JPH0343536B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a gas turbine combustor, and particularly relates to a gas turbine combustor that employs a two-stage combustion method in which the concentration of nitrogen oxides (NOx) in combustion gas is low. .

[Background of the invention]

In order to significantly reduce NOx in gas turbine combustors, a so-called two-stage combustion method is used to supply fuel to two stages in order to achieve uniform low-temperature combustion throughout the combustor. It has been used a lot recently. For example, a two-stage combustion type combustor was developed in 1987.
It is well known as seen in Japanese Patent No.-161422. A cross-sectional view of this known combustor is shown in FIG. The gas turbine includes a compressor 1, a turbine 2, a combustor 3, and the like. The air 4 compressed by the compressor 1 is guided to the combustor 3, which has a primary fuel nozzle 9 that supplies primary fuel 8 to the outer cylinder 5, inner cylinder 6, and head combustion chamber 7. The end cover 10 with the attached end cover 10 is attached. The inner cylinder 6 is a head combustion chamber 7
A connecting part 1 between the head combustion chamber 7 and the rear combustion chamber 11 is formed by a rear combustion chamber 11 having a larger diameter than this.
2 is provided with a secondary air supply hole 13, through which secondary fuel 14 is injected and supplied together with the secondary air to the rear combustion chamber 11 to form a premixed combustion flame 15 with excess air. As mentioned above, the inner cylinder 6 has an integral structure in which the head combustion chamber 7, the secondary air supply hole 13, and the rear combustion chamber 11 are connected, as shown in FIG. The cylinder 16 is housed in the outer cylinder 5 with its head supported by several stoppers 17 projecting radially. In addition, secondary air supply hole 1
A disk-shaped secondary fuel nozzle main body 14a is provided at the upstream part of the secondary fuel nozzle 3, and a plurality of secondary fuel nozzles 1
4b protrudes in the axial direction toward the secondary air supply hole 13 so that fuel can be injected. However, the conventional two-stage combustor described above has the following drawbacks. One is the rear end 7a of the head combustion chamber 7 where the primary combustion flame 18 and the secondary combustion flame 15 are in contact with each other.
, the flame may stagnate and the metal temperature may rise abnormally. Also, secondary air supply hole 13
This has the disadvantage that the metal temperature is low due to the constant flow of low temperature air, and excessive thermal stress is generated at the connection portion with the rear end portion 7a due to the temperature difference. The same can be said of the connection portion with the rear combustion chamber 11. Second, there is a drawback that the relative positional relationship with the secondary fuel nozzle 14b cannot be maintained in the event of thermal elongation or deformation of both. The above are the drawbacks of the conventional two-stage combustor.

[Purpose of the invention]

The present invention aims to improve the reliability of the secondary air supply hole, which is a weak point, in a combustor that can achieve low NOx through a two-stage combustion method, thereby ensuring reliability during long-term operation of the gas turbine. The purpose is also to reduce maintenance and operation costs.

[Summary of the invention]

That is, in the present invention, a swirler is fixedly held on an outer cylinder, a two-stage fuel nozzle is integrally provided on this swirler, and a downstream side wall of a head combustion chamber and a rear combustion chamber are connected to this swirler via a leaf spring. It was designed to support the upstream side wall of the bridge to achieve the intended purpose.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention. In this figure, a plurality of outer cylinders 21 are attached to the front side of a combustor casing 20, and inside thereof are located a combustor inner cylinder 22 and a transition piece 23 that guides the combustion gas generated therein to the turbine section. ing. The combustor inner cylinder 22 includes a head combustion chamber 25 for burning fuel from a primary fuel nozzle 24 and a rear combustion chamber 27 for burning fuel from a secondary fuel nozzle 26 and mixing it with primary combustion gas. It consists of two combustion chambers, each of which has a separate structure. Outer cylinder 21
is composed of a front outer cylinder 21a and a rear outer cylinder 21b, and a disk-shaped secondary fuel nozzle main body 28 is clamped and bolted to the middle part of both outer cylinders. The head combustion chamber 25 has a front cover 29 with a hole in the circumferential direction attached to the front end 25a so that the fuel injection nozzle 24a of the primary fuel nozzle 24 projects into the combustor. The head combustion chamber 25 is positioned at the center of the outer cylinder 21 by fitting the cone 24b of the primary fuel nozzle 24 with the collar 30 provided on the inside. Furthermore, a plurality of plate-shaped stoppers 31 are provided radially around the outer periphery of the head combustion chamber 25, and are assembled so as to fit into supports 32 that protrude toward the center from the inner periphery of the front outer cylinder 21a. It is designed to prevent axial movement and circumferential rotation during operation.
In order to prevent the head combustion chamber 25 from abnormally moving forward due to axial movement, the primary fuel nozzle 24 is restrained by a pin 34 protruding from the cover 33 supporting the primary fuel nozzle 24 in the axial direction. It's summery.
On the other hand, a plate-shaped spring 35 is provided around the entire circumference of the rear end portion 25b of the head combustion chamber 25. The rear combustion chamber 27 has a slightly larger diameter than the head combustion chamber 25, and the front end 27a has a cylindrical shape without a cover like the head combustion chamber 25. This rear combustion chamber 27 has a stopper 36 similar to that of the head combustion chamber 25 on the outer periphery of the front end 27a.
It is supported and fixed by a support 37 and a pin 38 attached to the secondary fuel nozzle body 28.
A plate-shaped spring 39 is provided around the entire circumference of the rear end portion 27b to ensure engagement with the transition piece 23, and the rear combustion chamber 27 is inserted into the transition piece 23. Built-in. FIG. 2 shows details of the combustor of the present invention. In this figure, the rear end 25b of the head combustion chamber 25 and the front end 2 of the rear combustion chamber 27 are shown.
7a has a certain dimension in the axial direction and is positioned by the aforementioned stopper and support so as to have a uniform space in the radial direction. In this space, fuel 41 is injected from a secondary fuel injection nozzle 40 that passes through the secondary fuel nozzle main body 28 and projects downstream through the fuel reservoir 28a, and secondary air 42 that flows into this space. A swirler 43 is installed to mix the mixture and flow it into the combustor.
This swirler 43 efficiently mixes the fuel 41 from the plurality of secondary fuel injection nozzles 40.
It has a double circular ring shape, and includes a plate spring 44 provided all around the outer circumference and a plate spring 35 provided all around the outer circumference of the rear end portion 25b of the head combustion chamber 25 mentioned above. It is inserted and supported by compressing each spring by a small amount between the two. With this structure, thermal stress due to temperature difference is not generated in each combustion chamber, and each thermal expansion can be absorbed by the plate spring. Furthermore, vibrations of the combustor due to combustion vibrations can also be absorbed by this leaf spring. In order to prevent the metal temperature from rising during operation, numerous small cooling holes 45 are provided in the rear combustion chamber 27, and the wall surface 47 is cooled by flowing air 46 thereinto. However, during operation, the areas around the plate springs 35 and 44 also become hot, so the plate springs 35 and 44 are provided with a large number of slits 48 in the axial direction as shown in FIG. It is used to improve workability during installation and as a cooling air introduction groove, and the inflow of cooling air 52 cools the wall surface 49 of the rear end 25b of the head combustion chamber 25, as well as the inner and outer circumferential surfaces of the swirler 43 and the rear combustion chamber. The front end 27a of 27 can be cooled. Note that the plate spring 35 (same as the spring 44) has an arc shape as shown in FIG.
One end is fixed and attached to the combustion chamber main body 50 by spot welding 51 or other means. 2
As mentioned above, the swirler 43 is provided in the secondary fuel nozzle body 28 in order to efficiently mix the fuel 41 from the secondary fuel injection nozzle 40 and the secondary air 42, but the positional relationship of each of these is very important. Swirler 4 is used to enable uniform premixing.
3 and the secondary fuel nozzle body 28 are integrated by welding or bolting so that they can be held in a certain position. As mentioned above, the head combustion chamber and the rear combustion chamber are separated, and in order to achieve efficient premixing, the fuel nozzle jet hole and the swirler for promoting mixing are integrated. It is characterized by becoming

〔Effect of the invention〕

According to the present invention, since the degree of freedom around the secondary air supply hole is increased, it is possible to prevent the occurrence of thermal stress due to temperature differences, and therefore, it is expected that the reliability of the combustor will be improved. Furthermore, since the two-stage combustion type combustors with different diameters can be manufactured separately, the number of man-hours can be greatly reduced. When assembling and disassembling, the weight of each item is lighter, making it easier and faster to assemble and disassemble. Furthermore, in the case of localized damage to a combustor, it is possible to replace only the damaged combustion chamber without having to replace the entire combustor set, reducing operating costs. I can do it. In the fuel nozzle, since the fuel nozzle ejection hole and the swirler can be integrated, fuel and air can be premixed efficiently. Due to the split structure, the length of the combustion chamber can be shortened as a single unit, and this can prevent buckling strength due to pressure differences inside and outside the combustion chamber or progress of creep deformation at high temperatures.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a detailed sectional view of main parts, FIG. 3 is a detailed perspective view of a second plate-shaped spring, and FIGS. 4 and 5. is a cross-sectional view of a conventional combustor. 40...Secondary fuel injection nozzle, 48...Slit, 28...Fuel nozzle body, 51...Spot welding, 35...Spring, 52...Cooling air, 43...
...Swirler, 25...Head combustion chamber, 44...Spring, 27...Rear combustion chamber.

Claims (1)

[Claims] 1. A first-stage fuel nozzle that injects fuel;
It also has a head combustion chamber where air is introduced and combustion takes place, and a second-stage fuel nozzle that injects second-stage fuel into the wake of the head combustion chamber, and a mixture with air is supplied to perform combustion. a rear combustion chamber, and an outer cylinder arranged on the outer periphery of the head combustion chamber and the rear combustion chamber; In the combustor, the swirler is fixedly held on the outer cylinder, a second stage fuel nozzle is integrally provided on the swirler, and the downstream wall of the head combustion chamber is connected to the swirler via a leaf spring. and a gas turbine combustor, characterized in that the upstream side wall of the rear combustion chamber is supported.