Infrared spectrum mixed gas identification method and identification device

Abstract

The application discloses an infrared spectrum mixed gas identification method and an identification device. The identification method comprises the following steps: sending a regulation and control instruction to a regulation and control component according to a regulation and control strategy, so that an infrared narrow-band filter generates multiple detection light beams with different center wavelengths, which are incident into a detection component; obtaining detection information obtained by detecting values corresponding to the detection component and each detection light beam, and judging whether it is a mixed gas type through a judgment rule; if yes, performing multi-component analysis on the detection information to obtain component analysis information; and obtaining key detection parameters from the detection information according to the component analysis information, and performing analysis to obtain a corresponding gas identification result. The identification method can realize continuous spectrum scanning in a certain waveband range by controlling the regulation and control component to adjust the infrared narrow-band filter to generate detection light beams with different center wavelengths, can perform multi-component analysis and obtain a gas identification result, and can realize reliable analysis on a mixed gas with multiple gas components and accurate acquisition of the concentration values of each gas.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a method and device for identifying infrared spectral mixed gases. Background Technology

[0002] Infrared gas detection methods primarily utilize the absorption characteristics of gas molecules to specific wavelengths of infrared light for qualitative or quantitative analysis. This detection process typically relies on non-dispersive infrared (NDIR) methods. NDIR methods use a broadband infrared light source to directly illuminate the gas to be measured, with a narrow-band filter installed in front of the detector to allow only infrared light of the target gas's characteristic absorption wavelengths to pass through. By measuring the intensity attenuation of light after passing through the gas sample, the gas concentration is calculated using Lambert-Beer's law. NDIR methods are characterized by their relatively simple structure, mature technology, good stability, and relatively low cost. However, they typically operate only in one wavelength band, measuring the concentration of a specific gas. If a mixture of multiple gases exists in space, the single wavelength band operated by a single NDIR device cannot determine the composition of the mixture, let alone accurately detect the concentration of each gas in the mixture. Therefore, existing gas detection methods based on non-dispersive infrared technology suffer from the problem of inaccurate detection of mixed gases. Summary of the Invention

[0003] This invention provides a method and device for identifying mixed gases using infrared spectroscopy, aiming to solve the problem that existing gas detection methods based on non-dispersive infrared light cannot accurately detect mixed gases.

[0004] In a first aspect, embodiments of this application provide a method for identifying infrared spectral mixed gases, wherein the method is applied in a controller of an identification device, the controller being communicatively connected to a control component and a detection component to achieve data information transmission, and an infrared light source, an infrared narrowband filter, and a detection component being sequentially arranged within the gas detection cavity of the identification device; the infrared narrowband filter is fixed to the control component, and the method includes: According to the preset control strategy, control commands are sent to the control component to adjust the infrared narrowband filter to generate multiple detection beams with different center wavelengths that enter the detection component. The detection values ​​corresponding to the detection components and each detection beam are obtained to acquire the corresponding detection information. The detection information is determined to be a mixed gas type based on the preset judgment rules, the pre-stored spectral analysis model, and the control strategy. If the detected information is a mixed gas type, the detected information is analyzed in multiple components according to the preset multi-component analysis strategy and the spectral analysis model to obtain the corresponding component analysis information; the component analysis information includes gas component information and concentration ratio information. Based on the gas composition information, obtain the matching key detection parameters from the detection information; The key detection parameters are analyzed based on the preset concentration analysis strategy and the concentration ratio information to obtain the corresponding gas identification results.

[0005] Secondly, embodiments of this application also provide an infrared spectral mixed gas identification device, which applies the infrared spectral mixed gas identification method as described in the first aspect, wherein the infrared spectral mixed gas identification device includes a gas detection cavity, an infrared light source, an infrared narrowband filter, a detection component, a controller, and a control component. The infrared light source, the infrared narrowband filter, and the detection component are arranged sequentially inside the gas detection cavity of the identification device; the gas detection cavity has an elongated structure, with the infrared light source and the detection component respectively located at both ends of the gas detection cavity; multiple ventilation holes are provided on both side walls of the gas detection cavity; the infrared narrowband filter is fixed to the control component; The controller is connected to the control component and the detection component to transmit data information.

[0006] This invention provides a method and device for identifying mixed gases using infrared spectroscopy. The method includes: sending a control command to a control component according to a preset control strategy to adjust an infrared narrowband filter to generate multiple detection beams with different center wavelengths that are incident on a detection component; acquiring the detection values ​​corresponding to each detection beam from the detection component to obtain corresponding detection information; determining whether the detection information is a mixed gas type based on judgment rules, a spectral analysis model, and the control strategy; if it is a mixed gas type, performing multi-component analysis on the detection information according to a multi-component analysis strategy and a spectral analysis model to obtain component analysis information; and obtaining key detection parameters from the detection information based on the component analysis information and performing analysis to obtain the corresponding gas identification result. This identification method, by controlling the control component to adjust the infrared narrowband filter to generate detection beams with different center wavelengths, achieves continuous spectral scanning within a certain wavelength range; if the detection information is determined to be a mixed gas type, multi-component analysis is performed and gas identification results are obtained, enabling reliable analysis of mixed gases with multiple gas components and accurate acquisition of the concentration values ​​of each gas. Attached Figure Description

[0007] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 A flowchart of the infrared spectroscopy mixed gas identification method provided in the embodiments of the present invention; Figure 2 This is a schematic diagram illustrating an application scenario of the infrared spectroscopy mixed gas identification method provided in this embodiment of the invention. Figure 3 This is a first application effect diagram of the infrared spectroscopy mixed gas identification method provided in the embodiment of the present invention; Figure 4 This is a second application effect diagram of the infrared spectroscopy mixed gas identification method provided in the embodiment of the present invention; Figure 5 This is a structural diagram of the infrared spectroscopy mixed gas identification device provided in an embodiment of the present invention.

[0009] Reference numerals: 1. Gas detection chamber; 2. Infrared light source; 3. Infrared narrow band filter; 4. Detection component; 5. Controller; 6. Adjustment component; 11. Vent. Detailed Implementation

[0010] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0011] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0012] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0013] This application discloses a method for identifying infrared spectral mixed gases, wherein the method is applied in the controller of an identification device; please refer to... Figure 2As shown in the figure, this method is applied to the controller of the identification device. The controller is communicatively connected to the control component and the detection component to realize the transmission of data information. The infrared light source, the infrared narrowband filter, and the detection component are arranged sequentially in the gas detection cavity of the identification device; the infrared narrowband filter is fixed on the control component. The controller is a component used to acquire data information, process it, and issue corresponding control commands, such as an MCU (Microcontroller Unit) chip or an FPGA (Field Programmable Gate Array) circuit. The infrared light source is a device that emits infrared beams. The infrared narrowband filter is used to filter the infrared light generated by the infrared light source, allowing only infrared light of a specific wavelength to pass through; the detection component is used to detect the intensity of the received infrared light of a specific wavelength to obtain the corresponding received intensity. The control component is used to control the detection component to adjust the infrared narrowband filter to generate detection beams with different center wavelengths that enter the detection component.

[0014] like Figure 1 As shown in the embodiment of this application, an infrared spectral mixed gas identification method is provided, which includes steps S110 to S160.

[0015] S110. According to the preset control strategy, a control command is sent to the control component to adjust the infrared narrowband filter to generate multiple detection beams with different center wavelengths that enter the detection component.

[0016] Specifically, a control strategy can be set based on the configuration structure of the control component. The controller then sends control commands to the control component according to the control strategy. The control component adjusts the infrared narrowband filter according to the control commands, thereby generating multiple detection beams with different center wavelengths. Each detection beam illuminates the detection component, and the detection value corresponding to each detection beam can be obtained.

[0017] In a more specific embodiment, step S110 includes the following sub-steps: the control component is a rotation control component, which adjusts the tilt angle of the infrared narrowband filter according to the control command; or, the control component is a heating control component, which adjusts the temperature of the infrared narrowband filter according to the control command.

[0018] Specifically, the control component can be a rotary control component, such as... Figure 2As shown, the rotation adjustment component is fixedly connected to the infrared narrowband filter. The tilt angle of the infrared narrowband filter can be adjusted by rotating the component; the tilt angle is the angle between the axis of the infrared narrowband filter and the infrared beam emitted by the infrared light source. If the tilt angle is zero, it indicates that the infrared beam emitted by the infrared light source is perpendicular to the mirror surface corresponding to the infrared narrowband filter, and the infrared light wavelength transmitted by the infrared narrowband filter is at its maximum. By gradually adjusting the tilt angle of the infrared narrowband filter, the angle between the infrared beam emitted by the infrared light source and the mirror surface corresponding to the infrared narrowband filter decreases, and the infrared light wavelength transmitted by the infrared narrowband filter gradually decreases.

[0019] Infrared narrowband filters achieve band selection based on the principle of multi-beam interference. When the resonance condition is met, light of a specific wavelength (center wavelength λ0) undergoes constructive interference and passes through, while other wavelengths are reflected due to destructive interference. For an FP structure (Fabry-Pérot etalon) infrared narrowband filter with a spacer layer in between, its resonance condition is: ; in, n c The refractive index of the spacer layer, d c The thickness of the spacer layer, i c The refraction angle of the spacer layer, m For a given resonance order... m When the tilt angle is zero, the center wavelength l m satisfy: ; When the tilt angle is i =0° increased to i s At that time, according to Snell's law n a sin i s = n c sin i c n a Let be the refractive index of air; then there exists a corresponding relationship: ; along with i s Increase i c Decrease, therefore l m ( i s )< l m ( θ=0° The center wavelength shifts towards shorter wavelengths. When the tilt angle is zero, i c =0°, the center wavelength has a maximum value: ; Inclination angle is i s hour( i s (≠0°), center wavelength is: ; in, n c * =n c / n a The term refers to the effective refractive index ratio. The tilt angle of the infrared narrowband filter was adjusted, gradually increasing from 0°, and the center wavelength of the infrared light transmitted through the filter was measured. The test results are shown below. Figure 3 As shown. Figure 3 The center wavelength of infrared light was tested at tilt angles of 0°, 15°, 30° and 45°, and the gas absorption coefficients of CH4 (methane) and C3H8 (propane) were measured respectively.

[0020] In another embodiment, the control component can also be a heating control component. The heating control component is attached to the infrared narrowband filter to heat the infrared narrowband filter. For example, the heating control component can be attached to the outer edge of the infrared narrowband filter, which will not affect the filtering function of the infrared narrowband filter. Alternatively, the heating control component can be made of a transparent material and attached to the mirror surface on one side of the infrared narrowband filter. The heating control component made of a transparent material (such as indium tin oxide) will not affect the filtering function of the infrared narrowband filter.

[0021] When the operating temperature of an infrared narrowband filter deviates from the reference temperature, its center wavelength shifts. For common infrared film systems, as the temperature increases, the center wavelength of the infrared narrowband filter shifts towards longer wavelengths, i.e., a redshift occurs. For an FP (Fabry-Pérot etalon) infrared narrowband filter, when the tilt angle is zero, the center wavelength of the infrared narrowband filter can be expressed as: ; When the operating temperature is not equal to the design reference temperature, the center wavelength of the infrared narrowband filter is affected by the thermal expansion effect and the thermo-optic effect. The thermal expansion effect can be expressed as: ; in, d c (T s ) Temperature of the infrared narrowband filter T s The thickness of the time interval layer, d 0 For reference temperature (e.g.) T 0 The thickness of the spacer layer at 25°C T s The operating temperature of the infrared narrowband filter. T 0 This is a reference temperature.

[0022] For the vast majority of infrared optical thin film materials α >0, therefore, as the temperature rises... T s >T 0 hour, d c (T s )>d 0 And as the temperature drops T s <T 0 hour, d c (T s )<d 0 The corresponding thermo-optical effect can be expressed as: ; n c (T s ) The temperature T of the infrared narrowband filter s The refractive index at that time n 0 For reference temperature (e.g.) T 0 The refractive index at 25℃ dn / dT The thermo-optic coefficient is the change in refractive index per unit temperature change.

[0023] For common infrared optical thin film materials dn / dT>0 Therefore, as the temperature rises T s >T 0 hour, n c(T s )>n 0 As the temperature drops T s <T 0 hour, n c (T s )<n 0 Considering both thermal expansion and thermo-optical effects, at the operating temperature... T s greater than the reference temperature T 0 hour, l (T s )>λ 0 That is, the center wavelength red-shifts, at the operating temperature T s Less than the reference temperature T 0 hour, λ(T s )<λ 0 This means that the center wavelength undergoes a blue shift. The operating temperature of the infrared narrowband filter was gradually increased, and the center wavelength of the infrared light transmitted through the filter was measured. The test results are as follows: Figure 4 As shown. Figure 4 The center wavelength of infrared light and the gas absorption coefficients of CH4 (methane) and C3H8 (propane) were tested at working temperatures of 5℃, 15℃, 25℃ and 35℃.

[0024] In a more specific embodiment, two infrared narrowband filters and two detection components may also be provided, one of which is fixedly connected to the rotation control component. By adjusting the tilt angle of the infrared narrowband filter, its modulation range is expanded to [ l r , l 0 ],in l r < l 0 Another infrared narrowband filter has an additional thermal control component attached to it. By adjusting the operating temperature of the infrared narrowband filter, its modulation range is extended to [ ]. l 0 , l t ],in l 0 < l tBy combining two infrared narrowband filters and two detection components, the modulation range can be expanded to [ l r , l t This is to further enhance the coverage range of infrared light wavelengths.

[0025] S120. Obtain the detection values ​​corresponding to the detection components and each detection beam to obtain the corresponding detection information.

[0026] Furthermore, the detection values ​​corresponding to each detection beam are obtained from the detection components. Each detection beam corresponds to an infrared light wavelength, and each detection beam corresponds to a detection value. By combining the detection values ​​of each infrared light wavelength, the detection information can be obtained.

[0027] In a more specific embodiment, step S120 includes the following sub-steps: obtaining the received intensity corresponding to the detection component and each detection beam; calculating the ratio between the received intensity and the transmitted intensity to obtain the corresponding intensity ratio; and calculating the ratio between the intensity ratio and the pre-stored intensity attenuation coefficient corresponding to each detection beam to obtain the detection value corresponding to each detection beam.

[0028] Specifically, the received intensity of the detection component and each detection beam can be obtained, such as the intensity relative to the center wavelength. l 1 , l 2 …The corresponding infrared light receiving intensities are Q1, Q2…; the ratio between each receiving intensity and the emitted intensity Q0 is calculated to obtain the intensity ratio of each receiving intensity; the emitted intensity is also the intensity of the infrared beam emitted by the infrared light source. The controller also pre-stores the intensity attenuation coefficient corresponding to each detection beam. For example, if the control component is a rotary control component, the intensity attenuation coefficient f=0.88 when the center wavelength is 3400nm (tilt angle is 0°), and the intensity attenuation coefficient f=0.87 when the center wavelength is 3340nm (tilt angle is 30°). In order to eliminate the attenuation effect of infrared narrowband filter deflection or heating on transmittance, and to ensure that the detection value only retains the influence of gas concentration on infrared light transmission attenuation, each intensity ratio is divided by the corresponding intensity attenuation coefficient, that is, the ratio between the intensity ratio and the pre-stored intensity attenuation coefficient corresponding to the detection beam is calculated to obtain the detection value A1, A2… of each detection beam. By obtaining the intensity attenuation coefficient corresponding to each detection beam to correct the intensity ratio, the accuracy of gas detection can be further improved.

[0029] S130. Determine whether the detected information is a mixed gas type based on the preset judgment rules, the pre-stored spectral analysis model and the control strategy.

[0030] First, the detection information is judged based on the judgment rules, pre-stored spectral analysis models, and control strategies. The judgment result indicates whether the detection information corresponds to a mixed gas type. If the judgment rules determine that the detection information corresponds to a detection signal containing multiple gas components, then the detection information is determined to be a mixed gas type; if the judgment rules determine that the detection information corresponds to a detection signal containing only one gas type, then the detection information is determined not to be a mixed gas type. The spectral analysis model is a pre-constructed standard model used for spectral analysis of the detected values. The spectral analysis model contains standard feature vectors corresponding to each single gas type, as well as mixed feature vectors corresponding to multiple mixed gas types.

[0031] In a more specific embodiment, step S130 includes the following sub-steps: normalizing each detection value in the detection information according to the normalization processing rule corresponding to the control strategy to obtain the corresponding detection feature vector; calculating the vector space angle between the detection feature vector and the standard feature vector corresponding to each single gas type in the spectral analysis model; determining whether the smallest vector space angle is less than the vector space angle threshold corresponding to the vector space angle in the determination rule; if the smallest vector space angle is less than the vector space angle threshold, determining that the detection information is not a mixed gas type; if the smallest vector space angle is not less than the vector space angle threshold, determining that the detection information is a mixed gas type.

[0032] Specifically, if the control strategy is tilt angle control, then each detected value in the detection information is normalized according to the normalization rule corresponding to this control strategy to obtain the detection feature vector corresponding to tilt angle control. If the control strategy is temperature control, then each detected value in the detection information is normalized according to the normalization rule corresponding to this control strategy to obtain the detection feature vector corresponding to temperature control. For example, if the control strategy is temperature control, to highlight the differences between vectors, the average value of all detected values ​​can be subtracted from each detected value in the detection information, and the result can be used as the detection feature vector obtained after normalization, which is to obtain the k-dimensional gas spectral absorption vector. A(k) As the corresponding detection feature vector.

[0033] The spectral analysis model includes a standard eigenvector corresponding to a single gas type. The standard eigenvector for the same gas type differs depending on the control strategy employed. The standard eigenvector is also a k-dimensional spectral absorption vector; for example, the standard eigenvector (spectral absorption vector) for methane gas under tilt angle control is... A CH4 = (0.32, 0.37, 0.53, 0.69); The standard eigenvector (spectral absorption vector) of methane gas for temperature regulation is: A CH4= (0.69, 0.2, -0.26, -0.65). The vector space angle between the detected feature vector and the standard feature vectors for each individual gas type can be calculated. The vector space angle can be a cosine vector space angle value. A larger vector space angle value indicates a greater difference in features between the detected feature vector and the standard feature vector; a smaller vector space angle value indicates a closer similarity in features between the detected feature vector and the standard feature vector. A corresponding vector space angle can be calculated for each standard feature vector.

[0034] For example, the formulas for calculating the vector space angle between the detected feature vector and the standard feature vector of methane, and the vector space angle between the detected feature vector and the standard feature vector of propane are as follows: i CH4 =arccos[( A CH4 •A target ) / (║ A CH4 ║ • ║ A target ║)]; i C3H8 =arccos[( A C3H8 •A target ) / (║ A C3H8 ║ • ║ A target ║)]. Among them, A target To detect feature vectors, A CH4 This is the standard eigenvector of methane. A C3H8 This is the standard eigenvector of propane. i CH4 The vector space angle corresponding to the standard eigenvector of methane. i C3H8 The vector space angle corresponding to the standard eigenvector of propane.

[0035] The process involves obtaining the vector space angle threshold corresponding to each individual gas type in the judgment rules, i.e., different gas types correspond to different vector space angle thresholds. It then determines whether the smallest vector space angle is less than the corresponding vector space angle threshold. If the result is less than, it indicates that the gas concentration of the detected information can be analyzed using a single gas type, and the detected information is not a mixed gas type. If the result is not less than, it indicates that the gas concentration of the detected information cannot be analyzed using a single gas type, and the detected information is determined to be a mixed gas type. This solution focuses on a detailed explanation of the process of multi-component gas concentration analysis. The vector space angle threshold can be determined based on the vector space angle correspondence between the standard feature vectors of different gas types. Due to the presence of system noise, the spectral absorption vector of any gas will exhibit a certain degree of discrete distribution. Algorithms such as Support Vector Machines (SVM) can be used to identify the decomposition of different gases in the spectral absorption vector space, and then the vector space angle threshold can be configured based on a more precise definition.

[0036] In a more specific embodiment, after step S130, the method further includes: if the detection information is not a mixed gas type, determining the single gas type corresponding to the detection information; obtaining key detection parameters matching the single gas type based on the detection information; and analyzing the key detection parameters according to a preset concentration analysis strategy to obtain the corresponding gas identification result.

[0037] Specifically, the type corresponding to the standard feature vector of the maximum vector space angle is determined as the single gas type corresponding to the detection information.

[0038] Furthermore, based on the detection information, key detection parameters matching the gas type are obtained, specifically including: determining the target center wavelength corresponding to the gas type; and obtaining the detection value corresponding to the target center wavelength from the detection information as a key detection parameter.

[0039] First, determine the target center wavelength corresponding to the gas type. There is only one target center wavelength. For example, the target center wavelength for detecting methane gas is 3310 nm. Based on the determined target center wavelength, the corresponding detection value can be directly obtained from the detection information. If the detection information contains a detection value with a target center wavelength of 3310 nm, then that detection value can be directly obtained as the key detection parameter.

[0040] The key detection parameters are analyzed according to the concentration analysis strategy to obtain the corresponding target gas concentration as the final gas identification result. Specifically, this includes: analyzing the key detection parameters according to the gas molecule analysis rules in the concentration analysis strategy to obtain the corresponding gas molecule density; and converting the gas molecule density according to the conversion formula in the concentration analysis strategy to obtain the corresponding target gas concentration as the gas identification result.

[0041] Specifically, the key detection parameters are analyzed according to the gas molecule analysis rules in the concentration analysis strategy to obtain the gas molecule density; the gas molecule analysis rules are set according to the Lambert-Beer Law. The Lambert-Beer Law is as follows: ; Where x is the molecular number density, with units of molecules / cm³. 3 σ represents the absorption cross section, in cm. 2 / indivual, l Optical path length (length of the gas detection cavity), in cm; I To detect light intensity, I 0 The reference intensity of the beam; The corresponding rules for gas molecule analysis can then be constructed as follows: ; in, Â The values ​​of the key detection parameters, that is Â=I / I 0 .

[0042] Furthermore, the conversion formula in the concentration analysis strategy converts the gas molecule density, and the conversion formula can be expressed as: ; in, k B Boltzmann's constant is 1.3806 × 10⁻⁶. −23 J / K, T The thermodynamic temperature (T=T0=25℃ by default), in K. p This represents the partial pressure of the gas.

[0043] Further calculations of gas partial pressures and preset atmospheric pressures (e.g.) p 0 The ratio between (e.g., =101kPa) is used to obtain the gas concentration value as the target gas concentration.

[0044] In a more specific embodiment, the controller is communicatively connected to a temperature sensor disposed within the gas detection chamber. The conversion of the gas molecule density according to the conversion formula in the concentration analysis strategy includes: acquiring the temperature detection value obtained by the temperature sensor; and converting the gas molecule density according to the conversion formula and the temperature detection value to obtain the corresponding target gas concentration.

[0045] Furthermore, since the gas concentration changes continuously with temperature during gas detection, to obtain a more accurate target gas concentration, a temperature sensor installed inside the gas detection chamber can be used to acquire the temperature detection value, which can then replace the thermodynamic temperature in the above formula. T That is, the actual measured temperature is used instead of the default thermodynamic temperature, and the gas partial pressure that matches the measured temperature value is calculated. p’ Then calculate the partial pressure of the gas. p’ With preset atmospheric pressure (such as) p 0 The ratio between (e.g., =101kPa) is used to obtain the gas concentration value as the target gas concentration.

[0046] In a more specific embodiment, the controller is communicatively connected to a pressure sensor disposed within the gas detection chamber. The conversion of the gas molecule density according to the conversion formula in the concentration analysis strategy further includes: acquiring the temperature detection value detected by the temperature sensor and the pressure detection value detected by the pressure sensor; and converting the gas molecule density according to the conversion formula, the temperature detection value, and the pressure detection value to obtain the corresponding target gas concentration.

[0047] Furthermore, the target gas concentration is also correlated with external air pressure, which varies with altitude and whether the measurement environment is sealed. To more accurately obtain the target gas concentration, a pressure sensor can be installed inside the gas detection chamber. The pressure sensor's measured value can replace the preset atmospheric pressure used in the above calculation process. That is, the partial pressure of the gas can be calculated. p’ The ratio between the gas pressure reading and the gas pressure reading is used to obtain the gas concentration value, which is then taken as the target gas concentration.

[0048] S140. If the detected information is a mixed gas type, perform multi-component analysis on the detected information according to the preset multi-component analysis strategy and the spectral analysis model to obtain the corresponding component analysis information.

[0049] If the detected information is a mixed gas, then multi-component analysis is performed on the detected information according to the pre-set multi-component analysis strategy and the above-mentioned spectral analysis model. Multi-component analysis means obtaining the types of gases contained in the mixed gas and the concentration ratio coefficients of each gas type. The obtained component analysis information includes gas component information and concentration ratio information.

[0050] In a more specific embodiment, step S140 includes the following sub-steps: calculating the mixing vector space angle between the detection feature vector corresponding to the detection information and the mixing feature vector corresponding to each mixed gas type in the spectral analysis model; obtaining the gas type corresponding to the mixing feature vector with the highest mixing vector space angle as the corresponding gas component information; and performing component analysis on the detection feature vector to obtain the corresponding concentration ratio information based on the multi-component analysis strategy and the standard feature vectors of the gas types contained in the gas component information in the spectral analysis model.

[0051] The spectral analysis model also includes mixing feature vectors corresponding to each gas mixture type, such as the mixing feature vector corresponding to the methane / hydrogen sulfide gas mixture, the mixing feature vector corresponding to the methane / propane gas mixture, etc. The mixing vector space angle between the detection feature vector corresponding to the detection information and the mixing feature vector of each gas mixture type can be calculated sequentially. The gas type corresponding to the mixing feature vector with the highest mixing vector space angle is then obtained as the corresponding gas component information.

[0052] Furthermore, standard feature vectors of the gas types contained in the gas component information in the spectral analysis model are obtained; for example, if the gas type contained in the gas component information is methane / propane, then the standard feature vectors of methane gas in the spectral analysis model and the current control strategy can be obtained, as well as the standard feature vectors of propane gas in the spectral analysis model and the current control strategy.

[0053] Based on the multi-component analysis strategy and the standard feature vectors of the corresponding gas types, the detected feature vectors are analyzed to obtain the corresponding concentration ratio information. For example, for a mixture of two gas types, the obtained concentration ratio information includes the concentration ratio coefficients m1 and m2 corresponding to the two gas types, respectively.

[0054] Multi-component analytical strategies can be analytical strategies constructed based on the least squares method. For example, the basic model could be: A target = m 1 A CH4 +m 2 A C3H8 , A target To detect feature vectors, A CH4 This is the standard eigenvector of methane. A C3H8 Let be the standard eigenvectors of propane. Represented in matrix form: y=Xβ ,in, β= ; X= ,T It is the transpose symbol. y=A target T The least squares solution satisfies: X T Xβ=X T y ; calculate separately X T X and X T y Find the numerical values ​​of the two matrices and solve the system of equations. β=(X T X) −1 X T y Solving for this will yield the results. m 1 and m 2 The corresponding numerical values. Algorithms such as neural networks can also be used to more accurately solve for the concentration ratio coefficients of the two components in a gas mixture under a nonlinear absorption model. m 1 and m 2 .

[0055] For example, the control strategy is tilt angle control. A CH4 =[0.32, 0.37, 0.53, 0.69] A C3H8 =[0.58,0.58, 0.50, 0.26]; A target =[0.38, 0.44, 0.51, 0.48]; then in the above formula, X= , y = The final concentration ratios obtained from the analysis are as follows: m 1 =0.5667, m 2 =0.3804.

[0056] S150. Obtain matching key detection parameters from the detection information based on the gas composition information.

[0057] Furthermore, based on the gas composition information, key detection parameters that match the gas composition information are obtained from the detection information.

[0058] In a more specific embodiment, step S150 includes the following sub-steps: determining the center wavelength of each gas in the gas component information, and determining whether the center wavelength of each gas is discretely distributed; if the center wavelength of the gas is not discretely distributed, obtaining the detection value corresponding to a specific wavelength from the detection information as a key detection parameter; the specific wavelength matches the gas component information.

[0059] Specifically, the center wavelength of each gas in the gas composition information can be determined. Each gas has one and only one center wavelength; for example, the center wavelength of methane gas is 3310 nm. Further, it is determined whether the center wavelengths of each gas are discretely distributed. For example, it is determined whether the difference between the center wavelengths of two gases in the gas composition information is less than a preset difference threshold (e.g., a difference threshold of 200 nm). If the difference between the center wavelengths is less than the difference threshold, then the center wavelengths of the gas are determined not to be discretely distributed; if the difference between the center wavelengths is not less than the difference threshold, then the center wavelengths of the gas are determined to be discretely distributed.

[0060] If the distribution is not discrete, one (or several) specific wavelengths are determined based on the gas composition information, and the matching detection value is obtained from the detection information based on the specific wavelength as the key detection parameter. The embodiments of this application mainly focus on the case where the detection value corresponding to a specific wavelength is used as the key detection parameter.

[0061] In a more specific embodiment, after determining whether the center wavelength of each gas is discretely distributed, the method further includes: if the center wavelength of the gas is discretely distributed, obtaining the detection value corresponding to the center wavelength of each gas from the detection information as a key detection parameter.

[0062] If the center wavelength of the gas is discretely distributed, the detection value corresponding to each center wavelength is obtained from the detection information based on the center wavelength of each gas in the gas component information, and used as the key detection parameter. At this time, the gas concentrations of the two gas types in the gas component information are analyzed separately. The analysis process is similar to the concentration analysis process of a single gas type, except that it is necessary to analyze the target gas concentration of each of the two single gas types.

[0063] S160. The key detection parameters are analyzed according to the preset concentration analysis strategy and the concentration ratio information to obtain the corresponding gas identification results.

[0064] Furthermore, based on the concentration analysis strategy and concentration ratio information, key detection parameters can be analyzed to obtain the corresponding gas identification results.

[0065] In a more specific embodiment, step S160 includes the following sub-steps: performing proportional analysis based on the concentration ratio information and the standard feature vectors corresponding to the gases included in the gas component information in the spectral analysis model to obtain the absorption contribution rate of each gas in the gas component information; obtaining the absorption rate corresponding to each gas based on the key detection parameters and the absorption contribution rate of each gas; analyzing the absorption rate of each gas according to the gas molecule analysis rules in the concentration analysis strategy to obtain the gas molecule density corresponding to each gas; and converting the gas molecule density of each gas according to the conversion formula in the concentration analysis strategy to obtain the concentration value of each gas in the gas component information as the corresponding gas identification result.

[0066] The proportion can be analyzed based on the concentration ratio information and the standard feature vectors corresponding to the gases in the gas component information of the spectral analysis model. For example, if the gas component information includes methane and propane, the standard feature vectors corresponding to methane and propane and the current control strategy can be obtained separately. For example, if a specific wavelength is... λt Then we have: A target(λt) =m 1 •A CH4(λt) + m 2 • A C3H8(λt) ; A CH4(λt) For the standard eigenvectors of methane, and λt The corresponding vector value, A C3H8(λt) For the standard eigenvectors of propane and λt The corresponding vector value, A target(λt) For the mixed gas and λt The corresponding sum vector value.

[0067] Contribution of methane absorption rate in gas composition information Ar CH4 =m 1 •A CH4(λt) / A target(λt) The contribution rate of propane absorption Ar C3H8 =m 2 •A C3H8(λt) / A target(λt) .

[0068] Based on the key detection parameters and the absorption contribution rate of each gas, the absorption rate of each gas is obtained. Multiplying the absorption contribution rate of each gas by the detection value in the key detection parameters yields the corresponding absorption rate. Therefore, the absorption rate of methane in the gas composition information is... AB CH4 =m 1 •A CH4(λt) / A target(λt) •(I / I 0 ) ,in, I The detected light intensity, I 0 The reference light intensity (the light intensity without the target gas). I / I 0 This refers to the detection value among the key detection parameters. The same propane absorption rate... AB C3H8 =m 2 •A C3H8(λt) / A target(λt) •(I / I 0 ) .

[0069] The absorption rate of each gas is analyzed according to the gas molecule analysis rules in the concentration analysis strategy to obtain the gas molecule density corresponding to each gas. The analysis process is the same as that for obtaining the gas molecule density of a single gas type, that is, by applying the formula above... Â Replace with AB CH4 or AB C3H8 Then, perform the corresponding analytical calculations; further, convert the gas molecule density of each gas according to the conversion formula in the concentration analysis strategy to obtain the concentration value of each gas in the gas component information. The process of obtaining the gas concentration value is the same as the process of obtaining the gas concentration value of a single gas type in the above steps, and will not be repeated again. The concentration values ​​of each gas in the obtained gas component information are taken as the final gas identification result.

[0070] This invention also provides an infrared spectral mixed gas identification device, which applies the infrared spectral mixed gas identification method described in the above embodiments to achieve accurate identification of multiple types of gases, such as... Figure 2 and Figure 5As shown, the infrared spectral mixed gas identification device includes a gas detection chamber 1, an infrared light source 2, an infrared narrowband filter 3, a detection component 4, a controller 5, and a control component. The infrared light source 2, the infrared narrowband filter 3, and the detection component 4 are arranged sequentially within the gas detection chamber 1 of the identification device. The gas detection chamber 1 has an elongated structure, with the infrared light source 2 and the detection component 4 respectively located at both ends of the gas detection chamber 1. The side walls of the gas detection chamber 1 are provided with multiple ventilation holes 11. The infrared narrowband filter 3 is fixed to the control component. The controller 5 is communicatively connected to the control component and the detection component 4 to achieve data information transmission.

[0071] Furthermore, a temperature sensor can be installed inside the gas detection chamber, and a controller can be configured to communicate with the temperature sensor inside the gas detection chamber. The temperature sensor can be used to obtain temperature detection values, thereby enabling accurate analysis of the key detection parameters and obtaining more accurate gas identification results.

[0072] Furthermore, a pressure sensor can be installed inside the gas detection chamber, and a controller can be configured to communicate with the pressure sensor inside the gas detection chamber. By obtaining the pressure detection value through the pressure sensor and combining it with the temperature detection value, the key detection parameters can be accurately analyzed to obtain more accurate gas identification results.

[0073] This invention provides a method and device for identifying mixed gases using infrared spectroscopy. The method includes: sending a control command to a control component according to a preset control strategy to adjust an infrared narrowband filter to generate multiple detection beams with different center wavelengths that are incident on a detection component; acquiring the detection values ​​corresponding to each detection beam from the detection component to obtain corresponding detection information; determining whether the detection information is a mixed gas type based on judgment rules, a spectral analysis model, and the control strategy; if it is a mixed gas type, performing multi-component analysis on the detection information according to a multi-component analysis strategy and a spectral analysis model to obtain component analysis information; and obtaining key detection parameters from the detection information based on the component analysis information and performing analysis to obtain the corresponding gas identification result. This identification method, by controlling the control component to adjust the infrared narrowband filter to generate detection beams with different center wavelengths, achieves continuous spectral scanning within a certain wavelength range; if the detection information is determined to be a mixed gas type, multi-component analysis is performed and gas identification results are obtained, enabling reliable analysis of mixed gases with multiple gas components and accurate acquisition of the concentration values ​​of each gas.

[0074] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for identifying infrared spectral mixed gases, characterized in that, The method is applied to the controller of the identification device. The controller is connected to the control component and the detection component to realize the transmission of data information. The infrared light source, the infrared narrowband filter, and the detection component are arranged in sequence in the gas detection cavity of the identification device. The infrared narrowband filter is fixed to the control component, and the method includes: According to the preset control strategy, control commands are sent to the control component to adjust the infrared narrowband filter to generate multiple detection beams with different center wavelengths that enter the detection component. The detection values ​​corresponding to the detection components and each detection beam are obtained to acquire the corresponding detection information. The detection information is determined to be a mixed gas type based on the preset judgment rules, the pre-stored spectral analysis model, and the control strategy. If the detected information is a mixed gas type, the detected information is analyzed in multiple components according to the preset multi-component analysis strategy and the spectral analysis model to obtain the corresponding component analysis information; the component analysis information includes gas component information and concentration ratio information. Based on the gas composition information, obtain the matching key detection parameters from the detection information; The key detection parameters are analyzed based on the preset concentration analysis strategy and the concentration ratio information to obtain the corresponding gas identification results.

2. The infrared spectral mixed gas identification method according to claim 1, characterized in that, The step of determining whether the detected information is a mixed gas type based on preset judgment rules, pre-stored spectral analysis models, and the control strategy includes: According to the normalization processing rule corresponding to the control strategy, each detection value in the detection information is normalized to obtain the corresponding detection feature vector; Calculate the vector space angle between the detected feature vector and the standard feature vector corresponding to each single gas type in the spectral analysis model; Determine whether the smallest vector space angle is less than the vector space angle threshold corresponding to the vector space angle in the determination rule; If the smallest vector space angle is less than the vector space angle threshold, it is determined that the detection information is not a mixed gas type; If the minimum vector space angle is not less than the vector space angle threshold, the detected information is determined to be a mixed gas type.

3. The infrared spectral mixed gas identification method according to claim 2, characterized in that, The step of performing multi-component analysis on the detection information according to the preset multi-component analysis strategy and the spectral analysis model to obtain the corresponding component analysis information includes: Calculate the mixing vector space angle between the detection feature vector corresponding to the detection information and the mixing feature vector corresponding to each mixed gas type in the spectral analysis model; The gas type corresponding to the mixing feature vector with the highest mixing vector space angle is obtained as the corresponding gas component information. Based on the multi-component analysis strategy and the standard feature vectors of the gas types contained in the gas component information in the spectral analysis model, the detection feature vector is analyzed to obtain the corresponding concentration ratio information.

4. The infrared spectral mixed gas identification method according to any one of claims 1-3, characterized in that, The step of obtaining matching key detection parameters from the detection information based on the gas composition information includes: Determine the center wavelength of each gas in the gas component information, and determine whether the center wavelength of each gas is discretely distributed; If the center wavelength of the gas is not discretely distributed, the detection value corresponding to a specific wavelength is obtained from the detection information as a key detection parameter; the specific wavelength matches the gas composition information.

5. The infrared spectral mixed gas identification method according to claim 4, characterized in that, After determining whether the center wavelengths of each gas are discretely distributed, the process further includes: If the center wavelength of the gas is discretely distributed, the detection value corresponding to the center wavelength of each gas is obtained from the detection information as a key detection parameter.

6. The infrared spectral mixed gas identification method according to claim 4, characterized in that, The step of analyzing the key detection parameters according to the preset concentration analysis strategy and the concentration ratio information to obtain the corresponding gas identification result includes: Based on the concentration ratio information and the standard feature vectors corresponding to the gases in the gas component information in the spectral analysis model, the absorption contribution rate of each gas in the gas component information is obtained by performing ratio analysis. Based on the key detection parameters and the absorption contribution rate of each gas, the absorption rate of each gas is obtained respectively. The absorption rate of each gas is analyzed according to the gas molecule analysis rules in the concentration analysis strategy to obtain the gas molecule density corresponding to each gas. The gas molecule density of each gas is converted according to the conversion formula in the concentration analysis strategy to obtain the concentration value of each gas in the gas component information as the corresponding gas identification result.

7. The infrared spectral mixed gas identification method according to claim 6, characterized in that, After determining whether the detected information is a mixed gas type based on preset judgment rules, pre-stored spectral analysis models, and the control strategy, the method further includes: If the detection information is not a mixed gas type, determine the single gas type corresponding to the detection information; Based on the detection information, obtain key detection parameters that match the single gas type; The key detection parameters are analyzed according to a preset concentration analysis strategy to obtain the corresponding gas identification results.

8. The infrared spectral mixed gas identification method according to claim 7, characterized in that, The step of obtaining the detection values ​​corresponding to the detection components and each detection beam to obtain the corresponding detection information includes: Obtain the received intensity of the detection component and each detection beam; Calculate the ratio between the received strength and the transmitted strength to obtain the corresponding strength ratio; The ratio of the intensity ratio to the pre-stored intensity attenuation coefficient of each detection beam is calculated to obtain the detection value corresponding to each detection beam.

9. The infrared spectral mixed gas identification method according to claim 1, characterized in that, The step of sending a control command to the control component according to a preset control strategy to adjust the infrared narrowband filter to generate multiple detection beams with different center wavelengths that enter the detection component includes: The control component is a rotary control component, which adjusts the tilt angle of the infrared narrowband filter according to the control command. Alternatively, the control component may be a heating control component, which adjusts the temperature of the infrared narrowband filter according to the control command.

10. An infrared spectral mixed gas identification device, wherein the infrared spectral mixed gas identification device applies the infrared spectral mixed gas identification method as described in any one of claims 1-9, characterized in that, The infrared spectral mixed gas identification device includes a gas detection cavity, an infrared light source, an infrared narrowband filter, a detection component, a controller, and a control component; The infrared light source, the infrared narrowband filter, and the detection component are arranged sequentially inside the gas detection cavity of the identification device; the gas detection cavity has an elongated structure, with the infrared light source and the detection component respectively located at both ends of the gas detection cavity; multiple ventilation holes are provided on both side walls of the gas detection cavity; the infrared narrowband filter is fixed to the control component; The controller is connected to the control component and the detection component to transmit data information.

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