JP3559868B2 - Flame optical measurement device, combustion diagnosis device and combustion diagnosis method using the same - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a combustion diagnosis method and a combustion diagnosis device. More specifically, the present invention relates to a combustion diagnosis method and a combustion diagnosis device for a combustor in which a plurality of combustion burners are arranged close to each other.
[0002]
[Prior art]
In a gas turbine, in recent years, for the purpose of ease and NO _X reduction of load adjustment, the multi-burner type and multi-can type (hereinafter, simply multi that burner type) come to the combustor is often used for I have. In order to operate this gas turbine efficiently, it is necessary to grasp the combustion state of each burner, that is, make a combustion diagnosis. As for the combustion diagnosis of such a combustion flame, a method of diagnosing a combustion state by detecting a light emission spectrum of a combustion product contained in the flame with an optical probe or the like has been conventionally used.
[0003]
For example, Japanese Patent Publication No. 2-27571 discloses a spectrum that emits light from combustion products OH, C ₃ , CH, CH ₂ O, CHO, C ₂ , soot, H ₂ O, CO _2, etc. contained in a flame. As a reference substance, soot, H ₂ O, CO ₂ , and C _2, which are divided into two or more wavelengths, are spectrally measured, emit light at at least two wavelengths, and have a known relationship between the absorption coefficient for each wavelength. One of the reference materials is selected and measured at two wavelengths, the brightness of the reference material is analyzed to determine the flame temperature and the luminous efficiency of the reference material, and an index indicating the previously determined combustion state A combustion diagnosis method characterized by diagnosing the combustion state of a flame by using the relational expression is proposed.
[0004]
Also, a method of controlling a combustor based on such combustion diagnosis is disclosed in, for example, Japanese Patent Application Laid-Open No. Sho 63-105262, in which spark ignition is performed by setting an air-fuel ratio of an intake air-fuel mixture to a lean mixture leaner than a stoichiometric air-fuel ratio. The internal combustion engine is provided with an optical sensor for detecting combustion light in the combustion chamber, and the air-fuel ratio in the intake system is adjusted so that the output of the optical sensor becomes a value corresponding to the air-fuel ratio at the misfire limit. A method of controlling an air-fuel ratio in a lean-burn internal combustion engine characterized by the following has been proposed.
[0005]
However, in the gas turbine, since the compressor, the combustor, and the turbine are very compactly assembled, the burners provided in the combustor are also arranged close to each other. Therefore, the flames from the respective burners often interfere with each other.
[0006]
However, there has not been proposed any method for diagnosing the combustion of a flame that causes mutual interference in such burners arranged close to each other. Therefore, there is a problem that the combustion state of each burner cannot be grasped and control according to the combustion state of each burner cannot be performed.
[0007]
As described above, conventionally, since the combustion state of each burner cannot be diagnosed, only the total air flow rate and / or the total fuel flow rate is controlled instead of controlling each burner individually. Therefore, there is a problem that optimal control cannot be performed. In other words, the combustion air has a non-uniform flow velocity distribution due to the influence of the scroll shape and the like, so that the amount of air supplied to each burner may be unbalanced. As a result, the combustion becomes non-uniform, deviating from the optimum combustion state.
[0008]
Further, in the conventional detection device, since the optical probe is sometimes exposed to the flame, there is a problem that the optical probe used for detecting the flame is burned. Alternatively, there is also a problem that the structure is complicated because the optical probe is water-cooled or the like for protection from a flame.
[0009]
[Problems to be solved by the invention]
The present invention has been made in view of the problems of the related art, and since the burners are arranged close to each other, even when the flames interfere with each other, the combustion state of each burner can be accurately diagnosed. It is a main object to provide a combustion diagnosis method and a combustion diagnosis device.
[0010]
[Means for Solving the Problems]
The flame optical measuring device of the present invention is an optical flame measuring device in a combustion device of a gas turbine in which a plurality of burners are arranged close to each other, wherein the flame is provided between the swirler blades behind the swirler. Is provided so as to face a position facing the wall surface of the combustion chamber, and has an optical fiber probe whose tip is cut obliquely so as to have a specific viewing angle. Further, the combustion diagnosis device of the present invention is a combustion diagnosis device in a combustion device of a gas turbine in which a plurality of burners are arranged close to each other, wherein the optical diagnosis means, the spectroscopic means, the photoelectric conversion element, Processing means, wherein the optical measuring means is the optical measuring device .
[0011]
The combustion diagnosis is performed by comparing the measurement result of the optical measuring means with an index indicating a combustion state created in advance. Here, in the combustion diagnosis, for example, the self-luminous intensity ratio of the radical self-luminescence is obtained from the measured radical self-luminescence contained in the flame, and then the radical self-luminous intensity ratio and the airspace are calculated in advance based on the calculated value. The air-fuel ratio of each burner is calculated from the relationship with the fuel ratio.
[0012]
At that time, the radical self-emission intensity ratio, the intensity ratio of the OH radical self-emission intensity and CH radical self-emission intensity, and the intensity ratio or CH radical self-luminous intensity of the OH radicals self-emission intensity and C ₂ radical self-emission intensity It is preferable that the intensity ratio is the intensity ratio with the C ₂ radical self-luminous intensity.
On the other hand, a combustion diagnosis method according to the present invention is a combustion diagnosis method using the above-described optical measuring device for flame , wherein the combustion diagnosis is performed based on the radical self-luminous intensity measured by the optical measuring device. It is characterized by performing .
[0014]
Further, in the combustion diagnostic device of the present invention, the arithmetic processing means holds the relationship between the radical self-luminous intensity ratio present in the flame and the air-fuel ratio in the form of a table or a function. Here, as the radical self-emission intensity ratio, for example, the intensity ratio of the OH radical self-emission intensity and CH radical self-luminous intensity, the intensity ratio of the OH radical self-emission intensity and C ₂ radical self-emission intensity or CH radicals own The intensity ratio between the emission intensity and the C ₂ radical self-emission intensity is used.
[0015]
[Action]
Optical measurement of the self-emission of light from the flame of each burner in the combustor where the burners are located close to each other, at places where there is little effect on the flames of other burners, for example, at places facing the wall of the flame Measured by means, for example, an optical fiber probe, and the obtained light is subjected to spectral analysis. From the change in the emission intensity ratio of each radical self-luminescence (OH radical, CH radical, C ₂ radical) obtained by this spectral analysis, an index relating to the local air-fuel ratio in each burner or each can is calculated, and this index is set in advance. Combustion diagnosis, for example, calculation of the measured burner air-fuel ratio, is performed by collating with a prescribed relationship, for example, with a graph of the relationship between the emission intensity ratio and the air-fuel ratio.
[0016]
【Example】
Hereinafter, the present invention will be described based on embodiments with reference to the accompanying drawings, but the present invention is not limited to only the embodiments.
[0017]
FIG. 1 shows a block diagram of a combustion diagnosis device used in the combustion diagnosis method of the present invention. The combustion diagnostic apparatus shown in FIG. 1 includes, as main components, an optical measuring unit 1, a spectroscope 2, which is a spectroscopic unit, a photoelectric conversion element 3, and an arithmetic processing unit 4.
[0018]
The optical measuring means 1 detects or measures radical self-emission from OH radicals, CH radicals, C ₂ radicals, etc., and uses, for example, an optical fiber probe. Here, the optical fiber probe 1 will be described as an example, but the present invention is not limited to this. In the present embodiment, the optical fiber probe 1 is disposed, for example, behind a swirler 5 and attached to a premixed fuel nozzle 6, as shown in FIG. For this reason, as shown in FIG. 3, the tip portion 1a of the optical fiber probe 1 is cut obliquely so as to have a specific viewing angle so that a flame can come between the blades of the swirler 5. Further, as shown in FIG. 3, a heat-resistant protective tube 7, for example, a protective tube 7 made of a stainless steel tube is attached to the optical fiber probe 1 in order to secure its mechanical strength. At a predetermined location at the distal end of the protective tube 7, a measurement 7a window corresponding to the predetermined viewing angle is provided. The position of the flame facing the optical fiber probe 1 is a position where the influence of the flame of the adjacent burner is as small as possible. Specifically, for example, the flame is a portion facing the wall surface of the combustion chamber. As described above, in this embodiment, since the optical fiber probe is disposed behind the swirler, the optical fiber probe is not exposed to a flame. Therefore, cooling equipment and the like become unnecessary, and the configuration of the device can be simplified.
[0019]
The light detected by the optical fiber probe 1 is guided to the spectroscope 2 by an optical fiber cable, and is split into, for example, OH radical self-emission, CH radical self-emission, and C ₂ radical self-emission. Although the detailed description of the configuration of the spectroscope 2 is omitted, it is a known type conventionally used for this type of spectroscopy.
[0020]
The light separated by the spectroscope 2 is further guided to the photoelectric conversion element 3 by an optical fiber cable, converted into an electric signal, amplified, and guided to the arithmetic processing unit 4. Here, as the photoelectric conversion element 3, for example, a photomultiplier tube is used.
[0021]
The arithmetic processing unit 4 creates an index for combustion diagnosis based on the intensity of the detected radical self-emission and calculates the air-fuel ratio of the burner based on the intensity of the detected radical self-emission, thereby diagnosing the combustion state. . For example, the arithmetic processing unit 4, as shown in FIG. 4, the intensity ratio of the OH radical self-emission intensity and CH radical self-luminous intensity, the intensity ratio of the OH radical self-emission intensity and C ₂ radical self-emission intensity, and The relationship between the air-fuel ratio and the intensity ratio between the CH radical self-emission intensity and the C ₂ radical self-emission intensity is stored in advance as a table or a function. The air-fuel ratio in the operating state of each burner is calculated by calculating the intensity ratio of the self-light emission.
[0022]
FIG. 5 shows a block diagram of a combustion control device using such a combustion diagnostic device. The combustion control device shown in FIG. 5 has an air-fuel ratio control device 21 which receives the air-fuel ratio of each burner operating state from the combustion diagnosis device and calculates a control amount of air and fuel based on the input value. The main components are an air flow control device 22 that controls the air flow of each burner and a fuel flow control device 23 that controls the fuel flow of each burner.
[0023]
As the air-fuel ratio control device 21, for example, a computer is used. The computer 21 receives the air-fuel ratio of the operating state of each burner from the combustion diagnostic device, and stores a program for calculating a control amount of air and fuel based on the value and a necessary program required for control. .
[0024]
The air flow adjusting device 22 includes, for example, an air flow adjusting air flow path variable mechanism 221 and a variable mechanism control unit 222 that operates the variable mechanism 221. The variable mechanism control unit 222 adjusts the air flow path variable mechanism 221 corresponding to the air flow rate instructed by the air-fuel ratio control device 21.
[0025]
The fuel flow control device 23 includes, for example, a fuel flow control valve 231 and a valve control unit 232 that operates the valve 231. The valve control unit 232 adjusts the valve 231 to an opening corresponding to the fuel flow rate instructed by the air-fuel ratio control device 21.
[0026]
As described above, according to the present control device, since the fuel flow rate and the air flow rate are controlled for each burner while feeding back the air-fuel ratio in the operating state of each burner, each burner is burned at the optimum air-fuel ratio. be able to.
[0027]
As described above, the present invention has been described based on the embodiments. However, the present invention is not limited only to the embodiments, and various modifications are possible. For example, the combustion diagnostic device can be configured as shown in FIG. 6 to reduce the number of photoelectric conversion elements. With this configuration, the number of expensive photoelectric conversion elements can be reduced, and the cost of the combustion diagnostic device can be reduced. In FIG. 6, 31 indicates a demultiplexer, 32 indicates a rotating filter, 33 indicates a multiplexer, 34 indicates a photoelectric conversion element, and 35 indicates an FFT analyzer.
[0028]
【The invention's effect】
As described above, according to the present invention, even in a combustor in which a plurality of burners are closely arranged, an excellent effect that a combustion state in an operating state of each burner can be accurately diagnosed can be obtained. Can be
[0029]
Further, when each burner is controlled based on the combustion diagnosis result of the present invention, an excellent effect that each burner can be burned at an optimum air-fuel ratio can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment of a combustion diagnosis device used in a combustion diagnosis method of the present invention.
FIG. 2 is an explanatory diagram of an installation location of an optical fiber probe.
FIG. 3 is an explanatory diagram of an optical fiber probe.
FIG. 4 is a graph showing a relationship between a radical self-luminous intensity ratio and an air-fuel ratio.
FIG. 5 is a block diagram of a combustion control device using the combustion diagnosis device of the present invention.
FIG. 6 is a block diagram of another example of the combustion diagnosis device used in the combustion diagnosis method of the present invention.
[Explanation of symbols]
1 optical measuring means (optical fiber probe)
2 Spectroscopic means (spectrometer)
3 photoelectric conversion element 4 operation processing means (operation processing device)

Claims (12)

An optical measuring device for a flame in a combustion device of a gas turbine in which a plurality of burners are arranged in close proximity,
An optical fiber probe which is disposed behind the swirler so as to face a place where the flame faces the wall surface of the combustion chamber from between the blades of the swirler, and whose tip is obliquely cut to have a specific viewing angle. An optical measuring device for a flame, comprising: A combustion diagnostic device in a combustion device of a gas turbine in which a plurality of burners are arranged in close proximity,
Optical measuring means , spectral means , photoelectric conversion element, and arithmetic processing means,
A combustion diagnostic device, wherein the optical measuring means is the optical measuring device according to claim 1 . 3. The combustion diagnostic apparatus according to claim 2 , wherein the arithmetic processing unit holds the relationship between the radical self-luminous intensity ratio present in the flame and the air-fuel ratio in the form of a table or a function. The radical self-luminous intensity ratio is an intensity ratio between OH radical self-luminous intensity and CH radical self-luminous intensity, an intensity ratio between OH radical self-luminous intensity and C ₂ radical self-luminous intensity, or a CH radical self-luminous intensity and C ₂ radical 4. The combustion diagnostic apparatus according to claim 3 , wherein the ratio is an intensity ratio with the self-luminous intensity. A combustion control device comprising the combustion diagnosis device according to claim 2, 3 or 4 . The combustion control device includes an air-fuel ratio control unit, an air flow control unit, and a fuel flow control unit,
The air-fuel ratio control means calculates an air amount and / or a fuel amount of each burner based on a diagnosis result from the combustion diagnosis device, and calculates a control amount of the air flow control means and / or the fuel flow control means. And
The air flow control means controls the air flow of each burner according to the control amount,
The combustion control device according to claim 5, wherein the fuel flow control means controls the fuel flow of each burner according to the control amount. A combustion diagnosis method using the flame optical measuring device according to claim 1,
Combustion diagnostic methods and performing combustion diagnosis based on the I Ri measured radical self-emission intensity in the optical measuring device. The combustion diagnosis method according to claim 7 , wherein the combustion diagnosis is performed by comparing the radical self-luminous intensity with an index indicating a combustion state created in advance. The combustion diagnosis determines the self-luminous intensity ratio of the radical self-luminescence from the measured radical self-luminescence, and then calculates the air-fuel ratio of each burner from the relationship between the radical self-luminous intensity ratio and the air-fuel ratio previously obtained from the value. 9. The combustion diagnosis method according to claim 8 , wherein is calculated. The radical self-luminous intensity ratio is an intensity ratio between OH radical self-luminous intensity and CH radical self-luminous intensity, an intensity ratio between OH radical self-luminous intensity and C ₂ radical self-luminous intensity, or a CH radical self-luminous intensity and C ₂ radical The combustion diagnosis method according to claim 9 , wherein the ratio is an intensity ratio with the self-luminous intensity. A combustion control method, wherein each burner is controlled using the combustion diagnosis method according to claim 7, 8, 9, or 10 . Combustion control method according to claim 11, wherein the air flow rate and / or fuel flow rate of each burner is adjusted by the control.

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