JP2556798B2 - Gas turbine combustor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustor for a gas turbine, which is designed to reduce the amount of nitrogen oxide (NOx) produced during combustion, that is, to reduce NOx. .

[0002]

2. Description of the Related Art As a means for realizing low NOx combustion in a gas turbine combustor, as disclosed in, for example, Japanese Patent Publication No. 1-30055, a plurality of combustion chambers are provided. There is known a multi-burner combustor in which main burners of the premixed combustion type are arranged and the number of combustion operations of these main burners is controlled according to the load. According to this multi-burner combustor,
It is one of the means of reducing NOx that was carried out before that,
Disadvantages of the method of lowering the combustion flame temperature by injecting water or steam into the combustion chamber, namely, lowering the engine thermal efficiency (in the case of water injection), shortening the life of the engine due to corrosion of the turbine etc. due to bad water quality, An excellent effect that it is possible to overcome the drawbacks such as a rise in equipment and maintenance costs required for pretreatment for improving water quality, and to achieve a significant reduction in NOx while suppressing deterioration in performance. have.

On the other hand, in the above-mentioned multi-burner combustor, the flames at the time of ignition / starting are unstable due to premixed combustion, and when the load changes frequently, a plurality of burners are turned on / off. There are problems that the number of times increases and combustion tends to be unstable, and that flashback to the premixing section is likely to occur.

As disclosed in Japanese Patent Application No. 2-149688, the applicant of the present application has proposed a combustor for a gas turbine capable of solving the problems of the multi-burner combustor as described above. A diffusion combustion type pilot burner that directly injects fuel into the combustion chamber is installed in this section, and multiple premixed combustion type main burners are arranged around this pilot burner. It is proposed that the operation is controlled according to the above. According to the previously proposed gas turbine combustor (hereinafter referred to as "prior art"), the pilot burner provided in the central portion of the combustion chamber is a diffusion combustion type and always has a good flame holding effect. Therefore, it is possible to maintain stable combustion not only at the time of ignition / start-up, but also when there is a sudden load change, and the fuel injection nozzles of each main burner are distributed so that the fuel and air are mixed. Even if the distance and space are not increased, it is possible to substantially prevent the occurrence of flashback.

By the way, in the above-mentioned prior art, the main burner is constructed by inserting a fuel pipe having a dispersion type nozzle into an air inflow pipe having a swirl swirler at the end portion on the combustion chamber side. The boss inside the swirl swirler in the main burner is easily overheated during combustion operation,
The overheated boss portion is contacted with the air-fuel mixture that is premixed in the air inflow pipe and is ejected into the combustion chamber through the swirling swirler, which causes a problem that flashback is likely to occur.

The present invention has been made in view of the above circumstances, and not only can achieve the effects of the above-mentioned prior art, but can also prevent the occurrence of flashback during premixed combustion only by making a simple structural improvement. It is an object of the present invention to provide a combustor of a gas turbine that can be manufactured.

[0007]

In order to achieve the above object, a combustor for a gas turbine according to claim 1 of the present invention is a diffusion combustion type in which fuel is directly injected into the center of the combustion chamber into the combustion chamber. A pilot burner is installed, and a plurality of premixed combustion type main burners are arranged around this pilot burner.The main burners are equipped with a swirl swirler at the end on the combustion chamber side. In a combustor of a gas turbine that is configured by inserting a fuel pipe having an air passage, an air passage communicating with the air inflow pipe is formed in a boss portion inside the swirl swirler of the main burner, and the air passage is introduced into the air passage. An air ejection hole for ejecting air toward the combustion chamber is formed at the tip of the boss portion.

Further, in the combustor of the gas turbine according to claim 2 of the present invention, a plurality of concentric fuel passages are formed in the end cover arranged at one end side of the combustion chamber, and these fuel passages are formed as described above. It is connected to the fuel pipes of a plurality of sets of main burners, one set of which is arranged at a position 180 ° apart from each other around the pilot burner.

[0009]

According to the first aspect of the present invention, since the pilot burner provided in the central portion of the combustion chamber is of the diffusion combustion type, it exerts a good flame holding effect to the main burners arranged around it. The transfer of fire is reliable and easy, and the combustion flame at the time of ignition / starting can be stabilized, and even if the number of times the main burner is turned on / off increases due to frequent load changes, stable combustion can be maintained. It is possible, and the low NOx combustion can be reliably maintained by the change of the equivalence ratio per main burner according to the change of the load. Also, during premixed combustion in the main burner, part of the air flowing into the air inflow pipe passes through the air passage formed in the boss inside the swirl swirler, and burns from the air ejection hole at the tip of the boss. Since it is jetted toward the chamber and the air cools the boss, the boss is prevented from overheating,
It is possible to prevent flashback during premixed combustion.

According to a second aspect of the present invention, a plurality of fuel passages, which are concentrically formed in the end cover arranged at one end of the combustion chamber, are arranged in a symmetrical manner. Since it is connected to the fuel pipes of the main burners of the group, it is easy to equalize the distribution of the fuel to the main burners, and thereby a predetermined low NOx combustion can be stably performed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is a sectional view showing a combustor of a gas turbine according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG. In both figures, 1 is a cylindrical outer cylinder, 2 is a cylindrical combustion chamber housed in the outer cylinder 1,
An outer wall 3 of an engine (not shown) is coupled to one end of the outer cylinder 1 via flanges 1a and 3a by bolts and nuts, and an end cover 4 is bolted to the other end of the outer cylinder 1. The end portion on the end cover 4 side of the combustion chamber 2 is closed by a cover plate 6.

Reference numeral 7 is a diffusion combustion type pilot burner for directly injecting fuel into the combustion chamber 2, and only one is provided in the central portion of the combustion chamber 2. Reference numeral 8 denotes a premixed combustion type main burner that mixes fuel and air and then diffuses the mixture into the combustion chamber 2 and ejects the mixture, around the pilot burner 7 and in the pilot burner 7. And eight of them are arranged at equal intervals in the circumferential direction. Both the pilot burner 7 and the main burner 8 are provided so as to penetrate the cover plate 6 and have their tips protruding into the combustion chamber 2.

As shown in FIG. 3, the pilot burner 7 is fitted and held concentrically with the pilot air inflow pipe 10 into which an annular swirl swirler 9 is fitted. It is composed of a pilot fuel pipe 11 and a pilot (flame holding) multi-hole nozzle 12 fixed to the tip of the pilot fuel pipe 11, and the pilot fuel pipe 11 is connected to a pilot fuel supply pipe 13. . Injection hole 12a of the multi-hole nozzle 12 for pilot
As shown in FIG. 4, a plurality of are opened obliquely outward and are formed at equal intervals in the circumferential direction.

As shown in FIG. 5, the main burner 8 has an air inlet pipe 15 into which an annular swirler 14 is fitted, and a fuel pipe 16 concentrically fitted and held in the air inlet pipe 15. And a dispersion type nozzle 17 fixed to the tip of the fuel pipe 16 and positioned to face the swirl swirler 14, and the fuel pipe 16 is connected to the fuel supply pipe 18.
It is connected to the. As shown in FIG. 6, the dispersion-type nozzles 17 extend radially from the tip of the fuel pipe 16 in a radial direction and have a plurality of ends closed (indicated by 6 in the figure, but less or more than that). A large number of injection holes 17a are formed in each of the (good) pipes 17A so as to be located in a plane perpendicular to the fuel pipes 16.

Further, an air passage 19 is formed in the boss portion 14A inside the swirl swirler 14, and
An air ejection hole 14a for ejecting air obliquely outward is formed at the conical tip portion of the boss portion 14A, and a part of the air that has flowed into the air inflow pipe 15 is formed in the air passage 19 and the ejection hole. By jetting out into the combustion chamber 2 through 14a, overheating of the boss portion 14A is suppressed to prevent flashback during premixed combustion.

In each of the swirl swirlers 9 and 14 described above, the blades extending in the radial direction have air inflow pipes 10 and 15.
Are arranged side by side in the circumferential direction while being inclined at a predetermined angle with respect to the longitudinal direction.

Further, the end cover 4 is formed with four concentric fuel passages 24A to 24D,
The fuel passages 24A to 24D are respectively connected to the fuel supply pipes 18 in the four sets of the masonna 8 including two sets arranged at positions 180 ° apart from each other around the pilot burner 7. The fuel passages 24A to 24D and the pilot fuel supply pipe 13 of the pilot burner 7 are connected to a fuel manifold (not shown). In addition, in FIG.
Reference numeral 8 is a spark plug.

Next, the operation of the combustor of the gas turbine having the above structure will be described. In the pilot burner 7, compressed air supplied from an air compressor (not shown) flows into the air inflow pipe 10 as indicated by an arrow A, and is diffused into the combustion chamber 2 while swirling through the swirling swirler 9. The fuel supplied to the fuel pipe 11 is jetted into the combustion chamber 2 through the injection holes 12a of the multi-hole nozzle 12 and is instantaneously diffused by the air in the spiral shape. At this time, a stable flame holding portion is formed at the center of the spiral.

On the other hand, in the main burner 8, the compressed air flows into the air inflow pipe 15 as shown by the arrow B and is supplied into the four concentric fuel passages 24A to 24D formed in the end cover 4. The fuel is one to the other
After being evenly distributed to the fuel pipes 16 of the main burner 8 which is a set of two units arranged at 80 ° apart, they are jetted into the air inflow pipe 15 from the injection holes 17a of the dispersion type nozzle 17. Then, after being mixed with the above-mentioned air, it is diffused into the combustion chamber 2 through the swirling swirler 14 and ejected. Here, since the fuel is dispersed and ejected from the injection hole 17a of the dispersion type nozzle 17 into the air inflow pipe 15, the injection hole 17a is formed.
Even if the distance from the swirl swirler 14 to the swirler 14 is short, it is sufficiently mixed with the air. When the pilot burner 7 is ignited by the spark plug 38, the main burner 8 arranged close to the periphery of the pilot burner 7 is surely and easily ignited, whereby the combustion chamber Predetermined combustion is carried out in 2 to generate high pressure combustion gas for driving the engine.

In the above combustion state, the diffusion combustion is performed only by the pilot burner 7 in the central portion and the rest is premixed combustion by the main burner 8. Therefore, the amount of NOx generated is sufficiently reduced. Further, in the main burner 8, a part of the air flowing into the air inflow pipe 15 passes through the air passage 19 formed in the boss portion 14A inside the swirl swirler 14 and reaches the conical tip portion of the boss portion 14A. The air is ejected obliquely outward from the formed hole 14a into the combustion chamber 2, and the air suppresses overheating of the boss portion 14A, so that flashback during premixed combustion is prevented.

By the way, in the combustor of the gas turbine having the above structure, the number of the main burners 8 to be operated for combustion is changed according to the fluctuation of the load, so that stable combustion is performed with low NOx in the entire load range. That is, FIG. 7 shows the combustion operation state of the burner during load operation,
FIG. 8 is a diagram showing a valve control method at the time of starting combustion, in which two main burners 8, 8 positioned at an interval of 180 ° in the circumferential direction are set as a set (M1) and the load ratio is changed. Then, the fuel cutoff valves (not shown) corresponding to each of the four sets (M1, M2, M3, M4) are sequentially opened, and fuel is supplied to the main burner 8 of each set through the fuel supply pipe 18 and the fuel pipe 16. By performing the premixed combustion in this way, it is possible to perform stable combustion with low NOx and high efficiency in the entire load range. In addition, in FIG. 8, the horizontal axis represents the ratio of the engine speed, and the vertical axis represents the fuel amount.

In the above embodiment, eight main burners 8 are provided, and the combustion operation is controlled by dividing them into four sets, but the number of main burners 8 is an even number of four or more. Any number will do.

[0023]

As described above, according to the first aspect of the present invention, by providing the diffusion combustion type pilot burner in the central portion of the combustion chamber, a good flame holding effect is exerted and the surrounding area is provided. A condition that not only can reliably and easily transfer the fire to the placed main burner, but also stabilizes the combustion flame at the time of ignition / startup, and the load fluctuations are severe and the number of times the main burner is turned on / off increases. Even under the temperature, the combustion can be stably maintained and the low NOx combustion can be reliably maintained. Moreover, during premixed combustion in the main burner,
Cooling the boss part by injecting a part of the air that has flowed into the air inflow pipe toward the combustion chamber from the air ejection hole at the tip of the boss part through the air passage formed in the boss part inside the swirl swirler. Since the boss portion is prevented from overheating, flashback at the time of premixed combustion can be reliably prevented by a simple configuration improvement, and safety can be improved.

According to the second aspect of the present invention, a plurality of fuel passages are formed concentrically in the end cover arranged at one end side of the combustion chamber, and the plurality of fuel passages are arranged symmetrically. By connecting to the fuel pipes of a plurality of main burners, one of which is a set of two, it is easy to equalize the fuel distribution to each main burner while achieving a small space and reducing the overall size. The predetermined low NOx combustion can be performed more effectively.

[Brief description of drawings]

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

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

FIG. 3 is an enlarged vertical sectional view of a pilot burner.

FIG. 4 is an enlarged front view of the multi-hole nozzle of FIG.

FIG. 5 is an enlarged vertical sectional view of a main burner.

FIG. 6 is an enlarged vertical sectional front view of the dispersion type nozzle of FIG.

FIG. 7 is a diagram showing a combustion operation state of a burner during load operation.

FIG. 8 is a diagram showing a valve control method at the time of starting combustion.

[Explanation of symbols]

 2 Combustion chamber 4 End cover 7 Pilot burner 8 Main burner 14 Swirling swirler 14A Boss portion 14a Air ejection hole 15 Air inflow pipe 16 Fuel pipe 17 Dispersion type nozzle 19 Air passage 24A-24D Fuel passage

Front Page Continuation (72) Inventor Takesei Kimura 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries Ltd. Akashi Plant (56) Reference JP-A-4-43220 (JP, A) JP-A-61 -83813 (JP, A)

Claims (2)

(57) [Claims] 1. A diffusion combustion type pilot burner for directly injecting fuel into the combustion chamber is provided in the center of the combustion chamber, and a plurality of premixed combustion type main burners are arranged around the pilot burner. The main burner is a gas turbine combustor configured by inserting a fuel pipe having a distributed nozzle into an air inflow pipe provided with a swirl swirler at the end on the combustion chamber side, and inside the swirl swirler in the main burner. An air passage communicating with the air inflow pipe is formed in the boss portion, and an air ejection hole for ejecting the air flowing into the air passage toward the combustion chamber is formed at the tip of the boss portion. Gas turbine combustor. 2. A plurality of concentric fuel passages are formed in an end cover arranged on one end side of the combustion chamber, and these fuel passages are separated from each other by 180 ° about the pilot burner. The combustor for a gas turbine according to claim 1, wherein the combustor is connected to the fuel pipes of a plurality of sets of two main burners arranged in one set.