Mobile while-drilling soil gas detection system and wide concentration range detection method

Abstract

The present application relates to the technical field of pollutant detection, and in particular to a mobile while-drilling soil gas detection system and a wide-concentration-range detection method, which comprises: a movable platform comprising a loading platform and a driving wheel connected to the loading platform; and a drilling component mounted on the loading platform. The present application introduces an inert gas compensation mechanism, a gas dilution module provided in a sampling module is used to dynamically adjust the proportion of inert gas in the sampling system, dilute the flow of high-concentration samples, and reduce the concentration of pollutants at the inlet of the detection module, so as to expand the effective detection range of the detection module. A low-detection-limit detector can be selected to inhibit the signal overload of high-concentration samples without losing the sensitivity of low-concentration samples, realize continuous detection of pollutants in a wide concentration range, and balance the trace recognition and high-concentration anti-saturation capability, thereby significantly improving the analysis applicability of complex contaminated sites.

Description

Technical Field

[0001] This invention relates to the field of pollutant detection technology, and more specifically to a mobile soil gas detection system while drilling and a detection method with a wide concentration range. Background Technology

[0002] In response to the problems of low efficiency, insufficient accuracy, destructive sampling, and cross-contamination risks in traditional contaminated site investigation technologies, and combining the advantages of soil gas detection in reflecting pollution status and environmental risks, technicians have developed a drilling-while-drilling soil gas detection equipment. This equipment overcomes the shortcomings of traditional soil gas monitoring wells, which are limited in drilling depth and cannot be monitored in real time, and enables in-situ drilling-while-drilling detection of underground pollutants.

[0003] Currently, in-situ drilling detection technology for contaminated sites is limited by the narrow dynamic range of detectors. To ensure sensitive detection of low-concentration target substances, low detection limit detectors are usually selected. However, if high-concentration pollutants are encountered, signal saturation is likely to occur. If high detection limit detectors are selected, low-concentration samples will be missed due to insufficient sensitivity, making it difficult to meet the application needs of complex contaminated sites with significant differences in pollution concentration. Summary of the Invention

[0004] To address the technical problems existing in existing soil gas detection technologies, the first aspect of this invention proposes a mobile drilling-while-drilling soil gas detection system, comprising:

[0005] A mobile platform, including a loading platform and drive wheels connected to the loading platform;

[0006] The drilling component is mounted on the loading platform. The drilling component includes a drilling detection probe and a push drilling rig that drives the drilling detection probe to drill and pull it out. The drilling detection probe is configured to be driven by the push drilling rig to drill into a soil layer at a predetermined depth and collect gas samples from the current soil layer.

[0007] A sample introduction module, connected to the drilling detection probe, is used to process the gas sample entering the sample introduction module;

[0008] A sample acquisition module, connected to the sample introduction module, is used to collect and save gas samples entering the sample introduction module;

[0009] A detection module, connected to the sample introduction module, is used to detect the type and concentration of the target gas in the gas sample inside the sample introduction module in real time.

[0010] The gas path control module includes a distribution valve, which has two inlet ends and multiple outlet ends;

[0011] A gas supply module is connected to the distribution valve and is used to supply hydrogen and inert gas to the two inlet ends of the distribution valve, respectively. The multiple outlet ends of the distribution valve supply target types and flow rates of gas to the drilling system, the sampling module, and the detection system, respectively.

[0012] The controller is connected to the movable platform, drilling components, sample injection module, sample acquisition module, detection module, gas path control module, and gas supply module.

[0013] The sample injection module includes a gas dilution module. A first flow meter is provided upstream of the gas dilution module, and a second flow meter is provided downstream of the gas dilution module. The gas dilution module is used to replenish a predetermined amount of inert gas into the gas sample and maintain the same gas flow rate through the first flow meter and the second flow meter.

[0014] The detection upper limit value of the detection module is defined as S. max The detection limit is S min The controller is configured to detect the target gas concentration signal value S and S in real time by the detection module. max and S min The relationship is such that the gas dilution module controls the proportion of inert gas in the gas sample to ensure that the target gas concentration signal value S in the gas sample entering the detection module is within a preset range.

[0015] Preferably, the gas dilution module is configured to operate when the target gas concentration signal value S ≥ 80%. max or ≤5S min At the same time, adjust the proportion of inert gas in the gas sample;

[0016] Among them, D n =D n-1 ×S / S t D n D is the adjusted dilution factor. n-1 The initial state D is the dilution factor before adjustment. n-1 S is 1. t S is the target signal value. t S is the geometric mean of the upper and lower limits, and S is the target gas concentration signal value actually detected by the detection module.

[0017] Preferably, the gain of the detection module is set to be adjusted synchronously according to the dilution factor of the gas sample by the gas dilution module;

[0018] Among them, G n =D n G n This is the gain of the adjusted detection module.

[0019] Preferably, the gas dilution module includes a Y-shaped pipe, which includes a first input pipe, a second input pipe, and an output pipe. The first input pipe is equipped with a first flow valve and an exhaust pipe, and the second input pipe is equipped with a second flow valve.

[0020] The first input pipe is connected to the probe outlet pipe to receive the gas sample entering through the probe outlet pipe. The first flow valve controls the first part of the gas sample to enter the output pipe and the second part of the gas sample to enter the exhaust pipe. The second input pipe is connected to the outlet end of the distribution valve and the second flow valve controls the flow rate of the inert gas entering the second input pipe.

[0021] Preferably, the controller is configured to adjust the opening of the second flow valve and the first flow valve according to the target dilution ratio of the inert gas in the gas sample, so that the gas flow rates of the first flow meter and the second flow meter are consistent.

[0022] Preferably, a hollow fiber drying tube is provided between the first flow meter and the gas dilution module. The hollow fiber drying tube includes an insulation shell and an outer tube and an inner tube disposed within the insulation shell. The first end of the inner tube is connected to the output end of the first flow meter, and the second end is connected to the input end of the gas dilution module. A separation chamber is formed between the outer tube and the inner tube. The outer tube is provided with a backflush gas inlet and a backflush gas outlet. The backflush gas inlet is connected to the outlet end of the distribution valve, allowing flowing inert gas to enter the separation chamber. The inner tube includes a hollow fiber membrane tube for water vapor to permeate.

[0023] Preferably, the drilling detection probe includes a probe body, a gas sample collection chamber, and a selective permeation membrane structure disposed outside the gas sample collection chamber. The probe body is also provided with a probe inlet pipe and a probe outlet pipe, both of which are connected to the gas sample collection chamber. The probe body is also provided with a heating component for heating the gas sample collection chamber.

[0024] Preferably, the direct-push drilling rig is used to control the drilling speed of the probe body, wherein the controller controls the drilling speed of the direct-push drilling rig based on the difference between the real-time temperature of the selectively permeable membrane structure and a preset value.

[0025] A second aspect of this invention provides a technical solution: a mobile drilling-while-drilling soil gas detection method with a wide concentration range, using the aforementioned mobile drilling-while-drilling soil gas detection system, comprising the following steps:

[0026] Step 1: Pipeline cleaning. Inert gas at a predetermined flow rate is introduced into the injection module. The signal value is detected by the detection module. If the signal value change is less than the preset value within a predetermined period, the pipeline cleaning is completed.

[0027] Step 2: Detection module calibration. External standard gas is introduced into the injection module at a constant flow rate. If the change in the signal value of the detection module is less than the preset value within a predetermined time, and the maximum signal value deviation is less than the preset value, then the detection module meets the usage requirements.

[0028] Step 3: System calibration. Use a standard solution to calibrate the system on the selective permeable membrane structure of the drilling detection probe, record the peak elution of the detection module, and compare it with the standard spectrum, including peak elution time and maximum peak height parameters. If the preset deviation is not exceeded, the system calibration is completed.

[0029] Step 4: Drill at the target location, assemble the extension probe, and control the probe to drill using a direct-push drilling rig. After drilling to a predetermined depth, stop for the time required for the sample to be transferred from the selective permeation membrane to the detection module, and continue drilling.

[0030] Step 5: After drilling to the predetermined depth, remove the probe rod and probe in sequence, and then perform the system calibration in Step 3. If the requirements are met, the test ends.

[0031] In step 4, the gas sample collection and detection at the predetermined depth includes the following steps:

[0032] Step 41: Purge the gas sample in the gas sample collection chamber with inert gas and introduce it into the sample introduction module;

[0033] Step 42: Dehumidify the gas sample entering the injection module;

[0034] Step 43: Detect the dehumidified gas sample using the detection module and obtain the current gas sample's detection concentration signal;

[0035] Among them, when the target gas concentration signal value S detected by the detection module reaches 80%S max If drilling is interrupted, the dilution factor should be adjusted, and the gain of the result should be adjusted simultaneously; if the target gas concentration signal value S is less than 5 times S min If drilling is stopped immediately, adjust the dilution factor. If the dilution factor has been adjusted to 1 and cannot be diluted further, continue drilling normally and adjust the result gain simultaneously.

[0036] The dilution factor and the resulting gain are adjusted according to the following formula:

[0037] D n =D n-1 ×S / S t ;

[0038] G n =D n ;

[0039] Where S is the target gas concentration signal value actually detected by the detection module, and D n D is the adjusted dilution factor. n-1 The initial state D is the dilution factor before adjustment. n-1 G is 1. n To adjust the gain of the detection module, S t S is the target signal value. t It is the geometric mean of the upper and lower limits.

[0040] Preferably, step 4 also includes a gas sample storage step, in which the gas sample in the gas sample collection chamber is purged into the sample injection module and stored through an independent gas bag in the sample injection module.

[0041] Compared with the prior art, the advantages of the present invention are as follows:

[0042] To address the significant differences in contaminant concentrations at sites, low-limit detectors are typically chosen to ensure sensitive detection of low-concentration targets. However, high-concentration samples easily exceed the detector's linear range, leading to signal saturation and the formation of a "flat-top peak," which affects quantitative accuracy. Therefore, this application introduces an inert gas compensation mechanism. By using a gas dilution module within the sample introduction module, the proportion of inert gas in the introduction system is dynamically adjusted to dilute the flow rate of high-concentration samples, reducing the contaminant concentration at the inlet of the detection module. This expands the effective detection range of the detection module, allowing for the selection of low-limit detectors. Without sacrificing sensitivity for low-concentration samples, this mechanism suppresses signal overload at high concentrations, enabling continuous detection of contaminants over a wide concentration range. It balances trace detection with high-concentration anti-saturation capabilities, significantly improving the analytical applicability to complex contaminated sites. Attached Figure Description

[0043] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0044] Figure 1 This is a schematic diagram of the structure of the mobile drilling soil gas detection system shown in this invention;

[0045] Figure 2 This is a schematic diagram of the hollow fiber drying tube shown in this invention;

[0046] Figure 3 This is a schematic diagram of the gas dilution module shown in this invention. Detailed Implementation

[0047] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0048] {Example 1}

[0049] Combination Figure 1 As shown, the first aspect of the present invention proposes a mobile soil gas detection system while drilling, including a mobile platform, a drilling component 10, a sample injection module, a sample acquisition module 30, a detection module 40, a gas path control module 50, a gas supply module 60, and a controller.

[0050] In an optional embodiment, the movable platform includes a loading platform and drive wheels connected to the loading platform. The drive wheels can move the loading platform to the target location. The drive system of the drive wheels can be controlled by a remote controller, including functions such as steering, forward, reverse, and speed change, to meet remote control movement requirements.

[0051] The loading platform is used to carry the gas supply module, sample injection module, gas path control module, detection module, data acquisition module, and computer terminal, etc.

[0052] Furthermore, the drilling component 10 is mounted on the loading platform. The drilling component 10 includes a drilling detection probe and a push-type drilling rig that drives the drilling detection probe to drill and pull it out. The drilling detection probe is configured to be driven by the push-type drilling rig to drill into the soil layer at a predetermined depth and collect gas samples from the current soil layer.

[0053] Preferably, the direct-push drilling rig is used to control the drilling speed of the probe body, wherein the controller controls the drilling speed of the direct-push drilling rig based on the difference between the real-time temperature of the selective permeable membrane structure 12 and a preset value.

[0054] It should be understood that temperature affects the volatilization of organic pollutants. When the actual heating temperature of the selective osmosis membrane does not match the preset value, the drilling speed should be adjusted appropriately. Specifically:

[0055] When 10>Δ T ≥5, V n =V n-1 -a%Δ T When 20 > Δ T ≥10, V n =V n-1 -b%Δ T If Δ T If the value is ≥20, stop drilling immediately and wait for Δ T <5. Resume drilling.

[0056] Among them, |Δ T | represents the absolute value of the difference between the actual temperature and the preset temperature; a and b are drilling speed adjustment coefficients, V n and V n-1 These are the adjusted drilling speed and the previous drilling speed, respectively, where 2cm / s≥Vn ≥0cm / s.

[0057] Optionally, the drilling detection probe includes a probe body, a gas sample collection chamber 11, and a selective permeation membrane structure 12 disposed outside the gas sample collection chamber 11. The probe body also includes a probe inlet pipe 14 and a probe outlet pipe 15, both of which are connected to the gas sample collection chamber 11. The probe body also includes a heating element 13, which is used to heat the gas sample collection chamber 11.

[0058] Optionally, the gas sampling chamber 11 is a metal heating chamber. The selective permeation membrane structure 12 consists of a substrate, a metal mesh, and a membrane material. The metal mesh is fixed to the substrate by welding, and the surface is coated with a complete membrane material. The membrane material is waterproof and breathable, and has a certain barrier effect on inert small molecule gases such as nitrogen, while allowing most volatile organic pollutants to pass through.

[0059] Furthermore, an electric heating element is provided to heat the probe inlet pipe 14 and the probe outlet pipe 15, for example, by setting a resistance wire around the pipeline for heating.

[0060] Combination Figure 1 As shown, when the detection probe is driven by the direct-push drilling rig to drill into the ground to a predetermined depth, the heating element 13 and the electric heating elements around the pipeline heat the gas sampling chamber 11 and the surrounding gas pipeline, and the gas enters the gas sampling chamber 11. The carrier gas is brought into the gas sampling chamber 11 by the probe inlet pipe 14, and the sample gas is brought into the probe outlet pipe 15 and output to the sample injection module, and then detected by the detection module 40.

[0061] Thus, by setting up heating component 13 and electric heating component, the soil gas transmission pipeline (probe inlet pipe 14 and probe outlet pipe 15) is heated. While reducing sample transmission loss, it can also accelerate purging, achieve rapid aging of the pipeline, and speed up system stability. At the same time, the heating of the transmission line can effectively reduce the loss of volatile organic pollutants, solving the problems of large pollutant loss and long pipeline aging time in soil gas transmission.

[0062] The sample introduction module is connected to the drilling detection probe and is used to process the gas sample entering the sample introduction module; the sample acquisition module 30 is connected to the sample introduction module and is used to store the gas sample entering the sample introduction module; the detection module 40 is connected to the sample introduction module and is used to detect the type and concentration of the target gas in the gas sample in the sample introduction module in real time.

[0063] Optionally, the detection module 40 includes PID, FID, XSD, and ECD detectors. The sample first enters the PID detector and then is diverted to the FID, XSD, and ECD detectors. The FID detector is connected to the gas path control module 50 via a metal gas tube and is used to receive hydrogen gas supplied by the gas supply module 60.

[0064] Optionally, the sample collection module 30 includes a sample collection tube, a low-temperature storage box, and a gas bag. The first end of the sample collection tube is connected to the sample injection module, and the second end is connected to the gas bag for collecting the gas sample discharged from the gas sample collection chamber 11. The low-temperature storage box has a hollow structure and places the gas bag inside for low-temperature storage of the gas bag to reduce the loss of volatile organic compounds.

[0065] Combination Figure 1 As shown, the sample injection module includes a gas dilution module 23. A first flow meter 21 is provided upstream of the gas dilution module 23, and a second flow meter 24 is provided downstream of the gas dilution module 23. The gas dilution module 23 is used to replenish a predetermined amount of inert gas into the gas sample and maintain the same gas flow rate through the first flow meter 21 and the second flow meter 24.

[0066] In this way, the pressure in the entire injection pipeline will not change, which helps to maintain the pressure balance of the gas path and make the measurement results of the detection module 40 more accurate.

[0067] Furthermore, a hollow fiber drying tube 22 is provided between the first flow meter 21 and the gas dilution module 23. In this way, by setting the hollow fiber drying tube 22, the gas sample entering the detection module 40 can be dehumidified, removing moisture and preventing abnormal fluctuations in the signal value of the detection module 40 caused by water vapor entering the pipeline.

[0068] Specifically, in combination Figure 2 As shown, the hollow fiber drying tube 22 includes an insulation shell 221 and an outer tube 222 and an inner tube 223 disposed inside the insulation shell 221. The first end of the inner tube 223 is connected to the output end of the first flow meter 21, and the second end is connected to the input end of the gas dilution module 23. A separation chamber is formed between the outer tube 222 and the inner tube 223.

[0069] The outer tube 222 is provided with a backflush gas inlet 227 and a backflush gas outlet 226. The backflush gas inlet 227 is connected to the outlet of the distribution valve, so that flowing inert gas enters the separation chamber. The inner tube 223 includes a hollow fiber membrane tube for water vapor to pass through.

[0070] Furthermore, the insulation shell 221 is used to control the temperature of the hollow fiber gas drying module to ensure the dehydration efficiency, and the temperature is generally controlled within 100℃.

[0071] Thus, as the gas sample flows from the first end 224 of the inner tube 223 to the second end 225, the humidity inside the separation chamber is low due to the inert gas flowing outside the inner tube 223, while the humidity inside the inner tube 223 is high. The water vapor is discharged into the separation chamber through the humidity difference, making the humidity of the gas sample passing through the hollow fiber drying tube 22 even lower.

[0072] Furthermore, the gas path control module 50 includes a distribution valve, which has two inlet ends and multiple outlet ends. The gas supply module 60 is connected to the distribution valve and is used to supply hydrogen and inert gas to the two inlet ends of the distribution valve, respectively. The multiple outlet ends of the distribution valve supply the target type and flow rate of gas to the drilling system 10, the sampling module, and the detection system 40, respectively.

[0073] Specifically, in combination Figure 1 As shown, the two inlet ends of the distribution valve are connected to a hydrogen gas source and an inert gas source, respectively. The four outlet ends of the distribution valve are the first outlet pipe 51, the second outlet pipe 52, the third outlet pipe 53, and the fourth outlet pipe 54. The first outlet pipe 51 is connected to the probe inlet pipe 14, the second outlet pipe 52 is connected to the detection module 40, the third outlet pipe 53 is connected to the gas dilution module 23, and the fourth outlet pipe 54 is connected to the backflush gas inlet 227 of the hollow fiber drying tube 22.

[0074] In the above embodiments, the controller is electrically connected to the movable platform, the drilling component 10, the sample injection module, the sample acquisition module 30, the detection module 40, the gas path control module 50, and the gas supply module 60.

[0075] To effectively control the concentration of organic matter in the gas sample entering the detection module 40 within a suitable range, thus aiding in the accurate detection of organic matter content by the sensor, the detection upper limit value of the detection module 40 is defined as S. max The detection limit is S min The controller is set to detect the target gas concentration signal value S and S in real time by the detection module 40. max and S min The relationship is such that the gas dilution module 23 adjusts the proportion of inert gas in the gas sample so that the target gas concentration signal value S in the gas sample entering the detection module 40 is within a preset range.

[0076] Thus, by controlling the concentration signal S of the target gas entering the detection module 40, the range of the sensor can be extended based on the selection of a low detection limit sensor, avoiding the problems of flat peaks in small-range sensors and insensitivity in large-range sensors. The concentration of the target gas can be dynamically adjusted according to the concentration signal S of the target gas entering the detection module 40, enabling accurate detection of gas sample concentration by a small-range sensor throughout the entire process.

[0077] In an optional embodiment, the gas dilution module 23 is configured to operate when the target gas concentration signal value S ≥ 80%. max or ≤5S min At the same time, adjust the proportion of inert gas in the gas sample;

[0078] Among them, D n =D n-1 ×S / S t D n D is the adjusted dilution factor. n-1 The initial state D is the dilution factor before adjustment. n-1 S is 1. t Let S be the target signal value, where S t It equals the geometric mean of the upper and lower limits, where S is the actual target gas concentration signal value detected by the detection module. Where D... n-1 The initial value is 1, indicating no dilution. The value should be greater than or equal to 1. If the result calculated according to the formula is less than 1, it should be calculated as =1.

[0079] Thus, when the gas sample enters the detection module 40, the concentration of the target gas is detected in real time. When the concentration signal S of the target gas is ≥ 80%, the concentration is determined. max At that time, adjust the dilution factor so that the diluted factor D is... n =D n-1 ×S / S t This reduces the concentration of organic matter and brings it back into the sensor's detection range.

[0080] Meanwhile, as the dilution factor of organic matter increases, the result gain of the detection module 40 is set to be adjusted synchronously according to the dilution factor of the gas sample by the gas dilution module 23;

[0081] Among them, G n =D n G n The result gain of the adjusted detection module 40.

[0082] Thus, based on the concentration changes of organic matter within the sensor's detection range, the dilution factor of the organic matter is adjusted in real time, and the gain of the detection module 40 is also adjusted to ensure that the concentration of organic matter remains below the sensor's detection limit. This guarantees detection sensitivity and prevents the occurrence of a flat-top peak due to excessively large concentration peaks. Figure 3 As shown, the gas dilution module 23 includes a Y-shaped pipe 231, which includes a first input pipe 232, a second input pipe 233, and an output pipe 234. The first input pipe 232 is equipped with a first flow valve 235 and an exhaust pipe 237, and the second input pipe 233 is equipped with a second flow valve 236.

[0083] Thus, when a gas sample containing organic matter enters the Y-shaped pipe 231 from the first input pipe 232, the proportion of the gas sample entering the output pipe 234 can be controlled by the first flow valve 235, which determines the content of organic matter entering the output pipe 234. The proportion of inert gas entering the output pipe 234 can be controlled by the second input pipe 233, which determines the dilution factor of the gas sample.

[0084] Specifically, when the air intake ratio of the first input pipe 232 and the second input pipe 233 is 2:8, the dilution factor of the gas sample is 5 times.

[0085] It should be particularly noted that when the gas intake ratio of the first input pipe 232 and the second input pipe 233 is 1:0, the dilution factor is 1, i.e., no dilution. Specifically, the first input pipe 232 is connected to the probe outlet pipe 201 to receive the gas sample entering through it. The first flow valve 235 controls the flow of the first portion of the gas sample into the output pipe 234 and the second portion into the exhaust pipe 237. The second input pipe 233 is connected to the outlet of the distribution valve, and the second flow valve 236 controls the flow rate of the inert gas entering the second input pipe 233.

[0086] Furthermore, the controller is configured to adjust the opening of the second flow valve 236 and the first flow valve 235 according to the target dilution ratio of the inert gas in the gas sample, so that the gas flow of the first flow meter 21 and the second flow meter 24 are consistent.

[0087] In this way, by controlling the dilution ratio of the sample gas, the intake volume before dilution and the output volume after dilution are also balanced to ensure that the gas flow rate is the same, so as to avoid inaccurate test results caused by changes in flow rate.

[0088] In a specific embodiment, the initial dilution factor is 1. When the result calculated according to the formula is less than 1, it should be calculated as =1, that is, the air intake of the first input pipe 232 is 100% of the total flow rate, and the air intake of the second input pipe 233 is 0%.

[0089] Optionally, in the initial state, Dn-1 = 1, Gn = 1, and the sensor's range is 0 to Cmax (corresponding to a signal range of 10000 to 500000).

[0090] When the concentration rises and triggers the first adjustment, the detection signal S reaches 400000 (80% of Smax), Dn = Dn-1 × S / St = 1 × 400000 / 70711 ≈ 5.66, the dilution factor Dn ≈ 5.66, and the gain Gn = 5.66, meaning the gas sample is diluted 5.66 times. The air flow rate of the first input tube 232 and the second input tube 233 is redistributed, and the detection signal drops to 70711 (within the safe range). After gain compensation, the output concentration is correct. At this time, the processable concentration is ≈ 5.66 × Cmax (500000), while the signal remains at 70711, which is much smaller than the upper limit of the signal.

[0091] Furthermore, as the actual concentration continued to increase, the diluted signal rose from 70711 to 400000 (triggered again). The current Dn-1≈5.66, the new Dn=5.66×400000 / 70711≈5.66×5.66≈32.0, the updated Dn≈32.0, Gn=32.0, the signal dropped to 70711, and the treatable concentration≈32.0×Cmax.

[0092] As mentioned above, this method can expand the measurement range and avoid flat-top peaks.

[0093] {Example 2}

[0094] A second aspect of this invention provides a technical solution: a mobile drilling-while-drilling soil gas detection method with a wide concentration range, using the aforementioned mobile drilling-while-drilling soil gas detection system, comprising the following steps:

[0095] Step 1: Pipeline cleaning. Inert gas at a predetermined flow rate is introduced into the injection module. The signal value is detected by the detection module 40. If the signal value change is less than the preset value within a predetermined period, the pipeline cleaning is completed.

[0096] Step 2: Calibrate the detection module 40. Introduce external standard gas into the injection module at a constant flow rate. If the change in the signal value of the detection module 40 within a predetermined time is less than the preset value, and the deviation of the maximum signal value from the standard value is less than the preset value, then the detection module 40 meets the usage requirements.

[0097] In step 2, the standard gas should be introduced directly into the detection module 40, without passing through the long pipeline of the sample injection module, to avoid contamination residue in the pipeline.

[0098] Step 3: System calibration. Use a standard solution to calibrate the system on the selective permeable membrane structure 12 of the drilling detection probe, record the peak elution of the detection module 40, and compare it with the standard spectrum, including the peak elution time and maximum peak height parameters. If the preset deviation is not exceeded, the system calibration is completed.

[0099] Step 4: Drill at the target location, assemble the extension probe, and control the probe to drill using a direct-push drilling rig. After each predetermined depth of drilling, allow the sample to remain in place for 40 seconds after it has been transferred from the selective permeation membrane to the detection module before continuing to drill.

[0100] Step 5: After drilling to the predetermined depth, remove the probe rod and probe in sequence, and then perform the system calibration in Step 3. If the requirements are met, the test ends.

[0101] In step 4, the gas sample collection and detection at the predetermined depth includes the following steps:

[0102] Step 41: Purge the gas sample collection chamber 11 with inert gas and introduce it into the sample injection module;

[0103] Step 42: Dehumidify the gas sample entering the injection module;

[0104] Step 43: The dehumidified gas sample is tested by the detection module 40;

[0105] Among them, when the target gas concentration signal value S detected by the detection module 40 reaches 80%S max If this occurs, drilling should be stopped immediately, the dilution factor adjusted, and the result gain adjusted simultaneously; if the target gas concentration signal value S is less than 5 times S min If the situation worsens, drilling should be stopped immediately, the dilution factor adjusted, and the result gain adjusted simultaneously. If the dilution factor has been adjusted to 1 and cannot be diluted further, drilling should proceed normally.

[0106] The dilution factor and the resulting gain are adjusted according to the following formula:

[0107] D n =D n-1 ×S / S t ;

[0108] G n =D n ;

[0109] Where S is the target gas concentration signal value actually detected by the detection module 40, and D n D is the adjusted dilution factor. n-1 The initial state D is the dilution factor before adjustment. n-1 =1, D n-1 The maximum value is also 1, G n To adjust the gain of the results from the detection module 40, S t S is the target signal value. t It is the geometric mean of the upper and lower limits.

[0110] Furthermore, step 4 also includes a gas sample storage step, in which the gas sample collection chamber 11 is purged into the sample introduction module and stored through an independent gas bag in the sample introduction module. This not only enables real-time detection but also allows for the collection and storage of gas samples from the target depth layer through an independent gas bag, enabling higher-precision detection in the laboratory.

[0111] In a specific embodiment, the specific detection method is as follows:

[0112] (1) Using the mobile soil gas detection system described above, the equipment is moved to the designated location using a mobile platform.

[0113] (2) After arriving at the designated location, start the equipment, connect each module, and turn on the gas supply module, gas path control module, sample injection module (the sample injection module is optional and can be turned on when needed), detection module, data acquisition system and computer terminal in sequence.

[0114] (3) Quality control before implementation:

[0115] Pipeline aging and baseline calibration: The aging of the circuit and detector is accelerated by heating the gas sample collection chamber 11 with the heating element 13 (resistance wire) and increasing the carrier gas flow rate, thus eliminating interference from residual contaminants. During the equipment aging stage, the gas flow rate at the probe outlet is increased to 150 mL / min, the temperature of the gas sample collection chamber 11 is increased to 150℃, and the resistance wire temperature is increased to 100℃. After aging for 5 minutes, if the change in the signal values ​​of all detectors is less than 8% within 20–50 seconds (i.e., the time it takes for the sample to enter the detection module 40 from the selective permeation membrane window and generate detection data), it indicates that the residual contaminants have been basically removed, and the aging process ends at this point.

[0116] Reduce the temperature of the metal heating chamber to 80-120℃, the resistance wire temperature to 40-80℃, and the gas flow rate at the probe to 30-50 ml / min. After the temperature and gas flow rate at the probe have reached the preset values ​​for 5 minutes, if the peak value change of all detector signals is less than 5% within 20-50 seconds, it indicates that the baseline is basically stable, and the next step can be performed.

[0117] Calibration of Detection Module 40's Detection Capability: The detection capability of Detection Module 40 is crucial for the application of drilling inspection equipment. During system calibration, the conversion from liquid to gas phase has significant uncertainty, and the sample acquisition through the selective permeation membrane window has a certain degree of randomness, which may lead to the failure to detect insufficient detector capability. Therefore, separate calibration of the detector's detection capability is required. At the gas sampling end of Detection Module 40, external standard gas is introduced at a constant flow rate, and the detection data of Detection Module 40 is recorded. The maximum signal value and signal variation are examined. If the variation range of all signal values ​​of Detection Module 40 within a certain period is less than 4%, and the deviation of the maximum signal value from the standard value is less than 5%, it indicates that Detection Module 40 meets the usage requirements.

[0118] The standard gas may contain one or more factors, but it must be ensured that the introduced standard gas can be detected by all detection modules 40.

[0119] System calibration: Simulate the underground environment and use standard solutions to calibrate the system at the selective permeation membrane window. Ensure that the time the standard solution is placed at the selective permeation membrane window is consistent with the time it was placed when the standard spectrum library was established, ensure that the volume of the standard solution is consistent, record the peak elution, and compare it with the standard spectrum, including peak elution time and maximum peak height parameters.

[0120] Ensure that the flow rate, calibration solution and concentration, and the duration of solution inversion within the selective permeation membrane window are consistent with the standard spectral library (i.e., the spectrum generated from the response test of the calibration solution completed before the equipment arrives). Differences in detection results caused by variations in the initial calibration solution temperature and ambient temperature should also be considered. The peak elution time error should be less than 4%, and the maximum peak height error should be 8% + E.

[0121] E=α*|Δ air |*(T0 / T bp ) k 1+β*|Δ liquid |(T0 / T bp ) k 2

[0122] α and β are the weighting coefficients for changes in atmospheric temperature and calibration liquid temperature, respectively, used to adjust the degree of influence of changes in atmospheric temperature and liquid temperature on the error.

[0123] k1 and k2 are the pollutant boiling point influence coefficients, used to adjust the weight of the boiling point's influence on temperature changes.

[0124] E represents the error deviation value, indicating the error deviation caused by changes in the boiling point and temperature of contaminants during the calibration process.

[0125] |Δ air | represents the difference between the atmospheric temperature at the time the standard spectral library was established and the temperature at the time of actual detection, |Δ liquid| represents the difference between the standard solution temperature when the standard spectral library was established and the temperature during actual detection.

[0126] T bp The unit is the boiling point of the pollutant (°C, which must be consistent with T0). Organic pollutants with a boiling point below 40°C should not be used as calibration liquids.

[0127] T0 is the reference boiling point threshold (generally taken as 180-220℃).

[0128] For example: when the standard spectral library was established, the atmospheric temperature was 25℃ and the standard solution temperature was 20℃. During actual detection, the temperature was 30℃, the standard solution temperature was 22℃, α was 0.05, β was 0.11, k1 was 1.5, k2 was 2, T0 was 200℃, and T... bp The corresponding |Δ air | and |Δ liquid They are 5 and 2 respectively.

[0129] E = 0.05 * 5 * (200 / 83.5) 1.5 +0.11*2*(200 / 83.5) 2 =0.93 + 1.26 = 2.19%

[0130] Under these conditions, the maximum peak height error is 8% + E = 8% + 2.19% = 10.19%.

[0131] The standard solution is generally a benzene series compound or a halogenated hydrocarbon, with a concentration between 1 and 100 ppm and a boiling point between 40 and 150 °C. If it exceeds the error range, it needs to be stabilized and retested until it passes the deviation calibration.

[0132] (4) Assemble the extension probe according to the drilling depth requirements, connect the extension probes that meet the drilling depth requirements to the measuring line, drill in sequence, and monitor the whole process. The monitoring content includes: drilling speed, system pressure, and temperature.

[0133] ① Drilling speed control: The drilling speed should not exceed 2cm / s, and uniform drilling should be the main method. After drilling 30-50cm, the sample should be paused to allow time for transfer from the selective permeation membrane to the detection module before continuing drilling.

[0134] ②System pipeline pressure control: The system pressure should remain basically stable during drilling. If the change is greater than 4%, or if there is air leakage or blockage in the surface pipeline, drilling should be stopped immediately, and drilling should be restarted after troubleshooting.

[0135] ③ Temperature control: Temperature affects the volatilization of organic pollutants. When the actual heating temperature of the selective osmosis membrane does not match the preset value, the drilling speed should be adjusted appropriately. Specifically:

[0136] When 10>ΔT ≥5, V n =V n-1 -a%Δ T When 20 > Δ T ≥10, V n =V n-1 -b%Δ T If Δ T If the value is ≥20, stop drilling immediately and wait for Δ T <5. Resume drilling.

[0137] Among them, |Δ T | represents the absolute value of the difference between the actual temperature and the preset temperature; a and b are drilling speed adjustment coefficients, V n and V n-1 These are the adjusted drilling speed and the previous drilling speed, respectively, where 2cm / s≥V n ≥0cm / s.

[0138] (5) When drilling reaches the required sampling depth, switch to sample acquisition mode, close the valve of the probe outlet gas pipe 201 in the sample injection module flowing into the detection module 40, open the low-temperature storage box of the sample acquisition module in advance, maintain the temperature inside the box at less than or equal to 4℃, open the valve of the probe outlet gas pipe 201 in the sample injection module flowing into the sample acquisition module 30, and collect gas samples into the gas bag. After the gas bag load is reached, sampling can continue to another gas bag. After completion, mark the location, depth, and other information on the gas bag. Close the valve of the probe outlet gas pipe 201 in the sample injection module flowing into the sample acquisition module 30, and simultaneously open the valve of the probe outlet gas pipe 201 in the sample injection system flowing into the detection module 40. After waiting for the sample pipeline transmission time, drilling and detection can continue.

[0139] (6) Gas dilution module operation: When the detector signal value reaches 80% of the maximum limit, drilling should be stopped immediately, the dilution factor should be adjusted, and the result gain should be adjusted synchronously; when the actual detected signal value is less than 5 times the detection limit, drilling should be stopped immediately, the dilution factor should be adjusted, and the result gain should be adjusted synchronously, as follows:

[0140] When the target gas concentration signal value S detected by the detection module 40 reaches 80% max If this occurs, drilling should be stopped immediately, the dilution factor adjusted, and the result gain adjusted simultaneously; if the target gas concentration signal value S is less than 5 times S min If this occurs, drilling should be stopped immediately, the dilution factor adjusted, and the result gain adjusted simultaneously.

[0141] The dilution factor and the resulting gain are adjusted according to the following formula:

[0142] D n =D n-1 ×S / S t ;

[0143] G n =D n ;

[0144] Where S is the target gas concentration signal value actually detected by the detection module 40, and D n D is the adjusted dilution factor. n-1 The initial state D is the dilution factor before adjustment. n-1 =1, D n-1 The maximum value is also 1, G n To adjust the gain of the results from the detection module 40, S t S is the target signal value. t It is the geometric mean of the upper and lower limits.

[0145] (7) After drilling to the predetermined depth, stop the time for the sample to be transferred from the selective permeation membrane to the detector, take out the probe and drill bit in sequence, and perform system calibration in the manner of (3). If the requirements are met, the test can be ended; if the deviation is large, it needs to be stabilized and then retested; if the deviation is still too large after retesting, the entire equipment should be overhauled. After the overhaul is completed, the point should be retested according to the steps (1) to (7) above.

[0146] In conjunction with the above embodiments, in order to address the problem of insufficient quality control in traditional membrane interface detection technology or drilling detection technology, as shown in step (3), baseline calibration, detector detection capability calibration, and system calibration methods are introduced before and after implementation. During implementation, drilling speed, temperature, and system pressure are monitored in real time and adjusted collaboratively to improve the overall reliability of the equipment application.

[0147] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A mobile soil gas detection system while drilling, characterized in that, include: A mobile platform, including a loading platform and drive wheels connected to the loading platform; The drilling component (10) is mounted on the loading platform. The drilling component (10) includes a drilling detection probe and a push drilling rig that drives the drilling detection probe to drill and pull it out. The drilling detection probe is configured to be driven by the push drilling rig to drill into a soil layer of a predetermined depth and collect gas samples of the current soil layer. A sample introduction module, connected to the drilling detection probe, is used to process the gas sample entering the sample introduction module; The sample acquisition module (30) is connected to the sample injection module and is used to collect and save the gas sample entering the sample injection module; The detection module (40) is connected to the injection module and is used to detect the type and concentration of the target gas in the gas sample in the injection module in real time. The gas path control module (50) includes a distribution valve, which includes two inlet ends and multiple outlet ends; A gas supply module (60) is connected to the distribution valve and is used to supply hydrogen and inert gas to the two inlet ends of the distribution valve respectively. The multiple outlet ends of the distribution valve supply the target type and flow rate of gas to the drilling component (10), the sampling module and the detection module (40) respectively. The controller is electrically connected to the movable platform, drilling component (10), sample injection module, sample acquisition module (30), detection module (40), gas path control module (50) and gas supply module (60); The sample injection module includes a gas dilution module (23). A first flow meter (21) is provided upstream of the gas dilution module (23), and a second flow meter (24) is provided downstream of the gas dilution module (23). The gas dilution module (23) is used to add a predetermined amount of inert gas to the gas sample and keep the gas flow rate through the first flow meter (21) and the second flow meter (24) the same. The detection upper limit value of the detection module (40) is defined as S. max The detection limit is S min The controller is configured to detect the target gas concentration signal value S and S in real time by the detection module (40). max and S min The relationship between the gas dilution module (23) and the gas dilution module (23) is controlled to adjust the proportion of inert gas in the gas sample so that the target gas concentration signal value S in the gas sample entering the detection module (40) is within a preset range. The gas dilution module (23) is set to operate when the target gas concentration signal value S ≥ 80%S max or ≤5S min At the same time, adjust the proportion of inert gas in the gas sample; Among them, D n =D n -1 ×S / S t D n D is the adjusted dilution factor. n -1 The initial dilution factor is D before adjustment. n -1 S is 1. t S is the target signal value. t It is the geometric mean of the upper and lower limits; The result gain of the detection module (40) is set to be adjusted synchronously according to the dilution factor of the gas sample by the gas dilution module (23); Among them, G n =D n G n The result gain of the adjusted detection module (40); The gas dilution module (23) includes a Y-shaped pipe (231), which includes a first input pipe (232), a second input pipe (233), and an output pipe (234). The first input pipe (232) is provided with a first flow valve (235) and an exhaust pipe (237), and the second input pipe (233) is provided with a second flow valve (236). The first input pipe (232) is connected to the probe outlet pipe (15) to receive the gas sample entering through the probe outlet pipe (15). The first flow valve (235) is used to control the first part of the gas sample to enter the output pipe (234) and the second part of the gas sample to enter the exhaust pipe (237). The second input pipe (233) is connected to the outlet end of the distribution valve. The second flow valve (236) is used to control the flow rate of inert gas entering the second input pipe (233). A hollow fiber drying tube (22) is provided between the first flow meter (21) and the gas dilution module (23). The hollow fiber drying tube (22) includes an insulation shell (221) and an outer tube (222) and an inner tube (223) disposed in the insulation shell (221). The first end of the inner tube (223) is connected to the output end of the first flow meter (21), and the second end is connected to the input end of the gas dilution module (23). A separation chamber is formed between the outer tube (222) and the inner tube (223). The outer tube (222) is provided with a backflush gas inlet (227) and a backflush gas outlet (226). The backflush gas inlet (227) is connected to the outlet end of the distribution valve, so that flowing inert gas enters the separation chamber. The inner tube (223) includes a hollow fiber membrane tube for water vapor to pass through.

2. The mobile drilling soil gas detection system according to claim 1, characterized in that, The controller is configured to adjust the opening of the second flow valve (236) and the first flow valve (235) according to the target dilution ratio of the inert gas in the gas sample, so that the gas flow of the first flow meter (21) and the second flow meter (24) are consistent.

3. The mobile drilling soil gas detection system according to claim 1, characterized in that, The drilling detection probe includes a probe body, a gas sampling chamber (11), and a selective permeation membrane structure (12) disposed outside the gas sampling chamber (11). The probe body is also provided with a probe inlet pipe (14) and a probe outlet pipe (15). The probe inlet pipe (14) and the probe outlet pipe (15) are both connected to the gas sampling chamber (11). The probe body is also provided with a heating component (13) for heating the gas sampling chamber (11).

4. The mobile drilling soil gas detection system according to claim 3, characterized in that, The direct-push drilling rig is used to control the drilling speed of the probe body, wherein the controller controls the drilling speed of the direct-push drilling rig based on the difference between the real-time temperature of the selective permeable membrane structure (12) and a preset value.

5. A mobile drilling method for detecting soil gas over a wide concentration range, characterized in that, Using the mobile drilling soil gas detection system according to any one of claims 1-4 includes the following steps: Step 1: Pipeline cleaning. Inert gas at a predetermined flow rate is introduced into the injection module. The signal value is detected by the detection module (40). If the signal value change is less than the preset value within the predetermined period, the pipeline cleaning is completed. Step 2: Calibrate the detection module (40). Introduce external standard gas into the injection module at a constant flow rate. If the signal value of the detection module (40) changes less than the preset value within a predetermined time, and the maximum signal value deviation is less than the standard value, then the detection module (40) meets the usage requirements. Step 3: System calibration. Use the standard solution to calibrate the system on the selective permeable membrane structure (12) of the drilling detection probe, record the peak elution of the detection module (40), and compare it with the standard spectrum, including the peak elution time and the maximum peak height parameter. If it does not exceed the preset deviation, the system calibration is completed. Step 4: Drill the target point, assemble the extension probe, and control the probe to drill through the direct-push drilling machine. After each predetermined depth of drilling, the sample is left to transfer from the selective permeation membrane to the detection module (40) for a period of time before drilling continues. Step 5: After drilling to the predetermined depth, remove the probe rod and probe in sequence, and then perform the system calibration in Step 3. If the requirements are met, the test ends. In step 4, the collection and detection of gas samples at a predetermined depth includes the following steps: Step 41: The pollutants collected in the gas sample collection chamber (11) are purged into the sample introduction module by inert gas; Step 42: Dehumidify the gas sample entering the injection module; Step 43: The dehumidified gas sample is detected by the detection module (40) and the detection concentration signal of the current gas sample is obtained; Among them, when the target gas concentration signal value S detected by the detection module (40) reaches 80%S max If drilling is interrupted, the dilution factor should be adjusted, and the gain of the result should be adjusted simultaneously; if the target gas concentration signal value S is less than 5 times S min If the situation worsens, immediately stop drilling, adjust the dilution factor, and simultaneously adjust the result gain. If the dilution factor has been adjusted to 1 and cannot be diluted further, then continue drilling normally. The dilution factor and the resulting gain are adjusted according to the following formula: D n =D n -1 ×S / S t ; G n =D n ; Where S is the target gas concentration signal value actually detected by the detection module (40), and D n D is the adjusted dilution factor. n -1 The initial dilution factor is D before adjustment. n -1 G is 1. n To adjust the result gain of the detection module (40), S t S is the target signal value. t It is the geometric mean of the upper and lower limits.

6. The mobile drilling-while-drilling soil gas wide concentration range detection method according to claim 5, characterized in that, Step 4 also includes a gas sample collection and storage step, in which the sample in the gas sample collection chamber (11) is purged into the sample injection module and stored through an independent gas bag in the sample injection module.

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