JP2002061841A - Combustor, gas turbine and jet engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of NOx and contrive the decrease in the vibration of combustion in a combustor, and permit stable operation in a gas turbine and jet engine. SOLUTION: A pilot cone 17 is provided with an equal diameter portion 17b continuously with an enlarged diameter portion 17a that is the same as the conventional, and thereby the diffusion of the combustion gas flowing along the inside surface of the pilot cone 17 to the circumference is suppressed by the equal diameter portion 17b, so as to avoid the major impingement between the combustion gas and the air flow from a main burner 13 and reduce the turbulence of the air flow in the rear side of a combustor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a combustor capable of reducing combustion oscillation, and further relates to a gas turbine and a jet engine provided with the combustor.

[0002]

2. Description of the Related Art In recent years, with increasing interest in environmental issues, there has been a demand for reduction of emissions of nitrogen oxides (hereinafter, NOx) and the like. Therefore, various researches and developments on a gas turbine and a jet engine, particularly on a combustor, are being advanced.

For example, in a premix type combustor,
It is known that making the mixing ratio of fuel gas and air uniform is effective in reducing NOx. If the mixture ratio is not uniform, the flame in the region where the fuel gas concentration is high becomes locally high in temperature, and generates a large amount of NOx.

FIG. 6 shows an example of a conventional gas turbine combustor. In the figure, reference numeral 1 denotes a combustion cylinder, 2 denotes a pilot burner, and 3 denotes a main burner. A plurality of main burners 3 are arranged inside the combustion cylinder 1 so as to surround the pilot burner 2.

At the tip of the pilot burner 2, a pilot cone 5 is provided so as to cover the periphery of the pilot nozzle 4, and at the tip of the main burner 3, an extension pipe 7 is provided to cover the periphery of the main nozzle 6. . The pilot cone 5 is formed in a funnel shape whose diameter increases toward the rear end.

In the above-described gas turbine combustor, by arranging a plurality of main burners 3 so as to surround the pilot burner 2, the fuel gas ejected from the pilot burner 2 and the air ejected from the main burner 3 are reduced. Are made uniform.

Here, the process of combustion in the gas turbine combustor will be described. First, air compressed by a compressor (not shown) flows into the combustion cylinder 1 from the base end of each burner to the tip. Flows. Pilot burner 2
Is mixed with fuel in the pilot nozzle 4 and then ignited by a pilot flame (not shown) and burned. At this time, a part of the combustion gas flows along the inner side surface of the pilot cone 5, and is ejected so as to be diffused around with a flame, so that the main burner 3 is ignited.

The air flow flowing along each of the main burners 3 is mixed with fuel in the main nozzle 6 and then ignited by a flame which is jetted along the pilot cone 5 to be jetted backward as a combustion gas.

[0009]

In the above-described gas turbine combustor, the flow of air from the main nozzle 6 and the flow of combustion gas along the pilot cone 5 collide with each other. It causes combustion vibration.

Such combustion vibration propagates as a pressure wave and resonates the acoustic system composed of the combustion cylinder and the casing of the gas turbine, which may increase the internal pressure fluctuation, which may make normal operation of the gas turbine difficult. There is. Such a phenomenon can occur in a jet engine including a combustor having the above-described configuration.

The present invention has been made in view of the above circumstances, and has as its object to suppress the generation of NOx in a combustor and reduce combustion vibration, thereby enabling stable operation in a gas turbine or a jet engine. And

[0012]

As means for solving the above-mentioned problems, a combustor, a gas turbine and a jet engine having the following structures are employed. That is, in the combustor according to claim 1 of the present invention, a pilot burner, a plurality of main burners arranged so as to surround the pilot burner, and a combustion provided at a tip of the pilot burner and ejected from the pilot burner. A pilot cone for diffusing gas to the surroundings is provided, and the pilot cone has an enlarged portion that gradually increases in diameter in a direction in which the combustion gas is ejected, and a diameter substantially continuous from the enlarged portion in the ejection direction. An equal diameter portion is formed.

In this combustor, by providing an equal-diameter portion continuously to the enlarged-diameter portion, the combustion gas flowing along the inner surface of the pilot cone is distributed to the surrounding by the equal-diameter portion continuous to the enlarged-diameter portion. Since the diffusion is suppressed, a large collision with the airflow from the main burner does not occur, and the turbulence of the airflow behind the combustor is reduced. When the equal diameter portion is longer than the enlarged diameter portion, the diffusion of the combustion gas to the surroundings is drastically reduced, and the main burner is not ignited. Therefore, the length of the equal diameter portion is appropriately set in consideration of this point.

According to a second aspect of the present invention, there is provided the combustor according to the first aspect, wherein a cutout portion is formed in the equal diameter portion.

In this combustor, the combustion gas is ejected outward from the notch, and plays a role as a fire source to the main burner. This makes it possible to satisfactorily ignite the main burner while preventing the collision between the combustion gas and the airflow from the main burner by making the equal-diameter portion longer.

According to a third aspect of the present invention, in the combustor according to the second aspect, the cutouts are individually formed at positions corresponding to the respective main burners.

In this combustor, the cutouts are individually formed at positions corresponding to the respective main burners, so that the ignition of the respective main burners can be performed satisfactorily.

According to a fourth aspect of the present invention, in the gas turbine, a compressor for compressing the air, and the combustor according to the first, second or third aspect of combusting the air compressed in the compressor, and jetting from the combustor. And a turbine driven by expansion of the combustion gas.

In this gas turbine, combustion oscillation is reduced by employing the combustor having the above-described configuration. Thereby, resonance of the acoustic system including the casing of the combustor and the gas turbine is prevented.

According to a fifth aspect of the present invention, there is provided a jet engine comprising: a compressor for compressing air; and the combustor according to the first, second or third aspect, wherein the air compressed by the compressor is burned. It is characterized in that a propulsive force is obtained by expansion of a combustion gas ejected from a fuel cell.

In this jet engine, combustion oscillation is reduced by employing the combustor having the above-described configuration. Thereby, resonance of the acoustic system including the combustor and the casing of the engine is prevented.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the present invention will be described. The gas turbine and the jet engine each have a compressor, a combustor, and a turbine as main components. One gas turbine drives a turbine using combustion gas generated in a combustor, and obtains shaft output to drive a generator and the like. A jet engine injects a rapidly expanding combustion gas and uses kinetic energy of a jet (jet stream) as propulsion. It should be noted that a jet engine normally drives a turbine by utilizing the expansion of combustion gas, and uses its shaft output as power for a compressor.

Among the above main components, the compressor introduces air serving as a working fluid into itself, compresses the air, and supplies the compressed air to the combustor. This air flow is mixed with fuel in a combustor, ignited, and supplied to a turbine as high-temperature, high-pressure combustion gas, which drives the turbine with kinetic energy generated in the course of expansion and drives the kinetic energy to drive the turbine. Or to exert.

Here, the combustor in the gas turbine is shown in FIGS. In the figure, reference numeral 11 denotes a combustion cylinder, 1
2 indicates a pilot burner, and 13 indicates a main burner. Inside the combustion cylinder 11, eight main burners 13 surround one pilot burner 12, and are arranged at equal intervals.

The pilot burner 12 is provided with a pilot swirler 14 for generating a swirl flow in the flow of air flowing toward the tip, and the main burner 13 is provided with a main swirler 15 having the same function. Further, behind the pilot swirler 14, a pilot nozzle 16 is provided.
However, a main nozzle 18 is provided behind the main swirler 15.

At the tip of the pilot burner 12, a pilot cone 1 is provided so as to cover the periphery of the pilot nozzle 16.
7 is provided, and an extension pipe 19 that covers the periphery of the main nozzle 18 is provided at the tip of the main burner 13.

The pilot cone 17 is formed with an enlarged diameter portion 17a whose diameter gradually increases in the direction in which the combustion gas is ejected, and an equal diameter portion 17b whose diameter is almost equal. Equal diameter part 17a
Is formed so as to be continuous from the enlarged diameter portion 17a toward the rear end. The rear end of the extension tube 19 is formed in an elliptical shape.

The process of combustion in the above-structured combustor will be described. First, air compressed in a compressor (not shown) flows into the combustion cylinder 11 and the burners are burned from the base end to the front end. Flows towards Pilot burner 1
The air flow flowing along 2 is given a swirling flow by the pilot swirler 14, and after mixing fuel in the pilot nozzle 16, it is ignited by a pilot flame (not shown) and burns, and is ejected from the pilot nozzle 16.

The air flow flowing along each main burner 13 is provided with a swirling flow by the main swirler 15, and after fuel is mixed in the main nozzle 18, the combustion gas flowing along the pilot cone 17 (the accompanying flame) ), And is emitted from the main nozzle 8 as a combustion gas.

At this time, since the combustion gas expands rapidly, it tends to diffuse not only behind the nozzle but also to the surroundings.
This causes turbulence in the airflow behind the combustor.
7a is provided with an equal-diameter portion 17b, and the combustion gas flowing along the inner surface of the pilot cone 17 has its flow direction corrected in the longitudinal direction of the equal-diameter portion 17b, and diffuses to the surroundings. Since the suppression is suppressed, a large collision does not occur between the airflow from each main burner 13 and the turbulence of the airflow behind the combustor is reduced.

According to the combustor configured as described above,
By reducing the turbulence of the airflow behind the combustor, combustion oscillation is less likely to occur. Therefore, in a gas turbine or a jet engine including this combustor, resonance of the combustor or casing caused by combustion vibration is prevented, and as a result, stable operation can be realized.

When the equal-diameter portion 17b is extremely long compared to the enlarged-diameter portion 17a, the diffusion of the combustion gas to the surroundings is drastically reduced, and the main burner 13 is not ignited. Therefore, it is desirable that the length of the equal diameter portion 17b is appropriately set in consideration of this point.

Next, a second embodiment according to the present invention will be described. The components already described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
In the present embodiment, as shown in FIG. 3 and FIG.
A notch 21 is formed in the equal diameter portion 17b of the pilot cone 17 from the rear end side. This notch 21 is provided corresponding to one of the main burners. That is, the notch 21 is formed at a position where the extension pipe 19 ′ of the associated main burner 13 can be visually recognized through the notch 21 from inside the pilot cone 17.

In the combustor of the present embodiment, a combustion gas (flame) is ejected outward from the notch 21 in the course of combustion, and this serves as a fire for the main burner 13 associated therewith. This makes it possible to satisfactorily ignite the main burner 13 'while keeping the equal-diameter portion 17b long to prevent collision of the combustion gas with the other airflow from the main burner 13. The other main burner 1
Since the combustion that has occurred in the main burner 13 'spreads to 3, the combustion as a whole does not stop.

According to the combustor configured as described above,
The stability can be improved by further reducing combustion oscillation.

Next, a third embodiment according to the present invention will be described. In addition, the same reference numerals are given to the components already described in each of the above embodiments, and the description is omitted. In the present embodiment, as shown in FIG.
It is individually formed at a position corresponding to each main burner 13.

In the combustor of this embodiment, the notch 2
By forming 1 at a position corresponding to each main burner 13, ignition of each main burner 13 can be performed satisfactorily. Thereby, similarly to the second embodiment, it is possible to further reduce the combustion oscillation and improve the stability.

In this embodiment, the notches 21 are provided so as to correspond to all the main burners 13. However, for example, the notches 21 are provided every other or every two main burners 13 arranged. It does not matter.

[0039]

As described above, according to the combustor according to the first aspect of the present invention, the combustor flows along the inner surface of the pilot cone by providing an equal diameter portion continuously to the enlarged diameter portion. Since the combustion gas is prevented from diffusing into the surroundings by the equal diameter portion continuing to the enlarged diameter portion, a large collision with the air flow from the main burner does not occur, and the turbulence of the air flow behind the combustor is reduced. . Thereby, combustion oscillation in the combustor can be reduced.

According to the combustor of the second and third aspects, the combustion gas is ejected outward from the notch portion and plays a role as a fire source for the main burner, so that the equal diameter portion is made longer. It is possible to satisfactorily ignite the main burner while preventing the combustion gas from colliding with the airflow from the main burner. Further, by forming the cutout portions individually at positions corresponding to the respective main burners, the ignition of the respective main burners can be performed more favorably. Thereby, the combustion oscillation can be further reduced, and the stability can be improved.

According to the gas turbine of the fourth aspect, by reducing the combustion vibration in the combustor as described above, the resonance of the acoustic system composed of the casing of the combustor and the gas turbine itself is prevented. A stable operation of the gas turbine can be realized.

According to the fifth aspect of the present invention, the resonance of the acoustic system comprising the combustor and the casing of the engine itself is prevented by reducing the combustion vibration in the combustor as described above. Stable operation of the engine can be realized.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment according to the present invention, and is a side sectional view of a combustor.

FIG. 2 is a side view of the combustor of FIG. 1 as viewed from the rear.

FIG. 3 is a view showing a second embodiment according to the present invention, and is a side view of the combustor as viewed from the rear.

FIG. 4 is a perspective view of the pilot cone and the extension tube as viewed obliquely from above.

FIG. 5 is a view showing a second embodiment according to the present invention, and is a side view of the combustor as viewed from the rear.

FIG. 6 is a side sectional view showing an example of a conventional combustor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Combustion cylinder 12 Pilot burner 13 Main burner 17 Pilot cone 17a Enlarged diameter part 17b Equal diameter part 19 Extension pipe 21 Notch

Claims (5)

[Claims] 1. A pilot burner, a plurality of main burners arranged to surround the pilot burner,
A pilot cone is provided at a tip of the pilot burner and diffuses combustion gas ejected from the pilot burner to the surroundings.The pilot cone has a diameter-enlarging portion that gradually increases in diameter in a direction in which the combustion gas is ejected. A combustor, wherein an equal-diameter portion having a diameter substantially equal to the diameter extending from the enlarged-diameter portion to the ejection direction is formed. 2. The combustor according to claim 1, wherein a cutout portion is formed in the equal diameter portion. 3. The combustor according to claim 2, wherein the cutouts are individually formed at positions corresponding to the main burners. 4. A compressor for compressing air, the combustor according to claim 1, 2 or 3, wherein the air compressed in the compressor is burned, and driven by expansion of combustion gas ejected from the combustor. A gas turbine, comprising: 5. A compressor for compressing air, and the combustor according to claim 1, 2 or 3 for burning the air compressed in the compressor, and expansion of combustion gas ejected from the combustor. A jet engine characterized by gaining propulsion power.