JPH02183720A - gas turbine combustor - Google Patents

Abstract

PURPOSE:To obtain a premix combustion structure advantageous to superlow NOx combustion by actuating a pilot burner from ignition to a low load, and performing premix combustion by a premix burner during a high load. CONSTITUTION:At the time of ignition, diffusion combustion is performed by a pilot fuel 35 and pilot burner air 36. As a combustion load is increased, premix air 28 such as a first stage air from an air introduction hole 29 for a fuel 25 of a premix burner 3, a second stage air of a fuel 26 and an air introduction hole 30, and a third stage air from a fuel 27 and an air introduction hole 31 is introduced through an air control ring 34 to make previous mixture so as to continue combustion from the center part of the burner to the peripheral direction by a fuel load region. In this case, the balance of an air bypass air amount to a premix air amount is set by the air control ring 34 and a mutual opening area to prevent the increase of pressure loss and the fluctuation of the air supply amount for each burner. Thereby, the control of fuel-air ratio of premix burners becomes easy, high reliable operation is possible for a combustion load of a wide range and a combustor advantageous to low NOx can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas turbine combustor, and particularly to the structure of a premix combustor with a pilot burner for the purpose of reducing nitrogen oxides (NOx).

[Conventional technology]

Conventional low NOx combustor (low NOx for Humbind plant)
x Development of Gas Turbine Combustor The 14th Proceedings of the Gas Turbine Society (1987) p51-56) is a two-stage combustion system in which diffusion combustion is performed in the head auxiliary chamber and premix combustion is performed in the rear main chamber. When the load is low, diffusion combustion is the main activity, and when the load is high, the second-stage premix combustion continues due to the heating effect from the diffusion flame. In particular, in premix combustion, the amount of air is adjusted relative to the fuel, and stabilization is achieved by controlling the fuel chamber ratio.

[Problem to be solved by the invention]

In the prior art, since the diffusion combustion section and the premix combustion section are separated from each other in the axial direction of the combustion chamber, the amount of diffusion combustion required to stabilize the premix combustion increases. Also,
Even during high-load combustion, diffusion combustion and premix combustion are performed simultaneously, so it is difficult to achieve large +i1 low NOx combustion. In particular, controlling the amount of air for premix combustion changes the amount of air for diffusive combustion, and reducing the amount of premixed air shifts diffusive combustion to the lean side, causing unburned matter such as CO to be generated. There were other problems.

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

[Means to solve the problem]

The above purpose is to install a diffusion combustion pilot burner and a premix burner in the cross-section of the head of the combustion chamber, and the pilot burner operates only from ignition at low loads, and at high loads, the premix burner performs premix combustion. .

In particular, the structure of the premix burner is such that the pilot burner is divided in the radial direction of the outer periphery adjacent to the center of the pilot burner. Make it controllable and install it.

Additionally, an air conditioning astragalus is installed at the air inlet of each flow path to adjust the amount of air flowing into each flow path, while at the same time controlling the bypass air to the downstream side of the combustion chamber via the bypass annular flow path. Configure it so that you can.

Therefore, during low-load combustion using the pilot flame near the premix burner, and during premix combustion, the simultaneous function of combustion air and bypass air should not directly affect the combustor. The multiple nozzle type prevents flashback and improves premixed combustion over a wide load range.

[Effect]

The pilot flame during premix combustion is the heat source for ignition and low-load premix combustion, and having a high temperature flame near the premix burner is very advantageous for flame holding performance.

On the other hand, in premix combustion, fuel and air are mixed and injected into the combustion chamber, so the shape of the nozzle becomes relatively large. By dividing this nozzle portion and forming a relatively narrow flow path portion, when the premixture increases or decreases due to load, the formation of an extreme hollow portion (dead space) in the internal flow path is prevented. In particular, when a hollow part is formed during the internal flow process, current transformation occurs.
At the part where fuel is mixed with air, mixing is poor due to a mismatch between the air velocity gradient and the fuel density, and at the ejection port, flashback occurs due to the difference in fuel concentration and ejection velocity distribution.

Furthermore, in the fuel chamber ratio control, in order to continue stable combustion in the premix burner, air other than that required for combustion is discharged as bypass air. Therefore, prevention of increase in pressure loss in the combustor,
Furthermore, since no excess air flows near the burner, it is possible to establish an ideal structure for premix combustion, such as stable combustion.

〔Example〕

FIG. 1 shows a longitudinal section of the combustor head of the present invention. Outer cylinder 1. Inner cylinder 2. At the head of a gas turbine combustor consisting of a premix burner 3, a swirler 4 is installed in the center of the premix burner 3,
A fuel flow path 5 and an annular air flow path 6 connected to the swirler 4 are formed at the upstream axis 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 premix burner 3 includes swirl vanes 12 in flow passages 9, 10, and 11 that are annularly divided in the cross-sectional direction of the outer circumferential side of the pilot burner 8.
, 13 and 14 are fixed, and the fuel nozzle 15 is arranged so as to protrude from the upstream end of the divided flow path section formed by the swirl vanes of each flow path section.
, 16.17 will be installed in large numbers.

The fuel nozzles 15, 16, 17 are fixed to the burner body 18, the fuel chambers 19, 20, 21 and the fuel inlet pipe 22,
23.24 is provided to enable split introduction adjustment of each fuel 25°26.27.

On the other hand, the premixed air 28 is provided by extending the annular flow passage portions 9, 10° 11 in the radial direction of the outer circumference to form air inlets 29, 30, 31 having a circumferential opening shape. An air bypass annular flow path section 33 having an opening section 32 in the same circumferential shape extending from the rear section to the rear section is configured to communicate into the combustion chamber.

In addition, a gap is provided between the air inlets 29, 30.31 and the outer periphery of the air bypass opening 32 to make the air adjustment ring 34 correspond to the air inlets 29, 30.31, so that when the air inlets 29, 30.31 are fully open, the opening 32 is fully open. The air adjustment ring 34 can be moved and adjusted as desired.

Therefore, at the time of ignition, the pilot fuel 35 and the pilot burner air 36 perform diffusion combustion. In addition, as the combustion load increases, the fuel 25 of the premix burner 3 is supplied with first-stage air from the air inlet 29, second-stage air between the fuel 26 and the air inlet 30, and fuel 27 and the air inlet 31. Premixed air 28, such as third-stage air, is introduced through the air adjustment ring 34 to create a premixed air mixture, and combustion continues from the center of the burner toward the outer periphery according to the combustion load zone. In this case, by setting the mutual opening area with the air adjustment ring 34 to balance the amount of air bypass air with respect to the amount of premixed air, increases in pressure loss and fluctuations in the amount of air supplied to each burner are prevented.

FIG. 2 shows an embodiment of the fuel control operation method in the gas turbine operating range. The operating range of pilot fuel Fp is
From the time of ignition, the turbine load is 25% and the total fuel is 5 to 15%, and under no-load conditions, the first stage fuel FL = 10% of the premix burner is introduced stepwise at the same time as Fp = 1.
Decrease 0% and keep it constant at 5%, first stage fuel Fz: 2
Increase the temperature by 8% to create a no-load condition. In addition, when there is no load, the first stage fuel Fl is reduced by 8% in steps, the second stage fuel F2 is injected at 8%, the pilot fuel FP is set at 5%, and the first stage fuel Fl is kept constant at 20%, resulting in F2 fuel. Increase the load by increasing. Furthermore, at 25% turbine load, the first stage fuel Fl
: 20% constant, 2nd stage fuel Fz = 35% to 30%, 3rd stage fuel F3 = 10% is injected stepwise, pilot fuel Fp is adjusted to O, and F8 fuel is used to reduce the load. Aim to increase.

At rated time, first stage fuel Fl = 20%, second stage fuel Fz
:30%, and the premix burner is operated with third stage fuel Fa=50% to continue premix combustion.

In this case, premix air adjustment to each stage is performed by the air adjustment ring, and by setting the combustion chamber ratio as a combustion condition to 0.50 or less, effective low NOx combustion can be performed.

〔Effect of the invention〕

According to the present invention, the fuel chamber ratio of the premix burner can be easily controlled and reliable operation can be performed over a wide range of combustion loads, making it possible to provide a combustor that is advantageous for reducing NOx. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a gas turbine combustor according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of fuel control operation in the combustor of FIG. 1. Fp...pilot fuel, Fs...first stage fuel, F
2...2nd stage fuel, Fs...3rd stage fuel, 3...
Premix burner, 8...Pilot burner, 9-11.
...Annular flow path section, 15-17...Fuel nozzle, 19-
21... Fuel chamber, 29-31... Air inlet, 32... Air bypass opening, 33... Air bypass annular flow path section, 34... Air adjustment ring. Figure Z Figure 7 - Bin negative side (〃)

Claims (1)

[Claims] 1. In a gas turbine combustor with a combination of a diffusion combustion pilot burner and a premix burner, a diffusion pilot burner is provided in the center of the head combustion chamber, and an annular swirler is superimposed on the outer circumferential side of the nozzle part. A gas turbine combustor, characterized in that a premix burner is installed, and when the premix burner is operated, an annular swirl nozzle portion into which a premixture suitable for a combustion load zone is divided is operated. 2. In the combustor structure according to claim 1, fuel and air are introduced into the central part of the head combustion chamber, a pilot burner with a swirler is installed, and the combustor is divided into an annular shape in the cross-sectional direction of its outer circumference. A fuel nozzle is made to protrude into the flow path from an upstream end of a divided hollow portion formed by overlapping the flow path portions and providing swirl vanes in each of the flow path portions, so that the fuel is introduced separately into each annular flow path. Each annular flow path has a divided hollow part further extended in the outer circumferential direction to form a circumferential air inlet, and a fuel system path is formed in the vicinity of the downstream side of the air inlet. An air bypass inlet having an annular flow path for bypassing air into the combustion chamber and having a circumferential opening has the same diameter as the air inlet and has an air conditioning ring corresponding thereto;
A gas characterized in that the ring shape is movable so that when the air inlet is fully open, the air bypass inlet is fully closed, and combustion is performed by adjusting the fuel and air according to the combustion load zone. Turbine combustor.