Device for high-precision detection of leakage of hydrogen-doped natural gas pipeline

Abstract

The invention belongs to the technical field of natural gas pipelines, and particularly relates to a high-precision hydrogen-doped natural gas pipeline leakage detection device which comprises a mounting plate, a detection pipe is arranged on at least one part of the top and / or the bottom of the mounting plate, a cavity is formed in the detection pipe, and an opening end is arranged at one end of the detection pipe. A selective permeable membrane through which hydrogen-doped natural gas passes is arranged on the pipe wall of the detection pipe, an air pressure adjusting device is arranged at the opening end of the detection pipe, the air pressure adjusting device comprises a vacuum pump, a detection device is arranged on the outer side of the detection pipe in a sleeving manner, and the detection device comprises a methane detector and a hydrogen sensor. By integrating the functions of flow detection, leakage positioning, data remote transmission and the like, whole-process automation of detection, analysis and alarm is achieved, and manual operation is reduced. Leakage point location information is generated in real time, a pipeline fault area can be quickly positioned by combining a positioning system, and the maintenance response time is shortened.

Description

Technical Field

[0001] The present invention belongs to the technical field of natural gas pipelines, and in particular relates to a device for detecting leakage of hydrogen-blended natural gas pipelines with high precision. Background Art

[0002] Hydrogen energy is a clean energy that helps reduce carbon emissions. Among them, the most widely recognized approach is to use existing natural gas pipelines to mix hydrogen in permitted proportions and supply it to residential, commercial, industrial production and other fields, which can effectively avoid the problem of pure hydrogen storage and transportation.

[0003] Existing technologies are essentially all aimed at natural gas pipeline leaks. However, because the volumetric calorific value of hydrogen is lower than that of natural gas, the Wobbe number of the mixture significantly decreases after natural gas is blended with hydrogen. This number also decreases with increasing hydrogen blending ratios. Relevant scholars have pointed out that in a mixture of 20% hydrogen and 80% natural gas, the flow rate of the mixture must be increased by 1.8 times to maintain the same energy supply. Therefore, hydrogen-blended natural gas mixtures require a larger volume flow rate, making pipeline gas leaks more likely to occur. Furthermore, because hydrogen has a low ignition energy and a wide ignition concentration, it is extremely easy to ignite. Once leaked, it can affect production operations at the very least, or even cause serious accidents such as fires and explosions, resulting in casualties. Therefore, leak detection requirements for hydrogen-blended natural gas are even stricter.

[0004] Currently available leak detection methods mainly include gas sensor detection and sensory detection. Among them, the gas sensor detection method is easily interfered by factors such as air humidity. The sensory detection method relies on manual inspections, which is inefficient and poses safety hazards. There is also a technical problem that hydrogen-blended natural gas leaks cannot be detected in a timely manner. Summary of the Invention

[0005] The present invention discloses a device for detecting leakage of hydrogen-blended natural gas pipelines with high precision, which mainly solves the problems that traditional leakage detection methods are susceptible to interference, have low efficiency and pose potential safety hazards.

[0006] To achieve the aforementioned objectives, the present invention provides a high-precision device for detecting leaks in hydrogen-blended natural gas pipelines. The device comprises a mounting plate, at least a portion of the top and / or bottom of which is provided with a detection tube. The detection tube has a chamber disposed within it, one end of the detection tube is provided with an open end, and the wall of the detection tube is provided with a selectively permeable membrane for allowing hydrogen-blended natural gas to pass through it. The open end of the detection tube is provided with a pressure regulating device comprising a vacuum pump. At least a portion of the outer surface of the detection tube is sheathed with a detection device, and several methane detectors, a hydrogen sensor, and a flowmeter are provided at corresponding positions within the pipeline to detect the methane concentration of the gas within the detection tube, a hydrogen sensor, and a flowmeter. The device is equipped with a methane detector, a hydrogen sensor, and a flowmeter, with preset methane concentration values of 1.25-2.5%vol and hydrogen concentration values of 1-2%vol. The flowmeter detects the gas flow within the detection tube. Changes in flow rate can reflect the gas state within the pipeline. Combined with the gas concentration data, a more comprehensive analysis can be made to determine whether a leak exists.

[0007] The system also includes a determination module, which uses the gas concentration values obtained by the methane detector and hydrogen sensor, as well as the flow rate data obtained by the flow meter, to make a judgment. It can not only determine whether the methane and hydrogen concentrations meet preset standards individually, but also whether both do not meet the standards simultaneously. This multi-dimensional determination method can more accurately determine pipeline leaks and avoid misjudgments.

[0008] The judgment module includes a PLC control center, a flow detection module, a leakage detection module, a point detection module, and a GPRS data remote module. These modules work together to comprehensively analyze and process the detection data to improve the accuracy of the judgment.

[0009] Based on the results of the determination module, the alarm device issues corresponding alarm messages, including those indicating excessive methane concentration, excessive hydrogen concentration, and natural gas leaks. Clear alarm classification helps quickly locate problems and improves the efficiency of leak response. Furthermore, the point detection module and GPRS data remote module enable positioning and remote monitoring, further improving the accuracy of leak detection and response.

[0010] The vacuum pump is used to form a negative pressure at the open end of the detection tube to extract the tube gas and flow along the internal cavity of the detection tube through the detection device to the open end.

[0011] Preferably, the air pressure regulating device includes a vacuum pump and a vacuum tank connected to the vacuum pump. An electric valve is also provided on the side of the vacuum tank away from the vacuum pump. The vacuum pump + vacuum tank combination accurately adjusts the pressure environment in the detection tube to ensure that the osmotic membrane operates under optimal working conditions; the drying box eliminates the interference of humidity on the test results and improves data reliability.

[0012] The electric valve automatically adjusts the gas flow to ensure the pressure balance in the detection tube and adapt to different pipeline pressure conditions.

[0013] Preferably, the humidity regulating device is a drying oven.

[0014] Preferably, the detection device includes a flow meter and a gas detector, the gas detector includes a methane detector and a hydrogen sensor, and the hydrogen sensor is a fiber optic hydrogen sensor including a light source, a single-mode optical fiber, a coupler, a sensing probe, and a photoelectric detector.

[0015] Preferably, the electric valve, gas detector and flow meter are all electrically connected to a PLC control center. Combined with a methane analyzer (to detect gas composition) and a flow meter (to monitor gas flow rate), the PLC comprehensively analyzes data to accurately distinguish normal fluctuations from leakage signals and avoid false alarms.

[0016] Preferably, the PLC control center includes a flow detection module, a leak detection module, a point detection module, and a GPRS data remote module. The GPRS module enables remote data transmission, supports cloud storage and multi-terminal access, facilitates real-time monitoring and long-term trend analysis, and improves management efficiency.

[0017] Preferably, the detection tube comprises an annular surface layer, and at least a portion of the inner surface of the surface layer is provided with a selective permeable membrane.

[0018] Preferably, the material of the selective permeable membrane is a modified lignin and polydimethylsiloxane composite material, the material of the surface layer is one of polytetrafluoroethylene mesh cloth or glass fiber mesh cloth, and the outer layer of the detection tube uses glass fiber mesh cloth as a base, which is corrosion-resistant and mechanically shock-resistant, and is suitable for complex buried or overhead pipeline environments.

[0019] Preferably, the selective permeable membrane is made of a nanoporous material prepared by modifying a polydopamine (PDA) layer on the surface of fluorinated polyimide (FPI) by a solution oxidation method.

[0020] The rubbery properties (flexibility) of the selectively permeable membrane can adapt to the pipe deformation caused by temperature changes and avoid cracking of the membrane layer.

[0021] Preferably, the PLC control center is located at a control console, which is also provided with a display screen for displaying test data, and the display screen is electrically connected to the PLC control center. The console is integrated with a display screen that displays test data (such as methane concentration and flow curve) in real time, providing intuitive guidance for on-site operations.

[0022] The technical solution provided by the present invention has at least the following technical effects: This system integrates flow detection, leak location, and remote data transmission to automate the entire detection, analysis, and alarm process, reducing manual intervention. It generates real-time leak location information and, combined with a geographic information system (GIS), can quickly locate pipeline fault areas, shortening repair response times. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0024] Figure 1 Schematic diagram of the structure of an embodiment of the present invention; Figure 2 Schematic diagram of the structure of the detection tube in the present invention; Explanation of main reference numerals: 1. Mounting plate; 2. Natural gas pipeline; 3. Detection tube; 4. Vacuum pump; 5. Vacuum tank; 6. Electronic valve; 7. Flow meter; 8. Gas detector; 9. PLC control center; 10. Control console; 11. Drying oven; 12. Display screen; 3-1. Surface layer; 3-2. Selective permeability membrane; DETAILED DESCRIPTION The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the embodiments of the present invention, and should not be construed as limiting the present invention.

[0025] In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of the embodiments of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0027] Please refer to Figure 1 , Figure 1 is a structural diagram of an embodiment of the present invention, Figure 1 The arrow in the figure indicates the direction of gas flow in the pipeline. This embodiment provides a high-precision device for detecting leakage in a hydrogen-blended natural gas pipeline, comprising a mounting plate 1. Detection tubes 3 are provided at the top and bottom of the mounting plate 1. A gas pressure regulating device is provided at one end of the detection tube 3. In this embodiment, the portion of the detection tube 3 located at the bottom of the mounting plate 1 is arranged parallel to the natural gas pipeline.

[0028] The other end of the detection tube 3 is also provided with a humidity control device, and at least a portion of the outer side of the detection tube 3 is sheathed with a detection device. The air pressure control device includes a vacuum pump 4 and a vacuum tank 5 connected to the vacuum pump 4. The vacuum tank 5 is also provided with an electric valve on the side away from the vacuum pump 4. In this embodiment, the vacuum pump 4 is located on the far left. The humidity control device is a drying oven 11, and the detection device includes a flow meter 7 and a gas detector 8.

[0029] In this embodiment, the gas detector 8 comprises a methane detector and a hydrogen sensor. The methane detector is a device used to monitor the concentration of methane (CH4) gas in the environment in real time, primarily through principles such as catalytic combustion, infrared absorption, or optical interference. Its core components include a sensor, display, and alarm system, capable of rapidly responding and outputting concentration data. The model used in this embodiment is the BX-Q610 high-performance online methane detector produced by Beijing Beixin Keyuan Instrument Co., Ltd. This model supports linkage with a PLC control system, facilitating remote monitoring and alarms, and is suitable for continuous monitoring of methane concentration. Other common methane detectors available on the market can also be used, but are not limited to these. The hydrogen sensor is primarily used to detect the concentration of hydrogen (H2) in the air. Its specific operating principle is based on existing technology and will not be elaborated here.

[0030] In this embodiment, a vacuum pump in the air pressure regulating device continuously draws air from the detection tube, creating a negative pressure within the detection tube chamber, forcing the gas in the tube to flow along the inner chamber of the detection tube to the open end. This negative pressure helps guide the gas flow in a predetermined direction, ensuring orderly detection. Furthermore, the provision of a vacuum tank and electric valve allows for better control of air pressure, making the detection process more stable and accurate.

[0031] The humidity control device can remove moisture from the gas and prevent it from affecting the test results. Because moisture may interfere with the accuracy of the gas detector, removing moisture allows the methane detector and hydrogen sensor to detect gas concentration more accurately.

[0032] The electric valve, gas detector 8 and flow meter 7 are all electrically connected to a PLC control center 9, which includes a flow detection module, a leakage detection module, a point detection module and a GPRS data remote module. The detection tube 3 includes a circular surface layer 3-1, and at least a portion of the inner surface of the surface layer 3-1 is provided with a selective permeable membrane 3-2.

[0033] In this embodiment, the selective permeable membrane 3-2 is made of a composite material of modified lignin and polydimethylsiloxane. The modified lignin is prepared by reacting sodium lignin sulfonate with formaldehyde under alkaline conditions. After hydroxylation, it forms a three-dimensional aromatic ring network structure, enhancing its affinity and compatibility with methane. The polydimethylsiloxane serves as a rubbery polymer matrix. The hydrocarbon groups in its network structure have a natural affinity for methane, while also providing flexibility and processability. The two are mixed using a crosslinking agent. The surface layer 3-1 is made of a glass fiber mesh.

[0034] The PLC control center 9 is arranged above the console 10. The console 10 is also provided with a display screen 12 for displaying detection data. The display screen 12 is electrically connected to the PLC control center 9. The display screen 12 can display the data collected by the detection device to facilitate maintenance personnel to understand the specific situation and improve work efficiency.

[0035] When this embodiment is working, the gas leak is detected by the gas detector 8, and the detected data is collected and processed by the PLC control center 9 to obtain the leakage point, and finally the real-time data remote transmission is realized through the GPRS data remote module.

[0036] Please refer to Figure 2 , Figure 2 The present invention also provides a method for preparing a selective permeable membrane 3-2, comprising the following steps: S1: Preparation of modified lignin; S2: Modified lignin is blended with vinyl acetate polymer (PVAc) to prepare composite functional material H-SL / PDMS; S3: Prepare the test tube membrane.

[0037] The modified lignin preparation method comprises the following steps: adding 60 g of sodium lignin sulfonate and deionized water in a mass ratio of 5-10% to a 1000 ml flask, adjusting the pH to 8.7 using a 6 wt % NaOH solution, and then uniformly mixing at 80° C. and 1200 r / min. Then, dropwise adding a formaldehyde solution in a mass ratio of sodium lignin sulfonate to formaldehyde of 1:1 for reaction for 1.5 hours. After the mixed solution in the flask is cooled to room temperature, the pH is adjusted to 4 using a 0.1 mol / L hydrochloric acid solution. Finally, the mixed solution is centrifuged for 20 minutes to obtain a modified lignin (H-SL), which is then dried in a drying oven 11 at 40° C. for 72 hours. The dried modified lignin (H-SL) is then repeatedly ground using a ball mill for 2 hours, and then packaged for later use.

[0038] The preparation method of the composite functional material H-SL / PDMS is as follows: 30 g of modified lignin (H-SL) is placed in an oven and baked at 90°C for 1 hour. After natural cooling, the mixture is placed in a container for storage. The modified lignin (H-SL) is mixed with 200 g of vinyl acetate polymer (PVAc). 120 g of n-hexane is added, and the mixture is ultrasonically treated for 30 minutes. After that, 16 g of a cross-linking agent is added, and the mixture is stirred at 50°C for 3 hours to obtain the composite functional material H-SL / PDMS.

[0039] The crosslinking agent is tetraethyl orthosilicate (TEOS).

[0040] The preparation method of the detection tube 3 membrane includes the following steps: S31: The surface layer 3-1 is a base mesh. The base mesh is first pretreated by soaking it in deionized water for 2-3 hours. After soaking, the base mesh is repeatedly rinsed with deionized water and dried in a sealed vacuum drying oven 11. The pretreated base mesh is placed on a glass plate and fixed with clips. S32: ultrasonically stirring the composite functional material H-SL / PDMS for another 10 minutes; S33: The composite functional material H-SL / PDMS is spread on the base mesh, and then scraped to prepare a selective permeable membrane 3-2. The prepared selective permeable membrane 3-2 is placed in a blast drying oven 11 for drying for 15 minutes.

[0041] In this embodiment, the selectively permeable membrane in the detection tube allows hydrogen-doped natural gas to pass through. This property helps filter out the target gas, reduce interference from other gases, and improve the specificity of detection. The membrane is made of a composite material of modified lignin and polydimethylsiloxane. This special material selection allows methane and hydrogen to pass through while blocking other unwanted gases, thereby improving detection accuracy.

[0042] The material of the surface layer is one of polytetrafluoroethylene mesh cloth or glass fiber mesh cloth. This material, in combination with the selective permeability membrane, helps to maintain the stability of the gas environment inside the detection tube, further ensuring the accuracy of the detection.

[0043] According to another embodiment of the present invention, the selective permeable membrane in this embodiment is made of a nanoporous material prepared by modifying a polydopamine (PDA) layer on the surface of fluorinated polyimide (FPI) by a solution oxidation method.

[0044] The present invention has at least the following advantages: 1. High sensitivity and selective detection capabilities: The membrane utilizes a composite material of modified lignin (H-SL) and PDMS. Its three-dimensional aromatic ring network and hydrocarbon-based properties have a high affinity for methane, preferentially adsorbing and permeating methane, significantly improving selectivity for leaked gases and reducing interference from other gases (such as hydrogen and carbon dioxide). The microporous channels (nanoscale) achieve efficient separation of methane molecules through a molecular sieve effect, achieving detection sensitivity at the ppm level.

[0045] Combining the gas detector 8 (detecting gas composition) and the flow meter 7 (monitoring gas flow rate), the PLC comprehensively analyzes the data to accurately distinguish normal fluctuations from leakage signals and avoid false alarms.

[0046] 2. Intelligent and automated control: It integrates functions such as flow detection, leak location, and remote data transmission (GPRS module) to achieve full automation of detection, analysis, and alarm, reducing manual intervention.

[0047] Generate leakage point information in real time, and combined with the Geographic Information System (GIS), quickly locate pipeline fault areas and shorten maintenance response time.

[0048] Remote data transmission is achieved through the GPRS module, supporting cloud storage and multi-terminal access, facilitating real-time monitoring and long-term trend analysis, and improving management efficiency.

[0049] 3. Environmental adaptability and stability: Air pressure and humidity control system: The vacuum pump 4 + vacuum tank 5 combination accurately adjusts the pressure environment in the detection tube 3 to ensure that the permeable membrane operates under optimal working conditions; the drying oven 11 eliminates the interference of humidity on the test results and improves data reliability.

[0050] The electric valve automatically adjusts the gas flow rate to ensure the pressure balance in the detection tube 3 and adapt to different pipeline pressure conditions.

[0051] The outer layer of the detection tube 3 uses glass fiber mesh cloth as a base, which is corrosion-resistant and mechanically impact-resistant and is suitable for complex buried or overhead pipeline environments.

[0052] The rubbery properties (flexibility) of the selective permeable membrane 3-2 can adapt to the pipe deformation caused by temperature changes and avoid cracking of the membrane layer.

[0053] 4. Structural design and engineering applicability: The detection tube 3 and the mounting plate 1 adopt a split design, which supports quick disassembly and replacement; the detection device is external, which is convenient for calibration and maintenance.

[0054] The console 10 is integrated with a display screen 12 to display detection data (such as methane concentration and flow curve) in real time, and to intuitively guide on-site operations.

[0055] The detection tube 3 is arranged parallel to the natural gas pipeline and can cover leakage-prone areas such as straight pipe sections, elbows, valves, etc. It is suitable for urban pipeline networks, long-distance pipelines and industrial gas systems.

[0056] Supports the detection of hydrogen-blended natural gas mixtures to meet the compatibility requirements of future hydrogen energy transmission pipelines.

[0057] 5. Economic Benefits and Safety Improvement: Automated detection reduces the frequency of manual inspections and saves labor costs; high-precision positioning of leak points can avoid large-scale excavation and repairs, reducing repair costs.

[0058] The early leakage warning capability effectively prevents the risk of explosion caused by methane accumulation, ensuring personnel safety and the integrity of pipeline facilities.

[0059] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A device for high-precision detection of hydrogen-blended natural gas pipeline leaks, characterized by: include: a mounting plate, a bracket being provided at the bottom of the mounting plate, a detection tube being provided at at least a portion of the top and / or bottom of the mounting plate, a chamber being provided inside the detection tube, an open end being provided at one end of the detection tube, a selective permeation membrane being provided on the tube wall of the detection tube for allowing hydrogen-blended natural gas to pass therethrough, a gas pressure regulating device being provided at the open end of the detection tube, the gas pressure regulating device comprising a vacuum pump, wherein the vacuum pump continuously draws gas from the detection tube and creates a negative pressure in the chamber of the detection tube, causing the tube gas to flow along the internal chamber of the detection tube to the open end; A detection device, comprising at least one methane detector, a hydrogen sensor, and a flow meter disposed at corresponding positions on the pipeline; The determination module is connected to the corresponding component in the detection device, and is used to determine whether the gas in the detection tube cavity meets the preset standard based on the information obtained by the detection device.

2. The device for detecting leakage of hydrogen-blended natural gas pipelines with high precision according to claim 1, characterized in that: The determination module is configured to determine whether a methane concentration value of the gas in the detection tube chamber obtained by the methane detector meets a preset standard, and whether a hydrogen concentration value of the gas in the detection tube chamber obtained by the hydrogen sensor meets a preset standard. Furthermore, when the determination module determines the methane concentration value and the hydrogen concentration value of the gas in the detection tube chamber, it is configured to determine whether both the methane concentration value and the hydrogen concentration value do not meet the preset standard at the same time.

3. The device for detecting leakage of hydrogen-blended natural gas pipelines with high precision according to claim 2, characterized in that: in, The preset standard for methane concentration value is 1.25~2.5%vol, and the preset standard for hydrogen concentration value is 1~2%vol. It also includes an alarm device, which is connected to the detection device and the judgment module. The alarm device is used to issue corresponding alarm information according to the judgment result of the judgment module. The alarm information includes information on excessive methane concentration, excessive hydrogen concentration and natural gas leakage.

4. The device for detecting leakage of hydrogen-blended natural gas pipelines with high precision according to claim 1, characterized in that: The air pressure regulating device also includes a vacuum tank. A vacuum chamber is provided inside the vacuum tube. The vacuum chamber is connected to the internal cavity of the detection tube. An electric valve is also provided on the side of the vacuum tank away from the vacuum pump.

5. The device for detecting leakage of hydrogen-blended natural gas pipelines with high precision according to claim 1, characterized in that: A humidity regulating device is further provided at one end of the detection tube away from the open end, and the humidity regulating device is a drying box.

6. The device for detecting leakage of hydrogen-blended natural gas pipelines with high precision according to claim 3, characterized in that: The alarm device includes a point detection module and a GPRS data remote module.

7. The device for detecting leakage of hydrogen-blended natural gas pipelines with high precision according to claim 6, characterized in that: The determination module includes a PLC control center, a flow detection module, a leakage detection module, a point detection module and a GPRS data remote module.

8. The device for detecting leakage of hydrogen-blended natural gas pipelines with high precision according to claim 1, characterized in that: The detection tube includes an annular surface layer, and at least a portion of the inner surface of the surface layer is provided with a selective permeation membrane.

9. The device for detecting leakage of hydrogen-blended natural gas pipelines with high precision according to claim 8, characterized in that: The selective permeable membrane is made of a composite material of modified lignin and polydimethylsiloxane, and the surface layer is made of a polytetrafluoroethylene mesh or a glass fiber mesh.

10. The device for detecting leakage of hydrogen-blended natural gas pipelines with high precision according to claim 7, characterized in that: The determination module is arranged on a console, and the console is also provided with a display screen for displaying detection data.

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