JPH11264541A - Gas turbine combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve such a trouble that the sectional load factor increases partially and causes unstable combustion and that the occurrence of Nox increases, in a gas turbine combustor which is supplied with compressed air and fuel and brings the combustion (gas) to drive a gas turbine into existence. SOLUTION: Main fuel 15, which ignites by the flame kept by the pilot nozzle 2 arranged at the axis of a tubular upstream inner tube 6 made symmetrical about an axis and performs main combustion, is supplied to a gas turbine combustor, being divided in the direction of the flow of the air 21 for combustion within a combustion chamber which is so arranged as to let flow the air 21 for combustion made into a whirling flow by a swirler 3 arranged around a pilot nozzle 2. Hereby, the above-mentioned trouble is dissolved, and also the combustion gas comes to high temperature and high pressure conditions, and in case that it becomes the load to satisfy the self ignition condition of the main fuel 13, this combustor can materialize stable combustion state even if the user stops the supply of pilot fuel 13.

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 for generating a combustion gas for driving a gas turbine, and more particularly to a main fuel divided and supplied in a flow direction of the combustion gas in the combustor. Thus, the present invention relates to a gas turbine combustor capable of suppressing stable combustion and NOx generation in a combustion chamber.

[0002]

2. Description of the Related Art In a gas turbine, compressed air and fuel from a compressor driven by the gas turbine are supplied to a gas turbine combustor and burned to generate high-temperature, high-pressure combustion gas. The gas turbine is operated by the gas to drive the above-described compressor and to obtain an external outlet for driving a generator and the like. FIG. 3 is a partial longitudinal sectional view of a conventional combustor in which compressed air and fuel are supplied to generate combustion gas, as described above.

As shown in the figure, generally, in a conventional gas turbine combustor 1, an axially symmetrical cylindrical upstream inner cylinder 6, and a front end connected to a rear end of the upstream internal cylinder 6 are connected. A combustion chamber 12 is formed, which is defined by being surrounded by the downstream side inner cylinder 7, and a pilot nozzle 2 is attached to a central portion of the upstream side wall of the combustion chamber 12, and a pilot nozzle 2 is provided on an outer periphery of the pilot nozzle 2. The pilot swirlers 3 that generate a swirling flow in the pilot air 4 as a part of the combustion air supplied in front of the pilot nozzle 2 are provided at a constant pitch in the circumferential direction.

Further, a pilot swirler 3 is provided, and a plurality of main nozzles 8 are arranged at equal intervals in the circumferential direction outside a pilot air flow path 5 through which the pilot air 4 flows. ing. In addition, a swirling flow is supplied to the outer periphery of each main nozzle 8 through a main air flow path 11 to the front end of the main nozzle 8 and to main air 10 as combustion air for performing main combustion. The main swirlers 9 to be generated are provided at equal pitches in the circumferential direction.

[0005] When the gas turbine combustor 1 thus configured is operated, the swirling flow is generated by the pilot swirler 3 and introduced into the combustion chamber 12 through the pilot air flow path 5. A pilot fuel 13 is injected from the pilot nozzle 2 and mixed therein, ignited by an ignition plug (not shown), and expanded from the outer periphery of the outlet of the pilot air flow path 5 rearward. After a recirculation area 14 for flame holding is formed on the downstream side of the duct 16, the main swirler 9 is
The swirling flow is applied to the main air 10 supplied to the tip of the main nozzle 8 through the plurality of main air passages 11, from the main nozzles 8 provided at the axial centers of the respective main air passages 11. , Injecting the main fuel 15,
The mixture is ignited to generate a high-temperature, high-pressure combustion flame.

[0006] The combustion gas generated by the combustion flame is led out from the outlet of the combustion chamber 12 (not shown), is speed-controlled by the stationary blades, is sent to the moving blades, and generates a driving force for the gas turbine.

The upstream inner cylinder 6 in which the pilot nozzle 2, the main nozzle 8 and the like are disposed inside.
As shown in the figure, a downstream inner cylinder 7 having a front end connected to a rear end thereof to form a combustion chamber 12 together with an upstream inner cylinder 6 has a plurality of outer diameters that are increased toward the downstream side. The connecting portion of the downstream inner cylinder 7 which is formed of
A gap is formed, and a part of the compressed air flowing outside the upstream-side inner cylinder 6 and the downstream-side inner cylinder 7 flows into the downstream-side inner cylinder 7 as cooling air 17 from this gap. It flows along the inner peripheral surface of the side inner cylinder 7 and cools the downstream inner cylinder 7 from the inside to protect it from high temperature and high pressure combustion gas.

As described above, in the conventional gas turbine combustor 1, the pilot nozzle 2, the main nozzle 8, and the like are disposed in the upstream inner cylinder 6 on the upstream side of the combustion chamber 12, and the pilot fuel 13 and the main fuel All of 15,
In other words, all the fuel required to operate the gas turbine
Since the fuel is supplied on the upstream side of the combustion chamber 12, the unburned fuel ratio of the supplied fuel is increased on the upstream side as shown in the unburned fuel combustor axial distribution shown in FIG. Although the distribution becomes large, the distribution gradually decreases toward the downstream side. That is, although the ratio of the amount of fuel burning in a certain cross section in the combustion chamber 12, that is, the cross-sectional load factor increases on the upstream side, a certain unburned charge ratio is maintained in a certain range on the downstream side. Since the sectional load factor is shared, combustion in the combustion chamber 12 can maintain stable combustion and low NOx.

However, in recent years, in gas turbines which require high temperature and high pressure of the combustion gas in order to increase the size and increase the efficiency, the high temperature and high pressure of the combustion gas cause The reaction speed of the fuel supplied to the inside of the fuel cell 12 increases, and therefore, if 100% fuels 13 and 15 required for the operation of the gas turbine are supplied on the upstream side, the fuel is immediately burned on the upstream side. The unburned fuel is hardly distributed on the downstream side, the cross-sectional load factor increases on the upstream side, the combustion in the combustion chamber 12 becomes unstable, and the generation of NOx increases. The problem has arisen.

[0010]

SUMMARY OF THE INVENTION The present invention is directed to a gas turbine which is required to have a high temperature and a high pressure of a combustion gas in order to increase the size and the efficiency, as well as a conventional gas turbine. Instability of combustion state or NOx caused when 100% fuel is supplied to the upstream side of the combustion chamber
An object of the present invention is to provide a gas turbine combustor capable of solving the problem of increased generation.

[0011]

For this reason, the gas turbine combustor of the present invention has the following means.

(1) The main fuel, which ignites by the flame holding of the pilot nozzle disposed at the axial center of the axially symmetrical cylindrical upstream inner cylinder and performs main combustion, is provided on the outer periphery of the pilot nozzle. A combustion chamber formed by an upstream inner cylinder and a downstream inner cylinder having a distal end connected to the upstream inner cylinder, in which the swirling combustion air is caused to flow by the disposed swirler. The air was divided and supplied in the direction of the air flow.

(A) Due to this, in recent years, it has become necessary to increase the temperature and pressure of the combustion gas in order to increase the size and increase the efficiency, and the combustion gas is supplied into the combustion chamber by the high temperature and pressure. Even in a gas turbine where the reaction speed of fuel increases, the proportion of unburned fuel in the fuel supplied to the combustion chamber should have a distribution that smoothly fluctuates in the direction of the flow of combustion air flowing through the combustion chamber. Can be.

That is, the sectional load factor is prevented from locally increasing, particularly on the upstream side, so that the combustion in the combustion chamber is in a stable combustion state, and the generation of NOx due to the combustion is reduced. it can. Further, the gas turbine combustor of the present invention employs the following means in addition to the above-mentioned means (1).

(2) An upstream forming the combustion chamber at a supply position determined so that the main nozzle for supplying the main fuel into the combustion chamber is divided in the direction of the flow of the combustion air to supply the main fuel. It is provided so as to penetrate the side inner cylinder and the downstream inner cylinder.

(B) Accordingly, in addition to the above (a), the distribution of the unburned fuel ratio in the axial direction of the combustion chamber can be freely controlled by individually controlling the fuel injected from each main nozzle. As a result, the combustion state can be made more stable, and the generation of NOx can be effectively reduced.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a gas turbine combustor according to the present invention will be described below with reference to the drawings. FIG.
1 is a partial longitudinal sectional view showing a first embodiment of a gas turbine combustor according to the present invention. In the figure, the same or similar members as those of the conventional gas turbine combustor shown in FIG.

As shown in the figure, the gas turbine combustor 20 of the present embodiment has a cylindrical upstream-side inner cylinder 6 formed axially symmetrically and a front end connected to a rear end of the upstream-side inner cylinder 6. A divided combustion chamber 12 is defined by being surrounded by the downstream inner cylinder 7, and a pilot nozzle 2 is attached to a central portion of the upstream side wall of the combustion chamber 12, and an outer periphery of the pilot nozzle 2 is formed. A pilot swirler 3 having a base end fixed to the outer peripheral surface of the pilot nozzle 2 for generating a swirling flow in the combustion air 21 supplied in front of the pilot nozzle 2 is provided at a constant pitch in the circumferential direction. I have.

Further, a pilot swirler 3 is provided between the outer peripheral surface to which the tip of the pilot swirler 3 is fixed and the inner peripheral surface which is the outer peripheral surface of the pilot nozzle 2, so that the combustion air 21 flows. The main nozzles 22a to 22a through which the upstream inner cylinder 6 and the downstream inner cylinder 7 penetrate through the upstream inner cylinder 6 and the downstream inner cylinder 7 at intervals in the axial direction of the combustion air 21 in the combustion chamber 12 flowing from the exit side of the combustion air flow path 23. A plurality of main nozzles 22f are provided.

In the gas turbine combustor 20 of the present embodiment configured as described above, the pilot fuel 13
Is supplied from the pilot nozzle 2. Further, the swirling force is applied to the combustion air 21 by the pilot swirler 3 and supplied to the combustion chamber 12. For this reason, in front of the pilot nozzle 2, similarly to the conventional gas turbine combustor 1, a flame holding recirculation region 14 is formed upstream of the combustion chamber 12, and the flame holding is performed.

When the load of the gas turbine is low, the temperature of the combustion gas generated in the combustion chamber 12 is low.
5, the main fuel 15 is supplied only from the main nozzle 22a provided to penetrate the pilot nozzle 2 and the upstream inner cylinder 6, and the main fuel 15 is supplied 100% upstream of the combustion chamber 12. I am trying to supply.

Further, when the gas turbine is under heavy load, the main fuel 15 is also supplied from the main nozzles 22b to 22f provided through the downstream inner cylinder 7, so that the main fuel 15 is also provided on the downstream side of the combustion chamber 12. So that the supply of the main fuel 15 is distributed and supplied in the axial direction of the combustion chamber 12.

That is, when the gas turbine has a low load,
On the upstream side of the combustion chamber 12, 100
By supplying%, the unburned combustion ratio of the main fuel 15 in the axial direction in the combustion chamber 12 becomes as shown by the solid line in FIG. 2. When the gas turbine is under a high load, it is necessary for the operation of the gas turbine. By dividing and supplying the main fuel 15 from the upstream side to the downstream side of the combustion chamber 12, the unburned combustion ratio of the main fuel 15 in the axial direction of the combustion chamber 12 becomes as shown by a dotted line in FIG.

As described above, in the gas turbine combustor 20 of the present embodiment, the reaction speed of the main fuel 15 is low when the load of the gas turbine is low and the pressure of the combustion gas is low. By supplying all of the main fuel 15 and performing flame holding by the recirculation flow 14, a safe combustion state is realized. That is, the same operation as that of the conventional combustor 1 is performed basically.

On the other hand, when the load of the gas turbine becomes high and the pressure of the combustion gas becomes high, the reaction speed of the main fuel 15 increases, and the main fuel 15 flows from the upstream side of the combustion chamber 12.
When 100% is supplied, the cross-sectional load factor on the upstream side of the combustion chamber 12 increases, resulting in an unstable combustion state.
This increase in the cross-sectional load factor causes a high-temperature gas region to be locally formed in the combustion chamber 12, so that the generation of NOx increases. For this reason, when the load is high, the main fuel 15 is divided and supplied also to the downstream side of the combustion chamber 12, so that the cross-sectional load factor on the upstream side of the combustion chamber 12 is reduced, and the cross-sectional load factor is reduced to the downstream side of the combustion chamber 12. By dispersing to the side, a stable combustion state is realized, and generation of NOx can be suppressed by eliminating a local high-temperature gas region in the combustion chamber 12.

Further, when the combustion gas becomes high temperature and high pressure conditions and the load of the gas turbine satisfies the self-ignition condition of the main fuel 15, the pilot fuel 13 supplied by the pilot nozzle 2 is extremely discharged. To the recirculation zone 14 by reducing
A stable combustion state can be realized without supplying the pilot fuel 13 to the
The generation of NOx can be suppressed by reducing the local high-temperature gas region generated due to the combustion of NO. In addition, the air flow path for supplying air required for combustion to the combustion chamber 12 is conventionally provided in two systems: the pilot air flow path 5 and a plurality of main air flow paths 11. The installation of the combustion air flow path 23 is sufficient, and the installation of the main swirler 9 provided for each main air flow path 11 becomes unnecessary.

Although the description is omitted in the present embodiment, the cooling air 17 for protecting the downstream inner cylinder 7 from high temperature and high pressure gas is supplied to the combustion chamber 12 in the same manner as shown in FIG. It is introduced and flows along the inner peripheral surface of the downstream inner cylinder 7 to cool the downstream inner cylinder 7.

[0028]

As described above, the gas turbine combustor according to the present invention is ignited by the flame holding of the pilot nozzle disposed at the axial center of the axially inner cylindrical inner cylinder. The main fuel for performing main combustion is divided and supplied in a direction of the flow of combustion air in a combustion chamber in which swirling combustion air is caused to flow by a swirler arranged around the pilot nozzle. I did it.

Thus, even if the reaction speed of the main fuel supplied into the combustion chamber is increased by the high-temperature and high-pressure combustion gas at a high load of the gas turbine in recent years, even if the main fuel supplied into the combustion chamber is not The fuel / fuel ratio can be made to have a distribution that fluctuates smoothly in the direction of the flow of combustion air flowing through the combustion chamber, and the cross-sectional load factor does not locally increase on the upstream side, resulting in a stable combustion state. In addition, the generation of NOx can be reduced.

Further, when the temperature of the combustion gas is high and high pressure, and the load of the gas turbine satisfies the self-ignition condition of the main fuel, the pilot fuel supplied by the pilot nozzle is extremely reduced. Alternatively, without supplying the pilot fuel to the recirculation region by stopping the supply, a stable combustion state can be realized, and at the same time, the local high-temperature gas region is reduced, and NO
The occurrence of x can be suppressed.

Further, in the gas turbine combustor according to the present invention, the main nozzle for supplying main fuel into the combustion chamber is provided at a supply position determined so as to be divided and supplied in the direction of the flow of the combustion air. The chamber is formed so as to penetrate the upstream inner cylinder and the downstream inner cylinder that form the chamber.

Thus, the distribution of the unburned fuel in the axial direction of the combustion chamber can be freely controlled by controlling the fuel injected from each main nozzle, so that the combustion state can be made more stable. , NOx can be more effectively reduced.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a first embodiment of a gas turbine combustor according to the present invention;

FIG. 2 is a diagram showing an unburned fuel ratio of main fuel in an axial direction of a combustion chamber shown in FIG. 1;

FIG. 3 is a partial longitudinal sectional view showing a conventional gas turbine combustor.

FIG. 4 is a diagram showing an unburned fuel ratio of main fuel in an axial direction of a combustion chamber shown in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas turbine combustor 2 Pilot nozzle 3 Pilot swirler 4 Pilot air 5 Pilot air flow path 6 Upstream inner cylinder 7 Downstream inner cylinder 8 Main nozzle 9 Main swirler 10 Main air 11 Main air flow path 12 Combustion chamber DESCRIPTION OF SYMBOLS 13 Pilot fuel 14 Flame holding recirculation area 15 Main fuel 16 Flame holding duct 17 Cooling air 20 Gas turbine combustor 21 Combustion air 22, 22a to 22f Main nozzle 23 Combustion air flow path

────────────────────────────────────────────────── ─── Continuing on the front page (51) Int.Cl. ⁶ Identification code FI F23R 3/34 F23R 3/34 (72) Inventor Masatoyo Ota 2-1-1, Araimachi Shinhama, Takasago-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Inside the Takasago Research Laboratory (72) Inventor Mitsuru Inada 2-1-1, Shinhama, Arai-machi, Takasago City, Hyogo Prefecture Inside the Takasago Machinery Works, Mitsubishi Heavy Industries, Ltd.

Claims (2)

[Claims] 1. A pilot nozzle which is disposed at an axial center of a cylindrical upstream inner cylinder formed to be axially symmetrical and performs flame holding, and is disposed around an outer periphery of the pilot nozzle,
A gas turbine combustor including a swirler configured to supply combustion air into a combustion chamber formed by a swirling flow and formed into a combustion chamber formed by the upstream inner cylinder and a downstream inner cylinder having a distal end connected to the upstream inner cylinder. 3. The gas turbine combustor according to claim 1, wherein the main fuel for performing the main combustion is divided and supplied in the direction of the flow of the combustion gas in the combustion chamber. 2. The upstream internal cylinder and the downstream internal cylinder at a supply position where a main nozzle that supplies the main fuel into the combustion chamber is supplied in a divided manner in a direction of the combustion gas flow. The gas turbine combustor according to claim 1, wherein the gas turbine combustor is provided so as to pass therethrough.