JP2729748B2 - Gas turbine combustion method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a combustion method and a device suitably used as a combustor in a land-based gas turbine engine.

[0002]

2. Description of the Related Art As one of conventional combustion methods for a gas turbine, as shown in FIG. 6, a plurality of combustion chambers 50 are provided at an inlet portion of a combustion chamber 50 at predetermined intervals in a circumferential direction thereof. While the fuel injection nozzles 51 are arranged circumferentially, a combustion air hole 53 and a dilution air hole 54 are provided at predetermined positions in the peripheral wall of a combustion cylinder 52 constituting the combustion chamber 50 at predetermined intervals in the axial direction. The fuel F is injected from the plurality of cylindrically arranged fuel injection nozzles 51 into the combustion chamber 50 using the combustion device provided with the combustion air, and the combustion air A1 is discharged from the combustion air holes 53. The two are mixed and burned by being supplied into the combustion chamber 50, and the temperature distribution at the outlet of the combustion chamber 50 is adjusted by the dilution air blown into the combustion chamber 50 through the dilution air hole 54. Things are known.

As another example of a gas turbine combustion method, particularly as an example of a low NOx combustion method, as shown in FIG. 8, the number of fuel injection nozzles 51 for injecting fuel F into a combustion chamber 50 is reduced. In many cases, these fuel injection nozzles 51
Are classified into ignition nozzles 51a and rated combustion nozzles 51b. Further, in order to enhance the reduction of NOx, combustion air holes 53 provided at several places at predetermined intervals in the axial direction on the peripheral wall of the combustion cylinder 52 and By using a combustion device provided with a variable valve 55 capable of changing the opening degree of the dilution air hole 54 among the dilution air holes 54, the opening degree of the variable valve 55 is increased at the time of ignition, and The amount of air supplied from the air holes 53 into the combustion chamber 50 is reduced by reducing the amount of air supplied from the air holes 53 into the combustion chamber 50 and reducing the opening of the variable valve 55 during rated combustion. By increasing the number, there has been proposed a method in which the required combustion amount at the time of rating is ensured while improving the ignitability. This proposal is based on Technical Document A
SME (THE AMERICAN SOCIETY OF MECHANICAL ENGI-NE
ERS), 81-GT-40, pp. 1-3, PBRoberts
It was announced in 1981.

[0004]

However, among the above-mentioned conventional combustion methods for gas turbines, the former combustion method using a combustion device as shown in FIG. 6 realizes a reduction in NOx and an increase in temperature. For this purpose, a large amount of air is required to be supplied from the combustion air holes 53 into the combustion chamber 50, so that the amount of air supplied from the dilution air holes 54 is insufficient.
As shown in FIG. 7B, a large fuel distribution occurs in the circumferential direction between a portion corresponding to each fuel injection nozzle 51 and a portion other than the fuel injection nozzle 51, and as a result, a large temperature distribution as shown in FIG. Occurs and the outlet temperature distribution also increases. Further, due to the large temperature distribution in the combustion chamber 50, FIG.
The hatched portion in (B) becomes a local high temperature region, and NOx
The amount increases.

In the case of the latter combustion method using a combustion device as shown in FIG. 8, the amount of air supplied from the combustion air holes 53 into the combustion chamber 50 at the time of ignition is reduced, so that ignitability is improved. On the other hand, since the air velocity is low, the atomization of the fuel is poor and the combustion efficiency is deteriorated. Also,
As the amount of air supplied from the combustion air holes 53 into the combustion chamber 50 increases during rated combustion, the dilution air holes 5
4 decreases, and the distribution of the outlet temperature of the combustion chamber 50 deteriorates. In addition, the dilution air hole 54 exists in a high temperature range, and the relative position between the variable valve 55 and the dilution air hole 54 changes with thermal expansion and contraction. Adjustment of the air supply amount by opening control is very difficult, and there is a disadvantage that the stable combustion range is narrow.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and enables stable combustion to be performed over a wide range from ignition to rated combustion, uniform fuel distribution and outlet temperature distribution, and lean combustion. It is an object of the present invention to provide a gas turbine combustion method and an apparatus thereof that can suppress the amount of NOx generated due to NOx and greatly reduce NOx emissions.

Another object of the present invention is to provide a combustion device for a gas turbine which can shorten the overall length of the gas turbine and simplify the structure.

[0008]

In order to achieve the above-mentioned main object, a combustion method for a gas turbine according to the invention of claim 1 is provided.
Each of the combustion air and the fuel is passed through a plurality of circumferentially defined passages formed between adjacent ones of a plurality of swirling vanes arranged at predetermined intervals in a circumferential direction at an inlet portion of the combustion chamber. A method of supplying and combusting, at the time of ignition, of the plurality of partitioned passages, the combustion air and fuel are supplied to the combustion chamber only from the partitioned passages located at predetermined intervals in the circumferential direction and ignited, At the time of rated combustion, combustion air and fuel are supplied into the combustion chamber from all of the plurality of partitioned passages to perform combustion.

According to a second aspect of the present invention, there is provided a combustion apparatus for a gas turbine, wherein a plurality of swirling blades are fixedly arranged at a predetermined interval in a circumferential direction at an inlet of the combustion chamber, and the adjacent fixed swirling blades are arranged adjacent to each other. A plurality of partition passages are formed in a circumferential direction between the plurality of partition passages, and an air flow path for supplying combustion air toward the partition passages is provided, and a fuel injection nozzle is disposed in each of the partition passages. A variable valve is provided at the entrance of each of a plurality of passages located in the circumferential direction at predetermined intervals in the passage so that the degree of opening of each of the passages is closed during ignition and opened during rated combustion.

According to a third aspect of the present invention, there is provided a combustion apparatus for a gas turbine according to the third aspect of the present invention, wherein the combustion tube constituting the combustion chamber has heat resistance. A cooling air passage is formed on the outer periphery of the combustion cylinder, and a compressor outlet of the gas turbine disposed upstream of the combustion chamber and the combustion cylinder are separated from the compressor. The air is directly connected to the partition passage and the cooling air passage via the fixed swirling vane portion.

[0011]

According to the first and second aspects of the present invention, a plurality of partitioned passages are formed between adjacent ones of a plurality of swirling vanes arranged at predetermined intervals in a circumferential direction at an inlet of the combustion chamber. Since the combustion air and the fuel are uniformly distributed in the circumferential direction and supplied through the combustion chamber, the fuel distribution in the circumferential direction becomes uniform, and the outlet temperature of the combustion chamber is also adjusted uniformly in the circumferential direction. . Further, since the temperature distribution is made substantially flat by the circumferential uniform combustion in the combustion chamber and a local high temperature region is not formed, the emission of NOx is remarkably reduced in combination with the lean and uniform combustion of the fuel. In addition, at the time of ignition, by supplying combustion air and fuel to the combustion chamber only from the partition passages located at predetermined intervals in the circumferential direction, it is possible to reduce the amount of air while keeping the air flow rate constant, Good ignitability, and by supplying combustion air and fuel from all compartment passages into the combustion chamber during rated combustion, it is possible to increase the amount of air while maintaining a constant flow velocity, By improving the distribution, NOx can be reduced by lean combustion.

Further, according to the third aspect of the present invention, since the combustion cylinder constituting the combustion chamber is made of a heat-resistant material, the amount of air required for cooling the combustion cylinder may be small.
Therefore, when a compressor outlet disposed upstream of the combustion chamber is directly connected to a combustion cylinder and combustion is performed using air from the compressor as combustion air, the gas turbine rating may fluctuate. Therefore, even if the distribution of the amount of air from the compressor changes, the ratio of the amount of air supplied to the combustion chamber is maintained due to the rectification effect of the directly connected fixed swirling vanes,
It is possible to eliminate combustion instability. Therefore, the fixed swirling vane portion can be used also as a diffuser, and the overall length can be reduced and the structure can be simplified.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing a combustion apparatus for realizing a gas turbine combustion method according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an annular combustion cylinder, in which a combustion chamber 1A is provided. Is formed. A plurality of supply holes 3 for dilution air A2 are provided on the outer peripheral wall of the combustion cylinder 1 and an inlet 4 of the combustion chamber 1A is
As shown in FIGS. 2 and 3, a plurality of plate-shaped swirling blades 5 are fixedly arranged at predetermined intervals in a circumferential direction, and a combustion air A1 is provided between each adjacent swirling blade 5. A plurality of partition passages 6 are formed to guide the swirl and supply it into the combustion chamber 1A.

Reference numeral 7 denotes an air flow path for supplying air A to the partition passage 6, and the air A supplied to the flow path 7
Is supplied in a circumferential direction to the combustion chamber 1A through the plurality of partition passages 6 as the combustion air A1 while being supplied to the combustion chamber 1A through the supply holes 3 as the dilution air A2. It is blown and supplied. Numeral 8 denotes fuel supply pipes radially inserted from the outside in a substantially central portion of each of the partition passages 6. On / off valves 11 are interposed at the base end sides of these fuel supply pipes 8, and A fuel injection nozzle 9 for injecting the fuel F into the combustion chamber 1A through each of the partition passages 6 is formed at the distal end.

Of the plurality of partitioned passages 6, one in the circumferential direction.
At the entrances of the partition passages 6A positioned every other, variable valves 10 that can be opened and closed with the center of the width of each of the partition passages 6A as a fulcrum are provided. The opening of 6A is adjustable.

Next, a description will be given of the combustion operation of the gas turbine combustion apparatus having the above-described configuration. First, at the time of ignition, the on-off valve 11 on the base end side of the fuel supply pipe 8 inserted in the partition passage 6A positioned every other in the circumferential direction is closed, and the fuel from the corresponding fuel injection nozzle 9 is closed. While stopping the injection, the variable valve 10 is closed to stop the supply of the combustion air from each of the partition passages 6A. In this state, the fuel F injected from the fuel injection nozzle 9 is supplied into the combustion chamber 1A through the partition passage 6, while the fuel A flowing through the air flow path 7 is partially open. The air is supplied to the combustion chamber 1A as combustion air A1 only through the passage 6. Thereby, the supply amount of the combustion air A1 is small,
In addition, since the flow velocity is maintained at a high speed, the fuel F is finely atomized and reliable ignition can be performed.

After the ignition as described above, the on-off valves 11 corresponding to the partition passages 6A are opened to inject the fuel F from all the fuel injection nozzles 9, and the variable valves 10 are opened to open the air. A part of the air A flowing through the flow path 7 is supplied as combustion air A1 into the combustion chamber 1A through all the partition passages 6 and 6A. As a result, the supply amount of the combustion air A1 is large, and the flow velocity thereof is maintained at a high speed. Therefore, while the atomization of the fuel F is favorably maintained, the stability of the rated combustion is improved by the improvement of the mixing property accompanying the swirl. It is possible to plan.

At the time of the rated combustion, FIG.
As shown in (A), the fuel F and the combustion air A1 are uniformly supplied in the circumferential direction into the combustion chamber 1A from all of the plurality of partition passages 6 and 6A. The effective uniform volume utilization can be achieved by the circumferential uniform combustion, and a uniform temperature distribution in the circumferential direction can be obtained as shown in FIG. 4 (B). While maintaining high combustion efficiency, NOx reduction can be achieved in combination with uniform outlet temperature distribution and lean and uniform combustion of fuel.

FIG. 5 is a schematic sectional view showing a combustion apparatus for a gas turbine according to another embodiment of the present invention, in which the combustion tube 1 constituting the combustion chamber 1A is heat-resistant such as FRC (fiber reinforced ceramics). And a cooling air passage 12 formed on the outer periphery of the combustion cylinder 1A.
The compressor outlet and the combustion cylinder 1 are directly connected via an air supply unit 5A including the fixed swirl vanes 5, and in this embodiment, compressed air A discharged from the compressor is discharged. The partition passages 6, 6A and the cooling air passage 1
2 and functions as a gas turbine combustion device.

In the combustion apparatus for a gas turbine having the structure shown in FIG. 5, the combustion tube 1 is made of a heat-resistant material, and the cooling air passage 12 is used to cool the combustion tube 1.
Since the amount of air to be diverted into the air supply unit may be small, it is easy to use the air supply unit 5A also as a diffuser. That is, the distribution of the amount of air from the compressor often changes with a change in the rating (output ratio) of the gas turbine. Therefore, if the combustion apparatus has a configuration that requires a large amount of cooling air for cooling the combustion cylinder 1, the amount of combustion air also fluctuates with the fluctuation of the rating (output ratio) of the gas turbine. , The combustion itself tends to be unstable. Therefore, even if the amount of air from the compressor fluctuates,
In order to maintain a sufficient ratio of the cooling air amount and the combustion air amount, a sufficient distance is required between the air supply unit 5A and the diffuser, and the overall length becomes long. On the other hand, according to the embodiment of FIG. 5, since the amount of cooling air may be small, even if the distribution of the amount of air from the compressor changes, the combustion chamber is rectified by the directly connected fixed swirl vanes. It is possible to eliminate the instability of combustion by maintaining the air supply rate within 1A. Therefore, the air supply portion 5A, which is a fixed swirling blade portion, can also be used as a diffuser, thereby shortening the overall length and simplifying the structure.

The variable valve 10 is not limited to the one shown in the above embodiment, but may be any other variable as long as it can adjust the opening of the partition passage 6A. Is also good.

[0022]

As described above, claims 1 and 2 are as described above.
According to the invention, combustion air and fuel are introduced into the combustion chamber through a plurality of partition passages formed between adjacent ones of the plurality of swirling vanes arranged at predetermined intervals in the circumferential direction at the inlet of the combustion chamber. In order to distribute and supply the fuel uniformly in the circumferential direction, not only the fuel distribution in the circumferential direction but also the outlet temperature of the combustion chamber can be uniformly adjusted in the circumferential direction. In addition, since the temperature distribution is made substantially flat by uniform circumferential combustion in the combustion chamber and no local high-temperature region is formed, it is possible to significantly reduce NOx emissions in combination with the lean and uniform combustion of fuel. it can. Furthermore, at the time of ignition, by supplying combustion air and fuel into the combustion chamber only from the partition passages located at predetermined intervals in the circumferential direction, the air flow rate is maintained at a high speed, and the atomization of the fuel is maintained satisfactorily. Since it is possible to reduce the amount of air, it is excellent in ignitability, and at the time of rated combustion, by supplying combustion air and fuel from all the compartment passages into the combustion chamber, the flow velocity is kept high, Since it is possible to increase the amount of air while maintaining good fuel atomization as in the case of ignition, low NOx due to lean combustion
This makes it possible to stabilize the temperature and to achieve a uniform temperature distribution.

Further, according to the third aspect of the present invention, the combustion cylinder constituting the combustion chamber is made of a heat-resistant material to reduce the amount of air necessary for cooling the combustion cylinder. When a compressor outlet arranged upstream of the combustion chamber is directly connected to a combustion cylinder and combustion is performed using air from the compressor as combustion air, the compression is performed in accordance with fluctuations in the gas turbine rating. Even if the distribution of the amount of air from the machine changes, the ratio of the amount of air supplied to the combustion chamber can be maintained, and the instability of combustion can be eliminated. As a result, the fixed swirl vane portion can also be used as a diffuser, and the overall length can be reduced and the structure can be simplified.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a gas turbine combustion device for realizing a gas turbine combustion method according to an embodiment of the present invention.

FIG. 2 is an enlarged front view of a main part viewed from an arrow X direction in FIG.

FIG. 3 is an enlarged plan view of a main part viewed from an arrow Y direction in FIG. 1;

FIG. 4A is a plan view of a main part explaining a distribution state of fuel and combustion air, and FIG. 4B is a plan view of a main part explaining a temperature distribution state.

FIG. 5 is a schematic sectional view showing a gas turbine combustion apparatus according to another embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view of a combustion device used to carry out one of the conventional gas turbine combustion methods.

FIG. 7 shows a combustion state by the combustion device of FIG. 6, and (A)
FIG. 2 is a plan view of a main part illustrating a distribution state of fuel and combustion air, and FIG. 2B is a plan view of a main part illustrating a temperature distribution state.

FIG. 8 is a schematic cross-sectional view of a combustion device used to carry out another conventional combustion method for a gas turbine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustion cylinder 1A Combustion chamber 5 Swirling blade 5A Air supply part (fixed swirling blade part) 6, 6A Partition passage 7 Air flow path 9 Fuel injection nozzle 10 Variable valve 12 Cooling air passage A1 Combustion air F Fuel

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-48-73607 (JP, A) JP-A-4-203710 (JP, A)

Claims (3)

(57) [Claims] 1. A plurality of circumferentially divided passages formed between adjacent ones of a plurality of swirling vanes which are arranged at predetermined intervals in a circumferential direction at an inlet portion of a combustion chamber, respectively, for combustion air and fuel. And supplying the combustion air and fuel into the combustion chamber only from the plurality of the divided passages which are located at predetermined intervals in the circumferential direction at the time of ignition. Let it ignite, and
A combustion method for a gas turbine, wherein combustion is performed by supplying combustion air and fuel from all of the plurality of partitioned passages into a combustion chamber during rated combustion. 2. A plurality of swirling vanes are fixedly arranged at a predetermined interval in a circumferential direction at an inlet portion of a combustion chamber, and a plurality of partitioned passages are formed in a circumferential direction between adjacent fixed swirling blades. ,
In addition to providing an air flow path for supplying combustion air toward the partition passage, a fuel injection nozzle is disposed in each of the partition passages, and a predetermined number of the plurality of partition passages are located in the circumferential direction. A combustion device for a gas turbine, characterized in that a variable valve is provided at an inlet of a partition passage to change the opening of each of the partition passages to closed at the time of ignition and to open at the time of rated combustion. 3. A combustion tube constituting the combustion chamber is made of a heat-resistant material, a cooling air passage is formed on an outer periphery of the combustion tube, and a gas disposed upstream of the combustion chamber. The compressor outlet of the turbine and the combustion cylinder are directly connected via the fixed swirl vanes so as to divert air from the compressor to the partition passage and the cooling air passage. The combustion device for a gas turbine according to claim 2, wherein