A fuel nozzle mixer suitable for use in a hydrogen-blend fuel gas turbine

Abstract

This disclosure provides a fuel nozzle mixer suitable for a hydrogen-fueled gas turbine, comprising: an inlet section, a constriction section, a throat, a diffuser section, and an outlet section arranged coaxially along the fluid flow direction; the constriction section is conical and gradually narrows along the fluid flow direction, with its outlet end connected to the throat; the throat is configured as a cylindrical structure; the diffuser section is conical and gradually widens along the fluid flow direction; an annular hydrogen injection mechanism is fitted and fixed to the inner wall of the constriction section; a swirling and turbulent mixing mechanism is disposed inside the throat; and a low-resistance guiding and rectifying mechanism is disposed inside the diffuser section.

Description

Technical Field

[0001] The embodiments disclosed herein belong to the technical field of gas turbine equipment, and specifically relate to a fuel nozzle mixer suitable for hydrogen mixed fuel gas turbines. Background Technology

[0002] As the global energy structure shifts towards low-carbon development, the application of hydrogen-blended fuels in gas turbines is receiving increasing attention.

[0003] However, for gas turbines using hydrogen-fuel mixtures, the homogeneity of the fuel mixture directly affects the stability of the combustion process, combustion efficiency, and nitrogen oxide (NOx) emission levels. Due to hydrogen's characteristics of rapid flame propagation, high diffusion coefficient, and strong reactivity, if the fuel and air are not sufficiently and uniformly mixed before entering the combustion chamber, local equivalence ratios will deviate from the design value, leading to a series of adverse consequences: Firstly, uneven mixing can induce combustion instability, generating pressure pulsations and combustion oscillations, which may severely damage equipment. Secondly, localized fuel-rich areas will generate high-temperature hotspots, promoting the large-scale generation of thermal NOx and significantly increasing the concentration of emitted pollutants. Furthermore, localized hydrogen accumulation may also trigger backfire risks, threatening the safe operation of the unit.

[0004] Therefore, how to solve the above problems has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The embodiments disclosed herein are intended to at least address one of the technical problems existing in the prior art, and to provide a fuel nozzle mixer suitable for hydrogen mixed fuel gas turbines.

[0006] One aspect of the embodiments of this disclosure provides a fuel nozzle mixer suitable for a hydrogen-mixed fuel gas turbine, comprising: The inlet section, constriction section, throat, diffuser section, and outlet section are arranged coaxially along the direction of fluid flow. The constriction section is conical and gradually narrows along the fluid flow direction, with its outlet end connected to the throat. The throat is configured as a cylindrical structure; The diffusion section is conical and gradually expands along the direction of fluid flow; An annular hydrogen injection mechanism is fitted and fixed to the inner wall of the contraction section; A swirling and turbulent mixing mechanism is disposed inside the throat; and, A low-resistance flow guiding and rectifying mechanism is disposed inside the diffuser section.

[0007] Optionally, the taper of the contraction section is set between 30° and 45°; the taper of the diffusion section is set between 20° and 30°.

[0008] Optionally, the annular hydrogen injection mechanism is configured as an annular hydrogen injection ring with 12 to 16 injection holes evenly distributed on it, and the injection direction of all the injection holes is inclined toward the central axis of the throat.

[0009] Optionally, it also includes a hydrogen delivery regulating mechanism, which includes a hydrogen delivery pipe connected to the annular hydrogen injection ring and a flow regulating valve installed in series on the hydrogen delivery pipe.

[0010] Optionally, the swirling mixing mechanism includes 3 to 4 turbulence blades, which are evenly distributed in a circumferential array along the throat, and each turbulence blade is inclined at 30° to 45° relative to the axial flow direction of the mixer.

[0011] Optionally, the root of the deflector blade is integrally fixed to the inner wall of the throat.

[0012] Optionally, the low-resistance guiding and rectifying mechanism includes 2 to 3 arc-shaped guide plates, which extend along the generatrix direction of the diffuser section and are arranged to fit the conical inner wall curved surface of the diffuser section.

[0013] Optionally, the curvature of the arc-shaped guide plate matches the curvature of the inner wall of the diffuser section, and the arc-shaped guide plate is configured as a low-profile, wall-mounted protrusion structure and distributed in the near-wall boundary layer region of the pipe.

[0014] Optionally, when there are two arc-shaped guide vanes, the two arc-shaped guide vanes are symmetrically distributed at 180°; when there are three arc-shaped guide vanes, the three arc-shaped guide vanes are circumferentially distributed at 120° intervals.

[0015] Optionally, the mixer is configured as an axisymmetric, integral tubular structure.

[0016] The beneficial effects of the embodiments of this disclosure include: In this application, the efficient and deep mixing of hydrogen and gas is achieved through the synergistic effect of the directional hydrogen introduction and circumferential porous uniform injection of the annular hydrogen injection mechanism, as well as the active turbulence at the throat, significantly improving the mixing uniformity. At the same time, combined with the low-resistance guiding and rectifying flow of the diffusion section, local high temperature, backfire and combustion oscillation are effectively suppressed, significantly reducing nitrogen oxide emissions and improving the stability and safety of the combustion system. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a fuel nozzle mixer suitable for a hydrogen mixed-fuel gas turbine according to an embodiment of the present disclosure.

[0018] In the diagram, 1 is the inlet section; 2 is the contraction section; 3 is the throat; 4 is the diffusion section; 5 is the outlet section; 6 is the annular hydrogen injection mechanism; 7 is the turbulence vane; and 8 is the arc-shaped guide vane. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] The embodiments of this application will be further described in detail below with reference to the accompanying drawings and examples. The detailed descriptions and accompanying drawings of the following embodiments are used to exemplarily illustrate the principles of this application, but should not be used to limit the scope of this application; that is, this application is not limited to the described embodiments. In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships 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 of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable error range. "Parallel" is not strictly parallel, but within the allowable error range.

[0021] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application depending on the specific circumstances.

[0022] like Figure 1 As shown, a fuel nozzle mixer suitable for hydrogen mixed fuel gas turbines includes an inlet section 1, a constriction section 2, a throat 3, a diffuser section 4, and an outlet section 5 arranged coaxially along the fluid flow direction.

[0023] The constriction section 2 is conical and gradually narrows along the fluid flow direction, with its outlet end connected to the throat 3. The throat 3 is configured as a cylindrical structure.

[0024] The diffuser section 4 is conical and gradually expands along the fluid flow direction. An annular hydrogen injection mechanism is fixed to the inner wall of the contraction section 2. A swirling and mixing mechanism is located inside the throat 3. A low-resistance guiding and rectifying mechanism is also located inside the diffuser section 4.

[0025] In this application, the efficient and deep mixing of hydrogen and gas is achieved through the synergistic effect of the directional hydrogen introduction and circumferential porous uniform injection of the annular hydrogen injection mechanism, as well as the active turbulence mechanism of the throat 3, which significantly improves the mixing uniformity. At the same time, combined with the low-resistance guiding and rectifying of the diffuser section 4, local high temperature, backfire and combustion oscillation are effectively suppressed, significantly reducing nitrogen oxide emissions and improving the stability and safety of the combustion system.

[0026] In some embodiments, the taper of the contraction section 2 is set between 30° and 45°. The taper of the diffusion section 4 is set between 20° and 30°.

[0027] In this application, this setting ensures smooth airflow acceleration and diffusion, avoids vortex separation, and reduces flow resistance.

[0028] In some embodiments, the annular hydrogen injection mechanism is configured as an annular hydrogen injection ring with 12 to 16 injection holes evenly distributed thereon, and the injection direction of all the injection holes is inclined toward the central axis of the throat 3.

[0029] In this application, the above-mentioned settings can achieve uniform circumferential coverage of hydrogen injection, avoid local agglomeration, and improve the initial mixing uniformity.

[0030] In some embodiments, a hydrogen delivery regulating mechanism is also included, which includes a hydrogen delivery pipe communicating with the annular hydrogen injection ring and a flow regulating valve installed in series on the hydrogen delivery pipe.

[0031] In this application, this setting allows for precise control of hydrogen flow rate based on operating conditions, adapting to various hydrogen blending ratios and improving operational flexibility.

[0032] In some embodiments, the swirling mixing mechanism includes 3 to 4 turbulence blades, which are evenly distributed in a circumferential array along the throat 3, and each turbulence blade is inclined at 30° to 45° relative to the axial flow direction of the mixer.

[0033] In this application, the setting can actively break laminar flow to generate turbulent shear, enhance momentum exchange, and achieve rapid deep mixing.

[0034] In some embodiments, the root of the deflector blade is integrally fixed to the inner wall of the throat 3.

[0035] In some embodiments, the low-resistance guiding and rectifying mechanism includes 2 to 3 arc-shaped guide plates that extend along the generatrix direction of the diffuser section 4 and are arranged to conform to the conical inner wall surface of the diffuser section 4.

[0036] In this application, the setting can regulate residual swirling flow and near-wall eddy current, suppress backflow loss, and achieve low-resistance rectification and homogenization.

[0037] In some embodiments, the curvature of the arc-shaped guide plate matches the curvature of the inner wall of the diffuser section 4, and the arc-shaped guide plate is configured as a low-profile, wall-mounted protrusion structure and distributed in the near-wall boundary layer region of the pipe.

[0038] In this application, the flow is rectified close to the boundary layer, which can effectively eliminate near-wall eddies and further reduce flow resistance losses.

[0039] In some embodiments, when there are two arc-shaped guide vanes, the two arc-shaped guide vanes are symmetrically distributed at 180°. When there are three arc-shaped guide vanes, the three arc-shaped guide vanes are circumferentially distributed at 120° intervals.

[0040] In this application, the configuration allows the arc-shaped guide vanes to be circumferentially and symmetrically distributed, ensuring balanced flow field rectification, avoiding flow deviation, and improving outlet uniformity.

[0041] In some embodiments, the mixer is configured as an axisymmetric, monolithic tubular structure.

[0042] This application provides a fuel nozzle mixer suitable for hydrogen-fueled gas turbines, which is an axisymmetric, integrated tubular structure. Along the fluid flow direction, it is coaxially arranged with an inlet section 1, a contraction section 2, a throat 3, a diffuser section 4, and an outlet section 5. The mixer includes a three-stage fluid channel (contraction-throat 3-diffusion) for generating a Venturi negative pressure guiding effect, an annular hydrogen injection mechanism conforming to the inner wall of the contraction section 2, a swirling turbulence mixing mechanism located in the throat 3, a low-resistance guiding and rectifying mechanism located in the diffuser section 4, and a precisely controllable hydrogen delivery regulating mechanism.

[0043] The contraction section 2 adopts a tapered, tapered structure design, with its outlet end connecting to the throat 3. The inner diameter is contracted, and the overall taper is controlled between 30° and 45°. This taper design ensures smooth acceleration of the main airflow (air / natural gas) without boundary layer separation, while forming a stable negative pressure zone in the throat 3, providing a stable power source for the passive flow of hydrogen.

[0044] The inner wall of the contraction section 2 is designed to be smooth without any protrusions, in order to minimize the basic resistance of the main airflow. An annular hydrogen injection mechanism 6 is fixedly attached to the inner wall of the contraction section 2, specifically an annular hydrogen injection ring (as shown in Figure 1). The annular hydrogen injection ring is completely attached to the inner wall of the contraction section 2 and arranged coaxially without any gaps or protrusions, so as to avoid interfering with the flow field of the main airflow.

[0045] Furthermore, the annular hydrogen injection ring has 12 to 16 nozzles evenly distributed on its ring body. All nozzles are evenly arrayed circumferentially, and the injection direction of all nozzles is inclined towards the central axis of the throat 3. A hydrogen delivery pipe is connected and fixed to the outside of the annular hydrogen injection ring. The pipe passes through the outer wall of the mixer and is sealed to ensure airtightness. A flow regulating valve is installed in series on the hydrogen delivery pipe, which can precisely adjust the hydrogen injection flow rate according to the unit's operating load and preset hydrogen blending ratio, adapting to various operating conditions such as pure air, natural gas, low hydrogen blending, and high hydrogen blending.

[0046] Furthermore, based on the Venturi negative pressure effect, hydrogen is directionally injected into the high-speed, low-pressure throat region 3 through circumferentially distributed micro-nozzles, achieving full circumferential coverage and uniform injection of hydrogen into the main gas flow. This avoids hydrogen agglomeration caused by localized concentrated injection, thereby improving the initial mixing uniformity from the source. The throat 3 is a cylindrical straight-through structure, coaxially connected to the outlet of the contraction section 2 and the inlet of the diffuser section 4. The throat 3 is the core region of the Venturi effect, where the airflow velocity reaches its peak and the negative pressure intensity is the highest. It is the core region for hydrogen mixing and provides a stable flow field basis for subsequent turbulence-enhanced mixing. Three to four turbulence blades 7 are fixedly installed inside the throat 3. The turbulence blades 7 are evenly arrayed along the circumference of the throat 3, and the root of the blades is integrally fixed to the inner wall of the throat 3. The turbulence blades 7 are inclined at 30° to 45° relative to the axial flow direction of the mixer.

[0047] In this application, the inclined arrangement of the turbulence-disrupting blades 7 can actively turbulentize the high-speed main airflow and the injected hydrogen-gas mixture, breaking the laminar flow state and forcibly generating small-amplitude swirling and turbulent shearing effects. This significantly improves the momentum exchange and mass diffusion efficiency between hydrogen, air, and natural gas, achieving rapid and deep mixing. At the same time, the lightweight design with fewer blades and a smaller width can effectively reduce the structural blockage ratio and control pressure loss.

[0048] The diffuser section 4 adopts a tapered, gradually expanding structure, with its diffusion taper controlled between 20° and 30°. The gentle diffusion taper avoids eddies and backflow phenomena caused by rapid diffusion of high-speed airflow, reducing energy loss during diffusion and providing structural support for low-drag operation. Two to three arc-shaped guide vanes 8 are uniformly fixed to the inner wall of the diffuser section 4. Each arc-shaped guide vane 8 is a long, thin, arc-shaped blade extending along the generatrix of the diffuser section 4. The arc-shaped guide vanes 8 are arranged to fit snugly against the curved surface of the tapered inner wall of the diffuser section 4, with the surface curvature perfectly matching the curvature of the inner wall, forming a conformal arc structure.

[0049] The arc-shaped guide vane 8 starts from the inlet end of the diffuser section 4 and extends axially to the outlet end of the diffuser section 4, completely covering the fluid flow area of ​​the diffuser section 4. The arc-shaped guide vane 8 is radially protruding, designed as a low-profile, wall-hugging protrusion structure, and distributed in the near-wall boundary layer region of the pipe, without intruding into the main flow area in the center of the pipe, and will not cause obstruction or impact resistance to the main airflow. The arc-shaped guide vanes 8 are evenly arranged circumferentially, with two guide vanes symmetrically distributed at 180°, and three guide vanes equally divided circumferentially at 120°, with smooth surfaces without sharp edges or structural abrupt changes.

[0050] The low-profile arc-shaped guide vane 8 can specifically constrain and regulate the micro-swirling flow and near-wall separated vortex residual in the throat 3 turbulence blades, suppress boundary layer wall detachment, backflow and secondary flow loss during the diffusion process, and achieve flow field rectification and homogenization without increasing friction drag.

[0051] The tilted turbulence-inducing blades 7 at the throat 3 are arranged in the main flow zone at the center of the pipe, achieving deep mixing of hydrogen and gas through moderate turbulent shearing. The low-profile, wall-mounted arc-shaped guide vanes 8 in the diffuser section 4 are arranged in the near-wall region, focusing on rectifying and optimizing turbulence, swirl, and boundary layer losses. The two sections work separately and complement each other, forming a coupled structure of "high-efficiency mixing at the center and low-resistance rectification near the wall," which completely solves the technical contradiction that "intensified mixing inevitably leads to high resistance" in the overall turbulence-inducing structure of traditional mixers.

[0052] The main gas flow (air or natural gas) enters the mixer through the inlet, gradually accelerating in the contraction section 2, where the gas velocity gradually increases and the static pressure gradually decreases, forming a stable negative pressure zone in the throat region 3. Hydrogen, after being pressurized and metered by the delivery pipe and flow regulating valve, enters the annular hydrogen injection mechanism 6, and is directionally injected into the core flow field of the throat 3 through circumferentially distributed micro-nozzles. Utilizing the Venturi negative pressure entrainment effect, the hydrogen is rapidly entrained and initially mixed by the high-speed main gas flow. Subsequently, the mixed gas flow passes through the inclined turbulence blades 7 in the throat 3, breaking the laminar flow and generating stable turbulence and micro-swirls, achieving deep and rapid mixing of hydrogen and the main gas flow. Finally, the turbulent mixture enters the diffuser section 4, where it is rectified and regulated by the arc-shaped guide plate 8, eliminating flow eddies and energy loss, and after stable diffusion, is uniformly output from the outlet, completing a low-resistance, high-efficiency premixing process.

[0053] This application combines a triple mixing mechanism of Venturi negative pressure directional hydrogen introduction, circumferential multi-orifice full-coverage injection, and three tilted turbulence blades and seven active turbulence in the throat. It enhances mixing from multiple dimensions such as hydrogen injection, airflow disturbance, and mass diffusion, and completely solves the problems of hydrogen stratification and local enrichment in traditional mixers. The uniformity of hydrogen-gas mixing is greatly improved, effectively suppressing problems such as local high temperature, backfire, and combustion oscillation in combustion, reducing nitrogen oxide pollutant emissions, and improving the stability of the combustion system.

[0054] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A fuel nozzle mixer suitable for hydrogen-fueled gas turbines, characterized in that, include: The inlet section, constriction section, throat, diffuser section, and outlet section are arranged coaxially along the direction of fluid flow. The constriction section is conical and gradually narrows along the fluid flow direction, with its outlet end connected to the throat. The throat is configured as a cylindrical structure; The diffusion section is conical and gradually expands along the direction of fluid flow; An annular hydrogen injection mechanism is fitted and fixed to the inner wall of the contraction section; A swirling and turbulent mixing mechanism is disposed inside the throat. as well as, A low-resistance flow guiding and rectifying mechanism is disposed inside the diffuser section.

2. The fuel nozzle mixer according to claim 1, characterized in that, The taper of the contraction section is set between 30° and 45°; the taper of the diffusion section is set between 20° and 30°.

3. The fuel nozzle mixer according to claim 1 or 2, characterized in that, The annular hydrogen injection mechanism is configured as an annular hydrogen injection ring, on which 12 to 16 injection holes are evenly opened, and the injection direction of all the injection holes is inclined towards the central axis of the throat.

4. The fuel nozzle mixer according to claim 3, characterized in that, It also includes a hydrogen delivery regulating mechanism, which includes a hydrogen delivery pipe connected to the annular hydrogen injection ring, and a flow regulating valve installed in series on the hydrogen delivery pipe.

5. The fuel nozzle mixer according to claim 1 or 2, characterized in that, The swirling mixing mechanism includes 3 to 4 turbulence blades, which are evenly distributed in a circumferential array along the throat, and each turbulence blade is inclined at 30° to 45° relative to the axial flow direction of the mixer.

6. The fuel nozzle mixer according to claim 5, characterized in that, The root of the turbulence blade is integrally fixed to the inner wall of the throat.

7. The fuel nozzle mixer according to claim 1 or 2, characterized in that, The low-resistance flow guiding and rectifying mechanism includes 2 to 3 arc-shaped flow guide plates, which extend along the generatrix direction of the diffuser section and are arranged to fit the conical inner wall curved surface of the diffuser section.

8. The fuel nozzle mixer according to claim 7, characterized in that, The curvature of the arc-shaped guide plate matches the curvature of the inner wall of the diffuser section, and the arc-shaped guide plate is configured as a low-profile, wall-mounted protrusion structure and distributed in the near-wall boundary layer region of the pipe.

9. The fuel nozzle mixer according to claim 7, characterized in that, When there are two arc-shaped guide vanes, the two arc-shaped guide vanes are symmetrically distributed at 180°; when there are three arc-shaped guide vanes, the three arc-shaped guide vanes are circumferentially distributed at 120° intervals.

10. The fuel nozzle mixer according to claim 1, characterized in that, The mixer is configured as an axisymmetric, integrated tubular structure.

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