JPH05195822A - Gas turbine combustor and load control method - Google Patents

Abstract

PURPOSE:To reduce the number of fuel nozzles according to load under a low load condition so as to carry out low NOx premixture combustion in a wire load range by dividing a plurality of fuel nozzles provided in a premixture flow passage into a plurality of groups, and controlling the fuel flow amount of respective groups independently. CONSTITUTION:A diffusion combustion system is introduced at a first step, and a premixture combustion system is introduced at a second step, in a gas turbine combustor. Air supplied from a compressor is led into a combustor casing 10. Air flows into a combustion chamber 15 from respective combustion air holes 13, 33 of first step and second step combustor liners 30, 31, and a second step premixture flow passage 32. Fuel F1 in the first step is injected from a fuel nozzle 34 into the combustion chamber 15, and diffusion combustion is carried out. In this case, fuel F2 in the second step is divided into two systems F2-1, F2-2, and the divided fuels are injected from respective fuel nozzles 35, 351. After the divided fuels are mixed with air in the premixture flow passage 32, they are supplied into the combustion chamber 15, and premixture combustion is carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine combustor, and more particularly to a combustor and a fuel control method suitable for load control of a low NOx premixed combustor.

[0002]

2. Description of the Related Art A gas turbine combustor has used a diffusion combustion system having excellent stability. However, as environmental problems have become more serious in recent years, the reduction of NOx in gas turbines has become an important issue, and combustors employing a premixed combustion method, which is advantageous in reducing NOx, have been put to practical use.

In order to perform premixed combustion, it is necessary to devise a premixing device for mixing fuel and air and a method for stabilizing combustion. As one example, a two-stage combustion technology combining diffusion combustion and premixed combustion is disclosed (US Patent.
4,898.001). Its structure is shown in FIG. This is a gas turbine combustor that employs a premixed combustion method that is advantageous in diffusion combustion in the first stage and low NOx in the second stage, and the air supplied from the compressor is introduced into the combustor casing 10. Here, the air enters the combustion chamber 15 through the combustion air holes 13 and 33 opened in the first-stage combustor liner 30, the second-stage combustor liner 31, and the second-stage premix flow passage 32, respectively. The first-stage fuel (F1) is injected from the fuel nozzle 34 into the combustion chamber and diffuse-combusted. The second-stage fuel (F2) is injected from the fuel nozzle 35 and flows into the premixing passage 32 to mix with air to form a premixed mixture with an appropriate ratio, and then flows into the combustion chamber 15 for premixed combustion. .. This combustion gas is diluted with air holes 14
It is diluted with the air entering from and is introduced to the turbine.

Here, FIGS. 3 and 4 are enlarged views of the portion for premixing the second stage fuel and air. Premixing channel 3
2 has a shape in which an annular flow path is partitioned by a large number of partition plates 40. The fuel nozzles are projected from the fuel manifold 36 to the center of each flow passage, and the fuel gas ejected from the fuel injection holes 37 opened near the tip of the fuel nozzle 36 in four directions orthogonal to the main air flow flows into the air while flowing through the flow passage. Is mixed with the mixture to form a premixed gas, which flows out into the combustion chamber and is premixed and burned.

Next, FIG. 5 shows the relationship between the load of the present combustor, the fuel flow rate, and the NOx concentration in the exhaust gas. At low load, fuel is injected only in the first stage diffusion combustion, and above a certain load, 2
The load was controlled by injecting fuel into the premixed combustion in the second stage and controlling both diffusion and premixed fuel.

[0006]

SUMMARY OF THE INVENTION In the above-mentioned conventional technique, a large number of fuel nozzles are installed in the inner circumferential direction of the annular premixing passage to uniformly disperse and mix the fuel to realize lean premixed low NOx combustion. Has become. However, if the fuel supply amount is reduced in order to reduce the load, the fuel supply system is only one system, so the fuel concentration at the outlet of the premixing flow passage decreases uniformly, and combustion instability occurs at a certain concentration or less, There has been a problem that the possible load range of low NOx premixed combustion is narrow.

The object of the present invention is to achieve low N over a wide load range.
An object of the present invention is to provide a combustor capable of Ox premixed combustion and a control method thereof.

[0008]

The above object can be achieved by dividing a plurality of fuel nozzles in a premixing passage into a plurality of groups and controlling the fuel supply amount of each group according to the load of combustion.

[0009]

[Function] Under low load operating conditions, the number of fuel nozzles that supply fuel according to the load is reduced to secure a fuel flow rate per fuel nozzle that is supplying fuel. The fuel concentration at the flow path outlet can be maintained at a concentration capable of stable combustion, and low NOx premixed combustion can be performed in a low load range as a whole.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. This is a gas turbine combustor that employs a premixed combustion method that is advantageous in diffusion combustion in the first stage and low NOx in the second stage, and the air supplied from the compressor is the combustor casing 10.
Will be introduced to. Here, the air is the first stage combustor line 30,
The air enters the combustion chamber 15 through the combustion air holes 13 and 33 opened in the second-stage combustor liner 31 and the second-stage premix flow passage 32, respectively. The first stage fuel (F1) is the fuel nozzle 34
Is injected into the combustion chamber from and diffuses and burns. The second-stage fuel (F2) is divided into two systems, F2-1 and F2-2, which are injected from the fuel nozzles 35 and 351 and premixed with the flow passage 32.
While flowing inside, it mixes with air to form a premixed gas with an appropriate ratio and flows into the combustion chamber 15 for premixed combustion. This combustion gas is diluted by the air that has entered through the dilution air holes 14 and is introduced into the turbine.

An enlarged view of the premixing flow path portion is shown in FIGS. 6 to 8. FIG. 6 is a schematic cross-sectional view of the premixing channel 32, in which the annular channel is partitioned by a large number of partition plates 40. Here, the F2-1 fuel nozzles 35 and the F2-2 fuel nozzles 351 are alternately installed in the circumferential direction, and protrude from the fuel manifolds 38 and 39 to the center of their respective flow passages as shown in the sectional views of FIGS. 7 and 8. The fuel gas ejected from the fuel injection holes 41, 42 opened near the tip of the fuel gas in four directions orthogonal to the main air flow mixes with the air while flowing through the flow path to become a premixed gas and flows out into the combustion chamber. Then premix combustion.

Next, FIG. 9 shows the relationship between the fuel flow rate of the present combustor and the gas turbine load. In the low load region shown in (A) in the figure, only the F1 of the diffusion combustion is operated, and then in the (B) region, fuel is injected into the F2-1 (fuel nozzle 35) of the premixed combustion to further increase the load ( In the area C), fuel is also injected into F2-2 (fuel nozzle 351). With such a configuration and operation, the fuel concentration is diluted at the exit of the premixing flow path and combustion instability is conventionally caused, and the fuel is supplied only to the fuel nozzle 35 even in the region (B) where the premixed combustion cannot be performed. As a result, premixed combustion becomes possible in the downstream portion of the fuel nozzle 35, and low NO in a wide load range.
x Premixed combustion is possible. Further, in the present embodiment, by appropriately setting the ratio of the fuel to be supplied to the fuel nozzles 35 and the fuel nozzles 351, it is possible to broaden the stable combustion range by positively giving a shade to the fuel concentration distribution at the outlet of the premixing passage. Is. Fuel nozzles 35 and 351
Various combinations can be considered for the method of division, but one example is shown in FIGS. 10 and 11. FIG. 10 shows the case of dividing into two in the circumferential direction, and FIG. 11 shows the case of dividing into three more finely.

Next, another embodiment of the present invention will be described with reference to FIGS.
5 shows. 12 and 13 show a small premixed combustor element 5
This is a type of combustor in which 6 pieces of 0 are incorporated in one combustor liner 31. The premix combustor element has a sectional structure as shown in FIG. 14, and the pilot fuel injection hole 5 is provided at the center.
1, a ring-shaped premixing channel 32 and a premixing fuel nozzle 352 are installed around it. Premix fuel nozzle 35
No. 2 is divided into two groups as shown in FIG. 15, and fuel is supplied to all nozzles at high load, but at low load, one of the two groups of premixed fuel nozzles is not supplied with fuel and partially loaded. Drive. By performing such an operation in each premixed combustion element, the load control range of the premixed combustion can be expanded and the temperature distribution in the combustor can be kept uniform.

[0014]

According to the present invention, by reducing the number of fuel nozzles that supply fuel according to the load under low load operating conditions,
It is possible to secure the fuel flow rate for each fuel nozzle that is supplying fuel, and to maintain the fuel concentration at the flow path outlet downstream of this fuel nozzle at a concentration that allows stable combustion, thus reducing NOx to a low load range as a whole. Premixed combustion is possible.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a conventional example.

FIG. 3 is a cross-sectional view of a premixing channel of a conventional example.

FIG. 4 is a cross-sectional view of a conventional premixing channel.

FIG. 5 is an explanatory diagram of fuel control of a conventional example.

FIG. 6 is a cross-sectional view of a premixing channel according to the embodiment of the present invention.

FIG. 7 is a sectional view of a premixing flow channel according to the embodiment of the present invention.

FIG. 8 is a sectional view of a premixing flow channel according to the embodiment of the present invention.

FIG. 9 is an explanatory view of fuel control according to the embodiment of the present invention.

FIG. 10 is a supplementary explanatory diagram of the embodiment of the present invention.

FIG. 11 is a supplementary explanatory diagram of the embodiment of the present invention.

FIG. 12 is an explanatory diagram of another embodiment of the present invention.

FIG. 13 is an explanatory diagram of another embodiment of the present invention.

FIG. 14 is an explanatory diagram of another embodiment of the present invention.

FIG. 15 is an explanatory diagram of another embodiment of the present invention.

[Explanation of symbols]

35, 351, 352 ... Premix fuel nozzle, 32 ... Premix flow passage, 33 ... Premix combustion air hole, 36, 38, 39
… Fuel manifold.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Satoru Tsukahara, Satoshi Tsukaura, Ibaraki Prefecture, 502 Jinritsu-cho, Hiratsugu Co., Ltd.Mechanical Research Laboratory (72) Inventor, Noriyuki Hayashi, 502, Kintate-cho, Tsuchiura-shi, Ibaraki, Hitate Co., Ltd. Mechanical Research Laboratory (72) Inventor Tamio Inami 502 Jinritsucho, Tsuchiura-shi, Ibaraki Hiritsu Manufacturing Co., Ltd.Mechanical Research Laboratory (72) Inventor ▲ Shohei Tada 502 Jinmachi-cho, Tsuchiura-shi, Ibaraki Hiritsu Manufacturing Machinery Co., Ltd. In-house (72) Inventor Yasuhiko Otawara 1-1-1, Sachimachi, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Factory (72) Inventor Tomio Kuroda 3-1-1, Sachimachi, Hitachi, Ibaraki Stock Association Company Hitachi, Ltd.Hitachi factory

Claims (4)

[Claims] 1. A gas turbine combustor having a single or a plurality of premixing passages for mixing fuel and air, and a plurality of fuel nozzles provided in the premixing passages, wherein the plurality of fuel nozzles are provided. A gas turbine combustor characterized by being divided into groups and provided with means for independently controlling the fuel flow rate of each group. 2. The combustor according to claim 1, wherein the premixing passage opening in which the plurality of fuel nozzles are installed forms a continuous flame port. 3. A gas turbine combustor having a single or a plurality of premixing passages for mixing fuel and air, and a plurality of fuel nozzles provided in the premixing passages, wherein the plurality of fuel nozzles are provided. A means for independently controlling the fuel flow rate of each group is provided, and a load range for stopping or limiting the fuel supply of some of the plurality of fuel nozzle groups in the combustor partial load is provided. A method for controlling a gas turbine combustor, which is characterized. 4. A premixing apparatus having a single or a plurality of premixing channels for mixing fuel and air, and a plurality of fuel nozzles provided in the premixing channel, wherein a plurality of fuel nozzles are installed. In a gas turbine combustor in which a passage opening forms a continuous flame port, the fuel nozzle is divided into a plurality of groups, and means for independently controlling the fuel flow rate of each group is provided. A method for controlling a gas turbine combustor, characterized in that a load range for stopping or limiting fuel supply to some groups is provided in the combustor partial load.