JPS62197645A - Gas turbine combustor - Google Patents

Abstract

PURPOSE:To reduce thermal stresses due to temperature difference between a tail cylinder and an impinge cover by fixing the impinge cover on the outside of the tail cylinder of a combustor, forming corrugated grooves in the axial direction of the cover, and forming a bent hem at the fixed part. CONSTITUTION:An impinge cover 11 provided with a number of cooling air inlet holes 12 for cooling a tail cylinder 5 of a combustor is arranged with a specified gap on the outside of the tail cylinder. While the cooling air enters the inside of the impinge cover 11 via the inlet holes 12 and flows out of through holes 13 arranged on the most downstream side of the tail cylinder 5 of the combustor, at this time a great temperature difference is produced between both of the parts 5 and 11. To cope with this, corrugated grooves 14 are formed on the impinge cover 11 to absorb circumferential expansion. Projections 15 are also formed on the impinge cover 11 to keep the gap between the parts 5 and 11 constant. The difference in thermal elongations between both of the parts 5 and 11 is absorbed by deformations of bent lines 16 and 17 formed on both hems of the impinge cover 11.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a combustor transition piece having an impingement cover,
The structure of the impingement cover reduces thermal stress caused by the temperature difference between the transition piece and the impingement cover, and prevents deformation caused by the difference in thermal expansion. Regarding highly reliable impingement cover of combustor transition piece.

[Conventional technology]

The structure of the impingement cover adopted for the purpose of cooling the conventional gas turbine combustor transition piece is disclosed in Japanese Patent Publication No. 54-11.
As described in Publication No. 443, the part of the transition piece that is most difficult to cool due to the structure inside the combustor chamber is made of a thin steel plate with a certain gap between it and the wall surface of the transition piece, and the entire circumference is made of a thin steel plate. It had a fixed structure.

Because high-temperature gas from the combustor liner flows inside the combustor transition piece, the transition piece wall temperature becomes over 700C.

On the other hand, the impingement cover has a metal temperature of around 400C due to the flow of air discharged from the compressor. Because the combustor transition piece and impingement cover are connected together, the above temperature difference is caused by thermal stress between the transition piece and impingement cover,
Or, it often occurs as a result of deformation due to differences in thermal expansion. The above-mentioned known examples did not give sufficient consideration to this aspect.

[Problem that the invention seeks to solve]

The impingement cover provided for cooling the combustor transition tube has a shape that has a certain gap with the outer wall of the first transition tube, and has numerous inlet holes on the entire surface to match the cooling efficiency of the first transition tube. The structure allows cooling air to pass through. This cooling air collides with the transition piece or cools the transition piece by convection, and flows into the high-temperature gas passage through a through hole provided on the downstream side of the transition piece.

The impingement cover in the above-mentioned prior art is fixed to the entire circumference by welding or other methods while maintaining a certain gap from the one tail tube.

During operation of the gas turbine, the combustor transition piece is exposed to a wall temperature of 700C or more due to the flow of high-temperature gas from the combustion chamber inside, and the impingement cover is affected by the flow of discharge air from the compressor. The wall temperature will be around 400C, and there will be a large temperature difference between the transition piece and the impingement cover. This large temperature difference causes large thermal stress or thermal deformation in the transition piece and impingement cover. This large thermal stress leads to failure of the invincible capper connection with the transition piece.

In order to maintain the wall temperature of the transition piece below an allowable value, it is necessary to keep the gap between the transition piece and the impingement cover constant at all times. In conventional technology, this thermal deformation causes the gap between the transition piece and the impingement cover to fluctuate, which also affects the cooling efficiency of the impingement cover, making it highly likely that the wall temperature of the transition piece cannot be kept below the allowable value. .

The purpose of the present invention is to provide appropriate flexibility to the impingement cover side so that the difference in thermal expansion caused by the temperature difference between the transition piece and the impingement cover can be absorbed in all directions, and to provide a structure between the transition piece and the impingement cover. By providing an appropriate protrusion shape on the impingement cover side so that the gap can always be kept constant,
The objective is to reduce thermal stress during operation and to maintain a constant gap between the transition piece and the impingement cover.

[Means for solving problems]

The impingement cover used to cool the combustor transition piece needs to have the most efficient cooling structure with the minimum required air flow rate in terms of overall efficiency of the gas turbine. Therefore, it is necessary to reduce wasted cooling air that does not contribute to cooling the transition piece, and to maintain a constant gap between the transition piece and the impingement cover.

In order to reduce wasted cooling air and create a highly reliable mounting structure, the impingement cover should be tightly attached by welding or other methods over its entire circumference. During operation, a temperature difference of 3500 to 400 C occurs between the transition piece and the impingement cover, and this temperature difference is caused by an increase in thermal stress near the transition piece and the impingement cover fixing part, and thermal deformation of other parts. . In the known example, a method is used in which a bent edge is provided around the impingement cover and fixed to the transition piece. In this method, the difference in thermal expansion in the axial direction of the transition tube can be absorbed by the deformation of the bent edge of the impingement cover, but the difference in thermal expansion in the circumferential direction of the transition tube cannot be absorbed. This will generate large thermal stress.

The present invention is characterized in that wavy shapes with appropriate R shapes are provided at appropriate intervals so as to absorb the thermal expansion difference in the circumferential direction of the transition piece over the entire range. This wavy shape allows the impingement cover to have a deformation amount that can follow the thermal expansion of the transition piece due to the spring effect of the wavy R shape.

Further, this wavy shape is highly effective in increasing the rigidity of the impingement cover and preventing distortion caused by thermal deformation.

In the known example, since the intermediate portion other than the all-around fixed portion does not follow the thermal expansion of the transition piece, the gap between the transition piece and the impingement cover becomes smaller during operation. As a result, the impingement efficiency fluctuates, making it difficult to maintain the wall temperature of the transition tube within a set value, and the temperature of the transition tube also varies from place to place.

In the present invention, in order to maintain a constant 13 tl between the outer wall surface of the transition tube and the impingement cover even during operation, a protrusion that contacts the transition tube on the impingement cover side is installed in an appropriate manner that does not obstruct the flow of cooling air. It has all the features that are provided at intervals.

[Effect]

In the impingement cover structure used for the combustor transition piece, the wave-shaped groove provided in the axial direction absorbs the difference in thermal expansion in the perpendicular direction (the expansion of the transition piece is wider than that of the impingement cover), and the deformation of the groove shape. The projections provided on the impingement cover prevent large thermal stress from occurring on the impingement cover even when the structure maintains a constant 1 tl between the transition piece and the impingement cover. □1.゛1 Shikiru.

〔Example〕

Below is an example of the present invention! This will be explained using diagram s1.

The combustor chamber of the gas turbine consists of a discharge casing 1°, a turbine shell 2. Fuel nozzle 3. It is composed of an end cover 4, a combustor transition piece 52, a transition piece flow sleeve 6, a combustor liner 7, and a combustor liner flow sleeve 8.

The discharge air from the compressor 9 passes between the transition piece flow sleeve 6 and the combustor transition piece 5, and further flows into the combustor liner 7 using the combustor liner 70-sleeve 8 as a guide. The fuel from the fuel nozzle 3 is combusted in the combustor liner 7, and passes through the combustor transition piece 5 in the state of high temperature and high pressure gas.
It is guided to the turbine 10. Since high-temperature gas flows through the combustor transition piece, what is the allowable temperature of the heat-resistant alloy that can be used at this time? You will end up exceeding it. This trend is particularly noticeable as high temperature heating is promoted to improve the efficiency of today's high-efficiency or combined coil coils. In order to keep the temperature of the combustor transition piece below an allowable temperature, a method of cooling the combustor transition piece using air discharged from a compressor is generally used. Particularly in high-temperature gas turbines, a system using a transition piece flow sleeve 6 shown in FIG. 1 is also widely used. Furthermore, the structure of the transition piece flow sleeve 6 cannot be used, and the combustor transition piece 5 requires highly efficient cooling.
Near the rear end, one type of impingement cover is used.

Details of part A in FIG. 1 are shown in FIG. 2. In Fig. 2, there is a wadding cover 1 around the entire rear end of the combustor transition piece 5, and an impingement cover 1
1 is attached at a constant distance from the combustor transition piece 5.

Referring to FIG. 3, a cooling structure using one type of impingement cover will be explained.

Impingement cover 1 attached to the outside of the combustor transition piece 5
1 has a fine inlet hole 12 for cooling the tail cylinder on the entire surface.
will be provided. Due to the pressure difference between the inside and outside of the combustor transition pipe through this inlet hole 12, discharge air from the compressor flows in, collides with the combustor transition pipe 5 surface, and then...

nothing. Therefore, the metal temperature of the combustor transition piece 5 becomes 7000 or more, and the impingement cover 11 becomes about υ400C because it is exposed to the cooling air, and a large temperature difference occurs between the two.

FIG. 4 shows a view seen from direction B in FIG. 2. In FIG. 4, a corrugated groove 14 and a protrusion 15 installed on the impingement cover 11 are shown. The wavy grooves 14 and the protrusions 15 are of appropriate size and spacing.

The difference in thermal expansion between the combustor transition piece 5 and the impingement cover 11 during operation is absorbed in the axial direction by deformation of the bent edges 16 and 17 provided at both ends. The circumferential direction is absorbed by the deformation of the wave-shaped grooves 14 provided in the axial direction. In FIGS. 5 to 7, the protrusion 15 provided on the impingement cover 11 is
The structure is such that the flow of cooling air between the impingement cover 11 and the combustor transition piece 5 is not obstructed, and the impingement cover 11 is in contact with the combustor transition piece 5.

Since the thermal expansion of the combustor transition piece 5 is always larger than that of the impingement cover, the function of the protrusion 15 makes it possible to always maintain a constant gap between the impingement cover 11 and the combustor transition piece.

〔Effect of the invention〕

According to the present invention, in an impingement cover that is attached to a combustor transition piece for the purpose of cooling, thermal stress due to a temperature difference that occurs between the transition piece and the impingement cover can be reduced, and in addition, the gap between the transition piece and the impingement cover can be reduced. By being able to maintain constant impingement at all times, a stable impingement cooling effect can be expected and a highly reliable gas turbine combustor can be provided.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the gas turbine combustor, Figure 2 is a detailed view of part A in Figure 1, Figure 3 is a detailed view of the impingement cover, and Figure 4 is a detailed view of the impingement cover.
The figure is a view taken along arrow B in Fig. 2, Fig. 5 is a sectional view taken along line C-C in Fig. 4, Fig. 6 is a sectional view taken along line D-D in Fig. 4, and Fig. 7 is a sectional view taken along line E in Fig. 4.
-E sectional view. l...Discharge casing, 2...Turbine shell, 3
... Fuel nozzle, 4... End cover, 5... Combustor transition piece, 6... Transition piece flow sleeve, 7... Combustor liner, end... Combustor liner flow sleeve, 9
... Compressor, 10... Turbine, 11... Impingement cover, 12... Inlet hole, 13... Through hole, 1
4... Wave-shaped groove, 15 protrusions.

Claims (1)

[Claims] 1. In a gas turbine in which an impingement cover is provided on the outside of the combustor transition piece in order to cool the combustor transition piece, the entire circumference of the impingement cover is fixed to the transition piece, and the transition piece and the impingement cover are 2. A gas turbine combustor, wherein the fixed portion is provided with a bent edge, and the impingement cover is provided with a corrugated groove at intervals in the axial direction, in order to reduce thermal stress caused by a temperature difference. 2. Claim 1 is characterized in that the impingement cover is provided with protrusions that contact the transition piece at appropriate intervals so that the gap between the transition piece and the impingement cover can be maintained constant. gas turbine combustor.