An underground pipe gallery gas pipeline leakage monitoring and leakage point accurate positioning system

Abstract

The present application is suitable for pipeline monitoring technical field, provide a kind of underground pipe gallery gas pipeline leakage monitoring and leak point accurate positioning system, the system includes pipe outer monitoring subsystem and pipe inner monitoring subsystem, the steps of pipe outer monitoring subsystem are carried out outside pipe monitoring are as follows: by track robot carrying laser remote sensing detector to carry out inspection around pipeline, realize the accurate positioning of gas pipeline leakage by the change of monitoring methane gas concentration value;The steps of pipe inner monitoring subsystem are carried out inside pipe monitoring are as follows: the installation position of pressure sensor, flow sensor and temperature sensor is determined by selecting monitoring point to gas pipeline, compare according to real-time monitoring value and simulation value to realize the leakage identification of gas pipe network, establish leakage point positioning model to determine the specific position of gas leakage.The accurate positioning of underground pipe gallery gas pipeline leak point is realized by the way of inside and outside pipe double positioning and software and hardware combination, reduce false alarm rate, and sensitivity is high.

Description

Technical Field

[0001] This invention relates to the field of pipeline monitoring technology, specifically to a system for monitoring and accurately locating leaks in underground gas pipeline corridors. Background Technology

[0002] In underground utility tunnels, gas pipelines coexist with other pipelines, so monitoring gas pipelines is particularly important, and monitoring gas pipeline leaks is one of the most critical aspects. Doing a good job in monitoring gas pipeline leaks is extremely important for ensuring the normal life of residents and the stable development of the city.

[0003] Currently known methods for detecting gas pipeline leaks each have their advantages and disadvantages, and the technology is relatively mature. The suitable monitoring environments (pipeline material, pipeline length, route area, etc.) for different methods are basically determined, and each monitoring method has formed its own detection principle and methodological system. The differences lie only in construction costs and accuracy requirements. With the development of laser absorption spectroscopy technology, this technology has been used to monitor gas pipeline leaks and can accurately detect even minor leaks. However, when the gas leak is more serious, this method cannot accurately locate the leak location, resulting in low accuracy. Furthermore, some monitoring technologies applied to underground gas pipeline corridors are affected by various factors such as the environment and pipeline operating conditions, leading to a high false alarm rate and an inability to accurately locate the leak. Therefore, there is a need to provide a gas pipeline leak monitoring and leak point accurate location system for underground pipeline corridors, aiming to solve the above problems. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a system for monitoring and accurately locating leaks in underground gas pipeline corridors, so as to solve the problems existing in the above-mentioned background technology.

[0005] This invention is implemented as follows: a system for monitoring and accurately locating leaks in underground gas pipelines. The system includes an external monitoring subsystem and an internal monitoring subsystem. The external monitoring subsystem performs external monitoring by using a tracked robot equipped with a laser remote sensing instrument to inspect the area around the pipeline and accurately locate gas leaks by monitoring changes in methane gas concentration. The internal monitoring subsystem performs internal monitoring by selecting monitoring points along the gas pipeline to determine the installation locations of pressure sensors, flow sensors, and temperature sensors. It then compares real-time monitoring values ​​with simulated values ​​to identify leaks in the gas pipeline network and establishes a leak location model to pinpoint the exact location of the gas leak.

[0006] As a further embodiment of the present invention: the external monitoring subsystem includes a track robot, a laser remote sensing instrument, a data processing module, and a wireless charging power supply; the track robot is placed on a track laid on the ground of the gas pipeline, the laser remote sensing instrument is used to monitor the methane concentration, the data processing module is used to process the methane concentration data to obtain the methane concentration change, and the wireless charging power supply is used to provide power support for the track robot. The track robot is equipped with a laser remote sensing instrument, a data processing module, and a wireless charging power supply, and the laser remote sensing instrument and the data processing module are connected.

[0007] As a further embodiment of the present invention: the pipeline monitoring subsystem includes a pressure sensor, a flow sensor, a temperature sensor, a monitoring substation host, an optical fiber, a host computer, and a computer processing center; the pressure sensor, flow sensor, and temperature sensor are arranged on the pipeline according to a determined monitoring point sequence; the monitoring substation host is used to realize the communication and networking functions of the pressure sensor, flow sensor, and temperature sensor, and to control the sensors to monitor the pipeline in real time; the optical fiber is used to connect the monitoring substation and the monitoring center; the monitoring substation includes a monitoring substation host; the monitoring center includes a host computer and a computer processing center; the host computer issues instructions to transmit monitoring data to the computer processing center; the computer processing center compares the real-time monitoring values ​​and simulated values ​​to identify gas pipeline leaks and establish a gas pipeline leak location model for precise location.

[0008] As a further aspect of the present invention: the laser remote sensing detector includes a laser module, a laser detector, a lock-in amplifier, and an A / D converter; the laser module is used to emit laser light, and the emitted laser light can stabilize the center wavelength near the center of the methane gas absorption line; the laser detector is used to receive the light signal reflected back from the laser module when the gas leaks; the lock-in amplifier is used to filter and amplify the electrical signal to obtain the first harmonic and second harmonic signals; the A / D converter is used to convert analog signals to digital signals; and the data processing module is used to obtain the gas concentration change and determine the precise location of the gas leak.

[0009] As a further aspect of the present invention: the steps of the external monitoring subsystem for accurately locating gas pipeline leaks specifically include:

[0010] Two track robots were placed on tracks laid on both sides of the gas pipeline.

[0011] This allows the two track robots to perform alternating inspections, one moving and one stopping, and wireless charging stations are set up at the start and end of the inspection to ensure that the track robots can be charged when they reach the end.

[0012] The laser remote sensing detector on the orbital robot absorbs some of the laser energy when it scans the CH4 gas cloud formed around the leak point. The concentration of CH4 can be deduced from the initial power and echo power of the laser.

[0013] The data processing module generates a methane concentration change graph, and the highest point of methane concentration is the location of the gas pipeline leak. Combined with the position information of the track robot, the gas leak point is accurately located.

[0014] As a further aspect of the present invention, the step of reversing the concentration of CH4 specifically includes:

[0015] When the absorption spectrum of a gas is described by the Lorentz function, and the center frequency of the output light from a semiconductor laser is aligned with the absorption peak of the gas spectrum, we have:

[0016]

[0017] Where, α v Let α be the absorption coefficient of the gas for light at frequency v, α0 be the peak absorption coefficient of the gas absorption spectrum, and δ be the peak absorption coefficient. v ω is the frequency modulation amplitude, γ is the half-width of the absorption line, and ω is the frequency of the cosine signal.

[0018] Calculate the first harmonic I f and second harmonic I 2f The first harmonic and the second harmonic are respectively:

[0019] I 2f =sI0(v)α0A2CL

[0020] Where C is the volume concentration of the gas being measured, L is the length of the gas absorption optical path, s is the light collection efficiency, and δ I Here, I0(v) represents the frequency modulation amplitude, I0(v) represents the optical power output by the laser module, I(v) represents the optical power received by the laser detector, and A0 and A2 are related to δ. v A function of γ, where A0, A2 < 1;

[0021] Through the formula: The concentration C of CH4 was obtained.

[0022] As a further aspect of the present invention: the step of the in-pipe monitoring subsystem determining the specific location of the gas leak specifically includes:

[0023] Based on the structural analysis of underground utility tunnel gas pipelines, pressure sensors, flow sensors, and temperature sensors are arranged at sealing rings, welds, nodes, and flange connections. Pressure, flow, and temperature monitoring points are selected in the pipeline according to the number of pipe sections.

[0024] Based on the pressure and flow sensors installed on both sides of the pipe section, the pressure and flow values ​​at both ends of the pipe can be detected in real time. A mathematical model is established based on the pressure P0 monitored at the starting point to simulate and obtain the pressure value P of each pipe section. n The system compares the monitored values ​​with the simulated values, compares the flow rates of two adjacent monitoring points, sets a threshold, determines whether a leak has occurred in the pipe section, and identifies the location of the leak point in the pipe section.

[0025] The pipe section where the gas leak is located is identified, and the starting pressure of the pipe section is set as P. l The traffic is Q l The pressure at the end of the pipe section is set to P. i The flow rate is Q i Let the location of the gas leak be r. The pressure P at the leak location r is simulated in the computer processing center using the pressure and flow rate at the starting point. r 'and traffic Q r Then P r 'and Q r Simulated end pressure P of pipe section i ', by comparing P i and P i This allows us to pinpoint the exact location of the gas leak.

[0026] As a further aspect of the present invention: the step of determining whether a pipe section has leaked specifically includes:

[0027] Based on the real-time pressure signals detected in each pipe section {P0, P1, ... P n} and flow rate signals {Q0, Q1, ... Q} n Perform leak monitoring;

[0028] The initial pressure P0 and initial flow rate Q0 of the pipeline are obtained using the pressure sensor and flow sensor at the starting point, according to the formula:

[0029] P n =P n-1 -ρ g (Z n-1 -Z n )-ρgh w

[0030]

[0031] In the formula: P n Z represents the pressure at the monitoring point, in Pa. n The height of the monitoring point relative to the reference plane is in meters (m); ρ is the average density of the fluid inside the pipe, in kg / m³. 3 g is the acceleration due to gravity, g = 9.8 m / s² 2 h wγ is the energy loss per unit weight of fluid from the beginning to the end of a pipe segment, in meters; γ is the specific weight of the gas inside the pipe, γ = ρg; v1 and v2 are the average flow velocities at both ends of the pipe segment, in meters per second.

[0032] Based on the pressure P0 monitored at the starting point, the pressure value signals {P1', P2', ... P1'} of each pipe section are simulated according to the formula. n '};

[0033] The real-time detected pressure of each pipe section is compared with the simulated pressure value, and the flow monitoring values ​​of two nearby monitoring points are compared. If |P i -P′ i | max <ε, and |Q i -Q i-1 | max If δ < i = 1, 2, 3…n, and ε and δ are threshold values, then no leaks have occurred in any pipe section; otherwise, leaks have occurred in the pipe section, thus identifying the pipe section where the gas leak occurred.

[0034] As a further aspect of the present invention: the step of determining the specific location of the gas leak specifically includes:

[0035] Using the inlet of the identified leaking pipe section as the starting point and the outlet as the ending point, the starting pressure P is determined through real-time monitoring. l Traffic Q l and temperature T l Endpoint pressure P i Traffic Q i and temperature T i ;

[0036] Determine the simulated pressure value at the leak location r: in, Here, ρ is the average friction coefficient, D is the pipe diameter, ρ is the gas density, P0 is the fluid pressure under standard conditions, and T0 is the pipe section temperature under standard conditions. Z0 is the average compressibility coefficient, and L is the compressibility coefficient under standard conditions. r Let r be the length from the starting point of the pipe segment;

[0037] The simulated pressure value P at point r r The flow rate Q at point r r =Q l -Q i The simulated pressure value P at the end of the pipe section was obtained. i ';

[0038] Establish a leak location model, let l r =0, the simulated endpoint pressure P i 'and the pressure P monitored in real time i Compare, if |P'i -P i If |<μ, where μ is the set threshold, then the position of r is output; the location where the leak occurs is the starting point. Otherwise, let l r =l r +Δr, where Δr is the minimum value, after several iterations when |P' i -P i |<μ, output l r This will give you the location of the leak point r, which is the specific location of the gas pipeline leak.

[0039] Compared with the prior art, the beneficial effects of the present invention are:

[0040] This invention achieves precise location of gas pipeline leaks in underground utility tunnels by combining internal and external positioning with hardware and software, reducing false alarm rates and providing high sensitivity.

[0041] Specifically, a tracked robot equipped with a laser module utilizes near-infrared semiconductor laser absorption spectroscopy and harmonic detection technology to calculate the CH4 concentration at the leak location in real time by measuring the spectrum of methane molecules. After data processing, the change in CH4 gas concentration is obtained, and the maximum value of the CH4 concentration change indicates the location of the gas pipeline leak. It also records the leaked methane gas concentration. This method is based on α(v)CL << 1, meaning that when the pipeline damage is severe and the leak concentration is high, this method will have a relatively large error. Therefore, external monitoring is based on situations where the leak is relatively small, such as pipeline perforation.

[0042] The gas pipeline pressure and flow signals are monitored inside the pipeline. By comparing the real-time monitoring values ​​with the simulated values, gas pipeline leaks can be identified. A leak location model is established to solve for the leak location and accurately determine the location of the leak. This method is suitable for situations where gas leaks are relatively serious.

[0043] This invention integrates external and internal monitoring, allowing them to work together to accurately locate leaks in gas pipelines under various conditions. Attached Figure Description

[0044] Figure 1 This is an overall flowchart of a system for monitoring and accurately locating leaks in underground gas pipeline corridors.

[0045] Figure 2 This is a schematic diagram of the external monitoring subsystem in an underground utility tunnel gas pipeline leak monitoring and leak point precise location system.

[0046] Figure 3 This is a schematic diagram of the internal monitoring subsystem in an underground gas pipeline leak monitoring and leak point precise location system. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0048] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0049] like Figure 1 , Figure 2 and Figure 3 As shown in the figure, this embodiment of the invention provides a system for monitoring and accurately locating leaks in underground gas pipelines. The system includes an external monitoring subsystem and an internal monitoring subsystem. The steps of the external monitoring subsystem are as follows: a tracked robot carrying a laser remote sensing detector inspects the area around the pipeline and monitors changes in methane gas concentration to accurately locate gas pipeline leaks. The steps of the internal monitoring subsystem are as follows: the installation locations of pressure sensor 1, flow sensor 2, and temperature sensor 3 are determined by selecting monitoring points on the gas pipeline; leaks in the gas pipeline are identified by comparing real-time monitoring values ​​and simulated values; and a leak location model is established to determine the specific location of the gas leak.

[0050] In this embodiment of the invention, the external monitoring subsystem includes a track robot, a laser remote sensing instrument, a data processing module, and a wireless charging power supply. The track robot is placed on a track laid on the ground of the gas pipeline. The laser remote sensing instrument is used to monitor the methane concentration. The data processing module is used to process the methane concentration data to obtain the methane concentration change. The wireless charging power supply is used to provide power support for the track robot. The track robot is equipped with the laser remote sensing instrument, the data processing module, and the wireless charging power supply. The laser remote sensing instrument and the data processing module are connected.

[0051] In this embodiment of the invention, the pipeline monitoring subsystem includes a pressure sensor 1, a flow sensor 2, a temperature sensor 3, a monitoring substation host, an optical fiber, a host computer, and a computer processing center. The pressure sensor 1, flow sensor 2, and temperature sensor 3 are arranged on the pipeline according to a predetermined monitoring point sequence. The monitoring substation host is used to realize the communication and networking functions of the pressure sensor 1, flow sensor 2, and temperature sensor 3, and to control the sensors to monitor the pipeline in real time. The optical fiber is used to connect the monitoring substation and the monitoring center. The monitoring substation includes a monitoring substation host, and the monitoring center includes a host computer and a computer processing center. The host computer issues instructions to transmit monitoring data to the computer processing center. The computer processing center compares the real-time monitoring values ​​with simulated values ​​to identify leaks in the gas pipeline network and establish a gas pipeline leak location model for precise location. Preferably, the pressure sensor 1 is an MC20A type pressure sensor, the flow sensor 2 is a gas turbine flow meter, and the temperature sensor 3 is an MCT80S temperature sensor.

[0052] In a preferred embodiment of the present invention, the laser remote sensing detector includes a laser module, a laser detector, a lock-in amplifier, and an A / D converter. The laser module emits a laser beam whose center wavelength is stabilized near the center of the methane gas absorption line. The laser detector receives the light signal reflected back from the laser module when a gas leak occurs. The lock-in amplifier filters and amplifies the electrical signal to obtain the first and second harmonic signals. The A / D converter converts the analog signal to a digital signal. The data processing module obtains information on changes in gas concentration to accurately locate the gas leak. Preferably, the laser module uses a DFB laser, which emits a laser beam whose center wavelength is stabilized near the center of the methane gas absorption line. The laser detector uses a PIN photodetector to convert the reflected light signal into an electrical signal. The lock-in amplifier uses a LIA-MV-150 lock-in amplifier, whose parameters can be controlled by a switch and is protected against electromagnetic interference. The data processing module uses an S3C2440 ARM microprocessor.

[0053] As a preferred embodiment of the present invention, the steps of the external monitoring subsystem for accurately locating gas pipeline leaks specifically include:

[0054] S110, place two track robots on tracks laid on both sides of the gas pipeline;

[0055] S120 enables two track robots to conduct alternating inspections by moving and stopping, and wireless charging stations are set up at the start and end of the inspection to ensure that the track robots can be charged when they reach the end.

[0056] S130, the laser remote sensing detector on the orbital robot will absorb some of the laser energy when it scans the CH4 gas cloud formed around the leak point, and the concentration of CH4 can be inferred from the initial power and echo power of the laser.

[0057] S140 uses a data processing module to obtain a methane concentration change graph. The highest point of methane concentration is the location of the gas pipeline leak. Combined with the position information of the track robot itself, the gas leak point is accurately located.

[0058] The wireless charging station is set at the start and end points and is placed on the bottom power supply of the robot when the track robot arrives to wirelessly charge it. In order to meet the requirements of alternating inspection, the inspection time and charging time of the two track robots are both t, t = l / v, where l is the inspection length and v is the inspection speed of the robot. While one robot is charging, the other is inspecting, which can ensure uninterrupted inspection 24 hours a day.

[0059] In a preferred embodiment of the present invention, the step of reversing the concentration of CH4 specifically includes:

[0060] S131, using the Lorentz function to describe the absorption spectrum of the gas, and assuming the center frequency of the output light from the semiconductor laser is aligned with the spectral absorption peak of the gas, we have:

[0061]

[0062] Where, α v Let α be the absorption coefficient of the gas for light at frequency v, α0 be the peak absorption coefficient of the gas absorption spectrum, and δ be the peak absorption coefficient. v ω is the frequency modulation amplitude, γ is the half-width of the absorption line, and ω is the frequency of the cosine signal.

[0063] S132, because the absorption coefficient of gas to light in the near-infrared band is very small, when the gas absorption optical path is short or the gas concentration is low, α generally satisfies v CL << 1, calculate the first harmonic I. f and second harmonic I 2f The first and second harmonics are respectively:

[0064] I 2f =sI0(v)α0A2CL

[0065] Where C is the volume concentration of the gas being measured, L is the length of the gas absorption optical path, s is the light collection efficiency, and δ I Here, I0(v) represents the frequency modulation amplitude, I0(v) represents the optical power output by the laser module, I(v) represents the optical power received by the laser detector, and A0 and A2 are related to δ. v A function of γ, where A0, A2 < 1;

[0066] S133, due to α v CL<<1, and combining with the above formula, we can obtain By measuring the values ​​of the second and first harmonics, the concentration C of methane can be obtained, and the effects of factors such as light receiving efficiency and light power fluctuations can be eliminated.

[0067] As a preferred embodiment of the present invention, the step of the in-pipe monitoring subsystem determining the specific location of the gas leak specifically includes:

[0068] S210, based on the structural analysis of underground pipe gallery gas pipelines, pressure sensor 1, flow sensor 2 and temperature sensor 3 are arranged at the sealing ring, weld, node and flange connection, and pressure, flow and temperature monitoring points are selected in the pipeline according to the number of pipe sections.

[0069] S220, based on pressure sensor 1 and flow sensor 2 installed on both sides of the pipe section, can detect the pressure and flow values ​​at both ends of the pipe in real time. Based on the pressure P0 monitored at the starting point, a mathematical model is established to simulate and obtain the pressure value P of each pipe section. n The system compares the monitored values ​​with the simulated values, compares the flow rates of two adjacent monitoring points, sets a threshold, determines whether a leak has occurred in the pipe section, and identifies the location of the leak point in the pipe section.

[0070] S230, the pipe section with the gas leak is identified, and the starting pressure of the pipe section is set to P. l The traffic is Q l The pressure at the end of the pipe section is set to P. i The flow rate is Q i Let the location of the gas leak be r. The pressure P at the leak location r is simulated in the computer processing center using the pressure and flow rate at the starting point. r 'and traffic Q r Then P r 'and Q r Simulated end pressure P of pipe section i ', by comparing P i and P i This allows us to pinpoint the exact location of the gas leak.

[0071] In a preferred embodiment of the present invention, the step of determining whether a pipe section is leaking specifically includes:

[0072] S221, based on the real-time pressure value signals {P0, P1, ... P} detected in each pipe section, n} and flow rate signals {Q0, Q1, ... Q} n Perform leak monitoring;

[0073] S222, using pressure sensor 1 and flow sensor 2 at the starting point, the initial pressure P0 and initial flow rate Q0 of the pipeline are obtained, according to the formula:

[0074] P n =P n-1 -ρ g (Z n-1 -Z n )-ρgh w

[0075]

[0076] In the formula: P n Z represents the pressure at the monitoring point, in Pa. n The height of the monitoring point relative to the reference plane is in meters (m); ρ is the average density of the fluid inside the pipe, in kg / m³. 3 g is the acceleration due to gravity, g = 9.8 m / s² 2 h w γ represents the energy loss per unit gravity fluid from the beginning to the end of a pipe segment, in meters (m); γ is the specific gravity of the gas inside the pipe, γ = ρg; v1 and v2 are the average flow velocities at both ends of the pipe segment, in m / s; based on the pressure P0 monitored at the starting point, the pressure signals {P1', P2', ... P1'} of each pipe segment can be simulated using the above formulas. n '};

[0077] S223 compares the real-time detected pressure of each pipe section with the simulated pressure value, and compares the flow monitoring values ​​of two nearby monitoring points. If |P i -P′ i | max <ε, and |Q i -|Q i-1 | max If δ < i = 1, 2, 3…n, and ε and δ are threshold values, then no leaks have occurred in any pipe section; otherwise, leaks have occurred in the pipe section, thus identifying the pipe section where the gas leak occurred.

[0078] In a preferred embodiment of the present invention, the step of determining the specific location of the gas leak specifically includes:

[0079] S231, using the inlet of the identified leaking pipe section as the starting point and the outlet as the ending point, real-time monitoring is used to determine the starting pressure P. l Traffic Q l and temperature T l Endpoint pressure P i Traffic Q i and temperature T i ;

[0080] S232, Determine the simulated pressure value at the leak location r: in, Here, ρ is the average friction coefficient, D is the pipe diameter, ρ is the gas density, P0 is the fluid pressure under standard conditions, and T0 is the pipe section temperature under standard conditions. Z0 is the average compressibility coefficient, and L is the compressibility coefficient under standard conditions. r Let r be the length from the starting point of the pipe segment;

[0081] S233, the simulated pressure value P at point r r The flow rate Q at point r r =Q l -Q i The simulated pressure value P at the end of the pipe section was obtained. i ';

[0082] S234, Establish a leak location model, let l r =0, the simulated endpoint pressure P i 'and the pressure P monitored in real time i Compare, if |P' i -P i If |<μ, where μ is the set threshold, then the position of r is output; the location where the leak occurs is the starting point. Otherwise, let l r =l r +Δr, where Δr is the minimum value, repeat steps S232 and S233, and after several iterations, when |P' i -P i |<μ, output l r This will give you the location of the leak point r, which is the specific location of the gas pipeline leak.

[0083] In addition, both internal and external monitoring work together. When both detect a gas pipeline leak, and the leak locations output by both methods are close, with the distance between the leak locations less than or equal to a set value, the location output by external monitoring is taken as the standard, since internal monitoring locates the leak point by a distance Δr, while external monitoring has higher accuracy. When both detect a gas pipeline leak, but the leak locations output by the two methods deviate significantly, with the distance between the leak locations greater than the set value, it indicates a large-scale leak in the pipeline. In this case, the accuracy of external monitoring is lower, and the location output by internal monitoring is taken as the standard. When internal monitoring does not detect a gas leak, but external monitoring outputs the location of the gas leak, it indicates a small-scale leak in the pipeline.

[0084] The above description only details the preferred embodiments 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 within the scope of protection of the present invention.

[0085] It should be understood that although the steps in the flowcharts of the various embodiments of the present invention are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the various embodiments may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least a portion of the sub-steps or stages of other steps.

[0086] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the disclosure in the specification and embodiments. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

Claims

1. A system for monitoring and accurately locating leaks in underground gas pipeline corridors, characterized in that, The system includes an external monitoring subsystem and an internal monitoring subsystem. The external monitoring subsystem performs external monitoring by using a tracked robot equipped with a laser remote sensing detector to inspect the area around the pipeline and accurately locate gas pipeline leaks by monitoring changes in methane gas concentration. The internal monitoring subsystem performs internal monitoring by selecting monitoring points along the gas pipeline to determine the installation locations of pressure sensors, flow sensors, and temperature sensors. It then compares real-time monitoring values ​​with simulated values ​​to identify gas pipeline leaks and establishes a leak location model to pinpoint the exact location of the gas leak. The external monitoring subsystem includes a track robot, a laser remote sensing instrument, a data processing module, and a wireless charging power supply. The track robot is placed on a track laid on the ground of the gas pipeline. The laser remote sensing instrument is used to monitor the methane concentration. The data processing module is used to process the methane concentration data to obtain the methane concentration change. The wireless charging power supply is used to provide power support for the track robot. The track robot is equipped with a laser remote sensing instrument, a data processing module, and a wireless charging power supply. The laser remote sensing instrument and the data processing module are connected. The pipeline monitoring subsystem includes pressure sensors, flow sensors, temperature sensors, a monitoring substation host, optical fiber, a host computer, and a computer processing center. The pressure sensors, flow sensors, and temperature sensors are arranged on the pipeline according to a determined monitoring point sequence. The monitoring substation host is used to realize the communication and networking functions of the pressure sensors, flow sensors, and temperature sensors, and to control the sensors to monitor the pipeline in real time. The optical fiber is used to connect the monitoring substation and the monitoring center. The monitoring substation includes a monitoring substation host, and the monitoring center includes a host computer and a computer processing center. The host computer issues instructions to transmit the monitoring data to the computer processing center. The computer processing center compares the real-time monitoring values ​​with the simulated values ​​to identify gas pipeline leaks and establish a gas pipeline leak location model for accurate location. The steps of the external monitoring subsystem to accurately locate gas pipeline leaks specifically include: Two track robots were placed on tracks laid on both sides of the gas pipeline. This allows the two track robots to perform alternating inspections, one moving and one stopping, and wireless charging stations are set up at the start and end of the inspection to ensure that the track robots can be charged when they reach the end. The laser remote sensing detector on the orbital robot absorbs some of the laser energy when it scans the CH4 gas cloud formed around the leak point. The concentration of CH4 can be deduced from the initial power and echo power of the laser. The data processing module generates a methane concentration change graph. The highest point of methane concentration is the location of the gas pipeline leak. Combined with the position information of the track robot, the gas leak point is accurately located. The steps by which the in-pipe monitoring subsystem determines the specific location of a gas leak include: Based on the structural analysis of underground utility tunnel gas pipelines, pressure sensors, flow sensors, and temperature sensors are arranged at sealing rings, welds, nodes, and flange connections. Pressure, flow, and temperature monitoring points are selected in the pipeline according to the number of pipe sections. Based on the pressure and flow sensors installed on both sides of the pipe section, the pressure and flow values ​​at both ends of the pipe can be detected in real time. A mathematical model is established based on the pressure P0 monitored at the starting point to simulate and obtain the pressure value P of each pipe section. n The system compares the monitored values ​​with the simulated values, compares the flow rates of two adjacent monitoring points, sets a threshold, determines whether a leak has occurred in the pipe section, and identifies the location of the leak point in the pipe section. The pipe section where the gas leak is located is identified, and the starting pressure of the pipe section is set as P. l The traffic is Q l The pressure at the end of the pipe section is set to P. i The flow rate is Q i Let the location of the gas leak be r. The pressure P at the leak location r is simulated in the computer processing center using the pressure and flow rate at the starting point. r 'and traffic Q r Then P r 'and Q r Simulated end pressure P of pipe section i By comparing Pi and Pi', the specific location of the gas leak can be determined; Furthermore, the system is also configured to perform the following: when both the external monitoring subsystem and the internal monitoring subsystem detect a gas pipeline leak, and the leak locations output by both are close, with the distance between the leak locations being less than or equal to a preset distance threshold, the location output by the external monitoring subsystem shall be taken as the final gas pipeline leak location; when both the external monitoring subsystem and the internal monitoring subsystem detect a gas pipeline leak, but the leak locations output by both deviate significantly, with the distance between the leak locations being greater than the preset distance threshold, the location output by the internal monitoring subsystem shall be taken as the final gas pipeline leak location.

2. The underground utility tunnel gas pipeline leakage monitoring and leak point precise location system according to claim 1, characterized in that, The laser remote sensing detector includes a laser module, a laser detector, a lock-in amplifier, and an A / D converter. The laser module emits a laser beam with a center wavelength that is stabilized near the center of the methane gas absorption line. The laser detector receives the light signal reflected back from the laser module when a gas leak occurs. The lock-in amplifier filters and amplifies the electrical signal to obtain the first and second harmonic signals. The A / D converter converts the analog signal to a digital signal. The data processing module obtains information on changes in gas concentration to accurately locate the gas leak.

3. The underground utility tunnel gas pipeline leakage monitoring and leak point precise location system according to claim 1, characterized in that, The steps to determine the concentration of CH4 include: When the absorption spectrum of a gas is described by the Lorentz function, and the center frequency of the output light from a semiconductor laser is aligned with the absorption peak of the gas spectrum, we have: ； in, v Let be the absorption coefficient of the gas for light at frequency v. The peak absorption coefficient of the gas absorption spectrum. ω is the frequency modulation amplitude, γ is the half-width of the absorption line, and ω is the frequency of the cosine signal. Calculate the first harmonic and second harmonic The first harmonic and the second harmonic are respectively: ( )， ； Where C is the volume concentration of the gas being measured, L is the length of the gas absorption optical path, and s is the light collection efficiency. For frequency modulation amplitude, The optical power output by the laser module. The optical power received by the laser detector. and It is about and a function of γ, and , <1; Through the formula: The concentration of CH4 was obtained. .

4. The underground utility tunnel gas pipeline leakage monitoring and leak point precise location system according to claim 1, characterized in that, The step of determining whether a pipe section is leaking specifically includes: Based on the real-time pressure signals detected in each pipe section {P0, P1, ... P n } and flow rate signals {Q0, Q1,} Q n Perform leak monitoring; The initial pressure P0 and initial flow rate Q0 of the pipeline are obtained using the pressure sensor and flow sensor at the starting point, according to the formula: ； ； In the formula: Pressure at the monitoring point, in Pa; The height of the monitoring point relative to the reference plane, in meters (m). ρ is the average density of the fluid inside the pipe, in kg / m³; g is the acceleration due to gravity, g = 9.8 m / s²; h w γ is the energy loss per unit weight of fluid from the beginning to the end of a pipe segment, in meters; γ is the specific weight of the gas inside the pipe, γ = ρg; v1 and v2 are the average flow velocities at both ends of the pipe segment, in meters per second. Based on the pressure P0 monitored at the starting point, the pressure value signals {P1', P2', ...} of each pipe section are simulated according to the formula. P n '}; The real-time detected pressure of each pipe section is compared with the simulated pressure value, and the flow monitoring values ​​of two similar monitoring points are compared. If... ,and i = 1, 2, 3…n and If the threshold is set, then no leaks have occurred in any pipe section; otherwise, leaks have occurred, thus identifying the pipe section where the gas leak occurred.

5. The underground utility tunnel gas pipeline leakage monitoring and leak point precise location system according to claim 4, characterized in that, The step of determining the specific location of the gas leak specifically includes: Using the inlet of the identified leaking pipe section as the starting point and the outlet as the ending point, the starting pressure P is determined through real-time monitoring. l Traffic Q l and temperature T l Endpoint pressure P i Traffic Q i and temperature T i ; Determine the simulated pressure value at the leak location r: ,in, Where D is the average friction coefficient and D is the pipe diameter. For gas density, The fluid pressure under standard conditions. The pipe section temperature under standard conditions. The average compression ratio, The compression factor is the value under standard conditions. Let r be the length from the starting point of the pipe segment; The simulated pressure value P at point r r The flow rate Q at point r r =Q l -Q i The simulated pressure value P at the end of the pipe section was obtained. i '; Establish a leak location model, let l r =0, the simulated endpoint pressure P i 'and the pressure P monitored in real time i If a comparison is made, , If the set threshold is not met, the output position of r is used; the location where the leak occurs is the starting point. Otherwise, let l... r =l r + , To reach the minimum value, after several iterations when Output l r This will give you the location of the leak point r, which is the specific location of the gas pipeline leak.

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