A method and system for detecting oxygen content in a sintering machine large flue

Abstract

The application discloses a sintering machine large flue oxygen content detection method and system, and belongs to the technical field of sintering machine flue gas detection. The method comprises the following steps: determining the airflow stability of the detection area of the sintering machine large flue; in the detection area of the sintering machine large flue, the oxygen content is detected by using a horizontal river gas detection device to obtain initial oxygen content detection data; the initial oxygen content detection data is subjected to outlier rejection and data calibration to obtain accurate oxygen content data, if the accurate oxygen content data exceeds the preset normal oxygen content range, a warning mechanism is triggered and the next step is executed; the sampling position and detection parameters of the horizontal river gas detection device are adjusted and the oxygen content detection is re-executed until the accurate oxygen content data is stably fed back or the abnormal reason is confirmed and the detection is actively stopped. The performance advantage of the horizontal river gas detection device is fully exerted, accurate and real-time detection of the flue oxygen content is realized, and stable and efficient operation of the sintering production is ensured.

Description

Technical Field

[0001] This invention belongs to the field of sintering machine flue gas detection technology. Specifically, this invention relates to a method and system for detecting oxygen content in the main flue gas duct of a sintering machine. Background Technology

[0002] The sintering machine is a key piece of equipment in steel production. It produces sintered ore that meets the requirements of blast furnace smelting by mixing and sintering iron ore powder, fuel, and flux. During the sintering process, the sintering machine's main flue serves as the core channel for flue gas collection and emission. The oxygen content inside the flue directly affects the energy consumption, sinter quality, and environmental emission indicators of the sintering process. If the oxygen content is too high, it will lead to excessive airflow in the flue, increasing the energy consumption of the blower and potentially exacerbating the generation of harmful gases in the flue gas. If the oxygen content is too low, it will cause incomplete combustion of fuel, lower the sintering temperature, affect the strength of the sinter, and may even cause the sintering process to be interrupted.

[0003] Currently, oxygen content detection in the main flue gas duct of sintering machines mostly uses ordinary gas detection devices, which have the following problems: 1. Low detection accuracy: Ordinary detection devices do not take into account the influence of unstable airflow in the flue. During sampling, airflow fluctuations can easily lead to insufficient sample representativeness. In addition, no temperature and pressure compensation is performed, resulting in large deviations in the detection data. 2. Lack of dynamic adjustment mechanism: The detection location and parameters are fixed and cannot be adjusted according to the actual working conditions in the flue (such as airflow changes and temperature fluctuations), resulting in the detection data failing to reflect the true oxygen content in the flue in real time; 3. Insufficient early warning and linkage: When abnormal oxygen content is detected, it can only issue a simple alarm and cannot be linked with the sintering machine's air volume control, gas ratio and other systems, making it difficult to quickly resolve the abnormal oxygen content problem and easily causing production losses; 4. Non-standard calibration cycle: The lack of a regular and standardized calibration process leads to a decrease in sensor sensitivity after long-term use of the detection device, further reducing detection accuracy.

[0004] Yokogawa gas detection devices, as high-precision gas detection equipment, have high sensitivity, wide detection range and stable data processing capabilities. However, there is currently no specific application plan for detecting oxygen content in the main flue of sintering machines, which makes it impossible to fully utilize its performance advantages and meet the demand for accurate detection of oxygen content in flue gas during sintering production. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing technologies and proposes a method and system for detecting oxygen content in the main flue of a sintering machine. The purpose is to solve the problems of low detection accuracy, lack of dynamic adjustment and linkage early warning, and non-standard calibration of oxygen content in the main flue of existing sintering machines, and to give full play to the performance advantages of Yokogawa gas detection devices to achieve accurate and real-time detection of oxygen content in the flue, thereby ensuring stable and efficient operation of sintering production.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for detecting oxygen content in the main flue gas duct of a sintering machine, the method comprising the following steps: Step S1: Determine the airflow stability in the detection area of ​​the sintering machine's main flue. If the determination result is that the airflow is in a stable state, proceed to the next step. Step S2: In the detection area of ​​the sintering machine's main flue, an oxygen content detection device is used to detect the oxygen content and obtain initial oxygen content detection data. Step S3: Remove outliers and calibrate the initial oxygen content detection data to obtain accurate oxygen content data. If the accurate oxygen content data is within the preset normal oxygen content range, the single detection is completed; if it exceeds the preset normal oxygen content range, the early warning mechanism is triggered and step S4 is executed. Step S4: Adjust the sampling position and detection parameters of the Yokogawa gas detection device, and repeat steps S2 and S3 until the accurate oxygen content data is within the preset normal oxygen content range or the abnormality is confirmed and then the process is stopped.

[0007] Preferably, the method for determining airflow stability in step S1 includes: Step S11: At least three airflow velocity sensors are deployed around the detection area of ​​the sintering machine's main flue to synchronously collect the real-time airflow velocity at the location of each sensor. Step S12: In the case of any two sensors combined, calculate the airflow velocity difference between all sensor combinations. If all differences are less than the set velocity difference threshold and the duration reaches the set stability determination time, the airflow is determined to be in a stable state; otherwise, the airflow is determined to be unstable, and step S11 is re-executed after a preset interval.

[0008] Preferably, the placement of the airflow velocity sensor satisfies the following conditions: the distance between the airflow velocity sensor and the inner wall of the sintering machine's main flue is not less than 1 / 10 of the flue diameter, and the central angles between two adjacent sensors are equal.

[0009] Preferably, in step S2, multiple target detection positions are set in the detection area of ​​the sintering machine flue. The sampling probe of the Yokogawa gas detection device collects gas from each target detection position in a preset order to perform oxygen content detection. The method for determining the target detection positions is as follows: based on the diameter of the sintering machine flue and the airflow direction in the flue, the cross-section of the flue is divided into a central area, a middle ring area, and an edge area. Multiple evenly distributed sampling points are selected in each area as target detection positions.

[0010] Preferably, the outlier removal and data calibration of the initial oxygen content detection data in step S3 includes: Step S31: Use the Grubbs criterion to screen outliers in the initial oxygen content detection data and remove outliers that exceed the confidence interval; Step S32: Obtain the standard gas calibration curve built into the Yokogawa gas detection device, substitute the detection data after removing outliers into the calibration curve, and calculate the calibrated oxygen content data. Step S33: Compare the calibrated data with the preset standard oxygen content data under the temperature and pressure parameters in the flue at the same time. If the data deviation is less than the set compensation deviation threshold, it is determined as accurate oxygen content data; otherwise, based on the temperature and pressure parameters in the flue at the same time, the calibrated data is corrected a second time using the temperature-pressure compensation formula to obtain accurate oxygen content data.

[0011] Preferably, the temperature-pressure compensation formula is: O2cal=O2det×(P0 / Pdet)×[(Tdet+273.15) / (T0+273.15)]; Where O2cal is the oxygen content data after secondary correction, O2det is the oxygen content data after calibration, P0 is the standard atmospheric pressure, T0 is the standard ambient temperature, Pdet is the real-time pressure inside the flue, and Tdet is the real-time temperature inside the flue.

[0012] Preferably, in step S3, the early warning mechanism includes: When the precise oxygen content data is higher than the upper limit of the normal oxygen content range, an audible and visual warning of excessive oxygen content in the flue is issued, and an air volume adjustment signal is sent to the sintering machine control system. When the precise oxygen content data is lower than the lower limit of the normal oxygen content range, an audible and visual warning of low oxygen content in the flue is issued, and a gas ratio adjustment signal is sent to the gas supply system.

[0013] Preferably, the method further includes periodically calibrating the Yokogawa gas detection device: At each preset calibration cycle, the sampling probe of the Yokogawa gas detector is connected to a standard oxygen content gas cylinder to collect a standard gas sample and perform testing. The test results are compared with the actual oxygen content of the standard gas. If the deviation is greater than the set calibration deviation threshold, the sensor sensitivity parameters of the detector are adjusted until the detection deviation meets the requirements.

[0014] This invention provides an oxygen content detection system for a sintering machine flue, using the aforementioned method for detecting oxygen content in a sintering machine flue. The system includes a sintering machine flue sensor unit, a main control unit, an early warning unit, a sintering machine control system, a gas supply system, a Yokogawa gas detection device, and a standard gas calibration tank. The main control unit is connected to the sintering machine flue sensor unit, the early warning unit, the sintering machine control system, and the gas supply system. The standard gas calibration tank is used to calibrate the Yokogawa gas detection device. The sintering machine flue sensor unit includes an airflow velocity sensor, a temperature sensor, and a pressure sensor, all of which are connected to the main control unit.

[0015] Preferably, the Yokogawa gas detection device includes a sampling module, a detection module, and a data processing module connected in sequence, all of which are connected to the main control unit. The sampling module includes a retractable sampling tube and a flow control valve. The sampling tube is connected to the inlet of the detection module through the flow control valve, which is used to adjust the sampling flow rate according to the instructions of the main control unit.

[0016] The technical effects of this invention are as follows: 1. High detection accuracy: By using airflow stability assessment, multi-location sampling, outlier removal, and temperature-pressure compensation, combined with the high-precision performance of Yokogawa gas detection devices, the accuracy of oxygen content detection data is significantly improved; 2. Strong dynamic adaptability: It can adjust the sampling position and detection parameters according to changes in airflow, temperature and pressure in the flue, ensuring that the detection data reflects the actual working conditions in real time; 3. Highly efficient early warning and linkage: When the oxygen content is abnormal, it can quickly trigger a graded early warning and link with the sintering machine production system to adjust production parameters in a timely manner and reduce production losses; 4. Good long-term stability: Establish a regular calibration process to ensure that the testing device is in a precise state for a long time and avoid the decline in accuracy due to equipment aging.

[0017] The method and system of this invention can fully leverage the advantages of Yokogawa's gas detection devices, solve the pain point problem of oxygen content detection in the main flue of existing sintering machines, and provide reliable oxygen content data support for stable, efficient, and low-consumption operation of sintering production. Attached Figure Description

[0018] Figure 1 A flowchart of a method for detecting oxygen content in the main flue of a sintering machine, provided by an embodiment of the present invention; Figure 2 This is a structural block diagram of an oxygen content detection system for a sintering machine flue provided in an embodiment of the present invention. Detailed Implementation

[0019] The following is a further detailed description of the specific implementation of the present invention by describing the embodiments in conjunction with the attached drawings, aiming to help those skilled in the art have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention, and contribute to its implementation. It should be noted that the terms "first", "second", etc. described in this application are only for the convenience of describing the technical solution to distinguish components, and the corresponding component configurations may be the same or different, and this application is not limited thereby. To make the technical solution of the present invention clearer, the present invention is explained and illustrated through the following embodiments.

[0020] An embodiment of the present invention provides a method for detecting the oxygen content in the main flue of a sintering machine, aiming to solve the problems of low detection accuracy, lack of dynamic adjustment and linkage warning, and non-standard calibration in the existing detection of the oxygen content in the main flue of a sintering machine, giving full play to the performance advantages of the Yokogawa gas detection device, realizing accurate and real-time detection of the oxygen content in the flue, and ensuring the stable and efficient operation of sintering production. As Figure 1 shown, the method includes the following steps: Step S1: Determine the airflow stability of the detection area of the main flue of the sintering machine. If the determination result is that the airflow is in a stable state, continue to the next step; Step S2: In the detection area of the main flue of the sintering machine, use the Yokogawa gas detection device to detect the oxygen content and obtain the initial oxygen content detection data; Step S3: Remove outliers and calibrate the initial oxygen content detection data to obtain accurate oxygen content data. If the accurate oxygen content data is within the preset normal oxygen content range, the single detection is completed; if it exceeds the preset normal oxygen content range, trigger the warning mechanism and execute Step S4; Step S4: Adjust the sampling position and detection parameters of the Yokogawa gas detection device, and repeat Steps S2 and S3 until the accurate oxygen content data is within the preset normal oxygen content range or stop actively after confirming the abnormal reason.

[0021] Specifically, referring to Step S1, before detecting the oxygen content in the main flue of the sintering machine, it is necessary to determine the airflow stability. Unstable airflow will cause uneven mixing of air and flue gas in the sampling sample, affecting the accuracy of oxygen content detection. Therefore, it is necessary to first determine the airflow state to ensure that the sampling conditions meet the requirements. The airflow stability determination method in this embodiment includes: Step S11: At least three airflow velocity sensors are deployed around the detection area of ​​the sintering machine's main flue to synchronously collect the real-time airflow velocity at the location of each sensor. The deployment of the airflow velocity sensors shall meet the following conditions: the distance between the airflow velocity sensor and the inner wall of the sintering machine's main flue shall not be less than 1 / 10 of the flue diameter, and the central angles between two adjacent sensors shall be equal to ensure coverage of different airflow areas in the flue cross-section. This deployment method can avoid the sensor being affected by the airflow eddies on the flue wall, while achieving comprehensive monitoring of the cross-sectional airflow. Step S12: In any pairwise sensor combination, calculate the airflow velocity difference between all sensor combinations. If all differences are less than the set velocity difference threshold (e.g., 0.2 m / s) and the duration reaches the set stability determination time (e.g., 30 seconds), the airflow is considered to be in a stable state; otherwise, the airflow is considered unstable, and step S11 is repeated after a preset interval (e.g., 1 minute). Through multi-sensor synchronous monitoring and difference determination, the stability of the airflow can be accurately identified, providing reliable conditions for subsequent sampling.

[0022] Referring to step S2, under the premise of stable airflow, this embodiment uses a Yokogawa gas detection device (model: Yokogawa ZR802G series) to detect oxygen content.

[0023] First, it is necessary to set the oxygen content detection parameters of the Yokogawa gas detection device, including the detection cycle, sampling flow rate, and data filtering threshold. In this embodiment, the detection cycle is set to 2 minutes / time, the sampling flow rate is 1L / min, and the data filtering threshold is 0.05% to ensure the stability and timeliness of the detection data.

[0024] Then, the sampling probe of the Yokogawa gas detection device can be controlled to extend into the detection area of ​​the sintering machine's main flue to collect gas samples from the flue, perform oxygen content detection, and obtain initial oxygen content detection data. Specifically, in this embodiment, multiple target detection positions are set within the detection area of ​​the sintering machine's main flue. The sampling probe of the Yokogawa gas detection device sequentially collects gas samples from each target detection position in a preset order to perform oxygen content detection. The method for determining the target detection positions is as follows: based on the diameter of the sintering machine's main flue and the airflow direction within the flue, the cross-section of the flue is divided into a central area, a middle ring area, and an edge area. Multiple evenly distributed sampling points are selected as target detection positions (usually 2 to 3) within each area. Finally, the retractable sampling tube of the Yokogawa gas detection device can be controlled to extend into each target detection position, sequentially collect gas samples, perform oxygen content detection, and obtain initial oxygen content detection data.

[0025] Referring to step S3, the initial oxygen content detection data typically contains outliers and cannot meet the requirements for data reliability. Therefore, step S3 performs outlier removal and data calibration on the initial oxygen content detection data. The specific methods include: Step S31: Use the Grubbs criterion to screen outliers in the initial oxygen content detection data and remove outliers that exceed the confidence interval (e.g., 95% confidence level). The Grubbs criterion can effectively identify outliers caused by instantaneous equipment interference or sampling errors, ensuring the reliability of the basic data. Step S32: Obtain the standard gas calibration curve built into the Yokogawa gas detection device, substitute the detection data after removing outliers into the calibration curve, and calculate the calibrated oxygen content data; perform preliminary calibration using the device's built-in calibration curve to correct errors caused by sensor drift. Step S33: Compare the calibrated data with the preset standard oxygen content data (obtainable through extensive experimental statistics) under the same temperature and pressure parameters in the flue at the same time. If the data deviation is less than the set compensation deviation threshold (e.g., 0.1%), it is determined as accurate oxygen content data; otherwise, based on the temperature and pressure parameters in the flue at the same time, the calibrated data is corrected a second time using the temperature-pressure compensation formula to obtain accurate oxygen content data. That is, a second correction is performed based on the actual temperature and pressure parameters of the flue, further eliminating the influence of environmental factors on the test results, improving data accuracy, and finally obtaining accurate oxygen content data.

[0026] The temperature-pressure compensation formula in this embodiment is: O2cal=O2det×(P0 / Pdet)×[(Tdet+273.15) / (T0+273.15)]; Wherein, O2cal represents the oxygen content data after secondary correction, O2det represents the calibrated oxygen content data, P0 is the standard atmospheric pressure, T0 is the standard ambient temperature, Pdet is the real-time pressure inside the flue, and Tdet is the real-time temperature inside the flue. This formula is derived based on the ideal gas law and can accurately correct for the influence of temperature and pressure changes on oxygen content detection, ensuring the accuracy of data under different operating conditions.

[0027] Step S3 further determines whether the precise oxygen content data is within the normal oxygen content range, and thus determines whether the oxygen content is abnormal. If the precise oxygen content data is within the preset normal oxygen content range, a single test is completed; if it exceeds the preset normal oxygen content range, it is determined that the oxygen content is abnormal, at which point an early warning mechanism is triggered and step S4 is executed.

[0028] In this embodiment, the early warning mechanism includes: When the precise oxygen content data is higher than the upper limit of the normal oxygen content range (such as 16%), an audible and visual warning of excessive oxygen content in the flue is issued, and an air volume adjustment signal is sent to the sintering machine control system to control the fan to reduce the air volume. When the precise oxygen content data falls below the lower limit threshold (10%) of the normal oxygen content range, an audible and visual warning of excessively low oxygen content in the flue gas duct is issued, and a gas ratio adjustment signal is sent to the gas supply system to increase the gas supply. Through linkage with the production system, it can quickly respond to abnormal oxygen content and reduce production losses.

[0029] Referring to step S4, in the event of abnormal oxygen content, this embodiment adjusts the sampling position and detection parameters of the Yokogawa gas detection device and repeats steps S2 and S3 until the accurate oxygen content data is within the preset normal oxygen content range or the abnormality is confirmed and then actively stopped. For example, when the oxygen content is abnormal, the influence of local abnormal airflow is eliminated by adjusting the sampling position, and the detection parameters are adjusted (such as increasing the sampling flow rate and shortening the detection cycle) to increase the detection frequency, quickly locate the cause of the abnormality, and assist in solving the problem.

[0030] In addition, this embodiment also performs periodic calibration on the Yokogawa gas detection device. Periodic calibration ensures that the detection device remains in a state of accurate detection over a long period, avoiding accuracy degradation caused by sensor aging. The periodic calibration method includes: At each preset calibration cycle (e.g., 1 month), the sampling probe of the Yokogawa gas detector is connected to a standard oxygen-containing gas cylinder (e.g., a standard gas with an oxygen content of 5%), a standard gas sample is collected and tested, and the test results are compared with the actual oxygen content of the standard gas. If the deviation is greater than the set calibration deviation threshold (e.g., 0.2%), the sensor sensitivity parameters of the detector are adjusted until the detection deviation meets the requirements.

[0031] Based on the above, one application scenario of this invention is as follows: (1) Determine the airflow stability of the detection area of ​​the sintering machine's main flue: Four airflow velocity sensors are set up around the detection area of ​​the sintering machine's main flue (diameter 3m). The distance between the sensors and the inner wall of the flue is 0.3m (i.e., 1 / 10 of the flue diameter), and the arc length between adjacent sensors is equal. The real-time airflow velocity of each sensor is collected synchronously, and the velocity difference between any two sensors is calculated. If all differences are less than 0.2m / s and last for 30 seconds, the airflow is determined to be stable, and step (2) is executed; otherwise, wait for 1 minute and re-detect.

[0032] (2) Start the Yokogawa gas detection device (model: Yokogawa ZR802G series), set the detection parameters: detection cycle is 2 minutes / time, sampling flow rate is 1L / min, data filtering threshold is 0.05%, and ensure the stability and timeliness of the detection data.

[0033] (3) Determine the target detection location and collect gas samples: Divide the flue cross-section into a central area (radius 0-0.5m), a middle ring area (radius 0.5-1.0m), and an edge area (radius 1.0-1.5m). Select 2 sampling points in each area, for a total of 6 target detection locations. Control the retractable sampling tube of the Yokogawa gas detection device to extend into each target location, collect gas samples in sequence, perform oxygen content detection, and obtain 6 sets of initial oxygen content detection data.

[0034] (4) Outlier removal and data calibration: The Grubbs criterion (95% confidence level) was used to screen the 6 sets of initial data. One set of outlier data that exceeded the confidence interval was removed (e.g., the initial data were 14.2%, 14.3%, 14.1%, 14.4%, 20.2%, 14.3%, and 10.2%). The remaining 5 sets of data were substituted into the standard calibration curve built into the Yokogawa detection device to obtain the calibrated oxygen content data (e.g., 14.22%, 14.31%, 14.10%, 14.42%, 14.33%). The operating parameters were obtained by the temperature sensor (real-time temperature 120℃) and the pressure sensor (real-time pressure 102.5kPa). The parameters were substituted into the temperature-pressure compensation formula for secondary correction to calculate the accurate oxygen content data (e.g., 14.25%, 14.34%, 14.13%, 14.45%, 14.36%). The average value of 14.31% was taken as the final detection result.

[0035] If the preset normal oxygen content range is 10%-16%, and 14.31% is within this range, complete a single test; if the test result is 18.5% (higher than the upper limit), then proceed to step (5).

[0036] (5) Triggering early warning and adjusting detection parameters: Issue an audible and visual early warning of "excessive oxygen content in flue gas" and send a signal to the sintering machine control system to "reduce the fan air volume by 10%"; adjust the sampling flow rate of the Yokogawa detection device to 1.5L / min, shorten the detection cycle to 1 minute / time, recollect gas samples from 3 target locations (2 points in the original middle circle area and 1 point in the central area), repeat steps (3)-(4), obtain new accurate oxygen content data of 15.8% (within the normal range), stop the early warning, and restore the original detection parameters.

[0037] In addition, periodic calibration is performed every month: the sampling probe of the Yokogawa detection device is connected to a standard gas cylinder with an oxygen content of 14%. The detection result is 14.15%, with a deviation of 0.15% (less than the calibration deviation threshold of 0.2%), and no adjustment of the sensor parameters is required. If the next calibration result is 5.3%, with a deviation of 0.3%, the sensor sensitivity is adjusted until the detection result is 14.05%, and the deviation meets the requirements.

[0038] This invention also provides an oxygen content detection system for the main flue gas duct of a sintering machine, using the aforementioned oxygen content detection method for the main flue gas duct of a sintering machine, such as... Figure 2 As shown, the system includes a sintering machine flue gas sensor unit, a main control unit, an early warning unit, a sintering machine control system, a gas supply system, a Yokogawa gas detection device, and a standard gas calibration tank. The main control unit is connected to the sintering machine flue gas sensor unit, the early warning unit, the sintering machine control system, and the gas supply system. The standard gas calibration tank is used to calibrate the Yokogawa gas detection device. Based on a method for detecting oxygen content in a sintering machine flue gas according to an embodiment of the present invention, the main control unit controls the Yokogawa gas detection device to perform oxygen content detection in the sintering machine flue gas, and triggers an early warning or sends a control signal to related systems based on the detection result. The early warning unit includes an audible and visual alarm device.

[0039] The sintering machine flue gas sensor unit includes an airflow velocity sensor, a temperature sensor, and a pressure sensor, all of which are connected to the main control unit. The airflow velocity sensor is located on the inner wall of the sintering machine flue gas and is evenly distributed along the cross-section of the flue gas. The temperature and pressure sensors are located inside the sintering machine flue gas and are used to collect real-time temperature and pressure data within the flue gas, providing temperature-pressure compensation for the oxygen content detection data of the Yokogawa gas detection device.

[0040] The Yokogawa gas detection device is located outside the sintering machine's main flue, with a sampling probe extending into the flue. Specifically, it includes a sampling module, a detection module, and a data processing module connected in sequence. All three modules are connected to the main control unit. The sampling module includes a retractable sampling tube and a flow control valve. The sampling tube is connected to the inlet of the detection module via the flow control valve, which adjusts the sampling flow rate according to instructions from the main control unit. The detection module detects the oxygen content of the collected gas samples, and the data processing module performs preliminary processing of the detection data (e.g., data calibration) before sending it to the main control unit.

[0041] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A method for detecting oxygen content in the main flue gas duct of a sintering machine, characterized in that: The method includes the following steps: Step S1: Determine the airflow stability in the detection area of ​​the sintering machine's main flue. If the determination result is that the airflow is in a stable state, proceed to the next step. Step S2: In the detection area of ​​the sintering machine's main flue, an oxygen content detection device is used to detect the oxygen content and obtain initial oxygen content detection data. Step S3: Remove outliers and calibrate the initial oxygen content detection data to obtain accurate oxygen content data. If the accurate oxygen content data is within the preset normal oxygen content range, the single detection is completed; if it exceeds the preset normal oxygen content range, the early warning mechanism is triggered and step S4 is executed. Step S4: Adjust the sampling position and detection parameters of the Yokogawa gas detection device, and repeat steps S2 and S3 until the accurate oxygen content data is within the preset normal oxygen content range or the abnormality is confirmed and then the process is stopped.

2. The method for detecting oxygen content in the main flue of a sintering machine according to claim 1, characterized in that: The airflow stability determination method in step S1 includes: Step S11: At least three airflow velocity sensors are deployed around the detection area of ​​the sintering machine's main flue to synchronously collect the real-time airflow velocity at the location of each sensor. Step S12: In the case of any two sensors combined, calculate the airflow velocity difference between all sensor combinations. If all differences are less than the set velocity difference threshold and the duration reaches the set stability determination time, the airflow is determined to be in a stable state; otherwise, the airflow is determined to be unstable, and step S11 is re-executed after a preset interval.

3. The method for detecting oxygen content in the main flue of a sintering machine according to claim 2, characterized in that: The placement of the airflow velocity sensor meets the following conditions: the distance between the airflow velocity sensor and the inner wall of the sintering machine's main flue is not less than 1 / 10 of the flue diameter, and the central angles between two adjacent sensors are equal.

4. The method for detecting oxygen content in the main flue of a sintering machine according to claim 1, characterized in that: In step S2, multiple target detection positions are set in the detection area of ​​the sintering machine flue. The sampling probe of the Yokogawa gas detection device collects gas from each target detection position in a preset order to perform oxygen content detection. The method for determining the target detection positions is as follows: based on the diameter of the sintering machine flue and the airflow direction in the flue, the cross-section of the flue is divided into a central area, a middle ring area, and an edge area. Multiple evenly distributed sampling points are selected in each area as target detection positions.

5. The method for detecting oxygen content in the main flue of a sintering machine according to claim 1, characterized in that: In step S3, outlier removal and data calibration of the initial oxygen content detection data include: Step S31: Use the Grubbs criterion to screen outliers in the initial oxygen content detection data and remove outliers that exceed the confidence interval; Step S32: Obtain the standard gas calibration curve built into the Yokogawa gas detection device, substitute the detection data after removing outliers into the calibration curve, and calculate the calibrated oxygen content data. Step S33: Compare the calibrated data with the preset standard oxygen content data under the temperature and pressure parameters in the flue at the same time. If the data deviation is less than the set compensation deviation threshold, it is determined as accurate oxygen content data; otherwise, based on the temperature and pressure parameters in the flue at the same time, the calibrated data is corrected a second time using the temperature-pressure compensation formula to obtain accurate oxygen content data.

6. The method for detecting oxygen content in the main flue of a sintering machine according to claim 5, characterized in that: The temperature-pressure compensation formula is as follows: O2cal=O2det×(P0 / Pdet)×[(Tdet+273.15) / (T0+273.15)]; Where O2cal is the oxygen content data after secondary correction, O2det is the oxygen content data after calibration, P0 is the standard atmospheric pressure, T0 is the standard ambient temperature, Pdet is the real-time pressure inside the flue, and Tdet is the real-time temperature inside the flue.

7. The method for detecting oxygen content in the main flue of a sintering machine according to claim 1, characterized in that: In step S3, the early warning mechanism includes: When the precise oxygen content data is higher than the upper limit of the normal oxygen content range, an audible and visual warning of excessive oxygen content in the flue is issued, and an air volume adjustment signal is sent to the sintering machine control system. When the precise oxygen content data is lower than the lower limit of the normal oxygen content range, an audible and visual warning of low oxygen content in the flue is issued, and a gas ratio adjustment signal is sent to the gas supply system.

8. The method for detecting oxygen content in the main flue of a sintering machine according to claim 1, characterized in that: The method also includes periodically calibrating the Yokogawa gas detection device: At each preset calibration cycle, the sampling probe of the Yokogawa gas detector is connected to a standard oxygen content gas cylinder to collect a standard gas sample and perform testing. The test results are compared with the actual oxygen content of the standard gas. If the deviation is greater than the set calibration deviation threshold, the sensor sensitivity parameters of the detector are adjusted until the detection deviation meets the requirements.

9. A system for detecting oxygen content in the main flue of a sintering machine, using the method for detecting oxygen content in the main flue of a sintering machine according to any one of claims 1-8, characterized in that: The system includes a sintering machine flue gas sensor unit, a main control unit, an early warning unit, a sintering machine control system, a gas supply system, a Yokogawa gas detection device, and a standard gas calibration tank. The main control unit is connected to the sintering machine flue gas sensor unit, the early warning unit, the sintering machine control system, and the gas supply system. The standard gas calibration tank is used to calibrate the Yokogawa gas detection device. The sintering machine flue gas sensor unit includes an airflow velocity sensor, a temperature sensor, and a pressure sensor, all of which are connected to the main control unit.

10. The oxygen content detection system for the main flue gas duct of a sintering machine according to claim 9, characterized in that: The Yokogawa gas detection device includes a sampling module, a detection module, and a data processing module connected in sequence. The data processing module, detection module, and sampling module are all connected to the main control unit. The sampling module includes a retractable sampling tube and a flow control valve. The sampling tube is connected to the inlet of the detection module through the flow control valve. The flow control valve is used to adjust the sampling flow rate according to the instructions of the main control unit.

Images