CN215675303U

CN215675303U - Premixing fuel nozzle of gas turbine

Info

Publication number: CN215675303U
Application number: CN202121770869.6U
Authority: CN
Inventors: 王彤; 胡宏斌; 姜磊; 王博涵; 姜向禹; 陈溯敏
Original assignee: Institute of Engineering Thermophysics of CAS
Current assignee: Institute of Engineering Thermophysics of CAS
Priority date: 2021-07-30
Filing date: 2021-07-30
Publication date: 2022-01-28
Anticipated expiration: 2031-07-30

Abstract

The utility model provides a premixed fuel nozzle of a gas turbine, which comprises a central cone, a first-stage swirler, a second-stage swirler, a nozzle shell and an air collecting cavity, wherein the central cone, the first-stage swirler, the second-stage swirler, the nozzle shell and the air collecting cavity are sequentially arranged from inside to outside; the central cone, the first stage swirler, the second stage swirler, and the nozzle housing are coaxially disposed. The premixed fuel nozzle of the gas turbine, provided by the utility model, has the advantages of simple and reasonable structure, good universality, clean combustion, low pollution and very wide application.

Description

Premixing fuel nozzle of gas turbine

Technical Field

The utility model belongs to the field of gas turbines, and particularly relates to a premixed fuel nozzle of a gas turbine.

Background

The nozzle is an important working component of the combustion chamber of the gas turbine, and fuel is supplied into the combustion chamber of the gas turbine through the nozzle during the working process and is mixed with air in the combustion chamber and combusted. In the design of gas fuel nozzles, there is a continuing need for improved designs and configurations to achieve more stable, reliable, and well-performing products. In the process, the performance of fuel nozzles with different structures and types needs to be detected so as to obtain key parameters such as combustion characteristics and pollutant emission levels of the fuel nozzles, and reference is provided for retrofit design.

Compared with solid and liquid fuels such as coal, petroleum and the like, the gas fuel not only can be combusted more fully and completely, the maximum utilization of energy is ensured, but also pollutants generated by combustion are less, and the influence on the environment is lower. Under the national policy of energy conservation and emission reduction, the gas fuel plays an increasingly important role. At present, the gas fuel is widely applied to the fields of power driving, power generation and heat supply, petrochemical industry, building materials, machining, food industry and the like. The gaseous fuel is generally fed to the combustion chamber for combustion through a nozzle, where it undergoes a blending and rectifying process to form a homogeneous premixed gas at the outlet, thereby achieving complete combustion and low pollutant emissions.

The traditional gas turbine generally adopts a diffusion combustion mode to organize combustion, and the combustion chamber can not ensure the uniform mixing of fuel and air, so the pollutant emission, especially the emission of nitrogen oxides, is high. The lean premixed combustion mode can effectively reduce the emission of nitrogen oxides in the combustion process, and is a clean combustion mode.

The single lean premixed combustion is very easy to generate the phenomena of combustion chamber thermoacoustic oscillation, combustion instability and even flameout due to low combustion equivalent, and meanwhile, the premixed combustion flame is fast in propagation speed, so that the head of the nozzle is easy to burn down due to backfire of the combustion chamber, and serious accidents are caused. Therefore, there is a need for a nozzle that can pre-mix fuel and air, and form a fuel-air mixture at a certain velocity and uniform mixing at the nozzle outlet, and then enter the flame tube for combustion. However, since the fuel injected from the premixing nozzle is burned in the combustion chamber in the form of premixed flame, in order to achieve extremely low pollutant emission, the flame works near the combustible boundary and the jet velocity of the fuel-air mixed gas injected from the nozzle is high, so that reliable ignition of the combustion chamber is difficult.

Therefore, it is necessary to provide a gas fuel nozzle that can sufficiently burn a gas fuel structure and has a low fuel utilization rate.

Disclosure of Invention

In order to solve the problems, the utility model aims to provide a premixed fuel nozzle of a gas turbine, which is used for solving the problems of insufficient combustion of gas fuel organization, low fuel utilization rate and serious pollution of the existing nozzle.

In order to achieve the purpose, the technical scheme adopted by the utility model is as follows:

the premixing fuel nozzle of the gas turbine comprises a central cone, a first-stage swirler, a second-stage swirler, a nozzle shell and a gas collection cavity which are sequentially arranged from inside to outside; the central cone, the first stage swirler, the second stage swirler, and the nozzle housing are coaxially disposed.

The premixing fuel nozzle of the gas turbine is also characterized in that the central cone is a hollow cavity, and the front end of the central cone is provided with a convergent-divergent nozzle.

The gas turbine premix fuel nozzle provided by the present invention is also characterized in that the primary swirler comprises a plurality of primary swirler vanes forming a plurality of primary air passages with the central cone.

The gas turbine premix fuel nozzle provided by the utility model is also characterized in that the number of the swirl vanes is five.

The gas turbine premixing fuel nozzle provided by the utility model is also characterized in that the first-stage swirler is also provided with a flow guide cover plate arranged on the outer side of the first-stage swirl vanes, and the flow guide cover plate is of a short annular structure.

The premixing fuel nozzle of the gas turbine is also characterized in that the second-stage swirler comprises a plurality of second-stage swirl vanes, and the number of the second-stage swirl vanes is twice that of the first-stage swirl vanes; the second-stage swirl blades and the first-stage swirl blades have opposite swirl directions.

The premixing fuel nozzle of the gas turbine is also characterized in that a fuel channel is arranged in the secondary swirl vane; and a plurality of fuel injection holes are formed in the surface of the secondary swirl vane.

The gas turbine premix fuel nozzle provided by the utility model is also characterized in that the number of the injection holes is three.

The utility model also provides a premixing fuel nozzle of a gas turbine, which is characterized in that a second-stage air channel is formed between the nozzle shell and the second-stage swirler; the nozzle housing tapers forwardly along an axis to a flare.

The premixing fuel nozzle of the gas turbine is also characterized in that a gas supply connector used for storing natural gas fuel is arranged outside the gas collection cavity.

Has the advantages that:

the central cone in the premixed fuel nozzle of the gas turbine effectively forms guide airflow, prevents the airflow from forming a wall surface attachment layer on the inner wall of the nozzle or staying in the premixing section for a long time to form standing vortex, and effectively prevents tempering and flame holding phenomena.

The gas turbine premixing fuel nozzle provided by the utility model can ensure the uniform flow distribution of each fuel injection hole and the uniformity of subsequent mixing through the design of the gas collecting cavity and the fuel injection holes.

The premixed fuel nozzle of the gas turbine, provided by the utility model, has the advantages of simple and reasonable structure, good universality, clean combustion, low pollution and very wide application.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a cross-sectional plan view of a premix fuel nozzle for a gas turbine provided in accordance with an embodiment of the present invention;

FIG. 2 is a perspective cross-sectional view of a premix fuel nozzle for a gas turbine provided in an embodiment of the utility model;

wherein: 1. a central cone; 2: a first stage swirl vane; 3: a draft shield plate; 4: a secondary swirl vane; 5: a nozzle housing; 6: a gas collection cavity; 7: a fuel delivery conduit; 8: a fuel injection hole; 9: the air supply connector.

Detailed Description

In order to make the technical means, the original features, the achieved objects and the effects of the present invention easily understood, the following embodiments are specifically described with reference to the attached drawings.

In the description of the embodiments of the present invention, it should be understood that the terms "central", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only used for convenience in describing and simplifying the description of the present invention, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit to a number of indicated technical features. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the utility model, the meaning of "a plurality" is two or more unless otherwise specified.

The terms "mounted," "connected," and "coupled" are to be construed broadly and may, for example, be fixedly coupled, detachably coupled, or integrally coupled; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the creation of the present invention can be understood by those of ordinary skill in the art through specific situations.

1-2, a gas turbine premix fuel nozzle is provided. The nozzle comprises a central cone 1, a first-stage swirler, a second-stage swirler, a nozzle shell 5 and an air collecting cavity 6 which are arranged from inside to outside in sequence; the central cone 1, the first stage swirler, the second stage swirler and the nozzle housing 5 are coaxially arranged. The central cone 1 is a hollow cavity, and the front end of the central cone 1 is provided with a retractable nozzle.

In the above embodiment, the hollow cavity is a cooling channel, and the central cone 1 can effectively guide the air flow, so as to prevent the air flow from forming a wall surface adhesion layer on the inner wall of the nozzle or from forming standing vortex when the air flow stays in the premixing section for a long time, and effectively generate the phenomena of wall surface tempering and flame holding. Under a low working condition, natural gas is supplied into the hollow cavity, and an on-duty flame is formed outside the nozzle to maintain the combustion stability; under high working conditions, cooling air is supplied into the hollow cavity and used for cooling the wall surface of the nozzle, so that the temperature distribution of flame in the nozzle can be adjusted, the excessive high discharge of NOx is prevented, nozzle components can be cooled, and the head part of the combustion chamber is prevented from being damaged by high temperature.

In some embodiments, the first stage swirler includes 5 first stage swirl vanes 2, and 5 first stage air passages are formed between the first stage swirl vanes 2 and the central cone 1 to generate swirl air. The first-stage swirler is also provided with a flow guide cover plate 3 arranged on the outer side of the first-stage swirler vanes 2, and the flow guide cover plate 3 is of a short annular structure. The second-stage cyclone comprises 10 second-stage cyclone blades 4, and the number of the second-stage cyclone blades 4 is twice that of the first-stage cyclone blades 2; the second-stage swirl blades 4 and the first-stage swirl blades 2 have opposite directions of rotation. A fuel channel is arranged in the second-stage rotational flow blade 4; the surface of the second-stage swirl vane 4 is provided with 3 fuel injection holes 8.

In the above embodiment, the second stage swirl blades 4 and the first stage swirl blades 2 have opposite rotation directions, and two high-speed air swirls can be generated by the two stage swirl blades with opposite rotation directions, and a swirl shear layer is formed at the interface of the two stage swirl blades, so that fuel micro-clusters are dispersed by shear force, and the mixing of fuel and air is enhanced. The design of the double-stage reverse rotation swirler and the proper ratio of the first-stage rotational flow vanes and the second-stage rotational flow vanes can form a strong shearing layer, break up gas micro-clusters, ensure uniform mixing, ensure the stability of combustion flame at the outlet of the nozzle and reduce the discharge amount of NOx.

In some embodiments, a second stage air passage is formed between the nozzle housing 5 and the second stage swirler; the nozzle housing 5 tapers forwardly along an axis to a flare. And a gas supply connector 9 for storing natural gas fuel is arranged outside the gas collection cavity 6. The gas supply connector 9 is connected with a natural gas pipeline, natural gas fuel enters the gas collecting cavity 6 through the connector, then reaches the fuel injection hole 8 along the fuel conveying pipeline 7 in the secondary swirl vane 4, and is injected into swirl air through the fuel injection hole 8.

In the embodiment, the trumpet-shaped closing-in of the outlet part of the nozzle can improve the speed distribution of mixed gas in the premixing section, generate steady flow and rectification effects on outlet airflow and ensure the uniform mixing of fuel gas and air.

The operation principle of the premixing fuel nozzle of the gas turbine is as follows:

when the gas turbine works under low working condition (less than or equal to 20 percent), the natural gas fuel is supplied into the combustion chamber in two paths. The fuel of the main combustion path is supplied into the gas collecting cavity 6 from the pipeline, then reaches the fuel injection hole 8 along the fuel conveying pipeline 7 in the secondary swirl vane 4, and is uniformly injected into the high-speed strong swirl air outside through the fuel injection hole 8. The natural gas fuel finishes the processes of crushing, atomizing and mixing in the air through the shearing action of the first-stage rotational flow and the second-stage rotational flow, is rectified by the trumpet-shaped closing-up at the front part of the nozzle, forms mixed gas with uniform mixing and regular flow field at the outlet of the nozzle, and is supplied into the combustion chamber for premixed combustion. The fuel of the secondary combustion path is directly sprayed into the combustion chamber through the central cavity, and a diffusion on-duty flame is formed at the outlet of the nozzle, so that stable combustion is facilitated, and meanwhile, the combustion temperature is increased to reduce thermoacoustic oscillation.

When the gas burner works under high working conditions (more than 20%), natural gas fuel is not fed into the central cavity any more to form on-duty flame, fuel is only fed into the main combustion path, and uniform premixed fuel gas is formed through the rotational flow shearing action of the rotational flow blades of the nozzle and is supplied for combustion. Cooling air is introduced into the central cavity to help cool the nozzle walls and prevent high temperatures from damaging the nozzle components.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the utility model, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention. The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.

Claims

1. The premixing fuel nozzle of the gas turbine is characterized by comprising a central cone, a first-stage swirler, a second-stage swirler, a nozzle shell and a gas collection cavity which are sequentially arranged from inside to outside; the central cone, the first stage swirler, the second stage swirler, and the nozzle housing are coaxially disposed.

2. The gas turbine premix fuel nozzle as in claim 1, wherein said center cone is a hollow cavity, and wherein said center cone has a convergent-divergent nozzle at a forward end thereof.

3. The gas turbine premix fuel nozzle of claim 1, wherein the first stage swirler comprises a plurality of first stage swirler vanes forming a plurality of first stage air passages with the center cone.

4. The gas turbine premix fuel nozzle of claim 3, wherein said swirler vanes are five.

5. The gas turbine premix fuel nozzle of claim 3, wherein said primary swirler is further provided with a deflector plate disposed outboard of the primary swirler vanes, said deflector plate being of short annular configuration.

6. The gas turbine premix fuel nozzle of claim 3, wherein the second stage swirler comprises a plurality of second stage swirler vanes twice as many as the first stage swirler vanes; the second-stage swirl blades and the first-stage swirl blades have opposite swirl directions.

7. The gas turbine premix fuel nozzle of claim 6, wherein a fuel passage is provided in said secondary swirler vane; and a plurality of fuel injection holes are formed in the surface of the secondary swirl vane.

8. The gas turbine premix fuel nozzle of claim 7, wherein said injection orifices are three.

9. The gas turbine premix fuel nozzle of claim 1, wherein a second stage air passage is formed between said nozzle housing and said second stage swirler; the nozzle housing tapers forwardly along an axis to a flare.

10. The gas turbine premix fuel nozzle of claim 1, wherein a gas supply nipple for storing natural gas fuel is provided outside the plenum.