Buried gas pipe network combustible gas monitoring and early warning system and method

Abstract

The invention discloses a buried gas pipe network combustible gas monitoring and early warning system and method, and belongs to the field of monitoring and early warning, the buried gas pipe network combustible gas monitoring and early warning system comprises a sensor module used for monitoring the temperature of an absolute key point, a high risk area and a conventional pipeline and the concentration of combustible gas; the communication module is used for transmitting the temperature monitored by the sensor module and the concentration of the combustible gas to the monitoring center CPU; the monitoring center CPU is used for judging whether a combustible gas leakage risk exists or not on the basis of the temperature and the concentration of the combustible gas in combination with the spatio-temporal data and the environmental data, and compared with the prior art, the beneficial effects are that whether the combustible gas leakage risk exists or not is judged on the basis of the collected temperature and the concentration of the combustible gas in combination with the spatio-temporal data and the environmental data; the method reduces misjudgment caused by interference, is high in precision, can predict risks based on combustible gas concentration changes and temperature changes, and is high in intelligence.

Description

Technical Field

[0001] The present invention belongs to the field of monitoring and early warning, and in particular relates to a combustible gas monitoring and early warning system and method for an underground gas pipeline network. Background Art

[0002] Underground gas pipeline networks are crucial infrastructure for urban gas transportation, and their safety is directly linked to public safety. Current combustible gas monitoring relies primarily on sensors and other equipment to detect gas concentrations. When concentrations reach a preset threshold, a leak risk is identified and a response mechanism is triggered.

[0003] However, this solution has the following limitations: First, it cannot identify potential risks where concentrations gradually increase but do not reach the threshold; second, environmental influences interfere with the detection of combustible gas concentrations, leading to misjudgments (for example, 1. Methane is the main component of natural gas, and many sensors used to detect methane are not absolutely specific. Some types of sensors may also respond to carbon monoxide, nitrogen oxides, and incompletely burned hydrocarbons in automobile exhaust. Even if the sensor is mainly targeted at methane, high concentrations of other reducing gases may also cause signal interference. 2. Ambient wind quickly blows away and dilutes combustible gases escaping from tiny leaks in buried pipelines). This shows that the existing monitoring system still needs to be improved in terms of accuracy and intelligence, and there is an urgent need to achieve more accurate risk warnings through technological improvements. Summary of the Invention

[0004] Based on this, it is necessary to provide a combustible gas monitoring and early warning system and method for an underground gas pipeline network to address the above-mentioned problems.

[0005] The embodiment of the present invention is implemented as follows: a combustible gas monitoring and early warning system for an underground gas pipeline network, comprising:

[0006] Sensor modules are used to monitor the temperature and concentration of combustible gases at absolutely critical points, high-risk areas, and conventional pipelines;

[0007] Communication module, used to transmit the temperature and combustible gas concentration monitored by the sensor module to the monitoring center CPU;

[0008] The monitoring center CPU is used to determine whether there is a risk of combustible gas leakage based on temperature and combustible gas concentration, combined with spatiotemporal data (such as gradual increase in concentration over time, location in a vehicle exhaust interference area, etc.) and environmental data (such as wind speed and direction, etc.), and to issue an alarm when there is a risk of combustible gas leakage.

[0009] In one embodiment, the present invention provides a combustible gas monitoring and early warning system for an underground gas pipeline network, wherein the absolutely critical points include a pressure regulating station, a valve well, a key interface, and a crossing section;

[0010] An infrared absorption sensor is placed above key equipment (such as pressure regulators and filters) in the pressure regulating station, an infrared absorption sensor is placed at each of the inlet and outlet pipe interfaces, and multiple (usually 2 or 3) infrared absorption sensors are placed at the environmental concentration monitoring points;

[0011] At least one infrared absorption sensor is installed at the top of the valve well (methane accumulation area), and one infrared absorption sensor is installed directly above each flange and valve interface;

[0012] A TDLAS laser sensor is installed at the interface of key interfaces (such as pipe conversion joints, which can be the transition connection between steel pipes and PE pipes; third-party construction area interfaces, which can be the casing isolation interfaces used when crossing municipal drainage pipes / thermal pipes). A TDLAS laser sensor is installed at each end of the crossing section (such as when crossing roads or rivers).

[0013] In one embodiment, the present invention provides a combustible gas monitoring and early warning system for an underground gas pipeline network. High-risk areas include densely populated areas (such as schools and hospitals) and sensitive facility areas (such as subways and chemical plants);

[0014] Bury temperature-sensing optical cables directly above the pipeline in crowded areas to monitor temperature anomalies (vibration-sensing optical cables can also be buried to monitor leakage vibration signals);

[0015] TDLAS laser sensors are deployed at the boundaries of sensitive facility areas (to monitor large-scale gas diffusion); infrared absorption sensors are deployed at key nodes (such as raw material pipeline interfaces in chemical plant areas, explosion-proof wall penetration pipe sections, ventilation shaft connection points in subway tunnel areas, etc.) (double protection).

[0016] In one embodiment, the present invention provides a combustible gas monitoring and early warning system for an underground gas pipeline network, wherein conventional pipelines include a main pipeline and a secondary pipeline;

[0017] Temperature-sensing optical cables are laid along the entire trunk pipeline to monitor pipeline temperature changes in real time;

[0018] One catalytic combustion sensor is installed at the tee and elbow of the secondary trunk pipe; one catalytic combustion sensor is installed at the interface of the old pipe section; and one catalytic combustion sensor is installed at the extension point of the valve well (catalytic combustion sensors have low cost).

[0019] In one embodiment, the present invention provides a method for monitoring and warning combustible gas in an underground gas pipeline network, which is applied to the above-mentioned underground gas pipeline network combustible gas monitoring and warning system. The underground gas pipeline network combustible gas monitoring and warning method comprises the following steps:

[0020] Obtain the temperature and combustible gas concentration at absolutely critical points, high-risk areas, and conventional pipelines of the underground gas pipeline network;

[0021] Based on temperature, combustible gas concentration, combined with spatiotemporal data and environmental data, determine whether there is a combustible gas leakage risk and classify the risk level;

[0022] Trigger different alarm mechanisms based on risk levels.

[0023] In one embodiment, the present invention provides a method for monitoring and early warning of combustible gas in an underground gas pipeline network. The method comprises the following steps: determining whether there is a combustible gas leakage risk based on temperature and combustible gas concentration, combined with spatiotemporal data and environmental data, and classifying the risk level.

[0024] Real-time monitoring of combustible gas concentration and temperature at each node. A combustible gas concentration > 10% LEL (lower explosion limit) or a temperature rise > 0.5°C / 10m is marked as a Level 1 risk point. Spatial analysis is performed to pre-determine areas with high exhaust gas interference (intersections / tunnel exits). In these areas, the concentration judgment threshold is increased by 5% LEL (for example, a 10% potential risk in ordinary areas and a 15% potential risk in areas with high exhaust gas interference).

[0025] Perform time series analysis. If the combustible gas concentration gradient is greater than 5%LEL / minute for three consecutive cycles (e.g., 5 seconds / cycle), or the temperature rise rate is greater than 0.2°C / minute for three consecutive cycles, it is determined to be a time series leakage diffusion trend. Perform spatial verification. If the combustible gas concentration is greater than 15%LEL at three adjacent nodes (spacing ≤ 50m), or the temperature rise at two adjacent nodes is greater than 0.5°C / 10m, it is determined to be a spatial leakage area.

[0026] Conduct environmental analysis, obtain wind speed and direction data, activate the exhaust diffusion model, and adjust the monitoring range based on wind speed to use combustible gas concentration and temperature data (for example, when wind speed is greater than 3m / s, use data from a core area with a radius of 50% of the original monitoring range to eliminate edge interference, and increase the weight of concentration / temperature data in the core area to 80%; when wind speed is greater than 5m / s, increase the temperature rise judgment threshold to 1.0℃ / 10m to reduce interference from wind cooling effects);

[0027] Risk levels are divided into: Level 1 risk: combustible gas concentration in conventional areas is >10%LEL or combustible gas concentration in areas with high incidence of exhaust gas interference is >15%LEL or temperature rise is >0.5℃ / 10m; Level 2 risk: based on the level 1 risk, there is a temporal leakage diffusion trend or spatial leakage area; Level 3 risk: combustible gas concentration in conventional areas is >50%LEL or combustible gas concentration in areas with high incidence of exhaust gas interference is >55%LEL or leakage area is >10㎡ or temperature rise is >2.0℃ / 10m.

[0028] In one embodiment, the present invention provides a method for monitoring and early warning of combustible gas in an underground gas pipeline network. The method includes real-time monitoring of the combustible gas concentration and temperature at each node, marking a combustible gas concentration greater than 10% LEL or a temperature rise greater than 0.5°C / 10m as a first-level risk point; performing spatial analysis, presetting areas with high incidence of exhaust gas interference, and raising the concentration judgment threshold by 5% LEL in these areas, further comprising:

[0029] Traffic flow in areas with high incidence of exhaust gas interference is counted through intersection cameras, and the impact of new energy vehicles (no exhaust gas) is eliminated through license plate recognition. The size of 5%LEL is adjusted based on the traffic flow.

[0030] In one embodiment, the present invention provides a method for monitoring and early warning of combustible gas in an underground gas pipeline network. The steps of performing environmental analysis, obtaining wind speed and direction data, activating an exhaust gas diffusion model, and adjusting the monitoring range based on wind speed using combustible gas concentration and temperature data further include:

[0031] Real-time fusion of meteorological radar and rain gauge data. When rainfall is greater than 10 mm / h, the dynamic attenuation mechanism for temperature rise determination is activated. Based on the negative correlation between rainfall intensity and soil heat conductivity, the risk assessment of temperature rise data is dynamically adjusted. After the rain stops, the risk assessment of temperature rise data is restored based on the soil type (clay has stronger hysteresis than sand).

[0032] In one embodiment, the present invention provides a method for monitoring and early warning of combustible gas in an underground gas pipeline network, wherein the risk level is divided into the following steps: Level 1 risk: combustible gas concentration in conventional areas is greater than 10% LEL or combustible gas concentration in areas with high incidence of exhaust gas interference is greater than 15% LEL or temperature rise is greater than 0.5°C / 10m; Level 2 risk: based on the level 1 risk, there is a temporal leakage diffusion trend or a spatial leakage area; Level 3 risk: combustible gas concentration in conventional areas is greater than 50% LEL or combustible gas concentration in areas with high incidence of exhaust gas interference is greater than 55% LEL or leakage area is greater than 10 m2 or temperature rise is greater than 2.0°C / 10m, and the steps further include:

[0033] The underground gas pipeline negative pressure pump (-0.1MPa) in the area identified as a secondary risk area will be started to forcibly extract soil gas for detection; the concentration of leaking combustible gas (<1%LEL) will be amplified to actively create detection conditions to improve sensitivity, and the pressure will be reset immediately after confirmation to avoid pipeline deformation.

[0034] In one embodiment, the present invention provides a method for monitoring and early warning of combustible gas in an underground gas pipeline network, wherein the steps of triggering different alarm mechanisms based on risk levels specifically include:

[0035] In case of level 1 risk, locate the level 1 risk point and generate an inspection work order (30-minute response time limit);

[0036] In case of level 2 risk, the leak point coordinates and concentration gradient curve will be sent to the emergency repair team; video surveillance within 500m of the leak point will be automatically linked;

[0037] When the risk reaches level 3, shut down the valves of the associated underground gas pipeline network sections (≤30 seconds); activate the sound and light alarm plus voice evacuation command (covering a radius of 200m); and transmit the GIS heat map (including the diffusion model predicted boundary) to the emergency department.

[0038] Compared with the existing technology, the beneficial effects of the present invention are: the present invention determines whether there is a risk of combustible gas leakage based on the collected temperature and concentration of combustible gas, combined with spatiotemporal data and environmental data, reduces misjudgment caused by interference, and has high accuracy. At the same time, it can predict risks based on changes in combustible gas concentration and temperature, and is highly intelligent. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of a combustible gas monitoring and early warning system for an underground gas pipeline network provided by an embodiment of the present invention.

[0040] Figure 2 A schematic diagram of absolutely key points provided in an embodiment of the present invention.

[0041] Figure 3 A schematic diagram of a high-risk area provided in an embodiment of the present invention.

[0042] Figure 4 A schematic diagram of a conventional pipeline provided in an embodiment of the present invention.

[0043] Figure 5 for Figure 1 A flow chart of a combustible gas monitoring and early warning method for an underground gas pipeline network provided by an embodiment of the present invention.

[0044] Figure 6 A schematic diagram of the process of risk determination and risk level classification provided by an embodiment of the present invention.

[0045] Figure 7 A schematic diagram of a combustible gas concentration determination threshold value for vehicle flow regulation provided in an embodiment of the present invention.

[0046] Figure 8 A schematic diagram of rainfall-adjusted temperature rise risk determination according to an embodiment of the present invention.

[0047] Figure 9 A schematic diagram of actively creating detection conditions provided by an embodiment of the present invention.

[0048] Figure 10 A schematic diagram of the alarm triggering process provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0050] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but unless otherwise specified, these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, a first xx script may be referred to as a second xx script, and similarly, a second xx script may be referred to as a first xx script without departing from the scope of this application.

[0051] In one embodiment, Figure 1 As shown, a combustible gas monitoring and early warning system for an underground gas pipeline network includes:

[0052] Sensor module 1 is used to monitor the temperature and combustible gas concentration at absolutely critical points, high-risk areas, and conventional pipelines;

[0053] Communication module 2, used to transmit the temperature and combustible gas concentration monitored by the sensor module to the monitoring center CPU;

[0054] The monitoring center CPU3 is used to determine whether there is a risk of combustible gas leakage based on temperature and combustible gas concentration, combined with spatiotemporal data (such as gradual increase in concentration over time, location in a vehicle exhaust interference area, etc.) and environmental data (such as wind speed and direction, etc.), and to issue an alarm when there is a risk of combustible gas leakage.

[0055] Sensor module 1 employs a hierarchical targeted monitoring strategy: high-precision infrared absorption sensors and TDLAS laser sensors are used at critical locations to detect early-stage leaks. Distributed temperature-sensing optical cables provide continuous temperature scanning in high-risk areas, combined with TDLAS laser sensors to expand gas monitoring coverage. Conventional pipelines utilize low-cost catalytic combustion sensors to cover leak-prone nodes. Communication module 2 optimizes transmission methods based on scenario requirements: Enclosed spaces (valve wells) utilize low-power LoRaWAN / NB-IoT to ensure a battery life of more than three years; a dedicated fiber-optic network for trunk pipelines ensures real-time transmission of massive temperature data; and TDLAS monitoring points support video linkage via industrial Ethernet, with no restrictions on communication methods. The monitoring center's CPU 3 reduces false alarms through threshold triggering, spatiotemporal gradient analysis, and environmental interference filtering.

[0056] In one embodiment, Figure 2 As shown, a combustible gas monitoring and early warning system for an underground gas pipeline network, the absolute key points include the pressure regulating station, valve well, key interface and crossing section;

[0057] An infrared absorption sensor is placed above key equipment (such as pressure regulators and filters) in the pressure regulating station, an infrared absorption sensor is placed at each of the inlet and outlet pipe interfaces, and multiple (usually 2 or 3) infrared absorption sensors are placed at the environmental concentration monitoring points;

[0058] At least one infrared absorption sensor is installed at the top of the valve well (methane accumulation area), and one infrared absorption sensor is installed directly above each flange and valve interface;

[0059] A TDLAS laser sensor is installed at the interface of key interfaces (such as pipe conversion joints, which can be the transition connection between steel pipes and PE pipes; third-party construction area interfaces, which can be the casing isolation interfaces used when crossing municipal drainage pipes / thermal pipes). A TDLAS laser sensor is installed at each end of the crossing section (such as when crossing roads or rivers).

[0060] Absolutely critical points are focused on areas with the highest probability of leakage: Pressure regulators and filters within the pressure regulating station bear the greatest pressure, and the inlet and outlet are stress concentration points. Therefore, highly interference-resistant infrared absorption sensors are deployed in a 1:1 ratio. Two to three environmental monitoring points provide a concentration gradient. Because methane is less dense than air, infrared absorption sensors are placed atop valve wells, directly above flanges and valves to address the risk of seal failure. TDLAS laser sensors are deployed at key interfaces and crossings. Their open-path monitoring can cover a range of 20 meters, increasing efficiency fivefold compared to point-based detection.

[0061] In one embodiment, Figure 3 As shown, a combustible gas monitoring and early warning system for underground gas pipeline networks is used. High-risk areas include densely populated areas (such as schools and hospitals) and sensitive facility areas (such as subways and chemical plants).

[0062] Bury temperature-sensing optical cables directly above the pipeline in crowded areas to monitor temperature anomalies (vibration-sensing optical cables can also be buried to monitor leakage vibration signals);

[0063] TDLAS laser sensors are deployed at the boundaries of sensitive facility areas (to monitor large-scale gas diffusion); infrared absorption sensors are deployed at key nodes (such as raw material pipeline interfaces in chemical plant areas, explosion-proof wall penetration pipe sections, ventilation shaft connection points in subway tunnel areas, etc.) (double protection).

[0064] Temperature-sensing optical cables are deployed throughout densely populated areas (schools and hospitals). Because temperature anomalies appear before gas accumulation, they can provide early warnings 10-30 minutes in advance. TDLAS laser sensors are deployed along the perimeters of sensitive facilities (chemical plants and subways) to monitor large-scale gas diffusion. Infrared absorption sensors are added to key nodes, such as the raw material pipe joints in chemical plants (corrosion rate > 0.5mm / year), for dual redundancy. Mechanical vibration doubles the risk of leakage in pipe sections penetrating explosion-proof walls. This dual-sensor configuration reduces the missed detection rate to near zero.

[0065] In one embodiment, Figure 4 As shown, a combustible gas monitoring and early warning system for an underground gas pipeline network, conventional pipelines include main pipelines and secondary pipelines;

[0066] Temperature-sensing optical cables are laid along the entire trunk pipeline to monitor pipeline temperature changes in real time;

[0067] One catalytic combustion sensor is installed at the tee and elbow of the secondary trunk pipe; one catalytic combustion sensor is installed at the interface of the old pipe section; and one catalytic combustion sensor is installed at the extension point of the valve well (catalytic combustion sensors have low cost).

[0068] Temperature-sensing optical cables are installed along the entire main pipeline to enable real-time temperature imaging. High-pressure pipeline leaks can diffuse at speeds of up to 2 m / s, requiring global monitoring. On secondary main pipelines, catalytic combustion sensors are deployed at stress concentration points (where wall thinning due to eddy current impact at tees / elbows exceeds 15%), along older pipe sections (where corrosion pit depth exceeds 1.5 mm), and at valve well extension points (where seal failures account for 42%). These sensors, costing only one-third of infrared absorption sensors, are suitable for long-term monitoring in non-submerged environments.

[0069] In one embodiment, Figure 5 As shown, a method for monitoring and warning combustible gas in an underground gas pipeline network is applied to the above-mentioned combustible gas monitoring and warning system for an underground gas pipeline network. The method for monitoring and warning combustible gas in an underground gas pipeline network comprises the following steps:

[0070] Step S1, obtaining the temperature and combustible gas concentration at absolutely critical points, high-risk areas, and conventional pipelines of the underground gas pipeline network;

[0071] Step S2: Based on the temperature and the concentration of the combustible gas, combined with the spatiotemporal data and the environmental data, determine whether there is a risk of combustible gas leakage and classify the risk level;

[0072] Step S3: trigger different alarm mechanisms based on risk levels.

[0073] Step S1 obtains data from all network points to avoid monitoring blind spots; Step S2 integrates exhaust interference correction (spatial), leakage diffusion trend (temporal), and wind cooling / rain effect compensation (environmental) to achieve dynamic risk assessment; Step S3 initiates response according to level (level one manual verification, level two video linkage, level three emergency valve shutdown) to ensure that low risks are not false alarms and high risks are handled in seconds.

[0074] In one embodiment, Figure 6 As shown, a method for monitoring and early warning of combustible gas in an underground gas pipeline network is provided. Step S2 is to determine whether there is a combustible gas leakage risk based on temperature and combustible gas concentration, combined with spatiotemporal data and environmental data, and to classify the risk level. Specifically, the method includes:

[0075] Step S21: Real-time monitoring of the combustible gas concentration and temperature at each node. A combustible gas concentration > 10% LEL (lower explosion limit) or a temperature rise > 0.5°C / 10m is marked as a Level 1 risk point. Spatial analysis is performed, and areas with high exhaust gas interference incidence (intersections / tunnel exits) are pre-set. In these areas, the concentration judgment threshold is increased by 5% LEL (e.g., 10% potential risk in ordinary areas and 15% potential risk in areas with high exhaust gas interference incidence).

[0076] Step S22: Perform a time series analysis. If the combustible gas concentration gradient is greater than 5%LEL / minute for three consecutive cycles (e.g., 5 seconds / cycle), or the temperature rise rate is greater than 0.2°C / minute for three consecutive cycles, it is determined to be a time series leakage diffusion trend. Perform a spatial verification. If the combustible gas concentration is greater than 15%LEL at three adjacent nodes (spacing ≤ 50m), or the temperature rise at two adjacent nodes is greater than 0.5°C / 10m, it is determined to be a spatial leakage area.

[0077] Step S23: Perform environmental analysis, obtain wind speed and direction data, activate the exhaust diffusion model, and adjust the monitoring range based on wind speed to use combustible gas concentration and temperature data (for example, when the wind speed is greater than 3 m / s, use the data from the core area with a radius of 50% of the original monitoring range to eliminate edge interference, and increase the weight of concentration / temperature data in the core area to 80%; when the wind speed is greater than 5 m / s, increase the temperature rise judgment threshold to 1.0°C / 10 m to reduce the interference of wind cooling effect);

[0078] Step S24, risk level classification, level one risk: combustible gas concentration in conventional areas > 10% LEL or combustible gas concentration in areas with high incidence of exhaust gas interference > 15% LEL or temperature rise > 0.5°C / 10m; level two risk: based on the level one risk, there is a temporal leakage diffusion trend or spatial leakage area; level three risk: combustible gas concentration in conventional areas > 50% LEL or combustible gas concentration in areas with high incidence of exhaust gas interference > 55% LEL or leakage area > 10 m2 or temperature rise > 2.0°C / 10m.

[0079] To illustrate the working process, for example, a main pipe passed through the casing interface of a municipal thermal pipe (a key interface), and the pipe was punctured due to construction by an excavator.

[0080] Step S21: Spatial Analysis: The construction site is located at an intersection (a high-incidence area for exhaust emissions), with an initial concentration of 14% LEL (<15% threshold). The system retrieves camera data and finds that fuel-powered vehicles account for 90% of the vehicle population, and that the number of vehicles passing through in 10 minutes reaches 100. The threshold is dynamically adjusted to 14.5% LEL (e.g., 10% + 5% × 90%), so no alarm is triggered.

[0081] Step S22: Timing Verification: The concentration gradient reaches 7%LEL / minute (>5% threshold) for three consecutive cycles, and the temperature rise rate of two nodes within 50 meters is 0.3°C / minute (>0.2% / minute). This is determined to be a time-series leakage diffusion + spatial leakage area.

[0082] Step S23: Environmental compensation: Real-time wind speed is 4m / s (>3m / s). The system shrinks the monitoring range to the core area with a radius of 50%, eliminating the interference of edge data. At this time, the concentration in the core area is 25%LEL.

[0083] Step S24: Risk grading: Core area concentration 25%LEL (Level 1 risk) + spatiotemporal diffusion evidence (Level 2 risk) + combustible gas concentration less than 50%LEL and leakage area 10 m2, comprehensively determined as Level 2 risk.

[0084] In one embodiment, Figure 7 As shown, a method for monitoring and early warning of combustible gas in an underground gas pipeline network, in which step S21 monitors the combustible gas concentration and temperature of each node in real time, and marks a combustible gas concentration greater than 10%LEL or a temperature rise greater than 0.5°C / 10m as a first-level risk point; performs spatial analysis, presets areas with high incidence of exhaust gas interference, and increases the concentration judgment threshold by 5%LEL in areas with high incidence of exhaust gas interference, further comprising:

[0085] Traffic flow in areas with high incidence of exhaust gas interference is counted through intersection cameras, and the impact of new energy vehicles (no exhaust gas) is eliminated through license plate recognition. The size of 5%LEL is adjusted based on the traffic flow.

[0086] Dynamically adjust the concentration threshold to make it more reasonable, bringing the detected combustible gas concentration closer to the actual value. Because fuel vehicle exhaust contains 0.1-2% methane, a fixed threshold can easily cause false alarms at intersections during peak traffic hours. By using license plate recognition to calculate the percentage of fuel vehicles (e.g., >70%), the threshold base is dynamically adjusted based on the number of fuel vehicles passing per unit time (e.g., 5% LEL x percentage of fuel vehicles), allowing the threshold to fluctuate and reducing false alarm rates at intersections.

[0087] In one embodiment, Figure 8As shown, a method for monitoring and early warning of combustible gas in an underground gas pipeline network, wherein step S23 performs environmental analysis, obtains wind speed and direction data, starts an exhaust gas diffusion model, and adjusts the monitoring range based on the wind speed using combustible gas concentration and temperature data, further comprising:

[0088] Real-time fusion of meteorological radar and rain gauge data. When rainfall is greater than 10 mm / h, the dynamic attenuation mechanism for temperature rise determination is activated. Based on the negative correlation between rainfall intensity and soil heat conductivity, the risk assessment of temperature rise data is dynamically adjusted. After the rain stops, the risk assessment of temperature rise data is restored based on the soil type (clay has stronger hysteresis than sand).

[0089] Heavy rainfall (>10 mm / h) increases soil thermal conductivity by 2.5 times (for sandy soil) to 4 times (for clay soil), attenuating the temperature rise signal by 60%-80% for the same leakage rate. A dynamic attenuation mechanism is based on a rainfall intensity-soil type matrix: For sandy soil, the temperature rise is weighted by ×0.4 for every 10 mm / h of rainfall intensity, and ×0.2 for clay soil. After the rain stops, the weight is slowly restored based on the clay soil hysteresis factor (2 h / mm) to prevent missed reports due to residual moisture after rain.

[0090] In one embodiment, Figure 9 As shown, a method for monitoring and early warning of combustible gas in an underground gas pipeline network is provided. In step S24, risk levels are divided into: level 1 risk: combustible gas concentration in conventional areas is greater than 10% LEL or combustible gas concentration in areas with high incidence of exhaust gas interference is greater than 15% LEL or temperature rise is greater than 0.5°C / 10m; level 2 risk: based on the level 1 risk, there is a temporal leakage diffusion trend or a spatial leakage area; level 3 risk: combustible gas concentration in conventional areas is greater than 50% LEL or combustible gas concentration in areas with high incidence of exhaust gas interference is greater than 55% LEL or leakage area is greater than 10 m2 or temperature rise is greater than 2.0°C / 10m. The steps further include:

[0091] The underground gas pipeline negative pressure pump (-0.1MPa) in the area identified as a secondary risk area will be started to forcibly extract soil gas for detection; the concentration of leaking combustible gas (<1%LEL) will be amplified to actively create detection conditions to improve sensitivity, and the pressure will be reset immediately after confirmation to avoid pipeline deformation.

[0092] Secondary risk only indicates the existence of a leakage trend (such as an increase in concentration gradient or abnormal spatial correlation), but it may be a simultaneous false alarm of adjacent sensors (such as electromagnetic interference); small leaks (<1%LEL) are amplified by environmental factors (such as inversion layer causing gas accumulation); thermal interference of non-gas leaks (such as overheating of underground cables causing temperature rise), so further verification of secondary risks is needed to reduce false alarms.

[0093] Furthermore, spatial verification of the secondary risk (three adjacent nodes > 15% LEL) can only pinpoint an approximate area, but the actual leak could be anywhere within the area, such as a valve or weld. Direct excavation for inspection is costly and requires precise location. A temporary negative pressure pump (-0.1 MPa) is activated in the pipeline to draw free gas from the soil into a detection chamber. A laser spectrometer within the chamber amplifies the gas concentration tenfold (for example, 0.5% LEL becomes a significantly different 5% LEL), exceeding the sensitivity limit of conventional sensors.

[0094] Only for level 2 risk: level 1 risk will not be activated, and the cost-benefit ratio will be insufficient; level 3 risk will be skipped, and the valve will be closed directly to stop the loss.

[0095] In one embodiment, Figure 10 As shown, a method for monitoring and early warning of combustible gas in an underground gas pipeline network, step S3, triggering different alarm mechanisms based on risk levels, specifically includes:

[0096] Step S31: When the risk is level 1, locate the level 1 risk point and generate an inspection work order (30-minute response time limit);

[0097] Step S32: When the risk is level 2, the leak point coordinates and concentration gradient curve are pushed to the emergency repair team; the video surveillance within 500m of the leak point is automatically linked;

[0098] Step S33: When the risk reaches level 3, shut down the associated underground gas pipe network section valves (≤30 seconds); activate the sound and light alarm plus voice evacuation command (covering a radius of 200m); and transmit the GIS heat map (including the diffusion model predicted boundary) to the emergency department.

[0099] Level 1 risk requires a 30-minute response time, reflecting the manageable period for minor leaks. Level 2 automatically triggers video surveillance to visually confirm the visible / infrared signature of the leak. Level 3 valve shutoff takes ≤30 seconds, based on a diffusion velocity of 1.5 m / s for the lower explosive limit concentration (200 m radius, covering the evacuation window). The audible and visual alarm frequency is set at 400-600 Hz, effectively penetrating rain and noise environments. GIS heat maps and diffusion models are overlaid to enhance prediction accuracy.

[0100] It should be understood that, although the various steps in the flow chart of each embodiment of the present invention are shown in sequence according to the indication of the arrows, these steps are not necessarily performed in sequence according to the order indicated by the arrows. Unless otherwise specified herein, the execution of these steps is not strictly limited in order, and these steps can be performed in other orders. Moreover, at least a portion of the steps in each embodiment may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily performed at the same time, but can be performed at different times, and the execution order of these sub-steps or stages is not necessarily performed in sequence, but can be performed in turn or alternately with at least a portion of other steps or sub-steps or stages of other steps.

[0101] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0104] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A combustible gas monitoring and early warning system for an underground gas pipeline network, characterized in that: The underground gas pipeline network combustible gas monitoring and early warning system includes: Sensor modules are used to monitor the temperature and concentration of combustible gases at absolutely critical points, high-risk areas, and conventional pipelines; Communication module, used to transmit the temperature and combustible gas concentration monitored by the sensor module to the monitoring center CPU; The monitoring center CPU is used to determine whether there is a risk of combustible gas leakage based on temperature, combustible gas concentration, combined with spatiotemporal data and environmental data, and to issue an alarm when there is a risk of combustible gas leakage.

2. The underground gas pipeline network combustible gas monitoring and early warning system according to claim 1 is characterized in that: Absolutely critical points include pressure regulating stations, valve wells, key interfaces and crossing sections; An infrared absorption sensor is installed above the key equipment in the pressure regulating station, an infrared absorption sensor is installed at the inlet and outlet pipeline interfaces, and multiple infrared absorption sensors are installed at the environmental concentration monitoring points; At least one infrared absorption sensor is placed on the top of the valve well, and one infrared absorption sensor is placed directly above each flange and valve interface; A TDLAS laser sensor is installed at the interface of the key interface, and a TDLAS laser sensor is installed at each end of the crossing section.

3. The underground gas pipeline network combustible gas monitoring and early warning system according to claim 1 is characterized in that: High-risk areas include densely populated areas and sensitive facility areas; Bury temperature-sensing optical cables directly above pipelines in densely populated areas to monitor temperature anomalies; TDLAS laser sensors are deployed at the boundaries of sensitive facility areas; infrared absorption sensors are deployed at key nodes.

4. The underground gas pipeline network combustible gas monitoring and early warning system according to claim 1 is characterized in that: Conventional pipelines include main pipelines and secondary pipelines; Temperature-sensing optical cables are laid along the entire trunk pipeline to monitor pipeline temperature changes in real time; One catalytic combustion sensor is installed at the tee and elbow of the secondary trunk pipe; one catalytic combustion sensor is installed at the interface of the old pipe section; and one catalytic combustion sensor is installed at the extension point of the valve well.

5. A method for monitoring and early warning combustible gas in an underground gas pipeline network, applied to the underground gas pipeline network combustible gas monitoring and early warning system according to any one of claims 1 to 4, the method comprising the following steps: Obtain the temperature and combustible gas concentration at absolutely critical points, high-risk areas, and conventional pipelines of the underground gas pipeline network; Based on temperature, combustible gas concentration, combined with spatiotemporal data and environmental data, determine whether there is a combustible gas leakage risk and classify the risk level; Trigger different alarm mechanisms based on risk levels.

6. The method for monitoring and early warning combustible gas in an underground gas pipeline network according to claim 5, characterized in that: The step of determining whether there is a risk of combustible gas leakage based on temperature and combustible gas concentration, combined with spatiotemporal data and environmental data, and classifying the risk level specifically includes: Real-time monitoring of combustible gas concentration and temperature at each node. Combustible gas concentrations > 10% LEL or temperature rise > 0.5°C / 10m are marked as Level 1 risk points. Spatial analysis is performed to pre-determine areas with high incidence of exhaust gas interference, where the concentration judgment threshold is increased by 5% LEL. Perform time series analysis. If the combustible gas concentration gradient is greater than 5%LEL / minute for three consecutive cycles or the temperature rise rate is greater than 0.2°C / minute for three consecutive cycles, it is determined to be a time series leakage diffusion trend. Perform spatial verification. If the combustible gas concentration is greater than 15%LEL at three adjacent nodes at the same time, or the temperature rise at two adjacent nodes is greater than 0.5°C / 10m, it is determined to be a spatial leakage area. Conduct environmental analysis, obtain wind speed and direction data, start the exhaust diffusion model, and adjust the monitoring range based on wind speed using combustible gas concentration and temperature data; Risk levels are divided into: Level 1 risk: combustible gas concentration in conventional areas is >10%LEL or combustible gas concentration in areas with high incidence of exhaust gas interference is >15%LEL or temperature rise is >0.5℃ / 10m; Level 2 risk: based on the level 1 risk, there is a temporal leakage diffusion trend or spatial leakage area; Level 3 risk: combustible gas concentration in conventional areas is >50%LEL or combustible gas concentration in areas with high incidence of exhaust gas interference is >55%LEL or leakage area is >10㎡ or temperature rise is >2.0℃ / 10m.

7. The method for monitoring and early warning combustible gas in an underground gas pipeline network according to claim 6, characterized in that: The combustible gas concentration and temperature of each node are monitored in real time. Combustible gas concentration > 10% LEL or temperature rise > 0.5°C / 10m is marked as a first-level risk point; Perform spatial analysis, pre-determine areas with high incidence of exhaust gas interference, and increase the concentration judgment threshold by 5% LEL in these areas. This step also includes: Traffic flow in areas with high incidence of exhaust gas interference is counted through intersection cameras, and the impact of new energy vehicles is eliminated through license plate recognition. The size of 5%LEL is adjusted based on the traffic flow.

8. The method for monitoring and early warning combustible gas in an underground gas pipeline network according to claim 6, characterized in that: The steps of performing environmental analysis, obtaining wind speed and direction data, starting an exhaust gas diffusion model, and adjusting the monitoring range based on wind speed using combustible gas concentration and temperature data also include: Real-time fusion of meteorological radar and rain gauge data. When rainfall is greater than 10 mm / h, the dynamic attenuation mechanism for temperature rise judgment is activated. Based on the negative correlation between rainfall intensity and soil heat conduction, the risk judgment of temperature rise data is dynamically adjusted. After the rain stops, the risk judgment of temperature rise data is restored based on soil type.

9. The method for monitoring and early warning combustible gas in an underground gas pipeline network according to claim 6, characterized in that: The risk level classification is as follows: Level 1 risk: the combustible gas concentration in the conventional area is greater than 10% LEL or the combustible gas concentration in the area with high incidence of exhaust gas interference is greater than 15% LEL or the temperature rise is greater than 0.5°C / 10m; Level 2 risk: based on the level 1 risk, there is a temporal leakage diffusion trend or a spatial leakage area; Level 3 risk: the combustible gas concentration in the conventional area is greater than 50% LEL or the combustible gas concentration in the area with high incidence of exhaust gas interference is greater than 55% LEL or the leakage area is greater than 10 m2 or the temperature rise is greater than 2.0°C / 10m. The steps also include: The negative pressure pump of the underground gas pipeline network identified as a secondary risk area will be started to forcibly extract soil gas for detection; the concentration of leaking combustible gas will be amplified, and detection conditions will be actively created to improve sensitivity. After confirmation, the pressure will be reset immediately to avoid pipeline deformation.

10. The method for monitoring and early warning combustible gas in an underground gas pipeline network according to claim 5, characterized in that: The steps of triggering different alarm mechanisms based on risk levels specifically include: When there is a level 1 risk, locate the level 1 risk point and generate an inspection work order; In case of level 2 risk, the leak point coordinates and concentration gradient curve will be sent to the emergency repair team; video surveillance within 500m of the leak point will be automatically linked; When the risk reaches level three, shut down the valves of the associated underground gas pipeline network sections; activate the sound and light alarm plus voice evacuation instructions; and transmit the GIS heat map to the emergency department.

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