CN-121978246-A - Gas chromatography-based waste gas detection method and device

CN121978246ACN 121978246 ACN121978246 ACN 121978246ACN-121978246-A

Abstract

The invention discloses a gas chromatography-based waste gas detection method and a device, which relate to the technical field of waste gas detection and are characterized in that the difference between a current chromatography response signal and a reference signal is recorded and compared in real time in each detection process, and calculates the matching degree index, the method can effectively identify and compensate the phenomena of concentration jump and residual tailing caused by nonlinear adsorption and desorption in a chromatographic system. By means of reverse intervention operation, such as increasing the channel temperature and increasing the carrier gas flow rate to carry out fitting correction on signals, the method can eliminate the influence of historical residues, avoid misleading detection results and remarkably improve the accuracy and reliability of detection. The method effectively solves the problems of false alarm, false omission and false regulation and control decision-making caused by the chromatographic memory effect in the prior art, and ensures accurate monitoring of the concentration of pollutants and more reasonable regulation and control decision-making.

Inventors

LIN KAI
ZHAO MINHUI
Cao Jiangbing
SUN HAIBO
ZHANG JIANI
SONG LEI
HU BAOPING
Xiang Zhengchao

Assignees

浙江楚迪检测技术有限公司

Dates

Publication Date: 20260505
Application Date: 20260302

Claims (10)

1. The exhaust gas detection method based on gas chromatography is characterized by comprising the following steps of: injecting standard gas samples of all target pollutants, and recording chromatographic response signals of the target pollutants at different concentrations as reference chromatographic response signals; After each round of waste gas samples are injected into a gas chromatograph, recording a chromatographic response signal as a current chromatographic response signal; Calculating a matching degree index for reflecting residual risks according to the reference chromatographic response signal and the current chromatographic response signal; If the matching degree index is higher than a preset threshold, performing reverse intervention operation to carry out fitting correction on the chromatographic response signal, wherein the reverse intervention operation comprises the steps of increasing the channel temperature and increasing the carrier gas flow rate; Outputting the detection result of the current sample according to the corrected chromatographic response signal, and taking the detection result as the final detection output of the current sample.
2. The gas chromatography-based exhaust gas detection method according to claim 1, wherein the step of calculating a matching degree index reflecting a residual risk from the reference chromatography response signal and the current chromatography response signal is: According to the reference chromatographic response signal and the current chromatographic response signal, calculating a dynamic track deformation matching index and a signal complexity matching index, adding the dynamic track deformation matching index and the signal complexity matching index to obtain a residual risk index, and taking the residual risk index as a matching degree index for reflecting the residual risk.
3. The gas chromatography-based exhaust gas detection method according to claim 2, wherein the step of calculating the dynamic trajectory deformation matching index is: After each round of waste gas samples are injected into the gas chromatograph, recording the time-amplitude sequence of the current chromatograph response signal; For a time-amplitude sequence corresponding to the descending-phase signal, calculating the amplitude difference and the time difference between each time point and the previous time point, and dividing the amplitude difference by the time difference to obtain the local slope of each time point; Fitting the descending-stage signals by adopting a quadratic polynomial fitting method to obtain a fitted curve, and for each time point, obtaining a nonlinear factor of the signals at the corresponding time point by deviating the fitted curve corresponding to each time point from an actual signal; performing derivative calculation on the amplitude and time change of the descending-stage signal at each time point by using Jacobian transformation to obtain Jacobian transformation quantity at each time point; adding the local slope, the nonlinear factor and the Jacobian transformation metric of each time point to serve as deformation metrics of the corresponding time points, adding the deformation metrics of all the time points in the descending-stage signals to obtain deformation values of the current sample, and recording the deformation values as first deformation values; and calculating a deformation value of the reference chromatographic response signal as a second deformation value, and dividing the first deformation value by the second deformation value to obtain a dynamic track deformation matching index.
4. The gas chromatography-based exhaust gas detection method according to claim 2, wherein the step of calculating the signal complexity matching index is: taking a signal after an autonomous peak start point in the current chromatographic response signal as a descending-stage signal; For a time-amplitude sequence corresponding to a descending-stage signal, carrying out symbolization processing on signal values of continuous sampling points in a descending stage, and aiming at signal values of two adjacent sampling points, marking as an ascending mark if the value of a later sampling point is larger than that of a former sampling point, marking as a stable mark if the values of the two points are equal, marking as a descending mark if the value of the later point is smaller than that of the former point, so as to generate a group of change direction sequences only comprising the ascending, descending and stable marks; A plurality of continuous sliding subsequences are constructed in the sequence of the change direction by taking the fixed length as a unit to form a plurality of local change mode units with the same length; Multiplying the occurrence frequency of each mode by the logarithm of the occurrence frequency and then summing to obtain a distribution uncertainty value of each change mode; Taking the uncertainty value as a numerator, taking the logarithmic value of the number of the types of the local variation patterns actually appearing in the current sample as a denominator, and taking the division result as a complexity concentration value; And comparing the complexity concentration value of the current sample with the complexity concentration value recorded by the corresponding target pollutant in the reference behavior database, calculating the absolute value of the difference between the complexity concentration value and the complexity concentration value, and deducting the absolute value of the difference from the absolute value, wherein the obtained value is the signal complexity matching index.
5. The gas chromatography-based exhaust gas detection method according to claim 1, wherein if the matching degree index is higher than a preset threshold, the step of performing the reverse intervention operation to perform fitting correction on the chromatographic response signal comprises: comparing the residual risk index with a preset residual risk index threshold, and entering a reverse intervention mode if the residual risk index is not smaller than the preset residual risk index threshold; under the reverse intervention mode, automatically increasing the temperature of the chromatographic channel to a preset heating value, and increasing the carrier gas flow rate, wherein the increase range of the carrier gas flow rate is 1.2 to 2 times of the set value; After the reverse intervention operation is completed, fitting correction is performed on the chromatographic response signals.
6. An exhaust gas detection device based on gas chromatography, the device comprising: the reference module is used for injecting standard gas samples of all target pollutants and recording chromatographic response signals of the target pollutants at different concentrations as reference chromatographic response signals; The current module is used for recording a chromatographic response signal as a current chromatographic response signal after each round of waste gas samples are injected into the gas chromatograph; The calculating module is used for calculating a matching degree index for reflecting the residual risk according to the reference chromatographic response signal and the current chromatographic response signal; the interference module is used for executing reverse interference operation to carry out fitting correction on the chromatographic response signal if the matching degree index is higher than a preset threshold value, wherein the reverse interference operation comprises the steps of increasing the channel temperature and increasing the carrier gas flow rate; And the detection module outputs the detection result of the current sample according to the corrected chromatographic response signal and takes the detection result as the final detection output of the current sample.
7. The gas chromatography-based exhaust gas detection apparatus according to claim 6, wherein the calculation module comprises: And the residual risk module is used for calculating a dynamic track deformation matching index and a signal complexity matching index according to the reference chromatographic response signal and the current chromatographic response signal, adding the dynamic track deformation matching index and the signal complexity matching index to obtain a residual risk index, and taking the residual risk index as a matching degree index for reflecting the residual risk.
8. The gas chromatography-based exhaust gas detection apparatus of claim 7, wherein said residual risk module comprises: the acquisition module is used for recording the time-amplitude sequence of the current chromatographic response signal after each round of waste gas samples are injected into the gas chromatograph; The local slope module is used for taking a signal after the start point of an autonomous peak in the current chromatographic response signal as a descending-stage signal, calculating the amplitude difference and the time difference between each time point and the previous time point of the descending-stage signal for the time-amplitude sequence corresponding to the descending-stage signal, and dividing the amplitude difference by the time difference to obtain the local slope of each time point; the nonlinear module is used for fitting the descending-stage signals by adopting a quadratic polynomial fitting method to obtain a fitted curve, and for each time point, the deviation between the fitted curve corresponding to each time point and the actual signal is used for obtaining a nonlinear factor of the signal at the corresponding time point; The transformation quantity module is used for carrying out derivative calculation on the amplitude and time change of the descending-stage signal at each time point by using Jacobian transformation to obtain Jacobian transformation quantity at each time point; The first deformation value module is used for adding the local slope, the nonlinear factor and the Jacobian transformation metric of each time point to serve as deformation metrics of the corresponding time points, adding the deformation metrics of all the time points in the descending stage signals to obtain deformation values of the current sample, and recording the deformation values as first deformation values; and the dynamic track deformation matching module is used for calculating the deformation value of the reference chromatographic response signal as a second deformation value, and dividing the first deformation value by the second deformation value to obtain a dynamic track deformation matching index.
9. The gas chromatography-based exhaust gas detection apparatus of claim 7, wherein said residual risk module further comprises: the descending-stage signal module takes a signal after the start point of an autonomous peak in the current chromatographic response signal as a descending-stage signal; The change direction module is used for carrying out symbolization processing on signal values of continuous sampling points in a descending stage of a time-amplitude sequence corresponding to a descending stage signal, and marking ascending marks if the value of a later sampling point is larger than that of a former sampling point aiming at the signal values of two adjacent sampling points; The frequency module is used for constructing a plurality of continuous sliding subsequences in the change direction sequence by taking a fixed length as a unit to form a plurality of local change mode units with the same length; The uncertainty value module is used for multiplying the occurrence frequency of each mode by the logarithm of the occurrence frequency and then summing the obtained value to obtain a distribution uncertainty value of each change mode; the complexity concentration value module takes the uncertainty value as a numerator, takes the logarithmic value of the number of the types of the local variation modes actually appearing in the current sample as a denominator, and takes the division result as the complexity concentration value; And the signal complexity matching index module is used for comparing the complexity concentration value of the current sample with the complexity concentration value recorded in the reference behavior database of the corresponding target pollutant, calculating the absolute value of the difference between the complexity concentration value and the complexity concentration value, and subtracting the absolute value of the difference from the value 1 to obtain the value which is the signal complexity matching index.
10. The gas chromatography-based exhaust gas detection apparatus of claim 6, wherein said intervention module comprises: The comparison module is used for comparing the residual risk index with a preset residual risk index threshold value, and entering a reverse intervention mode if the residual risk index is not smaller than the preset residual risk index threshold value; The intervention operation module is used for automatically increasing the temperature of the chromatographic channel to a preset heating value in a reverse intervention mode, and increasing the flow rate of the carrier gas, wherein the increasing range of the flow rate of the carrier gas is 1.2 to 2 times of a set value; and the correction module is used for carrying out fitting correction on the chromatographic response signals after the reverse intervention operation is completed.

Description

Gas chromatography-based waste gas detection method and device Technical Field The invention relates to the technical field of waste gas detection, in particular to a gas chromatography-based waste gas detection method and device. Background In environmental monitoring and industrial emission control, gas chromatography-based exhaust gas detection methods have become a central means of identifying and quantifying pollutants such as Volatile Organic Compounds (VOCs). The method generally comprises the steps of collecting an exhaust gas sample, injecting the exhaust gas sample into a gas chromatograph after passing through a pretreatment module (such as filtration, drying and enrichment), taking the sample into a chromatographic column by using carrier gas to realize component separation, and finally outputting corresponding qualitative and quantitative analysis results through devices such as a Flame Ionization Detector (FID), a Thermal Conductivity Detector (TCD) and the like. The technology is widely applied to multiple fields of fixed pollution source emission, indoor air quality assessment, emergency response and the like due to high selectivity, high sensitivity and good linear response, and has remarkable advantages in monitoring accuracy and method stability. However, in the long-term practical application process, the existing exhaust gas detection method based on gas chromatography has a problem that the existing exhaust gas detection method is difficult to detect and affects far in the face of certain polar organic components (such as aldehydes, phenols and the like), and the existing exhaust gas detection method is likely to memorize the previous pollution state and continuously output misleading detection results even if the concentration of the target component in the actual sample is changed due to the fact that the substances are easy to be subjected to nonlinear adsorption and slow desorption in the inner wall of a sampling pipeline or a chromatographic system. The problem called chromatographic memory effect not only seriously disturbs the real judgment of pollution fluctuation, but also can cause false alarm, missing report or error regulation decision, and an effective recognition and compensation mechanism needs to be provided for solving. Disclosure of Invention The invention aims to solve the problems that when the existing gas chromatography-based waste gas detection method in the background technology is used for treating polar organic components, concentration jump or residual tailing is easy to cause due to nonlinear adsorption and slow desorption on the inner wall of a system, so that misleading detection results are caused, thereby disturbing the real judgment of pollution fluctuation and possibly causing misinformation, missing report or wrong decision. In a first aspect of the present invention, there is provided a gas chromatography-based exhaust gas detection method, the method comprising: S1, injecting standard gas samples of target pollutants into a gas chromatograph, and recording chromatographic response signals of the target pollutants at different concentrations as reference chromatographic response signals; S2, after each round of waste gas samples are injected into the gas chromatograph, recording a chromatographic response signal as a current chromatographic response signal; S3, calculating a matching degree index for reflecting residual risks according to the reference chromatographic response signal and the current chromatographic response signal; S4, if the matching degree index is higher than a preset threshold, performing reverse intervention operation to carry out fitting correction on the chromatographic response signal, wherein the reverse intervention operation comprises the steps of increasing the channel temperature and increasing the carrier gas flow rate; S5, outputting a detection result of the current sample according to the corrected chromatographic response signal, and taking the detection result as a final detection output of the current sample. Optionally, the step of calculating the matching degree index for reflecting the residual risk according to the reference chromatographic response signal and the current chromatographic response signal is: According to the reference chromatographic response signal and the current chromatographic response signal, calculating a dynamic track deformation matching index and a signal complexity matching index, adding the dynamic track deformation matching index and the signal complexity matching index to obtain a residual risk index, and taking the residual risk index as a matching degree index for reflecting the residual risk. Optionally, the calculating step of the dynamic track deformation matching index is as follows: After each round of waste gas samples are injected into the gas chromatograph, recording the time-amplitude sequence of the current chromatographic response signal; For a time-amplitude sequence