JP2865684B2 - Gas turbine combustor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a gas turbine combustor, and more particularly, to a structure of a premix combustor with a pilot burner for the purpose of reducing nitrogen oxides (NOx).

[Conventional technology]

Conventional low NOx combustor (Development of low NOx gas turbine combustor for combined plant 14th Gas Turbine Society Transactions (1987) pp. 51-56) consists of diffusion combustion in the head sub chamber and premixed combustion in the rear main chamber. Is a two-stage combustion method. When the load is low, diffusion combustion is mainly performed, and when the load is high, the premixed combustion in the second stage is continued by the heating action from the diffusion flame. In particular, in the premixed combustion, the amount of air is adjusted with respect to the fuel to stabilize the fuel-air ratio control.

[Problems to be solved by the invention]

In the prior art, since the diffusion combustion section and the premix combustion section are separated in the axial direction of the combustion chamber, the amount of diffusion combustion required for stabilizing the premix combustion increases. In addition, even during high load combustion, diffusion combustion and premix combustion are performed simultaneously, so it is difficult to perform large NOx reduction combustion. In particular, controlling the amount of air in premixed combustion changes the amount of air to diffuse combustion, and reducing the amount of premixed air shifts diffusion combustion to the lean side, causing unburned components such as CO. And other problems.

An object of the present invention is to provide a combustor which solves the above-mentioned problems, and which has a premixed combustor structure which is advantageous for ultra-low NOx combustion.

[Means for solving the problem]

The above-mentioned object is to install a pilot burner and a premix burner for diffusion combustion in the cross section of the combustion chamber head, operate the pilot burner only at low load from ignition, and perform premix burn with the premix burner at high load. . In particular, in the structure of the premix burner, the orifice of the flow path part which divided the pilot burner in the outer peripheral radial direction adjacent to the center part is formed by a multiple annular swirler, and the fuel system is individually provided for each flow path part. Install with controllable. Furthermore, at the same time as installing an air adjustment ring at the air introduction port of each flow path to adjust the amount of air to each flow path,
The configuration is such that bypass air can be controlled downstream of the combustion chamber via the bypass annular flow path.

Therefore, the simultaneous function of combustion air and bypass air should not directly affect the combustion field during low-load combustion or premixed combustion with the pilot flame near the premixed burner. Premixed combustion is improved in a wide load zone, such as flashback prevention, due to multiple injection nozzles.

[Action]

The pilot flame during premixed combustion is a heat source for ignition and low-load premixed combustion, and the presence of a high-temperature flame near the premixed burner is extremely advantageous for flame holding performance.

On the other hand, in premixed combustion, the fuel and air are mixed and injected into the combustion chamber, so that the shape of the injection port is relatively large. By forming the injection port portion into a relatively narrow channel portion, when the premixed gas increases or decreases due to a load, formation of an extremely aerial portion (dead space) in the internal channel is prevented. In particular, when a hollow portion is formed during the internal flow, a current change occurs.At the fuel mixing portion for air, mixing becomes poor due to the mismatch between the air velocity gradient and the fuel density. A flashback occurs from the difference. Also,
In the fuel-air ratio control, air other than air necessary for combustion is discharged as bypass air in order to continue stable combustion of the premix burner. Therefore, preventing the pressure loss in the combustor from increasing, and
Since the excess air does not flow in the vicinity of the burner, it is possible to establish an ideal structure for premixed combustion, such as good stable combustion.

〔Example〕

FIG. 1 shows a vertical section of a combustor head according to the present invention. A swirler 4 is installed at the center of the premix burner 3 at the head of the gas turbine combustor composed of the outer cylinder 1, the inner cylinder 2, and the premix burner 3. An annular air flow path 6 connected to the swirler 4 is formed from the outer peripheral side of the head, and a fuel injection hole 7 is provided in the swirler 4 to form a pilot burner 8. The premixing burner 3 has swirling blades 12, 13, and 14 fixed to flow passage portions 9, 10, and 11, which are annularly sectioned in a sectional direction on the outer peripheral side of the pilot burner 8, and is formed by the swirling blades of each flow passage portion. A large number of fuel nozzles 15, 16, 17 are provided so as to protrude from the upstream end of the divided flow path. The fuel nozzles 15, 16, and 17 are fixed to the burner main body 18. I do.

On the other hand, the premixed air 28 extends through the annular flow passages 9, 10, 11 in the radial direction of the outer circumference, and has an air inlet having a circular opening shape.
29, 30, 31 are formed, and an air bypass annular flow path portion 33 having the same circumferential opening 32 connected to the rear portion from each air inlet is connected to the combustion chamber. Also, air inlet 2
A gap is provided on the outer peripheral side of the air bypass opening 32 with the air adjustment ring 34 so that the air opening 29 is fully closed when the air introduction ports 29, 30, 31 are fully opened. Adjustment ring 34
The movement can be adjusted.

Accordingly, at the time of ignition, diffusion combustion is performed by the pilot fuel 35 and the air 36 for the pilot burner. Further, as the combustion load increases, the first-stage air from the air inlet 29 for the fuel 25 of the premix burner 3, the second-stage air of the fuel 26 and the air inlet 30,
Premixed air 28 such as third-stage air from fuel 27 and air inlet 31
Is introduced through the air conditioning ring 34 to produce a premixed air-fuel mixture, and the combustion is continued from the central portion of the burner toward the outer periphery by the combustion load zone. In this case, the balance of the amount of air bypass air with respect to the amount of premixed air is set by setting the mutual opening area with the air adjusting ring 34, thereby preventing an increase in pressure loss and a fluctuation in the amount of air supplied to each burner.

FIG. 2 shows one embodiment of the fuel control operation method in the gas turbine operating range. Operating range of pilot fuel F _P is
From the time of ignition, the tarpin load is 25% and the fuel is 5 to 15%
Under no-load conditions, the first stage fuel of the premix burner
At the same time as introducing F ₁ = 10% in a stepwise manner, F _P = 10% is decreased and kept constant at 5%, and the first-stage fuel F _{1 is} increased by 28% to a no-load condition. Also, at no load decreases 8% first stage fuel F ₁ in step form, pilot fuel F _P = 5% second stage fuel F ₂ = 8% turned to the first stage fuel F ₁ = 20% constant raising the load by F ₂ fuel increase. Further, the turbine load 25%, the first stage fuel F ₁ = 20% constant, from the second-stage fuel F ₂ = 35%
The fuel is reduced to 30%, the third-stage fuel F ₃ = 10% is charged in steps, and the pilot fuel F _P = 0 is adjusted to increase the load by the F ₃ fuel.

At the time of rating, first stage fuel F ₁ = 20%, second stage fuel F ₂ = 30
% And the third-stage fuel F ₃ = 50% to operate the premix burner to continue the premix combustion. In this case, the premixed air adjustment to each stage is performed by the above-described air adjustment ring, and the fuel-air ratio as the combustion condition is set to 0.50 or less, so that the effective low-mixing air is effectively reduced.
NOx combustion can be performed.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, since the fuel-air ratio control of a premix burner becomes easy and highly reliable driving | operation with respect to a wide range of combustion loads is possible, it is possible to provide a combustor that is advantageous for reducing NOx. .

[Brief description of the drawings]

FIG. 1 is a sectional view of a gas turbine combustor according to one embodiment of the present invention, and FIG. 2 is an explanatory diagram of a fuel control operation in the combustor of FIG. F _P … Pilot fuel, F ₁ … First stage fuel, F ₂ …… Second
Stage fuel, F ₃ …… Third stage fuel, 3 …… Premix burner, 8…
… Pilot burner, 9-11 …… Circular flow path, 15-17…
... fuel nozzles, 19 to 21 ... fuel chambers, 29 to 31 ... air inlets, 32 ... air bypass openings, 33 ... air bypass annular flow passages, 34 ... air adjustment rings.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Fumio Kato 502 Kandate-cho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. (72) Takashi Hashimoto 502-Kindachi-cho, Tsuchiura-City, Ibaraki Hitachi, Ltd. In-house (56) References JP-A-63-217141 (JP, A) JP-A-63-156925 (JP, A)

Claims (1)

(57) [Claims] 1. A pilot burner for injecting pilot fuel and air for a pilot burner into a combustion chamber in which a combustion flame is formed, a pilot burner disposed adjacent to an outer periphery of the pilot burner, and a premixed fuel and a premixed air. And a premix burner that injects a premixed gas premixed into the combustion chamber, wherein the premixed burner has an injection port that injects the premixed gas in a radial direction and an axial direction. A gas turbine combustor characterized by being formed by a plurality of flow paths that inject the premixed gas from adjacent ones and the injection port portion is located on the inner periphery according to a combustion load zone.