CN114047154B - A device and method for online measurement of burnout degree of pulverized coal boilers based on spectral analysis - Google Patents

Abstract

The invention discloses a device and a method for online measuring the burnout degree of a pulverized coal boiler based on spectral analysis. The device includes a detection device and a computer equipped with control software; the detection device includes two front and rear cavities. When the front cavity is far away from the rear An opening is provided on the side of the cavity, and an armored optical fiber extending along its length is provided in the front cavity. A collimating lens is provided at an end of the armored optical fiber away from the rear cavity and corresponding to the opening. The armored optical fiber The other end is connected to the spectrometer in the rear cavity, and the spectrometer and the computer communicate through a serial bus connection. The device disclosed in this application has a simple structure and can be used with a computer to detect the burnout degree of coal near the center of the furnace in situ and obtain real-time combustion rate and apparent kinetic parameters.

Description

A device and method for online measurement of burnout degree of pulverized coal boilers based on spectral analysis

Technical field

The invention belongs to the technical field of coal combustion analysis research, and specifically relates to a device and method for online measuring the burnout degree of a pulverized coal boiler based on spectral analysis.

Background technique

Coal has always been an important primary energy source supporting my country's economic and social development. The efficient and clean utilization of coal has far-reaching significance for the sustainable development of the economy and ecology. Coal resources occupy a very critical position in my country's total energy and play an effective role in supporting the rapid development of the national economy. The normal operation of the power station boiler is the basis for the safe operation of the power station. The combustion state of coal is related to the operation of the boiler. Therefore, it is extremely important to quickly, timely and accurately judge the combustion state in the furnace of the power station boiler.

For coal-fired power generating units, the calorific value of coal coke can account for 95% of the total calorific value of coal, and the burnout time of coal coke accounts for more than 90% of the total combustion time. Therefore, the combustion efficiency and burnout time of coal are mainly determined by the coal. Determined by coke, the degree of burnout of coal coke in the furnace largely determines the degree of utilization of pulverized coal. The degree of burnout of coal coke is an important indicator to measure the degree of utilization of pulverized coal. This requires that the degree of coal coke burnout in the actual combustion process Burn as completely as possible in the shortest possible time. According to the burnout detection results at different heights in the furnace, the combustion of coal char in the furnace can be better organized, the efficiency of pulverized coal combustion can be improved, the usage of coal can be reduced, and the pressure of _CO2 emission reduction can be reduced.

The current research method for investigating the burnout degree of pulverized coal furnaces is mainly the along-process sampling method. This method calculates the corresponding burnout degree based on the component changes of coal char collected at different heights. Chinese patent CN 105527255 A discloses a method of coal feeding into the furnace. The quality characteristics online monitoring system includes a sampling unit, a plasma spectrum analysis unit, a sample storage unit, a three-way particle flow measurement unit and a sample return unit. This system can effectively analyze the coal quality characteristics, but the sampling tube of this method The road is relatively complicated, there are many inconveniences in the experiment, and there is a lack of detection and analysis of the boiler burnout degree. It is impossible to achieve online real-time detection, and it is impossible to obtain real-time combustion rate and apparent kinetic parameters.

The commonly used calculation method for burnout degree is mainly the ash tracer method. This method assumes that the ash content in the coal sample remains unchanged before and after combustion, and calculates the precipitation ratio of combustibles in coal based on the change in ash mass fraction before and after combustion, that is, the burnout degree. This detection method can only collect the burnout degree of coal char near the sampling point (fire observation hole), and cannot detect the burnout degree of coal char near the center of the furnace. The detection results cannot represent the overall level of burnout degree at the detection height. , and it is impossible to detect in situ in real time to obtain real-time combustion rate and apparent kinetic parameters.

Contents of the invention

The object of the present invention is to provide a device and method for online measurement of the burnout degree of a pulverized coal boiler based on spectral analysis. The device has a simple structure and can be used with a computer to detect the burnout degree of coal near the center of the furnace in situ and obtain the real-time combustion rate. and apparent kinetic parameters.

The technical solution of the present invention is: a device for online measuring the burnout degree of pulverized coal boilers based on spectral analysis, including a detection device and a computer equipped with control software; the detection device includes two front and rear cavities, and the front cavity is far away from the rear cavity. There is an opening on the side of the body, and an armored optical fiber extending along its length is provided in the front cavity. A collimating lens is provided at the end of the armored optical fiber away from the rear cavity and corresponding to the opening. The armored optical fiber is The other end is connected to the spectrometer in the rear cavity, and the spectrometer and the computer communicate through a serial bus connection.

Further, a quartz lens is installed at the opening.

Further, the armored optical fiber is fixed in the front cavity through a support frame. The cavity shells of the front cavity and the rear cavity are made of 304 stainless steel; there is a handle at the lower end of the rear cavity and a handle at the upper end.

The method of measuring the burnout degree of a pulverized coal boiler using the above-mentioned device for online measurement of the burnout degree of a pulverized coal boiler based on spectral analysis mainly includes the following steps:

S1: Assemble the detection device, connect the computer using the serial bus, and insert the front cavity of the detection device into the fire observation hole;

S2: The light inside the furnace is transmitted to the spectrometer through the armored optical fiber. The spectrometer collects spectral images of the combustion conditions of the pulverized coal furnace in the power station. The appropriate integration time is adjusted during the acquisition process. After the image data acquisition is completed, the image information is transmitted to the computer, and the program on the computer Data processing through algorithms;

S3: Using the collected spectral distribution diagram of each layer of the pulverized coal furnace, calculate the temperature and emissivity distribution image of the furnace cross-section according to the spectral radiation intensity, and use the function model of spectral emissivity, temperature, and burnout degree Calculate the pulverized coal burnout degree of coal char particles at different temperatures and different spectral emissivities;

S4: Change the probe position of the detection device, repeat the above steps S1, S2, and S3 to obtain the temperature and emissivity distribution diagram of the pulverized coal furnace under different working conditions, and calculate the burnout degree of the pulverized coal.

Further, in step S3, the function model is mentioned It is established based on the following steps:

1) According to the thermal radiation theorem, obtain the expression of the spectral radiation intensity of single particle coal char;

2) Use a spectrometer to collect the radiation spectrum of coal char particles in the 200-1100nm band;

3) Divide the spectral response band into multiple narrow spectral bands, obtain the spectral radiation intensity in each narrow spectral band and perform normalization processing;

4) According to the divided narrow spectral bands of visible light, obtain the blackbody radiation intensity in each narrow spectral band and perform normalization processing;

5) The normalized measured spectral radiation intensity and the normalized black body radiation intensity at the same temperature have similar distribution characteristics. Compare them at different temperatures and calculate the spectral radiation intensity and Planck black body radiation of the actual object according to the least squares method. The difference between intensities, a smaller coefficient gives a stronger correlation; obtain the minimum distance between the spectral intensity curve in the narrow-band spectral window and the Planck blackbody radiation curve at different temperatures, and the corresponding temperature at this time is the current The corresponding measured temperature in the spectral window;

6) Divide the processed spectral radiation intensity and blackbody radiation intensity to obtain the spectral emissivity in the thermal radiation band;

7) Obtain the burnout degree of pulverized coal according to the along-process sampling method. Based on the obtained temperature, emissivity and burnout degree, establish the relationship between the three and obtain the function model of spectral emissivity, temperature and burnout degree.

Further, in step 1), according to the thermal radiation theorem, the spectral radiation intensity of single particle coal char is obtained and expressed as:

In formula (1), I _b (λ _i , T) is the blackbody radiation intensity, W/m ^-3 ; I (λ _i , T) is the spectral radiation intensity, W/m ^-3 ; ε (λ _i ) is the coal Spectral emissivity of char particles; T is the temperature of char particles, ℃; C ₁ is Planck’s first radiation constant, 1.1910×10 ⁸ W·μm ⁴ ·m ^-2 ·sr ^-1 ; λ _i is the wavelength, m; n is the number of wavelengths; C ₂ is Planck’s second radiation constant, 1.4388×10 ^{- 2} m·K.

Further, in step 3), the spectral response band is divided into M narrow-band spectral windows. There are i wavelengths in each narrow-band spectrum. For the m-th narrow spectrum, there are

I _m =[I (λ ₁ , T _m ), I (λ ₂ , T _m ),...I (λ _i , T _m )], m=1, 2,...M (2)

In formula (2), I _m is the spectral radiation intensity in the m-th narrow spectrum band, W/m ³ . The spectral radiation intensity in the narrow spectrum band is normalized as:

In formula (3), I′(λ _i , T _m ) is the normalized spectral radiation intensity distribution within the narrow band interval;

In step 4), the standard Planck blackbody radiation intensity matrix I′ _b (λ _i , T _m ) is normalized in the narrow band as:

In formula (4), b represents a black body, T ₁ , T ₂ ,...T _m represents the possible temperature range of coal char particles.

Further, in step 5), the minimum value is calculated according to the least squares method. The specific calculation is as follows:

For any element n=1, 2,...,N; the temperature T _m corresponding to the minimum distance is calculated as follows:

T ₁ , T ₂ ,...T _N represent the possible temperature range of coal char particles.

Further, in step 6), the spectral emissivity in the thermal radiation band is

Further, in step 7), the specific formula for the burnout degree of pulverized coal is obtained according to the along-process sampling method as follows:

B is the burnout degree, A is the ash mass fraction during the combustion process of pulverized coal, and A ₀ is the initial ash mass fraction of pulverized coal. Based on the obtained temperature, emissivity and burnout degree, the relationship between the three is established:

Let the undetermined coefficient matrix be

Then the burnout degree B of pulverized coal particles can be expressed as the average surface emissivity in the 200-1100nm band and a function of temperature T:

in, Through formula (7), it can be obtained that the pulverized coal particles corresponding to different burnout degrees B _m = [B ₁ B ₂ B ₃ ... B _m ] and combustion temperatures T _m = [T ₁ T ₂ T ₃ ... T _m ] are in the range of 200 ~ Average surface emissivity in the 1100nm band The undetermined coefficient matrix A can be obtained through binary nonlinear regression. When detecting the burnout degree of boiler pulverized coal, the pulverized coal flame combustion temperature measured through equations (6) and (7) and the average value in the 200-1100nm band By bringing the surface emissivity into equation (9), the burnout degree of the pulverized coal flame in the furnace can be obtained.

Compared with the existing technology, the present invention has the following advantages:

1. The pulverized coal boiler burnout degree detection device proposed in this application based on spectral analysis can realize online detection of the pulverized coal boiler burnout degree. According to the radiation spectrum of coal char in the visible light band (200nm-1100nm), it is calculated through spectral analysis The surface temperature and emissivity of coal char particles are used to obtain the spectral emissivity distribution of coal char particles in the thermal radiation band. Under the condition of known temperature and emissivity, the coal char burnout degree can be calculated, and on this basis, the coal char burnout degree can be calculated. The relationship between different heights and different burnout degrees in the powder furnace;

2. Compared with the existing technology, the disclosed solution of this application can realize online real-time detection and obtain real-time combustion rate and apparent kinetic parameters;

3. The detection device disclosed in this application can go deep into the fire observation hole of the boiler to obtain a better field of view and keep the spectrometer in the rear cavity away from high temperatures. By controlling the spectrometer in the rear cavity of the detector through a computer, spectral data can be collected and calculated. The powder burns completely and the convenience of use is significantly improved.

Description of the drawings

Figure 1 is a schematic structural diagram of a device for online measurement of burnout degree of pulverized coal boilers based on spectral analysis;

Figure 2 is a schematic diagram of the experimental device for detecting spectral signals of coal char particles on a drop tube furnace;

Figure 3 is a schematic diagram of a field test using the device shown in Figure 1 for measurement;

Figure 4 is the actual measurement diagram on site;

Figure 5 shows the spectral response curve and emissivity under the same load;

Figure 6 is a flame image collected on site.

Among them, 1-detection device, 2-computer;

11-front cavity, 12-rear cavity, 13-opening, 14-armored optical fiber, 15-support frame, 16-collimating lens, 17-spectrometer, 18-grip, 19-handle;

Detailed ways

The technical solution of the present invention will be further described below in conjunction with the accompanying drawings, but it is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be covered by the present invention. within the scope of protection.

In order to successfully and reliably detect the burnout degree of coal coke near the center of the furnace, this embodiment discloses a device for online measurement of the burnout degree of pulverized coal boilers based on spectral analysis. Its structure is shown in Figure 1. It mainly consists of It consists of a detection device 1 and a computer 2 equipped with control software.

The detection device 1 includes two front and rear cavities. The front cavity 11 and the rear cavity 12 are integrally formed. The cavity shell is made of 304 stainless steel and can withstand high temperatures.

The front cavity 11 is a long columnar structure to ensure that it can penetrate into the center of the boiler furnace. There is an opening 13 on the side of the front cavity 11 away from the rear cavity 12. The opening 13 is equipped with a quartz lens to protect the lens. The front cavity 11 is provided with an armored optical fiber 14 extending along its length direction. The armored optical fiber 14 is fixed in the front cavity 11 through a support frame 15 . An end of the armored optical fiber 14 away from the rear cavity 12 is provided with a collimating lens. 16. The setting position of the collimating lens 16 corresponds to the position of the opening 13, which can ensure that the parallel light entering the armored optical fiber 14 is the parallel light in the direction in which the probe is facing. The other end of the armored optical fiber 14 is connected to the spectrometer 17 in the rear cavity 12 .

The front cavity 11 extends into the boiler's flame viewing hole and is aligned with the furnace area where the burnout degree needs to be detected, thereby obtaining a better view and ensuring that the spectrometer 17 in the rear cavity 12 can stay away from high temperatures. The spectrometer 17 is connected to the computer 2 through a serial bus, and the spectral response range is 200-1100nm. The collected spectral data are recorded and processed by the computer 2 to calculate the burnout degree of the pulverized coal.

In addition, for the convenience of operation, a handle 18 is provided at the lower end of the rear cavity 12 and a handle 19 is provided at the upper end for easy carrying and inspection.

The principle of calculating the burnout degree of pulverized coal based on spectral analysis is as follows:

The spectral signal collected by the detection device 1 is mainly composed of the continuous spectrum generated by the thermal radiation of coal char in the furnace and the characteristic spectrum of alkali metals. When calculating the spectral emissivity, spectral analysis should first be performed. After eliminating the characteristic spectra of alkali metals, polynomials can be used to simulate The combined spectral separation algorithm eliminates the influence of non-coal thermal radiation and obtains the continuous spectrum produced by coal thermal radiation.

According to the thermal radiation theorem, the spectral radiation intensity of single particle coal char can be expressed as:

In formula (1), I _b (λ _i , T) is the blackbody radiation intensity, W/m ^-3 ; I (λ _i , T) is the spectral radiation intensity, W/m ^-3 ; ε (λ _i ) is the coal Spectral emissivity of char particles; T is the temperature of char particles, ℃; C ₁ is Planck’s first radiation constant, 1.1910×10 ⁸ W·μm ⁴ ·m ^-2 ·sr ^-1 ; λ _i is the wavelength, m; n is the number of wavelengths; C ₂ is Planck’s second radiation constant, 1.4388×10- ² m·K.

The spectral response band is divided into M narrow-band spectral windows. There are i wavelengths in each narrow spectral band. For the m-th narrow spectrum, there are

I _m =[I (λ ₁ , T _m ), I (λ ₂ , T _m ),...I (λ _i , T _m )], m=1, 2,...M (2)

In formula (2), I _m is the spectral radiation intensity in the m-th narrow spectrum band, W/m ³ . The spectral radiation intensity in the narrow spectrum band is normalized as:

In formula (3), I′(λ _i , T _m ) is the normalized radiation intensity distribution within the narrow spectrum band. In the same way, the standard Planck blackbody radiation intensity is normalized within the mth narrow spectrum band. The matrix is:

In formula (4), b represents a black body, T ₁ , T ₂ ,...T _m represents the possible temperature range of coal char particles. Compare at different temperatures and calculate the minimum value according to the least squares method. The specific calculation is as follows :

For any element n=1, 2,...,N, use the least squares method to calculate the difference between the spectral radiation intensity of the actual object and the Planck blackbody radiation intensity. The greater the error between the curves, the greater the spectral radiation intensity curve measured by the spectrometer. The correlation with the standard Planck radiation intensity curve is weaker. On the contrary, smaller coefficients give stronger correlations.

When the distance difference in the spectrum window is minimized, the corresponding temperature T _N is the corresponding measured temperature in the current spectrum window. In equation (6), T ₁ , T ₂ ,..., T _N represent the possible temperature range of the coal char particles. , these N elements represent the distance between the measured spectral intensity curve in the narrow-band spectral window and the Planck blackbody radiation curve at different temperatures, that is, the temperature corresponding to the minimum distance is the desired temperature:

Each row of the matrix in equation (4) represents the normalized standard Planck radiation intensity at different wavelengths, and each column represents the standard Planck radiation intensity at the same wavelength at different temperatures, then the spectrum in the thermal radiation band Emissivity

This implementation requires obtaining the spectral emissivity of coal particles at different temperatures and different burnout degrees through the above algorithm. The required data are collected experimentally on a dropper furnace. The experiment will be carried out on the device shown in Figure 2. The specific experimental steps are as follows:

1. Select five commonly used domestic bituminous coals: Shendong coal (non-caking coal, long-flame coal), Datong coal (weak-caking coal), Zhungeer coal (long-flame coal), Tiefa coal (long-flame coal) , Jingyuan coal (non-sticking coal), uses a tube furnace to prepare coal coke particles with different burnout degrees, and sieves the prepared coal coke into single particles;

2. Use a dropper furnace to generate a high-temperature environment, set the furnace to _N2 atmosphere, set the furnace temperature to 1400K, and use a platinum-rhodium filament thermocouple to measure the temperature distribution of the reaction section in the furnace under _N2 atmosphere;

3. Use a syringe to inject single particle coal char into the single particle injection hole, and use a fiber spectrometer to collect spectral data from the visualization window of the dropper furnace;

4. Adjust the proportion of air to achieve temperature control. The temperature at the visual window position of the dropper furnace under each working condition is measured by a platinum-rhodium filament thermocouple to verify the accuracy of spectral temperature measurement;

5. Measure the spectral data at different temperatures, and use the algorithm described above to obtain the spectral emissivity distribution under each working condition. The specific formula for the burnout degree of pulverized coal based on the along-process sampling method is as follows:

B is the burnout degree, A is the ash mass fraction during the combustion process of pulverized coal, and A ₀ is the initial ash mass fraction of pulverized coal.

Based on the obtained temperature, emissivity and burnout degree, establish the relationship between the three:

Let the undetermined coefficient matrix be

Then the burnout degree B of pulverized coal particles can be expressed as the average surface emissivity in the 200-1100nm band and a function of temperature T:

in, Through formula (7), it can be obtained that the pulverized coal particles corresponding to different burnout degrees B _m =[B ₁ B ₂ B ₃ ...B _m ] and combustion temperatures T _m =[T ₁ T ₂ T ₃ ...T _m ] are in the range of 200~ Average surface emissivity in the 1100nm band The undetermined coefficient matrix A can be obtained through binary nonlinear regression. When detecting the burnout degree of boiler pulverized coal, the pulverized coal flame combustion temperature measured through equations (6) and (7) and the average value in the 200-1100nm band The surface emissivity is brought into equation (9), and the burnout degree of the pulverized coal flame in the furnace can be obtained.

6. By repeating experiments with different coal types, the burnout degree of different pulverized coals can be directly calculated.

The above burnout degree measurement method may include the following steps during on-site measurement (refer to Figure 3):

S1: After installing the pulverized coal furnace measuring device and connecting to the computer using the serial bus, the entire system starts to run. Insert the front end of the front cavity of the measuring device equipped with armored optical fiber into the fire observation hole. In order to prevent the fire observation hole from erupting If the operator is burned by high-temperature gas or pulverized coal, a fire-retardant plate can be installed at the fire observation hole;

S2: The light inside the furnace is transmitted to the spectrometer through the armored optical fiber. The spectrometer collects the spectral image of the combustion status of the pulverized coal furnace in the power station. The appropriate integration time can be adjusted during the acquisition process to ensure that the spectral image data collected by the spectrometer is not saturated and has high performance. After the image data collection is completed, the image information is transmitted to the computer through the serial bus transmission function, and the program on the computer performs data processing through algorithms;

S3: Use the collected spectral distribution diagram of each layer of the pulverized coal furnace to calculate the temperature and emissivity distribution image of the furnace cross-section based on the spectral radiation intensity. Use the function model of spectral emissivity, temperature, and burnout degree obtained from the above experiments. The pulverized coal burnout degree of coal char particles under different temperatures and different spectral emissivities was calculated.

S4: Change the probe position of the detection device and repeat the above steps 1, 2, and 3 to obtain the temperature and emissivity distribution diagrams of the pulverized coal furnace under different working conditions, and calculate the burnout degree of the pulverized coal.

Figure 4 shows the on-site measurement chart. Based on the on-site data collected by the spectrometer, the electrical signal is converted into radiation intensity, and then converted into absolute radiation intensity through the calibration of the blackbody furnace. The above algorithm is used to calculate the flame temperature and emissivity. Figure 5 is Six typical spectral curves under the same load were selected from the spectral data collected on site and the calculated spectral emissivity of the flame at different wavelengths.

As can be seen from Figure 5, there are several spectral bumps on the spectral curve, and these bumps are distributed within the narrow band range of the spectral curve. According to the query of the spectral database, it can be known that the radiation spectrum at the convex position is the atomic emission spectrum line excited by the heat of the alkali metal element. The characteristic spectral line at 590nm comes from the alkali metal Na, and the characteristic spectral lines at 766.5nm and 769.9nm come from Alkali metal K.

The flame images shown in Figure 6 are images under different integration times. It can be seen that the brightness of the flame is different depending on the integration time. According to the algorithm, the temperature and average emissivity are as follows:

The above are the calculation results of the spectral data of a layer of flame. Based on the experimentally established functional model of spectral emissivity, temperature and burnout degree of coal char particles in the 200nm-1100nm band Calculate burndown. According to the detection device and method proposed by the present invention, online detection of burnout degrees at different heights and regions in the furnace can be achieved, and burnout degree distribution images corresponding to different heights can be established according to different working conditions. After computer processing, the burnout degree in the furnace can be further obtained. The relationship between degree and height.

The above are only examples of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the description and drawings of the present invention, or directly or indirectly applied to other related technologies fields are equally included in the scope of patent protection of the present invention.

Claims (3)

1. A method for measuring the burnout degree of a pulverized coal boiler using a device for online measuring the burnout degree of a pulverized coal boiler based on spectral analysis, characterized in that the device includes a detection device and a computer equipped with control software; The detection device includes two front and rear cavities. An opening is provided on the side of the front cavity away from the rear cavity. An armored optical fiber extending along its length direction is provided in the front cavity. The armored optical fiber is located away from the rear cavity. One end of the optical fiber is equipped with a collimating lens at the position corresponding to the opening, and the other end of the armored optical fiber is connected to the spectrometer in the rear cavity. The spectrometer and the computer communicate through a serial bus connection; The measurement process includes the following steps: S1: Assemble the detection device, connect the computer using the serial bus, and insert the front cavity of the detection device into the fire observation hole; S2: The light inside the furnace is transmitted to the spectrometer through the armored optical fiber. The spectrometer collects spectral images of the combustion conditions of the pulverized coal furnace in the power station. The appropriate integration time is adjusted during the acquisition process. After the image data acquisition is completed, the image information is transmitted to the computer, and the program on the computer Data processing through algorithms; S3: Using the collected spectral distribution diagram of each layer of the pulverized coal furnace, calculate the temperature and emissivity distribution image of the furnace cross-section according to the spectral radiation intensity, and use the function model of spectral emissivity, temperature, and burnout degree Calculate the pulverized coal burnout degree of coal char particles at different temperatures and different spectral emissivities; S4: Change the probe position of the detection device, repeat the above steps S1, S2, and S3 to obtain the temperature and emissivity distribution diagram of the pulverized coal furnace under different working conditions, and calculate the burnout degree of the pulverized coal; Function model mentioned in step S3 It is established based on the following steps: 1) According to the thermal radiation theorem, obtain the expression of the spectral radiation intensity of single particle coal char; 2) Use a spectrometer to collect the radiation spectrum of coal char particles in the 200-1100nm band; 3) Divide the spectral response band into multiple narrow spectral bands, obtain the spectral radiation intensity in each narrow spectral band and perform normalization processing; 4) According to the divided narrow spectral bands of visible light, obtain the blackbody radiation intensity in each narrow spectral band and perform normalization processing; 5) The normalized measured spectral radiation intensity and the normalized black body radiation intensity at the same temperature have similar distribution characteristics. Compare them at different temperatures and calculate the spectral radiation intensity and Planck black body radiation of the actual object according to the least squares method. The difference between intensities, a smaller coefficient gives a stronger correlation; obtain the minimum distance between the spectral intensity curve in the narrow-band spectral window and the Planck blackbody radiation curve at different temperatures, and the corresponding temperature at this time is the current The corresponding measured temperature in the spectral window; 6) Divide the processed spectral radiation intensity and blackbody radiation intensity to obtain the spectral emissivity in the thermal radiation band; 7) Obtain the burnout degree of pulverized coal according to the along-process sampling method. Based on the obtained temperature, emissivity and burnout degree, establish the relationship between the three and obtain the function model of spectral emissivity, temperature and burnout degree. In step 1), according to the thermal radiation theorem, the spectral radiation intensity of single particle coal char is obtained as: In formula (1), I _b (λ _i , T) is the blackbody radiation intensity, W/m ^-3 ; I (λ _i , T) is the spectral radiation intensity, W/m ^-3 ; ε (λ _i ) is the coal Spectral emissivity of char particles; T is the temperature of char particles, ℃; C ₁ is Planck’s first radiation constant, 1.1910×10 ⁸ W·μm ⁴ ·m ^-2 ·sr ^-1 ; λ _i is the wavelength, m; n is the number of wavelengths; C ₂ is Planck’s second radiation constant, 1.4388×10 ^-2 m·K; In step 3), the spectral response band is divided into M narrow-band spectral windows. There are i wavelengths in each narrow-band spectrum. For the m-th narrow spectrum, there are I _m =[I (λ ₁ , T _m ), I (λ ₂ , T _m ),...I (λ _i , T _m )], m=1, 2,...M (2) In formula (2), I _m is the spectral radiation intensity in the m-th narrow spectrum band, W/m ³ . The spectral radiation intensity in the narrow spectrum band is normalized as: In formula (3), I′(λ _i , T _m ) is the normalized spectral radiation intensity distribution within the narrow band interval; In step 4), the standard Planck blackbody radiation intensity matrix I′ _b (λ _i , T _m ) is normalized in the narrow band as: In formula (4), b represents a black body, T ₁ , T ₂ ,...T _m represents the possible temperature range of coal char particles; In step 5), the minimum value is calculated according to the least squares method. The specific calculation is as follows: For any element n=1, 2,...,N; the temperature T _m corresponding to the minimum distance is calculated as follows: T ₁ , T ₂ ,...T _N represent the possible temperature range of coal char particles; In step 6), the spectral emissivity in the thermal radiation band is In step 7), the specific formula for the burnout degree of pulverized coal is obtained according to the along-process sampling method as follows: B is the burnout degree, A is the ash mass fraction during the combustion process of pulverized coal, and A ₀ is the initial ash mass fraction of pulverized coal. Based on the obtained temperature, emissivity and burnout degree, the relationship between the three is established: Let the undetermined coefficient matrix be Then the burnout degree B of pulverized coal particles can be expressed as the average surface emissivity in the 200-1100nm band and a function of temperature T: in, Through formula (7), it can be obtained that the pulverized coal particles corresponding to different burnout degrees B _m =[B ₁ B ₂ B ₃ ... B _m ] and combustion temperatures T _m [=T ₁ T ₂ T ₃ ... T _m ] are in the range of 200~ Average surface emissivity in the 1100nm band The undetermined coefficient matrix A can be obtained through binary nonlinear regression. When detecting the burnout degree of boiler pulverized coal, the pulverized coal flame combustion temperature measured through equations (6) and (7) and the average value in the 200-1100nm band By bringing the surface emissivity into equation (9), the burnout degree of the pulverized coal flame in the furnace can be obtained. 2. A method for measuring the burnout degree of a pulverized coal boiler using a device for online measuring the burnout degree of a pulverized coal boiler based on spectral analysis as claimed in claim 1, characterized in that a quartz lens is installed at the opening. 3. A method for measuring the burnout degree of a pulverized coal boiler based on a device for online measuring the burnout degree of a pulverized coal boiler based on spectral analysis as claimed in claim 1, characterized in that the armored optical fiber is fixed in the front cavity through a support frame, The cavity shells of the front cavity and the rear cavity are made of 304 stainless steel; there is a handle at the lower end of the rear cavity and a carrying handle at the upper end.