JPH02154919A - Heat shielding pressure partition wall - Google Patents

Abstract

PURPOSE:To reduce a temperature difference in a liner shell by introducing cooling air into intermediate chambers through cooling holes provided in an outer shell to carry out the convective cooling of honeycomb-like fins in an inner shell, discharging the cooling air in the intermediate chambers into a combustion chamber through holes provided at the backward flow ends of the inner shell, and forming a cooling air layer on the combustion chamber side of the inner shell to prevent the inner shell from being heated. CONSTITUTION:Cooling air in a cooling air chamber 3 passes through cooling holes 5 to impinge against pieces 6 and enters intermediate chambers 7. The outer circumferential surfaces of the pieces 6 are cooled by the impingement and convective cooling of the cooling air. The discharge of the cooling air from the intermediate chambers 7 into a combustion chamber 4 is carried out through discharge channels 8 provided at the circumferential ends of the pieces 6, thereby cooling the inner side surfaces of the pieces 6 and the inner side surfaces of the pieces 6 on the backward flow side. The temperature of the pieces 6 becomes high because they are directly subjected to the flame in the combustion chamber and, as a result, a thermal stress is generated by a temperature difference between the pieces 6 and an outer shell 1. Accordingly, in order to reduce the thermal stress, it is required to divide the thermal stress into the axial and peripheral directions. Therefore, the discharge channels 8 are provided linearly in the peripheral direction and in the axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a combustor for a gas turbine, and particularly to a combustor structure suitable for reducing metal temperature and thermal stress of liners and transition pieces.

[Conventional technology]

In order to increase the output and efficiency of a gas turbine, its operating temperature can be increased. However, in this case, since the combustion chamber is exposed to extremely high temperatures, it is necessary to improve the combustor components and the cooling method. In particular, if the cooling structure is improved,
High temperatures can be achieved without using expensive heat-resistant alloys.

Combustor cooling includes convection cooling using compressor discharge air and film cooling that forms a thin film of cooling air between the combustion chamber and the high-temperature combustion gas. - In boat fishing, a method is often adopted in which compressor discharge air is introduced into a combustion chamber and a protective film is formed on the inner surface of the combustor shell. In order to cool the entire combustor shell, the shell is formed with a plurality of holes spaced apart in the axial direction, and the shell is generally cylindrical in shape, and a plurality of holes are also formed in the circumferential direction of the shell. be. Increased cooling air usage has an undesirable effect on combustor performance and is preferably kept to a minimum. In particular, a low NOx type combustor requires a large amount of combustion air.

In order to form a cooling air film on the inner surface of the combustor, it is necessary to align the direction of air entering the shell with the inner surface to form a boundary layer that does not suck in or entrain the high-temperature gases in the combustion chamber. There is. To properly direct this cooling fluid flow, it is common to use an axially extending overhanging lip to form slots that properly direct the fluid flow between the lip and the inner surface of the combustor. be.

FIG. 2 shows a sectional view of a conventional liner with an overhanging lip as disclosed in Japanese Patent Application Laid-Open No. 51-141912.

The liner shell 1 has a hollow, cylindrical shape and has an overhanging lip 2 on its inner surface, and the lip is attached to the chevron-shaped part of the liner 1. A cooling air hole 5 for introducing cooling air from the cooling air chamber 3 to the combustion chamber 4 is provided in the shell on the downstream side of the overhanging lip 2. The cooling air hits the lip 2 from the cooling hole 5, and the liner shell 1 is configured to create a cooling layer along the inner surface of the However, when a liner with an overhanging lip is heated to a higher temperature than before, the following problem occurs. The first is that a temperature difference occurs in the shell wall between the lips of the liner shell as shown in FIG. 3, and in the state shown, tensile thermal stress acts around the cooling holes. Second, the shell between the lips is directly exposed to the flame, which creates a boundary layer of cooling air and adds radiant heat, making the shell temperature extremely high and shortening the life of the combustor. This is a contributing factor. In particular, if the temperature of the gas turbine is raised, the life of the gas turbine will be further shortened because the temperature of the shell will rise.

[Problem to be solved by the invention]

The above conventional technology attempts to form a cooling air layer inside the liner shell, but due to the turbulent flow of flame inside the combustion chamber,
Since no consideration has been taken to prevent the flow from being disturbed, and no measures are taken to prevent heat radiation, a temperature difference occurs in the liner shell, which is a strength member, generating thermal stress and causing extreme heating. There was a problem with the shell becoming hot.

The purpose of the present invention is to attach the inner surface of the liner shell and the inner shell so that combustion radiant heat does not directly hit the liner shell,
It is an object of the present invention to provide a combustor that reduces the temperature difference between liner shells and lowers the temperature.

Another object of the present invention is to provide a combustor that can lower the shell temperature and withstand long-term use, and to provide a combustor whose shell member can be manufactured at low cost.

[Means to solve the problem]

Inside the combustor shell that separates the cooling air chamber and the combustion chamber is another layer of shell, the inner shell being spaced a certain distance from the outer shell. In other words, the combustion treasure is double, with an intermediate chamber between the inner and outer shells. The sides of the intermediate chamber of the inner shell are completely covered with a honeycomb that is lower than the gap between the intermediate chambers. Cooling air is introduced into this intermediate chamber through cooling holes in the outer shell to cool the honeycomb fins in the inner shell by convection. The cooling air in the intermediate chamber is discharged from the hole at the trailing end of the inner shell to the combustion chamber, forming a cooling air layer on the combustion chamber side of the inner shell to prevent heating of the inner shell.

In this way, the above objective is achieved.

[Function] In conventional technology, a lip was provided inside the shell to create a cooling air layer, but because the length of the lip is partial, the cooling layer is damaged by vibrations of the combustion flame and heat radiation. Sometimes it is not fully formed. Therefore, in the present invention, with the main aim of reliably lowering the temperature of the outer shell, which is a strength member, and reducing thermal stress caused by temperature unevenness, an intermediate chamber is created inside the outer shell and separated from the combustion chamber. The layered slits ensure the formation of a cooling air layer inside the 1A shell, and the temperature of the outer shell.

At the same time, since the outer shell is not exposed to flame, it is not subject to heat radiation and temperature non-uniformity is eliminated. Cooling holes are provided in the outer shell,
Cooling air is introduced into the intermediate chamber from the outside of the outer shell, and the inner shell, which has a honeycomb on its surface inside the intermediate chamber, is cooled by what is called a pin fin. Although this inner shell is in direct contact with the flame in the combustion chamber, it does not reach a particularly high temperature because of its high bottle fin cooling efficiency.

In addition, a cooling air layer is formed on the combustion chamber side by the exhaust cooling air flowing from the intermediate chamber to the combustion chamber. That is, film cooling is performed. This also prevents the inner shell from becoming too hot.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows one embodiment of the present invention.

Between the cooling air chamber 3 and the combustion chamber 4 there is a combustor shell 1 . A plurality of pieces 6 are fixed to the outer shell 1 by brazing, welding, or the like. Further details are as follows.

As shown in FIG. 4, a honeycomb 30 is brazed to the surface of the piece 6 on the intermediate chamber 7 side. Some of the hollow hexagonal columns forming the cells of the honeycomb 30 are tall, and others are short. The former is a support column 31 of the piece 6 with honeycomb 30 to the outer shell 1, and the latter serves as a so-called turbulence promoter 32, which promotes heat transfer by cooling air flowing through the intermediate chamber 7. The honeycomb 30 is assembled into a turbulence promoter 32 by brazing the parts 6 and removing the plurality of support columns 31 by etching.
The height of the honeycomb 30 is lowered.

Part 6 and outer shell 1 are nickel-brazed again.

Alternatively, it is fixed by diffusion bonding. The ends of the pieces.

Adjacent to other parts with a narrow gap between them. This gap is.

It is determined by the amount of air flowing in from the cooling air chamber 3 and the amount of thermal expansion of one piece 6. The cooling air in the cooling air chamber 3 impinges on the piece 6 through the cooling holes 5 and enters the intermediate chamber 7 .

The outer peripheral surface of the piece 6 is cooled by this collision and convection cooling.

Cooling air is discharged from the intermediate chamber 7 to the combustion chamber 4 through an exhaust groove 8 provided at the peripheral end of the piece 6, and from the inner surface of the piece 6.
Then, the inner surface of the piece 6 on the downstream side is cooled. Piece 6 comes into direct contact with the flame in the combustion chamber, so it becomes hot, and the outer shell 1
Thermal stress occurs due to the temperature difference between the Therefore, in order to reduce thermal stress, it is necessary to divide the groove in the axial direction and the circumferential direction.
In this example, the piece 6 has a tile shape. Of course, small pieces may be attached, but since this increases the number of manufacturing steps, it is better to minimize the number of pieces 6. In addition, as shown in FIG. 4, a slit 1 is provided at the end of the discharge groove 8 to relieve stress.
If 0 is provided, the stress concentration in the piece 6 will be reduced and its life will be extended. Since the exhaust grooves 8 and the slits 10 affect the performance of the cooling air, it is necessary to sufficiently adjust their dimensions. Further, it is preferable that the cooling holes 5 have a large diameter and a small number to cool the piece 6 as far as the strength and performance of the outer shell allow. The discharge groove 8 may have a hexagonal shape. As shown in Fig. 6, since it is necessary to effectively cool the adjacent parts near the discharge groove 8 on the downstream side of the piece 6, the end of the downstream side piece 6 is removed to facilitate the formation of a cooling air film. Slanted toward the shell side, the cooling air film as a boundary layer is less susceptible to disturbances in the combustion chamber gas flow. The condition is that the cooling holes 5 in the outer shell are separated from the slits 10 in the discharge groove 8.

This is to prevent cooling air introduced from the cooling holes 5 from directly entering the combustion chamber 4.

FIG. 5 shows a second embodiment of the invention. The outer shell 1 has a ring shape with a chevron in the axial direction to improve rigidity. A piece 6 is fixed inside the outer shell on the downstream side of the cooling hole. The upstream side of the piece is.

attached to the outer shell. Cooling air enters the intermediate chamber 7 through the cooling hole, flows through the intermediate chamber while colliding with the fins of the piece, exits through the exhaust hole 8 at the rear end of the piece, and spreads a cooling film layer along the inner surface of the adjacent piece. Form and cool the pieces. The circumferential exit of the piece is provided with a drainage groove, which serves to relieve thermal stresses in the piece. Further, since the position of the cooling hole can be moved to any position in order to cool the parts, it is possible to equalize the temperature of the parts and reduce thermal stress. Also,
In order to minimize the amount of cooling air, the cooling holes may be made small. At this time, the inner surface of one piece may be coated with a thermal radiation coating to lower the metal temperature of the piece and improve its life.

The pieces can be attached partially in the axial direction and also in the circumferential direction of the combustor shell. Further, both the liner and the transition piece can be applied to a multi-tube combustor, and can also be applied to an annular combustor.

〔Effect of the invention〕

According to the present invention, extreme temperature increases due to heat radiation are eliminated. Additionally, the shell can be kept at a sufficiently low temperature.

In addition, the temperature in the inner shell is sufficiently low.

Furthermore, the combustion chamber side is film-cooled by the exhaust air from the intermediate chamber. Furthermore, applying a thermal barrier coating will be sufficiently effective against the rise in temperature of the inner shell.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a combustor according to an embodiment of the present invention. Figure 2 is a cross-sectional view of a conventional combustor, Figure 3 is a wall temperature distribution diagram of a conventional combustor, Figure 4 is a view of the honeycomb on the piece of Figure 1 seen from the intermediate chamber side, FIG. 5 is a cross-sectional view of a combustor according to a second embodiment of the present invention, and FIG. 6 is a cross-sectional view of a combustor according to a third embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Combustor outer shell, 3... Cooling air chamber, 4... Combustion chamber, 5... Cooling hole, 6... Part, 7... Intermediate chamber, 8... Discharge Groove, 10... stress relaxation slit. Figure 1 Figure 2 Figure 5 Figure 6

Claims (1)

[Claims] 1. In a partition wall in which a heating medium flows along one surface and a cooling medium flows along the other surface, the surface through which the heating medium flows is constituted by a plurality of pieces,
The surface through which the cooling medium flows is composed of one continuous surface, an intermediate chamber is formed between the surfaces, and the cooling medium flows from the surface through which the cooling medium flows via the intermediate chamber. ,
A heat shielding pressure partition wall characterized in that a means for flowing toward the heating medium and a means for promoting heat transfer from the heating medium are provided on the intermediate chamber side of the surface through which the heating medium flows. 2. In claim 1, the surface through which the cooling medium flows and the heating medium are arranged so that the cooling medium flows from the surface through which the cooling medium flows through the intermediate chamber and toward the heating medium side. A heat shielding pressure partition wall characterized in that a plurality of holes communicating with the intermediate chamber are provided on the flow surface. 3. In claim 1, as a means for promoting heat transfer from the heating medium to the surface on the intermediate chamber side of the surface through which the heating medium flows, a honeycomb-shaped piece is placed on the surface through which the heating medium flows. A heat shielding pressure partition wall fixed to a surface on the side of the intermediate chamber.