A sintering machine large flue air leakage rate online detection method based on laser oxygen measurement

Abstract

This invention discloses an online detection method for air leakage rate in the main flue of a sintering machine based on laser oxygen measurement. The method involves arranging multiple laser detection modules along the main flue to form an in-situ detection optical path. Combined with dynamic temperature and pressure compensation, the method calculates the in-situ oxygen content of the flue gas in real time. It then acquires sintering process parameters to construct a theoretical oxygen balance model for the sintering process, deducts the inherent oxygen loss from the sintering reaction, and calculates a theoretical baseline value for the oxygen content under leak-free conditions. The measured oxygen content and the baseline value are substituted into the oxygen mass balance formula to calculate the current real-time air leakage rate of the main flue. Furthermore, the method extracts the leakage increment gradient based on the difference in leakage rates between adjacent measuring points, achieving precise location of local leakage areas. This invention achieves high-precision continuous online measurement and anomaly warning of air leakage rate under harsh operating conditions, solving the problems of traditional detection lag and difficulty in tracing the source of leakage points.

Description

Technical Field

[0001] This invention relates to the field of flue gas detection technology for sintering equipment, specifically to an online detection method for the air leakage rate of the main flue of a sintering machine based on laser oxygen measurement. Background Technology

[0002] The sintering machine's main flue operates under high temperature, negative pressure, and high dust conditions for extended periods. Due to thermal stress and equipment wear, the flue walls and joints are prone to sealing failures and air leaks. Air leaks increase the power consumption of the main exhaust fan and disrupt the oxygen balance during sintering, ultimately affecting the quality of the sintered ore. Obtaining accurate air leakage rate data and pinpointing the location of leaks is fundamental for sintering production control and equipment maintenance.

[0003] The industry commonly uses zirconia oxygen analyzers to detect the oxygen content in flue gas to estimate air leakage rates. This detection method requires flue gas extraction and pretreatment. The probe is exposed to high-temperature, high-dust gases for extended periods, making it highly susceptible to mechanical wear and dust blockage, resulting in high equipment failure rates and short service life. Furthermore, the flue gas extraction process causes significant data response lag, making real-time, high-precision oxygen content measurement impossible.

[0004] In terms of specific calculation of air leakage rate, existing technologies mostly rely on manual periodic measurement of pressure difference and substitution into fixed empirical formulas for estimation. This static calculation method is detached from the actual physical process of sintering machine operation, and cannot synchronously respond to changes in dynamic process parameters such as sintering machine speed, solid fuel ratio, and total air volume. It also fails to deduct the inherent oxygen loss in the sintering chemical reaction, resulting in large errors in the calculated air leakage rate data, which cannot meet the detection requirements under varying operating conditions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an online detection method for the air leakage rate of a sintering machine's large flue based on laser oxygen measurement. This method solves the problem that the probe is easily subjected to mechanical wear and dust blockage due to long-term exposure to high-temperature and high-dust gases.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an online detection method for air leakage rate of a sintering machine flue based on laser oxygen measurement, comprising the following steps: Step 1: Install laser emitting units and laser receiving units at the preset detection points in the main flue of the sintering machine to form a detection optical path that runs through the flue gas flow channel inside the main flue, receive the real-time temperature and pressure parameters inside the main flue, and perform dynamic temperature and pressure compensation calibration. Step 2: Control the laser emitting unit to emit a laser beam of a specific wavelength to penetrate the high-temperature dusty flue gas inside the large flue. Collect the original absorption spectrum signal of the transmitted laser through the laser receiving unit. After signal processing and combined with the temperature and pressure dynamic compensation calibration results, calculate the real-time oxygen content of the flue gas in situ in the large flue. Step 3: Obtain the standard sintering process parameters of the sintering machine, substitute the standard sintering process parameters into the oxygen balance theoretical model of the sintering process, deduct the inherent oxygen loss of the sintering reaction, and calculate the theoretical oxygen content benchmark value of the flue gas in the large flue under the standard working condition without air leakage, hereinafter referred to as the theoretical oxygen content benchmark value. Step 4: Record the real-time oxygen content of the flue gas in the main flue as the measured oxygen content of the flue gas. Combine the theoretical oxygen content benchmark value and the ambient air standard oxygen content, substitute them into the real-time air leakage rate calculation formula of the main flue, and calculate the current real-time air leakage rate of the main flue. Step 5: Arrange multiple sets of laser detection modules evenly along the flue gas flow direction inside the main flue wall. Based on the real-time air leakage rate difference between adjacent measuring point sections, locate the local air leakage area of ​​the main flue. Based on historical detection data and standard sintering process parameters under current operating conditions, perform early warning and dynamic model correction of the air leakage status of the main flue.

[0007] Preferably, the installation of laser emitting units and laser receiving units at preset detection points in the sintering machine's main flue, forming a detection optical path that traverses the flue gas flow channel inside the main flue, receives real-time temperature and pressure parameters inside the main flue, and performs dynamic temperature and pressure compensation calibration, includes: A tunable diode laser with a center wavelength of 760nm is installed inside the laser emitting unit; Quartz protective lenses are provided at the front end of both the laser emitting unit and the laser receiving unit, and both are connected to a nitrogen purging protection device that introduces nitrogen into the detection optical path, forming a positive pressure protective gas curtain on the outside of the quartz protective lenses; Before performing dynamic temperature and pressure compensation calibration, standard zero-oxygen gas is introduced into the detection optical path to complete zero-point calibration, and standard oxygen gas with 10% VOL and 20% VOL is introduced to complete multi-point range calibration.

[0008] Preferably, the calculation of the real-time in-situ flue gas oxygen content in the main flue gas duct, after signal processing and combining the results of dynamic temperature and pressure compensation calibration, includes: The original absorption spectrum signal is processed using a lock-in amplification algorithm and a digital filtering algorithm to remove background noise signals generated by dust scattering, equipment mechanical vibration, and electromagnetic interference. Based on the initial emitted light intensity of the laser beam of the specific wavelength, the received light intensity of the transmitted laser, and the effective optical path of the detection optical path, the gas concentration under standard conditions is calculated by fitting according to the Lambert-Beer law. The real-time temperature and pressure parameters are incorporated into the fitting relationship to perform dynamic compensation calculation, eliminating the absorption line attenuation caused by temperature changes and the deviation in gas molecule number density caused by pressure fluctuations, and outputting the real-time oxygen content of the flue gas in situ in the large flue.

[0009] Preferably, the step of obtaining the standard sintering process parameters of the sintering machine, substituting the standard sintering process parameters into the oxygen balance theoretical model of the sintering process, subtracting the inherent oxygen loss of the sintering reaction, and calculating the theoretical oxygen content benchmark value of the flue gas in the large flue under the standard operating condition without air leakage includes: Obtain the standard sintering process parameters, including the sintering mix ratio, sintering machine speed, ignition temperature, main exhaust fan air volume, sintering negative pressure, and the moisture content of the mix. Extract the air volume parameters of the main exhaust fan, and combine them with the standard oxygen content of ambient air to calculate the initial oxygen supply and initial total air distribution volume of the sintering system. Extract the solid fuel ratio data from the sintering mixture ratio parameters, determine the total amount of oxygen required for the complete reaction of the sintering material according to the fuel combustion chemical reaction equation, and subtract the total amount of oxygen consumed from the initial oxygen supply to obtain the theoretical remaining oxygen amount. The incremental volume of carbon dioxide and sulfur dioxide produced by the reaction is calculated based on the chemical reaction equation of the fuel combustion, and the incremental volume of water vapor produced by water evaporation is calculated based on the moisture content of the mixture. The theoretical total flue gas volume is calculated by subtracting the total oxygen consumption from the initial total air distribution volume and adding the above-mentioned flue gas increment volume and the above-mentioned water vapor increment volume. The theoretical remaining oxygen content is divided by the theoretical total volume of flue gas to calculate the theoretical oxygen content baseline value.

[0010] Preferably, the step of substituting the real-time air leakage rate into the formula for calculating the current real-time air leakage rate of the main flue includes: An oxygen mass balance calculation formula is established to calculate the real-time air leakage rate of the large flue, and the oxygen mass balance calculation formula is called to perform numerical calculations. The oxygen mass balance calculation formula uses the difference between the measured oxygen content of flue gas and the theoretical oxygen content benchmark value as the numerator, and the difference between the ambient air standard oxygen content and the theoretical oxygen content benchmark value as the denominator. The real-time air leakage rate of the main flue is calculated by obtaining the percentage ratio of the numerator to the denominator, wherein the standard oxygen content of the ambient air is fixed at 21% VOL.

[0011] Preferably, the step of locating the location of local air leakage areas in the main flue based on the real-time air leakage rate difference between adjacent measuring point sections includes: Obtain the coordinates of the measuring points corresponding to each group of laser detection modules, and calculate the real-time air leakage rate difference of the large flue between the cross sections of two adjacent groups of measuring points in sequence. The physical distance between two adjacent sets of measuring point sections is extracted by combining the coordinates of the above measuring points. The leakage increment gradient is calculated by dividing the real-time leakage rate difference of the large flue by the above physical distance. The incremental gradient of air leakage between adjacent measuring points is compared with the preset air leakage gradient threshold. When it is determined that the incremental gradient of air leakage in a certain adjacent measuring point interval exceeds the preset air leakage gradient threshold, the adjacent measuring point interval is locked as an abnormal air leakage area, and the location data of the local air leakage area of ​​the main flue is output.

[0012] Preferably, the early warning system for the air leakage status of the main flue includes: The current real-time air leakage rate data of the large flue is compared with the multi-level air leakage rate safety threshold. When the real-time air leakage rate data of the current large flue exceeds any of the above-mentioned multi-level air leakage rate safety thresholds, an audible and visual alarm mechanism is triggered. Simultaneously record the time of the anomaly and the location data of the corresponding local air leakage area in the main flue; Extract historical real-time air leakage rate data of the main flue to construct an air leakage trend model, and combine the air leakage trend model to calculate the slope of the real-time air leakage rate of the main flue over time. The rate of seal decay of the main flue is evaluated by the slope of change. When the slope of change is greater than the preset decay rate threshold, an early warning signal for air leakage fault of the main flue is generated and sent to the industrial control terminal for display and early warning.

[0013] Preferably, the dynamic correction of the execution model includes: The standard sintering process parameters under the current operating conditions are periodically acquired; The corresponding input variables in the oxygen balance theoretical model of the sintering process are updated using the updated standard sintering process parameters. The theoretical oxygen content baseline value was recalculated based on the updated oxygen balance theoretical model of the sintering process, and the recalculated theoretical oxygen content baseline value replaced the original baseline value in the online calculation of the real-time air leakage rate of the large flue.

[0014] Preferably, the number of the multiple sets of laser detection modules is set to 10 sets, and the multiple sets of laser detection modules respectively cover the inlet section, front section, middle section, rear section and outlet section of the large flue.

[0015] An online detection system for air leakage rate in the main flue of a sintering machine based on laser oxygen measurement includes: The laser detection module includes a laser emitting unit and a laser receiving unit installed at preset detection points in the main flue of the sintering machine, which are used to form a detection optical path that crosses the flue gas flow channel inside the main flue; the laser emitting unit is controlled to emit a laser beam of a specific wavelength to penetrate the high-temperature dust-laden flue gas inside the main flue, and the original absorption spectrum signal of the transmitted laser is collected by the laser receiving unit. The operating condition compensation module is used to receive real-time temperature and pressure parameters inside the large flue and perform dynamic temperature and pressure compensation calibration. The signal processing module is used to receive the original absorption spectrum signal, process the signal, and combine it with the temperature and pressure dynamic compensation calibration results to calculate the real-time oxygen content of the flue gas in situ in the main flue. The data calculation module is used to acquire the standard sintering process parameters of the sintering machine, substitute these parameters into the oxygen balance theoretical model of the sintering process, deduct the inherent oxygen loss of the sintering reaction, and calculate the theoretical oxygen content benchmark value. The in-situ real-time flue gas oxygen content of the main flue is recorded as the measured flue gas oxygen content. Combined with the theoretical oxygen content benchmark value and the standard oxygen content of ambient air, it is substituted into the real-time air leakage rate calculation formula of the main flue to calculate the current real-time air leakage rate of the main flue. The module also performs dynamic model correction based on the standard sintering process parameters under the current operating conditions. The point positioning module is used to locate the location of a local air leakage area in the main flue based on the real-time air leakage rate difference between each adjacent measuring point section obtained by multiple sets of laser detection modules evenly arranged along the wall of the main flue. The data display and early warning module is used to issue early warnings for the air leakage status of the main flue based on historical detection data.

[0016] This invention provides an online detection method for the air leakage rate of a sintering machine's main flue based on laser oxygen measurement. It has the following beneficial effects: 1. This invention employs tunable diode laser absorption spectroscopy technology for in-situ penetration detection of flue gas inside large flues, combined with a nitrogen purging protection device and dynamic temperature and pressure compensation calibration. This non-contact optical path measurement method eliminates the flue gas extraction and pretreatment steps required for traditional zirconia detection, avoids direct wear and blockage of the detection probe under high temperature and high dust conditions, shortens data response time, and effectively improves the online measurement accuracy of flue gas oxygen content and the service life of equipment in harsh environments.

[0017] 2. This invention constructs a theoretical model of oxygen balance in the sintering process by acquiring process parameters such as real-time sintering machine speed, main exhaust fan air volume, and solid fuel ratio. It calculates the theoretical oxygen content benchmark value under standard operating conditions without air leakage and calculates the air leakage rate based on the oxygen mass balance formula. This calculation mechanism uses the oxygen consumption and air volume balance of the actual sintering chemical reaction as a benchmark for dynamic parameter calculation, replacing the traditional manual pressure difference estimation method, eliminating the calculation error caused by empirical formulas, and ensuring the accuracy of the real-time air leakage rate result of the large flue under variable operating conditions.

[0018] 3. This invention arranges multiple sets of laser detection modules evenly along the flue gas flow direction of the main flue. By calculating the difference in real-time air leakage rate and physical distance between adjacent measuring point sections of the main flue, the leakage increment gradient is extracted for anomaly threshold comparison. This multi-point array spatial comparison mechanism solves the technical defect that traditional single-point detection cannot trace the source of air leakage. It can accurately locate the specific area of ​​local air leakage in the main flue and output fault prediction signals in advance in combination with the air leakage change trend model, providing a direct basis for targeted maintenance and energy efficiency control of sintering equipment. Attached Figure Description

[0019] Figure 1 This is a system structure diagram of the present invention; Figure 2 This is a flowchart of the method for detecting the air leakage rate of the sintering machine flue of the present invention; Figure 3 This is a schematic diagram of the multi-measuring point arrangement and air leakage location of the sintering machine flue of the present invention.

[0020] The components include: 1. Laser emitting unit; 2. Laser receiving unit; 3. Nitrogen purging protection device; 4. Main flue wall; 5. Flue gas circulation channel; 6. Signal cable; 7. Industrial control terminal; 100. Laser detection module; 200. Signal processing module; 300. Data calculation module; 400. Operating condition compensation module; 500. Data display and early warning module; 600. Point positioning module. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0022] See attached document Figure 1This invention provides an online detection system for the air leakage rate of a sintering machine flue based on laser oxygen measurement. The system includes: a laser detection module 100, a signal processing module 200, a data calculation module 300, a working condition compensation module 400, a data display and early warning module 500, and a point positioning module 600.

[0023] The laser detection module 100 includes a symmetrically arranged laser emitting unit 1 and a laser receiving unit 2. The laser emitting unit 1 and the laser receiving unit 2 are installed on both sides of the wall of the large flue duct 4 through flanges. The laser emitting unit 1 and the laser receiving unit 2 are arranged coaxially to form a detection optical path that crosses the flue gas flow channel 5 inside the large flue.

[0024] Both the laser emitting unit 1 and the laser receiving unit 2 are equipped with protective lenses at their front ends, and both are connected to a nitrogen purging protection device 3. The nitrogen purging protection device 3 introduces nitrogen into the detection optical path channel to prevent smoke and dust from adhering to the protective lenses.

[0025] The laser detection module 100 is connected to the industrial control terminal 7 via the signal cable 6. The aforementioned signal processing module 200, data calculation module 300, working condition compensation module 400, data display and early warning module 500, and point positioning module 600 are all integrated into the industrial control terminal 7.

[0026] See attached document Figure 2 This invention provides an online detection method for the air leakage rate of a sintering machine's main flue based on laser oxygen measurement. The method, based on the aforementioned system, includes the following steps: Step S1: Install and fix the equipment. Install the laser emitting unit 1 and the laser receiving unit 2 at the preset detection points in the sintering machine's main flue, and turn on the nitrogen purging protection device 3.

[0027] Step S2: Perform parameter calibration and zero-point calibration. Introduce standard zero oxygen gas into the laser detection module 100 for zero-point calibration, and introduce standard oxygen gas of known concentration for range calibration. The operating condition compensation module 400 receives real-time temperature and pressure parameters collected by the temperature and pressure sensors inside the large flue and performs dynamic temperature and pressure compensation calibration.

[0028] Step S3: Perform in-situ laser spectrum acquisition. Laser emitting unit 1 emits a laser beam of a specific wavelength to penetrate the flue gas in the flue gas flow channel 5, and laser receiving unit 2 collects the transmitted laser signal after absorption by the flue gas.

[0029] Step S4: Filtering and noise reduction and calculation of flue gas oxygen content are performed. The signal processing module 200 receives the transmitted laser signal, removes noise signals through lock-in amplification algorithm and digital filtering algorithm, and calculates the in-situ real-time flue gas oxygen content of the main flue according to Lambert-Beer law.

[0030] Step S5: Process parameters are collected and oxygen balance benchmark is calculated. The data calculation module 300 obtains the standard sintering process parameters of the sintering machine, including the sintering mixture ratio, sintering machine speed, main exhaust fan air volume, and sintering negative pressure. The data calculation module 300 substitutes the standard sintering process parameters into the oxygen balance theoretical model of the sintering process, deducts the inherent oxygen loss of the sintering reaction, and calculates the theoretical oxygen content benchmark value of the flue gas under the standard operating condition without air leakage (hereinafter referred to as the theoretical oxygen content benchmark value of the flue gas).

[0031] Step S6: Perform the air leakage rate formula calculation. The data calculation module 300 combines the measured oxygen content of flue gas, the theoretical oxygen content benchmark value of flue gas in the main flue, and the standard oxygen content of ambient air to calculate the current real-time air leakage rate of the main flue through the oxygen mass balance calculation formula.

[0032] Step S7: Perform multi-point data comparison and air leakage location. Multiple sets of laser detection modules 100 are evenly arranged along the flue gas flow direction of the main flue. The point location module 600 compares the oxygen content difference and air leakage rate difference between each measuring point. Combined with the measuring point location information, the location of the air leakage area is determined and output.

[0033] Step S8 involves data storage, real-time display, and tiered alarm. The data display and early warning module 500 stores real-time air leakage rate data and flue gas oxygen content data, and displays them on the industrial control terminal 7. When the real-time air leakage rate of the main flue exceeds the preset real-time air leakage rate safety threshold, an audible and visual alarm is triggered.

[0034] Step S9 involves predicting air leakage trends and dynamically correcting the model. Based on historical detection data, an air leakage trend model is constructed to predict the air leakage status of the main flue. The oxygen balance theoretical model is adjusted according to the sintering process parameters to correct the theoretical oxygen content benchmark value of the flue gas in the main flue.

[0035] See attached document Figure 1 This invention provides an in-situ detection optical path construction and adaptive design scheme for a real-time online detection system for the leakage rate of a sintering machine's large flue based on laser oxygen measurement, including: Laser emitting unit 1 and laser receiving unit 2 are installed at the preset detection points in the main flue of the sintering machine. Laser emitting unit 1 and laser receiving unit 2 are symmetrically fixed on both sides of the main flue wall 4 by means of flange through the wall. Laser emitting unit 1 and laser receiving unit 2 are arranged coaxially to form a detection optical path that crosses the flue gas flow channel 5 inside the main flue.

[0036] The laser emitting unit 1 is equipped with a tunable diode laser with a center wavelength of 760nm. This wavelength matches the characteristic absorption spectrum of oxygen and avoids the spectral interference of flue gas dust, sulfides and nitrogen oxides inside the flue gas flow channel 5.

[0037] Both the laser emitting unit 1 and the laser receiving unit 2 are equipped with quartz protective lenses at their front ends. The quartz protective lenses physically isolate the optical components of the laser equipment from the high-temperature and dusty environment inside the flue gas circulation channel 5.

[0038] Both the front end of the laser emitting unit 1 and the laser receiving unit 2 are connected to the nitrogen purging protection device 3. The nitrogen purging protection device 3 continuously introduces nitrogen into the detection optical path channel. The introduced nitrogen forms a positive pressure protective air curtain on the outside of the quartz protective lens. The positive pressure protective air curtain prevents dust and oil fumes in the flue gas flow channel 5 from adhering to the quartz protective lens, keeping the detection optical path unobstructed.

[0039] After the above physical structure is built, the system performs parameter calibration and zero-point calibration. Standard zero-oxygen gas is introduced into the detection optical path to complete the zero-point calibration, and standard oxygen gas of 10%VOL and 20%VOL is introduced to complete the multi-point range calibration.

[0040] The operating condition compensation module 400 receives real-time temperature and pressure parameters from the temperature sensor installed inside the flue, as well as real-time temperature and pressure parameters from the pressure sensor. Based on the above real-time temperature and pressure parameters, the operating condition compensation module 400 performs dynamic temperature and pressure compensation calibration to eliminate the interference of the high temperature and negative pressure environment inside the flue gas flow channel 5 on the spectral acquisition accuracy.

[0041] See attached document Figure 2 This invention provides a high-precision spectral acquisition and dynamic temperature and pressure compensation solution scheme for an online detection method of air leakage rate in the large flue of a sintering machine based on laser oxygen measurement, including the following contents.

[0042] Laser emitting unit 1 emits a specific laser beam with a center wavelength of 760nm. The specific laser beam directly penetrates the high-temperature dust-laden flue gas inside the flue gas flow channel 5 of the large flue pipe wall 4. After being absorbed by the high-temperature dust-laden flue gas, the specific laser beam forms a transmitted laser. Laser receiving unit 2 collects the original absorption spectrum signal of the transmitted laser.

[0043] The laser receiving unit 2 transmits the original absorption spectrum signal to the signal processing module 200. The signal processing module 200 uses the built-in lock-in amplification algorithm and digital filtering algorithm to process the original absorption spectrum signal and remove the background noise signal generated by dust scattering, equipment mechanical vibration and electromagnetic interference.

[0044] The operating condition compensation module 400 synchronously transmits the real-time temperature and pressure parameters inside the large flue to the signal processing module 200.

[0045] The signal processing module 200 receives the denoised spectral signal and establishes a spectral absorption fitting relationship according to the Lambert-Beer law. Specifically, the signal processing module 200 calculates the gas concentration under standard conditions based on the initial emitted light intensity of a specific laser beam, the received light intensity of the transmitted laser, and the effective optical path of the detection optical path.

[0046] The signal processing module 200 incorporates the aforementioned real-time temperature and pressure parameters into the spectral absorption fitting relationship to perform dynamic compensation calculations, thereby eliminating the attenuation of the absorption line strength caused by temperature changes and the deviation in gas molecule number density caused by pressure fluctuations.

[0047] The signal processing module 200 outputs the real-time measured value of oxygen content in the flue gas in situ, and the data response time of the final measured oxygen content is controlled within 1 second, with a measurement accuracy error not exceeding ±0.2%VOL.

[0048] See attached document Figure 2 This invention provides a theoretical model construction and dynamic benchmark solution scheme for sintering oxygen balance based on laser oxygen measurement for online detection of air leakage rate in the large flue of a sintering machine. The scheme includes the following: The data calculation module 300 obtains the standard sintering process parameters of the sintering machine in real time through the industrial control terminal 7. The standard sintering process parameters include the sintering mixture ratio, sintering machine speed, ignition temperature, main exhaust fan air volume, sintering negative pressure, and mixture moisture content.

[0049] The data calculation module 300 constructs a theoretical model of oxygen balance in the sintering process based on the above-mentioned standard sintering process parameters. The data calculation module 300 extracts the air volume parameters of the main exhaust fan and, combined with the standard oxygen content of the ambient air, calculates the initial oxygen supply and the initial total air distribution volume input to the sintering system.

[0050] The data calculation module 300 combines the sintering mixture ratio parameters, extracts the solid fuel ratio data within the sintering mixture ratio parameters, and determines the total amount of oxygen required for the complete reaction of the sintering materials according to the fuel combustion chemical reaction equation. The total amount of oxygen consumed includes the inherent oxygen loss of the oxidation reaction and the inherent oxygen loss of the reduction reaction during the sintering production process.

[0051] The data calculation module 300 calculates the incremental volume of carbon dioxide and sulfur dioxide generated by the reaction based on the chemical reaction equation of fuel combustion, and calculates the incremental volume of water vapor generated by water evaporation in combination with the moisture content of the above-mentioned mixture. The data calculation module 300 deducts the total amount of oxygen consumed above from the initial oxygen supply to obtain the theoretical amount of remaining oxygen after the sintering reaction.

[0052] The data calculation module 300, in conjunction with the flue gas volume balance relationship, subtracts the total oxygen consumption from the total initial air distribution volume and adds the flue gas increment volume and the water vapor increment volume to calculate the theoretical oxygen content benchmark value of the flue gas in the main flue. The data calculation module 300 then divides the theoretical remaining oxygen by the theoretical total flue gas volume to calculate the theoretical oxygen content benchmark value of the flue gas in the main flue.

[0053] During the continuous operation of the sintering machine, the data calculation module 300 periodically reads the updated standard sintering process parameters. Based on the updated standard sintering process parameters, the data calculation module 300 adjusts the oxygen balance theoretical model of the sintering process and dynamically iterates to calculate the theoretical oxygen content benchmark value of the flue gas in the main flue, ensuring the detection accuracy under all working conditions.

[0054] See attached document Figure 3 This invention provides an online leakage rate calculation and multi-point array tracing and positioning scheme for an online detection method of leakage rate in the large flue of a sintering machine based on laser oxygen measurement, including the following:

[0055] The data calculation module 300 receives the real-time oxygen content of the flue gas in situ from the signal processing module 200 and records the real-time oxygen content of the flue gas in situ as the measured oxygen content of the flue gas. At the same time, the data calculation module 300 extracts the theoretical oxygen content benchmark value of the flue gas in sintering under the standard working condition of no air leakage, output by the oxygen balance theoretical model of the sintering process.

[0056] The data calculation module 300 retrieves the ambient air standard oxygen content and substitutes the measured flue gas oxygen content, the theoretical oxygen content benchmark value of the flue gas in the main flue, and the ambient air standard oxygen content into the real-time air leakage rate calculation formula for the main flue to calculate the current real-time air leakage rate of the main flue. The formula for calculating the real-time air leakage rate of the large flue built into the data calculation module 300 mentioned above is as follows: In the formula, η is the real-time air leakage rate of the large flue, and C meas To measure the oxygen content in the flue gas, C theo C is the theoretical oxygen content benchmark value for flue gas from large flues. air The standard oxygen content in ambient air is fixed at 21% VOL.

[0057] Multiple sets of laser detection modules 100 are evenly arranged along the flue gas flow direction inside the wall of the main flue. The number of laser detection modules 100 is set to 3 to 8 sets, respectively covering the inlet section, front section, middle section, rear section and outlet section of the main flue.

[0058] The point positioning module 600 synchronously acquires the coordinates of the measuring points corresponding to each group of laser detection modules 100, and the real-time air leakage rate data of the large flue corresponding to the measuring point cross-section obtained by the data calculation module 300. The point positioning module 600 calculates the real-time air leakage rate difference of the large flue between two adjacent sets of measuring point sections according to the flue gas flow direction, and extracts the physical distance between two adjacent sets of measuring point sections in combination with the above measuring point position coordinates. Then, it calculates the air leakage increment gradient by dividing the above real-time air leakage rate difference of the large flue by the above physical distance.

[0059] The point location module 600 compares the leakage increment gradient between each adjacent measuring point section with the preset leakage gradient threshold. When it is determined that the leakage increment gradient of a certain adjacent measuring point interval exceeds the preset leakage gradient threshold, the point location module 600 locks the adjacent measuring point interval as an abnormal leakage area and outputs the location data of the local leakage area of ​​the large flue.

[0060] See attached document Figure 2 This invention provides a data early warning closed-loop and model adaptive iteration scheme for an online detection method of air leakage rate in the large flue of a sintering machine based on laser oxygen measurement, including the following:

[0061] The industrial control terminal 7 receives real-time air leakage rate data, flue gas oxygen content data, and local air leakage area location data of the main flue. The data display and early warning module 500 classifies and stores the above-mentioned real-time air leakage rate data, flue gas oxygen content data, and local air leakage area location data of the main flue, and displays them synchronously on the display interface of the industrial control terminal 7.

[0062] The data display and early warning module 500 has multiple preset safety thresholds for air leakage rate. It compares the real-time air leakage rate data of the main flue with the multiple safety thresholds. When the real-time air leakage rate data of the main flue exceeds any of the above-mentioned multiple safety thresholds, the data display and early warning module 500 triggers an audible and visual alarm mechanism and simultaneously records the time of the anomaly and the corresponding location data of the leakage area.

[0063] The data calculation module 300 extracts historically stored real-time air leakage rate data of the main flue, constructs an air leakage trend model, and calculates the slope of the real-time air leakage rate of the main flue over time based on the air leakage trend model. The data calculation module 300 evaluates the sealing degradation rate of the main flue based on the above-mentioned slope. The data calculation module 300 compares the above-mentioned slope with a preset degradation rate threshold. When the above-mentioned slope is greater than the above-mentioned preset degradation rate threshold, the data calculation module 300 generates an early warning signal for air leakage faults in the main flue and sends the above-mentioned early warning signal for air leakage faults in the main flue to the industrial control terminal 7 for display and early warning.

[0064] The data calculation module 300 periodically acquires the standard sintering process parameters under the current operating conditions and uses these standard sintering process parameters to update the corresponding input variables in the oxygen balance theoretical model of the sintering process.

[0065] The data calculation module 300 recalculates the theoretical oxygen content benchmark value of the flue gas in the main flue based on the updated oxygen balance theoretical model of the sintering process, and replaces the original benchmark value with the recalculated theoretical oxygen content benchmark value of the flue gas in the main flue to participate in the online measurement of the real-time air leakage rate of the main flue, thus completing the dynamic correction of the theoretical oxygen content benchmark value of the flue gas in the main flue.

[0066] See attached document Figure 1 This invention provides a typical industrial embodiment verification scheme for an online detection method of air leakage rate in the large flue of a sintering machine based on laser oxygen measurement, including the following contents.

[0067] In the first industrial embodiment, the above-mentioned online detection method is applied to the main flue of a 360-square-meter sintering machine. Along the flue gas flow direction inside the main flue pipe wall 4, three sets of laser detection modules 100 are arranged in the flue gas inlet section, middle section and outlet section respectively. Each set of laser detection modules 100 is equipped with a tunable diode laser with a center wavelength of 760nm and a matching nitrogen purging protection device 3.

[0068] After the system is powered on, zero-point calibration and range calibration are performed. The operating condition compensation module 400 collects real-time temperature parameters of 120 to 180 ℃ and real-time pressure parameters of -8000 to -12000 Pa inside the main flue through temperature and pressure sensors installed inside the main flue, and completes dynamic temperature and pressure compensation calibration based on the above real-time temperature and pressure parameters.

[0069] The data calculation module 300 retrieves the standard sintering process parameters of the current sintering machine through the industrial control terminal 7. The above standard sintering process parameters include a sintering machine speed of 1.8 meters per minute, a main exhaust fan air volume of 85,000 m³ / h, and a sintering negative pressure of 10,000 Pa. The data calculation module 300 substitutes the above standard sintering process parameters into the oxygen balance theoretical model of the sintering process and calculates that the theoretical oxygen content of the flue gas in the large flue under the standard operating condition of no air leakage is 4.2% VOL.

[0070] The signal processing module 200 calculates the measured oxygen content of the flue gas at the measuring point in the middle section of the main flue to be 6.8% VOL. The data calculation module 300 substitutes the measured oxygen content of the flue gas of 6.8% VOL, the theoretical oxygen content of the flue gas of 4.2% VOL, and the ambient air standard oxygen content of 21% VOL into the real-time air leakage rate calculation formula of the main flue, and calculates that the current real-time air leakage rate of the main flue in the middle section of the main flue is 15.48%.

[0071] The point positioning module 600 compares the data output by the three sets of laser detection modules 100, extracts the leakage increment gradient between adjacent measuring point sections, and determines that the leakage increment gradient between the outlet section and the middle section exceeds the preset leakage gradient threshold, thereby determining that there is an abnormal leakage area in the outlet section of the large flue.

[0072] The data display and early warning module 500 extracts the preset 12% air leakage rate safety threshold. Since the real-time air leakage rate of the main flue is 15.48%, which is greater than the above-mentioned 12% air leakage rate safety threshold, the data display and early warning module 500 triggers the audible and visual alarm mechanism and stores the detection data synchronously on the industrial control terminal 7. The data calculation module 300 updates the oxygen balance theoretical model of the sintering process in real time according to the changes in subsequent sintering process parameters and dynamically corrects the theoretical oxygen content benchmark value of the flue gas in the main flue.

[0073] In the second industrial embodiment, the above-mentioned online detection method is applied to the main flue of a 200-square-meter sintering machine. Five sets of laser detection modules 100 are evenly arranged along the flue gas flow direction of the main flue pipe wall 4. The theoretical oxygen content benchmark value of the flue gas under the standard working condition of no air leakage calculated by the data calculation module 300 is 3.8%VOL, and the measured oxygen content of the flue gas calculated by the signal processing module 200 is 5.5%VOL. The data calculation module 300 substitutes the above values ​​into the real-time air leakage rate calculation formula of the main flue and calculates that the current real-time air leakage rate of the main flue is 9.88%.

[0074] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for online detection of air leakage rate in the main flue of a sintering machine based on laser oxygen measurement, characterized in that, Includes the following steps: Step 1: Install laser emitting unit (1) and laser receiving unit (2) at the preset detection points in the sintering machine flue to form a detection optical path that crosses the flue gas flow channel (5) inside the flue, receive the real-time temperature parameters and real-time pressure parameters inside the flue, and perform dynamic temperature and pressure compensation calibration. Step 2: Control the laser emitting unit (1) to emit a laser beam of a specific wavelength to penetrate the high-temperature dusty flue gas inside the large flue. Collect the original absorption spectrum signal of the transmitted laser through the laser receiving unit (2). After signal processing and combined with the temperature and pressure dynamic compensation calibration results, calculate the real-time oxygen content of the flue gas in situ in the large flue. Step 3: Obtain the standard sintering process parameters of the sintering machine, substitute the standard sintering process parameters into the oxygen balance theoretical model of the sintering process, deduct the inherent oxygen loss of the sintering reaction, and calculate the theoretical oxygen content benchmark value of the flue gas in the large flue under the standard working condition without air leakage, hereinafter referred to as the theoretical oxygen content benchmark value. Step 4: Record the real-time oxygen content of the flue gas in the main flue as the measured oxygen content of the flue gas. Combine the theoretical oxygen content benchmark value and the ambient air standard oxygen content, substitute them into the real-time air leakage rate calculation formula of the main flue, and calculate the current real-time air leakage rate of the main flue. Step 5: Arrange multiple sets of laser detection modules (100) evenly along the flue gas flow direction inside the wall (4) of the main flue. Locate the location of the local air leakage area of ​​the main flue based on the real-time air leakage rate difference between adjacent measuring point sections. Based on historical detection data and standard sintering process parameters under current operating conditions, perform early warning and dynamic model correction of the air leakage status of the main flue.

2. The method for online detection of air leakage rate in the main flue of a sintering machine based on laser oxygen measurement according to claim 1, characterized in that, The laser emitting unit (1) and laser receiving unit (2) are installed at the preset detection points in the main flue of the sintering machine to form a detection optical path that crosses the flue gas flow channel (5) inside the main flue. This path receives real-time temperature and pressure parameters inside the main flue and performs dynamic temperature and pressure compensation calibration, including: A tunable diode laser with a center wavelength of 760nm is installed inside the laser emitting unit (1); Quartz protective lenses are provided at the front ends of both the laser emitting unit (1) and the laser receiving unit (2), and both are connected to a nitrogen purging protection device (3) that introduces nitrogen into the detection optical path, forming a positive pressure protective air curtain on the outside of the quartz protective lenses; Before performing dynamic temperature and pressure compensation calibration, standard zero-oxygen gas is introduced into the detection optical path to complete zero-point calibration, and standard oxygen gas with 10% VOL and 20% VOL is introduced to complete multi-point range calibration.

3. The method for online detection of air leakage rate in the main flue of a sintering machine based on laser oxygen measurement according to claim 1, characterized in that, The oxygen content of the in-situ flue gas in the main flue, calculated by signal processing and combining the results of dynamic temperature and pressure compensation calibration, includes: The original absorption spectrum signal is processed using a lock-in amplification algorithm and a digital filtering algorithm to remove background noise signals generated by dust scattering, equipment mechanical vibration, and electromagnetic interference. Based on the initial emitted light intensity of the laser beam of the specific wavelength, the received light intensity of the transmitted laser, and the effective optical path of the detection optical path, the gas concentration under standard conditions is calculated by fitting according to the Lambert-Beer law. The real-time temperature and pressure parameters are incorporated into the fitting relationship to perform dynamic compensation calculation, eliminating the absorption line attenuation caused by temperature changes and the deviation in gas molecule number density caused by pressure fluctuations, and outputting the real-time oxygen content of the flue gas in situ in the large flue.

4. The method for online detection of air leakage rate in the main flue of a sintering machine based on laser oxygen measurement according to claim 1, characterized in that, The process of obtaining standard sintering process parameters for the sintering machine, substituting these parameters into the oxygen balance theoretical model of the sintering process, subtracting the inherent oxygen loss from the sintering reaction, and calculating the theoretical oxygen content benchmark value of the flue gas in the large flue under standard operating conditions with no air leakage includes: Obtain the standard sintering process parameters, including the sintering mix ratio, sintering machine speed, ignition temperature, main exhaust fan air volume, sintering negative pressure, and the moisture content of the mix. Extract the air volume parameters of the main exhaust fan, and combine them with the standard oxygen content of ambient air to calculate the initial oxygen supply and initial total air distribution volume of the sintering system. Extract the solid fuel ratio data from the sintering mixture ratio parameters, determine the total amount of oxygen required for the complete reaction of the sintering material according to the fuel combustion chemical reaction equation, and subtract the total amount of oxygen consumed from the initial oxygen supply to obtain the theoretical remaining oxygen amount. The incremental volume of carbon dioxide and sulfur dioxide produced by the reaction is calculated based on the chemical reaction equation of the fuel combustion, and the incremental volume of water vapor produced by water evaporation is calculated based on the moisture content of the mixture. The theoretical total flue gas volume is calculated by subtracting the total oxygen consumption from the initial total air distribution volume and adding the above-mentioned flue gas increment volume and the above-mentioned water vapor increment volume. The theoretical remaining oxygen content is divided by the theoretical total volume of flue gas to calculate the theoretical oxygen content baseline value.

5. The method for online detection of air leakage rate in the main flue of a sintering machine based on laser oxygen measurement according to claim 1, characterized in that, The real-time air leakage rate of the main flue is calculated by substituting the values ​​into the formula for calculating the real-time air leakage rate of the main flue, including: An oxygen mass balance calculation formula is established to calculate the real-time air leakage rate of the large flue, and the oxygen mass balance calculation formula is called to perform numerical calculations. The oxygen mass balance calculation formula uses the difference between the measured oxygen content of flue gas and the theoretical oxygen content benchmark value as the numerator, and the difference between the ambient air standard oxygen content and the theoretical oxygen content benchmark value as the denominator. The real-time air leakage rate of the main flue is calculated by obtaining the percentage ratio of the numerator to the denominator, wherein the standard oxygen content of the ambient air is fixed at 21% VOL.

6. The method for online detection of air leakage rate in the main flue of a sintering machine based on laser oxygen measurement according to claim 1, characterized in that, The method of locating the location of local air leakage areas in the main flue based on the real-time air leakage rate difference between adjacent measuring point sections includes: Obtain the coordinates of the measuring points corresponding to each group of laser detection modules (100), and calculate the real-time air leakage rate difference of the large flue between the cross sections of two adjacent groups of measuring points in turn; The physical distance between two adjacent sets of measuring point sections is extracted by combining the coordinates of the above measuring points. The leakage increment gradient is calculated by dividing the real-time leakage rate difference of the large flue by the above physical distance. The incremental gradient of air leakage between adjacent measuring points is compared with the preset air leakage gradient threshold. When it is determined that the incremental gradient of air leakage in a certain adjacent measuring point interval exceeds the preset air leakage gradient threshold, the adjacent measuring point interval is locked as an abnormal air leakage area, and the location data of the local air leakage area of ​​the main flue is output.

7. The method for online detection of air leakage rate in the main flue of a sintering machine based on laser oxygen measurement according to claim 1, characterized in that, The warning for the air leakage status of the main flue includes: The current real-time air leakage rate data of the large flue is compared with the multi-level air leakage rate safety threshold. When the real-time air leakage rate data of the current large flue exceeds any of the above-mentioned multi-level air leakage rate safety thresholds, an audible and visual alarm mechanism is triggered. Simultaneously record the time of the anomaly and the location data of the corresponding local air leakage area in the main flue; Extract historical real-time air leakage rate data of the main flue to construct an air leakage trend model, and combine the air leakage trend model to calculate the slope of the real-time air leakage rate of the main flue over time. The rate of seal decay of the large flue is evaluated by the slope of change. When the slope of change is greater than the preset decay rate threshold, an early warning signal for air leakage fault of the large flue is generated and the above-mentioned early warning signal for air leakage fault of the large flue is sent to the industrial control terminal (7) for display and warning.

8. The method for online detection of air leakage rate in the main flue of a sintering machine based on laser oxygen measurement according to claim 1, characterized in that, The dynamic correction of the execution model includes: The standard sintering process parameters under the current operating conditions are periodically acquired; The corresponding input variables in the oxygen balance theoretical model of the sintering process are updated using the updated standard sintering process parameters. The theoretical oxygen content baseline value was recalculated based on the updated oxygen balance theoretical model of the sintering process, and the recalculated theoretical oxygen content baseline value replaced the original baseline value in the online calculation of the real-time air leakage rate of the large flue.

9. The method for online detection of air leakage rate in the main flue of a sintering machine based on laser oxygen measurement according to claim 1, characterized in that, The number of the multiple laser detection modules (100) is set to 3 to 8, and the multiple laser detection modules (100) respectively cover the inlet section, front section, middle section, rear section and outlet section of the large flue.

10. An online detection system for the air leakage rate of a sintering machine's main flue based on laser oxygen measurement, used to implement the online detection method for the air leakage rate of a sintering machine's main flue based on laser oxygen measurement as described in any one of claims 1 to 9, characterized in that, include: The laser detection module (100) includes a laser emitting unit (1) and a laser receiving unit (2) installed at preset detection points in the main flue of the sintering machine, which are used to form a detection optical path that crosses the flue gas flow channel (5) inside the main flue; the laser emitting unit (1) is controlled to emit a laser beam of a specific wavelength to penetrate the high temperature dust-laden flue gas inside the main flue, and the original absorption spectrum signal of the transmitted laser is collected by the laser receiving unit (2). The operating condition compensation module (400) is used to receive real-time temperature and pressure parameters inside the large flue and perform dynamic temperature and pressure compensation calibration. The signal processing module (200) is used to receive the original absorption spectrum signal, process the signal and combine it with the temperature and pressure dynamic compensation calibration results to calculate the real-time oxygen content of the flue gas in the main flue. The data calculation module (300) is used to obtain the standard sintering process parameters of the sintering machine, substitute the standard sintering process parameters into the oxygen balance theoretical model of the sintering process, deduct the inherent oxygen loss of the sintering reaction, and calculate the theoretical oxygen content benchmark value; record the in-situ real-time flue gas oxygen content of the main flue as the measured flue gas oxygen content, combine the theoretical oxygen content benchmark value and the standard oxygen content of the ambient air, substitute it into the real-time air leakage rate calculation formula of the main flue, and calculate the current real-time air leakage rate of the main flue; and perform dynamic model correction based on the standard sintering process parameters under the current operating conditions. The point positioning module (600) is used to locate the location of the local air leakage area of ​​the large flue based on the real-time air leakage rate difference between each adjacent measuring point section obtained by multiple sets of laser detection modules (100) evenly arranged along the wall of the large flue (4). The data display and early warning module (500) is used to perform early warning of the air leakage status of the large flue based on historical detection data.

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