JPH0726734B2 - Gas turbine combustor - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a gas turbine combustor used in a gas turbine power plant, and more particularly to improvement of a cooling structure of a combustor transition piece.

[Technical background of the invention and its problems]

A gas turbine power plant guides discharge air compressed by driving a compressor provided coaxially with a gas turbine to a gas turbine combustor as combustion air, burns it with fuel in the combustor, and burns the combustion gas. The internal cylinder guides the gas turbine to drive the gas turbine for work.

FIG. 3 shows a general configuration example of a conventional gas turbine combustor. That is, a plurality of gas turbine combustors 1 are provided between the compressor 2 and the gas turbine 3 and are provided around the axis, and are housed in the discharge chamber 4 for the combustion air discharged from the compressor 2. There is. The gas turbine combustor 1 includes an outer cylinder 5 and an inner cylinder 6, and an annular combustion air flow path 7 is formed between the outer cylinder 5 and the inner cylinder 6, while a combustion chamber 8 is defined inside the inner cylinder 6 and the combustion is performed. The fuel is mixed with the combustion air in the chamber 8 and burned. Combustion gas is the inner cylinder 6
The gas turbine 3 is driven by being guided to the inlet of the gas turbine 3 through the inside of the transition piece 9 connected to the rear end of the gas turbine 3.

The transition piece 9 of the gas turbine combustor 1 described above has a generally single-layered structure in the past, and its tip end is fitted to the rear end of the inner cylinder 6 and elastically held by a leaf spring or the like. This tail cylinder 9
It is heated from the inside by the flow of high-temperature combustion gas, but is convectively cooled by the contact with the combustion air supplied from the compressor 2 to the discharge chamber 4.

By the way, in recent years, further improvement in combustion efficiency has been desired from the viewpoint of energy saving, and accordingly, the combustion temperature of the gas turbine combustor has become higher. In this case, the conventional single-structured transition piece 9 for convection cooling does not always provide sufficient cooling. For example, in the case of a high temperature gas turbine combustor of 1300 ° C. or higher, the transition piece exposed to high temperature combustion gas is used. 9
There is a risk that the temperature will exceed the technically compatible temperature of the transition piece material (about 800 ° C), which will reduce the durability and reliability of the gas turbine combustor.

For this reason, studies are underway to improve the cooling performance of the transition piece,
For example, a technology to enhance heat transfer with air by providing a cooling air guide plate on the outer peripheral side of the portion of the transition piece where the temperature tends to be high, and an annular steam flow on the outer peripheral side of the transition piece. Techniques and the like have been proposed so far in which passages are provided and effective cooling is performed with steam having a high specific heat.

However, in the above technique of providing a plate for the cooling air guide, the flow of air becomes uneven depending on the shape of the transition piece, or an air layer of a constant thickness is formed along the outer peripheral surface of the transition piece, and the boundary layer Since the air outside of does not contribute much to the heat transfer for cooling, it is not always possible to obtain a sufficient effect on the transition piece cooling of the high temperature gas turbine combustor of 1300 ° C or higher,
Further, in the case where steam is used as the cooling medium, there is a problem that a special supply structure for supplying steam is required and the structure becomes complicated.

[Object of the Invention]

The present invention has been made in consideration of the above-mentioned circumstances, and greatly improves the cooling performance of the combustor transition piece under a relatively simple configuration in which the discharge air of the compressor is used as cooling air. In particular, it can maintain sufficient durability and reliability when applied to high-temperature gas turbines, which can further improve combustion efficiency and, in turn, effectively reduce energy consumption. The purpose is to provide a container.

[Outline of Invention]

In order to achieve the above-mentioned object, the present invention forms a combustion air flow path between an outer cylinder of a liner and an inner cylinder of a liner, defines a combustion chamber in the inner cylinder of the liner, and guides combustion gas. In a gas turbine combustor in which a transition piece is provided in the liner inner tube, the transition piece is housed in a discharge chamber of combustion air discharged from a compressor, and the transition piece is formed of an outer piece of the tail piece and an inner piece of the tail piece. With a heavy structure, the annular portion is used as a cooling flow path communicating with the combustion air flow path, and a large number of cooling air holes are formed in the transition piece outer cylinder to enable impingement cooling of the transition piece inner cylinder. It is a thing.

Example of Invention

An embodiment of the gas turbine combustor according to the present invention will be described below with reference to FIGS. 1 and 2.

The gas turbine combustor 10 according to this embodiment is provided between a compressor 11 and a gas turbine 13 that drives a generator 12, and is housed in a chamber casing (not shown) that defines a discharge chamber 14 from the compressor 11. . The chamber casing integrally connects the compressor 11 and the casings of the gas turbine 13, and a plurality of gas turbine combustors 10, for example, 10 or 14 are arranged in the chamber casing in the circumferential direction.

Each gas turbine combustor 10 is formed in a double cylinder structure from a liner outer cylinder 15 and an inner cylinder 16 that form a combustor body, and its annular space is defined as a combustion air flow path 17. A combustion chamber 18 is defined in the liner inner cylinder 16, and fuel and combustion air are supplied into the combustion chamber 18 for combustion.

On the other hand, a transition piece 20 is attached to the rear end portion of the inner cylinder of the gas turbine combustor 10. The tail cylinder 20 has a tail cylinder inner cylinder 21 and a tail cylinder outer cylinder 22, and an annular space therebetween is defined as a cooling flow path 23.
A plurality of cooling fins 24 also functioning as reinforcement in the cooling flow path 23.
Are arranged in a radial pattern to increase the heat transfer area (heat exchange area) in the cooling flow path 23 and promote heat dissipation. The tail cylinder inner cylinder 21 is loosely fitted to the rear end of the liner inner cylinder 18 of the combustor body, and elastically held by a leaf spring or the like. The inside of the transition piece 21 is a gas turbine for the combustion gas burned in the combustion chamber 18.
It is formed as a guideway 25 leading to the entrance of 13.

The tail end side of the cooling passage 23 formed in the transition piece 20 is formed as an inlet 23a, the outlet 23b on the front end side of the cooling passage 23 communicates with the combustion air passage 17, and the inside of the transition piece inner tube 21 The cooling discharge air that has undergone heat exchange with the passing combustion gas is guided to the fuel air flow path 17.

Further, as shown in FIG. 1, a large number of small-diameter cooling air holes 27 are formed in the transition piece outer cylinder 22 in a plurality of rows or randomly in the circumferential direction, for cooling the outer periphery of the transition piece outer tube 22. Air is introduced into the cooling flow path 23 through the cooling air holes 27 and collides (impingement) on the surface of the tail cylinder inner cylinder 21. With the formation of such a large number of cooling air holes 27,
Since the amount of cooling air flowing into the cooling flow path 23 gradually increases on the downstream side in the axial direction, the cross-sectional area of the cooling flow path 23 is based on the calculation of the cooling performance of the combustor and is smaller than that on the inlet 23a (rear end) side. 23b
It is set to be larger on the (front end) side.

Next, the operation of the gas turbine combustor 10 will be described.

High-pressure discharge air compressed by driving the compressor 11 of the gas turbine power plant is discharged into the discharge chamber 14,
A part of the discharge chamber 14 is guided to the cooling flow path 23, and the rest is guided to the combustion air flow path 17. The air guided to the combustion air flow path 17 is then guided to the combustion chamber 18 in the liner inner cylinder 16, mixed with the fuel separately guided to the combustion chamber 18 and used for combustion, and the high temperature combustion gas Becomes The combustion gas passes through the guide passage 25 formed in the inner cylinder 21 of the transition piece and the gas turbine 13
Be led to. As the combustion gas passes through the gas turbine 13, it expands and does work, driving the generator 12 to rotate. The combustion gas that has worked in the gas turbine 13 is exhausted.

In this case, the inner cylinder 21 of the transition piece is heated by the passage of high-temperature combustion gas, but the high-speed air flow in the cooling flow path 23 formed between the outer tube 22 and the transition piece outer tube 22 provided on the outer peripheral side thereof, Further, the impingement cooling by the introduced air from the cooling air holes 27 formed in the transition piece outer cylinder 22 provides extremely effective cooling.

That is, the air in the discharge chamber 14 flows into the cooling flow passage 23 from the inlet 23a on the rear end side of the transition piece outer cylinder 22 as the first path, and flows in the cooling flow passage 23 along the axial direction. And is guided to the combustion air flow path 17 from the outlet 23b on the front end side. At this time, since the cooling flow passage 23 is a narrow annular space, the cooling air is accelerated in the cooling flow passage 23, and the flow velocity is, for example, about 10
It increases from m / sec to about 40 m / sec. As a result of this high-speed airflow contacting the surface of the tail cylinder inner cylinder 21 and efficient counter-current cooling, the heat dissipation efficiency of the tail cylinder inner cylinder 21 is improved, and the heat transfer of the tail cylinder inner cylinder 21 is also improved. And actively cooled.

On the other hand, the air in the discharge chamber 14 serves as a second path from a large number of cooling air holes 27 radially formed in the tail cylinder outer cylinder 22 over a wide range into the cooling flow path 23 in the radial direction. It is introduced in a spotwise manner. Since each cooling air hole 27 has a small diameter, the air introduced from the cooling air hole 27 becomes a high-speed jet, and a cooling air layer in the axial direction from the inlet 23a side to the outlet 23b side is bored in the cooling flow path 23 to form a tail tube inside. It impinges on the surface of the cylinder 21 at a high speed (impingement), whereby so-called impingement cooling is performed.

According to this impingement cooling, the air in the low temperature state inside the discharge chamber 14 directly collides with the surface of the tail cylinder inner cylinder 21 at all positions in the axial direction of the tail cylinder 20, so that it extends from the upstream side to the downstream side. A large heat dissipation effect can be obtained with a very good heat transfer coefficient in a wide area. Therefore, only in the cooling path along the first axial direction, depending on the shape of the transition piece, the air flow becomes non-uniform and the heat dissipation efficiency is lowered, or the air becomes a constant laminar flow state in the axial direction. Since it flows, there is a possibility that the heat transfer coefficient will gradually decrease on the downstream side. However, these points are sufficiently overcome, and an excellent transition cylinder cooling effect is achieved.

As a result, the gas turbine combustor 10 is applied to a high temperature gas turbine, for example, even if the combustion temperature is 1300 ° C. or higher, the temperature of the tail cylinder inner cylinder 21 can sufficiently withstand the existing combustion material, for example, about The temperature can be lowered to 700 ° C or lower, which makes it possible to effectively improve the combustion efficiency and to effectively save energy. Moreover, unlike steam cooling, etc., the cooling performance of the combustor transition piece can be significantly improved under the relatively simple structure in which the discharge air of the compressor is used as cooling air. In addition, many excellent advantages can be obtained in terms of practical use such as simplification and economic efficiency.

By the use of the above impingement cooling, the amount of air supplied to the cooling passage 23 of the transition piece 20 gradually increases on the downstream side,
In this embodiment, since the cross-sectional area of the cooling flow passage 23 is set to be larger on the outlet 23b (front end) side than on the inlet 23a (rear end) side, the air flow in the cooling flow passage 23 is always smooth. You can do it.

Further, in this embodiment, as shown in FIG.
Since the cooling fins 24 are provided in the rear fin 20 to increase the heat transfer area of the transition piece 20, the heat radiation efficiency of the surface of the transition piece inner cylinder 21 can be further improved.

In the above examples, the liner outer cylinder is extended to the tail cylinder side, the tail cylinder outer cylinder is inserted into the liner outer cylinder, and the overlapping portion is formed. An axial gap may be formed between the outer cylinder and the outer cylinder, or the tail cylinder outer cylinder may be integrally or integrally connected to the liner outer cylinder.

〔The invention's effect〕

As described above in detail, according to the gas turbine combustor of the present invention, the transition piece has a double structure including the transition piece outer cylinder and the transition piece inner cylinder, and the annular portion of the transition piece has a combustion air passage. By using a cooling flow path that communicates with the cooling air flow path, the cooling air is accelerated in the cooling flow path to increase the flow velocity to efficiently perform convective cooling on the surface of the tail cylinder inner cylinder, and improve the heat dissipation efficiency of the tail cylinder inner cylinder. Improved and effective cooling with good heat transfer. In addition, by providing a large number of cooling air holes in the outer cylinder of the transition piece to allow impingement cooling of the inner tube of the transition piece, the cold air in the discharge chamber can be directly fed at all axial positions of the transition piece. By colliding with the surface of the inner cylinder of the transition piece, it is possible to obtain a large heat dissipation effect with an extremely good heat transfer coefficient in a wide region from the upstream side to the downstream side.
This makes it possible to sufficiently supplement the decrease in heat transfer on the downstream side in the above-mentioned double structure.

Therefore, according to the present invention, even if the gas turbine combustor is applied to a high-temperature gas turbine, the temperature of the inner cylinder of the transition piece can be lowered to a temperature that can sufficiently withstand the existing combustion material. It is possible to ensure high durability and reliability, further improve combustion efficiency, and effectively achieve energy saving. Moreover, unlike steam cooling, etc., the cooling performance of the combustor transition piece can be significantly improved under the relatively simple structure in which the discharge air of the compressor is used as cooling air. There are many practical advantages such as simplification and economic efficiency.

When the cooling fins are provided in the cooling passage, the heat transfer area of the transition piece can be increased, and the heat radiation efficiency of the surface of the transition piece inner cylinder can be further improved.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a transition piece structure showing an embodiment of a gas turbine combustor according to the present invention, and FIG. 2 is II-II of FIG.
FIG. 3 is a diagram along a line, and FIG. 3 is a diagram showing a gas turbine combustor attached to a gas turbine. 10 …… Gas turbine combustor, 11 …… Compressor, 13 …… Gas turbine, 15 …… Liner outer cylinder, 16 …… Liner inner cylinder,
17: Combustion air flow path, 18: Combustion chamber, 20: Tail tube, 21
...... Tail tube inner tube, 22 ...... Tail tube outer tube, 23 ...... Cooling channel, 23a
...... Cooling channel inlet, 23b …… Cooling channel outlet, 24 ……
Cooling fins, 25 ... Combustion gas guideways, 27 ... Cooling air holes.

Claims (2)

[Claims] 1. A liner outer cylinder and a liner inner cylinder are formed to form a combustion air flow path, a combustion chamber is defined in the inner liner cylinder, and a tail cylinder for guiding combustion gas is formed in the liner inner cylinder. In the gas turbine combustor provided in, the tail cylinder is housed in the discharge chamber of the combustion air discharged from the compressor, and the tail cylinder outer cylinder and the tail cylinder inner cylinder constitute a double structure, A gas turbine characterized in that the annular portion is used as a cooling passage communicating with the combustion air passage, and a large number of cooling air holes are formed in the outer cylinder of the tail cylinder to allow impingement cooling of the inner cylinder of the tail cylinder. Combustor. 2. The gas turbine combustor according to claim 1, wherein a plurality of cooling fins are radially arranged in a cooling passage formed by an outer cylinder of the tail cylinder and an inner cylinder of the tail cylinder.