JPH10196404A - Device and method for adjusting clearance between moving blade and stationary blade for gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve efficiency of a gas turbine by reducing the radial clearance between a moving blade platform and a stationary blade inner shroud. SOLUTION: A first channel 9 is provided to supply bleed air from the interstage of a compressor to a second stage stationary blade 3 of a gas turbine, and a second channel 11 which supplies bleed air from a combustor chamber or the high pressure stage of a compressor merges into the first channel 9. An air cooler 10 and a control valve 12 are shown. When starting up the gas turbine or increasing its load, high-temperature air is introduced from the second channel 11, from either the combustor chamber or the compressor high pressure stage, so that the heat expansion speed of the second stage stationary blade 3 will increase and the clearance between moving and stationary blades is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for controlling the clearance between a moving blade and a stationary blade by controlling a cooling air temperature of the stationary blade during starting of a gas turbine.

[0002]

2. Description of the Related Art A high temperature portion of a gas turbine is cooled by cooling air. FIG. 5 shows a typical example of this, and the cooling air system is constituted by the following three systems.

(1) Compressor discharge air system The discharge air of the air compressor 21 is guided into the hollow first stage stationary blades 23 of the turbine 22, cools the stationary blades 23 and joins the main gas flow.

(2) Compressor intermediate-stage bleeding system The bleed air from the intermediate stage of the air compressor 21 is guided to hollow stationary blades 24, 25, and 26 of the second and subsequent stages of the turbine 22 corresponding to the pressure. After cooling 24, 25 and 26, they join the main gas stream.

(3) Extraction system of the combustor / compressor casing The high-pressure bleed air extracted from the combustor / compressor casing 27 flows into the turbine rotor via the air cooler 28, the air filter 29 and the shut-off valve 30, and flows into the turbine disk. After cooling the blade 31 and the bucket 32 (first and second stage buckets), they join the main gas flow.

[0006] Of the three systems described above, the air extracted from the compressor intermediate-stage extraction system of item (2) is provided as it is as cooling air. As described above, the first and second stage rotor blades 32 include:
High-temperature cooling air in the combustor / compressor compartment is supplied,
The second stage stationary blades 24 are supplied with cooling air of a compressor intermediate stage.

Therefore, the first and second stage blades 32 and the second stage stationary blade 2
In the case of No. 4, the thermal expansion speed difference is the largest, and there is a fear of contact at the time of start-up or at the time of increasing load.

[0008]

In order to prevent contact due to vibrations, shocks, and thermal expansion differences, including transitional states, the moving blades and the stationary blades of the gas turbine, that is, the rotor side and the stator side are radially interposed. Although there is a directional clearance, there is naturally a physical value there.

On the other hand, in gas turbines, it is desirable to make the clearance as small as possible, since reducing the amount of sealing air as much as possible leads to an improvement in turbine efficiency. However, there is a limit in reducing the clearance to satisfy these conflicting two.

In particular, when the turbine is started, the elongation due to the centrifugal load of the rotor increases and exceeds the amount of thermal elongation on the stationary side, so that the clearance is temporarily minimized. FIG. 6 shows this state.

SUMMARY OF THE INVENTION It is an object of the present invention to solve this problem and to reduce the radial clearance between the moving blade side, that is, the moving blade platform, and the stationary side, that is, the inner blade inner shroud, thereby improving the gas turbine efficiency. And

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises a first flow path for supplying bleed air from a compressor intermediate stage to a gas turbine vane, and a valve device for burning a gas turbine vane. A second flow path for supplying bleed air from an air conditioning room or a high pressure stage of a compressor, and a clearance adjusting device between a moving blade and a stationary blade of a gas turbine having a configuration in which a cooler is provided in at least the second flow path. I do.

According to the clearance adjusting device of the present invention, when the gas turbine is started or when the load is increased, the second
By supplying high-temperature air from the combustor casing or the compressor high-pressure stage through the flow passage, the temperature rise of the stationary blade can be accelerated, and the clearance between the gas turbine moving and stationary blades can be prevented from narrowing. The amount of hot air supplied from the combustor casing or the compressor high-pressure stage is adjusted by adjusting the valve device in the second flow path.

According to another aspect of the present invention, there is provided a first flow path for supplying bleed air from a compressor intermediate stage to a gas turbine vane, A second flow path for supplying bleed air from the combustor casing or the compressor high pressure stage to the blades, a valve device provided upstream of the junction of the second flow path with respect to the junction, and the junction And a cooling device provided between the moving blade and the stationary blade of the gas turbine.

According to this clearance adjusting device, when the gas turbine is started or when the load is increased, the amount of the cooling air in the combustor chamber adjusted by the valve device from the second flow passage to the stationary blade cooling air in the first flow passage. Alternatively, high-temperature air from the compressor high-pressure stage is mixed in, and the temperature rise of the stationary blade can be accelerated to prevent the clearance between the gas turbine moving and stationary blades from narrowing.

In the clearance adjusting device according to the present invention, it is preferable that the stationary blade for supplying the bleed air is a second stage stationary blade.

As described above, according to the present invention, the flow rate of the cooling medium supplied to the stationary blades at the time of starting up or increasing the load of the gas turbine is made smaller than the flow rate supplied at the time of steady operation, whereby the moving blades and the stationary blades of the gas turbine are provided. The clearance between the inner shroud of the second stage stationary blade and the blade platform can be adjusted.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a clearance adjusting device between a gas turbine moving blade and a stationary blade according to the present invention will be specifically described based on an illustrated embodiment.

(First Embodiment) First, a first embodiment shown in FIG. 1 will be described. In FIG. 1, reference numeral 1 denotes a first-stage moving blade, and 2 denotes a second-stage moving blade. 1st stage bucket 1 and 2nd stage
Between the stage moving blades 2, the second stage nozzle vane 3 is provided with a radial clearance C _1, C _2.

C ₁ is a gap between the outer diameter δ ₁ of the labyrinth receiver 4 of the moving blade disk and the inner diameter δ _{2 of the} labyrinth 6 fitted in the seal housing 5 of the second stage stationary blade 3. Also,
C ₂ is the outer diameter of the platform 7 of the moving blades 1 and 2 and the stationary blade 3
Of the inner shroud 8.

A second-stage stationary blade 3 is provided with a supply pipe for bleed air at an intermediate stage of the compressor to form a first flow path 9 according to the present invention. A cooler 10 is provided. In addition, a supply pipe for guiding bleed air from the vehicle compartment or the high pressure stage of the compressor is connected to the first flow path 9 to form the second flow path 11 according to the present invention. A control valve 12 is provided in the second flow path 11.

As described with reference to FIG. 5, in the gas turbine, the first and second stage moving blades are supplied with high-temperature cooling air of the combustor / compressor cabin. Also, for the second stage stationary blade,
Cooling air for the compressor middle stage is supplied.

Therefore, the first and second stage moving blades and the second stage stationary blade are
The difference in thermal expansion rate is the largest, and there is a fear of contact at the time of startup and at the time of load increase. This will be described with reference to FIG.
Since the seal housing 5 of the step stationary blade is cooled, the elongation due to heat is slower than that of the labyrinth receiver 4 of the moving blade disk, and the curve is as shown in FIG.

Therefore, the second stage stationary blades 3 are supplied by supplying high temperature air of the vehicle compartment or the high pressure extraction stage from the second passage 11 to the first passage 9 at the time of transition such as when the gas turbine is started or when the load is increased.
Is adjusted so as to heat the seal housing 5 quickly.

As a result, the seal housing 5 of the second stage stationary blade 3 has a curved line as shown in FIG. 2, and a clearance is provided by Δ compared to the case where no high-temperature air is introduced from the second flow path. Therefore, if smaller as the curve of narrowing only advance Δ a labyrinth gap C _1, start, while avoiding contact at the time of temperature load, clearance of the rotor blade platform 7 and stator inner shroud 8 in the steady state C ₂ can be kept small.

(Second Embodiment) Next, a second embodiment shown in FIG. 3 will be described. In the device shown in FIG.
A second flow path 11 that guides bleed air from the combustor casing or the compressor high-pressure stage to a first flow passage 9 that guides compressor middle-stage bleed air for cooling to the second stage stationary blade 3 is joined.

However, in the apparatus shown in FIG.
The control valve 13 is provided in the first flow path 9 upstream of the junction with the second flow path, and the second flow path is upstream of the junction with the first flow path 9.
A control valve 12 and a cooler 14 are provided in the flow path 11.
Other configurations are substantially the same as those of the first embodiment shown in FIG. 1, and corresponding portions are denoted by the same reference numerals as in FIG. 1, and redundant description thereof will be omitted.

As described above, the minimum clearance appears between the first and second stage moving blades and the second stage stationary blade when the gas turbine is started or when the load is increased, but in the apparatus shown in FIG. By narrowing the control valve 13 in the one flow path 9, the thermal expansion speed on the second stage stationary blade side can be increased, and the gas turbine can be started or the load can be increased while securing clearance.

When the temperature of the second stage vane reaches a temperature requiring cooling, the control valve 13 of the first flow path 9 is opened. The first in steady state
The control valve 13 of the flow path 9 is opened to reduce the thermal expansion of the second stage stationary blade. FIG. 4 shows a state of the clearance control between the first and second stage moving blades and the second stage stationary blade in the device according to the second embodiment.

[0030]

As described above, according to the present invention,
By providing a second flow passage for guiding the bleed air from the combustor casing or the high pressure stage of the compressor to the stationary blade, or by reducing the flow rate of the cooling medium supplied to the stationary blade at the time of starting the gas turbine or at the time of increasing the load, by reducing the flow rate from the steady state. The clearance between the moving blade and the stationary blade can be controlled to prevent the radial gap between the moving blade platform and the stationary blade inner shroud from decreasing. Accordingly, the amount of sealing air can be reduced, and accordingly, the efficiency of the gas turbine is improved.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a configuration of a clearance adjustment device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a change in clearance between gas turbine blades and blades by the apparatus of FIG. 1;

FIG. 3 is a system diagram showing a configuration of a clearance adjustment device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a change in clearance between the gas turbine moving and stationary blades by the apparatus of FIG. 3;

FIG. 5 is a system diagram of conventional cooling air in a gas turbine.

FIG. 6 is a diagram showing a change in clearance between moving and stationary blades in a gas turbine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 1st stage moving blade 2 2nd stage moving blade 3 2nd stage stationary blade 4 Labyrinth receiver of moving blade (rotor) disk 5 Seal housing of 2nd stage stationary blade 6 Labyrinth 7 Moving blade platform 8 Inner shroud of stationary blade 9 First flow Road 10,14 Cooler 11 Second flow path 12,13 Control valve

Claims (4)

[Claims] A first flow path for supplying bleed air from a compressor middle stage to a gas turbine vane; and a valve device for supplying bleed air from a combustor casing or a high-pressure compressor stage to the vane. A clearance adjusting device between a moving blade and a stationary blade of a gas turbine, wherein a cooling device is provided at least in the second flow channel. 2. A first passage for supplying bleed air from a compressor middle stage to a gas turbine vane, and a first passage merging with the first passage from a combustor casing or a compressor high pressure stage to the vane. A second flow path for supplying bleed air, a valve device provided at a point upstream of the junction of the second flow path, and cooling provided between the junction and the stationary vane. And a clearance adjusting device between a moving blade and a stationary blade of a gas turbine. 3. The clearance adjusting device according to claim 1, wherein a target to be supplied with the bleed air from the flow passage is a second stage stationary blade. 4. A method for adjusting a clearance between a moving blade and a stationary blade of a gas turbine, wherein a flow rate of a cooling medium supplied to the stationary blade at the time of starting up or increasing the load of the gas turbine is made smaller than a flow rate supplied at the time of steady operation.