Micro-mixing single nozzle, combustor and gas turbine

Abstract

The invention discloses a micro-mixing single nozzle, a combustor and a gas turbine, and belongs to the technical field of combustor design. The micro-mixing single nozzle combustor comprises a fuel pipe and an air pipe; one end of the fuel pipe is a fuel inlet, the other end of the fuel pipe is closed, and a plurality of fuel perforations are formed in the side wall; air holes are formed in the side wall of one end of the air pipe, and the other end of the air pipe is an ignition end; the fuel pipe is coaxially arranged in the air pipe in a sleeved mode, the inlet end of the fuel pipe is connected with the end of the air pipe in a sealed mode, an annular space used for mixing gas is formed between the fuel pipe and the air pipe, and the air holes are communicated with the annular space. Oxidation gas flows into the air pipe through the air holes, the fuel injection direction is perpendicular to the air flowing direction, and fuel is mixed in an annular area in a cross jet mode. The micro-mixing single-nozzle combustor has the advantages of efficient mixing, compact structure, high flexibility, easiness in manufacturing and maintenance, environmental protection, energy conservation and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of burner design, and in particular to a micro-mixing single nozzle, a burner and a gas turbine. Background Art

[0002] The micro-mixing single nozzle is the core component of the burner. Its function is to mix the fuel and gas. The micro-mixing single nozzle uses a micro-tube instead of a traditional single thick tube to organize combustion. Since the spatial size is significantly reduced, the degree of mixing of fuel and air is generally high. Existing micro-mixing single nozzle burners usually have fuel and air inlets respectively opened on a single tube, and the fuel flow and air flow are premixed in the tube, resulting in a long premixing distance. Flashback is a phenomenon in which the flame flows back to the fuel supply system during the combustion process. In a micro-mixing single nozzle burner, due to the small tube diameter and the fuel and air mixing area close to the nozzle outlet, once flashback occurs, the flame will quickly spread to the entire micro-tube, which may cause damage to the entire micro-tube. When the micro-tube works under high pressure and high temperature conditions, its material properties may be affected, such as decreased strength, increased creep, etc., and may even damage the nozzle or other key components, causing serious safety accidents. Summary of the invention

[0003] In view of 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 ejected from the fuel perforations opened downstream, and the air flows into the air pipe through the air holes. The fuel injection direction is perpendicular to the air flow direction, and the two are mixed in the form of cross jets, shortening the premixing distance of the fuel gas and air, improving the mixing uniformity, solving the flashback problem of the micro-mixing single nozzle burner, and improving the safety of the entire burner.

[0004] The present invention is achieved through the following technical solutions: In a first aspect, the present application provides a micro-mixing single nozzle burner, comprising a fuel pipe and an air pipe; One end of the fuel pipe is a fuel inlet, the other end is closed, and a plurality of fuel perforations are arranged 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 an ignition end; The fuel pipe is coaxially sleeved in the air pipe, the inlet end of the fuel pipe is sealed and connected to the end of the air pipe, an annulus for mixed gas is formed between the fuel pipe and the air pipe, and the air hole is connected to the annulus; The oxidizing gas flows into the air pipe from the air hole, the fuel injection direction is perpendicular to the air flow direction, and is mixed in the annular area in the form of cross jets.

[0005] Preferably, the plurality of fuel perforations are spaced apart along the axial direction of the fuel pipe, the plurality of fuel perforations are arranged in an equidistant manner, and the injection direction of the fuel is perpendicular to the axial direction of the fuel pipe.

[0006] Preferably, the plurality of fuel perforations are divided into a plurality of groups, each group includes a plurality of fuel perforations, the plurality of fuel perforations are circumferentially distributed at the same cross section, and the spacing between the plurality of fuel groups decreases from the open end to the closed end.

[0007] Preferably, the air pipe comprises a premixing section and a mixing section which are connected in sequence, and the fuel pipe is located in the premixing section of the air pipe.

[0008] Preferably, the air holes are circular, polygonal or strip-shaped holes.

[0009] Preferably, there are multiple air holes, and the multiple air holes are evenly distributed around the circumference.

[0010] Preferably, the air hole has a length of 10 mm, a width of 2 mm, and an air tube diameter of 8 mm.

[0011] Preferably, the number of the fuel perforations is 12, the hole spacing is 5 mm, and the hole diameter of the fuel perforations is 0.8 mm.

[0012] In a second aspect, the present application provides a burner including the micro-mixing single nozzle.

[0013] In a third aspect, the present application provides a gas turbine comprising the above-mentioned burner.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention provides a micro-mixing single nozzle, which is composed of a fuel pipe and an air pipe coaxially sleeved, the top end of the fuel pipe is closed, the fuel gas is sprayed out from a small hole opened downstream, and the 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 jets. This mixing method significantly shortens the premixing distance of the fuel gas and the air, improves the uniformity of the mixing, and thus ensures the high efficiency and stability of the combustion; the micro-mixing single nozzle burner has the advantages of efficient mixing, compact structure, high flexibility, optimized air hole design, easy manufacturing and maintenance, and environmental protection and energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 It is a structural schematic diagram of a micro-mixing single nozzle of the present invention; Figure 2 It is an end view of the micro-mixing single nozzle of the present invention; Figure 3 It is a structural schematic diagram of the fuel pipe of the present invention; Figure 4 It is a schematic structural diagram of the burner of the present invention.

[0017] In the figure, 1, air pipe; 2, fuel pipe; 3, fuel perforation; 4, air hole; 5, annulus. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0020] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0021] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invented product is usually placed when used. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0022] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0023] In the description of the embodiments of the present application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0024] The working principle of the premixing fuel nozzle is to premix the fuel and air inside the nozzle to form a fuel-air mixture of a certain proportion, and then enter the combustion chamber for combustion. This premixing method allows the fuel to be fully mixed with the air before entering the combustion chamber, thereby improving the combustion efficiency and stability of the fuel. Specifically, the premixing fuel nozzle usually has parts such as a fuel inlet, an air inlet, a mixing chamber and a nozzle. The fuel and air enter the mixing chamber through these inlets, and after being fully mixed in the mixing chamber, they are ejected from the nozzle into the combustion chamber for combustion.

[0025] Since the fuel and air have been fully mixed at the nozzle, they can burn quickly and completely after entering the combustion chamber, thereby improving combustion efficiency. This helps to reduce fuel waste and emission generation, and has positive significance for environmental protection. The premixed fuel nozzle can reduce pollutant emissions generated during the combustion process by optimizing the mixing ratio and mixing effect of fuel and air. This helps to reduce the emission of harmful substances such as nitrogen oxides and carbon monoxide, and meets modern environmental protection requirements. Since the fuel and air have been fully mixed, the flame during the combustion process is more stable. In view of the problems of long mixing distance and easy flashback in existing premixed fuel nozzles, this application designs a micro-mixing single nozzle.

[0026] See also Figure 1-3 , a micro-mixing single nozzle, comprising a fuel pipe 2 and an air pipe 1; One end of the fuel pipe 2 is a fuel inlet, the other end is closed, and a plurality of fuel perforations 3 are arranged on the side wall; An air hole 4 is provided on the side wall of one end of the air pipe, and the other end is an ignition end; The fuel pipe is coaxially sleeved in the air pipe, the inlet end of the fuel pipe is sealed and connected to the end of the air pipe, an annulus 5 for mixed gas is formed between the fuel pipes, and the air hole is connected to the annulus.

[0027] The micro-mixing single nozzle is composed of a fuel pipe and an air pipe arranged inside and outside, and an annular space for users to mix fuel and air is formed between the fuel pipe and the air pipe. The fuel gas is ejected from the fuel perforations opened downstream, and the air flows into the air pipe from the air holes. The fuel injection direction is perpendicular to the air flow direction, and the two are mixed in the form of cross jets, shortening the premixing distance of the fuel gas and air and improving the mixing uniformity.

[0028] In some embodiments, the fuel pipe is an open structure at one end and a closed structure at the other end, the open end is a fuel inlet, the fuel pipe is sleeved in the air pipe, and the fuel pipe and the end of 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 a fuel delivery pipeline, the fuel gas is injected into the fuel pipe in a pressurized manner, and flows out through the fuel perforations.

[0029] In some embodiments, multiple fuel perforations are spaced apart along the axial direction of the fuel pipe, the multiple fuel perforations are arranged at equal intervals, and the fuel injection direction is perpendicular to the axial direction of the fuel pipe, that is, the axial direction of the fuel perforations is arranged along the radial direction of the fuel pipe.

[0030] In another embodiment, the plurality of fuel perforations are divided into a plurality of groups, each group includes a plurality of fuel perforations, the plurality of fuel perforations are circumferentially distributed at the same cross section, and the number of the plurality of fuel perforations is 2-4; the plurality of groups of fuels are arranged at equal intervals, or the intervals decrease in sequence from the open end to the closed end.

[0031] In some embodiments, the air pipe is a hollow pipe with two ends open, one end of which is sealed and connected to the outside of the fuel pipe, and the other end serves as an outlet for the mixed fuel. The air pipe is divided into two sections, one end is a premixing section, and the other end is a mixing section. The fuel pipe is located in the premixing section of the air pipe, and the premixed fuel passes through the mixing section and is ignited at the outlet. The inner diameter of the air pipe is larger than the outer diameter of the fuel pipe. When the two are coaxially sleeved, an annular space is formed between the air pipe and the fuel pipe, which serves as a premixing section for fuel and air. The end of the air pipe is connected to the fuel pipe through a sealing structure.

[0032] The air hole is arranged on the outer wall of the air pipe and close to the end. The air hole is connected with the premixing section and is located on one side close to the end of the premixing section. The air enters the premixing section radially and then flows axially, while the fuel gas flows axially into the fuel pipe and then enters the premixing section radially along the fuel perforations. In the premixing section, the flow directions of the fuel airflow and the air airflow are perpendicular to each other, forming a cross mixed flow.

[0033] In some embodiments, the air hole is circular, polygonal, approximately circular or strip-shaped, preferably a strip-shaped hole, and the long direction of the strip-shaped hole is arranged along the axial direction of the air tube.

[0034] There are multiple air holes, which are evenly distributed around the circumference. The number is 2-4, preferably 4, and they are symmetrically arranged in pairs. The holes are preferably strip holes.

[0035] Since the parameters of the air holes and fuel perforations have a key influence on the uniformity of fuel and air mixing and the nozzle pressure loss, optimal design of the air holes and fuel perforations can avoid the flashback phenomenon of the micro-mixing single nozzle burner. To address this problem, the present application uses a three-dimensional numerical simulation method to optimize the micro-mixing single nozzle to determine the optimal parameters of the air holes and fuel perforations, so as to optimize the performance of the micro-mixing single nozzle.

[0036] The length of the air hole is 10 mm, the width is 2 mm, and the air tube diameter is 8 mm.

[0037] After simulation verification, when the length of the air hole is 10 mm, the air inlet width is 2 mm, and the air pipe diameter is 8 mm, the uniformity index is the largest, the fuel-air mixing effect is the best, and the total pressure loss coefficient meets the requirements.

[0038] The number of the fuel perforations is 12, the hole spacing is 5 mm, and the hole diameter of the fuel perforations is 0.8 mm.

[0039] After simulation calculations of different numbers of fuel perforations, it is found that as the number of holes increases, the total pressure loss coefficient decreases nonlinearly. When the number of holes is greater than 8, the decrease rate decreases significantly. When the number of holes is 4, the corresponding nozzle total pressure loss coefficient is 6.217%. When the number of holes increases to 8, the total pressure loss coefficient decreases to 4.456%, which is close to the design standard. When the number of holes is increased to 12, the total pressure loss coefficient decreases to 3.996%. On this basis, the total pressure loss coefficient decreases to 3.663% when the number of holes is further increased to 24, with little change. Since the number of fuel injection holes has little effect on mixing uniformity, the number of fuel injection holes for micro-mixed burners is preferably 12 according to the total pressure loss coefficient of the nozzle.

[0040] The simulation verification of fuel perforations with different diameters shows that the variation trend of the uniformity index with axial distance is basically the same under different apertures. At a fixed axial height, when the aperture is 0.8 mm, the uniformity index is the largest, and when the axial height is 80 mm, the uniformity index is greater than 0.95, and the fuel-air mixing is optimal under this aperture. The total pressure loss coefficient shows a nonlinear downward trend with the increase of the aperture, and when the aperture is greater than 0.6 mm, the decline rate decreases significantly, and the total pressure loss coefficient decreases from 4.6% at 0.6 mm to about 3.8% at 1.2 mm. According to the above results, the uniformity index and the total pressure loss coefficient are comprehensively evaluated, and the aperture diameter of the fuel injection hole in the micro-mixed burner is preferably 0.8 mm.

[0041] The uniformity index under different hole spacings increases nonlinearly with the increase of axial height. Compared with the results of hole spacings of 2 mm, 7 mm and 10 mm, the uniformity index corresponding to the hole spacing of 5 mm is the largest at any axial height, and the uniformity index is greater than 0.95 when the axial height is 80 mm.

[0042] When the fuel pipe diameter increases from 1.5 mm to 3.0 mm, the total pressure loss coefficient decreases nonlinearly. When the fuel pipe diameter is greater than 2.0 mm, the decrease rate decreases significantly, and the total pressure loss coefficient is less than 5%. The fuel pipe diameter is preferably 2.0 mm.

[0043] With the optimal structure of air holes and fuel perforations, the fuel can be vertically injected into the surrounding air, and the two can be quickly and evenly mixed. By studying the influence of air inlet height, width and air pipe inner diameter on the airflow mixing process and nozzle pressure loss, and optimizing the micro-mixing single nozzle configuration with excellent performance according to the data change law; in this configuration, once backfire occurs, the flame will be transmitted back into the nozzle, and the flame will be extinguished near the downstream injection hole of the fuel pipe, and will not enter the fuel pipe to cause greater damage.

[0044] The micro-mixing single nozzle is composed of a fuel pipe and an air pipe coaxially arranged. The top of the fuel pipe is closed, and the fuel gas is ejected from a small hole opened downstream. The 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 jets. This mixing method significantly shortens the premixing distance of the fuel gas and air, improves the uniformity of the mixing, and thus ensures the high efficiency and stability of the combustion. The micro-mixing single nozzle burner has the advantages of efficient mixing, compact structure, high flexibility, optimized air hole design, easy manufacturing and maintenance, and environmental protection and energy saving.

[0045] Correspondingly, the present application also provides a burner, comprising the above-mentioned micro-mixing single nozzle, wherein a plurality of micro-mixing single nozzles are arranged in an array in the burner.

[0046] See also Figure 4The schematic diagram of the burner structure is shown in Figure 1. Fuel (such as natural gas, liquefied gas, etc.) and air are mixed in a micro-mixing single nozzle to form a combustible mixed gas to promote uniform mixing of fuel and air. The mixed combustible gas is ejected through the nozzle and ignited in the combustion chamber. The ignition system is usually composed of electrodes, spark plugs or flame sensors, etc., which are used to trigger electric sparks in the mixed gas to ignite the mixed gas. The high temperature and high pressure environment in the combustion chamber enables the mixed gas to burn quickly and stably. The ignited mixed gas burns in the combustion chamber, releasing a large amount of heat energy. The combustion process is stable and controllable, and the flame shape and combustion intensity can be adjusted by adjusting the mixing ratio of fuel and air and the parameters of the ignition device. The high temperature and high pressure gas generated by the combustion is partially expanded by the turbine to do work, converting the heat energy into mechanical energy. At the same time, part of the heat energy can also be transferred to other media (such as water, air, etc.) through equipment such as heat exchangers for heating or steam generation and other process processes.

[0047] The present application also provides a gas turbine, comprising the above-mentioned combustor.

[0048] In a gas turbine, the role of the burner is crucial. It is not only a key component for mixing and burning fuel and air, but also a core link for converting the chemical energy of the fuel into the thermal energy of high-temperature and high-pressure gas. Specifically, the burner receives the high-pressure and high-temperature air compressed by the compressor, mixes it with the injected fuel and ignites it. The high-temperature and high-pressure gas generated drives the turbine to rotate, and then drives the compressor to rotate at high speed, thereby partially converting the chemical energy of the fuel into mechanical work. In addition, the design and performance of the burner directly affect the combustion efficiency, emission characteristics and operating stability of the gas turbine. Therefore, in a gas turbine, the burner is a key component to ensure efficient and low-emission operation of the entire machine.

[0049] The micro-mixing single nozzle provided in this application has the following significant advantages: 1. Efficient mixing: Through the ingenious design of fuel perforations and air holes, fuel gas and air are mixed in the form of cross jets. 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.

[0050] 2. Compact structure: The burner adopts the structure of fuel pipe and air pipe inside and outside, which makes the overall structure compact and occupies less space. This design is not only easy to install and maintain, but also helps to improve the overall efficiency and reliability of the equipment.

[0051] 3. High flexibility: The design of fuel perforations has many possibilities, such as equal spacing arrangement, multiple groups of circular distribution, etc., which can be adjusted according to actual needs. This flexibility enables the burner to adapt to different fuel types and combustion requirements, improving its scope of application and performance.

[0052] 4. Optimize the air hole design: By optimizing the shape, number and position of the air holes, the mixing effect of fuel and air can be further improved and the occurrence of backfire can be avoided. This design not only improves the safety of the burner, but also helps to extend its service life.

[0053] 5. Easy to manufacture and maintain: The burner has a simple and clear structure, which is easy to manufacture and process. At the same time, due to the compact structure and reasonable connection between components, maintenance and overhaul work are more convenient.

[0054] In summary, the micro-mixing single nozzle burner has the advantages of efficient mixing, compact structure, high flexibility, optimized air hole design, easy manufacturing and maintenance, and environmental protection and energy saving. These advantages make the burner have broad application prospects in the fields of energy utilization, environmental protection and sustainable development.

[0055] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A micro-mixing single nozzle burner, characterized in that: Includes fuel and air pipes; One end of the fuel pipe is a fuel inlet, the other end is closed, and a plurality of fuel perforations are arranged 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 an ignition end; The fuel pipe is coaxially sleeved in the air pipe, the inlet end of the fuel pipe is sealed and connected to the end of the air pipe, an annulus for mixed gas is formed between the fuel pipe and the air pipe, and the air hole is connected to the annulus; The oxidizing gas flows into the air pipe from the air hole, the fuel injection direction is perpendicular to the air flow direction, and is mixed in the annular area in the form of cross jets.

2. The micro-mixing single nozzle burner according to claim 1, characterized in that: The plurality of fuel perforations are spaced apart along the axial direction of the fuel pipe, the plurality of fuel perforations are arranged in an equidistant manner, and the injection direction of the fuel is perpendicular to the axial direction of the fuel pipe.

3. The micro-mixing single nozzle burner according to claim 1, characterized in that: The multiple fuel perforations are divided into multiple groups, each group includes a plurality of fuel perforations, the plurality of fuel perforations are circumferentially distributed at the same cross section, and the spacing between the multiple groups of fuel perforations decreases from the open end to the closed end.

4. The micro-mixing single nozzle burner according to claim 1, characterized in that: The air pipe comprises a premixing section and a mixing section which are connected in sequence, and the fuel pipe is located in the premixing section of the air pipe.

5. The micro-mixing single nozzle burner according to claim 1, characterized in that: The air holes are circular, polygonal or strip-shaped holes.

6. The micro-mixing single nozzle burner according to claim 1, characterized in that: There are multiple air holes, and the multiple air holes are evenly distributed around the circumference.

7. The micro-mixing single nozzle burner according to claim 1, characterized in that: The length of the air hole is 10 mm, the width is 2 mm, and the air tube diameter is 8 mm.

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

9. A burner, characterized in that: It comprises the micro-mixing single nozzle as described in any one of claims 1 to 8.

10. A gas turbine, characterized in that: Comprising the burner as claimed in claim 9.

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