Micromix single nozzle, combustor and gas turbine

Abstract

This invention discloses a micro-mixing single-nozzle burner, a burner, and a gas turbine, belonging to the field of burner design technology. The micro-mixing single-nozzle burner includes a fuel pipe and an air pipe. One end of the fuel pipe is a fuel inlet, and the other end is closed, with multiple fuel injection holes on its sidewall. An air hole is provided on the sidewall of one end of the air pipe, and the other end is an ignition point. The fuel pipe is coaxially sleeved within the air pipe, with the inlet end of the fuel pipe sealed to the end of the air pipe, forming an annulus for gas mixing between the fuel pipe and the air pipe. The air hole communicates with the annulus. Oxidizing gas flows into the air pipe through the air hole. The fuel injection direction is perpendicular to the airflow direction, and mixing occurs in the annulus region in the form of cross-jet flow. This micro-mixing single-nozzle burner has advantages such as high-efficiency mixing, compact structure, high flexibility, ease of manufacturing and maintenance, and environmental protection and energy saving.

Description

Technical Field

[0001] This invention relates to the field of burner design technology, specifically to a micro-mixing single nozzle, burner, and gas turbine. Background Technology

[0002] The micro-mixing single-nozzle burner is a core component of the burner, responsible for mixing fuel and gas. It utilizes a micro-tube instead of the traditional single, thick tube for combustion, resulting in a significantly reduced space and generally higher degree of fuel-air mixing. Existing micro-mixing single-nozzle burners typically have separate fuel and air inlets on a single tube, with the fuel-air flow premixed within the tube, leading to a longer premixing distance. Backfire is a phenomenon where the flame flows backward into the fuel supply system during combustion. In micro-mixing single-nozzle burners, due to the small tube diameter and the proximity of the fuel-air mixing area to the nozzle outlet, backfire can rapidly spread the flame throughout the micro-tube, potentially damaging it. Furthermore, the material properties of the micro-tube may be affected under high pressure and high temperature conditions, such as decreased strength and increased creep, potentially damaging the nozzle or other critical components and causing serious safety accidents. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention provides a micro-mixing single nozzle, a burner, and a gas turbine. The fuel gas of the micro-mixing single nozzle is injected from a fuel injection hole opened downstream, and air flows into the air pipe through an air hole. The fuel injection direction is perpendicular to the air flow direction, and the two are mixed in the form of cross-jet, which shortens the premixing distance of fuel gas and air, improves the mixing uniformity, solves the backfire problem of the micro-mixing single nozzle burner, and improves the safety of the entire burner.

[0004] This invention is achieved through the following technical solution:

[0005] In a first aspect, this application provides a micro-mixing single-nozzle burner, including a fuel pipe and an air pipe;

[0006] One end of the fuel pipe is a fuel inlet, and the other end is closed. Multiple fuel injection holes are provided on the side wall.

[0007] An air hole is provided on the side wall of one end of the air pipe, and the other end is the ignition end;

[0008] The fuel tube is coaxially sleeved in the air tube, the inlet end of the fuel tube is sealed to the end of the air tube, and an annulus for mixing gas is formed between the fuel tube and the air tube, and the air hole communicates with the annulus.

[0009] Oxidizing gases flow into the air pipe through air holes, and the fuel injection direction is perpendicular to the air flow direction, and they are mixed in the annular region in the form of cross jets.

[0010] Preferably, multiple fuel injection holes are spaced apart along the axial direction of the fuel pipe, and the multiple fuel injection holes are arranged in an equally spaced manner, and the fuel injection direction is perpendicular to the axial direction of the fuel pipe.

[0011] Preferably, the plurality of fuel injection holes are divided into multiple groups, each group including several fuel injection holes, the several fuel injection holes are circumferentially distributed at the same cross section, and the spacing between the multiple groups of fuel injection holes decreases sequentially from the open end to the closed end.

[0012] Preferably, the air pipe includes a premixing section and a mixing section connected in sequence, and the fuel pipe is located in the premixing section of the air pipe.

[0013] Preferably, the air hole is a circular, polygonal, or strip-shaped hole.

[0014] Preferably, there are multiple air holes, which are evenly distributed around the circumference.

[0015] Preferably, the air hole has a length of 10 mm, a width of 2 mm, and an air tube diameter of 8 mm.

[0016] Preferably, the number of fuel injection holes is 12, the hole spacing is 5 mm, and the diameter of the fuel injection holes is 0.8 mm.

[0017] Secondly, this application provides a burner including the aforementioned micro-mixing single nozzle.

[0018] Thirdly, this application provides a gas turbine including the aforementioned burner.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] This invention provides a micro-mixing single nozzle, which consists of a fuel pipe and an air pipe coaxially sleeved together. The top of the fuel pipe is closed, and fuel gas is injected from a small hole at the downstream end. Air flows into the air pipe from the bottom air inlet. The fuel injection direction is perpendicular to the air flow direction, and the two are mixed in the form of cross-jet. This mixing method significantly shortens the premixing distance of fuel gas and air, improves the uniformity of mixing, and thus ensures high efficiency and stability of combustion. This micro-mixing single nozzle burner has the advantages of high-efficiency mixing, compact structure, high flexibility, optimized air hole design, easy manufacturing and maintenance, and environmental protection and energy saving. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the micro-mixing single nozzle of the present invention;

[0023] Figure 2 This is an end view of the micro-mixing single nozzle of the present invention;

[0024] Figure 3 This is a schematic diagram of the fuel pipe structure of the present invention;

[0025] Figure 4 This is a schematic diagram of the burner structure of the present invention.

[0026] In the diagram, 1 is the air pipe; 2 is the fuel pipe; 3 is the fuel injection port; 4 is the air hole; and 5 is the annulus. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the 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.

[0029] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0030] In the description of the embodiments of this application, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing this application 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, and therefore should not be construed as a limitation on this application. In addition, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0032] In the description of the embodiments of this application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" 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 mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0033] The working principle of a premixed fuel nozzle is to premix fuel and air inside the nozzle to form a fuel-air mixture in a specific ratio before it enters the combustion chamber for combustion. This premixing method ensures that the fuel is fully mixed with air before entering the combustion chamber, thereby improving the combustion efficiency and stability of the fuel. Specifically, a premixed fuel nozzle typically has a fuel inlet, an air inlet, a mixing chamber, and an nozzle. Fuel and air enter the mixing chamber through these inlets, are fully mixed within the mixing chamber, and are then ejected from the nozzle into the combustion chamber for combustion.

[0034] Because the fuel and air are fully mixed at the nozzle, they can burn rapidly and completely upon entering the combustion chamber, improving combustion efficiency. This helps reduce fuel waste and emissions, which is beneficial for environmental protection. Premixed fuel nozzles, by optimizing the mixing ratio and effect of fuel and air, can reduce pollutant emissions during combustion. This helps reduce emissions of harmful substances such as nitrogen oxides and carbon monoxide, meeting modern environmental protection requirements. Since the fuel and air are fully mixed, the flame is more stable during combustion. This application addresses the problems of long mixing distances and susceptibility to backfire in existing premixed fuel nozzles by designing a micro-mixing single nozzle.

[0035] See Figure 1-3 A micro-mixing single nozzle includes a fuel pipe 2 and an air pipe 1;

[0036] One end of the fuel pipe 2 is a fuel inlet, and the other end is closed. Multiple fuel injection holes 3 are provided on the side wall.

[0037] An air hole 4 is provided on the side wall of one end of the air pipe, and the other end is the ignition end;

[0038] The fuel tube is coaxially sleeved in the air tube, and the inlet end of the fuel tube is sealed to the end of the air tube. An annulus 5 for mixing gas is formed between the fuel tubes, and the air hole is connected to the annulus.

[0039] This micro-mixing single nozzle consists of an inner and outer fuel pipe and an air pipe, forming an annular space between the fuel pipe and the air pipe for the user to mix fuel and air. The fuel gas is injected from the fuel injection hole opened downstream, and the air flows into the air pipe through the air hole. The fuel injection direction is perpendicular to the air flow direction, and the two are mixed in the form of cross jets, which shortens the premixing distance of fuel gas and air and improves the mixing uniformity.

[0040] In some embodiments, the fuel pipe has an open end and a closed end structure. The open end is the fuel inlet. The fuel pipe is sleeved in the air pipe, and the ends of the fuel pipe and the air pipe form a sealed connection. The closed end of the fuel pipe is located in the air pipe, and the open end of the fuel pipe extends to the outside of the air pipe for connecting to the fuel delivery pipeline. The fuel gas is injected into the fuel pipe by pressurization and flows out through the fuel injection hole.

[0041] In some embodiments, a plurality of fuel injection holes are spaced apart along the axial direction of the fuel pipe, the plurality of fuel injection holes are arranged in an equally spaced manner, and the fuel injection direction is perpendicular to the axial direction of the fuel pipe, that is, the axial direction of the fuel injection holes is arranged radially along the fuel pipe.

[0042] In another embodiment, the multiple fuel injection holes are divided into multiple groups, each group including several fuel injection holes, the several fuel injection holes are circumferentially distributed at the same cross section, and the number of several fuel injection holes is 2-4; the multiple groups of fuel injection holes are arranged at equal intervals, or the interval decreases sequentially from the open end to the closed end.

[0043] In some embodiments, the air pipe is a hollow pipe open at both ends, with one end sealed to the outside of the fuel pipe and the other end serving as the outlet for the mixed fuel. The air pipe is divided into two sections: a premixing section and a mixing section. The fuel pipe is located in the premixing section of the air pipe, and the premixed fuel is ignited at the outlet after passing through the mixing section. The inner diameter of the air pipe is larger than the outer diameter of the fuel pipe. When the two are coaxially fitted, an annular space is formed between the air pipe and the fuel pipe, serving as the premixing section for fuel and air. The end of the air pipe is connected to the fuel pipe through a sealing structure.

[0044] The air hole is located on the outer wall of the air pipe and near the end. The air hole is connected to the premixing section and is located on the side near the end of the premixing section. Air enters the premixing section radially and then flows axially, while fuel gas flows axially into the fuel pipe and then enters the premixing section radially through the fuel injection hole. In the premixing section, the flow directions of the fuel gas flow and the air flow are perpendicular to each other, forming cross-mixing.

[0045] In some embodiments, the air hole is circular, polygonal, approximately circular, or strip-shaped, preferably strip-shaped, with the longitudinal direction of the strip-shaped hole arranged along the axial direction of the air pipe.

[0046] There are multiple air holes, which are evenly distributed around the circumference. The number of air holes is 2-4, with a preference for 4, which are arranged symmetrically in pairs. The holes are preferably strip-shaped.

[0047] Since the parameters of the air orifice and fuel injection orifice have a critical impact on the uniformity of fuel and air mixing and nozzle pressure drop, optimal design of the air orifice and fuel injection orifice can prevent backfire in micro-mixing single-nozzle burners. To address this issue, this application uses a three-dimensional numerical simulation method to optimize the micro-mixing single nozzle, thereby determining the optimal parameters of the air orifice and fuel injection orifice, so that the performance of the micro-mixing single nozzle can be optimized.

[0048] The air hole is 10 mm long, 2 mm wide, and has an air tube diameter of 8 mm.

[0049] Simulation results show that when the length of the air inlet is 10 mm, the width of the air inlet is 2 mm, and the diameter of the air pipe is 8 mm, the uniformity index is the highest, the fuel-air mixing effect is the best, and the total pressure loss coefficient meets the requirements.

[0050] The number of fuel injection holes is 12, the hole spacing is 5 mm, and the diameter of the fuel injection holes is 0.8 mm.

[0051] Simulation calculations were performed on different numbers of fuel injection holes. As the number of holes increased, the total pressure loss coefficient decreased non-linearly. The decrease slowed significantly after the number of holes exceeded 8. With 4 holes, the corresponding total pressure loss coefficient was 6.217%. When the number of holes increased to 8, the total pressure loss coefficient decreased to 4.456%, close to the design standard. Increasing the number of holes to 12 reduced the total pressure loss coefficient to 3.996%. Further increasing the number of holes to 24 resulted in a decrease to 3.663%, a negligible change. Since the number of fuel injection holes has little impact on mixing uniformity, based on the total pressure loss coefficient, 12 fuel injection holes are optimal for the micro-mixer burner.

[0052] Simulations were conducted on fuel injection orifices of different diameters. The uniformity index showed a consistent trend with axial distance for different orifice diameters. At a fixed axial height, the uniformity index was highest at an orifice diameter of 0.8 mm, and exceeded 0.95 at an axial height of 80 mm, indicating optimal fuel-air mixing at this orifice diameter. The total pressure loss coefficient (TPS) decreased non-linearly with increasing orifice diameter, and the rate of decrease significantly decreased after the orifice diameter exceeded 0.6 mm, with the TPS decreasing from 4.6% at 0.6 mm to approximately 3.8% at 1.2 mm. Based on these results, and considering both the uniformity index and TPS, a fuel injection orifice diameter of 0.8 mm is optimal for the micro-mixer burner.

[0053] The uniformity index increases non-linearly with increasing axial height for different hole spacings. Compared with the results for hole spacings of 2 mm, 7 mm and 10 mm, the uniformity index is the largest at any axial height when the hole spacing is 5 mm, and the uniformity index is greater than 0.95 when the axial height is 80 mm.

[0054] As the fuel pipe diameter increases from 1.5 mm to 3.0 mm, the total pressure loss coefficient decreases non-linearly. When the fuel pipe diameter is greater than 2.0 mm, the rate of decrease decreases significantly, and the total pressure loss coefficient is less than 5%. The preferred fuel pipe diameter is 2.0 mm.

[0055] With the air orifice and fuel injection orifice in their optimal configuration, fuel can be injected vertically into the surrounding air, resulting in rapid and uniform mixing. By studying the effects of air inlet height, width, and air pipe inner diameter on the airflow mixing process and nozzle pressure loss, and based on the data variation patterns, a high-performance micro-mixing single-nozzle configuration was selected. In this configuration, if backfire occurs, the flame propagates back into the nozzle and is extinguished near the injection orifice downstream of the fuel pipe, preventing it from entering the fuel pipe and causing greater damage.

[0056] This micro-mixing single-nozzle burner consists of a fuel pipe and an air pipe coaxially fitted together. The top of the fuel pipe is closed, and fuel gas is injected from a small hole at the downstream end. Air flows into the air pipe through the bottom air inlet. The fuel injection direction is perpendicular to the air flow direction, and the two mix in a cross-jet manner. This mixing method significantly shortens the premixing distance between fuel gas and air, improves the uniformity of mixing, and thus ensures high efficiency and stability of combustion. This micro-mixing single-nozzle burner has the advantages of high-efficiency mixing, compact structure, high flexibility, optimized air hole design, ease of manufacturing and maintenance, and environmental protection and energy saving.

[0057] Correspondingly, this application also provides a burner including the above-mentioned micro-mixing single nozzle, wherein multiple micro-mixing single nozzles are arranged in an array in the burner.

[0058] See Figure 4 This is a schematic diagram of a burner. Fuel (such as natural gas, liquefied petroleum gas, etc.) and air are mixed in a micro-mixing single nozzle to form a combustible mixture, promoting uniform mixing of fuel and air. The mixed combustible gas is ejected through the nozzle and ignited in the combustion chamber. The ignition system typically consists of electrodes, spark plugs, or flame sensors, used to generate an electric spark in the mixture, thereby igniting it. The high-temperature, high-pressure environment in the combustion chamber allows for rapid and stable combustion of the mixture. The ignited mixture burns within the combustion chamber, releasing a large amount of heat energy. The combustion process is stable and controllable; the flame shape and combustion intensity can be adjusted by modifying the fuel-air mixing ratio and the parameters of the ignition device. The high-temperature, high-pressure gas produced by combustion expands through a turbine, converting heat energy into mechanical energy. Simultaneously, some of the heat energy can be transferred to other media (such as water, air, etc.) through heat exchangers or other equipment for heating or steam generation processes.

[0059] This application also discloses a gas turbine including the aforementioned burner.

[0060] In a gas turbine, the combustor plays a crucial role. It is not only a key component for mixing and burning fuel and air, but also the core link in converting the chemical energy of the fuel into the thermal energy of the high-temperature, high-pressure gas. Specifically, the combustor receives high-pressure, high-temperature air compressed by the compressor, mixes it with injected fuel, and ignites it. The resulting high-temperature, high-pressure gas drives the turbine to rotate, which in turn drives the compressor to rotate at high speed, thus partially converting the chemical energy of the fuel into mechanical work. Furthermore, the design and performance of the combustor directly affect the combustion efficiency, emission characteristics, and operational stability of the gas turbine. Therefore, in a gas turbine, the combustor is a key component ensuring the efficient and low-emission operation of the entire unit.

[0061] The micro-mixing single nozzle provided in this application has the following significant advantages:

[0062] 1. High-efficiency mixing: Through the ingenious design of fuel injection holes and air holes, fuel gas and air are mixed in the form of cross-jet streams. This mixing method significantly shortens the premixing distance between fuel gas and air, improves the uniformity of mixing, and thus ensures high efficiency and stability of combustion.

[0063] 2. Compact Structure: The burner employs an inner and outer casing structure for the fuel and air pipes, resulting in a compact overall structure that occupies less space. This design not only facilitates installation and maintenance but also helps improve the overall efficiency and reliability of the equipment.

[0064] 3. High flexibility: The design of the fuel perforations offers various possibilities, such as equal spacing or multiple sets of circumferential distribution, which can be adjusted according to actual needs. This flexibility allows the burner to adapt to different fuel types and combustion requirements, improving its applicability and performance.

[0065] 4. Optimize air vent design: By optimizing the shape, number, and location of the air vents, the mixing effect of fuel and air can be further improved, and backfire can be avoided. This design not only improves the safety of the burner but also helps to extend its service life.

[0066] 5. Easy to manufacture and maintain: The burner has a simple and clear structure, making it easy to manufacture and process. Furthermore, its compact structure and rational connection method between components make maintenance and repair more convenient.

[0067] In summary, this micro-mixer single-nozzle burner boasts advantages such as high-efficiency mixing, compact structure, high flexibility, optimized air orifice design, ease of manufacturing and maintenance, and environmental friendliness and energy saving. These advantages make this burner a promising candidate for applications in energy utilization, environmental protection, and sustainable development.

[0068] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A micro-mixing single-nozzle burner, characterized in that, Including fuel lines and air lines; One end of the fuel pipe is a fuel inlet, and the other end is closed. Multiple fuel injection holes are provided on the side wall. An air hole is provided on the side wall of one end of the air pipe, and the other end is the ignition end; The fuel tube is coaxially sleeved in the air tube, the inlet end of the fuel tube is sealed to the end of the air tube, and an annulus for mixing gas is formed between the fuel tube and the air tube, and the air hole communicates with the annulus. Oxidizing gases flow into the air pipe through air holes, and the fuel injection direction is perpendicular to the air flow direction, and they are mixed in the annular region in the form of cross jets; Multiple fuel injection holes are spaced apart along the axial direction of the fuel pipe, and the multiple fuel injection holes are arranged in an equally spaced manner, and the fuel injection direction is perpendicular to the axial direction of the fuel pipe; The multiple fuel injection holes are divided into multiple groups, each group including several fuel injection holes. The several fuel injection holes are circumferentially distributed at the same cross section, and the spacing between the multiple groups of fuel injection holes decreases sequentially from the open end to the closed end. The air pipe includes a premixing section and a mixing section connected in sequence, and the fuel pipe is located in the premixing section of the air pipe.

2. The micro-mixing single-nozzle burner according to claim 1, characterized in that, The air holes can be circular, polygonal, or strip-shaped.

3. A micro-mixing single-nozzle burner according to claim 1, characterized in that, The number of air holes is multiple, and the multiple air holes are evenly distributed around the circumference.

4. A micro-mixing single-nozzle burner according to claim 1, characterized in that, The air hole is 10 mm long, 2 mm wide, and has an air tube diameter of 8 mm.

5. A micro-mixing single-nozzle burner according to claim 1, characterized in that, The number of fuel injection holes is 12, the hole spacing is 5 mm, and the diameter of the fuel injection holes is 0.8 mm.

6. A burner, characterized in that, Includes the micro-mixing single nozzle as described in any one of claims 1-5.

7. A gas turbine, characterized in that, Includes the burner as described in claim 6.

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