JP2965639B2 - Gas turbine combustor - Google Patents

Description

The present invention relates to a gas turbine combustor for premixing air and fuel for combustion, and more particularly to a gas turbine combustor for reducing NOx. About.

(Prior Art) In general, the main factor of NOx generation in a gas turbine combustor is that a combustion region where the equivalent ratio of fuel and air is close to 1 occurs in the combustion gas, and the combustion gas is locally generated in this combustion region. Is to raise the temperature. Caused by such factors
As a means for suppressing NOx, there is a lean premix combustion system.

As a conventional combustor to which the above-mentioned lean premixed combustion system is applied, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 61-110817. As shown in FIG. 8, the combustor includes a liner 102 provided with a swirler 101 at the head, a premixing chamber 103 formed in a double cylindrical shape on the outer periphery of the liner 102, and a liner 102. It is composed of a plurality of ventilation guides 104 communicating between the premixing chamber 103 perforated in the body and the inside of the liner 102.

The first-stage fuel 106 is supplied to the internal combustion chamber 105 of the liner 102, and stable diffusion combustion is performed while diffusing and mixing with the air 107 supplied through the swirler 101.

On the other hand, from the inlet opening of the premixing chamber 103, the second stage fuel 108
And the air 107 are taken in and premixed lean, and the premixed gas 109 is supplied to the combustion chamber 105 through the ventilation guide 104 to perform lean premixed combustion. The premixed gas 109 spouted from the ventilation guide 104
The air flows into the swirl flow 110 formed by the air passing therethrough, and forms a central backflow flame holding region 111. A part of the premixed gas 109 keeps flame in the central backflow flame holding region 111, thereby promoting stable combustion of the premixed gas. Outside the swirl flow 110, an outer peripheral backflow flame holding region 112 is formed as shown in FIG. By such a method, a part of the fuel is subjected to lean premix combustion to reduce NOx.

(Problems to be solved by the invention) However, in general, the swirling flow 110 constantly fluctuates,
The fluctuation of the swirling flow 110 causes a fluctuation between the center backflow flame holding area 111 and the outer circumference backflow flame holding area 112. In detail, swirl flow 1
When 10 changes, for example, from FIG. 9 (a) to FIG. 9 (b), the central backflow flame holding region 111 becomes smaller and the outer peripheral backflow flame holding region 112 becomes larger. This central part backflow flame holding area 1
As for 11, the larger the temperature becomes, the higher the degree of combustion of the premixed gas 109 becomes, the higher the gas temperature in the central backflow flame holding zone becomes, and the larger it becomes. Conversely, as the central backflow flame holding area 111 becomes narrower, the gas temperature in the central backflow flame holding area decreases and becomes smaller.

As described above, in the conventional combustor, the fluctuation in the central backflow flame holding region affects the positive feedback and the flame holding state is greatly changed, so that there is a problem that the generation of NOx cannot be sufficiently suppressed. Further, positive feedback fluctuations in the central backflow flame holding region increase combustion oscillations, and the increase in combustion oscillations increases fluctuation stress acting on components of the gas turbine combustor and the amount of wear of each component. There was a problem that the life of the vessel was shortened.

Therefore, an object of the present invention is to provide a gas turbine combustor that can stabilize a swirling flow with an extremely simple configuration and sufficiently suppress the generation of NOx and combustion oscillation.

[Object of the invention]

(Means for Solving the Problems) In order to achieve this object, the present invention provides a swirler which is attached to a head of a liner in an annular shape and supplies air as a circular swirling flow to a combustion chamber in the liner; A first-stage fuel nozzle attached to the head of the liner so as to be surrounded by the first-stage fuel nozzle, which discharges the first-stage fuel into the combustion chamber, diffuses and mixes with the annular swirling flow, and performs diffusion combustion; Premixing gas to produce a premixed gas, and a premixed gas ejection means for ejecting the premixed gas from the plurality of ejection holes formed in the liner body to the combustion chamber as a plurality of premixed gas flows. A gas turbine combustor in which a part of the premixed gas flow flows into a region surrounded by the annular swirling flow to form a central backflow flame holding region; Towards An annular swirling flow guide having a generally frustoconical shape extending to gradually increase in diameter, the annular swirling flow guide guiding the annular swirling flow so that it flows out along the annular swirling flow guide; The length of the annular swirling flow guide is determined so that the central backflow extension region is located in a region surrounded by the annular swirling flow guide.

In this configuration, it is preferable that the swirler is a radial swirler that allows the air to flow out toward the side surface of the first stage combustion nozzle.

Further, it is preferable that a diameter of a connecting portion between the tip of the annular swirling flow guide and the liner body is sharply increased, and that the annular swirling flow forms an outer periphery backflow flame holding region at the connecting portion.

It is desirable that an additional nozzle is arranged adjacent to the upstream side of the swirler, and the first-stage fuel is discharged from the additional nozzle to the swirler.

Further, a common first-stage fuel supply passage may be used to supply the first-stage fuel to the first-stage combustion nozzle and the additional nozzle, or separate first-stage independent fuel stages may be used. A fuel supply path can also be used.

(Operation) The air that has flowed into the swirler mixes with the first-stage fuel from the first-stage fuel nozzle, forms an annular swirl, is guided by the annular swirl guide, and flows along the annular swirl guide.

A part of the premixed gas flow jetted from the premixed gas jetting means into the combustion chamber flows into a region surrounded by the annular swirling flow and forms a central backflow flame holding region.

Since the annular swirling flow is guided by the annular swirling flow guide, its spreading angle is always kept substantially constant, and the length of the annular swirling flow guide is a region where the central backflow flame holding region is surrounded by the annular swirling flow guide. It is determined to be located within. In addition, the boundary region where the annular swirling flow guide and the liner body are connected is an enlarged diameter portion whose diameter increases,
Combustion is stable in the peripheral backflow flame holding region formed in this region. The center backflow flame holding region is always maintained at a substantially constant size, and the flame holding of the premixed gas is stably maintained.

Even if the pressure in the central backflow flame holding region rises due to fluctuations in the flow of the premixed gas, and the external force that expands the annular swirl flow acts, the displacement of the annular swirl flow is limited by the annular swirl guide. Therefore, the size of the central backflow flame holding area hardly changes. Conversely, even if the pressure in the central backflow flame holding area decreases and a force acts to draw the annular swirl flow inward, the annular swirl flow adheres to the annular swirl flow guide and is therefore easily swirled. The size of the central backflow flame holding area is kept substantially constant without being separated from the flow guide.

Embodiment An embodiment of a gas turbine combustor according to the present invention will be described below with reference to FIGS.

A plurality of gas turbine combustors shown in FIGS. 1 to 3 are installed between a compressor (not shown) and a gas turbine, and housed in a combustor wrapper 1 surrounding a compressor discharge chamber. I have.

A combustor outer cylinder 2 is joined to the combustor wrapper 1, and an upstream end of the combustor outer cylinder 2 is closed by a head plate 3. A liner 5 that forms an outer wall of the combustion chamber 4 is installed inside the combustor wrapper 1 and the combustor outer cylinder 2,
A liner cap 6 having a cooling air hole 6a is attached to a front end, that is, an upstream end of the liner 5, and a transition piece 7 is attached to a rear end of the liner 5. A flow sleeve 8 supported by the combustor outer cylinder 2 is interposed in a gap between the combustor outer cylinder 2 and the liner 5, and the flow sleeve 8 transfers compressed air 9 from the compressor to a front end of the liner 5. That is, to the liner head. A liner support 10 is fixed to the flow sleeve 8, and the liner support 10 is
I support.

A first-stage burner 11 is installed at the center of the head plate 3, and a first-stage fuel system 12 is installed at the center of the first-stage burner 11.
A first-stage fuel inlet 13 and a first-stage fuel nozzle 14 are provided, and a radial swirler 15 is provided around the first-stage fuel nozzle 14 so as to surround the nozzle 14. The radial swirler 15 swirls the compressed air 9 flowing between the liner 5 and the flow sleeve 8 and discharges the compressed air 9 toward the side surface of the first-stage fuel nozzle 14. Radial swara
An annular swirling flow guide 16 having a truncated conical shape whose diameter gradually increases toward the downstream side is connected to the passage wall of the passage 15. , And the front end is fitted into the opening of the liner cap 6.

On one side of the head plate 3, a second stage fuel inlet 18 communicating with a second stage fuel system 17 is mounted, and on the other side, eight second stage fuel nozzles 19 are provided. They are mounted at approximately equal angular intervals around 14. An annular second-stage fuel header 20 is formed in the head plate 3, and the second-stage fuel header 20 communicates the second-stage fuel inlet 18 with the second-stage fuel nozzle 19.

Eight premixing ducts 21 are provided between the liner 5 and the flow sleeve 8, and each premixing duct 21 has an inlet facing the second-stage fuel nozzle 19 and three branch outlets 21a. The three branch outlets 21a of the premix duct 21 are connected to the liner 5
Is inserted into the sleeve 22 fitted in the hole. The upstream side of the premixing duct 21 is supported by the liner 5 by a support 23, and the downstream side of the premixing duct 21 is a support plate 24 and a support ring 25.
And is supported by the liner 5. The support plate 24 is fixed to the branch outlet, and the support ring 25 is wound around the liner 5 via the support plate 24.

The runner cap 6 is provided with an inner heat shield plate 26, and the liner 5 is provided with a plurality of diluted air holes 27 on the downstream side.

 Next, the operation of this embodiment will be described.

Compressed air 9 from the compressor passes through a gap between the liner 5 and the flow sleeve 8 and passes through the radial swirler 15 and the premixing duct 21.
And into the entrance. In addition, a part of the compressed air 9 passes through the diluted air hole 27 of the liner 5, the cooling air hole 6a of the liner cap 6 shown in FIG. Through the liner.

The air passing through the radial swirler 15 is swirled there, collides with the side surface of the first-stage fuel nozzle 14, mixes with a part of the first-stage fuel from the first-stage fuel nozzle hole 14a, and forms an annular swirling flow. It is guided by the annular swirling flow guide 16 as 28, flows along the inner surface of the guide 16, and flows into the combustion chamber 4. The annular swirling flow 28 flows out at a constant opening angle along the annular swirling flow guide 16 to form a central backflow flame holding region 29 therein. A part 29a of the central backflow flame holding region 29 is located in a region surrounded by the annular swirling flow guide 16. The annular swirling flow 28 forms an outer peripheral backflow flame holding region 30 behind the liner cap 6, that is, at the enlarged diameter portion at the boundary between the tip of the annular swirling flow guide 16 and the upstream end of the liner 5.

The second-stage fuel that has flowed into the premixing duct 21 from the second-stage fuel nozzle 19 is mixed with the compressed air 9 in the premixing duct 21 and enters the combustion chamber 4 from the premixing duct outlet 21a as a premixing gas 31. Inflow. A part of the inflowing premixed gas 31 flows into the central backflow flame holding region 29.

Most of the first-stage fuel from the first-stage fuel nozzle hole 14a is diffused and combusted, and the diffused-combusted first-stage fuel is mixed with the premixed gas 31 burned in the central backflow flame holding zone 29 and the remaining fuel ( Flame is maintained as a strong pilot flame for the premixed gas mainly).

Since the annular swirling flow 28 always flows along the inner surface of the annular swirling flow guide 16 even if the compressed air 9 flowing into the radial swirler 15 fluctuates, the size of the central backflow flame holding region 28 is maintained constant. be able to. Also, even if the flow of the premixed gas 31 fluctuates and the pressure in the central backflow flame holding region 29 rises, even if an external force is applied to the annular swirl flow 28 to spread it outward, the annular swirl flow 28 Since the displacement is limited by the annular swirling flow guide 16, the size of the central backflow flame holding region 29 hardly changes. Conversely, even if the pressure in the central backflow flame holding region 29 decreases and a force is applied to draw inward the annular swirl 28, the annular swirl 28 adheres to the annular swirl guide 16 and flows. The size of the central backflow flame holding region 29 is maintained substantially constant without easily separating from the annular swirling flow guide 16.

Since the first-stage fuel mixed in the outer peripheral portion of the annular swirl flow 28 is stably burned in the outer peripheral backflow flame holding region 30,
Combustion efficiency can be increased.

FIGS. 4 and 5 show a second embodiment of the present invention. The second embodiment is a first stage fuel nozzle according to the first embodiment.
It significantly reduces the amount of NOx generated by the combustion of the first stage fuel from Step 14. An additional nozzle 32 for the first stage fuel is arranged adjacent to the radial swirler 15 on the upstream side thereof. The first-stage burner 11 has a first-stage fuel inlet 13 and a first-stage fuel inlet 13.
A common first-stage fuel supply passage 33 communicating with the stage fuel nozzle 14 and the additional nozzle 32 is provided.

Part of the first-stage fuel from the first-stage fuel inlet 13 flows out of the first-stage fuel nozzle 14 and diffuses into the air from the radial swirler 15 and burns, and the rest of the first-stage fuel flows through the first-stage fuel supply passage 33. The radial swirler 1 is diverted from the plurality of holes 32a of the additional nozzle 32.
5 flows out, and is premixed with the compressed air 9 passing through the radial swirler 15 to form an annular swirling flow 28.

By providing the additional nozzle 32 in this manner, the amount of the first-stage fuel flowing out of the first-stage fuel nozzle 14 can be reduced as compared with the first embodiment. As a result, the NOx generated by the combustion of the first-stage fuel from the first-stage fuel nozzle 14
Can be greatly reduced.

FIG. 6 shows a modification of the second embodiment, in which a first-stage fuel intake 34 for an additional nozzle independent of the first-stage fuel intake 13 is attached to the first-stage burner 11. Have been. The first-stage burner 11 has a first-stage fuel inlet for an additional nozzle.
A first-stage fuel header 35 that communicates with the additional nozzle 32 is provided.

As described above, the first-stage fuel is supplied to the first-stage fuel nozzle 14 and the additional nozzle 32 from the separate first-stage fuel intake 13 and the additional-stage first-stage fuel intake 34, respectively. First
The first stage fuel supply amount to the stage fuel nozzle 14 and the first stage fuel supply amount to the additional nozzle 32 can be controlled independently.
Therefore, the first-stage fuel supply amount to the first-stage fuel nozzle 14 and the first-stage fuel supply amount to the additional nozzle 32 depend on the load change of the gas turbine.
By properly controlling the stage fuel supply amount and the second stage fuel supply amount to the premixing duct 21, NOx can be sufficiently reduced over the entire load region of the gas turbine.

FIG. 7 shows the relationship between the load of the gas turbine and the first-stage fuel flow rate a to the first-stage fuel nozzle 14, the first-stage fuel flow rate b to the additional nozzle 32, and the second-stage fuel flow rate c to the premixing duct 21. In the case where the second stage fuel is supplied from the intermediate load, the ratio of the additional nozzle first stage fuel flow rate b to the first nozzle fuel nozzle first stage fuel flow rate a, especially in the vicinity of the switching point, is shown in FIG. By making it lower than under load,
It is possible to stabilize the combustion at the time of charging the stage fuel. Also,
The ratio of the additional nozzle first-stage fuel flow rate b is increased and the ratio of the first-stage fuel nozzle first-stage fuel flow rate a is reduced in a higher load region before the second-stage fuel injection and after the second-stage fuel injection. Thus, the amount of NOx at each load can be minimized.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible. For example, the shape, the position of the swirler 15 with respect to the first-stage fuel nozzle 14, the method of ejecting air, and the like can be appropriately changed.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, a substantially frusto-conical shape extending so as to gradually increase in diameter from near the tip of the first stage combustion nozzle toward the premixed gas ejection hole of the liner is provided. An annular swirling flow guide, which guides the annular swirling flow so as to flow out along the annular swirling flow guide, and adjusts the length of the annular swirling flow guide to a central part backflow flame holding. The region is defined so as to be located within a region surrounded by the annular swirling flow guide, and an outer peripheral backflow flame holding region is formed at an enlarged diameter portion at a boundary between a tip of the annular swirling flow guide and an upstream end of the liner. Therefore, the flow position of the annular swirl flow is always substantially constant, and the center backflow flame holding region can be maintained constant. Therefore,
It is possible to sufficiently suppress the generation of NOx, suppress the combustion oscillation, and extend the life of the gas turbine combustor.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a gas turbine combustor according to the present invention, FIG. 2 is an enlarged longitudinal sectional view showing a main part of FIG. 1, and FIG. FIG. 4 is a longitudinal sectional view showing a main part of a second embodiment of the gas turbine combustor according to the present invention, and FIG. 5 is a sectional view taken along line VV of FIG.
FIG. 6 is a longitudinal sectional view showing a modification of the second embodiment, FIG. 7 is a graph showing the relationship between the load of the gas turbine and the fuel flow rate, and FIG. 9 (a) and 9 (b) are longitudinal sectional views showing the gas turbine combustor of FIG.
It is explanatory drawing which showed the swirling flow and the flow of the premixed gas in the gas turbine combustor of the figure. 4 ... combustion chamber, 5 ... liner, 9 ... compressed air, 12 ...
1st stage fuel system, 14 ... 1st stage fuel nozzle, 15 ... swirler, 16 ... annular swirl flow guide, 17 ... 2nd stage fuel system, 21
…… Premixing duct, 28… Circular swirling flow, 29 …… Central backflow flame holding zone, 31 …… Premixed gas

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Claims (1)

(57) [Claims] A swirler attached to the head of the liner for supplying air as an annular swirling flow to a combustion chamber in the liner; a first stage mounted on the head of the liner so as to be surrounded by the swirler; A first-stage fuel nozzle for discharging fuel into the combustion chamber and diffusively mixing and diffusing and burning the annular swirl flow, and a second-stage fuel and air are premixed to form a premixed gas. A premixed gas jetting means for jetting a plurality of premixed gas streams from the plurality of jet holes formed in the liner body into the combustion chamber, and a part of the premixed gas stream is converted into the annular swirling flow. In a gas turbine combustor which flows into an enclosed region to form a central backflow flame holding region, the gas turbine combustor extends from the vicinity of the first stage fuel nozzle tip so as to gradually increase in diameter toward the ejection hole. Almost frustoconical shape An annular swirl guide, wherein the annular swirl guide guides the annular swirl as it flows out along the annular swirl guide, and the length of the annular swirl guide is the central backflow. A flame region is defined so as to be located in a region surrounded by the annular swirling flow guide, and an outer peripheral backflow flame holding region is formed at an enlarged diameter portion at a boundary between a tip of the annular swirling flow guide and an upstream end of the liner. A gas turbine combustor characterized in that: