JPH11248158A - Combustion device for gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize combustion while reducing the producing of nitrogen oxide by a method wherein eddy current is generated in the flame of mixed fluid of fuel and air, which is injected out of a pilot fuel injection valve, when an air opening and closing means is closed to retain the flame while the mixed fluid of fuel and air is pre-mixed and pre-evaporated when the air opening and closing means is opened. SOLUTION: A mixing pipe 11 for flame retaining and combustion, which effects pilot combustion and premixing as well as pre-evaporation, is arranged at the downstream of a pilot fuel injection valve 3 while an air opening means 12 is arranged at the upstream side of the mixing tube 11. Under the condition of combustion by the pilot fuel injection valve 3, air from air intakes 5A, 5B is mixed into fuel and is injected out of the fuel injection valve 3 to burn whereby diffusion flame (f) is formed in the mixing tube 11 for flame retaining and combustion. On the other hand, a part of the diffusion flame (f) is spread laterally and eddy current is formed near a perforated plate 12A whereby flame is retained. In accordance with the increase of number of rotation of a gas turbine, fuel injection from the pilot fuel injection valve 3 and fuel injection, accompanying premixing and pre-evaporation from a main fuel injection valve 4, are effected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus for a gas turbine, and more particularly, to ensuring stable combustion while reducing the amount of nitrogen oxides generated.

[0002]

2. Description of the Related Art In a combustion apparatus (combustor) used for an aircraft, a ship, a gas turbine for power generation, and the like, a technique for reducing the amount of nitrogen oxides (NOx) in a combustion gas is as follows. Kaihei 09-178184 has been proposed.

FIG. 6 shows an example of the structure of a gas turbine combustion apparatus described in the aforementioned Technical Example 1. A combustion liner 2, a pilot fuel injection valve 3, and a main fuel injection valve are provided inside a casing 1. 4 and the air flow is introduced into the combustion liner 2 from the air intake 5, and the fuel injected from the pilot fuel injection valve 3 and the main fuel injection valve 4 is ignited and burned, At the time of starting, fuel is sent from the pilot fuel supply system 6 to the pilot fuel injection valve 3 and the ignition plug 7 is operated in a state of high fuel concentration to ignite the fuel and lead to a combustion state.
Fuel is fed from the main fuel supply system 8 to the main fuel injection valve 4, and the premixed pipe 9 is burned (premixed and pre-evaporated) after being diluted with a large amount of air and vaporized. . Technical Example 1 employs an operation mode in which the fuel injection amount passing through the pilot injection valve is reduced to zero or significantly reduced under a steady combustion condition, and flame holding means is added near the outlet of the premixing pipe. While improving the
The amount of nitrogen oxides generated based on the pilot flame is reduced to reduce NOx, thereby ensuring stable combustion.

[0004]

However, at the start of the pilot fuel injection valve 3, the fuel is ignited in a state where the fuel concentration is high at the time of starting, thereby leading to a combustion state.
Also during the combustion by the premixed pre-evaporation in the main fuel injection valve 4, the combustion state in the start-up operation mode by the pilot fuel injection valve 3 is taken over, and the premixed pre-evaporation is not performed in the pilot flame. It is technically difficult to reduce the amount of oxides, and if premixed pre-evaporation is performed at the pilot fuel injection valve 3, there remains a problem that flame stability is impaired.

[0005] The present invention has been made in view of these problems, and aims to achieve the following objects. Even if premixed pre-evaporation is performed in the pilot fuel injection valve portion, the amount of generated nitrogen oxides can be reduced. Achieving an overall reduction in nitrogen oxides. Ensuring stable combustion during startup, transition, and steady operation.

[0006]

SUMMARY OF THE INVENTION At a position upstream of a combustion liner, a pilot fuel injection valve for performing pilot combustion, a main fuel injection valve for performing main combustion, and air is disposed at the main fuel injection valve to transfer fuel to air. A premixing pipe for dilution by a flow, wherein a flame stabilizing combustion mixing pipe is provided at a position downstream of the pilot fuel injection valve, and air is provided at an upstream position of the flame stabilizing mixing pipe. Opening / closing means is provided, and when the air opening / closing means is closed, a part of the flame of the fuel-air mixed fluid injected from the pilot fuel injection valve generates a vortex to perform flame holding. A technique of pre-mixing and pre-evaporating the fuel-air mixed fluid injected from the fuel injection valve is employed. The air opening / closing means is arranged upstream of the flame stabilizing combustion mixing pipe to take in air, an opening / closing plate rotatably attached to the perforated plate to open and close holes, and an opening / closing plate. And an opening / closing actuator that is connected to and performs an opening / closing operation. The perforated plate and the open / close plate set the air flow by a combination of a plurality of holes spaced in the circumferential direction of the pilot fuel injection valve, and the perforated plate and the open / close plate are slidably combined with each other. Have been.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a gas turbine combustion apparatus according to the present invention will be described below with reference to FIGS.

Also in the first embodiment, a pilot fuel injection valve 3 for pilot combustion and a pilot fuel injection valve 3 for main combustion are provided in the casing 1 at a position upstream of the combustion liner 2 according to the example of FIG. A main fuel injection valve 4 and a premixing pipe 9 arranged in the main fuel injection valve 4 for diluting fuel by an air flow are provided, and the pilot fuel injection valve 3 and the main fuel injection valve 4 are provided. , Pilot fuel supply system 6
And the main fuel supply system 8 is connected.

As shown in FIG. 1, a straight cylindrical flame holding combustion mixing pipe 11 for performing pilot combustion and premixing / pre-evaporation is disposed downstream of the pilot fuel injection valve 3. An air opening / closing means 12 is disposed upstream of the flame holding combustion mixing pipe 11.

The air opening / closing means 12 is a mixing tube 1 for flame holding and combustion.
1 is provided with a perforated plate 12A, and a plurality of holes 12a formed in the perforated plate 12A at intervals.
The opening and closing plate 12B is slidably superimposed on the upstream side of the perforated plate 12A to open and close the hole 12a. An opening / closing actuator 12C for performing an operation and a rotational force transmission system 12D are arranged in a connected state.

As shown in FIGS. 2 and 3, the opening / closing plate 12B has a plurality of holes 12b corresponding to the holes 12a of the perforated plate 12A. By the operation of rotating the valve 3 in the circumferential direction, for example, a plurality of holes 12a and 12b spaced apart in the circumferential direction of the pilot fuel injection valve 3 are combined to form an air cutoff state, an air insertion state, or a state in which the air insertion amount is adjusted. I try to set the flow of air.

In the combustion apparatus having the above-described configuration, the fuel supply system and the combustion mode are switched according to each operation mode such as when the gas turbine is started, when the load is light, and when the load is steady. At this time, the air opening / closing means 12 is operated to adjust the amount of air passing through the hole 12a of the perforated plate 12A. In addition, the pilot fuel supply system 6 and the main fuel supply system 8 include the technical example 1 (FIG. 4).
Control means for setting the fuel supply ratio and fuel supply amount by the pilot fuel supply system 6 and the main fuel supply system 8 by switching between the start operation mode, the start-up operation mode, the steady operation mode, etc. Is done.

Start-up operation mode: When starting the gas turbine, as shown in FIG. 1A, the perforated plate 12A of the air opening / closing means 12 is closed by the opening / closing plate 12B, and the amount of air passing through the hole 12a is reduced to zero. Then, the fuel is supplied from the pilot fuel supply system 6 shown in FIG. 6 to the pilot fuel injection valve 3 to ignite the fuel, and the operation of gradually increasing the rotation speed of the gas turbine to bring it to a steady state is performed. It is.

In the pilot combustion state of the pilot fuel injection valve 3, the air and fuel taken in from the air intakes 5A and 5B are mixed with each other and injected from the pilot fuel injection valve 3 as a fuel-air mixed fluid. By burning, a diffusion flame f is formed inside the flame holding combustion mixing pipe 11 as shown in FIG.
On the other hand, part of the diffusion flame f spreads sideways,
In the vicinity of A, as shown by the arrow in FIG.

Start-up operation mode (at low load): The fuel is supplied from the main fuel supply system 8 shown in FIG. 6 in accordance with an increase in the number of revolutions of the gas turbine and according to the load condition. Control is performed by injecting fuel from the injection valve 4 to increase the overall fuel supply amount and lead to a steady operation mode. In a transient operation state or a low load state until the load reaches the maximum load, fuel injection from pilot fuel injection valve 3 and fuel injection from main fuel injection valve 4 with premixed pre-evaporation are performed. At the same time, premix combustion is performed downstream of the premix pipe 9 of the main fuel injection valve 4. FIG. 4 schematically shows a situation in which a diffusion flame f and a premixed flame g are generated inside the flame holding combustion mixing pipe 11 and downstream of the premixing pipe 9 of the main fuel injection valve 4. ing.

Steady-state operation mode: After the internal temperature of the combustion liner 2 has sufficiently increased, the operation mode is switched to a steady-state operation mode in which fuel corresponding to a steady-state load is ejected. In this steady operation mode, in addition to the premixed pre-evaporation in the main fuel injection valve 4, the premixed pre-evaporation is also performed in the pilot fuel injection valve 3.

That is, the mechanical force generated by the opening / closing actuator 12C is transmitted to the opening / closing plate 12B via the rotational force transmission system 12D, and the position of the hole 12b in the opening / closing plate 12B is shifted to form the perforated plate 12A. 1B, air is taken into the flame stabilizing combustion mixing pipe 11 through the hole 12a as shown in FIG. 1B. Air opening / closing means 1
If air is introduced into the pilot fuel injection valve 3 from inside 2 to form an air flow and dilute the fuel flow to be in a premixed and pre-evaporated state, the diffusion combustion conditions inside the flame holding combustion mixing pipe 11 are impaired. Then, premix pre-evaporation is also performed downstream of the flame stabilizing combustion mixing pipe 11 schematically shown in FIG. 5, and a premix flame h is generated. Therefore, at the time of maximum load: in the steady operation mode, premixed combustion is performed in the entire area of the combustion liner 2 to increase the temperature inside the combustion liner 2 (combustion chamber). Due to the fact that the air flow has reached a sufficient velocity and that all the fuel is burned in a premixed pre-evaporated state,
The production amount of nitrogen oxides will be significantly reduced.

[Other Embodiments] In the combustion apparatus for a gas turbine of the present invention, the following techniques can be adopted. a) In the start-up operation mode (at a low load), the air opening / closing means 12 is operated to form an air flow passing through the perforated plate 12A, thereby gradually increasing the amount of air. b) In the air opening / closing means 12, the air amount is adjusted by means other than the rotational movement and sliding of the opening / closing plate 12B. Also,
The number, shape, and combination of the holes 12a and 12b are arbitrary.

[0019]

According to the combustion apparatus for a gas turbine of the present invention, the following excellent effects can be obtained. (1) A mixing pipe for flame holding combustion is arranged at a position downstream of the pilot fuel injection valve, and an air opening / closing means is arranged at a position upstream of the mixing pipe for flame holding combustion, and the fuel is ejected from the pilot fuel injection valve in the normal operation mode. By performing premix combustion on the fuel, the amount of generated nitrogen oxides can be reduced. (2) Premixed pre-evaporation is performed in both the pilot fuel injection valve and the main fuel injection valve to generate premixed combustion throughout the combustion liner, thereby achieving an overall reduction in the amount of nitrogen oxides. it can. (3) The air opening / closing means is closed to cause diffusion combustion inside the flame stabilizing combustion mixing tube and to generate flame swirling in a part of the flame to perform flame stabilization. Stable combustion can be ensured. (4) The optimal air amount can be adjusted based on the operation of the air opening / closing means.

[Brief description of the drawings]

FIG. 1 is a first view of a gas turbine combustion apparatus according to the present invention.
1A and 1B are front sectional views of a fuel supply state in a start-up operation mode, and FIG. 2B is a front sectional view of a fuel supply state in a normal operation mode.

FIG. 2 is a perspective view of a pilot fuel injection valve in FIG.

FIG. 3 is an exploded perspective view showing a combined state of a perforated plate and an opening / closing plate of the air opening / closing means in FIG. 1;

FIG. 4 is a schematic diagram showing a combustion state in a start-up operation mode.

FIG. 5 is a schematic diagram showing a combustion state in a normal operation mode.

FIG. 6 is a partially cutaway front view showing a structural example of the combustion device for a gas turbine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 2 Combustion liner 3 Pilot fuel injection valve 4 Main fuel injection valve 5 Air intake 5A, 5B air intake 6 Pilot fuel supply system 8 Main fuel supply system 9 Premixing pipe 11 Mixing pipe for flame holding combustion 12 Air opening / closing means 12A Perforated plate 12B Opening / closing plate 12C Opening / closing actuator 12D Rotating force transmission system 12a, 12b Hole f Diffusion flame g Premixed flame h Premixed flame

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F23R 3/18 F23R 3/18 3/28 3/28 B 3/34 3/34 (72) Inventor Takashi Ikezaki Nishitama-gun, Tokyo 229 Tonogaya, Mizuho-cho Ishi Kawashima-Harima Heavy Industries, Ltd.Mizuho Plant Co., Ltd. Mizuho Branch, Mizuho Factory

Claims (4)

[Claims] 1. A pilot fuel injector (3) for pilot combustion at a position upstream of a combustion liner (2).
A combustion apparatus comprising: a main fuel injection valve (4) for performing main combustion; and a premixing pipe (9) disposed in the main fuel injection valve and diluting fuel by an air flow, wherein the pilot fuel injection valve is provided. A flame stabilizing combustion mixing pipe (11) is arranged at a downstream position, and an air opening / closing means (12) is arranged upstream of the flame stabilizing combustion mixing pipe. A vortex is generated in a part of the flame of the fuel-air mixture fluid injected from the pilot fuel injection valve to perform flame holding, and when opened, the fuel-air mixture fluid injected from the pilot fuel injection valve is premixed and pre-evaporated. A combustion device for a gas turbine, comprising: 2. An air opening / closing means (12) is arranged upstream of a flame stabilizing combustion mixing pipe (11) for taking in air, and is rotatably attached to the perforated plate. 2. The gas according to claim 1, further comprising an opening / closing plate (12B) for opening and closing the holes (12a, 12b), and an opening / closing actuator connected to the opening / closing plate for opening / closing operation. Combustion device for turbine. 3. A perforated plate (12A) and an opening / closing plate (12).
3. The gas turbine according to claim 2, wherein in (B), the flow of air is set by a combination of a plurality of holes (12a, 12b) spaced in the circumferential direction of the pilot fuel injection valve (3). For combustion equipment. 4. A perforated plate (12A) and an opening / closing plate (12).
4. The gas turbine combustion device according to claim 3, wherein B) is slidably combined with each other.