Detection equipment and method for field analysis of volatile organic compounds in soil

Abstract

The invention discloses detection equipment and method for on-site analysis of volatile organic compounds in soil, the detection equipment comprises a shell, a sample heating and purging unit, a water removal unit, an adsorption and desorption unit and a separation and detection unit, the shell is used for mounting and fixing other units, the sample heating and purging unit is used for heating a sample, and the water removal unit is used for removing water. The water removal unit is used for carrying out refrigeration water removal and carrier gas preheating on sample gas, the adsorption and desorption unit is used for carrying out secondary water removal on the sample gas and adsorbing and desorbing volatile organic compounds, the separation and detection unit is used for detecting the total amount, variety and content of volatile pollutants, soil is heated by the sample heating and purging unit, and after a sample is volatilized, the sample is sent to the detection unit. Purge gas enters the water removal unit for refrigeration and water removal and then is conveyed to the adsorption and desorption unit for secondary water removal, the purge gas containing volatile organic pollutants is adsorbed and collected, an adsorption pipe is heated after collection is completed, and adsorbed sample gas is desorbed and conveyed to the separation and detection unit for total pollution amount, type and content detection.

Description

Technical Field

[0001] This invention relates to the field of environmental testing technology, specifically to a testing device and method for on-site analysis of volatile organic compounds in soil. Background Technology

[0002] With increasing environmental awareness, soil pollution has become a global concern. Volatile organic compounds (VOCs), a significant component of soil pollution, have a wide range of sources, including but not limited to fuels, solvents, paints, adhesives, and refrigerants. The emission and leakage of VOCs not only affect soil quality but can also harm the ecological environment and human health.

[0003] Currently, the detection of volatile organic pollutants (VOCs) in soil typically involves on-site sampling followed by laboratory pretreatment and analysis. According to standards, laboratories often employ headspace or purge pretreatment methods, adding pure water or ethanol as solvent to the sample, then heating the sample at a constant temperature before extracting VOCs using headspace or purge collection. This method is time-consuming, cumbersome, and requires large and energy-intensive equipment, making it unsuitable for on-site analysis. Furthermore, the moisture content of the sample is measured separately using an oven drying method. Overall, current methods have poor timeliness and are insufficient to meet the needs of applications requiring on-site or rapid detection of pollutants in soil, such as site pollution investigations.

[0004] Therefore, accurate and rapid on-site analysis of VOCs in soil has significant environmental implications and application value. Summary of the Invention

[0005] The purpose of this invention is to provide a detection device and method for on-site analysis of volatile organic compounds in soil, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: The aforementioned detection device for on-site analysis of volatile organic compounds in soil includes a shell, a sample heating and purging unit, a dehydration unit, an adsorption-desorption unit, and a separation and detection unit. The shell is placed on a horizontal foundation and consists of a front shell, a rear shell, and an outer shell. The front shell and the rear shell are fixedly connected, with the front shell fixedly installed inside the outer shell, and the rear shell fixedly installed inside the outer shell. The sample heating and purging unit is fixedly connected to the front shell and connected to the dehydration unit via a pipeline. The dehydration unit is fixedly installed on the end face of the front shell near the horizontal foundation. The dehydration unit is connected to the adsorption-desorption unit via a pipeline, with the adsorption-desorption unit fixedly installed on the end face of the front shell away from the horizontal foundation. The adsorption-desorption unit is connected to the separation and detection unit via a pipeline, with the separation and detection unit fixedly installed on the end face of the front shell away from the horizontal foundation.

[0007] The housing is used for mounting and fixing the other units. The sample heating and purging unit is used for sample heating. The dehydration unit is used for cooling and dehydrating the sample gas and preheating the carrier gas. The adsorption and desorption unit is used for secondary dehydration of the sample gas and adsorption and desorption of volatile organic compounds. The separation and detection unit is used to detect the total amount, type and content of volatile pollutants. After the soil is heated by the sample heating and purging unit, the sample evaporates. The purging gas enters the dehydration unit for cooling and dehydration and is then transported to the adsorption and desorption unit for secondary dehydration. The purging gas containing volatile organic pollutants is adsorbed and collected. After collection, the adsorption tube is heated. The adsorbed sample gas is desorbed and transported to the separation and detection unit for detection of the total amount, type and content of pollutants.

[0008] Furthermore, the sample heating and purging unit includes a circulating pump, a purging tube, a heating plate, and an insulation shell. The circulating pump is fixedly installed on the upper surface of the front shell near the horizontal foundation. The circulating pump is connected to one end of the purging tube, which is fixedly installed at the end of the front shell away from the horizontal foundation. There are two heating plates, which are hinged together and fitted onto the outer surface of the purging tube. The heating plates are fixedly connected to the insulation shell, which consists of two shells surrounding the heating plates. The insulation shells are fixedly installed inside the shell. The other end of the purging tube is connected to a water removal unit pipe.

[0009] The staff weighed the soil sample to be tested and put it into the purge tube. At this time, the controller controlled the heating plate to heat the soil sample in the purge tube, which evaporated the moisture and volatile organic compounds in the soil. The controller controlled the circulation pump to start, which used high-purity nitrogen to quickly purge the moisture and volatile organic compounds in the soil into the dewatering unit.

[0010] Furthermore, the water removal unit includes a water remover and a solenoid valve. The water remover is connected to a purge pipe. The water remover consists of a front-end heat exchanger and a rear-end refrigeration module. The water remover is fixedly installed on the upper surface of the front housing near the horizontal foundation. The solenoid valve is fixedly installed on the upper surface of the front housing near the horizontal foundation. The water outlet of the water remover is connected to the solenoid valve, and the air outlet of the water remover is connected to the adsorption / desorption unit pipe.

[0011] High-purity nitrogen gas carries soil moisture and volatile organic compounds into the dehydrator, where it is cooled by heat exchange with cold air, causing the moisture in the sample gas to condense and removing moisture from the soil sample. At the same time, the heat exchanged preheats the carrier gas, reducing the impact of moisture on the detection system and lowering system energy consumption. The pre-dried gas then passes through a ten-way membrane valve and enters the adsorption-desorption unit.

[0012] Furthermore, the adsorption-desorption unit includes a dual-path cold trap, a desorption tube, and a ten-way membrane valve. The inlet and outlet of the desorption tube are both connected to the ten-way membrane valve. The dual-path cold trap is fixedly installed at the end of the front housing away from the horizontal foundation. The desorption tube is fixedly installed inside the dual-path cold trap and consists of two quartz tubes, one of which is empty and the other is filled with adsorption packing material. A heating wire is wound around the outside of the desorption tube. The ten-way membrane valve is fixedly installed on the front housing and between the purge tube and the flame ionization detector. A chromatographic column is uniformly wound around the surface of the ten-way membrane valve and connected to it.

[0013] After dehydration, the volatile organic compounds (VOCs) enter the desorption tube, where the empty tube further dehydrates the sample gas. Meanwhile, the adsorption packing inside another quartz tube adsorbs the VOCs. After adsorption, the controller heats the desorption tube and switches the ten-port membrane valve, altering the gas flow path. High-purity nitrogen carries the desorbed VOC components through the ten-port membrane valve into a gas chromatography column for separation. The total amount of volatile pollutants, as well as the composition and content of VOCs, are detected by a flame ionization detector. Simultaneously, the condensate in the empty tube is purged from the system by carrier gas.

[0014] Furthermore, the separation and detection unit includes a flame ionization detector and a chromatographic column. The flame ionization detector is connected to the chromatographic column and is fixedly installed at the end of the front housing away from the horizontal base. The outlet of the flame ionization detector extends out of the outer surface of the housing away from the horizontal base. The chromatographic column is wrapped around the outside of the ten-way membrane valve. The chromatographic column includes two columns: a capillary chromatographic column and a total hydrocarbon chromatographic column, which are connected to the ten-way membrane valve and the flame ionization detector.

[0015] During the process of the controller controlling the hydrogen flame ionization detector to detect volatile organic compounds, the EPC board controls the carrier gas pressure to provide a constant flow rate for the hydrogen flame ionization detector to meet the detection requirements. The current or voltage signal obtained from the hydrogen flame ionization detector is fed back to the controller for analysis and output of results, thereby realizing the detection of gases in soil samples.

[0016] Furthermore, a powder filter is fixedly connected to one end of the purge pipe near the horizontal foundation, and the heating plate is electrically connected to a temperature sensor.

[0017] To effectively remove these particulate matter and suspended solids, prevent column clogging, and ensure smooth chromatographic analysis, a powder filter is fixedly connected to the purge tube near the horizontal base. At the same time, to allow volatile organic compounds to evaporate quickly and to heat the soil sample, thereby improving detection results, the heating plate is electrically connected to the temperature sensor.

[0018] Furthermore, a temperature controller, a power indicator, and a power switch are provided on one side of the outer surface of the housing, and a fan and a carrier air inlet are provided on the other side of the outer surface of the housing.

[0019] To facilitate convenient and quick control of the device's startup and real-time monitoring of temperature and power, a temperature controller, power indicator, and power switch are installed on the outer surface of one side of the housing. To prevent the device from generating heat during operation and affecting its lifespan, a fan is installed on the housing. To facilitate smooth detection, a carrier gas inlet is provided on the housing to carry volatile organic compounds into the flame ionization detector.

[0020] The detection method for on-site analysis of volatile organic compounds in soil includes the following steps: S1. Sample loading; Step S1 includes the following specific steps: S11. Weigh the soil sample from the area to be tested, then fill the sample into the purge tube and weigh it. S2, Heating; Step S2 includes the following specific steps: S21. Heat the soil sample to evaporate the moisture and volatile organic compounds in the soil into the carrier gas; S3, water removal and adsorption; Step S3 includes the following specific steps: S31. The carrier gas undergoes heat exchange and cooling to remove water twice, and the organic matter to be tested in the sample gas is adsorbed by the adsorption tube. S4. Desorption and detection; Step S4 includes the following specific steps: S41. The adsorption tube is heated, the sample to be tested is desorbed, and carried by the carrier gas to the chromatographic column for detection. The condensed water evaporates and is purged out of the system by the carrier gas. The sample is separated in the chromatographic column and detected by FID. S42. After the test is completed, weigh the purge pipe and calculate the moisture content.

[0021] Compared with existing technologies, the beneficial effects achieved by this invention are as follows: This invention heats the soil sample in the purge tube using a heating plate in the sample heating and purging unit, causing the moisture and volatile organic compounds in the soil to evaporate. Then, the sample is cooled by heat exchange with cold air through a dehydrator in the dehydration unit, causing the moisture in the sample gas to condense and thus removing moisture from the soil sample. Simultaneously, the heat exchanged preheats the carrier gas, reducing the impact of moisture on the detection system. Furthermore, the empty tube in the desorption tube of the adsorption-desorption unit further removes moisture from the sample gas, thereby improving the accuracy of the detection. Meanwhile, the adsorption packing material inside another quartz tube effectively removes volatile organic compounds. Adsorption occurs, and after adsorption is complete, the controller heats the desorption tube and controls the 10-port membrane valve to change the gas flow path. High-purity nitrogen carries the desorbed volatile organic compound gas components through the 10-port membrane valve into the gas chromatography column for separation. The total amount of volatile pollutants, as well as the composition and content of volatile organic compounds, are detected by a flame ionization detector. At the same time, the condensate in the empty tube is purged out of the system by the carrier gas. A single injection can simultaneously detect the total amount of volatile pollutants, the types and contents of characteristic pollutants, and the moisture content of the sample. In addition, this device has the advantages of small size, low energy consumption, rapid analysis, and convenient on-site use through its integrated design. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall appearance and structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the present invention; Figure 3 This is a schematic diagram showing the installation positions of each component of the water removal unit of the present invention; Figure 4 This is a schematic diagram of the mounting positions of the sample heating and purging unit, the adsorption and desorption unit, and the partial separation and detection unit of the present invention. Figure 5 This is a schematic diagram of the installation positions of part of the separation detection unit and part of the housing of the present invention; In the diagram: 1. Shell; 11. Front shell; 12. Rear shell; 13. Outer shell; 131. Temperature controller; 132. Power indicator; 133. Power switch; 134. Fan; 135. Carrier gas inlet; 2. Sample heating and purging unit; 21. Circulation pump; 22. Purge tube; 23. Heating plate; 24. Insulation shell; 3. Dehydration unit; 31. Dehydrator; 32. Solenoid valve; 4. Adsorption and desorption unit; 41. Dual-channel cold trap; 42. Desorption tube; 43. Ten-way membrane valve; 5. Separation and detection unit; 51. Flame ionization detector; 52. Chromatographic column. Detailed Implementation

[0023] 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.

[0024] The present invention provides the following technical solution: like Figure 1 , 2 As shown in Figures 3 and 5, a detection device for on-site analysis of volatile organic compounds in soil includes a housing 1, a sample heating and purging unit 2, a dehydration unit 3, an adsorption and desorption unit 4, and a separation and detection unit 5. The housing 1 is placed on a horizontal foundation and consists of a front housing 11, a rear housing 12, and an outer shell 13. The front housing 11 and the rear housing 12 are fixedly connected and the front housing 11 is fixedly installed inside the outer shell 13. The rear housing 12 is fixedly installed inside the outer shell 13. The sample heating and purging unit 2 is fixedly connected to the front housing 11 and is piped to the dehydration unit 3. The dehydration unit 3 is fixedly installed on the end face of the front housing 11 near the horizontal foundation. The dehydration unit 3 is piped to the adsorption and desorption unit 4 and is fixedly installed on the end face of the front housing 11 away from the horizontal foundation. The adsorption and desorption unit 4 is piped to the separation and detection unit 5 and is fixedly installed on the end face of the front housing 11 away from the horizontal foundation.

[0025] The housing 1 is used for the installation and fixation of the other units. The sample heating and purging unit 2 is used for sample heating. The dehydration unit 3 is used for cooling and dehydrating the sample gas and preheating the carrier gas. The adsorption and desorption unit 4 is used for secondary dehydration of the sample gas and adsorption and desorption of volatile organic compounds. The separation and detection unit 5 is used to detect the total amount, type and content of volatile pollutants. After the soil is heated by the sample heating and purging unit 2 and the sample volatilizes, the purging gas enters the dehydration unit 3 for cooling and dehydration and is then transported to the adsorption and desorption unit 4 for secondary dehydration. The purging gas containing volatile organic pollutants is adsorbed and collected. After collection, the adsorption tube is heated. The adsorbed sample gas is desorbed and transported to the separation and detection unit 5 for detection of the total amount, type and content of pollutants.

[0026] like Figure 3 , 4 As shown, the sample heating and purging unit 2 includes a circulating pump 21, a purging pipe 22, a heating plate 23, and an insulation shell 24. The circulating pump 21 is fixedly installed on the upper surface of the front housing 11 near the horizontal foundation. The circulating pump 21 is connected to one end of the purging pipe 22. The purging pipe 22 is fixedly installed on the end of the front housing 11 away from the horizontal foundation. There are two heating plates 23, which are hinged together. The heating plates 23 are fitted on the outer surface of the purging pipe 22. The heating plates 23 are fixedly connected to the insulation shell 24. There are two insulation shells 24, which surround the heating plates 23. The insulation shells 24 are fixedly installed inside the housing 1. The other end of the purging pipe 22 is connected to the dewatering unit 3.

[0027] The staff weighed the soil sample to be tested and put it into the purge tube 22. At this time, the controller controlled the heating plate 23 to heat the soil sample in the purge tube 22, so that the moisture and volatile organic compounds in the soil would evaporate. The controller controlled the circulation pump 21 to start, so that high-purity nitrogen would drive the rapid purge of the moisture and volatile organic compounds in the soil into the dewatering unit 3.

[0028] like Figure 3 As shown, the water removal unit 3 includes a water remover 31 and a solenoid valve 32. The water remover 31 is connected to the purge pipe 22. The water remover 31 consists of a front heat exchanger and a rear refrigeration module. The water remover 31 is fixedly installed on the upper surface of the front housing 11 near the horizontal foundation. The ten-way membrane valve 43 is fixedly installed on the upper surface of the front housing 11 away from the horizontal foundation. The surface of the ten-way membrane valve 43 is evenly wrapped with a chromatographic column and a total hydrocarbon column. The ten-way membrane valve 43 is connected to one end of the chromatographic column and the total hydrocarbon column. The solenoid valve 32 is fixedly installed on the upper surface of the front housing 11 near the horizontal foundation. The water remover 31 is connected to the ten-way membrane valve 43 through the solenoid valve 32. The ten-way membrane valve 43 is connected to the adsorption-desorption unit 4.

[0029] High-purity nitrogen gas carries soil moisture and volatile organic compounds into the dehydrator 31, where it is cooled by heat exchange with cold air, causing the moisture in the sample gas to condense and thus removing water from the soil sample. At the same time, the heat exchange preheats the carrier gas, reducing the impact of moisture on the detection system and lowering system energy consumption. Meanwhile, the volatile organic compound gas is opened by the solenoid valve 32 and enters the ten-way membrane valve 43, which then enters the adsorption-desorption unit 4.

[0030] like Figure 4 As shown, the adsorption-desorption unit 4 includes a dual-path cold trap 41, a desorption tube 42, and a ten-way membrane valve 43. The inlet and outlet of the desorption tube 42 are both connected to the ten-way membrane valve 43. The dual-path cold trap 41 is fixedly installed at the end of the front housing 11 away from the horizontal foundation. The desorption tube 42 is fixedly installed inside the dual-path cold trap 41. The desorption tube 42 consists of two quartz tubes, one of which is empty and the other is filled with adsorption packing. A heating wire is wound around the outside of the desorption tube 42. The ten-way membrane valve 43 is fixedly installed on the front housing 11 and between the purge tube 22 and the ten-way membrane valve 43. Two ports of the ten-way membrane valve 43 are connected to the chromatographic column and the total hydrocarbon column pipes that are uniformly wound around the surface of the ten-way membrane valve 43. The other port of the ten-way membrane valve 43 is connected to the separation and detection unit 5.

[0031] After dehydration, the volatile organic compounds (VOCs) gas enters the desorption tube 42. The empty tube further dehydrates the sample gas, thereby improving the accuracy of detection. Meanwhile, the adsorption packing inside another quartz tube adsorbs the VOCs. At this time, the controller applies current to the heating wire to heat the desorption tube 42 and controls the switching of the ten-way membrane valve 43, which switches the gas flow path. High-purity nitrogen is used for backflushing, and the components desorbed from the VOCs gas are carried into the gas chromatography column through the ten-way membrane valve 43 for separation and detection of the total amount of volatile pollutants and the content of specific volatile substances. After that, the components enter the separation and detection unit 5 through the ten-way membrane valve 43.

[0032] like Figure 4 , 5 As shown, the separation and detection unit 5 includes a flame ionization detector 51 and a chromatographic column 52. The flame ionization detector 51 is connected to the ten-way membrane valve 43 via a pipeline. The flame ionization detector 51 is fixedly installed at the end of the front housing 11 away from the horizontal base. The outlet of the flame ionization detector 51 extends out of the outer surface of the outer housing 13 away from the horizontal base. The flame ionization detector 51 is slidably connected to the outer housing 13. The chromatographic column 52 is fixedly installed at the end of the rear housing 12 near the horizontal base. The chromatographic column 52 is connected to the ten-way membrane valve 43 via a pipeline.

[0033] During the detection of volatile organic compounds by the hydrogen flame ionization detector 51 controlled by the controller, the carrier gas pressure controlled by the chromatographic column 52 provides a constant flow rate for the hydrogen flame ionization detector 51 to meet the detection requirements. The current or voltage signal obtained from the hydrogen flame ionization detector 51 is fed back to the controller for analysis and output of results, thereby realizing the detection of gases in the soil sample.

[0034] like Figure 4 As shown, a powder filter is fixedly connected to one end of the purge pipe 22 near the horizontal foundation, and the heating plate 23 is electrically connected to the temperature sensor.

[0035] In order to effectively remove these particulate matter and suspended matter, prevent column clogging, and ensure smooth chromatographic analysis, a powder filter is fixedly connected to the purge tube 22 near the horizontal base. At the same time, in order to facilitate the heating of soil samples and promote the volatilization of volatile organic compounds, thereby improving the detection effect, the heating plate 23 is electrically connected to the temperature sensor.

[0036] like Figure 1 , 5 As shown, a temperature controller 131, a power indicator 132 and a power switch 133 are provided on one side of the outer surface of the housing 13, and a fan 134 and a carrier air inlet 135 are provided on the other side of the outer surface of the housing 13.

[0037] To facilitate convenient and quick control of the device's startup and real-time monitoring of temperature and power, a temperature controller 131, a power indicator 132, and a power switch 133 are provided on the outer surface of one side of the housing 13. To prevent the device from generating heat during operation and affecting its lifespan, a fan 134 is provided on the housing 13. To facilitate smooth detection, a carrier gas is introduced to carry volatile organic compounds into the hydrogen flame ionization detector 51 for detection. Therefore, a carrier gas inlet 135 is provided on the housing 13 to facilitate the entry of the carrier gas.

[0038] A detection method for on-site analysis of volatile organic compounds in soil includes the following steps: S1. Sample loading; Step S1 includes the following specific steps: S11. Weigh the soil sample from the area to be tested, then fill the sample into the purge tube and weigh it. S2, Heating; Step S2 includes the following specific steps: S21. Heat the soil sample to evaporate the moisture and volatile organic compounds in the soil into the carrier gas; S3, water removal and adsorption; Step S3 includes the following specific steps: S31. The carrier gas undergoes heat exchange and cooling to remove water twice, and the organic matter to be tested in the sample gas is adsorbed by the adsorption tube. S4. Desorption and detection; Step S4 includes the following specific steps: S41. The adsorption tube is heated, the sample to be tested is desorbed, and carried by the carrier gas to the chromatographic column for detection. The condensed water evaporates and is purged out of the system by the carrier gas. The sample is separated in the chromatographic column and detected by FID. S42. After the test is completed, weigh the purge pipe and calculate the moisture content.

[0039] Working principle of the invention: The staff weighs the soil sample to be tested and loads it into the purge tube 22. At this time, the controller controls the heating plate 23 to heat the soil sample in the purge tube 22, causing the moisture and volatile organic compounds in the soil to evaporate. The controller then starts the circulating pump 21, which uses high-purity nitrogen to quickly purge the moisture and volatile organic compounds from the soil into the dehydrator 31. Through heat exchange with cold air, the sample gas is cooled, causing the moisture in the sample gas to condense, thus removing water from the soil sample. Simultaneously, the heat exchange preheats the carrier gas, reducing the impact of moisture on the detection system and lowering system energy consumption. The volatile organic compound gas is then opened by the solenoid valve 32 and enters the ten-way diaphragm valve 43. After dehydration, the volatile organic compound gas enters the desorption tube 42 through the ten-way diaphragm valve 43, where the empty tube further removes water from the sample gas, thereby improving efficiency. The accuracy of the detection is improved. Meanwhile, the adsorption packing inside another quartz tube adsorbs volatile organic compounds. At this time, the controller applies current to the heating wire to heat the desorption tube 42 and controls the switching of the ten-way membrane valve 43, switching the gas flow path. High-purity nitrogen is used for backflushing, and the components desorbed from the volatile organic compounds are carried through the ten-way membrane valve 43 into the gas chromatography column for separation and detection of the total amount of volatile pollutants and the content of specific volatile substances. After passing through the ten-way membrane valve 43, they enter the hydrogen flame ionization detector 51. During the detection of volatile organic compounds by the hydrogen flame ionization detector 51, the controller controls the carrier gas pressure through the chromatographic column 52 to provide a constant flow rate for the hydrogen flame ionization detector 51. The current or voltage signal obtained from the hydrogen flame ionization detector 51 is fed back to the controller for analysis and output of results, thus realizing the detection of soil sample gas.

[0040] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0041] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A detection device for on-site analysis of volatile organic compounds in soil, Features: A detection device for on-site analysis of volatile organic matter in soil comprises a housing (1), a sample heating and purging unit (2), a water removal unit (3), an adsorption and desorption unit (4) and a separation and detection unit (5); the housing (1) is placed on a horizontal foundation; the housing (1) is composed of a front housing (11), a rear housing (12) and an outer housing (13); the front housing (11) and the rear housing (12) are fixedly connected; the front housing (11) is fixedly mounted inside the outer housing (13); the rear housing (12) is fixedly mounted inside the outer housing (13); the sample heating and purging unit (2) and the water removal unit (3) are fixedly mounted inside the outer housing (13); The purge unit (2) is fixedly connected to the front shell (11); the sample heating purge unit (2) is connected to the dewatering unit (3) via a pipeline; the dewatering unit (3) is fixedly mounted on an end surface of the front shell (11) close to a horizontal foundation; the dewatering unit (3) is connected to the adsorption and desorption unit (4) via a pipeline; the adsorption and desorption unit (4) is fixedly mounted on an end surface of the front shell (11) away from a horizontal foundation; the adsorption and desorption unit (4) is connected to the separation and detection unit (5) via a pipeline; the separation and detection unit (5) is fixedly mounted on an end surface of the front shell (11) away from a horizontal foundation.

2. A detection device for on-site analysis of volatile organic compounds in soil according to claim 1, Features: The sample heating and purging unit (2) comprises a circulation pump (21), a purging pipe (22), a heating plate (23) and an insulation shell (24). The circulation pump (21) is fixedly mounted on the upper surface of one end of the front shell (11) close to the horizontal foundation. The circulation pump (21) is connected to one end of the purging pipe (22) by a pipeline. The purging pipe (22) is fixedly mounted on the end of the front shell (11) away from the horizontal foundation. There are two heating plates (23). The two heating plates (23) are hingedly connected. The heating plates (23) are sleeved on the outer surface of the purging pipe (22). The heating plates (23) are fixedly connected to the insulation shell (24). There are two insulation shells (24). The two insulation shells (24) surround the outside of the heating plates (23). The insulation shell (24) is fixedly mounted inside the shell (1). The other end of the purging pipe (22) is connected to the dewatering unit (3) by a pipeline.

3. A detection device for on-site analysis of volatile organic compounds in soil according to claim 2, Features: The dewatering unit (3) comprises a dewatering device (31) and a switch solenoid valve (32); the dewatering device (31) is connected to the purge pipe (22) by a pipeline; the dewatering device (31) is composed of a front-end heat exchanger and a rear-end refrigeration module; the dewatering device (31) is fixedly mounted on the upper surface of one end of the front shell (11) close to the horizontal foundation; the switch solenoid valve (32) is fixedly mounted on the upper surface of one end of the front shell (11) close to the horizontal foundation; the water outlet of the dewatering device (31) is connected to the switch solenoid valve (32); and the air outlet of the dewatering device (31) is connected to the adsorption and desorption unit (4) by a pipeline.

4. A detection device for on-site analysis of volatile organic compounds in soil according to claim 3, Features: The adsorption and desorption unit (4) comprises a dual-path cold trap (41), a desorption pipe (42) and a ten-way membrane valve (43); the air inlet and the air outlet of the desorption pipe (42) are both connected to the ten-way membrane valve (43) pipeline; the dual-path cold trap (41) is fixedly mounted at one end of the front shell (11) away from the horizontal foundation; the desorption pipe (42) is fixedly mounted inside the dual-path cold trap (41); the desorption pipe (42) is composed of two quartz tubes, one of which is an empty tube and the other is filled with adsorption filler; a heating wire is wound around the outside of the desorption pipe (42); the ten-way membrane valve (43) is fixedly mounted on the front shell (11); the ten-way membrane valve (43) is fixedly mounted between the purge pipe (22) and the hydrogen flame ionization detector (51); and a chromatographic column is evenly wound around the surface of the ten-way membrane valve (43) and connected to the chromatographic column.

5. A detection device for on-site analysis of volatile organic compounds in soil according to claim 4, Features: The separation and detection unit (5) comprises a hydrogen flame ionization detector (51) and a chromatographic column (52), wherein the hydrogen flame ionization detector (51) is connected to the chromatographic column (52), wherein the hydrogen flame ionization detector (51) is fixedly mounted on an end of the front shell (11) away from the horizontal base, wherein an outlet of the hydrogen flame ionization detector (51) extends out of an outer surface of an end of the outer shell (13) away from the horizontal base, wherein the chromatographic column (52) is wound around the outside of a ten-way membrane valve (43), wherein the chromatographic column (52) comprises two, a capillary chromatographic column and a total hydrocarbon chromatographic column, and connects the ten-way membrane valve (43) and the hydrogen flame ionization detector (51).

6. A detection device for on-site analysis of volatile organic compounds in soil according to claim 2, Features: A powder filter is fixedly connected to one end of the purge pipe (22) close to the horizontal base, and the heating plate (23) is electrically connected to a temperature sensor.

7. A detection device for on-site analysis of volatile organic compounds in soil according to claim 1, Features: A temperature control meter (131), a power display (132) and a power switch (133) are provided on an outer surface of one side of the outer shell (13), and a fan (134) and a carrier gas inlet (135) are provided on an outer surface of the other side of the outer shell (13).

8. A detection method for on-site analysis of volatile organic compounds in soil, Features: The detection method for on-site analysis of volatile organic compounds in soil comprises the following steps: S1, sample loading; The step S1 comprises the following specific steps: S11, weighing the soil sample of the area to be tested, filling the sample into the purge tube and weighing it; S2, heating; The step S2 comprises the following specific steps: S21, heating the soil sample to volatilize the moisture and volatile organic matter in the soil into the carrier gas; S3, water removal and adsorption; The step S3 comprises the following specific steps: S31, the carrier gas is subjected to heat exchange and refrigeration to remove water twice, and the organic matter to be tested in the sample gas is adsorbed by the adsorption tube; S4, desorption and detection; The step S4 comprises the following specific steps: S41, heating the adsorption tube, desorbing the sample to be tested, and being carried to the chromatographic column by the carrier gas for detection, condensed water evaporates and is purged out of the system by the carrier gas, and the sample is separated in the chromatographic column and detected by FID; S42. After the test is completed, weigh the purge tube and calculate the moisture content.

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