JPS61173024A - Gas turbine combustor - Google Patents

Abstract

PURPOSE:To improve durability and reliability of a combustor by installing a circumferential groove, into which a front end of a flat spring is allowed to enter to prevent erosion and cutting of the plate spring. CONSTITUTION:A gap g1 is kept between an inner cylinder 4 of a combustor and a transition piece 3. A plate spring 13 is assembled in a state with some initial load and is placed at the outerside of a groove 22 made on the inner cylinder 4 of the combustor. When the combustion gas flows in the inner cylinder of the combustor, the size of the gap becomes small as g2 due to the expansion of the cylinder by heat and then the plate spring 13 is compressed radically but a fulcrum moves in the direction of the arrow 23 as the spring is fixed at the rear end 11 of the inner cylinder 4 and the fulcrum drops into the circumferential groove 22. As a result, the fulcrum 21 of the plate spring 13 escapes from the direction of compressive load and the compressive load on the plate spring 13 becomes small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a combustor for a gas turbine, and more particularly to the structure of a mounting portion between a transition piece and an inner cylinder of the combustor.

[Background of the invention]

FIG. 1 is a diagram of a gas turbine combustor and its surroundings. Air 2 is compressed by compressor l.

The air flows around the transition piece 3 and the combustor inner cylinder 4, and then flows into the inner cylinder through an air hole formed in the combustor inner cylinder 4. Here, it is mixed and diffused with the fuel sprayed from the fuel nozzle 5, ignited by the spark plug 6, and combusted. Combustion gas 7.

It flows into the turbine section 8 through the combustor inner cylinder 4 and the transition piece 3, and rotates the rotor 9.

The exhaust gas 10 is released into the atmosphere. Combustor inner cylinder 4
and transition piece 3, the end 11 of the combustor inner cylinder 4 on the upstream side is inserted into the inlet part 12 of the transition piece 3 on the downstream side so that the combustion gas 7 flows smoothly as shown in FIG. It has a fitted structure. Also,
In order to prevent the compressed air 2 mentioned above from directly flowing into the transition piece 3, this part is designed to prevent thermal expansion of the combustor inner cylinder 4 and the transition piece 3 during operation in the radial and axial directions. In order to absorb it with
As shown in FIG. 6, the leaf spring 13 is bent into an arch.
is interposed. One side of the leaf spring 13 is fixed to the rear end 11 side of the combustor inner cylinder 4 by a spot welder 4 (Fig. 6), and when the combustor is assembled, the combustor inner cylinder 4 and the transition piece 3 are connected. The centers should be aligned so that the combustor inner cylinder 4 and the transition piece 3 would not come into direct contact with each other due to the weight of the combustor inner cylinder 4, vibrations generated by combustion, and air flowing around them. , it is assembled in a compressed state under some initial load. 2
1 is a sliding fulcrum (hereinafter simply referred to as the fulcrum),
FIG. 7 shows a state in which the combustor inner cylinder 4 and the transition piece 3 are assembled. In this case, that is, before operation, the engine is in the initial gap g115 state. Then, when the operation begins and high temperature combustion gas begins to pass through the combustor inner cylinder 4 and the transition piece 3, the combustor inner cylinder 4 undergoes thermal expansion 16 in the radial direction and axial The thermal elongation 17 in the direction, the transition piece 3 results in a thermal elongation 18 in the radial direction and a thermal elongation 19 in the axial direction. However, these thermal elongations do not occur and progress uniformly, and the combustor inner cylinder 4 has a thickness of one-third of the plate thickness of the transition piece 3.
Since the heat capacity is small and the mass is small, the time from when it starts to be exposed to combustion gas until it starts to thermally expand is very short.Furthermore, even if it is limited to the combustor inner cylinder 4, it overlaps with the transition piece 3. The part surrounded by the leaf spring 13 is not directly exposed to the air flowing around the combustor inner cylinder 4.
The metal temperature tends to become high, and as a result, the radial thermal expansion 16 of the rear end of the combustor inner cylinder to which the leaf spring 13 is attached starts earlier than the axial thermal expansion 17, and the rate of expansion becomes larger. Considering the sequence of occurrence and progression of thermal elongation based on the above-mentioned effects, first of all, in the radial direction 16 of the combustor inner cylinder,
, then its axial direction 17, and finally the axial direction 19 and radial direction 18 of the transition piece, which creates very severe conditions for the leaf spring 13.

That is, due to the difference in radial thermal expansion between the combustor inner cylinder 4 and the transition piece 3, the gap g2 between the two openings becomes extremely small, and the leaf spring 13 is subjected to a strong radial compressive force. Axial thermal elongation will occur. This phenomenon occurs every time the operation starts and stops, and the leaf spring 13 is repeatedly subjected to strong wear and large deformation.

Eventually, there is a risk that the compressed air will break and flow into the turbine section, or that a large amount of compressed air will flow in, resulting in a deterioration in turbine performance.

The technique of providing such a leaf spring in a gas turbine combustor is known, for example, as described in the US document (ASME81-GT-
32 Figs, 3. , and ASM11'70-P
It is shown in Fig. 1) of vr-14. For the above-mentioned leaf springs, there is an urgent need to improve their reliability and durability for the reasons mentioned above.

[Purpose of the invention]

An object of the present invention is to prevent the above-mentioned abrasion and breakage of the leaf spring and to improve the durability and reliability of the combustor.

[Summary of the invention]

The basic principle of the present invention created to achieve the above object will be briefly described below. When the gas turbine starts operating and thermal expansion occurs in the combustor inner cylinder, and a compressive load is applied to the leaf spring, the other fulcrum moves in the opposite direction to the fixed end of the leaf spring, and at that time, that fulcrum moves toward the inner circumference. A groove is provided on the outer periphery of the combustor inner cylinder to allow the combustor to escape. The fulcrum escapes inward to reduce the compressive load on the leaf spring, reducing the surface pressure when the leaf spring slides in the axial direction, thereby preventing early wear and breakage of the leaf spring.

[Embodiments of the invention]

An embodiment of the present invention is shown in FIGS. 1 to 3.

FIG. 1 shows a state before combustion gas starts to flow inside the combustion base inner cylinder 4, and before both the combustor inner cylinder 4 and the transition piece 3 generate thermal elongation. FIG. 2 is a perspective view in this state. At this time, there is a gap gt (Fig. 1) between the combustor inner cylinder 4 and the transition piece 3, and the leaf spring 13 is assembled with some initial load. The fulcrum 21 is located outside the groove 22 provided in the combustor inner cylinder 4. However, when the combustion gas flows through the next combustor inner cylinder and thermal expansion occurs, the combustor inner cylinder 4 and transition piece 3
The gap between g and g becomes very small. Then, the plate bar 13 is compressed in the radial direction, but since the rear end 11 side of the combustor inner cylinder 4 is fixed, the fulcrum 21 moves in the direction of the arrow 23. The fulcrum 21 of the leaf spring 13, which has moved in the direction of the arrow 23, falls into the groove 22 of the combustor interior 4. As a result, the fulcrum 21 of the leaf spring 13
However, the compressive load will escape from the direction in which the compressive load is applied, and the compressive load applied to the leaf spring 13 will become smaller.

Next, thermal elongation in the axial direction of the combustor inner cylinder 4 and the transition piece 3 occurs, and friction occurs between the leaf spring 13 and the transition piece 3. At this time, the surface pressure acting on the leaf spring 13 is Since it is small, the wear of the leaf spring 13 is greatly reduced, and the durability of the leaf spring can be improved.

In addition, during operation, a force that tends to crush the internal state of the combustor acts on the combustor internal cylinder due to the pressure difference between the inside and outside of the internal cylinder and the wind pressure caused by the flow of compressed air. If the groove 22 is formed by constricting a part of the groove 22, the section modulus will increase due to the structural mechanical effect of this constricted part.
This has the secondary effect of improving the strength of the combustor inner cylinder itself.

As explained above, the configuration of providing a cylindrical groove that allows the tip of the leaf spring to enter can be applied to a conventional combustor (including the leaf spring) without changing the main specifications thereof.

〔Effect of the invention〕

As clarified by the above-mentioned embodiments, when the present invention is applied, it is possible to prevent wear and breakage of the leaf spring provided at the connection part of the combustor, and improve the durability and reliability of the combustor. This has excellent practical effects.

[Brief explanation of drawings]

1 to 3 show one embodiment of the present invention, FIG. 1 is a cross-sectional view in a state before the start of operation, and FIG. 2 is a perspective view depicting the leaf spring and the combustor inner cylinder in the same state. , FIG. 3 is a cross-sectional view of a state where thermal elongation has occurred after the start of operation. FIG. 4 is a cross-sectional view showing the overall configuration of a gas turbine combustor, FIG. 5 is a cross-sectional view showing the joint between the combustor inner cylinder and transition piece of a conventional gas turbine combustor, and FIG. FIG. 2 is a perspective view of a conventional combustor inner cylinder equipped with a combustor. FIGS. 7 and 8 are explanatory diagrams of thermal stress applied to a leaf spring6 1.1. Compressor, 2... Compressed air, 3... Transition piece, 4... Combustor internal information, 5... Fuel nozzle, 6... Spark plug, 7... Combustion gas, 8...
Turbine, 9... Turbine rotor, 10... Exhaust gas, 11... Rear end of combustor inner cylinder, 12... Transition piece inlet, 13... Leaf spring, 14... Spot welding part , 16... Thermal elongation radial direction of the combustor inner cylinder,
17...Thermal elongation in the axial direction of the combustor inner cylinder, 18...Thermal elongation in the radial direction of the transition piece, 19...Thermal elongation in the axial direction of the transition piece, 22...Provided in the combustor inner cylinder Circumferential groove. 23... Extension direction of the leaf spring.

Claims (1)

[Claims] In a gas turbine combustor in which one end of the combustor inner cylinder is fitted into one end of the transition piece, and a sealing plate spring is interposed in the fitting part, when the plate spring receives a compressive load, the plate A gas turbine combustor characterized in that a circumferential groove that allows the tip of a spring to enter is provided on the outer periphery of an inner cylinder of the combustor.