Laser radar-based gas extraction pipe network leak detection system and method

Abstract

This invention relates to a leak detection system and method for gas extraction pipelines based on lidar, belonging to the field of gas extraction technology. The system includes several leak detection units; one end of each unit is equipped with a laser signal generator, and the other end with a laser signal receiver. When a gas leak occurs at a certain location in the gas extraction pipeline, radial airflow pressure fluctuations are generated, causing laser signal attenuation and affecting the number of laser beams received by the laser signal receiver. The signal collection and analysis terminal uses Doppler frequency shift to calculate the location of the airflow anomaly. Signals from all signal collection and analysis terminals are transmitted in real-time to an external monitoring system through a signal integration substation. This invention can simultaneously meet the leak detection needs of both positive and negative pressure gas transmission pipelines, achieving real-time leak detection of the extraction pipeline network and determining the leak point.

Description

Technical Field

[0001] This invention belongs to the field of gas extraction technology, and relates to a gas extraction pipeline network leak detection system and method based on lidar. Background Technology

[0002] Coal mine gas, also known as coalbed methane, is one of the main factors threatening safe production in coal mines. Extracting and utilizing coalbed methane has many benefits; on the one hand, it can promote safe and efficient mine production; on the other hand, it can increase energy supply. Therefore, ensuring the efficient extraction and utilization of mine gas is indispensable. Generally, extraction boreholes are used to remove coalbed methane to reduce the gas content in the area to be mined. The extracted gas needs to be transported to the surface for utilization through a gas extraction pipeline network. The extraction section of the gas extraction pipeline network is a negative pressure pipeline, and the output section is a positive pressure pipeline.

[0003] The gas drainage pipeline network is a crucial link in ensuring effective gas drainage and achieving efficient gas utilization. First, deformation of underground roadways or impacts from falling coal and rock fragments can easily cause accidental damage to the gas drainage pipeline. Second, due to the long length of underground pipelines and the complex underground environment, locating leak points in the gas drainage pipeline can be challenging. Third, because the gas drainage pipeline network contains both positive and negative pressure sections, existing real-time pipeline leak detection technologies are all designed for positive pressure pipelines. However, the integrity of the gas drainage pipeline network is precisely one of the important factors affecting the efficient extraction, utilization, and safety of coal seam gas.

[0004] The relevant patent for gas pipeline leak detection found is patent application number CN201120131338.2, which discloses an ultrasonic leak detector for gas drainage pipelines in coal mines. The detector includes an ultrasonic probe, a signal amplification circuit, an audio processing circuit, a frequency display circuit, and a microcontroller. The ultrasonic probe acquires the ultrasonic signal generated by the pipeline leak. After passing through the signal amplification circuit, the ultrasonic signal is input to the audio processing circuit, which converts the high-frequency ultrasonic signal into a low-frequency signal audible to the human ear. The frequency display circuit displays the frequency value of the ultrasonic signal in real time. This leak detector, which uses an ultrasonic probe to acquire the ultrasonic signal generated by the pipeline leak and converts the high-frequency signal into a low-frequency signal or displays the frequency value of the ultrasonic signal in real time via the frequency display circuit, is low-cost, easy to use, fast, accurate, reliable, and convenient for on-site detection. It is suitable for gas leak detection in gas transportation pipelines in explosive gas environments in underground coal mines.

[0005] By reviewing and analyzing relevant materials, it can be seen that the current pipeline leak detection methods in non-mining fields are mainly positive pressure transmission pipeline leak detection methods, while pipeline leak detection in mining fields are mainly local manual inspection leak detection. Neither of the aforementioned leak detection methods can achieve real-time dynamic leak detection for both positive and negative pressure transmission pipeline networks at the same time. Summary of the Invention

[0006] In view of this, in order to address the problems of low efficiency, easy to miss detection, and inability to perform synchronous leak detection on the entire gas extraction pipeline network, which are currently limited to local manual inspection methods, this invention proposes a gas extraction pipeline network leak detection system and method based on lidar. This system can achieve real-time dynamic leak detection on both positive and negative pressure transmission pipelines, greatly improving the leak detection efficiency of gas extraction pipeline networks.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A leak detection system for gas extraction pipelines based on lidar, which includes several leak detection units;

[0009] The leak detection unit is defined as follows: the gas extraction pipeline network is divided into several straight pipe sections according to the laying path of the gas extraction pipeline network, and each straight pipe section is a leak detection unit.

[0010] The laser signal receiving device 2 is used to receive the laser emitted by the laser signal generating device 1 of the corresponding leak detection unit;

[0011] The laser can envelop the gas extraction pipeline 4;

[0012] Each laser signal receiving device 2 is equipped with a signal collection and analysis terminal 3;

[0013] All signal collection and analysis terminals 3 are connected to the signal integration substation 5;

[0014] The signal integration substation 5 is connected to an external monitoring system;

[0015] When a gas leak occurs at a certain location in the gas extraction pipeline 4, radial airflow pressure fluctuations are generated, causing laser signal attenuation and affecting the number of lasers received by the laser signal receiving device 2. The signal collection and analysis terminal 3 uses Doppler frequency shift to calculate the location of the abnormal airflow. All signals from the signal collection and analysis terminal 3 are transmitted in real time to the external monitoring system through the signal integration substation 5 to realize real-time leak detection, leak point location, and alarm of the gas extraction pipeline network.

[0016] Furthermore, the laser signal generating device 1 is a ring laser signal generating device, used to emit a ring laser signal that surrounds the gas extraction pipeline 4.

[0017] A method for detecting leaks in gas extraction pipelines based on lidar, comprising the following steps:

[0018] S1: Leak detection unit division and determination; Based on the mine gas drainage pipeline network laying diagram, the number of straight pipe sections and the corresponding pipe diameter and length of the straight pipe sections are divided, and the leak detection units are determined. The inner diameter of the laser signal generator 1 and laser signal receiver 2 required for different leak detection units must match the outer diameter of the corresponding straight pipe section gas drainage pipeline 4.

[0019] S2: Device installation; Based on the leak detection units defined and determined in S1, a laser signal generator 1 and a laser signal receiver 2 are installed at the beginning and end of the corresponding straight pipe section of the gas extraction pipeline 4, respectively. The beginning and end of the straight pipe section are determined according to the gas flow direction. Each straight pipe section laser signal receiver 2 is equipped with a signal collection and analysis terminal 3. All signal collection and analysis terminals 3 are connected to the signal integration substation 5, and the signal integration substation 5 is connected to the external monitoring system.

[0020] S3: System debugging; check if the system can operate normally; during the trial operation, set the leak detection sensitivity in the system according to the site conditions; for gas extraction pipelines with 4 straight pipe sections reaching a certain length, determine whether to increase the number of leak detection units in the pipelines that have reached a certain length based on the debugging results.

[0021] S4: Real-time leak detection and monitoring; After the system is debugged to the optimal operating state, the system is restarted to start the real-time leak detection and monitoring of the gas extraction pipeline network. The laser signal generator 1 and the laser signal receiver 2 will continuously generate and receive signals for scanning detection. The signal collection and analysis terminal 3 will process and analyze the signals in real time and transmit them synchronously to the external monitoring system through the signal integration substation 5.

[0022] S5: Leakage alarm and location; When a gas leak occurs at a certain location in the gas extraction pipeline 4, radial airflow pressure fluctuations are generated, causing laser signal attenuation and affecting the number of lasers received by the laser signal receiving device 2. The signal collection and analysis terminal 3 uses Doppler frequency shift to calculate the location of the abnormal airflow and transmits it synchronously to the external monitoring system. The system issues an alarm and displays the alarm straight pipe section and the specific location of the leak point.

[0023] S6: Manual verification and repair of leak points; after receiving an alarm from the external monitoring system, staff will be dispatched to the designated location with manual leak detectors and repair tools to carry out the work.

[0024] Turn off the laser signal generator 1 and laser signal receiver 2 on both sides of the leak point. Use a manual leak detector to check and verify the leak around the pipeline at the leak alarm point. After verification, use the gas extraction pipeline 4 leak repair tool to repair the leak. Restart the laser signal generator 1 and laser signal receiver 2 on both sides of the leak point. Contact the external monitoring system to check if the alarm has been cleared.

[0025] The beneficial effects of this invention are as follows:

[0026] First, it can simultaneously meet the leak detection requirements of positive and negative pressure gas transmission pipelines;

[0027] Second, it can realize synchronous real-time leak detection of the extraction pipeline network;

[0028] Third, it can quickly and automatically identify leak points in the extraction pipeline network.

[0029] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0031] Figure 1 This is a schematic diagram of the invention;

[0032] Figure 2 This is a cross-sectional view of the installation of the laser signal generator and the laser signal receiver.

[0033] Reference numerals: 1-Laser signal generator, 2-Laser signal receiver, 3-Signal collection and analysis terminal, 4-Gas extraction pipeline, 5-Signal integration substation. Detailed Implementation

[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0035] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0036] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0037] To achieve real-time leak detection in gas drainage pipelines and ensure the effectiveness of coal seam gas extraction and utilization, a leak detection system and method based on lidar for gas drainage pipelines are proposed.

[0038] The working principle of this method is as follows:

[0039] Due to site conditions, the gas extraction pipeline network requires elbows or tees to connect the gas extraction pipeline 4 at points where its direction of travel changes. Therefore, the entire gas extraction pipeline network contains several straight pipe sections. Each straight pipe section of the gas extraction pipeline network is considered a leak detection unit. Each leak detection unit has a ring-shaped laser signal generator 1 and a laser signal receiver 2 installed at its starting and ending ends, respectively. Each laser signal receiver 2 is equipped with a signal collection and analysis terminal 3. When the leak detection system is running, it emits a ring-shaped laser signal that surrounds the gas extraction pipeline 4. The laser signal receiver 2 receives the signal. When a leak occurs at a certain location in the gas extraction pipeline 4, radial airflow pressure fluctuations are generated, causing laser signal attenuation and affecting the number of lasers received by the laser signal receiver 2. The signal collection and analysis terminal 3 calculates the location of the airflow anomaly using Doppler frequency shift. The signals from all leak detection units' signal collection and analysis terminals 3 are transmitted in real-time to the ground real-time monitoring system via a signal integration substation 5, enabling real-time leak detection, leak location, and alarm for the gas extraction pipeline network.

[0040] The main steps of implementing this method are as follows:

[0041] Step 1: Leak detection unit division and determination. Based on the mine gas drainage pipeline network layout diagram, the number of straight pipe sections and corresponding parameters (corresponding pipe diameter and length) are determined to identify the leak detection units. The inner diameter of the laser signal generator 1 and laser signal receiver 2 required for different leak detection units must match the outer diameter of the corresponding straight pipe section gas drainage pipeline 4.

[0042] Step 2: Device Installation. Based on the division and determination of leak detection units in Step 1, laser signal generator 1 and laser signal receiver 2 are installed at the beginning and end of the corresponding straight pipe sections of the gas extraction pipeline 4. The beginning and end of the straight pipe sections are determined according to the gas flow direction. A signal collection and analysis terminal 3 is configured below each laser signal receiver 2 in each straight pipe section. All signal collection and analysis terminals 3 are connected to the signal integration substation 5, which is connected to the ground real-time monitoring system.

[0043] Step 3: System Debugging. After all devices and systems are installed and connected according to Step 2, turn on the leak detection system. First, check if the system can operate normally. Second, to avoid false alarms of pipeline leaks caused by changes in the underground environment, the leak detection sensitivity can be set in the system according to the site conditions during the trial operation. Third, for gas extraction pipelines with four straight pipe sections reaching 200 meters, it can be determined whether to increase the number of leak detection units in the pipeline based on the debugging results.

[0044] Step 4: Real-time Leak Detection and Monitoring. After the system is debugged to its optimal operating state, the system is restarted to begin real-time leak detection and monitoring of the gas extraction pipeline network. Laser signal generator 1 and laser signal receiver 2 will continuously generate and receive signals for scanning detection. Signal collection and analysis terminal 3 will process and analyze the signals in real time and transmit them synchronously to the ground real-time monitoring system through signal integration substation 5.

[0045] The optimal operating state is:

[0046] The system is operating normally; the leak detection sensitivity maintains a dynamic balance with the site environment; if the debugging results of a straight pipe section with a length of 200 meters are not ideal, it is necessary to increase the number of leak detection units in the pipeline until the debugging results are ideal.

[0047] Step 5: Leakage Alarm and Location. During system operation, if a leak occurs at a certain location in the gas extraction pipeline 4, radial airflow pressure fluctuations will occur, causing laser signal attenuation and affecting the number of lasers received by the laser signal receiver 2. The signal collection and analysis terminal 3 will calculate the location of the abnormal airflow through Doppler frequency shift and transmit it synchronously to the ground real-time monitoring system. The system will issue an alarm and display the alarm straight pipe section and the specific location of the leak.

[0048] Step 6: Manual verification and repair of the leak point. After receiving the alarm, the ground-based real-time monitoring system dispatches personnel with a manual leak detector and repair tools to the designated location for work. First, shut down laser signal generator 1 and laser signal receiver 2 on both sides of the leak point, and use the manual leak detector to check the leak around the pipeline at the leak alarm point; second, after verification, repair the leak using the gas extraction pipeline repair tools; third, restart laser signal generator 1 and laser signal receiver 2 on both sides of the leak point; fourth, contact the ground-based real-time monitoring system to check if the alarm has been cleared.

[0049] The key points of this invention are as follows:

[0050] Based on the principle of lidar wind measurement, and using a laser signal generator, a laser signal receiver, a signal collection and analysis terminal, and a ground real-time monitoring system, a lidar-based gas extraction pipeline network leak detection system and method are developed to achieve real-time leak detection, leak point location, and alarm for the gas extraction pipeline network.

[0051] (1) A leak detection system and method for gas extraction pipeline network based on lidar, including hardware and software such as a laser signal generator, a laser signal receiver, a signal collection and analysis terminal, and a ground real-time monitoring system. The main principle is as follows: each straight pipe section of the gas extraction pipeline network is regarded as a leak detection unit. A ring-shaped laser signal generator and a laser signal receiver are installed at the beginning and end of each leak detection unit, respectively. Each laser signal receiver 2 is equipped with a signal collection and analysis terminal. When the leak detection system is running, it can emit a ring-shaped laser signal that surrounds the pipeline. The laser signal receiver can receive the signal. When a leak occurs at a certain location in the pipeline, radial airflow pressure fluctuations will be generated, which will cause the laser signal to attenuate and affect the number of lasers received by the laser signal receiver 2. The signal collection and analysis terminal will calculate the location of the abnormal airflow through Doppler frequency shift and transmit the signal of the leak detection unit signal collection and analysis terminal to the ground real-time monitoring system in real time through the substation. Real-time leak detection, leak point location and alarm of the gas extraction pipeline network can be realized.

[0052] (2) A leak detection system and method for gas extraction pipelines based on lidar, comprising the following steps: Step 1: Leak detection unit division and determination. Step 2: Device installation. Step 3: System debugging. Step 4: Real-time leak detection and monitoring. Step 5: Leak point alarm and location. Step 6: Manual verification and repair of leak points.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A gas extraction pipeline network leak detection system based on lidar, characterized in that: The system includes several leak detection units; the leak detection unit is formed by dividing the gas extraction pipeline network into several straight pipe sections according to the laying path of the gas extraction pipeline network, with each straight pipe section being a leak detection unit; The leak detection unit is equipped with a laser signal generator (1) at one end and a laser signal receiver (2) at the other end. The laser signal generating device (1) is a ring laser signal generating device, used to emit a ring laser signal that surrounds the gas extraction pipeline (4); The laser signal receiving device (2) is used to receive the loop laser signal emitted by the laser signal generating device (1) of the leak detection unit; Each laser signal receiving device (2) is equipped with a signal collection and analysis terminal (3); All signal collection and analysis terminals (3) are connected to the signal integration substation (5) via signal connection. The signal integration substation (5) is connected to an external monitoring system; When a gas leak occurs at a certain location in the gas extraction pipeline (4), radial airflow pressure fluctuations are generated, causing the ring-pipe laser signal to attenuate, affecting the number of lasers received by the laser signal receiving device (2), and the signal collection and analysis terminal (3) uses Doppler frequency shift to calculate the location of the abnormal airflow. The signals from all signal collection and analysis terminals (3) are transmitted in real time to the external monitoring system through the signal integration substation (5) to realize real-time leak detection, leak point location and alarm of the gas extraction pipeline network.

2. A method for detecting leaks in gas extraction pipeline networks based on lidar, characterized in that: The method includes the following steps: S1: Leak detection unit division and determination; According to the mine gas extraction pipeline network laying diagram, divide the number of straight pipe sections and the corresponding pipe diameter and length of the straight pipe sections, determine the leak detection unit, and the inner diameter of the laser signal generating device (1) and laser signal receiving device (2) required for different leak detection units must match the outer diameter of the corresponding straight pipe section gas extraction pipeline (4). S2: Device installation; According to the leak detection unit divided and determined in S1, a laser signal generator (1) and a laser signal receiver (2) are installed at the beginning and end of the corresponding straight pipe section of the gas extraction pipeline (4), respectively. The beginning and end of the straight pipe section are determined according to the gas flow direction. The laser signal generator (1) is a ring laser signal generator used to emit a ring laser signal that surrounds the gas extraction pipeline (4). Each straight pipe section laser signal receiver (2) is equipped with a signal collection and analysis terminal (3). All signal collection and analysis terminals (3) are connected to the signal integration substation (5). The signal integration substation (5) is connected to the external monitoring system. S3: System debugging; check whether the system is operating normally. During the trial operation, set the leak detection sensitivity in the system according to the site conditions. For gas extraction pipeline (4) with a straight pipe section length of 200 meters, determine whether to increase the number of leak detection units in the straight pipe section of the gas extraction pipeline (4) according to the debugging results. S4: Real-time leak detection and monitoring; After the system is debugged to normal operation and the leak detection sensitivity is dynamically balanced with the field environment, the system is restarted to start the real-time leak detection and monitoring of the gas extraction pipeline. The laser signal generator (1) and the laser signal receiver (2) continuously transmit and receive signals for scanning detection. The signal collection and analysis terminal (3) processes and analyzes the signals in real time and transmits them synchronously to the external monitoring system through the signal integration substation (5). S5: Leakage alarm and location; When a gas leak occurs at a certain location in the gas extraction pipeline (4), radial airflow pressure fluctuations are generated, causing the ring pipe laser signal to attenuate, affecting the number of lasers received by the laser signal receiving device (2). The signal collection and analysis terminal (3) uses Doppler frequency shift to calculate the location of the abnormal airflow and transmits it synchronously to the external monitoring system. The system issues an alarm and displays the alarm straight pipe section and the specific location of the leak point. S6: Manual verification and repair of leak points; After receiving the alarm, the external monitoring system arranges for staff to carry manual leak detectors and repair tools to the designated location for operation. The laser signal generators (1) and laser signal receivers (2) on both sides of the leak point are turned off. The manual leak detector is used to check the leak around the pipeline at the leak alarm point. After verification, the gas extraction pipeline (4) repair tools are used for repair. The laser signal generators (1) and laser signal receivers (2) on both sides of the leak point are restarted. The external monitoring system is contacted to check whether the alarm has been cleared.

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