Underway gas production system for soil gas collection

Abstract

The invention relates to the technical field of gas sampling, in particular to an underway gas sampling system for soil gas collection, comprising: a gas collection container comprising any one or more of a first container, a second container and a third container, the first container comprising a steel cylinder for storing a gas sample with a first pressure, the second container comprising a gas sample with a second pressure, and the third container comprising a gas sample with a second pressure; the first container comprises a first pressure and a second pressure, the second container comprises a flexible air bag, the flexible air bag is used for storing a gas sample with a second pressure, the second pressure is smaller than the first pressure, the third container comprises an air exhaust pipeline, and the air exhaust pipeline and a soil layer to be sampled form a soil sample collection container. According to the underway gas collection system for soil gas collection, sampling can be carried out in three gas collection modes of the gas cylinder, the flexible gas bag and the gas extraction pipeline, the underway gas collection system can adapt to different sampling points, gas samples collected at the sampling points are detected on site at the same time according to the same standard, and gas sample components of the current sampling point can be reduced more effectively.

Description

Technical Field

[0001] The invention relates to the technical field of gas sampling, and in particular to a cruise gas sampling system for soil gas collection. Background Art

[0002] Since hydrogen and helium molecules are small, light, and easy to diffuse, the reservoir formation conditions are harsh, which greatly increases the difficulty of exploration. However, due to the easy diffusion of hydrogen and helium molecules, soil gas detection has become an effective method to trace the local enrichment of underground hydrogen and helium. Gases such as methane and carbon dioxide in soil gas are possible co-existing gases of hydrogen and helium. Their content and isotopic characteristics are helpful for analyzing the origin of hydrogen and helium, and are also the objects of soil gas detection.

[0003] For field sampling of soil gas, it is usually analyzed in the laboratory using a gas detector after sampling. However, since hydrogen and helium are very easy to dissipate, after being collected by sampling bags or cylinders, long-distance transportation to the laboratory for measurement will lead to gas loss, resulting in inaccurate measurement results. On the other hand, in order to obtain a large amount of surface data, large-scale sampling will be carried out in large areas, which requires a lot of manpower (sampling, collection, transportation, testing), material resources (sampling bags, cylinders, vehicles, etc.), and financial resources (long-term labor costs, transportation gas costs, laboratory instrument usage costs, etc.), so it is not possible to send all samples to the laboratory. Summary of the invention

[0004] In view of the technical problems existing in the soil gas collection in the prior art, the first aspect of the present invention proposes a cruise gas collection system for soil gas collection, comprising:

[0005] The gas collection container comprises any one or more of a first container, a second container and a third container, wherein the first container comprises a steel cylinder, the steel cylinder is used to store a gas sample at a first pressure, the second container comprises a flexible air bag, the flexible air bag is used to store a gas sample at a second pressure, the second pressure is less than the first pressure, and the third container comprises an air extraction pipeline, the air extraction pipeline and the soil layer to be sampled constitute a soil sample collection container;

[0006] A pretreatment system, comprising a pressure regulating component and a flow regulating component, wherein the pretreatment system is provided with three injection paths, respectively used to be connected to the first container, the second container and the third container;

[0007] The gas analysis system is used to perform chromatography, mass spectrometry and carbon dioxide isotope analysis on the collected gas samples, and obtain the concentrations of hydrogen and helium as well as the carbon dioxide concentration and carbon dioxide isotope ratio in the current gas samples;

[0008] Wherein, the first container is connected to the first injection path, the second container is connected to the second injection path, the third container is connected to the third injection path, the pressure regulating component includes a vacuum device and a pressure regulating valve, the first injection path is connected to the input end of the pressure regulating valve, the vacuum device input end is connected to the second injection path and the third injection path, the vacuum device output end is connected to the input end of the pressure regulating valve, and the pressure regulating valve output end is connected to the flow regulating component, so that the gas sample in the first container, the second container or the third container enters the gas analysis system at a predetermined pressure and flow rate.

[0009] Preferably, the first container, the second container or the third container is detachably connected to the injection path of the pretreatment system.

[0010] Preferably, the input end of the gas extraction device is provided with a first gas selector, the first gas selector is provided with a first input port and a second input port, the first input port is connected to the second container through a flow regulating valve, the second input port is connected to the third container, the flow regulating valve and the first input port of the first gas selector constitute a second injection path, and the second input port of the first gas selector constitutes a third injection path.

[0011] Preferably, the output end of the gas extraction device is provided with a second gas selector, the second selector is provided with a third input port and a fourth input port, the third input port of the second selector is connected to the output end of the gas extraction device, and the fourth input port of the second selector constitutes a first injection path.

[0012] Preferably, a gas-liquid separation tank is provided at the output end of the second selector, a third gas selector is provided at the output end of the gas-liquid separation tank, and the third gas selector is located at the input end of the pressure stabilizing valve.

[0013] Preferably, the gas pressure output from the pre-treatment system to the gas analysis system is 0.1 MPa.

[0014] Preferably, the gas path capacity between each injection path in the pretreatment system and the gas analysis system is A, and the smallest capacity among the first container, the second container or the third container is B, and B≥10A.

[0015] Preferably, the capacity of the flexible air bag is 200-400 ml, the flexible air bag includes an aluminum foil air bag, the length of the exhaust pipe is 15-25 m, the inner diameter of the exhaust pipe is 6 mm, and the air path capacity between each injection path in the pretreatment system and the gas analysis system is less than 30 ml.

[0016] Preferably, the collection system is integrated into a movable platform, the movable platform comprises a wheeled chassis, and the air extraction device is detachably connected to the movable platform.

[0017] Preferably, the gas analysis system includes a chromatography system, a mass spectrometry system, a spectral system, a data acquisition system and an exhaust gas treatment system. The mass spectrometry system is equipped with an independent turbomolecular pump and an electronic pressure controller. The turbomolecular pump is used to evacuate the gas in the pipeline in the gas analysis system, and the electronic pressure controller is used to fill nitrogen into the pipeline in the gas analysis system or the pretreatment system.

[0018] Preferably, after each gas detection, the pipelines in the pre-treatment system and the gas analysis system are evacuated and filled with nitrogen.

[0019] Compared with the prior art, the advantages of the present invention are:

[0020] The walking gas sampling system for soil gas collection proposed in the present invention can sample through three gas sampling methods: gas cylinders, flexible gas bags and air extraction pipelines. Therefore, when the walking carrier drives to a field detection point, if it is very close to the detection point, soil gas sampling can be directly carried out through the pipeline, and the gas will be transported to the mass spectrometer for detection through the pipeline. If in some occasions where the road conditions are poor, for example, the field detection point is far away from the passable road, the walking carrier cannot drive to the vicinity of the destination point, and the pipeline cannot reach the destination point, air extraction equipment and gas sample bags can be used to sample soil gas, and immediately send it to the walking carrier to connect to the mass spectrometer air inlet port for detection. In addition, for some special oil and gas plant areas and other places, when sampling, the gas pressure in the sampled well is relatively high, and it is necessary to first use a steel cylinder to collect gas, and then connect the steel cylinder to the pipeline system of the walking carrier, and then transport the gas to the mass spectrometer for detection through the pipeline.

[0021] Therefore, the cruise gas sampling system for soil gas collection proposed in the present invention can adapt to different sampling points, and perform on-site simultaneous detection of gas samples collected from these sampling points with the same standard, and can more effectively restore the gas sample composition of the current sampling point. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0023] Figure 1 It is a principle block diagram of the cruise gas collection system for soil gas collection shown in the present invention;

[0024] Figure 2It is a structural schematic diagram of a cruise gas collection system for soil gas collection shown in the present invention;

[0025] Figure 3 is a schematic diagram of a sampling path of a first container shown in the present invention;

[0026] Figure 4 is a schematic diagram of a sampling path of the second container shown in the present invention;

[0027] Figure 5 is a schematic diagram of a sampling path of a third container shown in the present invention;

[0028] Figure 6 is a schematic diagram of a processing path for spectral analysis of a gas sample shown in the present invention;

[0029] Figure 7 It is a schematic diagram of a processing path for pre-column separation of a gas sample shown in the present invention;

[0030] Figure 8 It is a schematic diagram of the processing path for mass spectrometry analysis of gas samples shown in the present invention. DETAILED DESCRIPTION

[0031] In order to better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0032] For the collection of soil gas, there may be different sampling scenarios, such as areas where the equipment can be approached or cannot be approached, or special oil and gas plant areas. For gas samples such as hydrogen and helium that are extremely easy to dissipate, distributed sampling followed by centralized laboratory analysis and detection cannot accurately reflect the concentration of the gas. Therefore, it is very necessary to realize real-time on-site sampling and analysis.

[0033] The on-site sampling scenarios are usually divided into three categories. The first category is the detection points that can be reached by mobile devices. These detection points can be directly transported to the mass spectrometer on the mobile device through pipelines for detection. The second category is the detection points that cannot be reached by mobile devices. These detection points can be sampled using gas sample bags and then detected using the mass spectrometer on the mobile device in a very short time. The third category is the sampling wells in the oil and gas plant area. The gas pressure in the sampling wells is high, and steel cylinders can be used as sampling containers. Then, the mass spectrometer on the mobile device can be used for detection in a very short time.

[0034] Therefore, the field collection system proposed in this application can perform real-time field sampling + detection on the sampling points of the above three types of sampling areas, and ensure that each method is carried out with the same detection standard to avoid result deviation caused by interference factors.

[0035] like Figure 1 and Figure 2As shown, the first aspect of the present invention proposes a cruise gas collection system for soil gas collection, including a gas collection container 10, a pretreatment system 20 and a gas analysis system 30, wherein the gas collection container 10 includes any one or more of a first container 11, a second container 12 and a third container 13.

[0036] It can be understood that appropriate sampling containers are selected according to the distribution of sampling points in the sampling area. In order to ensure the timeliness of sampling and monitoring, the next sampling is carried out after one monitoring is completed. When sampling and testing, it is preferred to sample and test the test points in the adjacent area in sequence.

[0037] In a preferred embodiment, the collection system is integrated into a movable platform, which includes a wheeled chassis, such as a manned or unmanned wheeled chassis, which can travel on a flat road to facilitate transfer to a target sampling point or a location close to the sampling point.

[0038] Optionally, if the sampling area is a rectangle, and a number of sampling points in the rectangular area are distributed in a matrix, the sampling and detection of each sampling point should be implemented in sequence according to a serpentine trajectory.

[0039] Optionally, if roads are distributed in the sampling area, sampling and detection are performed preferentially on sampling points near the roads.

[0040] In an optional embodiment, the first container 11 includes a steel cylinder, which is used to store a gas sample at a first pressure. The second container 12 includes a flexible air bag, which is used to store a gas sample at a second pressure, and the second pressure is less than the first pressure. The third container 13 includes an air extraction pipeline, and the air extraction pipeline and the soil layer to be sampled constitute a soil sample collection container.

[0041] Among them, the first container 11 is used to collect gas samples from sampling wells in the oil and gas plant area. After sampling, the pressure in the cylinder is usually 1Mpa~4Mpa. The second container 12 is used to sample and collect sampling points far away from the road. The third container 13 performs real-time collection and detection on sampling points close to the road.

[0042] It should be understood that the distance between the current sampling point and the equipment and the length of the exhaust pipe determine the use of exhaust pipe or flexible air bag for sampling. Usually the length of the exhaust pipe is 15 to 25m. Therefore, for sampling points more than 25m away from the equipment, flexible air bags should be used for collection. After collection, the user should promptly transfer the sample to the sampling interface of the equipment for on-site analysis. For sampling points within 25m of the equipment, exhaust pipes should be used for real-time collection. The collected gas samples should be directly connected to the sampling interface of the equipment for on-site analysis. When the sampling point is a high-pressure gas sample from a sampling well, cylinder sampling should be used. After sampling, the user should promptly transfer the sample to the sampling interface of the equipment for on-site analysis.

[0043] Furthermore, the pretreatment system 20 is intended to give each gas sample a suitable pressure and flow before it enters the gas analysis system 30. Therefore, the pretreatment system 20 includes a pressure regulating component and a flow regulating component 23, and the pretreatment system is provided with three injection paths, which are respectively used to connect to the first container 11, the second container 12 and the third container 13.

[0044] Since the gas content, pressure and uniformity of the first container 11, the second container 12 and the third container 13 are different, the gas sample of each container needs to be processed differently.

[0045] The first container 11 is connected to the first injection path, the second container 12 is connected to the second injection path, and the third container 13 is connected to the third injection path.

[0046] Optionally, the pressure regulating component includes an exhaust device 21 and a pressure-stabilizing valve 22, the first sampling path is connected to the input end of the pressure-stabilizing valve 22, the input end of the exhaust device 21 is connected to the second sampling path and the third sampling path, the output end of the exhaust device 21 is connected to the input end of the pressure-stabilizing valve 22, and the output end of the pressure-stabilizing valve 22 is connected to the flow regulating component 23.

[0047] In this way, the gas sample entering the second injection path and the third injection path is pressurized by the vacuum device 21 so that the pressure reaches a preset value. Before entering the gas analysis system 30, the input flow is controlled by the flow regulating component 23 so that the gas sample in the first container 11 or the second container 12 or the third container 13 enters the gas analysis system 30 at a predetermined pressure and flow rate.

[0048] Since the amount of gas in the flexible air bag is small, in order to ensure that the amount of gas entering the second injection path after being pressurized by the vacuum device 21 is uniform, in an optional embodiment, a first gas selector 24 is provided at the input end of the vacuum device 21, and the first gas selector 24 is provided with a first input port and a second input port. The first input port is connected to the second container 12 through a flow regulating valve 121, and the second input port is connected to the third container 13. The second injection path is constituted by the flow regulating valve 121 and the first input port of the first gas selector 24, and the third injection path is constituted by the second input port of the first gas selector 24.

[0049] In this way, a flow regulating valve 121 is provided at the first input port of the first gas selector 24 to control the amount of gas from the flexible gas bag entering the air extraction device 21. When the output pressure is ensured to be a preset value, the input and output flow rates are preset values. Since the inner diameter and length of the air extraction pipeline are fixed values, which constrain the maximum amount of air intake, there is no need to provide a flow regulating valve in the air extraction pipeline.

[0050] In an optional embodiment, the output end of the gas extraction device 21 is provided with a second gas selector 25, the second selector is provided with a third input port and a fourth input port, the third input port of the second selector is connected to the output end of the gas extraction device 21, and the fourth input port of the second selector constitutes a first injection path. The output end of the second selector is provided with a gas-liquid separation tank 27, the output end of the gas-liquid separation tank 27 is provided with a third gas selector 26, and the third gas selector 26 is located at the input end of the pressure regulating valve 22.

[0051] In this way, since water is easily liquefied after the gas sample is pressurized by the vacuum device 21, a gas-liquid separation tank 27 is provided to enable the gas sample to be separated into gas and liquid after passing through the gas-liquid separation tank 27. Gas sampling after gas-liquid separation is conducive to obtaining better test results.

[0052] In a specific embodiment, Figure 3 As shown, taking the injection of a steel cylinder as an example, the steel cylinder is connected to the fourth input port of the second gas selector 25. The gas in the steel cylinder enters the second gas selector 25 through the first injection path, and then enters the gas-liquid separation tank 27. After passing through the gas-liquid separation tank 27, gas-liquid separation is achieved, and then enters the third gas selector 26. Finally, it passes through the pressure regulating valve 22 and the flow regulating component 23, so that the gas flow entering the ten-way injection valve 31 is a constant pressure and constant flow gas sample.

[0053] In a specific embodiment, Figure 4 As shown, taking the flexible air bag as an example, the flexible air bag is connected to the flow regulating valve 121. Through the pressurizing action of the vacuum device 21, the gas sample in the flexible air bag passes through the flow regulating valve 121, the first gas selector 24 and the vacuum device 21 in sequence. After being pressurized by the vacuum device 21, the gas sample enters the second gas selector 25 and the gas-liquid separation tank 27. After passing through the gas-liquid separation tank 27, the gas-liquid separation is achieved, and then the gas sample enters the third gas selector 26. After that, the gas sample passes through the pressure stabilizing valve 22 and the flow regulating component 23, so that the gas flow entering the ten-way injection valve 31 is a constant pressure and constant flow gas sample.

[0054] In an optional embodiment, the gas pressure output by the pre-treatment system 20 to the gas analysis system 30 is 0.1 MPa.

[0055] Optionally, the suction device 21 is detachably connected to the movable platform. When sampling the flexible air bag, the suction device 21 is detachable and transferred to the sampling point by the sampling personnel, and an air passage of a predetermined size is drilled at the sampling point using a drilling tool (detection metal tube), the detection tool is placed in the air passage, the suction device 21 is connected between the air passage and the flexible air bag, and the air sample in the air passage is sucked into the flexible air bag.

[0056] In a specific embodiment, Figure 5As shown, taking the exhaust pipeline as an example, the two ends of the exhaust pipeline are respectively connected to the airway and the first gas selector 24. Through the exhaust action of the exhaust device 21, the gas sample in the airway enters the first gas selector 24 and the exhaust device 21 through the exhaust pipeline, and after being pressurized by the exhaust device 21, enters the second gas selector 25 and the gas-liquid separation tank 27, realizes gas-liquid separation after passing through the gas-liquid separation tank 27, and then enters the third gas selector 26, and then passes through the pressure regulating valve 22 and the flow regulating component 23, so that the airflow entering the ten-way injection valve 31 is a constant pressure and constant flow gas sample.

[0057] It should be understood that, since the first container 11, the second container 12 or the third container 13 needs to be frequently disconnected from the pipeline during the sampling and detection process, preferably, the first container 11, the second container 12 or the third container 13 is detachably connected to the injection path of the pretreatment system, for example, using a quick-release connector.

[0058] In the above embodiment, in order to prevent the residual gas in the fixed pipeline of the equipment from affecting the gas sample, the gas path capacity between each injection path in the pretreatment system 20 and the gas analysis system 30 is A, and the smallest capacity among the first container 11, the second container 12 or the third container 13 is B, where B≥10A.

[0059] Optionally, the capacity of the flexible air bag is 200-400 ml, the flexible air bag includes an aluminum foil air bag, the length of the exhaust pipe is 15-25 m, the inner diameter of the exhaust pipe is 6 mm, and the gas path capacity between each injection path in the pretreatment system 20 and the gas analysis system 30 is less than 30 ml.

[0060] In this way, during detection, the front-stage gas is discarded and not detected, that is, the gas path between each injection path in the pre-treatment system 20 and the gas analysis system 30 is emptied.

[0061] In the above embodiment, the gas analysis system 30 is used to perform chromatography, mass spectrometry and carbon dioxide isotope analysis on the collected gas sample, and obtain the concentrations of hydrogen and helium as well as the carbon dioxide concentration and carbon dioxide isotope ratio in the current gas sample.

[0062] Specifically, the gas analysis system 30 includes a chromatographic system, a mass spectrometry system, a spectral system, a data acquisition system and an exhaust gas treatment system, which effectively separates different components in the mixture, determines the composition and purity of the sample, and detects the target substance. The chromatographic system determines the concentration of specific components in the sample by measuring parameters such as peak area or peak height, and compares it with a known standard or database to sensitively detect trace target substances in the sample. The mass spectrometry system includes a quadrupole system, an ion source, a detector, a vacuum system, a circuit control system, and hydrogen-helium detection software. Spectral system: a precisely temperature-controlled spectral measurement box, the entire analysis system remains gas-tight. It contains components such as a quantum cascade laser, a laser temperature controller, an infrared laser detector, and a hollow absorption cavity pool. The absorption cavity pool is about 1 meter long and flows into a hollow waveguide through a capillary with an outer diameter of 1 / 16 inch, and infrared laser spectral detection is performed on the gas components flowing through it. Data acquisition system: includes a computer (with Windows system pre-installed), a high-speed data acquisition card, and power supplies for various instruments. The fixed rear end of the data acquisition card is connected to three SMA signal lines, namely the data acquisition card trigger connector, the sample gas detector connection line and the reference gas detector connection line, which are used to connect the spectrometer and the laser driver. The laser driver in the instrument provides drive for the spectrometer laser, responsible for generating the modulated waveform and driving the laser to light up.

[0063] The mass spectrometry system is equipped with an independent turbomolecular pump and an electronic pressure controller. The turbomolecular pump is used to evacuate the gas in the pipeline of the gas analysis system 30 , and the electronic pressure controller is used to fill nitrogen into the pipeline of the gas analysis system 30 or the pretreatment system 20 .

[0064] The electronic pressure controller includes a nitrogen gas source, which includes multiple output ends, one of which can be connected to the air inlet end of the pretreatment system 20 to flush the pipelines in the pretreatment system 20 and the gas analysis system 30. The turbomolecular pump can simultaneously perform suction to extract the remaining exhaust gas from the pipeline.

[0065] Preferably, after each gas detection, the pipelines in the pre-treatment system 20 and the gas analysis system 30 are evacuated and filled with nitrogen. In this way, the results of the gas detection after each detection can be guaranteed to be relatively accurate.

[0066] like Figure 1As shown, in an optional embodiment, taking the use of steel cylinders for collection and detection as an example: the steel cylinder gas directly obtained from the wellhead of the gas production plant, the internal gas pressure is usually 1MP~4MP, the steel cylinder is connected to the fourth input port of the second gas selector 25, the sample gas is purified and pressure-regulated by the pre-treatment system 20, and the gas passes through the chromatographic separation system to separate the required hydrogen, helium, methane, carbon dioxide, etc. and transmit them to the mass spectrometry system, and the remaining unnecessary gases are discharged through the tail gas treatment system. The tail gas treatment system can be selected by activated carbon adsorption, catalytic oxidation, etc., which can effectively Remove harmful substances from tail gas and improve the emission quality of tail gas. For hydrogen, helium, methane and carbon dioxide in the mass spectrometry system, the pressure is appropriately monitored by a vacuum gauge to prevent the mass spectrometer from being powered on at too high a pressure, so as to provide a guarantee for gas analysis with the best sensitivity. Some of the other gases are measured by multipliers to measure extremely small ion currents or extremely high measurement speeds, increase the sensitivity of the instrument and reduce the partial pressure, and then transmit the data analyzed by the mass spectrometry system to the computer terminal for processing. Some of the residual gas spectrum and background pressure conditions are optimized through turbomolecular pumps. Before tail gas treatment, an independent pump is usually required to evacuate the measurement system. Small units with turbomolecular pumps and diaphragm pumps can be used for this purpose. Finally, the tested gas is subjected to tail gas treatment to avoid polluting the environment. The mass spectrometry system is also equipped with an electronic pressure controller, which can fill the pipeline with an appropriate amount of nitrogen. After each test, the pipeline is flushed and the tail gas is treated to avoid contamination caused by the entry of miscellaneous gases and improve the accuracy of the test results.

[0067] A method of using the above-mentioned cruise gas collection system for soil gas collection is as follows:

[0068] According to sampling requirements, select a suitable sampling point in the field and move the underwater gas sampling system for soil gas collection to a position close to the sampling point;

[0069] The selected multiple sampling points include a first sampling point, a second sampling point and a third sampling point. The sampling area is defined to include a road. The sampling well included in the collection area is the first sampling point, the sampling point far away from the road area (more than 25m away from the sampling point) is the second sampling point, and the sampling point located in the road area (less than 25m away from the sampling point) is the third sampling point.

[0070] Next, the first container 11, the second container 12 and / or the third container 13 are used to sample the gas at the sampling points. The first container 11 is used to sample the gas at the first sampling point, the second container 12 is used to sample the gas at the second sampling point, and the third container 13 is used to sample the gas at the third sampling point, wherein the first container 11 and the second container 12 are connected to the pre-processing system 20 after sampling, and the third container 13 is connected to the pre-processing system 20 before sampling;

[0071] Among them, for sampling at the first sampling point, the first container 11 is connected to the sampling well, and the gas sample is pressed into the first container 11 by the pressure of the sampling well; for sampling at the second sampling point, an airway of a predetermined size is drilled out at the sampling point using a drilling tool, a detection tool is placed in the airway, a suction device 21 is connected between the airway and the second container 12, and the gas sample in the airway is pumped into the second container 12; for sampling at the third sampling point, an airway of a predetermined size (diameter of about 2 cm and length of about 1 m) is drilled out at the sampling point using a drilling tool, a detection tool is placed in the airway, and both ends of the third container 13 are connected to the airway and the pretreatment system 20 respectively;

[0072] Furthermore, the pre-treatment system 20 allows the gas sample in the first container 11 , the second container 12 or the third container 13 to enter the gas analysis system 30 at a predetermined pressure and flow rate for gas sample analysis.

[0073] It should be understood that during the sampling process of the third container, due to the long length of the pipeline, the gas sample enters the mass spectrometry system unevenly when it is drawn. Therefore, the concentration of the gas sample at different detection times should be considered during detection.

[0074] Specifically, define the volume of the pipeline as V and the volume of the underground hole as V 管 (V 管 It can be calculated using the pipe diameter R and the hole depth h, that is, V 管 =1 / 4πR 2 *h), the pumping rate of the pumping device is Q, the unit is ml / min, the delay time T from the sample gas to the detector is calculated according to the pumping rate Q and the volume V of the pipeline, the unit is s, and the calculation is T=V / Q after the units are aligned, that is, from the moment of starting pumping, after a delay of Ts, the detection begins. For any time tx after the start of detection, the concentration C of hydrogen or helium h2 x or C He x can be expressed by the following formula:

[0075]

[0076] Where t0 is the time of the first peak, t N is the time of the last peak, C t is the concentration of hydrogen or helium at time t, C h2 x or C He x, the test interval is 1min / time.

[0077] Therefore, the concentration corresponding to each detection data can be obtained through the above formula, that is, the corresponding relationship between the concentration and quantity of hydrogen or helium.

[0078] In this way, the detection results at different times correspond to detection results of different concentrations, among which, when the concentration peak is the highest, it is closer to the original concentration of hydrogen and helium in the gas sample.

[0079] Since gas is compressible, the pressure and flow rate of the sample gas must be guaranteed to ensure that the amount of sample gas entering the system is stable each time. Therefore, the gas samples in the first container 11, the second container 12 or the third container 13 are all controlled to stabilize the pressure and flow to ensure the flow rate of the sample gas.

[0080] like Figure 6 As shown, after the gas treated with pressure stabilization and flow stabilization enters the ten-way injection valve 31, the hydrogen and helium concentrations and the carbon dioxide concentration and its isotope are detected. The gas path for detecting the hydrogen and helium concentrations is shown by the red line in the figure, and the gas path for detecting the carbon dioxide concentration and its isotope is shown by the blue line in the figure.

[0081] Specifically, the gas used for hydrogen and helium concentration detection enters the chromatographic system through the cut valve from the ten-way injection valve 31 for pre-separation. First, the air and the sample that will peak later are directly discharged from the system in the pre-column 33. Then, the sample processed by the pre-column 33 mainly contains hydrogen, helium and a small amount of air. At this time, it enters the first separation column 36 for further separation. After the hydrogen and helium enter the second separation column 37, the remaining air is discharged from the system.

[0082] After hydrogen and helium are separated from the second separation column 37, they enter the mass spectrometer system and are separated by a quadrupole, outputting mass number data of M / Z=2 and M / Z=4 respectively, thereby obtaining the concentrations of hydrogen and helium.

[0083] Specifically, the device for measuring carbon dioxide concentration and isotopes has a measurement range of only 300ppm to 2000ppm. On the one hand, its measurement range is relatively small, so a dilution module is added to the system. By fixing the flow rate of the sample gas, such as 50sccm, zero-level air 38 is added at the back end for dilution, thereby widening the measurement range and ensuring that the instrument can measure 300ppm to 20000ppm.

[0084] Specifically, Figure 6 As shown, taking the gas sample of the cylinder as an example, the gas sample passes through the second gas selector 25, enters the gas-liquid separation tank 27, and enters the injection port. After exiting the injection port, it enters the third gas selector 26 and then enters the pressure regulating valve 22 → flow regulating component 23 → port 9 of the ten-way injection valve 31 → quantitative ring 32 → port 1 → port 0 and exits to the dilution mixing chamber 35 of the carbon dioxide concentration and isotope detector → spectral analysis (shown by the blue line).

[0085] like Figure 7As shown, the ten-way injection valve 31 is opened, and the nitrogen in the electronic pressure controller 39 enters port 7 of the ten-way injection valve 31 → port 8 → quantitative ring 32 (bringing the gas in the quantitative ring of the previous step backward) → port 1 → port 2 → pre-column 33 → port 6 → port 5 → first separation column 36 → port 5 of the six-way switching valve 34 → port 4 → second separation column 37 → mass spectrometry analysis (shown by the red line).

[0086] The main function of this step is to bring the sample in the quantitative ring 32 into the separation system of the mass spectrometer and separate it in the pre-column 33. Since the speed of helium and hydrogen is greater than that of other components such as air, when all the helium and hydrogen come out of the pre-column 33 and enter the first separation column 36, the ten-way injection valve 31 is immediately closed.

[0087] like Figure 8 As shown, after the separation of the pre-column 33 is completed, hydrogen, helium and a small amount of oxygen and nitrogen enter the first separation column 36, and the output nitrogen from the middle of the electronic pressure controller 39 is from port 4 → port 5 → first separation column 36 → port 5 of the six-way switching valve 34 → port 4 → second separation column 37 → mass spectrometer. When hydrogen and helium completely enter the separation column 2 from the separation column 1, substances such as oxygen and nitrogen are still in the separation column 1. At this time, the six-way switching valve 34 is opened to become the following gas path.

[0088] In this state, the nitrogen on the right side of the electronic pressure controller 39 enters port 3 → port 4 of the six-way switching valve 34 → the second separation column 37 → mass spectrometry, completing the mass spectrometry detection of hydrogen and helium gases. At the same time, the oxygen, nitrogen and other gases in the first separation column 36 are carried by the nitrogen in the middle of the electronic pressure controller 39 and continue to be discharged from port 5 → port 6 of the six-way switching valve 34.

[0089] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A cruise gas collection system for soil gas collection, characterized in that: include: A gas collection container (10) comprises any one or more of a first container (11), a second container (12) and a third container (13), wherein the first container (11) comprises a steel cylinder, the steel cylinder being used to store a gas sample at a first pressure, the second container (12) comprises a flexible air bag, the flexible air bag being used to store a gas sample at a second pressure, the second pressure being less than the first pressure, and the third container (13) comprises an air extraction pipeline, the air extraction pipeline and the soil layer to be sampled constitute a soil sample collection container; A pretreatment system (20), comprising a pressure regulating component and a flow regulating component (23), wherein the pretreatment system is provided with three injection paths, respectively used to be connected to the first container (11), the second container (12) and the third container (13); A gas analysis system (30) is used to perform chromatography, mass spectrometry and carbon dioxide isotope analysis on the collected gas sample, and obtain the concentration of hydrogen and helium as well as the concentration of carbon dioxide and the carbon dioxide isotope ratio in the current gas sample; The first container (11) is connected to a first injection path, the second container (12) is connected to a second injection path, the third container (13) is connected to a third injection path, the pressure regulating component comprises a suction device (21) and a pressure regulating valve (22), the first injection path is connected to an input end of the pressure regulating valve (22), the input end of the suction device (21) is connected to the second injection path and the third injection path, the output end of the suction device (21) is connected to the input end of the pressure regulating valve (22), and the output end of the pressure regulating valve (22) is connected to the flow regulating component (23), so that the gas sample in the first container (11) or the second container (12) or the third container (13) enters the gas analysis system (30) at a predetermined pressure and flow rate.

2. The cruise gas collection system for soil gas collection according to claim 1 is characterized in that: The first container (11), the second container (12) or the third container (13) is detachably connected to the injection path of the pretreatment system.

3. The cruise gas collection system for soil gas collection according to claim 1 is characterized in that: The input end of the gas extraction device (21) is provided with a first gas selector (24), and the first gas selector (24) is provided with a first input port and a second input port, the first input port is connected to the second container (12) through a flow regulating valve (121), and the second input port is connected to the third container (13), the flow regulating valve (121) and the first input port of the first gas selector (24) form a second injection path, and the second input port of the first gas selector (24) forms a third injection path.

4. The cruise gas collection system for soil gas collection according to claim 3 is characterized in that: The output end of the gas extraction device (21) is provided with a second gas selector (25), the second selector is provided with a third input port and a fourth input port, the third input port of the second selector is connected to the output end of the gas extraction device (21), and the fourth input port of the second selector constitutes a first injection path.

5. The cruise gas collection system for soil gas collection according to claim 4 is characterized in that: The output end of the second selector is provided with a gas-liquid separation tank (27), the output end of the gas-liquid separation tank (27) is provided with a third gas selector (26), and the third gas selector (26) is located at the input end of the pressure stabilizing valve (22).

6. The cruise gas collection system for soil gas collection according to claim 1 is characterized in that: The gas path capacity between each injection path in the pretreatment system (20) and the gas analysis system (30) is A, and the smallest capacity among the first container (11), the second container (12) or the third container (13) is B, and B≥10A.

7. The cruise gas collection system for soil gas collection according to claim 1 is characterized in that: The capacity of the flexible air bag is 200-400 ml, the flexible air bag comprises an aluminum foil air bag, the length of the exhaust pipe is 15-25 m, the inner diameter of the exhaust pipe is 6 mm, and the air path capacity between each injection path in the pretreatment system (20) and the gas analysis system (30) is less than 30 ml.

8. The cruise gas collection system for soil gas collection according to claim 1 is characterized in that: The collection system is integrated into a movable platform, which comprises a wheeled chassis, and the air extraction device (21) is detachably connected to the movable platform.

9. The cruise gas collection system for soil gas collection according to any one of claims 1 to 8, characterized in that: The gas analysis system (30) comprises a chromatography system, a mass spectrometry system, a spectral system, a data acquisition system and an exhaust gas treatment system. The mass spectrometry system is equipped with an independent turbomolecular pump and an electronic pressure controller. The turbomolecular pump is used to evacuate the gas in the pipeline of the gas analysis system (30), and the electronic pressure controller is used to fill nitrogen into the pipeline of the gas analysis system (30) or the pretreatment system (20).

10. The cruise gas collection system for soil gas collection according to claim 9, characterized in that: After each gas detection, the pipelines in the pre-treatment system (20) and the gas analysis system (30) are evacuated and filled with nitrogen.

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