CN114993944B - A method, device and equipment for co-detection of methane and carbon monoxide - Google Patents

Abstract

The invention provides a co-detection method, device and equipment for methane and carbon monoxide, which mainly solve the problem of carbon monoxide concentration correction when a large amount of gas exists in a coal mine and spectral lines of the gas intersect or overlap adjacent characteristic absorption peaks of carbon monoxide. Firstly, selecting a carbon monoxide absorption peak at a wavelength of 2333.72nm, simultaneously scanning methane absorption peaks at adjacent wavelengths of 2333.63nm and 2333.98nm, and simultaneously obtaining three harmonic signals for component identification; secondly, aiming at the problems of wing line asymmetry and concentration error caused by interference, a corresponding waveform correction method and a corresponding concentration inversion method are provided. The invention not only can realize the judgment of components and the concentration detection with high sensitivity, but also is suitable for the practical use of the concentration detection of complex mixed gas background trace gases such as coal mines and the like.

Description

A method, device and equipment for co-detection of methane and carbon monoxide

Technical Field

The present invention relates to a trace gas multi-component concentration detection technology, especially in the fields of coal mines and electric power, and aims at the cross-interference of components in the background of mixed gas to achieve real-time detection and early warning of the concentration of carbon monoxide, a characteristic gas of coal spontaneous combustion, under the background of high-concentration methane.

Background Art

The advantage of tunable semiconductor laser absorption spectroscopy is that it uses a narrow linewidth laser to output a beam targeting the characteristic absorption peak of the gas to accurately detect the gas to be tested. In the presence of high-concentration gas in coal mines, the carbon monoxide absorption peak in the near-infrared band (1566nm) is easily covered by the spectral lines of high-concentration methane, carbon dioxide and other gases, so there is cross-interference, and it is impossible to accurately detect and warn carbon monoxide, a sign of coal spontaneous combustion.

Shao et al. used the wavelength of 4297.7cm ^-1 CO absorption peak (2326.8nm) to detect carbon monoxide and methane mixed gas. CN202010334381.2 proposed to use the 2330.2nm characteristic absorption peak combined with identification factors such as trough width to achieve simultaneous measurement of carbon monoxide and methane. J.Chen et al. used a 2365nm laser to simultaneously scan multiple absorption peaks of carbon monoxide and methane for the first time to detect methane and carbon monoxide mixed gas. However, none of them effectively solved the problem of methane interference.

Summary of the invention

In order to overcome the deficiencies in the prior art, the inventors have conducted intensive research and provided a method, device and equipment for co-detection of methane and carbon monoxide to address the impact of high-concentration gas on the accuracy of carbon monoxide detection.

The technical solution provided by the present invention is as follows:

In a first aspect, a method for co-detecting methane and carbon monoxide comprises the following steps:

S1, using a tunable laser gas analyzer to scan the characteristic absorption peaks of carbon monoxide and methane, and obtaining the second harmonic curve of the carbon monoxide-methane mixed gas covering the characteristic absorption peaks of carbon monoxide and methane;

S2, performing baseline fitting according to the trough point of the second harmonic curve of the carbon monoxide-methane mixture, and completing the baseline correction of the second harmonic curve by deducting the fitted baseline;

S3, subtract the methane signal from the characteristic harmonic signal of carbon monoxide in the second harmonic curve of the carbon monoxide-methane mixed gas after baseline correction, make component judgment according to the positions of the characteristic harmonic signals of carbon monoxide and methane, perform concentration inversion according to the amplitude of the characteristic harmonic signal, and obtain the gas concentration values of carbon monoxide and methane respectively.

Furthermore, in step S1, the characteristic absorption peak of carbon monoxide is located at a wavelength of 2333.72 nm, and the characteristic absorption peak of methane is located at wavelengths of 2333.63 nm and 2333.98 nm.

Furthermore, in step S2, the baseline fitting method includes linear fitting or nonlinear fitting.

Furthermore, in step S3, the step of subtracting the methane signal from the carbon monoxide characteristic harmonic signal in the second harmonic curve of the carbon monoxide-methane mixed gas after baseline correction is achieved by correcting the inversion coefficient of carbon monoxide, and the specific implementation method is as follows:

S3.1, determine the absorption coefficient α1 of methane at the characteristic absorption peak wavelength of carbon monoxide;

S3.2, select a methane absorption peak that is not interfered by other spectral lines or is far away from the characteristic absorption peak of carbon monoxide, and determine the absorption coefficient α2 of methane at the wavelength of the absorption peak;

S3.3, determine the contribution coefficient M, M = α2/α1;

S3.4, the corrected inversion coefficient of carbon monoxide is: κ _CO =κ-κ _CH4 /M; wherein, κ is the inversion coefficient of carbon monoxide at the characteristic absorption peak wavelength of carbon monoxide without deducting the interference of methane; κ _CH4 is the inversion coefficient of methane at its characteristic absorption peak wavelength; κ _CO is the inversion coefficient of carbon monoxide at the characteristic absorption peak wavelength of carbon monoxide after deducting the interference of methane.

Furthermore, the correction of the carbon monoxide absorption coefficient is implemented in the following manner:

S3.1, determine that the absorption coefficient of methane at the characteristic absorption peak wavelength of carbon monoxide 2333.72nm is 0.008;

S3.2, select the methane absorption peak at 2333.98 nm, and determine that the absorption coefficient of the methane absorption peak at the characteristic absorption peak wavelength is 0.263;

S3.3, determine the contribution coefficient M, M = 32.875;

S3.4, the corrected inversion coefficient of carbon monoxide is: κ _CO =κ-κ _CH4 /32.875.

Furthermore, in step S3, the step of determining the components according to the positions of the characteristic harmonic signals of carbon monoxide and methane is implemented in the following manner:

Determine that the wavelength scanning range covers the characteristic absorption peak wavelength of carbon monoxide 2333.72nm, the characteristic absorption peak wavelengths of methane 2333.63nm and 2333.98nm, and make the second harmonic curve contain only the characteristic harmonic signals of carbon monoxide and methane; the first and third characteristic harmonic signal positions in the second harmonic curve correspond to methane, and the second characteristic harmonic signal position corresponds to carbon monoxide.

Further, in step S3, the amplitude of the characteristic harmonic signal of methane is determined by: searching for the peak and the troughs on both sides of the peak according to the horizontal coordinate of the characteristic harmonic signal of methane, and obtaining the harmonic signal amplitude of the methane absorption peak at 2333.98nm; the amplitude of the characteristic harmonic signal of carbon monoxide is determined by: searching for the peak and the troughs on both sides of the peak according to the horizontal coordinate of the characteristic harmonic signal of carbon monoxide, and obtaining the harmonic signal amplitude of the carbon monoxide absorption peak at 2333.72nm.

In a second aspect, a methane and carbon monoxide detection device comprises:

A receiving module, used for receiving a second harmonic curve of a carbon monoxide-methane mixed gas covering characteristic absorption peaks of carbon monoxide and methane obtained by a tunable laser gas analyzer;

A baseline fitting and baseline correction module is used to perform baseline fitting according to the trough point of the second harmonic curve of the carbon monoxide-methane mixture, and complete the baseline correction of the second harmonic curve by deducting the fitting baseline;

The component identification and concentration measurement module is used to subtract the methane signal from the carbon monoxide characteristic harmonic signal in the second harmonic curve of the carbon monoxide-methane mixed gas after baseline correction, make component judgments based on the positions of the characteristic harmonic signals of carbon monoxide and methane, and perform concentration inversion based on the amplitude of the characteristic harmonic signal to obtain the gas concentration values of carbon monoxide and methane, respectively.

In a third aspect, a methane and carbon monoxide detection device comprises:

one or more processors;

a storage device for storing one or more programs,

The one or more programs are executed by the one or more processors to:

receiving a second harmonic curve of a carbon monoxide-methane mixed gas covering characteristic absorption peaks of carbon monoxide and methane obtained by a tunable laser gas analyzer;

Baseline fitting is performed according to the trough point of the second harmonic curve of the carbon monoxide-methane mixture, and the baseline correction of the second harmonic curve is completed by deducting the fitted baseline;

The methane signal is subtracted from the characteristic harmonic signal of carbon monoxide in the second harmonic curve of the carbon monoxide-methane mixture after baseline correction. The components are judged according to the positions of the characteristic harmonic signals of carbon monoxide and methane. The concentration is inverted according to the amplitude of the characteristic harmonic signal to obtain the gas concentration values of carbon monoxide and methane, respectively.

A method, device and equipment for co-detection of methane and carbon monoxide provided by the present invention has the following beneficial effects:

(1) The present invention provides a method for reducing the interference of high-concentration methane on trace carbon monoxide detection values by using the high-concentration gas conditions in the underground coal mine environment, thereby solving the problem of determining carbon monoxide and methane components and accurately measuring their concentrations in a high-concentration gas environment;

(2) The solution to the problem of spectral line cross-interference in multi-component gas detection provided by the present invention is universal and can be applied not only to applications such as carbon monoxide detection in coal mines, but also to various gas detections involving spectral line cross-interference.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a characteristic absorption spectrum of methane and carbon monoxide gases selected by the present invention for simultaneous measurement;

FIG2 is an uncorrected harmonic signal curve of a methane and carbon monoxide mixed gas;

FIG3 is an interference curve of the methane absorption peak to the carbon monoxide absorption peak;

FIG. 4 is a harmonic signal curve after correction for concentration value calculation according to the present invention.

DETAILED DESCRIPTION

The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

According to a first aspect of the present invention, a method for co-detection of methane and carbon monoxide is provided, comprising the following steps:

S1, using a tunable laser gas analyzer to scan the characteristic absorption peaks of carbon monoxide and methane to obtain a second harmonic curve of a carbon monoxide-methane mixed gas covering the characteristic absorption peaks of carbon monoxide and methane; preferably, the characteristic absorption peak of carbon monoxide is 2333.72nm, and the characteristic absorption peaks of methane are 2333.63nm and 2333.98nm;

S2, performing baseline fitting according to the trough point of the second harmonic curve of the carbon monoxide-methane mixture, and completing the baseline correction of the second harmonic curve by deducting the fitted baseline;

S3, subtract the methane signal from the characteristic harmonic signal of carbon monoxide in the second harmonic curve of the carbon monoxide-methane mixed gas after baseline correction, make component judgment according to the positions of the characteristic harmonic signals of carbon monoxide and methane, perform concentration inversion according to the amplitude of the characteristic harmonic signal, and obtain the gas concentration values of carbon monoxide and methane respectively.

There is high concentration of gas in the underground working environment of coal mines. There are two adjacent methane absorption peaks near the characteristic absorption peak of carbon monoxide at a wavelength of 2333.72nm, which are 2333.63nm and 2333.98nm respectively. However, high concentration of methane gas will lead to inaccurate detection of carbon monoxide concentration value, especially the absorption peak at a wavelength of 2333.63nm has cross interference with the absorption peak of carbon monoxide 2333.72nm. The present invention focuses on solving the problem of cross interference between high concentration of methane and carbon monoxide spectral lines, and reducing the carbon monoxide concentration detection error caused by high gas.

After determining the parameters of the mixed gas spectrum, a signal analysis and processing method is proposed to eliminate the carbon monoxide concentration detection error caused by high concentration of methane, aiming at the problem that the methane absorption peak at a wavelength of 2333.63nm interferes with the carbon monoxide absorption peak at a wavelength of 2333.72nm. The implementation of the technical solution relies on a detection device of tunable semiconductor laser absorption spectroscopy technology (i.e., a tunable laser gas analyzer), including a laser driving module that emits a sawtooth and sine superimposed modulation signal. The modulation signal is tuned by the current or temperature of the laser in order to make the laser wavelength scan multiple absorption lines of the gas to be measured; the laser emits a laser beam (e.g., a wavelength scanning range of 2333.5 to 2334.1 nm, a width of 0.6 nm, covering the methane absorption peaks at 2333.63 nm and 2333.98 nm, and the carbon monoxide absorption peak at 2333.72 nm; the gas characteristic absorption peak fitting curve of the 2333.4 to 2334.2 nm band obtained according to the HITRAN database is shown in FIG1.) and enters the gas chamber, the gas chamber is filled with the gas to be measured, and the absorbed light signal is converted into an electrical signal and enters the digital phase-locked unit, and the second harmonic signal is obtained through the phase-sensitive detection unit. The identification of the components of the gas to be measured is fundamentally based on the different wave numbers of the spectral lines. According to the wave number calibration, the horizontal coordinate positions of the harmonic curves are different, and the components are identified based on the positions; the concentration value of the gas to be measured is obtained by inverting the amplitude of the harmonic signal of the corresponding gas.

The narrow linewidth laser scans the characteristic absorption peak of carbon monoxide at 2333.72nm, as well as the adjacent characteristic absorption peaks of methane at 2333.63nm and 2333.98nm, and simultaneously obtains three characteristic harmonic signals of the two gases, which are used for component identification and concentration detection, respectively. Among them, the first characteristic harmonic signal represents the characteristic absorption peak of methane at a wavelength of 2333.63nm, the second characteristic harmonic signal represents the characteristic absorption peak of carbon monoxide at a wavelength of 2333.72nm, and the third characteristic harmonic signal represents the characteristic absorption peak of methane at a wavelength of 2333.98nm. The measured second harmonic curve shows that the characteristic absorption peak of carbon monoxide at a wavelength of 2332.72nm is interfered by the characteristic absorption peak of methane at a wavelength of 2333.63nm on the left, resulting in asymmetric wing lines and changes in the absorption coefficient, so the obtained carbon monoxide concentration value is inaccurate.

Baseline fitting is performed according to the trough point of the second harmonic curve of the carbon monoxide-methane mixture, and the baseline correction of the second harmonic curve is completed by deducting the fitted baseline. The present invention is not limited to any fitting method, including linear fitting or nonlinear fitting, as long as the baseline obtained by fitting is within the limit. Assuming that nonlinear fitting such as cubic fitting is used, the baseline obtained is:

y ₀ = a + bx + cx ² (1)

Among them, _y0 is the baseline curve; x is the second harmonic, and the horizontal coordinate can be a data point or a wave number.

Update the obtained harmonic curve to:

Y＝yy ₀ (2)

Where Y is the corrected harmonic curve, _y0 is the baseline curve, and y is the measured harmonic curve.

The methane concentration signal is subtracted from the characteristic harmonic signal of carbon monoxide in the harmonic curve after baseline correction. After correction, the harmonic signal wing line is already symmetrical, but considering that high concentration of methane not only affects the symmetry of the wing line of the carbon monoxide spectrum, but also causes changes in its spectral line intensity and width, thereby causing changes in the carbon monoxide absorption coefficient and harmonic signal, as shown in Figure 3. Therefore, not only the line shape is corrected, but also the concentration needs to be corrected. Through research, the inventors have found that the impact on the carbon monoxide concentration detection can be deducted proportionally according to the absorption coefficient of methane. According to the absorption coefficient calculation, the methane absorption coefficient at a wavelength of 2333.98nm is 0.263, and the methane absorption coefficient at a wavelength of 2333.72nm is 0.008, and the contribution multiple is 32.875 times. Determine the inversion coefficient of carbon monoxide after deducting methane interference (the inversion coefficient is a proportional coefficient reflecting the relationship between the harmonic signal amplitude and the concentration value) as follows:

κ _CO =κ-κ _CH4 /32.875 (3)

Wherein, κ is the inversion coefficient of carbon monoxide at a wavelength of 2333.72 nm without deducting the interference of methane; κ _CH4 is the inversion coefficient of methane at its characteristic absorption peak wavelength of 2333.98 nm; κ _CO is the inversion coefficient of carbon monoxide at a wavelength of 2333.72 nm after deducting the interference of methane, and κ _CH4 /32.875 corresponds to the interference of methane on carbon monoxide at a wavelength of 2333.72 nm.

Of course, in addition to using the methane absorption coefficient at 2333.98 nm to determine the contribution multiple, the absorption coefficient of methane at other absorption peak wavelengths can also be used. Therefore, the implementation method of proportionally deducting the influence of the methane absorption coefficient on carbon monoxide is summarized as follows:

Determine the absorption coefficient α1 of methane at the characteristic absorption peak wavelength of carbon monoxide;

Select a methane absorption peak that is not interfered by other spectral lines or is far away from the characteristic absorption peak of carbon monoxide, and determine the absorption coefficient α2 of methane at the wavelength of the absorption peak;

Determine the contribution coefficient M, M = α2/α1;

The corrected inversion coefficient of carbon monoxide is: κ _CO =κ-κ _CH4 /M; wherein, κ is the inversion coefficient of CO at the characteristic absorption peak wavelength of carbon monoxide without deducting the interference of methane; κ _CH4 is the inversion coefficient of methane at its characteristic absorption peak wavelength; κ _CO is the inversion coefficient of CO at the characteristic absorption peak wavelength of carbon monoxide after deducting the interference of methane, and κ _CH4 /32.875 corresponds to the interference of methane on the inversion coefficient of carbon monoxide at the characteristic absorption peak wavelength of carbon monoxide.

After completing the baseline correction, the components are judged according to the positions of the characteristic harmonic signals of carbon monoxide and methane. According to the position of the methane characteristic harmonic signal on the horizontal axis, the peaks and troughs are searched within a limited range to obtain the harmonic signal amplitude of the 2333.98nm methane absorption peak, and the methane concentration value is obtained by inverting the calibration data. The peak and trough values are searched within the limited horizontal axis range to obtain the 2333.72nm carbon monoxide characteristic harmonic signal amplitude, and the carbon monoxide concentration value is deduced. The inversion coefficient of the carbon monoxide concentration is the inversion coefficient minus the methane concentration. The present invention is not limited to any concentration inversion method, but the methane and carbon monoxide concentration detection methods that obtain the corrected harmonic signal of the band by harmonic inversion are within the scope of the present invention. The step of judging the components according to the positions of the characteristic harmonic signals of carbon monoxide and methane is implemented in the following manner: determining that the wavelength scanning range covers the characteristic absorption peak of carbon monoxide 2333.72nm and the characteristic absorption peaks of methane 2333.63nm and 2333.98nm, so that the second harmonic curve only contains the characteristic harmonic signals of carbon monoxide and methane; the first and third characteristic harmonic signal positions in the second harmonic curve correspond to methane, and the second characteristic harmonic signal position corresponds to carbon monoxide, as shown in FIG2 .

According to the method proposed in the present invention, the calibrated harmonic curves of carbon monoxide and methane are shown in FIG4 . Tests have shown that after correction, accurate measurement of carbon monoxide in a mixed gas with a methane background of high concentration of 0.5% or more can be achieved, and the detection limit is 5 ppm.

According to a second aspect of the present invention, there is provided a device for detecting methane and carbon monoxide, comprising:

A receiving module, used for receiving a second harmonic curve of a carbon monoxide-methane mixed gas covering characteristic absorption peaks of carbon monoxide and methane obtained by a tunable laser gas analyzer;

A baseline fitting and baseline correction module is used to perform baseline fitting according to the trough point of the second harmonic curve of the carbon monoxide-methane mixture, and complete the baseline correction of the second harmonic curve by deducting the fitting baseline;

The component identification and concentration measurement module is used to subtract the methane signal from the carbon monoxide characteristic harmonic signal in the second harmonic curve of the carbon monoxide-methane mixed gas after baseline correction, make component judgments based on the positions of the characteristic harmonic signals of carbon monoxide and methane, and perform concentration inversion based on the amplitude of the characteristic harmonic signal to obtain the gas concentration values of carbon monoxide and methane, respectively.

According to a third aspect of the present invention, there is provided a methane and carbon monoxide detection device, comprising:

one or more processors;

a storage device for storing one or more programs,

The one or more programs are executed by the one or more processors to:

receiving a second harmonic curve of a carbon monoxide-methane mixed gas covering characteristic absorption peaks of carbon monoxide and methane obtained by a tunable laser gas analyzer;

Baseline fitting is performed according to the trough point of the second harmonic curve of the carbon monoxide-methane mixture, and the baseline correction of the second harmonic curve is completed by deducting the fitted baseline;

The methane signal is subtracted from the characteristic harmonic signal of carbon monoxide in the second harmonic curve of the carbon monoxide-methane mixture after baseline correction. The components are judged according to the positions of the characteristic harmonic signals of carbon monoxide and methane. The concentration is inverted according to the amplitude of the characteristic harmonic signal to obtain the gas concentration values of carbon monoxide and methane, respectively.

Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and equipment can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

In the embodiments provided in the present application, it should be understood that the provided devices and equipment can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the modules is only a logical function division, and there may be other division methods in actual implementation. In addition, each functional unit in the relevant embodiments of the present application can be integrated in a processing unit, or each functional unit can exist physically separately, or two or more functional units can be integrated in a processing unit. The above-mentioned integrated functional units can be implemented in the form of hardware or in the form of software functional units.

If the integrated functional unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

Those skilled in the art will appreciate that in one or more of the above examples, the functions described in the present invention may be implemented in hardware, software, firmware, or any combination thereof. When implemented using software, the functions may be stored in a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein communication media include any media that facilitates the transmission of a computer program from one place to another. The storage medium may be any available medium that a general or special-purpose computer can access.

The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims (9)

1. A method for co-detecting methane and carbon monoxide, comprising the steps of:

s1, scanning characteristic absorption peaks of carbon monoxide and methane by using a tunable laser gas analyzer to obtain a second harmonic curve of carbon monoxide-methane mixed gas covering the characteristic absorption peaks of the carbon monoxide and the methane;

s2, performing baseline fitting according to trough points of a carbon monoxide-methane mixture second harmonic curve, and completing second harmonic curve baseline correction by deducting the fitting baseline;

S3, subtracting methane signals from carbon monoxide characteristic harmonic signals in a second harmonic curve of the carbon monoxide-methane mixed gas after baseline correction, judging components according to the positions of the carbon monoxide and methane characteristic harmonic signals, inverting the concentration according to the amplitude of the characteristic harmonic signals, and respectively obtaining gas concentration values of the carbon monoxide and the methane;

The step of subtracting the methane signal from the carbon monoxide characteristic harmonic signal in the second harmonic curve of the carbon monoxide-methane mixture after baseline correction is realized by correcting the inversion coefficient of carbon monoxide, and the specific implementation mode is as follows:

S3.1, determining an absorption coefficient alpha 1 of methane at a characteristic absorption peak wavelength of carbon monoxide;

s3.2, selecting a methane absorption peak which is not interfered by other spectral lines or is far away from a carbon monoxide characteristic absorption peak, and determining an absorption coefficient alpha 2 of methane at the wavelength of the absorption peak;

s3.3, determining a contribution coefficient M, m=α2/α1;

S3.4, the inversion coefficient of the corrected carbon monoxide is as follows: kappa _CO＝κ-κ_CH4/M; wherein, κ is the inversion coefficient of carbon monoxide under the characteristic absorption peak wavelength of carbon monoxide without deducting methane interference; kappa _CH4 is the inversion coefficient of methane at its characteristic absorption peak wavelength; kappa _CO is the inverse coefficient of carbon monoxide at the characteristic absorption peak wavelength of carbon monoxide with methane interference subtracted.

2. The method for co-detection of methane and carbon monoxide according to claim 1, wherein in step S1, the characteristic absorption peak of carbon monoxide is at 2333.72nm and the characteristic absorption peak of methane is at 2333.63nm and 2333.98 nm.

3. The method for co-detection of methane and carbon monoxide according to claim 1, wherein in step S2, the method for baseline fitting comprises linear fitting or nonlinear fitting.

4. The co-detection method of methane and carbon monoxide according to claim 1, wherein the correction of the absorption coefficient of carbon monoxide is performed by:

s3.1, determining that the absorption coefficient of methane at the characteristic absorption peak wavelength 2333.72nm of carbon monoxide is 0.008;

S3.2, selecting a methane absorption peak at 2333.98nm, and determining that the absorption coefficient of methane at the characteristic absorption peak wavelength is 0.263;

s3.3, determining a contribution coefficient M, m= 32.875;

s3.4, the inversion coefficient of the corrected carbon monoxide is as follows: kappa _CO＝κ-κ_CH4/32.875.

5. The method for co-detecting methane and carbon monoxide according to claim 1, wherein in step S3, the step of determining the composition according to the characteristic harmonic signal positions of carbon monoxide and methane is performed by:

Determining characteristic harmonic signals of which the wavelength scanning range covers the characteristic absorption peak wavelengths 2333.72nm of carbon monoxide and the characteristic absorption peak wavelengths 2333.63nm and 2333.98nm of methane and enabling a second harmonic curve to only contain the carbon monoxide and the methane; the first and third characteristic harmonic signal positions in the second harmonic curve correspond to methane, and the second characteristic harmonic signal position corresponds to carbon monoxide.

6. The method for co-detection of methane and carbon monoxide according to claim 1, wherein in step S3, the characteristic harmonic signal amplitude of methane is determined by: searching wave crests and wave troughs on two sides of the wave crests according to the abscissa where the methane characteristic harmonic signals are located, and obtaining harmonic signal amplitude values of methane absorption peaks at 2333.98 nm.

7. The method for co-detection of methane and carbon monoxide according to claim 1, wherein in step S3, the characteristic harmonic signal amplitude of carbon monoxide is determined by: searching the wave crest and the wave troughs at the two sides of the wave crest according to the abscissa where the carbon monoxide characteristic harmonic signal is located, and obtaining the harmonic signal amplitude of the carbon monoxide absorption peak at 2333.72 nm.

8. A methane and carbon monoxide detection device, comprising:

the receiving module is used for receiving the second harmonic curve of the carbon monoxide-methane mixed gas which is obtained by the tunable laser gas analyzer and covers the characteristic absorption peaks of the carbon monoxide and the methane;

The baseline fitting and baseline correction module is used for carrying out baseline fitting according to trough points of the carbon monoxide-methane mixture second harmonic curve and completing the second harmonic curve baseline correction by deducting the fitting baseline;

The component identification and concentration determination module is used for deducting the methane signal from the carbon monoxide characteristic harmonic signal in the second harmonic curve of the carbon monoxide-methane mixed gas after baseline correction, judging the components according to the positions of the carbon monoxide and methane characteristic harmonic signals, inverting the concentration according to the amplitude of the characteristic harmonic signal, and respectively obtaining the gas concentration values of the carbon monoxide and the methane;

the method is characterized in that methane signal deduction is carried out on carbon monoxide characteristic harmonic signals in a carbon monoxide-methane mixed gas second harmonic curve after baseline correction, and the method is realized by correcting inversion coefficients of carbon monoxide, and the specific implementation mode is as follows:

S3.1, determining an absorption coefficient alpha 1 of methane at a characteristic absorption peak wavelength of carbon monoxide;

s3.2, selecting a methane absorption peak which is not interfered by other spectral lines or is far away from a carbon monoxide characteristic absorption peak, and determining an absorption coefficient alpha 2 of methane at the wavelength of the absorption peak;

s3.3, determining a contribution coefficient M, m=α2/α1;

S3.4, the inversion coefficient of the corrected carbon monoxide is as follows: kappa _CO＝κ-κ_CH4/M; wherein, κ is the inversion coefficient of carbon monoxide under the characteristic absorption peak wavelength of carbon monoxide without deducting methane interference; kappa _CH4 is the inversion coefficient of methane at its characteristic absorption peak wavelength; kappa _CO is the inverse coefficient of carbon monoxide at the characteristic absorption peak wavelength of carbon monoxide with methane interference subtracted.

9. A methane and carbon monoxide detection apparatus comprising:

one or more processors;

storage means for storing one or more programs,

The one or more programs are executed by the one or more processors for:

receiving a second harmonic curve of the carbon monoxide-methane mixed gas which is obtained by the tunable laser gas analyzer and covers characteristic absorption peaks of carbon monoxide and methane;

performing baseline fitting according to trough points of a carbon monoxide-methane mixed gas second harmonic curve, and completing second harmonic curve baseline correction by deducting the fitting baseline;

Performing methane signal deduction on a carbon monoxide characteristic harmonic signal in a carbon monoxide-methane mixed gas second harmonic curve after baseline correction, performing component judgment according to the characteristic harmonic signal positions of carbon monoxide and methane, performing concentration inversion according to the characteristic harmonic signal amplitude value, and respectively obtaining gas concentration values of carbon monoxide and methane;

the method is characterized in that methane signal deduction is carried out on carbon monoxide characteristic harmonic signals in a carbon monoxide-methane mixed gas second harmonic curve after baseline correction, and the method is realized by correcting inversion coefficients of carbon monoxide, and the specific implementation mode is as follows:

S3.1, determining an absorption coefficient alpha 1 of methane at a characteristic absorption peak wavelength of carbon monoxide;

s3.2, selecting a methane absorption peak which is not interfered by other spectral lines or is far away from a carbon monoxide characteristic absorption peak, and determining an absorption coefficient alpha 2 of methane at the wavelength of the absorption peak;

s3.3, determining a contribution coefficient M, m=α2/α1;

S3.4, the inversion coefficient of the corrected carbon monoxide is as follows: kappa _CO＝κ-κ_CH4/M; wherein, κ is the inversion coefficient of carbon monoxide under the characteristic absorption peak wavelength of carbon monoxide without deducting methane interference; kappa _CH4 is the inversion coefficient of methane at its characteristic absorption peak wavelength; kappa _CO is the inverse coefficient of carbon monoxide at the characteristic absorption peak wavelength of carbon monoxide with methane interference subtracted.