Industrial park gas leakage positioning laser on-line monitoring method and light path structure

Abstract

The invention relates to the technical field of gas leakage monitoring, and discloses an industrial park gas leakage positioning laser on-line monitoring method, which comprises the following steps of: 1, superposing a sawtooth wave signal generated by a scanning signal generation circuit on a driving current generated by a current control circuit, periodic scanning of the output wavelength of the semiconductor laser is realized, and the output wavelength covers the absorption spectral line of the target gas; 2, light beams output by the semiconductor laser are divided into two paths through an optical fiber beam splitter, the light power ratio is 1: 9, and the low-power path penetrates through the calibration pool to obtain a calibration spectrum signal; according to the industrial park gas leakage positioning laser on-line monitoring method provided by the invention, an infrared laser spectrum open type long optical path detection technology and a multi-optical path gas two-dimensional distribution inversion algorithm are combined to obtain horizontal plane two-dimensional distribution data of target gas concentration above the area, and reliable indication of gas leakage positioning can be provided.

Description

Technical Field

[0001] The present invention relates to the technical field of gas leakage monitoring, and in particular to a laser online monitoring method and an optical path structure for positioning gas leakage in an industrial park. Background Art

[0002] Gas leakage prevention and early warning in industrial parks is an important part of the current production process, which is related to safety, dual carbon standards, and environmental protection. Especially in chemical parks, my country is a major chemical industry country, and its output value accounts for more than half of the world's total. Due to the complex production process and harsh conditions in the chemical industry, which involves flammable, explosive, toxic and harmful dangerous chemicals and industrial gas leakage, high-consequence accidents are very likely to occur, causing serious damage to people's lives and property. Rapid discovery and precise positioning of gas leaks are of great significance to protecting personnel and environmental safety and preventing major safety accidents.

[0003] Traditional gas detection sensors are contact-type measurements with high sensitivity and measurement accuracy. However, gas leakage monitoring in industrial parks often requires the deployment of a large number of sensors at each potential leakage point in the area, which is time-consuming and labor-intensive, and there is a high risk of sensor failure and false alarms. In addition, practice has shown that single-point detector detection is easily affected by wind direction environmental factors, making it difficult to quickly locate the source of leakage or predict the situation at the leakage site, and the detection efficiency is low. The optical and spectroscopic monitoring method belongs to non-contact measurement, which uses the fingerprint spectral characteristics of the gas to perform high-sensitivity and high-resolution online measurement of one or more target gases in a complex gas component environment. The optical and spectroscopic methods currently used for industrial environmental gas monitoring include differential absorption spectroscopy (DOAS), Fourier transform spectroscopy (FTIR), and tunable semiconductor laser absorption spectroscopy (TDLAS). By combining with open long optical path technology, optical coverage monitoring of the area is achieved to obtain the average gas concentration of the regional optical path. The optical monitoring method also constructs an open multi-optical path monitoring system, which is combined with a computer tomography algorithm (CT) to achieve two-dimensional reconstruction of regional gas distribution. However, this method requires the construction of an open cross-multi-monitoring optical path, requires the coordination of multiple optical systems, and has a complex structure. Summary of the invention

[0004] In order to make up for the above shortcomings, the present invention provides a laser online monitoring method and optical path structure for locating gas leaks in industrial parks, aiming to improve the problem of being unable to provide indications of gas leak locating and the system structure being too complicated.

[0005] In a first aspect, the present invention provides the following technical solution, a laser online monitoring method for positioning gas leaks in an industrial park, comprising the following steps:

[0006] Step 1: superimpose the sawtooth wave signal generated by the scanning signal generating circuit on the driving current generated by the current control circuit to achieve periodic scanning of the output wavelength of the semiconductor laser, and the output wavelength covers the absorption spectrum of the target gas;

[0007] Step 2: The light beam output by the semiconductor laser is divided into two paths through a fiber optic beam splitter, with an optical power ratio of 1:9. The low-power path passes through the calibration pool to obtain a calibration spectrum signal, and the high-power path is transmitted to the transceiver integrated optical end as a detection beam;

[0008] Step 3: Divide the monitoring area into grids, set corner reflectors in each grid, and drive the transceiver to perform horizontal scanning under the guidance of the horizontal scanning gimbal, and form detection optical paths with the corner reflectors in each grid in turn to obtain the absorption spectrum signal of the target gas in each detection optical path;

[0009] Step 4, preprocessing and digitally collecting the acquired spectral signals, and using the calibration spectral signals to invert the optical path integral concentration of each detection light path;

[0010] Step 5: Calculate the target gas concentration distribution in each grid according to the optical path integral concentration of each detection light path, obtain gas concentration distribution data, and provide gas leakage positioning information.

[0011] In the step 4, the optical path integral concentration is inverted, the light intensity fitting function is obtained by fitting the data of the non-absorption signal area, the detection and calibration spectral signals are normalized, and then linear fitting is performed to obtain the integrated absorbance.

[0012] In the step 5, when calculating the target gas concentration in each grid, a linear constant coefficient equation group about the gas concentration of each grid is constructed, and the gas concentration of each grid is solved using a non-negative least squares fitting algorithm.

[0013] In a second aspect, the present invention provides the following technical solutions: an optical path structure of a laser online monitoring method for positioning gas leaks in an industrial park, comprising a host subsystem, a long optical path horizontal scanning optical subsystem, and a corner reflector array;

[0014] The host subsystem includes a scanning signal generating circuit, a current control circuit, a temperature control circuit, a semiconductor laser, a fiber beam splitter, a calibration cell, a fiber self-focusing lens, a photodetector, a signal amplifying circuit, and a signal acquisition and processing circuit that are interconnected;

[0015] The long optical path horizontal scanning optical subsystem is composed of an integrated transceiver optical end and a horizontal scanning platform. The integrated transceiver optical end is equipped with a collimating lens, a parabolic mirror, and a photoelectric detector. The integrated transceiver optical end is connected to the host subsystem through a single-mode optical fiber and a cable, and the horizontal scanning platform is connected to the host subsystem through a cable.

[0016] The corner reflector array is distributed in each grid of the monitoring area, and forms a detection optical path with the transceiver integrated optical end.

[0017] Preferably, in the host subsystem, the operating wavelength of the semiconductor laser is set by a temperature control circuit and a current control circuit.

[0018] Preferably, in the long optical path horizontal scanning optical subsystem, the horizontal scanning gimbal can realize horizontal scanning and precise positioning, so that the transceiver integrated optical end is aligned with the corner reflectors in each grid in sequence.

[0019] Preferably, the collimating lens in the integrated transceiver optical end is used to emit a detection light beam, the parabolic mirror is used to collect the reflected light beam, and the photodetector is used to convert the optical signal into an electrical signal.

[0020] Preferably, the installation height of the corner reflectors in the corner reflector array is the same as that of the transceiver-in-one optical end, and the installation height ensures that the connection line between the transceiver-in-one optical end and the corner reflectors is not blocked.

[0021] In the third aspect, the invention provides the following technical solution: a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned laser online monitoring method for locating gas leaks in an industrial park when executing the computer program.

[0022] In a fourth aspect, the present invention provides the following technical solution: a readable storage medium having a computer program stored thereon, and the computer program, when executed by a processor, implements the above-mentioned laser online monitoring method for locating gas leaks in an industrial park.

[0023] The present invention has the following beneficial effects:

[0024] 1. The present invention provides an industrial park gas leakage positioning laser online monitoring method, which combines the infrared laser spectrum open long optical path detection technology with the multi-optical path gas two-dimensional distribution inversion algorithm to obtain the horizontal two-dimensional distribution data of the target gas concentration above the area, and can provide reliable indication of gas leakage positioning.

[0025] 2. In the present invention, the provided industrial park gas leakage positioning laser online monitoring method and optical path system adopt a scanning radial optical path structure, use a set of optical systems to realize sequential scanning of multiple optical paths, construct multiple detection optical paths, simplify the system structure, and improve the adaptability of the monitoring method and system to the application environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1A schematic diagram of an industrial park gas leakage positioning laser online monitoring method and an optical path structure of an industrial park gas leakage positioning laser online monitoring composition proposed by the present invention;

[0027] Figure 2 A schematic diagram of a laser online monitoring method for positioning gas leaks in industrial parks and a horizontal scanning radial multi-optical path structure of an optical path structure proposed by the present invention;

[0028] Figure 3 This is a schematic diagram of the internal structure of the optical end of the transceiver integrated with the optical path structure of an industrial park gas leakage positioning laser online monitoring method proposed by the present invention. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Embodiment 1

[0031] Reference Figure 1-Figure 3 In a first embodiment of the present invention, the present invention provides a laser online monitoring method for positioning gas leakage in an industrial park, comprising the following steps:

[0032] Step 1: superimpose the sawtooth wave signal generated by the scanning signal generating circuit on the driving current generated by the current control circuit to achieve periodic scanning of the output wavelength of the semiconductor laser, and the output wavelength covers the absorption spectrum of the target gas;

[0033] Step 2: The light beam output by the semiconductor laser is divided into two paths through a fiber optic beam splitter, with an optical power ratio of 1:9. The low-power path passes through the calibration pool to obtain a calibration spectrum signal, and the high-power path is transmitted to the transceiver integrated optical end as a detection beam;

[0034] Step 3: Divide the monitoring area into grids, set corner reflectors in each grid, and drive the transceiver to perform horizontal scanning under the guidance of the horizontal scanning gimbal, and form detection optical paths with the corner reflectors in each grid in turn to obtain the absorption spectrum signal of the target gas in each detection optical path;

[0035] Step 4, preprocessing and digitally collecting the acquired spectral signals, and using the calibration spectral signals to invert the optical path integral concentration of each detection light path;

[0036] Step 5: Calculate the target gas concentration distribution in each grid according to the optical path integral concentration of each detection light path, obtain gas concentration distribution data, and provide gas leakage positioning information.

[0037] In the step 4, the optical path integral concentration is inverted, the light intensity fitting function is obtained by fitting the data of the non-absorption signal area, the detection and calibration spectral signals are normalized, and then linear fitting is performed to obtain the integrated absorbance.

[0038] In the step 5, when calculating the target gas concentration in each grid, a linear constant coefficient equation group about the gas concentration of each grid is constructed, and the gas concentration of each grid is solved using a non-negative least squares fitting algorithm.

[0039] Embodiment 2:

[0040] Reference Figure 2 , in a second embodiment of the present invention, the present invention provides an optical path structure of an industrial park gas leak positioning laser online monitoring method, used for an industrial park gas leak positioning laser online monitoring method as described in any one of claims 1-3, including a host subsystem, a long optical path horizontal scanning optical subsystem and a corner reflector array;

[0041] The host subsystem includes a scanning signal generating circuit, a current control circuit, a temperature control circuit, a semiconductor laser, a fiber beam splitter, a calibration cell, a fiber self-focusing lens, a photodetector, a signal amplifying circuit, and a signal acquisition and processing circuit that are interconnected;

[0042] The long optical path horizontal scanning optical subsystem is composed of an integrated transceiver optical end and a horizontal scanning platform. The integrated transceiver optical end is equipped with a collimating lens, a parabolic mirror, and a photoelectric detector. The integrated transceiver optical end is connected to the host subsystem through a single-mode optical fiber and a cable, and the horizontal scanning platform is connected to the host subsystem through a cable.

[0043] The corner reflector array is distributed in each grid of the monitoring area, and forms a detection optical path with the transceiver integrated optical end.

[0044] In the host subsystem, the operating wavelength of the semiconductor laser is set by a temperature control circuit and a current control circuit.

[0045] In the long optical path horizontal scanning optical subsystem, the horizontal scanning platform can realize horizontal scanning and precise positioning, so that the optical end of the transceiver is aligned with the corner reflectors in each grid in sequence.

[0046] The collimating lens in the integrated transceiver optical end is used to emit a detection light beam, the parabolic mirror is used to collect the reflected light beam, and the photoelectric detector is used to convert the optical signal into an electrical signal.

[0047] The installation height of the corner reflectors in the corner reflector array is the same as that of the transceiver-in-one optical end, and the installation height ensures that the connection line between the transceiver-in-one optical end and the corner reflectors is not blocked.

[0048] 1. Adjust the current control circuit and temperature control circuit in the host subsystem to tune the central wavelength of the semiconductor laser output to the center of the absorption spectrum of the target gas; the scanning signal generated by the scanning signal generating circuit is superimposed on the output drive current of the current control circuit of the semiconductor laser, so that the output wavelength of the semiconductor laser periodically scans a specific wavelength range around the central wavelength, and the scanning signal amplitude is set so that the output scanning wavelength range of the semiconductor laser covers the absorption spectrum of the target gas.

[0049] 2. The laser beam output by the semiconductor laser is divided into two paths with an optical power ratio of 1:9 by the optical fiber beam splitter. The low-power path is used to obtain the calibration spectrum signal. After being collimated by the optical fiber self-focusing lens, it passes through a calibration cell sealed with a known concentration of calibration gas at the same atmospheric pressure as the gas to be measured. The length of the calibration cell is l0 and the concentration of the calibration gas is C0. It is then received by the photoelectric detection in the host and converted into a photoelectric signal. The signal acquisition and processing circuit digitally collects and saves it as a calibration spectrum signal. The calibration spectrum signal data sequence is represented by R0(n), where n is the position of the sampling point sequence of a sampling cycle data. The high-power path output by the optical fiber beam splitter is transmitted to the collimating lens, and after collimation, it is output by the integrated optical end for long optical path scanning detection in the area.

[0050] 3. The detection area is gridded into m grids according to the regional characteristics, which are respectively recorded as i=1~m. The transceiver optical end of the long optical path horizontal scanning optical subsystem is installed on a pan-tilt that can be in the horizontal direction. The pan-tilt is arranged at the angular position of the monitoring area and is used to optically scan the middle corner reflector of the regional grid; the preset scanning pan-tilt makes the transceiver optical end periodically scan in the horizontal plane, so that the transceiver optical end is aligned with the corner reflector in the regional grid one after another, and constitutes a detection optical path, a total of m optical paths, which are respectively recorded as j=1~m. The scanning gimbal makes the integrated optical end of the transceiver briefly stay at each position aligned with the corner reflector in the grid. The output light beam of the integrated optical end reaches the corner reflector arranged in the grid through the detection area. The laser beam is reflected back to the integrated optical end by the original light path of the corner reflector, and is collected and focused on the photodetector in the integrated optical end by the parabolic mirror of the integrated optical end. The photodetector converts the optical signal into an electrical signal, which is transmitted to the host subsystem by a cable. After being amplified by the amplifier circuit in the host subsystem, it is digitally collected and stored by the signal acquisition and processing circuit. After multiple accumulation and averaging, the detection spectrum signal data sequence of the detection optical path is obtained. The detection spectrum signal data sequence of the jth optical path is recorded as S j (n), where n is the position of the data sampling point sequence in one sampling period.

[0051] 4. The calibration spectrum signal data sequence R0(n) obtained from the calibration optical path and the detection spectrum signal data sequence S obtained from each detection optical path j(n) The integrated absorbance A0 of the reference light path and the integrated absorbance A of each detection light path can be calculated. j .

[0052] First, the light intensity fitting functions B0(n) and B j (n), the fitting function is:

[0053] B(n)=b0+b1n+b2n 2

[0054] And use the light intensity fitting function B j (n) and B0(n) respectively detect the spectral signal data sequence S j (n), the calibration spectrum signal data sequence R0(n) obtained by the calibration optical path is normalized to obtain the normalized detection spectrum signal data sequence SN j (n), normalized calibration spectrum signal data sequence RN0(n), the normalization formula is:

[0055]

[0056] The normalized detection spectrum signal data sequence SN of each detection optical path ij (n) and the normalized calibration spectrum signal data sequence RN0(n) are linearly fitted to obtain the integrated absorbance A of each detection light path. ij And the integrated absorbance A0 of the calibration light path, the linear function is taken as the Lorentz function:

[0057]

[0058] Among them: A j 、A0、n j , γ j , n0, and γ0 are fitting constants.

[0059] The optical path integral concentration of each detection optical path and calibration optical path is defined as the integral value of the gas concentration along the optical path, expressed as PIC j and PIC0. Calibration light path PIC0 = l0·C0, then:

[0060]

[0061] 5. Use the optical path integral concentration of each detection optical path to calculate the gas concentration of each grid in the edge area, and then obtain the gas concentration distribution characteristics. The gas concentration in each grid in the area is considered to be uniform, and the gas concentration of the i-th grid is marked as Ci. The transceiver integrated optical end of the long optical path horizontal scanning optical subsystem and each corner reflector in the i-th grid form the j=i-th detection optical path. The optical path length of the j-th detection optical path passing through grid i is lji , the outgoing light beam from the integrated optical end is reflected by the corner reflector and returns to the original light path, so the optical path length of the jth detection light path in grid i is 2l ji Then the pathlength integral concentration PIC of the jth detection light path is j It can be expressed as:

[0062]

[0063] PIC of the optical path integrated concentration of each optical path j can be expressed in the form of the above formula, where the optical path length of the jth detection light path in grid i is 2l ji It can be measured by the optical path, PIC j It is calculated by measuring the spectral signal. Therefore, the above formula can be used to calculate the detection light path integral concentration PIC of each light path. j The expression constitutes a relationship between the gas concentration C of each grid i The linear constant coefficient equations can be used to obtain the gas concentration C of each grid using the non-negative least squares fitting algorithm. i , and then obtain the two-dimensional distribution data of the target gas concentration horizontal plane above the area, thereby providing a reliable indication of gas leak location.

[0064] Embodiment 3

[0065] The third embodiment of the present invention is based on the same inventive concept. The present invention proposes a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the steps of the above-mentioned embodiment of a laser online monitoring method for locating gas leaks in an industrial park.

[0066] Embodiment 4

[0067] The fourth embodiment of the present invention is based on the same inventive concept. The present invention proposes a terminal, which includes: a processor and a memory; the processor and the memory communicate with each other; the memory is used to store instructions; the processor is used to execute the instructions in the memory, and execute the above-mentioned embodiment of a laser online monitoring method for locating gas leaks in an industrial park.

[0068] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0069] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser online monitoring method for gas leakage positioning in industrial parks, characterized in that: The following steps are involved: Step 1: superimpose the sawtooth wave signal generated by the scanning signal generating circuit on the driving current generated by the current control circuit to achieve periodic scanning of the output wavelength of the semiconductor laser, and the output wavelength covers the absorption spectrum of the target gas; Step 2: The light beam output by the semiconductor laser is divided into two paths through a fiber optic beam splitter, with an optical power ratio of 1:

9. The low-power path passes through the calibration pool to obtain a calibration spectrum signal, and the high-power path is transmitted to the transceiver integrated optical end as a detection beam; Step 3: Divide the monitoring area into grids, set corner reflectors in each grid, and drive the transceiver to perform horizontal scanning under the guidance of the horizontal scanning gimbal, and form detection optical paths with the corner reflectors in each grid in turn to obtain the absorption spectrum signal of the target gas in each detection optical path; Step 4, preprocessing and digitally collecting the acquired spectral signals, and using the calibration spectral signals to invert the optical path integral concentration of each detection light path; Step 5: Calculate the target gas concentration distribution in each grid according to the optical path integral concentration of each detection light path, obtain gas concentration distribution data, and provide gas leakage positioning information.

2. The laser online monitoring method for positioning gas leaks in industrial parks according to claim 1 is characterized in that: In the step 4, the optical path integral concentration is inverted, the light intensity fitting function is obtained by fitting the data of the non-absorption signal area, the detection and calibration spectral signals are normalized, and then linear fitting is performed to obtain the integrated absorbance.

3. The method for locating gas leakage in an industrial park by laser online monitoring according to claim 1, characterized in that: In the step 5, when calculating the target gas concentration in each grid, a linear constant coefficient equation group about the gas concentration of each grid is constructed, and the gas concentration of each grid is solved using a non-negative least squares fitting algorithm.

4. An optical path structure of a laser online monitoring method for positioning gas leaks in an industrial park, characterized in that: A laser online monitoring method for positioning gas leaks in industrial parks as described in any one of claims 1 to 3, comprising a host subsystem, a long optical path horizontal scanning optical subsystem and a corner reflector array; The host subsystem includes a scanning signal generating circuit, a current control circuit, a temperature control circuit, a semiconductor laser, a fiber beam splitter, a calibration cell, a fiber self-focusing lens, a photodetector, a signal amplifying circuit, and a signal acquisition and processing circuit that are interconnected; The long optical path horizontal scanning optical subsystem is composed of an integrated transceiver optical end and a horizontal scanning platform. The integrated transceiver optical end is equipped with a collimating lens, a parabolic mirror, and a photoelectric detector. The integrated transceiver optical end is connected to the host subsystem through a single-mode optical fiber and a cable, and the horizontal scanning platform is connected to the host subsystem through a cable. The corner reflector array is distributed in each grid of the monitoring area, and forms a detection optical path with the transceiver integrated optical end.

5. The optical path structure of the laser online monitoring method for locating gas leakage in an industrial park according to claim 4 is characterized in that: In the host subsystem, the operating wavelength of the semiconductor laser is set by a temperature control circuit and a current control circuit.

6. The optical path structure of the laser online monitoring method for positioning gas leakage in an industrial park according to claim 4 is characterized in that: In the long optical path horizontal scanning optical subsystem, the horizontal scanning platform can realize horizontal scanning and precise positioning, so that the optical end of the transceiver is aligned with the corner reflectors in each grid in sequence.

7. The optical path structure of the laser online monitoring method for locating gas leakage in an industrial park according to claim 4 is characterized in that: The collimating lens in the integrated transceiver optical end is used to emit a detection light beam, the parabolic mirror is used to collect the reflected light beam, and the photoelectric detector is used to convert the optical signal into an electrical signal.

8. The optical path structure of the laser online monitoring method for positioning gas leakage in an industrial park according to claim 4 is characterized in that: The installation height of the corner reflectors in the corner reflector array is the same as that of the transceiver-in-one optical end, and the installation height ensures that the connection line between the transceiver-in-one optical end and the corner reflectors is not blocked.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the laser online monitoring method for locating gas leaks in an industrial park is implemented as described in any one of claims 1 to 3.

10. A readable storage medium, characterized in that: The readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for online laser monitoring of gas leakage positioning in an industrial park as described in any one of claims 1 to 3 is implemented.

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