Method for detecting a gas concentration

Abstract

The disclosure provides a gas concentration detection method. The gas concentration detection method comprises: obtaining characteristic absorption wave band information corresponding to the to-be-detected flue gas, the to-be-detected flue gas comprising at least two first flue gas components, and the characteristic absorption wave band information comprising at least two groups of first wave band data corresponding to the at least two first flue gas components; obtaining first differential absorption cross-section data corresponding to each first target flue gas component, wherein the first differential absorption cross-section data is differential absorption cross-section data of the first target flue gas component in a non-coincidence wave band during measurement of the to-be-detected flue gas by using a differential absorption spectrum method; and calculating the concentration of the at least one first target flue gas component based on the first differential absorption cross-section data to obtain first concentration data, wherein the first concentration data comprises the concentration of the at least one target flue gas component. The disclosure can improve the accuracy of the calculation result of the flue gas component concentration.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of gas detection, and particularly relates to a gas concentration detection method. BACKGROUND

[0002] Differential Optical Absorption Spectroscopy (DOAS) is a technology that uses the narrow-band absorption characteristics of the gas molecules to be detected to identify the gas molecules, and inverses the concentration of the gas molecules according to the narrow-band absorption intensity. Specifically, when a light beam passes through a gas sample cell to be detected, the light is selectively absorbed by the gas molecules to be detected, thereby changing the light intensity and spectral structure of the incident light beam. By comparing the original spectrum of the incident light beam, the absorption spectrum can be obtained. Since the gas molecules have different absorption capabilities at different light wave bands, the composition of the gas to be detected and the concentration of the corresponding gas can be determined by analyzing the absorption spectrum of the light beam at a certain wave band.

[0003] However, in the actual gas concentration measurement process, the characteristic absorption wave band of some gases often overlaps, which leads to the change of the spectral structure in a certain wave band being caused by several different gases, thereby increasing the difficulty of measuring the concentration of each component gas in the target flue gas and also bringing a large error to the measurement result. It can be seen that the existing gas concentration detection method has the problem of inaccurate concentration detection of gases with overlapping characteristic absorption wave bands. SUMMARY

[0004] The gas concentration detection method provided by the present disclosure can improve the accuracy of the calculation result of the concentration of the flue gas components.

[0005] The gas concentration detection method provided by the present disclosure comprises:

[0006] Obtaining characteristic absorption wave band information corresponding to a to-be-detected flue gas, the to-be-detected flue gas comprising at least two first flue gas components, the characteristic absorption wave band information comprising at least two groups of first wave band data corresponding to the at least two first flue gas components one by one, wherein the first wave band data comprises a characteristic absorption wave band of the corresponding first flue gas component, the at least two first flue gas components comprising at least one first target flue gas component and at least one second target flue gas component, the first wave band data corresponding to the first target flue gas component comprising an overlapping wave band and a non-overlapping wave band, and the first wave band data corresponding to the second target flue gas component comprising the overlapping wave band.

[0007] obtaining first differential absorption cross-section data corresponding to each of the first target flue gas components, wherein the first differential absorption cross-section data is differential absorption cross-section data of the first target flue gas components in the non-overlapping waveband in a process of measuring the to-be-measured flue gas by using a differential absorption spectrum method;

[0008] calculating concentrations of the at least one first target flue gas component based on the first differential absorption cross-section data to obtain first concentration data, wherein the first concentration data comprises concentrations of the at least one target flue gas component.

[0009] Optionally, after the calculating of the concentrations of the at least one first target flue gas component based on the first differential absorption cross-section data to obtain the first concentration data, the method further comprises:

[0010] obtaining second differential absorption cross-section data, wherein the second differential absorption cross-section data is a sum of differential absorption cross-section data of the at least two first flue gas components in the overlapping waveband in the process of measuring the to-be-measured flue gas by using the differential absorption spectrum method;

[0011] calculating second concentration data based on the second differential absorption cross-section data, wherein the second concentration data is a sum of concentrations of the at least two first flue gas components;

[0012] calculating a concentration of the at least one second target flue gas component based on the first concentration data and the second concentration data.

[0013] Optionally, the calculating of the concentration of the at least one second target flue gas component based on the first concentration data and the second concentration data comprises:

[0014] generating third concentration data based on the first concentration data, wherein the third concentration data is a sum of concentrations of the at least one first target flue gas component;

[0015] calculating a difference between the second concentration data and the third concentration data to obtain fourth concentration data;

[0016] determining the concentration of the at least one second target flue gas component based on the fourth concentration data.

[0017] Optionally, the determining of the concentration of the at least one second target flue gas component based on the fourth concentration data comprises:

[0018] in a case where the to-be-measured flue gas comprises one second target flue gas component, determining the fourth concentration data as the concentration of the second target flue gas component;

[0019] In a case where the to-be-tested flue gas comprises at least two second target flue gas components, the concentration of the at least two second target flue gas components is determined based on a preset means.

[0020] Optionally, the concentration of the at least two second target flue gas components is determined based on a preset means, comprising:

[0021] At least two third differential absorption cross-section data are acquired, wherein the at least two third differential absorption cross-section data correspond to the at least two second target flue gas components one by one;

[0022] A target priority order is determined based on the at least two third differential absorption cross-section data, wherein the target priority order is used to indicate the order of concentration calculation of the at least two second target flue gas components, and in the target priority order, the greater the differential absorption cross-section indicated by the third differential absorption cross-section data, the higher the priority of the corresponding second target flue gas component;

[0023] The concentration of the at least two second target flue gas components is calculated in sequence according to the target priority order.

[0024] Optionally, the concentration of the at least two second target flue gas components is calculated in sequence according to the target priority order, comprising:

[0025] Third differential absorption cross-section data corresponding to the second flue gas component are acquired, the second flue gas component being any one of the at least two second target flue gas components;

[0026] The concentration of the second flue gas component is calculated based on the third differential absorption cross-section data corresponding to the second flue gas component.

[0027] Optionally, the second concentration data is calculated based on the second differential absorption cross-section data, comprising:

[0028] The differential absorption degree corresponding to the coincident wave band is determined based on the second differential absorption cross-section data;

[0029] The differential absorption degree is filtered to obtain a target differential absorption degree;

[0030] Second concentration data is calculated based on the target differential absorption degree.

[0031] Optionally, the differential absorption degree is filtered to obtain a target differential absorption degree, comprising:

[0032] The differential absorption degree is filtered by using a wavelet filtering anti-interference algorithm to obtain a target differential absorption degree.

[0033] Optionally, the filtering processing on the differential absorption degree is performed to obtain a target differential absorption degree, and the filtering processing on the differential absorption degree comprises:

[0034] The anti-interference algorithm using Kalman filtering is used to perform filtering processing on the differential absorption degree to obtain a target differential absorption degree.

[0035] Optionally, the concentration of the at least one first target flue gas component is calculated based on the first differential absorption cross-section data, and the calculation comprises:

[0036] The concentration of the at least one first target flue gas component is calculated based on the first differential absorption cross-section data and the Lambert-Beer law.

[0037] In the embodiments of the present disclosure, when the at least two first flue gas components have coincident characteristic absorption wavebands, the concentration of the first flue gas component is calculated by using the non-coincident wavebands of the first flue gas component except the coincident wavebands, so as to improve the accuracy of the calculation result of the flue gas component concentration. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings needed to be used in the description of the embodiments of the present disclosure will be briefly introduced. Obviously, the drawings in the following description are only some of the embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor.

[0039] Figure 1 is one of the flowcharts of the gas concentration detection method provided by the embodiments of the present disclosure;

[0040] Figure 2 is the second flowchart of the gas concentration detection method provided by the embodiments of the present disclosure. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present disclosure will be described clearly and completely in combination with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only some of the embodiments of the present disclosure, not all. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present disclosure.

[0042] Please refer to Figure 1 , Figure 1 is a flowchart of a gas concentration detection method provided by the embodiments of the present disclosure. The gas concentration detection method comprises the following steps:

[0043] In step 101, feature absorption band information corresponding to the to-be-tested flue gas is obtained, the to-be-tested flue gas includes at least two first flue gas components, the feature absorption band information includes at least two groups of first band data corresponding to the at least two first flue gas components one by one, wherein the first band data includes a feature absorption band of the corresponding first flue gas component, the at least two first flue gas components include at least one first target flue gas component and at least one second target flue gas component, the first band data corresponding to the first target flue gas component includes coincident bands and non-coincident bands, and the first band data corresponding to the second target flue gas component includes the coincident bands.

[0044] In step 102, first differential absorption cross-section data corresponding to each of the first target flue gas components is obtained, wherein the first differential absorption cross-section data is differential absorption cross-section data of the first target flue gas component in the non-coincident bands in a process of measuring the to-be-tested flue gas by using a differential absorption spectrum method.

[0045] In step 103, the concentration of the at least one first target flue gas component is calculated based on the first differential absorption cross-section data, to obtain first concentration data, and the first concentration data includes the concentration of the at least one target flue gas component.

[0046] The to-be-tested flue gas can be flue gas in various flue gas emission scenarios, for example, flue gas emitted by various industrial and mining enterprises. Before flue gas is emitted, the to-be-tested flue gas needs to be treated through several rounds of chemical reactions to remove as much toxic and harmful substances as possible in the to-be-tested flue gas. The to-be-tested flue gas can be flue gas after the above chemical reaction treatment. The types of substances generated after the chemical reaction can be directly inferred according to the chemical reaction formula, that is, the types of components included in the to-be-tested flue gas can be directly inferred. Therefore, the components in the to-be-tested flue gas can be directly determined.

[0047] Specifically, since the feature absorption bands and the differential absorption cross-sections of the components are relatively fixed in the case of environmental factors being determined, the feature absorption bands and the differential absorption cross-sections of the components at corresponding temperatures and pressures can be determined by looking up a table, to obtain the first band data and the differential absorption cross-section data of each component in the to-be-tested flue gas. It can be understood that the first band data can include the feature absorption bands of the corresponding first flue gas component.

[0048] The at least two groups of first flue gas components can be components in the to-be-tested flue gas, all characteristic absorption bands of which include the coincident band. Specifically, the at least two groups of first band data can be analyzed, and all first band data with the coincident band can be screened out, and components corresponding to the first band data with the coincident band are determined as the first flue gas components. In addition to the first flue gas components, other flue gas components in the to-be-tested flue gas can be detected in concentration by using a flue gas detection method in the related art. For example, a differential absorption spectrum method can be used to detect the concentration of the other flue gas components in the to-be-tested flue gas except the first flue gas components.

[0049] In the related art, some flue gas components have two or more characteristic absorption bands, for example, SO2 gas has two characteristic absorption bands. Therefore, when a certain flue gas component has two characteristic absorption bands, and one of the characteristic absorption bands of the flue gas component is the coincident band, the concentration of the flue gas can be calculated based on the other characteristic absorption band of the flue gas component, so as to avoid the problem of too large calculation error caused by using the coincident band to calculate the concentration.

[0050] It can be understood that the characteristic absorption band of the first target flue gas component and the characteristic absorption band of the second target flue gas component both include the coincident band, that is, the coincident band is the functional characteristic absorption band of the first target flue gas component and the second target flue gas component. The characteristic absorption band of the second target flue gas component only includes the coincident band, and the characteristic absorption band of the first target flue gas component includes the coincident band and a non-coincident band.

[0051] Based on this, the concentration of each first target flue gas component can be calculated based on the non-overlapping waveband. In one specific embodiment of the present disclosure, the to-be-measured flue gas includes j first flue gas components, and the specific calculation process can be: first, among the j first flue gas components, a first flue gas component is determined, wherein the non-overlapping waveband of the first flue gas component does not overlap with the characteristic absorption waveband of the other (j-1) flue gas components, then the first differential absorption cross-section data corresponding to the first flue gas component is obtained, and the concentration of the first flue gas component is calculated based on the first differential absorption cross-section data. Then, a second flue gas component is determined from the remaining (j-1) flue gas components, wherein the non-overlapping waveband of the second flue gas component does not overlap with the characteristic absorption waveband of the remaining (j-2) flue gas components, then the first differential absorption cross-section data corresponding to the second flue gas component is obtained, and the concentration of the second flue gas component is calculated based on the first differential absorption cross-section data. In turn, until the remaining k groups of first flue gas components each include only overlapping wavebands, and the remaining k groups of first flue gas components are determined as k groups of second target flue gas components. Wherein, j is an integer greater than or equal to 2, k is an integer greater than or equal to 1, and k is less than j.

[0052] The above calculation of the concentration of the at least one first target flue gas component based on the first differential absorption cross-section data can be calculated using the Lambert-Beer law. Wherein, the specific formula for calculating the concentration of the Lambert-Beer law is:

[0053]

[0054] In the formula: OD(λ) is the differential absorbance of the to-be-measured flue gas at a wavelength of λ, I0(λ) is the incident light intensity, I(λ) is the detected light intensity after gas absorption and scattering, which can be measured by a spectrometer, σ i (i, λ) is the differential absorption cross-section data of the i-th gas in the to-be-measured flue gas at a wavelength of λ, c i is the concentration of the i-th gas in the to-be-measured flue gas, and L is the optical path. The gas differential absorption cross-section data is filtered from the gas absorption cross-section data, and the absorption cross-section represents the light absorption ability of the gas. Wherein, the to-be-measured flue gas can include j first flue gas components, and the differential absorption cross-section data of the j first flue gas components can be represented as σ = [σ1…σ j ]. Wherein, after obtaining the differential cross-section data of the j first flue gas components, filtering processing can be performed to obtain σ, for example, the characteristic absorption cross-section data of the to-be-measured j first flue gas components can be filtered to remove the low-frequency part and only retain the high-frequency part, to obtain the differential absorption cross-section data σ = [σ1…σ j ] of the j first flue gas components.

[0055] Since I0(λ) is a known quantity, and I(λ) and OD(λ) can be measured by a spectrometer, σ i (λ) can be obtained by looking up a table, therefore, only c i is unknown in the above formula, and thus the concentration c i of the i-th flue gas component can be solved based on the above formula.

[0056] Specifically, when the concentration c i of the i-th flue gas component needs to be solved, the following calculation formula can be obtained by transforming the above formula:

[0057]

[0058]

[0059]

[0060] wherein, can be calculated from the measurement data of the spectrometer, is the differential absorption cross-section matrix of the i-th gas in the non-overlapping waveband λ nc , and the optical path L is known, then the concentration c i of the i-th flue gas component can be solved.

[0061] In this embodiment, when at least two first flue gas components have overlapping characteristic absorption wavebands, the concentration of the first flue gas components is calculated by using the non-overlapping wavebands of the first flue gas components other than the overlapping wavebands, so as to improve the accuracy of the calculation results of the concentrations of the first flue gas components.

[0062] Optionally, after the concentration of the at least one first target flue gas component is calculated based on the first differential absorption cross-section data to obtain first concentration data, the method further comprises:

[0063] obtaining second differential absorption cross-section data, wherein the second differential absorption cross-section data is the sum of the differential absorption cross-section data of the at least two first flue gas components in the overlapping waveband in the process of measuring the flue gas to be measured by using the differential absorption spectroscopy;

[0064] calculating second concentration data based on the second differential absorption cross-section data, wherein the second concentration data is the sum of the concentrations of the at least two first flue gas components;

[0065] calculating the concentration of the at least one second target flue gas component based on the first concentration data and the second concentration data.

[0066] The calculating the concentration of the at least one second target flue gas component based on the first concentration data and the second concentration data comprises:

[0067] generating third concentration data based on the first concentration data, the third concentration data being a sum of the concentrations of the at least one first target flue gas component;

[0068] calculating a difference between the second concentration data and the third concentration data to obtain fourth concentration data;

[0069] determining the concentration of the at least one second target flue gas component based on the fourth concentration data.

[0070] In this embodiment, since the second differential absorption cross-section data is a sum of the differential absorption cross-section data of the at least two first flue gas components in the overlapping waveband during the measurement of the to-be-measured flue gas by using the differential absorption spectroscopy method, the second concentration data calculated based on the second differential absorption cross-section data is a sum of the concentrations of the at least two first flue gas components. The first concentration data calculated based on the above embodiment includes the concentration of each first target flue gas component, and thus the sum of all first target flue gas components can be calculated by using the first concentration data to obtain the third concentration data. In this way, the sum of the concentrations of all second target flue gas components can be obtained by subtracting the third concentration data from the second concentration data, and the fourth concentration data is the sum of the concentrations of all second target flue gas components. Thus, the concentration of the at least one second target flue gas component can be determined by using the fourth concentration data.

[0071] Optionally, the determining the concentration of the at least one second target flue gas component based on the fourth concentration data comprises:

[0072] in a case where the to-be-measured flue gas includes one second target flue gas component, determining the fourth concentration data as the concentration of the second target flue gas component;

[0073] in a case where the to-be-measured flue gas includes at least two second target flue gas components, determining the concentrations of the at least two second target flue gas components based on a preset means.

[0074] In this embodiment, since the fourth concentration is a sum of the concentrations of all second target flue gas components in the to-be-measured flue gas, in a case where the to-be-measured flue gas includes only one second target flue gas component, the fourth concentration data can be directly determined as the concentration of the second target flue gas component, thereby completing the process of solving the concentration of the second target flue gas component. Correspondingly, in a case where the to-be-measured flue gas includes at least two second target flue gas components, the concentrations of the at least two second target flue gas components can be further determined based on a preset means.

[0075] Optionally, the determining the concentrations of the at least two second target flue gas components based on the preset means comprises:

[0076] obtaining at least two third differential absorption cross section data, wherein the at least two third differential absorption cross section data correspond to the at least two second target flue gas components one by one;

[0077] determining a target priority order based on the at least two third differential absorption cross section data, wherein the target priority order is used to indicate the order of the concentration calculation of the at least two second target flue gas components, and in the target priority order, the greater the differential absorption cross section indicated by the third differential absorption cross section data, the higher the priority of the corresponding second target flue gas component;

[0078] calculating the concentrations of the at least two second target flue gas components in turn according to the target priority order.

[0079] In the above obtaining at least two third differential absorption cross section data, that is, obtaining one corresponding third differential absorption cross section data for each second target flue gas component, the third differential absorption cross section data corresponding to the second target flue gas component is the differential absorption cross section data of the second target flue gas component in the non-coincidence wave band during the measurement of the to-be-measured flue gas by using the differential absorption spectrum method.

[0080] Specifically, since in the process of calculating the concentration of each second target flue gas component respectively, the greater the differential absorption cross section of the flue gas component, the greater the calculation error it brings, therefore, before calculation, the target priority order is determined first to ensure that the concentration calculation is performed first for the second target flue gas component with a larger third differential absorption cross section, thereby avoiding the influence of the second target flue gas component with a larger differential absorption cross section on the concentration calculation process of the second target flue gas component with a smaller differential absorption cross section, and further facilitating to further improve the accuracy of the concentration calculation of the second target flue gas component.

[0081] Optionally, the calculating the concentrations of the at least two second target flue gas components in turn according to the target priority order comprises:

[0082] obtaining the third differential absorption cross section data corresponding to the second flue gas component, the second flue gas component being any one of the at least two second target flue gas components;

[0083] calculating the concentration of the second flue gas component based on the third differential absorption cross section data corresponding to the second flue gas component.

[0084] It can be understood that the above means for calculating the second flue gas component concentration based on the third differential absorption cross-section data is the same as the means adopted in the above-described embodiments, and has the same beneficial effects. To avoid repetition, it will not be described here.

[0085] In one embodiment of the present disclosure, when there are multiple gases in the overlapping waveband (i.e. the flue gas to be measured includes at least two second target flue gas components), and these gases have no other characteristic waveband (i.e. there is no non-overlapping waveband for the at least two second target flue gas components), it means that the overlapping problem cannot be avoided, and at this time, the error can only be reduced as much as possible. When there are j gases in the overlapping waveband, according to the basic formula of the DOAS principle, the calculation formula of the concentration of each gas is:

[0086] OD c = -σ c cL

[0087] wherein:

[0088]

[0089]

[0090] c = [c1 … c h … c j ] T

[0091] Suppose that the overlapping waveband λ c contains k points OD c is the differential absorption of the multi-component gas in the overlapping waveband λ c , which can be calculated from the spectrometer measurement data, σ c is the differential absorption cross-section matrix of the multi-component gas in the overlapping waveband λ c , and c is the concentration matrix of the multi-component gas.

[0092] If calculated according to the traditional method, the above formula can be used to invert the concentration c1~c j of each gas in the multi-component gas at this time, but the calculation error of this method is large, because the waveband overlapping phenomenon causes the differential absorption OD c measured by the spectrometer to be caused by the superposition of multiple gases in the overlapping waveband, thereby affecting the measurement accuracy of the gas concentration.

[0093] The embodiment of the present disclosure arranges the gas absorption cross sections in descending order, and preferentially calculates the gas concentration with the largest gas absorption cross section in the overlapping waveband, and then calculates the concentration of each component gas in descending order of the differential absorption cross section of the gas. In other words, in the solution of the multi-component gas concentration, only one gas is concerned, and other gases are regarded as error terms and interference terms. The order of the concerned gas is in descending order of the differential absorption cross section of the gas. After the concentration of one gas is solved, the differential absorption of the gas is calculated using the concentration value and the differential absorption cross section parameter of the gas, and the influence caused by the gas is subtracted from the total differential absorption in the overlapping waveband, so as to calculate the concentration of the next gas using this value, and the calculation is performed in turn, to calculate the concentration of each gas.

[0094] The principle of the sorting is:

[0095] OD c = -σ c cL

[0096] The above formula is the relationship between the differential absorption of multiple gases, the differential absorption cross section, the concentration and the optical path. Assuming that only the h gas is concerned and other gases are regarded as error and interference terms, the following formula is obtained:

[0097]

[0098]

[0099] is the differential absorption of the h gas in the overlapping waveband, is the differential absorption of the h gas in the overlapping waveband, is the differential absorption cross section of the h gas in the overlapping waveband, is the differential absorption cross section matrix of the remaining other gases in the overlapping waveband except the h gas; c h is the concentration of the h gas, c e is the concentration matrix of the remaining other gases in the mixed gas except the h gas. After the gases except the h gas are regarded as errors, the above formula is transformed as:

[0100]

[0101] where Δ is the error, OD Δ is the differential absorption error. Obviously, the smaller the error term is, the c h is closer to the true value. When the concentration information cannot be confirmed, the differential absorption cross section matrix is smaller, and the error term is smaller, that is, the differential absorption cross section of the gas h should be the largest differential absorption cross section in the current mixed gas, and then the differential absorption cross section is calculated in descending order to ensure that the error of the concentration of each currently concerned gas is kept to be the smallest.

[0102] In addition, at this time, the anti-interference gas concentration inversion algorithm such as wavelet filtering or Kalman filtering is introduced, and the value of the differential absorption error term OD Δ is further filtered, which further ensures that the error term tends to a minimum value, and the differential absorption is closer to the true value of OD , so as to improve the concentration measurement accuracy of the gas h.

[0103] Optionally, the calculating the second concentration data based on the second differential absorption cross-section data comprises:

[0104] determining the differential absorption degree corresponding to the coincident wave band based on the second differential absorption cross-section data;

[0105] filtering the differential absorption degree to obtain a target differential absorption degree;

[0106] calculating the second concentration data based on the target differential absorption degree.

[0107] In this embodiment, before the concentration calculation, filtering is performed first, which is beneficial to remove the influence of other gases in the differential absorption degree, and to retain the differential absorption degree of the current concerned gas to the greatest extent, so as to remove the noise in the differential absorption degree. Thus, it is beneficial to reduce the influence of noise, and then the accuracy in the subsequent concentration calculation process can be improved.

[0108] Optionally, the filtering the differential absorption degree to obtain a target differential absorption degree comprises:

[0109] using a wavelet filtering anti-interference algorithm to filter the differential absorption degree to obtain a target differential absorption degree.

[0110] Specifically, by filtering based on the wavelet filtering anti-interference algorithm, the influence of other gases on the target gas to be measured can be reduced. Because the wavelet filtering has good time-frequency localization property, it can well preserve the sharp peaks and abrupt changes of useful signals. When the problem of reduced gas concentration measurement accuracy caused by coincident wave bands occurs in the measurement of multi-component gas concentration based on the DOAS principle, the wavelet filtering can well eliminate the differential absorption cross-section information of other gases in the coincident wave band, and retain the differential absorption cross-section information of the concerned gas to the greatest extent, thereby reducing the influence of other gases on the concentration inversion of the target gas and improving the concentration measurement accuracy.

[0111] After the gases are sorted by differential absorption cross-section from large to small, when the concentration of the current concerned gas is solved, other gases in the mixed gas are considered as noise, and the noise is removed as much as possible through wavelet filtering, so as to achieve the purpose of improving the accuracy of the current solved gas concentration.

[0112] In an embodiment, the mixed gas differential absorption OD c is considered to be composed of the differential absorption OD of the current gas of interest h Δ plus noise OD c . The OD is decomposed by discrete wavelet, the wavelet coefficients with higher amplitude have higher correlation with OD , according to the selected threshold, the wavelet coefficients higher than the threshold are reserved, and the coefficients lower than the threshold are removed, which is the principle of reducing noise, in the next step, the remaining wavelet coefficients and scale coefficients are used to reconstruct the waveform, and the obtained waveform is filtered from noise, which is the differential absorption OD h of the gas h closest to the true value.

[0113] Optionally, the filtering processing on the differential absorption is to obtain a target differential absorption, and the filtering processing comprises:

[0114] The filtering processing on the differential absorption is to obtain a target differential absorption by using a Kalman filter anti-interference algorithm.

[0115] Unlike the above example, in this example, the Kalman filter is used as an anti-interference algorithm to improve the calculation accuracy of the gas concentration. The Kalman filter provides a recursive algorithm, which obtains the optimal estimation of the system state from the observed data with noise, which is linear, unbiased and minimum error variance. The basic idea is to give a set of reasonable assumptions, and to infer the estimated value of the next step from the observed historical data. Using the prediction and estimation characteristics of the system future value, when the gas concentration measurement accuracy is reduced due to the overlapping of the characteristic wave bands in the measurement of the concentration of multiple component gases based on the DOAS principle, only the concentration of one gas is concerned, and other gases are regarded as noise, and the Kalman filter principle is used to filter out the noise information, so as to obtain higher concentration calculation accuracy. The idea of Kalman filter is to use the predicted value to correct the observed value, improve the accuracy of the measured value, reduce the influence of other gases on the gas of interest in the overlapping wave band, and obtain the corresponding concentration, and then inversely calculate the concentration of other gases. The state equation of the Kalman filter is:

[0116] S(n) = AS(n-1) + w(n) (1)

[0117] x(n) = CS(n) + v(n) (2)

[0118] In this embodiment, the parameters in the above formula (1) can be defined as: S(n) is a state variable, which is defined as the concentration value c h; S(n-1) is the gas concentration value at the previous wavelength; A is a state parameter, in this case, the gas concentration value is regarded as a constant, i.e. the concentration values at the previous wavelength and the next wavelength are equal; w(n) is the system noise; each parameter in the above formula (2) can be defined as x(n) is a measurement value, which is defined as a differential absorbance value at the wavelength value λ n

[0119] In the embodiments of the present disclosure, when analyzing the flue gas to be measured, two methods are used to solve the problem of overlapping of gas characteristic absorption bands, and after this method, the measurement accuracy of each gas concentration in the multi-component mixed gas can be effectively improved. The core idea is roughly the classification and sorting method, after the inevitable gas characteristic band overlap phenomenon occurs, the gas concentration measurement accuracy is improved as much as possible. And when inverting the gas concentration, an anti-interference gas concentration inversion algorithm is used, which reduces the influence of noise and other gases on the gas concentration inversion of the concerned gas in the concentration calculation process, further improving the concentration measurement accuracy.

[0120] The method provided by the embodiments of the present disclosure measures the multi-component flue gas concentration by using the differential optical absorption spectroscopy (DOAS) in the spectral analysis method, and proposes a solution to the problem of concentration measurement accuracy decline caused by the characteristic band overlap phenomenon often occurring in the actual measurement process. The solution can effectively improve the measurement accuracy when the band overlap phenomenon occurs in the concentration measurement process, and does not need to increase other hardware, greatly saving the cost. The method proposed by the present disclosure effectively makes up for the shortcomings of the existing technology. The present disclosure classifies the gases by using the different characteristics of different gases in absorbing light bands, sorts the gases by using the characteristics of the gas characteristic absorption cross section, and then uses an anti-interference algorithm to invert the measured gas concentration, further improving the gas concentration measurement accuracy. When facing the problem of overlapping of gas absorption bands, it can still provide good solving performance, to a certain extent, to ensure the gas concentration measurement accuracy and make up for the shortcomings of the existing technology.

[0121] Please refer to Figure 2 ​A flowchart of a gas concentration detection method provided by one embodiment of the present disclosure is shown in the figure, and the method comprises the following steps: step 1) judging whether there is a coincident wave band in the flue gas to be detected, if not, using an anti-interference algorithm to calculate the concentration of each flue gas component in turn; if yes, step 2) is performed, in the following, the multi-component flue gas with a coincident wave band is expressed as at least two first flue gas components; step 2) judging whether the at least two first flue gas components have a non-coincident wave band, and the first flue gas component with a non-coincident wave band is referred to as a first target flue gas component, and the first flue gas component with only a coincident wave band is referred to as a second target flue gas component; if yes, step 3) is performed, if not, step 4) is performed; step 3) using the non-coincident wave band data to calculate the concentration of each first target flue gas component; step 4) sorting the second target flue gas components with a coincident wave band to obtain a target priority order; 5) according to the target priority order, using an anti-interference algorithm to calculate the concentration of each second target flue gas component in turn; and step 6) outputting the concentration information.

[0122] It should be noted that in this document, the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusions, so that processes, methods, articles, or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed, or inherent to such processes, methods, articles, or devices. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or device that includes the element.

[0123] From the above description of the embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be realized by means of software and a necessary general hardware platform, of course, they can also be realized by hardware, but in many cases, the former is a better embodiment. Based on such understanding, the technical solutions of the present disclosure can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a plurality of instructions for making an electronic device (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) execute the methods described in various embodiments of the present disclosure.

[0124] The embodiments of the present disclosure are described above in combination with the drawings, but the present disclosure is not limited to the above-mentioned specific embodiments, and the above-mentioned specific embodiments are only illustrative, not restrictive, and those skilled in the art can make many forms without departing from the purpose of the present disclosure and the scope protected by the claims under the inspiration of the present disclosure, which all belong to the protection of the present disclosure.

Claims

1. A method of detecting a concentration of a gas, characterized by, The method comprises the following steps: obtaining characteristic absorption band information corresponding to the to-be-tested flue gas, wherein the to-be-tested flue gas comprises at least two first flue gas components, and the characteristic absorption band information comprises at least two groups of first band data corresponding to the at least two first flue gas components, wherein the first band data comprises a characteristic absorption band of the corresponding first flue gas component, the at least two first flue gas components comprise at least one first target flue gas component and at least one second target flue gas component, the first band data corresponding to the first target flue gas component comprises coincident bands and non-coincident bands, and the first band data corresponding to the second target flue gas component comprises the coincident bands; obtaining first differential absorption cross-section data corresponding to each first target flue gas component, wherein the first differential absorption cross-section data is differential absorption cross-section data of the first target flue gas component in the non-coincident bands in a process of measuring the to-be-tested flue gas by using a differential absorption spectrum method; calculating the concentration of the at least one first target flue gas component based on the first differential absorption cross-section data to obtain first concentration data, wherein the first concentration data comprises the concentration of the at least one target flue gas component; when the to-be-tested flue gas comprises at least two second target flue gas components, obtaining third differential absorption cross-section data corresponding to the at least two second target flue gas components, determining a target priority order based on the third differential absorption cross-section data, and the second target flue gas component with a larger differential absorption cross-section has a higher priority in the target priority order; calculating the concentration of the at least two second target flue gas components in sequence according to the target priority order.

2. The method of claim 1, wherein, After the step of calculating the concentration of the at least one first target flue gas component based on the first differential absorption cross-section data to obtain the first concentration data, the method further comprises the following steps: obtaining second differential absorption cross-section data, wherein the second differential absorption cross-section data is a sum of differential absorption cross-section data of the at least two first flue gas components in the coincident bands in the process of measuring the to-be-tested flue gas by using the differential absorption spectrum method; calculating second concentration data based on the second differential absorption cross-section data, wherein the second concentration data is a sum of the concentrations of the at least two first flue gas components; calculating the concentration of the at least one second target flue gas component based on the first concentration data and the second concentration data.

3. The method of claim 2, wherein, The step of calculating the concentration of the at least one second target flue gas component based on the first concentration data and the second concentration data comprises the following steps: generating third concentration data based on the first concentration data, wherein the third concentration data is a sum of the concentrations of the at least one first target flue gas component; calculating a difference value between the second concentration data and the third concentration data to obtain fourth concentration data; determining the concentration of the at least one second target flue gas component based on the fourth concentration data.

4. The method of claim 3, wherein, The step of determining the concentration of the at least one second target flue gas component based on the fourth concentration data comprises the following steps: In the case that the to-be-tested flue gas comprises a second target flue gas component, the fourth concentration data is determined as the concentration of the second target flue gas component; In the case that the to-be-tested flue gas comprises at least two second target flue gas components, the concentrations of the at least two second target flue gas components are determined based on a preset means.

5. The method of claim 4, wherein, The concentration of the at least two second target flue gas components is calculated in sequence according to the target priority order, comprising: Obtaining third differential absorption cross-section data corresponding to a second flue gas component, the second flue gas component being any one of the at least two second target flue gas components; Based on the third differential absorption cross-section data corresponding to the second flue gas component, the concentration of the second flue gas component is calculated.

6. The method of claim 2, wherein, The second concentration data is calculated based on the second differential absorption cross-section data, comprising: Based on the second differential absorption cross-section data, the differential absorption degree corresponding to the coincident wave band is determined; The differential absorption degree is filtered to obtain a target differential absorption degree; The second concentration data is calculated based on the target differential absorption degree.

7. The method of claim 6, wherein, The differential absorption degree is filtered to obtain a target differential absorption degree, comprising: The differential absorption degree is filtered using a wavelet filter anti-interference algorithm to obtain a target differential absorption degree.

8. The method of claim 7, wherein, The differential absorption degree is filtered to obtain a target differential absorption degree, comprising: The differential absorption degree is filtered using a Kalman filter anti-interference algorithm to obtain a target differential absorption degree.

9. The method of claim 1, wherein, The concentration of the at least one first target flue gas component is calculated based on the first differential absorption cross-section data, comprising: The concentration of the at least one first target flue gas component is calculated based on the first differential absorption cross-section data using the Lambert-Beer law.

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