A methane emission monitoring method, system, device and storage medium

Abstract

The application discloses a kind of methane emission monitoring method, system, equipment and storage medium, it is applied to industrial computer in TDLAS system, it is related to gas detection technical field, comprising: obtaining laser electric signal and solving absorption intensity, and based on light absorption intensity, the methane path integral concentration data corresponding to each scanning angle is determined, the spatial interpolation and fitting of each scanning angle data are carried out, the methane concentration data are obtained, and the methane surface density is determined accordingly, with gas diffusion cross section as integral interval, the methane mass density is obtained by integrating surface density, in combination with real-time wind speed and monitoring time length, the real-time emission rate and total emission are calculated, to improve the accuracy of methane emission monitoring.

Description

Technical Field

[0001] This invention relates to the field of gas detection technology, and in particular to a method, system, device and storage medium for monitoring methane emissions. Background Technology

[0002] Currently, the mainstream technology for methane gas detection is TDLAS (Tunable Diode Laser Absorption Spectroscopy). Most monitoring systems developed domestically and internationally based on this technology emit a single beam of light, and then detect a specific point in the environment by collecting and analyzing the reflected light signal. However, due to the uncontrollable nature of the gas escape process, measurement data from a single point cannot depict the complete spatiotemporal information of methane gas, making it difficult to determine the location of the gas leak source. Furthermore, existing point-based measurement data has poor time synchronization, making it impossible to guarantee cross-sectional data at the same moment when calculating emissions, resulting in significant errors in gas emission calculations.

[0003] As can be seen from the above, improving the accuracy of methane emission monitoring is an urgent problem to be solved. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method, system, device, and storage medium for monitoring methane emissions, which can improve the accuracy of methane emission monitoring. The specific solution is as follows: In a first aspect, this application provides a method for monitoring methane emissions, applied to an industrial control computer within a TDLAS system, comprising: A laser electrical signal is acquired, and its absorption intensity is calculated to obtain the light absorption intensity. Based on the light absorption intensity, the methane path integral concentration data corresponding to each scanning angle is determined. The laser electrical signal is a signal determined based on a photodetector and an echo laser signal. The echo laser signal is a signal obtained by reflecting light from background reflectors. The light signal is a signal emitted by a tunable semiconductor laser to the methane gas to be detected in the target monitoring area. Based on the integrated concentration data of each methane path corresponding to the gas diffusion cross section of the target monitoring area, the methane concentration data corresponding to each detection path in the target monitoring area is obtained, and the methane surface density data is determined using the methane concentration data. Spatial interpolation and fitting are performed on the methane surface density data to obtain the methane surface density distribution function, and the methane mass density is obtained by integrating the methane surface density distribution function based on the gas diffusion cross section. The real-time methane emission rate is determined based on the methane mass density and wind speed, and the total methane gas emission within the target monitoring area is determined based on the real-time methane emission rate and monitoring duration.

[0005] Optionally, acquiring the laser electrical signal includes: A tunable semiconductor laser is driven by a preset current and temperature controller in order to determine the optical signal output by the tunable semiconductor laser, and the optical signal is transmitted to an optical fiber collimator using a single-mode optical fiber. The optical signal is collimated using the fiber collimator to obtain a parallel beam, and the parallel beam is split using a beam splitter to obtain transmitted light and reflected light. The transmitted light is incident on the reflecting surface of the galvanometer, so that the deflection angle of the transmitted light in the vertical direction can be adjusted by the galvanometer. Then, the light beam reflected by the galvanometer is incident on a high-speed rotating multi-faceted mirror, so that the deflection angle of the light beam in the horizontal direction can be adjusted by the multi-faceted rotating mirror to obtain a laser beam. When the laser beam illuminates the target background of the target monitoring area, a diffusely reflected echo signal is obtained, and the reflected light is determined by the multi-faceted rotating mirror, the galvanometer and the beam splitter in sequence. The reflected light is focused through a lens onto the photosensitive surface of a photodetector, so that the photodetector can convert the reflected light into a laser electrical signal.

[0006] Optionally, the step of calculating the absorption intensity of the laser electrical signal to obtain the light absorption intensity, and determining the methane path integral concentration data corresponding to each scanning angle based on the light absorption intensity, includes: Determine the echo laser signal reflected by background reflectors within the target monitoring area; The laser electrical signal is determined based on the echo laser signal; The absorption intensity of the laser electrical signal is calculated using TDLAS technology to obtain the light absorption intensity at the laser emission angle, and the methane path integral concentration data at the laser emission angle is determined. The scanning motion azimuth information is determined based on each scanning emission angle. The scanning motion azimuth information is used to match the methane path integral concentration data at the corresponding scanning exit angle.

[0007] Optionally, obtaining the methane concentration data corresponding to each detection path in the target monitoring area based on the integrated concentration data of each methane path corresponding to the gas diffusion cross section of the target monitoring area includes: Based on the gas diffusion cross section of the target monitoring area, the coordinate information of each detection optical path and the methane path integral concentration data of the corresponding optical path are extracted from the methane gas spatiotemporal distribution dataset to obtain a discrete methane gas concentration point cloud. The methane gas concentration point cloud is interpolated and fitted using a spatial interpolation algorithm to obtain methane concentration data within the target monitoring area. The methane concentration data is equivalently transformed based on the laser absorption path corresponding to the methane concentration data to obtain the transformed methane concentration data.

[0008] Optionally, determining the methane surface density data using the methane concentration data includes: The converted methane concentration data is used, and the methane path integral concentration data is processed based on the methane molar mass and gas molar volume to obtain processed data; The processed data is converted using a preset unit conversion formula to obtain the corresponding methane surface density data.

[0009] Optionally, the step of performing spatial interpolation and fitting processing on each of the methane surface density data to obtain a methane surface density distribution function, and integrating the methane surface density distribution function based on the gas diffusion cross section to obtain the methane mass density, includes: The two-dimensional plane perpendicular to the methane gas diffusion direction in the target monitoring area is set as the gas diffusion cross section, and the lateral path of the gas diffusion cross section is set as the integration interval; Spatial interpolation and fitting are performed on each of the methane surface density data within the integration interval to obtain the methane surface density distribution function. The methane surface density data in the gas diffusion cross section are then integrated along the integration path using the methane surface density distribution function to obtain the methane mass density of the gas diffusion cross section.

[0010] Optionally, determining the real-time methane emission rate based on the methane mass density and wind speed, and determining the total methane gas emission within the target monitoring area based on the real-time methane emission rate and monitoring duration, includes: The real-time wind speed of the methane gas to be measured in the target monitoring area at the gas diffusion section is obtained, and the real-time emission rate of methane is determined by the methane mass density and the real-time wind speed based on the mass conservation method. The monitoring duration of the methane emission monitoring process is determined, and the total methane gas emission in the target monitoring area is determined based on the real-time methane emission rate and the monitoring time.

[0011] Secondly, this application provides a methane emission monitoring system, applied to an industrial control computer within a TDLAS system, comprising: A semiconductor laser used to emit a laser beam into a methane gas to be tested; An optical fiber collimator is used to collimate the laser beam into a parallel incident beam. The beam splitting unit includes a beam splitter for splitting the parallel incident beam into a transmitted beam and a reflected beam; A galvanometer-rotating mirror cooperative scanning assembly is used to determine the reflected beam containing methane gas absorption information in the space region to be measured. The galvanometer-rotating mirror cooperative scanning assembly is located on the transmitted light output path of the beam splitter and includes a galvanometer unit and a rotating mirror unit arranged sequentially along the transmitted light output path. The galvanometer unit is used to adjust the vertical azimuth angle of the beam; the rotating mirror unit is used to adjust the horizontal azimuth angle of the beam reflected by the galvanometer unit. A reflector is used to reflect the reflected light beam to a lens; the lens is used to focus the reflected light beam onto a photodetector. The photodetector is used to convert the focusing signal into a laser electrical signal; Furthermore, the methane emission monitoring system also includes the industrial control computer.

[0012] Thirdly, this application provides an industrial control computer, including: Memory, used to store computer programs; A processor is used to execute the computer program to implement the aforementioned methane emission monitoring method.

[0013] Fourthly, this application provides a computer-readable storage medium for storing a computer program, wherein the computer program, when executed by a processor, implements the aforementioned methane emission monitoring method.

[0014] As can be seen from the above, before monitoring methane emissions, this application needs to acquire laser electrical signals, calculate the absorption intensity of the laser electrical signals to obtain the light absorption intensity, and determine the methane path integral concentration data corresponding to each scanning angle based on the light absorption intensity. The laser electrical signal is a signal determined based on a photodetector and an echo laser signal. The echo laser signal is a signal obtained from the light signal reflected by background reflectors. The light signal is a signal emitted by a tunable semiconductor laser to the methane gas to be detected in the target monitoring area. Based on the methane path integral concentration data corresponding to each methane path in the target monitoring area, the methane concentration data corresponding to each detection path in the target monitoring area is obtained, and the methane surface density data is determined using the methane concentration data. Spatial interpolation and fitting processing is performed on each methane surface density data to obtain the methane surface density distribution function, and the methane mass density is obtained by integrating the methane surface density distribution function based on the gas diffusion cross section. The real-time methane emission rate is determined based on the methane mass density and wind speed, and the total methane gas emission in the target monitoring area is determined based on the real-time methane emission rate and monitoring duration.

[0015] Therefore, this application first needs to acquire the laser electrical signal and calculate its absorption intensity to obtain the light absorption intensity. Based on the light absorption intensity, the integrated concentration data of methane paths corresponding to each scanning angle is determined. Second, based on the integrated concentration data of each methane path corresponding to the gas diffusion cross section of the target monitoring area, the methane concentration data corresponding to each detection path in the target monitoring area is obtained, and the methane surface density data is determined using the methane concentration data. Then, spatial interpolation and fitting processing is performed on each methane surface density data to obtain the methane surface density distribution function. The methane mass density is obtained by integrating the methane surface density distribution function based on the gas diffusion cross section. Finally, the real-time methane emission rate is determined based on the methane mass density and wind speed, and the total methane gas emission in the target monitoring area is determined based on the real-time methane emission rate and monitoring duration. In this way, the accuracy of methane emission monitoring is improved, thereby enhancing the user experience. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 This is a flowchart of a methane emission monitoring method disclosed in this application; Figure 2 This application discloses a specific schematic diagram of Lambert-Beer's law. Figure 3 This is a schematic diagram of a specific TDLAS gas detection system disclosed in this application; Figure 4 This is a schematic diagram of a specific testing instrument disclosed in this application; Figure 5 This is a schematic diagram of the spatiotemporal distribution of a specific type of methane gas disclosed in this application; Figure 6 This is a schematic diagram of a methane emission monitoring system disclosed in this application; Figure 7 This is a structural diagram of an industrial control computer disclosed in this application. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The mainstream technology for methane gas detection is TDLAS. Currently, most monitoring systems developed domestically and internationally based on this technology emit a single-line beam and then detect a specific point in the environment by collecting and analyzing the reflected light signal. However, due to the uncontrollable nature of the gas escape process, measurement data from a single point cannot depict the complete spatiotemporal information of methane gas, making it difficult to determine the location of the gas leak source. Furthermore, existing point-based measurement data has poor time synchronization, making it impossible to guarantee cross-sectional data at the same moment when calculating emissions, resulting in significant errors in emission calculation. Therefore, this application provides a methane emission monitoring method that can improve the accuracy of methane emission monitoring.

[0020] See Figure 1 As shown in the figure, an embodiment of the present invention discloses a method for monitoring methane emissions, comprising: Step S11: Acquire the laser electrical signal, calculate the absorption intensity of the laser electrical signal to obtain the light absorption intensity, and determine the methane path integral concentration data corresponding to each scanning angle based on the light absorption intensity; the laser electrical signal is a signal determined based on the photodetector and the echo laser signal; the echo laser signal is a signal obtained by reflecting light from the background reflector; the light signal is a signal emitted by the tunable semiconductor laser to the methane gas to be detected in the target monitoring area.

[0021] In this embodiment, the TDLAS technology obtains gas concentration information by detecting the degree of light intensity attenuation caused by the absorption of laser light of a specific wavelength by the analyte gas based on Lambert-Beer's law. The principle diagram of Lambert-Beer's law is shown below. Figure 2 As shown.

[0022] It is worth noting that when a laser beam of a specific wavelength passes through a target gas, if the laser wavelength is outside the gas absorption spectrum, the light intensity will not change; if the laser wavelength is within the gas absorption spectrum, some of the light energy will be absorbed by the gas molecules, resulting in light intensity attenuation, as shown in the following equation: ; in, , These represent the intensity of the emitted light from the system and the intensity of the reflected light after absorption by the target gas, respectively. The wavelength of light The wavelength absorbed by the target gas center. For gas temperature, , , , , These represent ambient pressure, gas absorption intensity, gas absorption function, gas concentration, and gas absorption optical path length, respectively.

[0023] As can be seen from the above formula, the embodiments of this application can obtain information such as gas concentration by measuring the emitted light intensity.

[0024] Subsequently, the absorbance needs to be defined in this application embodiment. Taking the logarithm of the ratio of emitted light intensity to reflected light intensity in Beer-Lambert's law, we get: ; absorbance Take the integral, where the normalized linear function is... The integral value is 1: ; The gas concentration can be obtained: ; As can be understood from the above formula, by measuring the attenuation of laser light intensity at a specific wavelength, relevant information such as gas concentration can be obtained.

[0025] In this embodiment, the schematic diagram of the TDLAS gas detection system is as follows: Figure 3 As shown: The signal driving module drives the laser to emit a beam with a wavelength at the absorption wavelength of methane. The beam is collimated into parallel light by an optical fiber collimator and then emitted. After being absorbed by the gas, the beam diffusely reflected back from the background is focused by a lens onto a photodetector. The detector converts the optical signal into an electrical signal. The data acquisition module converts the analog electrical signal into a digital electrical signal. Finally, the industrial control computer analyzes the digital electrical signal to obtain the gas concentration.

[0026] It is worth mentioning that the TDLAS gas detection system is encapsulated in a structure such as Figure 4 The detection instrument shown has limitations due to its technical principles. It can only detect methane gas concentration along a specific laser path. In practical applications, due to the uncertainty of the gas dispersion process, relying solely on methane gas leakage information measured along a few laser paths only allows for the determination of the presence of methane gas at a few measurement points, making it difficult to pinpoint the location of the leak source. Furthermore, it cannot calculate the actual amount of methane gas emitted over the entire space. Therefore, a technology is urgently needed to address these shortcomings.

[0027] In this embodiment, the methane emission monitoring system detects the spatiotemporal distribution data of methane gas, including methane gas concentration and scanning motion azimuth information. Using this information, a spatiotemporal distribution image of methane gas can be generated. Each motion azimuth angle represents the position of an image pixel, and the detected methane gas concentration at that azimuth angle represents the image pixel value. The corresponding spatiotemporal distribution image of methane gas is shown below. Figure 5 As shown.

[0028] In this embodiment, a tunable semiconductor laser (DFB-LD, or Distributed Feedback-Laser Diode) with a center wavelength located near the strong absorption line of methane (e.g., around 1653 nm) is selected. The laser is driven by a current / temperature controller, outputting a wavelength-controlled beam. The laser is then transmitted via a single-mode fiber to a fiber collimator, outputting a parallel beam. This parallel beam is incident on a 50 / 50 beam splitter, where it is split into transmitted and reflected light (each with approximately 50% energy). The beam that passes through the beam splitter first strikes the reflecting surface of a galvanometer. The galvanometer is driven by a servo motor, performing high-frequency reciprocating oscillations to change the beam's deflection angle in the vertical direction.

[0029] Furthermore, the beam reflected by the galvanometer is incident on a high-speed rotating multifaceted mirror. The high-speed rotation of the mirror allows the beam to scan rapidly in the horizontal direction. The combined motion of the galvanometer and rotating mirror alters the laser beam's exit angle, achieving spatial scanning and covering the entire field of view. After the laser beam illuminates the target background (such as the ground, wall, or equipment surface), diffuse reflection occurs. A portion of the diffusely reflected light returns along the original optical path, passing sequentially through the reflecting surfaces of the rotating mirror and the galvanometer before returning to the beam splitter. At the beam splitter, a portion of the returning light is reflected and enters the receiving optical path. Subsequently, the returning light separated by the beam splitter is focused by a focusing lens onto the photosensitive surface of a high-sensitivity photodetector. The detector converts the optical signal into an electrical signal. Then, the calculated integrated concentration value is mapped one-to-one with the corresponding scanning angle onto a two-dimensional plane, generating a methane column concentration distribution image. Finally, the gas emission amount is calculated based on the gas emission calculation method described in Part II.

[0030] Specifically, acquiring the laser electrical signal may include: driving a tunable semiconductor laser through a preset current and temperature controller to determine the optical signal output by the tunable semiconductor laser, and transmitting the optical signal to an optical fiber collimator using a single-mode fiber; collimating the optical signal using the optical fiber collimator to obtain a parallel beam, and splitting the parallel beam using a beam splitter to obtain transmitted light and reflected light; incident the transmitted light onto the reflecting surface of a galvanometer to adjust the deflection angle of the transmitted light in the vertical direction using the galvanometer, and then incident the beam reflected by the galvanometer onto a high-speed rotating multifaceted mirror to adjust the deflection angle of the beam in the horizontal direction using the multifaceted mirror to obtain a laser beam; when the laser beam illuminates the target background of the target monitoring area, a diffusely reflected echo signal is obtained, and the reflected light is determined sequentially using the multifaceted mirror, the galvanometer, and the beam splitter; and converging the reflected light through a lens onto the photosensitive surface of a photodetector to convert the reflected light into a laser electrical signal using the photodetector.

[0031] In this embodiment, calculating the gas emission rate requires first calculating the gas emission amount. The most commonly used method for calculating the gas emission rate is the mass conservation method, and the formula for this method is as follows: ; in, This indicates the gas emission rate (unit: g / s). The mass distribution function of methane gas at a certain cross section (unit: g / m). V This represents the diffusion velocity (in m / s) at this cross-section. When studying gas plumes in space, it is necessary to obtain the diffusion velocity and mass distribution at various points on a plane of the gas cloud in order to calculate the gas leakage rate.

[0032] Furthermore, embodiments of this application require determining the acquisition point. , The gas emission rate of the leak source can be calculated by integrating the product of the mass distribution and diffusion velocity at each detection location. It's worth noting that TDLAS technology measures path integral concentration in ppm·m (representing the gas integral concentration along the laser path). Combined with optical spatial scanning technology, the actual measurement result is represented as a spatial "methane column concentration projection map." Therefore, a conversion between "column concentration" and "mass density" is required before the gas emission rate can be calculated.

[0033] Specifically, the step of calculating the absorption intensity of the laser electrical signal to obtain the light absorption intensity, and determining the methane path integral concentration data corresponding to each scanning angle based on the light absorption intensity, may include: determining the echo laser signal reflected by the background reflectors within the target monitoring area; determining the laser electrical signal based on the echo laser signal; calculating the absorption intensity of the laser electrical signal using TDLAS technology to obtain the light absorption intensity at the laser emission angle, determining the methane path integral concentration data at the laser emission angle, and determining the scanning motion azimuth information based on each scanning emission angle; and matching the methane path integral concentration data at the corresponding scanning emission angle using the scanning motion azimuth information.

[0034] Step S12: Based on the methane path integral concentration data corresponding to the gas diffusion cross section of the target monitoring area, obtain the methane concentration data corresponding to each detection path in the target monitoring area, and use the methane concentration data to determine the methane surface density data.

[0035] In this embodiment, the gas concentration distribution function needs to be calculated and the unit converted: the detection unit of TDLAS technology is ppm·m, which means the gas concentration on this optical path × the value of the absorption path. If the absorption path is assumed to be 1m, then the measurement result means the gas concentration when the absorption path is 1m.

[0036] In subsequent calculations, this embodiment of the application equates the measurement result to the gas concentration when the absorption path is 1m. Then, based on the detection optical path coordinate information and the gas concentration along the detection optical path, this embodiment uses an interpolation algorithm to convert the discrete gas concentration point cloud into a gas concentration distribution function. Then, a unit conversion is performed, and the gas concentration distribution function is converted into a mass distribution function using the following formula: ; in, l For distance variables, 1m is used as the unit for separation. Let be the gas mass distribution function on the cross section. Let be the gas concentration distribution function. Where is the molar mass of methane. This represents the molar volume of the gas.

[0037] Specifically, obtaining the methane concentration data corresponding to each detection path in the target monitoring area based on the methane path integral concentration data corresponding to the gas diffusion cross section of the target monitoring area may include: extracting the coordinate information of each detection optical path and the methane path integral concentration data of the corresponding optical path from the methane gas spatiotemporal distribution dataset based on the gas diffusion cross section of the target monitoring area to obtain a discrete methane gas concentration point cloud; performing interpolation and fitting processing on the methane gas concentration point cloud using a spatial interpolation algorithm to obtain methane concentration data within the target monitoring area; and performing an equivalent transformation on the methane concentration data based on the laser absorption path corresponding to the methane concentration data to obtain the transformed methane concentration data.

[0038] Subsequently, determining the methane surface density data using the methane concentration data may include: processing the methane path integral concentration data using the converted methane concentration data and based on the methane molar mass and gas molar volume to obtain processed data; and converting the processed data using a preset unit conversion formula to obtain the corresponding methane surface density data.

[0039] Step S13: Perform spatial interpolation and fitting on each of the methane surface density data to obtain the methane surface density distribution function, and integrate the methane surface density distribution function based on the gas diffusion cross section to obtain the methane mass density.

[0040] In this embodiment, the gas mass integral of the above-mentioned cross-section is performed to obtain the "gas linear density" of the cross-section. The integral formula is as follows: ; in, For distance variables.

[0041] Specifically, spatial interpolation and fitting are performed on each of the methane surface density data to obtain a methane surface density distribution function. The methane mass density is then obtained by integrating the methane surface density distribution function based on the gas diffusion cross section. This process can include: defining a two-dimensional plane perpendicular to the methane gas diffusion direction in the target monitoring area as the gas diffusion cross section, and defining the transverse path of the gas diffusion cross section as the integration interval; performing spatial interpolation and fitting on each of the methane surface density data within the integration interval to obtain a methane surface density distribution function; and then integrating the methane surface density data in the gas diffusion cross section along the integration path using the methane surface density distribution function to obtain the methane mass density of the gas diffusion cross section.

[0042] Step S14: Determine the real-time methane emission rate based on the methane mass density and wind speed, and determine the total methane gas emission in the target monitoring area based on the real-time methane emission rate and monitoring duration.

[0043] In this embodiment, the emission rate needs to be calculated by multiplying the "gas linear density" by the diffusion velocity on the plane. Obtain gas emission rate: ; Subsequently, embodiments of this application can determine the amount of methane gas emitted based on the emission rate and emission time.

[0044] Specifically, determining the real-time methane emission rate based on the methane mass density and wind speed, and determining the total methane gas emission in the target monitoring area based on the real-time methane emission rate and monitoring duration, may include: obtaining the real-time wind speed of the methane gas to be measured in the target monitoring area at the gas diffusion cross section, and determining the real-time methane emission rate based on the methane mass density and the real-time wind speed using the mass conservation method; determining the monitoring duration of the methane emission monitoring process, and determining the total methane gas emission in the target monitoring area based on the real-time methane emission rate and the monitoring duration.

[0045] As can be seen from the above, the embodiments of this application first need to acquire the laser electrical signal, calculate the absorption intensity of the laser electrical signal to obtain the light absorption intensity, and determine the methane path integral concentration data corresponding to each scanning angle based on the light absorption intensity; secondly, based on the methane path integral concentration data corresponding to each methane path in the target monitoring area, the methane concentration data corresponding to each detection path in the target monitoring area is obtained, and the methane surface density data is determined using the methane concentration data; then, spatial interpolation and fitting processing is performed on each methane surface density data to obtain the methane surface density distribution function, and the methane mass density is obtained by integrating the methane surface density distribution function based on the gas diffusion cross section; finally, the real-time methane emission rate is determined based on the methane mass density and wind speed, and the total methane gas emission in the target monitoring area is determined based on the real-time methane emission rate and monitoring duration. In this way, the accuracy of methane emission monitoring is improved during the methane emission monitoring process, thereby enhancing the user experience.

[0046] Accordingly, see Figure 6 As shown, this application also provides a methane emission monitoring system, comprising: A semiconductor laser used to emit a laser beam into a methane gas to be tested; An optical fiber collimator is used to collimate the laser beam into a parallel incident beam. The beam splitting unit includes a beam splitter for splitting the parallel incident beam into a transmitted beam and a reflected beam; A galvanometer-rotating mirror cooperative scanning assembly is used to determine the reflected beam containing methane gas absorption information in the space region to be measured. The galvanometer-rotating mirror cooperative scanning assembly is located on the transmitted light output path of the beam splitter and includes a galvanometer unit and a rotating mirror unit arranged sequentially along the transmitted light output path. The galvanometer unit is used to adjust the vertical azimuth angle of the beam; the rotating mirror unit is used to adjust the horizontal azimuth angle of the beam reflected by the galvanometer unit. A reflector is used to reflect the reflected light beam to a lens; the lens is used to focus the reflected light beam onto a photodetector. The photodetector is used to convert the focusing signal into a laser electrical signal; Furthermore, the methane emission monitoring system also includes an industrial control computer.

[0047] In this embodiment, the methane emission monitoring system proposed in this application aims to achieve "area-like" scanning detection of methane gas in a spatial range, thereby obtaining spatiotemporal data of methane distribution to locate methane leakage sources and calculate gas emissions.

[0048] In this embodiment, the methane emission monitoring system consists of a rotating mirror, a galvanometer, a light source, a fiber optic collimator, a beam splitter, a reflector, a lens, and a photodetector. The light source is a tunable semiconductor laser, whose driving current can be adjusted to change the output wavelength, placing it within the methane gas absorption band. The laser beam is collimated into parallel light by the fiber optic collimator and then emitted through the beam splitter. The beam splitter can separate an incident beam into reflected and transmitted light in a specific ratio. This system uses a 50 / 50 beam splitter, which can evenly distribute the incident light energy into two parts: half passes through the lens, and the other half is reflected. After being collimated by an optical fiber collimator, the light beam is emitted. Approximately 50% of the energy passes through the beam splitter during the first pass. The beam then travels to a galvanometer on the periphery of the transceiver system. The galvanometer swings up and down to change the vertical azimuth angle of the beam, thus achieving vertical scanning. The beam reflected by the galvanometer then travels to a rotating mirror, which rotates horizontally to achieve horizontal scanning. By utilizing the cooperation between the galvanometer and the rotating mirror, omnidirectional scanning detection within a spatial range can be achieved. The reflected beam is reflected again by the rotating mirror to the beam splitter, then reflected a second time to a reflecting mirror. The beam reflected by the reflecting mirror is focused by a lens onto a photodetector. The photodetector converts the light into an electrical signal, which is then sent to subsequent systems for processing and analysis of the methane gas concentration.

[0049] Furthermore, this application also discloses an industrial control computer. Figure 7This is a structural diagram of an industrial control computer 20 according to an exemplary embodiment. The content of the diagram should not be construed as limiting the scope of this application. Specifically, the industrial control computer 20 may include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input / output interface 25, and a communication bus 26. The memory 22 stores a computer program, which is loaded and executed by the processor 21 to implement the relevant steps in the methane emission monitoring method disclosed in any of the foregoing embodiments. Furthermore, the industrial control computer 20 in this embodiment may specifically be an electronic computer.

[0050] In this embodiment, the power supply 23 is used to provide operating voltage for the various hardware devices on the industrial control computer 20; the communication interface 24 can create a data transmission channel between the industrial control computer 20 and external devices, and the communication protocol it follows can be any communication protocol applicable to the technical solution of this application, and is not specifically limited here; the input / output interface 25 is used to acquire external input data or output data to the outside world, and its specific interface type can be selected according to specific application needs, and is not specifically limited here.

[0051] In addition, the memory 22, as a carrier for resource storage, can be a read-only memory, random access memory, disk or optical disk, etc. The resources stored thereon can include operating system 221, computer program 222, etc., and the storage method can be temporary storage or permanent storage.

[0052] The operating system 221 is used to manage and control the various hardware devices on the industrial control computer 20 and the computer program 222, which may be Windows Server, Netware, Unix, Linux, etc. In addition to including a computer program capable of performing the methane emission monitoring method executed by the industrial control computer 20 as disclosed in any of the foregoing embodiments, the computer program 222 may further include computer programs capable of performing other specific tasks.

[0053] Furthermore, this application also discloses a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, it implements the aforementioned methane emission monitoring method. Specific steps of this method can be found in the corresponding content disclosed in the foregoing embodiments, and will not be repeated here.

[0054] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0055] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0056] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0057] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0058] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for monitoring methane emissions, characterized in that, Industrial control computers used in TDLAS systems include: A laser electrical signal is acquired, and its absorption intensity is calculated to obtain the light absorption intensity. Based on the light absorption intensity, the methane path integral concentration data corresponding to each scanning angle is determined. The laser electrical signal is a signal determined based on a photodetector and an echo laser signal. The echo laser signal is a signal obtained by reflecting light from background reflectors. The light signal is a signal emitted by a tunable semiconductor laser to the methane gas to be detected in the target monitoring area. Based on the integrated concentration data of each methane path corresponding to the gas diffusion cross section of the target monitoring area, the methane concentration data corresponding to each detection path in the target monitoring area is obtained, and the methane surface density data is determined using the methane concentration data. Spatial interpolation and fitting are performed on the methane surface density data to obtain the methane surface density distribution function, and the methane mass density is obtained by integrating the methane surface density distribution function based on the gas diffusion cross section. The real-time methane emission rate is determined based on the methane mass density and wind speed, and the total methane gas emission within the target monitoring area is determined based on the real-time methane emission rate and monitoring duration.

2. The methane emission monitoring method according to claim 1, characterized in that, The acquisition of the laser electrical signal includes: A tunable semiconductor laser is driven by a preset current and temperature controller in order to determine the optical signal output by the tunable semiconductor laser, and the optical signal is transmitted to an optical fiber collimator using a single-mode optical fiber. The optical signal is collimated using the fiber collimator to obtain a parallel beam, and the parallel beam is split using a beam splitter to obtain transmitted light and reflected light. The transmitted light is incident on the reflecting surface of the galvanometer, so that the deflection angle of the transmitted light in the vertical direction can be adjusted by the galvanometer. Then, the light beam reflected by the galvanometer is incident on a high-speed rotating multi-faceted mirror, so that the deflection angle of the light beam in the horizontal direction can be adjusted by the multi-faceted rotating mirror to obtain a laser beam. When the laser beam illuminates the target background of the target monitoring area, a diffusely reflected echo signal is obtained, and the reflected light is determined by the multi-faceted rotating mirror, the galvanometer and the beam splitter in sequence. The reflected light is focused through a lens onto the photosensitive surface of a photodetector, so that the photodetector can convert the reflected light into a laser electrical signal.

3. The methane emission monitoring method according to claim 1, characterized in that, The process of calculating the absorption intensity of the laser electrical signal to obtain the light absorption intensity, and determining the methane path integral concentration data corresponding to each scanning angle based on the light absorption intensity, includes: Determine the echo laser signal reflected by background reflectors within the target monitoring area; The laser electrical signal is determined based on the echo laser signal; The absorption intensity of the laser electrical signal is calculated using TDLAS technology to obtain the light absorption intensity at the laser emission angle, and the methane path integral concentration data at the laser emission angle is determined. The scanning motion azimuth information is determined based on each scanning emission angle. The scanning motion azimuth information is used to match the methane path integral concentration data at the corresponding scanning exit angle.

4. The methane emission monitoring method according to claim 3, characterized in that, The method of obtaining methane concentration data corresponding to each detection path in the target monitoring area based on the integrated concentration data of each methane path corresponding to the gas diffusion cross section of the target monitoring area includes: Based on the gas diffusion cross section of the target monitoring area, the coordinate information of each detection optical path and the methane path integral concentration data of the corresponding optical path are extracted from the methane gas spatiotemporal distribution dataset to obtain a discrete methane gas concentration point cloud. The methane gas concentration point cloud is interpolated and fitted using a spatial interpolation algorithm to obtain methane concentration data within the target monitoring area. The methane concentration data is equivalently transformed based on the laser absorption path corresponding to the methane concentration data to obtain the transformed methane concentration data.

5. The methane emission monitoring method according to claim 4, characterized in that, The process of determining methane surface density data using the methane concentration data includes: The converted methane concentration data is used, and the methane path integral concentration data is processed based on the methane molar mass and gas molar volume to obtain the processed data; The processed data is converted using a preset unit conversion formula to obtain the corresponding methane surface density data.

6. The methane emission monitoring method according to claim 1, characterized in that, The process of spatial interpolating and fitting the methane surface density data to obtain the methane surface density distribution function, and integrating the methane surface density distribution function based on the gas diffusion cross section to obtain the methane mass density, includes: A two-dimensional plane perpendicular to the methane gas diffusion direction in the target monitoring area is set as the gas diffusion cross section, and the lateral path of the gas diffusion cross section is set as the integration interval; Spatial interpolation and fitting are performed on each of the methane surface density data within the integration interval to obtain the methane surface density distribution function. The methane surface density data in the gas diffusion cross section are then integrated along the integration path using the methane surface density distribution function to obtain the methane mass density of the gas diffusion cross section.

7. The method for monitoring methane emissions according to any one of claims 1 to 6, characterized in that, The process of determining the real-time methane emission rate based on the methane mass density and wind speed, and determining the total methane emissions within the target monitoring area based on the real-time methane emission rate and monitoring duration, includes: The real-time wind speed of the methane gas to be measured in the target monitoring area at the gas diffusion section is obtained, and the real-time emission rate of methane is determined by the methane mass density and the real-time wind speed based on the mass conservation method. The monitoring duration of the methane emission monitoring process is determined, and the total methane gas emission in the target monitoring area is determined based on the real-time methane emission rate and the monitoring time.

8. An industrial control computer, characterized in that, include: Memory, used to store computer programs; A processor for executing the computer program to implement the methane emission monitoring method as described in any one of claims 1 to 7.

9. A methane emission monitoring system, characterized in that, include: A semiconductor laser used to emit a laser beam into a methane gas to be tested; An optical fiber collimator is used to collimate the laser beam into a parallel incident beam. The beam splitting unit includes a beam splitter for splitting the parallel incident beam into a transmitted beam and a reflected beam; A galvanometer-rotating mirror cooperative scanning assembly is used to determine the reflected beam containing methane gas absorption information in the space region to be measured. The galvanometer-rotating mirror cooperative scanning assembly is located on the transmitted light output path of the beam splitter and includes a galvanometer unit and a rotating mirror unit arranged sequentially along the transmitted light output path. The galvanometer unit is used to adjust the vertical azimuth angle of the beam; the rotating mirror unit is used to adjust the horizontal azimuth angle of the beam reflected by the galvanometer unit. A reflector is used to reflect the reflected light beam to a lens; the lens is used to focus the reflected light beam onto a photodetector. The photodetector is used to convert the focusing signal into a laser electrical signal; Furthermore, the methane emission monitoring system also includes the industrial control computer as described in claim 8.

10. A computer-readable storage medium, characterized in that, Used to store a computer program, wherein the computer program, when executed by a processor, implements the methane emission monitoring method as described in any one of claims 1 to 7.

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