JP2001342807A - Back plate structure of gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a back plate structure capable of preventing lowering of turbine output due to thermal expansion and being formed simply. SOLUTION: In a gas turbine for discharging a combustion gas from a nozzle to drive a turbine, the nozzle is provided with an annular nozzle mounting flange, the nozzle mounting flange is fixed to a housing, a gap is provided between the inner peripheral end part of the nozzle mounting flange and the housing to form an annular groove, the outer peripheral end part of the back plate forming a wall surface partitioning a combustion gas passage in the annular groove part is clamped to be slidable in the radial direction and to be immobile in the axial direction of the turbine shaft, whereby when the back plate is expanded due to thermal transfer from the combustion gas, the back plate can be expanded outwardly in the radial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a back plate provided at a nozzle portion of a gas turbine.

[0002]

2. Description of the Related Art FIG. 4 is a schematic sectional view of a back plate structure 90 of a conventional gas turbine. As shown in FIG. 4, in a conventional gas turbine, a nozzle 91 for discharging combustion gas to a back plate structure 90 fixed to a housing 94 is provided.
The back plate structure 90 forms a wall surface that partitions a passage of the combustion gas.

[0003]

When the back plate structure 90 thermally expands due to heat transfer from the combustion gas, the nozzle 9
The position of 1 fluctuates. When the position of the nozzle 91 fluctuates, the position of the nozzle shroud 97 integrated with the nozzle 91 with respect to the turbine 92 fluctuates. When a predetermined clearance (about 1 mm) between the nozzle shroud 97 and the turbine 92 fluctuates, the turbine output is reduced. It causes a decline.

Therefore, conventionally, in order to avoid this, the elastic member 93 absorbs the distortion due to thermal expansion, and the housing 9
4, a complicated structure in which the rigid member 96 is fixed with bolts 95 or the like, which requires a lot of labor and cost in manufacturing, has been adopted. Accordingly, an object of the present invention is to provide a back plate structure that can avoid a decrease in turbine output due to thermal expansion and that can be easily formed.

[0005]

According to a first aspect of the present invention, there is provided a gas turbine for driving a turbine by discharging combustion gas from a nozzle, wherein the nozzle is provided with an annular nozzle mounting flange. A back plate that fixes a nozzle mounting flange to a housing, forms an annular groove by providing a gap between an inner peripheral end of the nozzle mounting flange and the housing, and forms a wall surface that partitions a combustion gas passage at the annular groove portion. Of the turbine shaft is slidable in the radial direction and immovable in the axial direction of the turbine shaft. When the back plate expands due to heat transfer from the combustion gas, the back plate is moved outward in the radial direction. Swellable.

According to a second aspect of the present invention, in the first aspect of the invention, the back plate is formed of a sheet metal.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the inner peripheral end of the back plate is slidable in the radial direction with respect to the housing, and is axially movable with respect to the turbine shaft. Support for immobility.

[0008]

FIG. 1 is a schematic cross-sectional view of a back plate structure 100 according to the first and second aspects of the present invention. In the backplate structure 100 shown in FIG. 1, a turbine 3 having turbine blades 4 is supported by a bearing (not shown) with respect to a housing 5.

The annular nozzle mounting flange 8 fixed to the nozzle 2 is fixed with bolts and nuts (not shown) at equal intervals on the circumference of an annular fixing flange 16 and an annular fixing member 17 of the housing 5. As a result, it is fixed to the housing 5.

A nozzle shroud 6 is fixed to the nozzle 2, the nozzle shroud 6 forms a wall surface that partitions a passage of the combustion gas, and a predetermined clearance (between the nozzle shroud 6 and the turbine blade 4). For example, 0.5
１．０1.0 mm).

An annular groove 10 is formed between the housing 5 and the nozzle mounting flange 8. The annular groove 10 has an outer peripheral end 1a of the back plate 1 integrally formed in an annular shape.
The outer peripheral end 1 a of the back plate 1 is sandwiched between the housing 5 and the nozzle mounting flange 8. The inner peripheral end 1 b of the back plate 1 is fixed to the housing 5 with bolts 7. The housing 5 is provided with screw holes 5a for screwing the bolts 7 at equal intervals at a plurality of positions (for example, eight positions) in the circumferential direction. In the annular groove 10 in which the outer peripheral end 1a of the back plate 1 is inserted, a gap 11 is formed radially outward from the back plate 1.

Since the annular back plate 1 has the outer peripheral end 1a and the inner peripheral end 1b fixed as described above,
Although it cannot move in the axial direction of the rotating shaft 9 of the turbine 3,
When heat is transferred from the combustion gas and thermally expanded, the gap 11 is formed radially outward, so that the gap 11 can slide with respect to the housing 5 and the nozzle mounting flange 8.

The back plate 1 can be formed by pressing one sheet metal. Moreover, you may manufacture by die casting.

FIG. 3 is a schematic partial sectional view of the back plate structure 110 according to the first embodiment of the present invention. The back plate structure 110 of FIG.
The difference from 0 is that the back plate 1 includes an outer part 12 and an inner part 13. Outer part 1
2 is sandwiched between the housing 5 and the nozzle mounting flange 8 similarly to the outer peripheral end 1a of the back plate 1 shown in FIG.

The inner peripheral end 13a of the inner portion 13
Is fixed to the housing 5 with bolts 7. The outer portion 12 and the inner portion 13 are integrally fixed by welding. The back plate 1 may be configured by integrally fixing the outer portion 12 and the inner portion 13 as described above.

The inner peripheral end of the inner portion 13 in FIG. 3 may be sandwiched between the holding member 14 and the housing 5 like the inner peripheral end 1b of the back plate 1 in FIG.

FIG. 2 is a schematic sectional view of a back plate structure 120 according to the third aspect of the present invention. The back plate structure 120 of FIG. 2 differs from the back plate structure 100 of FIG. 1 in the manner of fixing the inner peripheral end 1b of the back plate 1, and there is no other difference from the back plate structure 100 of FIG. .

As shown in FIG. 2, the bolt 7 is screwed into a screw hole 5a (only one is shown in FIG. 2) of the housing 5 arranged at equal intervals on the circumference so that the annular holding member 14 5 is fixed.

An annular groove 15 is formed between the holding member 14 and the housing 5. The inner peripheral end 1b of the back plate 1 is inserted into the annular groove 15, and the inner peripheral end 1b
Is held between the housing 5 and the holding member 14.
Therefore, both the outer end 1a and the inner end 1b of the back plate 1 can slide in the radial direction, but cannot move in the axial direction of the rotating shaft 9.

As described above, the outer peripheral end 1 of the back plate 1
When the inner peripheral end 1b is slidable in the radial direction with respect to the housing 5 in addition to a, the back plate 1 is thermally expanded and deformed, the passage of the combustion gas is widened, and the output of the turbine 3 is reduced. Can be avoided more reliably.

[0021]

According to the first aspect of the present invention, since the back plate 1 is sandwiched between the housing 5 and the nozzle 2 (nozzle mounting flange 8) and is slidable radially outward, heat from combustion gas is reduced. Even if the back plate 1 is transmitted and thermally expanded, the relative position of the nozzle 2 to the housing 5 does not change, and the clearance between the turbine blade 4 of the turbine 3 supported by the housing 5 and the nozzle shroud 6 does not change. Therefore, a decrease in the output of the turbine 3 can be avoided.

According to the second aspect of the present invention, since the back plate 1 is formed of a sheet metal, manufacturing is facilitated and cost can be reduced.

According to the third aspect of the present invention, in addition to the outer peripheral end 1a of the back plate 1, the inner peripheral end 1b is also provided in the housing 5.
Is slidable in the radial direction, the back plate 1 is thermally expanded and deformed, so that the passage of the combustion gas is widened and the output of the turbine 3 is reduced.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a back plate structure according to the invention of claim 1;

FIG. 2 is a schematic sectional view of a back plate structure according to the invention of claim 3;

FIG. 3 is a schematic sectional view showing another embodiment of the back plate structure according to the first embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a back plate structure of a conventional gas turbine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Back plate 2 Nozzle 3 Turbine 4 Turbine blade 5 Housing 6 Nozzle shroud 7 Bolt 8 Nozzle mounting flange 9 Rotating shaft 10 Annular groove 11 Gap 14 Clamping member 100 Back plate structure

Claims (3)

[Claims] 1. A gas turbine for driving a turbine by discharging combustion gas from a nozzle, wherein the nozzle is provided with an annular nozzle mounting flange, the nozzle mounting flange is fixed to a housing, and an inner peripheral end of the nozzle mounting flange is provided. An annular groove is formed by providing a gap between the section and the housing, and an outer peripheral end of a back plate that forms a wall surface that partitions a combustion gas passage at the annular groove portion is slidable in a radial direction and a turbine shaft. A back plate structure for a gas turbine, characterized in that the back plate is radially outwardly expandable when the back plate expands due to heat transfer from combustion gas. 2. The gas turbine back plate structure according to claim 1, wherein said back plate is formed of sheet metal. 3. The gas turbine according to claim 1, wherein an inner peripheral end of the back plate is supported so as to be slidable in the radial direction with respect to the housing and immovable in the axial direction of the turbine shaft. Back plate structure.