Micro-scale fuel-air jet mixing structure

Abstract

The application belongs to the field of combustion chamber design, and particularly relates to a micro-size fuel-air jet mixing structure, which comprises an air pipe, a fuel nozzle and a combustion chamber flame tube; the fuel nozzle is coaxially arranged in the air pipe, the air pipe is connected with the combustion chamber flame tube, the outlet section of the convergent nozzle is in a convergent form, the end of the outlet section is provided with a coaxial injection hole, and the side wall is provided with a vertical injection hole, and the outlet of the vertical injection hole faces the combustion chamber flame tube. Through the coaxial nesting structure of the air pipe and the fuel nozzle, the end coaxial injection hole and the vertical injection hole distributed on the side wall are matched, the forced close-range shear mixing of the fuel jet and the air main stream is realized, the uniform premixed gas is quickly formed in the micro-size channel, the foundation of low-NOx combustion is laid, and the fuel is prevented from directly contacting the pipe wall. X The annular air channel wraps the fuel jet in the form of a high-speed jet, which not only improves the premixed gas flow rate and inhibits backfire, but also avoids the direct contact of the fuel with the pipe wall.

Description

Technical Field

[0001] This application belongs to the field of combustion chamber design, and specifically relates to a micro-sized fuel-air jet mixing structure. Background Technology

[0002] Gas turbines urgently need to reduce carbon emissions during their application. One of the most effective measures currently is to replace fossil fuels such as natural gas, which are commonly used in gas turbines, with low-carbon or zero-carbon fuels. In IGCC power plants, gas turbines can significantly reduce carbon emissions by burning syngas. Compared to natural gas, syngas contains a higher volume fraction of H2, which makes it more prone to backfire during combustion in the combustion chamber, resulting in higher NOx emissions.

[0003] Currently, there are two common combustion methods used in combustion chambers that burn syngas: one is diffusion combustion, which uses N2, water vapor, or CO2 for dilution to reduce emissions; the other is large-scale premixed combustion.

[0004] The main drawbacks of existing technical solutions are:

[0005] 1. High risk of backfire: Existing large-size premixed combustion chambers use cyclones to generate a backflow zone to stabilize the flame, which creates a large low-speed zone. Therefore, when using syngas, backfire is likely to occur.

[0006] 2. High NOx emissions: Existing large-size premixed combustion chambers use cyclones to create a recirculation zone to stabilize the flame. The high-temperature flame area is large, so when using syngas, NOx emissions are high.

[0007] 3. Poor fuel flexibility: Existing large-size premixed combustors are prone to backfire when using syngas. This limits the H2 content in the syngas. In practical applications, the restrictions on fuel composition are even more stringent, limiting the application of gas turbines.

[0008] Therefore, how to design a more effective combustion chamber nozzle structure is a problem that needs to be solved. Summary of the Invention

[0009] To address the aforementioned issues, this application provides a micro-sized fuel-air jet mixing structure to solve the problems of high backfire risk, high NOx emissions, and poor fuel flexibility in existing combustion chamber nozzle structures.

[0010] The technical solution of this application is: a micro-sized fuel-air jet mixing structure, including an air pipe, a fuel nozzle, and a combustion chamber flame tube;

[0011] The fuel nozzle is coaxially inserted into the air pipe, which is connected to the combustion chamber flame tube. The fuel nozzle has a cylindrical structure, with a coaxial nozzle at the end of the outlet section and a vertical nozzle on the side wall. The outlet of the vertical nozzle faces the combustion chamber flame tube.

[0012] Preferably, there are multiple vertical nozzles arranged in a ring at intervals around the axis of the fuel nozzle.

[0013] Preferably, there is a gap between the fuel nozzle and the air pipe to form an annular air passage.

[0014] Preferably, the inner diameter of the air pipe is between 8 and 15 mm; the inner diameter of the fuel nozzle (2) is less than or equal to half the inner diameter of the air pipe.

[0015] Preferably, an annular micro-slit heat dissipation groove is formed on the inner wall of the air pipe, and the groove depth of the annular micro-slit heat dissipation groove is 0.2–0.8 mm.

[0016] Preferably, the fuel nozzle has a necking damping ring inside, and the necking damping ring protrudes in an arc shape towards the inside of the fuel nozzle.

[0017] The micro-sized fuel-air jet mixing structure of this application has the following advantages:

[0018] Through the coaxial nested structure of the air pipe and fuel nozzle, combined with the coaxial nozzle at the end and the vertically distributed nozzles on the sidewall, close-range forced shear mixing of the fuel jet and the mainstream air is achieved. This rapidly forms a uniform premixed gas within a micro-channel, laying the foundation for low NOx emissions. x The basis of combustion; the annular air passage allows air to envelop the fuel jet in a high-speed jet form, which not only increases the premixed gas flow rate and suppresses backfire, but also avoids direct contact between the fuel and the pipe wall. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of this application.

[0020] 1. Air pipe; 2. Fuel nozzle; 3. Coaxial nozzle; 4. Vertical nozzle; 5. Fuel; 6. Air; 7. Combustion chamber flame tube; 8. Annular micro-slit heat dissipation groove; 9. Necked damping ring. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only some, not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0022] The first aspect of this application provides a micro-sized fuel-air jet mixing structure, such as Figure 1 As shown, it includes an air pipe 1, a fuel nozzle 2, and a combustion chamber flame tube 7.

[0023] The fuel nozzle 2 is coaxially inserted into the air pipe 1, which is connected to the combustion chamber flame tube 7. The fuel nozzle 2 has a cylindrical structure, with a coaxial nozzle 3 at the end of the outlet section and a vertical nozzle 4 on the side wall. The outlet of the vertical nozzle 4 faces the combustion chamber flame tube 7.

[0024] By coaxially nesting the air pipe 1 and fuel nozzle 2, and combining the coaxial nozzle tip orifice 3 with the vertical sidewall orifice 4, close-range, forced shear mixing of the fuel jet 5 and the mainstream air 6 is achieved. The direct jet from the coaxial nozzle 3 can penetrate the center of the air flow 6, ensuring the axial depth of fuel 5 distribution; the radial jet from the vertical sidewall orifice 4 creates lateral disturbance to the air flow 6, enhancing entrainment and mixing, and rapidly forming a uniform premixed gas within the micro-channel, structurally laying the foundation for low NO₂ levels. x The combustion process is based on the principle of eliminating traditional cyclones, thus avoiding the formation of low-speed backflow zones and reducing the risk of backfire.

[0025] Preferably, there are multiple vertical nozzles 4, arranged in a ring-shaped interval around the axis of the fuel nozzle 2. This ensures that the radial jet is evenly distributed circumferentially, forming a symmetrical annular jet field. This allows for 360° radial disturbance and sweeping of the main airflow 6 without dead angles, effectively avoiding flow deviation, local fuel-rich areas 5, and uneven temperature field caused by unilateral jets.

[0026] Preferably, there is a gap between the fuel nozzle 2 and the air pipe 1, forming an annular air channel. The annular air channel formed by the gap between the fuel nozzle 2 and the air pipe 1 allows the air 6 to wrap around the fuel 5 jet in an annular high-speed jet form.

[0027] Preferably, the inner diameter of the air pipe 1 is between 8 and 15 mm; the inner diameter of the fuel nozzle 2 (2) is less than or equal to half the inner diameter of the air pipe 1. This significantly improves the flow rate and wall heat transfer intensity within the channel, shortens the mixing distance between fuel 5 and air 6, and achieves rapid and uniform mixing.

[0028] Preferably, 1-3 annular micro-slit heat dissipation grooves 8 are formed on the inner wall of the air pipe 1, and the groove depth of the annular micro-slit heat dissipation grooves 8 is 0.2-0.8 mm. This disrupts the continuous low-velocity boundary layer near the pipe wall, and the micro-vortices formed in the grooves can entrain high-temperature gas, while increasing the heat exchange area of ​​the wall surface.

[0029] Preferably, the fuel nozzle 2 is provided with a necking damping ring 9 inside, and the necking damping ring 9 protrudes in an arc shape towards the inside of the fuel nozzle 2. By providing a necking damping ring 9 that protrudes in an arc shape towards the inside of the fuel nozzle 2, a local throttling structure is formed, which can improve the injection velocity of the fuel 5 and at the same time suppress the backflow of the flame along the fuel 5 channel.

[0030] In summary, this application has the following technical effects:

[0031] Through the coaxial nested structure of the air pipe and fuel nozzle, combined with the coaxial nozzle at the end and the vertically distributed nozzles on the sidewall, close-range forced shear mixing of the fuel jet and the mainstream air is achieved. This rapidly forms a uniform premixed gas within a micro-channel, laying the foundation for low NOx emissions. x The basis of combustion; the annular air passage allows air to envelop the fuel jet in a high-speed jet form, which not only increases the premixed gas flow rate and suppresses backfire, but also avoids direct contact between the fuel and the pipe wall.

[0032] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A micro-sized fuel-air jet mixing structure, characterized in that, It includes an air pipe (1), a fuel nozzle (2), and a combustion chamber flame tube (7); The fuel nozzle (2) is coaxially inserted into the air pipe (1). The air pipe (1) is connected to the combustion chamber flame tube (7). The fuel nozzle (2) has a cylindrical structure. The end of the outlet section is provided with a coaxial nozzle (3) and a vertical nozzle (4) is provided on the side wall. The outlet of the vertical nozzle (4) faces the combustion chamber flame tube (7).

2. The micro-sized fuel nozzle mixing structure as described in claim 1, characterized in that, The vertical nozzles (4) are multiple and are arranged in a ring-shaped interval around the axis of the fuel nozzle (2).

3. The micro-sized fuel nozzle mixing structure as described in claim 1, characterized in that, There is a gap between the fuel nozzle (2) and the air pipe (1) to form an annular air passage.

4. The micro-sized fuel-air jet mixing structure as described in claim 1, characterized in that, The inner diameter of the air pipe (1) is between 8 and 15 mm; the inner diameter of the fuel nozzle (2) is less than or equal to half the inner diameter of the air pipe (1).

5. The micro-sized fuel (5) air (6) jet mixing structure as described in claim 1, characterized in that, The air pipe (1) has an annular micro-slit heat dissipation groove (8) on its inner wall, and the groove depth of the annular micro-slit heat dissipation groove (8) is 0.2–0.8 mm.

6. The micro-sized fuel (5) air (6) jet mixing structure as described in claim 1, characterized in that, The fuel nozzle (2) is provided with a necked damping ring (9) inside, and the necked damping ring (9) protrudes in an arc shape towards the inside of the fuel nozzle (2).

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