JPH07248117A - Combustion method for gas turbine premixing combustor - Google Patents

Abstract

PURPOSE:To provide a combustion method for a gas turbine premixing combustor capable of controlling the generation amount of NOX by a diffusion burner without deteriorating freedom and reliability in the operation of a gas turbine during the period from the start to the rated operation of the gas turbine. CONSTITUTION:A combustor is provided with a first stage combustion chamber (I), a first stage mixing region (II), a second stage combustion chamber (III), a second stage mixing region (IV) and a third stage combustion chamber (V) which are arranged in the above order from the upstream side, and combustion gas generated in the first stage combustion chamber (I) and pre-mixed gas supplied from a downstream side are mixed with each other and pre-mixed combustion is successively effected in the second stage combustion chamber (III) and the third stage combustion chamber (V) in accordance with the load of a gas turbine. Before the pre-mixed combustion on the downstream side is effected, in the first stage combustion chamber (I) mode is switched from a combustion mode by use of diffusion fuel 28 to a diffusion/first stage pre- mixed hybrid combustion mode in which most part of the diffusion fuel 28 is diverted to primarily pre-mixed fuel 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion method for a gas turbine premixed combustor, which suppresses the amount of NOx produced.

[0002]

2. Description of the Related Art Conventionally, NO emitted from a gas turbine
A dry low NOx combustor is used to suppress x, and most of them use a premixed combustion method in which fuel gas and air are premixed and burned.

The principle of reducing NOx is to burn at low temperature with the mixture ratio of fuel and air smaller than the theoretical fuel-air ratio,
The amount of x generated is suppressed. The gas turbine premixed combustor is a so-called hybrid type that combines pre-mixed combustion with diffusion combustion that has been conventionally used to secure the stability of combustion from the start of the gas turbine to the time of low load. Is the mainstream.

The main problems of the dry low NOx combustor are (1) stable combustion with a fuel-air ratio as small as possible,
(2) Expansion of premixed combustion ratio by limiting diffusion combustion as much as possible during high load operation of gas turbine, (3)
Examples include expansion of the premixed combustion operating range to the low load side of the gas turbine.

As a method for solving these problems, a method of arranging a plurality of premixing burners to increase the number of premixing burners to be ignited according to the load of the gas turbine, and a method of combusting air according to the fuel flow rate The method of adjustment is generally adopted.

In Japanese Patent Laid-Open No. 61-135942, a diffusion burner for diffusion combustion is provided at the end of the combustion gas flowing in the combustor on the upstream side of the combustor, and the premixed gas is supplied from the side wall on the downstream side of the combustor. A structure is disclosed in which the fuel is divided into three systems for supply and combustion.

In such a structure, fuel is supplied only from the most upstream side system during low load operation of the gas turbine. Therefore, if mixed with the total amount of premixed air,
Even if the fuel flow rate is too lean to ignite, the combustible concentration is obtained, and the gas turbine can be operated by premixed combustion even at a low load.

Further, in this type of combustor, the premixed gas is ignited by the heat contained in the flame of the diffusion burner upstream of the combustor. That is, the flame of the diffusion burner requires a heat amount more than that capable of holding the ignition and flame holding of the premixed gas, but if this condition is satisfied, stable combustion can be obtained.

Further, in this type of combustor, when the combustion gas generated on the upstream side of the combustor and the premixed gas supplied from the downstream side of the combustor are mixed in the combustor, the combustion gas has a predetermined temperature or higher. At a high temperature, even if the fuel-air ratio is very small, the combustion reaction proceeds, so that the premixed combustion operation range can be widened.

[0010]

However, in the dry low NOx combustor as described above, the premixture supplied to the downstream side of the combustor is ignited by the combustion by the diffusion burner mounted on the upstream side of the combustor. It stabilizes the flame. Therefore, the fuel supplied from the diffusion burner cannot be reduced to a predetermined amount or less.

Even from high load to rated load,
Since the combustion ratio of the diffusion burner is kept high, the NOx generation amount of the entire gas turbine combustor is increased. That is, in order to further reduce the NOx generation amount, it is necessary to suppress the NOx generation amount by the diffusion burner.

However, when this suppression is performed, the function of the diffusion burner is not deteriorated, that is, the degree of freedom and reliability of operation of the gas turbine from the start of the gas turbine to the rated operation is not impaired. Strict conditions are attached to it.

An object of the present invention is to provide a combustion method for a gas turbine premixed combustor capable of suppressing the NOx generation amount by a diffusion burner while satisfying such severe conditions.

[0014]

The above object can be achieved as follows.

(1) In a combustor of a gas turbine, a diffusion burner is provided at the center of the upstream end surface of the combustion gas flowing inside the combustor, and a mixture of primary air and primary fuel is provided on the outer peripheral side of the diffusion burner. A first-stage premixing nozzle that supplies a certain primary premixed gas is provided, and at least one of the fuel supplied from the diffusion burner and the primary premixed gas supplied from the first stage premixing nozzle is burned. The first stage combustion chamber,
A secondary pre-mixture, which is a mixture of secondary air and secondary fuel, is formed in the space extending from the upstream end surface to the downstream side and is provided on the outer peripheral side of the downstream end of the first-stage combustion chamber. A second-stage combustion chamber for combusting the secondary premixed gas is formed in the space downstream of the position having the secondary premixed gas supply unit, and further for the second stage. A third premixed air supply means is provided on the outer peripheral side of the downstream end of the combustion chamber, and a third premixed air supply means is provided for supplying a third premixed air-fuel mixture of tertiary air and tertiary fuel. In a combustion method of a gas turbine premixing combustor configured by forming a third stage combustion chamber for combusting a third premixed gas in a space downstream of a position having a The combustion gas generated by the supplied fuel reaches a temperature condition in which the primary premixture can undergo an oxidation reaction. Supplies the fuel only from the diffusion burner to generate combustion gas, and after reaching the temperature condition, most of the fuel supplied from the diffusion burner is turned into the fuel of the primary premixed gas, and The diffusion / first-stage premixed hybrid combustion method in which any of the first-stage premixing nozzles is operated is used to increase the load of the gas turbine in the first-stage combustion chamber, and then the secondary premixed gas supply means The secondary premixture is supplied to the second-stage combustion chamber to increase the load of the gas turbine by the second-stage combustion, and after the gas turbine reaches a predetermined load, the tertiary premixture is reduced to 3
Supply to the third stage combustion chamber and operate the gas turbine to the rated load by combustion inside the third stage combustion chamber.

(2) In (1), in the diffusion / first stage premixed hybrid combustion method, the method of turning the fuel supplied from the diffusion burner to the fuel of the primary premixed mixture is the diffusion burner and the first stage premixed. The common fuel supply base system with the nozzle is branched into a fuel supply system for the diffusion burner and a fuel supply system for the first stage premixing nozzle, and a fuel supply system for the diffusion burner and the first stage premixing nozzle. Flow control valve is attached to each of the fuel supply system and the opening and closing of the flow control valve.

(3) In (1) or (2), diffusion /
In the first-stage premixed hybrid combustion method, the total amount of fuel supplied from the diffusion burner and the first-stage premixing nozzle is constant, and the flow rates of the fuel supplied from the diffusion burner and the fuel supplied from the first-stage premixing nozzle. The ratio is 1 to 9.

[0018]

In the present invention, the diffusion combustion and the diffusion / first-stage premix hybrid combustion method are used together to generate the combustion gas in the first-stage combustion chamber. That is, a diffusion burner and 1
The combustion gas generated by the fuel supplied from the diffusion burner to the first-stage combustion chamber can oxidize the primary pre-mixture under the condition that the total fuel supplied from the first-stage premix nozzle is constant. Until the temperature is reached, the fuel is supplied only from the diffusion burner to generate combustion gas. After reaching the temperature, most of the fuel supplied from the diffusion burner is the fuel of the primary premixture. To the hybrid combustion mode using the diffusion burner and the first-stage premixing nozzle to minimize diffusion combustion.

Therefore, it is possible to reduce the diffusion combustion that generates a large amount of NOx and increase the premixed combustion. Since the premixed combustion is a thin combustion, the combustion gas generated in the first stage combustion chamber has The amount of NOx contained can be greatly suppressed.

From the combustion mode by the diffusion burner,
Switching to the diffusion / first stage premixed hybrid combustion mode is achieved by increasing the fuel to the first stage premixing nozzle while reducing the fuel to the diffusion burner. The temperature of the combustion gas is low and the amount of NOx generated is small until the ignition is reliably performed.

Further, when premixed combustion exists on the downstream side of the combustor, the flame holding ability decreases due to the temperature decrease of the combustion gas on the upstream side of the combustor, so the combustion efficiency of the premixed flame decreases and the flame blows off. However, the diffusion combustion mode is switched to the diffusion / first stage premixed hybrid combustion mode before the secondary premixture and the tertiary premixture on the downstream side of the combustor are supplied. Therefore, it is possible to avoid a decrease in the combustion efficiency of the premixed flame and the occurrence of flame blowout.

Further, during combustion of the gas turbine from high load to rated load, the combustion ratio of diffusion combustion can be reduced and the entire combustor can be premixed combustion-based combustion. The overall amount of NOx generated can be suppressed to an extremely low level.

[0023]

Embodiments of the present invention will be described below with reference to FIGS. 1 is an explanatory view of a gas turbine premixed combustor of the present embodiment, FIG. 2 is a diagram showing a gas turbine load and a fuel control / supply method of the present embodiment, and FIG. 3 is a first stage combustion chamber of FIG. FIG. 5 is an explanatory diagram of a flammable condition of the premixed flame in FIG. FIG. 4 is an explanatory diagram of a change state of the combustion gas temperature / fuel distribution during the fuel switching period in the first-stage combustion chamber of FIG.

The gas turbine power plant comprises a compressor 1, a combustor 2 and a turbine 3, and an output of the turbine 3 drives a generator 4. The combustor 2 is a can-type combustor, and includes a turbine casing 5, a combustor outer cylinder 6, and a combustor cover 7.
The diffusion burner 14 is attached to the center of the upstream end surface of the combustor 2, and the primary premixed gas supply device 11 is attached to the outer peripheral side of the diffusion burner 14.

Further, a reduced portion in which the diameter of the combustor 2 is narrowed is provided in each of the intermediate portion and the downstream portion toward the downstream side of the combustor 2, and the secondary premixed gas supplier 12 is provided in these reduced portions. And a tertiary premixed gas supply device 13 are attached respectively, and the outlet end of the combustor 2 is connected to the combustor transition piece 8. That is, the combustor 2 includes a first-stage combustion chamber I, a first-stage mixing region II, a second-stage combustion chamber III, a second-stage mixing region IV, and a third-stage combustion chamber V, which are arranged from the upstream side to the downstream side. It is composed.

The diffusion burner 14 attached to the upstream end of the first-stage combustion chamber I has a flame swirler 10 for holding flame.
Is equipped with. The air swirler 10 has been conventionally used in a gas turbine premix combustor.

The primary premixed gas supply device 11 mounted on the outer peripheral side of the diffusion burner 14 has a diameter reduced toward the downstream side of the combustor 2 and is formed by one inner wall and one outer wall. A flow path for the next premixed air mixture 36 is formed, the upstream end of the flow path is opened as an inlet for the primary premixed air 33, and the downstream end is opened inside the first stage combustion chamber I.

A plurality of first-stage premixing nozzles 15 are attached at appropriate intervals upstream of the flow path of the first-stage premixing gas 36. The fuel 29 is injected to form the primary premixed gas 36, which is supplied into the first-stage combustion chamber I.

Connected to the downstream end of the first-stage combustion chamber I 1
On the outer peripheral side of the stage mixing region II, the downstream side end of the above-mentioned secondary premixed gas supply device 12 is attached. Ie 2
The secondary premixed air supply device 12 forms a tubular flow path, and its upstream end faces the flow direction of the compressor discharge air 32.

The secondary premixed air supply device 12 takes in the secondary premixed air 34, and the secondary premixed air 34 and the secondary premixed air 34.
A secondary premixed gas 37 is formed by the secondary premixed fuel 30 supplied from the second stage premixing nozzle 16 provided on the downstream side of the opening of the secondary premixed air 34, and the secondary premixed gas 37 is formed. ,
The fuel is supplied from the outer peripheral side of the first-stage mixing region II into the first-stage mixing region II in a direction substantially perpendicular to the axis of the combustor 2. It should be noted that the distance between the combustion injection position and the premixed gas outlet is set to such a length that the mixing of the fuel and air can be sufficiently homogenized.

The secondary premixed gas 37 supplied into the first-stage mixing area II and the combustion gas generated in the first-stage combustion chamber I are mixed with each other.
They are mixed in the second-stage mixing region II to form a predetermined high temperature combustible gas, and burned in the second-stage combustion chamber III.

At the outer periphery of the second-stage mixing region IV connected to the downstream end of the second-stage combustion chamber III, a tertiary premixed gas supply device having the same shape as the above-mentioned secondary premixed gas supply device 12 is provided. The downstream end of 13 is attached. That is, the third premixed air 35
And the third premixed fuel 31 supplied from the third stage premixing nozzle 17 to form a third premixed gas mixture 38,
The tertiary premixed gas 38 is supplied into the combustor 2 from the outer periphery of the second-stage mixing area IV in a manner substantially perpendicular to the axis of the combustor 2 into the second-stage mixing area IV.

The tertiary premixed gas 38 supplied into the second-stage mixing region IV is mixed with the combustion gas generated in the first-stage combustion chamber I and the second-stage combustion chamber III in the second-stage mixing region IV. Form a high temperature combustible gas of a predetermined temperature, and this high temperature combustible gas is 3
The high-temperature combustion gas 39 is burned in the stage combustion chamber V, and the high-temperature combustion gas 39 is guided to the turbine vane 9 via the combustor transition piece 8.

For supplying fuel, the first stage fuel system 18, 2
There are a second stage fuel system 21 and a third stage fuel system 22, which are respectively provided by a first stage fuel flow rate control valve 23, a second stage fuel flow rate control valve 26 and a third stage fuel flow rate control valve 27. The fuel flow rate is adjusted for each system. Furthermore,
The first stage fuel system 18 is branched into a diffusion fuel system 19 and a primary premixed fuel system 20, and the fuel flow rate in these systems is controlled by the diffusion fuel flow rate control valve 24 and the primary premixed fuel flow rate control valve 25. Each is adjusted.

Next, a method of operating the gas turbine premixed combustor of this embodiment will be described with reference to FIG. The abscissa of FIG. 2 represents the gas turbine load as a percentage, and the ordinate represents the fuel supplied at the full load of the gas turbine as 100%,
The distribution ratio of the fuel supplied to each fuel system in each load is expressed as a percentage.

From the start-up of the gas turbine to about 10% load, that is, A in FIG. 2, the gas turbine is operated only with the diffusion fuel 28. That is, from the start of the gas turbine up to about 10% load, the variation range of the fuel flow rate and the air flow rate is large, and in order to ensure stable combustion when the load is cut off, diffusion combustion with high flame holding characteristics is performed. It is done.
Although not shown in FIG. 2 from the time of starting to the time of 0% load, it is omitted because it does not directly affect the description of the present embodiment.

When the operation of the gas turbine reaches A in FIG. 2, the fuel switching operation of the diffusion fuel 28 is performed.
That is, most of the diffusion fuel 28 is the primary premixed fuel 29.
The amount of the diffused fuel 28 is reduced by turning it to, the primary premixed fuel 29 supplied from the primary premixed fuel system 20 is burned by the flame produced during the diffuse combustion, and the generated premixed fuel 29 is further produced. Holds mixed flames. And
Finally, the diffusion fuel system 19 and the primary premixed fuel system 2
The fuel switching operation is completed by setting the flow rate ratio of the diffusion fuel 28 and the primary premixed fuel 29 at 0 to about 1 to 9.

In order to enable such fuel switching, it is necessary that the fuel / air ratio of the primary premixed gas mixture 36 be equal to or higher than the so-called combustible fuel / air ratio. Figure 3
It is an explanatory view of the flammability condition of the premixed flame in the first-stage combustion chamber, and shows the relationship diagram between the gas turbine load and the premixed fuel-air ratio, but the fuel-air ratio is approximately 0.026 or more, and the gas turbine If the load is about 5% or more, fuel switching is possible.

Further, FIG. 4 is an explanatory diagram of a change state of the combustion gas temperature / fuel distribution during the fuel switching period in the first-stage combustion chamber of FIG. 1, and FIG. The change state of the combustion gas temperature, and FIG. 4B shows the change state of the combustion gas temperature with respect to the elapsed combustion time.

Even in the case of adopting the diffusion / first stage premixed hybrid combustion mode as in this embodiment, the fuel gas is not burned until the combustion efficiency of the premixed flame becomes sufficiently high. As it flows out, the combustion gas temperature temporarily drops. ΔTf in FIG. 4A indicates the combustion gas temperature drop.

The combustion gas temperature drop ΔTf is supplied before the first-stage premixed fuel 29 is narrowed down to the diffusion fuel 28, or the flame produced by the first-stage premixed combustion and the diffusion combustion. By promoting the contact with the flame due to, the combustibility of the premixed flame can be improved and reduced. That is, in this way, it is possible to suppress the combustion gas temperature drop to a small extent, but it is difficult to eliminate it, and correspondingly, a load drop of the gas turbine also occurs.

However, in the diffusion / first stage premixed hybrid combustion of the present embodiment, since the fuel flow rate of the primary premixed fuel 29 is large and the fuel-air ratio of the primary premixed gas 36 is also large, the fuel gas temperature is high. Also, both the gas turbine load and the gas turbine load are restored to the same values after the fuel switching and before the fuel switching in a short time, and the content ratio of the NOx amount in the combustion gas is also greatly reduced.

After the completion of the fuel switching in the first-stage combustion chamber I, the gas turbine is operated by the injection of the secondary premixed fuel 30 to the gas turbine load as shown by B in FIG. In this case, the combustion gas in the first mixing region II is set to a high temperature equal to or higher than a predetermined temperature. In this embodiment, this temperature is set to approximately 1200 ° C., and under this condition, even a very thin mixture of fuel burns with high combustion efficiency.

From the gas turbine load (B in FIG. 4) to 100% load, that is, the rated load, the flow rates of the diffusion fuel 28, the primary premixed fuel 29, and the secondary premixed fuel 30 are almost the same. After being kept constant, the third premixed fuel 31 is further supplied to operate the gas turbine. The combustion gas temperature in the second mixing zone IV is the first mixing zone
The same as the case of II, and at 100% load, about 95% or more of the total fuel is burned as premixed combustion.

That is, in the case of the premixed combustor of the same type as that of this embodiment, the combustion performance of the premixed flame in the second-stage combustion chamber III and the third-stage combustion chamber V is the combustion performance in the mixing region on the upstream side of each stage. Strongly depends on gas temperature. In particular, when the combustion gas temperature becomes lower than a predetermined value, the combustion speed is remarkably reduced, and the flame is extinguished.

However, in this embodiment, the second stage combustion chamber II
I, before the flame is generated in the third-stage combustion chamber V, the fuel is switched in the upstream first-stage combustion chamber I to form the premixed combustion mode, so that stable combustion is achieved over the entire gas turbine load. Can be realized and low N
Ox conversion is possible.

[0047]

According to the present invention, NOx by the diffusion burner is maintained without impairing the degree of freedom and reliability in the operation of the gas turbine from the start of the gas turbine to the rated operation.
It is possible to provide a combustion method of a gas turbine premixed combustor capable of suppressing the generation amount.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a gas turbine premix combustor according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a fuel supply / control method according to an embodiment of the present invention.

3 is an explanatory diagram of a flammability condition of a premixed flame in the first-stage combustion chamber of FIG.

FIG. 4 is an explanatory diagram of combustion gas temperature / fuel distribution in the first stage combustion chamber of FIG. 1.

[Explanation of symbols]

1 ... Compressor, 2 ... Combustor, 3 ... Turbine, 4 ... Generator,
5 ... Turbine casing, 6 ... Combustor outer cylinder, 7 ... Combustor cover, 8 ... Combustor tail cylinder, 9 ... Turbine vanes, 10 ... Air swirler, 11 ... Primary mixture supply, 12 ... Secondary Air-fuel mixture feeder, 13 ... tertiary air-fuel mixture feeder, 14 ... diffusion burner,
15 ... 1st stage premixing nozzle, 16 ... 2nd stage premixing nozzle, 17 ... 3rd stage premixing nozzle, 18 ... 1st stage fuel system, 19 ... Diffusion fuel system, 20 ... Primary premixing fuel system,
21 ... 2nd stage fuel system, 22 ... 3rd stage fuel system, 23 ...
First stage fuel flow rate control valve, 24 ... Diffusion fuel flow rate control valve, 2
5 ... Primary premixed fuel flow rate adjusting valve, 26 ... Second stage fuel flow rate adjusting valve, 27 ... Third stage fuel flow rate adjusting valve, 28 ... Diffusion fuel, 29 ... Primary premixed fuel, 30 ... Secondary premixing Fuel, 3
1 ... 3rd premixed fuel, 32 ... Compressor discharge air, 33 ... 1
Secondary premixed air, 34 ... secondary premixed air, 35 ... tertiary premixed air, 36 ... primary premixed air, 37 ... secondary premixed air, 3
8 ... Tertiary premixed gas, 39 ... High temperature combustion gas, I ... 1st stage combustion chamber, II ... 1st stage mixing region, III ... 2nd stage combustion chamber, IV ...
2nd stage mixing area, V ... 3rd stage combustion chamber.

Front Page Continuation (72) Inventor Shohei Yoshida, 502 Jinritsu-cho Machinery Research Center, Tsuchiura-shi, Ibaraki Machinery Research Laboratories, Ltd. (72) Inventor Tomoki Koganazawa 502 Jinrachicho, Tsuchiura City, Ibaraki Prefecture Inside the Hiritsu Seisakusho Mechanical Research Laboratory

Claims (3)

[Claims] 1. A diffusion burner is provided at the center of the upstream end surface of the combustion gas flowing in the combustor of a gas turbine combustor, and a mixture of primary air and primary fuel is provided on the outer peripheral side of the diffusion burner. A first stage premixing nozzle for supplying a certain primary premixed gas is provided, and at least one of the fuel supplied from the diffusion burner and the primary premixed gas supplied from the first stage premixing nozzle is provided. A first-stage combustion chamber to be burnt is formed in a space extending from the upstream end face to the downstream side, and on the outer peripheral side of the downstream end of the first-stage combustion chamber,
It has a secondary premixed gas supply means for supplying a secondary premixed gas mixture which is a mixture of secondary air and secondary fuel, and is located in the space downstream of the position having the secondary premixed gas supply means. A second-stage combustion chamber that burns the secondary pre-mixture is formed, and a tertiary mixture that is a mixture of tertiary air and tertiary fuel is provided on the outer peripheral side of the downstream end of the second-stage combustion chamber. A third-stage combustion chamber that has a tertiary premixed gas supply means for supplying the premixed gas, and that burns the tertiary premixed gas in a space downstream of the position where the tertiary premixed gas supply means is provided. In a combustion method of a gas turbine premixed combustor configured and formed, a combustion gas generated by fuel supplied from the diffusion burner to the first-stage combustion chamber can oxidize the primary premixed gas. Until the temperature is reached, the fuel is supplied only from the diffusion burner to generate combustion gas. Is, after reaching the temperature, the most of the fuel supplied from the diffusion burner 1
The load of the gas turbine in the first-stage combustion chamber by the diffusion / first-stage premix hybrid combustion method in which the diffusion burner and the first-stage premix nozzle are operated by turning to the fuel of the next premix mixture. And then the secondary premixed gas supply means supplies the secondary premixed gas to the second-stage combustion chamber to increase the load of the gas turbine by the second-stage combustion, After the gas turbine reaches a predetermined load, the tertiary premixed gas is supplied to the third-stage combustion chamber, and the gas turbine is operated up to the rated load by combustion inside the third-stage combustion chamber. A method for combusting a gas turbine premix combustor, comprising: 2. The method of turning the fuel supplied from the diffusion burner into the fuel of the primary premixed gas in the diffusion / first stage premixed hybrid combustion method is the diffusion burner and the first stage premixed nozzle. And a fuel supply system for the diffusion burner and a fuel supply system for the first stage premixing nozzle, and a fuel supply system for the diffusion burner and the first stage. The combustion method for a gas turbine premix combustor according to claim 1, wherein a flow control valve is attached to each of the fuel supply system to the premix nozzle and the opening / closing of the flow control valve is adjusted. 3. In the diffusion / first stage premix hybrid combustion method, the total amount of fuel supplied from the diffusion burner and the first stage premix nozzle is constant, and the fuel supplied from the diffusion burner and the fuel supplied from the diffusion burner are the same. The combustion method for a gas turbine premix combustor according to claim 1 or 2, wherein the flow rate ratio of the fuel supplied from the first-stage premix nozzle is 1: 9.