Low-nitrogen burner

Abstract

The application provides a low-nitrogen burner compatible with blast furnace gas and natural gas, and belongs to the technical field of low-nitrogen combustion of industrial kiln and furnace, and comprises a burner brick, a heat storage component and a natural gas lance; the burner brick is provided with a gas injection port, an air injection port and a natural gas injection port; the gas injection port and the air injection port are arranged at intervals along a first direction; the air injection port and the natural gas injection port are arranged at intervals along a second direction perpendicular to the first direction; the heat storage component is provided with a channel for the combustion-supporting air and the blast furnace gas to flow through, and is used for absorbing the heat of the kiln and furnace to heat the gas; the natural gas lance is communicated with the natural gas injection port. During combustion, the combustion-supporting air, the blast furnace gas and the natural gas are mixed and mixed at a position far away from the burner brick and entrain the kiln flue gas, so that the reaction intensity is reduced. The low-nitrogen burner provided by the application realizes delayed mixing and flue gas entrainment by using heat storage preheating and jet space separation, reduces the emission of thermal NOx, is compatible with blast furnace gas and natural gas, and is stable, efficient and reliable in combustion.

Description

Technical Field

[0001] This invention belongs to the field of burner technology, and more specifically, relates to a low-NOx burner. Background Technology

[0002] Currently, both domestic and international regulations on flue gas emissions from industrial furnaces and kilns are becoming increasingly stringent, particularly regarding NOx emissions. Burners, as the core heating equipment in industrial furnaces and kilns, bear the heavy responsibility of reducing NOx emissions. This is especially true for regenerative annular furnaces, where furnace temperatures can reach up to 1300℃ and the regenerated air temperature reaches approximately 1100℃, making NOx emission reduction particularly challenging. Regenerative furnaces and kilns must save energy for users while simultaneously reducing atmospheric pollutant emissions, thus presenting burner design with stringent requirements.

[0003] In existing low-NOx burner technologies, staged combustion technology or flue gas recirculation technology are commonly used to reduce NOx emissions. The core purpose is to reduce the combustion reaction rate and minimize the temperature difference between different temperature zones.

[0004] However, while staged combustion technology shows significant nitrogen reduction effects below 1000℃, it still achieves nitrogen reduction at temperatures above 1000℃, resulting in high NOx emissions. In regenerative annular furnaces, where temperatures exceed 1000℃, large amounts of thermal NOx are generated, making the nitrogen reduction effects of traditional staged combustion or flue gas recirculation technologies particularly limited. Summary of the Invention

[0005] The purpose of this application is to provide a low-NOx burner to solve the problem that in the prior art, when the furnace temperature of a regenerative furnace is higher than 1000℃, the nitrogen reduction effect of traditional burners is limited, resulting in high NOx emissions.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: A low-NOx burner is provided, comprising: Burner bricks are used to install on kilns; the burner bricks have gas nozzles, air nozzles and natural gas nozzles on the side facing the kiln; the gas nozzles and air nozzles are arranged at intervals along a first preset direction, and the air nozzles and natural gas nozzles are arranged at intervals along a second preset direction, and the first preset direction is perpendicular to the second preset direction; A heat storage component is disposed on the burner brick; the heat storage component has channels through which combustion air and blast furnace gas flow, and the heat storage component is respectively connected to the gas nozzle and the air nozzle; the heat storage component is used to absorb heat from the kiln to heat the flowing gas; and A natural gas nozzle, used to allow natural gas to pass through and be ejected, and connected to the natural gas nozzle; Wherein, after the combustion air and the blast furnace gas, or the combustion air and the natural gas, or the combustion air, the blast furnace gas and the natural gas are injected into the kiln, they converge and mix at a position away from the burner bricks, and the mixed gas is suitable for stirring and entraining the flue gas in the kiln, so as to reduce the intensity of the combustion reaction and reduce the emission of thermal NOx.

[0007] In one possible implementation, there are two gas nozzles, and the air nozzle is located between the two gas nozzles; the heat storage assembly includes three heat storage elements, one of which is used to introduce the combustion air and is connected to the air nozzle; the other two heat storage elements are used to introduce the blast furnace gas and are connected to the two gas nozzles one-to-one.

[0008] In one possible implementation, the gas nozzle adopts a long, flat structure.

[0009] In one possible implementation, there are multiple natural gas nozzles, and the multiple natural gas nozzles are arranged at intervals along the first preset direction; there are multiple natural gas nozzles, and each nozzle corresponds to and is connected to one of the multiple natural gas nozzles.

[0010] In one possible implementation, the natural gas nozzle axis has a first included angle α relative to the horizontal plane, the first included angle α being in the range of 0° to 10°.

[0011] In one possible implementation, the axis of the air nozzle is parallel to the horizontal plane; the number of air nozzles is multiple, and the multiple air nozzles are arranged in a rectangular array.

[0012] In one possible implementation, the axis of one of the gas nozzles forms a second included angle β with the axis of the air nozzle, the second included angle β ranging from 10° to 20°; the axis of the other gas nozzle forms a third included angle γ with the axis of the air nozzle, the third included angle γ ranging from 0° to 10°. The values ​​of the second included angle β and the third included angle γ are different.

[0013] In one possible implementation, the heat storage element includes: A housing, mounted on the burner brick, is internally used for introducing the combustion air or the blast furnace gas, and is connected to the air nozzle or the gas nozzle; and A ceramic honeycomb structure is filled inside the box and has a multi-layered breathable structure. The ceramic honeycomb structure is used to exchange heat with the kiln and heat the gas flowing through the box.

[0014] In one possible implementation, the box body is further provided with a high-temperature resistant baffle brick, which has a porous structure; the high-temperature resistant baffle brick is located on the side of the ceramic honeycomb body facing the kiln.

[0015] In one possible implementation, the burner brick also has a variable diameter channel, one end of which is connected to the housing and the other end is connected to the air nozzle or the gas nozzle; the inner diameter of the variable diameter channel gradually decreases in the direction toward the kiln.

[0016] The low-NOx burner provided in this application embodiment has combustion air and blast furnace gas entering corresponding channels in the heat storage component on the burner brick when the burner is working. The heat storage component continuously absorbs the high-temperature radiation and waste heat of the flue gas in the kiln to preheat the gas, so that it is heated to a higher temperature before being injected into the furnace.

[0017] The preheated blast furnace gas and combustion air are respectively sprayed out from the gas nozzle and air nozzle at intervals along the first preset direction. When needed, natural gas is sprayed out from the natural gas nozzle through the natural gas nozzle, and the natural gas nozzle and air nozzle are arranged at intervals along the second preset direction perpendicular to the first preset direction.

[0018] Because each nozzle maintains a preset interval in two vertical directions in space, and the jet velocity is high, the fuel and combustion air do not mix immediately near the nozzle, but gradually converge in the area away from the burner bricks after entering the kiln.

[0019] During this process, the high-speed jet exerts a strong entrainment and entrainment effect on the surrounding flue gas. A large amount of flue gas with higher temperature and lower oxygen content is drawn into the fuel-air mixture, effectively diluting the reactant concentration and stretching the combustion zone into a more diffuse space. This flue gas dilution combustion reduces the intensity of the combustion reaction and lowers the peak flame temperature, thus suppressing the large-scale formation of thermal NOx at its source even under high-temperature conditions exceeding 1000℃.

[0020] The low-NOx burner provided in this application embodiment, compared with the prior art, achieves delayed convergence and dilution combustion of fuel and combustion-supporting gas in the furnace by combining the spaced arrangement of nozzles in two vertical directions with high-speed jet entrainment of flue gas. This weakens the conditions for the formation of thermal NOx and solves the problem that the existing staged combustion or flue gas internal circulation technology has limited NOx reduction effect when the furnace temperature is higher than 1000℃ in regenerative furnaces.

[0021] The heat storage components are integrated on the burner bricks, which can continuously preheat the gas, ensuring stable ignition and efficient combustion of low-calorific-value blast furnace gas, while avoiding combustion pulsation caused by commutation fluctuations, making the temperature field inside the furnace more stable.

[0022] The arrangement of the gas and air nozzles along a first preset direction, and the air and natural gas nozzles along a second preset direction, allows for a more spatially distributed combustion zone, increasing the flame coverage and resulting in a more uniform temperature distribution within the furnace. This helps improve the heating quality of the workpiece and reduce damage to the furnace lining from localized high temperatures. Furthermore, the burner is equipped with both blast furnace gas nozzles and natural gas lances, allowing for flexible use or co-firing depending on fuel conditions, thus improving the equipment's fuel adaptability and operational economy. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A three-dimensional structural diagram of a low-NOx burner provided in an embodiment of the present invention. Figure 1 ; Figure 2 A three-dimensional structural diagram of a low-NOx burner provided in an embodiment of the present invention. Figure 2 ; Figure 3 A three-dimensional structural diagram of a low-NOx burner provided in an embodiment of the present invention. Figure 3 ; Figure 4 A three-dimensional structural diagram of a low-NOx burner provided in an embodiment of the present invention. Figure 4 ; Figure 5 This is a side view of the low-NOx burner provided in an embodiment of the present invention; Figure 6 This is a front view schematic diagram of the low-NOx burner provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the vertical cross-sectional structure of a low-NOx burner provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the horizontal cross-sectional structure of a low-NOx burner provided in an embodiment of the present invention; Figure 9 A combustion principle diagram of a low-NOx burner during operation, provided in an embodiment of the present invention.

[0025] The following are the labeling elements in the figure: 1. Burner brick; 2. Gas nozzle; 3. Air nozzle; 4. Natural gas nozzle; 5. Heat storage component; 51. Housing; 52. Ceramic honeycomb body; 6. Natural gas nozzle; 7. High-temperature resistant baffle brick; 8. Variable diameter channel; 9. Kiln. Detailed Implementation

[0026] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0027] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0028] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "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 convenience of describing the present invention and simplifying the description, 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 the present invention.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] Please refer to the following: Figures 1 to 9 The low-NOx burner provided in this application will now be described. The low-NOx burner includes a burner brick 1, a heat storage component, and a natural gas injection gun 6.

[0031] Burner brick 1 is installed on kiln 9, and combustion air and blast furnace gas are introduced into the channels in the heat storage component, while natural gas is introduced by natural gas injection gun 6.

[0032] The heat storage component first absorbs the heat from the high-temperature flue gas inside the kiln 9, and then transfers the heat to the flowing combustion air and blast furnace gas, preheating both. The preheated combustion air is ejected at high speed from the air nozzle 3, the preheated blast furnace gas is ejected from the gas nozzle 2, and the natural gas is ejected from the natural gas nozzle 4 through the natural gas nozzle 6.

[0033] Since the gas nozzle 2 and the air nozzle 3 are arranged at intervals along the first preset direction, and the air nozzle 3 and the natural gas nozzle 4 are arranged at intervals along the second preset direction perpendicular to the first preset direction, the multiple jets only converge and mix after leaving the burner brick 1 for a certain distance.

[0034] During the mixing process, the jet entrains and agitates the flue gas from the surrounding kiln 9, causing a large amount of flue gas to participate in the mixing and dilute the reactants. This results in a soft, extended flame forming in the area away from the burner brick 1, suppressing the heat release rate and significantly reducing the intensity of the combustion reaction.

[0035] This burner utilizes a triple mechanism of regenerative preheating, fuel staging, and entrained flue gas to achieve low-NOx combustion: the regenerative component recovers waste heat from the flue gas for preheating, improving the thermal efficiency of the kiln 9. Gas nozzle 2 and air nozzle 3 separate along a first preset direction, while air and natural gas separate in a second preset direction perpendicular to this direction. This spatially delays the mixing of combustion air with blast furnace gas and natural gas. The fuel undergoes pyrolysis and partial oxidation in a low-oxygen atmosphere before gradually mixing with air and burning completely, resulting in rich-lean combustion and staging combustion. The high-temperature jet can entrain flue gas in the furnace, simultaneously reducing the oxygen concentration and peak temperature in the flame zone, effectively suppressing the formation of thermal NOx.

[0036] The first and second preset directions can be the width and height directions of the kiln 9, respectively, to create a more three-dimensional mixing delay effect. The heat storage component can adopt a multi-chamber heat storage structure, switching the air and flue gas channels in stages. The burner brick 1 can be designed as rectangular or arc-shaped according to the arch or side wall structure of the kiln 9. The natural gas lance 6 can move independently relative to the burner brick 1 to adjust the natural gas jet length. If only blast furnace gas is used, the natural gas lance 6 can be turned off, and the burner can still maintain low-NOx characteristics.

[0037] The arrangement of the gas nozzle 2 and the air nozzle 3 along the first preset direction, and the air nozzle 3 and the natural gas nozzle 4 along the second preset direction, allows the combustion zone to be reasonably expanded in space, increases the flame coverage area, and makes the temperature distribution inside the furnace more uniform, which helps to improve the heating quality of the workpiece and reduce the damage of local high temperature to the furnace lining.

[0038] In addition, the burner is equipped with both blast furnace gas nozzle 2 and natural gas nozzle 6, which can be used flexibly or mixed according to fuel conditions (i.e., using combustion air and blast furnace gas, or using combustion air and natural gas, or using combustion air, blast furnace gas and natural gas at the same time), which improves the fuel adaptability and operating economy of the equipment.

[0039] Further, please refer to Figures 1 to 9 In one specific embodiment of the low-NOx burner provided by the present invention, the three heat storage elements 5 in the heat storage assembly are respectively introduced with gas. The middle heat storage element 5 delivers preheated combustion air to the air nozzle 3, and the two side heat storage elements 5 respectively deliver preheated blast furnace gas to the two gas nozzles 2. The air nozzles 3 are located between the two gas nozzles 2, and along a first preset direction, the central nozzle ejects an air jet, while the two side nozzles eject blast furnace gas jets.

[0040] After these three parallel jets leave the burner brick 1, they gradually mix at a relatively far distance due to the spacing between the gas and air nozzles 3. At the mixing boundary, they entrain a large amount of flue gas, forming a flow field structure with air in the middle and gas on both sides. Combustion occurs slowly in the mixing layer, and the flame is elongated along the depth of the kiln 9.

[0041] The system employs a centrally located combustion air jet with blast furnace gas distributed on both sides. This arrangement creates a double-sided rich and lean combustion zone, where the outer side of each gas jet is filled with furnace flue gas and the inner side with combustion air. Before contacting the air, the blast furnace gas mixes with the high-temperature flue gas, reducing the local oxygen content, slowing down the oxidation process, and suppressing a rapid increase in flame front temperature. Simultaneously, the central air jet, acting as a staged burnout air stream, enhances the entrainment of flue gas, increasing the entrainment ratio and further lowering the flame zone temperature, thus disrupting the high-temperature, oxygen-enriched formation conditions for thermal NOx.

[0042] The air nozzle 3 can be further subdivided into multiple jets, and the width of the gas nozzles 2 on both sides is adjustable. The heat storage unit 5 can be an independent modular heat storage box, which is convenient for maintenance and replacement. The three heat storage units 5 can share a set of switching valves to simultaneously store and release heat. When a higher combustion power is required, multiple sets of air-centered and gas-distributed nozzle units can be added vertically.

[0043] By employing the above technical solution, a symmetrical combustion flow field is formed by sandwiching combustion air between two streams of blast furnace gas, resulting in high flame stability and reducing the likelihood of backfire or flameout. The double-sided injection of blast furnace gas enhances the entrainment of flue gas in the mixing zone, leading to better delayed combustion and further reducing thermal NOx production. Simultaneously, the symmetrical structure ensures uniform temperature distribution across the width of the kiln, which is beneficial for the quality of the heating process.

[0044] Further, please refer to Figures 1 to 9 As a specific embodiment of the low-NOx burner provided by the present invention, the low-NOx burner adopts a long and flat gas nozzle 2, and the long axis of the nozzle is perpendicular to the first preset direction (i.e. the width direction of the burner).

[0045] The preheated blast furnace gas is ejected from the nozzle in a flat jet shape. This jet rapidly thins along the short axis of the nozzle while maintaining a large continuous span along the long axis. After ejection, it forms a large contact interface with adjacent air jets and flue gas inside the kiln, thickening the shear layer and enhancing the entrainment effect. A large amount of flue gas is drawn into the unburned gas area, after which the air gradually mixes with the gas, completing progressive combustion.

[0046] The elongated, flat nozzle transforms the circular jet into a sheet-like jet, increasing the ratio of jet circumference to cross-sectional area. Consequently, at the same flow rate, the area for momentum, heat, and mass exchange between the jet and the surrounding fluid is significantly expanded. This enhances the entrainment capacity of the gas jet on the flue gas, diluting and cooling it before it comes into contact with sufficient air. The initial combustion temperature is lower, and the mixing rate is slowed down by diffusion control, thus avoiding localized high temperatures and suppressing NOx formation.

[0047] The flat cross-section of the gas nozzle 2 can be rectangular, elliptical, or oblong, and its outlet cross-sectional area is matched with the flow rate of the other gas nozzle 2, achieving a high-speed ejection effect of 60-100 m / s or higher. Multiple flat nozzles can replace a single long nozzle to achieve segmented injection. Guide ribs can be installed on the inner wall of the flat nozzle to prevent premature jet collapse. This structure is also suitable for nozzles of other gaseous fuels.

[0048] By adopting the above technical solution, the elongated flat structure effectively increases the entrainment and mixing of flue gas without increasing the total nozzle area, further reducing the peak flame temperature and decreasing thermal NOx emissions. The flame is more evenly distributed across the width of the furnace, with no localized hot spots, which helps protect the kiln lining while maintaining a high burnout rate.

[0049] Further, please refer to Figures 1 to 9 As a specific embodiment of the low-NOx burner provided by the present invention, natural gas is fed into a plurality of corresponding natural gas nozzles 4 by a plurality of natural gas injection guns 6, and these nozzles are arranged at intervals along a first preset direction.

[0050] Natural gas is ejected in multiple independent jets, which combine with air nozzles 3 arranged along the second preset direction and gas nozzles 2 arranged along the first preset direction to form a three-dimensional jet matrix.

[0051] Within the kiln space 9, multiple natural gas jets disperse laterally, each entraining smoke and gradually meeting the air away from the nozzle. Combustion is broken down into multiple dispersed small flame clusters, which then mix and burn out in the longitudinally extending region.

[0052] By dividing the natural gas nozzle 4 into multiple injection points along a first preset direction, it is equivalent to achieving fuel grading. Each natural gas jet is diluted by the surrounding flue gas and possible coal gas products before contacting the air, and the flame changes from concentrated to discrete, reducing the local heat intensity and thus reducing the formation rate of thermal NOx.

[0053] Multi-point injection also enhances the controllability of the macroscopic mixing scale of natural gas and combustion air, avoiding premature uniform mixing to form a high-temperature flame.

[0054] The number of natural gas nozzles 4 can be designed from 3 to 10 depending on the width of the kiln 9. Each nozzle can independently adjust the natural gas flow rate to adapt to the variable load requirements of the heating process. The nozzles can be arranged alternately in two rows to further increase the dispersion. Some nozzles can be used for ignition and stable combustion, while the rest are used for the main combustion stage, thus broadening the load adjustment ratio.

[0055] By adopting the above technical solution, multi-point natural gas injection allows combustion to spread more evenly within the space, resulting in a more gradual flame temperature distribution. This effectively suppresses NOx and reduces the potential for localized overheating and burn-off caused by a single large flame. Adjusting the flow rate of each spray gun allows for flexible control of the temperature curve within the kiln 9, which is particularly advantageous for heat treatment and heating kilns 9, while maintaining low-NOx characteristics.

[0056] Further, please refer to Figures 1 to 9 In one specific embodiment of the low-NOx burner provided by the present invention, the axis of the natural gas nozzle 4 is provided with a first included angle α relative to the horizontal plane, where α is between 0° and 10°. The natural gas jet is injected into the kiln 9 at a slight upward or downward angle, forming a vertical misalignment with the air jet ejected in the horizontal direction and the horizontal or angled gas jet.

[0057] After the jet is ejected, it still follows the spatial separation of the first and second preset directions on the horizontal projection plane, but it deviates in the vertical direction, causing the mixing point of natural gas with air and coal gas to be further pushed back and dispersed in three-dimensional space. The flue gas is entrained layer by layer between the jets, forming a three-dimensional flue gas entrainment.

[0058] By fine-tuning the vertical angle of the natural gas jet, the timing of the intersection between the natural gas and air jets can be controlled without altering the horizontal arrangement of the nozzles. A smaller angle allows the natural gas to first enter the area above or below where flue gas is abundant, where it is heated and diluted by the flue gas before gradually diffusing into the mainstream air zone to participate in combustion. This increases the mixing delay time, enhances flue gas recirculation, and slightly stretches the flame in the height direction, reducing volumetric heat intensity and thus lowering NOx formation.

[0059] The first included angle α is determined based on the flue gas flow direction in the kiln 9. Utilizing thermal buoyancy or the internal circulating vortex of the kiln 9, multiple natural gas injection nozzles 6 can be set at different angles to achieve stratified combustion. An adjustment mechanism can be installed to change the α value online to adapt to changes in operating conditions.

[0060] By adopting the above technical solution and changing the direction of the natural gas jet, more freedom is given to the combustion organization. The flame length and shape can be finely adjusted, which can effectively prevent the flame from scouring the furnace top or materials, and further alleviate the concentration of high-temperature zones, thus further reducing thermal NOx emissions. At the same time, the inclined injection helps to enhance the entrainment efficiency of flue gas, improve combustion stability and flue gas recirculation rate.

[0061] Further, please refer to Figures 1 to 9 As a specific embodiment of the low-NOx burner provided by the present invention, the axis of the air nozzle 3 is kept horizontal, and air is ejected from multiple air nozzles 3 arranged in a rectangular array to form multiple parallel horizontal jets.

[0062] These air jets are spatially arrayed, forming a three-dimensional jet group with the gas nozzles 2 arranged along the first direction and the natural gas nozzles 4 arranged along the second direction. After the air enters the kiln 9 in the form of dispersed, parallel jets, the boundary layer of each jet is superimposed with the entrained flue gas, and the overall entrainment capacity of the air jet group for the flue gas is enhanced, so that it is mixed and burned completely with the gas and natural gas at a relatively far downstream distance.

[0063] The multi-jet rectangular array of air streams essentially further classifies the combustion air, distributing it evenly over a larger cross-section. Each jet individually entrains surrounding flue gas, and the collective entrainment effect of the array significantly increases the flue gas circulation volume in kiln 9, diluting the oxygen concentration in the reaction zone. Simultaneously, the parallel jets are less likely to prematurely collide directly with the fuel stream, which helps maintain macroscopic separation between fuel and air, achieving more delayed mixing and reducing the volume and peak temperature of the high-temperature oxygen-rich zone.

[0064] The rectangular array of air nozzles 3 can be 2×2, 3×3, etc., and the nozzle spacing and orifice diameter can be optimized according to the air volume to ensure uniform air momentum. Some air nozzles 3 can be closed in stages to achieve more flexible air grading. This structure can also be coupled with the variable diameter channel 8 at the outlet of the regenerator to ensure uniform airflow distribution. The shape of the nozzles in the rectangular array is not limited and can be circular, square, or flat. The total cross-sectional area of ​​the air nozzles 3 is matched with the airflow rate to achieve a high-speed ejection effect of 60-100 m / s or more.

[0065] Further, please refer to Figures 1 to 9 As a specific embodiment of the low-NOx burner provided by the present invention, in the structure of two gas nozzles 2, the axis of one gas nozzle 2 forms a second included angle β with the axis of the horizontal and parallel air nozzle 3, ranging from 10° to 20°; the axis of the other gas nozzle 2 forms a third included angle γ, ranging from 0° to 10°, and β and γ are not equal.

[0066] In this way, the gas jets on both sides are ejected at different angles, one more inclined toward the air side, and the other nearly horizontal or with a slight deflection. The two gas jets form an asymmetrical flow structure within the kiln 9, with the air jet trapped between them, creating an oblique mixing boundary, and the vortex form of the flue gas entrainment becomes more complex.

[0067] The asymmetric gas jet arrangement breaks the periodic vortex shedding and orderly mixing that easily occur in symmetric flow fields, and introduces stronger anisotropic turbulent mixing.

[0068] On the side with a larger β angle, the gas expands rapidly and entrains a large amount of smoke, while on the other side with a smaller γ angle, the gas stream is relatively concentrated and has a longer penetration distance. This causes the mixing process on both sides of the air jet to be asynchronous, stretching the mixing process in time and space, avoiding concentrated heat release, achieving more complete staged combustion and internal flue gas recirculation, thereby further reducing the peak flame temperature and NOx.

[0069] By adopting the above technical solution, the asymmetry of the gas jet angle is utilized to achieve a redistribution of internal flame temperature and reaction rate through a simple differential deflection structure, eliminating concentrated high-temperature nuclei and reducing thermal NOx. Simultaneously, the flame as a whole remains stable, without serious uneven burning or furnace wall erosion problems, providing an effective means for precise temperature control of the kiln's nine cross-sections.

[0070] Further, please refer to Figures 1 to 9 In one specific embodiment of the low-NOx burner provided by this invention, when the heat storage element 5 is working, the ceramic honeycomb 52 filled inside the housing 51 serves as the heat storage medium. It first undergoes a flue gas heat release period, where high-temperature flue gas flows through the multi-layered permeable channels of the ceramic honeycomb 52, transferring heat to the honeycomb. When preheated combustion air or blast furnace gas flows through the heated ceramic honeycomb 52, the gas is rapidly heated to near the flue gas temperature of the kiln 9, and then ejected through the connecting channel from the air nozzle 3 or gas nozzle 2. This cycle repeats, continuously recovering the waste heat of the flue gas and using it to preheat the combustion air.

[0071] The ceramic honeycomb structure 52 possesses an extremely high specific surface area and low flow resistance, enabling highly efficient convective heat transfer between the gas and solid. The multi-layered permeable structure forms numerous microchannels, allowing for sufficient heat exchange within a short heat storage cycle, achieving a preheating heat storage efficiency of over 90%. Preheating the combustion air and gas to high temperatures can compensate for the low calorific value and insufficient theoretical combustion temperature of the blast furnace gas. However, simple high-temperature preheating can promote NOx formation; therefore, it must be combined with the aforementioned delayed mixing and flue gas entrainment measures. Staged combustion ensures that the high-temperature flame zone is occupied by rich combustion and flue gas dilution, resulting in a net NOx reduction effect.

[0072] The ceramic honeycomb cell 52 can be made of cordierite, mullite, or corundum to adapt to different flue gas temperatures and corrosiveness. The housing 51 can be designed as a detachable structure for easy cleaning or replacement of the ceramic honeycomb cell 52. For low-sulfur clean flue gas, a honeycomb cell with denser pores can be used to improve heat exchange efficiency.

[0073] By adopting the above technical solutions, the heat storage unit 5 achieves efficient recovery of sensible heat from flue gas, reduces fuel consumption, and improves the thermal efficiency of the kiln 9. Simultaneous preheating of combustion air and coal gas stabilizes the combustion of blast furnace gas, expands the application range of low-calorific-value fuels, and, after combining with the aforementioned mixture of flue gas, air, coal gas, and natural gas, does not cause an increase in NOx. On the contrary, improved ignition and controllable mixing contribute to an overall reduction in emissions.

[0074] Further, please refer to Figures 1 to 9 As a specific embodiment of the low-NOx burner provided by the present invention, a high-temperature resistant baffle 7 is provided on the side of the ceramic honeycomb 52 facing the kiln 9 inside the housing 51. Flue gas or preheated gas must pass through this porous baffle when entering or exiting the housing 51. The high-temperature resistant baffle 7, with its porous structure, withstands direct radiation from the kiln 9 and possible flame erosion, protecting the inner ceramic honeycomb 52.

[0075] The high-temperature resistant baffle brick 7 serves the dual functions of an airflow distributor and a heat shield. Its porous structure redistributes the incoming flow from the pipes, preventing uneven heat exchange, localized overheating, or concentrated thermal stress in different areas of the honeycomb structure due to localized flow deviation. The high-temperature resistant baffle brick 7 directly faces the high-temperature environment of the kiln 9 and potential slag and flame licking; its material has a much higher temperature resistance than ordinary honeycomb structures, effectively extending the lifespan of the honeycomb structure. Simultaneously, the absorption and re-emission of radiant heat by the high-temperature resistant baffle brick 7 further stabilizes the airflow temperature at the inlet of the regenerator chamber.

[0076] By adopting the above technical solutions, the reliability and service life of the heat storage body are improved, and the frequency of maintenance caused by honeycomb blockage or breakage is reduced. After the airflow uniformity is improved, the quality of the jet ejected from the nozzle is higher, which is conducive to maintaining the designed flow field and low-NOx combustion organization effect, and prevents local high temperature points caused by uneven airflow, thus ensuring the sustainability of low NOx emissions at the system level.

[0077] Further, please refer to Figures 1 to 9 In one specific embodiment of the low-NOx burner provided by this invention, after the gas flows out of the housing 51 of the heat storage element 5, it enters the variable-diameter channel 8 inside the burner brick 1. The cross-section of the variable-diameter channel 8 gradually narrows towards the kiln 9. As the airflow passes through the narrowing section, its velocity continuously increases, and its pressure energy is converted into kinetic energy. Finally, it is ejected at high speed from the air nozzle 3 or the gas nozzle 2, with a velocity reaching 60-100 m / s. After this accelerated jet is ejected from the nozzle, it strongly entrains the flue gas of the surrounding kiln 9 with its high momentum and maintains a relatively long jet core area along the injection path, realizing the designed delayed mixing and strong flue gas entrainment combustion process.

[0078] By adopting the above technical solution and accelerating the jet flow through variable diameter, the entrainment rate of each jet on the flue gas is increased, further enhancing flue gas circulation and strengthening the low-NOx combustion effect. The high-speed jet also helps prevent backfire and ensures combustion safety. The accelerated airflow allows for a more rational flame spread within the kiln 9, resulting in a more uniform temperature distribution. This has a positive effect on improving heating quality and increasing yield, while simultaneously consolidating the advantage of reduced NOx emissions.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-NOx burner, characterized in that, include: Burner bricks are used for installation on kilns; the burner bricks have gas nozzles, air nozzles and natural gas nozzles on the side facing the kiln. The gas nozzles and air nozzles are arranged at intervals along a first preset direction, and the air nozzles and natural gas nozzles are arranged at intervals along a second preset direction, wherein the first preset direction is perpendicular to the second preset direction; A heat storage component is disposed on the burner brick; the heat storage component has a channel through which combustion air and blast furnace gas flow, and the heat storage component is connected to the gas nozzle and the air nozzle respectively; the heat storage component is used to absorb heat in the kiln to heat the flowing gas. as well as A natural gas nozzle, used to allow natural gas to pass through and be ejected, and connected to the natural gas nozzle; Wherein, after the combustion air and the blast furnace gas, or the combustion air and the natural gas, or the combustion air, the blast furnace gas and the natural gas are injected into the kiln, they converge and mix at a position away from the burner bricks, and the mixed gas is suitable for stirring and entraining the flue gas in the kiln, so as to reduce the intensity of the combustion reaction and reduce the emission of thermal NOx.

2. The low-NOx burner as described in claim 1, characterized in that, The number of gas nozzles is two, and the air nozzle is located between the two gas nozzles; the heat storage assembly includes three heat storage elements, one of which is used to introduce the combustion air and is connected to the air nozzle; the other two heat storage elements are used to introduce the blast furnace gas and are connected to the two gas nozzles one by one.

3. The low-NOx burner as described in claim 1 or 2, characterized in that, The gas nozzle adopts a long, flat structure.

4. The low-NOx burner as described in claim 1, characterized in that, The number of natural gas nozzles is multiple, and the multiple natural gas nozzles are arranged at intervals along the first preset direction; the number of natural gas spray guns is multiple, and each of the multiple natural gas nozzles is connected to one of them.

5. The low-NOx burner as described in claim 1 or 4, characterized in that, The natural gas nozzle axis has a first included angle α relative to the horizontal plane, and the value of the first included angle α ranges from 0° to 10°.

6. The low-NOx burner as described in claim 1 or 2, characterized in that, The axis of the air nozzle is parallel to the horizontal plane; there are multiple air nozzles, and the multiple air nozzles are arranged in a rectangular array.

7. The low-NOx burner as described in claim 6, characterized in that, One of the gas nozzles forms a second angle β with the air nozzle axis, the second angle β ranging from 10° to 20°; the other gas nozzle forms a third angle γ with the air nozzle axis, the third angle γ ranging from 0° to 10°. The values ​​of the second included angle β and the third included angle γ are different.

8. The low-NOx burner as described in claim 2, characterized in that, The heat storage component includes: A housing, mounted on the burner brick, is internally used for introducing the combustion air or the blast furnace gas, and is connected to the air nozzle or the gas nozzle; and A ceramic honeycomb structure is filled inside the box and has a multi-layered breathable structure. The ceramic honeycomb structure is used to exchange heat with the kiln and heat the gas flowing through the box.

9. The low-NOx burner as described in claim 8, characterized in that, The box body is also equipped with high-temperature resistant baffle bricks, which have a porous structure; the high-temperature resistant baffle bricks are located on the side of the ceramic honeycomb body facing the kiln.

10. The low-NOx burner as described in claim 9, characterized in that, The burner brick also has a variable diameter channel, one end of which is connected to the housing and the other end is connected to the air nozzle or the gas nozzle; the inner diameter of the variable diameter channel gradually decreases in the direction toward the kiln.

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