JP2005030667A - Combustor for gas turbine and operation method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustor for a gas turbine capable of more effectively suppressing NOx. <P>SOLUTION: In this combustor, a fuel supply amount of an annular burner group positioned on the radially inner side among a plurality of radially divided annular burner groups 11A-11C is set to be smaller than the annular burner group positioned on the radially outer side. Thereby, fuel spouted from the annular burner group positioned on the radially inner side is present on the upstream side of a combustion chamber 2 as non-combusted amount, and it is combusted on the downstream side to allow sluggish progress of combustion. As a result, combustion temperature in a center part of the combustor falls to suppress generation of NOx. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas turbine combustor and a method of operating the same, and more particularly to a gas turbine combustor that individually controls a fuel supply system corresponding to each of a plurality of annular burners divided in the radial direction. Regarding the method.
[0002]
[Prior art]
Conventionally, for example, Patent Document 1 and Patent Document 2 have already proposed a combustor for a gas turbine in which a fuel supply system corresponding to each of a plurality of annular burner groups divided in a radial direction is individually controlled.
[0003]
[Patent Document 1]
JP-A-56-119423 (FIGS. 2a and 2b and description thereof)
[Patent Document 2]
JP-A-6-323543 (FIG. 4 and paragraph number 0013 of the specification)
[0004]
[Problems to be solved by the invention]
Conventional gas turbine combustors can individually control the supply of fuel to a plurality of annular burner groups, but consider more effective suppression of nitrogen oxides (hereinafter referred to as NOx). It has not been.
[0005]
The objective of this invention is providing the combustor for gas turbines which can suppress NOx more effectively.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an annular burner group in which the fuel supply amount of an annular burner group located radially inside among a plurality of annular burner groups divided into a plurality in the radial direction is located radially outward. It is less than that.
[0007]
With the above configuration, the fuel ejected from the annular burner group located on the radially inner side exists as an unburned portion upstream of the combustion chamber. This is burned while being mixed with burned gas on the downstream side, so that the combustion proceeds slowly. As a result, the combustion temperature at the center of the combustor is lowered, and the generation of NOx can be suppressed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
A gas turbine combustor according to a first embodiment of the present invention will be described below with reference to FIGS.
[0009]
The gas turbine combustor 1 is roughly divided into a combustion chamber 2 having a combustor central axis X in the combustion gas flow direction, a combustion burner 3 for injecting an air-fuel mixture into the combustion chamber 2, and fuel to the combustion burner 3. And a fuel supply system 4 to be supplied.
[0010]
The combustion chamber 2 is formed by a cylindrical combustor liner 6 that is disposed inside the outer cylinder 5 with an interval.
[0011]
The combustion burner 3 is paired with an end plate 7 that closes the upstream end of the combustor liner 6, a large number of air holes 8 provided in the end plate 7, and the air holes 8. A number of fuel nozzles 9 parallel to X and a fuel header 10 for distributing fuel to be supplied to the fuel nozzles 9 are provided.
[0012]
As shown in FIGS. 3 and 4, the multiple fuel nozzles 9 include a first fuel header 10 </ b> A, a second fuel header 10 </ b> B, and a third fuel header 10 </ b> C obtained by dividing the fuel header 10 in the radial direction Y from the inside. It is divided into a first fuel nozzle group 9A, a second fuel nozzle group 9B, and a third fuel nozzle group 9C. Then, the first annular burner group 11A and the second annular burner group are formed by the air holes 8 facing the fuel nozzles 9 of the divided first fuel nozzle group 9A, second fuel nozzle group 9B, and third fuel nozzle group 9C. 11B and the 3rd annular burner group 11C are constituted.
[0013]
On the other hand, the fuel supply system 4 includes a fuel supply pipe 12, and a first fuel supply pipe 13A, a second fuel supply pipe 13B, and a third fuel supply pipe 13C branched from the fuel supply pipe 12. The pipes 12, 13A, 13B, and 13C are respectively provided with fuel control valves 14, 15a to 15c, and the first to third fuel supply pipes 13A to 13C are provided with shut-off valves 16a to 16c. Yes.
[0014]
The air compressed by the compressor 17 is pumped between the combustor liner 6 and the outer cylinder 5 from the downstream side of the combustor liner 6 to the gas turbine combustor 1 configured as described above. A part of the pumped air flows into the combustion chamber 2 from cooling air holes (not shown) provided in the combustor liner 6, and the remaining air passes through the air holes 8 from the upstream side of the end plate 7. And flows into the uppermost stream side of the combustion chamber 2. Here, since the air hole 8 provided in the end plate 7 is arranged coaxially with the fuel nozzle 9, the fuel jet jetted from the fuel nozzle 9 is jetted into the combustion chamber 2 in a state of being wrapped in an air annular flow. However, the fuel and air mixed there form a flame and burn. Combustion gas by combustion is supplied to a gas turbine 19 coaxial with the compressor 17 via a transition piece 18 connected to the downstream side of the combustor liner 6 and imparts rotational force to the gas turbine.
[0015]
Next, a method for operating the gas turbine combustor having the above-described configuration will be described with reference to FIG. The broken line in the figure shows the change in the local fuel-air ratio with respect to 100% load from the combustor ignition. (1) is at the time of ignition, (2) is when the load is started, and (3) is at 100% load. From ignition until the load is started, the shutoff valves 16b and 16c of the second fuel supply pipe 13B and the third fuel supply pipe 13C are closed, and the shutoff valve 16a of the first fuel supply pipe 13A is opened to open the first annular burner group 11A. Operation is performed in mode I in which only the fuel is supplied to form a flame. When a load is applied in this state, the local fuel-air ratio increases, and the combustion temperature rises accordingly. Therefore, the NOx emission amount increases. In the middle of further increasing the load (4), the shutoff valve 16b of the second fuel supply pipe 13B is opened and fuel is supplied to the second annular burner group 11B in addition to the first annular burner group 11A. Operate in mode II to form. Then, since the same amount of fuel is supplied over a wide range, the formed flame spreads in the radial direction Y with respect to the combustor central axis X of the combustion chamber 2. At this time, since the local fuel-air ratio falls to (5), the combustion temperature is lowered and the NOx emission amount can be suppressed.
[0016]
Furthermore, when the load is increased, the local fuel-air ratio increases to (6). Here, the shutoff valve 16c of the third fuel supply pipe 13C is opened and fuel is supplied to the third annular burner group 11C in addition to the first annular burner group 11A and the second annular burner group 11B, and fuel is supplied from all the burners. When jetted and burned in mode III, a flame is formed throughout the downstream of the combustion chamber 2. At this time, the local fuel-air ratio decreases to (7), thereby lowering the combustion temperature and reducing NOx emission.
[0017]
Further, the operation in mode III is performed up to 100% (3) by increasing the load.
[0018]
According to the operation method described above, a single flame that spreads in the radial direction Y from the combustor central axis X can always be formed, and the temperature distribution bias at the combustor outlet can be reduced.
[0019]
In the partial load region, the local fuel-air ratio increases as shown in (4) and (6) and the combustion temperature rises depending on the conditions, which may heat the combustor liner 6 and shorten the life. is there. However, in the present embodiment, as shown in mode I and mode II, the flame formed at the time of partial load is due to the first and second annular burner groups 11A and 11B and is away from the combustor liner 6. Moreover, since there is a jet of air from the third annular burner group 11C between the combustor liner 6 and the flame to suppress the temperature rise of the combustor liner 6, it is possible to suppress a decrease in life.
[0020]
In addition, according to the present embodiment, the combustion burner 3 is divided into the first annular burner group 11A, the second annular burner group 11B, and the third annular burner group 11C in the radial direction Y with respect to the combustor axial direction X. Since the fuel can be supplied and the supply amount can be adjusted, the local fuel-air ratio in the flame can be distributed in the radial direction Y. For example, as shown in the deformation mode I in FIG. 6, the local fuel-air ratio in the second annular burner group 11B and the third annular burner group 11C is the fuel-air ratio at which the flame is stably held, The fuel-air ratio of the first annular burner group 11A can be lowered to the extent that the flame is not held in the vicinity of the first annular burner group 11A. At this time, the fuel ejected from the first annular burner group 11A exists as a large amount of unburned fuel on the upstream side of the combustion chamber 2, but it is caused by heat conduction and convection diffusion mixing with the surrounding high-temperature combustion gas. Since the heat is transferred, the combustion proceeds slowly. And finally, since the combustion reaction is completed, the emission amount of carbon monoxide and unburned hydrocarbons becomes extremely small. In this case, the combustion temperature in the central portion of the combustion chamber 2 is lowered, and the NOx emission amount can be suppressed.
[0021]
Further, for example, as shown in the deformation mode II of FIG. 7, in addition to the first annular burner group 11A, the fuel-air ratio of the second annular burner group 11B is also lowered so as not to hold the flame in the vicinity of the burner. It is also possible to perform combustion using only 11C. As described above, when the combustion is performed only by the third annular burner group 11C, the region where the combustion temperature is low increases, so that the entire NOx emission amount can be reduced. However, if the flame holding area of the flame becomes too narrow in the radial direction at this time, the stability will be lowered, and the possibility of carbon monoxide and unburned hydrocarbons being discharged due to the influence of the airflow flowing around the flame will increase. It is desirable to secure the region with a certain width in the radial direction.
[0022]
In this way, the NOx emission amount is reduced by lowering the fuel-air ratio of the first annular burner group 11A or the first annular burner group 11A and the second annular burner group 11B located inside the third annular burner group 11C. be able to.
[0023]
An operation method for the load at this time will be described with reference to FIG. The load corresponding to the local fuel-air ratio (7) to (3) is operated in mode III, and the flame is formed on the downstream front surface of the combustion burner. When the load is reduced from this point, if the fuel-air ratio is lowered as a whole, the flame is not maintained, so the mode is switched to mode II. At this time, since the local fuel-air ratio becomes large, the combustion temperature rises and a large amount of NOx is discharged. Therefore, if the fuel-air ratio of the first annular burner group 11A or the first annular burner group 11A and the second annular burner group 11B is lowered to a level that does not hold the flame and switched to the deformation mode II, the fuel flows from the front of the combustion burner. Therefore, the local fuel-air ratio is lower than that in mode II, and as a result, the combustion temperature is lowered, so that the amount of NOx emission can be suppressed. Further, since the local fuel-air ratio of the third annular burner group 11C is maintained at a value that holds the flame, the load band that can be operated with low NOx can be widened.
[0024]
Similarly, at the load corresponding to the local fuel-air ratio (5), the operation is switched from the mode II to the deformation mode I ′. In the deformation mode I ′, since the local fuel-air ratio is low and the combustion temperature is low even at the same load as in the mode I, the amount of NOx emission is smaller than in the mode I, and as a result, the load band that can be operated with low NOx is expanded. be able to.
[0025]
By the way, gas turbines having a plurality of combustors are not adjacent to each combustor by igniting each combustor by igniting each combustor, but are ignited by a specific combustor having a spark plug and then adjacent to each other. In general, high-temperature combustion gas flows into the combustor one after another through the crossfire pipe, and the adjacent combustors are ignited one after another by the heat.
[0026]
However, as shown in the first embodiment, if a large number of air holes 8 exist on the entire surface of the end plate 7 of the combustion burner 3, when only the first annular burner group 11A is ignited, its radius The air blown out from the air holes 8 of the second annular burner group 11B and the third annular burner group 11C on the outer side in the direction forms an air curtain, and this curtain of air causes the high-temperature combustion gas in the first annular burner group 11A to crossfire. There is an inconvenience that prevents the adjacent combustor from being ignited by preventing movement to the adjacent combustor through the tube.
[0027]
A second embodiment of the gas turbine combustor according to the present invention in which such inconvenience is eliminated will be described with reference to FIG.
[0028]
That is, a plurality of flame-holding regions 20 extending in the radial direction are provided in regions facing the second annular burner group 11B and the third annular burner group 11C of the end plate 7 of the combustion burner, and the flame-holding regions 20 are not shown. It was made to face the opening.
[0029]
In the flame holding region 20, for example, a region where the opening area of the air hole 8 is reduced or a region where the air hole 8 does not exist is provided so that an air curtain is not formed. As a result, the flame easily propagates to the downstream side of the flame holding region 20, and high-temperature combustion gas necessary for ignition can be introduced into the adjacent combustor from the crossfire pipe.
[0030]
FIG. 10 shows a third embodiment of the combustor for a gas turbine according to the present invention. This embodiment is a third annular shape among the air holes 8 in the second embodiment shown in FIG. A swivel angle is provided in the air hole 8C facing the burner group 11C. The swirl angle has components in the circumferential direction and the radial direction with respect to the combustor central axis X. The radial component is formed so that the jet port of the air hole 8C faces inward in the radial direction.
[0031]
Since the air hole 8C having the swirl angle as described above is formed, the jet flow ejected forms a swirl flow directed radially inward, and the jet flow of the first annular burner group 11A and the second annular burner group 11B downstream of the combustor. Mixing with is promoted.
[0032]
Normally, the flame is not held radially inward as in the deformation mode I ′ and deformation mode I in FIG. 8 described above, but by heat conduction or convection diffusion with the high-temperature combustion gas radially outside in the downstream region of the combustion chamber. In a combustion mode in which the combustion reaction of the gas mixture on the radially inner side is advanced by the transfer of heat, if sufficient mixing is not performed between the gas mixture flowing on the radially inner side and the hot combustion gas flowing on the radially outer side, Carbon oxides and unburned hydrocarbons may be emitted.
[0033]
However, according to the present embodiment, the air-fuel mixture flowing inside and outside the radial direction and the high-temperature combustion gas are sufficiently mixed by the swirl flow that is formed radially outward and faces radially inward. By sufficient mixing of this mixture and high-temperature combustion gas, heat is actively transferred and the combustion reaction of the mixture flowing radially inward is promoted, reducing the emission of carbon monoxide and unburned hydrocarbons. can do.
[0034]
FIG. 11 shows a fourth embodiment of a gas turbine combustor according to the present invention. This embodiment is a first annular shape among the air holes 8 in the second embodiment shown in FIG. A swivel angle is provided in the air hole 8A facing the burner group 11A. The swirl angle has components in the circumferential direction and the radial direction with respect to the combustor central axis X. The radial component is formed such that the jet port of the air hole 8A faces outward in the radial direction.
[0035]
Since the air hole 8A has the swirl angle as described above, the jet flow ejected from the first annular burner group 11A forms a swirl flow directed radially outward, and the second annular burner group 11B and the first Mixing of the three annular burner groups 11C with the high-temperature combustion gas is promoted. By sufficient mixing of the gas mixture inside and outside the radial direction and the high-temperature combustion gas, heat is actively transferred and the combustion reaction of the gas mixture flowing inside the radial direction is promoted, and carbon monoxide and unburned carbon Hydrogen emissions can be reduced.
[0036]
FIG. 12 shows a fifth embodiment of the gas turbine combustor according to the present invention. In this embodiment, the third annular burner group 11C is composed of two semi-annular burners 21A and 21B. A fuel supply pipe (not shown) that can be controlled separately is connected to these, and a cross fire pipe 22 is provided facing the semi-annular burner 21B out of these two semi-annular burners 21A and 21B.
[0037]
In the above configuration, at the time of ignition, fuel is supplied to the first fuel nozzle group 9A of the first annular burner group 11A, and fuel is also supplied to the third fuel nozzle group 9C of the semi-annular burner 21B. As a result, the semi-annular burner 21B has a transmission function of transmitting the high-temperature combustion gas from the first annular burner group 11A to the crossfire tube 22, and can perform crossfire well.
[0038]
Therefore, according to the present embodiment, it is not necessary to provide the flame holding region 20 as shown in FIGS. Other than that, the same operational effects as the above-described embodiments are exhibited.
[0039]
【The invention's effect】
As described above, according to the present invention, a gas turbine combustor capable of more effectively suppressing NOx can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional side view showing a first embodiment of a gas turbine combustor according to the present invention.
FIG. 2 is an enlarged view of the upstream side of the combustion chamber in FIG. 1 as viewed from the downstream side.
FIG. 3 is an enlarged perspective view showing a fuel header in FIG. 1;
4 is a perspective view in which a fuel nozzle is attached to the fuel header in FIG. 3. FIG.
FIG. 5 is an explanatory diagram showing a relationship between a local fuel-air ratio and a combustion mode during operation of the first embodiment of the gas turbine combustor according to the present invention.
6 is an explanatory diagram showing a deformation mode in FIG. 5. FIG.
FIG. 7 is an explanatory view showing another deformation mode in FIG. 5;
8 is another explanatory diagram showing the relationship between the local fuel-air ratio and the combustion mode in FIG. 5. FIG.
FIG. 9 is a view corresponding to FIG. 2 showing a second embodiment of a combustor for a gas turbine according to the present invention.
FIG. 10 is a view corresponding to FIG. 2 showing a third embodiment of a gas turbine combustor according to the present invention.
FIG. 11 is a view corresponding to FIG. 2 showing a fourth embodiment of a gas turbine combustor according to the present invention.
FIG. 12 is a view corresponding to FIG. 2 showing a fifth embodiment of a gas turbine combustor according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Gas turbine combustor, 2 ... Combustion chamber, 3 ... Combustion burner, 4 ... Fuel supply system, 7 ... End plate, 8 ... Air hole, 9 ... Fuel nozzle, 9A-9C ... 1st-3rd fuel nozzle group DESCRIPTION OF SYMBOLS 10 (10A-10C) ... Fuel header, 11A-11C ... 1st-3rd annular burner group, 12 ... Fuel supply pipe, 13A-C ... 1st-3rd fuel supply pipe, 14, 15a-15c ... Fuel control valve , 16a to 16c: shut-off valves.

Claims (7)

A plurality of burner units each having a fuel nozzle for jetting fuel and an air hole that is paired with the fuel nozzle and jets air are formed in the combustion chamber, and the plurality of burner units are arranged in a plurality of annular burners in the radial direction. In the gas turbine combustor provided with a plurality of fuel supply systems that individually control and supply the fuel supply amount to each of the divided annular burner groups, the plurality of fuel supply systems have a radius A combustor for a gas turbine, characterized in that the fuel supply amount of the annular burner group located on the inner side in the direction is set to be smaller than that of the annular burner group located on the outer side in the radial direction. The combustor for a gas turbine according to claim 1, wherein the air holes of the annular burner group located on the radially outer side have an inclination angle toward the radially inner side on the downstream side. The combustor for a gas turbine according to claim 2, wherein the air hole has a turning angle in a circumferential direction. The combustor for a gas turbine according to claim 1, wherein the air holes of the annular burner group located radially inward have a turning angle in the circumferential direction. A plurality of burner units each having a fuel nozzle for jetting fuel and an air hole that is paired with the fuel nozzle and jets air are formed toward the combustion chamber, and the plurality of burner units are arranged in a plurality of annular burners in the radial direction. And a gas turbine combustor provided with a plurality of fuel supply systems that individually control and supply a fuel supply amount to each of the plurality of divided annular burner groups. The fuel supply amount of the annular burner group located on the inner side in the direction is set to be smaller than that of the annular burner group located on the outer side in the radial direction, and a flame propagation area is provided across the plurality of annular burner groups in the combustion chamber. A combustor for a gas turbine. A plurality of burner units each having a fuel nozzle for jetting fuel and an air hole that is paired with the fuel nozzle and jets air are formed toward the combustion chamber, and the plurality of burner units are arranged in a plurality of annular burners in the radial direction. In the operating method of a combustor for a gas turbine provided with a plurality of fuel supply systems that supply the fuel supply amount to each of the divided annular burner groups by individually controlling the fuel supply amount. A method for operating a combustor for a gas turbine, characterized in that less fuel is supplied to an annular burner group than to an annular burner group located radially outward. A plurality of burner units each having a fuel nozzle for jetting fuel and an air hole that is paired with the fuel nozzle and jets air are formed toward the combustion chamber, and the plurality of burner units are arranged in a plurality of annular burners in the radial direction. And a method for operating a combustor for a gas turbine provided with a plurality of fuel supply systems that individually control and supply a fuel supply amount to each of a plurality of divided annular burner groups. An operation method of a combustor for a gas turbine, characterized in that fuel is sequentially increased from a fuel nozzle of an annular burner group positioned radially inside to a fuel nozzle of an annular burner group positioned radially outward.

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