JPH06193470A - Method of retraining combustion vibration and device therefor - Google Patents

Abstract

PURPOSE:To enlarge the operational range by restraining pressure variation occurring in a burner, that is, combustion vibration. CONSTITUTION:Fuel used for combustion is divided into a main fuel line 32 and an auxiliary fuel line 31, and variation pressure in a burner is detected and is then subjected to a frequency analysis so as to obtain a frequency and a degree of the pressure variation. Further, a signal having a time delay suppressing the pressure variation is delivered, and the flow rate of fuel flowing through the auxiliary line 31 is synchronized with the signal, and is changed in accordance with the degree of the pressure variation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for suppressing combustion vibration in a gas turbine combustor, and can be applied to a combustion furnace such as a boiler.

[0002]

2. Description of the Related Art In a combustor such as a gas turbine combustor, when combustion oscillation is generated, the combustor parts may be damaged. Measures have been taken to avoid the range.

FIG. 5 shows a combustor in the vicinity of a pressure fluctuation measuring section of a conventional combustor monitoring device. In FIG.
The compressed air compressed by a compression unit (not shown) passes through a large number of air holes 3 provided in the axial direction and the circumferential direction of the combustor inner cylinder 2 arranged substantially concentrically in the combustor outer cylinder 1. It passes through and flows into the combustor inner cylinder 2. The inflowing air is mixed and diffused here with the fuel injected from the fuel nozzle 4, ignited by some means and burned to generate combustion gas.

The tube 5 projectingly retained in the combustor outer cylinder 1 terminates at a substantially intermediate position of a space 6 between the combustor inner cylinder 2 and the combustor inner cylinder 2. A pressure sensor 7 is provided at the other end of the tube 5.
Is installed. This pressure is measured in each combustor.

Further, another tube 8 is attached to the outer cylinder 1 of the combustor so that its tip ends inside the inner cylinder 2 of the combustor. The other end of the tube 8 is branched into two by a block 9, and pressure sensors 10 and 11 are attached to each of them.

The pressure sensors 11, 10 and 7 output output signals P _A , P _B and P _C representing the measured pressure, and are sent to the combustion state discriminating device 12 shown in FIG. The combustion state discrimination device 12 has a combustion oscillation pressure discriminator 13 and a combustor internal / external pressure difference discriminator 14. The discriminators 13 and 14 store preset operation initial values and design allowable values, and the pressure signals P _A , P _B , P measured by the respective combustors are stored.
Output signal ~ is output in comparison with _C. The output signals of the discriminators 13 and 14 are appropriately logically operated and then become signals representing various states.

[0007]

[Problems to be Solved by the Invention] To protect the global environment,
There is a need for operation in which harmful exhaust gas is reduced as much as possible, and a combustor having a wide operating range is desired. For this purpose, it is essential to suppress the fluctuation of the pressure generated in the combustor, which has limited the operating region, that is, the suppression of combustion oscillation.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a combustion vibration suppressing means capable of suppressing combustion vibration and expanding an operating region.

[0009]

To solve the above problems, according to the present invention, the fuel used for combustion is divided into a main flow and a side flow, and the flow rate is synchronized with the pressure fluctuation of the combustor and has a time delay. A method for suppressing combustion oscillation is provided, which is characterized in that a fluctuation is applied to a sidestream.

[0010]

According to the above means, the pressure fluctuation in the combustor is measured, and the fuel flow rate is fluctuated based on the measured pressure fluctuation to suppress the combustion vibration. However, of all the fuel, the components that contribute to pressure fluctuations are very small, so
The fuel system is divided into a main flow and a sub flow, and only the fuel flow rate of the sub flow is changed.

[0011]

FIG. 1 shows an example of the construction of an apparatus in which the method for suppressing combustion oscillation according to the present invention is applied to a gas fuel combustor. In FIG. 1, reference numeral 20 is a combustor, 21 is a conduit, and 2
2 is a pressure sensor, 23 is an amplifier, 24 is a processing device, 25
Is a fast Fourier transformer, 26 is a digital filter, 2
7 is a delay circuit, 28 is an output amplifier, 29 is a valve drive device,
Reference numeral 30 is a fuel flow rate adjusting valve, 31 is a sub fuel line, and 32 is a main fuel line.

As shown in FIG. 1A, the fuel system is composed of one auxiliary fuel line 31 arranged in the center and eight main fuel lines 32 arranged in a large number in the circumferential direction. As shown in FIG. 1B, the combustion oscillation suppressing device is associated with only the auxiliary fuel line 31, and is a total fuel
The fuel system of / 9 is adjusted.

The pressure fluctuation generated in the combustor 20 is transferred to the conduit 21.
After being converted into an electric signal by the pressure sensor 22 via the, the signal is amplified by the amplifier 23 and input to the processing device 24. The processing unit 24 includes a fast Fourier transformer 25, a digital filter 26 and a delay circuit 27,
The electric signal from the amplifier 23 is first subjected to frequency analysis by the fast Fourier transformer 25, and the main frequency of pressure fluctuation and its magnitude are detected. Thereafter, the digital filter 26 extracts only the vibration of the frequency component analyzed by the fast Fourier transformer 25, and the delay circuit 27 converts the vibration into a vibration waveform having a time delay so as to suppress the pressure fluctuation generated in the combustor 20. It The vibration waveform from the delay circuit 27 including the frequency and amplitude components is output and amplified by the output amplifier 28 and then input to the valve drive device 29 to drive the fuel flow rate adjusting valve 30 to change the fuel supply amount in the sidestream. Let

The magnitude of the drive signal of the fuel flow rate adjusting valve 30 corresponds to the magnitude of the pressure fluctuation, and when the large pressure fluctuation occurs, the flow rate fluctuation largely works. Further, the time delay of the vibration determined by the delay circuit 27 is a phase that suppresses the generated pressure fluctuation, that is, the time from when the fuel is injected into the combustor 20 to when the pressure due to combustion rises. A value obtained by correcting the response time delay of the drive device 29 is used.

FIG. 2 shows an example of application to an oil fuel combustor. In the figure, the same parts as those shown in FIG. 1 are designated by the same reference numerals. In FIG. 2, the sub fuel line 31 is provided with a fuel flow rate adjusting valve 33 and a solenoid valve 34.

The pressure fluctuation generated in the combustor 20 is transferred to the conduit 21.
After being converted into an electric signal by the pressure sensor 22 via the, the signal is amplified by the amplifier 23 and input to the processing device 24. In the processing device 24, the electric signal amplified by the amplifier 23 is frequency-analyzed by the fast Fourier transformer 25, the main frequency of pressure fluctuation and its magnitude are detected, and the fuel flow rate corresponding to the magnitude of pressure fluctuation is detected. The opening degree of the adjusting valve 33 is determined. Next, the digital filter 26 extracts only the vibration of the frequency component analyzed by the fast Fourier transformer 25, and the delay circuit 27 sets the timing corresponding to the phase that suppresses the pressure fluctuation generated in the combustor 20. Occurs,
The solenoid valve 34 is controlled to open and close. As a result, the fuel in the auxiliary fuel line 31 is periodically introduced into the combustor 20 in accordance with the pressure fluctuation timing by a predetermined amount according to the magnitude of the pressure fluctuation.

FIG. 3 shows the effect of the embodiment of FIG. 1, in which the variation of the valve opening is delayed by an amount corresponding to a phase angle of 90 ° with respect to the variation of the pressure, and the auxiliary fuel line 31 is delayed.
It is shown that the pressure fluctuation level can be reduced to a fraction by changing the fuel quantity.

FIG. 4 shows temporal changes in pressure fluctuation, fuel fluctuation, and heat generation fluctuation. The heat generation fluctuation generated by the fuel fluctuation occurs at the timing 180 ° out of phase with the pressure fluctuation in the combustor, and it can be seen that there is an effect of canceling the pressure fluctuation.

[0019]

According to the present invention, the pressure fluctuation in the combustor is measured, and the fuel flow rate is changed based on this pressure fluctuation to suppress the pressure fluctuation, so that the combustion vibration is greatly reduced. Therefore, it is possible to include the region where combustion vibration has occurred until now in the operating region, and it is possible to secure a wide operating region.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of a combustion vibration suppressing device according to the present invention.

FIG. 2 is a configuration diagram showing another example of the combustion vibration suppressing device according to the present invention.

FIG. 3 is an explanatory view showing the effect of suppressing combustion oscillation by the device of FIG.

FIG. 4 is an explanatory diagram showing temporal changes in pressure fluctuation, fuel fluctuation, and heat generation fluctuation.

FIG. 5 is a partial cross-sectional view of a combustor showing a pressure fluctuation measurement unit of a conventional combustor monitoring device.

6 is a configuration diagram showing an example of a combustion state determination device of the device of FIG.

[Explanation of symbols]

 20 Combustor 21 Conduit 22 Pressure Sensor 23 Amplifier 24 Processor 25 Fast Fourier Transform 26 Digital Filter 27 Delay Circuit 28 Output Amplifier 29 Valve Driver 30 Fuel Flow Control Valve 31 Secondary Fuel Line 32 Main Fuel Line 33 Fuel Flow Control Valve 34 solenoid valve

Claims (3)

[Claims] 1. A combustion oscillation characterized in that the fuel used for combustion is divided into a main flow and a side flow, and a flow rate fluctuation that is in synchronism with the pressure fluctuation of the combustor and has a time delay is given to the side flow. Suppression method. 2. A pressure sensor for detecting a pressure fluctuation generated in a combustor and converting it into an electric signal, an amplifier for amplifying the converted electric signal, and a frequency analysis of the amplified electric signal for frequency fluctuation main analysis. Fast Fourier transformer for outputting the frequency and its magnitude, a digital filter for extracting only the vibration component from the analyzed frequencies, and converting the vibration component into a vibration waveform with a time delay for suppressing the pressure fluctuation. A combustion vibration suppressing device comprising: a delay circuit, an amplifier for amplifying a vibration waveform of the delay circuit, and a device for varying a fuel flow rate of a sidestream according to the amplified vibration waveform. 3. A pressure sensor for detecting a pressure fluctuation generated in a combustor and converting it into an electric signal, an amplifier for amplifying the converted electric signal, and a frequency analysis of the amplified electric signal for the main purpose of the pressure fluctuation. Fast Fourier transformer that outputs the frequency and its magnitude, a digital filter that extracts only the vibration component from the analyzed frequencies, and a delay that generates a timing corresponding to the time delay for suppressing the pressure fluctuation from the vibration component. A combustion oscillation suppressing device comprising: a circuit; and a device that adjusts a fuel flow rate of the sidestream according to the magnitude of the pressure fluctuation and supplies or stops the sidestream fuel according to the timing.