Device for measuring concentration of hydrogen in soil and method for determining diffusion path of hydrogen

Abstract

The invention provides a device for measuring the concentration of hydrogen in soil and a method for determining a hydrogen diffusion path, and the device comprises a first gas stone and a second gas stone which are buried in the soil; one end of the air inlet pipe is connected with the first air stone, and one end of the air outlet pipe is connected with the second air stone; the other end of the gas inlet pipe is connected with a gas inlet of the return pump, and the other end of the gas outlet pipe is connected with a gas outlet of the return pump, so that a circulating hydrogen loop is formed; the measuring assembly comprises a sealing bag and a hydrogen sensor, the sealing bag is communicated with the gas inlet pipe, and the hydrogen sensor is arranged in the sealing bag so as to measure the hydrogen concentration in the circulating hydrogen loop; the hydrogen concentration obtained by the measuring device is high in accuracy.

Description

Technical Field

[0001] The present application relates to the technical field of gas measurement in soil, and in particular to a device for measuring hydrogen concentration in soil and a method for determining a hydrogen diffusion path. Background Art

[0002] As the potential of natural hydrogen as a clean energy source gradually emerges, its distribution, migration characteristics, and occurrence mechanisms on the Earth's surface have attracted widespread attention. However, current soil hydrogen measurement technologies generally suffer from the following problems: First, sampling methods have many open links and are easily affected by external air interference, resulting in dilution of hydrogen concentration; second, most methods rely on one-time sampling, making it difficult to achieve long-term monitoring of a single underground point; third, the spatial and temporal heterogeneity of hydrogen distribution in soils and the lack of a waiting mechanism for equilibrium lead to large fluctuations in measured values, affecting the representativeness and repeatability of the data. Summary of the Invention

[0003] In view of this, the purpose of this application is to propose a device for measuring hydrogen concentration in soil and a method for determining the hydrogen diffusion path, so as to solve the current problems of low hydrogen sampling accuracy and inability to continuously monitor.

[0004] Based on the above objectives, the present application provides a device for measuring hydrogen concentration in soil, comprising: The first and second air stones are buried in the soil; an air inlet pipe and an air outlet pipe, wherein one end of the air inlet pipe is connected to a first air stone, and one end of the air outlet pipe is connected to a second air stone; A return pump, wherein the other end of the air inlet pipe is connected to the air inlet of the return pump, and the other end of the air outlet pipe is connected to the air outlet of the return pump to form a circulating hydrogen loop; The measuring component includes: a sealed bag and a hydrogen sensor, wherein the sealed bag is connected to the air inlet pipe, and the hydrogen sensor is placed in the sealed bag to measure the hydrogen concentration in the circulating hydrogen loop.

[0005] Based on the same inventive concept, the present disclosure also provides a method for determining a hydrogen diffusion path, comprising: Constructing a measurement area on the soil, determining a center point on the soil of the measurement area, drilling a central air hole at the center point, and obtaining a measured value of the hydrogen concentration in the soil at the center point using the above-mentioned measuring device; Determining edge points on the soil of the measurement area, and drilling edge air holes at the edge points; Injecting carbon dioxide of a preset concentration into the central pore, allowing part of the carbon dioxide to diffuse into the edge pores, and measuring the carbon dioxide concentration in the edge pores; determining a diffusion coefficient of carbon dioxide in the soil of the measurement area based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge pores; Determining a theoretical value of the hydrogen concentration in the soil at the center point based on the diffusion coefficient of the carbon dioxide in the soil of the measurement area, the measured value of the hydrogen concentration in the soil at the center point, the reference diffusion coefficient of carbon dioxide, and the hydrogen to carbon dioxide diffusion rate ratio; Based on the theoretical values ​​of hydrogen concentration in the soil at the center points within multiple measurement areas, the hydrogen diffusion path and hydrogen emission points are determined.

[0006] Optionally, constructing a measurement area on the soil, determining a center point on the soil in the measurement area, drilling a central air hole at the center point, and obtaining a measured value of hydrogen concentration in the soil at the center point by the above-mentioned measuring device includes: placing the hydrogen sensor in the sealing bag, and connecting the sealing bag to the air inlet pipe; Connect one end of the air inlet pipe to the first air stone, and the other end to the air inlet of the return pump; connect one end of the air outlet pipe to the second air stone, and the other end to the air outlet of the return pump; placing the first air stone and the second air stone in the central air hole and covering them with soil; Turning on the return pump, the first gas stone, the air inlet pipe, the return pump, the air outlet pipe and the second gas stone form a circulating hydrogen loop; After the circulating hydrogen loop runs for a preset time, the hydrogen sensor is turned on to measure the hydrogen concentration in the sealed bag, and the measured hydrogen concentration is used as the actual measured value of the hydrogen concentration in the soil at the center point.

[0007] Optionally, determining the diffusion coefficient of carbon dioxide in the soil of the measurement area based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge pores includes: determining a concentration gradient of carbon dioxide in the soil of the measurement area based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge pores; Based on the preset concentration of carbon dioxide, measuring the mass-time change rate of carbon dioxide in the central pore; determining a diffusion flux of carbon dioxide in the soil at the central point based on the mass-time rate of change of carbon dioxide in the central pore and the cross-sectional area of ​​the first air stone; The diffusion coefficient of carbon dioxide in the soil of the measurement area is determined based on the concentration gradient of carbon dioxide in the soil of the measurement area and the diffusion flux of carbon dioxide in the soil at the central point.

[0008] Optionally, the concentration gradient of carbon dioxide in the soil of the measurement area is determined based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge pores, wherein the concentration gradient of carbon dioxide in the soil of the measurement area is expressed by the formula: ΔC / ΔX=(C0-C t ) / ΔX; Wherein, ΔC / ΔX is the concentration gradient of carbon dioxide in the soil of the measurement area, and C0 is the preset concentration of carbon dioxide; C t is the carbon dioxide concentration in the edge pores at time t, and ΔX is the distance between the central pore and the edge pore.

[0009] Optionally, the diffusion flux of carbon dioxide in the soil at the center point is determined based on the mass-time change rate of carbon dioxide in the central pore and the cross-sectional area of ​​the first air stone, wherein the diffusion flux of carbon dioxide in the soil at the center point is expressed using the formula: q d =(δm / δt) / A; Among them, q d is the diffusion flux of carbon dioxide in the soil at the central point; δm / δt is the mass-time change rate of carbon dioxide in the central pore; A is the cross-sectional area of ​​the first air stone.

[0010] Optionally, the diffusion coefficient of carbon dioxide in the soil of the measurement area is determined based on the concentration gradient of carbon dioxide in the soil of the measurement area and the diffusion flux of carbon dioxide in the soil at the center point, wherein the diffusion coefficient of carbon dioxide in the soil of the measurement area is expressed by the formula: D=-q d / (ΔC / ΔX); Among them, q d is the diffusion flux of carbon dioxide in the soil at the center point; ΔC / ΔX is the concentration gradient of carbon dioxide in the soil in the measurement area; and D is the diffusion coefficient of carbon dioxide in the soil in the measurement area.

[0011] Optionally, the theoretical value of the hydrogen concentration in the soil at the center point is determined based on the diffusion coefficient of the carbon dioxide in the soil of the measurement area, the measured value of the hydrogen concentration in the soil at the center point, the reference diffusion coefficient of carbon dioxide, and the diffusion rate ratio of hydrogen to carbon dioxide, wherein the theoretical value of the hydrogen concentration in the soil at the center point is expressed by the formula: C corr =kC meas D / D ref ; Among them, C corr is the theoretical value of the hydrogen concentration in the soil at the center point; D is the diffusion coefficient of the carbon dioxide in the soil in the measurement area; C meas is the measured value of the hydrogen concentration in the soil at the central point; k is the diffusion rate ratio of hydrogen to carbon dioxide; Dref is the reference diffusion coefficient of carbon dioxide, which uses the free air diffusion coefficient and is 0.16 cm2 / s.

[0012] Optionally, after placing the first air stone and the second air stone in the central air hole and burying them with soil, the method further includes: draining the gas in the sealing bag through the reserved hole of the sealing bag, and then blocking the reserved hole of the sealing bag.

[0013] Optionally, placing the first air stone and the second air stone in the central air hole includes: arranging the first air stone and the second air stone axially along the central air hole, with a gap left between the first air stone and the second air stone.

[0014] As can be seen from the above, the first air stone, air inlet pipe, return pump, air outlet pipe, and second air stone in the measuring device provided by this application form a circulating hydrogen loop. The sealed bag is directly connected to the air inlet pipe, and the hydrogen sensor is placed inside the sealed bag to directly detect the hydrogen concentration, effectively preventing the entry of outside air. Compared with the traditional semi-open sampling method, this solves the problem of hydrogen concentration dilution caused by external air interference, making the measurement results closer to the actual concentration of hydrogen in the soil. In addition, because the return pump can continuously and stably drive hydrogen to circulate in the loop, the measuring component can monitor the hydrogen concentration in the circulating loop in real time. Without the frequent on-site sampling operations required by traditional one-time sampling methods, long-term and continuous monitoring of the hydrogen concentration at a specific underground point can be achieved, providing a reliable data source for studying the temporal variation of hydrogen concentration. In addition, due to the circulation effect of the circulating hydrogen loop, the hydrogen in the soil can be fully mixed and balanced in the soil. The hydrogen sensor in the sealed bag performs measurements after the hydrogen reaches a stable state, avoiding fluctuations in the measurement values ​​and greatly improving the representativeness and repeatability of the data, laying a solid foundation for subsequent analysis of the distribution, migration characteristics and occurrence mechanism of hydrogen.

[0015] In addition, the method for determining the hydrogen diffusion path provided in the present application calibrates the measured value of hydrogen into a theoretical value through parameters such as the diffusion coefficient of carbon dioxide in the soil in the measurement area and the measured value of the hydrogen concentration in the soil at the center point, thereby eliminating the influence of the inherent characteristics of different measurement areas such as soil texture and permeability on the hydrogen concentration measurement, so that the hydrogen concentrations in different measurement areas have the conditions for direct comparison, thereby providing a reliable basis for accurately judging the diffusion path and emission point of hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in this application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are merely embodiments of this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 This is a schematic diagram showing the structure of a measuring device according to an embodiment of the present application; Figure 2 This is a flow chart showing a method for determining a hydrogen diffusion path according to an embodiment of the present application.

[0018] Figure numerals: 01, central air hole; 1, first air stone; 2, second air stone; 3, air inlet pipe; 4, air outlet pipe; 5, return pump; 6, measuring component; 61, sealing bag; 611, reserved hole; 62, hydrogen sensor. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of this application more clear, this application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0020] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should have the usual meanings understood by people with ordinary skills in the field to which this application belongs. The "first", "second" and similar words used in the embodiments of the present application do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0021] As mentioned above, against the backdrop of global energy transformation, the development and utilization of clean energy has become an inevitable trend. Natural hydrogen, as a highly promising clean energy source, is gradually entering the public eye. Its renewable nature and the fact that its combustion product is solely water make it a key player in the future energy landscape, making it a powerful weapon for alleviating energy crises and environmental pressures. Natural hydrogen is widely distributed in soil layers and loose sediments in the shallow crust, as well as in sedimentary basins, fault zones, volcanic activity zones, and associated environments in oil and gas basins deep underground. By measuring hydrogen concentration in the soil, we can determine the hydrogen diffusion path and, subsequently, the source (or emission point) of hydrogen, providing critical basic data support for the subsequent precise exploration of natural hydrogen resources, the assessment of resource potential, and the formulation of rational development plans.

[0022] However, the currently widely used hydrogen soil measurement technology has exposed many difficult problems in actual operation and data acquisition. First, the sampling method has obvious flaws. The commonly used sampling method has many open links, which easily mixes with external air, diluting the original hydrogen concentration in the soil and making it difficult to accurately reflect the actual soil hydrogen content. This has caused deviations in subsequent data-based analysis, research, and resource assessment work.

[0023] Secondly, most existing measurement methods can only collect hydrogen samples in the soil at a specific moment, and are powerless to measure the dynamic changes in hydrogen concentration over time at the same location underground. However, in reality, the generation, migration, and storage of underground hydrogen are affected by a variety of complex geological factors, such as changes in stratum structure, groundwater flow, and differences in rock mineral composition. These factors are constantly changing, resulting in the hydrogen concentration at a certain point underground not being constant, but fluctuating over time. The lack of long-term monitoring methods means that it is impossible to fully grasp the temporal evolution of hydrogen concentration, missing a lot of key information, and seriously restricting the in-depth understanding of the occurrence state and migration process of underground hydrogen.

[0024] Furthermore, the distribution of hydrogen in the soil shows significant heterogeneity in time and space. Spatially, the pore structure, permeability, and mineral composition of soils in different regions vary. Since the natural source of hydrogen is underground, some places have large pores and good connectivity, which are conducive to the migration and escape of hydrogen, resulting in lower concentrations. In other areas, hydrogen is difficult to escape due to dense soil and strong mineral adsorption, resulting in higher concentrations. From a temporal perspective, changes in soil temperature and humidity, as well as changes in microbial activity at different times of the day and in different seasons, will affect the generation and escape of hydrogen. However, current measurement technology directly compares measurement values ​​without considering corrections for the soil's ability to retain hydrogen. The reliability of research conclusions and resource evaluation results based on this is difficult to guarantee, which poses hidden dangers for subsequent resource exploration and development.

[0025] In order to solve the above problems, the present application provides a device for measuring hydrogen concentration in soil and a method for determining the hydrogen diffusion path.

[0026] The following is combined with Figure 1-2 The embodiments of the present application will be described in detail.

[0027] like Figure 1 As shown, a device for measuring hydrogen concentration in soil includes: The first air stone 1 and the second air stone 2 are buried in the soil; An air inlet pipe 3 and an air outlet pipe 4, one end of the air inlet pipe 3 is connected to the first air stone 1, and one end of the air outlet pipe 4 is connected to the second air stone 2; A return pump 5, the other end of the inlet pipe 3 is connected to the air inlet of the return pump 5, and the other end of the outlet pipe 4 is connected to the air outlet of the return pump 5, so as to form a circulating hydrogen loop; The measuring component 6 includes a sealing bag 61 and a hydrogen sensor 62 . The sealing bag 61 is connected to the air inlet pipe 3 . The hydrogen sensor 62 is placed in the sealing bag 61 to measure the hydrogen concentration in the circulating hydrogen loop.

[0028] Specifically, the first air stone 1 and the second air stone 2 are porous stones with high air permeability, which are convenient for collecting hydrogen from the soil and transporting hydrogen to the soil. A central air hole 01 is drilled in the measurement area of ​​the soil, and the first air stone 1 and the second air stone 2 are placed in the central air hole 01. The central air hole 01 is then covered with soil, thereby burying the first air stone 1 and the second air stone 2 in the soil. The shape of the first air stone 1 and the second air stone 2 can be cylindrical and vertically placed in the central air hole 01. The first air stone 1 and the second air stone 2 are both connected to an air nozzle. The first air stone 1 and the second air stone 2 respectively insert the air nozzle into the corresponding air pipe to complete the connection between the air stone and the air pipe. The connection is convenient and efficient. Both the inlet pipe 3 and the outlet pipe 4 are made of a corrosion-resistant, elastic plastic material, such as chlorinated polyvinyl chloride (CPVC) or high-density polyethylene (HDPE). These materials offer excellent chemical resistance and are resistant to various acids and bases present in the soil. They also possess a certain degree of elasticity, facilitating a tight connection with the gas nozzle, thereby enhancing the sealing of the measuring device. Furthermore, to further enhance the sealing of the measuring device, sealing tape may be wrapped around the connection between the gas stone and the pipe. In the measuring assembly 6, a sealing bag 61 is directly connected to the center of the inlet pipe 3 via the inlet and outlet ports. The sealing bag 61 can be made of age-resistant, transparent polyethylene, facilitating easy observation of the gas content within the bag and the status of the hydrogen sensor 62. The hydrogen sensor 62 is a high-precision electrochemical sensor that directly displays hydrogen concentration and can also be connected to an external terminal (such as a computer or data logger) via a data transmission line for automatic data storage and remote viewing. The reserved hole 611 of the sealing bag 61 can be a rubber valve port with a diameter of 5 mm, and can be easily opened and closed with a rubber cap with a diameter of 4 mm, so as to discharge or collect the gas in the sealing bag 61 when necessary.

[0029] In this embodiment, the first air stone 1, air inlet pipe 3, return pump 5, air outlet pipe 4, and second air stone 2 in the measuring device form a circulating hydrogen loop. A sealed bag 61 is directly connected to the air inlet pipe 3, and a hydrogen sensor 62 is located within the sealed bag 61 to directly detect the hydrogen concentration. This effectively prevents the ingress of outside air. Compared to traditional semi-open sampling methods, this solves the problem of hydrogen concentration dilution caused by interference from outside air, making the measurement results closer to the actual concentration of hydrogen in the soil. Furthermore, because the return pump 5 can continuously and stably drive hydrogen to circulate within the loop, the measuring component 6 can monitor the hydrogen concentration in the circulating hydrogen loop in real time. This eliminates the need for frequent on-site sampling operations required by traditional one-time sampling methods, enabling long-term, continuous monitoring of hydrogen concentration at a specific underground point, providing a reliable data source for studying the temporal variation of hydrogen concentration. In addition, due to the circulation effect of the circulating hydrogen loop, the hydrogen in the soil can be fully mixed and balanced in the soil. The hydrogen sensor 62 in the sealed bag 61 performs measurements after the hydrogen reaches a stable state, avoiding fluctuations in the measurement values ​​and greatly improving the representativeness and repeatability of the data, laying a solid foundation for subsequent analysis of the distribution, migration characteristics and occurrence mechanism of hydrogen.

[0030] Based on the same inventive concept, corresponding to the above embodiments, Figure 2 As shown, the present application also provides a method for determining a hydrogen diffusion path, comprising the following steps: S100: constructing a measurement area on the soil, determining a center point on the soil of the measurement area, drilling a center air hole 01 at the center point, and obtaining a measured value of hydrogen concentration in the soil at the center point using the above-mentioned measuring device; In this step, the measurement area is a small area, constructed to determine the hydrogen concentration in the soil at a specific point. This measurement area can be a circular area with a diameter of approximately 2 meters, with the center point being the origin of the circular area. The depth of the central air hole 01 at the center point is 0.8 to 1.0 meters to ensure that hydrogen is collected. Using this measurement device, the hydrogen concentration within the central air hole 01 is collected, improving the accuracy of the hydrogen concentration in the soil at the center point.

[0031] S200: determining edge points on the soil of the measurement area, and drilling edge pores at the edge points; In this step, the distance between the edge point and the center point can be 1 meter, the edge gas size is consistent with the size of the center pore 01, and the edge points and edge pores are set to multiple. For example, the edge pores are set to four, which are evenly distributed around the center point to ensure that hydrogen diffusion signals in different directions can be captured.

[0032] S300: injecting carbon dioxide of a preset concentration into the central pore 01, partially diffusing the carbon dioxide to the edge pores, and measuring the carbon dioxide concentration in the edge pores; S400: Determining a diffusion coefficient of carbon dioxide in the soil of the measurement area based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge pores; In steps S300 and S400, carbon dioxide is selected as a tracer. A preset concentration and volume of carbon dioxide is injected into the central pore 01 at a controlled injection rate of 0.1-0.3 liters / minute to avoid disturbing the soil structure. Before injection, the central pore 01 is covered with surrounding soil, leaving only the injection hole. This ensures that the injected carbon dioxide can diffuse into the soil to the greatest extent possible. This prevents leakage that could result in insufficient carbon dioxide at the preset concentration, which could affect the accuracy of subsequent measurements of carbon dioxide concentration in the peripheral pores. After carbon dioxide injection is completed, the injection pump catheter is removed and the injection hole is immediately completely blocked with soil or a rubber stopper to ensure that all injected carbon dioxide diffuses into the soil and prevent outside air from entering the central pore 01 and interfering with the diffusion process. Furthermore, it is important to note that before determining the hydrogen diffusion path, the central measuring device must be removed to avoid interfering with the determination of the hydrogen diffusion path. After measuring the carbon dioxide concentration, the remaining injected carbon dioxide must be removed to avoid interfering with subsequent measurements of the hydrogen concentration after equilibrium in the soil.

[0033] After injection is complete, measure the concentration of each edge pore every hour using a portable carbon dioxide analyzer (accuracy ±1ppm) or using the aforementioned measuring device (with the carbon dioxide sensor replacing the hydrogen sensor) and record the peak concentration (e.g., a peak value of 1200ppm at a northeast edge point and 500ppm in the southwest). Based on the preset carbon dioxide concentration and the carbon dioxide concentration (peak concentration) in each edge pore, determine the diffusion coefficient of carbon dioxide in the soil in all directions within the measurement area. The diffusion coefficient of carbon dioxide in the soil of the measurement area can be selected based on the research objectives and soil characteristics: for areas with uniform soil texture and insignificant anisotropy (e.g., homogeneous sand layers), the average value for each direction can be used. For scenarios where a dominant diffusion direction (e.g., along the strike of a fault) needs to be analyzed, the diffusion coefficient in that direction can be selected as a representative value to highlight the diffusion characteristics of the key direction.

[0034] S500: Determining a theoretical value of the hydrogen concentration in the soil at the center point based on the diffusion coefficient of carbon dioxide in the soil in the measurement area, the measured value of the hydrogen concentration in the soil at the center point, a reference diffusion coefficient of carbon dioxide, and a hydrogen to carbon dioxide diffusion rate ratio; In this step, the theoretical value is not directly measured, but rather a correction to the measured value, providing a more accurate reflection of the true diffusion state of hydrogen in the soil. Specifically, hydrogen diffuses in soil over time and space, with diffusion rates in different directions varying due to differences in soil properties. Directly comparing measured values ​​across regions cannot accurately determine the true distribution and diffusion trend of hydrogen. The theoretical value, derived from a unified calculation model, eliminates the impact of inherent differences in soil texture, permeability, and other properties on hydrogen concentration measurements across different measurement areas. This effectively 'calibrates' the hydrogen concentration data for each region to the same soil environmental benchmark, enabling direct comparison of hydrogen concentrations across different measurement areas and providing a reliable basis for accurately determining overall diffusion paths and emission points.

[0035] S600: Determine a hydrogen diffusion path and a hydrogen emission point based on theoretical values ​​of hydrogen concentration in the soil at center points within multiple measurement areas.

[0036] In step S600, for example, 10 measurement areas are arranged in different directions in a 50m x 50m grid within the study area. Steps S100-S500 are repeated for each measurement area to obtain the theoretical hydrogen concentration value for each measurement area. The diffusion path of hydrogen is determined based on the theoretical hydrogen concentration value, and ultimately the hydrogen emission point is determined. For example, if a measurement area is located in the southeast, its theoretical hydrogen concentration value is generally higher than that of a measurement area in the northwest, indicating that the hydrogen diffusion path is from southeast to northwest, and the hydrogen emission point is located in the southeast where the hydrogen concentration is the highest.

[0037] In this embodiment, this determination method calibrates the measured hydrogen value to a theoretical value using parameters such as the carbon dioxide diffusion coefficient in the soil of the measurement area and the measured hydrogen concentration in the soil at the central point. This eliminates the influence of inherent differences in soil texture, permeability, and other properties on hydrogen concentration measurements across different measurement areas, enabling direct comparison of hydrogen concentrations in different measurement areas and providing a reliable basis for accurately determining the overall diffusion path and emission point. Furthermore, using carbon dioxide as a tracer provides a highly accurate indicator of hydrogen diffusion performance. Specifically, both carbon dioxide and hydrogen are small molecules, and their diffusion behavior in soil is similarly influenced by factors such as pore structure and humidity. Furthermore, carbon dioxide is chemically stable and non-biodegradable, preventing interference from tracer loss on diffusion coefficient calculations.

[0038] In some embodiments, in step S100, constructing a measurement area on the soil, determining a center point on the soil of the measurement area, drilling a central air hole 01 at the center point, and obtaining a measured value of hydrogen concentration in the soil at the center point include: S101: placing the hydrogen sensor 62 in the sealing bag 61, and connecting the sealing bag 61 to the intake pipe 3; In this step, the reserved hole 611 provided on the sealing bag 61 is completely closed during sampling, and exhaust is discharged through the reserved hole when exhaust is required.

[0039] S102: Connect one end of the air inlet pipe 3 to the first air stone 1 and the other end to the air inlet of the return pump 5; connect one end of the air outlet pipe 4 to the second air stone 2 and the other end to the air outlet of the return pump 5; S103: placing the first air stone 1 and the second air stone 2 in the central air hole 01 and covering them with soil; In this step, the first air stone 1 and the second air stone 2 are arranged axially along the central air hole, with a gap between them. For example, the central air hole 01 is a vertically downward hole with a depth of 0.8 to 1.0 m. The first air stone 1 is positioned above the second air stone 2, and the second air stone 2 is positioned at the bottom of the central air hole 01. A gap of 5 cm is left between the first and second air stones 1 and 2 to prevent interference and affect sampling.

[0040] S104 : The gas in the sealing bag 61 is drained through the reserved hole 611 of the sealing bag 61 , and then the reserved hole of the sealing bag 61 is blocked.

[0041] In this step, the reserved hole 611 in the sealing bag 61 can, for example, be a 5mm diameter rubber valve port. A 500mL syringe is connected to the bag. The air in the bag is degassed by slowly pushing and pulling the syringe piston (at a rate of 20mL / s). When the syringe piston can no longer be pulled (the vacuum level in the bag is ≥ -0.09MPa), the reserved hole is immediately sealed with a dedicated rubber stopper. The stopper fits snugly against the hole wall to prevent air from entering. During the degassing process, the sealing bag 61 should be inspected for damage (e.g., bulging or denting). If so, the bag should be replaced and the process repeated. This step is intended to completely remove air from the circulation loop and the sealing bag 61 to prevent it from affecting the hydrogen concentration.

[0042] S105: Turn on the return pump 5, and the first gas stone 1, the air inlet pipe 3, the return pump 5, the air outlet pipe 4 and the second gas stone 2 form a circulating hydrogen loop; S106: After the circulating hydrogen loop runs for a preset time, the hydrogen sensor 62 is turned on to measure the hydrogen concentration in the sealed bag 61, and the measured hydrogen concentration is used as the actual value of the hydrogen concentration in the soil at the center point.

[0043] In this step, the preset duration can be at least one day to ensure that the hydrogen in the soil and the circulating hydrogen loop reaches equilibrium. The hydrogen sensor 62 automatically activates after the circulating loop has run for the preset duration. For example, it records the concentration every 60 seconds for 5 minutes, taking the average value as the measured value at the center point. If the data fluctuation within 5 minutes is ≤5%, the measurement is considered valid. If the fluctuation is excessive (>5%), the cycle is extended by 10 minutes and the measurement is repeated.

[0044] In this embodiment, the hydrogen concentration measured by the above-mentioned measurement method has high accuracy and can achieve long-term continuous detection. There is no need to perform frequent on-site sampling operations like the traditional one-time sampling method. The sampling is convenient and efficient.

[0045] In some embodiments, in step S400, determining the diffusion coefficient of carbon dioxide in the soil of the measurement area based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge pores includes: S401: Determining a concentration gradient of carbon dioxide in the soil of the measurement area based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge pores; In this step, the concentration gradient of carbon dioxide in the soil of the measurement area is expressed by the formula: ΔC / ΔX=(C0-C t ) / ΔX; Wherein, ΔC / ΔX is the concentration gradient of carbon dioxide in the soil of the measurement area, g / cm 3 / cm2, C0 is the preset concentration of carbon dioxide, g / cm2 3 ; C t is the carbon dioxide concentration in the edge pores at time t, g / cm 3 ; ΔX is the distance between the central pore 01 and the edge pore, cm. In this application, ΔX is 100 cm.

[0046] S402: Based on the preset concentration of carbon dioxide, measuring the mass-time change rate of carbon dioxide in the central pore 01; For example, a valved sampling tube (connected to a portable gas mass flowmeter) is attached to the top of the sealed central air hole 01. A gas sample (volume 50 mL) is collected every 30 minutes. The mass of carbon dioxide in the sample is measured using a gas chromatograph (accuracy ±0.01 mg). Six consecutive measurements are performed (covering the change before and after the peak concentration). The measured mass data are then fitted to a curve corresponding to the corresponding time (with the injection moment as the zero point). The slope of the curve at the peak moment is calculated using the least squares method, which is the mass-time rate of change (δm / δt).

[0047] S403: Determine the diffusion flux of carbon dioxide in the soil at the center point based on the carbon dioxide mass-time change rate in the central pore 01 and the cross-sectional area of ​​the first air stone 1; In this step, the diffusion flux of carbon dioxide in the soil at the central point is expressed using the formula: q d =(δm / δt) / A; Among them, q d is the diffusion flux of carbon dioxide in the soil at the central point, g / s / cm 2 ; δm / δt is the mass-time rate of change of carbon dioxide in the central pore 01, g / s; A is the cross-sectional area in the diffusion direction, that is, the cross-sectional area of ​​the first air stone 1, cm 2 .

[0048] In addition, if the carbon dioxide concentration in the soil at the center point c t As time goes by, it indicates that the gas accumulation rate increases. By fitting c t A curve of change over time (e.g. linear or exponential fit) with the slope dc calculated t / dt. Combined with the soil porosity θ, the diffusion flux can be approximated as: q d ≈θLdc t / dt; where L is the characteristic length of the diffusion path (here ΔX = 100 cm).

[0049] S404: Determine a diffusion coefficient of carbon dioxide in the soil of the measurement area based on the concentration gradient of carbon dioxide in the soil of the measurement area and the diffusion flux of carbon dioxide in the soil at the center point.

[0050] In this step, the diffusion coefficient of carbon dioxide in the soil of the measurement area is expressed by the formula: D=-q d / (ΔC / ΔX); Among them, q d is the diffusion flux of carbon dioxide in the soil at the central point, g / s / cm 2 ; ΔC / ΔX is the concentration gradient of carbon dioxide in the soil of the measurement area, g / cm 3 / cm; D is the diffusion coefficient of carbon dioxide in the soil of the measurement area, cm 2 / s.

[0051] In this embodiment, the abstract diffusion process is broken down into measurable physical quantities through the step-by-step calculation of "concentration gradient - diffusion flux - diffusion coefficient": the concentration gradient intuitively reflects the driving force of gas diffusion, the diffusion flux quantifies the gas migration rate per unit area, and finally the diffusion coefficient is derived through the linear relationship between the two. Each step is based on the microscopic mechanism of gas diffusion, avoiding errors caused by ignoring intermediate variables.

[0052] In some embodiments, the theoretical value of the hydrogen concentration in the soil at the center point is determined based on the diffusion coefficient of carbon dioxide in the soil of the measurement area, the measured value of the hydrogen concentration in the soil at the center point, the reference diffusion coefficient of carbon dioxide, and the diffusion rate ratio of hydrogen to carbon dioxide, wherein the theoretical value of the hydrogen concentration in the soil at the center point is expressed by the formula: C corr =kC meas D / D ref ; Among them, C corr is the theoretical value of the hydrogen concentration in the soil at the central point, g / cm 3 ; D is the diffusion coefficient of carbon dioxide in the soil of the measurement area, cm 2 / s;C meas is the measured value of the hydrogen concentration in the soil at the central point, g / cm³; k is the diffusion rate ratio of hydrogen to carbon dioxide; D ref is the reference diffusion coefficient of carbon dioxide, cm 2 / s, using the free air diffusion coefficient of 0.16cm 2 / s.

[0053] Specifically, when soil gas diffuses, the gas source is usually from the atmosphere. The measured concentration is converted into the corrected concentration using the following model-based concentration correction formula: C corr =C meas D ref / D; In natural hydrogen exploration, the hydrogen source is located underground and escapes into the atmosphere. The small diffusion coefficient is not easy to escape and is conducive to preservation. Therefore, since the migration is in the opposite direction, D ref Exchange positions with D to get C corr =kC meas D / D ref .

[0054] In this embodiment, the theoretical value of hydrogen concentration C corr By introducing D / D refThe correction term is used to uniformly correct measured values ​​based on the free air diffusion coefficient, facilitating comparison. For example, in clay soils, due to poor air permeability, hydrogen diffusion is hindered, resulting in higher measured values. The resulting theoretical value after correction better reflects the influence of underground hydrogen sources and the true state of hydrogen, thus resolving the problem of deviations in measured values ​​caused by local soil conditions.

[0055] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present application is limited to these examples. In line with the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0056] In addition, to simplify the description and discussion, and to avoid obscuring the embodiments of the present application, known power / ground connections to the integrated circuit chips and other components may or may not be shown in the provided figures. In addition, devices may be shown in block diagram form to avoid obscuring the embodiments of the present application, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform on which the embodiments of the present application will be implemented (i.e., these details should be fully within the scope of understanding of those skilled in the art). Where specific details (e.g., circuits) are set forth to describe exemplary embodiments of the present application, it will be apparent to those skilled in the art that the embodiments of the present application can be implemented without these specific details or with variations in these specific details. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0057] Although the present invention has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations of these embodiments will be apparent to those skilled in the art based on the foregoing description. For example, other memory architectures may use the embodiments discussed.

[0058] The embodiments of the present application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the present application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the scope of protection of the present application.

Claims

1. A device for measuring hydrogen concentration in soil, characterized in that: include: A first air stone (1) and a second air stone (2) are buried in the soil; an air inlet pipe (3) and an air outlet pipe (4), one end of the air inlet pipe (3) being connected to the first air stone (1), and one end of the air outlet pipe (4) being connected to the second air stone (2); A return pump (5), the other end of the air inlet pipe (3) is connected to the air inlet of the return pump (5), and the other end of the air outlet pipe (4) is connected to the air outlet of the return pump (5), so as to form a circulating hydrogen loop; The measuring assembly (6) comprises: a sealing bag (61) and a hydrogen sensor (62), wherein the sealing bag (61) is connected to the air inlet pipe (3), and the hydrogen sensor (62) is placed in the sealing bag (61) to measure the hydrogen concentration in the circulating hydrogen loop.

2. A method for determining a hydrogen diffusion path, characterized in that: include: Constructing a measurement area on the soil, determining a center point on the soil of the measurement area, drilling a center pore (01) at the center point, and obtaining a measured value of hydrogen concentration in the soil at the center point using the measurement device according to claim 1; Determining edge points on the soil of the measurement area, and drilling edge air holes at the edge points; Injecting carbon dioxide of a preset concentration into the central pore (01), allowing part of the carbon dioxide to diffuse into the edge pores, and measuring the carbon dioxide concentration in the edge pores; determining a diffusion coefficient of carbon dioxide in the soil of the measurement area based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge pores; Determining a theoretical value of the hydrogen concentration in the soil at the center point based on the diffusion coefficient of the carbon dioxide in the soil of the measurement area, the measured value of the hydrogen concentration in the soil at the center point, the reference diffusion coefficient of carbon dioxide, and the hydrogen to carbon dioxide diffusion rate ratio; Based on theoretical values ​​of hydrogen concentration in the soil at the central point within a plurality of measurement areas, a hydrogen diffusion path and a hydrogen emission point are determined.

3. The method for determining a hydrogen diffusion path according to claim 2, wherein: The method comprises constructing a measurement area on the soil, determining a center point on the soil of the measurement area, drilling a center pore (01) at the center point, and obtaining a measured value of hydrogen concentration in the soil at the center point by using the measurement device according to claim 1, comprising: placing the hydrogen sensor (62) in the sealing bag (61), and connecting the sealing bag (61) to the air inlet pipe (3); One end of the air inlet pipe (3) is connected to the first air stone (1), and the other end is connected to the air inlet of the return pump (5); one end of the air outlet pipe (4) is connected to the second air stone (2), and the other end is connected to the air outlet of the return pump (5); placing the first air stone (1) and the second air stone (2) in the central air hole (01) and covering them with soil; The return pump (5) is turned on, and the first gas stone (1), the gas inlet pipe (3), the return pump (5), the gas outlet pipe (4) and the second gas stone (2) form a circulating hydrogen loop; After the circulating hydrogen loop runs for a preset time, the hydrogen sensor (62) is turned on to measure the hydrogen concentration in the sealed bag (61), and the measured hydrogen concentration is used as the actual value of the hydrogen concentration in the soil at the center point.

4. The method for determining a hydrogen diffusion path according to claim 2, wherein: The step of determining the diffusion coefficient of carbon dioxide in the soil of the measurement area based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge pores includes: determining a concentration gradient of carbon dioxide in the soil of the measurement area based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge pores; Based on the preset concentration of carbon dioxide, measuring the mass-time change rate of carbon dioxide in the central pore (01); Determining the diffusion flux of carbon dioxide in the soil at the central point based on the mass-time change rate of carbon dioxide in the central pore (01) and the cross-sectional area of ​​the first air stone (1); The diffusion coefficient of carbon dioxide in the soil of the measurement area is determined based on the concentration gradient of carbon dioxide in the soil of the measurement area and the diffusion flux of carbon dioxide in the soil at the central point.

5. The method for determining a hydrogen diffusion path according to claim 4, wherein: The concentration gradient of carbon dioxide in the soil of the measurement area is determined based on the preset concentration of carbon dioxide and the concentration of carbon dioxide in the edge pores, wherein the concentration gradient of carbon dioxide in the soil of the measurement area is expressed by the formula: ΔC / ΔX=(C0-C t ) / ΔX; Wherein, ΔC / ΔX is the concentration gradient of carbon dioxide in the soil of the measurement area, and C0 is the preset concentration of carbon dioxide; C t is the carbon dioxide concentration in the edge pores at time t, and ΔX is the distance between the central pore (01) and the edge pores.

6. The method for determining a hydrogen diffusion path according to claim 4, wherein: The diffusion flux of carbon dioxide in the soil at the central point is determined based on the mass-time change rate of carbon dioxide in the central pore (01) and the cross-sectional area of ​​the first air stone (1), wherein the diffusion flux of carbon dioxide in the soil at the central point is expressed by the formula: q d =(δm / δt) / A; Among them, q d is the diffusion flux of carbon dioxide in the soil at the central point; δm / δt is the mass-time change rate of carbon dioxide in the central pore (01); and A is the cross-sectional area of ​​the first air stone (1).

7. The method for determining a hydrogen diffusion path according to claim 4, wherein: The diffusion coefficient of carbon dioxide in the soil of the measurement area is determined based on the concentration gradient of carbon dioxide in the soil of the measurement area and the diffusion flux of carbon dioxide in the soil at the center point, wherein the diffusion coefficient of carbon dioxide in the soil of the measurement area is expressed by the formula: D=-q d / (ΔC / ΔX); Among them, q d is the diffusion flux of carbon dioxide in the soil at the center point; ΔC / ΔX is the concentration gradient of carbon dioxide in the soil in the measurement area; and D is the diffusion coefficient of carbon dioxide in the soil in the measurement area.

8. The method for determining a hydrogen diffusion path according to claim 2, wherein: The theoretical value of the hydrogen concentration in the soil at the center point is determined based on the diffusion coefficient of carbon dioxide in the soil of the measurement area, the measured value of the hydrogen concentration in the soil at the center point, the reference diffusion coefficient of carbon dioxide, and the diffusion rate ratio of hydrogen to carbon dioxide. The theoretical value of the hydrogen concentration in the soil at the center point is expressed by the formula: C corr =kC meas D / D ref ; Among them, C corr is the theoretical value of the hydrogen concentration in the soil at the center point; D is the diffusion coefficient of the carbon dioxide in the soil in the measurement area; C meas is the measured value of the hydrogen concentration in the soil at the central point; k is the diffusion rate ratio of hydrogen to carbon dioxide; D ref is the reference diffusion coefficient of carbon dioxide, using the free air diffusion coefficient, which is 0.16 cm 2 / s.

9. The method for determining a hydrogen diffusion path according to claim 3, wherein: After placing the first air stone (1) and the second air stone (2) in the central air hole (01) and burying them with soil, the method further includes: draining the air in the sealing bag (61) through the reserved hole (611) of the sealing bag (61), and then blocking the reserved hole (611) of the sealing bag (61).

10. The method for determining a hydrogen diffusion path according to claim 3, wherein: The placing of the first air stone (1) and the second air stone (2) in the central air hole (01) comprises: arranging the first air stone (1) and the second air stone (2) axially along the central air hole (01), with a gap left between the first air stone (1) and the second air stone (2).

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