Patent Grant
7171813
1) Field of the Invention
The present invention relates to a gas turbine combustor for a gas turbine. More particularly, this invention relates to a fuel injection nozzle for a gas turbine combustor that supplies fuel to air guided to the gas turbine combustor for the gas turbine, a gas turbine combustor that has this fuel injection nozzle, and a gas turbine that has the nozzle.
2) Description of the Related Art
A conventional gas turbine combustor has widely used a diffusion combustion system that injects fuel and combustion air from different nozzles, and burns the mixture. However, recently, in place of the diffusion combustion system, a premixed combustion system which is advantageous based on a reduction of thermal NOx has come to be used. The premixed combustion system refers to a system that mixes fuel and combustion air in advance, injects the mixture (hereinafter, “premixed gas”) from one nozzle, and burns the mixture. According to this premixed combustion system, even if the ratio of the fuel to the premixed gas is low, the premixed gas is burned in all the combustion area. Therefore, it is easy to lower the temperature of the flame (hereinafter, “premixed flame”) generated by the premixed gas. Consequently, this system is advantageous in the reduction of NOx as compared with the diffusion combustion system. On the other hand, this system has a problem in that the stability of combustion is inferior to that of the diffusion combustion system, and backfire and autoignition of the premixed gas occur.
A premixed flame formation nozzle 40 is provided around the diffusion flame formation corn 30 in advance. A main fuel injection nozzle 610 that injects main fuel, mixes the main fuel with the combustion air, and forms the premixed gas is provided inside the premixed flame formation nozzle 40. This main fuel injection nozzle 610 has a conical shape at a front end thereof. Fuel injection holes 61 that inject the main fuel are provided on the external surface of the main fuel injection nozzle 610. The main fuel injected from the fuel injection holes 61 is mixed with the combustion air supplied from between the gas turbine combustor external cylinder 10 and the gas turbine combustor internal cylinders 20, and the premixed gas is formed. This premixed gas is injected from the premixed flame formation nozzle 40 to a combustion chamber 50 via a premixed flame formation nozzle extension pipe 400.
A high-temperature combustion gas emitted from the diffusion flame ignites the premixed gas injected to the combustion chamber 50, thereby to form the premixed flame. The diffusion flame formed by the diffusion flame formation corn 30 stabilizes the premixed flame. A high-temperature and high-pressure combustion gas is emitted from the premixed flame. The combustion gas passes through a tailpipe, not shown, of the gas turbine combustor, and is guided to a turbine first stage nozzle.
As the above main fuel injection nozzle 610 is provided with the fuel injection holes 61 that inject the main fuel on the external surface of the main fuel injection nozzle 610, the main fuel is injected out along the surface of the main fuel injection nozzle 610. Therefore, this main fuel does not diffuse easily at the downstream, and there is a problem that it is not possible to homogeneously generate the premixed flame. In order to solve this problem, Japanese Patent Application Laid-open No. 6-2848 discloses a fuel injection nozzle that has a plurality of cylindrical spokes having a plurality of fuel injection holes in a radial direction of the fuel injection nozzle, and injects the fuel from the fuel injection holes provided on the spokes.
A fuel injection nozzle 620 injects the fuel from the fuel injection holes 61 provided on cylindrical hollow spokes 68. Therefore, there is an advantage that it is easy to diffuse the fuel at the downstream of the hollow spokes 68, and that it is possible to keep a homogeneous and stable combustion state. However, as each hollow spoke 68 has a circular cross section, the flow of the combustion air is disturbed at the back of the hollow spoke 68, which has caused the occurrence of backfire.
It is an object of the present invention to at least solve the problems in the conventional technology.
The fuel injection nozzle according to one aspect of the present invention includes a nozzle body that has a first cavity where fuel flows; and a spoke that is provided on the nozzle body and has a leading edge, a trailing edge, a second cavity connected to the first cavity, and a hole from which the fuel is injected, wherein the hole is provided on a side of the spoke at a distance from a surface of the fuel injection nozzle body, and the distance is determined based on diffusion of the fuel.
The gas turbine combustor according to another aspect of the present invention includes a gas turbine combustor internal cylinder; a first nozzle that is disposed inside the gas turbine combustor internal cylinder, and mixes pilot fuel with air to generate a diffusion flame; a second nozzle that is provided on a circumference being concentric with the first nozzle, and mixes main fuel with air to generate a premixed flame; a diffusion corn that is attached at an outlet of the first nozzle to diffuse the pilot fuel mixed; and a premixed gas guide that is attached at the outlet of the second nozzle to guide the main fuel mixed to an inner peripheral surface of the gas turbine combustor internal cylinder.
The gas turbine combustor according to still another aspect of the present invention includes a gas turbine combustor internal cylinder; a first nozzle that is disposed inside the gas turbine combustor internal cylinder, and has a first hole into which a main fuel flows; a spoke that is provided on an inner peripheral surface of the first nozzle and has a leading edge, a trailing edge, a cavity connected to the first hole, and a second hole from which the main fuel is injected; and a second nozzle that is disposed inside the first nozzle, and mixes pilot fuel with air.
The gas turbine according to still another aspect of the present invention includes a compressor that compresses air; a gas turbine combustor that generates combustion gas from the air, wherein the gas turbine combustor includes a gas turbine combustor internal cylinder; a first nozzle that is disposed inside the gas turbine combustor internal cylinder, and mixes pilot fuel with air to generate a diffusion flame; a second nozzle that is provided on a circumference being concentric with the first nozzle, and mixes main fuel with air to generate a premixed flame; a diffusion corn that is attached at an outlet of the first nozzle to diffuse the pilot fuel mixed; and a premixed gas guide that is attached at the outlet of the second nozzle to guide the main fuel mixed to an inner peripheral surface of the gas turbine combustor internal cylinder; and a turbine that is driven by the combustion gas generated.
The gas turbine according to still another aspect of the present invention includes a compressor that compresses air; a gas turbine combustor that generates combustion gas from the air, wherein the gas turbine combustor includes a gas turbine combustor internal cylinder; a first nozzle that is disposed inside the gas turbine combustor internal cylinder, and has a first hole into which a main fuel flows; a spoke that is provided on an inner peripheral surface of the first nozzle and has a leading edge, a trailing edge, a cavity connected to the first hole, and a second hole from which the main fuel is injected; and a second nozzle that is disposed inside the first nozzle, and mixes pilot fuel with air; and a turbine that is driven by the combustion gas generated.
The other objects, features and advantages of the present invention are specifically set forth in or will become apparent from the following detailed descriptions of the invention when read in conjunction with the accompanying drawings.
Exemplary embodiments relating to the present invention will be explained in detail below with reference to the accompanying drawings. The present invention is not limited to the embodiments. Constituent elements in the following embodiments include those which persons skilled in the art could easily assume or which are substantially identical elements.
A plurality of hollow spokes 62, each having an aerofoil cross section, are radially provided around the nozzle body 60 as shown in
The fuel injection nozzle 600 has the fuel injection holes 61 that inject the fuel. The fuel injection holes 61 are provided on the side surfaces of the hollow spokes 62 with a distance from the surface of the cylindrical nozzle body 60. Because of the provision of these fuel injection holes 61, the fuel can easily diffuse at the downstream of the hollow spokes 62. The mixed gas of the fuel and the combustion air burns homogeneously, and thus the flame generated by the mixed gas does not have a local high-temperature area. As a result, the fuel injection nozzle 600 can reduce the generation of NOx more than the conventional fuel injection nozzle.
Conventionally, the cross section of each hollow spoke in a circumferential direction is circular. This circular shape allows the combustion air to whirl at the downstream of the hollow spoke and flow far away from the surface of the hollow spoke, and thus causes a backfire. On the other hand, since the hollow spoke 62 according to the this embodiment has the aerofoil cross section, the combustion air flows smoothly, and disturbance of the combustion air is reduced at the downstream of the hollow spoke 62. Therefore, it is possible to suppress the generation of NOx and suppress backfire by diffusing the fuel to the combustion air. Consequently, it is possible to reduce the burnout of the nozzle extension pipe and the like, and it is possible to make long the life of the gas turbine combustor. It is also possible to reduce the trouble of maintenance and inspection.
While the cross section of each hollow spoke 62 is aerofoil, the cross section can also take a plate shape thereby to suppress the disturbance of the combustion air at the downstream of the hollow spoke 62. When the cross section of the hollow spoke 62 has a plate shape, it is possible to manufacture the hollow spokes 62 easily, although the effect of suppressing the disturbance of the combustion air is slightly less than the effect when the cross section is aerofoil.
When a swirler is used to give a swirl to the combustion air, the hollow spoke 62 may be inclined toward the axial direction of the nozzle body 60 so that the hollow spoke 62 is parallel with the flow direction of the combustion air that is given the swirl by the swirler. Precisely, the hollow spoke 62 is provided so that a chord line connecting the leading edge 62l and the trailing edge 62t is nonparallel to the axis of the nozzle body. With this arrangement, the combustion air whose direction is changed by the swirler flows smoothly along the surface of the hollow spoke 62. Therefore, it is possible to reduce the disturbance of the combustion air at the downstream of the hollow spoke 62. As a result, the swirler can sufficiently mix the combustion air with the fuel, and it becomes possible to reduce NOx by suppressing the generation of a local high-temperature area, and reduce the burnout of the nozzle extension pipe and the like by suppressing the occurrence of backfire.
As shown in
Further, as shown in
As a result, it is possible to suppress the generation of a local high-temperature area, and it becomes possible to further reduce the generation of NOx. Each hollow spoke 63 having an aerofoil cross section does not allow the combustion air to flow far away from the surface of the hollow spoke 63, and the flow of the combustion air is not disturbed at the downstream of the hollow spoke 63. Therefore, it is possible to suppress backfire. Further, since the hollow spokes 63 give a swirl to the combustion air, depending on the level of the swirl, it is not necessary to use a swirler provided in the vicinity of the inlet of premixed flame formation nozzle.
As shown in
A trailing edge 65t of each hollow spoke 65 has a sweptforward angle θ. It is preferable to provide this a sweptforward angle θ as it is possible to suppress separation of air thereby to suppress backfire. From the viewpoint of suppressing the separation of air at the trailing edge 65t of each hollow spoke 65, the sweptforward angle θ is preferably 10 to 30 degrees, and more preferably 15 to 25 degrees.
The combustion air that flows from an inlet 46 of the flame formation nozzle 41 is mixed with the fuel injected from the fuel injection holes 61 to the inside of the flame formation nozzle 41. The fuel injection nozzle 603 according to the present embodiment does not have the cylindrical nozzle body 60 (see
In this embodiment, when a swirler is used to give a swirl to the combustion air, the hollow spokes 65 may be fitted with an inclination toward the axial direction of the flame formation nozzle 41. With this arrangement, the combustion air whose direction is changed by the swirler flows smoothly along the surface of the hollow spokes 65. Therefore, it is possible to reduce the disturbance of the combustion air at the downstream of the hollow spoke 65. As a result, the swirler can sufficiently mix the combustion air with the fuel, and it becomes possible to reduce NOx by suppressing the generation of a local high-temperature area, and reduce the burnout of the nozzle extension pipe and the like by suppressing the occurrence of backfire.
As explained in the second embodiment, the hollow spokes 65 of the fuel injection nozzle 603 according to the present embodiment may be inclined toward the flow direction of the combustion air to give a swirl to the combustion air, thereby to sufficiently mix the combustion air with the main fuel. Depending on the level of the swirl, it is not necessary to use the swirler to give a swirl to the combustion air.
Examples of applications of the fuel injection nozzle according to the present invention to a gas turbine combustor are explained next.
As shown in
As shown in
As shown in
As shown in
Of side portions of each nozzle extension pipe 410 that exists in a radial direction of the gas turbine combustor internal cylinder 20, at least a side portion 411 near the central axis of the gas turbine combustor internal cylinder 20 is inclined toward the outside of the radial direction of the gas turbine combustor internal cylinder 20 at a constant angle α from a plane perpendicular to the central axis of the gas turbine combustor internal cylinder 20 (see
As explained above, by inclining each nozzle extension pipe 410 toward the outside of the radial direction of the gas turbine combustor internal cylinder 20, it is possible to give an outward flow to the premixed gas (as shown by arrow mark A in
The flow of air is explained with reference to
The swirler 33 provided within the diffusion flame formation nozzle 32 stirs the compressed air guided into the diffusion flame formation nozzle 32, and sufficiently mixes the compressed air with the pilot fuel injected from the pilot fuel injection nozzle 31. Both mixed gases form the diffusion flame, and this diffusion flame is injected out from the diffusion flame formation corn 30 to the combustion chamber 50. This diffusion flame causes the premixed gas prepared by the premixed flame formation nozzle 40 to be combusted quickly. This diffusion flame stabilizes the combustion of the premixed gas, and suppresses backfire of the premixed flame and autoignition of the premixed gas.
A swirler 42 provided within the premixed flame formation nozzle 40 stirs the compressed air guided into the premixed flame formation nozzle 40. The compressed air is sufficiently mixed with the main fuel injected from the fuel injection holes 61 provided on the hollow spokes 62 of the fuel injection nozzle 600, and a premixed gas is formed. The premixed gas is injected from the nozzle extension pipes 410 to the combustion chamber 50. As the fuel injection holes 61 are provided with a distance from the surface of the nozzle body 60, the main fuel sufficiently diffuses to the compressed air as the combustion air, and is mixed with the compressed air. As it is necessary to suppress the generation of NOx, the premixed gas is in a state that air is excess for the fuel. This high-temperature combustion gas emitted from the diffusion flame quickly ignites the premixed gas, and forms the premixed flame. High-temperature and high-voltage combustion gas is emitted from the premixed flame.
In the premixed flame formation nozzle 40 shown in
Like a premixed flame formation nozzle 40b shown in
As shown in
As explained above, at least a side portion of each nozzle extension pipe 410 near the central axis of the gas turbine combustor internal cylinder 20 is inclined toward the inner wall side of the gas turbine combustor internal cylinder 20 with the constant angle α from the axial direction of the gas turbine combustor internal cylinder 20. The outlet of each nozzle extension pipe 410 is inclined at the constant angle β from the axial direction of the gas turbine combustor internal cylinder 20. Therefore, the combustion gas within the combustion chamber 50 flows spirally around the axis of the gas turbine combustor internal cylinder 20. In other words, the combustion gas forms what is called an outward spiral flow.
The cooling of the gas turbine combustor internal cylinder 20 is explained next.
In order to avoid the above problem, it is preferable that a cooling unit is provided around the gas turbine combustor internal cylinder 20a at the combustion chamber 50 side, thereby to remove the heat of the combustion gas from the gas turbine combustor internal cylinder 20a. In the example shown in
The cooling unit is not limited to the plate fin. It is possible to use a fin called an MT fin. It is also possible to provide holes around the gas turbine combustor internal cylinder 20a at the combustion chamber 50 side, and the cooling air may be injected from these holes to film cool the gas turbine combustor internal cylinder 20a at the combustion chamber 50 side. Based on these cooling units, even when high-temperature combustion gas is injected to the inner peripheral surface of the internal cylinder at the combustion chamber 50 side, this surface portion is cooled. Therefore, it is possible to suppress an increase in a local temperature of the gas turbine combustor internal cylinder 20a at the combustion chamber 50 side. Consequently, it is possible to provide the outward flow more positively, and it becomes possible to further promote the mixing of the premixed gas.
According to the conventional gas turbine combustor, the combustion gas swirls toward the center of the gas turbine combustor, and forms what is called an inward spiral flow. Therefore, the premixed gas is concentrated to the vicinity of the center of the combustion chamber 50. Consequently, the combustion proceeds quickly at this portion, which easily generates a local high-temperature area. As a result, it is not possible to sufficiently suppress the generation of NOx. Further, as the recirculation area is not sufficiently formed, the premixed flame becomes unstable, and combustion oscillation and the like are generated.
On the other hand, in the gas turbine combustor to which the fuel injection nozzle 600 according to the present invention is applied, the fuel injection nozzle 600 provided within the premixed flame formation nozzle 40 sufficiently mixes the premixed gas. Therefore, it is possible to suppress the generation of a local high-temperature area. Further, according to this gas turbine combustor, each nozzle extension pipe 410 has a constant angle. Based on this, the outward spiral flow is given to the premixed gas to direct the premixed gas toward the outside of the radial direction of the gas turbine combustor internal cylinder 20 and flow the premixed gas spirally in the circumferential direction. Therefore, the premixed gas is further mixed in the process of spirally flowing around the diffusion flame, and homogeneously burns in the whole area within the combustion chamber 50. Based on the mutual interaction, it is possible to sufficiently suppress the generation of a local high-temperature area, and therefore, it is possible to sufficiently suppress the generation of NOx.
In the fuel injection nozzle 600 according to the present invention, the hollow spokes 62 have aerofoil cross sections. Therefore, the combustion air flows smoothly along the surface of the hollow spokes 62, which suppresses the disturbance of the combustion air at the downstream of the hollow spoke 62. Therefore, it is possible to suppress backfire attributable to the disturbance of the combustion air. Further, based on the outward spiral flow, the recirculation area formed at the center portion of the gas turbine combustor expands. Based on the interaction, the combustion of the premixed flame becomes stable, and it becomes possible to suppress the combustion oscillation. Therefore, it is possible to carry out a stable operation of the gas turbine. As the premixed gas burns in the whole area within the combustion chamber 50, there remains little premixed gas that does not combust, which makes it possible to efficiently utilize the fuel. In the present embodiment, in order to provide the outward spiral flow, only the outlet of each nozzle extension pipe 410 is inclined toward the outside of the radial direction and the circumferential direction of the gas turbine combustor internal cylinder 20. Since it is not necessary to carry out a special processing to the exit of each nozzle extension pipe 410, it becomes easy to manufacture the nozzle extension pipe.
A first modification of the first application example is explained below.
As shown in
Nozzle extension pipes 440 are provided at the outlet of each mixed gas formation cylinder 70. Each nozzle extension pipe 440 injects a gas mixture of the combustion air, the main fuel, and the pilot fuel to the combustion chamber 50 side. The outlet of each nozzle extension pipe 440 has a circular shape, and is inclined toward the outside of the radial direction of the gas turbine combustor internal cylinder 20. The nozzle extension pipe 440 is also inclined toward the circumferential direction of the gas turbine combustor internal cylinder 20. The outlet of each nozzle extension pipe 440 is not limited to the circular shape, and it may be a sector shape or an elliptical shape as shown in the first embodiment. This similarly applies to the following explanation.
The gas turbine combustor in the second application example has five mixed gas formation cylinders 70, each having the nozzle extension pipe 440 at the outlet thereof, disposed annularly inside the gas turbine combustor internal cylinder 20 (see
The flow of air is explained with reference to
The flow is explained with reference to
The mixed gas of the pilot fuel and the combustion air, and the premixed gas are injected to the combustion chamber 50 side via the nozzle extension pipes 440. The mixed gas of the pilot fuel that is injected to the combustion chamber 50 side and the combustion air forms a diffusion flame. The high-temperature combustion gas generated from the diffusion flame causes the premixed gas to be combusted quickly. This diffusion flame stabilizes the combustion of the premixed gas, and suppresses backfire of the premixed flame and autoignition of the premixed gas. The combusted premixed gas forms a premixed flame, and the high-temperature and high-pressure combustion gas is emitted from the premixed flame.
The mixed gas of the pilot fuel and the combustion air, and the premixed gas is directed from the nozzle extension pipes 440 toward the outside of the radial direction of the gas turbine combustor internal cylinder 20, and becomes the outward spiral flow that swirls to the circumferential direction and flows into the combustion chamber 50. Based on this outward spiral flow, the premixed gas is mixed sufficiently, and the combustion progresses in the whole area in the gas turbine combustor. Since the hollow spokes 62 diffuse the main fuel of the premixed gas, based on the interaction with the mixing operation, it is possible to more suppress the generation of a local high-temperature area. Therefore, it is possible to suppress the generation of NOx.
Based on the outward spiral flow, a portion near the inner wall of the combustion chamber 50 is applied with a high pressure, and a portion near the center is applied with a low pressure. As a result, a circular flow is generated between the vicinity of the inner wall and the vicinity of the center, and a recirculation area is formed. As the cross section of each hollow spoke 62 is aerofoil, the combustion air flows smoothly, and it becomes possible to suppress the generation of backfire. Based on these actions, the flame is stabilized and the combustion oscillation is reduced. Therefore, it is possible to carry out a stable operation of the gas turbine.
As shown in
Each premixed flame formation nozzle has the fuel injection nozzle 600 (refer to
The premixed gas injected from the premixed flame formation nozzle is injected to the combustion chamber side via the nozzle extension pipe 450. Based on the nozzle extension pipe 450, the premixed gas injected to the combustion chamber side becomes an outward spiral flow, and flows spirally within the combustion chamber. In the gas turbine combustor according to the present application example, since the premixed flame formation nozzles are disposed on each of the two pitch circles D1 and D2, the outward spiral flow is generated corresponding to the respective groups of the premixed flame formation nozzles provided on each of the two pitch circles D1 and D2. Based on the two outward spiral flows, a circulation flow is generated between the vicinity of the inner wall of the combustion chamber and the vicinity of the center of the combustion chamber, and between the outward spiral flow according to the outside premixed flame formation nozzle group and the outward spiral flow according to the inside premixed flame formation nozzle group, respectively. Based on the outward spiral flows and the circulation flows, the premixed gas of which main fuel is sufficiently diffused by the fuel injection nozzles 600 is further mixed. As a result, it is possible to suppress the generation of a local high-temperature portion, and therefore, it is possible to further suppress the generation of NOx.
Since the cross section of each hollow spoke 62 provided on the fuel injection nozzle 600 is aerofoil, the combustion air flows smoothly at the back of the hollow spoke 62. Based on this action and the two recirculation areas, the premixed flame is more stabilized, and it becomes possible to reduce combustion oscillation and the like. In the gas turbine combustor according to the present embodiment, as the premixed flame formation nozzles are disposed on each of the two pitch circles D1 and D2, it is possible to suitably select the premixed flame formation nozzle group according to the load. Therefore, it is possible to carry out a lean combustion operation at an optimum fuel-to-air ratio in a whole range from a partial load to the full load. Consequently, it is possible to suppress the generation of NOx in the whole load areas.
As shown in
The gas turbine combustor according to the fourth application example has the fins 465 provided at the outlet of the nozzle extension pipes 460. The outlet of each nozzle extension pipe 460 is inclined toward the outside of the radial direction of the gas turbine combustor internal cylinder 20. The fuel injection nozzle 600 (see
As the cross section of each hollow spoke 62 provided on the fuel injection nozzle 600 is aerofoil, the premixed gas is injected smoothly from the nozzle extension pipe 460. Based on the outward spiral flow, a portion near the inner wall of the combustion chamber 50 is applied with a high pressure, and a portion near the center is applied with a low pressure. Therefore, a large circulation flow is generated between the vicinity of the inner wall and the vicinity of the center, thereby to expand a recirculation area. As the premixed gas combusts stably based on these actions, it is possible to suppress the combustion oscillation and the like, and it becomes possible to carry out a stable operation of the gas turbine. When the fins 465 are provided on the inner wall of the gas turbine combustor internal cylinder 20, it is also possible to obtain a similar effect.
In the gas turbine combustor according to the present modification, the fins 475 are provided at the outlet of each nozzle extension pipe 470. The outlet of the nozzle extension pipe 470 is inclined to give the premixed gas a swirl that is directed to the circumferential direction of the gas turbine combustor internal cylinder 20. The fins 475 are also inclined toward the outside of the radial direction of the gas turbine combustor internal cylinder 20, thereby to give the premixed gas a flow directed to this direction. It is possible to suitably increase or decrease the number of fins 475.
Based on the inclination of the nozzle extension pipes 470 and the inclination of the fins, the premixed gas injected from the nozzle extension pipes 470 proceeds spirally around the axis of the gas turbine combustor internal cylinder 20. In other words, the premixed gas forms the outward spiral flow. Since the premixed gas is sufficiently mixed based on the outward spiral flow and the fuel injection nozzles 600 (see
Although not clear from
When the hollow spokes inclined toward the flow direction of the combustion air are used, it is possible to give a swirl to the combustion air. Therefore, it is possible to sufficiently mix the fuel with the combustion air at the downstream of the hollow spokes. Since it is possible to suppress the generation of a local high-temperature area, the gas turbine 100 can reduce the generation of NOx more than the conventional gas turbine. Since the gas turbine can suppress the generation of backfire more than the conventional gas turbine, it is possible to carry out a highly reliable operation by maintaining a stable combustion state. Since it is possible to make long the life of the gas turbine combustor 106, it becomes possible to reduce the trouble of maintenance and inspection.
When the premixed flame formation nozzles 40b shown in
In the present gas turbine 100, it is possible to apply the fuel injection nozzles 600 and the like (see
As explained above, according to a first aspect of the present invention, in the fuel injection nozzle for a gas turbine combustor, a plurality of fuel injection holes that supply fuel are provided on the side surfaces of the hollow spokes, each having an aerofoil cross section, with a distance from the surface of the nozzle body. Therefore, the fuel can easily diffuse at the downstream of the hollow spokes. The mixed gas of the fuel and the combustion air burns homogeneously, which can suppress the generation of a local high-temperature area. As a result, this fuel injection nozzle can reduce the generation of NOx more than the conventional fuel injection nozzle. Since the cross section of each hollow spoke according to the present invention is aerofoil, the combustion air flows smoothly. Therefore, it is possible to reduce the disturbance of the combustion air at the back of the hollow spoke, and it becomes possible to suppress backfire while reducing the generation of NOx.
According to a second aspect of the present invention, the fuel injection nozzle for a gas turbine combustor has the hollow spokes disposed at the upstream of the swirler. Therefore, the swirler disposed at the downstream of the hollow spokes generates pressure loss in the combustion gas. This pressure loss stirs the combustion gas, and homogeneously mixes the fuel in the combustion gas with air, therefore, the combustion air combusts more homogeneously. As a result, it becomes possible to more suppress the generation of a local high-temperature area, and it becomes possible to more reduce NOx.
According to a third aspect of the present invention, in the fuel injection nozzle for a gas turbine combustor, the trailing edge of the end portion of each hollow spoke is disposed at the upstream of the inlet of the flame formation nozzle. Therefore, it is possible to minimize the influence of the hollow spoke, and it is possible to supply a sufficient quantity of combustion air into the flame formation nozzle. As a result, it becomes possible to reduce the generation of NOx.
According to a fourth aspect of the present invention, in the fuel injection nozzle for a gas turbine combustor, a fuel injection nozzle consisting of only hollow spokes is provided on the inner wall of the flame formation nozzle. Therefore, the cylindrical nozzle body is not necessary. The cross sectional area through which the combustion air passes inside the flame formation nozzle can be made larger than that when the fuel injection nozzle having the cylindrical nozzle body is used. Consequently, when the quantities of the combustion air that flow in both cases are the same, it is possible to make smaller the external sizes of the flame formation nozzle. As a result, it becomes possible to suppress backfire while reducing the generation of NOx, and it becomes possible to make compact the gas turbine combustor as a whole.
According to a fifth aspect of the present invention, the fuel injection nozzle for a gas turbine combustor has the hollow spokes inclined toward the flow direction of the combustion air. Since it is possible to give a swirl to the combustion air, it becomes possible to sufficiently mix the fuel with the combustion air based on the interaction with the diffusion of fuel. Since each hollow spoke has an aerofoil cross section, there is little separation of the combustion air, and it becomes possible to suppress disturbance of the flow at the downstream of the hollow spokes. As a result, it is possible to suppress the generation of a local high-temperature area, and it is possible to suppress backfire while reducing the generation of NOx.
According to a sixth aspect of the present invention, the fuel injection nozzle for a gas turbine combustor has the sweptforward angle at the trailing edge of each hollow spoke. Therefore, the combustion air that enters from the leading edge flows smoothly along the trailing edge. As a result, it is possible to suppress disturbance of the flow at the downstream of the hollow spokes, and it becomes possible to suppress backfire.
According to a seventh aspect of the present invention, the gas turbine combustor has the fuel injection nozzle for a gas turbine combustor. Therefore, it is possible to suppress the generation of NOx, and it becomes possible to reduce the environmental burden by purifying exhaust gas. Since the fuel injection nozzle for the gas turbine combustor can suppress backfire, the life of the gas turbine combustor becomes long, and it becomes possible to reduce the trouble of maintenance and inspection.
According to an eighth aspect of the present invention, the gas turbine has a gas turbine combustor having the fuel injection nozzle for a gas turbine combustor. Therefore, it is possible to reduce NOx, and it becomes possible to reduce the environmental burden by purifying exhaust gas. Since it is also possible to suppress the generation of backfire, it becomes possible to carry out a highly reliable operation by maintaining a stable combustion state.
Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.
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