Equipment and method for simultaneously detecting VOCs (Volatile Organic Compounds) in underground water and soil gas of polluted site

Abstract

The invention discloses equipment and a method for simultaneously detecting VOCs (Volatile Organic Compounds) in underground water and soil gas of a polluted site. The equipment comprises a supporting assembly, a sampling assembly, a detection assembly and a PLC (Programmable Logic Controller), the supporting assembly comprises a wellhead support and a shaft. The sampling assembly comprises a gas sampling component and a water sampling component which are arranged in the shaft, and a traction component arranged on the wellhead bracket; the detection assembly comprises a purging and trapping component and a VOCs detector which are arranged on the wellhead bracket; the purging and trapping component is respectively connected with the water sampling component and the VOCs detector; the VOCs detector is connected with the gas production component; the PLC is electrically connected with each electric device; the equipment is reasonable in structural design, VOCs in underground water and polluted soil can be detected at the same time, the VOCs detection difficulty is reduced, and the detection efficiency is improved; and the equipment has the advantages of high automation degree and small disturbance on the polluted soil in the VOCs collection process, and is suitable for popularization and application.

Description

Technical Field

[0001] The present invention relates to the field of environmental governance technology, and in particular to a device and method for simultaneously detecting VOCs in groundwater and soil gas at a contaminated site. Background Art

[0002] The sources of VOCs are mainly divided into two categories: natural sources and anthropogenic sources. Natural sources refer to VOCs released by biological processes such as animals, plants and microorganisms in nature, and non-biological processes such as volcanic eruptions and forest fires. Anthropogenic sources refer to those generated by human activities, including industrial sources, agricultural sources, living sources and mobile sources. Globally, natural emissions contribute 91.9% of TVOCs, but in areas where humans live, human factors are comparable to natural factors. The diversity of human activities has led to the complexity of VOCs sources, such as landfills, transportation, industrial production and fossil fuel combustion; with economic development and urban planning, industrial production activities and legacy organic pollution sites are one of the important sources of VOCs. Industrial production activities generate VOCs pollutants that enter the human environment. Some VOCs substances enter the soil and groundwater during transportation and storage through leakage and unreasonable stacking with rainwater.

[0003] Faced with the increasingly severe situation of soil and groundwater pollution risk prevention and control, VOCs detection in soil and groundwater of contaminated sites is the primary link in soil environmental governance; however, existing detection equipment mainly relies on manual sampling and detection, with a long detection cycle, and the detection equipment is expensive and has high requirements for the experimental environment. It is mostly used for laboratory quantitative analysis and cannot be carried to the site for use, and it is impossible to monitor organic pollutants in soil and groundwater at the same time; and when samples are stored or transported to analytical laboratories, pollutants may be lost due to evaporation or degradation during transportation, affecting the investigation results. Summary of the invention

[0004] In response to the above-mentioned technical problems, the present invention provides a device and method for simultaneously detecting VOCs in groundwater and soil gas in a contaminated site.

[0005] The technical solution of the present invention is: a device for simultaneously detecting VOCs in groundwater and soil gas in a contaminated site, comprising a support component, a sampling component, a detection component and a PLC controller; the support component comprises a wellhead bracket and a wellbore;

[0006] The sampling assembly includes an air sampling component and a water sampling component arranged inside the wellbore, and a pulling component arranged on the wellhead bracket; the air sampling component includes two sealing disks and sealing air bags respectively sleeved outside the two sealing disks, and the two sealing disks are connected by a pull rod; an inflator connected to the sealing air bags and an air pump connected to the space surrounded by the two sealing disks and the wellbore are arranged on the wellhead bracket; the water sampling component includes an adjusting cylinder arranged at the bottom end of the sealing disk, a water collecting cylinder arranged at the bottom end of the adjusting cylinder, and an electric push rod arranged inside the adjusting cylinder and connected to the water collecting cylinder; a water inlet groove is penetrated on the side wall of the water collecting cylinder, and a liquid level sensor is arranged at the bottom end; a water pump connected to the water collecting cylinder is arranged on the wellhead bracket;

[0007] The detection assembly includes a purge and capture component and a VOCs detector arranged on a wellhead bracket; the purge and capture component is connected to a water pump and a VOCs detector respectively; the VOCs detector is connected to an air pump;

[0008] The PLC controller is electrically connected to the liquid level sensor, the inflator, the air pump, the electric push rod, the water pump, the purge and capture component and the VOCs detector respectively.

[0009] Furthermore, the pulling member includes a guide pulley rotatably connected to the top of the wellhead bracket, an electric winch arranged on the wellhead bracket and electrically connected to the PLC controller, and a traction rope having one end connected to a sealing disk located at the upper end of the wellbore and the other end connected to the electric winch after passing through the guide pulley;

[0010] Description: Use the PLC controller to control the start of the electric winch, and use the electric winch to control the retraction and release of the traction rope, so as to adjust the height of the sampling component inside the wellbore.

[0011] Furthermore, the purge and collection component includes a purge cylinder, a gas collecting plate arranged at the top of the purge cylinder, and a defoaming motor arranged at the top of the purge cylinder and electrically connected to the PLC controller; a carrier gas pipe and a sampling pipe are arranged on the side wall of the purge cylinder from top to bottom, and the sampling pipe is connected to the output end of the water pump through a conduit; a filter plate is arranged at the bottom of the gas collecting plate, and a transfer pipe that penetrates the purge cylinder and is connected to the VOCs detector is arranged on the side wall of the gas collecting plate; the output shaft of the defoaming motor penetrates the purge cylinder, and a defoaming spiral is sleeved on the output shaft;

[0012] Description: The water sample collected inside the water collection tube enters the purge tube through the sampling tube under the action of the water pump, and nitrogen is loaded into the purge tube through the carrier gas tube to purge the VOCs in the water sample. The purged VOCs pass through the filter disk and the transfer tube in turn and then enter the VOCs detector for detection. When the VOCs pass through the filter disk, the foam and water droplets carried in the VOCs are filtered and blocked by the filter disk.

[0013] Furthermore, a cooling jacket is provided on the outer sleeve of the purge cylinder, and several U-shaped cooling tubes are evenly distributed inside the cooling jacket; a first annular tube connected to one output end of each U-shaped cooling tube is provided at the upper end of the outer wall of the cooling jacket, and a second annular tube connected to the bottom end of each U-shaped cooling tube is provided at the bottom end of the cooling jacket; the first annular tube is connected to the VOCs detector, and a drainage joint is provided on the second annular tube; the number of transfer tubes corresponds to the number of U-shaped cooling tubes, and each transfer tube is connected to the other output end of each U-shaped cooling tube in a one-to-one correspondence;

[0014] Description: When in use, inject coolant into the cooling jacket, and the VOCs purged from the water sample enter the U-shaped cooling tube through the adapter tube. The water vapor carried by the VOCs forms droplets after cooling and enters the second annular tube; the cooled VOCs enter the VOCs detector through the first annular tube to prevent water vapor from affecting the detection accuracy of the VOCs detector.

[0015] Furthermore, a sliding sleeve is arranged outside the water collecting cylinder and at a position corresponding to the water inlet groove; a sliding rod penetrating the adjusting cylinder is arranged at the top of the sliding sleeve, and a limiting head is arranged at the top of the sliding rod;

[0016] Note: When the water collecting cylinder is in use, an electric push rod is used to push the water collecting cylinder away from the adjusting cylinder. During the movement of the water collecting cylinder, the sliding rod moves on the adjusting cylinder. When the limit head contacts the bottom of the adjusting cylinder, the sliding sleeve disengages from the water inlet groove. At this time, the water sample enters the water collecting cylinder through the water inlet groove, preventing debris from entering the water collecting cylinder when the water collecting cylinder is placed in the wellbore.

[0017] Furthermore, a filter screen is provided on the water inlet trough, and a cleaning sleeve abutting against the filter screen is provided on the inner side wall of the sliding sleeve;

[0018] Note: By setting up a filter, external debris can be prevented from entering the water collection tube; during the movement of the sliding sleeve, the filter is cleaned with a cleaning sleeve to prevent the filter from being blocked and affecting the sampling efficiency of the water collection tube.

[0019] The present invention also provides a method for simultaneously detecting VOCs in groundwater and soil gas of a contaminated site, based on the above-mentioned device for simultaneously detecting VOCs in groundwater and soil gas of a contaminated site, comprising the following steps:

[0020] S1. Dig a sampling well at the contaminated site, then place the wellbore into the sampling well; finally, connect the wellhead bracket to the wellbore, and the VOCs and groundwater in the contaminated soil enter the wellbore through the through hole;

[0021] S2, control the pulling member to start through the PLC controller, and use the pulling member to put the sampling assembly into the wellbore. When the liquid level sensor senses that the water collecting tube contacts the water surface, control the pulling member to close through the PLC controller; at the same time, control the inflator to start through the PLC controller to inflate the two sealing airbags so that the two sealing disks are clamped in the wellbore; control the electric push rod to start through the PLC controller, and use the electric push rod to push the water collecting tube away from the regulating tube so that the groundwater collected in the wellbore enters the water collecting tube through the water inlet trough;

[0022] S3. Use a vacuum pump to draw the VOCs in the space enclosed by the two sealing plates and the wellbore into the VOCs detector for detection; use a water pump to draw the water sample collected from the water collection tube into the purge and capture component, and the VOCs blown out from the purge and capture component enter the VOCs detector for detection.

[0023] Compared with the prior art, the beneficial effects of the present invention are embodied in the following aspects:

[0024] First, the device structure of the present invention is reasonably designed and can detect VOCs in groundwater and contaminated soil at the same time, which reduces the difficulty of VOCs detection and improves detection efficiency; and the device of the present invention has the advantages of high automation and little disturbance to contaminated soil during VOCs collection;

[0025] Second, the device of the present invention utilizes the space enclosed by the two sealing disks and the wellbore to collect VOCs in the contaminated soil, so that the device of the present invention can simultaneously collect VOCs in the contaminated soil and groundwater, and can also avoid the contaminated soil and groundwater VOCs from mixing with each other to affect the detection accuracy;

[0026] Third, during use of the purge and capture component of the present invention, a cooling jacket is provided so that when VOCs carrying water vapor pass through the U-shaped cooling tube, the water vapor is liquefied into water droplets and gathered at the bottom of the U-shaped cooling tube for discharge, thereby improving the detection accuracy of VOCs in groundwater. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a longitudinal sectional view of the apparatus of the present invention;

[0028] Figure 2 is a top view of the apparatus of the present invention;

[0029] Figure 3 It is a schematic diagram of the connection between the air collecting component and the water collecting component of the present invention;

[0030] Figure 4 The present invention Figure 3 A local enlarged schematic diagram of the middle A;

[0031] Figure 5 It is a schematic diagram of the connection between the sealing airbag and the sealing disk of the present invention;

[0032] Figure 6 is a longitudinal sectional view of the purge and capture member of the present invention;

[0033] Figure 7 is a front view of the purge and capture component of the present invention;

[0034] Figure 8 It is a schematic diagram of the connection between the gas collecting plate, the cooling jacket and the purge cylinder of the present invention;

[0035] Among them, 1-support component, 10-wellhead bracket, 11-wellbore, 110-through hole, 2-sampling component, 20-gas collection component, 200-sealing disk, 201-sealing airbag, 202-pull rod, 203-inflator, 204-air pump, 21-water collection component, 210-adjusting cylinder, 211-water collecting cylinder, 2110-water inlet tank, 2111-propelling frame, 2112-filter net, 212-electric push rod, 213-water pump, 214-sliding sleeve, 2140-sliding rod, 2141-limiting head, 2142-cleaning sleeve, 22-pulling component , 220-guide pulley, 221-electric winch, 222-traction rope, 3-detection component, 30-purge and capture component, 300-purge cylinder, 3000-carrier gas tube, 3001-injection tube, 301-gas collecting plate, 3010-filter plate, 3011-transfer tube, 302-defoaming motor, 3020-output shaft, 3021-defoaming spiral, 3022-compression spring, 303-cooling jacket, 3030-first annular tube, 3031-second annular tube, 304-U-type cooling tube, 31-VOCs detector, 4-solar power supply module. DETAILED DESCRIPTION

[0036] Example 1

[0037] like Figure 1 The device for simultaneously detecting VOCs in groundwater and soil gas of a contaminated site is characterized in that it includes a support component 1 and a sampling component 2, a detection component 3 and a PLC controller arranged on the support component 1; the sampling component 2 is connected to the detection component 3, and the sampling component 2 and the detection component 3 are electrically connected to the PLC controller respectively; the support component 1 includes a wellhead bracket 10 arranged on the ground and a wellbore 11 arranged below the ground and movably connected to the wellhead bracket 10; a through hole 110 is penetrated on the side wall of the wellbore 11;

[0038] like Figure 1 , 2As shown in , 3, 4, and 5, the sampling assembly 2 includes a gas collection component 20 arranged inside the wellbore 11, a water collection component 21 arranged at the bottom of the gas collection component 20, and a pulling component 22 arranged on the wellhead bracket 10 and connected to the gas collection component 20; the gas collection component 20 includes a sealing disk 200 and a sealing airbag 201 sleeved on the outside of the sealing disk 200, two sealing disks 200 are provided, and the two sealing disks 200 are connected by a pull rod 202; an inflator 203 and an air pump 204 are provided on the wellhead bracket 10; the output end of the inflator 203 is respectively connected to the two sealing airbags 201 through a conduit; the input end of the air pump 204 is connected to the space surrounded by the two sealing disks 200 and the wellbore 11 through a conduit; the water collection component 2 1 comprises an adjusting cylinder 210 arranged at the bottom of a sealing disk 200 located at the lower end of the wellbore 11, a water collecting cylinder 211 movably arranged at the bottom of the adjusting cylinder 210, and an electric push rod 212 arranged inside the adjusting cylinder 210 and connected to the water collecting cylinder 211; a water inlet groove 2110 is penetrated on the side wall of the water collecting cylinder 211, and a liquid level sensor is arranged at the bottom of the water collecting cylinder 211; a pushing frame 2111 penetrating the adjusting cylinder 210 and slidingly engaged with the adjusting cylinder 210 is arranged at the top of the water collecting cylinder 211, and the electric push rod 212 is connected to the pushing frame 2111; a water pump 213 is arranged on the wellhead bracket 10, and the input end of the water pump 213 is connected to the water collecting cylinder 211 through a conduit; the pulling member 22 adopts a traction machine in the prior art;

[0039] The detection assembly 3 includes a purge and capture component 30 disposed on the wellhead bracket 10 and connected to the output end of the water pump 213 and a VOCs detector 31 disposed on the wellhead bracket 10 and connected to the output end of the air pump 203; the purge and capture component 30 is connected to the VOCs detector 31; the purge and capture component 30 adopts a purge and capture machine in the prior art;

[0040] The PLC controller is electrically connected to the liquid level sensor, the inflator 203 , the air pump 204 , the electric push rod 212 , the water pump 213 , the purge and capture component 30 and the VOCs detector 31 , respectively.

[0041] Example 2

[0042] This embodiment describes a method for simultaneously detecting VOCs in groundwater and soil gas at a contaminated site. The device for simultaneously detecting VOCs in groundwater and soil gas at a contaminated site based on Embodiment 1 includes the following steps:

[0043] S1. Dig a sampling well at the contaminated site, and then place the wellbore 11 into the sampling well; finally, connect the wellhead bracket 10 with the wellbore 11, and the VOCs and groundwater in the contaminated soil enter the wellbore 11 through the through hole 110;

[0044] S2, control the pulling member 22 to start through the PLC controller, and use the pulling member 22 to put the sampling assembly 2 into the wellbore 11. When the liquid level sensor senses that the water collecting tube 211 contacts the water surface, control the pulling member 22 to close through the PLC controller; at the same time, control the inflator 203 to start through the PLC controller to inflate the two sealing airbags 201, so that the two sealing disks 200 are clamped in the wellbore 11; control the electric push rod 212 to start through the PLC controller, and use the electric push rod 212 to drive the pushing frame 2111, so that the water collecting tube 211 is away from the regulating tube 210. At this time, the groundwater collected in the wellbore 11 enters the water collecting tube 211 through the water inlet trough 2110;

[0045] S3. Use the vacuum pump 204 to pump the VOCs in the space enclosed by the two sealing plates 200 and the wellbore 11 into the VOCs detector 31 for detection; use the water pump 213 to pump the water sample collected from the water collecting tube 211 into the purge and capture component 30, and the VOCs blown out from the purge and capture component 30 enter the VOCs detector 31 for detection.

[0046] Example 3

[0047] The difference between this embodiment and embodiment 1 is that:

[0048] like Figure 1 , 2 As shown, the pulling member 22 includes a guide pulley 220 rotatably connected to the top of the wellhead bracket 10, an electric winch 221 disposed on the wellhead bracket 10 and electrically connected to the PLC controller, and a traction rope 222 having one end connected to the sealing disk 200 located at the upper end of the wellbore 11 and the other end connected to the electric winch 221 after passing through the guide pulley 220;

[0049] By providing the pulling member 22, it is convenient to adjust the height of the sampling assembly 2 inside the wellbore 11, thereby improving the convenience of collecting VOCs in contaminated soil and groundwater.

[0050] Example 4

[0051] This embodiment describes a method for simultaneously detecting VOCs in groundwater and soil gas at a contaminated site. The device for simultaneously detecting VOCs in groundwater and soil gas at a contaminated site based on Embodiment 3 is different from Embodiment 2 in that:

[0052] In step S2 , the PLC controller is used to control the electric winch 221 to start, and the electric winch 221 is used to control the retraction and extension of the traction rope 222 , so that the sampling assembly 2 is raised and lowered inside the wellbore 11 .

[0053] Example 5

[0054] The difference between this embodiment and embodiment 3 is that:

[0055] like Figure 6 , 7 As shown, the purge and capture component 30 includes a purge cylinder 300, a gas collecting plate 301 arranged at the top of the purge cylinder 300, and a defoaming motor 302 arranged at the top of the purge cylinder 300 and electrically connected to the PLC controller; a carrier gas pipe 3000 and a sample injection pipe 3001 are arranged on the side wall of the purge cylinder 300 from top to bottom, and the sample injection pipe 3001 is connected to the output end of the water pump 213 through a conduit; a filter plate 300 is arranged at the bottom of the gas collecting plate 301. 010, a transfer tube 3011 is provided on the side wall of the gas collecting plate 301, which passes through the purge cylinder 300 and is connected to the VOCs detector 31; the output shaft 3020 of the defoaming motor 302 passes through the purge cylinder 300, and a defoaming spiral 3021 is sleeved on the output shaft 3020; the defoaming spiral 3021 is slidably engaged on the output shaft 3020; the output shaft 3020 is sleeved with a compression spring 3022 which abuts against the upper end surface of the defoaming spiral 3021.

[0056] Example 6

[0057] This embodiment describes a method for simultaneously detecting VOCs in groundwater and soil gas at a contaminated site. The device for simultaneously detecting VOCs in groundwater and soil gas at a contaminated site based on Embodiment 5 is different from Embodiment 4 in that:

[0058] In step S3, after the water sample enters the purge cylinder 300, nitrogen is loaded into the purge cylinder 300 through the carrier gas pipe 3000 to purge the VOCs in the water sample. The purged VOCs pass through the filter disc 3010 and the transfer tube 3011 in turn and enter the VOCs detector 31 for detection. When the VOCs pass through the filter disc 3010, the foam and water droplets carried by the VOCs are filtered and blocked by the filter disc 3010; at the same time, the PLC controller is used to control the defoaming motor 302 to start, and the defoaming motor 302 is used to drive the defoaming spiral 3021 to rotate, so as to perform secondary crushing treatment on the foam carried by the VOCs; wherein, the nitrogen loading amount is 90ml / min;

[0059] Example 7

[0060] The difference between this embodiment and embodiment 5 is that:

[0061] like Figure 6 , 8As shown, the purge cylinder 300 is provided with a cooling jacket 303 on the outside, and six U-shaped cooling tubes 304 are evenly distributed inside the cooling jacket 303; a first annular tube 3030 connected to one output end of each U-shaped cooling tube 304 is provided on the upper end of the outer wall of the cooling jacket 303, and a second annular tube 3031 connected to the bottom end of each U-shaped cooling tube 304 is provided on the bottom end of the cooling jacket 303; the first annular tube 3030 is connected to the VOCs detector 31, and a drainage joint is provided on the second annular tube 3030; the number of transfer tubes 3011 corresponds to the number of U-shaped cooling tubes 304, and each transfer tube 3011 is connected to the other output end of each U-shaped cooling tube 304 one by one;

[0062] By providing the cooling jacket 303 and the U-shaped cooling tube 304, the water vapor carried by the VOCs is condensed into water droplets and discharged through the second annular tube 3030, thereby preventing the water vapor from affecting the detection accuracy of the VOCs in the groundwater.

[0063] Example 8

[0064] This embodiment describes a method for simultaneously detecting VOCs in groundwater and soil gas at a contaminated site. The device for simultaneously detecting VOCs in groundwater and soil gas at a contaminated site based on Embodiment 7 is different from Embodiment 6 in that:

[0065] In step S3, coolant is injected into the cooling jacket 303, and the VOCs purged from the water sample enter the U-shaped cooling tube 304 through the transfer tube 3011. The water vapor carried by the VOCs forms droplets after cooling and enters the second annular tube 3030; the cooled VOCs enter the VOCs detector 31 through the first annular tube 3030.

[0066] Example 9

[0067] The difference between this embodiment and embodiment 7 is that:

[0068] Nine U-shaped cooling tubes 304 are evenly distributed inside the cooling jacket 303 .

[0069] Example 10

[0070] This embodiment is different from Embodiment 7 in that:

[0071] like Figure 3 , 4 As shown, a sliding sleeve 214 is arranged outside the water collecting cylinder 211 and at a position corresponding to the water inlet groove 2110; a sliding rod 2140 penetrating the adjusting cylinder 210 is arranged at the top of the sliding sleeve 214, and a limiting head 2141 is arranged at the top of the sliding rod 2140; a filter screen 2112 is arranged on the water inlet groove 2110, and a cleaning sleeve 2142 abutting against the filter screen 2112 is arranged on the inner side wall of the sliding sleeve 214;

[0072] By setting the sliding sleeve 214, it is possible to prevent debris from entering the water collecting tube 211 and affecting the detection accuracy when the water collecting tube 211 is placed in the wellbore 11; during the movement of the sliding sleeve 214, the cleaning sleeve 2142 is used to clean the filter screen 2112 to prevent the filter screen 2112 from being blocked and affecting the sampling efficiency of the water collecting tube 211.

[0073] Embodiment 11

[0074] This embodiment describes a method for simultaneously detecting VOCs in groundwater and soil gas at a contaminated site. The device for simultaneously detecting VOCs in groundwater and soil gas at a contaminated site based on Embodiment 10 is different from Embodiment 8 in that:

[0075] In step S2, during the movement of the water collecting cylinder 211, the sliding rod 2140 moves on the adjusting cylinder 210. When the limit head 2141 contacts the bottom of the adjusting cylinder 210, the sliding sleeve 214 disengages from the water inlet groove 2110. At this time, the water sample enters the water collecting cylinder 211 through the water inlet groove 2110. During the movement of the sliding sleeve 214, the cleaning sleeve 2142 is used to clean the filter screen 2112.

[0076] Example 12

[0077] The difference between this embodiment and embodiment 10 is that:

[0078] like Figure 2 As shown, it also includes a solar power supply module 4 which is arranged on the wellhead bracket 10 and is electrically connected to the inflator 203, the air pump 204, the electric push rod 212, the water pump 213, the purge and capture component 30 and the VOCs detector 31 respectively;

[0079] The solar power supply module 4 is used to provide power for various electrical devices, which is beneficial to improving the convenience of the device of the present invention when used outdoors, and also reduces the energy consumption of the device.

[0080] It should be noted that the PLC controller, liquid level sensor, inflator 203, vacuum pump 204, electric push rod 212, water pump 213, electric winch 221, defoaming motor 302, VOCs detector 31 and solar power supply module 4 used in the present invention all adopt existing technologies, and no special limitations are made here. The corresponding products can be selected according to actual needs.

Claims

1. Equipment for simultaneous detection of VOCs in groundwater and soil gas at contaminated sites, characterized by: It comprises a support component (1), a sampling component (2), a detection component (3) and a PLC controller; the support component (1) comprises a wellhead support (10) and a wellbore (11); The sampling assembly (2) comprises a gas sampling component (20) and a water sampling component (21) arranged inside the wellbore (11), and a pulling component (22) arranged on the wellhead bracket (10); the gas sampling component (20) comprises two sealing disks (200) and sealing airbags (201) respectively sleeved on the outside of the two sealing disks (200), and the two sealing disks (200) are connected by a pull rod (202); the wellhead bracket (10) is provided with an inflator (203) connected to the sealing airbags (201) and a pull rod (202) connected to the two sealing disks (200) and the wellbore. The water collecting member (21) comprises an adjusting cylinder (210) arranged at the bottom end of the sealing disk (200), a water collecting cylinder (211) arranged at the bottom end of the adjusting cylinder (210), and an electric push rod (212) arranged inside the adjusting cylinder (210) and connected to the water collecting cylinder (211); a water inlet groove (2110) is provided through the side wall of the water collecting cylinder (211), and a liquid level sensor is provided at the bottom end; a water pump (213) connected to the water collecting cylinder (211) is provided on the wellhead bracket (10); The detection assembly (3) comprises a purge and capture component (30) and a VOCs detector (31) arranged on a wellhead support (10); the purge and capture component (30) is connected to a water pump (213) and a VOCs detector (31) respectively; the VOCs detector (31) is connected to an air pump (203); The PLC controller is electrically connected to the liquid level sensor, the inflator (203), the air pump (204), the electric push rod (212), the water pump (213), the purge and capture component (30), and the VOCs detector (31), respectively.

2. The device for simultaneously detecting VOCs in groundwater and soil gas of a contaminated site according to claim 1, characterized in that: The pulling member (22) comprises a guide pulley (220) rotatably engaged with the top end of the wellhead bracket (10), an electric winch (221) arranged on the wellhead bracket (10) and electrically connected to the PLC controller, and a traction rope (222) having one end connected to a sealing disk (200) located at the upper end inside the wellbore (11) and the other end connected to the electric winch (221) after passing through the guide pulley (220).

3. The device for simultaneously detecting VOCs in groundwater and soil gas of a contaminated site according to claim 1, characterized in that: The purge and collection component (30) comprises a purge cylinder (300), a gas collecting plate (301) arranged at the top of the purge cylinder (300), and a defoaming motor (302) arranged at the top of the purge cylinder (300) and electrically connected to a PLC controller; a carrier gas pipe (3000) and a sample injection pipe (3001) are arranged on the side wall of the purge cylinder (300) in sequence from top to bottom, and the sample injection pipe (3001) is connected to a water pump (213) ) is connected to the output end of the gas collecting plate (301) through a conduit; a filter plate (3010) is arranged at the bottom of the gas collecting plate (301), and a transfer tube (3011) is arranged on the side wall of the gas collecting plate (301) and passes through the purge cylinder (300) and is connected to the VOCs detector (31); the output shaft (3020) of the defoaming motor (302) passes through the purge cylinder (300), and a defoaming spiral (3021) is sleeved on the output shaft (3020).

4. The device for simultaneously detecting VOCs in groundwater and soil gas of a contaminated site according to claim 3, characterized in that: The purge cylinder (300) is provided with a cooling jacket (303) on the outside, and a plurality of U-shaped cooling tubes (304) are evenly distributed inside the cooling jacket (303); a first annular tube (3030) connected to an output end of each U-shaped cooling tube (304) is provided at the upper end of the outer wall of the cooling jacket (303), and a second annular tube (3031) connected to the bottom end of each U-shaped cooling tube (304) is provided at the bottom end of the cooling jacket (303); the first annular tube (3030) is connected to a VOCs detector (31), and a drainage joint is provided on the second annular tube (3030); the number of the transfer tubes (3011) corresponds to the number of the U-shaped cooling tubes (304), and each transfer tube (3011) is connected to the other output end of each U-shaped cooling tube (304) in a one-to-one correspondence.

5. The device for simultaneously detecting VOCs in groundwater and soil gas of a contaminated site according to claim 1, characterized in that: A sliding sleeve (214) is arranged outside the water collecting cylinder (211) and at a position corresponding to the water inlet groove (2110); a sliding rod (2140) penetrating the regulating cylinder (210) is arranged at the top end of the sliding sleeve (214); and a limiting head (2141) is arranged at the top end of the sliding rod (2140).

6. The device for simultaneously detecting VOCs in groundwater and soil gas of a contaminated site according to claim 5, characterized in that: The water inlet trough (2110) is provided with a filter screen (2112), and the inner side wall of the sliding sleeve (214) is provided with a cleaning sleeve (2142) which abuts against the filter screen (2112).

7. A method for simultaneously detecting VOCs in groundwater and soil gas at a contaminated site, based on the device for simultaneously detecting VOCs in groundwater and soil gas at a contaminated site according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Dig a sampling well at the contaminated site, then place a wellbore (11) into the sampling well; finally, connect the wellhead support (10) to the wellbore (11), and allow VOCs and groundwater in the contaminated soil to enter the wellbore (11) through the through hole (110); S2, controlling the pulling member (22) to start up through the PLC controller, and using the pulling member (22) to drop the sampling assembly (2) into the wellbore (11); when the liquid level sensor senses that the water collecting tube (211) contacts the water surface, controlling the pulling member (22) to close through the PLC controller; at the same time, controlling the inflator (203) to start up through the PLC controller to inflate the two sealing airbags (201), so that the two sealing disks (200) are clamped in the wellbore (11); controlling the electric push rod (212) to start up through the PLC controller, and using the electric push rod (212) to push the water collecting tube (211) away from the regulating tube (210), so that the groundwater collected in the wellbore (11) enters the water collecting tube (211) through the water inlet trough (2110); S3. Using an air pump (204), the VOCs in the space enclosed by the two sealing disks (200) and the wellbore (11) are pumped into the VOCs detector (31) for detection; using a water pump (213), the water sample collected from the water collecting tube (211) is pumped into the purge and capture component (30), and the VOCs blown out from the purge and capture component (30) enter the VOCs detector (31) for detection.

8. The device for simultaneously detecting VOCs in groundwater and soil gas of a contaminated site according to claim 1, characterized in that: The water inlet tank (2110) is provided with a filter screen (2112).

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