A soil volatile organic compound detection system and method

Abstract

The application relates to the field of soil pollution detection, and discloses a detection system and a detection method for volatile organic compounds in soil. The first detection rod and the second detection rod are arranged to detect the gas in the soil on the spot, which has very high timeliness compared with the prior art, that is, the detection result can be quickly obtained, which provides a reference for the removal of the volatile organic compounds in the soil. The first detection rod performs preliminary detection to preliminarily determine whether the volatile organic compound gas exists at the sampling position, and the outer pipe is used to introduce the carrier gas into the inner pipe, which plays a role in dredging the inner pipe and also assists in blowing the volatile organic compound gas carried in the sampling soil, improves the sensitivity of detection, promotes continuous operation, quickly determines the depth of secondary detection, and combines the arrangement of the second detection rod to blow the carrier gas into the second detection rod, promotes the volatile organic compound gas to flow to the second detection rod, improves the accuracy of gas concentration detection, and reduces the generation of the plugging problem.

Description

Technical Field

[0001] This invention relates to the field of soil pollution detection, and more specifically to a detection system and method for volatile organic compounds in soil. Background Technology

[0002] Volatile organic compounds (VOCs) refer to organic matter with a saturated vapor pressure exceeding 70.91 P at room temperature or a boiling point below 260°C. They are the most common pollutants emitted by industries such as petroleum, chemical, pharmaceutical, printing, building materials, and spraying. VOCs can exist in the soil in either gaseous or liquid phases. In general soil, soil gas mainly contains nitrogen, oxygen, and carbon dioxide. In some underground environments, certain polluting gases can diffuse into the soil gas, such as those from landfills, mining, and oil. Soil gases containing toxic and harmful substances can diffuse into buildings, thus affecting human health.

[0003] In the detection of volatile organic compounds (VOCs) at contaminated sites, thin-walled soil samplers are typically used to collect undisturbed soil samples, which are then sealed, preserved, and transported to the laboratory for testing. However, in practice, soil excavation and disturbance can easily lead to the volatilization of soil gases, resulting in significant differences in test results. Furthermore, the process of sampling and transporting soil to the laboratory for testing is time-consuming. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a detection system for volatile organic compounds in soil to overcome the above-mentioned defects in the existing technology.

[0005] To achieve the first objective of this invention, the present invention provides the following technical solution:

[0006] A soil volatile organic compound detection system includes a support frame on which are mounted a...

[0007] The first detection rod includes an inner tube and an outer tube, the outer tube being sleeved over the inner tube. One end of the inner tube has a flow port, and an air inlet connects the inner and outer tubes. An air supply device is provided outside the outer tube to introduce carrier gas into it.

[0008] The second detection rod is inclined to the first detection rod. When the lower end of the second detection rod approaches the lower end of the first detection rod, the first detection rod outputs carrier gas to the second detection rod.

[0009] The drive assembly is used to drive the first detection rod and the second detection rod to descend.

[0010] A gas detection component is connected to an inner tube and a second detection rod, respectively. The gas detection component extracts gas from the inner tube or the second detection rod to obtain the concentration of volatile gases.

[0011] In this invention, preferably, the detection system includes

[0012] An environment acquisition module acquires environmental parameters to define them as environmental data, including current temperature, wind speed, and historical precipitation.

[0013] The soil information acquisition module captures images of the soil to define them as soil image information, and extracts soil data from the soil image information. The soil data includes soil particle data and soil color data. The soil particle data reflects the average size of the soil surface particles, and the soil color data reflects the color of the soil surface.

[0014] The control module controls the drive assembly to drive the first detection rod downwards at a preset downward speed. The gas supply device continuously supplies carrier gas into the outer pipe, and the gas detection unit determines the presence or absence of volatile gas in the inner pipe. When volatile gas is detected, the gas detection unit acquires the gas concentration to obtain a gas pre-detection concentration and generates a depth detection signal. It then controls the gas supply device and drive assembly to stop operating. The gas pre-detection concentration reflects the actual concentration of volatile gas at the flow port position on the first detection rod.

[0015] The depth measurement module acquires depth detection signals and depth data, which reflects the distance between the flow port of the first detection rod and the ground surface.

[0016] The processing module acquires the environmental data, soil data, gas pre-detection concentration, and depth data, inputs them into a trained depth-concentration model to obtain a predicted depth value, and generates a depth signal to the control module. The predicted depth value reflects the depth at which the gas concentration theoretically reaches its maximum value. The control module instructs the drive component to drive the first and second detection rods down to the predicted depth value position. Then, the gas supply device supplies gas so that the carrier gas reaches the second detection rod through the outer pipe. The gas detection unit collects the volatile gas concentration of the second detection rod to define it as the actual measured concentration.

[0017] In this invention, preferably, a baffle assembly is provided inside the first detection rod, the baffle assembly including a sensing element, a fixing element, a sliding element, and a transmission slider.

[0018] The sliding element is slidably connected to the inner wall of the outer tube. The transmission slider is annular and slidably connected between the inner and outer tubes. The transmission slider slides within the outer tube due to the pressure difference on both sides. The transmission slider is fixedly connected to the sliding part to drive the sliding element to slide synchronously.

[0019] The fixing member is fixedly connected to the outer tube and is used to restrict the movement of the transmission slider. When the lower end of the second detection rod approaches the lower end of the first detection rod, the sensing element is triggered to cause the fixing member to release the transmission slider.

[0020] The sliding member extends through one end of the outer tube near the flow port. The sliding member includes a baffle portion, a flexible support portion, and a sliding portion. The flexible support portion is bendable and connected between the baffle portion and the sliding portion. When the sliding portion slides inside the outer tube, the sliding portion can push the baffle portion to protrude outside the outer tube to guide the carrier gas to the second detection rod.

[0021] In this invention, preferably, the transmission slider is configured as a rubber elastic element, which has a pressure relief hole. When the pressure relief hole is compressed along the hole diameter direction, the rubber elastic element can generate elastic deformation to change the flow diameter of the pressure relief hole.

[0022] An expansion hole group is provided along the length direction inside the outer tube. The expansion hole group corresponds one-to-one with the pressure relief hole. The expansion hole group includes several expansion hole rods. The expansion hole rods in the same expansion hole group are distributed in a conical shape. When the transmission slider slides towards the flow port, the compression between the expansion hole rod and the pressure relief hole is reduced to reduce the flow hole diameter of the pressure relief hole.

[0023] In this invention, preferably, the bracket includes a first support and a second support, the distance between the first support and the second support is adjustable, the first detection rod is slidably mounted on the first support, and the second detection rod is slidably mounted on the second support.

[0024] The drive assembly includes a first motor, a first drive gear, and a first drive collar mounted on a first support. The first drive gear and the first drive collar are meshed with each other and are both rotatably connected to the first support. The output shaft of the first motor is coaxially and fixedly connected to the first drive gear. The first drive collar is sleeved on the outside of the first detection rod, and the first drive collar and the first detection rod are threaded together. When the first drive collar rotates, the first detection rod can slide along its own length.

[0025] The drive assembly includes a second motor, a second drive gear, and a second drive collar mounted on a second support. The second drive gear and the second drive collar mesh with each other and are rotatably connected to the second support. The second motor drives the second drive gear to rotate. The second drive collar is sleeved on the outside of the second detection rod, and the second drive collar and the second detection rod are threaded together. When the second drive collar rotates, the second detection rod can slide along its own length.

[0026] In this invention, preferably, the processing module is configured with an operation judgment strategy. Specifically, the operation judgment strategy is to acquire and judge whether the predicted depth value conforms to a preset detection interval. If the predicted detection depth is less than the lower limit of the preset detection interval, a first termination signal is generated to indicate that the depth is too shallow. If the predicted detection depth conforms to the lower limit of the preset detection interval, a second detection signal is generated to the control module. If the predicted detection depth exceeds the upper limit of the preset detection interval, a second termination signal is generated to indicate that the depth exceeds the limit.

[0027] In this invention, preferably, the processing module is configured with a concentration conversion strategy to convert the actual measured concentration into a target concentration. Specifically, the concentration conversion strategy takes a preset waiting time after the sensor is triggered as the starting point of the acquisition time, and a preset measurement time as the time span. It acquires the average gas supply speed of the gas supply device, the gas extraction speed of the gas detection component, and the average measured concentration of the gas detection unit. The average measured concentration represents the mean of the actual measured concentration. The target concentration is obtained by converting the average gas supply speed, the gas extraction speed, and the average measured concentration.

[0028] In this invention, preferably, the detection system is configured with a model update strategy, which specifically includes: obtaining the theoretical concentration extreme value based on the depth concentration model, the theoretical concentration extreme value reflecting the gas concentration at the theoretically predicted depth value position; comparing the actual measured concentration with the theoretical concentration extreme value; if the difference between the two is greater than a preset difference, then this data is discarded and a re-detection is prompted; if the difference between the two is less than or equal to the preset difference, then the actual measured concentration is taken as the new theoretical concentration extreme value and added as a set of data to the training set of the depth concentration model.

[0029] In this invention, preferably, the soil information acquisition module is configured with a particle data extraction strategy, specifically including: dividing the soil image information into several rectangular blocks and acquiring the grayscale value of each rectangular block; calculating the average grayscale value of the rectangular blocks; comparing the grayscale value of each rectangular block with the average grayscale value; if the grayscale value is greater than the average grayscale value, assigning a first grayscale value to the rectangular block; if the grayscale value is less than or equal to the average grayscale value, assigning a second grayscale value to the rectangular block; the first grayscale value being greater than the average grayscale value and the average grayscale value being greater than the second grayscale value, thereby achieving binarization of the soil image information; merging rectangular blocks with the same grayscale value into regions of the same color; calculating the number of regions of the same color with the first grayscale value and the sum of the areas of each region of the same color to obtain the average area size of the region of the same color; the area size of the region of the same color reflects the average size of soil particles in the soil image information.

[0030] To achieve the second objective of this invention, the present invention provides the following technical solution:

[0031] A method for detecting volatile organic compounds (VOCs) in soil, and a system for detecting VOCs in soil, include an environmental acquisition module, a soil information acquisition module, a control module, a depth measurement module, a processing module, and a support. The support is equipped with a first detection rod, a second detection rod, a drive assembly, and a gas detection assembly. The first detection rod includes an inner tube and an outer tube, with the outer tube sleeved over the inner tube. One end of the inner tube has a flow port, and an air inlet connects the inner and outer tubes. A gas supply device is provided outside the outer tube to introduce carrier gas. The second and first detection rods are inclined together. When the lower end of the second detection rod approaches the lower end of the first detection rod, the first detection rod outputs carrier gas to the second detection rod. The drive assembly drives the first and second detection rods downwards. The gas detection assembly is connected to both the inner tube and the second detection rod, and extracts gas from either the inner tube or the second detection rod to obtain the concentration of volatile gases.

[0032] The detection method includes:

[0033] Step one: A support frame is erected on the ground. The soil information acquisition module captures images of the soil to define as soil image information, and extracts soil data from the soil image information. The soil data includes soil particle data and soil color data. The soil particle data reflects the average size of the soil surface particles, and the soil color data reflects the color of the soil surface. The environmental acquisition module acquires environmental parameters to define as environmental data. The environmental parameters include current temperature, wind speed, and historical precipitation.

[0034] Step two: The control module controls the drive assembly to drive the first detection rod downwards at a preset downward speed. The gas supply device continuously supplies carrier gas into the outer pipe. The carrier gas passes through the outer pipe, the inlet, and the inner pipe, reaching the gas detection assembly. The gas detection unit determines the presence or absence of volatile gas in the inner pipe. When volatile gas is detected, the gas detection unit acquires the gas concentration to obtain a gas pre-detection concentration and generates a depth detection signal. It then controls the gas supply device and drive assembly to stop working. The gas pre-detection concentration reflects the actual concentration of volatile gas at the flow port position of the first detection rod.

[0035] The depth measurement module acquires a depth detection signal and acquires depth data, which reflects the distance between the flow port of the first detection rod and the ground surface.

[0036] Step 3: The processing module acquires the environmental data, soil data, gas pre-detection concentration and depth data and inputs them into the trained depth concentration model to obtain the predicted depth value and generate a depth signal to the control module. The predicted depth value reflects the depth at which the gas concentration theoretically reaches its maximum value.

[0037] Step four: The control module receives the depth signal and drives the first and second detection rods to descend to the predicted depth value position. Then, the gas supply device supplies gas so that the carrier gas reaches the second detection rod through the outer tube. The gas detection unit collects the volatile gas concentration of the second detection rod to define it as the actual measured concentration.

[0038] The beneficial effects of this invention are:

[0039] 1. The present invention uses a first detection rod and a second detection to detect gases in the soil in situ. Compared with the sampling-transportation-laboratory testing method in the prior art, it has a very high timeliness, that is, it can quickly obtain test results and provide a reference for the subsequent removal of volatile organic compounds in the soil.

[0040] 2. This invention uses a first detection rod for initial detection to preliminarily determine whether volatile organic compounds (VOCs) are present at the sampling location. The outer tube introduces carrier gas into the inner tube, which not only clears the inner tube but also helps to expel VOCs carried in the sampled soil, improving detection sensitivity and promoting continuous operation to quickly determine the depth for secondary detection. Combined with the second detection rod, which is a single-layer design with a smaller outer diameter than the first detection rod during its downward movement, this reduces gas overflow. Furthermore, the first detection rod can expel carrier gas into the second detection rod, promoting the flow of VOCs towards it, improving the accuracy of gas concentration detection and reducing blockage problems.

[0041] 3. The present invention uses the baffle assembly to guide the output carrier gas, promoting the flow of the carrier gas towards the second detection rod, thereby improving the accuracy of detection. Furthermore, the baffle does not require an additional drive source; the air supply device can simultaneously achieve both air supply and drive the slider movement. Considering that the extended baffle will be subject to soil compression, the flow diameter of the pressure relief hole is set to vary to improve the driving effect. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the main structure of the present invention;

[0043] Figure 2 This is a partial cross-sectional view of the first detection rod in the first state of the present invention;

[0044] Figure 3 yes Figure 2 A magnified view of a portion of point A in the middle;

[0045] Figure 4 This is a partial cross-sectional view of the first detection rod in the second state in this invention;

[0046] Figure 5 This is the system architecture diagram of the present invention.

[0047] Figure label:

[0048] 1. First detection rod; 101. Flow port; 102. Air inlet; 11. Inner tube; 12. Outer tube; 121. Air supply device; 13. Sliding component; 131. Baffle part; 132. Flexible support part; 133. Sliding part; 14. Transmission slider; 141. Pressure relief hole; 15. Expanding rod; 16. Pull rope; 2. Second detection rod; 31. First support; 311. First motor; 312. First drive gear; 313. First drive collar; 32. Second support; 321. Second motor; 322. Second drive gear; 323. Second drive collar; 4. Gas detection assembly; 41. Gas detection unit; 5. Environmental acquisition module; 6. Soil information acquisition module; 7. Control module; 8. Depth measurement module; 9. Processing module. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0052] Example 1:

[0053] Please also see Figures 1 to 5 This embodiment provides a soil volatile organic compound (VOC) detection system, including a support frame on which a first detection rod 1, a second detection rod 2, a drive assembly, and a gas detection assembly 4 are mounted. The drive assembly is used to drive the first detection rod 1 and the second detection rod 2 downwards. The gas detection assembly 4 includes a gas detection unit 41, which extracts gas to detect the concentration of VOCs.

[0054] First, regarding the support structure, please refer to... Figure 1 The bracket includes a first support 31 and a second support 32. A first detection rod 1 is slidably mounted on the first support 31. A first groove (not shown in the figure) is formed on the outer wall of the first detection rod 1. A first slider (not shown in the figure) is provided inside the first support 31. The first detection rod 1 and the first support 31 are slidably connected through the first groove and the second slider, and the sliding direction of the first detection rod 1 is vertical. A second detection rod 2 is slidably mounted on the second support 32. The connection method between the second detection rod 2 and the second support 32 is the same as above, except that there is an angle between the second detection rod 2 and the first detection rod 1, and the driving direction of the second detection rod 2 is along its own length. The distance between the first support 31 and the second support 32 is adjustable. To facilitate control of the distance between the first detection rod 1 and the second detection rod 2, the first support 31 and the second support 32 are connected by a telescopic rod with a length mark.

[0055] The drive assembly includes a first motor 311, a first drive gear 312, and a first drive collar 313, all mounted on a first support 31. Both the first drive collar 313 and the first drive gear 312 are rotatably connected to the first support 31. The outer periphery of the first drive collar 313 has several continuous first toothed portions, which mesh with each other. The output shaft of the first motor 311 is coaxially and fixedly connected to the first drive gear 312. The first drive collar 313 is sleeved on the outside of the first detection rod 1, and a threaded connection exists between the first drive collar 313 and the first detection rod 1. When the first drive collar 313 rotates, the first detection rod 1 can slide along its own length.

[0056] The drive assembly includes a second motor 321, a second drive gear 322, and a second drive collar 323, both mounted on a second support 32. The second drive gear 322 and the second drive collar 323 are rotatably connected to the second support 32. The second drive collar 323 has several continuous second toothed portions distributed around its periphery, and the second drive gear 322 meshes with these second toothed portions. The second motor 321 drives the second drive gear 322 to rotate. The second drive collar 323 is sleeved on the outside of the second detection rod 2, and is threadedly connected to the second detection rod 2. When the second drive collar 323 rotates, the second detection rod 2 can slide along its own length.

[0057] For the structural details of the first detection rod 1 and the second detection rod 2, please refer to... Figure 2The first detection rod 1 includes an inner tube 11 and an outer tube 12. The outer tube 12 is sleeved outside the inner tube 11. One end of the inner tube 11 has a flow port 101. An air inlet 102 connects the inner tube 11 and the outer tube 12. An air supply device 121 is provided outside the outer tube 12 to introduce carrier gas into the outer tube 12. The second detection rod 2 is inclined to the first detection rod 1. When the lower end of the second detection rod 2 is close to the lower end of the first detection rod 1, the first detection rod 1 outputs carrier gas to the second detection rod 2. The gas detection component 4 is connected to the inner tube 11 and the second detection rod 2 respectively. The gas detection component 4 extracts gas from the inner tube 11 or the second detection rod 2 to obtain the concentration of volatile gases. Inside the first detection rod 1, the carrier gas flows in two ways: first, it flows from the outer tube 12 through the inlet 102 and from the inner tube 11 to the gas detection component 4, where the gas detection device detects the gas flowing out of the first detection rod 1; second, it flows from the outer tube 12 through the inlet 102 and from the flow port 101 of the inner tube 11 into the second detection rod 2, finally reaching the gas detection component 4, where the gas detection device detects the gas flowing out of the second detection rod 2. This method of introducing carrier gas can clear the blockage in the inner tube 11 of the first detection rod 1 or the second detection rod 2, reducing the possibility of blockage, and can also alleviate the problem of gas spillage during sampling. The carrier gas carries the gas to the second detection rod 2, improving the accuracy of gas detection.

[0058] The first detection rod 1 is equipped with a baffle assembly; please refer to [link / reference]. Figures 2 to 4 The baffle assembly includes a sensor, a fixing member, a sliding member 13, and a transmission slider 14. When the lower end of the second detection rod 2 approaches the lower end of the first detection rod 1, the sensor is triggered, causing the fixing member to release the transmission slider 14. Specifically, a proximity switch can be used, for example, a magnet is built into the lower end of the second detection rod 2, and a Hall element is placed at the lower end of the first detection rod 1. When the two are brought close together, the Hall element is triggered, and the fixing member is electrically connected to the sensor, i.e., the Hall element.

[0059] The sliding member 13 is slidably connected to the inner wall of the outer tube 12. The transmission slider 14 is annular and slidably connected between the inner tube 11 and the outer tube 12. The transmission slider 14 slides in the outer tube 12 by relying on the pressure difference on both sides. The transmission slider 14 is fixedly connected to the sliding part 133 to drive the sliding member 13 to slide synchronously. The fixing member is fixedly connected to the outer tube 12 and is used to limit the movement of the transmission slider 14. The sliding member 13 passes through the end of the outer tube 12 near the flow port 101. The sliding member 13 includes a baffle part 131, a flexible support part 132 and a sliding part 133. The flexible support part 132 is bendable and connected between the baffle part 131 and the sliding part 133. When the sliding part 133 slides in the outer tube 12, the sliding part 133 can push the baffle part 131 to protrude out of the outer tube 12 to guide the carrier gas to the second detection rod 2. The fixing component can be set as a telescopic hook. A pull rope 16 is fixedly connected to the side of the transmission slider 14 away from the baffle part 131. That is, when the pull rope 16 is pulled, the baffle part 131 can be retracted and the pull rope 16 is hung on the hook. When the sensor is triggered, the hook is triggered and the pull rope 16 is disengaged from the hook. At this time, the transmission slider 14 is not restricted and slides by relying on the pressure difference, which drives the baffle part 131 to extend.

[0060] Please refer to the details. Figure 3 The transmission slider 14 is configured as a rubber elastic element, and a pressure relief hole 141 is provided on the rubber elastic element. When the pressure relief hole 141 is squeezed along the hole diameter direction, the rubber elastic element can generate elastic deformation to change the flow diameter of the pressure relief hole 141. The change in the flow diameter will change the pressure on both sides. An expansion hole group is provided in the outer tube 12 along the length direction. The expansion hole group corresponds one-to-one with the pressure relief hole 141. The expansion hole group includes several expansion hole rods 15. The expansion hole rods 15 in the same expansion hole group are distributed in a conical shape. When the transmission slider 14 slides towards the flow port 101, the compression between the expansion hole rods 15 and the pressure relief hole 141 is reduced to reduce the flow diameter of the pressure relief hole 141.

[0061] Please see Figure 5The detection system includes an environmental acquisition module 5, a soil information acquisition module 6, a control module 7, a depth measurement module 8, and a processing module 9. The environmental acquisition module 5 acquires environmental parameters to define as environmental data, including current temperature, wind speed, and historical precipitation. The soil information acquisition module 6 captures images of the soil to define as soil image information and extracts soil data from these images. The soil data includes soil particle data and soil color data; the soil particle data reflects the average size of the soil surface particles, and the soil color data reflects the color of the soil surface. The soil information acquisition module 6 is configured with a particle data extraction strategy, specifically including: dividing the soil image information into several rectangular blocks and acquiring the grayscale value of each rectangular block; calculating the average grayscale value of the rectangular blocks; comparing the grayscale value of each rectangular block with the average grayscale value; assigning a first grayscale value to the rectangular block if the grayscale value is greater than the average grayscale value, and assigning a second grayscale value to the rectangular block if the grayscale value is less than or equal to the average grayscale value; and achieving binarization of the soil image information by merging rectangular blocks with the same grayscale value into regions of the same color; calculating the number of regions of the same color with the first grayscale value and the sum of the areas of each region of the same color to obtain the average area of ​​the region of the same color. The area of ​​the region of the same color reflects the average size of the soil particles in the soil image information. The purpose of binarization is to distinguish between dark and bright areas in the soil image information, highlighting the boundaries of soil particles to facilitate the calculation of soil particle size. Soil color data can be obtained by directly selecting multiple points within the soil image information and collecting RGB color values, calculating the mean, excluding the RGB color values ​​of points with large differences, and then recalculating the mean after excluding the points as the soil color data.

[0062] Control module 7 controls the drive assembly to drive the first detection rod 1 downward at a preset downward speed. The gas supply device 121 continuously supplies carrier gas into the outer pipe 12, and the gas detection unit 41 determines the presence or absence of volatile gas in the inner pipe 11. When volatile gas is detected, the gas detection unit 41 acquires the gas concentration to obtain a pre-detection concentration and generates a depth detection signal. It then controls the gas supply device 121 and drive assembly to stop working. The pre-detection concentration reflects the actual concentration of volatile gas at the flow port 101 of the first detection rod 1. Depth measurement module 8 acquires the depth detection signal and depth data, which reflects the distance from the flow port 101 of the first detection rod 1 to the ground surface. The processing module 9 acquires environmental data, soil data, gas pre-detection concentration, and depth data, and inputs them into the trained depth concentration model to obtain a predicted depth value and generate a depth signal to the control module 7. The predicted depth value reflects the depth at which the gas concentration theoretically reaches its maximum value. The control module 7 instructs the drive component to drive the first detection rod 1 and the second detection rod 2 to descend to the predicted depth value position. Then, the gas supply device 121 supplies gas so that the carrier gas reaches the second detection rod 2 through the outer pipe 12. The gas detection unit 41 collects the volatile gas concentration of the second detection rod 2 to define it as the actual measured concentration.

[0063] The processing module 9 is configured with an operation judgment strategy. Specifically, the operation judgment strategy is to obtain and judge whether the predicted depth value meets the preset detection range. If the predicted detection depth is less than the lower limit of the preset detection range, a first termination signal is generated to indicate that the depth is too shallow. If the predicted detection depth meets the lower limit of the preset detection range, a second detection signal is generated to the control module 7. If the predicted detection depth exceeds the upper limit of the preset detection range, a second termination signal is generated to indicate that the depth exceeds the limit.

[0064] The processing module 9 is configured with a concentration conversion strategy to convert the actual measured concentration into the target concentration. Specifically, the concentration conversion strategy takes the preset waiting time after the sensor is triggered as the starting point of the acquisition time, the preset measurement time as the time span, and collects the average gas supply speed of the gas supply device 121, the gas extraction speed of the gas detection component 4, and the average measured concentration of the gas detection unit 41. The average measured concentration represents the mean of the actual measured concentration. The target concentration is obtained by converting the average gas supply speed, the gas extraction speed, and the average measured concentration.

[0065] The detection system is equipped with a model update strategy, which specifically includes: obtaining the theoretical concentration extreme value based on the depth concentration model. The theoretical concentration extreme value reflects the gas concentration at the theoretically predicted depth value position. The actual measured concentration is compared with the theoretical concentration extreme value. If the difference between the two is greater than the preset difference, the data is removed and a re-detection is prompted. If the difference between the two is less than or equal to the preset difference, the actual measured concentration is taken as the new theoretical concentration extreme value and added as a set of data to the training set of the depth concentration model.

[0066] Example 2:

[0067] This embodiment provides a method for detecting volatile organic compounds (VOCs) in soil, operated using a VOCs detection system disclosed in Embodiment 1. The system includes an environmental acquisition module 5, a soil information acquisition module 6, a control module 7, a depth measurement module 8, a processing module 9, and a support. The support is equipped with a first detection rod 1, a second detection rod 2, a drive assembly, and a gas detection assembly 4. The first detection rod 1 includes an inner tube 11 and an outer tube 12, with the outer tube 12 fitted over the inner tube 11. One end of the inner tube 11 has a flow port 101. An air inlet 102 is connected between the inner tube 11 and the outer tube 12. An air supply device 121 is provided outside the outer tube 12 to introduce carrier gas into the outer tube 12. The second detection rod 2 and the first detection rod 1 are inclined together. When the lower end of the second detection rod 2 is close to the lower end of the first detection rod 1, the first detection rod 1 outputs carrier gas to the second detection rod 2. The driving component is used to drive the first detection rod 1 and the second detection rod 2 to move down. The gas detection component 4 is connected to the inner tube 11 and the second detection rod 2 respectively. The gas detection component 4 draws gas from the inner tube 11 or the second detection rod 2 to obtain the concentration of volatile gas.

[0068] The detection methods include:

[0069] Step 1: Set up a support frame on the ground. The soil information acquisition module 6 takes a picture of the soil and defines it as soil image information. Soil data is extracted from the soil image information. Soil data includes soil particle data and soil color data. Soil particle data reflects the average size of the soil surface particles, and soil color data reflects the color of the soil surface. The environment acquisition module 5 acquires environmental parameters and defines them as environmental data. Environmental parameters include current temperature, wind force, and historical precipitation.

[0070] Step 2: The control module 7 controls the drive component to drive the first detection rod 1 downward at a preset downward speed. The gas supply device 121 continuously supplies carrier gas into the outer pipe 12. The carrier gas passes through the outer pipe 12, the air inlet 102, and the inner pipe 11 and reaches the gas detection component 4. The gas detection unit 41 determines the presence or absence of volatile gas in the inner pipe 11. When volatile gas is detected, the gas detection unit 41 obtains the gas concentration to obtain the gas pre-detection concentration and generates a depth detection signal. It then controls the gas supply device 121 and the drive component to stop working. The gas pre-detection concentration reflects the actual concentration of volatile gas at the flow port 101 position of the first detection rod 1. The depth measurement module 8 obtains the depth detection signal and the depth data. The depth data reflects the distance of the flow port 101 of the first detection rod 1 from the ground surface.

[0071] Step 3: The processing module 9 acquires environmental data, soil data, gas pre-detection concentration and depth data and inputs them into the trained depth concentration model to obtain the predicted depth value and generate a depth signal to the control module 7. The predicted depth value reflects the depth at which the gas concentration theoretically reaches its maximum value.

[0072] Step four: The control module 7 receives the depth signal and drives the first detection rod 1 and the second detection rod 2 to descend to the predicted depth value position. Then, the gas supply device 121 supplies gas so that the carrier gas reaches the second detection rod 2 through the outer pipe 12. The gas detection unit 41 collects the volatile gas concentration of the second detection rod 2 to define it as the actual measured concentration.

[0073] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A detection system for volatile organic compounds in soil, characterized in that: Includes a bracket, on which are provided The first detection rod (1) includes an inner tube (11) and an outer tube (12). The outer tube (12) is sleeved outside the inner tube (11). One end of the inner tube (11) has a flow port (101). An air inlet (102) connects the inner tube (11) and the outer tube (12). An air supply device (121) is provided outside the outer tube (12) to introduce carrier gas into the outer tube (12). The second detection rod (2) is inclined between the second detection rod (2) and the first detection rod (1). When the lower end of the second detection rod (2) approaches the lower end of the first detection rod (1), the first detection rod (1) outputs carrier gas to the second detection rod (2). The driving component is used to drive the first detection rod (1) and the second detection rod (2) to descend. Gas detection component (4), which is connected to the inner tube (11) and the second detection rod (2) respectively. The gas detection component (4) extracts the gas in the inner tube (11) or the second detection rod (2) to obtain the concentration of volatile gases. The detection system includes Environment acquisition module (5), the environment acquisition module (5) acquires environmental parameters to define them as environmental data, the environmental parameters include current temperature, wind force, and historical precipitation; Soil information acquisition module (6), the soil information acquisition module (6) takes a picture of the soil to define it as soil image information, and extracts soil data from the soil image information. The soil data includes soil particle data and soil color data. The soil particle data reflects the average size of the soil surface particles, and the soil color data reflects the color of the soil surface. The control module (7) controls the drive assembly to drive the first detection rod (1) downward at a preset downward speed. The gas supply device (121) continuously supplies carrier gas into the outer tube (12) and causes the gas detection unit (41) to determine the presence or absence of volatile gas in the inner tube (11). When volatile gas is detected, the gas detection unit (41) acquires the gas concentration to obtain the gas pre-detection concentration and generates a depth detection signal. It also controls the gas supply device (121) and the drive assembly to stop working. The gas pre-detection concentration reflects the actual concentration of volatile gas at the upper flow port (101) of the first detection rod (1). The depth measurement module (8) acquires depth detection signals and depth data, which reflects the distance between the flow port (101) of the first detection rod (1) and the ground surface. The processing module (9) acquires the environmental data, soil data, gas pre-detection concentration and depth data and inputs them into the trained depth concentration model to obtain the predicted depth value and generate a depth signal to the control module (7). The predicted depth value reflects the depth when the gas concentration reaches its maximum theoretical value. The control module (7) instructs the driving component to drive the first detection rod (1) and the second detection rod (2) to descend to the predicted depth value position. Then the gas supply device (121) supplies gas so that the carrier gas reaches the second detection rod (2) through the outer pipe (12). The gas detection unit (41) collects the volatile gas concentration of the second detection rod (2) to define it as the actual measured concentration.

2. The soil volatile organic compound detection system according to claim 1, characterized in that: The first detection rod (1) is provided with a baffle assembly, which includes a sensing element, a fixing element, a sliding element (13), and a transmission slider (14). The sliding member (13) is slidably connected to the inner wall of the outer tube (12). The transmission slider (14) is annular and slidably connected between the inner tube (11) and the outer tube (12). The transmission slider (14) slides in the outer tube by means of the pressure difference on both sides. The transmission slider (14) is fixedly connected to the sliding part (133) to drive the sliding member (13) to slide synchronously. The fixing member is fixedly connected to the outer tube (12) and is used to restrict the movement of the transmission slider (14). When the lower end of the second detection rod (2) approaches the lower end of the first detection rod (1), the sensing element is triggered to release the transmission slider (14) from the fixing member. The sliding member (13) passes through one end of the outer tube (12) near the flow port (101). The sliding member (13) includes a baffle part (131), a flexible support part (132) and a sliding part (133). The flexible support part (132) is flexible and connected between the baffle part (131) and the sliding part (133). When the sliding part (133) slides inside the outer tube (12), the sliding part (133) can push the baffle part (131) to protrude outside the outer tube (12) to guide the carrier gas to the second detection rod (2).

3. The soil volatile organic compound detection system according to claim 2, characterized in that: The transmission slider (14) is configured as a rubber elastic element, and the rubber elastic element has a pressure relief hole (141). When the pressure relief hole (141) is squeezed along the hole diameter direction, the rubber elastic element can generate elastic deformation to change the flow diameter of the pressure relief hole (141). The outer tube (12) is provided with an expansion hole group along its length. The expansion hole group corresponds one-to-one with the pressure relief hole (141). The expansion hole group includes several expansion rods (15). The expansion rods (15) in the same expansion hole group are distributed in a conical shape. When the transmission slider (14) slides towards the flow port (101), the compression between the expansion rods (15) and the pressure relief hole (141) is reduced to reduce the flow diameter of the pressure relief hole (141).

4. The soil volatile organic compound detection system according to claim 1, characterized in that: The bracket includes a first support (31) and a second support (32), the distance between the first support (31) and the second support (32) is adjustable, the first detection rod (1) is slidably mounted on the first support (31), and the second detection rod (2) is slidably mounted on the second support (32). The drive assembly includes a first motor (311), a first drive gear (312), and a first drive collar (313) mounted on a first support (31). The first drive gear (312) and the first drive collar (313) mesh with each other and are both rotatably connected to the first support (31). The output shaft of the first motor (311) is coaxially and fixedly connected to the first drive gear (312). The first drive collar (313) is sleeved on the outside of the first detection rod (1), and the first drive collar (313) and the first detection rod (1) are threadedly connected. When the first drive collar (313) rotates, the first detection rod (1) can slide along its own length. The drive assembly includes a second motor (321), a second drive gear (322), and a second drive collar (323) mounted on a second support (32). The second drive gear (322) and the second drive collar (323) mesh with each other and are rotatably connected to the second support (32). The second motor (321) drives the second drive gear (322) to rotate. The second drive collar (323) is sleeved on the outside of the second detection rod (2), and the second drive collar (323) and the second detection rod (2) are threadedly connected. When the second drive collar (323) rotates, the second detection rod (2) can slide along its own length direction.

5. The soil volatile organic compound detection system according to claim 1, characterized in that: The processing module (9) is configured with an operation judgment strategy. Specifically, the operation judgment strategy is to obtain and judge whether the predicted depth value meets the preset detection range. If the predicted detection depth is less than the lower limit of the preset detection range, a first termination signal is generated to indicate that the depth is too shallow. If the predicted detection depth meets the lower limit of the preset detection range, a second detection signal is generated to the control module (7). If the predicted detection depth exceeds the upper limit of the preset detection range, a second termination signal is generated to indicate that the depth is too low.

6. The soil volatile organic compound detection system according to claim 2, characterized in that: The processing module (9) is configured with a concentration conversion strategy to convert the actual measured concentration into a target concentration. Specifically, the concentration conversion strategy is to take the preset waiting time after the sensor is triggered as the starting point of the collection time, the preset measurement time as the time span, and collect the average gas supply speed of the gas supply device (121), the gas extraction speed of the gas detection component (4), and the average measured concentration of the gas detection unit (41). The average measured concentration represents the mean of the actual measured concentration. The target concentration is obtained by converting the average gas supply speed, the gas extraction speed, and the average measured concentration.

7. The soil volatile organic compound detection system according to claim 1, characterized in that: The detection system is configured with a model update strategy, which specifically includes: obtaining the theoretical concentration extreme value based on the depth concentration model, the theoretical concentration extreme value reflecting the gas concentration at the theoretically predicted depth value position; comparing the actual measured concentration with the theoretical concentration extreme value; if the difference between the two is greater than a preset difference, then this data is discarded and a re-detection is prompted; if the difference between the two is less than or equal to the preset difference, then the actual measured concentration is taken as the new theoretical concentration extreme value and added as a set of data to the training set of the depth concentration model.

8. The soil volatile organic compound detection system according to claim 1, characterized in that: The soil information acquisition module (6) is configured with a particle data extraction strategy, which specifically includes: dividing the soil image information into several rectangular blocks and acquiring the gray value of each rectangular block; calculating the gray mean of the rectangular blocks; comparing the gray value of each rectangular block with the gray mean; if the gray value is greater than the gray mean, assigning a first gray value to the rectangular block; if the gray value is less than or equal to the gray mean, assigning a second gray value to the rectangular block; the first gray value is greater than the gray mean, and the gray mean is greater than the second gray value, so as to realize the binarization of the soil image information; merging rectangular blocks with the same gray value into the same color region; calculating the number of the same color region with the first gray value and the sum of the areas of each same color region to obtain the average area size of the same color region; the area size of the same color region reflects the average size of soil particles in the soil image information.

9. A method for detecting volatile organic compounds in soil, characterized in that: A soil volatile organic compound (VOC) detection system is provided, comprising an environmental acquisition module (5), a soil information acquisition module (6), a control module (7), a depth measurement module (8), a processing module (9), and a support. The support is provided with a first detection rod (1), a second detection rod (2), a driving assembly, and a gas detection assembly (4). The first detection rod (1) includes an inner tube (11) and an outer tube (12). The outer tube (12) is sleeved outside the inner tube (11). One end of the inner tube (11) has a flow port (101). An air inlet (102) connects the inner tube (11) and the outer tube (12). The outer tube (12)... 12) An external gas supply device (121) is provided to introduce carrier gas into the outer tube (12). The second detection rod (2) and the first detection rod (1) are inclined together. When the lower end of the second detection rod (2) approaches the lower end of the first detection rod (1), the first detection rod (1) outputs carrier gas to the second detection rod (2). The driving assembly is used to drive the first detection rod (1) and the second detection rod (2) to descend. The gas detection assembly (4) is connected to the inner tube (11) and the second detection rod (2) respectively. The gas detection assembly (4) draws gas from the inner tube (11) or the second detection rod (2) to obtain the concentration of volatile gases. The detection method includes: Step 1: A support frame is erected on the ground. The soil information acquisition module (6) takes images of the soil to define them as soil image information and extracts soil data from the soil image information. The soil data includes soil particle data and soil color data. The soil particle data reflects the average size of the soil surface particles, and the soil color data reflects the color of the soil surface. The environment acquisition module (5) acquires environmental parameters to define them as environmental data. The environmental parameters include the current temperature, wind force, and historical precipitation. Step two, the control module (7) controls the drive assembly to drive the first detection rod (1) downward at a preset downward speed. The gas supply device (121) continuously supplies carrier gas into the outer tube (12). The carrier gas passes through the outer tube (12), the air inlet (102), and the inner tube (11) and reaches the gas detection assembly (4). The gas detection unit (41) determines the presence or absence of volatile gas in the inner tube (11). When volatile gas is detected, the gas detection unit (41) obtains the gas concentration to obtain the gas pre-detection concentration and generates a depth detection signal. It also controls the gas supply device (121) and the drive assembly to stop working. The gas pre-detection concentration reflects the actual concentration of volatile gas at the upper flow port (101) of the first detection rod (1). The depth measurement module (8) acquires the depth detection signal and acquires the depth data, which reflects the distance between the flow port (101) of the first detection rod (1) and the ground surface; Step 3: The processing module (9) acquires the environmental data, soil data, gas pre-detection concentration and depth data and inputs them into the trained depth concentration model to obtain the predicted depth value and generate a depth signal to the control module (7). The predicted depth value reflects the depth when the gas concentration reaches its maximum value in theory. Step four, the control module (7) receives the depth signal and drives the first detection rod (1) and the second detection rod (2) to descend to the predicted depth value position. Then the gas supply device (121) supplies gas so that the carrier gas reaches the second detection rod (2) through the outer pipe (12). The gas detection unit (41) collects the volatile gas concentration of the second detection rod (2) to define it as the actual measured concentration.

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