JPH0471126B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a resonance prevention device for a combustor of a gas turbine, and particularly to a device for preventing resonance of a combustor and its supporting part due to resonance between the natural vibration of the combustor and combustion vibration. The present invention relates to a resonance prevention device for a gas turbine combustor, which is suitable for preventing this.

[Background of the invention]

A gas turbine combustor generally has a cylindrical shape, and when fuel burns inside the combustor, combustion vibrations occur due to resonance with the air column. Although the vibration level may vary, this combustion vibration always occurs as long as the phenomenon of combustion occurs.
This combustion vibration occurs with a specific vibration frequency range, and occurs in the gap between the combustor and the support that supports it, which is provided to absorb elongation due to thermal expansion during operation. Excessive vibration causes wear. The vibration of the combustor due to this combustion vibration is closely related to the natural frequency of the combustor itself, and extreme vibration of the combustor occurs at the point where the combustion frequency range and the natural frequency match, that is, in the resonance state. It is something to do. usually,
The range of combustion oscillation frequency varies slightly depending on the length of the combustor and the temperature of the combustion gas, but is limited by the combustion performance of the combustor, so it is from around 100Hz to around 200 to 300Hz. Similarly, the diameter and length of the combustor are determined from the viewpoint of combustion performance, and the wall thickness is thin to alleviate thermal stress caused by rapid temperature rises and changes. Since the support part of the combustor is installed with a considerable gap, the natural frequency range is from 100Hz to 300Hz for the first to third vibration orders, and resonance is unavoidable. It is in.

These points will be explained below with reference to the drawings.

FIG. 1 shows the details of the combustor portion of the gas turbine, FIG. 2 shows the combustion vibration characteristics, and FIG. 3 shows the relationship between the combustion frequency and the natural frequency of the combustor.

In FIG. 1, air 1 is converted into compressed air 3 by a compressor 2 and flows into a combustor inner cylinder 4.
Here, it mixes with the fuel injected from the fuel nozzle 5 and diffuses, is ignited by the spark plug 6 and burns, becomes combustion gas 7, is guided to the turbine section 8, does work, and then becomes exhaust gas 9 and is released into the atmosphere. It is becoming more and more common. A combustor generally includes a combustor inner cylinder 4 that causes combustion, and a turbine section 8 that directs the combustion gas 7.
It is configured to include a transition piece 10 that guides the vehicle.

The support section of the combustor generally includes three supports: a front support 11 of the combustor inner cylinder head 4a, an intermediate support 12 of the transition tube inlet section 10a, and a rear support 13 of the transition tube outlet section 10b. There is. Of these three supports, one is completely fixed, and gaps are set in the other two to absorb thermal expansion during operation.As a combustor,
The gap between them is designed to allow free movement.
In FIG. 1, the rear support 13 is completely fixed.

The combustion vibration is caused by the vibration of a type of cylinder, that is, an air column, formed by the combustor inner cylinder 4 and the transition piece 10 in the combustion state, and from the idea of an air column, the total length of the combustor and The frequency is determined by the speed of sound, which is determined by the temperature of the combustion gas. The overall length of the combustor does not change much even during operation, but the sound speed, which is determined by the combustion gas temperature, is constantly affected by changes in the fuel flow rate due to changes in the gas turbine load or by uneven combustion gas temperature even at a constant load. It's changing. Therefore, as shown in FIG. 2, the combustion vibration has a peak 15 within a certain frequency range 14. Further, as shown in FIG. 3, the natural frequency of the combustor varies with each vibration order. Like the combustion vibration, this natural frequency 16 also changes over a certain range due to changes in the metal temperature of the combustor itself, but the change is not as large as the frequency range of the combustion vibration.

In this state, if the natural frequency 16 and the frequency range 17 where the combustion vibration peak occurs are superimposed on the graph, the resonance frequency becomes 18 at the third natural vibration order in Fig. 3, and the combustor's resonance frequency becomes 18. Resonance will occur. When this resonance occurs, the combustor vibrates extremely, causing excessive wear on each support portion in a short period of time due to the action of the combustor's own weight. Furthermore, since the members of the combustor itself also vibrate, cracks may occur due to high cycle fatigue due to vibration stress.

In order to avoid the above-mentioned resonance, currently it is necessary to suddenly change the load on the gas turbine to change the combustion gas temperature and change the frequency range of combustion oscillations, or to significantly increase the combustor metal temperature itself by some means. I am trying to change the natural frequency by changing it. Another measure is to periodically inspect the combustor and its support and repair or replace it. However, none of these measures has the disadvantage that they cannot effectively prevent damage to the combustor and its support.

[Purpose of the invention]

It is an object of the present invention to provide a combustor for a gas turbine that eliminates the drawbacks of the prior art, avoids resonance between the natural vibration of the combustor and combustion vibration, and prevents damage to the combustor and its support due to resonance. To provide a resonance prevention device.

[Summary of the invention]

The present invention includes a combustor clamp device attached to the casing side of a gas turbine, a vibration meter attached to the combustor, and a signal processing system for determining resonance between the natural vibration of the combustor and the combustion vibration on the vibration meter. The device is characterized in that a device that controls the clamping device in the clamping direction at the time of resonance determination is connected to this signal processing system. With this configuration, when the natural vibration of the combustor and the combustion vibration resonate, Detects this and immediately mechanically tightens the combustor, temporarily increasing the natural frequency of the combustor to avoid resonance and prevent damage to the combustor and its support. be able to.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 shows how the combustor and its surrounding members are attached, FIG. 5 shows an example of the clamp device, and FIG. 6 shows a part of the clamp device in an enlarged manner.

As shown in FIG. 4, the combustor of the gas turbine includes a combustor inner cylinder 20 and a transition piece 21.

The compressed air 19 pressurized by the compressor (not shown) flows to the upstream part of the combustor inner cylinder 20 through the outside of the transition piece 21 and becomes combustion gas 22 inside the combustor inner cylinder 20. , and is guided to the turbine section 23 through the inside of the transition piece 21 .

The transition piece 21 is fixed to the turbine section 23 on the downstream side 24, and the transition piece 21 is fixed on the upstream side 25.
It is supported by a support 26 with gaps set at each part to absorb thermal elongation. This support 26 is fixed to a portion 27a of the casing 27. Thereby, the transition piece 21 is structured to easily vibrate when an excitation force is applied to the transition piece 21. This is because complete restraint cannot be achieved due to absorption of thermal expansion during operation.
This is something that must be taken into consideration when designing a gas turbine combustor, and is an essential measure. Further, a clamp device 28 is provided on the upstream side 25 of the transition piece 21 to prevent resonance of the transition piece 21.

As shown in FIG. 4, the clamping device 28 is provided near a support 26 that freely allows thermal expansion of the combustor, which is the location where the natural vibration mode of the combustor has the largest amplitude. Further, as shown in FIGS. 5 and 6, this clamp device 28 includes first and second clamp members 29,
It is constructed by combining 30 pieces.

The first and second clamp members 29 and 30 are
As shown in FIG.
They are connected by a pin 31 provided on a support 26 attached to a portion 27a of the casing 27, and the first and second clamp members 29, 30 are configured to be openable and closable. Further, a space 32 as a tightening margin is provided between the other ends of the first and second clamp members 29 and 30, and further, a space 32 is provided between the other ends of the first and second clamp members 29 and 30. First and second protrusions 33 and 34 are provided facing each other.

A clamp hole 35 is formed in the first projection 33, and an air vent hole 46 forming a control device to be described later is provided in the clamp hole 35. Further, this first protrusion 33 has a second
A hook-shaped stopper 38 for receiving the protrusion 34 is attached.

The second protrusion 34 has a clamping protrusion 36.
is provided. This clamp projection 36 is provided with an opening hole 36c. The opening hole 36c
An end on the clamp hole 35 side is closed by a side wall 36a, and the other end is opened to the casing 27 through an opening 36b. Further, this clamping protrusion 36 is slidably inserted into the clamping hole 35.

As shown in FIG. 5, a compression spring 37 is provided on the side of the space 32 between the first and second clamp members 29 and 30, and this compression spring 37 causes the first clamp member 29 to be clamped. The tip of the clamping protrusion 36 of the second clamp member 30 is biased from within the hole 35 in the direction of insertion, ie, in the direction of not being clamped. When not clamped, the second protrusion 34 is locked by a stopper 38 attached to the first protrusion 33.

Furthermore, the transition piece 21 is provided with a vibration meter 39, as shown in FIG. This vibration meter 3
9 is also attached near the support 26, which is the point where the amplitude is largest in the natural vibration mode of the combustor, and this vibration meter 39 constantly monitors the vibration of the combustor.

A signal processing system is connected to the vibration meter 39,
A control device is connected to this signal processing system.

The signal processing system includes a frequency analyzer 41 and a comparator 42, as shown in FIG. The frequency analyzer 41 analyzes the frequency of the detection signal 40 output from the vibration meter 39 and determines the vibration level 4.
It is designed to extract 3. The comparator 42
compares the vibration level 43 output from the frequency analyzer 41 with a reference value 44, determines whether resonance has occurred in the combustor, and sends a control signal 45 to the control device.

As shown in FIG. 6, the control device has an air vent hole 46 communicating with the clamp hole 35 formed in the first protrusion 33 of the clamp device 28, and an air vent hole 46 at one end as shown in FIG. An air outlet pipe 4 connected to the hole 46 and having the other end open to the atmosphere.
7 and an on-off valve 48 provided thereon. The on-off valve 48 is connected to the comparator 42, and receives a control signal 4 from the comparator 42 when resonance occurs.
5 and opens the compressed air 19 in the clamp hole 35 to the air vent hole 46 and the air outlet pipe 4.
7 and released into the atmosphere.

In addition, in FIG. 6, 49 indicates a sliding portion between the clamp hole and the clamp protrusion, and in FIG. 4, 50 indicates a fixed rear support of the combustor.

The resonance prevention device of the above embodiment operates as follows.

That is, when resonance is not occurring in the combustor due to its natural vibration and combustion vibration, the second protrusion 36 comes into contact with the hook-shaped stopper 38 due to the action of the compression spring 37, as shown in FIG. being touched,
The clamping device 28 is set to a non-clamping state. In this state, the transition piece 21 is designed so that it can move freely against thermal expansion during operation.
A gap is ensured between the first and second clamp members 29 and 30 of the clamp device 28, and the transition piece 2
1 and the clamp device 28 do not come into contact with each other.

Furthermore, during operation, the vibration of the combustor is monitored by a vibration meter 39 attached to the transition piece 21.

During operation, the detection signal 40 from the vibration meter 39 is sent to the frequency analyzer 41 of the signal processing system, and the vibration level is analyzed.
As shown in the figure, when a vibration acceleration value 51 of a high level different from other frequencies is exhibited at a certain frequency and determined to be abnormal by the comparator 42 of the signal processing system, the on-off valve 48 of the control device is controlled to open. signal 4
5 is sent, and the on-off valve 48 is immediately opened.

In other words, the state shown in Figure 7 means the occurrence of a resonance phenomenon between the natural frequency of the combustor and the combustion vibration frequency range, which causes the combustor to vibrate abnormally and cause cracks due to high cycle fatigue of the vibration stress of the combustor. , and result in excessive wear on the combustor supports.

On the other hand, in this embodiment, the on-off valve 48 is immediately opened when the resonance state is determined.
As a result, the number 10 is inserted into the clamping hole 35 formed in the first protrusion 33 of the clamping device 28.
As can be seen from FIGS. 4 and 6, the compressed air 19 at a pressure of about Kg/cm ² g is discharged into the atmosphere through the air vent hole 46 → air outlet pipe 47 → on-off valve 48.

Therefore, the pressure inside the clamp hole 35 instantly drops to atmospheric pressure. On the other hand, the clamp protrusion 36
Since a pressure of tens of kg/cm ² g of compressed air 19 is acting on the side wall 36a through the opening 36b,
Pressure inside clamp hole 35 and clamp protrusion 36
The clamping protrusion 36 immediately enters the clamping hole 35 due to the pressure difference between the pressure of the compressed air 19 and the pressure of the compressed air 19 acting on the first and second clamping members 2.
9 and 30 are closed, the transition piece 21 is strongly clamped by the clamp device 28, and vibrations are mechanically suppressed.

As shown in FIG. 8, the combustor is fixed by clamping the transition piece 21 by the clamping device 28 in a state where the combustion oscillation frequency range 53 resonates with respect to the natural frequency 52 of the combustor. The support section is temporarily added. Therefore, the combustor is supported on the casing side of the gas turbine by the fixed support portions of the clamp device 28 and the fixed rear support 50 at multiple locations, so that the rigidity of the combustor increases rapidly. Regardless of the vibration order, the natural frequency 54 of the combustor shifts to a high level as shown by the broken line in FIG. Thereby, resonance with the combustion vibration frequency range 53 can be avoided, and damage to the combustor and its support portion due to resonance of the combustor can be prevented.

Furthermore, the combustion oscillation frequency range 53 is closely related to the frequency of the air column, and fluctuates due to changes in the combustion gas temperature due to changes in the gas turbine load, but the clamping device 28 greatly increases the natural frequency of the combustor. Therefore, resonance between the natural vibration of the combustor and the combustion vibration can be avoided regardless of fluctuations in the combustion vibration frequency range 53.

Next, after the resonance of the combustor is avoided, when the vibration acceleration shown in FIG. 7 falls below a certain level, a close control signal 45 is sent from the comparator 42 of the signal processing system to the on-off valve 48 of the control device. is sent, and the on-off valve 48 is closed by this control signal 45.

After being closed by the on-off valve 48, the clamp hole 35 and the clamp protrusion 3 are inserted into the clamp hole 35.
Compressed air 19 flows in from the sliding portion 49 between the clamping hole 35 and the clamping protrusion 36, and the pressure in the clamping hole 35 and the clamping protrusion 36 become almost the same, and in this state, the compression spring 37 causes the first and second clamping members 29, 30 is opened, the transition piece 21 is placed in a non-clamping state, and each member of the clamping device 28 returns to the state shown in FIG.

In addition, in the present invention, the signal processing system and the control device are not limited to the embodiment shown in the drawings, but in essence, the signal processing system and the control device determine the resonance of the combustor based on the vibration detection signal 40 output from the vibration meter 39, and detect the resonance state. Any structure may be used as long as the clamping device 28 can be operated in the clamping direction at the time of determination.

Further, the structure of the clamp device 28 is not limited to that shown in the drawings, and may be any structure as long as it has the desired function.

Furthermore, the clamping device 28 is not limited to one location;
They may be provided at multiple locations.

〔Effect of the invention〕

According to the present invention described above, a combustor clamp device is attached to the casing side of the gas turbine, a vibration meter is attached to the combustor, and the resonance between the natural vibration of the combustor and the combustion vibration is determined by the vibration meter. A control device that controls the clamping device in the clamping direction when resonance is determined is connected to this signal processing system, and when resonance is determined, the clamping device is immediately activated to direct combustion toward the casing side of the gas turbine. Since the combustor is fixed, the natural vibration of the combustor can be greatly increased, which has the effect of avoiding resonance caused by the combustor's natural vibration and combustion vibration. This has the effect of preventing damage to the support portion.

[Brief explanation of drawings]

Figure 1 is a longitudinal side view showing the combustor of a gas turbine and its surroundings, Figure 2 is an explanatory diagram of combustion vibration characteristics, Figure 3 is a diagram showing the relationship between combustion frequency and natural frequency, Figures 4 to 6 show an embodiment of the present invention, in which Figure 4 is a vertical side view, Figure 5 is a front view of the clamping device, and Figure 6 is a partially enlarged vertical sectional view of the clamping device. A front view, FIG. 7 is an explanatory diagram of the resonance state, and FIG. 8 is an explanatory diagram of the operational characteristics of the present invention. 19...Compressed air, 20...Combustor inner cylinder, 21
... Transition pipe, 26 ... Intermediate support of combustor, 2
7... Gas turbine casing, 28... Clamp device, 29, 30... First and second clamp members, 31... Intermediate support of combustor and first,
A pin for coupling with the second clamp member, 32...
Space between first and second clamp members, 33,3
4... First and second protrusions, 35... Clamping holes, 36... Clamping protrusions, 37... Compression springs, 39... Vibration meters, 40... Vibration detection signals,
41... Frequency analyzer of signal processing system, 42... Comparator, 43... Vibration level, 44... Reference value of vibration level, 45... Control signal, 46... Air vent of control device for clamp device Hole, 47...Air outlet piping, 48...Opening/closing valve.

Claims (1)

[Claims] 1. A combustor clamp device is attached to the casing side of the gas turbine, a vibration meter is attached to the combustor, and a signal is sent to the vibration meter to determine resonance between the natural vibration of the combustor and the combustion vibration. 1. A resonance prevention device for a gas turbine combustor, characterized in that a processing system is connected to the signal processing system, and a control device for controlling a clamp device in a clamping direction at the time of resonance determination is connected to the signal processing system. 2. In claim 1, the clamping device connects one end of the first and second clamping members via a pin so that they can be opened and closed, and the other end of the clamping member through a space serving as a tightening margin. 1st and 2nd located opposite each other
One of the protrusions has a gas vent hole communicating with the control device at one end, a clamping hole that opens at the other end, and the other protrusion has an outer periphery. Insert freely into the clamp hole,
A clamping protrusion is provided that has an open hole that closes the tip end on the inner circumference side of the clamping hole and opens the rear end into the inside of the casing, and the clamping protrusion is arranged in the open hole and in the clamping hole. 1. A resonance prevention device for a gas turbine combustor, characterized in that it is configured to slide due to a pressure difference.