Combustor for fuel combustion and combustion method thereof

Abstract

The application discloses a burner for fuel combustion and a combustion method thereof. The burner comprises a primary oxidant-fuel delivery assembly, a secondary oxidant delivery assembly and a tertiary oxidant delivery assembly. The secondary oxidant delivery assembly and the tertiary oxidant delivery assembly are arranged on the same side of the primary oxidant-fuel delivery assembly, and the secondary oxidant delivery assembly is located between the tertiary oxidant delivery assembly and the primary oxidant-fuel delivery assembly. The application combines the staged and dilution combustion technologies, so that the burner has a wide flame adjustable range, realizes the adjustment of a flame combustion position, a flame speed range, a flame local atmosphere and a flame length, and can effectively reduce the generation of NOx, and meanwhile, a high heat transfer efficiency is achieved.

Description

Technical Field

[0001] This invention relates to a burner and combustion method for fuel combustion, and more particularly to a burner capable of producing segmented flames in a multi-stage configuration, which has lower NOx emissions when suitable for industrial furnaces. Background Technology

[0002] It is known in the art that, in industrial furnaces, oxy-fuel combustion offers lower investment costs, higher combustion efficiency, reduced NOx emissions, and higher product quality compared to conventional air combustion (e.g., used in the metallurgical or glass industries).

[0003] In the prior art, a typical staged oxygen-fuel burner has a fuel passage and an oxidizer passage. Oxygen staged combustion is used to divert a portion of the oxygen from the flame to delay combustion. The nozzle end of the burner produces a generally flat, fuel-rich flame. The staged nozzles introduce a portion of the oxidizer from below this fuel-rich flame, resulting in a lean flame due to the lower part of the fuel-rich flame being entrained.

[0004] Chinese patent CN1134610C discloses a typical staged burner. For example... Figure 1A As shown, a staged oxygen-containing fuel burner can produce a generally flat flame with a fuel-rich flame zone and a fuel-lean flame zone. The fuel passage of the burner terminates at the nozzle. Furthermore, similar staged burners can also be used... Figure 1B As shown, secondary or staged oxidizers still participate in staged combustion, which is far removed from the primary oxidizer-fuel combustion process. The limitation of this type of burner is that it is difficult to flexibly adjust the oxygen distribution and flame shape, and it is also difficult to achieve the desired oxidizing or reducing atmosphere in a specific area.

[0005] The prior art also discloses, such as Figure 2 The diagram shows a two-stage oxygen fuel burner. Chinese Patent CN108458339B describes this oxygen fuel burner as including a central conduit and an annular conduit, with fuel ejected from the central conduit and oxidizer ejected from the upper and lower conduits. However, this staged burner has a significant limitation in adjusting the atmosphere on the surface of the molten raw material, resulting in a limited flame adjustment range. If the amount of oxidizer ejected from the lower layer is reduced or shut off, the oxidizer concentrates in the middle and upper layers, thus limiting the staged combustion adjustment of the oxidizer.

[0006] Figure 3This is a schematic diagram of the fuel and oxygen injection state in a dilute oxygen combustion (DOC) burner, another existing technology, where fuel and oxygen are injected from separate nozzles. Although dilute oxygen burners can avoid localized high-temperature spots and produce a more uniform temperature distribution, to achieve a better reducing atmosphere, the oxygen and fuel injection nozzles must be kept at a considerable distance. This ensures that after the oxygen and fuel are injected at high speed and mixed for combustion, the exhaust gas can be entrained into the oxidant and fuel streams, allowing them to react again with the fuel / oxygen separately. This dilute oxygen combustion method requires extremely high fuel and oxidant injection velocities and a more complex control process, which makes it more difficult to achieve industrial application.

[0007] Based on the above discussion, the market needs a more efficient burner and combustion method to overcome these shortcomings. There is a desire to minimize the average velocity difference between the fuel and oxidizer flows during initial mixing. Improved furnace performance is also desired by operating burners with higher momentum and more stages to produce longer and more stable fuel-rich flames. Further improvements are needed to increase overall heat transfer rate, enhance furnace performance, reduce glass defects, and increase production output. Simultaneously, flexible control of the atmosphere in specific local areas is required to improve atmosphere adjustability and reduce nitrogen oxide (NOx) emissions. Summary of the Invention

[0008] The present invention aims to solve the following technical problems in the prior art: narrow adjustable range of flame rigidity, flame length and coverage area; limited range of flame combustion position and speed adjustment; limited space for adjusting local flame atmosphere, making it difficult to control the specific atmosphere in a designated area; difficulty in adapting to process requirements by changing the heat transfer coefficient (radiation and convection); inconvenient adjustment of oxygen concentration; poor adaptability to ignition temperature limits; and excessively high local flame temperature.

[0009] The purpose of this invention is to combine staged and dilution combustion technologies to enable the burner to have a wide range of flame adjustability, allowing for adjustments to the flame combustion position, flame velocity range, local flame atmosphere, and flame length, while effectively reducing NOx generation and achieving high heat transfer efficiency.

[0010] To achieve the above objectives, a first aspect of the present invention provides a burner for fuel combustion, comprising a burner body extending along an axial direction and forming a flame for heating an object at a front end face of the burner body, the burner body comprising: a primary oxidant-fuel delivery assembly, a secondary oxidant delivery assembly, and a tertiary oxidant delivery assembly.

[0011] The secondary oxidant delivery assembly and the tertiary oxidant delivery assembly are located on the same side of the primary oxidant-fuel delivery assembly, and the secondary oxidant delivery assembly is located between the tertiary oxidant delivery assembly and the primary oxidant-fuel delivery assembly;

[0012] The primary oxidizer-fuel delivery assembly includes:

[0013] At least one fuel supply passage for supplying fuel flow, one end of which is provided with a fuel nozzle; and

[0014] At least one primary oxidant supply passage for supplying primary oxidant flow, the primary oxidant supply passage being configured to surround the outer wall of the fuel supply passage, with an annular nozzle surrounding the fuel nozzle at one end;

[0015] The secondary oxidant delivery assembly includes at least one secondary oxidant supply passage for supplying secondary oxidant flow, and a secondary oxidant nozzle is provided at one end.

[0016] The aforementioned tertiary oxidant delivery assembly includes at least one tertiary oxidant supply passage for supplying tertiary oxidant flow, with a tertiary oxidant nozzle at one end. This arrangement can be such that the primary oxidant-fuel delivery assembly is located between the secondary oxidant delivery assembly and the molten surface of the heated material, while the tertiary oxidant delivery assembly is located between the secondary oxidant delivery assembly and the top of the furnace.

[0017] Furthermore, in at least one primary oxidant-fuel delivery assembly, the primary oxidant supply passage and the fuel supply passage are coaxially arranged.

[0018] Furthermore, the outlet ends of the secondary oxidant nozzle and the tertiary oxidant nozzle are disposed on the front end face of the burner body, and the secondary oxidant and the tertiary oxidant are respectively injected at each outlet end, and the secondary oxidant mixes with the fuel first before the tertiary oxidant.

[0019] Furthermore, at least one of the fuel nozzles sprays fuel along the axial direction of the burner body.

[0020] Furthermore, at least one of the fuel nozzles has a first inclined flow path at its front end, the first inclined flow path being inclined toward the secondary oxidizer nozzle.

[0021] Furthermore, at least one fuel nozzle and an annular nozzle surrounding the fuel nozzle are provided with a first horizontal diffusion angle α1 biased towards the outer side of the burner body. The first horizontal diffusion angle α1 ranges from 0 to 20°, preferably 0 to 10°, and more preferably 3° to 6°. The first horizontal diffusion angle α1 causes both the fuel ejected from the fuel nozzle and the primary oxidizer ejected from the annular nozzle to extend outwards from the burner body. The first horizontal diffusion angle α1 refers to the angle between the central axis of the fuel nozzle and the axial direction of the burner body, where "outer side of the burner body" refers to the area away from the center of the burner body.

[0022] Furthermore, the fuel supply passage is arranged coaxially with the fuel nozzle at its end, and has the first horizontal diffusion angle α1.

[0023] Furthermore, at least one of the secondary oxidant nozzles sprays secondary oxidant along the axial direction of the burner body.

[0024] Furthermore, at least one of the secondary oxidizer nozzles has a second inclined flow path at its front end, the second inclined flow path being inclined toward the fuel nozzle. By making the oxidizer flow path inclined, the injection direction of the oxidizer can be changed, and the shape of the flame can be flexibly changed according to the shape of the furnace and the characteristics of the heated object.

[0025] Furthermore, at least one of the secondary oxidizer nozzles is provided with a second horizontal diffusion angle α2 biased towards the outside of the burner body. The second horizontal diffusion angle α2 ranges from 0 to 15°, preferably from 0 to 10°, and more preferably from 3° to 8°. The second horizontal diffusion angle α2 causes the secondary oxidizer ejected from the secondary oxidizer nozzle to extend outward from the burner body. The second horizontal diffusion angle α2 refers to the angle between the central axis of the secondary oxidizer nozzle and the axial direction of the burner body when the secondary oxidizer nozzle is projected onto the XY plane where the primary oxidizer-fuel delivery assembly is located.

[0026] Furthermore, at least one of the secondary oxidant supply passages is arranged coaxially with the secondary oxidant nozzle at its end, having a second horizontal diffusion angle α2.

[0027] Furthermore, at least one of the aforementioned tertiary oxidant nozzles sprays tertiary oxidant along the axial direction of the burner body.

[0028] Furthermore, at least one of the aforementioned three-stage oxidizer nozzles has a third inclined flow path at its front end, the third inclined flow path being inclined toward the fuel nozzle.

[0029] Furthermore, at least one of the three-stage oxidizer nozzles is provided with a third horizontal diffusion angle α3 biased towards the outer side of the burner body. The third horizontal diffusion angle α3 ranges from 0 to 15°, preferably from 2° to 10°, and more preferably from 4° to 10°. The third horizontal diffusion angle α3 causes the three-stage oxidizer ejected from the three-stage oxidizer nozzle to extend outward from the burner body. Specifically, the third horizontal diffusion angle refers to the angle between the central axis of the three-stage oxidizer nozzle and the axial direction of the burner body when the three-stage oxidizer nozzle is projected onto the XY plane where the primary oxidizer-fuel delivery assembly is located.

[0030] Furthermore, at least one of the aforementioned tertiary oxidant supply passages is arranged coaxially with the tertiary oxidant nozzle at its end, having a third horizontal diffusion angle α3.

[0031] Furthermore, at least one of the fuel nozzles is provided with a first vertical angle β1 biased towards the secondary oxidizer nozzle, and the angle β1 ranges from 0 to 10°, preferably from 0 to 3°. The first vertical angle β1 refers to the angle between the central axis of the fuel nozzle and the axial direction of the burner body when the fuel nozzle is projected onto the XZ plane.

[0032] Furthermore, at least one of the aforementioned primary oxidizer-fuel delivery components further includes: a first adjusting connector for connecting the fuel supply passage and its fuel nozzle, and capable of adjusting the fuel nozzle to have a first horizontal diffusion angle α1 and / or a first vertical angle β1 as needed. This first adjusting connector may include, but is not limited to, a universal joint, a bellows, or similar connecting mechanisms, which allow the fuel supply passage to be attached to the fuel nozzle, having a range of rotation to allow the fuel nozzle to have a preferred or default first horizontal diffusion angle α1 and / or first vertical angle β1.

[0033] Furthermore, at least one of the secondary oxidizer nozzles is provided with a second vertical angle β2 biased towards the primary oxidizer-fuel delivery assembly, and the range of β2 is 0~20°, preferably 0~10°, more preferably 2°~7°. The second vertical angle causes the secondary oxidizer ejected from the secondary oxidizer nozzle to deflect towards the primary oxidizer-fuel delivery assembly. Specifically, the second vertical angle refers to the angle between the central axis of the secondary oxidizer nozzle and the axial direction of the burner body when the secondary oxidizer nozzle is projected onto the vertical plane XZ of the XY plane containing the primary oxidizer-fuel delivery assembly.

[0034] Furthermore, at least one of the said secondary oxidant supply passages is arranged coaxially with the secondary oxidant nozzle at its end, having a second vertical angle β2.

[0035] Furthermore, the secondary oxidant delivery assembly further includes a second adjusting connector for connecting the secondary oxidant supply passage and its secondary oxidant nozzle, and for adjusting the second horizontal diffusion angle α2 and / or the second vertical angle β2 of the secondary oxidant nozzle. This second adjusting connector may include, but is not limited to, a universal joint, a bellows, or similar connecting mechanisms, which allow the secondary oxidant supply passage to be attached to the secondary oxidant nozzle, having a range of rotation to allow the fuel nozzle to have a preferred or default second horizontal diffusion angle α2 and / or second vertical angle β2.

[0036] Furthermore, at least one of the three-stage oxidizer nozzles is provided with a third vertical angle β3 biased towards the primary oxidizer-fuel delivery assembly, and the range of β3 is 0~20°, preferably 0~9°. This third vertical angle causes the three-stage oxidizer ejected from the three-stage oxidizer nozzle to deflect towards the primary oxidizer-fuel delivery assembly. Specifically, the third vertical angle β3 refers to the angle between the central axis of the three-stage oxidizer nozzle and the axial direction of the burner body when the three-stage oxidizer nozzle is projected onto the vertical plane XZ of the XY plane containing the primary oxidizer-fuel delivery assembly.

[0037] Furthermore, at least one of the aforementioned tertiary oxidant supply passages is arranged coaxially with the tertiary oxidant nozzle at its end, having a third vertical angle.

[0038] Furthermore, the three-stage oxidizer delivery assembly also includes a third adjusting connector for connecting the three-stage oxidizer supply passage and its three-stage oxidizer nozzle, and capable of adjusting the third horizontal diffusion angle α3 and / or the third vertical angle β3 of the three-stage oxidizer nozzle as needed. This third adjusting connector may include, but is not limited to, a universal joint, a bellows, or similar connecting mechanisms, which allow the three-stage oxidizer supply passage to be attached to the three-stage oxidizer nozzle, having a range of rotation to allow the fuel nozzle to have a preferred or default third horizontal diffusion angle α3 and / or third vertical angle β3.

[0039] Furthermore, the burner also includes an oxidant grading control mechanism that independently controls the oxidant flow rate in the primary oxidant supply path, the secondary oxidant supply path, and the tertiary oxidant supply path.

[0040] Furthermore, the primary oxidant-fuel delivery assembly, the secondary oxidant delivery assembly, and the tertiary oxidant delivery assembly are integrated into the same burner brick body, or are distributed and assembled in different burner brick bodies.

[0041] Furthermore, the primary oxidant-fuel delivery assembly, the secondary oxidant delivery assembly, and the tertiary oxidant delivery assembly are arranged sequentially from bottom to top.

[0042] Furthermore, the fuel nozzle, annular nozzle, secondary oxidant nozzle, and tertiary oxidant nozzle are each in any one of the following shapes: circular, elliptical, square, or irregular.

[0043] Furthermore, in the primary oxidant-fuel delivery assembly, the at least one fuel supply passage is configured to include a first fuel supply passage and a second fuel supply passage, wherein the first fuel supply passage is nested inside the corresponding second fuel supply passage, and the first fuel and the second fuel are each independently selected from solid fuel, liquid fuel or gaseous fuel.

[0044] A second aspect of the present invention provides a combustion method for a burner used for fuel combustion, employing a flame formed by at least one of the burners described above, the method comprising:

[0045] Fuel and primary oxidant surrounding the fuel are introduced through a primary oxidant-fuel delivery assembly, and the two are mixed near the front end face of the burner body and then injected into the combustion space together. The amount of primary oxidant provided is less than the amount of oxidant required for complete combustion of the fuel, so as to produce a primary mixture of primary combustion products and incompletely burned fuel.

[0046] The secondary oxidant is introduced through the secondary oxidant delivery component, so that the primary mixture and the secondary oxidant come into contact and mix at a set location, and combustion occurs to produce a secondary mixture;

[0047] A tertiary oxidant is introduced through a tertiary oxidant delivery assembly, which comes into contact with and mixes with the secondary mixture, causing combustion and forming the final combustion products.

[0048] Furthermore, the primary oxidant accounts for 1-20% of the total oxidant flow rate, with a preferred range of 1-15% and an optimal range of 2-5%, all measured by volumetric flow rate; the secondary oxidant flow rate accounts for 5-70% of the total oxidant flow rate, with a preferred range of 10-50% and an optimal range of 15-30%, all measured by volumetric flow rate; and the tertiary oxidant flow rate accounts for 5-90% of the total oxidant flow rate, with a preferred range of 20-80% and an optimal range of 50-75%, all measured by volumetric flow rate.

[0049] Furthermore, the injection velocity of the primary oxidant is set to 0.5 ~ 30 m / s, the injection velocity of the fuel is set to 5 ~ 130 m / s, the injection velocity of the secondary oxidant is set to 2.5 ~ 80 m / s, and the injection velocity of the tertiary oxidant is set to 5 ~ 160 m / s, forming a flame, and using the flame to heat the object being heated.

[0050] The burner and combustion method provided by this invention have the following advantages:

[0051] The burner provided by this invention delivers fuel and oxidant in a highly staged manner, achieving low NOx emissions and atmosphere control near the surface of the heated object.

[0052] By adjusting the speed, flow rate, and distribution of each stage of oxidant, the burner provided by this invention can better control the dilution degree of oxidant and hot flue gas in the furnace, adjust the length and rigidity of the flame, and adjust the flame coverage area.

[0053] This burner can effectively control the furnace temperature and avoid unwanted local overheating.

[0054] This burner can enhance thermal efficiency and yield, help to create stronger convection in the heated material, promote more complete removal of impurities, and improve product quality.

[0055] This burner can reduce costs, is easy to manufacture into an integrated burner, and reduces the space occupied by the burner. Attached Figure Description

[0056] The advantages and spirit of the present invention can be further understood from the following detailed description of the invention and the accompanying drawings.

[0057] Figure 1A This is a schematic diagram of the layout of a staged burner disclosed in Chinese Patent No. CN1134610C.

[0058] Figure 1B This is a schematic diagram of another typical staged burner layout in the prior art.

[0059] Figure 2 This is a schematic diagram of the layout of a two-stage oxygen fuel burner disclosed in Chinese Patent No. CN108458339B.

[0060] Figure 3 This is a schematic diagram of the fuel and oxygen ejection state of another dilute oxygen combustion (DOC) burner in the prior art.

[0061] Figure 4 This is a schematic cross-sectional view (XZ plane direction) of an exemplary burner of the present invention having a total fuel inlet and a total oxidizer inlet.

[0062] Figure 5 A schematic diagram illustrating the principle of the burner involved in this invention is shown.

[0063] Figure 6A The diagram shows cross-sectional views of the nozzle outlet ends of the burner involved in this invention; Figure 6B A three-dimensional view of the burner is shown.

[0064] Figure 7 This is a cross-sectional schematic diagram of an exemplary primary fuel-oxidant delivery assembly of the present invention in the XY plane direction.

[0065] Figure 8 This is a schematic projection of an exemplary secondary oxidant delivery assembly 20 of the present invention in the XY plane direction.

[0066] Figure 9 This is a schematic projection of an exemplary three-stage oxidant delivery assembly 30 of the present invention in the XY plane direction.

[0067] Figure 10A and Figure 10B This is a schematic projection of an exemplary burner of the present invention in the XZ plane direction.

[0068] Figure 11 A schematic cross-sectional view showing the defined angles of each oxidant supply passage, an exemplary embodiment of the present invention.

[0069] Figure 12 The diagram shows a top view of the burner of Embodiment 1 of the present invention installed in an aluminum smelting furnace.

[0070] Figure 13 A three-dimensional schematic diagram of the burner according to Embodiment 1 of the present invention is shown.

[0071] Figure 14A It shows, as Figure 1B The diagram shows a color chart illustrating the NOx concentration distribution produced by a staged burner. Figure 14B The diagram shows a color chart illustrating the NOx concentration distribution when the burner of Embodiment 1 of the present invention is configured inside an aluminum smelting furnace.

[0072] Figure 15 The burner of Embodiment 1 of the present invention and such Figure 1B The diagram shows a comparison of the volumetric flow rate of nitrogen oxides at the outlet of an industrial furnace for a staged burner.

[0073] Figure 16 The burner of Embodiment 1 of the present invention is shown, and as shown in the figure. Figure 1B The comparison of the adjustability of the in-furnace flame length of the staged burners is shown.

[0074] Figure 17 A schematic diagram of a burner with an exemplary configuration of the present invention, comprising multiple fuel nozzles, is shown.

[0075] Explanation of reference numerals in the attached drawings: 1. Burner body; 2. Burner brick; 3. Burner metal part; 10. Primary oxidizer-fuel delivery assembly; 11. Fuel supply passage; 111. Primary oxidizer supply passage; 12. Annular nozzle; 121. Secondary oxidizer delivery assembly; 20. Secondary oxidizer supply passage; 21. Secondary oxidizer nozzle; 211. Tertiary oxidizer delivery assembly; 30. Tertiary oxidizer supply passage; 31. Tertiary oxidizer nozzle; 311. First fuel injection pipe; 422. First fuel inlet end; 426. Second fuel inlet end; 427. Fuel outlet end; 424. Second fuel injection pipe; 425. Detailed Implementation

[0076] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0077] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the purpose of simplifying the description of this invention and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0078] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0079] Unless otherwise clearly indicated, each aspect or embodiment defined herein may be combined with any other aspect or embodiment. In particular, any feature indicated as preferred or advantageous may be combined with any other feature indicated as preferred or advantageous.

[0080] In this article, "the axial direction of the burner body" refers to a direction roughly parallel to the axis of rotation, axis of symmetry, or centerline of the burner body, and generally refers to the fuel delivery direction in the primary oxidizer-fuel delivery assembly. For example, in Figure 13 The direction along or parallel to the X-axis in the XY plane shown is the axial direction of the burner body. Correspondingly, the Y-axis direction can be determined as the direction orthogonal to the X-axis. The Z-axis direction can be determined according to the right-hand screw rule.

[0081] In this article, "outer side of the burner body" refers to the direction that extends outward from the center of the burner body as a whole.

[0082] As used in this article, "surrounding" or "encircling" basically refers to the shape of the ring, roughly meaning that the inner ring is enclosed within the outer ring, thus creating a certain gap between the inner and outer layers. This gap can be annular or non-annular. As used herein, it can refer to the primary oxidizer supply passage surrounding a portion of the circumference of the fuel supply passage (e.g., more than half), or it can refer to the primary oxidizer supply passage surrounding the entire circumference of the fuel supply passage. The latter can be understood as the primary oxidizer supply passage completely surrounding the circumference of the fuel supply passage in the circumferential direction. The design of fuel nozzles and annular nozzles can be understood similarly.

[0083] As used in this article, "staged" refers to mixing fuel and oxidizer at different times and locations to achieve low nitrogen oxide emissions and controlled gas atmosphere near the molten surface. Staged means that oxidizer can be supplied at different proportions or flow rates through other nozzles spaced apart from the fuel nozzle. For example, when the staged ratio of secondary to tertiary oxidizer is 95%, it means that the remaining 5% of the oxidizer is supplied with the primary oxidizer-fuel delivery assembly along with the fuel.

[0084] As used herein, "fuel" refers to gaseous, liquid, or solid fuels that can be used interchangeably or in combination. Gaseous fuels can be natural gas (primarily methane), propane, hydrogen, or any other hydrocarbon compound and / or sulfur-containing compound. Solid or liquid fuels can be any compound that is primarily carbon-containing and / or hydrocarbon and / or sulfur-containing. Those skilled in the art can determine the manner in which gaseous, liquid, or solid fuels are introduced as needed, and this invention is not intended to impose any limitations. Some of the data presented herein uses natural gas as fuel, but the results are considered applicable to other fuels, such as hydrogen and other gaseous fuels.

[0085] As used herein, "oxidant" may consist of an oxidant such as air or oxygen-enriched air. The oxidant stream preferably consists of an oxidant with an oxygen molar concentration of at least 50%, preferably at least 80%, more preferably at least 90%, and most preferably at least 95%. These oxidants include oxygen-enriched air containing at least 50% by volume oxygen, 99.5% pure oxygen produced by a cryogenic air separator, or non-pure oxygen (88% by volume or more) produced by a vacuum pressure swing adsorption process, or oxygen produced from any other source.

[0086] In this paper, the use of oxygenated fuels can eliminate nitrogen in the melting process and reduce NOx and particulate emissions below standards. Oxygenated fuel burners can achieve different flame momentum, melt coverage, and flame radiation characteristics. Within the furnace, nitrogen primarily originates from air leakage, low-purity oxygen supplied from vacuum pressure swing adsorption (PSA) or PSA units, nitrogen in the fuel (e.g., natural gas), or nitrogen contained in the molten feedstock.

[0087] As used herein, the term "nozzle" may have several different meanings. Generally, in this specification, a nozzle can be understood as the terminal conical portion of an atomizing spray system from which the spray is ultimately expelled. See, for example, Merriam-Webster's Dictionary definition of a nozzle: a short tube having a conical or tapered portion for accelerating or guiding a stream of fluid, as in a hose. In this specification, "nozzle" refers to the component located at the end of a burner that supplies fuel and oxidizer for combustion.

[0088] As used herein, the fuel supply passage, primary oxidant supply passage, secondary oxidant supply passage, and tertiary oxidant supply passage can be substantially annular channels, or a section of area having one inlet and one outlet. When viewed in cross-section from a plane perpendicular to the axial flow direction, the substantially annular passages are preferably annular, but this shape can also be non-annular.

[0089] In this article, the term "combustion surface" can be understood as being built on the front end surface of the burner brick, where the annular nozzle, secondary oxidizer nozzle, and tertiary oxidizer nozzle can terminate.

[0090] Figure 4A schematic cross-sectional (XZ section) view of an exemplary burner of the present invention, having a total fuel inlet and a total oxidizer inlet, is shown. The burner metal component 3 can be a metal body inserted into a generally cuboid-shaped burner brick 2, together forming part of the burner body. The burner metal component 3 is configured with a total fuel inlet, a total oxidizer inlet, an oxidizer grading control mechanism, and spaced channels. The oxidizer grading control mechanism and the spaced channels allow fuel or oxidizer to be delivered proportionally to the fuel supply passage 11, the primary oxidizer supply passage 12, the secondary oxidizer supply passage 21, and the tertiary oxidizer supply passage 31.

[0091] Fuel is supplied through the main fuel inlet to the fuel supply passage 11, which terminates at the fuel nozzle 111. The fuel nozzle 111 may be circular or non-circular with a certain aspect ratio. All oxidant is supplied through the main oxidant inlet to the burner metal component 3, where an oxidant grading control mechanism proportionally distributes the main oxidant to at least one of the primary oxidant supply passage 12, the secondary oxidant supply passage 21, and the tertiary oxidant supply passage 31. Figure 4 The primary oxidant supply passage 12 shown is for the flow of primary oxidant, surrounds the outer wall of the fuel supply passage 11, and is coaxial with the fuel supply passage 11. One end of the primary oxidant supply passage 12 is provided with an annular nozzle 121 surrounding the fuel nozzle 111.

[0092] The oxidant staged control mechanism can be a staged distribution valve, which can be installed in the burner nozzle metal part. Its function is to transfer the oxidant in stages from the burner metal part to the various oxidant supply passages for distribution. The oxidant staged control mechanism can include a primary oxidant control valve, a secondary oxidant control valve, and a tertiary oxidant control valve.

[0093] The fuel supply passage can be a fuel conduit made of a suitable material (e.g., high-temperature resistant metal or ceramic). The starting end of the fuel conduit is detachably connected to the burner metal component, or it can be integrally formed. The outlet end of the fuel conduit is connected to the fuel nozzle. Each oxidant supply passage can be an oxidant supply conduit made of a specific material (e.g., high-temperature resistant metal or ceramic), or it can be a cavity or passage formed in the burner brick with a corresponding shape. In the latter case, the burner metal component is inserted into the starting portion of the corresponding cavity or passage in the burner brick, allowing the oxidant to flow within these cavities or passages.

[0094] The secondary oxidant delivery assembly 20 includes a secondary oxidant supply passage 21 for secondary oxidant flow, and a secondary oxidant nozzle 211 is provided at its end.

[0095] The tertiary oxidant delivery assembly 30 includes a tertiary oxidant supply passage 31 for tertiary oxidant flow, and a tertiary oxidant nozzle 311 is provided at its end.

[0096] The fuel supply passage 11, the secondary oxidant supply passage 21 and the tertiary oxidant supply passage 31 are arranged sequentially from bottom to top in the Z-axis direction.

[0097] The total oxidant can be divided into three streams: a primary oxidant stream, a secondary oxidant stream, and a tertiary oxidant stream. The primary oxidant stream surrounds the fuel nozzle and its volumetric flow rate accounts for only a small proportion of the total oxidant, preferably less than 20%, less than 10%, less than 5%, or about 2% to 5%. The remaining oxidant is distributed as the secondary and tertiary oxidant streams. This is equivalent to a preferred grading ratio of at least 10%, at least 20%, at least 40%, at least 50%, at least 60%, or even at least 70%, respectively. This means that sufficient oxidant flows through the secondary or tertiary oxidant supply path, or is distributed between the two supply paths, for grading. This not only reduces NOx generation but also significantly improves the ability to control the gas atmosphere adjacent to the molten surface of the heated material. To control the atmosphere adjacent to the molten surface and selectively oxidize or reduce according to process conditions, it is desirable to be able to easily switch the burner operation. This can be achieved by independently controlling the oxidant flow rate (i.e., streams) in the primary, secondary, and tertiary oxidant supply paths using an oxidant grading control mechanism. Each oxidant stream is independent of the others, thus enabling precise combustion control.

[0098] It should be noted that a zero primary oxidant stream is undesirable, as it creates voids or vacuum in the primary oxidant supply path, drawing in hot, corrosive furnace gases that quickly damage the burner and cause flame instability. Furthermore, an insufficient primary oxidant stream reduces flame stability and worsens the mixing of gaseous fuel and oxidant, making it difficult to achieve a practical flame. In some cases, the secondary or tertiary oxidant streams can approach zero. In such cases, the burner is essentially close to or equivalent to a two-stage burner, and the corresponding combustion effects and characteristics can be predicted and adjusted according to the knowledge of those skilled in the art.

[0099] As an example, an annular nozzle 121 surrounds the fuel nozzle 111, and the outlet end of the annular nozzle 121 can terminate at the front end face of the burner body to form a flame that heats the object being heated. The front end face of the burner body can also be referred to as the "combustion face" or "hot face". The injection port of the fuel nozzle 111 can be recessed into the combustion face by about 2 cm to 5 cm. This arrangement allows the fuel and primary oxidant to mix near the combustion face and form a more stable flame.

[0100] Figure 5 The schematic diagram illustrates the principle of the burner involved in this invention. Industrial furnaces such as metallurgical furnaces or glass melting furnaces typically place molten raw materials or other materials to be heated in the lower part of the furnace, and form a flame in the upper space of the furnace, heating or melting the materials through thermal radiation from the flame.

[0101] In this embodiment, the tertiary oxidant and the secondary oxidant are located above each other on the same side of the fuel-primary oxidant. Typically, the primary and secondary oxidants contact the fuel stream before the tertiary oxidant, forming a fuel-rich flame and producing a fuel-rich combustion mixture, which may contain some combustion products, unreacted fuel, and oxidant. The cracking of this fuel-rich combustion mixture enhances soot formation, which is more conducive to the formation of a luminous flame.

[0102] In some cases, glass melting furnaces often require high flame intensity. In such situations, a faster-injected secondary oxidizer results in more rapid combustion. This is because it often leads to more rapid mixing of fuel and oxidizer, thereby shortening the flame length and causing a rapid rise in local temperature. Those skilled in the art will understand that various methods can be used to achieve the desired oxidizer injection rate, and this invention is not intended to be limiting, nor is it limited to adjusting the oxidizer flow rate, adjusting the oxidizer nozzle size, or adjusting the oxidizer temperature.

[0103] In some cases, such as in aluminum smelting furnaces, a longer flame length is often required to improve heat transfer efficiency. This can be addressed by further increasing the injection velocity of the tertiary oxidant to a suitable range. The high-speed injection of the tertiary oxidant further dilutes the mixture of the first two stages of combustion products, and the tertiary oxidant is further entrained into the surrounding atmosphere, which facilitates a longer flame length while simultaneously reducing NOx formation.

[0104] Figure 6A and 6B In the middle, to and Figure 4 The same structural parts of the burner shown are labeled with the same reference numerals. Figure 6A and 6B A typical burner design according to the first embodiment of the present invention is shown, wherein Figure 6A The diagram shows cross-sectional views of the nozzle outlet ends of the burner. Figure 6B A perspective view of the burner is shown. The burner is divided into three zones: zone A, zone B, and zone C. The burner body 1 includes a primary oxidizer-fuel delivery assembly 10 located in zone C, a secondary oxidizer delivery assembly 20 located in zone B, and a tertiary oxidizer delivery assembly 30 located in zone A. The burner brick 2, which is approximately rectangular in shape, can be made of various refractory materials. The front end face of the burner brick 2 can form the end face of the entire burner body.

[0105] The primary oxidant-fuel delivery assembly 10 is spaced apart from the secondary oxidant delivery assembly 20 and the tertiary oxidant delivery assembly 30. The secondary oxidant delivery assembly 20 and the tertiary oxidant delivery assembly 30 are located on the same side, i.e., the upper side, of the primary oxidant-fuel delivery assembly 10. The secondary oxidant delivery assembly 20 is located between the tertiary oxidant delivery assembly 30 and the primary oxidant-fuel delivery assembly 10.

[0106] Each oxidizer nozzle can terminate at the combustion surface of the burner brick 2. The outlet end of the fuel nozzle 111 can be recessed into the combustion surface by about 2cm to 5cm, meaning it can terminate prematurely at a certain distance from the combustion surface. This arrangement allows the fuel and primary oxidizer to mix near the combustion surface, forming a more stable flame. If termination occurs too early, and the distance between the outlet end of the fuel nozzle and the combustion surface is less than 2cm, the mixing time between the fuel and primary oxidizer is too short, resulting in poor mixing; if it is greater than 5cm, excessively rapid combustion leading to localized overheating can easily damage the burner.

[0107] Figure 7 This is a schematic cross-sectional view of the exemplary primary fuel-oxidant delivery assembly of the present invention in the XY plane. At least one fuel nozzle 111 and an annular nozzle 121 surrounding the fuel nozzle are simultaneously provided with a first horizontal diffusion angle α1 offset towards the outside of the burner body. This ensures that both the fuel ejected from the fuel nozzle 111 and the primary oxidant ejected from the annular nozzle 121 extend outwards from the burner body, resulting in a wider flame coverage. The first horizontal diffusion angle α1 refers to the angle between the central axis of the fuel nozzle 111 and the axial direction of the burner body. Here, "outside the burner body" refers to the side away from the center of the burner body. The first horizontal diffusion angle α1 is 0~20°, preferably 0~10°, more preferably 3°~6°. When the first horizontal diffusion angle α1 of a fuel nozzle is zero, the direction of the ejected fuel is substantially along the axial direction of the burner body.

[0108] In a primary oxidizer-fuel delivery assembly, when the primary oxidizer supply passage 12 and the annular nozzle 121 are coaxial with the surrounding fuel supply passage 11 and fuel nozzle 111, respectively, they have the same first horizontal diffusion angle α1. Those skilled in the art will understand that the fuel nozzle 111 and the annular nozzle 121 can be configured to be on different axes, as long as the annular nozzle always surrounds the fuel nozzle.

[0109] Exemplarily, each fuel nozzle can be configured to have a different or the same first horizontal diffusion angle biased towards the outside of the burner body, depending on the situation. Exemplarily, the fuel supply passage 11 is arranged coaxially with the fuel nozzle 111 at its end, that is, it also has the aforementioned first horizontal diffusion angle. Of course, for ease of manufacturing, the fuel supply passage 11 and the fuel nozzle 111 can be fixedly connected and integrally formed.

[0110] Figure 8 This is a schematic projection of an exemplary secondary oxidant delivery assembly 20 of the present invention in the XY plane. According to... Figure 8 As shown, the two sets of secondary oxidizer nozzles 211 are each provided with a second horizontal diffusion angle α2 that is biased towards the outside of the burner body. This makes the spray plane of the secondary oxidizer ejected from the secondary oxidizer nozzle 211 wider, the flame coverage wider, and more conducive to the formation of a flat flame. The second horizontal diffusion angle α2 refers to the angle between the central axis of the secondary oxidizer nozzle 211 and the axial direction of the burner body when the secondary oxidizer nozzle 211 is projected onto the XY plane where the primary oxidizer-fuel delivery assembly is located. As those skilled in the art know, each secondary oxidizer nozzle can be configured to have different or the same second horizontal diffusion angle biased towards the outside of the burner body, as needed.

[0111] The second horizontal diffusion angle α2 ranges from 0 to 15°, preferably from 0 to 10°, and more preferably from 3 to 8°. If the second horizontal diffusion angle is greater than 15°, it will result in an excessively low local oxidant concentration and incomplete combustion. Alternatively, the second horizontal diffusion angle of the secondary oxidant supply passage 21 and the secondary oxidant nozzle 211 connected thereto can be zero.

[0112] For example, at least one secondary oxidant supply passage 21 may be arranged coaxially with the secondary oxidant nozzle 211 at its end, both having a second horizontal diffusion angle α2.

[0113] Figure 9 This is a schematic projection of an exemplary three-stage oxidant delivery assembly 30 of the present invention in the XY plane. According to... Figure 9The arrangement shown depicts two sets of three-stage oxidizer nozzles 311 each with a third horizontal diffusion angle α3 offset towards the outer side of the burner body. This results in a wider spray plane for the three-stage oxidizer ejected from the nozzles 311, a larger flame coverage area, and is more conducive to forming a flat flame. The third horizontal diffusion angle α3 refers to the angle between the central axis of the three-stage oxidizer nozzle 311 and the axial direction of the burner body when projected onto the XY plane. As is known to those skilled in the art, each three-stage oxidizer nozzle can be configured with different or the same third horizontal diffusion angle offset towards the outer side of the burner body, as needed.

[0114] The third horizontal diffusion angle α3 ranges from 0 to 15°, preferably from 2° to 10°, and more preferably from 4° to 10°. If the third horizontal diffusion angle is greater than 15°, it will result in an excessively low local oxidant concentration and incomplete combustion. Alternatively, the third horizontal diffusion angle of the tertiary oxidant supply passage 31 and its connected secondary oxidant nozzle 311 can be zero.

[0115] By way of example, at least one tertiary oxidant supply passage 31 may also be arranged coaxially with the tertiary oxidant nozzle 311 at its end, both having a third horizontal diffusion angle α3.

[0116] Figure 10A and Figure 10B This is a schematic projection of an exemplary burner of the present invention in the XZ plane. The first vertical angle β1 of the fuel nozzle located in zone C ranges from 0 to 10°, preferably from 0 to 3°. Here, the first vertical angle β1 refers to the angle between the central axis of the fuel nozzle and the axial direction of the burner body when the fuel nozzle is projected in the XZ plane. β1 being zero indicates that the injection direction of the fuel nozzle is substantially consistent with the axial direction of the burner body. β1 being greater than 0° allows the overall injection direction of the fuel nozzle to bring the fuel closer to or more towards the secondary oxidizer nozzle. Setting β1 between 0 and 10° is beneficial for the injection direction of the fuel nozzle to be more offset towards the secondary oxidizer nozzle. If β1 exceeds 10°, the secondary and tertiary oxidizers will prematurely contact and mix with the fuel, failing to maintain the required flame length.

[0117] Each secondary oxidizer nozzle 211 located in zone B is also provided with a different or the same second vertical angle β2 along the Z-axis towards the primary oxidizer-fuel delivery assembly, causing the secondary oxidizer ejected from the secondary oxidizer nozzle 211 to deflect towards the primary oxidizer-fuel delivery assembly. The second vertical angle refers to the angle between the central axis of the secondary oxidizer nozzle 211 and the axial direction of the burner body when the secondary oxidizer nozzle is projected onto the vertical plane XZ of the XY plane containing the primary oxidizer-fuel delivery assembly. The second vertical angle β2 is less than 20°, preferably 0~10°, and more preferably 2°~7°. If the second vertical angle β2 is greater than 20°, it will cause the secondary oxidizer to prematurely contact and mix with the fuel, resulting in undesirable premature combustion.

[0118] As is known to those skilled in the art, each secondary oxidizer nozzle can be configured as needed to have different or the same second vertical angle β2 biased along the Z-axis toward the primary oxidizer-fuel delivery assembly. Furthermore, at least one secondary oxidizer supply passage 21 can also be arranged coaxially with its end secondary oxidizer nozzle 211, all having a second vertical angle β2.

[0119] The three-stage oxidizer nozzles 311 located in area A are each provided with the same or different third vertical angles β3 biased towards the primary oxidizer-fuel delivery assembly, causing the three-stage oxidizer ejected from the three-stage oxidizer nozzles 311 to deflect towards the primary oxidizer-fuel delivery assembly. The third vertical angle refers to the angle between the central axis of the three-stage oxidizer nozzle 311 and the axial direction of the burner body when the three-stage oxidizer nozzle 311 is projected onto the vertical plane XZ of the XY plane containing the primary oxidizer-fuel delivery assembly.

[0120] The third vertical angle β3 can be 0° to 20°, preferably 0° to 9°. If β3 is greater than 20°, it will cause the tertiary oxidant to come into contact with and mix with the fuel too early, making it impossible to maintain the flame length, and the flame will not spread further on the molten surface to form an effective heating flame.

[0121] Furthermore, depending on the circumstances, each tertiary oxidant nozzle 311 can be configured with a different or the same third vertical angle biased along the Z-axis toward the primary oxidant-fuel delivery assembly.

[0122] Furthermore, at least one tertiary oxidant supply passage 31 can be arranged coaxially with its end tertiary oxidant nozzle 311, both having a third vertical angle.

[0123] Figure 11A schematic cross-sectional view showing the defined angles of each oxidizer supply passage is provided. When the secondary oxidizer supply passage 21 and the tertiary oxidizer supply passage 31 are projected onto the XZ plane where the primary oxidizer-fuel delivery assembly is located, the intersection positions of the extended lines of the injection directions of the secondary and tertiary oxidizer nozzles with the axial direction of the burner body (which can also be understood as the axial direction of the primary oxidizer-fuel delivery assembly) are shown. These are hereinafter referred to as the third intersection position and the second intersection position. The second intersection position is closer to the burner metal parts, i.e., closer to the combustion surface, than the third intersection position. Assume the direction of fuel and primary oxidizer injection is P1, the direction of secondary oxidizer injection is P2, and the direction of tertiary oxidizer injection is P3.

[0124] This can be illustrated more vividly by the following relationship: The distance d3 (i.e., d2 / tgβ2) between the third intersection position and the combustion surface > the distance d4 (i.e., d1 / tgβ3) between the second intersection position and the combustion surface > the distance d5 between the corresponding intersection position of the primary oxidizer supply path and the combustion surface, i.e., d3 > d4 > d5. Here, d1 represents the distance between the center of the secondary oxidizer supply path and the center of the fuel supply path, and d2 represents the distance between the center of the tertiary oxidizer supply path and the center of the fuel supply path.

[0125] By way of example only, a burner may be provided with three sets of primary oxidant-fuel delivery assemblies, two sets of secondary oxidant delivery assemblies and two sets of tertiary oxidant delivery assemblies. Those skilled in the art will know that the number of each set of assemblies and the parameters of each assemblies can be selected according to the size of the industrial furnace, the type of molten material, the flame control requirements, etc.

[0126] The cross-sectional shape of each oxidant supply passage can be different, and can be circular, elliptical, square, or irregular. Furthermore, the fuel nozzle, annular nozzle, secondary oxidant nozzle, and tertiary oxidant nozzle can each be any one of the following shapes: circular, elliptical, square, or irregular.

[0127] The burner brick material can be selected from milk-colored brick material or other high-temperature resistant alloy materials. This all-oxygen burner can be applied in a variety of industrial fields, such as non-ferrous metals (e.g., aluminum industry), glass, cement, and ceramics. Because this burner can produce a flame with a neutral or reducing atmosphere at the bottom, and has a large flame coverage area, longer flame length, more uniform flame temperature, and no prominent local hot spots, it is particularly suitable for metallurgical furnaces such as those used in non-ferrous metals (e.g., aluminum smelting).

[0128] In the burner of this invention, the oxidizer and fuel will come into contact and mix in a reasonable manner within the furnace to complete the combustion process:

[0129] 1) The fuel supply passage on one side (e.g., the lower part) of the burner is surrounded by a primary oxidant supply passage, which accounts for only a small proportion of the total oxidant. The fuel and primary oxidant are mixed near the front end face of the burner body and then injected into the combustion space together to produce a primary mixture of primary combustion products and incompletely burned fuel.

[0130] 2) The primary mixture of primary combustion products and incompletely burned fuel from the previous step will first encounter the secondary oxidant at a suitable location, producing a secondary mixture. The combustion rate after this encounter is jointly controlled by the flow rate of each stream and the stoichiometric ratio of fuel to oxidant.

[0131] 3) The tertiary oxidant is ejected from another oxygen supply passage on the other side of the burner (e.g., the upper part), and after contacting the secondary mixture, it burns and forms the final combustion products.

[0132] Secondary and tertiary oxidizers can be mixed with fuel at predetermined angles and locations, thereby enabling control of flame temperature and luminosity, as well as combustion rate and reduction of nitrogen oxide (NOx) formation.

[0133] The various streams used in this burner can be configured with fuel injection velocities ranging from 5 to 130 m / s, primary oxidizer injection velocities ranging from 0.5 to 30 m / s, secondary oxidizer injection velocities ranging from 2.5 to 80 m / s, and tertiary oxidizer injection velocities ranging from 5 to 160 m / s. The suitable burner power load range is 0.6 to 5 MW.

[0134] In embodiments of this invention, the fuel can be a solid fuel, a gaseous fuel, or a liquid fuel. Solid fuels can be selected from petroleum coke, pulverized coal, biomass pellets, or other fossil fuels. Solid fuels generally require a carrier gas (e.g., air or carbon dioxide) to form a conveying airflow for transport. Liquid fuels can be selected from liquid hydrocarbons or coal tar. Gaseous fuels can be selected from natural gas, hydrogen, or other hydrocarbon gases. Chinese invention patent CN109489038B, entitled "A Burner with Adjustable Multiple Fuel Feed Ratios," is incorporated herein by reference in its entirety. The burner of this invention can also be equipped with multiple fuels, and the combustion effect can be controlled by adjusting the feed ratio of each fuel. It is particularly suitable for using hydrogen as a gaseous fuel. This invention can significantly alter the flame emissivity by controllably introducing solid or liquid fuel at the center of the hydrogen fuel, thereby significantly improving the direct heat transfer effect of the flame to the molten surface and reducing the water content in the combustion exhaust gas.

[0135] For example, it can be as follows Figure 17As shown, the first fuel inlet 426 and the second fuel inlet 427 can introduce different types of fuel. Each first fuel injection pipe 422 is fitted inside a corresponding second fuel injection pipe 425. Both the first fuel and the second fuel are ultimately ejected through the fuel outlet 424. The first fuel and the second fuel flow in their respective pipes, wherein the second fuel can flow in an annular pipe defined by the outer wall of the first fuel injection pipe and the inner wall of the second fuel injection pipe.

[0136] The primary fuel can be a solid, gaseous, or liquid fuel. Solid fuels can be selected from petroleum coke, pulverized coal, biomass pellets, or other fossil fuels, and generally require a carrier gas for air-powder transport. Liquid fuels can be selected from liquid hydrocarbons or coal tar. Surrounding the gaseous fuel stream with the solid fuel in a ring shape can make the flame brighter and improve combustion. Fuels with high ignition points (such as conventional liquid or solid fuels) or high calorific values ​​are generally used as the primary fuel. When using biomass gasification or coal gasification, these lower calorific value and less stable fuels are often preferred as the secondary fuel, while high-calorific-value natural gas is chosen as the primary fuel.

[0137] The second fuel can be a gaseous fuel. When hydrogen is used as the second fuel, the flame is almost invisible in the high-temperature furnace due to the characteristics of the hydrogen flame. When a solid or liquid fuel is used as the primary fuel located at the center, the flame's emissivity changes dramatically, and the direct heat transfer effect of the flame on the heated object is significantly improved.

[0138] Example 1

[0139] The burner of this invention is applied to an industrial furnace with a length of 5 meters and a width of 3 meters. The combustion rate of the burner is approximately 500 kW (common range 400~700 kW). The burner includes a primary oxidant-fuel delivery assembly, a secondary oxidant delivery assembly, and a tertiary oxidant delivery assembly. Figure 12 The diagram shows a top view of the burner of the present invention installed in an industrial furnace.

[0140] Figure 13 A perspective view of the burner in this embodiment is shown. In the primary oxidant-fuel delivery assembly, three sets of fuel nozzles 111 are provided. The first horizontal diffusion angle α1 of the two outer sets of fuel nozzles 111 is 5°, facing outwards from the burner body. The first horizontal diffusion angle of the fuel nozzle 111 in the middle position is zero. Each annular nozzle is configured accordingly around the surrounding fuel nozzles. In the secondary oxidant delivery assembly, two sets of secondary oxidant nozzles 211 are provided with a second vertical angle β2 of 6°, facing the fuel nozzles 111, and a second horizontal diffusion angle α2 of 5°, facing outwards from the burner.

[0141] In the three-stage oxidizer delivery assembly, the third vertical angle β3 of the two sets of three-stage oxidizer nozzles 311 is set to 8°, facing the fuel nozzle 111. The third horizontal diffusion angle α3 is set to 5°, facing the outside of the burner.

[0142] After entering the burner through the main fuel inlet, the fuel is evenly distributed to the three fuel supply passages 11 by the burner metal component 3. After entering through the main oxidant inlet, the oxidant is distributed to the three oxidant delivery assemblies by the oxidant grading control mechanism in the burner metal component 3, and finally injected into the combustion space.

[0143] The combustion reaction rate is jointly controlled by the rate of the mixed stream and the fuel / oxidant stoichiometric ratio. In this embodiment, the primary oxidant accounts for 5% of the total oxidant flow rate. The fuel and primary oxidant are mixed near the front end of the burner body before being injected into the combustion space. The secondary oxidant accounts for 30% of the total oxidant flow rate. After being injected, it meets and mixes with the primary mixture at a certain location in the furnace. The tertiary oxidant accounts for 65% of the total oxidant flow rate. After being injected, it mixes with the mixture from the first two stages of combustion in the furnace, completing the combustion process.

[0144] After normalizing the NOx concentration distribution in the aforementioned industrial furnace, as follows: Figure 14B As shown, and in the background art as Figure 1B The NOx concentration distribution of the staged burner shown is as follows: Figure 14A As shown in the diagram, the lighter the color of the color scale representing NOx concentration distribution, the higher the NOx concentration. It can be seen that the NOx concentration in the industrial furnace using the burner of this invention is significantly lower. The long flame generated by the burner in this embodiment forms a large coverage area on the surface of the heated material, and the overall flame temperature is uniform without localized overheating. We can consider this flame to be closer to a reducing atmosphere with the heated material. This type of flame is particularly suitable for aluminum smelting furnaces, as it has high heat transfer efficiency for aluminum smelting materials, preventing oxidation or volatilization of materials due to localized overheating, and thus reducing NOx generation.

[0145] In the background technology, such as Figure 1B The staged burner shown is different from the burner in the embodiment of the present invention. Different staged oxygen ratios are set, and the NOx volume concentration in the combustion products is tested. Figure 15 As shown. Apart from the difference in burner structure, the combustion space dimensions, maximum combustion space temperature, furnace pressure (the pressure measurement value during combustion in the kiln flame space), oxygen-fuel ratio, and other external environmental conditions are all the same.

[0146] Utilize Figure 1BThe staged burner shown was tested in three groups: a, b, and c, with the primary oxidant ratios set to approximately 35%, 20%, and 5%, respectively. After normalization, the NOx volume concentrations in the combustion products of the flame region for groups a, b, and c were approximately 1.30, 1.00, and 0.78, respectively. Using the burner shown in the embodiment of the invention, three groups: d, e, and f were tested, with the sum of the primary and secondary oxidant ratios set to approximately 40%, 25%, and 15%, respectively. After normalization, the NOx volume concentrations in the combustion products of the flame region for groups d, e, and f were approximately 0.91, 0.62, and 0.30, respectively. It can be concluded that with similar stage ratios, the formation of nitrogen oxides in the burner of the present invention is significantly reduced in the furnace space, especially in the flame region, by approximately 30%, 38%, and 61%, respectively.

[0147] Among them, in such Figure 1B In the staged burner shown, the proportion of primary oxidant is about 35%, and in the burner shown in the embodiment of the present invention, the sum of the proportions of primary oxidant and secondary oxidant is about 40%, and the combustion effect achieved is basically a shorter flame, higher brightness, and larger flame radiation coefficient.

[0148] In such Figure 1B In the staged burner shown, the proportion of primary oxidant is about 5% or even lower. In the burner shown in the embodiment of the present invention, the sum of the proportions of primary oxidant and secondary oxidant is about 15% or even lower. The combustion effect achieved is basically a longer flame, a larger flame coverage area, and good flame temperature uniformity. Under these conditions, the amount of NOx generated by combustion is lower.

[0149] In such Figure 1B In the staged burner shown, the proportion of primary oxidant is 20%, and in the burner shown in the embodiment of the present invention, the sum of the proportions of primary oxidant and secondary oxidant is approximately 25%, achieving a combustion effect between the two cases mentioned above.

[0150] In the background art, such as Figure 1B Compared to the staged burner shown, the primary, secondary, and tertiary oxidants are set to gradually move away from the fuel flow. This ensures that the primary and secondary oxidants are initially mixed with the fuel flow to stabilize the flame. The resulting fuel-rich unburned products are then mixed with the tertiary oxidant to carry out a full oxidation-reduction reaction, achieving the effects of a large flame coverage area, uniform flame temperature, and low NOx emissions.

[0151] Taking an experimental furnace with a width of 3 meters as an example, regarding the background technology such as Figure 1B The staged burner shown is different from the burner in this embodiment. Figure 16 This demonstrates a comparison of the adjustability of the flame length within the furnace for these two types of burners. Maintaining the same furnace pressure, natural gas was used as fuel, and pure oxygen as the oxidant. The burners were positioned on the end wall of the industrial furnace (e.g., Figure 12 As shown in the image, each burner has a combustion rate of approximately 500 kW. Tests have shown that... Figure 1B The adjustable flame length range of the staged burner shown is 0.9 to 1.9 meters, while the adjustable flame length range of the burner in this embodiment is 0.8 to 2.75 meters. It can be seen that the burner provided by this invention has a wide flame adjustment range, which can meet the needs of different production loads, raw materials, and product properties, and other changing production conditions.

[0152] In summary, the burner provided by this invention employs a multi-stage fuel-oxidizer combustion technology. The primary and secondary oxidizers react with the fuel to form a fuel-rich flame. The fuel-rich mixture pyrolyzes the fuel, enhancing soot generation to create a luminous flame. Further reducing the primary oxidizer flow rate and increasing the secondary oxidizer flow rate (or velocity) will increase the flame length. Further increasing the tertiary oxidizer velocity to an appropriate range will result in an even longer flame, thereby reducing NOx formation and achieving higher heat transfer efficiency. By controlling the distribution ratio of the primary, secondary, and tertiary oxidizers, the flame length and coverage area can be adjusted, controlling localized oxidizing or reducing atmospheres, and the flame direction can be adjusted according to product process requirements.

[0153] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A burner for fuel combustion, characterized in that, The burner includes a burner body extending along an axial direction, and a flame for heating an object is formed on the front end face of the burner body. The burner body includes: There is one and only one primary oxidizer-fuel delivery assembly. There is one and only one secondary oxidant delivery assembly and There is one and only one tertiary oxidant delivery assembly; The secondary oxidant delivery assembly and the tertiary oxidant delivery assembly are located on the same side of the primary oxidant-fuel delivery assembly, and the secondary oxidant delivery assembly is located between the tertiary oxidant delivery assembly and the primary oxidant-fuel delivery assembly. The primary oxidizer-fuel delivery assembly includes: At least one fuel supply passage for supplying fuel flow, one end of which is provided with a fuel nozzle; and At least one primary oxidant supply passage for supplying primary oxidant flow, the primary oxidant supply passage being configured to surround the outer wall of the fuel supply passage, one end of which is provided with an annular nozzle surrounding the fuel nozzle; The secondary oxidant delivery assembly includes at least one secondary oxidant supply passage for supplying secondary oxidant flow, and a secondary oxidant nozzle is provided at one end. The aforementioned three-stage oxidant delivery assembly includes at least one three-stage oxidant supply passage for supplying three-stage oxidant flow, and one end of which is provided with a three-stage oxidant nozzle.

2. The burner as claimed in claim 1, characterized in that, In at least one primary oxidant-fuel delivery assembly, the primary oxidant supply passage and the fuel supply passage are arranged coaxially.

3. The burner as described in claim 1, characterized in that, The outlet ends of the secondary oxidizer nozzle and the tertiary oxidizer nozzle are located on the front end face of the burner body. The secondary oxidizer and the tertiary oxidizer are respectively sprayed at each outlet end, and the secondary oxidizer mixes with the fuel first before the tertiary oxidizer.

4. The burner as claimed in claim 1, characterized in that, At least one of the fuel nozzles has a first inclined flow path at its front end, the first inclined flow path being inclined toward the secondary oxidizer nozzle.

5. The burner as claimed in claim 1, characterized in that, At least one of the fuel nozzles and the annular nozzle surrounding the fuel nozzle are provided with a first horizontal diffusion angle α1 that is biased toward the outside of the burner body, wherein the first horizontal diffusion angle α1 is in the range of 0° to 20°.

6. The burner as claimed in claim 1, characterized in that, At least one of the fuel nozzles and the annular nozzle surrounding the fuel nozzle are provided with a first horizontal diffusion angle α1 that is biased toward the outside of the burner body, wherein the first horizontal diffusion angle α1 is in the range of 3° to 6°.

7. The burner as claimed in claim 5, characterized in that, The fuel supply passage is arranged coaxially with the fuel nozzle at its end and has the first horizontal diffusion angle α1.

8. The burner as claimed in claim 1, characterized in that, At least one of the secondary oxidant nozzles has a second inclined flow path at its front end, the second inclined flow path being inclined toward the fuel nozzle.

9. The burner as claimed in claim 1, characterized in that, At least one of the secondary oxidant nozzles is provided with a second horizontal diffusion angle α2 that is biased toward the outside of the burner body, the second horizontal diffusion angle α2 being in the range of 0 to 15°.

10. The burner as claimed in claim 1, characterized in that, At least one of the secondary oxidant nozzles is provided with a second horizontal diffusion angle α2 that is biased toward the outside of the burner body, and the second horizontal diffusion angle α2 is in the range of 3° to 8°.

11. The burner as claimed in claim 9, characterized in that, At least one of the secondary oxidant supply passages is arranged coaxially with the secondary oxidant nozzle at its end, having a second horizontal diffusion angle α2.

12. The burner as claimed in claim 1, characterized in that, At least one of the three-stage oxidizer nozzles has a third inclined flow path at its front end, the third inclined flow path being inclined toward the fuel nozzle.

13. The burner as claimed in claim 1, characterized in that, At least one of the three-stage oxidant nozzles is provided with a third horizontal diffusion angle α3 that is biased towards the outside of the burner body, and the third horizontal diffusion angle α3 is in the range of 0~15°.

14. The burner as claimed in claim 1, characterized in that, At least one of the three-stage oxidant nozzles is provided with a third horizontal diffusion angle α3 that is biased towards the outside of the burner body, and the third horizontal diffusion angle α3 is in the range of 4° to 10°.

15. The burner as claimed in claim 13, characterized in that, At least one of the aforementioned tertiary oxidant supply passages is arranged coaxially with the tertiary oxidant nozzle at its end, having a third horizontal diffusion angle α3.

16. The burner as claimed in claim 1, characterized in that, At least one of the fuel nozzles is provided with a first vertical angle β1 biased toward the secondary oxidizer nozzle, and the range of β1 is 0 to 10°.

17. The burner as claimed in claim 1, characterized in that, At least one of the secondary oxidizer nozzles is provided with a second vertical angle β2 biased toward the primary oxidizer-fuel delivery assembly, and the range of β2 is 0 to 20°.

18. The burner as claimed in claim 1, characterized in that, At least one of the secondary oxidizer nozzles is provided with a second vertical angle β2 biased toward the primary oxidizer-fuel delivery assembly, and the range of β2 is 2° to 7°.

19. The burner as claimed in claim 17, characterized in that, At least one of the said secondary oxidant supply passages is arranged coaxially with the secondary oxidant nozzle at its end, having a second vertical angle β2.

20. The burner as claimed in claim 1, characterized in that, At least one of the three-stage oxidizer nozzles is provided with a third vertical angle β3 biased toward the primary oxidizer-fuel delivery assembly, and the range of β3 is 0 to 20°.

21. The burner as claimed in claim 20, characterized in that, At least one of the aforementioned tertiary oxidant supply passages is arranged coaxially with the tertiary oxidant nozzle at its end, having a third vertical angle β3.

22. The burner as claimed in claim 1, characterized in that, The burner also includes an oxidant graded control mechanism that independently controls the oxidant flow in the primary oxidant supply path, the secondary oxidant supply path, and the tertiary oxidant supply path.

23. The burner as claimed in claim 1, characterized in that, In the primary oxidant-fuel delivery assembly, the at least one fuel supply passage is configured to include a first fuel supply passage and a second fuel supply passage, wherein the first fuel supply passage is nested inside the corresponding second fuel supply passage, and the first fuel and the second fuel are each independently selected from solid fuel, liquid fuel or gaseous fuel.

24. A combustion method for a burner used for fuel combustion, characterized in that, A flame is formed using a burner according to any one of claims 1-23, the combustion method comprising: Fuel and primary oxidant surrounding the fuel are introduced through a primary oxidant-fuel delivery assembly, and the two are mixed near the front end face of the burner body and then injected into the combustion space together. The amount of primary oxidant provided is less than the amount of oxidant required for complete combustion of the fuel, so as to produce a primary mixture of primary combustion products and incompletely burned fuel. The secondary oxidant is introduced through the secondary oxidant delivery component, so that the primary mixture and the secondary oxidant come into contact and mix at a set location, and combustion occurs to produce a secondary mixture; A tertiary oxidant is introduced through a tertiary oxidant delivery assembly, which comes into contact with and mixes with the secondary mixture, causing combustion and forming the final combustion products.

25. The combustion method as described in claim 24, characterized in that, All are measured by volumetric flow rate ratios. The primary oxidant accounts for 1-20% of the total oxidant flow rate; the secondary oxidant accounts for 5-70% of the total oxidant flow rate; and the tertiary oxidant accounts for 5-90% of the total oxidant flow rate.

26. The combustion method as described in claim 24, characterized in that, All are measured by volumetric flow rate ratios. The primary oxidant accounts for 2% to 5% of the total oxidant flow rate; the secondary oxidant accounts for 15% to 30% of the total oxidant flow rate; and the tertiary oxidant accounts for 50% to 75% of the total oxidant flow rate.

27. The combustion method as described in claim 24, characterized in that, The primary oxidant is injected at a velocity of 0.5 to 30 m / s, the fuel is injected at a velocity of 5 to 130 m / s, the secondary oxidant is injected at a velocity of 2.5 to 80 m / s, and the tertiary oxidant is injected at a velocity of 5 to 160 m / s, forming a flame, which is then used to heat the object being heated.

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