Combustion diagnostic device, combustion diagnostic system, and combustion diagnostic device program

Abstract

To diagnose a combustion state of a flame with a simple configuration.SOLUTION: A combustion-diagnosing apparatus 3 diagnoses a combustion state of a flame based on an image of the flame captured by a visible light camera 2 and includes: a signal extraction part 33 for extracting signals in one or more specific wavelength bands from the flame portion of the image; and a combustion-diagnosing part 34 for diagnosing the combustion state based on signals in the specific wavelength bands.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for diagnosing the combustion state of a flame, and more particularly to a technique for diagnosing the combustion state of a flame based on an image of the flame captured by a visible light camera. [Background technology]

[0002] Incomplete combustion in various combustion devices, such as thermal power plants and household stoves, reduces combustion efficiency. Furthermore, incomplete combustion releases harmful components such as carbon monoxide, making combustion diagnostics (monitoring) of these devices essential.

[0003] Therefore, a method has been proposed to diagnose the combustion state based on the intensity of emission at specific wavelengths (autoluminescence or spontaneous emission) observed from a flame. Figure 10 is a graph showing an example of the emission spectrum intensity of a flame. Common autoluminescence of flames includes OH radical autoluminescence with a peak at 306 nm, CH radical autoluminescence with a peak at 430 nm, and C2 radical autoluminescence with a peak at 516 nm. By measuring the intensity of these autoluminescences, the combustion state of the flame can be diagnosed.

[0004] Patent Document 1 discloses a method for detecting the state of a flame by spectrally analyzing the light of the flame using a spectrometer and measuring the intensity of the OH radical autoluminescence. Patent Document 2 also discloses a method for detecting the state of a flame by spectrally analyzing the light of the flame using a spectroscopic measuring device and measuring the intensity of the CH radical autoluminescence or the C2 radical autoluminescence. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2005 / 045379 [Patent Document 2] International Publication No. 2008 / 059976 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the technologies described in Patent Documents 1 and 2 require a spectrometer, making it impossible to use inexpensive imaging devices such as visible light cameras.

[0007] In response to this, one might consider using a visible light camera to measure CH radical self-emission and C2 radical self-emission by attaching special filters to the visible light camera lens that allow light in the 430nm band to pass through, and special filters that allow light in the 516nm band to pass through, and then imaging the flame. However, such special filters are expensive, and it is necessary to change the special filters attached to the lens, making it impossible to measure CH radical self-emission and C2 radical self-emission at the same time.

[0008] The present invention was made to solve the above problems, and aims to diagnose the combustion state of a flame with a simple configuration. [Means for solving the problem]

[0009] To solve the above problems, the present invention includes the following embodiments. Section 1. A combustion diagnostic device that diagnoses the combustion state of a flame based on an image of the flame captured by a visible light camera, A signal extraction unit that extracts signals from one or more specific wavelength bands from the flame portion of the aforementioned image, A combustion diagnostic unit that diagnoses the combustion state based on the signal in the specific wavelength band, A combustion diagnostic device equipped with the following features. Section 2. The signal extraction unit is, A G-signal extraction unit that extracts the G-signal, A B signal extraction unit that extracts the B signal, Equipped with, The aforementioned combustion diagnostic unit is The combustion diagnosis device according to claim 1, comprising an equivalence ratio diagnosis unit that diagnoses the equivalence ratio of the fuel of the flame as the combustion state based on the G signal and the B signal. Item 3. The equivalence ratio diagnosis unit calculates the intensities of CH radical spontaneous emission and C2 radical spontaneous emission in the flame from the G signal and the B signal, and diagnoses the equivalence ratio based on the intensities, the combustion diagnosis device according to claim 2. Item 4. The signal extraction unit comprises an R signal extraction unit that extracts an R signal, The combustion diagnosis unit comprises a combustion temperature diagnosis unit that diagnoses the combustion temperature of the flame based on the R signal, the combustion diagnosis device according to claim 1. Item 5. The signal extraction unit comprises an R signal extraction unit that extracts an R signal, The combustion diagnosis unit calculates the intensity of OH radical spontaneous emission in the flame based on the R signal and the equivalence ratio, the combustion diagnosis device according to claim 2. Item 6. The combustion diagnosis unit comprises a combustion speed diagnosis unit that diagnoses the combustion speed of the flame based on the intensity of the OH radical spontaneous emission, the combustion diagnosis device according to claim 5. Item 7. A visible light camera that images the flame, A combustion diagnosis device that diagnoses the combustion state of the flame based on the image of the flame imaged by the visible light camera, A combustion diagnosis system comprising: The combustion diagnosis device is the combustion diagnosis device according to any one of claims 1 to 6, the combustion diagnosis system. Item 8. A combustion diagnosis program that operates a computer as the combustion diagnosis device according to any one of claims 1 to 6.

Advantages of the Invention

[0010] According to the present invention, the combustion state of a flame can be diagnosed with a simple configuration. [Brief explanation of the drawing]

[0011] [Figure 1] This is a block diagram showing the configuration of a combustion diagnostic system relating to one embodiment of the present invention. [Figure 2] This graph shows an example of the photoelectric conversion characteristics of R, G, and B pixels with respect to wavelength. [Figure 3] (a) is a graph showing the spectrum of blackbody radiation according to Planck's law of radiation, and (b) is a magnified graph of a portion of the blackbody radiation spectrum. [Figure 4] This graph shows the relationship between the integral of radiant energy (Int-E) and temperature. [Figure 5] (a) is a graph showing the relationship between the intensity of C2 radical self-emission and the intensity of the G signal, and (b) is a graph showing the relationship between the sum of 0.274 times the intensity of C2 radical self-emission and the intensity of CH radical self-emission and the intensity of the B signal. [Figure 6] This graph shows the relationship between predicted values ​​(horizontal axis) and measured values ​​(vertical axis) based on G and B signals for the ratio of the intensities of CH radical autoluminescence and C2 radical autoluminescence for fuels with different hydrogen blending ratios (α). [Figure 7] This graph shows the relationship between the intensity of the R signal and the measured value of the integral of the flame's radiant energy. [Figure 8] (a) is a graph showing the relationship between the equivalence ratio (horizontal axis) and the intensity of the R signal (vertical axis), and (b) is a graph showing the relationship between the equivalence ratio (horizontal axis) and the intensity of OH radical self-luminescence (vertical axis). [Figure 9] (a) is a graph showing the relationship between the intensity of the R signal (horizontal axis) and the intensity of OH radical self-luminescence (vertical axis), and (b) is a graph that classifies each fuel into a mixture with an equivalent ratio of less than 1 (lean group) and a mixture with an equivalent ratio of 1 or more (rich group) in the graph shown in Figure 9(a). [Figure 10] This graph shows an example of the emission spectral intensity of a flame. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below, and various modifications are possible without departing from its spirit.

[0013] (Overall structure) Figure 1 is a block diagram showing the configuration of a combustion diagnostic system 1 according to one embodiment of the present invention. The combustion diagnostic system 1 includes a visible light camera 2 and a combustion diagnostic device 3.

[0014] Visible light camera 2 is a camera manufactured primarily for the purpose of capturing visible light. Therefore, visible light camera 2 does not include cameras intended for capturing light other than visible light, such as infrared cameras or ultraviolet cameras. However, visible light camera 2 may have the function of detecting infrared light components, which have wavelengths slightly longer than visible light, or ultraviolet light components, which have wavelengths slightly shorter than visible light. Examples of visible light camera 2 include commercially available digital cameras and cameras installed in smartphones, and may also be video cameras capable of capturing moving images.

[0015] (Visible light camera) In this embodiment, the visible light camera 2 is equipped with R pixels, G pixels, and B pixels in its light-receiving section, and generates an image by converting incident light into R signals, G signals, and B signals. The image may be either a still image or a moving image. Figure 2 is a graph showing an example of the photoelectric conversion characteristics of the R pixels, G pixels, and B pixels with respect to wavelength. The photoelectric conversion characteristics vary somewhat depending on the model of the visible light camera 2. Although the visible light camera 2 employs the RGB method, other methods such as the CMYK method, RYYB method, and RGBY method may also be employed.

[0016] In the combustion diagnostic system 1, the fuel to be diagnosed is burned to form a flame, and the visible light camera 2 is positioned so that the flame faces the lens of the visible light camera 2. The fuel is not particularly limited, but in this embodiment, it is city gas, propane gas, hydrogen gas, etc. The shooting environment is preferably a dark place, but it may also be an environment with background light that does not change in brightness over time.

[0017] (Combustion diagnostic device) The combustion diagnostic device 3 is a device that diagnoses the combustion state of a flame based on an image of the flame captured by a visible light camera 2. The combustion diagnostic device 3 can be configured as a general-purpose computer and its hardware configuration includes a processor such as a CPU or GPU (not shown), a main memory such as DRAM or SRAM (not shown), and an auxiliary storage device 30 such as an HDD or SSD. The auxiliary storage device 30 stores various programs for operating the combustion diagnostic device 3, such as the combustion diagnostic program P.

[0018] The combustion diagnostic device 3 comprises, as functional blocks, an image acquisition unit 31, a background light removal unit 32, a signal extraction unit 33, and a combustion diagnostic unit 34. These functional blocks can be implemented in software by the processor of the combustion diagnostic device 3. In this case, each of the above units can be implemented by the processor reading the combustion diagnostic program P stored in the auxiliary storage device 30 into the main storage device and executing it. The combustion diagnostic program P may be downloaded to the combustion diagnostic device 3 via a communication network such as the Internet, or it may be installed in the combustion diagnostic device 3 via a computer-readable non-temporary recording medium such as a CD-ROM on which the combustion diagnostic program P is recorded.

[0019] The image acquisition unit 31 acquires flame image data transferred from the visible light camera 2. The image from the visible light camera 2 may be transferred to the combustion diagnostic device 3 by wired or wireless means, or it may be transferred to the combustion diagnostic device 3 via a recording medium.

[0020] The background light removal unit 32 removes background light from the flame image acquired by the image acquisition unit 31. The auxiliary storage device 30 has a background image previously captured by the visible light camera 2 in an environment without flames stored in it. The background light removal unit 32 generates an image that reflects the brightness of only the flame by subtracting the brightness of each pixel in the background image from the brightness of each pixel in the flame image. Note that if the flame is captured in a dark place, the processing by the background light removal unit 32 may be omitted.

[0021] The signal extraction unit 33 extracts signals of one or more specific wavelength bands from the flame portion of the image. In this embodiment, the signals of specific wavelength bands are three signals: an R signal, a G signal, and a B signal. The signal extraction unit 33 comprises an R signal extraction unit 331 for extracting the R signal, a G signal extraction unit 332 for extracting the G signal, and an R signal extraction unit 333 for extracting the R signal. The functions of the signal extraction unit 33 can also be implemented using commercially available software such as XnConvert.

[0022] The combustion diagnostic unit 34 diagnoses the combustion state of the flame based on signals (R signal, G signal, and B signal) of specific wavelength bands extracted by the signal extraction unit 33. In this embodiment, the combustion diagnostic unit 34 includes a combustion temperature diagnostic unit 341 for diagnosing the combustion temperature of the flame, a combustion rate diagnostic unit 342 for diagnosing the combustion rate of the flame, and an equivalent ratio diagnostic unit 343 for diagnosing the equivalent ratio of fuel in the flame.

[0023] (Equivalent ratio diagnosis) First, the equivalent ratio diagnostic unit 343 will be explained. The equivalent ratio diagnostic unit 343 diagnoses the equivalent ratio of the flame fuel (the mixing ratio of fuel to air) based on the G signal and the B signal. More specifically, the equivalent ratio diagnostic unit 343 calculates the intensities of the CH radical autoluminescence and C2 radical autoluminescence in the flame from the G signal and the B signal, and diagnoses the equivalent ratio based on these intensities. The intensities of the CH radical autoluminescence and C2 radical autoluminescence are calculated as follows.

[0024] Since the CH radical spontaneous emission has a peak at 430 nm, the luminance component of the CH radical spontaneous emission is mainly recorded in the B signal. However, depending on the model of the visible light camera 2, the luminance component of the CH radical spontaneous emission may be recorded in the G signal. Similarly, since the C2 radical spontaneous emission has a peak at 516 nm, the luminance component of the C2 radical spontaneous emission is mainly recorded in the G signal. However, depending on the model of the visible light camera 2, the luminance component of the C2 radical spontaneous emission may be recorded in the B signal.

[0025] Therefore, if the conversion efficiencies of the CH radical spontaneous emission (430 nm) and the C2 radical spontaneous emission (516 nm) recorded as the G signal are denoted as a(G430) and a(G516) respectively, the following equation (1) can be obtained.

[0026] I G =a(G430)*I CH +a(G516)*I C2 ···(1)

[0027] Here, I G is the intensity of the G signal, I CH is the intensity of the signal component due to the CH radical spontaneous emission, and I C2 is the intensity of the signal component due to the C2 radical spontaneous emission.

[0028] Also, if the conversion efficiencies of the CH radical spontaneous emission (430 nm) and the C2 radical spontaneous emission (516 nm) recorded as the B signal are denoted as a(B430) and a(B516) respectively, the following equation (2) can be obtained.

[0029] I B =a(B430)*I CH +a(B516)*I C2 ···(2)

[0030] Here, I B is the intensity of the B signal. Solving equations (1) and (2) simultaneously gives the following equations (3) and (4).

[0031] I C2 =I G / {a(G516)-a(G430)[a(B516) / a(B430)]-I B / {a(B430)[a(G516) / a(G430)]-a(B516)} ···(3) I CH =I G / {a(G430)-a(G516)[a(B430) / a(B516)]-I B / {a(B516)[a(G430) / a(G516)]-a(B430)} ···(4)

[0032] The value of a(B516) / a(B430) on the right side of equation (3) can be determined by imaging a flame with the visible light camera 2, alternating between a filter that transmits only 430nm light and a filter that transmits only 516nm light, and then taking the ratio of the B signal at 430nm to the B signal at 516nm. Similarly, the value of a(G430) / a(G516) on the right side of equation (4) can be determined by imaging a flame with the visible light camera 2, alternating between a filter that transmits only 430nm light and a filter that transmits only 516nm light, and then taking the ratio of the G signal at 430nm to the G signal at 516nm. Therefore, by performing multiple regression analysis, which is the least squares method for two variables, the coefficients a1, b1, a2, and b2 in the following equations (5) and (6) can be determined.

[0033] I C2 =a1*I G -b1*I B ...(5) I CH =a2*I G -b2*I B ...(6)

[0034] In this way, the intensities of the CH radical self-luminescence and the C2 radical self-luminescence can be calculated. Since the ratio of the CH radical self-luminescence intensity to the C2 radical self-luminescence intensity changes according to the fuel equivalence ratio, the equivalence ratio diagnostic unit 343 can predict the equivalence ratio based on the intensities of the CH radical self-luminescence and the C2 radical self-luminescence.

[0035] (Diagnosing combustion temperature) The combustion temperature diagnostic unit 341 diagnoses the combustion temperature of the flame based on the R signal. The inventors have found that the combustion temperature of the flame can be predicted based on the R signal, as follows.

[0036] As shown in Figure 2, the R signal records radiant intensity in approximately the range of 560 nm to 690 nm. Figure 3(a) is a graph showing the blackbody radiation spectrum according to Planck's law of radiation, and Figure 3(b) is a magnified graph of a portion of the blackbody radiation spectrum. Here, if we integrate the radiant energy (E) of each spectrum in the 560 nm to 690 nm band, indicated by F in Figure 3(b), we can obtain the relationship between the integral value of radiant energy (Int-E) and temperature, as shown in Figure 4.

[0037] Figure 4 shows that the integral of radiant energy in the 560nm to 690nm band can be approximated by a quadratic function of temperature. Since the intensity of the R signal is roughly proportional to the integral of radiant energy in the 560nm to 690nm band, it can be seen that there is a high correlation between the R signal and temperature. Based on this correlation, the combustion temperature diagnostic unit 341 can predict the combustion temperature of the flame based on the R signal.

[0038] (Diagnosing combustion rate) The combustion rate diagnostic unit 342 calculates the intensity of OH radical self-luminescence in the flame based on the R signal and the equivalence ratio, and diagnoses the combustion rate of the flame based on the intensity of the OH radical self-luminescence. Since OH radical self-luminescence is ultraviolet light (306 nm), it cannot be detected by the visible light camera 2, but the inventors have found that there is a correlation between the R signal and the intensity of OH radical self-luminescence, as shown in Example 3 described later. Based on this correlation, the intensity of OH radical self-luminescence in the flame can be calculated based on the R signal and the equivalence ratio predicted by the equivalence ratio diagnostic unit 343. Furthermore, since the intensity of OH radical self-luminescence correlates with the combustion rate of the flame, the combustion rate diagnostic unit 342 can predict the combustion rate of the flame based on the intensity of the OH radical self-luminescence.

[0039] (summary) As described above, in this embodiment, the combustion diagnostic device 3 can diagnose the combustion state of the flame (equivalent ratio of fuel in the flame, combustion temperature of the flame, and combustion speed of the flame) based on the flame image captured by the visible light camera 2. In other words, in this embodiment, since a spectrometer and a camera capable of detecting light other than visible light are not required, the combustion state of the flame can be diagnosed with a simple configuration.

[0040] Furthermore, in a configuration where a special filter is attached to the lens of a visible light camera to measure CH radical self-emission and C2 radical self-emission, it is necessary to change the special filter attached to the lens, making it impossible to measure CH radical self-emission and C2 radical self-emission at the same time. In contrast, in this embodiment, the respective intensities of CH radical self-emission and C2 radical self-emission in the flame are calculated from the G signal and B signal extracted from a single image, so CH radical self-emission and C2 radical self-emission can be measured at the same time.

[0041] (Additional notes) The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Forms obtained by appropriately combining the technical means disclosed in the embodiments are also included in the technical scope of the present invention.

[0042] In the above embodiment, the combustion state of the flame was diagnosed by the equivalent ratio of the fuel-air mixture, the combustion temperature of the flame, and the combustion speed of the flame. However, only some of these may be diagnosed. For example, if only the equivalent ratio of the mixture is to be diagnosed, the signal extraction unit 33 may extract only the G signal and the B signal as signals in a specific wavelength band. Also, if only the combustion temperature of the flame is to be diagnosed, the signal extraction unit 33 may extract only the R signal as a signal in a specific wavelength band.

[0043] In the above embodiment, the intensities of CH radical autoluminescence, C2 radical autoluminescence, and OH radical autoluminescence were used as indicators for diagnosing the combustion state. However, the present invention is not limited to these, and for example, the intensities of CN radical autoluminescence or CH3 radical autoluminescence may be used. [Examples]

[0044] In Example 1, we verified whether the fuel equivalent ratio could be diagnosed with high accuracy using the present invention. Specifically, based on the G signal and B signal, the ratio of the intensities of the CH radical autoluminescence and C2 radical autoluminescence used for diagnosing the equivalent ratio was calculated, and the diagnostic accuracy was verified by comparing this with measured values.

[0045] As the visible light camera 2, a Canon EOS 40D digital SLR camera was used to image the flame. A mixture of methane and hydrogen gas was used as the fuel. As the combustion diagnostic device 3, a general-purpose computer was used to calculate the ratio of the intensities of CH radical self-luminescence and C2 radical self-luminescence based on the G signal and B signal.

[0046] The performance of the visible light camera 2 used in this embodiment was verified, and it was confirmed that the conversion efficiency a(G430) at 430 nm recorded as the G signal was 0 (the value of a(G430) / a(G516) in equation (4) was 0), and the value of a(B516) / a(B430) in equation (3) was 0.274. Therefore, equations (7) and (8) were obtained from equations (5) and (6).

[0047] I C2 =I G / a(G516) ···(7) I CH =I B / a(B430)-0.274*I C2 ...(8)

[0048] Figure 5(a) is a graph showing the relationship between the intensity of C2 radical self-luminescence and the intensity of the G signal. The straight line in the graph is derived from equation (7). The markers plotted in the graph show the relationship between the intensity of C2 radical self-luminescence and the intensity of the G signal in flames imaged while varying the hydrogen mixture ratio (α) of the fuel. From the positional relationship between the straight line and each plotted marker, it can be seen that the relationship between the intensity of C2 radical self-luminescence and the intensity of the G signal generally satisfies equation (7) regardless of the hydrogen mixture ratio. In other words, a high correlation was confirmed between the intensity of C2 radical self-luminescence and the intensity of the G signal.

[0049] Figure 5(b) is a graph showing the relationship between the sum of the C2 radical self-luminescence intensity (0.274 times) and the CH radical self-luminescence intensity and the B signal intensity. The straight line in the graph is derived from equation (8). The markers plotted in the graph show the relationship between the sum of the C2 radical self-luminescence intensity (0.274 times) and the CH radical self-luminescence intensity and the B signal intensity in flames imaged while varying the hydrogen mixture ratio (α) of the fuel. From the positional relationship between the straight line and each plotted marker, it can be seen that regardless of the hydrogen mixture ratio, the relationship between the sum of the C2 radical self-luminescence intensity (0.274 times) and the CH radical self-luminescence intensity and the B signal intensity generally satisfies equation (8). In other words, a high correlation was confirmed between the sum of the C2 radical self-luminescence intensity (0.274 times) and the CH radical self-luminescence intensity and the B signal intensity.

[0050] Figure 6 is a graph showing the relationship between predicted values ​​(horizontal axis) and measured values ​​(vertical axis) of the ratio of the intensities of CH radical self-luminescence and C2 radical self-luminescence, based on G and B signals, for fuels with different hydrogen blending ratios (α). The measured values ​​of the intensities of CH radical self-luminescence and C2 radical self-luminescence were obtained by photographing a flame with a high-sensitivity ICCD camera (C9164, Hamamatsu Photonics K.K.) capable of measuring up to ultraviolet light, fitted with a filter that transmits only CH self-luminescence or C2 self-luminescence. Since the plotted marks are located near the straight line indicating that the measured values ​​and predicted values ​​are equal, it was found that the ratio of the intensities of CH radical self-luminescence and C2 radical self-luminescence can be predicted with high accuracy using G and B signals.

[0051] This demonstrates that the fuel equivalent ratio can be diagnosed with high accuracy using the present invention. [Examples]

[0052] In Example 2, we verified whether the present invention could accurately diagnose the combustion temperature of a flame. Specifically, we calculated the integral value of the radiant energy used to diagnose the combustion temperature based on the R signal and verified the diagnostic accuracy by comparing this with the measured value.

[0053] The visible light camera 2 and fuel used in this embodiment were the same as those in Embodiment 1 described above. R signals were extracted from images of flames of fuels with different hydrogen mixing ratios (α), and the intensity of the R signals was obtained. Furthermore, the integral value of the flame's radiant energy was determined by numerically integrating Planck's radiation equation shown below.

number

[0054] Figure 7 is a graph showing the relationship between the intensity of the R signal and the measured integral of the flame's radiant energy. Since the plotted markers are located near the straight line that represents the theoretical relationship between the intensity of the R signal and the integral of the radiant energy, it was found that there is a high correlation between the integral of the radiant energy and the intensity of the R signal.

[0055] This demonstrates that the present invention allows for highly accurate diagnosis of the combustion temperature of a flame. [Examples]

[0056] In Example 3, we verified whether the intensity of OH radical self-luminescence could be predicted with high accuracy from the R signal, G signal, and B signal.

[0057] The visible light camera 2 and fuel used in this embodiment were the same as those in embodiments 1 and 2 described above. R signals were extracted from images of flames of fuels with different hydrogen mixing ratios (α) and equivalent ratios, and the intensity of the R signals was obtained. In addition, the intensity of the OH radical self-luminescence of the flame was measured by attaching a filter that transmits only OH self-luminescence to an ICCD camera capable of measuring ultraviolet light and photographing the flame.

[0058] Figure 8(a) is a graph showing the relationship between the equivalence ratio (horizontal axis) and the intensity of the R signal (vertical axis), and Figure 8(b) is a graph showing the relationship between the equivalence ratio (horizontal axis) and the intensity of OH radical self-luminescence (vertical axis). Comparing these two graphs, their shapes are very similar. Therefore, the inventors investigated the correlation between the intensity of the R signal and the intensity of OH radical self-luminescence.

[0059] Figure 9(a) is a graph showing the relationship between the intensity of the R signal (horizontal axis) and the intensity of OH radical self-luminescence (vertical axis). From this graph, a correlation between the intensity of the R signal and the intensity of OH radical self-luminescence can be observed to some extent.

[0060] Figure 9(b) is a graph that classifies each fuel into two groups based on the graph shown in Figure 9(a): a mixture with an equivalent ratio of less than 1 (lean group) and a mixture with an equivalent ratio of 1 or more (rich group). From Figure 9(b), it was found that the correlation between the intensity of the R signal and the intensity of OH radical self-luminescence is strong when the mixture is divided into the lean group only and the rich group. From the above, it was found that the intensity of OH self-luminescence can be predicted with high accuracy from the R signal.

[0061] As described above, the equivalence ratio can be predicted from the ratio of the intensities of CH radical autoluminescence and C2 radical autoluminescence calculated from the G signal and B signal. Furthermore, it was found that the intensity of OH radical autoluminescence can be predicted with high accuracy from the R signal.

[0062] The reason for the high correlation between the intensity of the R signal and the intensity of OH radical self-luminescence is thought to be as follows.

[0063] OH radicals are the source of the intensity of self-luminescence. * The reaction equation is known to be as follows:

[0064] CH + O2 = CO + OH * ...(9)

[0065] OH * When it transitions to the ground state, light (self-luminescence) is observed due to the following reaction.

[0066] OH * =OH+hν ···(10)

[0067] In the reaction of equation (9), it has been found that O2 has a greater influence than CH. At high temperatures, O2 dissociates into oxygen atoms O, and the wavelengths of the self-luminescence of the O atoms were 557.7 nm and 630 nm. Since these two wavelength bands are included in the wavelength band of the R signal, it is thought that there is a high correlation between the self-luminescence intensity of OH and the intensity of the R signal. [Explanation of Symbols]

[0068] 1. Combustion diagnostic system 2. Visible light camera 3. Combustion diagnostic device 30 Auxiliary storage 31 Image acquisition unit 32 Background light removal section 33 Signal Extraction Unit 331 R signal extraction section 332 G signal extraction unit 333 R signal extraction section 34 Combustion Diagnosis Unit 341 Combustion Temperature Diagnostic Unit 342 Combustion Rate Diagnostic Unit 343 Equivalent Ratio Diagnostic Department

Claims

1. A combustion diagnostic device that diagnoses the combustion state of a flame based on an image of the flame captured by a visible light camera, A signal extraction unit that extracts signals from one or more specific wavelength bands from the flame portion of the aforementioned image, A combustion diagnostic unit that diagnoses the combustion state based on the signal in the specific wavelength band, Equipped with, The signal extraction unit is, It is equipped with an R signal extraction unit that extracts the R signal, The aforementioned combustion diagnostic unit is A combustion diagnostic device comprising a combustion temperature diagnostic unit that diagnoses the combustion temperature of the flame based solely on the intensity of the R signal.

2. A combustion diagnostic device for diagnosing the combustion state of a flame based on an image of the flame captured by a visible light camera, A signal extraction unit that extracts signals from one or more specific wavelength bands from the flame portion of the aforementioned image, A combustion diagnostic unit that diagnoses the combustion state based on the signal in the specific wavelength band, Equipped with, The signal extraction unit is, A G signal extraction unit that extracts the G signal, A B signal extraction unit that extracts the B signal, An R signal extraction unit that extracts the R signal, Equipped with, The aforementioned combustion diagnostic unit is Based on the G signal and the B signal, the system includes an equivalent ratio diagnostic unit that diagnoses the equivalent ratio of the fuel in the flame as the combustion state. A combustion diagnostic device that calculates the intensity of OH radical self-luminescence in the flame based on the R signal and the equivalent ratio.

3. The equivalent ratio diagnostic unit is, The combustion diagnostic device according to claim 2, which calculates the intensity of the CH radical self-luminescence and C2 radical self-luminescence in the flame from the G signal and the B signal, and diagnoses the equivalent ratio based on the intensity.

4. The aforementioned combustion diagnostic unit is The combustion diagnostic device according to claim 2, further comprising a combustion rate diagnostic unit for diagnosing the combustion rate of the flame based on the intensity of the self-luminescence of the OH radicals.

5. A visible light camera that captures images of flames, A combustion diagnostic device that diagnoses the combustion state of the flame based on an image of the flame captured by the visible light camera, A combustion diagnostic system comprising, The combustion diagnostic device is the combustion diagnostic device according to any one of claims 1 to 4, wherein the combustion diagnostic device is a combustion diagnostic device.

6. A combustion diagnostic program that causes a computer to operate as a combustion diagnostic device according to any one of claims 1 to 4.

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