A high combustion stability micro-mixing nozzle

Abstract

The application discloses a high combustion stability micro-mixing nozzle and belongs to the field of advanced combustion technology. The application solves the problem that the traditional micro-mixing nozzle is difficult to maintain high combustion stability when fuel components and operation conditions change. The nozzle comprises a fuel rod, a sliding air-fuel mixing module and a fixed air-fuel mixing module which are coaxially arranged from inside to outside, one end of the fuel rod is fixed on a fuel distribution cavity cover plate of a burner, the fixed air-fuel mixing module is fixed on an end cover of the burner, and the sliding air-fuel mixing module is driven to move along a central axis by an actuator. The first annular channel and the second annular channel are respectively used as air-fuel mixing channels in different nozzle modes. The burner can be operated efficiently and stably.

Description

Technical Field

[0001] This invention relates to a micro-mixing nozzle with high combustion stability, belonging to the field of advanced combustion technology. Background Technology

[0002] Improving burner combustion stability can significantly enhance its ability to withstand changes in fuel composition and operating conditions. Changes in fuel composition lead to variations in the Wobbe number. When the Wobbe number changes beyond a certain range, the airflow matching characteristics of existing burners deteriorate, resulting in problems such as blow-out, backfire, thermoacoustic oscillations, and increased pollutant emissions. Furthermore, due to burner structural limitations and combustion organization strategies, the blow-out and backfire equivalence ratio limits of the combustion chamber itself restrict the load regulation range achievable when facing changes in operating conditions. To achieve a wider load regulation ratio, the common approach is to equip the burner with more complex valve systems or add diffusion combustion organization strategies. This significantly increases the design, manufacturing, and operating costs of the burner, and also increases pollutant emissions. These problems will seriously affect the safe, efficient, and stable operation of existing burners.

[0003] Micro-mixing combustion technology is a low-emission combustion technology; however, traditional micro-mixing nozzles struggle to maintain high combustion stability when fuel composition and operating conditions change. Therefore, there is an urgent need for a novel micro-mixing nozzle structure that can maintain high airflow velocity to prevent backfire when burning fuels with high flame propagation velocities, and maintain low airflow velocity to prevent blow-out when burning fuels with low flame propagation velocities. Furthermore, it should maintain high homogeneity of air-fuel mixing even when air and fuel flow rates, pressures, and temperatures change, thus ensuring combustion stability while achieving low emissions. Summary of the Invention

[0004] The present invention aims to solve the above-mentioned technical problems and thereby provide a micro-mixing nozzle with high combustion stability.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: A high-combustion-stability micro-mixing nozzle includes a fuel rod, a sliding air-fuel mixing module, and a fixed air-fuel mixing module arranged coaxially from the inside out. One end of the fuel rod is fixedly mounted on the fuel distribution chamber cover of the burner, and the fixed air-fuel mixing module is fixedly mounted on the end cover of the burner. An actuator drives the sliding air-fuel mixing module to move along the central axis. The fuel rod has a fuel channel and several fuel through holes. The fuel channel is arranged along the axial direction of the fuel rod, with one end being the fuel inlet and the other end being a closed end. The several fuel through holes are distributed circumferentially along the fuel rod and communicate with the fuel channel. The other end of the fuel channel and the several fuel through holes are located inside the fixed air-fuel blending module. A first annular channel is formed between the outer wall of the fuel rod and the inner wall of the sliding air-fuel mixing module, with one end of the first annular channel being the air inlet. When the sliding air-fuel blending module slides toward the fuel inlet end, a second annular channel is formed between the outer wall of the fuel rod and the inner wall of the fixed air-fuel blending module, and the fuel through hole is connected to the second annular channel.

[0006] Furthermore, the other end of the fuel rod is located in the same plane as the other end of the fixed air-fuel blending module.

[0007] Furthermore, the sliding air-fuel blending module includes a first cylinder and a retaining ring fixedly fitted at one end of the first cylinder, and the other end of the first cylinder is slidably fitted between the fixed air-fuel blending module and the fuel rod.

[0008] Furthermore, the other end of the sliding air-fuel blending module is a gradually expanding outlet.

[0009] Furthermore, the fixed air-fuel blending module is a second cylinder, and the cross-sectional shape of the through hole inside the second cylinder is set to follow the cross-sectional shape of the outer wall of the first cylinder.

[0010] Furthermore, the corner structure between the other end of the second cylinder and its inner wall is a right angle.

[0011] Furthermore, one end of the fuel rod is coaxial and integrally machined with a ring platform.

[0012] Furthermore, the closed end of the fuel passage is hemispherical.

[0013] Furthermore, the actuator is fixedly mounted on the burner housing.

[0014] Furthermore, the actuator is a stepper motor.

[0015] Compared with the prior art, the present invention has the following advantages: The first annular channel and the second annular channel serve as air-fuel mixing channels for different nozzle modes.

[0016] The high combustion stability micro-mixing nozzle of the present invention has two nozzle modes: In the first nozzle mode, the other end of the sliding air-fuel mixing module, the other end of the fuel rod, and the other end of the fixed air-fuel mixing module are all located in the same plane. Air enters the first annular channel from the air inlet end, and fuel enters the fuel channel from the fuel inlet end, and then flows out into the first annular channel through the fuel through hole, where it mixes with the air entering the first annular channel, forming an air-fuel mixture at the outlet of the other end of the first annular channel.

[0017] In the second nozzle mode, the actuator drives the sliding air-fuel mixing module to move along the axis toward the fuel inlet end, so that the other end of the sliding air-fuel mixing module is located in the second annular channel, exposing the fuel through hole to the inside of the fixed air-fuel mixing module. Air enters the first annular channel from the air inlet end, and fuel enters the fuel channel from the fuel inlet end, and then flows out through the fuel through hole into the second annular channel, where it mixes with the air entering the second annular channel, forming an air-fuel mixture at the outlet of the other end of the second annular channel.

[0018] Compared with existing technologies, the high combustion stability micro-mixing nozzle of the present invention achieves efficient and stable burner operation through a simpler structural form when faced with changes in fuel composition and operating conditions.

[0019] For example, when burning hydrogen, the flame spreads quickly, so the first nozzle mode is used, and the airflow is fast to prevent backfire.

[0020] When using natural gas, the flame spreads slowly, so a second nozzle mode is used, which slows down the airflow to prevent it from being blown out.

[0021] When the burner uses the same fuel, under ignition conditions, the airflow is low, so the first nozzle mode is used to increase the air velocity and prevent backfire. Under design load, the airflow is high, so the second nozzle mode is used to reduce the air velocity, minimize pressure loss, control the flame anchoring position for stable combustion, and prevent blow-out. In addition, adjusting the air velocity enhances air-fuel mixing, achieving low pollutant emissions.

[0022] When the burner uses the same fuel, and the air flow rate remains constant, the first nozzle mode is used at low air temperatures to increase the air velocity, enhance mixing, and achieve low pollutant emissions. At high air temperatures, the second nozzle mode is used to maintain a constant air velocity, ensuring that the air mixing uniformity remains consistent and maintaining low pollutant emissions.

[0023] This invention can be applied in fields such as gas turbines, aircraft engines, aerospace engines, and industrial kilns. Attached Figure Description

[0024] Figure 1 This is a first main cross-sectional view of the high combustion stability micro-mixing nozzle of the present invention (in the first nozzle mode, and the positional relationship between the micro-mixing nozzle and the burner end cap and fuel distribution chamber cover plate is shown in the figure). Figure 2 This is a second main cross-sectional view of the high combustion stability micro-mixing nozzle of the present invention (in the second nozzle mode, and the positional relationship between the micro-mixing nozzle and the burner end cap and fuel distribution chamber cover plate is shown in the figure). Figure 3This is a first three-dimensional structural schematic diagram of the high combustion stability micro-mixing nozzle of the present invention (in the first nozzle mode). Figure 4 This is a first three-dimensional cross-sectional view of the high combustion stability micro-mixing nozzle of the present invention (in the first nozzle mode). Figure 5 This is a schematic diagram of the second three-dimensional structure of the high combustion stability micro-mixing nozzle of the present invention (in the second nozzle mode). Figure 6 This is a second three-dimensional cross-sectional view of the high combustion stability micro-mixing nozzle of the present invention (in the second nozzle mode). Figure 7 A three-dimensional structural diagram of a fixed air-fuel blending module; Figure 8 A three-dimensional structural diagram of a sliding air-fuel blending module; Figure 9 This is a three-dimensional structural diagram of the fuel rod.

[0025] In the picture: 1. Fuel rod; 11. Fuel channel; 12. Fuel through hole; 2. Sliding air-fuel mixing module; 21. First cylinder; 22. Retaining ring; 3. Fixed air-fuel mixing module; 4. Fuel distribution chamber cover plate; 5. End cover; 6. First annular channel; 7. Second annular channel; 8. Ring platform; 9. Actuator. Detailed Implementation

[0026] Specific implementation method one: Combining Figures 1-9 This description of embodiments provides a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that the descriptions of "front," "rear," "left," "right," "inner," "outer," "left side," "right side," "upper part," "lower part," "top," and "bottom" in this invention are defined based on the orientation or positional relationships shown in the accompanying drawings. They are merely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the described structure must be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] In the description of this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] A high-combustion-stability micro-mixing nozzle includes a fuel rod 1, a sliding air-fuel mixing module 2, and a fixed air-fuel mixing module 3 arranged coaxially from the inside out. One end of the fuel rod 1 is fixedly mounted on the fuel distribution chamber cover plate 4 of the burner, and the fixed air-fuel mixing module 3 is fixedly mounted on the end cover 5 of the burner. The sliding air-fuel mixing module 2 is moved along the central axis by an actuator 9. The fuel rod 1 has a fuel channel 11 and several fuel through holes 12. The fuel channel 11 is arranged along the axial direction of the fuel rod 1, with one end being the fuel inlet and the other end being a closed end. The several fuel through holes 12 are distributed circumferentially along the fuel rod 1 and communicate with the fuel channel 11. The other end of the fuel channel 11 and the several fuel through holes 12 are all located inside the fixed air-fuel blending module 3. A first annular channel 6 is formed between the outer wall of the fuel rod 1 and the inner wall of the sliding air-fuel mixing module 2, with one end of the first annular channel 6 being the air inlet end. When the sliding air-fuel blending module 2 slides toward the fuel inlet end, a second annular channel 7 is formed between the outer wall surface of the fuel rod 1 and the inner wall surface of the fixed air-fuel blending module 3, and the fuel through hole 12 is connected to the second annular channel 7.

[0030] One end of the fuel rod 1 is specifically fixedly mounted on the fuel distribution chamber cover plate 4, and the fixed air-fuel mixing module 3 is specifically fixedly mounted on the burner end cover 5. The fixed connection between the fuel rod 1 and the fuel distribution chamber cover plate 4, and between the fixed air-fuel mixing module 3 and the burner end cover 5, can be a threaded connection for easy disassembly. The fuel distribution chamber cover plate 4, the burner end cover 5, and the burner shell described in this invention are all conventional structures of existing burners, and will not be described in detail here.

[0031] The actuator 9 can be installed on the burner housing. All sliding air-fuel blending modules 2 on the burner can be moved simultaneously by a single actuator 9, or, depending on the actual burner structure layout, multiple actuators 9 can be used to move sliding air-fuel blending modules 2 in different areas. The transmission and connection structures between the actuator 9 and the sliding air-fuel blending modules 2 are existing technologies and will not be described further here.

[0032] One end of the fixed air-fuel blending module 3 is close to the fuel inlet, and the other end of the fixed air-fuel blending module 3 is far away from the fuel inlet.

[0033] According to the structural arrangement direction shown in the accompanying drawings of this invention, one end and the other end of each component structure in this invention are defined, that is, the right end of each structure is one end and the left end is the other end.

[0034] Fuel enters the fuel channel 11 within the fuel rod 1 from the fuel inlet end and is finally discharged through a number of fuel through holes 12. Preferably, there are six fuel through holes 12, and more preferably, these fuel through holes 12 are evenly arranged circumferentially along the fuel rod 1.

[0035] Air enters the first annular channel 6 within the sliding air-fuel mixing module 2 from the air inlet. The first annular channel 6 and the second annular channel 7 serve as air-fuel mixing channels for different nozzle modes.

[0036] The high combustion stability micro-mixing nozzle of the present invention has two nozzle modes: In the first nozzle mode, the other end of the sliding air-fuel mixing module 2, the other end of the fuel rod 1, and the other end of the fixed air-fuel mixing module 3 are all located in the same plane. Air enters the first annular channel 6 from the air inlet end, and fuel enters the fuel channel 11 from the fuel inlet end, and then flows out into the first annular channel 6 through the fuel through hole 12, where it mixes with the air entering the first annular channel 6, forming an air-fuel mixture at the outlet of the other end of the first annular channel 6.

[0037] In the second nozzle mode, the actuator 9 drives the sliding air-fuel mixing module 2 to move along the axis toward the fuel inlet end, so that the other end of the sliding air-fuel mixing module 2 is located in the second annular channel 7, exposing the fuel through hole 12 to the inside of the fixed air-fuel mixing module 3. Air enters the first annular channel 6 from the air inlet end, and fuel enters the fuel channel 11 from the fuel inlet end, and then flows out through the fuel through hole 12 into the second annular channel 7, where it mixes with the air entering the second annular channel 7, forming an air-fuel mixture at the outlet of the other end of the second annular channel 7.

[0038] Compared with existing technologies, the high combustion stability micro-mixing nozzle of the present invention achieves efficient and stable burner operation through a simpler structural form when faced with changes in fuel composition and operating conditions.

[0039] For example, when burning hydrogen, the flame spreads quickly, so the first nozzle mode is used, and the airflow is fast to prevent backfire.

[0040] When using natural gas, the flame spreads slowly, so a second nozzle mode is used, which slows down the airflow to prevent it from being blown out.

[0041] When the burner uses the same fuel, under ignition conditions, the airflow is low, so the first nozzle mode is used to increase the air velocity and prevent backfire. Under design load, the airflow is high, so the second nozzle mode is used to reduce the air velocity, minimize pressure loss, control the flame anchoring position for stable combustion, and prevent blow-out. In addition, adjusting the air velocity enhances air-fuel mixing, achieving low pollutant emissions.

[0042] When the burner uses the same fuel, and the air flow rate remains constant, the first nozzle mode is used at low air temperatures to increase the air velocity, enhance mixing, and achieve low pollutant emissions. At high air temperatures, the second nozzle mode is used to maintain a constant air velocity, ensuring that the air mixing uniformity remains consistent and maintaining low pollutant emissions.

[0043] This invention can be applied in fields such as gas turbines, aircraft engines, aerospace engines, and industrial kilns.

[0044] In this invention, the through holes inside the fixed air-fuel blending module 3 and the sliding air-fuel blending module 2 can be circular, rectangular, or other shaped through holes. The fuel rod 1 can be round, square, or other types of rods. Preferably, the shape of the outer wall of the fuel rod 1 is conformal to the shape of the through holes inside the sliding air-fuel blending module 2.

[0045] The other end of the fuel rod 1 and the other end of the fixed air-fuel blending module 3 are located in the same plane. As shown in the attached drawings, the other end of the fuel rod 1 and the other end of the fixed air-fuel blending module 3 are located in the same vertical plane. This design creates an annular surface between the outer wall of the other end of the fuel rod 1 and the inner wall of the other end of the fixed air-fuel blending module 3, forming a reflux vortex downstream of the fuel rod 1 with the fuel rod 1 as the center, thus further stabilizing combustion.

[0046] The sliding air-fuel blending module 2 includes a first cylindrical body 21 and a retaining ring 22 fixedly fitted at one end of the first cylindrical body 21. The other end of the first cylindrical body 21 is slidably fitted between the fixed air-fuel blending module 3 and the fuel rod 1. This design, by providing the retaining ring 22, facilitates the connection between the sliding air-fuel blending module 2 and the actuator 9, and also facilitates limiting the extreme positions of the sliding air-fuel blending module 2 when it moves towards the other end of the fuel pipe. The corner structure between the other end of the first cylindrical body 21 and its inner wall can be designed as a right angle, a chamfer, or a rounded corner, preferably a chamfer, thus forming a gradually expanding outlet at the other end of the sliding air-fuel blending module 2. The first cylindrical body 21 can be a cylindrical, square, or other cylindrical structure with any cross-sectional shape.

[0047] The other end of the sliding air-fuel mixing module 2 is a gradually expanding outlet. This outlet can be chamfered or rounded. With this design, air enters the second annular channel from the first annular channel, reducing vortices and pressure loss at the outlet of the first annular channel.

[0048] The fixed air-fuel blending module 3 is a second cylinder, and the cross-sectional shape of the through hole inside the second cylinder is set to conform to the cross-sectional shape of the outer wall of the first cylinder 21. With this design, the corner structure between the other end of the second cylinder and its inner wall can be designed as a right angle, a chamfer, or a rounded corner, preferably a right angle. The second cylinder can be a cylindrical, square, or other cylindrical structure with any cross-sectional shape.

[0049] The corner structure between the other end of the second cylinder and its inner wall is a right angle.

[0050] One end of the fuel rod 1 is coaxial and integrally machined with a ring platform 8. This design increases the contact area between the fuel rod 1 and the fuel distribution chamber cover plate 4 by setting the ring platform 8, thereby facilitating the installation and removal of the fuel rod 1.

[0051] The closed end of the fuel passage 11 is hemispherical.

[0052] The actuator 9 is fixedly mounted on the burner housing.

[0053] The actuator 9 is a stepper motor.

[0054] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A micro-mixing nozzle with high combustion stability, characterized in that: The device includes a fuel rod (1), a sliding air-fuel mixing module (2), and a fixed air-fuel mixing module (3) arranged coaxially from the inside out. One end of the fuel rod (1) is fixed to the fuel distribution chamber cover plate (4) of the burner, and the fixed air-fuel mixing module (3) is fixed to the end cover (5) of the burner. The sliding air-fuel mixing module (2) is moved along the central axis by the actuator (9). The fuel rod (1) is provided with a fuel channel (11) and several fuel through holes (12). The fuel channel (11) is arranged along the axial direction of the fuel rod (1) with one end being the fuel inlet and the other end being the closed end. Several fuel through holes (12) are distributed circumferentially along the fuel rod (1) and communicate with the fuel channel (11). The other end of the fuel channel (11) and several fuel through holes (12) are located inside the fixed air-fuel mixing module (3). A first annular channel (6) is formed between the outer wall of the fuel rod (1) and the inner wall of the sliding air-fuel mixing module (2), with one end of the first annular channel (6) being the air inlet end. When the sliding air-fuel blending module (2) slides toward the fuel inlet end, a second annular channel (7) is formed between the outer wall of the fuel rod (1) and the inner wall of the fixed air-fuel blending module (3), and the fuel through hole (12) is connected to the second annular channel (7).

2. The high combustion stability micro-mixing nozzle according to claim 1, characterized in that: One end of the fixed air-fuel blending module (3) is close to the fuel inlet, and the other end of the fixed air-fuel blending module (3) is far from the fuel inlet. The other end of the fuel rod (1) and the other end of the fixed air-fuel blending module (3) are located in the same plane.

3. The high combustion stability micro-mixing nozzle according to claim 1, characterized in that: The sliding air-fuel blending module (2) includes a first cylinder (21) and a retaining ring (22) fixedly fitted at one end of the first cylinder (21). The other end of the first cylinder (21) is slidably fitted between the fixed air-fuel blending module (3) and the fuel rod (1).

4. The high combustion stability micro-mixing nozzle according to claim 3, characterized in that: The other end of the first cylinder (21) is a gradually expanding outlet.

5. A high combustion stability micro-mixing nozzle according to claim 3, characterized in that: The fixed air-fuel mixing module (3) is a second cylinder, and the cross-sectional shape of the through hole inside the second cylinder is set to follow the cross-sectional shape of the outer wall of the first cylinder (21).

6. A high combustion stability micro-mixing nozzle according to claim 5, characterized in that: The corner structure between the other end of the second cylinder and its inner wall is a right angle.

7. A high combustion stability micro-mixing nozzle according to claim 1, characterized in that: One end of the fuel rod (1) is coaxial and integrally machined with a ring platform (8).

8. A high combustion stability micro-mixing nozzle according to claim 1, characterized in that: The closed end of the fuel passage (11) is hemispherical.

9. A high combustion stability micro-mixing nozzle according to claim 1, characterized in that: The actuator (9) is fixed to the burner housing.

10. A high combustion stability micro-mixing nozzle according to claim 1, characterized in that: The actuator (9) is a stepper motor.

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