A multi-layer swirled premixing nozzle for pure hydrogen gas turbine

Abstract

The application discloses a multilayer rotational flow premixing nozzle for pure hydrogen gas turbine, and relates to the technical field of gas turbine, which comprises a gas collecting cabin, a hydrogen pressure stabilizing chamber arranged in the gas collecting cabin, a hydrogen inlet arranged on the circumferential side wall of the gas collecting cabin close to one end of the gas collecting cabin, and the hydrogen inlet being communicated with the hydrogen pressure stabilizing chamber; a plurality of micro mixing pipes axially penetrating through the gas collecting cabin and being arranged in a multilayer annular shape along the circumference of the gas collecting cabin, comprising a central layer and a plurality of peripheral layers arranged around the central layer, the micro mixing pipes being communicated with the hydrogen pressure stabilizing chamber for external air to enter and to be micro-premixed with hydrogen; the central layer is one micro mixing pipe coinciding with the axis of the gas collecting cabin, the micro mixing pipes of the peripheral layers are arranged in an inclined manner relative to the axis of the gas collecting cabin to form rotational flow, the plurality of micro mixing pipes in the same layer are arranged in an inclined manner along the same rotation direction, and the plurality of micro mixing pipes of adjacent layers are arranged in opposite rotation directions. The application can improve combustion stability, inhibit thermal acoustic oscillation, strengthen hydrogen-air mixing, reduce the risk of backfire, and adapt to safe and efficient combustion of pure hydrogen.

Description

Technical Field

[0001] This invention relates to the field of gas turbine technology, and more particularly to a multi-layer swirl premixing nozzle for pure hydrogen gas turbines. Background Technology

[0002] Hydrogen energy, with its advantages of zero carbon emissions and high energy density, has become an important direction for replacing gas turbine fuels. However, pure hydrogen gas turbines still face many technical challenges in practical applications. Hydrogen flames are shorter and adiabatic flames are hotter, easily forming localized high-temperature zones, resulting in higher pollutant emissions. Furthermore, the flame's proximity to the nozzle can easily cause nozzle erosion. Hydrogen has a wide range of combustion concentrations and a fast flame propagation speed, significantly increasing the risk of backfire during premixed combustion. Under high-hydrogen conditions, the short ignition delay time also greatly increases the probability of accidental spontaneous combustion. Hydrogen's rapid heat release rate easily leads to increased pressure pulsation and higher frequency in the combustion chamber, generating significant thermoacoustic oscillations and reducing combustion stability. Hydrogen's low density and weak penetration in the combustion chamber result in poor mixing uniformity with air, directly affecting combustion efficiency and operational reliability. Without modifying the existing compressor and combustion chamber, optimizing the nozzle structure is the main technical approach to solving the problems of pure hydrogen combustion.

[0003] Micro-mixing combustion, through the organization of combustion with numerous micro-premixed flames, can enhance the rapid and uniform mixing of fuel and air, reduce local fuel enrichment, and lower local hot spots and pollutant emissions. The smaller premixing pipe diameter and high-speed airflow within the pipe can also suppress backfire and spontaneous combustion to a certain extent, making it a preferred technical solution for pure hydrogen combustion. However, existing micro-mixing combustion structures still have significant drawbacks: the micro-mixed jet flame lacks a recirculation zone, resulting in poor combustion stability under low-load conditions; densely distributed micro-mixed flames are prone to dynamic asynchrony, which can still induce thermoacoustic oscillations; the backfire risk of conventional micro-mixing structures has not been effectively eliminated, and the airflow organization and stratification layout are unreasonable, making it difficult to balance mixing uniformity, combustion stability, and thermoacoustic oscillation suppression effects. Consequently, it cannot fully adapt to the characteristics of pure hydrogen combustion and cannot meet the long-term safe, stable, and efficient operation requirements of pure hydrogen gas turbines. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, the present invention provides a multi-layer swirl premixing nozzle for pure hydrogen gas turbines.

[0005] To achieve the above objectives, the present invention provides a multi-layer swirl premixing nozzle for a pure hydrogen gas turbine, comprising: A gas collection chamber is provided inside which a hydrogen pressure stabilizing chamber is installed. A hydrogen inlet is provided on the circumferential side wall near one end of the gas collection chamber, and the hydrogen inlet is connected to the hydrogen pressure stabilizing chamber. Multiple micro-mixing pipes are axially inserted through the gas collection chamber and arranged in a multi-layered ring around the circumference of the gas collection chamber, including a central layer and multiple peripheral layers surrounding the central layer. The micro-mixing pipes are connected to the hydrogen pressure stabilizing chamber for the entry of external air and micro-premixing with hydrogen. The central layer is a micro-mixing tube that coincides with the centerline of the gas collection chamber. The micro-mixing tubes in the outer layer are inclined relative to the centerline of the gas collection chamber to form a vortex. Multiple micro-mixing tubes in the same layer are inclined in the same direction of rotation, while multiple micro-mixing tubes in adjacent layers have opposite directions of rotation.

[0006] Preferably, the micro-mixing pipe is provided with an air inlet, an air flow stabilization section, a venturi tube, a mixing flow stabilization section and an outlet convergence section that are interconnected along the airflow direction; The air inlet and the hydrogen inlet are located at the same end of the gas collection chamber. The air inlet is used for the entry of external air. The diameter of the inner wall of the outlet converging section gradually decreases along the airflow direction to increase the ejection velocity. A hydrogen injection port is provided on the circumferential sidewall of the micro-mixing tube corresponding to the venturi tube. The hydrogen injection port is connected to the interior of the micro-mixing tube and the hydrogen pressure stabilizing chamber, so that hydrogen is drawn into the micro-mixing tube by the negative pressure generated by the venturi tube.

[0007] Preferably, a mixer is provided in the mixing and stabilizing section. The mixer is a grate mixer, which is used to enhance airflow disturbance.

[0008] Preferably, the plurality of peripheral layers include an inner layer and an outer layer, wherein the number of outer layer micro-mixing tubes is twice the number of inner layer micro-mixing tubes.

[0009] Preferably, the micro-mixing tubes of the outer layer have a consistent tilt angle.

[0010] Preferably, the tilt angle ranges from 5° to 15°.

[0011] Preferably, the hydrogen ejector port is located at the minimum cross-sectional position of the venturi tube.

[0012] Preferably, the minimum inner diameter of the outlet converging section is set such that the Mach number of the premixed combustible gas outlet velocity is greater than 0.3.

[0013] Preferably, there are 2 to 4 hydrogen inlets, and the hydrogen inlets are evenly arranged around the gas collection chamber.

[0014] Preferably, the hydrogen inlet and the hydrogen ejector of the micro-mixing tube are offset from each other in the circumferential direction.

[0015] Based on this, the beneficial effects of the present invention are as follows: 1. This invention features a single micro-mixing pipe arranged in the center of the gas collection chamber, which can form a stable reference flame and construct a reliable combustion recirculation zone, effectively adapting to the characteristics of the fast propagation speed of hydrogen flame and improving the problem of unstable combustion under low load conditions; at the same time, multiple layers of annular peripheral micro-mixing pipes are arranged around the outer perimeter of the central layer, and the peripheral layer micro-mixing pipes are inclined to form swirls, with the same swirling direction in the same layer and the opposite swirling direction in adjacent layers. Through the mutual collision of multiple layers of swirls, the flow field distribution in the combustion chamber is effectively balanced, the combustion pressure pulsation is weakened, and the thermoacoustic oscillation problem that is prone to occur under pure hydrogen combustion conditions is significantly suppressed; 2. This invention arranges multiple micro-mixing pipes in parallel within the gas collection chamber. After the hydrogen is pressurized by the gas collection chamber, it can be synchronously and uniformly supplied to each micro-mixing pipe. It abandons the traditional center-to-outside step-by-step series gas supply mode, eliminates the problems of delayed gas supply and uneven pressure distribution in the outer micro-mixing pipes, and ensures that the gas intake of each pipeline is balanced and stable, which is suitable for the application characteristics of low density of pure hydrogen fuel and high requirements for flow distribution accuracy. 3. This invention utilizes the venturi structure of the micro-mixing tube to create an ejector inlet effect, which, together with the mixer, enhances the hydrogen-air premixing effect. At the same time, it relies on the swirling airflow to strengthen lateral mixing, compensating for the shortcomings of weak hydrogen penetration and poor mixing uniformity, reducing the generation of local high-temperature areas, and lowering pollutant emissions. The high-speed swirling flow inside the tube can block flame backlash, effectively avoiding the risks of backfire and spontaneous combustion of pure hydrogen. There is no need to modify the existing compressor and combustion chamber; simply by optimizing the nozzle structure, mixing uniformity, combustion stability, and operational safety can be simultaneously achieved. Attached Figure Description

[0016] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 A schematic diagram illustrating the structure of a premixing nozzle according to one embodiment of the present invention; Figure 2 A schematic axial cross-sectional view of a premixing nozzle according to one embodiment of the present invention; Figure 3 A schematic radial cross-sectional view of a premixing nozzle according to one embodiment of the present invention; Figure 4 A schematic cross-sectional view of a micro-mixing tube according to one embodiment of the present invention; Explanation of reference numerals in the attached diagram: 10-Gas collection chamber, 101-Hydrogen pressure stabilizing chamber, 102-Hydrogen inlet, 20-Micro-mixing pipe, 201-Air inlet, 202-Air flow stabilizing section, 203-Venturi tube, 204-Mixing flow stabilizing section, 2041-Mixer, 205-Outlet convergence section, 206-Hydrogen ejector port. Detailed Implementation

[0017] 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, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a," "the," and "the" as used in the embodiments of this application are also intended to include the plural forms unless the context clearly indicates otherwise.

[0019] It should be understood that although terms such as first, second, third, etc., may be used to describe related structures in the embodiments of this application, these related structures should not be limited to these terms. These terms are only used to distinguish related structures from each other.

[0020] Depending on the context, the word "if" as used here can be interpreted as "when" or "when". Similarly, depending on the context, the phrase "if determined" can be interpreted as "when determined" or "when (the condition or event of the statement) is detected".

[0021] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should also be understood that when it is mentioned that an element is formed "upper" or "lower" of another element, it can not only be formed directly "upper" or "lower" of the other element, but also indirectly "upper" or "lower" of the other element through an intermediate element.

[0022] Figure 1 This schematic diagram illustrates the structure of a premixing nozzle according to one embodiment of the present invention. Figure 2 This schematic diagram shows an axial sectional view of a premixing nozzle according to one embodiment of the present invention. Figure 3 This schematic diagram shows a radial cross-sectional view of a premixing nozzle according to one embodiment of the present invention. Figure 4 A schematic cross-sectional view of a micro-mixing tube according to one embodiment of the present invention is shown, such as... Figure 1-4 As shown, a multi-layer swirl premixing nozzle for a pure hydrogen gas turbine according to the present invention includes: The gas collecting chamber 10 is the core pressure-bearing and pressure-equalizing component of the nozzle. Its enclosed interior forms a hydrogen pressure-stabilizing chamber 101, which buffers, stabilizes, and evenly distributes hydrogen, providing stable gas supply conditions for each micro-mixing pipe 20. A hydrogen inlet 102 is arranged on the circumferential sidewall of the gas collecting chamber 10 near the inlet end. The hydrogen inlet 102 is directly connected to the hydrogen pressure-stabilizing chamber 101, enabling the smooth introduction of external hydrogen into the chamber, reducing local pressure fluctuations caused by inlet shock, and ensuring gas supply stability.

[0023] Multiple micro-mixing pipes 20 extend axially through the gas collection chamber 10 and are arranged in a multi-layered ring array centered on the axis of the gas collection chamber 10. The whole is divided into a central layer and multiple outer layers surrounding the central layer. All micro-mixing pipes 20 are connected to the hydrogen pressure stabilizing chamber 101. External air enters from the front end of the micro-mixing pipe 20 and is rapidly and fully micro-premixed with the hydrogen output from the hydrogen pressure stabilizing chamber 101 inside the pipe, providing a uniform and stable combustible mixture for the combustion chamber, which is suitable for the low density and high reactivity combustion characteristics of pure hydrogen.

[0024] The central layer is equipped with a single micro-mixing pipe 20, which is coaxially arranged with the center line of the gas collection chamber 10. During operation, it can form a stable central reference torch and establish a stable combustion recirculation zone inside the combustion chamber, effectively improving the problem of easy flameout and insufficient combustion stability of pure hydrogen micro-mixing flame under low load conditions.

[0025] Multiple micro-mixing tubes 20 in the outermost layer are arranged at an angle relative to the centerline of the gas collection chamber 10 to form a rotating jet. The micro-mixing tubes 20 in the same outermost layer have the same rotation direction, while the micro-mixing tubes 20 in adjacent outermost layers have opposite rotation directions. The flow field is homogenized by counter-swirling flow, which reduces combustion pressure pulsation and suppresses the thermoacoustic oscillations that are prone to occur during pure hydrogen combustion from a structural level.

[0026] Multiple micro-mixing pipes 20 are connected in parallel within the gas collection chamber 10, eliminating the drawbacks of uneven flow distribution and delayed outer layer gas supply caused by traditional series gas supply. During operation, air enters each micro-mixing pipe 20 from the front end; hydrogen enters the hydrogen pressure stabilizing chamber 101 through the hydrogen inlet 102, and after sufficient pressure stabilization and flow equalization, it enters each micro-mixing pipe 20 synchronously and evenly, completing efficient micro-premixing with the air inside the pipe.

[0027] Part of the premixed combustible gas is directly injected axially by the central layer micro-mixing pipe 20 to form a reference flame and a stable recirculation zone, ensuring reliable ignition and stable combustion under low load; the other part is injected in a swirling manner by multiple peripheral layer micro-mixing pipes 20. The swirling flows in the same direction in the same layer and in opposite directions in adjacent layers interact in the combustion chamber to achieve flow field reconstruction and pressure balance, significantly improving the stability and operational safety of the entire pure hydrogen combustion process.

[0028] The micro-mixing pipe 20 is sequentially provided with an air inlet 201, an air stabilization section 202, a venturi tube 203, a mixing stabilization section 204, and an outlet convergence section 205 that are interconnected along the airflow direction, forming a complete airflow channel from air intake, injection, mixing to stabilization and ejection, so as to realize efficient premixing and safe injection of pure hydrogen and air.

[0029] Air inlet 201 and hydrogen inlet 102 are located at the same end of gas collection chamber 10, allowing external combustion air to enter smoothly; the diameter of the inner wall of outlet convergent section 205 gradually shrinks along the airflow direction, forming a tapered nozzle structure, which increases the outlet velocity of premixed combustible gas, maintains a high flow velocity in the pipe, and suppresses the risk of backfire from the flow field level.

[0030] A hydrogen injection port 206 is provided on the circumferential sidewall of the micro-mixing tube 20 corresponding to the venturi tube 203. The hydrogen injection port 206 connects the interior of the micro-mixing tube 20 to the hydrogen pressure stabilizing chamber 101. When air flows through the venturi tube 203, the flow velocity increases rapidly and the local pressure decreases, forming a stable negative pressure zone. Under the action of the pressure difference, the hydrogen in the hydrogen pressure stabilizing chamber 101 is actively drawn into the interior of the micro-mixing tube 20, realizing ejector-type air intake and preliminary mixing, increasing the hydrogen entry velocity and the air convection impact intensity, and enhancing the premixing effect.

[0031] The orifice diameter of the air inlet 201 is set to 3-6 mm, which can be flexibly adjusted according to the design flow rate. Both the air stabilization section 202 and the mixing stabilization section 204 adopt a straight pipe structure with equal diameter to eliminate inlet airflow distortion and reduce turbulence disturbance, providing a stable and uniform flow field for subsequent Venturi ejection and outlet injection.

[0032] To further improve the ejection efficiency, the hydrogen ejection port 206 is located at the minimum cross-section of the venturi tube 203. This location is the negative pressure peak region of the venturi tube 203, which can maximize the ejection pressure difference and hydrogen intake flow rate, enhance the convective mixing intensity of hydrogen and air, and improve the initial mixing uniformity.

[0033] A grate-type mixer 2041 is installed inside the mixing and stabilizing section 204. The mixer 2041 is located downstream of the Venturi tube 203 and maintains a set distance from the Venturi tube 203 to avoid interfering with the stable establishment of the ejector negative pressure zone. After the hydrogen and air mixture initially mixed in the Venturi tube 203 enters the grate-type mixer 2041, the turbulence intensity and mixing scale inside the tube are significantly improved under the cutting, disturbance, and reversal effects of the grate structure. The hydrogen and air achieve more refined and uniform secondary mixing, effectively eliminating local fuel enrichment zones, reducing the generation of combustion hot spots, and providing a low-temperature, low-NOx environment. x The emission combustion lays the foundation; the fully mixed airflow completes pressure stabilization, flow stabilization and flow field adjustment in the mixing and stabilizing section 204, and then enters the outlet convergence section 205 for ejection.

[0034] The outlet convergence section 205 adopts an inner wall linear tapering structure with a minimum inner diameter of no more than 4mm. Under the constraint of the small-sized throat, the premixed combustible gas is kept at a high flow rate of Mach number Ma>0.3 at the outlet section. The high-speed airflow forms an effective gas barrier to prevent the flame from backflashing into the premixed channel. From both structural design and flow field control, the risk of backfire and spontaneous combustion is suppressed, which greatly improves the safety and reliability of pure hydrogen premixed combustion.

[0035] Multiple outer layers are preferably configured as a two-layer structure of inner and outer layers. The number of outer layer micro-mixing tubes 20 is twice the number of inner layer micro-mixing tubes 20. While ensuring the swirling intensity, the flow rate and flow field gradient are matched, thereby improving the overall mixing uniformity and combustion stability.

[0036] The two outer micro-mixing tubes 20 are tilted at the same angle, with a tilt angle range of 5° to 15°. This can form an effective swirling flow while avoiding problems such as jet deflection, increased flow resistance, and aggravated thermoacoustic oscillations caused by excessively large angles.

[0037] To ensure uniform pressure distribution and absence of local stagnation areas within the hydrogen pressure stabilizing chamber 101, 2 to 4 hydrogen inlets 102 are provided. Each hydrogen inlet 102 is arranged symmetrically and uniformly around the gas collecting chamber 10 to achieve synchronous gas intake from multiple directions and quickly balance the pressure within the chamber.

[0038] Meanwhile, the hydrogen inlet 102 and the hydrogen ejector port 206 of the micro-mixing tube 20 are staggered in the circumferential position to avoid the direct impact of high-pressure hydrogen on the ejector port, which would cause local pressure fluctuations, uneven flow distribution and increased operating noise. This ensures that the ejector flow of each micro-mixing tube 20 is consistent and the mixing state is stable, thereby improving the overall operating consistency and long-term reliability of the nozzle.

[0039] In summary, the premixed nozzle of this invention, through the integrated structure of the gas collecting chamber 10, the hydrogen pressure stabilizing chamber 101, and multiple micro-mixing tubes 20, combined with the synergistic design of the venturi tube 203, the grate mixer 2041, and the outlet convergence section 205, achieves efficient injection, enhanced mixing, and stable flow injection of hydrogen and air. The micro-mixing tubes 20 adopt a central direct-blowing and multi-layer reverse swirl arrangement, with the same layer in the same direction and the adjacent layers in opposite directions counteracting each other, which can balance the flow field of the combustion chamber and suppress thermoacoustic oscillations. The outlet convergence section 205 maintains an outlet Mach number Ma > 0.3 with a small-diameter structure, effectively suppressing backfire and reducing the risk of spontaneous combustion. The central layer micro-mixing tubes 20 form a stable reference flare and recirculation zone, significantly improving the stability of low-load combustion. The overall structure, while achieving uniform premixing of hydrogen and air, can suppress local high temperatures and reduce pollutant emissions, meeting the requirements for safe, stable, efficient, and low-emission operation of pure hydrogen gas turbines, and possesses good engineering applicability and long-term reliability.

[0040] The above description is merely a preferred embodiment of this application. Those skilled in the art should understand that the scope of disclosure in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A multi-layer swirl premixing nozzle for a pure hydrogen gas turbine, characterized in that, include: A gas collection chamber is provided inside which a hydrogen pressure stabilizing chamber is installed. A hydrogen inlet is provided on the circumferential side wall near one end of the gas collection chamber, and the hydrogen inlet is connected to the hydrogen pressure stabilizing chamber. Multiple micro-mixing pipes penetrate the gas collection chamber and are arranged in a multi-layered ring around the circumference of the gas collection chamber, including a central layer and multiple peripheral layers surrounding the central layer. The micro-mixing pipes are connected to the hydrogen pressure stabilizing chamber for the entry of external air and micro-premixing with hydrogen. The central layer is a micro-mixing tube that coincides with the axis of the gas collection chamber. The micro-mixing tubes of the outer layer are inclined relative to the axis of the gas collection chamber to form a vortex. Multiple micro-mixing tubes in the same layer are inclined along the same direction of rotation, while multiple micro-mixing tubes in adjacent layers have opposite directions of rotation. The micro-mixing pipe is provided with an interconnected air inlet, an air flow stabilization section, a venturi tube, a mixing flow stabilization section, and an outlet convergence section along the airflow direction. The air inlet and the hydrogen inlet are located at the same end of the gas collection chamber. The air inlet is used for the entry of external air. The diameter of the inner wall of the outlet converging section gradually decreases along the airflow direction to increase the ejection velocity. A hydrogen injection port is provided on the circumferential sidewall of the micro-mixing tube corresponding to the venturi tube. The hydrogen injection port is connected to the interior of the micro-mixing tube and the hydrogen pressure stabilizing chamber, so that hydrogen is drawn into the micro-mixing tube by the negative pressure generated by the venturi tube. A mixer is provided in the mixing and stabilizing section. The mixer is a grate-type mixer, which is used to enhance airflow disturbance. The micro-mixing tubes in the outer layer have a consistent tilt angle, which ranges from 5° to 15°. The minimum inner diameter of the outlet convergence section is set to ensure that the Mach number of the premixed combustible gas outlet velocity is greater than 0.

3.

2. The multi-layer swirl premixing nozzle for a pure hydrogen gas turbine according to claim 1, characterized in that, The plurality of peripheral layers include an inner layer and an outer layer, wherein the number of outer layer micro-mixing tubes is twice the number of inner layer micro-mixing tubes.

3. A multi-layer swirl premixing nozzle for a pure hydrogen gas turbine according to claim 1, characterized in that, The hydrogen ejector port is located at the minimum cross-sectional position of the venturi tube.

4. A multi-layer swirl premixing nozzle for a pure hydrogen gas turbine according to claim 1, characterized in that, The hydrogen inlet is configured to have 2 to 4 inlets, and the multiple hydrogen inlets are evenly arranged around the circumference of the gas collection chamber.

5. A multi-layer swirl premixing nozzle for a pure hydrogen gas turbine according to claim 1, characterized in that, The hydrogen inlet and the hydrogen ejector of the micro-mixing tube are circumferentially offset from each other.

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