A low-nitrogen burner for hydrogen fluoride rotary kiln

Abstract

The utility model discloses a low nitrogen combustor for hydrogen fluoride rotary kiln relates to hydrogen fluoride production equipment technical field. The utility model discloses the following: combustor main part, burn -out chamber and igniter, burn -out chamber is hollow cylinder type structure, and burn -out chamber is opened with primary circulating flue gas entrance, burn -out air inlet and secondary circulating flue gas entrance in proper order along the direction of being away from combustor main part, and primary circulating flue gas entrance and secondary circulating flue gas entrance all are communicated with the smoke outlet of rotary kiln through flue gas circulation mechanism. Utilize primary circulating flue gas to reduce flame temperature, and fundamentally restrain the generation of thermal type nitrogen oxides, and the oxygen is supplemented after primary circulating flue gas through burn -out air inlet, and the product of incomplete combustion is promoted to burn -out fully, and nitrogen oxides generation is effectively inhibited, and environmental pollution is reduced, and utilize secondary circulating flue gas to make fuel before entering rotary kiln has fallen to the temperature required for reaction, avoid the influence of temperature fluctuation to hydrogen fluoride reaction in rotary kiln, improve product quality and production efficiency.

Description

Technical Field

[0001] This utility model relates to the technical field of hydrogen fluoride production equipment, and more specifically to a low-NOx burner for a hydrogen fluoride rotary kiln. Background Technology

[0002] In the hydrogen fluoride production process, the rotary kiln needs to maintain a stable high-temperature environment to ensure the reaction proceeds fully. During production, the high-temperature flue gas at the kiln inlet is approximately 600°C, and the circulating flue gas at the outlet is approximately 400°C. The heat generated by combustion is used to supplement the heat consumed during the rotary kiln's production process. As a core heating component, the burner's combustion efficiency, fuel adaptability, and environmental performance directly affect production quality and cost. Currently, commonly used burners in hydrogen fluoride rotary kilns have the following problems:

[0003] Excessive nitrogen oxide emissions: Traditional burners, due to uneven air-fuel mixing and excessively high combustion temperatures, result in high nitrogen oxide production, making it difficult to meet current stringent environmental emission standards (such as nitrogen oxide emission concentrations needing to be below 200 mg / m³). 3 This increases the cost of environmental treatment.

[0004] Combustion stability and temperature control are difficult: Hydrogen fluoride rotary kilns have strict requirements for the inlet flue gas temperature (which needs to be stable at 600℃). Traditional burners cannot accurately control the flue gas temperature after complete combustion, which is prone to temperature fluctuations, affecting the production efficiency and product purity of hydrogen fluoride. Furthermore, it is necessary to ensure that the fuel is completely burned to avoid secondary combustion or incomplete combustion in the kiln, which would affect product quality.

[0005] To address these issues, there is an urgent need to develop a burner that is highly adaptable to fuels, has low nitrogen emissions, and offers precise temperature control to meet the production requirements of hydrogen fluoride rotary kilns. Utility Model Content

[0006] In view of this, the present invention aims to provide a low-NOx dual-fuel burner for a hydrogen fluoride rotary kiln to at least partially solve the technical problems of excessive nitrogen oxide emissions, combustion stability and temperature control in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A low-NOx burner for a hydrogen fluoride rotary kiln includes: a burner body, a burnout chamber, and an igniter; the burner body has a gas supply channel, and the burnout chamber is a hollow cylindrical structure, one end of which is fixed to the burner body and has a burnout chamber inlet for connecting to the gas supply channel, and the other end of which has a burnout chamber outlet for connecting to the rotary kiln inlet; the burnout chamber has a primary circulating flue gas inlet, a burnout air inlet, and a secondary circulating flue gas inlet sequentially arranged along the direction away from the burner body, and the primary circulating flue gas inlet and the secondary circulating flue gas inlet are both connected to the flue gas outlet of the rotary kiln through a flue gas circulation mechanism; the igniter is installed in the burnout chamber inlet.

[0009] The beneficial effects achievable by this invention are as follows: Staged combustion and cooling are employed, utilizing primary circulating flue gas to lower the flame temperature, fundamentally suppressing the generation of fuel-type and thermal nitrogen oxides; after the primary circulating flue gas, oxygen is replenished through the burnout air inlet, promoting the complete combustion of incomplete combustion products, effectively suppressing nitrogen oxide generation and reducing environmental pollution; furthermore, the secondary circulating flue gas ensures that the fuel is cooled to the required reaction temperature before entering the rotary kiln, avoiding the impact of temperature fluctuations on the hydrogen fluoride reaction within the rotary kiln, thus improving product quality and production efficiency.

[0010] Preferably, the exhaust direction of the primary circulating flue gas inlet, the exhaust direction of the burnout air inlet, and the exhaust direction of the secondary circulating flue gas inlet are all arranged along the tangent direction of the burnout chamber.

[0011] Preferably, the smoke outlet direction of the primary circulating flue gas inlet and the smoke outlet direction of the secondary circulating flue gas inlet are both perpendicular to the smoke outlet direction of the burnout air inlet.

[0012] Preferably, a high-temperature resistant insulation layer is provided on the inner wall of the combustion chamber, the high-temperature resistant insulation layer comprising an insulation fiber felt layer, an alumina hollow sphere layer and a corundum refractory brick layer that are sequentially fixed to the inner wall of the combustion chamber.

[0013] Preferably, a first temperature sensor is installed on the inner wall of the burnout chamber between the primary circulating flue gas inlet and the burnout air inlet, and a second temperature sensor is installed at the outlet of the burnout chamber.

[0014] Preferably, both the primary circulating flue gas inlet and the secondary circulating flue gas inlet are equipped with flue gas regulating valves at their inlet ends.

[0015] Preferably, a blower and an air flow regulating valve are installed at the burnout air inlet.

[0016] Preferably, the burner body includes an outer sleeve, an inner sleeve, and a central tube, which are sequentially sleeved from the outside to the inside and are all coaxially arranged with the combustion chamber; one end of the outer sleeve is fixed to the inlet of the combustion chamber, and the other end is sealed to the inner sleeve through a first sealing plate, and a biomass gas inlet is provided on the side wall near its other end; the end of the inner sleeve away from the combustion chamber is sealed to the central tube through a second sealing plate, and a combustion air inlet is provided on its side wall away from the combustion chamber; a natural gas inlet is provided on the end of the central tube away from the combustion chamber.

[0017] The gas transmission channel includes a biomass gas loop channel disposed between the outer sleeve and the inner sleeve and connecting the biomass gas inlet and the burnout chamber inlet, a combustion air loop channel disposed between the inner sleeve and the central pipe and connecting the combustion air inlet and the burnout chamber inlet, and a natural gas channel disposed in the inner cavity of the central pipe and connecting the natural gas inlet and the burnout chamber inlet.

[0018] Preferably, the outlet direction of the biomass gas inlet is arranged along the tangent direction of the outer sleeve; the outlet direction of the combustion air inlet is arranged along the tangent direction of the inner sleeve.

[0019] Preferably, the biomass gas inlet and the combustion air inlet have opposite gas outlet directions.

[0020] As can be seen from the above technical solution, compared with the prior art, this utility model discloses a low-NOx burner for a hydrogen fluoride rotary kiln, which has the following beneficial effects:

[0021] 1. Strong fuel adaptability and reduced costs: The use of both biomass gas and natural gas as fuels avoids production stoppages caused by the interruption of a single fuel and improves production continuity; at the same time, biomass gas, as a renewable energy source, can significantly reduce fuel costs.

[0022] 2. Staged combustion, high efficiency and low NOx: By reducing the flame temperature through primary flue gas circulation, the formation of fuel-type NOx and thermal NOx is fundamentally suppressed. After primary flue gas circulation, oxygen is replenished through the burnout air inlet, ensuring the complete combustion of unburned products (CO, H2, Char, etc.), effectively suppressing the formation of nitrogen oxides, with NOx emission concentration ≤100mg / m³. 3 It is far below the national environmental protection standards, reducing environmental pollution; and it ensures that the fuel is completely burned before entering the rotary kiln, avoiding local overheating or uneven product quality caused by continued combustion in the kiln, while improving thermal efficiency.

[0023] 3. Precise temperature control improves production quality: By introducing secondary circulating flue gas, the flue gas temperature is further adjusted, ensuring that the flue gas temperature entering the rotary kiln is stabilized at the temperature required for the reaction. This avoids the impact of temperature fluctuations on the hydrogen fluoride reaction in the rotary kiln, thereby improving product quality and production efficiency.

[0024] 4. Simple structure, saving space and cost: In traditional dual-fuel burners, the air passages for biomass gas and natural gas are often designed separately, which is complex and difficult to maintain. This burner body uses a single combustion air ring for both natural gas and biomass gas, which greatly simplifies the burner structure and reduces manufacturing and maintenance difficulties, thus saving manufacturing costs. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, 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 embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 This utility model provides a three-dimensional structural diagram of a low-NOx dual-fuel burner for a hydrogen fluoride rotary kiln.

[0027] Figure 2 This utility model provides a cross-sectional structural diagram of a low-NOx dual-fuel burner for a hydrogen fluoride rotary kiln.

[0028] Figure 3 A schematic diagram of the high-temperature resistant insulation layer structure provided by this utility model.

[0029] Figure 4 This is a three-dimensional structural diagram of the burner body provided by this utility model from one angle.

[0030] Figure 5 This is a side view of the burner body structure provided by this utility model.

[0031] Figure 6 This is a three-dimensional structural diagram of the burner body provided by this utility model from another angle.

[0032] Figure 7 A schematic cross-sectional view of the burner body provided by this utility model.

[0033] In the diagram: 1. Burner body; 11. Outer sleeve; 111. Biomass gas inlet; 12. Inner sleeve; 121. Combustion air inlet; 13. Central tube; 131. Natural gas inlet; 14. First sealing plate; 15. Second sealing plate; 16. Biomass gas loop; 17. Combustion air loop; 18. Natural gas passage; 2. Combustion chamber; 21. Combustion chamber inlet; 22. Combustion chamber outlet; 23. Primary circulation flue gas inlet; 24. Combustion air inlet; 25. Secondary circulation flue gas inlet; 3. High-temperature resistant insulation layer; 31. Insulation fiber felt layer; 32. Alumina hollow sphere layer; 33. Corundum refractory brick layer; 4. First temperature sensor; 5. Second temperature sensor. Detailed Implementation

[0034] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0035] In the description of this utility model, it should be understood that the terms "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 this utility model 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 this utility model.

[0036] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0037] Please see Figures 1-7This utility model discloses a low-NOx burner for a hydrogen fluoride rotary kiln, comprising: a burner body 1, a burnout chamber 2, and an igniter (not shown in the figure); multiple gas supply channels are arranged at intervals inside the burner body 1; the burnout chamber 2 is a hollow cylindrical structure, one end of which is fixed to the burner body 1 and has a burnout chamber inlet 21 for connecting to the gas supply channels, and the other end has a burnout chamber outlet 22 for connecting to the rotary kiln inlet; the burnout chamber 2 has a primary circulating flue gas inlet 23, a burnout air inlet 24, and a secondary circulating flue gas inlet 25 sequentially opened in the direction away from the burner body 1, and both the primary circulating flue gas inlet 23 and the secondary circulating flue gas inlet 25 are connected to the flue gas outlet of the rotary kiln through a flue gas circulation mechanism; the igniter is installed inside the burnout chamber inlet 21.

[0038] The flue gas recirculation mechanism may include a recirculation pump and a recirculation pipeline. The inlet of the recirculation pump is connected to the flue gas outlet of the rotary kiln, and one end of the recirculation pipeline is connected to the outlet of the recirculation pump, while the other end is connected to the primary recirculation flue gas inlet 23 and the secondary recirculation flue gas inlet 25, respectively. The flue gas recirculation mechanism may also adopt any form of flue gas recirculation mechanism in the prior art.

[0039] The exhaust direction of the primary circulating flue gas inlet 23, the exhaust direction of the burnout air inlet 24, and the exhaust direction of the secondary circulating flue gas inlet 25 are all arranged along the tangential direction of the burnout chamber 2. This ensures that the primary circulating flue gas, burnout air, and secondary circulating flue gas can fully mix with the combustion gas in the burnout chamber 2 after entering the burnout chamber 2, promoting complete combustion of the combustion gas and avoiding the generation of a large amount of nitrogen oxides.

[0040] The exhaust direction of the primary circulation flue gas inlet 23 and the exhaust direction of the secondary circulation flue gas inlet 25 are both perpendicular to the exhaust direction of the burnout air inlet 24, which enhances the swirling effect and promotes full mixing with the gas.

[0041] A high-temperature resistant insulation layer 3 is laid on the inner wall of the combustion chamber 2. The high-temperature resistant insulation layer 3 includes an insulation fiber felt layer 31, an alumina hollow sphere layer 32, and a corundum refractory brick layer 33, which are sequentially fixed to the inner wall of the combustion chamber 2. The internal corundum refractory bricks have a refractory temperature ≥1600℃, the alumina hollow sphere layer 32 has good heat resistance and insulation performance, and the insulation fiber felt layer 31 further enhances the insulation effect. Through the high-temperature resistant insulation layer 3, the outer surface temperature of the combustion chamber 2 during use does not exceed 60℃.

[0042] Temperature sensors are installed on the inner wall of the combustion chamber 2 between the primary circulating flue gas inlet 23 and the combustion air inlet 24, as well as at the combustion chamber outlet 22. These temperature sensors monitor the gas temperature after combustion of the primary circulating flue gas and the temperature at the combustion chamber outlet 22 after combustion of the secondary circulating flue gas.

[0043] Flue gas regulating valves are installed at the air inlets of both the primary circulating flue gas inlet 23 and the secondary circulating flue gas inlet 25. The primary circulating flue gas volume is adjusted based on the temperature sensor monitoring results after the primary circulating flue gas to control the corresponding temperature below 1000℃. The secondary circulating flue gas volume is adjusted based on the temperature sensor monitoring results after the secondary circulating flue gas to ensure that the flue gas temperature at the combustion chamber outlet 22 is stable at 600℃±5℃.

[0044] A blower and an air flow regulating valve are installed at the 24th burnout air inlet to adjust the amount of air supplied according to process requirements, ensuring complete combustion of fuel.

[0045] The burner body 1 includes an outer sleeve 11, an inner sleeve 12, and a central pipe 13, which are sequentially sleeved from the outside to the inside and are all coaxially arranged with the combustion chamber 2. One end of the outer sleeve 11 is fixed to the combustion chamber inlet 21, and the other end is sealed to the inner sleeve 12 through a first sealing plate 14. A biomass gas inlet 111 is provided on the side wall near the other end of the outer sleeve 11. The end of the inner sleeve 12 away from the combustion chamber 2 is sealed to the central pipe 13 through a second sealing plate 15. An air-supporting inlet 121 is provided on the side wall of the combustion chamber 2. A natural gas inlet 131 is provided on the end of the central pipe 13 away from the combustion chamber 2. The inner side wall of each pipe is provided with a high-temperature resistant coating, such as an alumina ceramic coating, to prevent corrosion of the pipe by high-temperature gas.

[0046] The gas transmission channels include a biomass gas loop 16 located between the outer sleeve 11 and the inner sleeve 12, connecting the biomass gas inlet 111 and the burnout chamber inlet 21; a combustion air loop 17 located between the inner sleeve 12 and the central pipe 13, connecting the combustion air inlet 121 and the burnout chamber inlet 21; and a natural gas channel 18 located within the central pipe 13, connecting the natural gas inlet 131 and the burnout chamber inlet 21. The burner body 1 has dual fuel input channels for biomass gas and natural gas, allowing for flexible fuel switching. The combustion air loop is located between the biomass gas loop and the natural gas input channel, enabling thorough mixing with both natural gas and biomass gas. This design is simple and compact, occupies little space, has low manufacturing costs, and is easy to maintain.

[0047] Biomass gas inlet 111, combustion air inlet 121 and natural gas inlet 131 are all equipped with corresponding gas supply systems. The supply systems are equipped with pressure and flow regulating devices to regulate the input amount and input pressure of the corresponding gases.

[0048] Specifically, to ensure complete combustion of natural gas, based on the required air-to-fuel ratio, the flow area of ​​the combustion air loop 17 is approximately nine times that of the natural gas channel 18. To maintain constant power and heat load during fuel switching, the energy input per unit time must be equal. Therefore, based on the ratio of biomass fuel gas to natural gas calorific value, the flow area of ​​the biomass fuel gas loop 16 is approximately seven times that of the natural gas channel 18.

[0049] The outlet direction of the biomass gas inlet 111 is arranged along the tangent direction of the outer sleeve 11; the outlet direction of the combustion air inlet 121 is arranged along the tangent direction of the inner sleeve 12. The biomass gas and combustion air are mixed after swirling along their respective annular cavities, which enhances the mixing effect of the combustion air with the biomass gas and natural gas, and ensures complete combustion of the fuel.

[0050] The biomass gas inlet 111 and the combustion air inlet 121 have opposite gas outlet directions, which can further enhance the mixing degree of combustion air and biomass gas.

[0051] The working process of the low-NOx dual-fuel burner for a hydrogen fluoride rotary kiln provided by this utility model is as follows:

[0052] 1. Fuel supply and blending: Based on production needs, biomass gas combustion is given priority. Natural gas combustion is used when biomass gas supply is insufficient or malfunctions occur.

[0053] 2. Preliminary Combustion: The fuel output from the burner body 1 is fully mixed with the combustion air at the inlet of the burnout chamber and ignited by the igniter. At the same time, the primary circulating flue gas is introduced into the burnout chamber 2 from the primary circulating flue gas inlet 23, which comes into contact with the flame and reduces the flame temperature (controlling the flame temperature ≤1000℃), thereby reducing the generation of thermal nitrogen oxides. In particular, the fuel (natural gas or biomass gas) is mixed and burned with air under the condition that the excess air coefficient is much less than 1 through the fuel supply system, forming an oxygen-deficient reducing flame, which fundamentally inhibits the generation of fuel nitrogen oxides and thermal nitrogen oxides.

[0054] 3. Complete combustion: The high-temperature flue gas (temperature 1000℃) after initial combustion and cooling flows along the inner cavity of the combustion chamber 2 to the combustion chamber outlet 22. The combustion air is introduced from the combustion air inlet 24 in the middle of the combustion chamber 2 to replenish oxygen and mix with the unburned gas to ensure complete combustion of fuel.

[0055] 4. Temperature regulation: The flue gas after combustion (temperature 800-900℃) continues to flow to the outlet 22 of the combustion chamber. The secondary circulating flue gas is introduced from the secondary circulating flue gas inlet 25, mixes with the flue gas after combustion and cools down, so that the flue gas temperature is stably reduced to 600℃, and finally introduced into the hydrogen fluoride rotary kiln to meet the production requirements.

[0056] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0057] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A low-NOx burner for a hydrogen fluoride rotary kiln, characterized in that, include: The burner body (1), the burnout chamber (2), and the igniter are provided. The burner body (1) is provided with a gas supply channel. The burnout chamber (2) is a hollow cylindrical structure. One end of the chamber is fixed to the burner body (1) and the end of the chamber is provided with a burnout chamber inlet (21) for connecting the gas supply channel. The other end is provided with a burnout chamber outlet (22) for connecting the inlet of the rotary kiln. The burnout chamber (2) is provided with a primary circulating flue gas inlet (23), a burnout air inlet (24), and a secondary circulating flue gas inlet (25) in sequence along the direction away from the burner body (1). The primary circulating flue gas inlet (23) and the secondary circulating flue gas inlet (25) are both connected to the flue gas outlet of the rotary kiln through a flue gas circulation mechanism. The igniter is installed in the burnout chamber inlet (21).

2. A low-NOx burner for a hydrogen fluoride rotary kiln according to claim 1, characterized in that, The exhaust direction of the primary circulating flue gas inlet (23), the exhaust direction of the burnout air inlet (24), and the exhaust direction of the secondary circulating flue gas inlet (25) are all arranged along the tangential direction of the burnout chamber (2).

3. A low-NOx burner for a hydrogen fluoride rotary kiln according to claim 2, characterized in that, The exhaust direction of the primary circulating flue gas inlet (23) and the exhaust direction of the secondary circulating flue gas inlet (25) are both perpendicular to the exhaust direction of the burnout air inlet (24).

4. A low-NOx burner for a hydrogen fluoride rotary kiln according to claim 1, characterized in that, A high-temperature resistant insulation layer (3) is provided on the inner wall of the burnout chamber (2). The high-temperature resistant insulation layer (3) includes an insulation fiber felt layer (31), an alumina hollow sphere layer (32), and a corundum refractory brick layer (33) that are fixed to the inner wall of the burnout chamber (2) in sequence.

5. A low-NOx burner for a hydrogen fluoride rotary kiln according to claim 1, characterized in that, A first temperature sensor (4) is installed on the inner wall of the burnout chamber (2) between the primary circulating flue gas inlet (23) and the burnout air inlet (24), and a second temperature sensor (5) is installed at the burnout chamber outlet (22).

6. A low-NOx burner for a hydrogen fluoride rotary kiln according to claim 5, characterized in that, Flue gas regulating valves are installed at the inlet ends of both the primary circulating flue gas inlet (23) and the secondary circulating flue gas inlet (25).

7. A low-NOx burner for a hydrogen fluoride rotary kiln according to claim 6, characterized in that, A blower and an air flow regulating valve are installed at the burnout air inlet (24).

8. A low-NOx burner for a hydrogen fluoride rotary kiln according to any one of claims 1-7, characterized in that, The burner body (1) includes an outer sleeve (11), an inner sleeve (12), and a central tube (13) arranged coaxially with the combustion chamber (2) from the outside to the inside. One end of the outer sleeve (11) is fixed to the combustion chamber inlet (21), and the other end is sealed to the inner sleeve (12) through a first sealing plate (14). A biomass gas inlet (111) is provided on the side wall near the other end of the outer sleeve (11). The end of the inner sleeve (12) away from the combustion chamber (2) is sealed to the central tube (13) through a second sealing plate (15). An air-supporting inlet (121) is provided on the side wall away from the combustion chamber (2). A natural gas inlet (131) is provided on the end of the central tube (13) away from the combustion chamber (2). The gas transmission channel includes a biomass gas loop (16) disposed between the outer sleeve (11) and the inner sleeve (12) and connecting the biomass gas inlet (111) and the burnout chamber inlet (21); a combustion air loop (17) disposed between the inner sleeve (12) and the central pipe (13) and connecting the combustion air inlet (121) and the burnout chamber inlet (21); and a natural gas channel (18) disposed in the inner cavity of the central pipe (13) and connecting the natural gas inlet (131) and the burnout chamber inlet (21).

9. A low-NOx burner for a hydrogen fluoride rotary kiln according to claim 8, characterized in that, The outlet direction of the biomass gas inlet (111) is arranged along the tangent direction of the outer sleeve (11); the outlet direction of the combustion air inlet (121) is arranged along the tangent direction of the inner sleeve (12).

10. A low-NOx burner for a hydrogen fluoride rotary kiln according to claim 9, characterized in that, The biomass gas inlet (111) and the combustion air inlet (121) have opposite gas outlet directions.

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