Buried gas leakage gas distribution collection and monitoring pipe network

Abstract

The application provides a buried gas leakage gas distribution collection and monitoring pipe network, which comprises a collection pipeline arranged in parallel with a gas pipeline and a plurality of waterproof and breathable gas collection pipe sections distributed on the collection pipeline at intervals, leaked gas can enter the collection pipeline from the adjacent gas collection pipe sections and be detected by a monitoring sensor, and the monitoring sensor transmits the data of the detected leaked gas to a signal terminal through wireless signal transmission or transmits the data to a remote signal terminal through a wired signal line. The monitoring pipe network of the application can monitor the pipeline leakage in the early and middle stages, the distributed collection pipe sections can collect the leaked gas in a distributed and efficient manner, effective and reliable monitoring is achieved, and the real-time signal monitoring device arranged synchronously can realize good timeliness and high reliability of the gas monitoring, the whole monitoring pipe network is economical and reasonable, and the risk of safety accidents such as gas pipeline explosion is reduced to the maximum extent.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of gas safety monitoring, oil pipeline safety monitoring and gas sensor, and particularly relates to a buried gas leakage gas distribution collection and monitoring pipe network. BACKGROUND

[0002] The prior art CN102518948B proposes a device and method for online detection of gas leakage. The method uses negative pressure to make the leaked gas enter the detection pipe and flow to the detection terminal, and then controls the negative pressure container device to record the gas leakage time, concentration and the like, so as to realize high-precision leakage detection and positioning. However, this method needs to use high-precision negative pressure detection equipment, which is difficult to cooperate with the laying of gas pipelines and is not easy to install. To achieve high-precision positioning, a large number of detection devices need to be arranged along with the laying of gas pipelines. Obviously, the detection equipment of this technology is not suitable for long-distance, widely distributed and buried gas pipelines.

[0003] The best gas leakage detection method in the prior art is as follows: first, the approximate range of gas leakage is confirmed by hole detection and adjacent well chamber and municipal well detection, and then buried gas leakage monitoring instruments are arranged in the gas leakage area to quickly obtain multi-point gas volume fraction distribution data, and a mature numerical model is used for rapid positioning and correction positioning. The buried gas leakage monitoring instrument needs to have a detection accuracy of 0.001% for measuring the methane volume fraction, so the unit price is 2000-3000 yuan. A large number of buried gas leakage monitoring instruments need to be buried by punching in the gas leakage area at an interval of 50 cm parallel to the pipeline and 1 m perpendicular to the pipeline. The methane volume fraction at the monitoring points is continuously monitored, which has a large amount of construction and high cost. The multi-point data is input into a numerical model based on the Dracy seepage equation, which is solved in the Matlab environment to obtain the real-time distribution of the underground methane volume fraction. Moreover, the approximate range of gas leakage needs to be confirmed by manual inspection, unmanned aerial vehicle inspection and laser remote gas monitoring. These methods have poor timeliness, high cost and high false alarm rate. In particular, the leaked gas needs to diffuse through the soil to the ground and reach a sufficient gas concentration to be monitored, which makes it difficult to monitor the pipeline leakage in the early and middle stages, misses the best monitoring and safety maintenance opportunity, and has high operating costs, personnel laxity and difficulty in inspection in some areas. Therefore, based on the existing situation, there is an urgent need for a real-time, efficient, reliable and dead-angle-free leakage gas safety monitoring technology. SUMMARY

[0004] The patent application aims at leakage monitoring of a buried long-distance gas pipeline network, and proposes a buried gas leakage gas distribution collection and monitoring pipeline network, which can timely and quickly collect leaked gas to monitoring sensors, effectively meeting the technical requirements of economic rationality, effectiveness and reliability, distributed monitoring, synchronous life and pipeline, and good timeliness of gas leakage monitoring.

[0005] A buried gas leakage gas distribution collection and monitoring pipeline network comprises:

[0006] A collection pipeline is laid in parallel with the gas pipeline and is laid in a sand layer outside the gas pipeline, a plurality of branch pipes and a plurality of water collection containers are distributed on the collection pipeline, a plurality of waterproof and breathable gas collection pipe sections are arranged on the collection pipeline between adjacent branch pipes or adjacent water collection containers, the gas collection pipe sections collect gas leaked from the gas pipeline into the sand layer into the collection pipeline and block the underground water of the soil layer and the sand layer from entering the collection pipeline;

[0007] The branch pipes are laid towards the ground, arranged in a valve well of the gas pipeline, or pre-buried in the soil layer, and power lines and signal lines extend from the branch pipes of the valve well into the collection pipeline to supply power and transmit signals to the monitoring sensors in the top of each branch pipe;

[0008] The monitoring sensors are used to detect the gas concentration in the branch pipes and report the time and the position of the branch pipe when the gas concentration reaches a threshold value;

[0009] A dehumidification device is connected to the pipeline in the collection pipeline and is used to periodically extract water vapor in the collection pipeline and liquid water in the water collection containers, and the water collection containers are used to collect the condensed liquid water in the collection pipeline;

[0010] An industrial computer receives the information reported by the monitoring sensors in the collection pipeline, queries the position and number of the monitoring sensor that reports the earliest information, queries the report information of the monitoring sensors adjacent to the monitoring sensor number, extracts the report information of the monitoring sensor with the nearest report time, calculates the time difference of the two monitoring sensors reporting that the gas reaches the threshold value, and calculates the starting position of the gas diffusion according to the diffusion model of the gas and the positions of the two monitoring sensors.

[0011] Advantageously, the branch pipe is laid towards the ground, which makes the monitoring sensor at the top of the branch pipe higher than the collecting pipe, and is conducive to collecting gas and avoiding being flooded by water. Meanwhile, the monitoring sensor at the top of the branch pipe is closer to the ground, which is convenient for maintenance after excavation. In addition, when the branch pipe is arranged in the valve well of the gas pipe, the power line and the signal line extend from the branch pipe of the valve well to the collecting pipe to supply power and transmit signals for the monitoring sensor in each branch pipe. The power can be obtained from the power supply facility on the ground, and the signal can be connected with the communication facility on the ground to transmit the detection information. The water collecting container is arranged below the collecting pipe and is connected with the collecting pipe in a water-tight and air-tight manner to collect the condensed water of the moisture in the collecting pipe. When the waterproof and air-permeable gas collecting pipe section and the collecting pipe are laid in the sand layer around the gas pipe, the sand layer is loose relative to the soil layer. Therefore, once the gas pipe leaks, the gas will permeate from the sand layer to the waterproof and air-permeable gas collecting pipe section, which is conducive to quickly collecting the leaked gas, so that the small leakage of the gas pipe can be found in a timely and sensitive manner. The gas collecting pipe section has the characteristics of waterproof and air permeability, which can avoid the rainwater permeating into the gas collecting pipe section to avoid blocking the collecting pipe. Meanwhile, the collecting pipe is preferably laid in the sand layer above the gas pipe to avoid or reduce being flooded by underground water.

[0012] The above measures make the monitoring system of the present application low in cost, realizes long-distance and high-precision positioning detection of the leakage of the underground gas pipe, and the collecting pipe node is arranged in the valve well of the gas pipe, which is the inherent cost of the gas pipe construction. The collecting pipe and the gas pipe are simultaneously pre-buried in the underground trench, and the filler is taken on site. When the sand particles are filled, the engineering budget is almost not increased. The cost of the monitoring system of the present application is only composed of the collecting pipe, the branch pipe, the power line, the signal line, the dehumidifying device, the water collecting container and the monitoring sensor. Except for the monitoring sensor, the cost is low, and the cost is mainly occupied by the monitoring sensor. Due to the use of the gas collecting pipe, the monitoring sensor can use a monitoring sensor with medium sensitivity, and the batch purchase price is only hundreds of yuan per sensor. According to the need, five to twenty monitoring sensors are arranged per kilometer. When the gas pipe between two monitoring sensors leaks, the time difference of the sensor sensing can be further detected when a certain concentration of leaked gas is detected by the two monitoring sensors. Based on the gas sensor diffusion model, the leakage position can be accurately calculated.

[0013] The pipe diameter of the collecting pipe is 0.5 cm to 50 cm, and the material of the collecting pipe is any one of a plastic pipe, a plastic-metal composite pipe and a cast iron pipe.

[0014] The length of the waterproof and air-permeable gas collecting pipe section is 0.5 cm to 10 cm, the spacing between adjacent gas collecting pipe sections is 0.5 m to 5 m, and a plurality of gas collecting pipe sections are installed on the collecting pipe to form a distributed gas collecting pipe line.

[0015] The gas collection pipe section comprises a hollow cavity through the front and rear end surfaces, the cavity is connected with the through hole in the opening area, the waterproof and breathable film is attached to the opening area of the cavity section and covers the through hole, the mesh cover is arranged outside the film, the mesh cover covers the film and is connected and installed with the outer wall of the cavity through the fixed connecting piece to form a waterproof and breathable gas collection pipe section, and the material of the film is preferably expanded polytetrafluoroethylene film (ePTFE), and the area of the mesh cover is not more than the surface area of the cavity.

[0016] The cavity is a cylindrical or square pipeline with a through hole in the wall surface, the mesh cover covers the waterproof and breathable film, and the two ends of the cavity are connected and installed with the collection pipeline through the fixed connecting piece.

[0017] Advantageously, the mesh cover sleeve can protect the film sleeve and avoid being blocked by fine sand in the sand layer. The waterproof and breathable film made of ePTFE film material has a pore diameter of less than 2.0 microns, and the size of a gas molecule is about 0.0004 microns. Therefore, the pore diameter of the ePTFE film is 250-25000 times larger than the diameter of the gas, so that the gas can pass through, and the diameter of a capillary water drop is 500 microns, which is hundreds of times larger than the pore diameter of the film. These micropores can prevent water, dirt and debris from entering, the air permeability of the ePTFE film is 76.66-90 mL / cm·s, the ePTFE film can be used at-50-150℃, and is soft and has strong chemical inertness. The high air permeability of the ePTFE film allows the small amount of gas leaked from the small leakage point of the gas pipeline to quickly pass through the film and gather in the collection pipeline to form a high-concentration gas environment, thereby reducing the requirement for the sensitivity of the monitoring sensor, and a high-performance-price-ratio monitoring sensor can be used. Therefore, a lower-cost monitoring sensor can be used, and because the concentration of the gas gathered near the leakage point in the collection pipeline is high, the concentration of the gas after long-distance diffusion in the collection pipeline is high, the arrangement density of the monitoring sensor can be reduced, the cost is further reduced, and good, effective, long-distance distributed, high-performance-price-ratio leakage gas collection and monitoring are achieved.

[0018] The gas collection pipe section is connected with the adjacent collection pipeline through the pipeline in the inner ring in a gas-tight and water-tight manner, and the gas collection pipe section can be sleeved on the inner wall of the two adjacent collection pipelines or be sleeved outside the inner wall of the two adjacent collection pipelines.

[0019] The through hole is an array of small holes formed in the pipeline by mechanical drilling or laser opening.

[0020] The gas collection pipe section comprises a pipe section with a through hole on the pipe wall of a section of collection pipeline, a waterproof and air-permeable fixing sleeve is sleeved outside the section of pipeline and covers the through hole, the thickness of the fixing sleeve is 0.1 mm to 100 mm, and the two ends of the fixing sleeve are water-tightly connected with the outer wall of the pipeline to form a waterproof and air-permeable gas collection pipe section, and the fixing sleeve is made of plaster or purple sand porcelain.

[0021] The plaster or purple sand porcelain has similar performance to the ePTFE film, is air-permeable and waterproof, is more resistant to water bubbles, and has a longer service life.

[0022] The gas collection pipe section comprises a waterproof and air-permeable pipe, the two ends of the waterproof and air-permeable pipe are water-tightly connected with adjacent collection pipelines, the waterproof and air-permeable pipe can be sleeved on the inner wall of the collection pipeline or the outer wall of the collection pipeline, and the waterproof and air-permeable pipe is made of plaster or purple sand porcelain.

[0023] The monitoring sensor comprises a gas sensor, a vibration sensor and a temperature sensor, the monitoring sensor is packaged in a sealed sensor box, the sensor box is communicated with the branch pipe through a section of thin pipe, and the monitoring sensor is buried in the soil near the ground above the collection pipeline.

[0024] The sensor box is provided with a moisture extraction device and discharges moisture to the outside of the soil.

[0025] The present application has the following beneficial effects:

[0026] 1) The present application synchronously and parallelly lays a small-diameter and low-cost leakage gas collection pipeline with the monitored gas pipeline, a large number of leakage gas collection pipe sections are arranged at intervals during pipeline laying, on the one hand, the pipeline cost is reduced, and on the other hand, the problem of distributed collection of leakage gas is solved, the leakage gas can be distributedly and fully effectively collected, only a limited number of gas monitoring sensors are used, the high-performance-price-ratio, high-precision positioning, high timeliness, no dead angle and high reliability monitoring and alarm of gas leakage can be realized on a long-distance gas pipeline, and the technical difficulty of long-distance gas pipeline leakage monitoring which has not been solved for a long time is fundamentally solved.

[0027] 2) The leaky gas collection pipeline of the present application adopts a distributed "waterproof and breathable" pipe section, which can only collect gas in the soil, while preventing liquid water in the soil after rain from seeping into the collection pipeline, ensuring the long-term, reliable and safe operation of the collection pipeline, the same service life as the gas pipeline, and eliminating the huge engineering quantity and high cost of replacing the collection pipeline. In addition, the collection pipeline network of the present application is equipped with a moisture extraction device, which can regularly extract water vapor in the collection pipeline, and a water collection container is arranged in the pipe section where water is easily accumulated in the sand layer, effectively recovering the water vapor condensate that is not extracted near the collection pipeline, ensuring the long-term, stable and safe operation of the collection pipeline;

[0028] 3) The monitoring sensor of the present application is equipped with a gas sensor, and also equipped with a vibration sensor, which can simultaneously solve the long-term difficult problem of external force excavation damage of the gas pipeline;

[0029] 4) The present application simultaneously sets up real-time signal monitoring equipment in the collection pipeline, i.e. laying power lines and signal lines, and connecting power supply, receiving sensor signals and sending interaction signals with monitoring sensors in the branch pipes of the collection pipeline, to monitor the collected leaked gas in the collection pipeline in real time and intelligently. The entire monitoring network has the following advantages: on the one hand, it can realize power supply to the distributed monitoring sensors in the network, i.e. efficient signal collection and transmission, solving the long-term power supply problem of distributed Internet of Things; on the other hand, the gas leakage monitoring network of the present application can avoid using manual inspection, unmanned aerial vehicle inspection and laser remote gas monitoring methods, which have poor timeliness, high cost and high false alarm rate. Especially when the leaked gas diffuses through the soil to the ground and reaches a sufficient gas concentration to be monitored, it is impossible to monitor the pipeline leakage in the early and middle stages, and the best monitoring and safety maintenance opportunity is easily missed. Therefore, when the monitoring network of the present application is used for buried gas pipeline leakage monitoring, it can monitor in the early and middle stages of pipeline leakage, and the distributed collection pipe sections can widely and efficiently collect leaked gas, achieving effective and reliable monitoring. With the help of the real-time signal monitoring device arranged synchronously, it can realize timely gas monitoring, and the entire monitoring network is economical and reasonable, which can greatly reduce the risk of explosion and other safety accidents, and provide a high cost-effective, real-time alarm and accurate positioning technical prevention means for the gas pipeline network. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic diagram of the gas leakage gas distribution collection and monitoring network of the present application;

[0031] Figure 2 is a structural schematic diagram of the gas leakage gas collection pipeline of the present application;

[0032] Figure 3is the sectional structure schematic diagram of the gas leakage gas collection pipeline in the present application, wherein Figure 3 (a) of is the sectional structure schematic diagram of the gas leakage gas collection pipeline laying process, Figure 3 (b) of is the sectional structure schematic diagram of the collection pipeline laying process with a water collecting container;

[0033] Figure 4 is the assembly structure schematic diagram of the waterproof and breathable gas collection pipe section made of ePTFE material;

[0034] Figure 5 is the structure schematic diagram of the inner sleeve installation of the pipe section shown in Figure 4 ;

[0035] Figure 6 is the structure schematic diagram of the outer sleeve installation of the pipe section shown in Figure 4 ;

[0036] Figure 7 is the structure schematic diagram of the integrated waterproof and breathable gas collection pipe section made of plaster or purple sand ceramic material;

[0037] Figure 8 is the structure schematic diagram of the inner sleeve installation of the waterproof and breathable pipe;

[0038] Figure 9 is the structure schematic diagram of the outer sleeve installation of the waterproof and breathable pipe.

[0039] In the figure: 1-gas pipeline, 2-buried sand layer, 3-soil layer, 4-collection pipeline, 5-gas collection pipe section, 6-power line / signal line, 7-monitoring sensor, 8-water collecting container, 9-valve well, 10-solar cell panel, 11-wireless antenna, 12-branch pipe, 41-through hole, 42-pipeline, 51-waterproof and breathable film, 52-net cover sleeve, 53-fixing connector, 54-waterproof and breathable fixed sleeve, 55-waterproof and breathable pipe. DETAILED DESCRIPTION

[0040] The present application will be further described in detail below in combination with the drawings and specific embodiments, but the embodiments should not be understood as limiting the present application.

[0041] In the following embodiments, the waterproof and breathable film can be directly customized and purchased, and the waterproof and breathable film BW1700 made of ePTFE film material of Changzhou Chuangcheng Technology Co., Ltd. is specifically selected;

[0042] In the following embodiments, the fixed sleeve can be made of plaster or purple sand ceramic.

[0043] The present application provides a buried gas leakage distribution collection pipeline and monitoring system following the laying of a gas pipeline, likeFigure 1 As shown, the gas pipeline 1 is laid in the soil layer 3, and the outer peripheral surface of the gas pipeline 1 is covered by the sand layer 2, and the gas leaked from the gas pipeline 2 diffuses in the sand layer 2.

[0044] As shown in Figure 1 and Figure 2 , the collection pipeline 4 is laid in the sand layer 2 around the gas pipeline 1, and the valve well 9 is provided in matching with the gas pipeline 1, which vertically penetrates the soil layer 3 and the sand layer 2, and the bottom thereof communicates with the space where the gas pipeline is located, and the top thereof communicates with the ground space, so as to facilitate manual access to the space where the gas pipeline is located for maintenance of the gas pipeline. As shown in Figure 1 , the power supply and communication facilities such as the solar panel 10 and the wireless antenna 11 are provided on the ground near the valve well 9. A plurality of branch pipes 12 and a plurality of water collection containers 8 are distributed and arranged on the collection pipeline 4, a part of the branch pipes 12 are located in the valve well 9 and are directed to the outlet of the valve well 9, and a part of the branch pipes 12 are reserved in the soil layer 3 after penetrating through the sand layer 2 and are directed to the ground, each branch pipe 12 is connected with the corresponding interface on the collection pipeline 4 in air tightness and water tightness, and the top of each branch pipe 12 is provided with a monitoring sensor 7. A plurality of water collection containers 8 are arranged in the sand layer 2 below the collection pipeline 4, and the water collection containers 8 communicate with the collection pipeline 4, and when the temperature drops, the water vapor may condense into liquid water, the condensed liquid water can flow along the inner wall of the collection pipeline 4 and collect into the water collection containers 8, thereby playing a role of collecting water vapor. The power supply line / signal line 6 of the power supply and communication facilities is laid along the collection pipeline 4 and its branch pipes 42, and is connected with the monitoring sensor 7 on each branch pipe 42 of the collection pipeline 4, and the power supply line / signal line 6 is connected with the power supply and communication facilities near the valve well 9 after penetrating out of the branch pipe 12 located at the valve well 9, and the power supply line / signal line 6 obtains power and signal from the power supply and communication facilities on the ground, thereby providing power and signal transmission channel for the monitoring sensor 7, and meanwhile the monitoring sensor 7 transmits the received monitoring signal to the wireless antenna 11 through the power supply line / signal line 6. Alternatively, the monitoring sensor 7 can transmit the signal to the terminal equipment through the wireless signal and the signal receiving point of the communication facilities on the ground, i.e. the wireless antenna 11. A vibration sensor is also provided on the monitoring sensor 7, which sends a pre-warning signal when the gas pipeline is vibrated due to external excavation to avoid being damaged.

[0045] The monitoring sensor is used to detect the gas concentration in the branch pipe and report the following information when the gas concentration reaches the threshold value: the time when the threshold value is reached, the location and number of the branch pipe; the industrial computer receives the information reported by each monitoring sensor in the collection pipeline, queries the location and number of the monitoring sensor that reports the earliest information, queries the reporting information of the monitoring sensors adjacent to the monitoring sensor number, extracts the reporting information of the monitoring sensor with the most recent reporting time, calculates the time difference between the two monitoring sensors reporting that the gas reaches the threshold value, and calculates the starting point of the gas diffusion according to the diffusion model of the gas and the positions of the two monitoring sensors. Specifically, the laying structure of the collection pipeline 4 and the gas pipeline 1 is as shown in Figure 1 The collection pipeline 4 is located above the gas pipeline 1, and a plurality of gas collection pipe sections 5 are arranged on the collection pipeline 4 at intervals, and a plurality of gas collection pipelines 5 are arranged between adjacent branch pipes 12 or adjacent water collecting containers 8. The gas collection pipe section 5 has the function of being permeable to gas and impermeable to water. The gas leaked from the gas pipeline 1 penetrates into the gas collection pipeline 5 after diffusion in the sand layer 2. The liquid water that may exist in the soil layer 3 and the sand layer 2 is blocked outside the collection pipeline 4 by the gas collection pipe section 5. Only the gas and water vapor can enter the collection pipeline 4 through the gas collection pipe section 5 and be detected and identified by the adjacent monitoring sensor 7.

[0046] As shown in Figure 3 , it is a cross-sectional view of the laying structure of the collection pipeline 4. Since the power line / signal line 6 is laid in the collection pipeline 4 at the same time, the water vapor carried by the gas leakage can penetrate into the collection pipeline 4 from the gas collection pipe section 5. A dehumidifying device is arranged at the branch pipe 12 of the valve well 9. The dehumidifying device is connected to the water collecting container through a pipeline, and can timely remove the water vapor. The water collecting container 8 can prevent the collection pipeline 4 and the power line / signal line 6 inside it from being soaked in liquid water all the time. The liquid water in the water collecting container 8 will be periodically removed by the dehumidifying device.

[0047] Further, the pipe diameter of the collection pipeline 4 is 0.5cm to 50cm, preferably 2cm to 5cm, and the pipe material is plastic pipe, plastic-metal composite pipe, cast iron pipe, etc. low-cost pipe material, preferably PE plastic pipe.

[0048] Further, the length of the gas collection pipe section 5 which is permeable to gas and impermeable to water is 0.5cm to 10cm, preferably 1cm to 2cm, and the spacing between adjacent gas collection pipe sections 5 is 0.5m to 5m, preferably 1m to 2m. A large number of gas collection pipe sections 5 are arranged at intervals on the collection pipeline 4 to form a distributed gas collection pipeline.

[0049] Optionally, the gas collection pipe section 5 can be a waterproof and breathable structure integrated with the collection pipeline 4, or a detachable assembly installation structure formed with the collection pipeline 4.

[0050] Embodiment 1

[0051] As shown in Figure 4 , when the waterproof and breathable gas collection pipe section 5 is made of ePTFE material, the gas collection pipe section 5 includes a pipe 42 with a moderate length, and the pipe wall of the middle section of the pipe 42 is uniformly distributed with through holes 41. A waterproof and breathable film 51 is wrapped around the pipe section of the pipe 42 provided with the through holes 41, and a mesh cover sleeve 52 is further provided on the outer periphery of the waterproof and breathable film 51. The two ends of the mesh cover sleeve 52 are water-tightly connected and installed with the outer walls of the two ends of the pipe 42 through fixed connecting pieces 53. The mesh cover sleeve 52 is used to cover the outside of the waterproof and breathable film 51 to prevent the sand in the sand layer 2 from contacting the internal waterproof and breathable film 51, thereby protecting the waterproof and breathable film 51 and avoiding blockage.

[0052] In order to facilitate the detachable installation and connection of the above-mentioned assembly structure of the gas collection pipe section 5 and the collection pipe 4, the gas collection pipe section 5 can be sleeved on the inner wall of the collection pipe 4, that is, as shown in Figure 5 ; or the gas collection pipe section 5 can be sleeved on the outer wall of the collection pipe 4, that is, as shown in Figure 6 . The leaked gas escaping from the sand layer 2 penetrates into the collection pipe 4 through the waterproof and breathable film 51, and is then detected by the monitoring sensor 7. The liquid water in the sand layer 2 is blocked outside the collection pipe 4, and the water condensed in the collection pipe 4 can be collected into the water collecting container 8 along the inner wall of the collection pipe 4.

[0053] Among them, the waterproof and breathable film 51 is selected from the waterproof and breathable film made of ePTFE film material on the market, the micropore diameter of which is <2.0 μm, and the gas molecule size is about 0.0004 μm. The ePTFE film pore size is 250~25000 times larger than the gas diameter, so the gas can pass through smoothly. The diameter of the capillary water droplet is about 500 μm, which is hundreds of times larger than the film micropore diameter. At the same time, the ePTFE film material is hydrophobic, so these micropores can prevent water, dirt and debris from entering. The air permeability of the ePTFE film is 76.66~90 mL / cm·s, and the ePTFE film can be used at -50~150 ℃, and is corrosion-resistant and has long service life. The mesh cover sleeve can be made of corrosion-resistant and low-cost geotextile, or other breathable building materials. The pipe 42 can be connected with the collection pipe 4 as a whole, or can be detachably connected and installed with the collection pipe 4. The through holes 41 are arrayed small holes formed on the pipe 42 by mechanical drilling or laser drilling method, and the diameter of the arrayed small holes is preferably 0.1 millimeter to 10 millimeters.

[0054] For example, when the gas pipeline diameter is 1.4 meters, the excavated trapezoidal trench for burying the gas pipeline has a bottom width of 2.2 meters and a slope ratio of 1:0.75, and the upper 0.5 meters of the gas pipeline is filled with sand, so the buried sand layer is 1.9 meters high, and the width of the top of the buried sand layer is 2*1.9*(1 / 0.75)+2.2=7.27 meters, the cross-sectional area of the gas pipeline is 1.54m 2 , the cross-sectional area of the trapezoidal trench is 8.99m 2 , the cross-sectional area of the buried sand layer is 7.45m 2 , the porosity of the sand is 38%, and the pore volume of the buried sand layer per meter is 7.45*1*0.38=2.83 m 3 If the monitoring sensor can monitor 0.001% of methane, at least 28mL of gas needs to leak into the buried sand layer per meter of gas pipeline. In this embodiment, there is a 2~4cm gas collection pipe section on each meter of the collection pipeline. According to the gas permeability of the gas collection pipe section, which is 76.66~90mL / cm·s, it only takes 0.24~0.87s for the monitoring sensor at the leakage point to detect the gas pipeline leak after 28mL of gas leaks from the gas pipeline. If the sensitivity of the monitoring sensor is reduced to 0.01%, it only takes 2.4~8.7s to detect the gas pipeline leak after 28mL of gas leaks from the gas pipeline, which can quickly and real-time respond.

[0055] Moreover, due to the large volume of gas collected in the collection pipeline per unit time near the leakage point, the concentration of the gas after long-distance diffusion in the collection pipeline is high, and it can still be detected, which can reduce the arrangement density of the monitoring sensor. According to the need, five to twenty monitoring sensors are arranged per kilometer of the collection pipeline. When a gas pipeline between two monitoring sensors leaks, the time difference between the two monitoring sensors can be further detected, and the distance of the leakage point relative to the two monitoring sensors can be accurately calculated based on the gas sensor diffusion model, so as to obtain the position of the leakage point.

[0056] Embodiment 2

[0057] As shown in Figure 7 , the structure of the integrated waterproof and breathable gas collection pipe section 5 made of plaster or purple sand ceramic material, a plurality of open hole sections are arranged on the collection pipe section 5, a through hole 41 is formed on the open hole section, and a waterproof and breathable fixing sleeve 54 is covered on the outer periphery of the open hole section. The two ends of the waterproof and breathable fixing sleeve 54 are connected and installed with the outer wall of the collection pipeline 4 through the water-tight connection of the bonding structure 53. The through hole 41 is an array of small holes formed on the collection pipe section 5 by mechanical drilling or laser drilling method. The diameter of the array of small holes is preferably 0.1mm to 10mm. The waterproof and breathable fixing sleeve 54 is made of plaster or purple sand ceramic.

[0058] Embodiment 3Figure 8 As shown, the structure of the discrete waterproof and breathable gas collection pipe section 5 made of plaster or purple sand ceramic material includes a waterproof and breathable pipe fitting 55 made of plaster or purple sand ceramic material, and the two ends of the waterproof and breathable pipe fitting 55 are respectively sleeved on the inner walls of the adjacent two collection pipes 4 and are water-tightly connected with the inner walls of the collection pipes 4 through the bonding structure 53. Alternatively, as shown, Figure 9 the two ends of the waterproof and breathable pipe fitting 55 are respectively sleeved on the outer walls of the adjacent two collection pipes 4 and are water-tightly connected with the outer walls of the collection pipes 4 through the bonding structure 53.

Claims

1. A buried gas leakage gas distribution collection and monitoring pipeline network, characterized in that: it comprises a collection pipeline laid parallel to the gas pipeline, the collection pipeline is laid in the sand layer outside the gas pipeline, a plurality of branch pipes and a plurality of water collection containers are distributed on the collection pipeline, a plurality of waterproof and breathable gas collection pipe sections are arranged on the collection pipeline between adjacent branch pipes or adjacent water collection containers, the gas collection pipe sections collect the gas leaked from the gas pipeline into the sand layer into the collection pipeline and block the underground water of the soil layer and the sand layer from entering the collection pipeline; the branch pipes are laid towards the ground and are arranged in the valve well of the gas pipeline or are pre-buried in the soil layer, power lines and signal lines extend from the branch pipes in the valve well to the collection pipeline to supply power and transmit signals for the monitoring sensors in the top of each branch pipe; the monitoring sensors are used to detect the concentration of gas in the branch pipes and report the following information when the concentration of gas reaches a threshold value: the time when the threshold value is reached, the position and number of the branch pipe; a dehumidification device is connected to the pipeline in the collection pipeline and is used to periodically extract water vapor in the collection pipeline and liquid water in the water collection container, the water collection container is used to collect the condensed liquid water in the collection pipeline; an industrial computer receives the information reported by each monitoring sensor in the collection pipeline, queries the position and number of the branch pipe of the monitoring sensor that reports the earliest information, queries the report information of the monitoring sensor adjacent to the number of the monitoring sensor, extracts the report information of the monitoring sensor with the nearest report time, calculates the starting position of the gas diffusion according to the diffusion model of the gas and the positions of the two monitoring sensors. The length of the gas collection pipe section is 0.5 cm to 10 cm, the distance between adjacent gas collection pipe sections is 0.5 m to 5 m, the gas collection pipe section includes a hollow cavity with through holes on the front and rear end faces, the through holes in the cavity are connected to the outside, a waterproof and breathable film is attached to the opening area outside the cavity of the gas collection pipe section and covers the through holes, a mesh cover is provided on the outside of the waterproof and breathable film, the mesh cover covers the waterproof and breathable film and is installed in water-tight connection with the outer wall of the cavity through a fixed connecting piece, forming a waterproof and breathable gas collection pipe section, the material of the film is expanded polytetrafluoroethylene film, and the area of the mesh cover is not more than the surface area of the cavity. The pipe diameter of the collection pipeline is 0.5 cm to 50 cm, and the material of the collection pipeline is any one of plastic pipe, plastic-metal composite pipe and cast iron pipe. The cavity is a cylindrical or square pipe with through holes on the wall, the mesh cover covers the waterproof and breathable film, and the two ends of the cavity are installed in water-tight connection with the collection pipeline through fixed connecting pieces. The diameter of the through hole is 0.1 mm to 10 mm. The monitoring sensor includes a gas sensor, a vibration sensor, a temperature sensor, a battery module and a signal transceiver module, the monitoring sensor is packaged in a sealed sensor box, the sensor box is connected to the branch pipe through a thin pipe, and the monitoring sensor is buried in the soil near the ground above the collection pipeline. ​ ​ 2. The buried gas leakage gas distribution collection and monitoring pipe network according to claim 1, characterized in that, ​ 3. The buried gas leakage gas distribution collection and monitoring pipe network according to claim 1, characterized in that, ​ 4. The buried gas leak gas distribution collection and monitoring pipe network according to claim 3, characterized in that, ​ 5. The buried gas leak gas distribution collection and monitoring pipe network according to claim 4, characterized in that, A moisture extraction device is provided in the sensor box and moisture is discharged outside the soil.

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