JPH02308926A - Cooling structure for trail cylinder of gas turbine combustor - Google Patents

Abstract

PURPOSE:To provide a cooling structure which enhances its cooling function while restricting thermal stress by dividing a space between a cover covering a part of a tail cylinder and the latter into several small spaces with the use of partition plates. CONSTITUTION:An impinging type cooling cover plate 13 is fixed to at least a part of a tail cylinder on the turbine stator vane 6 side, and is formed therein with several small holes 18, defining an air passage 11 between the cover plate 13 and the tail cylinder 4. An air hole 12 is formed in the tail cylinder 4 at a position where the tail cylinder 4 makes contact with the air passage 11. In this arrangement, there are provided partition plates 14 so as to divide the air passage 11 into several spaces. With this arrangement, heat can be smoothly transmitted to the cover plate 13 from the tail cylinder 4 by way of the partition plates 14. Thereby the cooling function of the tail cylinder 4 can be enhanced being caused by an increase in heat transmission of the outer periphery of the cover plate 13 through a guide wall 6. Further, the temperature of the tail cylinder 4 approaches the temperature of the tail cylinder 4 due to the provision of the partition plates 14, thereby it is possible to reduce thermal stress caused by a difference in temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas turbine combustor transition piece, and particularly to a cooling structure suitable for a transition piece of a high-temperature gas turbine combustor where the combustor exit gas temperature is high.

[Conventional technology]

A gas turbine combustor is a component that guides air pressurized by a compressor and fuel pressurized by a separate system into an inner cylinder, burns it to generate high-temperature gas, and guides it to a turbine via a transition piece. When the humidity of the combustion gas led to the turbine increases, the temperature of the transition tube wall surface exceeds its allowable limit, so special cooling is required. As shown in Figure 5, the gas passage area of the transition piece is larger on the inner cylinder side and smaller on the turbine side, so the heat transfer coefficient from the combustion gas to the wall of the transition piece is as shown in Figure 6. It is smaller on the inner cylinder side and thicker on the turbine side. Therefore, in order to cool the transition tube so that the wall surface temperature is uniform, it is necessary to strengthen the cooling on the turbine side more than the cooling on the inner tube side, which has been considered in the past. As an example, Fig. 4 shows JP-A-62-1111.
．． The structure of No. 32 is shown. By providing a guide wall 5 in a portion close to the inner cylinder, the flow velocity of air guided to the inner cylinder is increased to perform forced convection cooling. On the turbine side, impingement cooling is used to obtain a higher heat transfer coefficient, and a cover plate 13 is fixed to the outer periphery of the transition piece 4 so as to form a space at a constant interval. The cover plate 13 is provided with a large number of air holes 8, and the air flowing in from the air holes 8 collides with the transition piece 4, cools it, and is discharged through the air hole 12 into the transition piece gas passage. .

[Problem to be solved by the invention]

In the above conventional technology, the heat transfer from the transition piece 4 to the cover plate 13 is only by radiation heat transfer and heat conduction at the joints around the cover plate, and the amount of heat is small and passes through the air hole 8 of the cover plate 13. Since the cover plate 13 is sufficiently cooled by convective heat transfer by air, there is a large temperature difference between the transition piece 4 and the cover plate 13, and the thermal stress caused by the difference in thermal expansion causes the cover plate to cool down repeatedly when starting and stopping. ] There was insufficient consideration given to the possibility of deformation and damage to the engine, resulting in a decrease in cooling performance and a shortened transition tube life. Furthermore, by providing the guide wall 5 on the inner cylinder side of the transition piece 4, the air flow velocity around the cover plate 13 increases, and the cover plate 13 is further cooled.
The fact that the thermal stress of the cover plate 13 is increasing has not been taken into consideration.

An object of the present invention is to provide a cooling structure in which thermal stress is less likely to occur while improving cooling performance.

[Means to solve the problem]

In order to achieve the second objective, an impingement cooling cover plate that covers a part of the transition piece is installed at a certain distance from the transition piece on the turbine side, where the heat transfer coefficient inside the transition piece is large, and the cover plate is In addition, the space between the cover plate and the tail piece is divided into many parts by a partition wall, and the partition wall is fixed to the cover plate and the tail piece. The transition piece that is in contact with the space with the cylinder is provided with one or more small holes that communicate with the gas passage inside the transition piece.

Further, a guide wall that forms an annular passage is provided on the outer periphery of the transition piece on the side of the inner cylinder where the heat transfer coefficient is small inside the transition piece, thereby forming a passage for air to be supplied to the inner cylinder.

[Effect]

In the impingement cooling section provided on the turbine side of the transition piece, air flows in from the small hole group due to the pressure difference between the inside and outside of the cover plate and cools the transition piece by colliding with the transition piece.

The partition wall that connects the transition piece and the cover plate transfers heat from the transition piece to the cover plate by thermal conduction, so the temperature of the cover plate approaches the temperature of the transition piece, and due to the difference in thermal expansion due to the temperature difference between the cover plate and the transition piece. Thermal stress generated is reduced. As the temperature of the cover plate increases by 2, the temperature difference with the air flowing around the outer periphery of the cover plate becomes large, and convective heat transfer around the outer periphery of the cover plate is added to increase the cooling effect.

By selecting the annular passage area of the guide wall provided on the inner cylinder side of the transition piece, the air flow velocity and cooling performance can be selected, so the temperature of the wall surface of the transition piece covered by the guide wall can be selected. By providing a guide wall, the outer circumferential air flow velocity on the turbine side of the transition piece is increased, and the cooling performance of the impingement cooling structure with an internal partition wall is improved, so less impingement cooling air is required. Cooling at the same level as before is possible.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. Let me explain.

A combustor located between a compressor 10 (not shown) and a turbine stator blade 6 has an internal oil 2 that generates combustion gas, a transition pipe 4 that guides the generated combustion gas to the turbine stator blade 6, and a transition pipe 4 that supplies fuel to the inner cylinder 2. The main component is a fuel nozzle 1 (not shown). A guide tube 3 is provided on the outer tube of the inner tube 2 to increase the air flow velocity to improve cooling performance, and a similar guide wall 5 is provided on the inner tube side of the transition tube 4. A cover plate 13 for collision cooling is fixed to at least a part of the turbine blade side of the transition piece 4, and the cover plate 13 is provided with a large number of small holes 8. An air passage 11 is provided between the cover plate 13 and the transition piece 4, and an air passage 11 is provided in the transition piece 4 that is in contact with the air passage 1.
An air hole 12 is provided which communicates with the gas passage inside the transition piece. An example of the cross section of the impingement cooling section is shown in FIG. By providing a partition wall 14 between the transition piece 4 and the cover plate 13, the air passage 11 is divided, and a row of air holes 8 for collision cooling is provided for each air passage 11. A large number of air holes 8 are provided in the flow direction of the air passage 11.

In the structure of the present invention, the air that flows in from the many air holes 8 provided in the cover plate 13 for collision cooling due to the pressure difference between the inside and outside collides with the transition piece 4 to cool the transition piece 4, and the collided air flows through the air passage 11. The gas flows inside toward the turbine stationary blade 6 side, passes through the air hole 12 provided in the transition piece 4, and is discharged into the gas passage.

The heat transfer coefficient due to impingement cooling can be adjusted by changing the ratio between the diameter and pitch of the air holes 8, and it is possible to maintain a uniform temperature at a location where there is a distribution on the heating side.

Also, the air flow rate flowing inside the air passage 1 soil is the air hole 8.
Since a large number of partition walls 14. The amount of heat exchanged with the cover plate 13 increases, and the transition piece 4 is further cooled. Moreover, the cover plate 13 is cooled by the air when passing through the air hole 8 of the cover plate 1.8. Further, since air flows around the outer circumference of the cover plate 13 toward the inner cylinder 2, the cover plate 13 is cooled by this air flow.

On the other hand, by providing the guide wall 5 on the inner tube 2 side of the transition tube 4, the flow velocity of air supplied to the inner tube 2 through the annular passage on the outer periphery of the transition tube can be increased. Cooling is strengthened on the inner cylinder side of the transition cylinder 4, which is covered with. Furthermore, by providing the guide wall 5, the air flow around the transition piece 4 that is not covered by the guide wall 5 is also affected, and the air flow velocity near the transition piece 4 tends to increase, so the heat transfer coefficient increases.

In the present invention, since the partition wall 14 is provided on the turbine stationary blade 6 side of the transition piece 4 so that heat is easily transferred from the transition piece 4 to the cover plate 13, the heat on the outer periphery of the cover plate 13 due to the provision of the guide wall 5 is An increase in the transmission rate improves the cooling performance of the transition piece 4. Furthermore, by providing the partition wall 4 that transmits heat from the transition piece 4 to the cover plate 13, the temperature of the cover plate 3 approaches the temperature of the transition piece 4, reducing thermal stress due to the difference in thermal expansion. The possibility of deformation or damage to the transition piece 4 due to deformation or damage to the cover plate 13 is reduced.

The impingement cooling unit can be manufactured by forming an air passage 1-1 in the transition piece 4 and fixing the cover plate 13 thereon, as shown in FIG. There is a method of fixing the processed cover plate]-3 to the transition piece 4, and there is also a method of inserting a plate-shaped partition wall 14 between the transition piece 4 and the cover plate 13 and fixing them.

Although it is possible to provide two or more rows of air holes 8 for one air passage 1 in Fig. 2, the temperature difference between the cover plate 3 and the transition piece 4 will become large, and the air The reliability of the impingement cooling unit tends to be lower than when the holes 8 are arranged in one row.

〔Effect of the invention〕

According to the present invention, it is possible to reduce the thermal stress of the impingement cooling section and lower the temperature of the wall surface of the transition piece, thereby increasing the reliability of the transition piece and extending its life.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the transition piece of an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line n--n in FIG. 1, and FIG. Example, FIG. 4 is a sectional view of the tail tube part of the conventional example,
FIG. 5 is a flow direction distribution diagram of the transition pipe gas passage area, and FIG. 6 is a flow direction distribution diagram of the transition pipe gas side heat transfer coefficient. 2. Inner tube, 4. Tail tube, 5. Guide wall, 8. Air hole, 11
・Air passage, 12・Air hole, 13 Cover plate, 14-
...partition wall.

Claims (1)

[Claims] 1. Air pressurized by a compressor and fuel pressurized by a separate system are introduced into the inner cylinder of the combustor, and combustion proceeds in the inner cylinder of the combustor. In a gas turbine that derives output by guiding combustion gas to a turbine through a transition piece, a plurality of air passages are formed inside a wall surface of at least a portion of the transition piece near the turbine, so that air from the outer periphery of the outer cylinder is A group of air holes for collision cooling by air and a group of air holes connecting the air passage and the inside of the transition piece are provided, and a portion of the transition piece near the inner cylinder is provided with a hole from an outer peripheral wall of the transition piece. A gas turbine combustor tail pipe cooling structure characterized in that a guide wall is provided at intervals to form an annular passage, and the entire amount or a part of the air supplied to the inner cylinder flows through the annular passage. . 2. The gas turbine combustor transition piece cooling structure according to claim 1, wherein a row of impingement cooling air holes is provided for one air passage inside the transition piece wall surface. Cooling structure of combustor transition piece.