Gas analysis device based on discrete optical cell group and gas analysis method thereof

Abstract

The present invention provides a gas analysis device based on a discrete optical cell group and a gas analysis method thereof, comprising: a broadband light source, emitting a light beam covering the absorption spectrum of a multi-component gas; which may be an ultraviolet light source or an infrared light source; a multi-faceted reflection cone, used to reflect the light beam emitted by the broadband light source; a discrete optical cell group, comprising a combination of N discrete optical cells with different reflection optical paths, one of which is a reference optical cell; and a detector group, which is a photoelectric detector with lenses with different wavelength cutoffs. The present invention innovatively uses a multi-faceted reflection cone to evenly split the light beam of the broadband light source, and injects it into a combined gas cell composed of a plurality of discrete optical cells, thereby realizing a highly integrated multi-component gas monitoring device; at the same time, a multi-component gas analysis method based on a discrete optical cell group is proposed, which realizes multi-component gas monitoring in a wide concentration range without cross-interference by constructing multiple gas analysis models and establishing a calibration matrix through a principal component analysis algorithm.

Description

Technical Field

[0001] The present invention relates to the technical field of gas analysis, and in particular to a gas analysis device based on a discrete optical cell group and a gas analysis method thereof. Background Art

[0002] The vibration and rotation frequencies of gas molecules correspond to the characteristic absorption wavelengths of the gas, such as the greenhouse gas CO 2 , corresponding to a strong absorption band near 4.26um; toxic and harmful gas hydrogen sulfide (H 2 S), corresponding to a strong absorption band near 2.6um; nitrogen oxides (NO 2 ) and sulfur dioxide (SO 2 ), corresponding to a strong absorption band near 220nm. Since the characteristic spectra of most gases are located in the ultraviolet band (200-300nm), near infrared band (1.3~1.6um), mid-infrared band (3-5um) and long wave band (8-14um), molecular spectroscopy detection technology is widely used in environmental monitoring, industrial process control, toxic and hazardous leakage alarm and other fields.

[0003] Commonly used gas monitoring technologies such as ultraviolet spectroscopy and infrared spectroscopy often face the following problems when measuring multi-component gases:

[0004] 1) Interference between the measured gas components or background gas;

[0005] 2) The gas pool is single, and the absorption intensity of different gases in the spectral segment is inconsistent, which meets the detection sensitivity of one or two measured gases and cannot guarantee the detection accuracy of other component gases;

[0006] Traditional non-dispersive infrared uses a mechanical chopper wheel to switch filters to select different gas absorption bands. This method has mechanical moving parts and requires frequent maintenance. When monitoring multi-component gases, multiple module combinations or multiple devices are required, which is costly.

[0007] Ultraviolet spectroscopy technologies such as DUV and UV-DOAS use absorption characteristic differentials to deal with interference between the measured gas and the background gas, but they cannot completely eliminate the interference. When measuring multi-component gases at the same time, they also face the same problems as non-dispersive infrared. Summary of the invention

[0008] The object of the present invention is to provide a gas analysis device based on a discrete optical cell group and a gas analysis method thereof to solve the problems raised in the above background technology.

[0009] To achieve the above object, the present invention provides the following technical solution: a gas analysis device based on a discrete optical cell group, comprising:

[0010] A broadband light source, used to emit a light beam covering the absorption spectrum of multi-component gases; it can be an ultraviolet light source or an infrared light source;

[0011] A multi-faceted reflection cone for reflecting the light beam emitted by a broadband light source;

[0012] A discrete optical cell set, comprising a combination of N discrete optical cells with different reflection optical path lengths, one of which is a reference optical cell;

[0013] Detector group, photoelectric detector with lenses and cut-off films of different wavelength bands.

[0014] Furthermore, the broadband light source is located in the cavity of the discrete optical pool group and on the central axis of the multi-faceted emitting cone; the divergent light beam emitted by it can be evenly distributed on the reflecting surface of the multi-faceted reflecting cone; the distance between the broadband light source and the multi-faceted reflecting cone is controlled within 1 cm, so that the diameter of the light spot formed on the reflecting surface of the multi-faceted reflecting cone is controlled within 5 to 8 mm.

[0015] Furthermore, the multi-faceted reflection cone can be triangular, four-sided, or multi-faceted, and can be designed according to the type of gas to be measured and the background gas interference. The reflective surface of the multi-faceted reflection cone can be coated with an ultraviolet enhancement film or an infrared reflective film depending on the light source.

[0016] Further, a discrete optical cell group, several independent optical cells designed around a multi-faceted reflection cone;

[0017] The light beam is incident into each independent optical pool through the reflection surface of the multi-faceted reflection cone without affecting each other;

[0018] The optical pool is composed of two plane mirrors, or a plurality of plane mirror groups, or a plane mirror-concave reflector, or a combination of two concave reflectors, which can form multiple reflections, and the reflection optical path can be designed within 15cm to 3.2m;

[0019] The incident light beam is reflected multiple times in the optical pool and finally converged to the photodetector through a filter lens with wavelength cutoff;

[0020] The discrete optical cell group includes a reference optical cell, which is mainly used to eliminate the measurement deviation caused by light source fluctuation and attenuation or the absorption deviation caused by strong background gas.

[0021] Furthermore, the detector groups are distributed on the bottom plate of the discrete optical pool group, and each detector can be adjusted in three dimensions.

[0022] The above-mentioned gas analysis device based on the discrete optical cell group can realize the simultaneous measurement of N-1 gases, each discrete optical cell corresponds to a measured gas, and the gas analysis method thereof comprises the following steps:

[0023] S1. Establish multiple gas analysis models, introduce different concentrations and different types of gas to be measured into the analysis device in turn, obtain the unit absorption signal collection of the gas to be measured in N-1 independent discrete optical cells, divide the absorption signal in each independent discrete optical cell by the signal in the reference optical cell, and obtain the differential absorption signal; construct a mapping relationship according to the differential absorption signals corresponding to different types of gases and different concentrations, and establish multiple gas analysis models;

[0024] S2. Establish a calibration matrix for the measured gas under the corresponding working conditions, estimate the measuring range of the measured gas under different working conditions, and introduce different types of measured gases with measuring range concentrations. Based on the gas analysis model established in S1, obtain the calibration matrix for the measured gas under the corresponding working conditions.

[0025] S3, the concentration of the measured gas is calculated, and the differential absorption signal of the mixed superposition of different measured gases in N-1 independent discrete optical cells is obtained. Based on the gas analysis model established in S1 and the measured gas calibration matrix obtained in S2, the concentration of different types of measured gases can be further calculated based on the principal component analysis algorithm.

[0026] Furthermore, the unit absorption signals of different measured gases in step S1 can be expressed as:

[0027]

[0028] Among them, σ gas_q is the qth gas, n p,k The wavelength of the gas being measured is λ p,k Unit absorption; λ p,k is the interval corresponding to the bandwidth film system; k is the number of equally divided points in the ultraviolet band or infrared band, that is, For example, in the ultraviolet band of 190-280nm, Δλ=0.3nm, in the near-infrared band of 1300-1650nm, Δλ=0.2nm, in the mid-infrared band of 2.3μm-7.8μm, Δλ=0.4nm; p,q∈[1,N-1].

[0029] When the gas analysis device measures multiple groups of gases, the signals corresponding to each discrete optical cell are A 1 ,A 2 ,A 3 …,A N-1 ,A N .

[0030] Furthermore, the differential absorption signal calculation method in step S1 is:

[0031]

[0032] The Nth discrete optical cell is defined as the reference optical cell, A N, A p The signals corresponding to the Nth and Pth discrete optical cells, L N , L p They correspond to the effective optical path lengths of the Nth and Pth discrete optical cells respectively.

[0033] Furthermore, the calibration matrix in step S2 is:

[0034]

[0035] Among them, Z f,e is the calibration coefficient of the measured gas in different discrete optical cells, f,e∈[1,N-1].

[0036] Furthermore, the differential absorption signal of the mixed superposition of different measured gases in the N-1 independent discrete optical cells in step S3 can be expressed as:

[0037]

[0038] where γ p is the concentration of the gas being measured.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention innovatively uses a multi-faceted reflection cone to evenly split the light beam of a broadband light source, and then injects it into a combined gas pool composed of multiple discrete optical cells, thereby realizing a highly integrated multi-component gas monitoring device. At the same time, a multi-component gas analysis method based on a discrete optical cell group is proposed, which realizes multi-component gas monitoring in a wide concentration range without cross-interference by constructing multiple gas analysis models and establishing a calibration matrix through the principal component analysis algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the structure of the gas analysis device of the present invention;

[0042] Figure 2 Schematic diagram of the broadband light source and detector group distributed on the bottom plate of the discrete optical cell group corresponding to the three types of multi-faceted reflection cones.

[0043] Illustration: 1. Broadband light source; 2. Detector group; 3. Discrete optical cell; 4. Multi-faceted reflection cone. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with the accompanying drawings.

[0045] like Figure 1 As shown, a gas analysis device based on a discrete optical cell group comprises:

[0046] A broadband light source 1, used for emitting a light beam covering the absorption spectrum of multi-component gases; it can be an ultraviolet light source or an infrared light source;

[0047] A multi-faceted reflection cone 4, used for reflecting the light beam emitted by the broadband light source 1;

[0048] A discrete optical cell set, including a combination of N discrete optical cells 3 with different reflection optical path lengths, one of which is a reference optical cell;

[0049] Detector group 2, a photoelectric detector having lenses with cut-off films of different wavelength bands.

[0050] Furthermore, the broadband light source 1 is located in the cavity of the discrete optical pool group and on the central axis of the multi-faceted emitting cone 4; the divergent light beam emitted by it can be evenly distributed on the reflecting surface of the multi-faceted reflecting cone 4; the distance between the broadband light source 1 and the multi-faceted reflecting cone 4 is controlled within 1 cm, so that the diameter of the light spot formed on the reflecting surface of the multi-faceted reflecting cone 4 is controlled within 5 to 8 mm.

[0051] Furthermore, the multi-faceted reflection cone 4 can be triangular, quadrangular, or multi-faceted, and can be designed according to the type of gas being measured and the background gas interference. The reflection surface of the multi-faceted reflection cone 4 can be coated with an ultraviolet enhancement film or an infrared reflection film depending on the light source.

[0052] Further, a discrete optical pool group, a plurality of independent optical pools designed around the multi-faceted reflection cone 4;

[0053] The light beams are incident on each independent optical pool through the reflection surface of the multi-faceted reflection cone 4 without affecting each other;

[0054] The optical pool is composed of two plane mirrors, or a plurality of plane mirror groups, or a plane mirror-concave reflector, or a combination of two concave reflectors, which can form multiple reflections, and the reflection optical path can be designed within 15cm to 3.2m;

[0055] The incident light beam is reflected multiple times in the optical pool and finally converged to the photodetector through a filter lens with wavelength cutoff;

[0056] The discrete optical cell group includes a reference optical cell, which is mainly used to eliminate the measurement deviation caused by light source fluctuation and attenuation or the absorption deviation caused by strong background gas.

[0057] Furthermore, the detector group 2 is distributed on the bottom plate of the discrete optical pool group, and each detector can be adjusted in three dimensions. Figure 2 As shown, it is a schematic diagram of the broadband light source and detector group distributed on the bottom plate of the discrete optical pool group corresponding to the three types of multi-faceted reflection cones.

[0058] The above-mentioned gas analysis device based on the discrete optical cell group can realize the simultaneous measurement of N-1 gases, each discrete optical cell corresponds to a measured gas, and the gas analysis method thereof comprises the following steps:

[0059] S1. Establish multiple gas analysis models, introduce different concentrations and different types of gas to be measured into the analysis device in turn, obtain the unit absorption signal collection of the gas to be measured in N-1 independent discrete optical cells, divide the absorption signal in each independent discrete optical cell by the signal in the reference optical cell, and obtain the differential absorption signal; construct a mapping relationship according to the differential absorption signals corresponding to different types of gases and different concentrations, and establish multiple gas analysis models;

[0060] S2. Establish a calibration matrix for the measured gas under the corresponding working conditions, estimate the measuring range of the measured gas under different working conditions, and introduce different types of measured gases with measuring range concentrations. Based on the gas analysis model established in S1, obtain the calibration matrix for the measured gas under the corresponding working conditions.

[0061] S3, the concentration of the measured gas is calculated, and the differential absorption signal of the mixed superposition of different measured gases in N-1 independent discrete optical cells is obtained. Based on the gas analysis model established in S1 and the measured gas calibration matrix obtained in S2, the concentration of different types of measured gases can be further calculated based on the principal component analysis algorithm.

[0062] Furthermore, the unit absorption signals of different measured gases in step S1 can be expressed as:

[0063]

[0064] Among them, σ gas_q is the qth gas, n p,k The wavelength of the gas being measured is λ p,k Unit absorption; λ p,k is the interval corresponding to the bandwidth film system; k is the number of equally divided points in the ultraviolet band or infrared band, that is, For example, in the ultraviolet band of 190-280nm, Δλ=0.3nm, in the near-infrared band of 1300-1650nm, Δλ=0.2nm, in the mid-infrared band of 2.3μm-7.8μm, Δλ=0.4nm; p,q∈[1,N-1].

[0065] When the gas analysis device measures multiple groups of gases, the signals corresponding to each discrete optical cell are A 1 ,A 2 ,A 3 …,A N-1 ,A N .

[0066] Furthermore, the differential absorption signal calculation method in step S1 is:

[0067]

[0068] The Nth discrete optical cell is defined as the reference optical cell, A N , A p The signals corresponding to the Nth and Pth discrete optical cells, L N , L p They correspond to the effective optical path lengths of the Nth and Pth discrete optical cells respectively.

[0069] Furthermore, the calibration matrix in step S2 is:

[0070]

[0071] Among them, Z f,e is the calibration coefficient of the measured gas in different discrete optical cells, f,e∈[1,N-1].

[0072] Furthermore, the differential absorption signal of the mixed superposition of different measured gases in the N-1 independent discrete optical cells in step S3 can be expressed as:

[0073]

[0074] where γ p is the concentration of the gas being measured.

[0075] The above only expresses the preferred embodiments of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, several modifications, improvements and substitutions can be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A gas analysis method based on a discrete optical cell group, the gas analysis method is implemented by a gas analysis device, Features: The gas analysis method comprises the following steps: S1. Establish multiple gas analysis models, introduce different concentrations and different types of gas to be measured into the analysis device in turn, obtain the unit absorption signal collection of the gas to be measured in N-1 independent discrete optical cells, divide the absorption signal in each independent discrete optical cell by the signal in the reference optical cell, and obtain the differential absorption signal; construct a mapping relationship according to the differential absorption signals corresponding to different types of gases and different concentrations, and establish multiple gas analysis models; S2. Establish a calibration matrix for the measured gas under the corresponding working conditions, estimate the measuring range of the measured gas under different working conditions, and introduce different types of measured gases with measuring range concentrations. Based on the gas analysis model established in S1, obtain the calibration matrix for the measured gas under the corresponding working conditions. S3, calculation of the concentration of the measured gas, obtaining the differential absorption signals of the mixed superposition of different measured gases in N-1 independent discrete optical cells, based on the gas analysis model established in S1 and the measured gas calibration matrix obtained in S2, based on the principal component analysis algorithm, the concentrations of different types of measured gases can be further calculated; The gas analysis device includes: A broadband light source, used to emit a light beam covering the absorption spectrum of multi-component gases; it can be an ultraviolet light source or an infrared light source; A multi-faceted reflection cone for reflecting the light beam emitted by a broadband light source; A discrete optical cell group, comprising N independent discrete optical cells, one of which is a reference optical cell; Detector group, photoelectric detector with lenses and cut-off films of different wavelength bands.

2. A gas analysis method based on a discrete optical cell group according to claim 1, Features: The broadband light source is located in the cavity of the discrete optical cell group and is located at the central axis of the multi-faceted reflection cone; The divergent light beam emitted by it can be evenly distributed on the reflection surface of the multi-faceted reflection cone; the distance between the broadband light source and the multi-faceted reflection cone is controlled within 1 cm, so that the diameter of the light spot formed on the reflection surface of the multi-faceted reflection cone is controlled within 5-8 mm.

3. A gas analysis method based on a discrete optical cell group according to claim 1, Features: The multi-faceted reflection cone can be triangular, four-sided, or multi-faceted, and can be designed according to the type of gas to be measured and the background gas interference. The reflection surface of the multi-faceted reflection cone can be coated with an ultraviolet enhancement film or an infrared reflection film depending on the light source.

4. A gas analysis method based on a discrete optical cell group according to claim 1, Features: The discrete optical pool group comprises several independent optical pools designed around a multi-faceted reflective cone; The light beam is incident into each independent optical pool through the reflection surface of the multi-faceted reflection cone without affecting each other; The optical pool is composed of two plane mirrors, or a plurality of plane mirror groups, or a plane mirror-concave reflector, or a combination of two concave reflectors, which can form multiple reflections, and the reflection optical path can be designed within 15cm to 3.2m; The incident light beam is reflected multiple times in the optical pool and finally converged to the photodetector through a filter lens with wavelength cutoff; The discrete optical cell group includes a reference optical cell, which is mainly used to eliminate the measurement deviation caused by light source fluctuation and attenuation or the absorption deviation caused by strong background gas.

5. A gas analysis method based on a discrete optical cell group according to claim 1, Features: The detector group is distributed on the bottom plate of the discrete optical pool group, and each detector can be adjusted in three dimensions.

6. A gas analysis method based on a discrete optical cell group according to claim 1, Features: The unit absorption signals of different gases under test in step S1 can be expressed as: Among them, σ q is the qth gas, n p,k The wavelength of the gas being measured is λ p,k Unit absorption; λ p,k is the interval corresponding to the bandwidth film system; k is the number of equally divided points in the ultraviolet band or infrared band, p,q∈[1,N-1].

7. A gas analysis method based on a discrete optical cell group according to claim 6, Features: The differential absorption signal calculation method in step S1 is: The Nth discrete optical cell is defined as the reference optical cell, A N , A p The signals corresponding to the Nth and Pth discrete optical cells, L N , L p They correspond to the effective optical path lengths of the Nth and Pth discrete optical cells respectively.

8. A gas analysis method based on a discrete optical cell group according to claim 7, Features: The calibration matrix in step S2 is: Among them, Z f,e is the calibration coefficient of the measured gas in different discrete optical cells, f,e∈[1,N-1].

9. A gas analysis method based on a discrete optical cell group according to claim 8, Features: The differential absorption signal of the mixed superposition of different gases to be measured in the N-1 independent discrete optical cells in step S3 can be expressed as: where γ p is the concentration of the gas being measured.

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