JPH07332621A - Swirl burner for gas turbine combustion device - Google Patents

Abstract

PURPOSE:To provide a turning burner for a gas turbine combustion device in which its configuration is simple, a flame blowing-off state or the like can be prevented and a flame stability can be improved. CONSTITUTION:A circular swirl burner 1 for a gas turbine combustion device is constructed such that a dispersion fuel nozzle 3 having a plurality of holes at its central part is installed, and a plurality of swirling vanes 2 are installed in a circumferential direction toward an outer circumference of the swirl burner 1 from the dispersion fuel nozzle 3. In addition, the swirling vanes 2 are twisted from the central part toward an outer circumferential part and its swirling angle is varied. Due to this fact, the vanes 2 are constructed such that the central swirling angle 4 high at the central part is provided and an outer circumferential swirling angle 5 weak at the outer periphery is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine combustor, and more particularly to a swirl burner suitable for stably holding a flame.

[0002]

2. Description of the Related Art A conventional gas turbine combustor employs a premixed combustion system in which a fuel (for example, methane) and air are premixed and burned in order to reduce NOx in exhaust gas. Compared to the diffusion combustion method in which the fuel and air are separated and burned, the premixed combustion method can reduce the fuel concentration and lower the flame temperature, so the amount of NOx generated in the exhaust gas is small. In the premixed combustion system, a premixer for premixing fuel and air is provided upstream of the combustion chamber. Further, a flame stabilizer for stably burning the premixed gas of fuel and air flowing out from the premixer is required.

As a fire protection system, a system in which a pilot flame by diffusion combustion is used as an ignition source to stably burn a premixed air mixture, or a premixed airflow is swirled to generate a backflow in the vicinity of a central axis of the swirl, There is a method in which a high temperature burnt gas is retained by a reverse flow and the premixed gas is stably burned using this as an ignition source.

As conventional combustors, JP-A-2-93210, JP-A-2-23390, JP-A-1-9203809, JP-A-59-195011, and JP-A-54-159741 are known. There is one described in the publication.

[0005]

In order to stably hold the flame in the system using the swirl flow, the backflow rate is increased so that the high-temperature burned gas is always supplied from the flame region to the backflow region. In addition, it is important to suppress the fluctuation of the backflow as much as possible in order to prevent blowout of the flame.

In the above conventional technique, a stagnation region where the velocity becomes zero is generated in the vicinity of the central axis of the backflow generated by the action of swirling. This stagnation region could cause the flame to blow out, possibly deteriorating the stability of the flame.

In the case of a structure in which a plurality of swirl vanes having different swirl angles in the radial direction are used to change the swirl strength in the radial direction to reduce the stagnation area and improve flame stability, the swirl vanes are fixed. The manufacturability is complicated and it is difficult to downsize the burner.

An object of the present invention is to provide a swirl burner for a gas turbine combustor, which suppresses blowout of flame as much as possible, has excellent flame stability, and is excellent in manufacturability.

[0009]

In order to achieve the above object, in a swirl burner used in a gas turbine combustor,
The swirl burner is provided with a plurality of swirl vanes in the circumferential direction as a means for swirling air or premixed gas in the circumferential direction. This is a swirl burner that is changed in the radial direction from the central portion. A means for injecting fuel for forming a diffusion flame is provided at the center of the swirl burner.

Further, means for injecting fuel upstream or downstream of the swirl burner is provided so that the fuel and air can be mixed by utilizing the swirl flow of the swirl burner and the shear due to the difference in axial speed in the radial direction of the burner. This is the turning burner.

Further, means for injecting air into the vicinity of the central portion upstream or downstream of the swirl burner and means for injecting fuel to the outer peripheral portion thereof are provided, and the fuel and the outer periphery thereof are arranged from the center in the radial direction of the swirl burner. The swirl burner is designed to inject air from a portion and premixed gas from an outer peripheral portion.

[0012]

According to the structure of the swirl burner of the present invention, the means for generating swirl flows having different swirl strengths in the radial direction by twisting one swirl vane in the burner radial direction is realized by the swirl action of the outer peripheral portion. The generated backflow region can be expanded to the vicinity of the central axis, and the stagnation region near the central axis, which causes blowout of the flame and the like, can be reduced. Therefore, it is possible to stabilize the high-temperature backflow near the central axis, prevent blowout of the flame, and improve the stability of the flame. When premixed gas is injected from the downstream of the swirl burner to perform premixed combustion,
By means of injecting fuel provided in the center of the swirl burner,
A diffusion flame can be formed in the center of the burner due to the reaction between residual oxygen from premixed combustion and fuel, and premixing / diffusion mixed combustion becomes possible.
Furthermore, the stability of the flame can be improved. Further, according to the present invention, the swirl strength can be changed by one swirl vane in the burner radial direction, the manufacturability is excellent, and the burner can be easily downsized.

Further, if the structure is provided with means for injecting fuel upstream or downstream of the swirl burner, in addition to the mixing of air and fuel by the swirl flow, the axial direction based on the difference in swirl angle between the central portion and the outer peripheral portion of the burner. A shear flow is generated due to the difference in flow velocity, the mixing of air and fuel can be promoted, and a premixed gas with a high degree of mixing can be created.

Further, when the structure is provided with means for injecting air into the vicinity of the central axis upstream or downstream of the swirl burner and means for injecting fuel to the outside of the swirl burner, the fuel is at the center of the swirl burner, and the air is at the outer periphery thereof. In addition, a premixed gas can be ejected to the outer periphery, a diffusion flame due to the reaction of air and fuel can be formed in the center, and a premixed flame due to the reaction of the lean premixed gas can be formed at the outer periphery, thus premixing and diffusion mixed combustion It becomes possible to improve the stability of the flame and to reduce NOx.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, 1 is a swirl burner, 2 is a swirl vane, 3 is a diffusion fuel nozzle having one or more holes, 4
Is the central swivel angle of the swirl blade 2, and 5 is the outer circumferential swirl angle of the swirl blade 2. Further, in FIG. 2, reference numeral 6 is a turning burner 1.
Is a low-speed air flow flowing through the central portion of the swirl burner. Furthermore, in FIG.
Is a diffusion fuel flow injected from the diffusion fuel nozzle 3, 9 is a combustion chamber, 10 is a diffusion flame formed by the reaction of the fuel flow with the low-speed air flow 6 or the high-speed air flow 7, and 11 is the swirl of the swirl burner 1. The central circulation flow formed by the swirl flow based on the central swirl angle 4 of the blades 2 and the outer peripheral circulation flow 12 formed by the swirl flow based on the outer swirl angle of the swirl vanes 2 of the swirl burner 1. The swirl burner 1 has a diffusion fuel nozzle 3 at its center, and swirl vanes 2 are connected to the diffusion fuel nozzle 3 and the outer peripheral portion of the swirl burner 1. A plurality of swirl vanes 2 are arranged in the circumferential direction. Also, the swirl blade 2
Is partially twisted in the radial direction from the central portion of the swirl burner 1 toward the outer peripheral portion thereof, and the swivel angle is different between the central portion and the outer peripheral portion. Therefore, the swirl burner 1 has a swirl angle 4 at the center and a swivel angle 5 at the outer periphery. In the present invention, the central turning angle 4 of the turning burner 1 is larger than the outer turning angle 5. Therefore, a strong swirl flow is generated inside the swirl burner 1 and a weak swirl flow is generated outside. In addition, the resistance coefficient based on the turning angle differs between the central part and the outer peripheral part, and the turning burner 1
The velocity of the air flowing through the inside is different inside and outside. Generally, the magnitude of the turning angle is proportional to the magnitude of the resistance coefficient based on it. That is, the larger the turning angle, the larger the resistance coefficient. As a result, as shown in FIG. 2, the low speed airflow 6 flows through the central portion of the swirl burner 1 and the high speed airflow 7 flows through the outer peripheral portion thereof. An example of combustion using the swirl burner 1 according to the present invention is shown in FIG. The air flowing into the swirl burner 1 becomes a low speed air flow 6 in the axial direction of the strong swirl in the central portion by the swirl vanes 2 and flows out to the combustion chamber 9. Similarly, at the outer peripheral portion, a high-speed airflow 7 is formed in the axial direction of the weak swirl, and flows out into the combustion chamber 9.
In general, when the swirling flow is discharged to the expansion flow path, the flow velocity in the axial direction decreases with the expansion, and the dynamic pressure decreases. Therefore, the static pressure is restored, and a region where the static pressure becomes higher locally on the downstream side is generated, and a backflow occurs there. In the case of a swirling flow, since the swirling component becomes zero at the central axis due to the rigid vortex motion, it is said that this backflow occurs near the central axis and a circulating flow is formed. Therefore, according to the present invention, the central circulation flow 11 is generated by the strong rotation of the central portion, and the outer circulation flow 12 is generated by the weak rotation of the outer peripheral portion. Also, the diffusion fuel flow 8
Is a combustion chamber 9 from an injection hole provided on the entire surface of the diffusion fuel nozzle 3.
Spill to. Therefore, the low-speed air flow 6 and the high-speed air flow 7 and the diffusion fuel flow 8 meet in the combustion chamber 9 and diffuse combustion, and a diffusion flame 10 is generated. Once the diffusion flame 10 is formed, the high temperature burned gas is stagnated in the central circulation flow 11 and the peripheral circulation flow 12, and the diffusion flame 10 is retained. Like this, 2
The central circulation flow 11 and the outer circulation flow 12 can prevent the backflow velocity near the central axis from decreasing and reduce the stagnation region, thereby improving the stability of the diffusion flame 10. Further, when manufacturing a burner used for a combustor, it is necessary to withstand high-temperature and high-pressure conditions, so that all joints are generally welded. According to the invention, one swirl vane 2 in the radial direction
Therefore, when the swirl vane 2 is fixed, it is sufficient to weld the diffusion fuel nozzle 3 on the inner side and the outer peripheral portion of the swirl burner 1 at two locations. Therefore, there is an effect that the swivel burner can be easily manufactured. Here, diffusion combustion is taken as an example, but premixed combustion is also possible if a premixed gas mixture of air and fuel is introduced from the upstream of the swirl burner 1 instead of air.
At that time, if a small amount of the diffusion fuel flow 8 is introduced from the diffusion fuel nozzle 3, the fuel reacts with the residual oxygen of the premixed combustion to form a diffusion flame inside the premixed flame. Mixed burning is also possible. In this case, the presence of the diffusion flame improves the propagation characteristics of the premixed flame and improves the stability of the premixed flame.

4 and 5 show a modification of the swirl vane 2 of the present invention. In FIG. 4, 13 is a notch provided in the swirl vane 2. Further, in FIG. 5, reference numeral 14 denotes a joining portion between the central swirl vane 2-1 and the outer peripheral swirl vane 2-2.
As shown in FIG. 4, a notch 13 is provided between the central portion and the outer peripheral portion of the swirl blade 2 where the swirl angle changes so that the central portion and the outer peripheral portion of the swirl blade 2 can be easily twisted. It is a structure. As a result, one swirl vane 2 is provided in the radial direction.
Thus, the turning angle can be easily changed. Further, according to FIG. 5, a plurality of swirl vanes 2-1 and 2 having different swivel angles in advance.
-2 is prepared and joined by welding. As a result, the swirl vane 2 can be made to have a single structure by the joining portion 14. According to this method, it is not necessary to twist the swirl vanes 2, so that stress concentration due to bending can be avoided.

FIG. 6 shows another embodiment. In FIG.
Reference numeral 15 is a cylindrical premixer, 16 is a premixed fuel nozzle for injecting fuel into the premixer 15, 17 is a premixed fuel flow injected from the premixed fuel nozzle, and 18 is a reaction of the lean premixed gas. It is a premixed flame that is formed. The premix fuel nozzle 16 is arranged upstream or downstream of the swirl burner 1. In FIG. 6, the case where it is arranged downstream is taken as an example. The air that has flowed into the swirl burner 1 flows out to the premixer 15 by the swirl vanes 2 as a low-speed air flow 6 in the axial direction of strong swirl in the central portion and as a high-speed air flow 7 in the axial direction of swirl weaker than the outer peripheral portion. . On the other hand, the premixed fuel flow 17 flows out from the premixed fuel nozzle 16 to the premixer 15. Therefore, in the premixer 15, the air and the fuel are mixed by swirling. Furthermore, turbulence is generated by the shear flow based on the speed difference between the low-speed air flow 6 at the center of the swirl burner 1 and the high-speed air flow 7 at the outer periphery, and mixing of air and fuel can be promoted. The premixed gas created in the premixer 15 is ejected from the tip of the premixer into the combustion chamber 9, and a premixed flame 18 is formed by the reaction of the premixed gas. Further, in the case of the structure of the present invention, since the diffusion fuel nozzle 3 has a length up to the outlet of the premixer 15, if the diffusion fuel flow 8 is jetted from the diffusion fuel nozzle 3, the Reacting residual oxygen and diffusion fuel by mixed combustion,
The diffusion flame 10 may be formed within the premixed flame 18. The presence of this diffusion flame 10 improves the propagation characteristics of the premixed flame and further improves the stable range of the flame.

FIG. 7 shows still another embodiment. In FIG. 7, reference numeral 19 denotes an air flow passage for allowing the low-speed airflow 6 to flow in the strong swirling axial direction of the central portion of the swirling burner 1. In the present invention, the premix fuel nozzle 16 and the air flow passage 19 are arranged upstream or downstream of the swirl burner 1. In FIG. 7, the case where they are arranged downstream is taken as an example. The air that has flowed into the swirl burner 1 is, as in the previous embodiments, a low speed air flow 6 in the axial direction of the strong swirl in the central portion by the swirl vanes 2,
A high-speed airflow 7 flows out in the axial direction of the swirl weaker than the outer peripheral portion. After that, the low-speed airflow 6 at the center of the swirl burner 1
Flows out into the combustion chamber 9 through the air flow path 19. On the other hand, the high-speed air stream 7 at the outer peripheral portion mixes with the premixed fuel stream 17 ejected from the premixed fuel nozzle 16, becomes a premixed gas, flows out into the combustion chamber 9, and forms a premixed flame 18.
Further, when the diffusion fuel flow 8 is caused to flow out from the diffusion fuel nozzle 3, the diffusion flame 10 can be formed in the premixed flame 18 by the reaction with the air flowing out from the air flow passage 19. Therefore, the stability of the premixed flame can be improved. In the case of the present invention, not the reaction between residual oxygen and the diffusion fuel, which have become high temperature due to the premixed combustion reaction, but the reaction between the low temperature inlet air and the diffusion fuel, so the NOx emission amount can be reduced.

[0019]

As described above, according to the present invention,
The stagnation region near the central axis of the premixer can be reduced to stabilize the hot circulating flow. Furthermore, premixing and diffusion co-firing are possible, and there is an effect that flame blowout can be prevented and flame stability can be improved. In addition, the co-firing system can be configured to perform diffusion combustion by the reaction of air and fuel in the central part and premixed combustion by the reaction of the lean premixed gas in the outer peripheral part, improving flame stability and reducing NOx. There is also the effect of. In addition, since it is composed of one swirl vane in the radial direction, the method for fixing the swirl vane is easy, and there is an effect that the manufacturability is improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a swirl burner according to an embodiment of the present invention.

FIG. 2 is a structural schematic diagram of a swirl burner according to an embodiment of the present invention.

FIG. 3 is a diagram showing an example of combustion by the swirl burner of the present invention.

FIG. 4 is a view showing a modified example of the swirl vane structure of the present invention.

FIG. 5 is a diagram showing a modification of the swirl vane structure of the present invention.

FIG. 6 is a structural diagram of a swirl burner according to another embodiment of the present invention.

FIG. 7 is a structural diagram of a swirl burner according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Swirl burner, 2 ... Swirl vane, 3 ... Diffusion fuel nozzle, 4 ... Central swirl angle, 5 ... Peripheral swirl angle, 6 ... Low speed air flow, 7 ... High speed air flow, 8 ... Diffusion fuel flow, 9 ... Combustion chamber, 10 ... Diffusion flame, 11 ... Central circulation flow, 12 ... Peripheral circulation flow, 13 ... Notch, 14 ... Junction, 15 ... Premixer, 16 ... Premix fuel nozzle, 17 ... Premixed fuel flow,
18 ... Premixed flame, 19 ... Air flow path.

Claims (5)

[Claims] 1. A cylindrical gas turbine combustion swirl burner having a fuel nozzle arranged at the center and having a plurality of swirl vanes in the circumferential direction, wherein the swirl vanes are composed of one radial blade. A swirl burner for a gas turbine combustor, characterized in that a swirl angle is changed from the central part toward the outer peripheral part to change the swirl angle between the central part and the outer peripheral part. 2. The swirl burner for a gas turbine combustor according to claim 1, wherein a notch is provided in a radial portion of the swirl vane. 3. A swirl burner for a gas turbine combustor according to claim 1, wherein the swirl vanes are configured as one by connecting a plurality of swirl vanes having different swirl angles at a central portion and an outer peripheral portion. 4. In a cylindrical gas turbine combustion swirl burner having a fuel nozzle arranged at the center and having a plurality of swirl vanes in the circumferential direction, a fuel injection nozzle is provided upstream or downstream of the swirl burner, and downstream. A swirl burner for a gas turbine combustor, wherein a premixer enclosing the swirl burner and the fuel injection nozzle is arranged in the swirl burner. 5. A cylindrical gas turbine combustion swirl burner having a plurality of swirl vanes in the circumferential direction with a fuel nozzle arranged at the center, and an air pipe for guiding air to the central portion upstream or downstream of the swirl burner. A swirl burner for a gas turbine combustor, characterized in that a fuel injection nozzle is arranged on an outer peripheral portion of the swirl burner, and a premixer enclosing the air pipe and the fuel injection nozzle is disposed downstream.