JP3233798B2 - Combustor combustion vibration / pressure fluctuation reduction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reducing combustion vibration and pressure fluctuation of a combustor such as a gas turbine.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional gas turbine combustor. Air from the compressor burns fuel in a combustor 3 provided in the vehicle interior 1 to generate high-temperature combustion gas, and the combustion gas is supplied to a turbine to drive it. Reference numeral 2 denotes a bypass valve provided in the combustor 3.

In the conventional combustor, when combustion oscillations and pressure fluctuations occur, the fuel / air distribution ratio (fuel / air ratio), pilot ratio, bypass valve opening, and the like are changed, and the combustion state is determined by trial and error. By changing the pressure, combustion oscillation and pressure fluctuation were avoided. In addition, other measures have been taken such as securing the strength so that each member is not damaged even if combustion vibration or pressure fluctuation occurs.

Specifically, during the actual operation of the machine, the level of combustion vibration and pressure fluctuation is detected and monitored by a pressure sensor, and when a certain level of combustion vibration or pressure fluctuation occurs, the fuel-air ratio, pilot ratio and the like are determined. It is adjusted to be below a certain level that has been changed by trial and error. In addition, in order to secure strength when combustion vibrations and pressure fluctuations occur, ribs are provided in stress concentration portions of the combustor and peripheral devices thereof, and stress is reduced by increasing the thickness.

As described above, conventional measures against combustion vibration and pressure fluctuation have mainly focused on measures from the combustion system and structure, and few measures have been observed from the acoustic system.

Further, as shown in FIGS.
In the conventional gas turbine combustor 3 having a structure in which an inner cylinder 21 having a nozzle 24 and a tail cylinder 22 are fitted, a fitting portion between the inner cylinder 21 and the tail cylinder 22 is a type of a leaf spring. A spring clip 25 is interposed (see FIG. 9), and the combustion chamber 3 is only provided with a seal against the fluid from the cabin 1 and a damping of the structural system in view of the structural strength. There was almost no difference from the attenuation in the case of a rigid wall, and no measures and examinations were made for the acoustic system.

[0007]

SUMMARY OF THE INVENTION Combustion oscillations in a combustor,
A parameter is very complicated regarding the occurrence conditions of pressure fluctuations, satisfies the performance of such a gas turbine, NO _x, satisfies the emissions regulations such as CO, moreover to find the operating conditions such that the level of the combustion vibration small It was very difficult. In addition, even if driving conditions that satisfy all the conditions are found in the light, changes in weather conditions such as temperature and humidity,
Combustion oscillations and pressure fluctuations may occur due to changes in fuel components, malfunctions in the controller, and the like, and damage to the combustor and blades may occur.

Therefore, conventionally, as described above, the fuel / air distribution ratio, the pilot ratio, the opening degree of the bypass valve, etc. are changed to change the combustion state by trial and error, or to secure the strength of the equipment. Measures had been taken.

[0009] The combustion oscillation and pressure fluctuation in the combustor are important parameters of the oscillation condition, such as the oscillation frequency and the acoustic mode (pressure mode) and the positional relationship of the heat source. It is an object of the present invention to provide a device which can easily reduce combustion vibration and pressure fluctuation by performing control from the acoustic side separately from the countermeasure of the above.

[0010]

(1) A combustion vibration reducing device for a combustor according to the present invention comprises a hole provided in at least one of a combustor, a duct connected to the combustor, and a vehicle compartment. ,
A filling member having a low acoustic impedance and a high fluid impedance arranged to close the hole, and a valve for controlling the opening degree of the hole. (2) The apparatus for reducing pressure fluctuation of a combustor according to the present invention has a heat resistance with a low acoustic impedance and a high fluid impedance at a fitting portion between an inner cylinder and a transition piece of a combustor of a gas turbine having a fitted inner cylinder and a transition piece. The member was interposed, and the fitting portion was fluidly sealed.

[0011]

According to the present invention (1), the filling member arranged so as to close the hole provided in at least one of the combustor, the duct portion connected to the combustor and the vehicle compartment portion has the acoustic impedance. Is low, so that sound can pass, and fluid impedance is high, so that fluid cannot pass. Therefore, when the valve for controlling the opening degree of the hole is opened, the filling member and the valve are acoustically open and fluidly closed. When the valve is closed, the filling member and the valve are acoustically fluid. Also closes.

Therefore, according to the present invention (1), even if the hole is provided, the fluid does not flow through the hole regardless of the opening and closing of the valve, and the air distribution changes and the combustion state in the combustor changes. Is prevented.

When a hole is provided in a tubular member such as a combustor and a duct connected to the combustor or in a vehicle compartment, acoustic characteristics (particularly, frequency) vary depending on the size of the hole. By controlling the opening degree of the hole, the frequency (generally higher when the hole is drilled), the mode, and the damping can be changed.

The oscillation conditions of the combustion oscillation and the pressure fluctuation in the combustor are expressed by the following equation 1 when the pressure fluctuation is represented by p 'and the heat generation fluctuation q'.

[0015]

(Equation 1)

The magnitude of the left side of the above equation (1) depends on the pressure mode, the position of the heat source, and the time delay (the natural frequency of the acoustic system and the time delay of the supply system and the combustion system).

In the present invention (1), since the pressure mode and the natural frequency of the acoustic system can be adjusted by adjusting the opening of the hole, the value on the left side can be reduced, and the generation of vibration can be reduced. Can be prevented. By drilling holes, the attenuation of the field on the right side is increased, so that combustion vibration can be suppressed.

In the present invention (2), since the heat-resistant member interposed between the fitting portion of the inner cylinder and the transition piece of the combustor of the gas turbine has low acoustic impedance and high fluid impedance, the clearance of the fitting portion is low. Are acoustically open and fluidly closed.

Therefore, in the present invention (2), it is possible to prevent the fluid from flowing out and in through the heat-resistant member in the clearance of the fitting portion, and to prevent the air distribution from changing and the combustion state in the combustor from changing. Can be.

When there is a tubular part such as an inner cylinder and a transition piece of a combustor in a volume such as a vehicle compartment such as a gas turbine combustor, the acoustic characteristics change when a gap is provided in the pipe. The natural frequency increases, the sound attenuation increases, and the sound pressure mode of the clearance approaches the mode of the portion outside the clearance such as the vehicle interior.

In the mode on the cabin side of the clearance between the inner cylinder and the transition piece of the gas turbine combustor, there is almost no sound pressure except for low-order modes (Helmholtz mode and circumferential primary axis primary mode). . Therefore, the sound pressure mode of the clearance becomes close to open by providing a clearance for most of the modes.

Further, the oscillation condition of the pressure fluctuation in the combustor is expressed by the above equation (1). The size of the left side of Equation 1 depends on the pressure mode, the position of the heat source, and the time delay.

In the present invention (2), an acoustic clearance is formed in the fitting portion between the inner cylinder and the transition piece by the heat insulating member having a low acoustic impedance, the natural frequency increases, the wavelength decreases, Oscillation of pressure fluctuation is suppressed for the same combustion state. Also, the sound pressure mode of this clearance is close to open as described above, and since this clearance is in the combustion zone, p ′ in Equation 1 becomes smaller,
Oscillation of pressure fluctuation is suppressed.

Further, by forming an acoustic clearance at the fitting portion between the inner cylinder and the transition piece of the combustor, the attenuation of the field on the right side of Equation 1 is increased, so that the pressure fluctuation can be further reduced.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. In this embodiment, in the conventional gas turbine combustor shown in FIG. 7, a circular hole 7 having a diameter of about 2/3 to 1/3 of the diameter is provided in the combustor 3, and a cylindrical hole is formed in the hole 7. A pipe 8 is connected, a control valve 5 is provided at the end of the pipe 8 that can adjust the opening degree from fully closed to fully open, and a porous material having a low acoustic impedance and a high fluid impedance such that the hole 7 is closed in the pipe 8. The heat-resistant filling member 4 was disposed. The holes 7 are provided upstream or downstream of a region of the combustor 1 where a flame is generated, and the number thereof may be one or more.

Conventionally, since the acoustic characteristics of the combustor could not be adjusted, as shown in FIG. 2, the pilot ratio and the like were changed by trial and error with respect to a constant combustion oscillation oscillation range (1). Was changed from (a) to (b) to avoid combustion oscillation. However, in this embodiment, in addition to such adjustment of the combustion surface, adjustment of the acoustic surface can be performed. That is, by opening the control valve 5, the natural frequency f of the acoustic system is raised to f ', thereby increasing the oscillation range (1).
By shifting from (2) to (2), combustion oscillation can be avoided regardless of whether the operating condition is (a) or (b). Also, depending on the mode, it is considered that the pressure mode is greatly changed by opening and closing the hole 7, and when the hole 7 is closed,
Although the position of the heat source (flame) was downstream of the antinode of pressure, the oscillation range was changed from (1) to (3) by opening the hole 7 to make the position of the heat source upstream of the antinode of pressure. It can be shifted, and the combustion oscillation can be avoided.

Moreover, since the filling member 4 has a low acoustic impedance and a high fluid impedance, air or the like can pass through the filling member 4 even when the acoustic characteristics change due to the opening and closing of the control valve 5 as described above. Therefore, it is possible to prevent a change in the air distribution in the combustor 3 and a change in the combustion state.

Further, since the field attenuation can be added by opening the hole 7, the oscillation range can be reduced from (1) to (4) as shown in FIG. Therefore, it is effective in suppressing combustion oscillation from the viewpoint of damping.

As described above, according to the present embodiment, the combustion vibration can be controlled from the acoustic surface, the combustion vibration can be prevented over a wide range without causing a change in the combustion state, and the reliability can be improved. Can be.

A second embodiment of the present invention will be described with reference to FIG. In this embodiment, a pipe 1 extending from a combustor 3 to a bypass valve 2 in a combustor of a conventional gas turbine shown in FIG.
0, a hole 7 is provided, and a duct 6 is connected to the hole 7;
A control valve 5 capable of changing the degree of opening from fully closed to fully open is provided at the tip of. A filling member 4 similar to that of the first embodiment was arranged so as to close the hole 7 in the duct 6.

A third embodiment of the present invention will be described with reference to FIG. In the present embodiment, in the conventional gas turbine combustor shown in FIG. 7, a hole 7 is provided from the casing 1 to the turbine casing 11 or the compressor casing 12 (in FIG. 3, the hole 7 facing the turbine casing 11 is shown). A duct 6 is connected to the hole 7 and a control valve 5 is provided at the end of the duct 6 so that the opening degree can be changed from fully closed to fully open. A filling member 4 similar to that of the first embodiment was arranged so as to close the hole 7 in the duct 6.

In the second and third embodiments, the same operation and effect as those of the first embodiment can be obtained.

In the first, second and third embodiments, the filling member 4 is connected to the pipe 8 of the combustor 3, the duct 6 connected to the pipe 10 extending from the combustor 3 to the bypass valve 2, and Although each of the ducts 6 extending from the vehicle compartment 1 to the turbine casing is filled, the filling member 3 may be filled in a plurality of the above-mentioned portions at the same time.

A fourth embodiment of the present invention will be described with reference to FIG. This embodiment is an improvement of the conventional gas turbine combustor shown in FIGS. 8 and 9 as follows.

That is, at the fitting portion between the inner cylinder 21 having a circular cross section and the transition piece 22 having a circular cross section of the combustor 3 of the gas turbine, a spring attached to the outer periphery of the inner cylinder 21 for sealing leakage of fluid. An annular thickness of a porous material such as a sintered metal mesh, sintered metal, or porous ceramics, which has a large impedance fluidly but has a small acoustic impedance (a large sound pressure transmission amount) between the clip 25 and the transition piece 22. The heat-resistant member 23 having a height c is interposed so as to fluidly seal the fitting portion.

The spring clip 25 may have the same shape as that of the prior art. The inner diameter of the heat-resistant member 23 is equal to the inner diameter of the transition piece 22. As a result, the sound attenuation by the heat-resistant member 23 is increased, and the acoustic characteristics are improved. Can be improved.

Further, the fitting portion between the inner cylinder 21 and the transition piece 22 is fluidly sealed by the heat-resistant member 23, so that air or the like does not flow out and in through the heat-resistant member 23. it is possible to prevent causing a change <br/> allocation is turned into combustion state.

The effect of this embodiment will be described with reference to FIG. In this embodiment, first, the period of the natural vibration of the acoustic system is set to T by increasing the natural frequency due to the acoustic clearance.
6 to T ′, the wavelength with respect to the length of the heat source is shortened as shown in FIG. 6B, and the oscillation range of the pressure fluctuation is set as shown in FIG. , A to B. Further, as described above, since the mode of the acoustic clearance can be close to open, and the clearance is in the combustion zone,
Is reduced, and the oscillation range can be further reduced as shown by C in FIG. 6A. Finally, the acoustic gap increases the attenuation of the field, which is further illustrated in FIG.
The oscillation range can be reduced as indicated by D in FIG. Eventually, the oscillation range of the present embodiment becomes D as compared with the conventional oscillation range A, and the pressure fluctuation can be reduced.

As described above, according to the present embodiment, it is possible to reduce the pressure fluctuation without affecting the combustion state of the combustor, and it is possible to obtain a wider operating condition of the gas turbine. This has the effect of improving reliability.

[0040]

According to the present invention, there is provided a filling member having a low acoustic impedance and a high fluid impedance so as to cover a hole provided in at least one of a combustor, a duct portion connected to the combustor, and a vehicle compartment. By arranging and providing a valve for controlling the opening degree of the hole, it is possible to control combustion vibration from an acoustic surface without affecting the combustion state, and to prevent oscillation of combustion vibration in a wide range. Reliability can be improved.

Further, according to the present invention, a heat insulating member having a low acoustic impedance and a high fluid impedance is interposed in a fitting portion of an inner cylinder and a transition piece of a combustor of a gas turbine, and the fitting portion is fluidly sealed. Accordingly, the pressure fluctuation can be reduced from the acoustic surface without affecting the combustion state, and the gas turbine can be operated over a wide range, so that the reliability can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a combustion time delay and a combustion gain (load) showing the effect of the first embodiment.

FIG. 3 is an explanatory diagram of a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a third embodiment of the present invention.

5A and 5B show a fourth embodiment of the present invention. FIG. 5A is a longitudinal sectional front view, and FIG. 5B is a sectional view taken along line AA of FIG. 5A.

FIG. 6A is a graph showing the relationship between the cycle and the combustion gain (load) showing the effect of the fourth embodiment.
(B) is an explanatory view of the relationship between the position of the heat source and the pressure mode in the fourth embodiment.

FIG. 7 is an explanatory diagram of a conventional gas turbine combustor.

FIG. 8 is an explanatory diagram of another conventional gas turbine combustor.

FIG. 9A is a vertical sectional front view of a combustor of another conventional gas turbine, and FIG. 9B is a side view thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cabin 2 Bypass valve 3 Combustor 4 Filling member 5 Control valve 6 Duct 7 Hole 8, 10 Pipe 11 Turbine casing 12 Compressor casing 21 Inner cylinder of combustor 22 Transition pipe of combustor 23 Heat-resistant member 24 Nozzle 25 Spring clip

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F23R 3/42 F02C 7/24

Claims (2)

(57) [Claims] 1. A hole provided in at least one of a combustor, a duct portion connected to the combustor, and a vehicle compartment, and a filling material having a low acoustic impedance and a high fluid impedance arranged to cover the hole. A combustion vibration reducing device for a combustor, comprising: a member; and a valve for controlling an opening degree of the hole. 2. A heat-resistant member having a low acoustic impedance and a high fluid impedance is interposed in a fitting portion of a combustor of a gas turbine having a fitted inner cylinder and a transition piece. An apparatus for reducing pressure fluctuation of a combustor, which is fluidly sealed.