Collection and analysis system for volatile organic compounds in underground water and use method thereof

Abstract

The invention relates to the technical field of environmental monitoring, in particular to a system for collecting and analyzing volatile organic compounds in underground water and a using method thereof. Comprising a sampling needle; an outlet and an inlet are formed in the top of the purging pipe, an outlet pipe is connected to the outlet, an inlet pipe is connected to the inlet, and the inlet pipe is connected to the sampling needle; the capillary tubes are arranged in the purging pipe, one ends of the capillary tubes are connected to the inlet, and the other ends of the capillary tubes extend to the bottom wall of the purging pipe; the nitrogen mechanism is connected with the inlet pipe, and after the water sample enters the purging pipe, the nitrogen mechanism blows nitrogen into the purging pipe, so that the pressure in the purging pipe reaches a set value, and the volatile organic compounds are desorbed from the water sample; the condensation mechanism is provided with an inlet end and an outlet end, the inlet end is connected with the outlet pipe, and water vapor in the volatile organic compounds is filtered; and the detection mechanism is connected to the condensation mechanism and is used for detecting the filtered volatile organic compounds. The device has the beneficial effects that by arranging the purging pipe and the nitrogen mechanism, the nitrogen mechanism blows a water sample in the purging pipe, so that volatile organic compounds in the water sample are volatilized, and the situation that a large amount of water vapor is generated when the water sample is heated is avoided.

Description

Technical Field

[0001] This invention relates to the field of environmental monitoring technology, and specifically to a system for collecting and analyzing volatile organic compounds in groundwater and its usage method. Background Technology

[0002] Volatile organic compounds (VOCs) in water refer to organic compounds that exist in water bodies in the form of vapor at room temperature. Their components include compounds such as alkanes, aromatics, alkenes, halogenated hydrocarbons, esters, aldehydes, and ketones. They mainly originate from industrial emissions, domestic sewage, and water treatment byproducts, and have hazards such as toxicity and carcinogenicity.

[0003] Currently, the main methods for detecting and analyzing volatile organic compounds (VOCs) in water include headspace gas chromatography (GC) or mass spectrometry (MS / MS), and purge-and-trap GC or MS / MS. Headspace gas chromatography or MS / MS typically involves heating the water to volatilize the VOCs, allowing for their detection. However, heating causes significant evaporation of the water sample, generating large amounts of water vapor, which reduces the amount of volatilized VOCs and thus affects the detection accuracy.

[0004] Therefore, this invention proposes a system for collecting and analyzing volatile organic compounds in groundwater and its usage method. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a system for collecting and analyzing volatile organic compounds in groundwater and its usage method, which solves the problem that existing detection and analysis methods, which separate volatile organic compounds by heating, will generate a large amount of water vapor, thus affecting the detection effect.

[0006] The technical solution to achieve the above objectives is: This invention provides a system for collecting and analyzing volatile organic compounds in groundwater, comprising: A sampling needle has a collection end and a fixed end, wherein the collection end can be inserted into the water area to be tested to collect a water sample; The purge tube has an outlet and an inlet at its top. An outlet pipe is connected to the outlet of the purge tube, and an inlet pipe is connected to the inlet. One end of the inlet pipe is connected to the sampling needle, and the water sample in the sampling needle can enter the purge tube. Several capillaries are disposed inside the purge tube, with one end connected to the inlet and the other end extending to the bottom wall of the purge tube. When there is a water sample in the purge tube, the end of the capillary away from the inlet of the purge tube is inserted into the water sample. The nitrogen mechanism is connected to the inlet pipe of the purge tube. After the water sample enters the purge tube, the nitrogen mechanism can blow nitrogen into the purge tube through the inlet pipe and capillary tube, so that the nitrogen forms bubbles in the water sample and floats to the surface, so that the pressure in the purge tube reaches the set value, thereby desorbing volatile organic compounds from the water sample. The condensation mechanism has an inlet end and an outlet end, the inlet end being connected to one end of the outlet pipe, and can filter water vapor in the desorbed volatile organic compounds; The detection mechanism, connected to the outlet end of the condensation mechanism, is used to detect the volatile organic compounds after filtration.

[0007] Furthermore, a check valve is provided on the inlet pipe, and a pressure valve is provided on the outlet pipe; The pressure valve is normally closed. When high pressure is generated in the purge pipe and the pressure value reaches the set value, the pressure valve opens to allow nitrogen and volatile organic compounds in the purge pipe to enter the condensation mechanism. When the pressure in the purge pipe returns to normal, the pressure valve closes again.

[0008] Furthermore, it also includes: A sieve plate is disposed inside the purge tube, dividing the purge tube into upper and lower chambers. The sieve plate has several vent holes. When there is a water sample in the purge tube, the sieve plate is located inside the water sample. One end of the capillary is located in the upper chamber and connected to the inlet pipe, while the other end passes through the sieve plate and extends into the lower chamber. A circulation hole is provided at the upper chamber end of the capillary, through which nitrogen gas in the upper chamber can enter the capillary and then re-enter the lower chamber.

[0009] Furthermore, it also includes a cleaning mechanism connected to the inlet pipe of the purge pipe for cleaning the purge pipe.

[0010] Furthermore, the cleaning mechanism includes: The pump has an output pump and a water tank. The output pump has a first output end and a first input end. The first output end of the output pump is connected to the inlet pipe, and the first input end is connected to the water tank. The water tank contains distilled water. The output pump can pump the distilled water in the water tank into the purge pipe for cleaning. A peristaltic pump and a waste container, wherein the peristaltic pump has a second output end and a second input end, the second input end of the peristaltic pump is connected to the outlet pipe, and the second output end is connected to the waste container, and the peristaltic pump can pump water used to clean the purge pipe into the waste container; An air pump, connected to the inlet pipe, blows air into the purge pipe to remove water vapor from the purge pipe.

[0011] Furthermore, it also includes an adsorption mechanism and a pressure tank. The adsorption mechanism includes a housing and an adsorption tube. The adsorption tube is located inside the housing and one end is connected to the outlet end of the condensation mechanism, while the other end is connected to a second valve. The inner wall of the adsorption tube is coated with an adsorption material that can adsorb volatile organic compounds. After the volatile organic compounds are adsorbed onto the inner wall of the adsorption tube, nitrogen can be discharged through the second valve. The pressure tank has an inlet and an outlet. The inlet of the pressure tank is connected to the second valve, and the outlet is connected to the detection mechanism. The housing is equipped with a heating plate, which can heat the volatile organic compounds adsorbed on the inner wall of the adsorption tube so that the volatile organic compounds reach a set temperature, volatilize, and enter the pressure tank through the second valve.

[0012] Furthermore, the detection device is a gas chromatography-mass spectrometry (GC-MS) instrument or a gas chromatograph.

[0013] This invention also provides a method for using a system for collecting and analyzing volatile organic compounds in groundwater, specifically including the following steps: The sampling needle is inserted into the water area to be tested to collect water samples, and the collected water samples are pumped into the purge tube. The nitrogen mechanism is activated, causing it to blow nitrogen into the purge tube through the inlet tube and the capillary tube. This causes the nitrogen to form bubbles in the water sample and float to the surface, thereby separating the volatile organic compounds in the water sample. The nitrogen mechanism is then deactivated when the pressure in the purge tube reaches the set value. The volatile organic compounds in the purge pipe are introduced into the condensation mechanism through the outlet pipe. The condensation mechanism condenses the water vapor in the purge pipe into water, filters the water vapor, collects the volatile organic compounds, and discharges nitrogen. This allows volatile organic compounds to enter the testing facility for detection.

[0014] Furthermore, a check valve is provided on the inlet pipe, and a pressure valve is provided on the outlet pipe, the pressure valve being normally closed; The nitrogen mechanism blows nitrogen into the purge pipe. After the pressure in the purge pipe reaches the set value, the pressure valve opens to allow the nitrogen and volatile organic compounds in the purge pipe to enter the condensation mechanism. The pressure valve closes after the pressure inside the purge pipe returns to normal.

[0015] Furthermore, it also includes a cleaning mechanism, which is connected to the inlet pipe of the purge pipe; Before use, the cleaning mechanism should be used to clean the purge pipe; After use, the cleaning mechanism is used to clean the purge pipe.

[0016] Compared with the prior art, the present invention has the following beneficial effects: By setting up a purge pipe and a nitrogen mechanism, the nitrogen mechanism blows the water sample in the purge pipe, thereby causing the volatile organic compounds in the water sample to evaporate, thus avoiding the generation of a large amount of water vapor by heating the water sample.

[0017] By installing several capillaries and a sieve plate inside the purge tube, nitrogen gas is forced through the capillaries to form tiny bubbles that enter the water sample for aeration, allowing volatile organic compounds to be fully released. As the bubbles rise, they are further reduced in size by passing through the air vents on the sieve plate.

[0018] By incorporating a condensation mechanism, residual water vapor in the volatilized volatile organic compounds is liquefied, thus filtering out the water vapor. Furthermore, an adsorption mechanism is used to collect the volatile organic compounds and discharge excess nitrogen, achieving separation between nitrogen and volatile organic compounds. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall system for collecting and analyzing volatile organic compounds in groundwater according to the present invention.

[0020] Figure 2 This is a partial schematic diagram of the volatile organic compound (VOC) collection and analysis system in groundwater according to the present invention.

[0021] Legend: 1. Purge tube; 2. Sampling needle; 3. Switching valve; 4. Nitrogen mechanism; 5. Condensation mechanism; 6. Adsorption mechanism; 7. Power pump; 8. Pressure tank; 9. Detection mechanism; 10. Air pump; 11. Peristaltic pump; 12. Waste bin; 13. Output pump; 14. Water tank; 15. First valve; 16. Second valve; 17. Third valve; 18. Check valve; 19. Pressure valve; 20. Capillary tube; 21. Sieve plate; 22. Circulation hole; 23. Inlet pipe; 24. Outlet pipe; 25. Pressure valve. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0023] See Figure 1This invention provides a system for collecting and analyzing volatile organic compounds (VOCs) in groundwater and its usage method. It addresses the problem that existing detection and analysis methods, which separate VOCs through heating, generate large amounts of water vapor, thus affecting the detection results. To solve this problem, this invention discloses a purge tube and a nitrogen mechanism. The nitrogen mechanism blows nitrogen gas into the purge tube, causing the nitrogen to generate rising bubbles in the water sample, thereby evaporating the VOCs and avoiding the generation of large amounts of water vapor through heating.

[0024] To ensure the complete volatilization of volatile organic compounds (VOCs) in a water sample, this invention discloses several capillary tubes installed in a purge tube. One end of each capillary tube is connected to the inlet at the top of the purge tube, while the other end extends to the bottom of the purge tube and can be inserted into the water sample. Nitrogen gas is introduced into the water sample through the capillary tubes. The capillary tubes reduce the size of the nitrogen bubbles generated, thereby enabling thorough agitation of the water sample and better volatilization of VOCs. A sieve plate with several vent holes is also disclosed in the purge tube. Nitrogen bubbles generated in the water rise and pass through the vent holes in the sieve plate, becoming even smaller bubbles and further agitating the water sample. A circulation hole is also provided at the upper end of the capillary tubes, allowing nitrogen gas from the top of the purge tube to enter the capillary tubes and further into the water sample, thus circulating continuously.

[0025] Volatile organic compounds evaporate, but inevitably water vapor is produced. In order to filter out the residual water vapor, this invention discloses a condensation mechanism, in which the gas in the purge pipe first passes through the condensation mechanism, which liquefies the water vapor, thereby separating the water vapor.

[0026] Then, through the adsorption mechanism, volatile organic compounds are adsorbed inside the adsorption mechanism, thereby causing nitrogen to be discharged, thus achieving the separation of nitrogen and volatile organic compounds.

[0027] The following description, in conjunction with the accompanying drawings, illustrates a system for collecting and analyzing volatile organic compounds in groundwater according to the present invention, and its method of use.

[0028] See Figure 1 This diagram shows the overall structure of the volatile organic compound (VOC) collection and analysis system for groundwater according to the present invention. (See attached diagram.) Figure 2 This image shows a partial structural schematic diagram of the volatile organic compound (VOC) collection and analysis system for groundwater according to the present invention. The following is a related illustration. Figure 1 and Figure 2 This invention describes a system for collecting and analyzing volatile organic compounds in groundwater and its usage.

[0029] like Figure 1 and Figure 2 As shown, the present invention provides a system for collecting and analyzing volatile organic compounds in groundwater, comprising: The sampling needle 2 has a collection end and a fixed end, wherein the collection end can be inserted into the water area to be tested to collect water samples; The purge tube 1 has an outlet and an inlet at its top. An outlet pipe 24 is connected to the outlet of the purge tube 1, and an inlet pipe 23 is connected to the inlet. One end of the inlet pipe 23 is connected to the sampling needle 2, and the water sample in the sampling needle 2 can enter the purge tube 1. Several capillary tubes 20 are disposed inside the purge tube 1, with one end connected to the inlet and the other end extending to the bottom wall of the purge tube 1. When there is a water sample in the purge tube 1, the end of the capillary tube 20 away from the inlet of the purge tube 1 is inserted into the water sample. The nitrogen mechanism 4 is connected to the inlet pipe 23 of the purge pipe 1. After the water sample enters the purge pipe 1, the nitrogen mechanism 4 can blow nitrogen into the purge pipe 1 through the inlet pipe 23 and the capillary tube 20, so that the nitrogen forms bubbles in the water sample and floats up, so that the pressure in the purge pipe 1 reaches the set value, thereby desorbing volatile organic compounds from the water sample. The condensation mechanism 5 has an inlet end and an outlet end. The inlet end is connected to one end of the outlet pipe 24 and can filter water vapor in the desorbed volatile organic compounds. The detection mechanism 9 is connected to the outlet end of the condensation mechanism 5 and is used to detect the volatile organic compounds after filtration.

[0030] Preferably, the fixed end of the sampling needle 2 is equipped with a metering loop with a capacity of 5 ml. A syringe pump is installed on the metering loop to input the water sample from the metering loop into the switching valve 3. The pressure setting in the purge tube 1 is 0.3 MPa.

[0031] Specifically, the nitrogen mechanism 4 includes a nitrogen tank and a pump body. The pump body is connected to the nitrogen tank and can pump the nitrogen stored in the nitrogen tank into the purge pipe 1.

[0032] In one specific embodiment, a one-way valve 18 is provided on the inlet pipe 23, and a pressure valve 19 is provided on the outlet pipe 24; The pressure valve 19 is normally closed. When high pressure is generated in the purge pipe 1 and the pressure value reaches the set value, the pressure valve 19 opens to allow nitrogen and volatile organic compounds in the purge pipe 1 to enter the condensation mechanism 5. When the pressure in the purge pipe 1 returns to normal, the pressure valve 19 closes again.

[0033] In one specific embodiment, it also includes: A sieve plate 21 is disposed inside the purge tube 1, dividing the purge tube 1 into upper and lower chambers. The sieve plate 21 has several air vents. When there is a water sample in the purge tube 1, the sieve plate 21 is located inside the water sample. One end of the capillary tube 20 is located in the upper chamber and connected to the inlet pipe 23, while the other end passes through the sieve plate 21 and extends into the lower chamber. A circulation hole 22 is provided at the upper chamber end of the capillary tube 20, through which nitrogen gas in the upper chamber can enter the capillary tube 20 and then re-enter the lower chamber through the capillary tube 20.

[0034] Specifically, the diameter of capillary 20 is 0.45mm-0.25mm.

[0035] Preferably, the sieve plate 21 is made of quartz. By setting the sieve plate 21 and opening vent holes on the sieve plate 21, nitrogen gas in the lower chamber enters the upper chamber through the vent holes. The vent holes break the nitrogen gas into smaller bubbles, thereby allowing the bubbles to fully agitate the water sample and causing the volatile organic compounds in the water sample to evaporate.

[0036] In one specific embodiment, a cleaning mechanism is also included, which is connected to the inlet pipe 23 of the purge pipe 1, for cleaning the purge pipe 1.

[0037] In one specific embodiment, the cleaning mechanism includes: The output pump 13 and the water tank 14 are provided. The output pump 13 has a first output end and a first input end. The first output end of the output pump 13 is connected to the inlet pipe 23, and the first input end is connected to the water tank 14. The water tank 14 is filled with distilled water. The output pump 13 can pump the distilled water in the water tank 14 into the purge pipe 1 for cleaning. The peristaltic pump 11 and the waste container 12 are provided. The peristaltic pump 11 has a second output end and a second input end. The second input end of the peristaltic pump 11 is connected to the outlet pipe 24, and the second output end is connected to the waste container 12. The peristaltic pump 11 can pump water used to clean the purge pipe 1 into the waste container 12. An air pump 10 is connected to the inlet pipe 23 and can blow air into the purge pipe 1 to remove water vapor from the purge pipe 1.

[0038] In one specific embodiment, it also includes an adsorption mechanism 6 and a pressure tank 8. The adsorption mechanism 6 includes a housing and an adsorption tube. The adsorption tube is disposed inside the housing and one end is connected to the outlet end of the condensation mechanism 5, and the other end is connected to a second valve 16. The inner wall of the adsorption tube is coated with an adsorption material that can adsorb volatile organic compounds. After the volatile organic compounds are adsorbed onto the inner wall of the adsorption tube, nitrogen can be discharged through the second valve 16. The pressure tank 8 has an inlet and an outlet. The inlet of the pressure tank 8 is connected to the second valve 16, and the outlet is connected to the detection mechanism 9. The housing is equipped with a heating plate, which can heat the volatile organic compounds adsorbed on the inner wall of the adsorption tube so that the volatile organic compounds reach a set temperature and volatilize and enter the pressure tank 8 through the second valve 16.

[0039] Specifically, the adsorption tube is curved or spiral-shaped. This allows the volatile organic compounds to fully contact the inner wall of the adsorption tube, thus ensuring that the volatile organic compounds are fully absorbed.

[0040] Preferably, the adsorbent material is activated carbon or zeolite molecular sieve. The set temperature is 180°C.

[0041] Specifically, when the condensation mechanism 5 discharges volatile organic compounds and nitrogen, the power pump 7 starts and provides power. The volatile organic compounds are adsorbed on the inner wall of the adsorption tube, and the nitrogen is further discharged from the adsorption tube and discharged through the power pump 7.

[0042] In one specific embodiment, the detection device 9 is a gas chromatography-mass spectrometry (GC-MS) instrument or a gas chromatograph.

[0043] Specifically, the switching valve 3 has five valve ports. The sampling needle 2 is connected to one of these valve ports, and the inlet pipe 23 and outlet pipe 24 are connected to their respective valve ports. It also includes a first valve 15 and a third valve 17. The first valve 15 has four valve ports. The nitrogen mechanism 4 is connected to one of these valve ports, the inlet end of the condensation mechanism 5 is connected to one of these valve ports, and the air pump 10 is connected to its corresponding valve port. A corresponding valve port of the first valve 15 is connected to a corresponding valve port of the switching valve 3 via a pipe. The third valve 17 has three valve ports. The input end of the peristaltic pump 11 is connected to a corresponding valve port of the third valve 17, and the output end of the output pump 13 is connected to a corresponding valve port of the third valve 17 via a pipe. A corresponding valve port of the third valve 17 is connected to a corresponding valve port of the switching valve 3 via a pipe. Any two valve ports of the switching valve 3, first valve 15, second valve 16, and third valve 17 can be connected together.

[0044] This invention also provides a method for using a system for collecting and analyzing volatile organic compounds in groundwater, specifically including the following steps: The sampling needle 2 is inserted into the water area to be tested to collect water samples, and the collected water samples are pumped into the purge tube 1. The nitrogen mechanism 4 is activated, causing it to blow nitrogen into the purge tube 1 through the inlet pipe 23 and the capillary tube 20. This causes the nitrogen to form bubbles in the water sample and float to the surface, thereby separating the volatile organic compounds in the water sample. The nitrogen mechanism 4 is then deactivated when the pressure inside the purge tube 1 reaches the set value. The volatile organic compounds in the purge pipe 1 are allowed to enter the condensation mechanism 5 through the outlet pipe 24. The condensation mechanism 5 condenses the water vapor in the condensation mechanism 5 to form water, then filters the water vapor, collects the volatile organic compounds, and discharges nitrogen. The volatile organic compounds are introduced into the testing unit 9 for testing.

[0045] In one specific embodiment, a one-way valve 18 is provided on the inlet pipe 23, and a pressure valve 19 is provided on the outlet pipe 24. The pressure valve 19 is normally closed. The nitrogen mechanism 4 blows nitrogen into the purge pipe 1. After the pressure in the purge pipe 1 reaches the set value, the pressure valve 19 opens to allow the nitrogen and volatile organic compounds in the purge pipe 1 to enter the condensation mechanism 5. After the pressure in the purge pipe 1 returns to normal, the pressure valve 19 closes.

[0046] In one specific embodiment, a cleaning mechanism is also included, which is connected to the inlet pipe 23 of the purge pipe 1; Before use, the cleaning mechanism is used to clean the purge pipe 1; After use, the cleaning mechanism is used to clean the purge pipe 1.

[0047] The following is a detailed description of the usage process and working principle of the volatile organic compound collection and analysis system in groundwater according to the present invention.

[0048] Start the output pump 13 to pump distilled water from the water tank 14 into the purge pipe 1 to clean the purge pipe 1. Then start the peristaltic pump 11 to pump the water in the purge pipe 1 into the waste bin 12. Start the air pump 10 to blow air into the purge pipe 1 to blow out the water vapor remaining in the purge pipe 1.

[0049] Then, the sampling end of the sampling needle 2 is inserted into the water area to be tested to collect water samples. The injection pump is then started to pump the water samples into the purge tube 1 through the inlet pipe 23.

[0050] Then, the nitrogen mechanism 4 is activated, causing nitrogen to pass through the switching valve 3 and inlet pipe 23 into the capillary tube 20. The nitrogen then enters the lower chamber of the purge tube 1 through the outlet of the capillary tube 20. The nitrogen rises in the water sample and breaks into smaller bubbles through the vent holes of the sieve plate 21, entering the upper chamber and thus thoroughly agitating the water sample. The nitrogen in the upper chamber re-enters the capillary tube 20 through the circulation hole 22 and then enters the lower chamber through the outlet of the capillary tube 20, continuously circulating and causing volatile organic compounds in the water sample to evaporate.

[0051] By continuously blowing nitrogen, the pressure inside the purge pipe 1 rises continuously until it reaches 0.3 MPa. Then, the nitrogen mechanism 4 is shut off, and the pressure valve 19 and the power pump 17 are opened. This allows the nitrogen and volatile organic compounds in the purge pipe 1 to enter the condensation mechanism 5 through the outlet pipe 24. The condensation mechanism 5 continuously cools the air, causing the residual water vapor to form water. The nitrogen and volatile organic compounds then enter the adsorption mechanism 6, where the volatile organic compounds are adsorbed onto the inner wall of the adsorption tube. Finally, the nitrogen is discharged through the power pump 7.

[0052] After the pressure in the purge pipe 1 returns to normal, shut off the power pump 17 and the pressure valve 19.

[0053] Then, the heating plate of the adsorption mechanism 6 is activated to heat the adsorption tube, causing the volatile organic compounds adsorbed on the inner wall of the adsorption tube to volatilize and enter the pressure tank 8. The volatile organic compounds collected in the pressure tank 8 are then sent to the detection mechanism 9 for testing.

[0054] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. Those skilled in the art can make various modifications to the present invention based on the above description. Therefore, certain details in the embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention shall be defined by the appended claims.

Claims

1. A system for collecting and analyzing volatile organic compounds in groundwater, comprising: The utility model relates to a water sample collection device, comprising: a sampling needle (2) having a collection end and a fixed end, the collection end being insertable into a water area to be detected to collect a water sample; a purge pipe (1) having an outlet and an inlet at the top, the outlet of the purge pipe (1) being connected with an outlet pipe (24), the inlet being connected with an inlet pipe (23), one end of the inlet pipe (23) being connected to the sampling needle (2), and the water sample in the sampling needle (2) being able to enter the purge pipe (1); a plurality of capillary tubes (20) being arranged in the purge pipe (1), one end being connected to the inlet and the other end extending to the bottom wall of the purge pipe (1), when the purge pipe (1) has a water sample, one end of the capillary tube (20) away from the inlet of the purge pipe (1) being inserted into the water sample; a nitrogen mechanism (4) being connected to the inlet pipe (23) of the purge pipe (1), after the water sample enters the purge pipe (1), the nitrogen mechanism (4) being able to blow nitrogen into the purge pipe (1) through the inlet pipe (23) and the capillary tube (20), so that the nitrogen forms bubbles in the water sample and floats up, so that the pressure in the purge pipe (1) reaches a set value, thereby causing volatile organic compounds to be desorbed from the water sample; a condensing mechanism (5) having an inlet end and an outlet end, the inlet end being connected to one end of the outlet pipe (24), and being able to filter water vapor in the desorbed volatile organic compounds; a detection mechanism (9) being connected to the outlet end of the condensing mechanism (5) and being used for detecting the filtered volatile organic compounds.

2. The system for collecting and analyzing volatile organic compounds in groundwater according to claim 1, wherein: The inlet pipe (23) is provided with a one-way valve (18), and the outlet pipe (24) is provided with a pressure valve (19); The pressure valve (19) is in a normally closed state, when high pressure is generated in the purge pipe (1) and the pressure value reaches a set value, the pressure valve (19) is opened to enable the nitrogen and the volatile organic compounds in the purge pipe (1) to enter the condensing mechanism (5), and when the pressure in the purge pipe (1) returns to normal, the pressure valve (19) is closed again.

3. The system for collecting and analyzing volatile organic compounds in groundwater according to claim 1, wherein: Further comprising: a sieve plate (21) being arranged in the purge pipe (1) and dividing the purge pipe (1) into two chambers, the sieve plate (21) being provided with a plurality of air-permeable holes, and the sieve plate (21) being located in the water sample when the purge pipe (1) has a water sample; one end of the capillary tube (20) being located in the upper chamber and being connected to the inlet pipe (23), the other end of the capillary tube (20) extending into the lower chamber through the sieve plate (21), and the one end of the capillary tube (20) in the upper chamber being provided with a circulation hole (22), nitrogen in the upper chamber being able to enter the capillary tube (20) through the circulation hole (22) and re-enter the lower chamber through the capillary tube (20).

4. The system for collecting and analyzing volatile organic compounds in groundwater according to claim 1, wherein: Further comprising a cleaning mechanism being connected to the inlet pipe (23) of the purge pipe (1) and being used for cleaning the purge pipe (1).

5. The system for collecting and analyzing volatile organic compounds in groundwater according to claim 4, wherein: The cleaning mechanism comprises: An output pump (13) is connected to the water tank (14), the output pump (13) has a first output end and a first input end, the first output end of the output pump (13) is connected to the inlet pipe (23), and the first input end is connected to the water tank (14), the water tank (14) contains distilled water, and the output pump (13) can pump the distilled water in the water tank (14) into the purge pipe (1) for cleaning; A peristaltic pump (11) is connected to the waste barrel (12), the peristaltic pump (11) has a second output end and a second input end, the second input end of the peristaltic pump (11) is connected to the outlet pipe (24), and the second output end is connected to the waste barrel (12), the peristaltic pump (11) can pump the water used for cleaning the purge pipe (1) into the waste barrel (12); An air pump (10) is connected to the inlet pipe (23) and can blow air into the purge pipe (1) to remove water vapor in the purge pipe (1).

6. The system for collecting and analyzing volatile organic compounds in groundwater according to claim 1, wherein: It also includes an adsorption mechanism (6) and a pressure tank (8), the adsorption mechanism (6) includes a shell and an adsorption pipe, the adsorption pipe is arranged in the shell and one end is connected to the outlet end of the condensation mechanism (5), the other end is connected with a second valve (16), the inner wall of the adsorption pipe is coated with an adsorption material capable of adsorbing volatile organic compounds, and after the volatile organic compounds are adsorbed to the inner wall of the adsorption pipe, nitrogen can be discharged through the second valve (16); The pressure tank (8) has an inlet and an outlet, the inlet of the pressure tank (8) is connected with the second valve (16), and the outlet is connected with the detection mechanism (9); The shell is provided with a heating plate, which can heat the volatile organic compounds adsorbed on the inner wall of the adsorption pipe, so that the volatile organic compounds volatilize at a set temperature and enter the pressure tank (8) through the second valve (16).

7. The system for collecting and analyzing volatile organic compounds in groundwater according to claim 1, wherein: The detection mechanism (9) is a GC-MS or gas chromatograph.

8. A method of using the groundwater volatile organic compound collection and analysis system of claim 1, comprising: Specifically includes the following steps: Insert the collection end of the sampling needle (2) into the water area to be detected to collect water samples, and pump the collected water samples into the purge pipe (1); Start the nitrogen mechanism (4), make the nitrogen mechanism (4) blow nitrogen into the purge pipe (1) through the inlet pipe (23) and the capillary tube (20), so that the nitrogen forms bubbles in the water sample and floats up, thereby separating the volatile organic compounds in the water sample, until the pressure in the purge pipe (1) reaches a set value to close the nitrogen mechanism (4); Make the volatile organic compounds in the purge pipe (1) enter the condensation mechanism (5) through the outlet pipe (24), make the condensation mechanism (5) condense the water vapor in it to form water, then filter the water vapor, collect the volatile organic compounds, and discharge the nitrogen; Make the volatile organic compounds enter the detection mechanism (9) to detect the volatile organic compounds.

9. The method of using a volatile organic compound collection and analysis system in groundwater of claim 8, wherein: The inlet pipe (23) is provided with a one-way valve (18), and the outlet pipe (24) is provided with a pressure valve (19), which is in a normally closed state; The nitrogen mechanism (4) blows nitrogen into the purge pipe (1), and when the pressure in the purge pipe (1) reaches a set value, the pressure valve (19) opens to make the nitrogen and volatile organic compounds in the purge pipe (1) enter the condensing mechanism (5); After the pressure in the purge pipe (1) returns to normal, the pressure valve (19) is closed.

10. The method of using a volatile organic compound collection and analysis system in groundwater of claim 8, wherein: It also includes a cleaning mechanism connected to the inlet pipe (23) of the purge pipe (1); Before use, the purge pipe (1) is cleaned using the cleaning mechanism; After use, the purge pipe (1) is cleaned using the cleaning mechanism.

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