JPH08261467A - Gas turbine combustor - Google Patents

Abstract

PURPOSE: To provide a gas turbine combustor which makes it possible, while a lean premix is burned to reduce NOx, to reduce the amount of CO or THC produced at the time of a partial load. CONSTITUTION: A gas turbine combustor 11 has burners 5 each of which has a diffuse combustion type pilot nozzle 6 and premix combustion type main nozzles 7 at positions encircling the pilot nozzle 6. These burners 5 are placed at the head of the combustor and in a circular arrangement and pointed toward the combustion region inside the inner tube 3 of the combustor. In operating the gas turbine combustor 11 the main nozzles 7 are put in action one by one with increase of the gas turbine load. Each of the burners 5 of this gas turbine combustor 11 has a ceramic guide 13 which encloses the outlets for the premixed gas in a manner of walling them in downstream. This guide 13 is formed of a ceramic material having good resistances to heat and oxidation and projects from the forward end of the burner 5 when set.

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 in particular, a burner burning at the time of partial load of a gas turbine is not affected by an unburned burner, and CO and THC are reduced. Gas turbine combustor.

[0002]

2. Description of the Related Art A gas turbine combustor has a sleeve-shaped outer wall 1, a flow sleeve 2 provided inside the outer wall 1, and a flow sleeve 2 provided inside the flow sleeve 2, as shown in a vertical sectional side view in FIG. And an inner cylinder 3 that is formed. A head plate 4 is provided at the head end of the gas turbine combustor, and a plurality of burners 5 are annularly arranged on the head plate 4.

In a conventional burner 5, a diffusion combustion type pilot nozzle 6 and a premixed combustion type main nozzle 7 are arranged around the pilot nozzle 6, and the main nozzle 7 is equipped with a premixing duct 8
Facing the duct entrance side. Each burner 5 is annularly arranged toward the combustion region in the inner cylinder 3.

In the gas turbine combustor, each burner 5 is sequentially operated as the load of the gas turbine increases, but at the time of starting, only the pair of burners 5 and 5 diagonally located are driven by diffusion combustion by the pilot nozzle 6. Ignition and flame holding are performed, and premix combustion is performed by the main nozzle 7 of the burner 5 and the premix duct 8 as the load on the gas turbine increases. As a result, the ignition and flame holding property is improved, and stable combustion and NOx generation amount are reduced. At rated load, all of the burners 5 burn,
The gas turbine combustor is operated, thus achieving stable combustion and low NOx in the entire operating region of the gas turbine.

The premixing duct 8 of the burner 5 is provided with a main swirler 9 for causing a swirling flow, which promotes premixing of air and fuel, and the pilot nozzle 6 also has a swirler. 10 is provided, the swirler 10 expands the fuel injected from the pilot nozzle 6, and stable combustion is possible even when the amount of fuel for diffusion combustion is small, and lean premixed combustion is performed. By doing so, NOx is reduced.

[0006]

However, even in the conventional gas turbine combustor in which the premixed combustion type burner 5 is annularly arranged, further reduction of NOx is required, and therefore NOx is reduced.
Although the diffusion combustion that generates a large amount is reduced to perform lean combustion of the premixed gas, this causes the flame temperature to locally decrease, resulting in monoxide (CO) and unburned hydrocarbon (THC).
Causes a problem that occurs.

On the other hand, the burner 5 of the gas turbine combustor is
Since the gas turbines are operated sequentially as the load increases, burners that are burnt and burners that are not burnt coexist during partial load, and air flows to the unburned burners for reasons such as cooling. There is. Therefore, the flame of the combustion burner is locally cooled under the influence of the air from the unburned burner, and a low temperature part is generated, resulting in CO and T
This causes a problem that HC easily occurs.

The present invention has been made in consideration of the above-mentioned circumstances, and is a gas turbine combustor capable of reducing NOx by lean premixed combustion and at the same time reducing the amount of CO and THC generated at partial load. The purpose is to provide.

[0009]

In order to achieve the above object, according to the present invention, a diffusion combustion type pilot nozzle located at the center of a burner and a plurality of premixed combustion type main nozzles located on the outer periphery of the pilot nozzle are provided. In a gas turbine combustor in which a burner having and is arranged annularly in the combustor head toward the combustion region in the inner cylinder of the combustor, and the main nozzles are sequentially operated as the load of the gas turbine increases. A ceramic guide is provided so as to project from the tip of the burner so as to cover the outer peripheral portion on the downstream side of the premixed gas outlet of the burner.

According to a second aspect of the present invention, the burner of the combustor is arranged differently from the combustor of the first aspect. A gas turbine combustor having a diffusion combustion type pilot nozzle and a premixed combustion type main nozzle annularly arranged so as to surround the pilot nozzle, the premixed gas of the premixed combustion type main nozzle A ceramic guide is provided so as to project from the premixed gas outlet side of the main nozzle so as to cover the outer peripheral portion on the downstream side of the outlet.

According to a third aspect of the present invention, the guide is made of a ceramic matrix composite material having high temperature heat resistance and oxidation resistance, and a fourth aspect of the present invention is to fix the guide to the tip of the burner with a fixing member via a cushioning material. There is something I did.

[0012]

By having the ceramic guide projecting at the tip of the burner by premixed combustion, the flame of the burner burning especially at partial load may be affected by the air flowing to the adjacent unburned burner. In other words, the flame is protected and held by combustion, the flame temperature is prevented from lowering, and the amounts of CO and THC generated are suppressed.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings, in which the same members as those in FIG. 9 are designated by the same reference numerals.

FIG. 1 shows a longitudinal side surface of an embodiment of a gas turbine combustor according to the present invention, and FIG. 2 shows a cross section corresponding to AA of FIG. The gas turbine combustor 11 is
It is installed between the compressor of the gas turbine plant and the gas turbine. The gas turbine combustor 10 has a multi-cylinder structure including a sleeve-shaped outer wall 1, a flow sleeve 2 provided inside the outer wall 1, and an inner cylinder 3 further provided inside thereof. A head plate 4 is provided in the head portion, which is the upstream portion of the gas turbine combustor 10,
With this head plate 4, the outer wall 1 and the flow sleeve 2
Is closed at one end.

A plurality (six in the illustrated example) of burners 5 are inserted into and fixed to the head plate 4 in an annular arrangement. The burner 5 is provided with a diffusion combustion type pilot nozzle 6 which is inserted and arranged at the center of a burner body 12 which also serves as a main fuel header, and a premixed combustion type main nozzle 7 which is arranged around this nozzle. Each burner 5 is a combustion chamber A formed in the inner cylinder 3 from the head plate 4 side.
Are oriented so that they respectively face the combustion areas of.

The main nozzle 7 of the burner 5 has a nozzle opening facing the duct inlet 7a side of a premixing duct 8 as a premixing tube. The premixing duct 8 covers the periphery of the pilot nozzle 6 on the nozzle side, and a main swirler 9 is provided on the duct inlet side of the premixing duct 8. The main swirler 9 causes a swirling flow to stir the main fuel and air, thereby uniformly mixing the main fuel and air. To premix. The premixed fuel is injected from the duct outlet 8b of the premixing duct 8 into the combustion region in the inner cylinder 3.

On the other hand, as shown in FIG. 3, the pilot nozzle 6 has its nozzle port 6a directed toward the swirler 10, and the pilot fuel injected from this nozzle port 6a is agitated by the swirl flow by the swirler 10 to produce an inner cylinder. The head of No. 3 is designed to be burnt by diffusion. The swirler 10 is held on the inner peripheral surface of the premixing duct 8, and the swirler 10 holds the free end side of the pilot nozzle 6.

At the tip of the burner 5 of the gas turbine combustor 10, a ceramic cylindrical guide 13 is provided in the inner cylinder 3 so as to cover the outer peripheral portion of the premixing duct 8 following the premixing combustion type main nozzle 7. It is attached so as to project. As a constituent material of the guide 13, a ceramic material excellent in high temperature heat resistance and oxidation resistance is used, and preferably a ceramic matrix composite material is used. This ceramic guide 1
No. 3 does not need to be provided with a special cooling means, and therefore has the advantage of not having a substantial effect on the decrease in flame temperature.

FIG. 3 shows the burner 5 of the gas turbine combustor 10.
1 is an enlarged cross-sectional view showing one of the above, a main swirler 9 having a swirling function is provided on the duct inlet side in the premixing duct 8 of the burner 5, and the main nozzle 7 faces the swirler upstream side. Therefore, the main fuel F injected from the nozzle port of the main nozzle 7 flows toward the main swirler 9, and is agitated by the main swirler 9 together with the main air O flowing from the duct inlet 8a of the burner 5 and well premixed. At the same time, a premixed swirling flow is injected from the duct outlet 8b toward the combustion region of the inner cylinder 3, improving the flame holding property and performing stable combustion even if the diffusion fuel f is small. It is possible. As a result, lean premixed combustion can be performed and the amount of NOx generated can be reduced.

FIG. 4 is an enlarged sectional view showing the details of the portion B in FIG. 3, in which the base end of the ceramic guide 13 is formed with an inwardly facing flange portion 13a, and the metal burner 5 is pre-formed. The tip of the mixing duct 8 is formed with a flange portion 8c projecting outward, and a nut 14 is screwed onto the outer periphery of the premixing duct 8 to form the flange portion 13a.
The heat insulating material 15 which also serves as a cushioning material is fitted to the outer circumference of the premixing duct 8 between the nut 14 and the nut 14, and the flange portion 13a of the guide 13 is fitted to the intermediate position of the outer circumference of the heat insulating material 15 to fit the nut 14 It is fixed by tightening. The fixing member is not limited to the nut 14 and may be other fixing means such as a clamp, and may be any member as long as it can fix the guide 13 to the burner 5 side with the cushioning material 15 interposed.

As a result, the thermal expansion difference between the burner 5 and the guide 13 is absorbed by the heat insulating material 15. The thermal expansion can be absorbed by the heat insulating material 15, and expanded graphite packing or the like may be provided on the contact surface between the guide 13 and the metal part. In order to optimize the thermal expansion difference and the fitting force. A spring may be used.

Since the ceramic guide 13 is easily cracked by thermal stress and may be broken and scattered, the seal plate 16 is attached to the inner cylinder 3 by the latch pin 17, and the inner circumference of the seal plate 17 is covered with a nut. 14
(Or other portion) as close as possible to minimize the flow rate of the air flowing into the inner cylinder 3 and to minimize the cooling of the outer circumference of the ceramic guide 13 by the inflow air. To reduce the temperature deviation of the inner and outer surfaces of 13,
The thermal stress generated in the ceramic guide 13 is reduced.

FIG. 5 shows an example of the fuel schedule of the gas turbine combustor 11 according to the present invention, and the combustion itself is performed in the same manner as the conventional one. That is, when the gas turbine is started, only a pair of diagonal burners 5 are ignited by diffusion combustion by the pilot nozzle 6. As the load on the gas turbine increases, the burner 5 operates, and the main nozzle 7 and the premixing duct 8 inject the premixed gas into the premixed combustion. Further, the other burners 5 are ignited one after another according to the load on the gas turbine, and combustion proceeds.

FIG. 6 is a schematic diagram showing the state of combustion at a partial load, and there are burners 5a (indicated by diagonal lines) that are burning and burners 5b that are not burning at this partial load. Air is still flowing in the burner 5b which is not burning for the purpose of cooling or the like. The air flowing from the unburned burner 5b tends to locally lower the flame temperature of the combustion burner 5a, but a ceramic guide 13 is attached to the tip of the burning burner 5a so as to project forward. Therefore, the air does not affect the flame of the combustion burner 5a, the flame is protected and flame-preserved, and the premixed combustion is performed without lowering the flame temperature. As a result, the amount of CO and THC generated is increased. Reduce. in this case,
Since the ceramic guide 13 has no special cooling means, it does not cause a decrease in flame temperature.

FIG. 7 is a graph comparing the effect of the present invention with a conventional gas turbine combustor and is a graph of gas turbine load and CO generation amount. This graph shows that the gas turbine combustor 10 of the present invention has a significantly lower CO generation amount than the conventional gas turbine combustor.

FIG. 8 shows a vertical sectional side view of another embodiment of the present invention. The burner 5A of the gas turbine combustor 11A is shown in FIG.
Is provided with a pilot nozzle 6A for performing diffused combustion toward a combustion region in the inner cylinder 3 at a central position of the head plate 4, and a plurality of main nozzles 7A for performing premixed combustion are provided so as to surround the pilot nozzle 6A. The main nozzles 7A are arranged so as to extend into the premixing duct 8A and inject main fuel into the premixing duct 8A.

The premixing duct 8A is the gas turbine combustor 1
It is supported by a head plate 3a which is an end plate of the inner cylinder 3 of 1A. A main swirler 9 is provided on the duct inlet side of the premixing duct 7A. The main swirler 9 agitates the air flowing in from the duct inlet side to generate a swirl flow, and this swirl flow causes the fuel distribution header 20 in the head plate 4 to flow.
The main fuel injected from the main nozzle 7A via the premixing duct is premixed in the premixing duct 8A, and the premixed fuel is injected from the duct outlet of the premixing duct 7A into the ceramic sleeve-shaped guide 13. Has become.

Further, a diffusion combustion duct 21 as a guide cylinder is provided in the center of the head plate 3a of the inner cylinder 3, and a pilot nozzle 6A is inserted in the duct 21 so that a combustion area in the inner cylinder 3 is provided. The free end of the pilot nozzle 6A is held by the swirler 10 in the diffusion combustion duct 21 while the nozzle opening faces.

The pilot fuel guided through the pilot nozzle 6A is swirler 10 in the combustion chamber A in the inner cylinder 3.
It is agitated by the swirling flow from and diffused and burned. A premixed combustion zone is formed on the downstream side around the diffusion combustion zone, and premixed combustion is performed.

Also in this embodiment, the premixing duct 8A
A ceramic guide 1 is attached to the tip of the same as in the previous embodiment.
3 is attached so as to project into the inner cylinder 3. The operation is also similar to that of the above embodiment.

In addition, according to the present invention, the arrangement of burners, the number of burners,
Needless to say, the present invention can be applied regardless of distribution of fuel flow rate, fuel injection method, fuel injection position, and the like.

[0032]

As described above, according to the present invention, the flame of the burner burning at the time of partial load of the gas turbine is affected by the air flowing out from the unburned burner due to the presence of the ceramic guide. There is no flame protection and flame protection of the burning burner.
It is possible to prevent the temperature of the flame from decreasing locally and prevent CO and T
The amount of generated HC can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of a gas turbine combustor according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a vertical sectional side view showing one of the burners shown in FIG.

FIG. 4 is an enlarged cross-sectional view showing details of portion B in FIG.

FIG. 5 is a diagram showing a relationship between a gas turbine load and a fuel flow rate under operating conditions of a gas turbine combustor.

FIG. 6 is a schematic diagram showing a state of combustion when a partial load is applied to the gas turbine combustor according to the present invention.

FIG. 7 is a graph showing a relationship between a gas turbine load and a CO generation amount of a gas turbine combustor according to the present invention and a conventional gas turbine combustor.

FIG. 8 is a view corresponding to FIG. 1 showing another embodiment of the present invention.

FIG. 9 is a vertical cross-sectional side view showing a conventional gas turbine combustor.

[Explanation of symbols]

 1 Outer Wall 2 Flow Sleeve 3 Inner Cylinder 5,5A Burner 6,6A Pilot Nozzle 7,7A Main Nozzle 8,8A Premixing Duct (Premixing Pipe) 9 Main Swirler 10 Swirler 11,11A Gas Turbine Combustor 13 Ceramic Guide 14 Nut 15 Heat insulating material 16 Seal plate 17 Stop pin

Claims (4)

[Claims] 1. A burner having a diffusion combustion type pilot nozzle and a plurality of premixed combustion type main nozzles located on the outer periphery of the pilot nozzle is annularly arranged at the head of the combustor, and each burner burns. In the gas turbine combustor, which is directed toward the combustion region in the inner cylinder of the burner and sequentially operates the main nozzles as the load of the gas turbine increases, a downstream outer peripheral portion of the premixed gas outlet of the burner is provided. A gas turbine combustor characterized in that a ceramic guide is provided so as to cover the burner tip so as to cover the burner. 2. A diffusion combustion type pilot nozzle installed at a central position of a combustor head toward a combustion region in an inner cylinder of the combustor, and a preliminarily arranged annularly surrounding the pilot nozzle. In a gas turbine combustor having a mixed combustion type main nozzle, a ceramic guide is provided so as to cover a downstream side outer peripheral portion of a premixed gas outlet of the premixed combustion type main nozzle. A gas turbine combustor, which is provided so as to project from the gas turbine combustor. 3. The gas turbine combustor according to claim 1, wherein the ceramic guide is made of a ceramic matrix composite material having high temperature heat resistance and oxidation resistance. 4. The gas turbine combustor according to claim 1, wherein the ceramic guide is fixed to the tip of the burner by a fixing member via a cushioning material.