CN115639168B - Gas detection method, system and medium for gas analyzer - Google Patents
Gas detection method, system and medium for gas analyzer Download PDFInfo
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Abstract
The invention relates to a gas detection method, a system and a medium of a gas analyzer, wherein the gas detection method comprises the following steps: collecting the absorbance spectrum of each target gas with preset range point concentration, and also respectively collecting the absorbance spectrum of water vapor with different standard concentrations; selecting a target absorption peak according to the absorbance spectrum of the target gas to determine a target wave band corresponding to the target absorption peak; detecting the gas sample to be detected to obtain an absorbance spectrum of the gas sample to be detected; matching the absorbance spectrum of the gas sample to be detected with the absorbance spectra of water vapor with different standard concentrations to obtain the absorbance spectrum of the water vapor in the gas sample to be detected; and in a target wave band corresponding to the target gas to be detected, calculating the concentration of the target gas to be detected according to the preset measuring range point concentration of the target gas, the absorbance spectrum of the gas sample to be detected, the absorbance spectrum of water vapor in the gas sample to be detected and the influence of the rest gas to be detected in the gas sample to be detected on the target gas to be detected. The invention effectively improves the detection precision of the gas concentration.
Description
Technical Field
The invention belongs to the technical field of gas analysis and detection, and particularly relates to a gas detection method and system of a gas analyzer and a readable medium.
Background
The Fourier transform infrared spectrum technology is a comprehensive detection technology which is rapidly developed in recent years. As most trace and trace gases in the atmosphere are infrared active gases, the gas has the capability of absorbing and emitting infrared characteristic spectrum in the wave band range of 2-30 mu m, and the wave band is called as a fingerprint wave band in a middle infrared region, so that the gas is very favorable for spectral measurement.
Fourier transform infrared spectroscopy (FTIR) technology has been the dominant means of infrared spectroscopy since the 80 s. FTIR spectroscopy is a method which utilizes the principle of beam-splitting interference, combines a Michelson interferometer, a modulation technology and a computer technology, realizes the reduction from an interference pattern to a spectrum by a Fourier transform method, and then inverts the concentration of a gas to be measured according to the obtained spectroscopy. The technology has wide application prospect in air pollutant monitoring, such as a Fourier infrared gas analyzer.
The spectrum inversion algorithm has direct influence on the accuracy of the measurement result, and the conventional Fourier infrared gas analyzer adopting the traditional spectrum inversion algorithm is difficult to eliminate the influence of nonlinear absorption, so that the measurement result has large error in a detection environment with high humidity. In addition, the influence of mutual interference between gases is not considered.
Disclosure of Invention
Based on the above-mentioned shortcomings and drawbacks of the prior art, it is an object of the present invention to at least solve one or more of the above-mentioned problems of the prior art, in other words, to provide a gas detection method, system and medium for a gas analyzer that meets one or more of the above-mentioned needs.
In order to achieve the purpose, the invention adopts the following technical scheme:
the gas detection method of the gas analyzer comprises the following steps:
s1, respectively collecting absorbance spectrums of target gases with preset range point concentrations and also respectively collecting absorbance spectrums of water vapor with different standard concentrations;
s2, selecting a target absorption peak according to the absorbance spectrum of the target gas to determine a target wave band corresponding to the target absorption peak;
s3, detecting the gas sample to be detected to obtain an absorbance spectrum of the gas sample to be detected;
s4, matching the absorbance spectrum of the gas sample to be detected with the absorbance spectra of water vapor with different standard concentrations to obtain the absorbance spectrum of the water vapor in the gas sample to be detected;
and S5, in a target wave band corresponding to the target gas to be detected in the gas sample to be detected, calculating the concentration of the target gas to be detected according to the preset measuring range point concentration of the target gas, the absorbance spectrum of the gas sample to be detected, the absorbance spectrum of water vapor in the gas sample to be detected and the influence of other gas to be detected in the gas sample to be detected on the target gas to be detected.
Preferably, in the step S1, the target gas is selected from the group consisting ofmIn the method for preparing the seed coating,mis a positive integer;
the type of the target gas is determined according to the type of the gas to be measured in the gas sample to be measured.
Preferably, in step S1, the standard concentration of water vapor is in the interval of [0%,n%]the selection is carried out between the two groups,nand determining according to the maximum water vapor concentration in the gas sample to be detected.
Preferably, in the step S2, the second steplThe target band corresponding to the target gas isP l :Q l ，P l Is the starting position of the target band of wavelengths,Q l is the end position of the target band of wavelengths,l∈[1，m]。
preferably, the step S4 includes the following steps:
s41, selecting a target water vapor wave band only having water vapor absorption according to the absorbance spectrum of each target gas and the absorbance spectra of water vapor with different standard concentrations;
s42, respectively subtracting the spectral section of the target water vapor wave band corresponding to the absorbance spectrum of the gas sample to be detected from the spectral section of the target water vapor wave band corresponding to the absorbance spectrum of the water vapor with the standard concentration, and obtaining the target standard concentration with the minimum absolute value of the difference;
s43, obtaining a correction factor according to the spectral band corresponding to the target water vapor wave band on the absorbance spectrum of the gas sample to be detected and the spectral band corresponding to the target water vapor wave band on the absorbance spectrum of the water vapor with the target standard concentrationd：
Wherein the content of the first and second substances,
the target water vapor wave band is set,P 0 is the starting position of the target water vapor wave band,Q 0 is the termination position of the target water vapor wave band;gis the target standard concentration; min is a minimum calculation operator; />
The spectrum section corresponding to the target water vapor wave band on the absorbance spectrum of the gas sample to be detected; />
The spectrum section corresponding to the target water vapor wave band on the absorbance spectrum of the water vapor with the target standard concentration;
s44, correcting the absorbance spectrum of the water vapor with the target standard concentration according to the correction factor to obtain the absorbance spectrum of the water vapor in the gas sample to be measured.
Preferably, the step S4 further includes the following steps:
and S45, multiplying the correction factor by the target standard concentration to obtain the water vapor concentration in the gas sample to be detected.
Preferably, the step S5 includes the following steps:
s51, calculating a difference value or a ratio of a target absorption peak value of the absorbance spectrum of the target gas in the target waveband and the sum of the target absorption peak values of the absorbance spectra of the rest target gases serving as interferences;
s52, sorting according to the difference value or the ratio from big to small from the 1 st bit to the 1 st bitmA bit;
and S53, sequentially calculating the concentration of each target gas to be detected in the gas sample to be detected according to the sequence to obtain the concentration of each target gas to be detected.
Preferably, in the step S53, the first stepiThe gas to be tested of the target is correspondingly sequencediTarget gas of concentrationC i =k ii *C i0 ；
Wherein the content of the first and second substances,i∈[1，m]，C i0 to sequence toiA preset range point concentration of the target gas;k ii is as followsiA correction factor;
The present invention also provides a gas detection system of a gas analyzer, which applies the gas detection method according to any one of the above aspects, the gas detection system comprising:
the acquisition module is used for respectively acquiring the absorbance spectra of each target gas with the preset range point concentration and also respectively acquiring the absorbance spectra of water vapor with different standard concentrations;
the selecting module is used for selecting a target absorption peak according to the absorbance spectrum of the target gas so as to determine a target wave band corresponding to the target absorption peak;
the detection module is used for detecting the gas sample to be detected to obtain an absorbance spectrum of the gas sample to be detected;
the matching module is used for matching the absorbance spectrum of the gas sample to be detected with the absorbance spectra of water vapor with different standard concentrations to obtain the absorbance spectrum of the water vapor in the gas sample to be detected;
and the calculation module is used for calculating the concentration of the target gas to be detected according to the preset measuring range point concentration of the target gas, the absorbance spectrum of the gas sample to be detected, the absorbance spectrum of water vapor in the gas sample to be detected and the influence of other gas to be detected in the gas sample to be detected on the target gas to be detected in a target wave band corresponding to the target gas to be detected.
The present invention also provides a medium having stored therein instructions which, when run on a computer, cause the computer to perform a gas detection method as described in any one of the above aspects.
Compared with the prior art, the invention has the beneficial effects that:
the invention comprehensively considers the interference of water vapor and the interference between gases, eliminates the influence of nonlinear absorption and gas interference and effectively improves the precision of gas concentration detection.
Drawings
Fig. 1 is a flowchart of a gas detection method of a fourier infrared gas analyzer according to embodiment 1 of the present invention;
FIG. 2 is a spectrum of absorbance spectra for water vapor of various standard concentrations for example 1 of the present invention;
FIG. 3 is CH in example 1 of the present invention 4 And an absorbance spectrum of HCl as a target gas;
fig. 4 is a block diagram of a gas detection system of a fourier infrared gas analyzer according to embodiment 1 of the present invention.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention, the following description will explain specific embodiments of the present invention with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the invention, and that for a person skilled in the art, other drawings and embodiments can be derived from them without inventive effort.
Example 1:
the gas analyzer of the present embodiment will be described in detail by taking a fourier infrared gas analyzer as an example.
As shown in fig. 1, the gas detection method of the fourier infrared gas analyzer of the present embodiment includes the following steps:
s1, respectively collecting absorbance spectrums of target gases with preset range point concentrations
And respectively collecting the absorbance spectrums of water vapor with different standard concentrations>
。
Specifically, the kind of the target gas is determined according to the kind of the gas to be measured in the gas sample to be measured. Wherein, the kind of the target gas of the embodiment ismThe seed is used as an example of the method,mis a positive integer;
is as followslThe absorbance spectrum of the seed target gas,l∈[1，m]；
is at a standard concentration ofsThe absorbance spectrum of water vapor of (1).
In addition, the nonlinear effect of the water vapor spectrum is obvious, so that water vapor spectra with different concentrations are collected in advance. Standard concentration of water vaporsIn the interval 0%,n%]betweenSelecting the raw materials of the raw materials,nand determining according to the maximum water vapor concentration in the gas sample to be detected. For example, a standard concentration is chosen at every 1% to give absorbance spectra for 1%, 2%, 3%, 4%, 5% water vapor, as shown in FIG. 2. The water vapor with different standard concentrations can be obtained by mixing nitrogen and water vapor in different volume ratios.
S2, selecting a target absorption peak according to the absorbance spectrum of the target gas to determine a target wave band corresponding to the target absorption peak.
Specifically, the firstlThe target band corresponding to the target gas isP l :Q l ，P l Is the starting position of the target band of wavelengths,Q l is the end position of the target band.
And S3, detecting the gas sample to be detected to obtain an absorbance spectrum of the gas sample to be detected.
Specifically, a gas sample to be detected is detected by a Fourier infrared gas analyzer to obtain an absorbance spectrum of the gas sample to be detected
。
And S4, matching the absorbance spectrum of the gas sample to be detected with the absorbance spectra of water vapor with different standard concentrations to obtain the absorbance spectrum of the water vapor in the gas sample to be detected.
The step S4 specifically includes the following steps:
s41, selecting a target water vapor wave band only having water vapor absorption according to the absorbance spectrum of each target gas and the absorbance spectra of water vapor with different standard concentrations;
because the absorption of vapor is comparatively extensive, can select suitable spectrum wave band as target vapor wave band, there is the absorption of vapor in this wave band, and the gas that awaits measuring does not have the absorption. For example, the target water vapor waveband is 3200cm -1 ～3400cm -1 The determination can be specifically carried out according to the actual application condition.
S42, respectively subtracting the spectral section of the target water vapor wave band corresponding to the absorbance spectrum of the gas sample to be detected from the spectral section of the target water vapor wave band corresponding to the absorbance spectrum of the water vapor with the standard concentration, and obtaining the target standard concentration with the minimum absolute value of the difference;
wherein the content of the first and second substances,
is a target water vapor wave band and is,P 0 is the starting position of the target water vapor wave band,Q 0 is the termination position of the target water vapor wave band; />
Is the corresponding target water vapor wave band on the absorbance spectrum of the gas sample to be detected>
The spectral range of (a); />
The absorbance spectrum of the water vapor with the target standard concentration corresponds to the target water vapor wave band->
The spectral range of (a).
Selecting
Obtaining the corresponding of the minimum valuesAs the target standard concentrationg。
S43, obtaining a correction factor according to the spectral band corresponding to the target water vapor wave band on the absorbance spectrum of the gas sample to be detected and the spectral band corresponding to the target water vapor wave band on the absorbance spectrum of the water vapor with the target standard concentrationd：
Wherein min is a minimum calculation operator;
s44, correcting the absorbance spectrum of the water vapor with the target standard concentration according to the correction factor to obtain the absorbance spectrum of the water vapor in the gas sample to be measured
。
S45, multiplying the correction factor by the target standard concentration to obtain the water vapor concentration in the gas sample to be measuredd*g。
And S5, in a target wave band corresponding to the target gas to be detected in the gas sample to be detected, calculating the concentration of the target gas to be detected according to the preset measuring range point concentration of the target gas, the absorbance spectrum of the gas sample to be detected, the absorbance spectrum of water vapor in the gas sample to be detected and the influence of other gas to be detected in the gas sample to be detected on the target gas to be detected.
The step S5 specifically includes the following steps:
s51, calculating the difference value between the target absorption peak value of the absorbance spectrum of the target gas in the target waveband and the sum of the target absorption peak values of the absorbance spectra of the rest target gases serving as interference;
s52, sorting according to the difference value from large to small from the 1 st bit to the first bitmA bit; each corresponding to a target gas;
and S53, sequentially calculating the concentration of each target gas to be detected in the gas sample to be detected according to the sequence to obtain the concentration of each target gas to be detected.
The concentration of the gas to be measured is calculated according to the sequence, and the design is that the signal-to-noise ratio is highest and the interference influence is minimal; if the concentration calculation of the gas to be measured is carried out at random, the random noise is large, so that the concentration measurement value of the gas to be measured is unstable.
Specifically, the firstiThe gas to be tested of the target is correspondingly sequencediTarget gas of concentrationC i =k ii *C i0 ；
Wherein the content of the first and second substances,i∈[1，m]，C i0 to sequence toiTarget gas of siteThe preset range point concentration of (2);k ii is as followsiA correction factor;
wherein the content of the first and second substances,
to sequence toiThe target wave band corresponding to the target gas in position->
Is the corresponding target wave band on the absorbance spectrum of the gas sample to be detected>
The spectral range of (a); />
In the absorbance spectrum of water vapour of a target standard concentration corresponding to the target wavelength band>
The spectral range of (a);k ij to sequence tojTarget gas pair of siteiA correction factor for the target gas to be examined>
To sequence tojThe absorbance spectrum of the target gas corresponds to the target wave band
The spectral range of (a).
The following describes the calculation of the concentration of each gas to be measured in detail, specifically as follows:
(1) The 1 st target gas to be measured is the 1 st ordered target gas with the concentrationC 1 =k 11 *C 01 ；
Wherein, the first and the second end of the pipe are connected with each other,C 01 the concentration of the preset range point of the 1 st-order target gas is sequenced;k 11 is a first correction factor;
wherein the content of the first and second substances,
for sorting the target wave band corresponding to the target gas in position 1, < > H>
Is the corresponding target wave band on the absorbance spectrum of the gas sample to be detected>
The spectral range of (a); />
The absorbance spectrum of the water vapour at the target standard concentration corresponds to the target wave band->
The spectral range of (a);k j1 to order the firstjCorrection factor for the first target gas to be examined for a potential target gas, based on the measured value of the target gas>
To sequence tojThe absorbance spectrum of the target gas corresponds to the target band
The spectral range of (a).
(2) The 2 nd gas to be measured is the 2 nd gas with the concentrationC 2 =k 22 *C 02 ；
Wherein the content of the first and second substances,C 02 the concentration of the preset range point of the 2 nd-order target gas is sequenced;k 22 is a second correction factor;
wherein, the first and the second end of the pipe are connected with each other,
for the target wave band corresponding to the target gas in order of position 2, < > H>
Is the corresponding target wave band on the absorbance spectrum of the gas sample to be detected>
The spectral range of (a); />
The absorbance spectrum of the water vapour at the target standard concentration corresponds to the target wave band->
The spectral range of (a);k j2 to order the firstjCorrection factors of the target gas to the second target gas to be measured; />
The absorbance spectrum of the target gas which is sorted in position 1 corresponds to the target wavelength band->
The spectral range of (a); />
To sequence tojThe absorbance spectrum of the target gas corresponds to the target wave band
The spectral range of (a).
By analogy, untilFirst, themCalculating the concentration of the target gas to be measuredmThe target gas to be measured is the first to be sequencedmTarget gas of concentrationC m =k mm *C m0 ；
Wherein the content of the first and second substances,C m0 to sequence tomA preset range point concentration of the target gas;k mm is as followsmA correction factor;
by way of illustration, as shown in FIG. 3, HCl and CH 4 Absorbance spectra, CH, of two different target gases 4 Gas at 4100cm -1 The absorption peak is very high near the position, and the difference of the absorbance peak value is about 0.18 compared with that of the interfering gas HCl. If the two gases are reordered, CH 4 Is a first gas and HCl is a second gas. Is CH 4 4080-4300cm can be selected when gas is selected from target waveband -1 I.e. P 1 =4080cm -1 ，Q 1 =4300cm -1 (ii) a The wavelength band of HCl gas can be 3700-3900cm -1 I.e. P 2 =3700，Q 2 =3900cm -1 。
The interference of steam and the interference between the gas are comprehensively considered in the embodiment, and the accuracy of gas detection is effectively improved.
As can be seen from tables 1 and 2, the gas concentration measurement values obtained by the gas detection method of the present embodiment and the conventional PLS algorithm (i.e., partial least squares) are analyzed in comparison, and the gas concentration measurement values obtained by the gas detection method of the present embodiment have higher accuracy.
TABLE 1 measurements obtained by the conventional PLS algorithm
TABLE 2 measured values obtained by the gas detection method of this example
Based on the gas detection method of the fourier infrared gas analyzer in this embodiment, as shown in fig. 4, the present embodiment further provides a gas detection system of the fourier infrared gas analyzer, which includes an acquisition module, a selection module, a detection module, a matching module, and a calculation module.
Specifically, the collecting module of this embodiment is used to collect the absorbance spectra of each target gas with a preset range point concentration respectively
And respectively collecting the absorbance spectrums of water vapor with different standard concentrations>
。
Specifically, the kind of the target gas is determined according to the kind of the gas to be measured in the gas sample to be measured. Wherein, the kind of the target gas of the present embodiment ismThe seed is used as an example of the method,mis a positive integer;
is as followslThe absorbance spectrum of the seed target gas,l∈[1，m]；
is at a standard concentration ofsThe absorbance spectrum of water vapor.
In addition, the nonlinear effect of the water vapor spectrum is obvious, so that water vapor spectra with different concentrations are collected in advance. Standard concentration of water vaporsIn the interval 0%,n%]the method comprises the following steps of (1) selecting,nand determining according to the maximum water vapor concentration in the gas sample to be detected. For example, a standard concentration is chosen at every 1% to give absorbance spectra for 1%, 2%, 3%, 4%, 5% water vapor, as shown in FIG. 2. The water vapor with different standard concentrations can be obtained by mixing nitrogen and water vapor in different volume ratios.
The selecting module of this embodiment is configured to select a target absorption peak according to an absorbance spectrum of a target gas to determine a target band corresponding to the target absorption peak. Specifically, the firstlThe target band corresponding to the target gas isP l :Q l ，P l Is the starting position of the target band of wavelengths,Q l is the end position of the target band.
The detection module of this embodiment is used for detecting the gas sample that awaits measuring in order to obtain the absorbance spectrum of the gas sample that awaits measuring. Specifically, a gas sample to be detected is detected by a Fourier infrared gas analyzer to obtain an absorbance spectrum of the gas sample to be detected
。
The matching module of the embodiment is used for matching the absorbance spectrum of the gas sample to be detected with the absorbance spectra of water vapor with different standard concentrations to obtain the absorbance spectrum of the water vapor in the gas sample to be detected.
Specifically, the matching process of the present embodiment includes the following processes:
1. selecting a target water vapor wave band only having water vapor absorption according to the absorbance spectrum of each target gas and the absorbance spectra of water vapor with different standard concentrations;
because the absorption of vapor is comparatively extensive, can select suitable spectrum wave band as target vapor wave band, there is the absorption of vapor in this wave band, and the gas that awaits measuring does not have the absorption. For example, the target water vapor waveband is 3200cm -1 ～3400cm -1 The determination can be specifically carried out according to the actual application condition.
2. Respectively subtracting the spectral band corresponding to the target water vapor wave band on the absorbance spectrum of the gas sample to be detected from the spectral band corresponding to the target water vapor wave band on the absorbance spectrum of the water vapor with the standard concentration, and obtaining the target standard concentration with the minimum absolute value of the difference value;
wherein the content of the first and second substances,
the target water vapor wave band is set,P 0 is the starting position of the target water vapor wave band,Q 0 is the termination position of the target water vapor wave band; />
Is the corresponding target water vapor wave band on the absorbance spectrum of the gas sample to be detected>
The spectral range of (a); />
On the absorbance spectrum of moisture which is of a target standard concentration corresponds to a target moisture band>
The spectral range of (a).
Selecting
Obtaining the corresponding of the minimum valuesAs the target standard concentrationg。
3. Obtaining a correction factor according to the spectral band corresponding to the target water vapor wave band on the absorbance spectrum of the gas sample to be detected and the spectral band corresponding to the target water vapor wave band on the absorbance spectrum of the water vapor with the target standard concentrationd：
Wherein min is a minimum calculation operator;
4. correcting the absorbance spectrum of the water vapor with the target standard concentration according to the correction factor to obtain the absorbance spectrum of the water vapor in the gas sample to be measured
。
5. The water vapor concentration in the gas sample to be measured is obtained by multiplying the correction factor by the target standard concentrationd*g。
The calculation module of this embodiment is used for in the target wave band that the target gas that awaits measuring in the gas sample that awaits measuring corresponds, according to the preset range point concentration of target gas, the absorbance spectrum of the gas sample that awaits measuring, the absorbance spectrum of the steam in the gas sample that awaits measuring and the influence of the gas that awaits measuring of other gases that await measuring in the gas sample that awaits measuring to the target gas that awaits measuring.
Specifically, the calculation of the concentration of the target gas to be measured of the present embodiment includes the following processes:
1. calculating the difference value between the target absorption peak value of the absorbance spectrum of the target gas in the target waveband and the sum of the target absorption peak values of the absorbance spectra of the rest target gases serving as interferences;
2. sorting according to the difference from large to small from the 1 st bit to the 1 st bitmA bit; each corresponding to a target gas;
3. and sequentially calculating the concentration of each target gas to be detected in the gas sample to be detected according to the sequence to obtain the concentration of each target gas to be detected. The concentration of the gas to be detected is calculated in sequence according to the sequence, and the design is that the signal-to-noise ratio is highest and the interference influence is minimum; if the concentration calculation of the gas to be measured is carried out at random, the random noise is large, so that the concentration measurement value of the gas to be measured is unstable.
Specifically, the firstiThe gas to be tested of the target is correspondingly sequencediTarget gas of concentrationC i =k ii *C i0 ；
Wherein, the first and the second end of the pipe are connected with each other,i∈[1，m]，C i0 to sequence toiA preset range point concentration of the target gas;k ii is as followsiA correction factor;
wherein the content of the first and second substances,
to sequence toiThe target wave band corresponding to the target gas in position->
Is the corresponding target wave band on the absorbance spectrum of the gas sample to be detected>
The spectral range of (a); />
In the absorbance spectrum of water vapour of a target standard concentration corresponding to the target wavelength band>
The spectral range of (a);k ij to sequence tojTarget gas pair of siteiA correction factor for the target gas to be examined>
To sequence tojThe absorbance spectrum of the target gas corresponds to the target wave band
The spectral range of (a).
The following details are provided for the calculation of the concentration of each gas to be measured, specifically as follows:
(I) The 1 st target gas to be measured is the 1 st ordered target gas with the concentrationC 1 =k 11 *C 01 ；
Wherein the content of the first and second substances,C 01 the concentration of the preset range point of the target gas of the 1 st position is sequenced;k 11 is a first correction factor;
wherein the content of the first and second substances,
for sorting the target wave band corresponding to the target gas in position 1, < > H>
Is the corresponding target wave band on the absorbance spectrum of the gas sample to be detected>
The spectral range of (a); />
The absorbance spectrum of the water vapour at the target standard concentration corresponds to the target wave band->
The spectral range of (a);k j1 to sequence tojCorrection factor for the first target gas to be examined for a potential target gas, based on the measured value of the target gas>
To sequence tojThe absorbance spectrum of the target gas corresponds to the target wave band
The spectral range of (a).
(II) the 2 nd target gas to be measured is the 2 nd-ranked target gas, the concentration of whichC 2 =k 22 *C 02 ；
Wherein the content of the first and second substances,C 02 the concentration of the preset range point of the 2 nd-order target gas is sequenced;k 22 is a second correction factor;
wherein，
In order to rank the target wave band corresponding to the target gas in position 2>
Is the corresponding target wave band on the absorbance spectrum of the gas sample to be detected>
The spectral range of (a); />
The absorbance spectrum of the water vapour at the target standard concentration corresponds to the target wave band->
The spectral range of (a);k j2 to sequence tojCorrection factors of the target gas to the second target gas to be detected; />
The absorbance spectrum of the target gas which is sorted in position 1 corresponds to the target wavelength band->
The spectral range of (a); />
To sequence tojThe absorbance spectrum of the target gas corresponds to the target wave band
The spectral range of (a).
And so on until the firstmConcentration calculation of the target gas to be measuredmThe target gas to be measured is the first to be sequencedmTarget gas of concentrationC m =k mm *C m0 ；
Wherein the content of the first and second substances,C m0 to order the firstmA preset range point concentration of the target gas;k mm is a firstmA correction factor;
by way of illustration, as shown in FIG. 3, HCl and CH 4 Absorbance spectra, CH, of two different target gases 4 Gas at 4100cm -1 The absorption peak is very high near the position, and the difference of the absorbance peak value is about 0.18 compared with that of the interfering gas HCl. If the two gases are reordered, CH 4 Is a first gas and HCl is a second gas. Is CH 4 4080-4300cm can be selected when gas is selected from target waveband -1 I.e. P 1 =4080cm -1 ，Q 1 =4300cm -1 (ii) a The wavelength band of HCl gas can be 3700-3900cm -1 I.e. P 2 =3700，Q 2 =3900cm -1 。
The interference of steam and the interference between the gas are comprehensively considered in the embodiment, and the accuracy of gas detection is effectively improved.
The present embodiment also provides a readable medium, in which instructions are stored, and when the instructions are executed on a computer, the instructions cause the computer to execute the gas detection method of the present embodiment, so as to implement intelligent detection of the gas concentration.
Example 2:
the gas detection method of the fourier infrared gas analyzer of the present example is different from that of example 1 in that:
in step S51 in embodiment 1, the difference between the target absorption peak value of the absorbance spectrum of the target gas in the calculated target wavelength band and the target absorption peak value sum of the absorbance spectra of the remaining target gases as interferences is replaced with the ratio between the target absorption peak value of the absorbance spectrum of the target gas in the calculated target wavelength band and the target absorption peak value sum of the absorbance spectra of the remaining target gases as interferences, and the calculation is performed in the subsequent step S52 in descending order according to the ratio; the requirements of different applications are met;
the other steps are the same as in example 1.
Correspondingly, the gas detection system of the fourier infrared gas analyzer of the present embodiment is different from that of embodiment 1 in that:
the difference value of the target absorption peak value of the absorbance spectrum of the target gas in the target waveband and the sum of the target absorption peak values of the absorbance spectra of the rest target gases serving as interferences in the calculation module is replaced by the ratio of the target absorption peak value of the absorbance spectrum of the target gas in the target waveband and the sum of the target absorption peak values of the absorbance spectra of the rest target gases serving as interferences, and then the target absorption peak values are sorted from large to small according to the ratio; the requirements of different applications are met;
the other structures are the same as those of embodiment 1.
The present embodiment also provides a readable medium, in which instructions are stored, and when the instructions are executed on a computer, the instructions cause the computer to execute the gas detection method of the present embodiment, so as to implement intelligent detection of the gas concentration.
The foregoing has outlined, rather broadly, the preferred embodiment and principles of the present invention in order that those skilled in the art may better understand the detailed description of the invention without departing from its broader aspects.
Claims (6)
1. The gas detection method of the gas analyzer is characterized by comprising the following steps of:
s1, respectively collecting absorbance spectrums of target gases with preset range point concentrations and also respectively collecting absorbance spectrums of water vapor with different standard concentrations; wherein the target gas is of the typemIn the method for preparing the seed coating,mis a positive integer; the type of the target gas is determined according to the type of the gas to be detected in the gas sample to be detected;
s2, selecting a target absorption peak according to the absorbance spectrum of the target gas to determine a target wave band corresponding to the target absorption peak;
s3, detecting the gas sample to be detected to obtain an absorbance spectrum of the gas sample to be detected;
s4, matching the absorbance spectrum of the gas sample to be detected with the absorbance spectra of water vapor with different standard concentrations to obtain the absorbance spectrum of the water vapor in the gas sample to be detected;
the step S4 includes the steps of:
s41, selecting a target water vapor wave band only having water vapor absorption according to the absorbance spectrum of each target gas and the absorbance spectra of water vapor with different standard concentrations;
s42, respectively subtracting the spectral section of the target water vapor wave band corresponding to the absorbance spectrum of the gas sample to be detected from the spectral section of the target water vapor wave band corresponding to the absorbance spectrum of the water vapor with the standard concentration, and obtaining the target standard concentration with the minimum absolute value of the difference;
s43, obtaining a correction factor according to the spectral band corresponding to the target water vapor wave band on the absorbance spectrum of the gas sample to be detected and the spectral band corresponding to the target water vapor wave band on the absorbance spectrum of the water vapor with the target standard concentrationd：
Wherein the content of the first and second substances,
the target water vapor wave band is set,P 0 is the starting position of the target water vapor wave band,Q 0 is the termination position of the target water vapor wave band;gis a target standard concentration; min is a minimum calculation operator; />
The spectrum section corresponding to the target water vapor wave band on the absorbance spectrum of the gas sample to be detected; />
The spectrum section corresponding to the target water vapor wave band on the absorbance spectrum of the water vapor with the target standard concentration;
s44, correcting the absorbance spectrum of the water vapor with the target standard concentration according to the correction factor to obtain the absorbance spectrum of the water vapor in the gas sample to be measured;
s5, in a target wave band corresponding to target gas to be detected in the gas sample to be detected, calculating the concentration of the target gas to be detected according to the preset measuring range point concentration of the target gas, the absorbance spectrum of the gas sample to be detected, the absorbance spectrum of water vapor in the gas sample to be detected and the influence of other gas to be detected in the gas sample to be detected on the target gas to be detected;
the step S5 includes the steps of:
s51, calculating a difference value or a ratio of a target absorption peak value of the absorbance spectrum of the target gas in the target waveband and the sum of the target absorption peak values of the absorbance spectra of the rest target gases serving as interferences;
s52, sorting according to the difference value or the ratio from big to small from the 1 st bit to the 1 st bitmA bit;
s53, sequentially calculating the concentration of each target gas to be detected in the gas sample to be detected according to the sequence to obtain the concentration of each target gas to be detected;
in the step S53, theiThe target gas to be measured is correspondingly sequencediTarget gas of concentrationC i =k ii *C i0 ；
Wherein the content of the first and second substances,i∈[1，m]，C i0 to sequence toiA preset range point concentration of the target gas;k ii is as followsiA correction factor;
2. The gas detection method according to claim 1, wherein in step S1, the standard concentration of water vapor is in the interval [0%,n%]the method comprises the following steps of (1) selecting,nand determining according to the maximum water vapor concentration in the gas sample to be detected.
3. The gas detection method according to claim 2, wherein in the step S2, the first steplThe target band corresponding to the target gas isP l :Q l ，P l Is the starting position of the target band of wavelengths,Q l is the end position of the target band of wavelengths,l∈[1，m]。
4. the gas detection method according to claim 1, wherein the step S4 further comprises the steps of:
and S45, multiplying the correction factor by the target standard concentration to obtain the water vapor concentration in the gas sample to be detected.
5. A gas detection system of a gas analyzer, to which the gas detection method according to any one of claims 1 to 4 is applied, the gas detection system comprising:
the acquisition module is used for respectively acquiring the absorbance spectra of each target gas with the preset range point concentration and also respectively acquiring the absorbance spectra of water vapor with different standard concentrations;
the selecting module is used for selecting a target absorption peak according to the absorbance spectrum of the target gas so as to determine a target wave band corresponding to the target absorption peak;
the detection module is used for detecting the gas sample to be detected to obtain an absorbance spectrum of the gas sample to be detected;
the matching module is used for matching the absorbance spectrum of the gas sample to be detected with the absorbance spectra of water vapor with different standard concentrations to obtain the absorbance spectrum of the water vapor in the gas sample to be detected;
and the calculation module is used for calculating the concentration of the target gas to be detected according to the preset measuring range point concentration of the target gas, the absorbance spectrum of the gas sample to be detected, the absorbance spectrum of water vapor in the gas sample to be detected and the influence of other gas to be detected in the gas sample to be detected on the target gas to be detected in a target wave band corresponding to the target gas to be detected.
6. A medium having instructions stored therein, wherein the instructions, when executed on a computer, cause the computer to perform the gas detection method of any one of claims 1-4.
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