JP2013064563A - Gas turbine combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas turbine combustor which appropriately mixes fuel and combustion air and reduces NOx emission.SOLUTION: A combustor burner includes: a fuel nozzle 26 for jetting the fuel to a combustion chamber; a center rod 24 arranged on a center axis of the fuel nozzle; and air holes 27 for supplying the combustion air introduced from a compressor into the fuel nozzle. The air holes 27 are formed so that the combustion air is jetted toward the axial center side of a center rod. Further, the fuel nozzle 26 has: a channel for streaming the fuel at lower temperature compared to the combustion air to outer side than the center rod and the inside thereof; and a space 23 defined by an inner wall of the fuel nozzle and a downstream side end face of the center rod and communicating with the air holes and the combustion chamber, wherein the downstream end of the center rod is arranged as covering at least a part of the air holes communicating with the space, and the opening area of the air holes communicating with the space changes due to a thermal expansion difference between the fuel nozzle and the center rod.

Description

  The present invention relates to a gas turbine combustor that suppresses NOx emissions.

  In recent years, fuel gas temperature tends to be increased while high output and high efficiency are required for a gas turbine plant. When the temperature of the fuel gas increases, the concentration of nitrogen oxide (hereinafter referred to as NOx) in the exhaust gas increases. Therefore, also in the gas turbine combustor, the reduction of NOx emission is one of the important technical issues from the viewpoint of protecting the global environment.

  There is a premixed combustion method as a NOx reduction method in a gas turbine combustor. Premixed combustion is a combustion system in which fuel and air are mixed in advance in a premixer provided in a gas turbine combustor and supplied to the combustion chamber of the gas turbine combustor for combustion. By configuring the gas turbine combustor to perform premix combustion, it is possible to reduce the thermal NOx concentration in the generated fuel gas by suppressing the generation of a local high temperature region in the combustion chamber of the gas turbine combustor. .

  As a conventional method for reducing NOx in a gas turbine combustor, the amount of combustion air is increased as the load increases in the low load operation region, and the amount of combustion air is increased as the load increases in the high load operation region. Some have a combustion air regulating valve that operates to decrease. (For example, refer to Patent Document 1).

JP-A-6-281145

  Environmental regulations tend to be stricter, and a gas turbine combustor with reduced NOx generation is required. In that case, if a structure such as a combustion air control valve is provided, the structure becomes complicated, which may increase the cost and make the mechanism adjustment complicated.

  Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a gas turbine having a reduced NOx emission amount without complicating the structure.

  Inside the burner of the gas turbine combustor, the temperature of each part inside the burner may differ depending on the operation state of the combustor, and a difference in thermal expansion occurs between the parts. The principle of the present invention is to use this difference in thermal expansion to adjust the amount of combustion air introduced into the combustor burner so as to achieve an appropriate mixing state with fuel.

  Therefore, in the present invention, in a gas turbine combustor that mixes and burns fuel with combustion air introduced from a compressor and supplies the generated combustion gas to a turbine, a fuel nozzle that jets fuel into the combustion chamber, and the fuel A combustor burner comprising a center rod disposed on a central axis of a nozzle and an air hole for supplying combustion air introduced from the compressor into the fuel nozzle, wherein the air hole The fuel nozzle is formed so that a jetting direction is directed toward the axial center side of the center rod, and the fuel nozzle is disposed on the inside and outside the center rod. And a space formed by the downstream end surface of the center rod and communicating with the air hole and the combustion chamber, and the downstream end of the center portion covers at least a part of the air hole communicating with the space. Are arranged to, by differential thermal expansion of the fuel nozzle and the central rod, characterized by being configured to vary an opening area of said space and communicating with the air hole.

  According to the present invention, it is possible to provide a gas turbine combustor with low NOx without complicating the structure.

1 is an overall configuration diagram of a gas turbine plant including a gas turbine combustor according to Embodiment 1. FIG. 1 is a side sectional view of a combustor burner at the time of starting a gas turbine according to Embodiment 1. FIG. 3 is a side sectional view of the combustor burner during gas turbine rated operation of the first embodiment. FIG. 4 is a side sectional view of a combustor burner according to a second embodiment. FIG. 6 is a side sectional view of a combustor burner according to a third embodiment.

  Embodiments of the present invention will be described below.

  FIG. 1 is an overall configuration diagram of a gas turbine plant including a gas turbine combustor according to a first embodiment of the present invention. As shown in FIG. 1, a gas turbine plant compresses air to generate high-pressure combustion air, and mixes combustion air and fuel introduced from the compressor 1 to generate combustion gas. A combustor 3 and a turbine 2 that supplies combustion gas generated by the combustor 3 are provided. In addition, the compressor 1 and the turbine 1 are connected by the rotating shaft.

  The combustor 3 ejects fuel from the fuel nozzle 26, ejects combustion air from the air holes 27, and then generates a combustion chamber 6 that generates combustion gas that has been mixed and combusted; a liner 7 that forms the combustion chamber 6 therein; A transition piece 8 that guides the combustion gas 101 from the liner 7 to the turbine 2, an outer cylinder 9 that houses and seals the combustion nozzle 26, the liner 7, and the transition piece 8, and an upstream end of the combustor 3 A cover 10, an ignition plug 11 that is supported by the outer cylinder 9 and ignites the mixed gas 100 of combustion air 22 and fuel in the combustion chamber 6, and a fuel system 12 that supplies fuel to the fuel nozzle 26. In this embodiment, the direction of the fuel nozzle 26 from the combustion chamber 6 is the upstream side, and the direction of the liner 7 is the downstream side.

  2 and 3 are detailed sectional views of the combustor burner shown in FIG. In this embodiment, the fuel is introduced into the air hole 27 of the fuel nozzle 26, and the combustion air and the fuel are mixed inside the air hole 27. The fuel 21 is supplied to the outer peripheral portion of the center rod 24 by a labyrinth seal 25 at the burner upstream portion.

  The state shown in FIG. 2 is when the gas turbine is started, and a space 23 is formed between the center rod 24 and the combustion chamber 6, and the center rod 24 is disposed so as to cover a part of the upstream opening of the air hole 27. ing.

  Next, during rated operation of the gas turbine, the fuel 21 is typically 20-60 ° C and the compressed combustion air 22 is typically 380-420 ° C. The fuel gas adjusted by the labyrinth seal 25 installed upstream flows in the outer peripheral portion of the center rod 24. Therefore, the center rod 24 is kept at a low temperature by the fuel gas 21. On the other hand, the burner wall surface 28 is in a high temperature state due to the combustion air 22 flowing outside the burner. Due to the temperature difference between the burner wall surface 28 and the center bar 24, a thermal expansion difference occurs due to thermal expansion. Between the low-temperature center rod 24 and the high-temperature burner wall surface 28, the burner wall surface 28 extends in the downstream direction. Therefore, the state of FIG. 2 changes to the state of FIG.

  By changing from the state of FIG. 2 to the state of FIG. 3, the opening area of the air hole 27 is increased, and the amount of combustion air introduced into the space 23 is increased. Therefore, the fuel / air mixture ratio can be made lean in the rated operation state of the gas turbine, and NOx reduction can be achieved.

  According to this embodiment, when starting a gas turbine having a low combustion temperature, the amount of air used for combustion is reduced, the amount of combustion air is increased during rated operation, and combustion air and fuel are mixed appropriately. Therefore, NOx reduction can be achieved. That is, the temperature of each part in the burner varies depending on the operating state of the combustor, and the amount of combustion air introduced into the combustor burner is adjusted using the difference in thermal expansion based on this, so that the fuel and appropriate mixing state It becomes possible to. As a result, the NOx emission amount can be suppressed without complicating the structure.

  FIG. 4 shows a side sectional view of a combustor burner that is a second embodiment of the present invention. In the first embodiment, the fuel 21 is supplied to the outer peripheral portion of the center rod 24 by the labyrinth seal 25 in the burner upstream portion, whereas in this embodiment, the low temperature air is supplied to the inner peripheral portion of the center rod 24. 29 has been introduced.

  As in the first embodiment, the introduced low-temperature air 29 is generally around 15 ° C., and the center rod 24 is kept at a lower temperature than the combustion air 22 in the rated operation state. On the other hand, the burner wall surface 28 is in a high temperature state due to the combustion air 22 flowing outside the burner. Therefore, between the low-temperature center rod 24 and the high-temperature burner wall surface 28, the burner wall surface 28 thermally expands in the downstream direction, whereby the area of the air hole 27 changes. The low temperature air 29 may be supplied to both the outer peripheral side of the center bar or the inside of the center bar.

  According to the present embodiment, since the cooler low-temperature air 29 is supplied into the center bar 24, the center bar 24 can be maintained at a lower temperature. As a result, the amount of combustion air introduced into the combustor burner is adjusted using the difference in thermal expansion based on the temperature difference between the low temperature air 29 supplied into the center rod 24 and the combustion air 22 flowing outside the burner. Can be mixed with the fuel properly.

  FIG. 5 is a cross-sectional side view of a combustor burner showing a third embodiment of the present invention. In this embodiment, a plurality of combustor burners of FIG. 1 are arranged.

  The burner disposed at the center and the burners disposed at the periphery are disposed so that the area where the center rod 24 overlaps with a part of the upstream opening of the air hole 27 is different. In the illustrated example, the air hole 27 of the burner arranged around the burner arranged at the center is configured to have a larger opening area (smaller area of the air hole covered by the center bar). Yes. In the fuel system, the central burner and the surrounding burners have different fuel systems, and the fuels 41 and 42 are supplied independently.

  With this structure, even when a plurality of burners having different mixing ratios of fuel and combustion gas are arranged in the combustor, by changing the length of the center rod 24 by the burner, appropriate combustion can be performed in each burner. By mixing air and fuel, the NOx can be further reduced as a combustor.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Turbine 3 Combustor 6 Combustion chamber 7 Liner 8 Transition piece 9 Outer cylinder 10 Cover 11 Spark plug 12 Fuel system 21, 41, 42 Fuel 22 Combustion air 23 Space 24 Center rod 25 Labyrinth seal 26 Fuel nozzle 27 Air hole 28 Burner wall surface 29 Low temperature air 100 Mixed gas 101 Combustion gas

Claims (7)

In a gas turbine combustor that mixes and burns fuel into combustion air introduced from a compressor and supplies the generated combustion gas to a turbine.
Combustion comprising a fuel nozzle for injecting fuel into the combustion chamber, a center rod arranged on the center axis of the fuel nozzle, and an air hole for supplying combustion air introduced from the compressor into the fuel nozzle A vessel burner,
The air hole is formed such that the direction of ejection of combustion air is directed toward the axial center side of the center rod,
The fuel nozzle is formed by a flow path through which fuel having a temperature lower than that of the combustion air flows inside and outside the center rod, an inner wall of the fuel nozzle, and a downstream end face of the center rod. A space communicating with the combustion chamber, and a downstream end of the central portion is disposed so as to cover at least a part of the air hole communicating with the space,
A gas turbine combustor configured to change an opening area of an air hole communicating with the space by a difference in thermal expansion between the fuel nozzle and the center rod. A gas turbine combustor according to claim 1,
A gas turbine combustor, wherein fuel is circulated through a flow path formed by a gap between an outer peripheral side of the center rod and an inner peripheral side of the fuel nozzle. A gas turbine combustor according to claim 1,
A gas turbine combustor, wherein air having a temperature lower than that of the combustion air is supplied to the inside of the center rod or to the outer periphery thereof. A gas turbine combustor according to claim 2,
A gas turbine combustor, wherein the fuel supplied to the fuel nozzle is branched into the fuel nozzle and the flow path to supply the fuel. A gas turbine combustor according to claim 4,
A gas turbine combustor comprising a labyrinth seal provided upstream of the flow path. A gas turbine combustor according to any one of claims 1 to 5,
A gas turbine combustor comprising a plurality of the combustor burners arranged at the center of the combustor and the outer periphery thereof. A gas turbine combustor according to claim 6,
The gas turbine combustor characterized in that the area of the air hole covered by the center rod in the combustor burners on the center side and the outer periphery side is made different.