JP2004170010A - Gas turbine combustor and method of supplying fuel to the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustion system less in NOx and superior in combustion stability by solving problems with high level NOx in the case of a diffusion combustion system and with combustion stability due to backfire in the case of a premixture combustion system, at the same time. <P>SOLUTION: A combustion air flow path is arranged coaxially with a fuel flow on the wall face of a combustion chamber to form a coaxial jet with the fuel flow embraced by an air flow, as a porous coaxial jet with these diffused in number. Herein, a circular collar member is provided at the end of a fuel nozzle to form the air flow path perpendicular to the axis of the fuel flow. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a gas turbine combustor and a fuel supply method for the gas turbine combustor.
[0002]
[Prior art]
Gas turbine combustors include a diffusion combustion system and a premix combustion system. In the diffusion combustion method, a fuel is directly injected into a combustion chamber in order to secure a large combustion stability over a wide range from a start to a rated load condition. On the other hand, the premixed combustion method is a combustion method for reducing nitrogen oxides. However, in the case of the premixed combustion system, a specific unstable element such as a flashback phenomenon in which a flame enters the premixer and burns out the structure occurs.
[0003]
To cope with this problem, it has been proposed to arrange the fuel holes of the fuel nozzles opposed to the combustion chamber and the air holes of the air nozzles coaxially, and to supply the fuel and air to the combustion chamber as a coaxial flow ( For example, see Patent Document 1.)
[0004]
[Patent Document 1]
JP-A-2001-263093
[Problems to be solved by the invention]
In the case of the diffusion combustion system, there is a problem of high-level NOx, and in the case of the premix combustion system, there are problems of combustion stability such as flashback, and problems of flame stabilization at startup and partial load. In actual operation, it is desirable to solve these problems at the same time. On the other hand, in the gas turbine combustor described in Patent Document 1, fuel and air are supplied to the combustion chamber as a coaxial flow. However, since the air flow is not taken into consideration, manufacturing tolerances generated during the manufacturing process of the fuel nozzle and In the case of misalignment of each coaxial flow due to assembling tolerance generated in the assembling stage of the combustor, the influence on combustion performance caused by uneven distribution of fuel and air is not considered.
[0006]
An object of the present invention is to improve the combustion stability of a gas turbine combustor.
[0007]
[Means for Solving the Problems]
A gas turbine combustor comprising a fuel supply hole and a combustion air hole, and supplying fuel from the fuel nozzle to the combustion chamber through the combustion air hole, wherein a fuel flow passing through the combustion air hole is An air flow path capable of obtaining an air flow velocity in the axial center direction sufficient to be located substantially at the axial center of the air hole is provided.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
By making the fuel flow coaxial so that the air flow wraps around it, the fuel flows into the combustion chamber and then mixes with the surrounding coaxial air flow before actually contacting the hot gas and starting combustion, and It burns after it becomes a premixed mixture at a mixing ratio. For this reason, low NOx combustion equivalent to lean premixed combustion becomes possible. At this time, the portion corresponding to the premixing tube of the conventional premixed combustor is extremely short, and the fuel concentration near the inner wall surface of the air hole becomes almost zero, so that the potential for burnout due to flashback is extremely low. On the other hand, by providing a circular brim-shaped member at the tip of the fuel nozzle to form an air flow path orthogonal to the fuel flow axis, an air flow directed toward the axial center of each air flow path is formed. Even when there is a deviation between the center of the flow axis and the center of the air flow path, an effect of reducing the influence can be expected. That is, it is possible to reduce the influence on the combustion performance due to the misalignment of each coaxial flow due to the manufacturing tolerance generated during the manufacturing process of the fuel nozzle or the assembly tolerance generated at the stage of assembling the combustor.
[0009]
(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an overall cross-sectional view of a gas turbine combustor according to the present embodiment. In FIG. 1, this gas turbine combustor is mainly composed of a compressor 10 for compressing air for combustion, a turbine 18 for driving a turbine shaft by combustion gas, and a combustor.
[0010]
The compressor 10 compresses air supplied from the outside, and sends the compressed air to the combustor.
[0011]
The turbine 18 uses a high-temperature combustion gas generated from a combustor to rotationally drive a turbine shaft to generate electric power.
[0012]
The combustor includes a portion for supplying mainly fuel and air, a combustor liner 3, and an outer cylinder 2. Inside the outer cylinder 2 of the combustor, there is a fuel header 60 for sending the fuel 54 to the combustion chamber 1 in the combustor liner 3 as shown, and the fuel is supplied from a fuel nozzle 55 protruding from the fuel header 60. Further, in front of the fuel nozzles 55, combustion air holes 52 are provided coaxially corresponding to the respective nozzles.
[0013]
The air 50 sent from the compressor 10 passes between the outer cylinder 2 and the combustor liner 3, a part of which flows into the combustion chamber 1 as the cooling air 31 of the combustor liner 3, and the rest as combustion air holes as coaxial air 51. It is supplied to the combustion chamber 1 through 52. The fuel nozzle 55 is disposed so as to be substantially coaxial with the combustion air hole 52. After the fuel 54 has been pressure-recovered and rectified by the fuel header 60, the fuel 54 is supplied from a number of fuel nozzles 55 and coaxially flows with the combustion air. It flows into and mixes with the combustion chamber 1 to form a homogeneous and stable flame. The generated high-temperature combustion gas enters the turbine 18 and performs work to be exhausted.
[0014]
FIG. 2 shows the details of the nozzle section. The combustion air holes 52 are arranged so that the fuel supplied from the fuel nozzle 55 and the combustion air form a coaxial flow. Erupts from the end face of. The fuel and the air are configured as a large number of small-diameter coaxial flows, and the fuel and the air are sufficiently mixed over a relatively short distance to prevent flashback without uneven distribution of the fuel. In this embodiment, the combustion air holes 52 having a diameter larger than the inner diameter of the fuel nozzle 55 are provided. That is, since a large number of coaxial flows, which wrap the fuel flow in an annular air flow, are ejected from the end face of the combustion air hole 52, the fuel and the air are sufficiently mixed with a short premixing distance, and the NOx is reduced. Flashback can also be suppressed. However, even if the inner diameter of the fuel nozzle 55 is larger than the inner diameter of the combustion air hole 52, if a coaxial flow that wraps the fuel flow in the annular air flow can be formed, it will lead to the prevention of flashback.
[0015]
In addition, in the configuration of the present embodiment, the mixing proceeds partially before the fuel flows out from the inner surface of the combustion air hole wall 53, and the stirring effect due to the rapid expansion at the portion ejected as a coaxial flow causes a shorter distance. Mixing of fuel and air can be expected. Further, by adjusting the length of the flow path of the air hole, it is possible to set the state from a state where mixing is hardly performed in the flow path to a state where the mixing is almost completely premixed.
[0016]
Further, the gas turbine combustor of the present embodiment includes a fuel supply hole of the fuel nozzle 55, and a combustion air hole 52 disposed substantially coaxially with the fuel supply hole with a desired gap downstream thereof. The fuel supplied from the nozzle 55 is supplied to the combustion chamber through the combustion air hole 52, and the axial direction sufficient for the fuel flow passing through the combustion air hole 52 to be located substantially at the axial center of the combustion air hole 52 is sufficient. The air flow path which can obtain the air flow velocity of is provided. With such a configuration, combustion can be stabilized while reducing NOx.
[0017]
In the present embodiment, as an example of forming an air flow path capable of obtaining an air flow velocity in the axial center direction sufficient for the fuel flow passing through the combustion air hole 52 to be located substantially at the axial center of the combustion air hole 52, An annular collar 56 is provided at the tip of the fuel nozzle 55. This brim-shaped member 56 is installed so as to be parallel to the inner surface of the wall 53 where the combustion air hole 52 is formed. However, it may be slightly inclined as long as the following effects can be obtained, but the outermost peripheral portion of the collar member 56 is formed outside the combustion air hole 52. Since the fuel flow is located substantially in the center, it is possible to obtain a sufficient central air flow velocity, and a cross flow that is an air flow that is orthogonal to the fuel flow is generated. The fuel flow is prevented from flowing to another combustion air hole 52 by the cross flow. Thus, by forming an air flow path substantially perpendicular to the fuel flow axis, an air flow is generated toward the axial center of each air flow path as shown in FIG. As described above, by providing the annular brim-shaped member 56 at the tip of the fuel nozzle 55, it is possible to achieve low NOx and stable combustion with a simple structure.
[0018]
With the above-described configuration, even when a deviation occurs between the axial center of the fuel flow and the central axis of the air flow path due to an assembly tolerance or a manufacturing tolerance as shown in FIG. The effect of the air flow is expected to reduce the influence of the misalignment and maintain the coaxiality between the fuel and the air. In the case of such a configuration, the distance between the inner surface of the combustion air hole wall 53 and the brim-shaped member 56 is appropriately adjusted so that the fuel flow is not flown to another combustion air hole 52 by a cross flow as necessary. Is desirable. Further, a difference between the fuel flow and the air flow due to the magnitude relation of the flow velocity is conceivable, but it can be expected that a desired effect can be obtained in any case.
[0019]
(Second embodiment)
FIGS. 4A and 4B show details of the nozzle tip portion of the second embodiment. The present embodiment is an example in which a guide vane 57 extending in the radial direction is provided on the front surface of the brim member 56 at the tip of the fuel nozzle 55. In the case of this example, the flow of the air flow toward the center can be positively directed to the center of the fuel hole by the guide vanes 57, and the effect of further reducing the misalignment caused by assembly tolerance or manufacturing tolerance can be improved. Can be expected. In addition, the height dimension of the guide vane 57 is controlled so that the tip of the guide vane 57 is brought into close contact with the inner surface of the combustion air hole wall 53 to control the dimension in the inflow axial direction between the fuel hole and the combustion air hole. It can also be configured as follows. It is also conceivable to install the guide vanes 57 on the inner surface of the combustion air hole wall 53. In this case, a similar effect can be expected, but the direction of the air is the center of the air hole, and is not necessarily the center of the fuel hole.
[0020]
According to the present embodiment, a further mitigation effect can be expected with respect to misalignment caused by assembly tolerance or manufacturing tolerance, and further stabilization of combustion can be achieved while reducing NOx.
[0021]
(Third embodiment)
5A and 5B show a third embodiment. In this embodiment, the guide vanes 57 of the second embodiment shown in FIGS. 4A and 4B are configured to be inclined in the circumferential direction so that the airflow toward the center has a swirl component. . With such a configuration, in addition to the effects described in the second embodiment, an effect of promoting the mixing of fuel and air by the swirling flow generated by the inclined guide vanes can be expected, and a sufficient effect can be obtained over a shorter distance. Mixing becomes possible.
[0022]
According to the present embodiment, it is possible to expect a further mitigation effect and a further flashback suppression effect on the misalignment caused by assembly tolerance and manufacturing tolerance, thereby achieving low NOx and further stabilizing combustion. Can be achieved.
[0023]
(Fourth embodiment)
6 and 7 show a fourth embodiment. In FIG. 6A, the combustion air holes 52 are arranged so that the fuel supplied from the fuel nozzle 55 and the combustion air form a coaxial jet. A coaxial jet is supplied from the end face of the combustion air hole 52. The fuel and air are configured as a large number of small-diameter coaxial flows, and the fuel and air are sufficiently mixed over a relatively short distance, so that non-uniform distribution of fuel and flashback can be suppressed. Further, in the configuration of the present embodiment, the mixing proceeds partially before the fuel flows out from the inner surface of the combustion air hole wall 53, and the stirring effect accompanying the rapid expansion at the portion flowing out as a coaxial flow causes the fuel to be mixed at a shorter distance. Mixing of fuel and air can be expected. Further, by adjusting the length of the flow path of the air hole, it is possible to set the state from a state where mixing is hardly performed in the flow path to a state where the mixing is almost completely premixed.
[0024]
Here, in the present embodiment, the fuel nozzle 55 itself is configured as a thick tubular member instead of installing a brim-shaped member at the tip of the fuel nozzle. The inner diameter of the fuel nozzle 55 is smaller than the combustion air hole 52, and the outermost peripheral portion of the fuel nozzle 55 is formed on the outer peripheral side of the combustion air hole 52. As shown in FIG. 7 (a), the point that the air flow toward the center of the fuel hole is formed between the tip end surface of the fuel nozzle 55 and the inner surface of the combustion air hole wall 53 is the same as in the first embodiment. As shown in ()), it is possible to expect an action of mitigating misalignment caused by assembly tolerance or manufacturing tolerance.
[0025]
On the other hand, compared to the first embodiment, it is considered that the mechanical strength of the fuel nozzle 55 is increased and the reliability around the nozzle is improved. However, since the space between the adjacent fuel nozzles 55 becomes narrow, the air flow path to the combustion air hole 52A closer to the center of the combustor axis among the many combustion air holes 52 in FIG. There is a tendency, and it is desirable to consider the balance of the amount of combustion air passing through each combustion air hole 52.
[0026]
(Fifth embodiment)
8 and 9 show a fifth embodiment. In FIG. 8A, the combustion air hole 52 is arranged so that the fuel supplied from the fuel hole 55a instead of the fuel nozzle and the combustion air form a coaxial flow, and the fuel flow is wrapped by the annular air flow. Such a large number of coaxial flows are supplied from the end face of the air hole 52. The fuel and air are configured as a number of small diameter coaxial flows, and these fuels and air mix well over a relatively short distance, increasing the stirring effect. Further, in the configuration of the present embodiment, the mixing proceeds partially before the fuel flows out from the inner surface of the combustion air hole wall 53, and the stirring effect accompanying the rapid expansion at the portion flowing out as a coaxial flow causes the fuel to be mixed at a shorter distance. It can be expected to promote mixing of fuel and air. Further, by adjusting the length of the flow path of the air hole, it is possible to set the state from a state where mixing is hardly performed in the flow path to a state where the mixing is almost completely premixed.
[0027]
Further, in this embodiment, the fuel nozzles are not individually protruded, but are formed as fuel nozzles having fuel holes formed in the fuel header 60, and the air guide 58 is provided on the wall surface on the air hole side. As shown in FIG. 9A, the end face of the fuel hole 55a and the end face of the combustion air guide 58 form an airflow toward the center of the fuel hole as shown in FIG. As described above, it is possible to expect an action of mitigating misalignment caused by assembly tolerance or manufacturing tolerance. On the other hand, the space between the adjacent air guides tends to be narrow, and the air flow path to the combustion air hole 52A on the side closer to the center of the combustor axis among the many combustion air holes 52 as shown in FIG. It is necessary to pay attention to the balance of the amount of combustion air passing through each combustion air hole 52. In these embodiments, the fuel has a number of coaxial flows such that the air flow envelops it. Then, after the fuel flows into the combustion chamber, the fuel is mixed with the surrounding coaxial air flow before actually coming into contact with the high-temperature gas and starting the combustion, and after a premixed gas having an appropriate mixture ratio is burned. When the space between the fuel header and the inner surface of the combustion air hole wall is large, the fuel flow path also serves as an air flow path in the combustion air hole near the center of the combustor axis. A direct airflow is created. In an extreme case, this air flow may cause the fuel flow to flow to another air hole. According to the present invention, it is possible to minimize the flow of the fuel flow to another combustion air hole 52. Therefore, low NOx combustion equivalent to lean premixed combustion is possible.
[0028]
In this embodiment, the portion of the premixing passage corresponding to the premixing tube of the conventional premixed combustor is extremely short, and the fuel concentration near the wall surface is almost zero, so that the potential for burnout due to flashback is extremely low. A highly efficient combustor can be provided. In addition, by forming an air flow path substantially perpendicular to the fuel flow, such as by providing an annular collar member at the tip of the fuel nozzle, an air flow toward the axial center of each air flow path is generated, and the fuel flow Even when the center and the center of the air flow path are misaligned, an effect of reducing the influence of the misalignment can be expected. That is, it is possible to reduce the influence of the misalignment of each coaxial flow due to the manufacturing tolerance generated in the manufacturing process of the fuel nozzle or the assembly tolerance generated in the assembling stage of the combustor, and thus it is possible to improve the combustion stability. .
[0029]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the combustion stability of a gas turbine combustor can be improved.
[Brief description of the drawings]
FIG. 1 is an explanatory view including an overall sectional view of a first embodiment of the present invention.
FIG. 2 is a detailed explanatory view of a nozzle portion according to the first embodiment of the present invention.
FIG. 3 is an operation explanatory view of the first embodiment of the present invention.
FIG. 4 is a detailed explanatory view of a nozzle portion according to a second embodiment of the present invention.
FIG. 5 is a detailed explanatory view of a nozzle portion according to a third embodiment of the present invention.
FIG. 6 is a detailed explanatory view of a nozzle portion according to a fourth embodiment of the present invention.
FIG. 7 is an operation explanatory view of a fourth embodiment of the present invention.
FIG. 8 is a detailed explanatory view of a nozzle portion according to a fifth embodiment of the present invention.
FIG. 9 is an operation explanatory view of a fifth embodiment of the present invention.
[Explanation of symbols]
Reference numeral 2 denotes a combustor outer cylinder, 3 denotes a combustor liner, 52 denotes a combustion air hole, 55 denotes a fuel nozzle, 56 denotes a brim-like member, 57 denotes a guide vane, 58 denotes an air guide, and 60 denotes a fuel header.

Claims (6)

A fuel supply hole for the fuel nozzle; and a combustion air hole disposed substantially coaxially with the fuel supply hole with a desired gap downstream of the fuel nozzle. Fuel from the fuel nozzle is supplied to the combustion air hole. A gas turbine combustor for supplying to the combustion chamber via
A gas turbine combustor having an air flow path capable of obtaining an axial flow velocity sufficient for the fuel flow passing through the combustion air hole to be located substantially at the axial center of the combustion air hole. A fuel supply hole for the fuel nozzle; and a combustion air hole disposed substantially coaxially with the fuel supply hole with a desired gap downstream of the fuel nozzle. Fuel from the fuel nozzle is supplied to the combustion air hole. A gas turbine combustor for supplying to the combustion chamber via
A tip surface of the fuel nozzle,
Forming an air flow path with the fuel nozzle side wall surface of the member having the combustion air holes formed therein,
Arranged to supply air supplied from the air flow path to the combustion air holes,
A gas turbine combustor arranged such that a fuel flow passing through the combustion air hole is located substantially at the center of the axis. 3. The gas turbine combustor according to claim 2, wherein a circular brim-shaped member is provided at a tip of the fuel nozzle substantially in parallel with a wall surface on which the combustion air hole exists. 3. The gas turbine combustor according to claim 2, wherein the fuel nozzle is formed of a thick member, and air directed toward the axial center of each air passage is formed by a front end surface of the fuel nozzle and a wall surface on which the combustion air hole exists. 4. A gas turbine combustor characterized by forming a flow. A fuel supply hole for the fuel nozzle; and a combustion air hole disposed substantially coaxially with the fuel supply hole with a desired gap downstream of the fuel nozzle. Fuel from the fuel nozzle is supplied to the combustion air hole. A fuel supply method for a gas turbine combustor supplying to a combustion chamber through
Fuel is supplied to the outer peripheral side of the combustion air hole along the fuel flow so that the fuel flow passing through the combustion air hole is located substantially at the axial center of the combustion air hole. Supply method. A fuel supply hole for the fuel nozzle; and a combustion air hole disposed substantially coaxially with the fuel supply hole with a desired gap downstream of the fuel nozzle. Fuel from the fuel nozzle is supplied to the combustion air hole. A gas turbine combustion nozzle to be supplied to the combustion chamber via
A gas turbine combustion nozzle having an air flow path capable of obtaining an axial flow velocity sufficient for the fuel flow passing through the combustion air hole to be located substantially at the axial center of the combustion air hole.

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