QCLAS-based vehicle-mounted cruise gas leakage monitoring device and monitoring method

Abstract

The invention discloses a QCLAS-based vehicle-mounted cruise gas leakage monitoring device and monitoring method, and relates to the field of gas leakage monitoring. According to the vehicle-mounted cruising gas leakage monitoring method based on the QCLAS, when an inspection vehicle cruises, a laser control module obtains the temperature value of each time point in real time, temperature modulation processing and current wavelength modulation processing are carried out respectively, and laser is emitted after modulation processing; receiving laser emitted by the laser control module through a detector receiving module; according to the invention, through real-time temperature modulation and current wavelength modulation processing, the monitoring method can rapidly and accurately adjust laser parameters so as to adapt to environmental changes and characteristics of target gas, and the monitoring accuracy is improved. Therefore, the response speed of the system is increased, the measurement precision is enhanced, and gas leakage can be effectively monitored even under the condition that a vehicle moves at a high speed.

Description

Technical Field

[0001] The present invention relates to the field of gas leakage monitoring, and in particular to a QCLAS-based vehicle-mounted cruise gas leakage monitoring device and a monitoring method. Background Art

[0002] Gas leak monitoring is a critical area of ​​safety and environmental protection, impacting personnel safety, asset protection, and environmental protection. This is particularly true in sectors such as urban gas, petrochemicals, and gas transmission pipelines. Early detection and timely treatment of leaks are crucial for preventing accidents and reducing pollution. However, traditional leak detection technologies often suffer from low sensitivity, long response times, or the inability to detect leaks in real time, especially in mobile and expansive environments.

[0003] Quantum Cascade Laser Absorption Spectroscopy (QCLAS) is an advanced spectral analysis technique developed in recent years. It utilizes the properties of quantum cascade lasers (QCLs) to generate laser light of specific wavelengths in the mid-infrared region. This property enables QCLAS to exhibit high specificity and sensitivity in detecting the absorption peaks of specific chemicals, making it ideal for the detection of gas molecules such as methane, ethane, and other hydrocarbon gases.

[0004] The vehicle-mounted cruise gas leak monitoring system utilizes the high sensitivity and specificity of QCLAS. By being installed on a mobile vehicle, it can conduct real-time, continuous gas monitoring on city streets or along pipelines. Compared with traditional fixed monitoring stations or handheld detection equipment, this system can cover a wider area and provide more continuous and systematic data, greatly improving the efficiency and timeliness of monitoring.

[0005] As quantum cascade laser technology matures and its cost decreases, the QCLAS-based on-board cruise gas leak monitoring method is expected to be widely used in multiple fields, especially in situations requiring high sensitivity and large-scale continuous monitoring. This technology can not only improve the efficiency and accuracy of leak detection, but also support intelligent urban management and emergency response systems through timely data analysis and processing.

[0006] In the existing technology, the vehicle-mounted cruise gas leakage equipment based on laser spectral absorption technology on the market are basically of the pump-suction type. The limitations thereof include at least the following problems. First, the absorption pool and the sampling device of the pump-suction type are separated, and the sampling device, the absorption pool and the vacuum pump need to be connected through a soft pipe. The longer pipe increases the volume of the gas path, thereby reducing the gas exchange rate of the absorption pool, increasing the response speed of the equipment, and causing a certain lag. Secondly, the sampling device can only be fixed at a fixed point on the vehicle, and the air inlet of the air pipe is small. It is difficult to capture leaked gas when the vehicle is driving at high speed or when the wind speed is high. Secondly, in order to improve the response speed of the equipment, a large-flow vacuum pump is usually used. However, excessive gas flow will impact the reflector of the absorption pool, bringing high-frequency optical noise, affecting the detection accuracy of the equipment. Secondly, the vehicle-mounted cruise type equipment is usually powered by a vehicle-mounted mobile power supply. Using a large-flow vacuum pump will greatly increase the power of the equipment and reduce the cruising time of the equipment. Summary of the Invention

[0007] In response to the deficiencies in the prior art, the present invention provides a vehicle-mounted cruise gas leak monitoring device and monitoring method based on QCLAS, which solves the problem that the absorption pool and sampling device of the pump-suction type equipment are separated, and the sampling device, absorption pool and vacuum pump need to be connected through a soft pipe. The longer pipe increases the volume of the gas path, thereby reducing the gas exchange rate of the absorption pool, increasing the response speed of the equipment, and causing a certain lag. Secondly, the sampling device can only be fixed at a fixed point on the vehicle, and the air inlet of the air pipe is small. It is difficult to capture leaked gas when the vehicle is driving at high speed or when the wind speed is high. Secondly, in order to improve the response speed of the equipment, a large-flow vacuum pump is usually used. However, excessive gas flow will impact the reflector of the absorption pool, causing high-frequency optical noise and affecting the detection accuracy of the equipment. Secondly, vehicle-mounted cruise-type equipment is usually powered by a vehicle-mounted mobile power supply. Using a large-flow vacuum pump will greatly increase the power of the equipment and reduce the cruising time of the equipment.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: a QCLAS-based on-vehicle cruise gas leakage monitoring device, comprising: a fixed bracket arranged on the front bumper of the inspection vehicle, and also comprising: a monitoring component arranged on the fixed bracket, the monitoring component comprising a laser control module for emitting laser when the inspection vehicle is cruising, a small open-circuit optical path module is arranged on one side wall of the laser control module, one end of the small open-circuit optical path module is connected to a detector receiving module for receiving the laser emitted by the laser control module when the inspection vehicle is cruising, a signal processing module is arranged on one side wall of the detector receiving module, the signal processing module is used to perform gas leakage analysis on the laser emitted by the laser control module received by the detector receiving module when the inspection vehicle is cruising.

[0009] Furthermore, the monitoring component also includes a wireless communication module arranged on a side wall of the laser control module, and the wireless communication module is used to send the gas leakage analysis of the signal processing module to the PC tablet terminal inside the inspection vehicle.

[0010] The QCLAS-based vehicle-mounted cruise gas leakage monitoring method includes the following steps: when the inspection vehicle is cruising, the laser control module obtains the temperature value at each time point in real time and performs temperature modulation processing respectively; after the temperature modulation processing, the current wavelength modulation processing is performed on each time point respectively, and the laser is emitted after the current wavelength modulation processing; the laser emitted by the laser control module is received by the detector receiving module; the laser emitted by the laser control module received by the detector receiving module is analyzed for gas leakage by the signal processing module, and the analysis results are sent to the PC tablet terminal inside the inspection vehicle.

[0011] Furthermore, the specific steps for temperature modulation processing of the temperature value at each time point are as follows: obtaining a preset temperature threshold; performing difference analysis on the temperature value at each time point and the temperature threshold, and inputting the difference analysis results into the PID modulation model to obtain the modulated temperature value at each time point.

[0012] Furthermore, the specific formula for calculating the modulation temperature value at each time point is as follows: ;in, For the The modulation temperature value at each time point, is the preset temperature threshold, For the The temperature value at a time point, is the proportional gain, is the integral gain, is the differential gain, , The number of time points obtained.

[0013] Furthermore, the specific steps for performing current wavelength modulation processing at each time point are as follows: obtain the initial wavelength value, and analyze the modulation depth, first modulation frequency, and modulation phase of the gas to be treated; for each time point, perform a comprehensive analysis of the initial wavelength value, and analyze the modulation depth, first modulation frequency, and modulation phase of the gas to be treated to obtain the current modulation wavelength value at each time point.

[0014] Furthermore, the specific formula for calculating the current modulation wavelength value at each time point is as follows: ;in, For the The current modulation wavelength value at each time point is is the initial wavelength value, is the modulation depth of the gas to be modulated, is pi, is the first modulation frequency of the gas to be treated, is the modulation phase of the gas to be modulated, , The number of time points obtained.

[0015] Furthermore, the specific steps of performing gas leakage analysis on the laser emitted by the laser control module received by the detector receiving module through the signal processing module are as follows: for each time point, the detector receiving module converts the laser signal emitted by the laser control module into an electrical signal; the converted electrical signal at each time point is amplified and filtered by the signal processing module, and demodulated based on a phase-locked amplifier to obtain the second harmonic signal of the gas to be analyzed at each time point; the second harmonic signal of the gas to be analyzed at each time point is input into the analysis model to obtain the concentration value of the gas to be analyzed at each time point; the concentration value of the gas to be analyzed at each time point is compared and analyzed with a preset concentration threshold value, and if there is a time point where the concentration value of the gas to be analyzed is higher than the preset concentration threshold value, it is marked as a gas leak.

[0016] Furthermore, the specific formula for calculating the concentration value of the gas to be analyzed at each time point is as follows: ;in, For the The amplitude value of the second harmonic signal of the gas to be analyzed at a time point, is the initial amplitude value, is the second modulation frequency, is the phase offset, is a natural constant, is the wavelength absorption coefficient, is the optical path length, is the gas concentration, , The number of time points obtained.

[0017] The present invention has the following beneficial effects: (1) The QCLAS-based vehicle cruise gas leak monitoring method can quickly and accurately adjust the laser parameters to adapt to environmental changes and the characteristics of the target gas through real-time temperature modulation and current wavelength modulation processing. This not only improves the response speed of the system, but also enhances the measurement accuracy, making it possible to effectively monitor gas leaks even when the vehicle is moving at high speed.

[0018] (2) The QCLAS-based vehicle cruise gas leak monitoring method ensures the stability of the laser system during the measurement process by continuously monitoring and dynamically adjusting the laser wavelength, thereby reducing the impact of environmental factors on the monitoring results.

[0019] (3) The QCLAS-based vehicle cruise gas leak monitoring method can detect excessive gas concentrations in a timely manner by comparing them with the preset concentration threshold, thereby achieving early warning of potential gas leaks. This not only helps prevent possible safety accidents such as explosions or fires, but also can initiate timely emergency response measures in emergency situations, effectively reducing possible casualties and property losses.

[0020] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the top view of the vehicle-mounted cruise gas leakage monitoring device based on QCLAS of the present invention.

[0022] Figure 2 This is a schematic diagram of the monitoring component structure of the QCLAS-based vehicle-mounted cruise gas leakage monitoring device of the present invention.

[0023] Figure 3 The figure is a schematic diagram of the vehicle cruise gas leak monitoring principle based on QCLAS of the present invention.

[0024] Figure 4 The figure is a flow chart of the vehicle cruise gas leakage monitoring method based on QCLAS of the present invention.

[0025] Figure 5 This is a flowchart of the specific steps of performing temperature modulation processing on the temperature value at each time point in the vehicle cruise gas leakage monitoring method based on QCLAS of the present invention. DETAILED DESCRIPTION

[0026] The embodiment of the present application solves the problem of separation of the absorption pool and the sampling device of the pump-suction type equipment through an on-board cruise gas leakage monitoring device and a monitoring method based on QCLAS. The sampling device, the absorption pool and the vacuum pump need to be connected through a soft pipe. The longer pipe increases the volume of the gas path, thereby reducing the gas exchange rate of the absorption pool, increasing the response speed of the equipment, and causing a certain lag. Secondly, the sampling device can only be fixed at a fixed point on the vehicle, and the air inlet of the air pipe is small. It is difficult to capture leaked gas when the vehicle is driving at high speed or when the wind speed is high. Secondly, in order to improve the response speed of the equipment, a large-flow vacuum pump is usually used. However, excessive gas flow will impact the reflector of the absorption pool, causing high-frequency optical noise and affecting the detection accuracy of the equipment. Secondly, on-board cruise-type equipment is usually powered by an on-board mobile power supply. Using a large-flow vacuum pump will greatly increase the power of the equipment and reduce the cruising time of the equipment.

[0027] The overall approach to the problems in the embodiments of this application is as follows: During the patrol of the inspection vehicle, the temperature at each time point is first acquired in real time and temperature modulated, followed by current wavelength modulation to ensure accurate adjustment of the laser wavelength to adapt to changes in ambient temperature and the detection requirements of specific gases. After modulation, the laser control module 201 emits a laser, and the detector receiving module 203 captures the reflected or scattered laser signal. The laser signal received by the detector is converted into an electrical signal, which is then amplified and filtered. The processed signal is demodulated using a phase-locked amplifier to obtain the second harmonic signal of the gas to be analyzed. These second harmonic signals are input into the analysis model, and the gas concentration at each time point is calculated and compared with the preset threshold to determine whether there is a gas leak.

[0028] See also Figure 1-3 An embodiment of the present invention provides a technical solution: a QCLAS-based vehicle-mounted cruise gas leak monitoring device, comprising: a fixed bracket 1 arranged on the front bumper of a patrol vehicle, and also comprising: a monitoring component 2 arranged on the fixed bracket 1, the monitoring component 2 comprising a laser control module 201 for emitting a laser of a specific wavelength when the patrol vehicle is cruising, a small open-circuit optical path module 202 being arranged on one side wall of the laser control module 201, one end of the small open-circuit optical path module 202 being connected to a detector receiving module 203 for receiving the laser of a specific wavelength emitted by the laser control module 201 when the patrol vehicle is cruising, a signal processing module 204 being arranged on one side wall of the detector receiving module 203, the signal processing module 204 being used to perform gas leakage analysis on the laser of a specific wavelength emitted by the laser control module 201 and received by the detector receiving module 203 when the patrol vehicle is cruising.

[0029] The monitoring component 2 further includes a wireless communication module 205 disposed on a side wall of the laser control module 201 , and the wireless communication module 205 is used to send the gas leakage analysis of the signal processing module 204 to the PC tablet terminal inside the inspection vehicle via WiFi.

[0030] Its working principle is: when the vehicle is cruising, the monitoring component 2 reports the methane and ethane concentrations in the air on the vehicle's patrol path to the handheld PC tablet terminal inside the vehicle in real time through WiFi. At the same time, the data is also sent to the cloud server in real time for remote viewing. The monitoring component 2 consists of a laser control module 201, a small open-circuit optical path module 202, a detector receiving module 203, a signal processing module 204, and a wireless communication module 205. The laser control module 201 completes the drive of the QCL laser quantum cascade laser, including the laser temperature control TEC and modulation current LD control. The temperature control makes The PID controller is constructed using the MAX1978 chip, which integrates an ultra-low drift chopper operational amplifier and an integral amplifier. By optimizing the PID parameter proportional, integral, and differential gain coefficients, high temperature stability is maintained. The modulated current signal uses a low-frequency sawtooth scanning signal and a high-frequency sinusoidal modulation signal, which are simultaneously loaded onto the laser drive current using an adder circuit. The laser wavelength is modulated by the current signal, allowing the laser to scan within a specific wavelength range. The small open-circuit optical path module 202 is designed with an optical path of 50 cm, and a collimating lens assembly is used to adjust the divergence of the output light from the laser control module 201. The angle and spot size make the spot at the detector receiving module 203 three times the size of the detector array. The shorter optical path and larger spot are to ensure that the laser emitted by the monitoring component 2 during the rapid driving of the vehicle can still be received by the detector receiving module 203 to improve the stability of the equipment. At the same time, the beam shaping element is used to adjust the spot shape so that its energy is in a standard normal distribution to reduce the optical interference generated by the optical path module and improve the sensitivity of the equipment. After the generated laser signal is absorbed by the gas medium in the small open-path optical path module 202, the detector in the detector receiving module 203 uses The detector is an InAs / InAsSb mid-infrared detector developed by VIGO. It uses 2TE cooling to control the temperature of the detector receiving module 203 to -40°C to improve the detector response. The detector converts the optical signal into an electrical signal, which is then amplified and filtered by the signal processing module 204 and demodulated using a phase-locked amplifier to obtain its second harmonic signal. The gas concentration can then be measured based on the relationship between the second harmonic signal and the gas concentration. After calibration, the monitoring component 2 sends the detected gas concentration to the PC tablet terminal inside the vehicle via WiFi through the wireless communication module 205.

[0031] A near-infrared light source multiple reflection scheme can also be used to improve detection sensitivity by increasing the absorption optical path. However, its disadvantage is that the multiple reflection light spot is a point light source, and slight deformation of the optical path structure in the form of multiple reflections will cause a large offset in the optical path, causing the system to fail to work and poor stability.

[0032] See also Figure 4The QCLAS-based vehicle-mounted cruise gas leakage monitoring method includes the following steps: when the inspection vehicle is cruising, the laser control module 201 obtains the temperature value at each time point in real time and performs temperature modulation processing respectively; after the temperature modulation processing, the current wavelength modulation processing is performed on each time point respectively, and the laser is emitted after the current wavelength modulation processing; the laser emitted by the laser control module 201 is received by the detector receiving module 203; the laser emitted by the laser control module 201 received by the detector receiving module 203 is analyzed for gas leakage by the signal processing module 204, and the analysis results are sent to the PC tablet terminal inside the inspection vehicle, and the relevant staff are notified at the same time.

[0033] Specifically, if Figure 5 As shown, the specific steps for temperature modulation processing of the temperature value at each time point are as follows: obtaining a preset temperature threshold; performing difference analysis on the temperature value at each time point and the temperature threshold, and inputting the difference analysis results into the PID modulation model to obtain the modulated temperature value at each time point.

[0034] The specific formula for calculating the modulation temperature value at each time point is as follows: ;in, For the The modulation temperature value at each time point, is the preset temperature threshold, For the The temperature value at a time point, is the proportional gain, is the integral gain, is the differential gain, , The number of time points obtained.

[0035] 、 、 This can be achieved through the experimental method Ziegler-Nichols Tuning analysis, which has two main tuning rules: Open-loop method: Record the open-loop response of the system from steady state to a certain control input (such as a step input), find the reaction delay time and time constant from the response curve, and then calculate the gain.

[0036] Closed-loop method: Set the proportional gain and differential gain to 0, increase the integral gain until the system exhibits stable periodic oscillation (critical gain), record the critical oscillation period, and use the critical oscillation to analyze the gain.

[0037] In this embodiment, the Ziegler-Nichols adjustment method provides a fast and effective means to set the parameters of the PID controller, especially when deploying a new system or adjusting an existing system. Through this method, a reasonable control effect can be quickly achieved without the need for tedious manual adjustment. The rapid parameter setting enables the system to operate stably in a short period of time, which is especially important for vehicle-mounted systems because they often operate in a changing external environment and need to be able to adapt quickly to new operating conditions. By optimizing the PID parameters, the dynamic response of the system is improved, and the changes in the temperature set value can be tracked more accurately, thereby ensuring the modulation accuracy of the laser. The enhanced system responsiveness not only improves the monitoring accuracy, but also can quickly detect gas leaks. Quick response is crucial for preventing possible safety accidents. The PID parameters adjusted by the Ziegler-Nichols method can effectively reduce the overshoot and oscillation of the system, which is very important for maintaining the stability of the system under changing environmental conditions. The stability of the system directly affects the quality of laser emission and the subsequent gas detection accuracy. A stable control system can ensure reliable gas leak detection even in complex or extreme environmental conditions. Once the PID parameters are effectively set by the Ziegler-Nichols method, daily maintenance requirements and adjustment frequency will be greatly reduced, reducing long-term operating costs and the overall maintenance burden of the system, making the on-board cruise gas leak monitoring system more economical and practical.

[0038] Specifically, the specific steps for performing current wavelength modulation processing at each time point are as follows: obtaining the initial wavelength value, and analyzing the modulation depth, first modulation frequency, and modulation phase of the gas to be treated (methane and ethane); for each time point, performing a comprehensive analysis of the initial wavelength value, and analyzing the modulation depth, first modulation frequency, and modulation phase of the gas to be treated (methane and ethane) to obtain the current modulation wavelength value at each time point.

[0039] The specific formula for calculating the current modulation wavelength value at each time point is as follows: ;in, For the The current modulation wavelength value at each time point is is the initial wavelength value, which is the wavelength of the laser when there is no modulation. It is pre-set according to the absorption characteristics of the target gas. is the modulation depth of the target gas (methane and ethane), which is the maximum amplitude of wavelength modulation, indicating the maximum amount that the wavelength can deviate from the fundamental wavelength. The modulation depth should be sufficient to cover the main absorption peaks from methane to ethane, while trying to avoid exceeding this range to reduce background noise. is pi, is the first modulation frequency of the target gas (methane and ethane), which determines the rate of wavelength change, that is, the number of wavelength change cycles per second. The specific frequency may depend on the response speed of the laser system and the sampling rate of the detection equipment. For example, it can be set to tens to hundreds of hertz to ensure effective scanning. is the modulation phase of the gas (methane and ethane), which determines the starting angle of wavelength modulation and can help synchronize the starting point of wavelength modulation. , The number of time points obtained.

[0040] Among them, for the initial wavelength value In this example, the wavelength is selected for methane and ethane, as their spectral absorption peaks are typically located in the mid-infrared region. For example, methane has a significant absorption peak at 3.31 microns (λ = 3310 nanometers), while ethane also has a strong absorption peak near 3.35 microns. Therefore, a central wavelength that covers both absorption peaks is selected as the initial wavelength.

[0041] The modulation depth determines the range of variation of the laser output wavelength, which should be sufficient to cover the absorption linewidth of the target gas. Generally, the modulation depth is selected to be slightly greater than or equal to the Full Width at Half Maximum (FWHM) of the gas absorption line. This ensures that the entire absorption peak is fully scanned, thereby improving the accuracy of the measurement.

[0042] The selection of the first modulation frequency is usually based on the system response time and the required measurement speed: a frequency that is too high may lead to insufficient system response, while a frequency that is too low may slow down the measurement speed. In gas concentration measurement, the modulation frequency is usually selected in the range of tens to hundreds of hertz. This is a compromise that can ensure sufficient system response while maintaining a fast measurement update speed.

[0043] Modulation phase is often used to optimize signal detection and ensure signal separation from system noise: adjusting the modulation phase can help distinguish the signal from the target gas from background noise, especially in the presence of external disturbances or a mixture of multiple gases. Phase adjustment usually needs to be optimized through experimentation to find the phase setting that produces the maximum signal contrast.

[0044] A specific example of calculating the current modulation wavelength is as follows, with the following data: ; ; ; (i.e. 45°); Now calculate the current modulation wavelength value at the first time point based on the above data, that is, substitute the data into the formula to obtain: .

[0045] In this embodiment, through precise control of modulation depth and frequency, the laser can cover the spectral absorption peaks of methane and ethane. This coverage ensures maximum interaction between the laser and gas molecules, thereby improving the sensitivity of detection and reducing the possibility of false positives or false negatives. Accurately modulated wavelength can maximize the intensity of the absorption signal, which is especially important for tracking low-concentration gas leaks. By adjusting the modulation frequency and phase, the system can adapt to different environmental conditions and external interferences, such as temperature fluctuations and mechanical vibrations, which is particularly critical in vehicle-mounted systems. Appropriate frequency and phase settings can help the system distinguish between real signals and noise, especially in high-speed inspection vehicle environments. Optimization of the modulation phase ensures accurate gas detection even in complex backgrounds, thereby avoiding signal distortion caused by phase mismatch. Signal distortion, selecting the appropriate modulation frequency ensures that the system can quickly respond to environmental changes and update data in a timely manner, which is critical for real-time monitoring of gas leaks. Fast response time means that when a potential leak is detected, the system can immediately alarm and take corresponding safety measures. Fast and accurate wavelength modulation also means that the system can complete multi-point detection in a shorter time, improving inspection efficiency. This precise wavelength modulation processing method effectively solves the technical challenge of how to continuously perform high-precision gas monitoring under mobile conditions, especially in vehicle-mounted systems. It can maintain high-performance monitoring under different environmental conditions and different gas concentrations, ensuring the wide applicability and reliability of the system. Through this method, early warning of gas leaks in complex environments can be achieved, thereby significantly reducing the safety risks caused by gas leaks.

[0046] Specifically, the specific steps of performing gas leak analysis on the laser emitted by the laser control module 201 and received by the detector receiving module 203 through the signal processing module 204 are as follows: for each time point, the detector receiving module 203 converts the laser signal emitted by the laser control module 201 into an electrical signal; the converted electrical signal at each time point is amplified and filtered by the signal processing module 204, and demodulated based on a phase-locked amplifier to obtain the second harmonic signal of the gas to be analyzed (methane and ethane) at each time point; the second harmonic signal of the gas to be analyzed (methane and ethane) at each time point is input into the analysis model to obtain the concentration value of the gas to be analyzed (methane and ethane) at each time point; the concentration value of the gas to be analyzed (methane and ethane) at each time point is compared and analyzed with a preset concentration threshold value, and if there is a time point where the concentration value of the gas to be analyzed (methane and ethane) is higher than the preset concentration threshold value, it is marked as a gas leak.

[0047] The specific formula for calculating the concentration value of the gas to be analyzed (methane and ethane) at each time point is as follows: ;in, For the The amplitude value of the second harmonic signal of the gas to be analyzed (methane and ethane) at each time point, is the initial amplitude value, is the second modulation frequency (angular frequency, the selection of modulation frequency is usually based on the dynamic characteristics of the system and the required response speed, it can be selected according to the natural frequency of the system or through optimization experiments to ensure the stability and fast response of the control system), is the phase offset (the phase is usually determined experimentally during system debugging or initialization. In actual operation, the phase needs to be adjusted to achieve optimal system performance, especially when synchronizing with other periodic signals or interference). is a natural constant, is the wavelength absorption coefficient, is the optical path length (the length of the path that the emitted light travels), is the gas concentration, , The number of time points obtained.

[0048] In this embodiment, the concentrations of methane and ethane gases are measured, so the wavelength absorption coefficients of methane and ethane gases need to be brought into the model respectively. The amplitude value of the second harmonic signal at each time point is a known quantity, and all other parameters except the methane and ethane gas concentrations are known quantities. Therefore, by solving the model, the methane and ethane gas concentrations can be obtained.

[0049] Moreover, for methane and ethane gases, their absorption coefficients can be directly looked up from scientific literature or public databases (such as the HITRAN database).

[0050] In this embodiment, after the laser emitted by the laser control module is absorbed by the target gas (methane and ethane), the reflected or transmitted light is received by the detector and converted into an electrical signal. The converted electrical signal is amplified and filtered by the signal processing module to enhance the signal quality and reduce environmental noise and other interference. The phase-locked amplifier technology is used to extract the second harmonic component corresponding to the modulation frequency from the amplified signal. The key to this step is to improve the signal-to-noise ratio of the signal. The obtained second harmonic signal is input into the analysis model to calculate the gas concentration at each time point. Using a specific mathematical model and formula, based on the amplitude, absorption coefficient, optical path length and other parameters of the second harmonic signal, the methane and ethane concentrations at each time point are calculated. The calculated concentration is compared with the preset safety threshold. If the concentration exceeds the threshold, it is determined to be a leak, and corresponding marking and alarm are performed. This method uses automated signal processing The system realizes real-time monitoring through the use of the analysis model, which can quickly identify leakage events and greatly improve the response speed and processing efficiency. The second harmonic technology and phase-locked amplifier demodulation are used to enhance the accuracy of the detection signal and the reliability of the system, reduce the possibility of false alarms and missed alarms, and ensure the accuracy of the monitoring results. By adjusting the modulation frequency and phase, the system can flexibly adapt to different environmental conditions and different gas characteristics. This adaptability is particularly important for vehicle-mounted systems because they often need to operate in a changing environment. By timely and accurately monitoring and identifying gas leaks, the system can effectively prevent possible safety accidents such as explosions or fires, thereby protecting personnel and property safety, providing high-quality monitoring data, supporting data-based decision-making, and helping operation managers optimize maintenance plans and emergency response strategies. Through effective gas leak monitoring and control, environmental pollution is reduced and environmental protection standards and regulatory requirements are met.

[0051] In summary, this application has at least the following effects: Through real-time temperature modulation and current wavelength modulation processing, this monitoring method can quickly and accurately adjust laser parameters to adapt to environmental changes and the characteristics of the target gas. This not only improves the system's response speed, but also enhances the measurement accuracy, making it possible to effectively monitor gas leaks even when the vehicle is moving at high speed.

[0052] By continuously monitoring and dynamically adjusting the laser wavelength, the stability of the laser system during the measurement process is ensured, thereby reducing the impact of environmental factors on the monitoring results.

[0053] By comparing with preset concentration thresholds, this method can promptly detect excessive gas concentrations, thereby providing early warning of potential gas leaks. This not only helps prevent possible safety accidents such as explosions or fires, but also enables timely emergency response measures to be initiated in emergency situations, effectively reducing possible casualties and property losses.

[0054] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0055] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. QCLAS-based on-board cruise gas leak monitoring device, including: A fixing bracket (1) arranged on the front bumper of an inspection vehicle, characterized in that it also comprises: A monitoring component (2) is arranged on a fixed bracket (1), the monitoring component (2) comprising a laser control module (201) for emitting laser light when a patrol vehicle is cruising, a small open-circuit optical path module (202) is arranged on a side wall of the laser control module (201), one end of the small open-circuit optical path module (202) is connected to a detector receiving module (203) for receiving laser light emitted by the laser control module (201) when the patrol vehicle is cruising, a signal processing module (204) is arranged on a side wall of the detector receiving module (203), and the signal processing module (204) is used to perform gas leakage analysis on the laser light emitted by the laser control module (201) and received by the detector receiving module (203) when the patrol vehicle is cruising.

2. The QCLAS-based vehicle-mounted cruise gas leakage monitoring device according to claim 1 is characterized in that: The monitoring component (2) further comprises a wireless communication module (205) arranged on a side wall of the laser control module (201), wherein the wireless communication module (205) is used to send the gas leakage analysis of the signal processing module (204) to a PC tablet terminal inside the inspection vehicle.

3. A vehicle cruise gas leakage monitoring method based on QCLAS, using a vehicle cruise gas leakage monitoring device based on QCLAS according to any one of claims 1-2, characterized in that: The following steps are involved: When the inspection vehicle is cruising, the laser control module (201) acquires the temperature value at each time point in real time and performs temperature modulation processing respectively; After the temperature modulation process, a current wavelength modulation process is performed at each time point, and laser light is emitted after the current wavelength modulation process; receiving laser light emitted by the laser control module (201) through a detector receiving module (203); The laser emitted by the laser control module (201) and received by the detector receiving module (203) is analyzed for gas leakage through the signal processing module (204), and the analysis result is sent to a PC tablet terminal inside the inspection vehicle.

4. The vehicle cruise gas leakage monitoring method based on QCLAS according to claim 3 is characterized in that: The specific steps for temperature modulation processing of the temperature value at each time point are as follows: Get the preset temperature threshold; The temperature value at each time point is subjected to difference analysis with the temperature threshold, and the difference analysis result is input into the PID modulation model to obtain the modulation temperature value at each time point.

5. The QCLAS-based vehicle cruise gas leakage monitoring method according to claim 4 is characterized in that: The specific formula for calculating the modulation temperature value at each time point is as follows: ； in, For the The modulation temperature value at each time point, is the preset temperature threshold, For the The temperature value at a time point, is the proportional gain, is the integral gain, is the differential gain, , is the number of time points obtained.

6. The vehicle-mounted cruise gas leakage monitoring method based on QCLAS according to claim 3 is characterized in that: The specific steps of performing current wavelength modulation processing at each time point are as follows: Obtaining the initial wavelength value, and analyzing the modulation depth, first modulation frequency, and modulation phase of the gas to be treated; At each time point, the initial wavelength value is analyzed respectively, and the modulation depth, the first modulation frequency, and the modulation phase of the gas to be used are comprehensively analyzed to obtain the current modulation wavelength value at each time point.

7. The vehicle-mounted cruise gas leakage monitoring method based on QCLAS according to claim 6 is characterized in that: The specific formula for calculating the current modulation wavelength value at each time point is as follows: ； in, For the The current modulation wavelength value at a time point is is the initial wavelength value, is the modulation depth of the gas to be treated, is the circumference of a circle, is the first modulation frequency of the gas to be treated, is the modulation phase of the gas to be modulated, , is the number of time points obtained.

8. The vehicle-mounted cruise gas leakage monitoring method based on QCLAS according to claim 3 is characterized in that: The specific steps of performing gas leakage analysis on the laser emitted by the laser control module (201) and received by the detector receiving module (203) through the signal processing module (204) are as follows: At each time point, the detector receiving module (203) converts the received laser signal emitted by the laser control module (201) into an electrical signal; The converted electrical signal at each time point is amplified and filtered by a signal processing module (204), and demodulated based on a phase-locked amplifier to obtain a second harmonic signal of the gas to be analyzed at each time point; Inputting the second harmonic signal of the gas to be analyzed at each time point into the analysis model to obtain the concentration value of the gas to be analyzed at each time point; The concentration value of the analyzed gas at each time point is compared and analyzed with the preset concentration threshold. If there is a time point when the concentration value of the analyzed gas is higher than the preset concentration threshold, it is marked as a gas leak.

9. The QCLAS-based vehicle cruise gas leakage monitoring method according to claim 8 is characterized in that: The specific formula for calculating the concentration value of the gas to be analyzed at each time point is as follows: ； in, For the The amplitude value of the second harmonic signal of the gas to be analyzed at a time point, is the initial amplitude value, is the second modulation frequency, is the phase offset, is a natural constant, is the wavelength absorption coefficient, is the optical path length, is the gas concentration, , is the number of time points obtained.

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