JP4633976B2 - Combustion vibration monitoring device for gas turbine combustor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for monitoring combustion vibration of a gas turbine combustor.
[0002]
[Prior art]
A so-called premix combustor has been put to practical use as a combustor for a gas turbine. In this combustor, the fuel injected from the main nozzle is previously mixed with air and burned, and the fuel injected from the pilot nozzle is diffused and burned, and part of the combustion air supplied from the compressor is burned. It is configured to mix with the combustion gas via a bypass valve.
Since this combustor burns the lean premixed gas, it is effective for suppressing the generation of NOx. The diffusion combustion is performed in order to stabilize the flame by the combustion of the premixed gas.
[0003]
When combustion vibration of a predetermined level or more occurs in the combustor having the above configuration, the combustor components may resonate and be damaged. Therefore, conventionally, the combustion conditions are changed by trial and error by adjusting the opening degree of the bypass valve, the pilot ratio (the ratio of the fuel supply amount to the pilot nozzle with respect to the fuel supply amount to the main nozzle), etc. This reduces the level of combustion vibration.
[0004]
[Problems to be solved by the invention]
In the premixed combustor, combustion vibrations are generated in a wide frequency range up to an ultrahigh frequency of 1000 Hz or higher. The treatment for suppressing the combustion vibration differs depending on which frequency range of the wide frequency range the combustion vibration frequency belongs to.
That is, even if the combustion vibration in a certain frequency range of the frequency range is reduced, for example, by increasing the opening of the bypass valve, this treatment is not necessarily performed when combustion vibration in another frequency range occurs. It cannot be an effective vibration reduction treatment, and in some cases, the combustion vibration in the frequency range may be suppressed by reducing the opening of the bypass valve.
Therefore, in the above trial and error method, even a highly skilled worker takes a long time to bring the combustion vibration to a predetermined level or less.
[0005]
Accordingly, an object of the present invention is to monitor combustion vibrations in a wide frequency range over a high frequency of 1000 Hz or higher, and to display the frequency analysis results of combustion vibrations in a plurality of frequency ranges in this frequency range.
Another object of the present invention is to display a treatment for reducing combustion vibrations in the plurality of frequency ranges.
Another object of the present invention is to control the combustion state adjusting element in the combustor in a direction in which the combustion vibration is reduced.
[0006]
[Means for Solving the Problems]
The present invention premixes and injects fuel injected from a main nozzle, diffuses and injects fuel injected from a pilot nozzle, and passes a part of combustion air supplied from a compressor through a bypass valve. A combustion vibration monitoring device for a gas turbine combustor configured to be mixed with combustion gas, wherein the vibration detection means detects the combustion vibration of the combustor, and the magnitude of the combustion vibration is 0 to 1000 Hz or more. Frequency analysis means for analyzing in the frequency range, and display means for displaying the frequency analysis result of the combustion vibration in a plurality of frequency ranges in the frequency range are provided.
The vibration detection means includes a pressure detection sensor for detecting the pressure of the combustion gas in the combustor, a flow rate detection sensor for detecting the flow rate of the premixed gas or the combustion gas, and a luminance for detecting the brightness of the combustion flame of the premixed fuel. At least one of the detection sensors can be used.
Display means for displaying each treatment for reducing the combustion vibration in each frequency range based on the frequency analysis result of the combustion vibration in the plurality of frequency ranges may be further provided.
As measures for reducing the combustion vibration, the opening of the bypass valve is changed, the pilot ratio that determines the ratio of the fuel supply amount to the pilot nozzle with respect to the fuel supply amount to the main nozzle, the intake air of the compressor At least one of the quantity changes is employed.
Control means for controlling the combustion state adjusting element in the combustor in the direction in which the combustion vibration is reduced can be further added based on the frequency analysis result of the combustion vibration in the plurality of frequency ranges.
As the combustion state adjusting element, an element for adjusting the opening degree of the bypass valve, an element for adjusting a pilot ratio for determining a ratio of the fuel supply amount to the pilot nozzle with respect to the fuel supply amount to the main nozzle, the compressor It is possible to employ at least one of the elements that adjust the intake air amount.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, the gas turbine GT is configured by an air compressor 10, a combustor 20, and a turbine 30 each having an inlet gate vane (IGV) 11 at an inlet.
As shown in an enlarged view in FIG. 2, the combustor 20 includes a plurality of main nozzles 22 and one pilot nozzle 23 provided on the upstream side of the inner cylinder 21, and a tail cylinder connected to the downstream side of the inner cylinder 21. 24 and an outer housing 25 containing these elements.
[0008]
Fuel is supplied to the main nozzle 21 and the pilot nozzle 22 via a main fuel adjustment valve 26 and a pilot fuel adjustment valve 27, respectively. The tail pipe 24 is provided with a bypass pipe 29 that allows the inside of the tail pipe 24 and the housing 25 to communicate with each other, and a bypass valve 29 is provided in the middle of the bypass pipe 28.
[0009]
In the combustor 20, combustion air supplied from the compressor 10 (see FIG. 1) is supplied from the upstream side of each main nozzle 22 and pilot nozzle 23. The combustion air supplied to the upstream side of each main nozzle 22 is mixed with the premixed fuel ejected from the main nozzle 22 to form a premixed gas, and a premixed flame is formed in the front area of these main nozzles 22. Is generated.
[0010]
On the other hand, the combustion air supplied to the upstream side of the pilot nozzle 22 is mixed with the pilot combustion fuel ejected from the pilot nozzle 22 to form a diffusion combustion flame.
The high-temperature combustion gas generated by the premixed flame and the diffusion combustion flame is supplied to the turbine 30 shown in FIG. 1, and rotates the turbine by its expansion action.
[0011]
Here, the operation of the bypass valve 29 will be described. When the bypass valve 29 is closed, all of the combustion air supplied from the compressor 10 is used for combustion. On the other hand, when the bypass valve 29 is opened, an amount of air corresponding to the opening degree is directly mixed into the combustion gas. Therefore, the fuel-air ratio in the combustor 20 can be changed by adjusting the opening degree of the bypass valve 29.
[0012]
For example, 16 combustors 20 (1CH to 16CH) are arranged, and the combustion vibration is monitored by the combustion vibration monitoring device 40 shown in FIG.
1 is the pressure of the combustion gas in the combustor 20, the flow velocity detection sensor 42 is the flow velocity of the premixed gas or the combustion gas, and the luminance detection sensor 43 is the luminance of the combustion flame of the premixed fuel. , And is disposed for each of the above-mentioned combustors 20 of 1CH to 16CH. Then, the detection signal of each sensor 41 is applied to a frequency analysis unit 45 including a Fourier transformer or the like via the interface unit 44, where frequency analysis is performed.
[0013]
Since the combustion vibration is a kind of resonance vibration, it appears as a fluctuation in the pressure of the combustion gas, a fluctuation in the flow velocity of the premixed gas or the combustion gas, and a fluctuation in the brightness of the combustion flame of the premixed fuel. Therefore, the detection signals of the sensors 41 to 43 substantially indicate combustion vibration.
Therefore, for example, the frequency analysis unit 45 obtains a combustion vibration spectrum by Fourier-transforming the detection signal of the pressure detection sensor 41, and the low frequency region (0 to 50 Hz) and medium frequency shown in FIG. Extracts vibration components in the frequency range (50 to 500 Hz), high frequency range (160 to 500 Hz), high frequency range 1 (1200 to 1500 Hz), high frequency range 2 (2000 to 2500 Hz) and high frequency range 3 (3500 to 4200 Hz) To do.
[0014]
The vibration spectrum obtained by the frequency analysis unit 45 and the vibration components in the respective frequency ranges are added to a processing unit 46 composed of a CPU or the like. The spectrum is transferred from the processing unit 46 to the display unit 47 and displayed on the display unit 47 as illustrated in FIGS. 4 and 5.
[0015]
4 exemplifies the spectrum of combustion vibration in the frequency range of 0 to 5 KHz of the 1CH to 8CH combustor 20, and FIG. 5 illustrates the spectrum of the combustor 20 of 11CH to 16CH in the frequency range of 0 to 500Hz. The spectrum of combustion vibration is illustrated. Of course, the display unit 47 can also selectively display spectra in other frequency ranges of 1CH to 16CH as necessary.
[0016]
On the other hand, the processing unit 46 holds the peak value of the vibration component in each frequency region of each of the 1CH to 16CH combustors 20 and causes the display unit 47 to display the peak value in the manner shown in FIG. In addition, OA shown in FIG. 6 has shown the peak value of the vibration component in the wide frequency of 0-500 Hz.
Further, the processing unit 46 compares the peak value of the vibration component in each frequency range with a predetermined allowable reference level preset for each frequency range, and the vibration component is equal to or higher than the corresponding allowable reference level. In such a case, an alarm is issued and the vibration suppression treatment shown in FIG.
[0017]
The vibration suppression treatment includes changing the opening of the bypass valve 29, changing the pilot ratio described later, and changing the angle of the IGV11. For example, the peak value of the vibration component in the frequency range 3500 to 4200 Hz is allowed. When the reference level is exceeded, an opening reduction operation of the bypass valve 29, a pilot ratio reduction operation, and an opening increase operation of the IGV 11 are displayed as vibration suppression measures.
[0018]
Note that the opening degree changing operation of the bypass valve 29 and the opening degree changing operation of the IGV 11 change the fuel-air ratio of the combustion gas. The vibration suppression treatment is predetermined based on experiments and simulations, and is stored in advance in a memory (not shown) built in the processing unit 46.
[0019]
The pilot ratio indicates the ratio of the fuel supply amount Gp to the pilot nozzle 23 with respect to the fuel supply amount Gm to the main nozzle 22, and is expressed as follows.
Pilot ratio = Gp / (Gm + Gp)
Therefore, the pilot ratio can be changed by adjusting the opening degrees of the main fuel adjustment valve 26 and the pilot fuel adjustment valve 27 shown in FIG.
[0020]
The combustion vibration can also be suppressed by executing at least one of the opening degree changing operation of the bypass valve 29, the pilot ratio changing operation, and the opening degree changing operation of the IGV 11. If these operations are executed simultaneously, a quicker vibration suppressing effect can be obtained.
[0021]
The vibration analysis results shown in FIGS. 4, 5, and 6 are based on the detection signal of the pressure detection sensor 41. However, even when the detection signal of the flow velocity detection sensor 42 representing the flow velocity of the premixed gas or the combustion gas or the detection signal of the luminance detection sensor 43 representing the luminance of the combustion flame of the premixed fuel is used, FIGS. Therefore, any one of these sensors 42 and 43 can be used in place of the pressure detection sensor 41.
[0022]
Of course, it is also possible to set a vibration suppression treatment that uses all analysis results of the detection signals of the pressure detection sensor 41, the flow velocity detection sensor 42, and the luminance detection sensor 43, and execute the vibration suppression treatment. In this way, more effective vibration suppressing action can be expected.
[0023]
It is also possible to automatically execute the vibration suppression treatment. In this case, the control unit 48 shown in FIG. 1 is provided, and an electromagnetic type is used as the main fuel adjustment valve 26, the pilot fuel adjustment valve 27, and the bypass valve 29. Then, a control command signal for instructing the vibration suppression treatment is given from the processing unit 46 to the control unit 48 to control the valves 26, 27 and 28 and the drive actuator of the IGV 11 so as to follow the vibration suppression treatment.
[0024]
That is, for example, when the peak value of the vibration component in the frequency range 3500 to 4200 Hz shown in FIG. 3 exceeds the allowable reference level, the bypass valve 29 is controlled to operate in the closing direction by a predetermined reference control amount. At the same time, the main fuel adjustment valve 26 and the pilot fuel adjustment valve 27 are controlled so that the pilot ratio decreases by a predetermined reference control amount, and the IGV 11 operates in the opening direction by a predetermined reference control amount. Controlled. Each reference control amount is also appropriately determined in advance based on experiments and simulations.
[0025]
【The invention's effect】
According to the present invention, combustion vibrations in a wide frequency range (for example, 0 to 5000 Hz) over a high frequency of 1000 Hz or more required for a premixed combustor are monitored, and a plurality of frequency ranges in this frequency range are monitored. The frequency analysis result of combustion vibration can be displayed. Therefore, it is possible to take appropriate vibration suppression measures based on the display contents of the analysis result.
In addition, according to the present invention, since the measures for reducing the combustion vibrations in the plurality of frequency ranges can be displayed, the combustion vibrations can be easily and quickly suppressed.
Furthermore, according to the present invention, since the control means for controlling the combustion state adjusting element in the direction in which the combustion vibration is reduced is provided, the combustion vibration can be automatically suppressed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a combustion vibration monitoring apparatus according to the present invention.
FIG. 2 is a cross-sectional view conceptually illustrating the structure of a premix combustor.
FIG. 3 is a flowchart showing a procedure for vibration suppression.
FIG. 4 is a graph illustrating a spectrum of combustion vibration in a certain frequency range.
FIG. 5 is a graph illustrating a spectrum of combustion vibration in another frequency range.
FIG. 6 is a graph illustrating combustion vibration levels in a plurality of frequency ranges.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Compressor 20 Combustor 22 Main nozzle 23 Pilot nozzle 30 Turbine 40 Combustion vibration monitoring apparatus 41 Pressure detection sensor 42 Flow velocity detection sensor 43 Brightness sensor 45 Frequency analysis part 46 Processing part 47 Display part 48 Control part

Claims (6)

The fuel injected from the main nozzle is premixed and burned, the fuel injected from the pilot nozzle is diffusely burned, and part of the combustion air supplied from the compressor is mixed with the combustion gas via the bypass valve. A combustion vibration monitoring device for a gas turbine combustor configured to include:
Vibration detecting means for detecting combustion vibration of the combustor;
A frequency analysis means for analyzing the magnitude of the combustion vibration in a frequency range from 0 to 1000 Hz;
Display means for displaying a frequency analysis result of the combustion vibration in a plurality of frequency ranges in the frequency range;
A combustion vibration monitoring device for a gas turbine combustor. As the vibration detection means, a pressure detection sensor for detecting the pressure of the combustion gas in the combustor, a flow rate detection sensor for detecting the flow rate of the premixed gas or combustion gas, and a luminance detection for detecting the brightness of the combustion flame of the premixed fuel The combustion vibration monitoring device for a gas turbine combustor according to claim 1, wherein at least one of the sensors is used. 3. The display device according to claim 1, further comprising display means for displaying a treatment for reducing the combustion vibration in each frequency range based on the frequency analysis result of the combustion vibration in the plurality of frequency ranges. Combustion vibration monitoring device for gas turbine combustors. The measures for reducing the combustion vibration include at least one of an opening degree of the bypass valve, a pilot ratio that determines a ratio of a fuel supply amount to the pilot nozzle with respect to a fuel supply amount to the main nozzle, and an intake air amount of the compressor. The combustion vibration monitoring device for a combustor for a gas turbine according to claim 3, wherein one of the two is changed. The control means for controlling the combustion state adjusting element in the combustor in a direction in which the combustion vibration is reduced is further added based on the frequency analysis result of the combustion vibration in the plurality of frequency ranges. 4. A combustion vibration monitoring apparatus for a gas turbine combustor according to any one of 4 above. The combustion state adjusting element includes at least one of an opening degree of the bypass valve, a pilot ratio that determines a ratio of a fuel supply amount to the pilot nozzle with respect to a fuel supply amount to the main nozzle, and an intake air amount of the compressor. 6. The combustion vibration monitoring device for a gas turbine combustor according to claim 5, wherein the combustion vibration monitoring device is an element to be adjusted.

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