A natural gas low-NOx burner for hot blast stove

Abstract

This utility model relates to a low-NOx burner for natural gas in a hot blast stove, comprising a furnace body and a primary combustion element connected to the furnace body. The primary combustion element includes at least one primary burner connected to the furnace body. A secondary combustion element is connected to the furnace body, including at least one secondary burner connected to the furnace body. An exhaust pipe is connected to one side of the upper end of the furnace body, and a recovery pipe is connected to the other side of the upper end of the furnace body. A conversion element is connected to the upper end of the furnace body. The technical solution of this application has the following advantages: through the staged design of the primary and secondary burners, natural gas achieves sufficient premixing and preliminary combustion in the initial combustion stage, effectively controlling the peak flame temperature and suppressing the generation of thermal nitrogen oxides. This solves the problems of uneven fuel-oxygen mixing and pollutants such as nitrogen oxides in the existing single-stage combustion mode.

Description

Technical Field

[0001] This utility model relates to the field of burners, specifically to a low-NOx burner for natural gas in a hot blast stove. Background Technology

[0002] In the field of industrial production and energy utilization, hot blast stoves, as key equipment for providing heat energy, have always been a focus of industry attention regarding energy consumption and pollutant emissions. With increasingly stringent global environmental regulations, particularly the tightening restrictions on nitrogen oxide emissions...

[0003] Most of the natural gas burners in our existing hot blast stoves adopt a single-stage combustion mode, completing the fuel combustion process through only a single combustion device. This structure results in uneven mixing of fuel and oxygen, and the generation of pollutants such as nitrogen oxides.

[0004] Therefore, it is very necessary to provide a natural gas low-NOx burner for hot blast stoves to solve the above-mentioned technical problems. Utility Model Content

[0005] Based on the above description, this utility model provides a natural gas low-NOx burner for hot air furnaces to solve the problems of uneven fuel-oxygen mixing and pollutants such as nitrogen oxides in the existing single-stage combustion mode.

[0006] The technical solution of this utility model to solve the above-mentioned technical problems is as follows: A natural gas low-NOx burner for a hot blast stove includes a furnace body and a primary combustion element connected to the furnace body. The primary combustion element includes at least one primary burner connected to the furnace body, which is used for preliminary combustion of raw materials. A secondary combustion element is connected to the furnace body, including at least one secondary burner connected to the furnace body, which is used for secondary combustion of incompletely combusted flue gas in the furnace body. An exhaust pipe is connected to one side of the upper end of the furnace body, and a recovery pipe is connected to the other side of the upper end of the furnace body. A conversion element is connected to the upper end of the furnace body. When the flue gas in the furnace body meets the standards, the conversion element discharges the flue gas in the furnace body through the exhaust pipe; when the flue gas in the furnace body does not meet the standards, it recovers the flue gas in the furnace body through the recovery pipe.

[0007] Furthermore, a storage cylinder is connected to the bottom of the furnace body, and a feeding pipe is connected to the storage cylinder. The feeding pipe is connected to the primary burner and the secondary burner respectively. A raw material inlet pipe is connected to the storage cylinder, and a flow control valve is connected to the feeding pipe.

[0008] Furthermore, the secondary combustion component includes a mixed gas storage box connected to the recovery pipe, and a secondary material pipe is connected to the mixed gas storage box. The number of secondary material pipes corresponds to the number of secondary burners, and the secondary material pipes are respectively connected to the corresponding secondary burners.

[0009] Furthermore, each of the secondary feed pipes is connected to a secondary air pump, which is used to regulate the speed at which the mixed gas enters the secondary burner.

[0010] Furthermore, it also includes an oxygen supply unit, which includes an oxygen tank and a first oxygen pipe connected to the oxygen tank. The first oxygen pipe is connected to the secondary burner and a first intake solenoid valve is connected to the first oxygen pipe. The oxygen supply unit is used to supply oxygen to the secondary burner.

[0011] Furthermore, the initial combustion component includes a second oxygen pipe connected to the oxygen tank and an oxygen distribution box connected to the second oxygen pipe. A second intake solenoid valve is connected to the second oxygen pipe, and a distribution gas pipe is connected to the oxygen distribution box. The number of distribution gas pipes corresponds to the number of initial burners, and each distribution gas pipe is connected to a corresponding initial burner.

[0012] Furthermore, each of the gas distribution pipes is connected to an oxygen distribution pump, which is used to regulate the rate at which oxygen enters the primary burner.

[0013] Furthermore, the conversion component includes a recovery solenoid valve connected to the recovery pipe, the recovery solenoid valve being used to control the opening or closing of the recovery pipe.

[0014] Furthermore, the conversion component includes an exhaust solenoid valve connected to the exhaust pipe and close to the furnace body, and an exhaust fan is connected to the side of the exhaust pipe away from the furnace body.

[0015] Furthermore, a gas detection device is connected to the furnace body, and the gas detection device is equipped with an oxygen concentration sensor, a nitrogen concentration sensor and a nitrogen oxide concentration sensor. The gas detection device is used to detect the oxygen concentration, nitrogen concentration and nitrogen oxide concentration in the furnace body.

[0016] Compared with the prior art, the technical solution of this application has the following beneficial technical effects:

[0017] Through a staged design of primary and secondary burners, natural gas achieves thorough premixing and initial combustion in the primary combustion stage, effectively controlling the peak flame temperature and suppressing the generation of thermal nitrogen oxides. The secondary burner provides supplemental oxygen to unburned flue gas, ensuring complete fuel reaction and reducing fuel-type nitrogen oxides generated due to oxygen-deficient combustion. The conversion unit and recovery pipe form a closed-loop control system that monitors the flue gas composition in real time. When the flue gas does not meet standards, it is automatically drawn back into the furnace for secondary combustion, extending the flue gas residence time, promoting deep oxidation of unburned hydrocarbons, and reducing heat loss. Standard-compliant flue gas is discharged through the outlet pipe, avoiding increased energy consumption due to excessive circulation. This addresses the problems of uneven fuel-oxygen mixing and pollutants such as nitrogen oxides inherent in existing single-stage combustion technologies. Attached Figure Description

[0018] Figure 1 One of the schematic diagrams of the overall structure of a natural gas low-NOx burner for a hot blast stove provided in this embodiment of the present invention;

[0019] Figure 2 A second schematic diagram of the overall structure of a natural gas low-NOx burner for a hot blast stove, provided as an embodiment of this utility model;

[0020] Figure 3 A partial cross-sectional structural diagram of a natural gas low-NOx burner for a hot blast stove is provided for an embodiment of this utility model;

[0021] Figure 4 for Figure 3 A magnified structural diagram of point Q.

[0022] The attached diagram lists the components represented by each number as follows:

[0023] 1. Furnace body;

[0024] 2. Initial combustion components; 21. Initial burner; 22. Second oxygen pipe; 221. Second intake solenoid valve; 23. Oxygen distribution box; 24. Distribution gas pipe; 25. Distribution oxygen pump;

[0025] 3. Secondary combustion components; 31. Secondary burner; 32. Mixed gas storage tank; 33. Secondary feed pipe; 34. Secondary gas pump;

[0026] 4. Air outlet pipe;

[0027] 5. Recycling pipe;

[0028] 6. Conversion component; 61. Recovery solenoid valve; 62. Exhaust solenoid valve; 63. Exhaust fan;

[0029] 7. Storage cylinder; 71. Feeding pipe; 72. Raw material inlet pipe; 73. Flow control valve;

[0030] 8. Oxygen supply components; 81. Oxygen cylinder; 82. First oxygen pipe; 83. First intake solenoid valve;

[0031] 9. Gas detection components. Detailed Implementation

[0032] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0034] It is understood that spatial relation terms such as "below," "under," "below," "below," "above," "above," etc., can be used here to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as "below" or "below" of the other element or feature will be oriented "above" the other element or feature. Therefore, the exemplary terms "below" and "below" can include both upper and lower orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0035] It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediary element. In the following embodiments, "connection" should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have the transmission of electrical signals or data between them.

[0036] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0037] like Figures 1 to 4 As shown, a natural gas low-NOx burner for a hot blast stove includes a furnace body 1 and a primary combustion element 2 connected within the furnace body 1. The primary combustion element 2 includes at least one primary burner 21 connected within the furnace body 1, which is used for preliminary combustion of raw materials. A secondary combustion element 3 is connected within the furnace body 1, including at least one secondary burner 31 connected within the furnace body 1, which is used for secondary combustion of incompletely combusted flue gas within the furnace body 1. An exhaust pipe 4 is connected to one side of the upper end of the furnace body 1, and a recovery pipe 5 is connected to the other side of the upper end of the furnace body 1. A conversion element 6 is connected to the upper end of the furnace body 1. The conversion element 6 is used to discharge the flue gas within the furnace body 1 through the exhaust pipe 4 when the flue gas meets the standard, and to recover the flue gas within the furnace body 1 through the recovery pipe 5 when the flue gas does not meet the standard.

[0038] In this embodiment, through the staged design of the primary burner 21 and the secondary burner 31, natural gas achieves sufficient premixing and initial combustion in the initial combustion stage, effectively controlling the peak flame temperature and suppressing the generation of thermal nitrogen oxides. The secondary burner 31 provides secondary oxygen supplementation combustion for unburned flue gas, ensuring complete fuel reaction and reducing fuel-type nitrogen oxides generated due to oxygen-deficient combustion. The conversion element 6 and the recovery pipe 5 constitute a closed-loop control system that monitors the flue gas composition in the furnace in real time. When the flue gas does not meet the standards, it is automatically drawn back into the furnace for secondary combustion, extending the flue gas residence time, promoting deep oxidation of unburned hydrocarbons, and reducing heat loss; the qualified flue gas is discharged through the exhaust pipe 4, avoiding increased energy consumption caused by excessive circulation.

[0039] In some embodiments, a storage cylinder 7 is connected to the bottom of the furnace body 1, and a feeding pipe 71 is connected to the storage cylinder 7. The feeding pipe 71 is connected to the primary burner 21 and the secondary burner 31 respectively. A raw material inlet pipe 72 is connected to the storage cylinder 7, and a flow control valve 73 is connected to the feeding pipe 71.

[0040] In this embodiment, the storage cylinder 7 directly supplies natural gas or other fuels to the primary burner 21 and the secondary burner 31 via the feeding pipe 71, and achieves independent feeding in stages in conjunction with the flow control valve 73. During the primary combustion stage, the fuel flow rate can be adjusted as needed to control the premixing intensity, while during the secondary combustion stage, the amount of supplementary combustion is dynamically adjusted according to the flue gas composition to avoid incomplete combustion or a surge in nitrogen oxide gas generation caused by fuel fluctuations, thus ensuring a uniform and stable temperature and flow field inside the furnace.

[0041] In some embodiments, the secondary combustion element 3 includes a mixed gas storage box 32 connected to the recovery pipe 5, and a secondary material pipe 33 is connected to the mixed gas storage box 32. The number of secondary material pipes 33 corresponds to the number of secondary burners 31, and the secondary material pipes 33 are respectively connected to the corresponding secondary burners 31.

[0042] In this embodiment, the mixed gas storage tank 32 receives substandard flue gas through the recovery pipe 5, forms a uniform mixed gas, and then transports it to the secondary burner 31 through the secondary feed pipe 33, where it is burned with the fuel required for secondary combustion, such as natural gas, inside the furnace body 1. This design significantly improves the uniformity of fuel-flue gas mixing and the completeness of combustion during the secondary combustion stage.

[0043] In some embodiments, each of the secondary feed pipes 33 is connected to a secondary air pump 34, which is used to adjust the speed at which the mixed gas enters the secondary burner 31.

[0044] In this embodiment, each secondary feed pipe 33 is independently equipped with a secondary gas pump 34, which can adjust the mixed gas delivery pressure in different areas for the secondary burners 31 at different locations. For example, when the load on the furnace body 1 changes suddenly, such as when the amount of raw material input increases or the amount of nitrogen oxide gas in the furnace body 1 increases, the system automatically increases the speed of the corresponding secondary gas pump 34 through sensor feedback, quickly increasing the gas supply to the secondary burners 31 to ensure that unburned components in the flue gas are oxidized in time; when the load decreases, the gas pump 34 reduces the output pressure to avoid excessive gas supply leading to furnace temperature fluctuations or increased nitrogen oxide gas generation.

[0045] In some embodiments, the system further includes an oxygen supply component 8, which includes an oxygen tank 81 and a first oxygen pipe 82 connected to the oxygen tank 81. The first oxygen pipe 82 is connected to the secondary burner 31 and a first intake solenoid valve 83 is connected to the first oxygen pipe 82. The oxygen supply component 8 is used to supply oxygen to the secondary burner 31.

[0046] In this embodiment, the oxygen supply unit 8 directly supplies high-purity oxygen to the secondary burner 31 through the first oxygen pipe 82, forming an oxygen-rich combustion environment with the fuel-flue gas mixture provided by the mixed gas storage tank 32. The increased oxygen concentration significantly accelerates the combustion reaction rate, increasing the oxidation efficiency of unburned hydrocarbons and CO in the secondary combustion stage by 30%-50%. Simultaneously, it shortens the flame length and reduces the residence time in the high-temperature zone, thereby effectively suppressing the generation of thermal nitrogen oxides while ensuring complete combustion.

[0047] The first intake solenoid valve 83 is linked to the PLC control system of the hot blast stove, which can adjust the oxygen supply in real time according to the composition of the flue gas in the furnace. For example, when the gas concentration in the flue gas exceeds the standard, the system automatically increases the opening of the solenoid valve 83 to increase the oxygen enrichment of the secondary burner 31 to enhance the afterburning; when the nitrogen oxide gas concentration is close to the emission limit, the oxygen supply is reduced and the fuel flow is adjusted simultaneously to avoid local oxygen enrichment that leads to a surge in nitrogen oxide gas.

[0048] In addition, each secondary burner 31 is connected to an oxygen tank 81 via an independent first oxygen pipe 82 and is equipped with a first intake solenoid valve 83 to achieve precise oxygen supply to different furnace zones. For example, in a large rectangular furnace, the area near the feed inlet requires a higher oxygen concentration to control CO generation due to the large release of volatiles from the raw materials; while the area near the exhaust outlet requires an appropriate amount of oxygen to compensate for heat loss.

[0049] In some embodiments, the primary combustion element 2 includes a second oxygen pipe 22 connected to the oxygen tank 81 and an oxygen distribution box 23 connected to the second oxygen pipe 22. A second air intake solenoid valve 221 is connected to the second oxygen pipe 22, and a distribution gas pipe 24 is connected to the oxygen distribution box 23. The number of distribution gas pipes 24 corresponds to the number of primary burners 21, and the distribution gas pipes 24 are respectively connected to the corresponding primary burners 21.

[0050] In this embodiment, the initial combustion element 2 directly introduces high-purity oxygen from the oxygen tank 81 through the second oxygen pipe 22, and distributes it to each initial burner 21 via the oxygen distribution box 23, forming a staged oxygen-enriched combustion environment. In the initial combustion stage, the high concentration of oxygen can rapidly increase the flame temperature, accelerate the cracking of volatiles in the fuel and the combustion of fixed carbon, improve the burnout rate of the fuel in the initial combustion zone, reduce unburned components entering the secondary combustion zone, and reduce the potential for nitrogen oxide gas generation from the source.

[0051] The oxygen distribution box 23 adopts an equal-volume cavity and a porous flow equalization plate structure to evenly distribute the high-pressure oxygen input from the second oxygen pipe 22 to each distribution gas pipe 24. For example, in a hot blast stove equipped with four primary burners 21, the outlet pressure fluctuation range of the distribution box 23 is controlled within ±1%, ensuring that the oxygen supply deviation of each primary burner 21 is less than 3%, avoiding incomplete combustion due to insufficient local oxygen supply, such as increased CO generation or excessive oxygen supply causing local high temperature, leading to a surge in nitrogen oxide gas, thereby stabilizing the temperature and concentration fields in the primary combustion zone of the furnace.

[0052] In some embodiments, each of the gas distribution pipes 24 is connected to an oxygen distribution pump 25, which is used to regulate the rate at which oxygen enters the primary burner 21.

[0053] In this embodiment, the oxygen pump 25 corresponds one-to-one with the primary burner 21, forming a multi-zone independent oxygen regulation system. In a large rectangular furnace, the combustion characteristics of different zones vary significantly. For example, volatile matter is concentrated at the feed inlet, and heat loss is large at the exhaust outlet. The oxygen pump 25 allows for differentiated oxygen supply strategies for each zone: increasing oxygen levels at the feed inlet to accelerate volatilization and decomposition, and decreasing oxygen levels at the exhaust outlet to avoid localized oxygen enrichment. This design improves the uniformity of oxygen concentration distribution across the furnace cross-section by 35%, reducing combustion anomalies caused by oxygen deficiency or enrichment.

[0054] In some embodiments, the conversion element 6 includes a recovery solenoid valve 61 connected to the recovery pipe 5, the recovery solenoid valve 61 being used to control the opening or closing of the recovery pipe 5.

[0055] In this embodiment, the recovery solenoid valve 61 adopts a direct-acting high-pressure solenoid valve structure. After the coil is energized, the magnetic core completes the attraction action within 0.05 seconds, directly driving the valve disc to open or close the recovery pipe 5. Compared with traditional pneumatic / electric valves, the response speed is improved by more than 10 times. In the event of sudden changes in the hot blast stove load, such as emergency shutdown or rapid load increase, the system can instantly cut off or restore flue gas recovery through DCS signals, avoiding backflow of high-temperature flue gas and damage to the waste heat recovery device.

[0056] In addition, the valve seat and valve disc of the recycling solenoid valve 61 are made of hard alloy welding process, with a surface hardness of HRC60 or above, which can withstand the long-term scouring of dust in flue gas, such as coal dust and ash, without wear; the valve body integrates a self-cleaning spring structure, which automatically removes the dust between the valve disc and valve seat when the valve is closed, preventing sealing failure caused by coking or jamming.

[0057] In some embodiments, the conversion element 6 includes an exhaust solenoid valve 62 connected to the exhaust pipe 4 and located on the side near the furnace body 1, and an exhaust fan 63 is connected to the side of the exhaust pipe 4 away from the furnace body 1.

[0058] In this embodiment, a pressure sensor can be installed in the furnace as needed. It is a high-temperature resistant gas pressure sensor, such as the GEFRAN high-temperature melt pressure sensor. When the pressure increases, such as when combustion intensifies and the amount of flue gas generated increases, the system automatically increases the opening of the exhaust solenoid valve 62, such as from 50% to 80%, and simultaneously increases the speed of the exhaust fan 63, such as from 1500 rpm to 2500 rpm, to quickly discharge excess flue gas to maintain negative pressure.

[0059] In addition, if the pressure sensor detects that the furnace pressure is close to the positive pressure threshold, the exhaust solenoid valve 62 will immediately open fully, and the exhaust fan 63 will operate at maximum power to ensure that the furnace is always in a slightly negative pressure state, preventing high-temperature flue gas from leaking and causing safety accidents. Furthermore, the exhaust fan 63 is a high-temperature resistant fan, preferably a CY076 small multi-blade heat dissipation high-temperature resistant centrifugal fan.

[0060] In some embodiments, a gas detection element 9 is connected to the furnace body 1. The gas detection element 9 is equipped with an oxygen concentration sensor, a nitrogen concentration sensor and a nitrogen oxide concentration sensor. The gas detection element 9 is used to detect the oxygen concentration, nitrogen concentration and nitrogen oxide concentration in the furnace body 1.

[0061] In this embodiment, the gas detection element 9 monitors the concentrations of oxygen, nitrogen, and nitrogen oxides in the furnace body 1 in real time, constructs a three-dimensional combustion control model, and achieves a dynamic balance between combustion efficiency and pollutant emissions.

[0062] In addition, the oxygen concentration sensor continuously monitors the oxygen content in the furnace. Based on the correlation curve between oxygen concentration and combustion efficiency (e.g., a 1% decrease in oxygen concentration leads to a 0.5%-0.8% increase in combustion efficiency), the system automatically adjusts the fuel-to-air or-oxygen ratio. The nitrogen concentration sensor monitors the nitrogen percentage, providing more precise parameters for combustion optimization. When the system determines that there is an excess of air or oxygen, it automatically reduces the amount of combustion air or oxygen input to reduce exhaust heat loss. The nitrogen oxide concentration sensor monitors the amount of nitrogen oxide gas generated in real time. The system dynamically adjusts the combustion strategy based on the correlation model between nitrogen oxide gas and combustion temperature and oxygen concentration. For example, when the nitrogen oxide gas concentration approaches the emission limit, the system initiates staged combustion: first, fuel-rich combustion with a low oxygen concentration is performed to reduce the flame temperature and suppress nitrogen oxide gas generation; then, oxygen is supplemented by secondary air to complete combustion, ensuring combustion efficiency while controlling nitrogen oxide gas emissions. The specific structure and circuit connections of the control system are not the focus of this application and will not be elaborated here.

[0063] Example 1:

[0064] The furnace body 1 is made of high-temperature resistant alloy material, forming a closed combustion chamber inside to accommodate the combustion reaction and heat exchange. The outer wall of the furnace body 1 is equipped with an insulation layer to reduce heat loss. The initial combustion component 2 is fixedly connected to the middle of the inner side of the furnace body 1. The core of the initial combustion component 2 is the initial burner 21. There is at least one initial burner 21, and its specific number is adapted according to the capacity of the furnace body 1 and actual needs. They are evenly distributed in a ring on the inner wall of the furnace body 1. Each initial burner 21 is equipped with an ignition device for the initial combustion of natural gas. The air inlet of the initial burner 21 is connected to the feed pipe 71 and the distribution gas pipe 24 through pipelines to receive natural gas raw materials and combustion oxygen, respectively.

[0065] The upper inner side of the furnace body 1 is connected to the secondary combustion component 3. The core of the secondary combustion component 3 is the secondary burner 31. There is at least one secondary burner 31. The specific number is adapted according to the capacity of the furnace body 1 and actual needs. The installation position is higher than the primary burner 21. It is used to perform secondary high-temperature combustion on the incompletely burned flue gas generated by the primary combustion to reduce pollutant emissions. The air inlet end of the secondary burner 31 is connected to the feed pipe 71, the secondary feed pipe 33 and the first oxygen pipe 82 respectively. It can receive new natural gas, recovered flue gas and combustion oxygen.

[0066] A gas outlet pipe 4 is welded to the upper left side of the furnace body 1. The gas outlet pipe 4 is used to discharge compliant flue gas. A recovery pipe 5 is welded to the upper right side of the furnace body 1. The diameter of the recovery pipe 5 is the same as that of the gas outlet pipe 4. It is used to recover non-compliant flue gas. A conversion component 6 is fixed to the upper outer surface of the furnace body 1 by a bracket. The conversion component 6 includes a recovery solenoid valve 61 and a gas outlet solenoid valve 62. The recovery solenoid valve 61 is connected in series in the middle of the recovery pipe 5. It is used to control the opening and closing of the recovery pipe 5. The gas outlet solenoid valve 62 is connected in series at the end of the gas outlet pipe 4 near the furnace body 1. The end of the gas outlet pipe 4 away from the furnace body 1 is connected to an exhaust fan 63 through a flange. The exhaust fan 63 provides power to extract and discharge compliant flue gas.

[0067] The bottom of the furnace body 1 is fixed with bolts to the storage cylinder 7, which is a sealed pressure vessel with a volume designed according to the power of the furnace body 1, and is used to store natural gas. The upper right side of the storage cylinder 7 is welded with a raw material inlet pipe 72, which is connected to an external natural gas storage tank for replenishing raw materials. The top of the storage cylinder 7 is welded with a feeding pipe 71, which is divided into two branches by a three-way valve and connected to the primary burner 21 and the secondary burner 31 respectively. A flow control valve 73 is connected in series in the middle of the feeding pipe 71 to precisely adjust the natural gas delivery volume.

[0068] The secondary combustion component 3 also includes a mixed gas storage box 32, which is fixed to the outside of the furnace body 1 by a bracket. Its input end is connected to the recovery pipe 5 through a pipeline for temporarily storing the recovered substandard flue gas. The output end of the mixed gas storage box 32 is welded with a secondary material pipe 33. The number of secondary material pipes 33 is the same as that of the secondary burners 31. The end of each secondary material pipe 33 away from the storage box is connected to the corresponding secondary burner 31. A secondary gas pump 34 is connected in series in the middle of each secondary material pipe 33. The secondary gas pump 34 can adjust the speed at which the recovered flue gas enters the secondary burner 31.

[0069] An oxygen supply unit 8 is installed on the outside of the equipment. The core of the oxygen supply unit 8 is an oxygen tank 81. The output end of the oxygen tank 81 is connected to two oxygen pipes through a pressure reducing valve: one is a first oxygen pipe 82, which is directly connected to the secondary burner 31. A first intake solenoid valve 83 is connected in series in the middle to control the amount of oxygen supplied to the secondary burner 31. The other is a second oxygen pipe 22, which is connected to an oxygen distribution box 23. The oxygen distribution box 23 is fixed on the outside of the furnace body 1 and is used for oxygen diversion. A distribution gas pipe 24 is welded to the output end of the oxygen distribution box 23. The number of distribution gas pipes 24 is the same as that of the primary burner 21. The end of each distribution gas pipe 24 away from the distribution box is connected to the corresponding primary burner 21. An oxygen distribution pump 25 is connected in series in the middle of each distribution gas pipe 24. The oxygen distribution pump 25 can adjust the oxygen speed entering the primary burner 21.

[0070] Gas detection element 9 is fixed to the top of the inner side of the furnace body 1 by a bracket. The detection probe of gas detection element 9 extends into the combustion chamber inside the furnace body 1. It integrates oxygen concentration sensor, nitrogen concentration sensor and nitrogen oxide concentration sensor for real-time monitoring of flue gas composition. Gas detection element 9 is connected to the controller of components such as conversion element 6, flow control valve 73 and secondary gas pump 34 through signal lines to realize automatic control.

[0071] Compared with the prior art, the technical solution of this application has the following beneficial technical effects:

[0072] Through a staged design of primary and secondary burners, natural gas achieves thorough premixing and initial combustion in the primary combustion stage, effectively controlling the peak flame temperature and suppressing the generation of thermal nitrogen oxides. The secondary burner provides supplemental oxygen to unburned flue gas, ensuring complete fuel reaction and reducing fuel-type nitrogen oxides generated due to oxygen-deficient combustion. The conversion unit and recovery pipe form a closed-loop control system that monitors the flue gas composition in real time. When the flue gas does not meet standards, it is automatically drawn back into the furnace for secondary combustion, extending the flue gas residence time, promoting deep oxidation of unburned hydrocarbons, and reducing heat loss. Standard-compliant flue gas is discharged through the outlet pipe, avoiding increased energy consumption due to excessive circulation. This addresses the problems of uneven fuel-oxygen mixing and pollutants such as nitrogen oxides inherent in existing single-stage combustion technologies.

[0073] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A natural gas low-NOx burner for a hot blast stove, characterized in that, The furnace includes a furnace body (1) and a primary combustion element (2) connected within the furnace body (1). The primary combustion element (2) includes a primary burner (21) connected within the furnace body (1). At least one primary burner (21) is provided, and the primary burner (21) is used for the initial combustion of raw materials. A secondary combustion element (3) is connected within the furnace body (1). The secondary combustion element (3) includes a secondary burner (31) connected within the furnace body (1). At least one secondary burner (31) is provided, and the secondary burner (31)... Used for secondary combustion of the incompletely combusted flue gas in the furnace body (1); one side of the upper end of the furnace body (1) is connected to an exhaust pipe (4), the other side of the upper end of the furnace body (1) is connected to a recovery pipe (5), and the upper end of the furnace body (1) is connected to a conversion component (6). The conversion component (6) is used to discharge the flue gas in the furnace body (1) through the exhaust pipe (4) when the flue gas in the furnace body (1) meets the standard; and to recover the flue gas in the furnace body (1) through the recovery pipe (5) when the flue gas in the furnace body (1) does not meet the standard.

2. The natural gas low-NOx burner for a hot blast stove according to claim 1, characterized in that, The furnace body (1) is connected to a storage cylinder (7) at the bottom, and a feeding pipe (71) is connected to the storage cylinder (7). The feeding pipe (71) is connected to the primary burner (21) and the secondary burner (31) respectively. A raw material inlet pipe (72) is connected to the storage cylinder (7), and a flow control valve (73) is connected to the feeding pipe (71).

3. The natural gas low-NOx burner for a hot blast stove according to claim 1, characterized in that, The secondary combustion component (3) includes a mixed gas storage box (32) connected to the recovery pipe (5). A secondary material pipe (33) is connected to the mixed gas storage box (32). The number of secondary material pipes (33) corresponds to the number of secondary burners (31). The secondary material pipes (33) are respectively connected to the corresponding secondary burners (31).

4. A natural gas low-NOx burner for a hot blast stove according to claim 3, characterized in that, Each of the secondary feed pipes (33) is connected to a secondary air pump (34), which is used to regulate the speed at which the mixed gas enters the secondary burner (31).

5. A natural gas low-NOx burner for a hot blast stove according to claim 1, characterized in that, It also includes an oxygen supply unit (8), which includes an oxygen tank (81) and a first oxygen pipe (82) connected to the oxygen tank (81). The first oxygen pipe (82) is connected to the secondary burner (31), and a first intake solenoid valve (83) is connected to the first oxygen pipe (82). The oxygen supply unit (8) is used to supply oxygen to the secondary burner (31).

6. A natural gas low-NOx burner for a hot blast stove according to claim 5, characterized in that, The initial combustion component (2) includes a second oxygen pipe (22) connected to the oxygen tank (81) and an oxygen distribution box (23) connected to the second oxygen pipe (22). A second intake solenoid valve (221) is connected to the second oxygen pipe (22), and a distribution gas pipe (24) is connected to the oxygen distribution box (23). The number of distribution gas pipes (24) corresponds to the number of initial burners (21), and the distribution gas pipes (24) are respectively connected to the corresponding initial burners (21).

7. A natural gas low-NOx burner for a hot blast stove according to claim 6, characterized in that, Each of the gas distribution pipes (24) is connected to an oxygen distribution pump (25), which is used to regulate the speed at which oxygen enters the primary burner (21).

8. A natural gas low-NOx burner for a hot blast stove according to claim 7, characterized in that, The conversion component (6) includes a recovery solenoid valve (61) connected to the recovery pipe (5), which is used to control the opening or closing of the recovery pipe (5).

9. A natural gas low-NOx burner for a hot blast stove according to claim 8, characterized in that, The conversion component (6) includes an exhaust solenoid valve (62) connected to the exhaust pipe (4) and close to the furnace body (1), and an exhaust fan (63) is connected to the side of the exhaust pipe (4) away from the furnace body (1).

10. A natural gas low-NOx burner for a hot blast stove according to claim 9, characterized in that, A gas detection device (9) is connected to the furnace body (1). The gas detection device (9) is equipped with an oxygen concentration sensor, a nitrogen concentration sensor and a nitrogen oxide concentration sensor. The gas detection device (9) is used to detect the oxygen concentration, nitrogen concentration and nitrogen oxide concentration in the furnace body (1).

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