A mid-infrared laser carbon dioxide detection device and method for fixed pollution source

Abstract

The invention discloses a mid-infrared laser carbon dioxide detection device and method for a fixed pollution source, which relates to the technical field of gas content measurement, and comprises: obtaining multiple groups of concentration data groups, calculating and analyzing the concentration data groups, and outputting a slope threshold; building a gas analysis device, calibrating the gas analysis device, and outputting device completion information; using the gas analysis device to monitor the carbon dioxide concentration of the air at the fixed pollution source, and outputting the detected concentration; analyzing the detected concentration, and performing concentration prediction processing or change judgment processing based on the analysis result; the invention is used to solve the problem that the existing carbon dioxide gas detection method lacks a data verification process when abnormal data is detected, thereby resulting in inaccurate detection results.

Description

Technical Field

[0001] The invention relates to the technical field of gas content measurement, and in particular to a mid-infrared laser carbon dioxide detection device and method for a fixed pollution source. Background Art

[0002] Carbon dioxide (CO2) is a greenhouse gas that has a significant impact on global climate change. Through the carbon dioxide online monitoring system, real-time control and effective management of carbon emissions from thermal power plants, industrial boilers, waste gas treatment facilities, urban heating systems, waste incineration plants, industrial parks, environmental monitoring stations, scientific research institutions and other facilities can be achieved, providing data support and technical guarantee.

[0003] The existing methods for carbon dioxide gas detection usually improve the accuracy and stability of the gas detection system. For example, in the Chinese patent with invention publication number CN115656160A, a system and method for measuring the carbon dioxide content in the flue gas of a fixed pollution source are disclosed. The scheme is to set an absorption pool and an absorption container at the fixed pollution source, and selectively optimize the internal components of the absorption pool and the absorption container, so as to achieve continuous and accurate measurement of the carbon dioxide content in the flue gas of the fixed pollution source; other common detection methods often set an upper limit threshold of concentration after calibrating the detection equipment. If the real-time concentration is detected to be greater than the set upper limit threshold during the detection process, an alarm will be directly triggered; but under the premise of long-term continuous operation of the equipment, the detection result may be erroneous due to problems with the equipment itself, so that the detected concentration is greater than the concentration threshold; in this case, if the alarm is triggered, it will increase the invalid workload for the relevant staff; in view of this, it is necessary to improve the existing carbon dioxide gas detection method. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the prior art to at least a certain extent, by analyzing historical concentration data to obtain a slope threshold, and then analyzing the abnormal detection data obtained according to the slope threshold to determine whether the abnormal data obtained is true; finally, based on the judgment result, the abnormal data is corrected or the equipment calibration information is output; so as to solve the problem that the existing carbon dioxide gas detection method lacks a data verification process when abnormal data is detected, thereby resulting in inaccurate detection results and increased workload.

[0005] To achieve the above objectives, in a first aspect, the present application provides a mid-infrared laser carbon dioxide detection method for a fixed pollution source, comprising the following steps:

[0006] Acquire multiple concentration data sets, perform calculation and analysis on the concentration data sets, and output a slope threshold value based on the calculation and analysis results;

[0007] Build gas analysis equipment, calibrate the gas analysis equipment, and output equipment completion information based on the calibration results;

[0008] Based on the information completed by the equipment, the carbon dioxide concentration in the air at the fixed pollution source is monitored using gas analysis equipment to output the detected concentration; the detected concentration is analyzed, and concentration prediction processing or change judgment processing is performed based on the analysis results; operation judgment information is output based on the concentration prediction processing; based on the change judgment processing results, data calibration processing is performed on the detected concentration or equipment calibration information is output.

[0009] Furthermore, among the multiple concentration data groups, each concentration data group includes a plurality of historical concentration data; the historical concentration data includes normal historical concentration, abnormal historical concentration and acquisition time corresponding to the historical concentration data;

[0010] The abnormal historical concentration is a carbon dioxide concentration greater than a concentration threshold value obtained during measurement; the normal historical concentration is a carbon dioxide concentration less than or equal to the concentration threshold value obtained during measurement.

[0011] Further, a plurality of concentration data sets are obtained, and calculation and analysis are performed on the concentration data sets. The slope threshold is output based on the calculation and analysis results, including:

[0012] Acquire multiple concentration data sets, and for each concentration data set, establish a concentration scatter plot with the horizontal axis representing the acquisition time and the vertical axis representing the carbon dioxide concentration;

[0013] Calculate the slope of two adjacent points in the concentration scatter plot and mark it as the change slope;

[0014] Dividing the interval values ​​of the minimum change slope and the maximum change slope to obtain a first number of slope intervals;

[0015] The changing slope in each slope interval is counted and marked as the interval slope number;

[0016] Calculate the ratio of the number of slopes in each interval to the total number of changing slopes, and mark it as interval probability;

[0017] Randomly select 100 change slopes, count the slope threshold of each interval in the randomly selected change slopes, and express it as a percentage, marked as the test probability;

[0018] Calculate the ratio of the test probability to the interval probability, labeled as the probability ratio;

[0019] Compare the probability ratio with the probability threshold. If the probability ratio is greater than or equal to the probability threshold, mark the corresponding slope interval as a reference interval; if the probability ratio is less than the probability threshold, mark the corresponding slope interval as an invalid interval.

[0020] Mark the largest right endpoint of all reference intervals as the slope threshold.

[0021] Furthermore, a gas analysis device is built and calibrated, and the device completion information output based on the calibration result includes:

[0022] Building a gas analysis device, the gas analysis device comprising a light source, a measurement cavity and a detector;

[0023] A gas sample with a known carbon dioxide concentration is placed in the measurement chamber, and the light source is controlled to emit laser light;

[0024] The detector is used to receive the absorption signal, and the concentration of carbon dioxide in the measured gas sample is calculated and marked as the measured concentration;

[0025] Adjust the optical path in the measurement chamber so that the measured concentration is equal to the carbon dioxide concentration of the gas sample, and output the device completion information.

[0026] Further, based on the equipment completion information, the carbon dioxide concentration of the air at the fixed pollution source is monitored by using a gas analysis device, and the detection concentration is output; the detection concentration is analyzed, and concentration prediction processing or change judgment processing is performed based on the analysis result; operation judgment information is output based on the concentration prediction processing; data calibration processing or device calibration information is output based on the change judgment processing result, including:

[0027] Use gas analysis equipment to monitor fixed pollution sources, obtain the carbon dioxide concentration of the air at the fixed pollution source once every interval, mark it as the detection concentration; output the detection concentration and detection time;

[0028] When a new detection concentration is obtained, the detection concentration is compared with the concentration threshold. If the detection concentration is less than the concentration threshold, a concentration prediction process is performed, and operation judgment information is output based on the concentration prediction process.

[0029] If the detected concentration is greater than or equal to the concentration threshold, a change judgment process is performed; based on the change judgment process result, data calibration processing is performed on the detected concentration or device calibration information is output.

[0030] Furthermore, the operation judgment information includes concentration stability information and concentration warning information; and the concentration prediction processing includes:

[0031] Marking the detection time of the most recently acquired detection concentration as the second time;

[0032] Obtaining a second number of detection concentrations whose detection time is closest to the second time;

[0033] A scatter plot is established based on the detection concentration and the detection time, and a function fitting is performed on the data in the scatter plot to obtain a function with time as the independent variable and concentration as the dependent variable;

[0034] The fitted function is marked as the concentration prediction function;

[0035] Calculate the first time and the second time using the time calculation formula and output the predicted time;

[0036] The time calculation formula is configured as: ; Where Ty is the prediction time, T1 is the first time, T2 is the second time, and k is a constant;

[0037] Substitute the value of Ty into the concentration prediction function for calculation and output the predicted concentration;

[0038] Compare the predicted concentration with the concentration threshold. If the predicted concentration is less than the concentration threshold, output concentration stability information; if the predicted concentration is greater than or equal to the concentration threshold, output concentration warning information.

[0039] Furthermore, the change determination process includes:

[0040] The most recently acquired detection concentration is marked as n1, and the detection time corresponding to n1 is marked as j1;

[0041] Get the detection concentration and detection time closest to j1, marked as n2 and j2 respectively;

[0042] Combine n1 and j1 to get coordinate point 1 (j1, n1); combine n2 and j2 to get coordinate point 2 (j2, n2);

[0043] Use the two-point slope calculation formula to calculate coordinate point 1 and coordinate point 2, and output the analysis slope;

[0044] Compare the analysis slope with the slope threshold. If the analysis slope is less than or equal to the slope threshold, output the concentration limit exceeding information.

[0045] If the analysis slope is greater than the slope threshold, frequency conversion detection processing is performed, and data calibration processing is performed or device calibration information is output based on the frequency conversion detection processing result.

[0046] Furthermore, the frequency conversion detection process includes:

[0047] adjusting the acquisition interval of the gas analysis device from the first time to the third time;

[0048] Continue to monitor the carbon dioxide concentration in the air at the fixed pollution source, and mark the third most recently detected carbon dioxide concentration as the analysis concentration;

[0049] Compare each analytical concentration with the concentration threshold. If all analytical concentrations are less than the concentration threshold, perform data calibration on the detection concentration n1.

[0050] If any of the analyzed concentrations is greater than the concentration threshold, the device calibration information is output.

[0051] Furthermore, the data calibration process includes:

[0052] Calculate the average of all analyzed concentrations and label it as the calibration concentration;

[0053] Update the value of the detected concentration n1 to the value of the calibration concentration.

[0054] In a second aspect, the present application provides a mid-infrared laser carbon dioxide detection device for a fixed pollution source, including an analysis preparation module, an equipment construction module, and a monitoring and analysis module;

[0055] The analysis preparation module is used to obtain multiple concentration data groups, perform calculation analysis on the concentration data groups, and output a slope threshold value based on the calculation analysis results;

[0056] The equipment construction module is used to build a gas analysis device, calibrate the gas analysis device, and output equipment completion information based on the calibration result;

[0057] The monitoring and analysis module is used to monitor the carbon dioxide concentration in the air at a fixed pollution source using a gas analysis device based on the equipment completion information, and output the detected concentration; analyze the detected concentration, and perform concentration prediction processing or change judgment processing based on the analysis results; output operation judgment information based on the concentration prediction processing; and perform data calibration processing on the detected concentration or output equipment calibration information based on the change judgment processing results.

[0058] Beneficial effects of the present invention: The present invention obtains multiple groups of concentration data sets, performs calculation and analysis on the multiple groups of concentration data sets, and obtains a slope threshold; then builds a gas analysis device based on mid-infrared laser measurement, and uses the gas analysis device to monitor the carbon dioxide concentration at a fixed pollution source; the advantage of this is that the mid-infrared laser measurement has high selectivity and can target the absorption peak of a specific gas to reduce interference from other gases; on the other hand, by increasing the optical path and using modulation technology, low concentrations of carbon dioxide can be detected, thereby improving the accuracy of carbon dioxide concentration detection;

[0059] The present invention also analyzes the detection data obtained by the detection, performs concentration prediction processing based on the analysis result, and outputs operation judgment information; or performs change judgment processing based on the analysis result, and further performs data calibration processing or outputs equipment calibration information based on the change judgment processing result; the advantage of this is that when the detection data obtained by the detection is analyzed, it is possible to determine whether the data is abnormal; in the absence of abnormal data, the future carbon dioxide concentration of the fixed pollution source is predicted to reduce the occurrence of the concentration exceeding the set threshold; in the presence of abnormal data, the abnormal data can be verified to determine whether the data is true. If the data is true, if the data is not true, it is further determined whether the equipment is normal, and finally the abnormal data is calibrated or the equipment calibration information is output; the intelligence of the system operation is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 is a principle block diagram of the device of the present invention;

[0061] Figure 2 It is a partial data flow diagram of the present invention;

[0062] Figure 3 The concentration scatter points in one case of the present invention are Figure 1 ;

[0063] Figure 4 The concentration scatter points in another case of the present invention are Figure 2 ;

[0064] Figure 5 The figure is a flow chart of the steps of the method of the present invention. DETAILED DESCRIPTION

[0065] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0066] Example 1, please refer to Figure 1 as well as Figure 2 As shown, in the first aspect, the present application provides a mid-infrared laser carbon dioxide detection device for a fixed pollution source, including an analysis preparation module, an equipment construction module, and a monitoring and analysis module;

[0067] The analysis preparation module is used to obtain multiple concentration data sets, perform calculation analysis on the concentration data sets, and output a slope threshold value based on the calculation analysis results;

[0068] The analysis preparation module is configured with a slope calculation strategy, which includes:

[0069] Acquire multiple concentration data sets, and for each concentration data set, establish a concentration scatter plot with the horizontal axis representing the acquisition time and the vertical axis representing the carbon dioxide concentration;

[0070] It should be noted that, among the multiple concentration data groups, each concentration data group contains multiple historical concentration data; the historical concentration data includes normal historical concentration, abnormal historical concentration and acquisition time corresponding to the historical concentration data; wherein the abnormal historical concentration is a carbon dioxide concentration greater than the concentration threshold value obtained during measurement; the normal historical concentration is a carbon dioxide concentration less than or equal to the concentration threshold value obtained during measurement;

[0071] Each concentration data group is a data group in which the carbon dioxide concentration gradually increases and eventually exceeds the concentration threshold during monitoring. The purpose of selecting the abnormal concentration data group is to obtain the maximum rate of increase of carbon dioxide concentration, that is, the slope threshold, by calculating and analyzing the data of multiple groups. Then, when the latest abnormal concentration data is obtained in subsequent monitoring, its rising rate is calculated to determine whether the data is true, so as to realize data verification processing of abnormal data.

[0072] In the specific implementation, taking the fixed pollution source as a waste incineration plant as an example, based on the monitoring and analysis of the concentration of the waste gas discharged by the waste incineration plant, the waste gas content of carbon dioxide in the waste incineration flue gas is usually in the range of 10% to 15%, so the concentration threshold is set to 15%; on this basis, the two possible concentration data groups obtained are shown in Table 1-Concentration Data Table:

[0073] Table 1 - Concentration data table

[0074]

[0075] In the two concentration data groups, the concentration less than 15.0 is the normal historical concentration, and the concentration greater than 15.0 is the abnormal historical concentration; the acquisition time is uniformly replaced with a number starting from 1 for the convenience of display and calculation; the same acquisition time in different concentration data groups may not be the same as the actual acquisition time before replacement;

[0076] Taking the data in concentration data group 1 as an example, we can establish Figure 3 The concentration scatter plots shown Figure 1 , taking the data in concentration data group 2 as an example, we can establish Figure 4 The concentration scatter plots shown Figure 2 ; Figure 3 as well as Figure 4 In the example, the value between two adjacent scattered points is the change slope of the two adjacent points; if only Figure 3 and Figure 4By analyzing the change slope in , the maximum change slope is 0.8, and 0.8 is marked as the slope threshold;

[0077] Calculate the slope of two adjacent points in the concentration scatter plot and mark it as the change slope;

[0078] Dividing the interval values ​​of the minimum change slope and the maximum change slope to obtain a first number of slope intervals;

[0079] The changing slope in each slope interval is counted and marked as the interval slope number;

[0080] Calculate the ratio of the number of slopes in each interval to the total number of changing slopes, and mark it as interval probability;

[0081] Randomly select 100 change slopes, count the slope threshold of each interval in the randomly selected change slopes, and express it as a percentage, marked as the test probability;

[0082] Calculate the ratio of the test probability to the interval probability, labeled as the probability ratio;

[0083] Compare the probability ratio with the probability threshold. If the probability ratio is greater than or equal to the probability threshold, mark the corresponding slope interval as a reference interval; if the probability ratio is less than the probability threshold, mark the corresponding slope interval as an invalid interval.

[0084] The right endpoint of the largest interval among all reference intervals is marked as the slope threshold;

[0085] In a specific implementation, the first number is set to 10, that is, there are 10 groups of slope intervals between the minimum change slope and the maximum change slope;

[0086] The probability threshold is set to 0.5. Taking a random slope interval as an example, if the interval probability of the slope interval is 10%, then among 100 randomly selected change slopes, about 10 change slopes are within the slope interval. Only in a few cases, when no more than 4 change slopes among 100 change slopes are within the slope interval, will this slope interval be marked as an invalid interval.

[0087] Taking a waste incineration plant as an example, when burning waste, the concentration of carbon dioxide in the exhaust gas will change synchronously with the input of the incinerated materials and the changes in the incineration process. In the process of putting in waste, due to the increase of combustible materials, the concentration of carbon dioxide in the exhaust gas may increase sharply instantly. In this case, the slope of the change will become very large. If the maximum change slope is directly used as the slope threshold, the subsequent analysis results will be inaccurate. Therefore, the change slope is divided into intervals, and then the slope within the slope interval is verified by random sampling to obtain a slope threshold with reference significance.

[0088] The equipment construction module is used to build gas analysis equipment, calibrate the gas analysis equipment, and output equipment completion information based on the calibration results;

[0089] The device build module is configured with a device build strategy, which includes:

[0090] Build gas analysis equipment, which includes light source, measurement chamber and detector;

[0091] In the specific implementation, the light source is a quantum cascade laser (QCL), which can emit mid-infrared laser covering the carbon dioxide absorption peak (for example, near 4.26 microns); in the measurement cavity, high-reflectivity mirrors are installed at both ends of the cavity to increase the optical path, thereby improving the detection sensitivity; finally, a detector with high sensitivity and suitable for the mid-infrared band is selected, and the signal-to-noise ratio of the signal is improved by using wavelength modulation spectroscopy (WMS) or direct absorption spectroscopy (DAS) technology, thereby improving the detection accuracy; finally, the absorption signal is collected by the detector, and the concentration of carbon dioxide is calculated using the Beer-Lambert law;

[0092] A gas sample with a known carbon dioxide concentration is placed in the measurement chamber, and the light source is controlled to emit laser light;

[0093] In specific implementation, a gas sample with a known carbon dioxide concentration can be obtained by collecting an air sample and then analyzing the air sample using other calibrated gas analysis equipment; the purpose of selecting an air sample is to reduce the cost of artificially manufacturing a gas sample, and in the process of calibrating the equipment, it can eliminate the situation where the gas sample is affected by the air, resulting in deviations in the calibration results, thereby reducing the difficulty of the calibration process;

[0094] The detector is used to receive the absorption signal, and the concentration of carbon dioxide in the measured gas sample is calculated and marked as the measured concentration;

[0095] Adjust the optical path in the measurement cavity so that the measured concentration is equal to the carbon dioxide concentration of the gas sample, and output the device completion information;

[0096] In specific implementation, the carbon dioxide concentration in the air is usually 0.03%. Using air as a sample can increase the detection accuracy of the gas analysis equipment to one ten-thousandth, ensuring the accuracy of the measurement results of the gas analysis equipment.

[0097] The monitoring and analysis module is used to monitor the carbon dioxide concentration in the air at the fixed pollution source using the gas analysis equipment based on the equipment completion information, and output the detection concentration; analyze the detection concentration, and perform concentration prediction processing or change judgment processing based on the analysis results; output operation judgment information based on the concentration prediction processing; perform data calibration processing on the detection concentration or output equipment calibration information based on the change judgment processing results;

[0098] The monitoring and analysis module is configured with detection and judgment strategies, which include:

[0099] Use gas analysis equipment to monitor fixed pollution sources, obtain the carbon dioxide concentration of the air at the fixed pollution source once every interval, mark it as the detection concentration; output the detection concentration and detection time;

[0100] In specific implementation, the first time is set to 1 minute. Its advantages are: it can quickly detect changes in carbon dioxide concentration and provide more detailed data points, which is helpful for analyzing short-term trends and fluctuations; by updating every minute, efficient monitoring and control can be achieved without sacrificing data quality;

[0101] When a new detection concentration is obtained, the detection concentration is compared with the concentration threshold. If the detection concentration is less than the concentration threshold, the concentration prediction information is output;

[0102] If the detected concentration is greater than or equal to the concentration threshold, the change judgment information is output.

[0103] The monitoring and analysis module is also equipped with a concentration prediction strategy, which includes:

[0104] When the concentration prediction information is received, the detection time of the most recently acquired detection concentration is marked as the second time;

[0105] Obtaining a second number of detection concentrations whose detection time is closest to the second time;

[0106] In specific implementation, the second number is set to 9; since the concentration of carbon dioxide emitted by fixed pollution sources is continuously changing, the farther the detection concentration is from the second time, the worse its timeliness is; therefore, the second number is set to 9, plus the latest detection concentration, there are a total of 10 sets of data, and by calculating and analyzing the change of carbon dioxide concentration in a short period of time, a function that can predict the concentration change is obtained;

[0107] A scatter plot is established based on the detection concentration and the detection time, and a function fitting is performed on the data in the scatter plot to obtain a function with time as the independent variable and concentration as the dependent variable;

[0108] The fitted function is marked as the concentration prediction function;

[0109] In the specific implementation, the 10 sets of data obtained are shown in Table 2-Predicted Concentration Table:

[0110] Table 2 - Predicted concentration table

[0111]

[0112] The time indicates the acquisition time, and the size indicates the concentration;

[0113] The concentration prediction function obtained after a function fitting is y=0.12x+13.32; the time after three acquisition cycles is replaced to 13, and x=13 is substituted into the concentration prediction function to obtain y=14.88; at this time, 14.88 is less than 15.0, and the concentration stability information is output;

[0114] It should be noted that the concentration prediction function shows that the concentration is increasing and will definitely exceed the concentration threshold at some point in the future. However, the concentration stability information is still output this time. The purpose is to issue an early warning only when the carbon dioxide concentration is about to exceed the concentration threshold, thereby achieving early warning and reducing the number of warnings.

[0115] Calculate the first time and the second time using the time calculation formula and output the predicted time;

[0116] The time calculation formula is configured as: ; Where Ty is the prediction time, T1 is the first time, T2 is the second time, and k is a constant;

[0117] In the specific implementation, k is set to 3; at this time, the time calculation formula can be used to obtain the time after three acquisition cycles. When T1 is set to 1 minute, if T2 is 12:00; then Ty is calculated to be 12:03; among them, if the predicted time is closer to the current time, the higher the reliability of the prediction, but the less time is used to adjust the operating efficiency of the fixed pollution source; on the other hand, if the predicted time is farther from the current time, the reliability of the predicted result is lower; considering the two aspects, the concentration after three operation cycles is predicted, which ensures the reliability of the prediction results while leaving enough reaction time for adjusting the fixed pollution sources;

[0118] Substitute the value of Ty into the concentration prediction function for calculation and output the predicted concentration;

[0119] Compare the predicted concentration with the concentration threshold. If the predicted concentration is less than the concentration threshold, output concentration stability information; if the predicted concentration is greater than or equal to the concentration threshold, output concentration warning information.

[0120] The monitoring and analysis module is also configured with a change judgment strategy, which includes:

[0121] When the change judgment information is received, the newly acquired detection concentration is marked as n1, and the detection time corresponding to n1 is marked as j1;

[0122] Get the detection concentration and detection time closest to j1, marked as n2 and j2 respectively;

[0123] Combine n1 and j1 to get coordinate point 1 (j1, n1); combine n2 and j2 to get coordinate point 2 (j2, n2);

[0124] Use the two-point slope calculation formula to calculate coordinate point 1 and coordinate point 2, and output the analysis slope;

[0125] In the specific implementation, if the latest detected concentration is 15.6, the corresponding detection time is 13:00, forming coordinate point 1 (13:00, 15.6); then the detected concentration at the detection time of 12:59 is obtained, taking 14.8 as an example, forming coordinate point 2 (12:59, 14.8); at this time, the calculated analysis slope is 0.8, which is equal to the slope threshold, indicating that the carbon dioxide concentration is increasing at a normal rate to exceed the concentration threshold. At this time, it is necessary to output the concentration limit information to remind relevant personnel to take corresponding measures;

[0126] It should be noted that by analyzing multiple groups of data whose concentrations gradually increase and eventually exceed the concentration threshold, the maximum rate of change of gas concentration, that is, the slope threshold, can be obtained; since the device has a concentration prediction strategy, when the fixed pollution source is not adjusted, the detection data should not be greater than the concentration threshold, and at this time, it is necessary to perform data verification processing on the abnormal detection data; that is, when monitoring obtains abnormal detection data, by obtaining the data of an adjacent cycle, and then calculating the slope between the two points, the analysis slope used to determine whether the rising rate is normal is obtained; then the analysis slope is judged to complete the data verification processing;

[0127] Compare the analysis slope with the slope threshold. If the analysis slope is less than or equal to the slope threshold, output the concentration limit exceeding information.

[0128] It should be noted that the concentration prediction strategy is a prediction of possible concentration conditions in the future. When the prediction result is not accurate enough, or when the fixed pollution source is adjusted, the carbon dioxide concentration in the detection data will exceed the concentration threshold. If the data verification shows that the abnormal data is true, then relevant personnel need to deal with the fixed pollution source in a timely manner and output the concentration limit information.

[0129] If the analysis slope is greater than the slope threshold, the frequency conversion detection information is output;

[0130] It should be noted that if the analysis slope is greater than the slope threshold, it means that there is a leap-like increase in the carbon dioxide concentration. At this time, the abnormal data measured is not true; it may be due to accidental errors caused by long-term operation of the equipment, or it may be due to equipment failure. It is necessary to judge both situations and output frequency conversion detection information.

[0131] The monitoring and analysis module is also equipped with a frequency conversion detection strategy, which includes:

[0132] adjusting the acquisition interval of the gas analysis device from the first time to the third time;

[0133] Continue to monitor the carbon dioxide concentration in the air at the fixed pollution source, and mark the third most recently detected carbon dioxide concentration as the analysis concentration;

[0134] In specific implementation, the third time is set to 1 second, and the third number is set to 3; the third time is set to 1 second in order to quickly obtain multiple sets of carbon dioxide concentrations in the current measurement chamber, so that the time node of the measurement is as close as possible to the time when the untrue detection data appears, so as to improve the accuracy of data calibration; the third number is set to 3 in order to reduce the contingency in the frequency conversion detection strategy, and avoid the occurrence of misjudgment caused by accidental circumstances;

[0135] Compare each analytical concentration with the concentration threshold. If all analytical concentrations are less than the concentration threshold, calculate the average of all analytical concentrations and mark it as the calibration concentration.

[0136] Update the value of the detected concentration n1 to the value of the calibration concentration;

[0137] If any of the analyzed concentrations is greater than the concentration threshold, the device calibration information is output;

[0138] It should be noted that if all newly acquired analysis concentrations are less than the concentration threshold, it means that the abnormal data is caused by accidental errors in the equipment, and the normal use of the equipment will not be affected after the data is calibrated; and when any analysis concentration is greater than the concentration threshold, it means that the probability of an error in the equipment is too high, and calibration is required in a timely manner to output the equipment calibration information.

[0139] Example 2, please refer to Figure 5 As shown, in the second aspect, the present application provides a mid-infrared laser carbon dioxide detection method for a fixed pollution source, comprising the following steps:

[0140] Step S1, obtaining multiple concentration data sets, performing calculation and analysis on the concentration data sets, and outputting a slope threshold value based on the calculation and analysis results; Step S1 also includes the following sub-steps:

[0141] Step S101, obtaining multiple concentration data sets, and for each concentration data set, establishing a concentration scatter plot with the horizontal axis representing the acquisition time and the vertical axis representing the carbon dioxide concentration;

[0142] Among the multiple groups of concentration data groups, each concentration data group contains multiple historical concentration data; the historical concentration data include normal historical concentration, abnormal historical concentration and the acquisition time corresponding to the historical concentration data; the abnormal historical concentration is the carbon dioxide concentration obtained when measuring that is greater than the concentration threshold; the normal historical concentration is the carbon dioxide concentration obtained when measuring that is less than or equal to the concentration threshold.

[0143] Step S102, calculating the slope of two adjacent points in the concentration scatter plot, and marking it as a change slope;

[0144] Step S103, dividing the interval values ​​of the minimum change slope and the maximum change slope to obtain a first number of slope intervals;

[0145] Step S104, counting the change slope in each slope interval, and marking it as the interval slope number;

[0146] Step S105, calculating the ratio of the number of slopes in each interval to the total number of changing slopes, and marking it as interval probability;

[0147] Step S106, randomly selecting 100 change slopes, counting the slope threshold of each interval in the randomly selected change slopes, and expressing the result in percentage, which is marked as the test probability;

[0148] Step S107, calculating the ratio of the test probability to the interval probability, marked as the probability ratio;

[0149] Step S108, comparing the probability ratio with the probability threshold, if the probability ratio is greater than or equal to the probability threshold, marking the corresponding slope interval as a reference interval; if the probability ratio is less than the probability threshold, marking the corresponding slope interval as an invalid interval;

[0150] Step S109: Mark the right endpoint of the largest interval among all reference intervals as the slope threshold.

[0151] Step S2, building a gas analysis device, calibrating the gas analysis device, and outputting device completion information based on the calibration result; Step S2 also includes the following sub-steps:

[0152] Step S201, constructing a gas analysis device, the gas analysis device including a light source, a measurement cavity and a detector;

[0153] Step S202, placing a gas sample with a known carbon dioxide concentration in a measurement cavity, and controlling a light source to emit laser;

[0154] Step S203, using the detector to receive the absorption signal, and calculating the concentration of carbon dioxide in the measured gas sample, which is marked as the measured concentration;

[0155] Step S204, adjusting the optical path in the measurement cavity so that the measured concentration is equal to the carbon dioxide concentration of the gas sample, and outputting device completion information.

[0156] Step S3, based on the equipment completion information, the carbon dioxide concentration of the air at the fixed pollution source is monitored by using the gas analysis equipment, and the detection concentration is output; the detection concentration is analyzed, and concentration prediction processing or change judgment processing is performed based on the analysis result; operation judgment information is output based on the concentration prediction processing; data calibration processing is performed on the detection concentration or equipment calibration information is output based on the change judgment processing result; step S3 also includes the following sub-steps:

[0157] Step S3011, using a gas analysis device to monitor a fixed pollution source, obtaining the carbon dioxide concentration of the air at the fixed pollution source once at a first interval, marking it as a detection concentration; and outputting the detection concentration and the detection time;

[0158] Step S3012, when a new detection concentration is obtained, compare the detection concentration with the concentration threshold, if the detection concentration is less than the concentration threshold, execute step S302;

[0159] Step S3013, if the detected concentration is greater than or equal to the concentration threshold, execute step S303;

[0160] Step S302 includes the following sub-steps:

[0161] Step S3021, marking the detection time of the most recently acquired detection concentration as the second time;

[0162] Step S3025, obtaining a second number of detection concentrations whose detection time is closest to the second time;

[0163] Step S3023, establishing a scatter plot based on the detected concentration and the detected time, performing a function fitting on the data in the scatter plot to obtain a function with time as the independent variable and concentration as the dependent variable; marking the fitted function as a concentration prediction function;

[0164] Step S3024, using a time calculation formula to calculate the first time and the second time, and outputting a predicted time; the time calculation formula is configured as: ; Where Ty is the prediction time, T1 is the first time, T2 is the second time, and k is a constant;

[0165] Step S3025, substitute the value of Ty into the concentration prediction function for calculation, and output the predicted concentration;

[0166] Step S3026, compare the predicted concentration with the concentration threshold. If the predicted concentration is less than the concentration threshold, output concentration stability information; if the predicted concentration is greater than or equal to the concentration threshold, output concentration warning information.

[0167] Step S303 includes the following sub-steps:

[0168] Step S3031, mark the latest detected concentration as n1, and mark the detection time corresponding to n1 as j1;

[0169] Step S3032, obtaining the detection concentration and detection time closest to the detection time distance j1, marked as n2 and j2 respectively; combining n1 and j1 to obtain coordinate point 1 (j1, n1); combining n2 and j2 to obtain coordinate point 2 (j2, n2);

[0170] Step S3033, using a two-point slope calculation formula to calculate coordinate point 1 and coordinate point 2, and outputting an analysis slope;

[0171] Step S3034, comparing the analysis slope with the slope threshold, if the analysis slope is less than or equal to the slope threshold, outputting the concentration exceeding limit information;

[0172] Step S3035: If the analysis slope is greater than the slope threshold, execute step S304; step S304 includes the following sub-steps:

[0173] S3041, adjusting the acquisition interval of the gas analysis device from the first time to the third time;

[0174] S3042, continue to monitor the carbon dioxide concentration of the air at the fixed pollution source, and mark the third amount of carbon dioxide concentration detected most recently as the analysis concentration;

[0175] S3043, comparing each analysis concentration with the concentration threshold, if all analysis concentrations are less than the concentration threshold, calculating the average of all analysis concentrations and marking it as calibration concentration;

[0176] Update the value of the detected concentration n1 to the value of the calibration concentration.

[0177] S3044: If any analysis concentration is greater than the concentration threshold, output device calibration information.

[0178] Through the description of the above implementation methods, the embodiments of the present invention can be provided as methods, systems or computer program products. Based on such an understanding, the above technical solutions can be essentially or partly contributed to the prior art in the form of software products, which can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and include several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0179] In the embodiments provided in the present application, it should be understood that the disclosed system or method can be implemented in other ways. The embodiments described above are merely schematic. For example, the division of modules or units is only a logical function division. There may be other division methods in actual implementation. For example, multiple modules or units can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of systems, modules and units can be electrical, mechanical or other forms.

[0180] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A mid-infrared laser carbon dioxide detection method for a fixed pollution source, characterized in that: The steps include: Acquire multiple concentration data sets, perform calculation and analysis on the concentration data sets, and output a slope threshold value based on the calculation and analysis results; Build gas analysis equipment, calibrate the gas analysis equipment, and output equipment completion information based on the calibration results; Based on the equipment completion information, the carbon dioxide concentration in the air at the fixed pollution source is monitored using the gas analysis equipment, and the detection concentration is output; the detection concentration is analyzed, and concentration prediction processing or change judgment processing is performed based on the analysis results; and operation judgment information is output based on the concentration prediction processing; Perform data calibration processing on the detection concentration or output device calibration information based on the change judgment processing result; Among the multiple concentration data groups, each concentration data group includes multiple historical concentration data; the historical concentration data includes normal historical concentration, abnormal historical concentration and acquisition time corresponding to the historical concentration data; The abnormal historical concentration is a carbon dioxide concentration greater than a concentration threshold value obtained during measurement; the normal historical concentration is a carbon dioxide concentration less than or equal to a concentration threshold value obtained during measurement; Acquire multiple concentration data sets, perform calculation and analysis on the concentration data sets, and output slope thresholds based on the calculation and analysis results, including: Acquire multiple concentration data sets, and for each concentration data set, establish a concentration scatter plot with the horizontal axis representing the acquisition time and the vertical axis representing the carbon dioxide concentration; Calculate the slope of two adjacent points in the concentration scatter plot and mark it as the change slope; Dividing the interval values ​​of the minimum change slope and the maximum change slope to obtain a first number of slope intervals; The changing slope in each slope interval is counted and marked as the interval slope number; Calculate the ratio of the number of slopes in each interval to the total number of changing slopes, and mark it as interval probability; Randomly select 100 change slopes, count the slope threshold of each interval in the randomly selected change slopes, and express it as a percentage, marked as the test probability; Calculate the ratio of the test probability to the interval probability, labeled as the probability ratio; Compare the probability ratio with the probability threshold. If the probability ratio is greater than or equal to the probability threshold, mark the corresponding slope interval as a reference interval; if the probability ratio is less than the probability threshold, mark the corresponding slope interval as an invalid interval. Mark the largest right endpoint of all reference intervals as the slope threshold.

2. The mid-infrared laser carbon dioxide detection method for a fixed pollution source according to claim 1 is characterized in that: Build gas analysis equipment and calibrate it. Output equipment completion information based on the calibration results, including: Building a gas analysis device, the gas analysis device comprising a light source, a measurement cavity and a detector; A gas sample with a known carbon dioxide concentration is placed in the measurement chamber, and the light source is controlled to emit laser light; The detector is used to receive the absorption signal, and the concentration of carbon dioxide in the measured gas sample is calculated and marked as the measured concentration; Adjust the optical path in the measurement chamber so that the measured concentration is equal to the carbon dioxide concentration of the gas sample, and output the device completion information.

3. The mid-infrared laser carbon dioxide detection method for a fixed pollution source according to claim 2 is characterized in that: Based on the information completed by the equipment, the concentration of carbon dioxide in the air at the fixed pollution source is monitored by using the gas analysis equipment, and the detection concentration is output; the detection concentration is analyzed, and concentration prediction processing or change judgment processing is performed based on the analysis results; Outputting operation judgment information based on concentration prediction processing; Based on the change judgment processing results, data calibration processing or output device calibration information of the detection concentration includes: Use gas analysis equipment to monitor fixed pollution sources, obtain the carbon dioxide concentration of the air at the fixed pollution source once every interval, mark it as the detection concentration; output the detection concentration and detection time; When a new detection concentration is obtained, the detection concentration is compared with the concentration threshold. If the detection concentration is less than the concentration threshold, a concentration prediction process is performed, and operation judgment information is output based on the concentration prediction process. If the detected concentration is greater than or equal to the concentration threshold, a change judgment process is performed; based on the change judgment process result, data calibration processing is performed on the detected concentration or device calibration information is output.

4. The mid-infrared laser carbon dioxide detection method for a fixed pollution source according to claim 3 is characterized in that: The operation judgment information includes concentration stability information and concentration warning information; The concentration prediction process comprises: Marking the detection time of the most recently acquired detection concentration as the second time; Obtaining a second number of detection concentrations whose detection time is closest to the second time; A scatter plot is established based on the detection concentration and the detection time, and a function fitting is performed on the data in the scatter plot to obtain a function with time as the independent variable and concentration as the dependent variable; The fitted function is marked as the concentration prediction function; Calculate the first time and the second time using the time calculation formula and output the predicted time; The time calculation formula is configured as: ; Where Ty is the prediction time, T1 is the first time, T2 is the second time, and k is a constant; Substitute the value of Ty into the concentration prediction function for calculation and output the predicted concentration; Compare the predicted concentration with the concentration threshold. If the predicted concentration is less than the concentration threshold, output concentration stability information; if the predicted concentration is greater than or equal to the concentration threshold, output concentration warning information.

5. The mid-infrared laser carbon dioxide detection method for a fixed pollution source according to claim 4, characterized in that: The change determination process includes: The most recently acquired detection concentration is marked as n1, and the detection time corresponding to n1 is marked as j1; Get the detection concentration and detection time closest to j1, marked as n2 and j2 respectively; Combine n1 and j1 to get coordinate point 1 (j1, n1); combine n2 and j2 to get coordinate point 2 (j2, n2); Use the two-point slope calculation formula to calculate coordinate point 1 and coordinate point 2, and output the analysis slope; Compare the analysis slope with the slope threshold. If the analysis slope is less than or equal to the slope threshold, output the concentration limit exceeding information. If the analysis slope is greater than the slope threshold, frequency conversion detection processing is performed, and data calibration processing is performed or device calibration information is output based on the frequency conversion detection processing result.

6. The mid-infrared laser carbon dioxide detection method for a fixed pollution source according to claim 5, characterized in that: The frequency conversion detection process includes: adjusting the acquisition interval of the gas analysis device from the first time to the third time; Continue to monitor the carbon dioxide concentration in the air at the fixed pollution source, and mark the third most recently detected carbon dioxide concentration as the analysis concentration; Compare each analytical concentration with the concentration threshold. If all analytical concentrations are less than the concentration threshold, perform data calibration on the detection concentration n1. If any of the analyzed concentrations is greater than the concentration threshold, the device calibration information is output.

7. The mid-infrared laser carbon dioxide detection method for a fixed pollution source according to claim 6, characterized in that: The data calibration process includes: Calculate the average of all analyzed concentrations and label it as the calibration concentration; Update the value of the detected concentration n1 to the value of the calibration concentration.

8. A mid-infrared laser carbon dioxide detection device for a fixed pollution source, applicable to a mid-infrared laser carbon dioxide detection method for a fixed pollution source as claimed in any one of claims 1 to 7, characterized in that: It includes analysis preparation module, equipment construction module and monitoring and analysis module; The analysis preparation module is used to obtain multiple concentration data groups, perform calculation analysis on the concentration data groups, and output a slope threshold value based on the calculation analysis results; The equipment construction module is used to build a gas analysis device, calibrate the gas analysis device, and output equipment completion information based on the calibration result; The monitoring and analysis module is used to monitor the carbon dioxide concentration of the air at the fixed pollution source using the gas analysis equipment based on the equipment completion information, and output the detected concentration; analyze the detected concentration, and perform concentration prediction processing or change judgment processing based on the analysis results; output operation judgment information based on the concentration prediction processing; Based on the change judgment processing result, data calibration processing is performed on the detection concentration or device calibration information is output.

Images