air) and the second and ignition fuel velocities are depicted.

[0032] Figure 2b is a generally specified corresponding view of the catheter using this particular embodiment.

[0033] Figure 3a depicts a preferred embodiment related to the burner depicted in Figures 2a / 2b, wherein the ignition fuel conduit carries "gaseous fuel" and the auxiliary oxidizer conduit carries an oxidizer designated as "combustion accelerant". The ignition flame is "opened".

[0034] Figure 3b depicts an alternative embodiment of the implementation shown in Figure 3a, wherein the ignition fuel conduit for transporting “gaseous fuel” and the auxiliary oxidizer conduit for transporting oxidizer designated as “combustion improver” are arranged differently around the central main fuel nozzle.

[0035] Figure 4a essentially corresponds to the embodiment of Figure 3a, while highlighting the optional distance L1, where the ignition flame is "off". More specifically, the ignition fuel line is recessed into L1 to optimize the length of the ignition air so that it partially or fully develops before exiting the hot (HOT) side of the burner. Not intended to be theoretically constrained, this prevents backflow of combustibles within the fuel line 1 when the fuel is off.

[0036] Figure 4b shows an alternative (suboptimal) implementation scheme that does not use the distance L1.

[0037] Figure 4c also substantially corresponds to the embodiment of Figure 3a, while highlighting the optional distances L1, L2, and L3. Specifically, in a particular embodiment, the fuel line is recessed by a length of L2+L3 to allow the ignition airflow to develop an envelope around the liquid fuel nozzle before exiting the hot side of the burner. Not intended to be theoretically constrained, this helps to keep the fuel nozzle cool when liquid fuel is shut off by preventing hot gases from the swirling recirculation zone from impacting the nozzle's exhaust portion.

[0038] Figure 4d depicts a general alternative implementation. In a specific embodiment of this alternative design, the ignition air supply in duct 2 is provided via "air purge holes" on the wall of duct 2. These holes (number and diameter, hole series) are predetermined based on the area ratio of the holes to the area of ​​the swirling air exhaust section. The pre-calculated ratio depends on the required air volume in the ignition air duct and can be easily determined by a technician.

[0039] Figure 5 is a schematic diagram involving a cross-section similar to that of Figure 3a, indicating an exemplary preferred mode of operating the burner. In a particular embodiment, in step 1, the ignition flame is turned on; in step 2, the main fuel (here: liquid fuel) is ignited using the ignition flame; in step 3, the ignition flame is turned off, and the furnace can be heated for processing; and in step 4, the secondary fuel is turned on separately, which may be, for example, a low Btu / secondary gaseous fuel.

[0040] Figure 6 The experimental results described in this paper are presented. Detailed Implementation

[0041] The present invention generally provides burners, furnaces, and methods as defined in the claims.

[0042] In a first aspect of this document, a burner is provided, comprising: a central main fuel nozzle for supplying atomized liquid fuel, the central main fuel nozzle having a main fuel outlet at its downstream end; a main oxidizer conduit for supplying a main oxidizer (e.g., air, oxygen, or a combination thereof), the main oxidizer conduit having a main oxidizer outlet at its downstream end; an ignition fuel conduit for supplying gaseous ignition fuel, the ignition fuel conduit having an ignition fuel outlet at its downstream end; and an auxiliary oxidizer conduit for supplying an auxiliary oxidizer, the auxiliary oxidizer conduit having an auxiliary oxidizer outlet at its downstream end, wherein at least in all of the above... In the downstream portion of a burner having a main fuel outlet, a main oxidizer outlet, an ignition fuel outlet, and an auxiliary oxidizer outlet, an ignition fuel conduit, an auxiliary oxidizer conduit, and a main oxidizer conduit are concentrically arranged around a central main fuel nozzle, such that the central main fuel nozzle is surrounded by the ignition fuel conduit, the auxiliary oxidizer conduit, and the main oxidizer conduit. At least in the downstream portion of the burner, the central main fuel nozzle, the ignition fuel conduit, and the auxiliary oxidizer conduit are surrounded by the main oxidizer conduit, and a component for igniting the ignition fuel is located inside the ignition fuel conduit and / or the auxiliary oxidizer conduit, upstream of the main fuel outlet.

[0043] In a preferred embodiment of the first aspect, the burner further includes a secondary fuel conduit for supplying secondary fuel, the secondary fuel conduit having a secondary fuel outlet at its downstream end, wherein, at least in the downstream portion of the burner in which the main fuel outlet, main oxidizer outlet, ignition fuel outlet, and auxiliary oxidizer outlet are present, the secondary fuel conduit is preferably concentrically arranged around a central main fuel nozzle, and at least in the downstream portion of the burner, the central main fuel nozzle, ignition fuel conduit, auxiliary oxidizer conduit, and main oxidizer conduit are surrounded by the secondary fuel conduit.

[0044] Preferably, at least in the downstream portion of the burner, the central main fuel injector and the ignition fuel conduit are surrounded by an auxiliary oxidizer conduit.

[0045] As used herein, "the downstream portion of a burner having a main fuel outlet, a main oxidizer outlet, an ignition fuel outlet, and an auxiliary oxidizer outlet" means the entire downstream portion including the main fuel outlet, main oxidizer outlet, ignition fuel outlet, and auxiliary oxidizer outlet. Where a secondary fuel conduit is also present, the portion also includes a secondary fuel outlet. Furthermore, where a swirler section and / or annular region of the exhaust port are also present, the portion also includes a swirler section and / or annular region of the exhaust port. The term "downstream portion" may be used interchangeably with the term "downstream section."

[0046] Typically, in this invention, if a conduit (or spray gun, accordingly) has a smaller diameter than another conduit (or several other conduits, accordingly) and is arranged within said other conduits, then said conduit (or spray gun) is described as being "surrounded" by said other conduits. However, in the case of being "surrounded" by another conduit, the given conduit does not need to be completely surrounded by that other conduit, but may extend further downstream and / or upstream from that other conduit. The corresponding definition applies here, wherein a given element is referred to as being arranged "around" another element.

[0047] Preferably, here, the catheter described as being surrounded by another catheter shares its longitudinal axis with that other catheter.

[0048] In a preferred embodiment of the invention, the ignition fuel conduit, the auxiliary oxidizer conduit, and the main oxidizer conduit (and optionally the secondary fuel conduit) are arranged concentrically around the central main fuel nozzle.

[0049] In a particularly preferred embodiment of the invention, the ignition fuel conduit, auxiliary oxidizer conduit, and main oxidizer conduit (and optionally secondary fuel conduit) are concentrically arranged around the central main fuel nozzle in sections corresponding to at least 20%, preferably at least 30%, particularly at least 40%, especially at least 50%, and in some embodiments at least 75% of the total length of the burner, wherein said section includes the main fuel outlet, the main oxidizer outlet, the ignition fuel outlet, and the auxiliary oxidizer outlet, and optionally the secondary fuel outlet. Where a secondary fuel conduit is also present, said section preferably also includes the secondary fuel outlet. Furthermore, where a swirler section and / or annular region of the exhaust port are also present, said section preferably also includes the swirler section and / or annular region of the exhaust port.

[0050] Here, the “total length” of the burner of the present invention is determined by establishing the distance between the upstream end of all conduits and the downstream end of all conduits.

[0051] In another preferred embodiment, the ignition fuel conduit, the auxiliary oxidizer conduit, and the main oxidizer conduit (and optionally the secondary fuel conduit) are arranged concentrically around the central main fuel nozzle along their entire length.

[0052] In a preferred embodiment of the invention, a given catheter is arranged concentrically around another catheter, resulting in the formation of a corresponding annular region.

[0053] Therefore, in a preferred embodiment, the burner is configured such that ignition fuel and / or primary oxidant, and / or secondary oxidant, and / or secondary fuel, preferably at least ignition fuel, more preferably at least ignition fuel and secondary oxidant flow through the annular zone. In this invention, such annular zones may also be characterized by additional elements (such as discharge orifices, exhaust orifices, swirler sections, etc.) containing corresponding conduits as defined elsewhere herein.

[0054] Similarly, in a preferred embodiment, the burner is characterized in that the ignition fuel outlet and / or the main oxidizer outlet, and / or the auxiliary oxidizer outlet, and / or the secondary fuel outlet, preferably at least the ignition fuel outlet, more preferably at least the ignition fuel outlet and the auxiliary oxidizer outlet, are configured as an annular ring. In this invention, such an annular ring may be characterized by containing additional elements as defined elsewhere herein (such as discharge ports, exhaust ports, swirler sections, etc.).

[0055] According to the present invention, the main fuel used in the burner is a liquid fuel, particularly an atomized liquid fuel. According to the present invention, the ignition fuel used in the burner is a gaseous fuel.

[0056] Generally, the specific properties of the fuel and oxidant used with the burner of the present invention are not particularly limited herein.

[0057] According to the present invention, preferably, the secondary fuel is a gaseous fuel.

[0058] As will be readily understood by those skilled in the art, the primary and secondary fuels can be considered as the main fuels of the burner of this invention. In contrast, the ignition fuel is primarily used to ignite the primary fuel. Additionally or alternatively, the ignition fuel can assist in the very low control ratio of liquid fuel lance operation by providing a continuous ignition source.

[0059] In a particular embodiment, the secondary fuel of the gaseous fuel is preferably exhaust gas, such as, for example, one of the various exhaust gases produced by an industrial process, or it may be a process gas. As a non-limiting particular embodiment, the gaseous fuel may be selected from the group consisting of: PSA exhaust gas, syngas, and H2 / CO / CO2 / CH4 mixtures.

[0060] The central main fuel injector may also be referred to herein simply as "injector" (or "injector 1"), and in some embodiments may also be referred to as an oil injector. Furthermore, the term "main fuel injector" may be used interchangeably with "main fuel conduit".

[0061] In this invention, the central main fuel nozzle is designed as a liquid fuel conduit, specifically a conduit for atomizing liquid fuel. Specifically, in this invention, the central main fuel nozzle is used to supply atomized liquid fuel.

[0062] Therefore, the central main fuel nozzle can also be referred to as a liquid fuel atomizing nozzle. In some embodiments, the central main fuel nozzle is an air- or gas-assisted liquid fuel atomizing nozzle. In a specific embodiment, the central main fuel nozzle is an air-assisted liquid fuel atomizing nozzle. In a specific embodiment of a gas-assisted liquid fuel atomizing nozzle, it is useful for the ratio of the mass flow rate of the atomizing gas to the mass flow rate of the liquid fuel to be in the range of 0.025 to 0.5. In some embodiments, the central main fuel nozzle is a pressure atomizing liquid nozzle.

[0063] Furthermore, the central main fuel injector is preferably arranged at the center of the burner, preferably along its entire length, and in particular, the remaining ducts of the burner are arranged concentrically around the central main fuel injector.

[0064] The central main fuel injector preferably also includes a main fuel connector.

[0065] In a generally preferred embodiment, the burner is configured such that the main fuel velocity at the main fuel outlet is less than 140 feet per second, and particularly less than 120 feet per second. In another embodiment, the main fuel exhaust velocity is less than 100 feet per second, such as in the range of 80 feet per second to 100 feet per second. Therefore, in a generally preferred embodiment, the burner is configured such that the main fuel velocity at the main fuel outlet is in the range of 80 feet per second to 140 feet per second.

[0066] In this specific implementation, the velocity of the liquid fuel / oxidizer mixture helps the spray to be engulfed by the recirculation zone established by the air vortex. This advantageously avoids the problem that the spray might interfere with the development of the proper recirculation zone and lead to an increase in flame length (if the momentum is too high).

[0067] As indicated above, in this invention, the primary fuel is a liquid fuel. As a non-limiting specific embodiment, the liquid fuel may be selected from the group consisting of: #2 fuel oil, #6 fuel oil, naphtha, coal-water slurry, and any suitable waste liquid, all of which are readily known to those skilled in the art.

[0068] Furthermore, the ignition fuel conduit preferably also includes an ignition fuel connector.

[0069] In some embodiments, the ignition fuel conduit is designated as "pipeline 1", which is a gaseous fuel conduit.

[0070] Preferably, the ignition fuel conduit includes a plurality of discharge holes. Such "discharge holes" are holes included in the ignition fuel outlet through which the ignition fuel is discharged from the ignition fuel conduit.

[0071] Here, the diameter of the fuel discharge hole (22) can be defined as P0. Preferably, P0 / D1 is between 0.02 and 0.2.

[0072] Preferably, the outlet plane defined by the discharge hole corresponds to the outlet plane of the ignition fuel outlet.

[0073] Preferably, the discharge holes are arranged around the central main fuel nozzle, preferably equidistant from each other, and at a fixed interval from the central main fuel nozzle.

[0074] Here, the circumferential angle defined by the main axis (4) of the burner and the center of the two adjacent primary fuel discharge holes (22) can be defined as angle θ.

[0075] In a preferred embodiment, the angle θ is between 10 and 50 degrees.

[0076] Not intended to be bound by theory, a lower range helps to separate the orifices so that they are not too close to create fuel-rich areas and prevent air-fuel mixing, while a higher range prevents the orifices from being too far apart and ensures sufficient coupling between the two jets to provide the coupling effect of heat release from each jet for stable combustion.

[0077] In a preferred embodiment, the ignition fuel discharge plate (23) has a porosity in the range of 2% to 25% (defined by dividing the total open area on the plate that allows fuel flow by the cross-sectional area of ​​the plate).

[0078] Furthermore, regarding the auxiliary oxidant conduit, in some embodiments it is designated as "pipeline 2", which is specifically an air conduit.

[0079] The auxiliary oxidant conduit preferably also includes an auxiliary oxidant connector.

[0080] In some embodiments, the auxiliary oxidant conduit further includes an air purging port. Preferably, the air purging port allows the oxidant to pass between the main and auxiliary oxidant conduits.

[0081] Furthermore, the main oxidant conduit preferably also includes a main oxidant connector.

[0082] In some implementations, the main oxidant conduit is designated as "pipe 3", and in particular, it is an air conduit.

[0083] Preferably, the main oxidant conduit also includes a cyclone section.

[0084] Preferably, the hydrocyclone section is located upstream of the main oxidant outlet.

[0085] Preferably, the swirl angle is between 5 and 60 degrees. Depending on the desired or expected combustion rate and flame length, the swirl angle can be set between 30 and 45 degrees. In a particular embodiment, the swirl angle is between 30 and 42 degrees.

[0086] As used herein, the "swirling angle" is defined as the angle between the swirler blades and a plane parallel to the main axis of the burner.

[0087] Preferably, the intensity of the swirling effect imparted to the fluid can be quantified by the swirling number S, which is defined as the ratio of the axial flux of the angular momentum Gφ to the product of the axial thrust Gx and the exhaust radius R of the burner nozzle. When S = Gφ / GxR is less than 0.6, the fluid is in a weak swirling state, and when S is greater than 0.6, the fluid is in a strong swirling state. The swirling number is preferably in the range of 0.1 to 1.5. This swirling number or intensity can be generated by using axial, radial, or tangential swirlers.

[0088] The swirler section can be configured such that the air introduced into the swirler section causes a tangential flow field in the combustion chamber, in particular i) increasing the mixing rate between air, primary fuel, and secondary fuel, and / or ii) creating a compact flame suitable for a short reaction chamber.

[0089] In some preferred embodiments, the main oxidizer conduit also includes a drain hole. As used herein, the drain hole allows a portion of the main oxidizer to pass through during burner operation.

[0090] Preferably, the discharge port is included within the annular region of the discharge port.

[0091] In a preferred embodiment, the main oxidant conduit includes both a cyclone section and an annular region with an exhaust port.

[0092] In some embodiments, the annular discharge portion of the discharge port has a "purge air plate" (47) having a porosity within a limit of 2% to 15% (defined by dividing the total open area of ​​the plate that allows airflow by the cross-sectional area of ​​the plate).

[0093] In a particular embodiment, an exhaust orifice (and preferably an annular region of the exhaust orifice) is arranged next to the hydrocyclone section, such that the main oxidant can pass through both the exhaust orifice and the hydrocyclone section.

[0094] In some embodiments, the diameter of the discharge orifice (43) may be defined as P1. Preferably, P1 / D1 is between 0.02 and 0.2.

[0095] Preferably, the annular region of the discharge port is arranged in a fixed spatial relationship between the outermost part of the ignition fuel conduit wall and the auxiliary oxidizer conduit wall in the radial direction and between the cyclone section.

[0096] Furthermore, the secondary fuel conduit preferably also includes a secondary fuel connector.

[0097] In some embodiments, the secondary fuel conduit is designated as "pipeline 4", which is in particular a gas fuel conduit.

[0098] In a preferred embodiment, the secondary fuel conduit includes a turbulence generator, which may also be referred to herein as a component for generating turbulence or a turbulence generator component. It may include one or more turbulence generator discs or turbulence generator plates. Preferably, the turbulence generator component is arranged on an additional wall of the secondary fuel conduit, which is positioned adjacent to the wall of the primary oxidizer conduit.

[0099] Not intended to be bound by theory, regarding turbulence generation, the inventors have noted that in small-volume furnaces or containers, it may be important to achieve complete combustion of fuel over a short distance. To increase the turbulence intensity in secondary fuels (such as exhaust gas mixtures), a turbulence generator disk can be introduced into the exhaust gas stream. This disk creates vortices that contribute to increasing the turbulence intensity of the exhaust gas stream. Higher turbulence intensity helps to enhance the mixing of fuel and oxidant, thereby facilitating combustion of the exhaust gas mixture over a shorter downstream distance.

[0100] Preferably, in the presence of a secondary fuel conduit, the conduit end plane of the secondary fuel conduit is defined as the "hot surface" of the burner.

[0101] The secondary fuel conduit may take any form as known to those skilled in the art. The secondary fuel conduit may be located radially away from the primary oxidizer conduit.

[0102] Alternatively, the secondary fuel conduits can take the form of several concentric conduits located at fixed radial positions relative to the outer diameter of the main oxidizer conduit. Furthermore, these concentric concentric concentric rings can be arranged at several radial positions around the main oxidizer conduit.

[0103] In a preferred embodiment, the outlet plane of the ignition fuel outlet is recessed by a distance L1 in the upstream direction from the outlet plane of the main fuel outlet.

[0104] In the relevant implementation scheme, the outlet plane of the discharge hole is recessed by a distance L1 in the upstream direction from the outlet plane of the main fuel outlet.

[0105] In a preferred embodiment of the invention, the outlet plane of the innermost ignition fuel conduit and the auxiliary oxidizer conduit in the radial direction (preferably the ignition fuel conduit) is recessed by a distance L1 from the outlet plane of the main oxidizer conduit in the upstream direction.

[0106] In some embodiments, the outlet plane of the ignition fuel conduit and the outlet plane of the auxiliary oxidizer conduit are both recessed by a distance L1 from the outlet plane of the main oxidizer conduit in the upstream direction.

[0107] In a preferred embodiment of the invention, the end face of the auxiliary oxidant conduit is recessed by a distance L2 from the end face of the main oxidant conduit in the upstream direction.

[0108] In a preferred embodiment of the invention, the conduit end plane of the main oxidant conduit is recessed by a distance L3 from the conduit end plane of the secondary fuel conduit in the upstream direction.

[0109] In a preferred embodiment of the invention, the fuel tube is recessed by a length of L2+L3. This is considered advantageous to allow the ignition airflow to develop a cladding around the liquid fuel nozzle before exiting the hot side of the burner. Not intended to be theoretically constrained, this helps to keep the fuel nozzle cool when liquid fuel is shut off by preventing hot gases from the swirling recirculation zone from impacting the nozzle's exhaust portion.

[0110] As used herein, the “outlet plane” of a given conduit refers to the plane defined in a direction perpendicular to the main axis of the conduit at a downstream location where the fuel or oxidant is no longer restricted by the two walls, respectively.

[0111] Similarly, the "exit plane" of the central main fuel injector is defined as the plane in a direction perpendicular to the main axis of the duct, located downstream where the main fuel is no longer restricted by the two walls. This also applies to the central injector.

[0112] As used herein, the “catheter end plane” of a given catheter refers to the plane defined at the downstream end of the catheter in a direction perpendicular to the main axis of the catheter.

[0113] Similarly, the "duct end plane" (central nozzle end plane or similar term) of the central main fuel injector refers to the plane defined at the downstream end of the main fuel outlet in a direction perpendicular to the main axis of the duct. In the case of a central main fuel injector, the duct end plane corresponds to its outlet plane.

[0114] In a preferred embodiment, herein, the duct end plane of the main fuel duct is located downstream of the duct end plane of the pilot fuel duct, preferably at a distance L1 apart.

[0115] In a preferred embodiment, herein, the duct end plane of the auxiliary oxidizer duct is located downstream of the outlet plane of the auxiliary oxidizer duct, preferably at a distance L1 apart.

[0116] In a preferred embodiment, the duct end plane of the main oxidizer duct is located downstream of the outlet plane of the main oxidizer duct, preferably at a distance L2 apart.

[0117] Likewise, in a preferred embodiment, the duct end plane of the main oxidizer duct is located downstream of the duct end plane of the auxiliary oxidizer duct, preferably at a distance L2 apart.

[0118] In a preferred embodiment, herein, the duct end plane of the secondary fuel duct is located downstream of the outlet plane of the secondary fuel duct, preferably at a distance L3 apart.

[0119] Likewise, in a preferred embodiment, the duct end plane of the secondary fuel duct is located downstream of the duct end plane of the main oxidizer duct, preferably at a distance L3 apart.

[0120] In a preferred embodiment of the present invention, the central main fuel spray gun wall has an outer diameter D1.

[0121] In a preferred embodiment of the present invention, the innermost one in the radial direction of the pilot fuel duct wall and the auxiliary oxidizer duct wall has an outer diameter D2. More preferably, the pilot fuel duct wall has an outer diameter D2.

[0122] In a preferred embodiment of the present invention, the outermost one in the radial direction of the pilot fuel duct wall and the auxiliary oxidizer duct wall has an inner diameter D3. More preferably, the auxiliary oxidizer duct has an inner diameter D3.

[0123] In a preferred embodiment of the present invention, the outer wall of the main oxidizer duct has an inner diameter D4.

[0124] Furthermore, in a preferred embodiment of the present invention, the outer wall of the secondary fuel duct has an outer diameter D5.

[0125] According to a preferred embodiment, the magnitude (or diameter, respectively) of the diameters herein is D1 < D2 < D3 < D4, preferably D1 < D2 < D3 < D4 < D5.

[0126] In other embodiments, herein, the magnitude is D1 < D3 < D2 < D4, preferably D1 < D3 < D2 < D4 < D5.

[0127] In some implementations, D2 / D1 is between 1 and 2.5, and particularly between 1.7 and 2.2.

[0128] In some implementations, D3 / D1 is between 2 and 4, and particularly between 2.5 and 3.3.

[0129] In some implementations, D4 / D1 is between 3.5 and 6.5, and particularly between 4.5 and 6.

[0130] In some implementations, D5 / D1 is between 5.0 and 10.0, and particularly between 5.6 and 7.4.

[0131] In a particular embodiment, D2 / D1 is between 1 and 2.5, more preferably between 1.7 and 2.2; D3 / D1 is between 2 and 4, more preferably between 2.5 and 3.3; D4 / D1 is between 3.5 and 6.5, more preferably between 4.5 and 6; and D5 / D1 is between 5 and 10, more preferably between 5.6 and 7.4.

[0132] Preferably, L1 / D1 is between 0.5 and 15, more preferably between 1.0 and 10, and even more preferably between 1.5 and 4.

[0133] Preferably, L2 / D2 is between 0.05 and 10, more preferably between 0.07 and 2, and even more preferably between 0.1 and 0.5.

[0134] Preferably, L3 / D3 is between 0.05 and 10, more preferably between 0.07 and 2, and even more preferably between 0.1 and 0.5.

[0135] In certain specific embodiments herein, L1 / D1 is between 1.0 and 10, more preferably between 1.5 and 4; L2 / D2 is between 0.05 and 10, more preferably between 0.1 and 0.5; and L3 / D3 is between 0.05 and 10, more preferably between 0.1 and 0.5.

[0136] In alternative embodiments of this document corresponding to any of the above embodiments, each of the diameters D1, D2, D3, and D4 corresponds to an outer diameter.

[0137] In a preferred embodiment, the conduit end plane of the main fuel injector is substantially located downstream of the conduit end plane of the outermost conduit in the radial direction of the ignition fuel conduit and the auxiliary oxidizer conduit.

[0138] Typically, and needlessly so, the primary and secondary oxidants comprise oxygen. The oxygen is preferably included in the primary and / or secondary oxidants in an amount of 15% to 30% by volume. In a particularly preferred embodiment, the primary and secondary oxidants are air. It is generally known in the art that air comprises about 20.9% by volume of oxygen.

[0139] Therefore, the burner of the present invention can advantageously use air as an oxidant, and air is considered an readily available / inexpensive source of oxidant.

[0140] Furthermore, when both oxidants are the same (such as air, preferably), both the main oxidant conduit and the auxiliary oxidant conduit can be connected to the same oxidant supply.

[0141] Preferably, all the conduits are connected to the same oxidizer supply using control valves. Thus, in a particular embodiment, the oxidizer required to burn this ignition gas fuel, such as air, is supplied from the main air supply to the burner or a separate air line via a diversion valve.

[0142] In one embodiment, the volumetric flow rate of the auxiliary oxidant is approximately 5% to 20% of the total oxidant flow rate of the burner.

[0143] In some implementations, within a particular conduit, the volumetric flow rate of any fluid is distributed between different outlets by relating the cross-sectional area of ​​a single outlet portion of that conduit to the total cross-sectional area of ​​the outlet portions. In doing so, the fluid pressure and the pressure difference between two adjacent conduits are important criteria for determining the directional flow of the fluid.

[0144] In this alternative implementation, the area of ​​the various orifices and outlets can be defined. That is, for example, in the sample area specification of the combustion-supporting agent conduit, the cross-sectional areas of the air purge orifice (37) and the oxidizer section outlet (42) can be defined as A0 and A1. Preferably, A0 is 5% to 20% of (A0+A1).

[0145] Therefore, approximately 5% to 20% of the primary oxidant (e.g., primary air) can be supplied through the ignition burner flame. In some preferred embodiments, this air continues to flow in the gap between the swirling air and the liquid fuel conduit when the ignition burner fuel is shut off.

[0146] This feature is not intended to be limited in any way, and as will be readily understood by those skilled in the art, the ignition fuel conduit and auxiliary oxidizer conduit described herein can be described (and / or considered) as the ignition burner of the burner of the present invention.

[0147] Therefore, the auxiliary oxidant used herein may also be specified as "ignition air". However, the air may also be used for other purposes as described herein.

[0148] Generally, an "ignition burner" is understood as a burner used to initially ignite the main fuel. Therefore, an ignition burner is preferably used to ignite the main fuel.

[0149] Once the (main) burner is ignited using the ignition burner, the ignition burner can be shut off again by closing the ignition fuel conduit. In contrast to the ignition fuel conduit, the auxiliary oxidizer conduit is preferably not shut off, but rather serves as the oxidizer for the main fuel. Therefore, the auxiliary oxidizer conduit is preferably configured to supply oxidizer to the central main fuel nozzle, for example, after the ignition burner has been shut off.

[0150] More specifically, in a non-limiting embodiment, the ignition flame provides a small heat output: approximately 10% of the main combustion rate of the liquid fuel burner at startup. Typically, the ignition flame is only used to ignite the main liquid fuel during burner startup operation. Therefore, once the liquid fuel has been ignited, the ignition flame can be shut off without causing any primary liquid flame to be extinguished or damaging the burner. In some embodiments, the ignition fuel conduit 1 may be recessed by a length L1 from the central main fuel nozzle (e.g., oil nozzle 1). The recess L1 facilitates partial premixing of the ignition fuel and auxiliary oxidizer (ignition air), which helps to better stabilize the ignition flame and prevents it from being adversely affected by airflow swirl.

[0151] Typically, during the operation of the burner of the present invention, those skilled in the art can easily and appropriately adjust the rates of oxidant and fuel.

[0152] In a particular embodiment, the burner is configured such that the velocity of the main fuel is less than 140 feet per second, preferably less than 120 feet per second.

[0153] In a particular embodiment, the burner is configured such that the velocity of the primary oxidant is between 20 ft / s and 200 ft / s, particularly between 40 ft / s and 140 ft / s. However, if the available pressure is high, the velocity can easily reach 200 ft / s to 300 ft / s.

[0154] Not intended to be theoretically constrained, the maximum achievable primary oxidant (preferably air) velocity is typically determined by the available pressure from the blower. The inventors have discovered that these velocities, along with appropriate swirl angles, provide adequate mixing of the air with both fuels and maintain a stable flame over a wide range of burner operations, even in cold furnaces.

[0155] Generally, unless otherwise specified, a given speed refers to the speed of oxidizer / fuel at the outlet of its given conduit.

[0156] In a particular embodiment, the burner is configured such that the velocity of the auxiliary oxidant is between 10 feet per second and 80 feet per second, particularly between 20 feet per second and 40 feet per second.

[0157] Not intended to be theoretically constrained, the ignition / auxiliary fuel rate is typically kept low, allowing the air to provide sufficient momentum to prevent any backflow of hot gas toward the ignition fuel line. An upper limit is determined such that the momentum is not high enough to begin adversely affecting the recirculation region of the air cyclone separator.

[0158] In a particular embodiment, the burner is configured such that the velocity of the secondary fuel is between 20 feet per second and 200 feet per second, particularly between 40 feet per second and 120 feet per second.

[0159] Not intended to be theoretically constrained, the velocity of the secondary fuel was determined to provide sufficient mixing with the swirling air, thereby achieving a stable flame. Secondary fuel velocities below the lower velocity limit would cause unreacted fuel to accumulate near the furnace wall. This fuel could then burn there, leading to overheating of the reformer top wall.

[0160] In a particular embodiment, the burner is configured such that the ignition rate of the fuel at the discharge portion of the fuel discharge port is between 30 feet per second and 250 feet per second, particularly between 60 feet per second and 120 feet per second.

[0161] Preferably, the rate ratio of ignition fuel to auxiliary oxidizer is maintained in the range of 1.5 to 3.0.

[0162] Not intended to be bound by theory, the ignition rate of the fuel was determined to significantly contribute to its ability to mix rapidly with the surrounding air. The range and ratio of ignition fuel and auxiliary oxidizer rates provide a stable flame.

[0163] In one embodiment, the burner is configured such that, under startup conditions, the heat output of the ignition fuel is about 5% to 15% of the heat output of the main fuel, wherein the main fuel is preferably a liquid fuel.

[0164] In one embodiment, the burner is configured such that the total start-up heat output of the burner is provided by the main fuel up to 100%, wherein the main fuel is preferably a liquid fuel.

[0165] In one implementation, the burner is configured such that during normal operation, the heat output of the main fuel is 0 to 40% of the total heat output of the burner.

[0166] In a generally preferred embodiment, each of the conduits defined for the burner is configured as a pipe, particularly as a pipe having a generally circular cross-section, wherein all said conduits may be arranged substantially concentrically.

[0167] Similarly, each conduit in the catheter may have a roughly circular cross-section, and they may all be arranged substantially concentrically.

[0168] Preferably, all catheters in the catheter system share a common central axis. Preferably, all catheters in the catheter system are concentrically arranged around a common longitudinal axis. Also preferably, all catheters are concentrically arranged around a common longitudinal axis. Preferably, all catheters in the catheter system are substantially straight.

[0169] In a particular embodiment, the central main fuel injector is longer than the ignition fuel conduit, which is longer than the auxiliary oxidizer conduit, which is longer than the main oxidizer conduit, and the main oxidizer conduit is longer than the secondary fuel conduit.

[0170] Generally, the advantageous features of the invention include the following, all of which correspond to other preferred embodiments of the first aspect: – The burner of the first aspect can reduce the flame length, especially for keeping the flame length in the furnace smaller than the furnace length.

[0171] – The first type of burner eliminates the need for an external ignition burner. (Unlike typical liquid fuel burners, an external ignition burner is not required). Alternatively, a mechanism for igniting the liquid fuel is included as part of the main burner.

[0172] – The burner of the first aspect can enable the improved functionality of a burner including an ignition burner that is not configured as an ignition fuel conduit and auxiliary oxidizer conduit as defined in any of the preceding entries.

[0173] – The burner of the first aspect can be reliably started in a cold furnace, and the ignition flame can be shut off as needed after the main liquid flame is ignited.

[0174] – The first type of burner can achieve more thorough mixing through combined swirls, thereby producing a shorter flame suitable for compact / short reformers / furnaces / combustion chambers.

[0175] – The burner of the first aspect can achieve low back pressure of primary oxidant (e.g., combustion air) and secondary fuel (e.g., exhaust gas), which can reduce the power requirements of any compression unit or eliminate the need for any secondary compression unit.

[0176] – The first type of burner achieves sufficiently low back pressures for both the primary oxidant (e.g., primary air) and the exhaust gas, eliminating the need for any secondary compressor unit to increase the supply pressure. This, in particular, reduces compressor operating costs, which is required by some commercially available burners.

[0177] – The first aspect of the burner enables the combustion of two fuels using a single airflow, which can help reduce the overall cost of the burner, and optionally reduce the overall cost of the slide, distributor valve, and / or any complex control mechanism.

[0178] – The burner of the first aspect is characterized by a lean fuel-stabilized flame that does not extinguish under high excess air (equivalence ratio as low as 0.25).

[0179] – The first aspect of the burner enables advantageous operating aspects selected from the group consisting of: start-up, exhaust gas introduction, better control ratio, and a wider range of stable operation.

[0180] – The burner in the first aspect includes an ignition burner, which, if needed, can help reduce the regulation ratio when using liquid fuel.

[0181] – The burner in the first aspect includes an ignition burner, which, if needed, can help burn difficult-to-burn liquid fuels (e.g., viscous and / or low Btu fuels).

[0182] - When the ignition burner is turned off, the burner in the first aspect can be operated without damaging the burner.

[0183] – The burner in the first aspect enables the ignition air to be released to prevent any backflow of air into the ignition fuel line.

[0184] – In the burner of the first aspect, the use of a liquid fuel atomizing nozzle facilitates the adjustment of the combustion rate on the liquid fuel spray gun, the liquid fuel atomizing nozzle being an air- or any gas-assisted atomizing nozzle.

[0185] – The first aspect of the burner is characterized by the flexibility of burner operation across a wide range of total heat / energy splits from primary and secondary fuels. This includes approximately 5% to 100% of the total heat output from the primary fuel and the remainder from the secondary fuel.

[0186] In a second aspect of the invention, a furnace is provided that includes a burner according to a first aspect of the invention.

[0187] The preferred embodiment of the furnace of the present invention corresponds to the embodiment of the burner of the present invention described above. Therefore, preferably, the furnace is also defined to be consistent with any of the above embodiments of the burner described with respect to the first aspect.

[0188] This includes implementation schemes related to the advantages of the burner described above in the first aspect, which are also conceived here with respect to the corresponding furnace in the second aspect.

[0189] In some preferred embodiments, the furnace is selected from the group consisting of: furnaces for steam methane reforming, reheating furnaces in the steel industry, and secondary smelting furnaces.

[0190] In a third aspect of the invention, a method is provided for operating a burner of the first aspect and / or for operating a furnace of the second aspect. The method is not particularly limited, as will be readily understood by those skilled in the art.

[0191] In some embodiments, the method includes the steps of: i) starting a burner with an ignition fuel, wherein the ignition fuel is a gaseous fuel, and ii) providing and igniting a main fuel, wherein the main fuel is a liquid fuel.

[0192] Preferably, the method further includes the step of: iii) shutting off the flow of ignition fuel, specifically, wherein the flow is shut off after the main fuel has been ignited.

[0193] Typically, the method preferably further includes: providing and igniting secondary fuel. The secondary fuel can be provided once it becomes available during the industrial process.

[0194] In some embodiments, the method includes the additional step of providing and burning the ignition fuel again, preferably to keep the flame of the main fuel stable.

[0195] Generally, other preferred embodiments of the method of the present invention correspond to the embodiments of the burner of the present invention described above, wherein the burner used in the method is further defined by other product features. In other words, preferably, the method of the present invention is also defined to be consistent with any of the above embodiments of the burner described with respect to the first aspect.

[0196] Furthermore, further preferred embodiments of the method of the present invention involve additional method features based on any features described above with respect to the burner of the present invention.

[0197] For example, in a preferred embodiment of the method, the primary fuel used in the method is a liquid fuel and / or the ignition fuel used in the method is a gaseous fuel; preferably, the primary fuel used in the method is a liquid fuel, the secondary fuel used in the method is a gaseous fuel, and the ignition fuel used in the method is a gaseous fuel.

[0198] In a specific embodiment of the third aspect, the secondary fuel is exhaust gas. In a specific embodiment of the third aspect, the secondary fuel is derived from an industrial process. In a specific embodiment of the third aspect, the secondary fuel is process gas.

[0199] In a specific implementation of the third aspect, the secondary fuel is selected from the group consisting of: PSA exhaust gas, syngas, and H2 / CO / CO2 / CH4 mixtures.

[0200] Furthermore, in this method, the primary and secondary oxidants preferably comprise 15 to 30 vol% of oxygen in the primary and / or secondary oxidants. In a particularly preferred embodiment, the primary and secondary oxidants used in the method are air. It is generally known in the art that air comprises about 20.9 vol% oxygen. Therefore, the method of the present invention can advantageously use air as an oxidant.

[0201] Furthermore, in some embodiments of the method, the volumetric flow rate of the auxiliary oxidant is about 5% to 20% of the total oxidant flow rate of the burner. Therefore, preferably, about 5% to 20% of the primary oxidant (such as primary air) is supplied through the ignition burner flame. In some preferred embodiments, this air continues to flow in the gap between the swirling air and the liquid fuel conduit when the ignition burner fuel is shut off.

[0202] As another example, in a preferred embodiment of the third aspect, ignition fuel and / or primary oxidant, and / or secondary oxidant, and / or secondary fuel, preferably at least igniting fuel, more preferably at least igniting fuel and secondary oxidant, flows through the annular zone. The annular zone may also be characterized by containing additional elements (such as discharge orifices, drain orifices, cyclone sections, etc.) as defined herein with corresponding conduits.

[0203] Furthermore, in a particular embodiment of the method of the present invention, the speed of the main fuel is less than 140 feet per second, preferably less than 120 feet per second.

[0204] In a particular embodiment of the method of the invention, the velocity of the primary oxidant is between 20 feet per second and 200 feet per second, particularly between 40 feet per second and 140 feet per second. However, if the available pressure is high, the velocity can easily reach 200 to 300 feet per second.

[0205] In a particular embodiment of the method of the present invention, the rate of the co-oxidant is between 10 feet per second and 80 feet per second, particularly between 20 feet per second and 40 feet per second.

[0206] In a particular embodiment of the method of the invention, the velocity of the secondary fuel is between 20 feet per second and 200 feet per second, particularly between 40 feet per second and 120 feet per second.

[0207] In a particular embodiment of the method of the invention, the ignition speed of the fuel is between 30 feet per second and 250 feet per second, particularly between 60 feet per second and 120 feet per second.

[0208] In a specific embodiment of the method of the present invention, under startup conditions, the heat output of the ignition fuel is about 5% to 15% of the heat output of the main fuel, wherein the main fuel is preferably a liquid fuel.

[0209] In a specific embodiment of the method of the present invention, the total heat output of the burner at startup is provided by the main fuel up to 100%, wherein the main fuel is preferably a liquid fuel.

[0210] In a specific embodiment of the method of the present invention, during normal operation, the heat output of the main fuel is 0 to 40% of the total heat output of the burner.

[0211] Furthermore, the advantages of the present invention include the following, all of which correspond to further preferred embodiments of the third aspect: – The third approach can reduce the flame length, particularly for keeping the flame length in the furnace shorter than the furnace length.

[0212] – A third approach avoids the need for an external ignition burner. (Unlike typical liquid fuel burners, an external ignition burner is not required.) Instead, a mechanism for igniting the liquid fuel is included as part of the main burner.

[0213] – The third aspect of the method enables improvements to the functionality of a burner including an ignition burner that is not configured as an ignition fuel conduit and auxiliary oxidizer conduit as defined in any of the preceding entries.

[0214] – The third approach enables reliable startup in a cold furnace, and the ignition flame can be shut off as needed after the main liquid flame is ignited.

[0215] – The third approach is to achieve more thorough mixing by combining swirls, thereby producing shorter flames suitable for compact / short reformers / furnaces / combustion chambers.

[0216] – The third approach enables low back pressure of combustion air and exhaust gas, which eliminates the need for any secondary compression unit.

[0217] – The third approach achieves sufficiently low back pressures on the primary oxidant (such as primary air) and secondary fuel (e.g., exhaust gas) streams, eliminating the need for any compressor unit to increase the supply pressure. This, in particular, reduces compressor operating costs, which is required by some commercially available burners.

[0218] – The third approach enables the combustion of two fuels using a single airflow, which can help reduce the overall cost of the burner and optionally reduce the overall cost of the slide, distributor valve, and / or any complex control mechanism.

[0219] – The third approach can achieve advantageous operational aspects selected from the group consisting of: start-up, exhaust gas introduction, better control ratio, and a wider range of stable operation.

[0220] – A third approach may include using an ignition burner, which, if needed, can help reduce the regulation ratio when using liquid fuels.

[0221] – A third approach may include the use of an ignition burner, which, if desired, may optionally aid in the combustion of difficult-to-burn liquid fuels.

[0222] – When the ignition burner is turned off, the third method can be used without damaging the burner.

[0223] – A third approach is to establish an ignition air flame to prevent any backflow of air into the ignition fuel line.

[0224] Typically, in this context, a preferred embodiment of any of the second to fourth aspects corresponds to a preferred embodiment of the first aspect of this document.

[0225] Furthermore, when applied to any feature of the embodiments of the invention described in the specification and claims, the articles “a” and “an” as used herein mean one or more. 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 one or more specific designated features and may have a singular or plural meaning depending on the context in which it is used. The adjective “any” indiscriminately means one, some, or all of a quantity, regardless of the quantity.

[0226] Furthermore, generally, if an embodiment is described here by using the term "comprising" or a similar term, then other embodiments may also be envisioned here, which are described by using the term "consisting of" or a similar term instead of the term "comprising" or a similar term.

[0227] Other specific implementation schemes The present invention also specifically relates to the following items: Item 1: A burner (1) comprising: a central main fuel nozzle (10) for supplying atomized liquid fuel, the central main fuel nozzle having a main fuel outlet (14) at its downstream end; a main oxidizer conduit (40) for supplying a main oxidizer, the main oxidizer conduit having a main oxidizer outlet (44) at its downstream end; an ignition fuel conduit (20) for supplying gaseous ignition fuel, the ignition fuel conduit having an ignition fuel outlet (24) at its downstream end; and an auxiliary oxidizer conduit (30) for supplying an auxiliary oxidizer, the auxiliary oxidizer conduit having an auxiliary oxidizer outlet (34) at its downstream end, wherein at least the main fuel outlet (14), the main oxidizer outlet (44), the ignition fuel outlet (24), and the auxiliary oxidizer outlet (34) are present in the downstream portion of the burner (1). In part (5), the ignition fuel conduit (20), the auxiliary oxidizer conduit (30), and the main oxidizer conduit (40) are concentrically arranged around the central main fuel nozzle (10), such that the central main fuel nozzle (10) is surrounded by the ignition fuel conduit (20), the auxiliary oxidizer conduit (30), and the main oxidizer conduit (40), wherein at least in the downstream part (5) of the burner (1), the central main fuel nozzle (10), the ignition fuel conduit (20), and the auxiliary oxidizer conduit (30) are surrounded by the main oxidizer conduit (40), and wherein the component (65) for igniting the ignition fuel is optionally present inside the ignition fuel conduit (20) and / or the auxiliary oxidizer conduit (30), upstream of the main fuel outlet (14).

[0228] Item 2: According to the burner (1) of Item 1, the burner further includes: a secondary fuel conduit (50) for supplying secondary fuel, the secondary fuel conduit having a secondary fuel outlet (54) at its downstream end, wherein in the downstream portion (5) of the burner (1) in which at least a main fuel outlet, a main oxidizer outlet, an ignition fuel outlet (24) and an auxiliary oxidizer outlet are present, the secondary fuel conduit is concentrically arranged around the central main fuel nozzle (10), and wherein in the downstream portion (5) of the burner (1), the central main fuel nozzle (10), the ignition fuel conduit (20), the auxiliary oxidizer conduit (30) and the main oxidizer conduit (40) are surrounded by the secondary fuel conduit.

[0229] Item 3: The burner (1) according to Item 1, wherein at least in the downstream portion (5) of the burner (1), the central main fuel injector (10) and the ignition fuel conduit (20) are surrounded by the auxiliary oxidizer conduit (30).

[0230] Item 4: A burner (1) comprising a central main fuel nozzle (10) for supplying atomized liquid fuel, a main oxidizer conduit (40) for supplying a main oxidizer, an ignition fuel conduit (20) for supplying gaseous ignition fuel, and an auxiliary oxidizer conduit (30) for supplying an auxiliary oxidizer, wherein at least in the terminal portion of the burner (1) comprising at least 20% of its length, the ignition fuel conduit (20), the auxiliary oxidizer conduit (30), and the main oxidizer conduit (40) are concentrically arranged around the central main fuel nozzle (10). The central main fuel injector (10) is surrounded by the ignition fuel conduit (20), the auxiliary oxidizer conduit (30), and the main oxidizer conduit (40), wherein at least in the terminal portion of the burner (1), the central main fuel injector (10), the ignition fuel conduit (20), and the auxiliary oxidizer conduit (30) are surrounded by the main oxidizer conduit (40), and wherein a component (65) for igniting the ignition fuel is optionally present inside the ignition fuel conduit (20) and / or the auxiliary oxidizer conduit (30), upstream of the main fuel outlet.

[0231] Item 5: The burner (1) according to Item 4, wherein the burner (1) further includes a secondary fuel conduit (50) for supplying secondary fuel, wherein at least in the terminal portion of the burner (1), the secondary fuel conduit (50) is concentrically arranged around the central main fuel injector (10), and wherein at least in the terminal portion of the burner (1), the central main fuel injector (10), the ignition fuel conduit (20), the auxiliary oxidizer conduit (30), and the main oxidizer conduit (40) are surrounded by the secondary fuel conduit (50).

[0232] Item 6: A burner (1) comprising a central main fuel injector (10) for a main fuel and a main oxidizer conduit (40) for a main oxidizer, wherein the central main fuel injector (10) is substantially positioned (preferably concentrically) within the main oxidizer conduit (40); characterized in that the burner (1) further comprises an ignition fuel conduit (20) for igniting fuel and an auxiliary oxidizer conduit (30) for an auxiliary oxidizer, wherein the downstream portions (5) of the ignition fuel conduit (20) and the auxiliary oxidizer conduit (30) are positioned (preferably concentrically) within the main oxidizer conduit (40).

[0233] Item 7: The burner (1) according to Item 6, wherein the burner (1) further includes a secondary fuel conduit (50) for secondary fuel, wherein the primary oxidant conduit (40) is positioned (preferably concentrically) within the secondary fuel conduit (50).

[0234] Item 8: The burner (1) according to any one of the preceding items, wherein the main oxidant conduit (40) in the downstream section (5) of the burner (1) includes a cyclone section (42) upstream of the main oxidant outlet.

[0235] Item 9: The burner (1) according to any one of the preceding items, a) wherein the auxiliary oxidizer conduit (30) further includes an air purge hole (37), preferably wherein the air purge hole (37) is located upstream of the cyclone section (42), and / or b) wherein the ignition fuel conduit (20) discharge portion further includes a series of small discharge holes (22), in particular, wherein the discharge holes (22) are arranged in a fixed spatial position to create an ignition fuel jet.

[0236] Item 10: A burner (1) according to any one of the preceding items, wherein a) the central main fuel nozzle (10) is an air- or other gas-assisted atomizing nozzle, and / or b) wherein the secondary fuel conduit (50) includes a turbulence generator (57) upstream of its outlet plane (55), preferably immediately adjacent to its outlet plane (55).

[0237] Item 11: The burner (1) according to any one of the preceding items, wherein the outlet plane (25) of the ignition fuel outlet (24) is recessed by a distance L1 in the upstream direction from the outlet plane (15) of the main fuel outlet (14).

[0238] Item 12: The burner (1) according to Item 11, wherein the wall of the central main fuel nozzle (10) has an outer diameter D1.

[0239] Item 13: The burner (1) according to Item 12, wherein L1 / D1 is between 0.5 and 15.

[0240] Item 14: The burner (1) according to Item 13, wherein L1 / D1 is between 1.0 and 10.

[0241] Item 15: The burner (1) according to Item 14, wherein L1 / D1 is between 1.5 and 4.

[0242] Item 16: The burner (1) according to any one of the preceding items, wherein the conduit end plane of the auxiliary oxidant conduit is recessed by a distance L2 from the conduit end plane of the main oxidant conduit in the upstream direction.

[0243] Item 17: The burner (1) according to any one of the preceding items, wherein the innermost of the ignition fuel conduit wall (29) and the auxiliary oxidant conduit wall (39) in the radial direction, preferably the ignition fuel conduit wall (29), has an outer diameter D2.

[0244] Item 18: The burner (1) according to Item 17, wherein L2 / D2 is between 0.05 and 10, preferably between 0.1 and 10.

[0245] Item 19: The burner (1) according to Item 18, wherein L2 / D2 is between 0.07 and 2, preferably between 0.1 and 2.

[0246] Item 20: The burner (1) according to Item 19, wherein L2 / D2 is between 0.1 and 0.5.

[0247] Item 21: The burner (1) according to any one of the preceding items, wherein the conduit end plane (46) of the main oxidant conduit (40) is recessed by a distance L3 in the upstream direction from the conduit end plane (56) of the secondary fuel conduit (50).

[0248] Item 22: The burner (1) according to any one of the preceding items, wherein the outermost of the ignition fuel conduit wall (29) and the auxiliary oxidant conduit wall (39) in the radial direction, preferably the auxiliary oxidant conduit wall (39), has an inner diameter D3.

[0249] Item 23: The burner (1) according to Item 22, wherein L3 / D3 is between 0.05 and 10, preferably between 0.1 and 10.

[0250] Item 24: The burner (1) according to Item 23, wherein L3 / D3 is between 0.07 and 2, preferably between 0.1 and 2.

[0251] Item 25: The burner (1) according to Item 24, wherein L3 / D3 is between 0.1 and 0.5.

[0252] Item 26: The burner (1) according to any one of the preceding items, wherein the conduit end plane (16) of the main fuel injector (10) is substantially at the same downstream position as the conduit end plane (36) of the outermost conduit in the radial direction of the ignition fuel conduit (20) and the auxiliary oxidizer conduit (30).

[0253] Item 27: The burner (1) according to any one of the preceding items, wherein the central main fuel nozzle wall (19) has an outer diameter D1, the innermost of the ignition fuel conduit wall (29) and the auxiliary oxidizer conduit wall (39) in the radial direction has an outer diameter D2, the outermost of the ignition fuel conduit wall (29) and the auxiliary oxidizer conduit wall (39) in the radial direction has an inner diameter D3, and the outer wall (49) of the main oxidizer conduit (40) has an inner diameter D4.

[0254] Item 28: A burner (1) according to any one of items 1 to 26, wherein the central main fuel nozzle (10) has a diameter D1, and / or the main oxidizer conduit (40) has a diameter D4, and / or the secondary fuel conduit (50) has a diameter D5, and / or the ignition fuel conduit (20) has a diameter D2, and / or the auxiliary oxidizer conduit (30) has a diameter D3.

[0255] Item 29: The burner (1) according to Item 28, wherein the central main fuel nozzle (10) has a diameter D1, and the main oxidizer conduit (40) has a diameter D4, and the secondary fuel conduit (50) has a diameter D5, and the ignition fuel conduit (20) has a diameter D2, and the auxiliary oxidizer conduit (30) has a diameter D3.

[0256] Item 30: Burner (1) according to item 28 or 29, wherein each of said diameters is an outer diameter.

[0257] Item 31: Burner (1) according to any one of the preceding items, wherein D1 < D2 < D3 < D4, preferably, wherein D1 < D2 < D3 < D4 < D5.

[0258] Item 32: Burner (1) according to any one of the preceding items, wherein D1 < D3 < D2 < D4 < D5, preferably, wherein D1 < D2 < D3 < D4 < D5.

[0259] Item 33: Burner (1) according to any one of the preceding items, wherein D2 / D1 is between 1 and 2.5, particularly between 1.7 and 2.2. <o

[0260] Item 34: Burner (1) according to any one of the preceding items, wherein D3 / D1 is between 2 and 4, particularly between 2.5 and 3.3.

[0261] Item 35: Burner (1) according to any one of the preceding items, wherein D4 / D1 is between 3.5 and 6.5, particularly between 4. and 6.

[0262] Item 36: Burner (1) according to any one of the preceding items, wherein i) D2 / D1 is between 1 and 2.5, particularly between 1.7 and 2.2; and / or ii) D3 / D1 is between 2 and 4, particularly between 2.5 and 3.3; and / or iii) D4 / D1 is between 3.5 and 6.5, particularly between 4.5 and 6.

[0263] Item 37: Burner (1) according to any one of the preceding items, wherein i) D2 / D1 is between 1 and 2.5, particularly between 1.7 and 2.2; and ii) D3 / D1 is between 2 and 4, particularly between 2.5 and 3.3; and iii) D4 / D1 is between 3:5 and 6.5, particularly between 4.5 and 6.

[0264] Item 38: Burner (1) according to any one of the preceding items, wherein the outer wall (59) of the secondary fuel conduit (5o) has an outer diameter D5.

[0265] Item 39: Burner (1) according to item 38, wherein D5 / D1 is between 5 and 10.

[0266] Item 40: Burner (1) according to item 39, wherein D5 / D1 is between 5.6 and 7.4.

[0267] It should be noted that in the original text, there is a possible error in "5o" in "the secondary fuel conduit (5o)" in item 24. It is assumed to be "50" in the translation.Item 41: A burner (1) according to any one of items 38 to 40, wherein i) D2 / D1 is between 1 and 2.5, particularly between 1.7 and 2.2; and / or ii) D3 / D1 is between 2 and 4, particularly between 2.5 and 3.3; and / or iii) D4 / D1 is between 3.5 and 6.5, particularly between 4.5 and 6; and / or iv) D5 / D1 is between 5 and 10, particularly between 5.6 and 7.4.

[0268] Item 42: The burner (1) according to Item 41, wherein i) D2 / D1 is between 1 and 2.5, particularly between 1.7 and 2.2; and ii) D3 / D1 is between 2 and 4, particularly between 2.5 and 3.3; and iii) D4 / D1 is between 3.5 and 6.5, particularly between 4.5 and 6; and iv) D5 / D1 is between 5 and 10, particularly between 5.6 and 7.4.

[0269] Item 43: The burner (1) according to any one of the preceding items, wherein the swirling angle, defined as the angle between the swirler blades and the plane of the swirler parallel to the main axis of the burner (1), is 5 to 60 degrees.

[0270] Item 44: The burner (1) according to Item 43, wherein the swirl angle is 30 to 42 degrees.

[0271] Item 45: The burner (1) according to any one of the preceding items, wherein the main oxidant conduit (40) further includes an exhaust port (43), preferably wherein the exhaust port (43) is included within an annular region (48) of the exhaust port.

[0272] Item 46: The burner (1) according to any one of the preceding items, wherein the main oxidant conduit (40) comprises both a swirler section (42) and an exhaust port (43), preferably wherein the exhaust port (43) is included within an annular region (48) of the exhaust port.

[0273] Item 47: The burner (1) according to Item 45 or 46, wherein the discharge port (43) and preferably the annular region (48) of the discharge port (43) are arranged next to the cyclone section (42) such that the main oxidant can pass through both the discharge port (43) and the cyclone section (42).

[0274] Item 48: The burner (1) according to any one of items 45 to 47, wherein the discharge port (43) and the annular region (48) of the discharge port (43) preferably include the discharge port (43) are included in the downstream section of the main oxidant conduit (40) and next to the auxiliary oxidant conduit (30).

[0275] Item 49: The burner (1) according to any one of items 45 to 48, wherein the discharge port (43) and the annular region (48) of the discharge port (43) are arranged next to the cyclone section (42) such that the main oxidant can pass through both the discharge port (43) and the cyclone section (42).

[0276] Item 50: A burner (1) according to any one of the preceding items, wherein the burner (1) is configured such that the velocity of the main oxidant at the main oxidant outlet is between 20 feet / second and 200 feet / second, particularly between 40 feet / second and 140 feet / second.

[0277] Item 51: A burner (1) according to any one of the preceding items, wherein the burner (1) is configured such that the velocity of the auxiliary oxidant at the auxiliary oxidant outlet is between 10 feet / second and 80 feet / second, particularly between 20 feet / second and 40 feet / second.

[0278] Item 52: A burner (1) according to any one of the preceding items, wherein the burner (1) is configured such that the velocity of the secondary fuel at the secondary fuel outlet is between 20 feet / second and 200 feet / second, particularly between 40 feet / second and 120 feet / second.

[0279] Item 53: A burner (1) according to any one of the preceding items, wherein the burner (1) is configured such that the velocity of the ignition fuel at the ignition fuel outlet (24) is between 30 feet / second and 250 feet / second, particularly between 60 feet / second and 120 feet / second.

[0280] Item 54: A burner (1) according to any one of the preceding items, wherein i) the burner (1) is configured such that the velocity of the primary oxidant is between 20 ft / s and 200 ft / s, particularly between 40 ft / s and 140 ft / s; and / or ii) the burner (1) is configured such that the velocity of the secondary oxidant is between 10 ft / s and 80 ft / s, particularly between 20 ft / s and 40 ft / s; and / or iii) the burner (1) is configured such that the velocity of the secondary fuel is between 20 ft / s and 200 ft / s, particularly between 40 ft / s and 120 ft / s; and / or iv) the burner (1) is configured such that the velocity of the ignition fuel is between 30 ft / s and 250 ft / s, particularly between 60 ft / s and 120 ft / s. Preferably, all of the velocities are velocities at the respective outlets.

[0281] Item 55: A burner (1) according to any one of the preceding items, wherein i) the burner (1) is configured such that the velocity of the primary oxidant is between 20 ft / s and 200 ft / s, particularly between 40 ft / s and 140 ft / s; and ii) the burner (1) is configured such that the velocity of the secondary oxidant is between 10 ft / s and 80 ft / s, particularly between 20 ft / s and 40 ft / s; and iii) the burner (1) is configured such that the velocity of the secondary fuel is between 20 ft / s and 200 ft / s, particularly between 40 ft / s and 120 ft / s; and iv) the burner (1) is configured such that the velocity of the ignition fuel is between 30 ft / s and 250 ft / s, particularly between 60 ft / s and 120 ft / s. Preferably, all of the velocities are velocities at the respective outlets.

[0282] Item 56: A burner (1) according to any one of the preceding items, wherein the burner (1) is configured such that, under startup conditions, the heat output of the ignition fuel is about 5% to 15% of the heat output of the main fuel.

[0283] Item 57: A burner (1) according to any one of the preceding items, wherein the burner (1) is configured such that the total start-up heat output of the burner (1) is provided to 100 by the main fuel.

[0284] Item 58: A burner (1) according to any one of the preceding items, wherein the burner (1) is configured such that during normal operation, the heat output of the main fuel is 0 to 40% of the total heat output of the burner (1).

[0285] Item 59: The burner (1) according to any one of the preceding items, wherein the volumetric flow rate of the auxiliary oxidant is about 5% to 20% of the total oxidant flow rate of the burner (1).

[0286] Item 60: A burner (1) according to any one of the preceding items, wherein i) the burner (1) is configured such that, under startup conditions, the heat output of the ignition fuel is about 5% to 15% of the heat output of the main fuel; and / or ii) the burner (1) is configured such that the total startup heat output of the burner (1) is provided by the main fuel to 100; and / or iii) the burner (1) is configured such that, during normal operation, the heat output of the main fuel is 0% to 40% of the total heat output of the burner (1); and / or iv) the volumetric flow rate of the auxiliary oxidant is about 5% to 20% of the total oxidant flow rate of the burner (1).

[0287] Item 61: The burner (1) according to Item 60, wherein i) the burner (1) is configured such that, under startup conditions, the heat output of the ignition fuel is about 5% to 15% of the heat output of the main fuel; and / or ii) the burner (1) is configured such that the total startup heat output of the burner (1) is provided by the main fuel to 100; and / or iii) the burner (1) is configured such that, during normal operation, the heat output of the main fuel is 0% to 40% of the total heat output of the burner (1); and / or iv) the volumetric flow rate of the auxiliary oxidant is about 5% to 20% of the total oxidant flow rate of the burner (1).

[0288] Item 62: The burner (1) according to any one of the preceding items, wherein the ignition fuel conduit (20) and the auxiliary oxidizer conduit (30) are configured as ignition burners for igniting the burner (1).

[0289] Item 63: The burner (1) according to Item 62, wherein the ignition burner is used to ignite the main fuel.

[0290] Item 64: The burner (1) according to Item 62 or 63, wherein the auxiliary oxidizer conduit (30) is configured to supply oxygen to the central main fuel injector (10) after the ignition burner has been shut off.

[0291] Item 65: The burner (1) according to any one of the preceding items, wherein the secondary fuel is a gaseous fuel.

[0292] Item 66: A burner (1) according to any one of the preceding items, wherein the primary fuel is a liquid fuel, the secondary fuel is a gaseous fuel, and the ignition fuel is a gaseous fuel.

[0293] Item 67: The burner (1) according to any one of the preceding items, wherein the secondary fuel is exhaust gas.

[0294] Item 68: A burner (1) according to any one of the preceding items, wherein the secondary fuel is derived from an industrial process.

[0295] Item 69: The burner (1) according to any one of the preceding items, wherein the secondary fuel is a process gas.

[0296] Item 70: A burner (1) according to any one of the preceding items, wherein the secondary fuel is selected from the group consisting of: PSA exhaust gas, syngas, and H2 / CO / CO2 / CH4 mixture.

[0297] Item 71: A burner (1) according to any one of the preceding items, wherein the auxiliary oxidizer conduit (30) includes a component (65) for igniting the ignition fuel.

[0298] Item 72: A burner (1) according to any one of the preceding items 1 to 70, wherein the ignition fuel conduit (20) includes a component (65) for igniting the ignition fuel.

[0299] Item 73: The burner (1) according to any one of the preceding items, wherein the auxiliary oxidizer conduit (30) and the ignition fuel conduit (20) include the component (65) for igniting the ignition fuel.

[0300] Item 74: The burner (1) according to any one of the preceding items, wherein the component (65) for igniting the ignition fuel is an igniter tube.

[0301] Item 75: The burner (1) according to any one of the preceding items, wherein the secondary fuel conduit (50) includes a component (57) for generating turbulence.

[0302] Item 76: A burner (1) according to any one of the preceding items 1 to 74, wherein the secondary fuel conduit (50) includes a turbulence generator (57).

[0303] Item 77: The burner (1) according to Item 75 or 76, wherein the component for generating turbulence or the turbulence generator respectively comprises one or more turbulence generator disks.

[0304] Item 78: The burner (1) according to Item 75 or 76, wherein the component for generating turbulence or the turbulence generator respectively comprises one or more turbulence generator plates.

[0305] Item 79: The burner (1) according to Item 75 or 76, wherein the component for generating turbulence or the turbulence generator is arranged at the additional wall (58) of the secondary fuel conduit (50), the additional wall being positioned at the wall (49) of the main oxidant conduit (40).

[0306] Item 80: The burner (1) according to any one of the preceding items, wherein the auxiliary oxidizer conduit (30) further includes an air purge port (37).

[0307] Item 81: The burner (1) according to any one of the preceding items 1 to 79, wherein the main oxidant conduit (40) further includes an air purge port (37).

[0308] Item 82: The burner (1) according to Item 80 or 81, wherein the air purge hole (37) is located upstream of the cyclone section (42), preferably wherein the air purge hole (37) allows the oxidant to pass between the main oxidant conduit (40) and the auxiliary oxidant conduit (30).

[0309] Item 83: A burner (1) according to any one of the preceding items, wherein the primary oxidant comprises oxygen.

[0310] Item 84: A burner (1) according to any one of the preceding items, wherein the auxiliary oxidant comprises oxygen.

[0311] Item 85: A burner (1) according to any one of the preceding items, wherein the primary oxidant comprises oxygen and the secondary oxidant comprises oxygen.

[0312] Item 86: A burner (1) according to any one of items 56 or 58, wherein oxygen is included in the primary and / or secondary oxidant in an amount of 15% to 30% by volume.

[0313] Item 87: The burner (1) according to any one of the preceding items, wherein the primary oxidant is air.

[0314] Item 88: The burner (1) according to any one of the preceding items, wherein the auxiliary oxidant is air.

[0315] Item 89: The burner (1) according to any one of the preceding items, wherein the primary oxidant is air, and wherein the secondary oxidant is air.

[0316] Item 90: The burner (1) according to any one of the preceding items, wherein both the main oxidant conduit (40) and the auxiliary oxidant conduit (30) are connected to the same oxidant supply, preferably wherein both conduits are connected to the same oxidant supply using a control valve (60).

[0317] Item 91: The burner (1) according to any one of the preceding items, wherein the oxidant is air.

[0318] Item 92: The burner (1) according to any one of the preceding items, wherein each of the conduits is configured as a pipe.

[0319] Item 93: The burner (1) according to Item 92, wherein each of the conduits is configured as a pipe having a generally circular cross-section.

[0320] Item 94: A burner (1) according to any one of the preceding items, wherein all the said conduits are arranged substantially concentrically with each other.

[0321] Item 95: The burner (1) according to any one of the preceding items, wherein each of the conduits has a generally circular cross-section.

[0322] Item 96: The burner (1) according to any one of the preceding items, wherein the central main fuel injector (10) is designated as "injector 1".

[0323] Item 97: The burner (1) according to any one of the preceding items, wherein the central main fuel nozzle (10) is an air-assisted liquid fuel atomizing nozzle.

[0324] Item 98: The burner (1) according to any one of the preceding items 1 to 96, wherein the central main fuel nozzle (10) is a pressure atomizing liquid nozzle.

[0325] Item 99: A burner (1) according to any one of the preceding items, wherein a central main fuel injector (10) is arranged at the center of the burner (1), and in particular, wherein each of the other conduits is arranged concentrically around the central main fuel injector (10).

[0326] Item 100: The burner (1) according to any one of the preceding items, wherein the ignition fuel conduit (20) is designated as "pipe 1".

[0327] Item 101: A burner (1) according to any one of the preceding items, wherein the ignition fuel conduit (20) includes a plurality of discharge holes (22) for the ignition fuel, wherein the discharge holes (22) are arranged around the central main fuel nozzle (10).

[0328] Item 102: The burner (1) according to Item 101, wherein the discharge port (22) is located upstream of the main fuel outlet (14) of the central main fuel nozzle (10), in particular at a distance L1.

[0329] Item 103: The burner (1) according to any one of the preceding items, wherein the auxiliary oxidizer conduit (30) is designated as “pipe 2”, and in particular as an air conduit.

[0330] Item 104: A burner (1) according to any one of the preceding items, wherein the auxiliary oxidant conduit (30) is designed to provide oxidant to the ignition fuel, optionally wherein the auxiliary oxidant conduit (30) is designed to provide oxidant to the ignition fuel and to provide oxidant to the main fuel, particularly wherein the oxidant is provided continuously.

[0331] Item 105: A burner (1) according to any one of the preceding items, wherein the auxiliary oxidant is designated as "ignition air".

[0332] Item 106: The burner (1) according to any one of the preceding items, wherein the main oxidant conduit (40) is designated as “pipe 3”, and in particular as an air conduit.

[0333] Item 107: A burner (1) according to any one of the preceding items, wherein the main oxidizer conduit (40) includes a swirler section (42) configured such that air introduced into the swirler section (42) causes a strong tangential flow field in the combustion chamber, particularly wherein i) the mixing rate between the air, the primary fuel, and the secondary fuel is increased, and / or ii) a compact flame suitable for the short reaction chamber is created.

[0334] Item 108: The burner (1) according to any one of the preceding items, wherein the secondary fuel conduit (50) is designated as “pipe 4”, and in particular as a gas fuel conduit.

[0335] Item 109: The burner (1) according to any one of the preceding items, wherein the secondary fuel conduit (50) is an exhaust gas conduit, particularly an exhaust gas pipe, especially wherein the conduit is configured for exhaust gas, which is further defined according to any one of the preceding items 68 to 70.

[0336] Item 110: A burner (1) according to any one of the preceding items, wherein any one of D1, D2, D3, D4 and D5 described above is defined as the diameter of the respective conduit, preferably, all of the conduits having a substantially circular cross-section.

[0337] Item 111: A burner (1) according to any one of the preceding items, wherein any one of D1, D2, D3, D4 and D5 described above is defined as the diameter of the outlet of the respective conduit, preferably, all of the outlets having a substantially circular cross-section.

[0338] Item 112: A burner (1) according to any one of items 13 to 111, wherein i) L1 / D1 is between 1.0 and 10, particularly between 1.5 and 4; and / or ii) L2 / D2 is between 0.05 and 10, particularly between 0.1 and 0.5; and / or iii) L3 / D3 is between 0.05 and 10, particularly between 0.1 and 0.5.

[0339] Item 113: A burner (1) according to any one of items 13 to 112, wherein i) L1 / D1 is between 1.0 and 10, particularly between 1.5 and 4; and ii) L2 / D2 is between 0.05 and 10, particularly between 0.1 and 0.5; and iii) L3 / D3 is between 0.05 and 10, particularly between 0.1 and 0.5.

[0340] Item 114: A burner (1) according to any one of the preceding items, wherein all the conduits in the conduit share a common central axis.

[0341] Item 115: The burner (1) according to any one of the preceding items, wherein the central main fuel nozzle (10) is longer than the ignition fuel conduit (20), wherein the ignition fuel conduit (20) is longer than the auxiliary oxidizer conduit (30), wherein the auxiliary oxidizer conduit (30) is longer than the main oxidizer conduit (40), and wherein the main oxidizer conduit (40) is longer than the secondary fuel conduit (50).

[0342] Item 116: In any of the preceding items, the burner (1) of the secondary fuel conduit (50) is defined as the “hot surface” of the burner (1).

[0343] Item 117: The burner (1) according to any one of the preceding items, wherein all the conduits in the conduit are concentrically arranged around a common longitudinal axis at least in the downstream portion (5).

[0344] Item 118: A burner (1) according to any one of the preceding items, wherein all the conduits in the conduits are arranged concentrically around a common longitudinal axis.

[0345] Item 119: The burner (1) according to any one of the preceding items, wherein all the conduits in the conduit are substantially straight.

[0346] Item 120: The burner (1) according to any one of the preceding items, wherein the central main fuel injector (10) further includes a main fuel connector (11).

[0347] Item 121: The burner (1) according to any one of the preceding items, wherein the main oxidant conduit (40) further includes a main oxidant connector (41).

[0348] Item 122: The burner (1) according to any one of the preceding items, wherein the secondary fuel conduit (50) further includes a secondary fuel connector (51).

[0349] Item 123: The burner (1) according to any one of the preceding items, wherein the ignition fuel conduit (20) further includes an ignition fuel connector (21).

[0350] Item 124: The burner (1) according to any one of the preceding items, wherein the auxiliary oxidant conduit (30) further includes an auxiliary oxidant connector (31).

[0351] Item 125: A burner (1) according to any one of the preceding items, wherein the burner (1) comprises a configuration as described substantially in any of the figures or any combination thereof in the figures.

[0352] Item 126: A furnace comprising a burner (1) according to any one of items 1 to 125, wherein the furnace is selected from the group consisting of: furnaces for steam methane reforming, reheating furnaces in the steel industry, and secondary smelting furnaces.

[0353] Item 127: The furnace according to Item 126, wherein the furnace is further characterized by any of the features described in any of Items 1 to 125.

[0354] Item 128: A furnace as described in Items 126 or 127, wherein the furnace is further characterized by any additional features of the burner as defined elsewhere herein.

[0355] Item 129: A method for operating a burner (1) as defined in any one of Items 1 to 125 or a furnace as defined in any one of Items 126 and 127, the method comprising the steps of: i) starting the burner (1) using the ignition fuel, and ii) supplying and igniting the main fuel, the method optionally further comprising: iii) shutting off the flow of the ignition fuel, particularly wherein the flow is shut off after the main fuel has been ignited.

[0356] Item 130: The method according to Item 129, wherein the method further includes: further providing and igniting the secondary fuel.

[0357] Item 131: The method according to any one of items 129 and 130, wherein the secondary fuel is provided once it becomes available during the industrial process.

[0358] Item 132: The method according to any one of items 129 to 131, wherein the method further comprises the step of: continuing to supply and burn the ignition fuel as needed, particularly supplying and burning it at a low control ratio, so as to keep the flame of the main fuel stable.

[0359] Item 133: The method according to any one of items 129 to 131, wherein the method further comprises the step of: continuing to supply and burn the ignition fuel as needed, particularly for a liquid main fuel that is difficult to burn, so as to keep the flame of the main fuel stable.

[0360] Item 134: The method according to any one of items 129 to 133, wherein the method is further characterized by any of the features described in any one of items 1 to 125.

[0361] Item 135: The method according to any one of items 129 to 134, wherein the method is further characterized by any other features of the method as defined elsewhere herein. Example

[0362] The following examples are provided to further illustrate various aspects of the invention, but are by no means intended to limit it in any way.

[0363] Example 1 An example test burner (1) using air as the oxidant, #2 fuel oil as the liquid fuel, and a mixture of (H2, CO2, CH4) as the low BTU value exhaust gas fuel was designed, manufactured, and tested in a laboratory test furnace. The ignition fuel was natural gas, and 10% of the air from the primary air was used as ignition / secondary air.

[0364] Figure 6The graph showing flame length versus burner (1) combustion rate indicates that in a relatively cold furnace, under a wide range of operating conditions (start-up, full load during heating, 100% design combustion rate, and 50% control ratio, single-fuel operation, and dual-fuel operation), the flame length is approximately 2 / 3 of the furnace length. The average furnace wall temperature under these conditions ranges from 450 F to 830 F. The ratio of the mass flow rate of the atomized gas to the mass flow rate of the liquid fuel ranges from 0.025 to 0.5.

[0365] Figure 6 The curve showing flame length versus burner combustion rate indicates that, under a wide range of operating conditions, flame length (L) / D1 is approximately 60.0 or less. The ability of this burner to produce a short flame under wide operating conditions is attributed to several unique features. First, the combination of the low exhaust velocity of the fuel injector and the low-velocity ignition air near the injector helps anchor the liquid fuel flame in a cold furnace. The low exhaust velocity of the liquid fuel injector and the use of ignition or auxiliary air allow for a low axial momentum flux, which can be overcome by the tangential / radial momentum flux established by the swirl. Second, the turbulence generator in the exhaust duct helps increase the turbulence intensity of the secondary fuel flow, enabling an increased mixing rate between the secondary fuel and air, thus completing the secondary fuel combustion process over a short downstream distance. These unique design aspects of the burner, along with the specific velocity range of the fluid flow, contribute to enhanced oxidizer-fuel mixing, resulting in complete combustion over a short distance.

[0366] Example 2 In the following embodiments, a non-limiting exemplary detailed method of operating the burner (1) according to the invention is described (see also FIG5): Step 1: Start the primary air supply, which will also allow some airflow through the ignition air duct, igniting the ignition device located in the ignition fuel or air duct, and starting the ignition fuel. This ignites the ignition flame.

[0367] Step 2: Once the flame is ignited, the air-assisted liquid fuel flow is initiated. The heat release from the gas ignition fuel helps to ignite the liquid fuel. Furthermore, the primary oxidant (e.g., primary air) of the burner (1) helps to anchor the liquid fuel flame within the recirculation zone of the cyclone.

[0368] Step 3: Once the liquid fuel burner (1) has been ignited, shut off the ignition fuel supply. The design of the fuel injector and the burner (1) allows the liquid fuel to remain stably anchored while also producing a short flame suitable for small reactors. The combustion rate of the liquid fuel burner (1) reaches the desired flow rate.

[0369] Step 4: Once low BTU fuel is available from the equipment, it is introduced into the exhaust pipe. The liquid fuel burner (1) now acts as the ignition burner for the low BTU flame.

[0370] In step 1, the ignition flame is stable and reliably ignited in a cold furnace. The recess L1 of the ignition fuel conduit helps to partially premix the ignition fuel and ignition air. In addition, this recess allows for a robust anchoring position of the ignition flame next to the ignition fuel injection outlet (22), which is unaffected by the furnace atmosphere.

[0371] Furthermore, the ignition flame is well maintained even under cold furnace conditions at global equivalence ratios as low as 0.25. This low global equivalence ratio is due to the additional oxidizer supplied by the primary oxidizer conduit prior to the liquid fuel supply to the burner. This stable performance of the ignition flame is due to the unique configuration of the burner hardware, including the design of how the ignition fuel is injected through multiple orifices (22), the location of the ignition injection orifice recess length L1, the velocity ratio of the ignition fuel to the auxiliary fuel, and the volumetric flow rate ratio of the auxiliary oxidizer to the primary oxidizer. All these burner features allow for a zone in which partial ignition can be initiated and maintained while the composite fuel-air mixture remains below the global burner flammability limit of natural gas, which occurs at an equivalence ratio of approximately 0.48. Specifically, this is due to the way the ignition fuel is injected via different jets, which mix the fuel with auxiliary / ignition air to create multiple local fuel-air mixtures with equivalence ratios in the combustible zone, thus enabling reliable and repeatable ignition even if the composite gas mixture has a non-combustible fuel concentration. Furthermore, a portion of the primary air introduced into the auxiliary air duct (30) enters via the peripheral wall holes (37), allowing the development of local equivalence zones favorable for combustion in the recessed region L1.

[0372] The liquid fuel is ignited in step 2 and develops a stable flame in the cold furnace. This is possible because the ignition fuel is an integral part of the main burner and develops a symmetrical flame near the main fuel lance. The heat release from the ignition flame helps to reliably and safely ignite the liquid fuel.

[0373] As shown in step 3, the ignition flame operation can be stopped as needed. Without the aid of an ignition flame, the liquid fuel flame continues to produce a stable flame. Not intended to be theoretically constrained, the presence of low-velocity ignition air near the oil injector helps anchor the oil flame in the cold furnace. Additionally, the recessed ignition fuel tube of length L1 provides sufficient length for the ignition air to partially or fully develop before exiting the hot surface of the burner. This prevents any backflow of combustibles within fuel tube 1 when the ignition fuel is shut off.

[0374] For liquid fuels that are difficult to atomize and maintain a stable flame below their auto-ignition temperature, an ignition flame can be used for continuous operation to aid in the combustion of these difficult-to-burn liquid fuels (high viscosity, low Btu fuels, etc.). This benefit is unattainable with conventional external ignition burners, as they can lead to asymmetric effects in the flame, potentially resulting in uneven heat flux, flame impingement on the sidewalls, or, in the worst case, flame extinguishing when the ignition fuel is shut off. In this invention, the burner configuration allows the ignition flame to be symmetrical and concentric around the liquid nozzle. This allows for the provision of a reliable ignition source.

[0375] In addition, the ignition flame burner can also help operate liquid fuel lances at very low tune ratios by providing a continuous ignition source. This enables a wider operating range for liquid fuel burners.

[0376] The invention is characterized by igniting a flame to assist in the combustion of difficult-to-burn liquid fuels and forming a robust flame anchoring zone for fuels that do not require ignition, thereby allowing the burner to produce a stable flame (without any flaring) over a very wide range of equivalence ratios, even as low as 0.25. These features enable the preheating of the process furnace at a controlled rate, allowing the process to start up and reach steady-state conditions within the time frame dominated by process requirements. This operational aspect of the burner allows the use of the same burner for process heating with liquid fuels and eliminates the need for two separate burner systems for heating and steady-state furnace operation.

[0377] Total heat output is the sum of the heat output from the exhaust gas and the fuel supplied by liquid fuel. During equipment startup conditions, 100% of the heat output is supplied using liquid fuel. The heat from the liquid fuel is used to heat the equipment to the desired temperature.

[0378] Under normal operation of the burner (1), approximately 0 to 40% of the total heat output of the burner (1) is supplied by liquid fuel, and the remaining heat is supplied by gaseous exhaust fuel.

[0379] This burner is capable of producing a stable flame with a wide range of primary and secondary fuel distribution. Primary fuel can supply 5% to 100% of the total burner heat output, with the remainder coming from secondary fuel. The main reason for this flexibility is the strong flame anchoring zone of the primary fuel, provided by the atomized fuel jet and the low velocity of the ignition / auxiliary air, as discussed above, which allows for a reduction in primary fuel heat input, down to 5% of the total heat output.

[0380] Liquid fuel can be shut off if needed, and total heat output can be supplied via exhaust gas. The L2+L3 length fuel line recess allows ignition air to develop before it exits the hot side of the burner. Not intended to be theoretically constrained, this helps keep the fuel injector cool when liquid fuel is shut off by preventing hot gas from the combustion zone from impacting the nozzle's exhaust portion.

Claims

1. A burner (1), comprising A central main fuel nozzle (10) for supplying liquid fuel, the central main fuel nozzle having a main fuel outlet (14) at its downstream end. A main oxidant conduit (40) for supplying the main oxidant, the main oxidant conduit having a main oxidant outlet (44) at its downstream end. An ignition fuel conduit (20) for supplying gas ignition fuel, the ignition fuel conduit having an ignition fuel outlet (24) at its downstream end, and An auxiliary oxidant conduit (30) for supplying an auxiliary oxidant, the auxiliary oxidant conduit having an auxiliary oxidant outlet (34) at its downstream end. in, In at least the downstream portion (5) of the burner (1) in which the main fuel outlet (14), the main oxidizer outlet (44), the ignition fuel outlet (24), and the auxiliary oxidizer outlet (34) are present, the ignition fuel conduit (20), the auxiliary oxidizer conduit (30), and the main oxidizer conduit (40) are concentrically arranged around the central main fuel nozzle (10), such that the central main fuel nozzle (10) is surrounded by the ignition fuel conduit (20), the auxiliary oxidizer conduit (30), and the main oxidizer conduit (40). Wherein, at least in the downstream portion (5) of the burner (1), the central main fuel injector (10), the ignition fuel conduit (20) and the auxiliary oxidizer conduit (30) are surrounded by the main oxidizer conduit (40).

2. The burner (1) according to claim 1, wherein the burner further comprises A secondary fuel conduit (50) for supplying secondary fuel, the secondary fuel conduit having a secondary fuel outlet (54) at its downstream end. in, In at least the downstream portion (5) of the burner (1) in which the main fuel outlet (14), main oxidizer outlet (44), ignition fuel outlet (24), and auxiliary oxidizer outlet (34) are present, the secondary fuel conduits (50) are concentrically arranged around the central main fuel nozzle, and Furthermore, in at least the downstream portion (5) of the burner (1), the central main fuel nozzle (10), the ignition fuel conduit (20), the auxiliary oxidizer conduit (30) and the main oxidizer conduit (40) are completely or partially surrounded by the secondary fuel conduit (50).

3. The burner (1) according to claim 1, wherein i) The component (65) for igniting the ignition fuel is located inside the ignition fuel conduit (20) and / or the auxiliary oxidizer conduit (30), upstream of the main fuel outlet (14); and / or ii) At least in the downstream portion (5) of the burner (1), the central main fuel injector (10) and the ignition fuel conduit (20) are surrounded by the auxiliary oxidizer conduit (30).

4. The burner (1) according to claim 1, wherein the main oxidant conduit (40) in the downstream section of the burner (1) includes a cyclone section (42) upstream of the main oxidant outlet.

5. The burner (1) according to claim 1, wherein the outlet plane (25) of the ignition fuel outlet (24) is recessed by a distance L1 in the upstream direction from the outlet plane (15) of the main fuel outlet (14).

6. The burner (1) according to claim 5, wherein the central main fuel nozzle wall (19) has an outer diameter D1, and wherein L1 / D1 is between 0.5 and 15, preferably between 1.0 and 10, and particularly between 1.5 and 4.

7. The burner (1) according to claim 1, wherein the outermost conduit end plane (26 / 36) of the ignition fuel conduit (20) and the auxiliary oxidizer conduit (30) in the radial direction is recessed by a distance L2 from the conduit end plane (46) of the main oxidizer conduit (40) in the upstream direction.

8. The burner (1) according to claim 7, wherein the innermost of the ignition fuel conduit wall (29) and the auxiliary oxidant conduit wall (39) in the radial direction, preferably the ignition fuel conduit wall (29), has an outer diameter D2, and wherein L2 / D2 is between 0.05 and 10, preferably between 0.07 and 2, and particularly between 0.1 and 0.

5.

9. The burner (1) according to claim 2, wherein the conduit end plane (46) of the main oxidant conduit (40) is recessed by a distance L3 in the upstream direction from the conduit end plane (56) of the secondary fuel conduit (50).

10. The burner (1) according to claim 9, wherein the outermost of the ignition fuel conduit wall (29) and the auxiliary oxidant conduit wall (39) in the radial direction, preferably the auxiliary oxidant conduit wall (39), has an inner diameter D3, and wherein L3 / D3 is between 0.05 and 10, preferably between 0.07 and 2, and particularly between 0.1 and 0.

5.

11. The burner (1) according to claim 1, wherein the conduit end plane (16) of the main fuel nozzle (10) is substantially downstream of the conduit end plane (36) of the outermost conduit in the radial direction of the ignition fuel conduit (20) and the auxiliary oxidizer conduit (30).

12. The burner (1) according to claim 1, wherein The central main fuel spray gun wall (19) has an outer diameter D1, Of the ignition fuel conduit wall (29) and the auxiliary oxidizer conduit wall (39), the innermost one in the radial direction, preferably the ignition fuel conduit wall (29), has an outer diameter D2. The outermost of the ignition fuel conduit wall (29) and the auxiliary oxidizer conduit wall (39) in the radial direction, preferably the auxiliary oxidizer conduit wall (39), has an inner diameter D3, and The outer wall (49) of the main oxidant conduit (40) has an inner diameter D4. And among them i) D2 / D1 is between 1 and 2.5, especially between 1.7 and 2.2; and / or ii) D3 / D1 is between 2 and 4, especially between 2.5 and 3.3; and / or iii) D4 / D1 is between 3.5 and 6.5, especially between 4.5 and 6.

13. The burner (1) according to claim 2, wherein The outer wall (59) of the secondary fuel conduit (50) has an outer diameter D5, and wherein D5 / D1 is between 5 and 10, particularly between 5.6 and 7.

4.

14. The burner (1) according to claim 4, wherein the swirling angle, defined as the angle between the swirler blades and a plane parallel to the main axis of the burner (1), is 5 to 60 degrees, particularly 30 to 42 degrees.

15. The burner (1) according to claim 1, wherein the main oxidant conduit (40) further includes a discharge port (43), preferably wherein i) The diameter of the discharge port (43) is defined as P1, the outer diameter of the central main fuel injector wall is defined as D1, and P1 / D1 is between 0.02 and 0.2; and / or ii) The discharge port (43) is included in the annular region (48) of the discharge port. In particular, the annular region (48) of the discharge port is arranged in a fixed spatial relationship between the outermost part of the ignition fuel conduit wall (29) and the auxiliary oxidizer conduit wall (39) in the radial direction and between the cyclone section (42). Specifically, the annular discharge section of the discharge port includes a purge air plate (47) having a porosity in the range of 2% to 15% (defined by dividing the total open area on the plate that allows airflow by the cross-sectional area of ​​the plate).

16. The burner (1) according to claim 1, wherein the auxiliary oxidant conduit (30) further includes an air purge port (37), preferably wherein the air purge port (37) is located upstream of the cyclone section (42).

17. The burner (1) according to claim 1, wherein the ignition fuel conduit (20) discharge section further comprises a series of small discharge holes (22). In particular, among them i) The diameter of the discharge port (22) is defined as P0, the outer diameter of the central main fuel injector wall is defined as D1, and P0 / D1 is between 0.02 and 0.2; and / or ii) and / or the discharge orifice (22) is included in an ignition fuel discharge plate (23) having a porosity in the range of 2% to 25% (defined by the total open area on the plate allowing fuel flow divided by the cross-sectional area of ​​the plate); and / or iii) The discharge port (22) is arranged in a fixed spatial position to generate an ignition fuel jet.

18. The burner (1) according to claim 1, wherein the central main fuel nozzle (10) is an air- or other gas-assisted atomizing nozzle.

19. The burner (1) according to claim 1, wherein the secondary fuel conduit (50) includes a turbulence generator (57) upstream of its outlet plane (55), preferably immediately adjacent to its outlet plane (55).

20. The burner (1) according to claim 1, wherein i) The burner (1) is configured such that the velocity of the main oxidant at the main oxidant outlet is between 20 feet / second and 200 feet / second, particularly between 40 feet / second and 140 feet / second; and / or ii) The burner (1) is configured such that the velocity of the auxiliary oxidant at the auxiliary oxidant outlet is between 10 feet / second and 80 feet / second, particularly between 20 feet / second and 40 feet / second; and / or iii) The burner (1) is configured such that the velocity of the secondary fuel at the secondary fuel outlet is between 20 feet / second and 200 feet / second, particularly between 40 feet / second and 120 feet / second; and / or iv) The burner (1) is configured such that the velocity of the ignition fuel at the ignition fuel outlet (24) is between 30 feet / second and 250 feet / second, particularly between 60 feet / second and 120 feet / second.

21. A method of operating the burner (1) according to claim 1, wherein i) The burner (1) is operated such that, under startup conditions, the heat output of the ignition fuel is about 5-15% of the heat output of the main fuel, wherein the main fuel is preferably a liquid fuel; and / or ii) The burner (1) is operated such that the total start-up heat output of the burner (1) is provided to 100% by the main fuel, wherein the main fuel is preferably a liquid fuel; and / or iii) The burner (1) is operated such that during normal operation, the heat output of the main fuel is 0-40% of the total heat output of the burner (1); and / or iv) The volumetric flow rate of the auxiliary oxidant is about 5-20% of the total oxidant flow rate of the burner (1).

22. A method for operating a burner (1) according to any one of claims 1 to 17, the method comprising the following steps i) Start the burner (1) using the ignition fuel, wherein the ignition fuel is a gaseous fuel. ii) Provide and ignite the main fuel, wherein the main fuel is a liquid fuel. iii) Preferably, once the main fuel is ignited, the flow of the ignition fuel is shut off. In particular, the method further includes providing and igniting secondary fuel, especially wherein the secondary fuel is provided once it becomes available during the industrial process.

23. The method for operating a burner (1) according to claim 22, wherein the method comprises the additional steps of: continuing to supply and burn the ignition fuel as needed, particularly at a low control ratio and / or to aid the combustion of difficult-to-burn liquid fuels, in order to maintain flame stability of the main fuel.

24. The method according to claim 22 or 23, wherein the method is further characterized by any of the features outlined in any one of claims 1 to 21.

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