A method and system for detecting temperature distribution of a boiler heating surface based on infrared spectrum

Abstract

The present application belongs to the field of temperature detection, and discloses a kind of boiler heating surface temperature distribution detection method and system based on infrared spectrum, it includes the following steps: S1, the infrared spectrum signal and infrared thermal radiation image in the heating surface area of boiler are collected;S2, infrared spectrum signal is converted into spectral radiance intensity, and from it separates out the spectral radiance intensity absorbed by combustion gas medium in furnace;S3, based on spectral radiance intensity, the infrared emissivity of heating surface is calculated;S4, infrared thermal radiation image is converted into waveband radiance intensity image, combined with the spectral radiance intensity absorbed by combustion gas medium in furnace, obtains the infrared waveband radiance intensity image from heating surface;S5, according to the infrared waveband radiance intensity image from heating surface and the infrared emissivity of heating surface, obtains the temperature distribution of boiler heating surface.The present application can realize accurate on-line measurement of the temperature distribution of boiler heating surface.

Description

Technical Field

[0001] This invention belongs to the field of temperature detection, and more specifically, relates to a method and system for detecting the temperature distribution of a boiler heating surface based on infrared spectroscopy. Background Technology

[0002] The heating surfaces of boilers in thermal power plants mainly include water-cooled walls, superheaters, reheaters, and economizers. Their function is to absorb heat from the flue gas in the furnace to obtain steam with specified parameters (temperature, pressure) and quality. When combustion is unstable in the furnace, the local heat load is too high, or the flame center shifts upwards or is tilted, the heating surfaces are prone to overheating. Similarly, when the heat exchange tubes of the heating surfaces are blocked by foreign objects or have excessive scale buildup, it will cause uneven steam-water distribution and poor steam-water circulation, thus affecting heat transfer performance and causing a significant increase in the temperature of the heating surface tube walls. In severe cases, this can lead to overheating and bursting of the heating surface tubes. Therefore, real-time online monitoring of the heating surface temperature is of great significance for preventing tube wall overheating.

[0003] There are two main types of detection methods for the temperature distribution of heated surfaces. One type involves placing multiple thermocouples, fiber optic temperature sensors, and other contact-type point temperature measurement devices on the unfired side of the heated surface to indirectly determine the overheating situation of the heated surface on the fire-facing side of the furnace. The other type uses non-contact optical measurement methods to directly acquire infrared thermal radiation images of the heated surface inside the furnace. The temperature of the heated surface is obtained by processing the infrared images, such as the widely used infrared thermal imager. However, it should be noted that infrared thermal imagers require knowledge of the emissivity of the measured object within the infrared temperature measurement band to obtain accurate temperatures. However, the emissivity of the heated surface during boiler operation is unknown and varies with temperature. At the same time, particles and gaseous media in the combustion flame inside the furnace also emit strong thermal radiation in the infrared band at high temperatures, which is superimposed on the infrared radiation emitted by the heated surface in the furnace, resulting in a large error in the heated surface temperature results obtained by infrared thermal imagers. To address this issue, patent 202211282353.6 proposes establishing a detection model for the radiation intensity of the heated surface and the flame radiation intensity to obtain radiation information from the heated surface through the flame. However, this method requires extensive and precise radiation imaging calculations. Specifically, it is difficult to determine the energy proportions of the three components: the emission emitted from the boiler heated surface and reflected by the heated surface, the emission emitted from the heated surface and scattered by the flame, and the emission emitted from the heated surface and directly received by the photosensitive element. Obtaining the energy proportions of the three components—the emission emitted from the flame and reflected by the boiler heated surface, the emission emitted from the flame and directly received by the photosensitive element—is also difficult. Therefore, this method is not suitable for industrial applications involving online monitoring of the wall temperature distribution of the heated surface in the boiler on-site environment. Summary of the Invention

[0004] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a method and system for detecting the temperature distribution of boiler heating surface based on infrared spectroscopy, the purpose of which is to achieve accurate online measurement of the temperature distribution of boiler heating surface.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for detecting the temperature distribution of a boiler heating surface based on infrared spectroscopy is proposed, comprising the following steps: S1. Collect infrared spectral signals and infrared thermal radiation images within the boiler's heating surface area; S2. Convert the infrared spectral signal into spectral radiation intensity and separate the spectral radiation intensity absorbed by the combustion gas medium in the furnace from it; S3. Calculate the infrared emissivity of the heated surface based on the spectral radiation intensity; S4. Convert the infrared thermal radiation image into a band radiation intensity image, and combine it with the spectral radiation intensity absorbed by the combustion gas medium in the furnace to obtain an infrared band radiation intensity image from the heated surface. S5. Based on the infrared radiation intensity image from the heated surface and the infrared emissivity of the heated surface, the temperature distribution of the boiler heated surface is obtained.

[0006] As a further preferred option, step S2 includes the following steps: Convert infrared spectral signals into spectral radiance. And determine the wavelength range of the absorption peak based on the spectral radiance. ; Spectral radiation intensity of the heated surface after being absorbed by the combustion gas medium inside the furnace for:

[0007] Spectral radiation intensity absorbed by the combustion gas medium inside the furnace for:

[0008] in, For wavelength, This refers to the detection wavelength range when the spectrometer acquires spectral signals. The spectral radiation intensity of the heated surface that is not absorbed by the combustion gas medium in the furnace is determined by the following method: ( , )and( , The two intervals are close to and Multiple wavelengths corresponding to the spectral radiation intensity are selected on each side, and a fourth-order polynomial is fitted. The result is obtained from the fitted fourth-order polynomial. .

[0009] As a further preferred option, step S3 includes the following steps: Monochromatic emissivity of the furnace heating surface at the spectrometer measurement point Represented as:

[0010] in, wavelength The following spectral radiance:

[0011] wavelength and the temperature of the heated surface at the measuring point Blackbody spectral radiation intensity:

[0012] in, It is Planck's first constant. It is Planck's second constant; exist M wavelengths are selected within the range, corresponding to M monochromatic emissivity data, which are then statistically averaged to obtain the infrared emissivity of the heated surface. :

[0013] in, For the first i Monochromatic emissivity of the furnace heating surface corresponding to each wavelength.

[0014] As a further preferred embodiment, step S3 involves calculating the monochromatic emissivity. relative mean square deviation If the value is less than the preset threshold, continue with the subsequent steps; otherwise, change the position of the spectrometer measurement point and return to step S1.

[0015] As a further preferred option, step S4 includes the following steps: Establish a functional model of chromaticity information and band radiation intensity in infrared thermal radiation images:

[0016] in, The intensity of radiation in the band. For the chromaticity information of infrared thermal radiation images, These are the polynomial fitting coefficients of the model; Indicates the order of the function model; The acquired infrared thermal radiation images are converted into band radiation intensity images based on the function model. ; Then, based on the band radiation intensity image Combined with the spectral radiation intensity absorbed by the combustion gas medium inside the furnace Infrared radiation intensity images from the heated surface were obtained. .

[0017] As a further preferred step, step S4 involves determining the polynomial fitting coefficients of the model. The method is as follows: A series of preset temperatures are used to acquire infrared thermal radiation images of the blackbody furnace and its initial chromaticity information at multiple integration times under each preset temperature. By linearly fitting each integration time at each preset temperature with the corresponding initial chromaticity information, the following linear fitting function is obtained:

[0018] in, For the first time at the preset temperature T k The calibration experiment provides chromaticity information corresponding to different integration times. The integration time; The slope represents the standard chromaticity information obtained from a single calibration experiment. The intercept represents dark noise; The chromaticity information is denoised according to the following formula to obtain the denoised chromaticity information. :

[0019] Then calculate at each preset temperature, n Noise reduction color information in the secondary calibration experiment The average value is the standard chromaticity information of the infrared thermal radiation image of the blackbody furnace. ; Standard chromaticity information And the corresponding band radiation intensity at temperature T, substituting the chromaticity information of the infrared thermal radiation image into the function model of band radiation intensity, the polynomial fitting coefficients of the function model are obtained by solving. .

[0020] As a further preferred embodiment, in step S5, the formula for calculating the temperature distribution of the boiler heating surface is:

[0021] in, For pixels temperature, It is Planck's first constant. It is Planck's second constant. Wavelength; Pixels in an infrared radiation intensity image from a heated surface Infrared band radiation intensity, The infrared emissivity of the heated surface.

[0022] According to another aspect of the present invention, a detection system is provided for implementing the above-described method for detecting the temperature distribution of a boiler heating surface based on infrared spectroscopy, comprising an information acquisition module and a data storage and calculation module, wherein: The information acquisition module is used to implement step S1; the data storage and calculation module includes a processor, a memory, and a computer program stored in the memory and run in the processor. When the processor executes the computer program, it implements steps S2 to S5 and stores the calculated data in the memory.

[0023] As a further preferred embodiment, the information acquisition module includes an infrared imaging lens, a beam splitter, a collimating lens, a spectrometer, and an infrared thermal imager, wherein: The optical axis of the infrared imaging lens is set to be perpendicular to the heating surface of the boiler, and the infrared thermal imager is placed at the optical path output imaging position of the infrared imaging lens; the beam splitter is placed between the infrared imaging lens and the infrared thermal imager, and the beam splitter is at 45° to the optical axis of the infrared imaging lens; the spectrometer is placed in the beam splitter direction.

[0024] As a further preferred embodiment, a display module is also included, which displays the temperature distribution of the boiler heating surface in pseudo-color and / or contour lines.

[0025] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages: 1. This invention combines infrared spectral signals and infrared thermal radiation images. It obtains the emissivity of the heated surface within the measurement wavelength range online through infrared spectral analysis, and then outputs the emissivity data to the infrared thermal imaging temperature measurement method to achieve rapid and accurate online measurement of the temperature distribution of the heated surface.

[0026] 2. This invention is based on infrared spectral information, from which the discontinuous spectral portion from the combustion gas medium in the furnace and the continuous spectral portion from the heating surface are separated to obtain the spectral radiation intensity absorbed by the combustion gas medium in the furnace. Then, combined with infrared thermal radiation images, an infrared band radiation intensity image from the heating surface is obtained. This can reduce the influence of the combustion gas in the furnace on the spontaneous radiation absorption of the boiler heating surface and improve the accuracy of boiler heating surface temperature detection.

[0027] 3. This invention combines the advantages of high spectral resolution of a spectrometer with the advantages of a large imaging range and temperature measurement technology of an infrared camera, enabling industrial applications while significantly improving the accuracy of boiler heating surface temperature calculation. Furthermore, this invention eliminates the need for extensive radiation imaging calculations, and the measuring device has a simple structure and is easy to implement. It is suitable for the accurate detection of temperature distribution on the heating surfaces of thermal power plant boilers, allowing for the observation and measurement of the temperature distribution on the boiler heating surfaces. Attached Figure Description

[0028] Figure 1 This is a flowchart of the boiler heating surface temperature distribution detection method based on infrared spectroscopy, according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the information acquisition module in an embodiment of the present invention; Figure 3 This is a shortwave infrared spectral radiation intensity distribution diagram of the boiler heating surface according to an embodiment of the present invention; Figure 4 This is a spectral radiation intensity distribution diagram of the boiler heating surface after deducting the influence of combustion gas absorption in the furnace, according to an embodiment of the present invention. Figure 5 This is a fourth-order polynomial fitting graph of infrared radiation intensity and standard grayscale value in an embodiment of the present invention. Figure 6 The above is a spectral radiation intensity distribution of the boiler heating surface after deducting the influence of combustion gas absorption in the furnace, obtained by fourth-order polynomial fitting in an embodiment of the present invention. Figure 7 This is a schematic diagram of the detection system structure according to an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0030] This invention provides a method for detecting the temperature distribution of a boiler heating surface based on infrared spectroscopy, such as... Figure 1 As shown, it includes the following steps: S1. Collect infrared spectral signals and infrared thermal radiation images within the boiler's heating surface area.

[0031] Specifically, infrared thermal radiation images of the boiler's heating surface are acquired using an infrared thermal imaging instrument. The position of the infrared thermal imaging lens is adjusted to align with the boiler's heating surface under test, and the camera integration time is adjusted to ensure no image saturation. Infrared thermal radiation images are captured at different integration times. Simultaneously, an infrared spectral signal is acquired from the boiler's heating surface using a spectrometer. In this embodiment, the spectral signal acquired is in the short-wave infrared band, with a wavelength range of [wavelength range missing]. , nm, nm.

[0032] S2. Convert the infrared spectral signal into spectral radiance. This allows for the determination of the spectral radiation intensity absorbed by the combustion gases inside the furnace. .

[0033] S21. Convert the infrared spectral signal into spectral radiance. .

[0034] A blackbody furnace was used as a standard radiant heat source to calibrate the spectrometer. The short-wave infrared spectral signal data of the spectrometer was converted into spectral radiant intensity data to obtain the calibration coefficients. Then the spectral radiance It can be obtained from the spectral signal data of the spectrometer With calibration coefficient get:

[0035] S22, Based on spectral radiation intensity The wavelength range of the absorption peak is determined, the spectral radiation intensity distribution is divided, and then the spectral radiation intensity absorbed by the combustion gas in the furnace is determined. .

[0036] The boiler heating surface can be considered as a ash body, exhibiting continuous spectral emission characteristics. Gas radiation is highly selective for wavelength, possessing both radiative and absorptive capabilities only within specific wavelength ranges. The spectral radiation emitted by the boiler heating surface is absorbed by the combustion gas medium inside the furnace before being received by a spectrometer. Because the combustion gas has specific absorption spectral wavelengths, the obtained spectral radiation intensity data will show obvious absorption peaks, with the wavelength range of these absorption peaks being... . and The spectral radiance data between these points represent the discontinuous spectral radiance distribution after absorption by the combustion gas medium within the furnace. and The spectral radiance data, in addition to the above, is a continuous spectral radiance distribution from the boiler's heating surface. In this embodiment, the spectral radiance distribution of the boiler's heating surface is as follows: Figure 3 As shown, it can be seen =1318.96nm, =1493.74nm.

[0037] The spectral radiation intensity of the heated surface after being absorbed by the combustion gas medium inside the furnace is... and Integrating the radiation intensity across the bands yields:

[0038] In the above formula, The value represents the spectral radiation intensity of the heated surface after being absorbed by the combustion gas medium inside the furnace. The subscript 1 indicates that the data comes from a spectrometer.

[0039] The spectral radiation intensity absorbed by the combustion gas inside the furnace is:

[0040] In the above formula, The intensity of spectral radiation absorbed by the combustion gases in the furnace is measured by the spectrometer, which has a detection range of 1150 nm to 1650 nm in the short-wave infrared. Indicates the boiler heating surface at ~ The spectral radiation intensity that is not absorbed by the combustion gases in the furnace. This indicates the intensity of spectral radiation received by the spectrometer in the short-wave infrared range, excluding the absorption band of combustion gases.

[0041] Furthermore, The method for determining it is as follows: Subtract the continuous spectral signal obtained from the spectrometer and The signal data between, and perform polynomial fitting operation on the remaining spectral signal data, such as in Figure 3 deducting from and After obtaining the signal data between them Figure 4 ,Will Figure 4 The spectral signal data in the data are fitted with a polynomial to the wavelength.

[0042] The specific method is as follows: in (1150, )and( (1650) The two intervals are close to and By selecting 15-20 spectral radiation intensity data points from each side and performing a fourth-order polynomial fitting, the heating surface of the boiler can be obtained. ~ Spectral radiation intensity that is not absorbed by the combustion gases in the furnace exist ~ The fitting formula between them, such as Figure 6 As shown.

[0043] The obtained fourth-order polynomial fitting formula is:

[0044] To ensure the accuracy of subsequent calculations, the above formula is only used in... The range of values ​​is It can be used at any time, in the formula The intercept of the fourth-order polynomial fit (units) ), The coefficients are those of a fourth-order polynomial. The spectral radiance of the boiler heating surface that is not absorbed by the combustion gases in the furnace (unit: ).

[0045] S3. Calculate the emissivity distribution of the heated surface in the short-wave infrared band, and obtain the short-wave infrared emissivity of the heated surface by statistical averaging. .

[0046] S31. Calculate the emissivity distribution of the heated surface in the shortwave infrared band: The temperature of the furnace heating surface at the spectrometer measurement point was calculated using the multi-wavelength method.

[0047] In the above formula: Temperature of the furnace heating surface, in Kelvin (K). ), The number of wavelengths used in the calculation; This is Planck's second constant, with a value of 1.4388 × 10⁻⁶. -16 The unit is watts per square meter (W / m²) ); For the first Wavelength, unit is nanometer (nm) ), i =1,2… M ; The increase in wavelength, expressed in nanometers (nm). ).

[0048] According to Wien's displacement law:

[0049] The monochromatic emissivity of the furnace heating surface at the spectrometer measurement point Can be used at the same temperature T The ratio of lower radiation intensity to blackbody radiation intensity is expressed as:

[0050] In the above formula, wavelength The following spectral radiance:

[0051] wavelength and the obtained temperature Blackbody spectral radiation intensity:

[0052] S32. Obtain the short-wave infrared emissivity of the heated surface through statistical averaging. .

[0053] According to the method in S31, M wavelengths are taken at equal intervals within the short-wave infrared wavelength range of (1150, 1650) to calculate the corresponding M monochromatic emissivity of the furnace heating surface at the spectrometer measurement point. The data is then used to obtain its average value. With relative mean square deviation :

[0054]

[0055] In the above formula, This is the statistical average of the shortwave infrared emissivity of the heated surface. for The relative mean square error, if If the radiation is less than the preset threshold (set to 5% in this embodiment), then the radiation from the boiler's heating surface within the shortwave infrared range of (1150, 1650) can be considered as gray body radiation, and the following steps can continue. If the value is greater than or equal to 5%, the measurement point position of the spectrometer needs to be changed, and the process should return to step S1.

[0056] S4. Convert the infrared thermal radiation image into a band radiation intensity image, and combine it with the spectral radiation intensity absorbed by the combustion gas in the furnace to eliminate the influence of absorption by the combustion gas medium in the furnace, and obtain the infrared band radiation intensity image from the heated surface.

[0057] S41. The infrared thermal imager is calibrated using a blackbody furnace, and then the infrared thermal radiation image is converted into a band radiation intensity image. : S411. Establish chromaticity information of infrared thermal radiation images obtained from infrared thermal imagers. With band radiation intensity The function model is as follows:

[0058] In the above formula, The polynomial fitting coefficients are the first initial function model. is a positive integer representing the order of the function model.

[0059] S412. Set a series of preset temperatures, and obtain short-wave infrared images of the blackbody furnace at each preset temperature for multiple integration times using an infrared thermal imager, along with the initial chromaticity information of each short-wave infrared image. The preset temperatures range from 600℃ to 2200℃, and in principle, should cover all temperatures of the boiler's heating surfaces under operating conditions.

[0060] For each preset temperature: set a series of integration times (usually 8), and repeat the experiment several times for each integration time (usually 3 times); perform linear fitting between each integration time and the corresponding initial chromaticity information to obtain the linear fitting function corresponding to the integration time and initial chromaticity information at each preset temperature:

[0061] In the above formula, To set the temperature T, the first k The calibration experiment provides chromaticity information corresponding to different integration times. For integration time, The slope represents the standard colorimetric information obtained from a single calibration experiment. The intercept represents dark noise.

[0062] Subtract the intercept of the fitting function corresponding to the preset temperature from each initial chromaticity information, and then divide by the integration time corresponding to that initial chromaticity information to obtain the denoised chromaticity information:

[0063] Calculate the average value of the denoised chromaticity information of all calibration experiments at the preset temperature, and use this average value as the standard chromaticity information of the blackbody furnace near-infrared image at the corresponding preset temperature:

[0064] In the above formula, The total number of experiments is calibrated at each preset temperature.

[0065] The above method yielded multiple sets of preset temperatures T and their corresponding standard chromaticity information.

[0066] S413, Obtain the standard chromaticity information of the blackbody furnace near-infrared image obtained in S412. and the corresponding band radiation intensity (Based on temperature T and the wavelength corresponding to the maximum response of the infrared thermal imager) Substitute these values ​​into the function model of S411 to obtain the polynomial fitting coefficients of the function model. ,like Figure 5 As shown; then, based on the function model, the infrared thermal radiation image acquired by S1 is converted into a band radiation intensity image. .

[0067] S42. Based on the band radiation intensity image and the spectral radiation intensity absorbed by the combustion gases in the furnace Determine the infrared radiation intensity image from the heated surface. .

[0068] By adding the radiation intensity of each pixel in the infrared thermal radiation image captured by the short-wave infrared thermal imager to the radiation intensity of the combustion gas medium inside the furnace, the short-wave infrared band radiation intensity image data of each pixel from the heated surface is obtained:

[0069] In the above formula, pixels of an infrared thermal radiation image The intensity of radiation from the heated surface in one band. For pixels The intensity of the band radiation has not been adjusted to account for the absorption of the combustion gas medium inside the furnace.

[0070] Based on the spectral radiation intensity corresponding to each pixel This allows us to obtain the radiation intensity of the entire shortwave infrared image frame of the boiler's heating surface, i.e., the infrared radiation intensity image from the heating surface. .

[0071] S5. Based on the infrared radiation intensity image from the heated surface and the infrared emissivity of the heated surface, the temperature distribution of the boiler heated surface is obtained.

[0072] Based on the law of infrared thermal radiation, a quantitative relationship is established between the radiation intensity of the short-wave infrared band and the short-wave infrared emissivity and temperature.

[0073] Within the shortwave infrared wavelength range of (1150, 1650), according to Wien's displacement law:

[0074] Then, the pixel points in the shortwave infrared image can be obtained by inverse solving the above formula. The expression for temperature:

[0075] The shortwave infrared radiation intensity image data of the heated surface obtained in step S4 and the short-wave infrared emissivity of the heated surface obtained in step S3 Substituting into the above formula, we obtain the temperature distribution of the boiler's heating surface:

[0076] In the above formula, For pixels temperature, This is Planck's first constant, with a value of 3.74 × 10⁻⁶. -16 The unit is watts per square meter (W / m²) ), This is Planck's second constant, with a value of 1.4388 × 10⁻⁶. -16 The unit is watts per square meter (W / m²) ).

[0077] This invention also provides a detection system for implementing the above-described method for detecting the temperature distribution of a boiler heating surface based on infrared spectroscopy, such as... Figure 7 As shown, it includes an information acquisition module, a data storage and calculation module, and a display module, wherein: The information acquisition module is used to implement step S1; The data storage and computing module includes a processor, a memory, and a computer program stored in the memory and executable in the processor. When the processor executes the computer program, it performs steps S2 to S5 and stores the processed data in the memory. The display module shows the temperature distribution of the boiler's heating surface in pseudo-color and / or contour lines.

[0078] Furthermore, such as Figure 2 As shown, the information acquisition module includes an infrared imaging lens, a beam splitter, a collimating lens, a spectrometer, and an infrared thermal imager fixed on a substrate, wherein: An infrared imaging lens is positioned on the outer side of the boiler's heating surface, and an infrared thermal imager is placed at the output imaging position of the infrared imaging lens. A beam splitter is positioned between the infrared imaging lens and the infrared thermal imager, with the beam splitter at a 45° angle to the optical axis of the infrared imaging lens. The spectrometer is positioned along the beam splitter's direction. This arrangement ensures that the spectrometer and the infrared thermal imager receive the same beam of light from the heating surface. Furthermore, to ensure that the signal received by the spectrometer is the self-emission spectrum of the boiler's heating surface along the line of sight, a collimating lens equipped with an optical fiber is connected before the spectrometer's entrance slit, enabling the spectrometer to obtain the intensity of the boiler's self-emission short-wave infrared spectrum. The spectrometer and the infrared thermal imager are connected to the data storage and computing module via their respective interfaces.

[0079] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting the temperature distribution of a boiler heating surface based on infrared spectroscopy, characterized in that, Includes the following steps: S1. Collect infrared spectral signals and infrared thermal radiation images within the boiler's heating surface area; S2. Convert the infrared spectral signal into spectral radiation intensity, and separate the spectral radiation intensity absorbed by the combustion gas medium inside the furnace; including the following steps: Convert infrared spectral signals into spectral radiance. And determine the wavelength range of the absorption peak based on the spectral radiance. ; Spectral radiation intensity of the heated surface after being absorbed by the combustion gas medium inside the furnace for: Spectral radiation intensity absorbed by the combustion gas medium inside the furnace for: in, For wavelength, This refers to the detection wavelength range when the spectrometer acquires spectral signals. The spectral radiation intensity of the heated surface that is not absorbed by the combustion gas medium in the furnace is determined by the following method: ( , )and( , The two intervals are close to and Multiple wavelengths corresponding to the spectral radiation intensity are selected on each side, and a fourth-order polynomial is fitted. The result is obtained from the fitted fourth-order polynomial. ; S3. Calculate the infrared emissivity of the heated surface based on the spectral radiation intensity; including the following steps: Monochromatic emissivity of the furnace heating surface at the spectrometer measurement point Represented as: in, wavelength The following spectral radiance: wavelength and the temperature of the heated surface at the measuring point Blackbody spectral radiation intensity: in, It is Planck's first constant. It is Planck's second constant; exist M wavelengths are selected within the range, corresponding to M monochromatic emissivity data, which are then statistically averaged to obtain the infrared emissivity of the heated surface. : in, For the first i Monochromatic emissivity of the furnace heating surface corresponding to each wavelength; S4. Convert the infrared thermal radiation image into a band radiation intensity image, and combine it with the spectral radiation intensity absorbed by the combustion gas medium in the furnace to obtain an infrared band radiation intensity image from the heated surface. S5. Based on the infrared radiation intensity image from the heated surface and the infrared emissivity of the heated surface, the temperature distribution of the boiler heated surface is obtained.

2. The method for detecting boiler heating surface temperature distribution based on infrared spectroscopy as described in claim 1, characterized in that, Step S3, calculate monochromatic emissivity relative mean square deviation If the value is less than the preset threshold, continue with the subsequent steps; otherwise, change the position of the spectrometer measurement point and return to step S1.

3. The method for detecting boiler heating surface temperature distribution based on infrared spectroscopy as described in claim 1, characterized in that, Step S4 includes the following steps: Establish a functional model of chromaticity information and band radiation intensity in infrared thermal radiation images: in, The intensity of radiation in the band. For the chromaticity information of infrared thermal radiation images, These are the polynomial fitting coefficients of the model; Indicates the order of the function model; The acquired infrared thermal radiation images are converted into band radiation intensity images based on the function model. ; Then, based on the band radiation intensity image Combined with the spectral radiation intensity absorbed by the combustion gas medium inside the furnace Infrared radiation intensity images from the heated surface were obtained. .

4. The method for detecting boiler heating surface temperature distribution based on infrared spectroscopy as described in claim 3, characterized in that, Step S4: Determine the polynomial fitting coefficients of the model. The method is as follows: A series of preset temperatures are used to acquire infrared thermal radiation images of the blackbody furnace and its initial chromaticity information at multiple integration times under each preset temperature. By linearly fitting each integration time at each preset temperature with the corresponding initial chromaticity information, the following linear fitting function is obtained: in, For the first time at the preset temperature T k The calibration experiment provides chromaticity information corresponding to different integration times. The integration time; The slope represents the standard chromaticity information obtained from a single calibration experiment. The intercept represents dark noise; The chromaticity information is denoised according to the following formula to obtain the denoised chromaticity information. : Then calculate at each preset temperature, n Noise reduction color information in the secondary calibration experiment The average value is the standard chromaticity information of the infrared thermal radiation image of the blackbody furnace. ; Standard chromaticity information And the corresponding band radiation intensity at temperature T, substituting the chromaticity information of the infrared thermal radiation image into the function model of band radiation intensity, the polynomial fitting coefficients of the function model are obtained by solving. .

5. The method for detecting boiler heating surface temperature distribution based on infrared spectroscopy as described in any one of claims 1-4, characterized in that, Step S5, the formula for calculating the temperature distribution of the boiler heating surface is: in, For pixels temperature, It is Planck's first constant. It is Planck's second constant. Wavelength; Pixels in an infrared radiation intensity image from a heated surface Infrared band radiation intensity, The infrared emissivity of the heated surface.

6. A detection system for implementing the method for detecting the temperature distribution of a boiler heating surface based on infrared spectroscopy as described in any one of claims 1-5, characterized in that, It includes an information acquisition module and a data storage and computing module, wherein: The information acquisition module is used to implement step S1; the data storage and calculation module includes a processor, a memory, and a computer program stored in the memory and run in the processor. When the processor executes the computer program, it implements steps S2 to S5 and stores the calculated data in the memory.

7. The detection system as described in claim 6, characterized in that, The information acquisition module includes an infrared imaging lens, a beam splitter, a collimating lens, a spectrometer, and an infrared thermal imager, wherein: The optical axis of the infrared imaging lens is set to be perpendicular to the heating surface of the boiler, and the infrared thermal imager is placed at the optical path output imaging position of the infrared imaging lens; the beam splitter is placed between the infrared imaging lens and the infrared thermal imager, and the beam splitter is at 45° to the optical axis of the infrared imaging lens; the spectrometer is placed in the beam splitter direction.

8. The detection system as described in claim 6 or 7, characterized in that, It also includes a display module that displays the temperature distribution of the boiler's heating surface in pseudo-color and / or contour lines.

Images